Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * bufmgr.c
4 : : * buffer manager interface routines
5 : : *
6 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : : * Portions Copyright (c) 1994, Regents of the University of California
8 : : *
9 : : *
10 : : * IDENTIFICATION
11 : : * src/backend/storage/buffer/bufmgr.c
12 : : *
13 : : *-------------------------------------------------------------------------
14 : : */
15 : : /*
16 : : * Principal entry points:
17 : : *
18 : : * ReadBuffer() -- find or create a buffer holding the requested page,
19 : : * and pin it so that no one can destroy it while this process
20 : : * is using it.
21 : : *
22 : : * StartReadBuffer() -- as above, with separate wait step
23 : : * StartReadBuffers() -- multiple block version
24 : : * WaitReadBuffers() -- second step of above
25 : : *
26 : : * ReleaseBuffer() -- unpin a buffer
27 : : *
28 : : * MarkBufferDirty() -- mark a pinned buffer's contents as "dirty".
29 : : * The disk write is delayed until buffer replacement or checkpoint.
30 : : *
31 : : * See also these files:
32 : : * freelist.c -- chooses victim for buffer replacement
33 : : * buf_table.c -- manages the buffer lookup table
34 : : */
35 : : #include "postgres.h"
36 : :
37 : : #include <sys/file.h>
38 : : #include <unistd.h>
39 : :
40 : : #include "access/tableam.h"
41 : : #include "access/xloginsert.h"
42 : : #include "access/xlogutils.h"
43 : : #ifdef USE_ASSERT_CHECKING
44 : : #include "catalog/pg_tablespace_d.h"
45 : : #endif
46 : : #include "catalog/storage.h"
47 : : #include "catalog/storage_xlog.h"
48 : : #include "common/hashfn.h"
49 : : #include "executor/instrument.h"
50 : : #include "lib/binaryheap.h"
51 : : #include "miscadmin.h"
52 : : #include "pg_trace.h"
53 : : #include "pgstat.h"
54 : : #include "postmaster/bgwriter.h"
55 : : #include "storage/aio.h"
56 : : #include "storage/buf_internals.h"
57 : : #include "storage/bufmgr.h"
58 : : #include "storage/fd.h"
59 : : #include "storage/ipc.h"
60 : : #include "storage/lmgr.h"
61 : : #include "storage/proc.h"
62 : : #include "storage/proclist.h"
63 : : #include "storage/procsignal.h"
64 : : #include "storage/read_stream.h"
65 : : #include "storage/smgr.h"
66 : : #include "storage/standby.h"
67 : : #include "utils/memdebug.h"
68 : : #include "utils/ps_status.h"
69 : : #include "utils/rel.h"
70 : : #include "utils/resowner.h"
71 : : #include "utils/timestamp.h"
72 : : #include "utils/wait_event.h"
73 : :
74 : :
75 : : /* Note: these two macros only work on shared buffers, not local ones! */
76 : : #define BufHdrGetBlock(bufHdr) ((Block) (BufferBlocks + ((Size) (bufHdr)->buf_id) * BLCKSZ))
77 : : #define BufferGetLSN(bufHdr) (PageGetLSN(BufHdrGetBlock(bufHdr)))
78 : :
79 : : /* Note: this macro only works on local buffers, not shared ones! */
80 : : #define LocalBufHdrGetBlock(bufHdr) \
81 : : LocalBufferBlockPointers[-((bufHdr)->buf_id + 2)]
82 : :
83 : : /* Bits in SyncOneBuffer's return value */
84 : : #define BUF_WRITTEN 0x01
85 : : #define BUF_REUSABLE 0x02
86 : :
87 : : #define RELS_BSEARCH_THRESHOLD 20
88 : :
89 : : /*
90 : : * This is the size (in the number of blocks) above which we scan the
91 : : * entire buffer pool to remove the buffers for all the pages of relation
92 : : * being dropped. For the relations with size below this threshold, we find
93 : : * the buffers by doing lookups in BufMapping table.
94 : : */
95 : : #define BUF_DROP_FULL_SCAN_THRESHOLD (uint64) (NBuffers / 32)
96 : :
97 : : /*
98 : : * This is separated out from PrivateRefCountEntry to allow for copying all
99 : : * the data members via struct assignment.
100 : : */
101 : : typedef struct PrivateRefCountData
102 : : {
103 : : /*
104 : : * How many times has the buffer been pinned by this backend.
105 : : */
106 : : int32 refcount;
107 : :
108 : : /*
109 : : * Is the buffer locked by this backend? BUFFER_LOCK_UNLOCK indicates that
110 : : * the buffer is not locked.
111 : : */
112 : : BufferLockMode lockmode;
113 : : } PrivateRefCountData;
114 : :
115 : : typedef struct PrivateRefCountEntry
116 : : {
117 : : /*
118 : : * Note that this needs to be same as the entry's corresponding
119 : : * PrivateRefCountArrayKeys[i], if the entry is stored in the array. We
120 : : * store it in both places as this is used for the hashtable key and
121 : : * because it is more convenient (passing around a PrivateRefCountEntry
122 : : * suffices to identify the buffer) and faster (checking the keys array is
123 : : * faster when checking many entries, checking the entry is faster if just
124 : : * checking a single entry).
125 : : */
126 : : Buffer buffer;
127 : :
128 : : char status;
129 : :
130 : : PrivateRefCountData data;
131 : : } PrivateRefCountEntry;
132 : :
133 : : #define SH_PREFIX refcount
134 : : #define SH_ELEMENT_TYPE PrivateRefCountEntry
135 : : #define SH_KEY_TYPE Buffer
136 : : #define SH_KEY buffer
137 : : #define SH_HASH_KEY(tb, key) murmurhash32((uint32) (key))
138 : : #define SH_EQUAL(tb, a, b) ((a) == (b))
139 : : #define SH_SCOPE static inline
140 : : #define SH_DECLARE
141 : : #define SH_DEFINE
142 : : #include "lib/simplehash.h"
143 : :
144 : : /* 64 bytes, about the size of a cache line on common systems */
145 : : #define REFCOUNT_ARRAY_ENTRIES 8
146 : :
147 : : /*
148 : : * Status of buffers to checkpoint for a particular tablespace, used
149 : : * internally in BufferSync.
150 : : */
151 : : typedef struct CkptTsStatus
152 : : {
153 : : /* oid of the tablespace */
154 : : Oid tsId;
155 : :
156 : : /*
157 : : * Checkpoint progress for this tablespace. To make progress comparable
158 : : * between tablespaces the progress is, for each tablespace, measured as a
159 : : * number between 0 and the total number of to-be-checkpointed pages. Each
160 : : * page checkpointed in this tablespace increments this space's progress
161 : : * by progress_slice.
162 : : */
163 : : float8 progress;
164 : : float8 progress_slice;
165 : :
166 : : /* number of to-be checkpointed pages in this tablespace */
167 : : int num_to_scan;
168 : : /* already processed pages in this tablespace */
169 : : int num_scanned;
170 : :
171 : : /* current offset in CkptBufferIds for this tablespace */
172 : : int index;
173 : : } CkptTsStatus;
174 : :
175 : : /*
176 : : * Type for array used to sort SMgrRelations
177 : : *
178 : : * FlushRelationsAllBuffers shares the same comparator function with
179 : : * DropRelationsAllBuffers. Pointer to this struct and RelFileLocator must be
180 : : * compatible.
181 : : */
182 : : typedef struct SMgrSortArray
183 : : {
184 : : RelFileLocator rlocator; /* This must be the first member */
185 : : SMgrRelation srel;
186 : : } SMgrSortArray;
187 : :
188 : : /* GUC variables */
189 : : bool zero_damaged_pages = false;
190 : : int bgwriter_lru_maxpages = 100;
191 : : double bgwriter_lru_multiplier = 2.0;
192 : : bool track_io_timing = false;
193 : :
194 : : /*
195 : : * How many buffers PrefetchBuffer callers should try to stay ahead of their
196 : : * ReadBuffer calls by. Zero means "never prefetch". This value is only used
197 : : * for buffers not belonging to tablespaces that have their
198 : : * effective_io_concurrency parameter set.
199 : : */
200 : : int effective_io_concurrency = DEFAULT_EFFECTIVE_IO_CONCURRENCY;
201 : :
202 : : /*
203 : : * Like effective_io_concurrency, but used by maintenance code paths that might
204 : : * benefit from a higher setting because they work on behalf of many sessions.
205 : : * Overridden by the tablespace setting of the same name.
206 : : */
207 : : int maintenance_io_concurrency = DEFAULT_MAINTENANCE_IO_CONCURRENCY;
208 : :
209 : : /*
210 : : * Limit on how many blocks should be handled in single I/O operations.
211 : : * StartReadBuffers() callers should respect it, as should other operations
212 : : * that call smgr APIs directly. It is computed as the minimum of underlying
213 : : * GUCs io_combine_limit_guc and io_max_combine_limit.
214 : : */
215 : : int io_combine_limit = DEFAULT_IO_COMBINE_LIMIT;
216 : : int io_combine_limit_guc = DEFAULT_IO_COMBINE_LIMIT;
217 : : int io_max_combine_limit = DEFAULT_IO_COMBINE_LIMIT;
218 : :
219 : : /*
220 : : * GUC variables about triggering kernel writeback for buffers written; OS
221 : : * dependent defaults are set via the GUC mechanism.
222 : : */
223 : : int checkpoint_flush_after = DEFAULT_CHECKPOINT_FLUSH_AFTER;
224 : : int bgwriter_flush_after = DEFAULT_BGWRITER_FLUSH_AFTER;
225 : : int backend_flush_after = DEFAULT_BACKEND_FLUSH_AFTER;
226 : :
227 : : /* local state for LockBufferForCleanup */
228 : : static BufferDesc *PinCountWaitBuf = NULL;
229 : :
230 : : /*
231 : : * Backend-Private refcount management:
232 : : *
233 : : * Each buffer also has a private refcount that keeps track of the number of
234 : : * times the buffer is pinned in the current process. This is so that the
235 : : * shared refcount needs to be modified only once if a buffer is pinned more
236 : : * than once by an individual backend. It's also used to check that no
237 : : * buffers are still pinned at the end of transactions and when exiting. We
238 : : * also use this mechanism to track whether this backend has a buffer locked,
239 : : * and, if so, in what mode.
240 : : *
241 : : *
242 : : * To avoid - as we used to - requiring an array with NBuffers entries to keep
243 : : * track of local buffers, we use a small sequentially searched array
244 : : * (PrivateRefCountArrayKeys, with the corresponding data stored in
245 : : * PrivateRefCountArray) and an overflow hash table (PrivateRefCountHash) to
246 : : * keep track of backend local pins.
247 : : *
248 : : * Until no more than REFCOUNT_ARRAY_ENTRIES buffers are pinned at once, all
249 : : * refcounts are kept track of in the array; after that, new array entries
250 : : * displace old ones into the hash table. That way a frequently used entry
251 : : * can't get "stuck" in the hashtable while infrequent ones clog the array.
252 : : *
253 : : * Note that in most scenarios the number of pinned buffers will not exceed
254 : : * REFCOUNT_ARRAY_ENTRIES.
255 : : *
256 : : *
257 : : * To enter a buffer into the refcount tracking mechanism first reserve a free
258 : : * entry using ReservePrivateRefCountEntry() and then later, if necessary,
259 : : * fill it with NewPrivateRefCountEntry(). That split lets us avoid doing
260 : : * memory allocations in NewPrivateRefCountEntry() which can be important
261 : : * because in some scenarios it's called with a spinlock held...
262 : : */
263 : : static Buffer PrivateRefCountArrayKeys[REFCOUNT_ARRAY_ENTRIES];
264 : : static struct PrivateRefCountEntry PrivateRefCountArray[REFCOUNT_ARRAY_ENTRIES];
265 : : static refcount_hash *PrivateRefCountHash = NULL;
266 : : static int32 PrivateRefCountOverflowed = 0;
267 : : static uint32 PrivateRefCountClock = 0;
268 : : static int ReservedRefCountSlot = -1;
269 : : static int PrivateRefCountEntryLast = -1;
270 : :
271 : : static uint32 MaxProportionalPins;
272 : :
273 : : static void ReservePrivateRefCountEntry(void);
274 : : static PrivateRefCountEntry *NewPrivateRefCountEntry(Buffer buffer);
275 : : static PrivateRefCountEntry *GetPrivateRefCountEntry(Buffer buffer, bool do_move);
276 : : static inline int32 GetPrivateRefCount(Buffer buffer);
277 : : static void ForgetPrivateRefCountEntry(PrivateRefCountEntry *ref);
278 : :
279 : : /* ResourceOwner callbacks to hold in-progress I/Os and buffer pins */
280 : : static void ResOwnerReleaseBufferIO(Datum res);
281 : : static char *ResOwnerPrintBufferIO(Datum res);
282 : : static void ResOwnerReleaseBuffer(Datum res);
283 : : static char *ResOwnerPrintBuffer(Datum res);
284 : :
285 : : const ResourceOwnerDesc buffer_io_resowner_desc =
286 : : {
287 : : .name = "buffer io",
288 : : .release_phase = RESOURCE_RELEASE_BEFORE_LOCKS,
289 : : .release_priority = RELEASE_PRIO_BUFFER_IOS,
290 : : .ReleaseResource = ResOwnerReleaseBufferIO,
291 : : .DebugPrint = ResOwnerPrintBufferIO
292 : : };
293 : :
294 : : const ResourceOwnerDesc buffer_resowner_desc =
295 : : {
296 : : .name = "buffer",
297 : : .release_phase = RESOURCE_RELEASE_BEFORE_LOCKS,
298 : : .release_priority = RELEASE_PRIO_BUFFER_PINS,
299 : : .ReleaseResource = ResOwnerReleaseBuffer,
300 : : .DebugPrint = ResOwnerPrintBuffer
301 : : };
302 : :
303 : : /*
304 : : * Ensure that the PrivateRefCountArray has sufficient space to store one more
305 : : * entry. This has to be called before using NewPrivateRefCountEntry() to fill
306 : : * a new entry - but it's perfectly fine to not use a reserved entry.
307 : : */
308 : : static void
4124 andres@anarazel.de 309 :CBC 87715023 : ReservePrivateRefCountEntry(void)
310 : : {
311 : : /* Already reserved (or freed), nothing to do */
142 andres@anarazel.de 312 [ + + ]:GNC 87715023 : if (ReservedRefCountSlot != -1)
4124 andres@anarazel.de 313 :CBC 82719361 : return;
314 : :
315 : : /*
316 : : * First search for a free entry the array, that'll be sufficient in the
317 : : * majority of cases.
318 : : */
319 : : {
320 : : int i;
321 : :
322 [ + + ]: 44960958 : for (i = 0; i < REFCOUNT_ARRAY_ENTRIES; i++)
323 : : {
142 andres@anarazel.de 324 [ + + ]:GNC 39965296 : if (PrivateRefCountArrayKeys[i] == InvalidBuffer)
325 : : {
326 : 29070527 : ReservedRefCountSlot = i;
327 : :
328 : : /*
329 : : * We could return immediately, but iterating till the end of
330 : : * the array allows compiler-autovectorization.
331 : : */
332 : : }
333 : : }
334 : :
335 [ + + ]: 4995662 : if (ReservedRefCountSlot != -1)
336 : 4806727 : return;
337 : : }
338 : :
339 : : /*
340 : : * No luck. All array entries are full. Move one array entry into the hash
341 : : * table.
342 : : */
343 : : {
344 : : /*
345 : : * Move entry from the current clock position in the array into the
346 : : * hashtable. Use that slot.
347 : : */
348 : : int victim_slot;
349 : : PrivateRefCountEntry *victim_entry;
350 : : PrivateRefCountEntry *hashent;
351 : : bool found;
352 : :
353 : : /* select victim slot */
354 : 188935 : victim_slot = PrivateRefCountClock++ % REFCOUNT_ARRAY_ENTRIES;
355 : 188935 : victim_entry = &PrivateRefCountArray[victim_slot];
356 : 188935 : ReservedRefCountSlot = victim_slot;
357 : :
358 : : /* Better be used, otherwise we shouldn't get here. */
359 [ - + ]: 188935 : Assert(PrivateRefCountArrayKeys[victim_slot] != InvalidBuffer);
360 [ - + ]: 188935 : Assert(PrivateRefCountArray[victim_slot].buffer != InvalidBuffer);
361 [ - + ]: 188935 : Assert(PrivateRefCountArrayKeys[victim_slot] == PrivateRefCountArray[victim_slot].buffer);
362 : :
363 : : /* enter victim array entry into hashtable */
54 pg@bowt.ie 364 : 188935 : hashent = refcount_insert(PrivateRefCountHash,
365 : : PrivateRefCountArrayKeys[victim_slot],
366 : : &found);
4124 andres@anarazel.de 367 [ - + ]:CBC 188935 : Assert(!found);
368 : : /* move data from the entry in the array to the hash entry */
142 andres@anarazel.de 369 :GNC 188935 : hashent->data = victim_entry->data;
370 : :
371 : : /* clear the now free array slot */
372 : 188935 : PrivateRefCountArrayKeys[victim_slot] = InvalidBuffer;
373 : 188935 : victim_entry->buffer = InvalidBuffer;
374 : :
375 : : /* clear the whole data member, just for future proofing */
376 : 188935 : memset(&victim_entry->data, 0, sizeof(victim_entry->data));
377 : 188935 : victim_entry->data.refcount = 0;
110 378 : 188935 : victim_entry->data.lockmode = BUFFER_LOCK_UNLOCK;
379 : :
4124 andres@anarazel.de 380 :CBC 188935 : PrivateRefCountOverflowed++;
381 : : }
382 : : }
383 : :
384 : : /*
385 : : * Fill a previously reserved refcount entry.
386 : : */
387 : : static PrivateRefCountEntry *
388 : 76120912 : NewPrivateRefCountEntry(Buffer buffer)
389 : : {
390 : : PrivateRefCountEntry *res;
391 : :
392 : : /* only allowed to be called when a reservation has been made */
142 andres@anarazel.de 393 [ - + ]:GNC 76120912 : Assert(ReservedRefCountSlot != -1);
394 : :
395 : : /* use up the reserved entry */
396 : 76120912 : res = &PrivateRefCountArray[ReservedRefCountSlot];
397 : :
398 : : /* and fill it */
399 : 76120912 : PrivateRefCountArrayKeys[ReservedRefCountSlot] = buffer;
4124 andres@anarazel.de 400 :CBC 76120912 : res->buffer = buffer;
142 andres@anarazel.de 401 :GNC 76120912 : res->data.refcount = 0;
110 402 : 76120912 : res->data.lockmode = BUFFER_LOCK_UNLOCK;
403 : :
404 : : /* update cache for the next lookup */
142 405 : 76120912 : PrivateRefCountEntryLast = ReservedRefCountSlot;
406 : :
407 : 76120912 : ReservedRefCountSlot = -1;
408 : :
4124 andres@anarazel.de 409 :CBC 76120912 : return res;
410 : : }
411 : :
412 : : /*
413 : : * Slow-path for GetPrivateRefCountEntry(). This is big enough to not be worth
414 : : * inlining. This particularly seems to be true if the compiler is capable of
415 : : * auto-vectorizing the code, as that imposes additional stack-alignment
416 : : * requirements etc.
417 : : */
418 : : static pg_noinline PrivateRefCountEntry *
142 andres@anarazel.de 419 :GNC 126473464 : GetPrivateRefCountEntrySlow(Buffer buffer, bool do_move)
420 : : {
421 : : PrivateRefCountEntry *res;
422 : 126473464 : int match = -1;
423 : : int i;
424 : :
425 : : /*
426 : : * First search for references in the array, that'll be sufficient in the
427 : : * majority of cases.
428 : : */
4266 andres@anarazel.de 429 [ + + ]:CBC 1138261176 : for (i = 0; i < REFCOUNT_ARRAY_ENTRIES; i++)
430 : : {
142 andres@anarazel.de 431 [ + + ]:GNC 1011787712 : if (PrivateRefCountArrayKeys[i] == buffer)
432 : : {
433 : 51208336 : match = i;
434 : : /* see ReservePrivateRefCountEntry() for why we don't return */
435 : : }
436 : : }
437 : :
438 [ + + ]: 126473464 : if (likely(match != -1))
439 : : {
440 : : /* update cache for the next lookup */
441 : 51208336 : PrivateRefCountEntryLast = match;
442 : :
443 : 51208336 : return &PrivateRefCountArray[match];
444 : : }
445 : :
446 : : /*
447 : : * By here we know that the buffer, if already pinned, isn't residing in
448 : : * the array.
449 : : *
450 : : * Only look up the buffer in the hashtable if we've previously overflowed
451 : : * into it.
452 : : */
4124 andres@anarazel.de 453 [ + + ]:CBC 75265128 : if (PrivateRefCountOverflowed == 0)
454 : 73452443 : return NULL;
455 : :
54 pg@bowt.ie 456 :GNC 1812685 : res = refcount_lookup(PrivateRefCountHash, buffer);
457 : :
4124 andres@anarazel.de 458 [ + + ]:CBC 1812685 : if (res == NULL)
459 : 403887 : return NULL;
460 [ + + ]: 1408798 : else if (!do_move)
461 : : {
462 : : /* caller doesn't want us to move the hash entry into the array */
463 : 1311987 : return res;
464 : : }
465 : : else
466 : : {
467 : : /* move buffer from hashtable into the free array slot */
468 : : PrivateRefCountEntry *free;
469 : : PrivateRefCountData data;
470 : :
471 : : /* Save data and delete from hashtable while res is still valid */
54 pg@bowt.ie 472 :GNC 96811 : data = res->data;
473 : 96811 : refcount_delete_item(PrivateRefCountHash, res);
474 [ - + ]: 96811 : Assert(PrivateRefCountOverflowed > 0);
475 : 96811 : PrivateRefCountOverflowed--;
476 : :
477 : : /* Ensure there's a free array slot */
4124 andres@anarazel.de 478 :CBC 96811 : ReservePrivateRefCountEntry();
479 : :
480 : : /* Use up the reserved slot */
142 andres@anarazel.de 481 [ - + ]:GNC 96811 : Assert(ReservedRefCountSlot != -1);
482 : 96811 : free = &PrivateRefCountArray[ReservedRefCountSlot];
483 [ - + ]: 96811 : Assert(PrivateRefCountArrayKeys[ReservedRefCountSlot] == free->buffer);
4124 andres@anarazel.de 484 [ - + ]:CBC 96811 : Assert(free->buffer == InvalidBuffer);
485 : :
486 : : /* and fill it */
487 : 96811 : free->buffer = buffer;
54 pg@bowt.ie 488 :GNC 96811 : free->data = data;
142 andres@anarazel.de 489 : 96811 : PrivateRefCountArrayKeys[ReservedRefCountSlot] = buffer;
490 : : /* update cache for the next lookup */
55 491 : 96811 : PrivateRefCountEntryLast = ReservedRefCountSlot;
492 : :
142 493 : 96811 : ReservedRefCountSlot = -1;
494 : :
4124 andres@anarazel.de 495 :CBC 96811 : return free;
496 : : }
497 : : }
498 : :
499 : : /*
500 : : * Return the PrivateRefCount entry for the passed buffer.
501 : : *
502 : : * Returns NULL if a buffer doesn't have a refcount entry. Otherwise, if
503 : : * do_move is true, and the entry resides in the hashtable the entry is
504 : : * optimized for frequent access by moving it to the array.
505 : : */
506 : : static inline PrivateRefCountEntry *
142 andres@anarazel.de 507 :GNC 1323790495 : GetPrivateRefCountEntry(Buffer buffer, bool do_move)
508 : : {
509 [ - + ]: 1323790495 : Assert(BufferIsValid(buffer));
510 [ - + ]: 1323790495 : Assert(!BufferIsLocal(buffer));
511 : :
512 : : /*
513 : : * It's very common to look up the same buffer repeatedly. To make that
514 : : * fast, we have a one-entry cache.
515 : : *
516 : : * In contrast to the loop in GetPrivateRefCountEntrySlow(), here it
517 : : * faster to check PrivateRefCountArray[].buffer, as in the case of a hit
518 : : * fewer addresses are computed and fewer cachelines are accessed. Whereas
519 : : * in GetPrivateRefCountEntrySlow()'s case, checking
520 : : * PrivateRefCountArrayKeys saves a lot of memory accesses.
521 : : */
522 [ + + ]: 1323790495 : if (likely(PrivateRefCountEntryLast != -1) &&
523 [ + + ]: 1323775235 : likely(PrivateRefCountArray[PrivateRefCountEntryLast].buffer == buffer))
524 : : {
525 : 1197317031 : return &PrivateRefCountArray[PrivateRefCountEntryLast];
526 : : }
527 : :
528 : : /*
529 : : * The code for the cached lookup is small enough to be worth inlining
530 : : * into the caller. In the miss case however, that empirically doesn't
531 : : * seem worth it.
532 : : */
533 : 126473464 : return GetPrivateRefCountEntrySlow(buffer, do_move);
534 : : }
535 : :
536 : : /*
537 : : * Returns how many times the passed buffer is pinned by this backend.
538 : : *
539 : : * Only works for shared memory buffers!
540 : : */
541 : : static inline int32
4266 andres@anarazel.de 542 :CBC 721724984 : GetPrivateRefCount(Buffer buffer)
543 : : {
544 : : PrivateRefCountEntry *ref;
545 : :
546 [ - + ]: 721724984 : Assert(BufferIsValid(buffer));
547 [ - + ]: 721724984 : Assert(!BufferIsLocal(buffer));
548 : :
549 : : /*
550 : : * Not moving the entry - that's ok for the current users, but we might
551 : : * want to change this one day.
552 : : */
4124 553 : 721724984 : ref = GetPrivateRefCountEntry(buffer, false);
554 : :
4266 555 [ + + ]: 721724984 : if (ref == NULL)
556 : 50 : return 0;
142 andres@anarazel.de 557 :GNC 721724934 : return ref->data.refcount;
558 : : }
559 : :
560 : : /*
561 : : * Release resources used to track the reference count of a buffer which we no
562 : : * longer have pinned and don't want to pin again immediately.
563 : : */
564 : : static void
4266 andres@anarazel.de 565 :CBC 76120912 : ForgetPrivateRefCountEntry(PrivateRefCountEntry *ref)
566 : : {
142 andres@anarazel.de 567 [ - + ]:GNC 76120912 : Assert(ref->data.refcount == 0);
110 568 [ - + ]: 76120912 : Assert(ref->data.lockmode == BUFFER_LOCK_UNLOCK);
569 : :
4266 andres@anarazel.de 570 [ + - + + ]:CBC 76120912 : if (ref >= &PrivateRefCountArray[0] &&
571 : : ref < &PrivateRefCountArray[REFCOUNT_ARRAY_ENTRIES])
572 : : {
573 : 76028788 : ref->buffer = InvalidBuffer;
142 andres@anarazel.de 574 :GNC 76028788 : PrivateRefCountArrayKeys[ref - PrivateRefCountArray] = InvalidBuffer;
575 : :
576 : :
577 : : /*
578 : : * Mark the just used entry as reserved - in many scenarios that
579 : : * allows us to avoid ever having to search the array/hash for free
580 : : * entries.
581 : : */
582 : 76028788 : ReservedRefCountSlot = ref - PrivateRefCountArray;
583 : : }
584 : : else
585 : : {
54 pg@bowt.ie 586 : 92124 : refcount_delete_item(PrivateRefCountHash, ref);
4266 andres@anarazel.de 587 [ - + ]:CBC 92124 : Assert(PrivateRefCountOverflowed > 0);
588 : 92124 : PrivateRefCountOverflowed--;
589 : : }
590 : 76120912 : }
591 : :
592 : : /*
593 : : * BufferIsPinned
594 : : * True iff the buffer is pinned (also checks for valid buffer number).
595 : : *
596 : : * NOTE: what we check here is that *this* backend holds a pin on
597 : : * the buffer. We do not care whether some other backend does.
598 : : */
599 : : #define BufferIsPinned(bufnum) \
600 : : ( \
601 : : !BufferIsValid(bufnum) ? \
602 : : false \
603 : : : \
604 : : BufferIsLocal(bufnum) ? \
605 : : (LocalRefCount[-(bufnum) - 1] > 0) \
606 : : : \
607 : : (GetPrivateRefCount(bufnum) > 0) \
608 : : )
609 : :
610 : :
611 : : static Buffer ReadBuffer_common(Relation rel,
612 : : SMgrRelation smgr, char smgr_persistence,
613 : : ForkNumber forkNum, BlockNumber blockNum,
614 : : ReadBufferMode mode, BufferAccessStrategy strategy);
615 : : static BlockNumber ExtendBufferedRelCommon(BufferManagerRelation bmr,
616 : : ForkNumber fork,
617 : : BufferAccessStrategy strategy,
618 : : uint32 flags,
619 : : uint32 extend_by,
620 : : BlockNumber extend_upto,
621 : : Buffer *buffers,
622 : : uint32 *extended_by);
623 : : static BlockNumber ExtendBufferedRelShared(BufferManagerRelation bmr,
624 : : ForkNumber fork,
625 : : BufferAccessStrategy strategy,
626 : : uint32 flags,
627 : : uint32 extend_by,
628 : : BlockNumber extend_upto,
629 : : Buffer *buffers,
630 : : uint32 *extended_by);
631 : : static bool PinBuffer(BufferDesc *buf, BufferAccessStrategy strategy,
632 : : bool skip_if_not_valid);
633 : : static void PinBuffer_Locked(BufferDesc *buf);
634 : : static void UnpinBuffer(BufferDesc *buf);
635 : : static void UnpinBufferNoOwner(BufferDesc *buf);
636 : : static void BufferSync(int flags);
637 : : static int SyncOneBuffer(int buf_id, bool skip_recently_used,
638 : : WritebackContext *wb_context);
639 : : static void WaitIO(BufferDesc *buf);
640 : : static void AbortBufferIO(Buffer buffer);
641 : : static void shared_buffer_write_error_callback(void *arg);
642 : : static void local_buffer_write_error_callback(void *arg);
643 : : static inline BufferDesc *BufferAlloc(SMgrRelation smgr,
644 : : char relpersistence,
645 : : ForkNumber forkNum,
646 : : BlockNumber blockNum,
647 : : BufferAccessStrategy strategy,
648 : : bool *foundPtr, IOContext io_context);
649 : : static bool AsyncReadBuffers(ReadBuffersOperation *operation, int *nblocks_progress);
650 : : static void CheckReadBuffersOperation(ReadBuffersOperation *operation, bool is_complete);
651 : :
652 : : static pg_attribute_always_inline void TrackBufferHit(IOObject io_object,
653 : : IOContext io_context,
654 : : Relation rel, char persistence, SMgrRelation smgr,
655 : : ForkNumber forknum, BlockNumber blocknum);
656 : : static Buffer GetVictimBuffer(BufferAccessStrategy strategy, IOContext io_context);
657 : : static void FlushUnlockedBuffer(BufferDesc *buf, SMgrRelation reln,
658 : : IOObject io_object, IOContext io_context);
659 : : static void FlushBuffer(BufferDesc *buf, SMgrRelation reln,
660 : : IOObject io_object, IOContext io_context);
661 : : static void FindAndDropRelationBuffers(RelFileLocator rlocator,
662 : : ForkNumber forkNum,
663 : : BlockNumber nForkBlock,
664 : : BlockNumber firstDelBlock);
665 : : static void RelationCopyStorageUsingBuffer(RelFileLocator srclocator,
666 : : RelFileLocator dstlocator,
667 : : ForkNumber forkNum, bool permanent);
668 : : static void AtProcExit_Buffers(int code, Datum arg);
669 : : static void CheckForBufferLeaks(void);
670 : : #ifdef USE_ASSERT_CHECKING
671 : : static void AssertNotCatalogBufferLock(Buffer buffer, BufferLockMode mode);
672 : : #endif
673 : : static int rlocator_comparator(const void *p1, const void *p2);
674 : : static inline int buffertag_comparator(const BufferTag *ba, const BufferTag *bb);
675 : : static inline int ckpt_buforder_comparator(const CkptSortItem *a, const CkptSortItem *b);
676 : : static int ts_ckpt_progress_comparator(Datum a, Datum b, void *arg);
677 : :
678 : : static void BufferLockAcquire(Buffer buffer, BufferDesc *buf_hdr, BufferLockMode mode);
679 : : static void BufferLockUnlock(Buffer buffer, BufferDesc *buf_hdr);
680 : : static bool BufferLockConditional(Buffer buffer, BufferDesc *buf_hdr, BufferLockMode mode);
681 : : static bool BufferLockHeldByMeInMode(BufferDesc *buf_hdr, BufferLockMode mode);
682 : : static bool BufferLockHeldByMe(BufferDesc *buf_hdr);
683 : : static inline void BufferLockDisown(Buffer buffer, BufferDesc *buf_hdr);
684 : : static inline int BufferLockDisownInternal(Buffer buffer, BufferDesc *buf_hdr);
685 : : static inline bool BufferLockAttempt(BufferDesc *buf_hdr, BufferLockMode mode);
686 : : static void BufferLockQueueSelf(BufferDesc *buf_hdr, BufferLockMode mode);
687 : : static void BufferLockDequeueSelf(BufferDesc *buf_hdr);
688 : : static void BufferLockWakeup(BufferDesc *buf_hdr, bool wake_exclusive);
689 : : static void BufferLockProcessRelease(BufferDesc *buf_hdr, BufferLockMode mode, uint64 lockstate);
690 : : static inline uint64 BufferLockReleaseSub(BufferLockMode mode);
691 : :
692 : :
693 : : /*
694 : : * Implementation of PrefetchBuffer() for shared buffers.
695 : : */
696 : : PrefetchBufferResult
2218 tmunro@postgresql.or 697 : 40401 : PrefetchSharedBuffer(SMgrRelation smgr_reln,
698 : : ForkNumber forkNum,
699 : : BlockNumber blockNum)
700 : : {
701 : 40401 : PrefetchBufferResult result = {InvalidBuffer, false};
702 : : BufferTag newTag; /* identity of requested block */
703 : : uint32 newHash; /* hash value for newTag */
704 : : LWLock *newPartitionLock; /* buffer partition lock for it */
705 : : int buf_id;
706 : :
707 [ - + ]: 40401 : Assert(BlockNumberIsValid(blockNum));
708 : :
709 : : /* create a tag so we can lookup the buffer */
1378 rhaas@postgresql.org 710 : 40401 : InitBufferTag(&newTag, &smgr_reln->smgr_rlocator.locator,
711 : : forkNum, blockNum);
712 : :
713 : : /* determine its hash code and partition lock ID */
2218 tmunro@postgresql.or 714 : 40401 : newHash = BufTableHashCode(&newTag);
715 : 40401 : newPartitionLock = BufMappingPartitionLock(newHash);
716 : :
717 : : /* see if the block is in the buffer pool already */
718 : 40401 : LWLockAcquire(newPartitionLock, LW_SHARED);
719 : 40401 : buf_id = BufTableLookup(&newTag, newHash);
720 : 40401 : LWLockRelease(newPartitionLock);
721 : :
722 : : /* If not in buffers, initiate prefetch */
723 [ + + ]: 40401 : if (buf_id < 0)
724 : : {
725 : : #ifdef USE_PREFETCH
726 : : /*
727 : : * Try to initiate an asynchronous read. This returns false in
728 : : * recovery if the relation file doesn't exist.
729 : : */
1123 730 [ + + + - ]: 18483 : if ((io_direct_flags & IO_DIRECT_DATA) == 0 &&
871 731 : 9115 : smgrprefetch(smgr_reln, forkNum, blockNum, 1))
732 : : {
2218 733 : 9115 : result.initiated_io = true;
734 : : }
735 : : #endif /* USE_PREFETCH */
736 : : }
737 : : else
738 : : {
739 : : /*
740 : : * Report the buffer it was in at that time. The caller may be able
741 : : * to avoid a buffer table lookup, but it's not pinned and it must be
742 : : * rechecked!
743 : : */
744 : 31033 : result.recent_buffer = buf_id + 1;
745 : : }
746 : :
747 : : /*
748 : : * If the block *is* in buffers, we do nothing. This is not really ideal:
749 : : * the block might be just about to be evicted, which would be stupid
750 : : * since we know we are going to need it soon. But the only easy answer
751 : : * is to bump the usage_count, which does not seem like a great solution:
752 : : * when the caller does ultimately touch the block, usage_count would get
753 : : * bumped again, resulting in too much favoritism for blocks that are
754 : : * involved in a prefetch sequence. A real fix would involve some
755 : : * additional per-buffer state, and it's not clear that there's enough of
756 : : * a problem to justify that.
757 : : */
758 : :
759 : 40401 : return result;
760 : : }
761 : :
762 : : /*
763 : : * PrefetchBuffer -- initiate asynchronous read of a block of a relation
764 : : *
765 : : * This is named by analogy to ReadBuffer but doesn't actually allocate a
766 : : * buffer. Instead it tries to ensure that a future ReadBuffer for the given
767 : : * block will not be delayed by the I/O. Prefetching is optional.
768 : : *
769 : : * There are three possible outcomes:
770 : : *
771 : : * 1. If the block is already cached, the result includes a valid buffer that
772 : : * could be used by the caller to avoid the need for a later buffer lookup, but
773 : : * it's not pinned, so the caller must recheck it.
774 : : *
775 : : * 2. If the kernel has been asked to initiate I/O, the initiated_io member is
776 : : * true. Currently there is no way to know if the data was already cached by
777 : : * the kernel and therefore didn't really initiate I/O, and no way to know when
778 : : * the I/O completes other than using synchronous ReadBuffer().
779 : : *
780 : : * 3. Otherwise, the buffer wasn't already cached by PostgreSQL, and
781 : : * USE_PREFETCH is not defined (this build doesn't support prefetching due to
782 : : * lack of a kernel facility), direct I/O is enabled, or the underlying
783 : : * relation file wasn't found and we are in recovery. (If the relation file
784 : : * wasn't found and we are not in recovery, an error is raised).
785 : : */
786 : : PrefetchBufferResult
6322 tgl@sss.pgh.pa.us 787 : 29833 : PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum)
788 : : {
789 [ - + ]: 29833 : Assert(RelationIsValid(reln));
790 [ - + ]: 29833 : Assert(BlockNumberIsValid(blockNum));
791 : :
5622 rhaas@postgresql.org 792 [ + + ]: 29833 : if (RelationUsesLocalBuffers(reln))
793 : : {
794 : : /* see comments in ReadBufferExtended */
6244 tgl@sss.pgh.pa.us 795 [ + - - + ]: 1535 : if (RELATION_IS_OTHER_TEMP(reln))
6244 tgl@sss.pgh.pa.us 796 [ # # ]:UBC 0 : ereport(ERROR,
797 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
798 : : errmsg("cannot access temporary tables of other sessions")));
799 : :
800 : : /* pass it off to localbuf.c */
1758 tgl@sss.pgh.pa.us 801 :CBC 1535 : return PrefetchLocalBuffer(RelationGetSmgr(reln), forkNum, blockNum);
802 : : }
803 : : else
804 : : {
805 : : /* pass it to the shared buffer version */
806 : 28298 : return PrefetchSharedBuffer(RelationGetSmgr(reln), forkNum, blockNum);
807 : : }
808 : : }
809 : :
810 : : /*
811 : : * ReadRecentBuffer -- try to pin a block in a recently observed buffer
812 : : *
813 : : * Compared to ReadBuffer(), this avoids a buffer mapping lookup when it's
814 : : * successful. Return true if the buffer is valid and still has the expected
815 : : * tag. In that case, the buffer is pinned and the usage count is bumped.
816 : : */
817 : : bool
1399 rhaas@postgresql.org 818 : 5045 : ReadRecentBuffer(RelFileLocator rlocator, ForkNumber forkNum, BlockNumber blockNum,
819 : : Buffer recent_buffer)
820 : : {
821 : : BufferDesc *bufHdr;
822 : : BufferTag tag;
823 : : uint64 buf_state;
824 : :
1853 tmunro@postgresql.or 825 [ - + ]: 5045 : Assert(BufferIsValid(recent_buffer));
826 : :
909 heikki.linnakangas@i 827 : 5045 : ResourceOwnerEnlarge(CurrentResourceOwner);
1853 tmunro@postgresql.or 828 : 5045 : ReservePrivateRefCountEntry();
1378 rhaas@postgresql.org 829 : 5045 : InitBufferTag(&tag, &rlocator, forkNum, blockNum);
830 : :
1853 tmunro@postgresql.or 831 [ + + ]: 5045 : if (BufferIsLocal(recent_buffer))
832 : : {
1380 heikki.linnakangas@i 833 : 210 : int b = -recent_buffer - 1;
834 : :
835 : 210 : bufHdr = GetLocalBufferDescriptor(b);
110 andres@anarazel.de 836 :GNC 210 : buf_state = pg_atomic_read_u64(&bufHdr->state);
837 : :
838 : : /* Is it still valid and holding the right tag? */
1378 rhaas@postgresql.org 839 [ + - + - ]:CBC 210 : if ((buf_state & BM_VALID) && BufferTagsEqual(&tag, &bufHdr->tag))
840 : : {
1126 andres@anarazel.de 841 : 210 : PinLocalBuffer(bufHdr, true);
842 : :
1489 tmunro@postgresql.or 843 : 210 : pgBufferUsage.local_blks_hit++;
844 : :
1853 845 : 210 : return true;
846 : : }
847 : : }
848 : : else
849 : : {
850 : 4835 : bufHdr = GetBufferDescriptor(recent_buffer - 1);
851 : :
852 : : /*
853 : : * Is it still valid and holding the right tag? We do an unlocked tag
854 : : * comparison first, to make it unlikely that we'll increment the
855 : : * usage counter of the wrong buffer, if someone calls us with a very
856 : : * out of date recent_buffer. Then we'll check it again if we get the
857 : : * pin.
858 : : */
209 andres@anarazel.de 859 [ + + + + ]:GNC 9622 : if (BufferTagsEqual(&tag, &bufHdr->tag) &&
860 : 4787 : PinBuffer(bufHdr, NULL, true))
861 : : {
862 [ + - ]: 4778 : if (BufferTagsEqual(&tag, &bufHdr->tag))
863 : : {
864 : 4778 : pgBufferUsage.shared_blks_hit++;
865 : 4778 : return true;
866 : : }
209 andres@anarazel.de 867 :UNC 0 : UnpinBuffer(bufHdr);
868 : : }
869 : : }
870 : :
1853 tmunro@postgresql.or 871 :CBC 57 : return false;
872 : : }
873 : :
874 : : /*
875 : : * ReadBuffer -- a shorthand for ReadBufferExtended, for reading from main
876 : : * fork with RBM_NORMAL mode and default strategy.
877 : : */
878 : : Buffer
6395 heikki.linnakangas@i 879 : 62975583 : ReadBuffer(Relation reln, BlockNumber blockNum)
880 : : {
881 : 62975583 : return ReadBufferExtended(reln, MAIN_FORKNUM, blockNum, RBM_NORMAL, NULL);
882 : : }
883 : :
884 : : /*
885 : : * ReadBufferExtended -- returns a buffer containing the requested
886 : : * block of the requested relation. If the blknum
887 : : * requested is P_NEW, extend the relation file and
888 : : * allocate a new block. (Caller is responsible for
889 : : * ensuring that only one backend tries to extend a
890 : : * relation at the same time!)
891 : : *
892 : : * Returns: the buffer number for the buffer containing
893 : : * the block read. The returned buffer has been pinned.
894 : : * Does not return on error --- elog's instead.
895 : : *
896 : : * Assume when this function is called, that reln has been opened already.
897 : : *
898 : : * In RBM_NORMAL mode, the page is read from disk, and the page header is
899 : : * validated. An error is thrown if the page header is not valid. (But
900 : : * note that an all-zero page is considered "valid"; see
901 : : * PageIsVerified().)
902 : : *
903 : : * RBM_ZERO_ON_ERROR is like the normal mode, but if the page header is not
904 : : * valid, the page is zeroed instead of throwing an error. This is intended
905 : : * for non-critical data, where the caller is prepared to repair errors.
906 : : *
907 : : * In RBM_ZERO_AND_LOCK mode, if the page isn't in buffer cache already, it's
908 : : * filled with zeros instead of reading it from disk. Useful when the caller
909 : : * is going to fill the page from scratch, since this saves I/O and avoids
910 : : * unnecessary failure if the page-on-disk has corrupt page headers.
911 : : * The page is returned locked to ensure that the caller has a chance to
912 : : * initialize the page before it's made visible to others.
913 : : * Caution: do not use this mode to read a page that is beyond the relation's
914 : : * current physical EOF; that is likely to cause problems in md.c when
915 : : * the page is modified and written out. P_NEW is OK, though.
916 : : *
917 : : * RBM_ZERO_AND_CLEANUP_LOCK is the same as RBM_ZERO_AND_LOCK, but acquires
918 : : * a cleanup-strength lock on the page.
919 : : *
920 : : * RBM_NORMAL_NO_LOG mode is treated the same as RBM_NORMAL here.
921 : : *
922 : : * If strategy is not NULL, a nondefault buffer access strategy is used.
923 : : * See buffer/README for details.
924 : : */
925 : : inline Buffer
926 : 74155377 : ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum,
927 : : ReadBufferMode mode, BufferAccessStrategy strategy)
928 : : {
929 : : Buffer buf;
930 : :
931 : : /*
932 : : * Reject attempts to read non-local temporary relations; we would be
933 : : * likely to get wrong data since we have no visibility into the owning
934 : : * session's local buffers.
935 : : */
6244 tgl@sss.pgh.pa.us 936 [ + + - + ]: 74155377 : if (RELATION_IS_OTHER_TEMP(reln))
6244 tgl@sss.pgh.pa.us 937 [ # # ]:UBC 0 : ereport(ERROR,
938 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
939 : : errmsg("cannot access temporary tables of other sessions")));
940 : :
941 : : /*
942 : : * Read the buffer, and update pgstat counters to reflect a cache hit or
943 : : * miss.
944 : : */
762 tmunro@postgresql.or 945 :CBC 74155377 : buf = ReadBuffer_common(reln, RelationGetSmgr(reln), 0,
946 : : forkNum, blockNum, mode, strategy);
947 : :
6536 heikki.linnakangas@i 948 : 74155350 : return buf;
949 : : }
950 : :
951 : :
952 : : /*
953 : : * ReadBufferWithoutRelcache -- like ReadBufferExtended, but doesn't require
954 : : * a relcache entry for the relation.
955 : : *
956 : : * Pass permanent = true for a RELPERSISTENCE_PERMANENT relation, and
957 : : * permanent = false for a RELPERSISTENCE_UNLOGGED relation. This function
958 : : * cannot be used for temporary relations (and making that work might be
959 : : * difficult, unless we only want to read temporary relations for our own
960 : : * ProcNumber).
961 : : */
962 : : Buffer
1399 rhaas@postgresql.org 963 : 5965385 : ReadBufferWithoutRelcache(RelFileLocator rlocator, ForkNumber forkNum,
964 : : BlockNumber blockNum, ReadBufferMode mode,
965 : : BufferAccessStrategy strategy, bool permanent)
966 : : {
793 heikki.linnakangas@i 967 : 5965385 : SMgrRelation smgr = smgropen(rlocator, INVALID_PROC_NUMBER);
968 : :
762 tmunro@postgresql.or 969 [ + - ]: 5965385 : return ReadBuffer_common(NULL, smgr,
970 : : permanent ? RELPERSISTENCE_PERMANENT : RELPERSISTENCE_UNLOGGED,
971 : : forkNum, blockNum,
972 : : mode, strategy);
973 : : }
974 : :
975 : : /*
976 : : * Convenience wrapper around ExtendBufferedRelBy() extending by one block.
977 : : */
978 : : Buffer
986 979 : 57426 : ExtendBufferedRel(BufferManagerRelation bmr,
980 : : ForkNumber forkNum,
981 : : BufferAccessStrategy strategy,
982 : : uint32 flags)
983 : : {
984 : : Buffer buf;
1126 andres@anarazel.de 985 : 57426 : uint32 extend_by = 1;
986 : :
986 tmunro@postgresql.or 987 : 57426 : ExtendBufferedRelBy(bmr, forkNum, strategy, flags, extend_by,
988 : : &buf, &extend_by);
989 : :
1126 andres@anarazel.de 990 : 57426 : return buf;
991 : : }
992 : :
993 : : /*
994 : : * Extend relation by multiple blocks.
995 : : *
996 : : * Tries to extend the relation by extend_by blocks. Depending on the
997 : : * availability of resources the relation may end up being extended by a
998 : : * smaller number of pages (unless an error is thrown, always by at least one
999 : : * page). *extended_by is updated to the number of pages the relation has been
1000 : : * extended to.
1001 : : *
1002 : : * buffers needs to be an array that is at least extend_by long. Upon
1003 : : * completion, the first extend_by array elements will point to a pinned
1004 : : * buffer.
1005 : : *
1006 : : * If EB_LOCK_FIRST is part of flags, the first returned buffer is
1007 : : * locked. This is useful for callers that want a buffer that is guaranteed to
1008 : : * be empty.
1009 : : */
1010 : : BlockNumber
986 tmunro@postgresql.or 1011 : 210224 : ExtendBufferedRelBy(BufferManagerRelation bmr,
1012 : : ForkNumber fork,
1013 : : BufferAccessStrategy strategy,
1014 : : uint32 flags,
1015 : : uint32 extend_by,
1016 : : Buffer *buffers,
1017 : : uint32 *extended_by)
1018 : : {
1019 [ - + ]: 210224 : Assert((bmr.rel != NULL) != (bmr.smgr != NULL));
196 alvherre@kurilemu.de 1020 [ - + - - ]:GNC 210224 : Assert(bmr.smgr == NULL || bmr.relpersistence != '\0');
1126 andres@anarazel.de 1021 [ - + ]:CBC 210224 : Assert(extend_by > 0);
1022 : :
196 alvherre@kurilemu.de 1023 [ + - ]:GNC 210224 : if (bmr.relpersistence == '\0')
986 tmunro@postgresql.or 1024 :CBC 210224 : bmr.relpersistence = bmr.rel->rd_rel->relpersistence;
1025 : :
1026 : 210224 : return ExtendBufferedRelCommon(bmr, fork, strategy, flags,
1027 : : extend_by, InvalidBlockNumber,
1028 : : buffers, extended_by);
1029 : : }
1030 : :
1031 : : /*
1032 : : * Extend the relation so it is at least extend_to blocks large, return buffer
1033 : : * (extend_to - 1).
1034 : : *
1035 : : * This is useful for callers that want to write a specific page, regardless
1036 : : * of the current size of the relation (e.g. useful for visibilitymap and for
1037 : : * crash recovery).
1038 : : */
1039 : : Buffer
1040 : 55973 : ExtendBufferedRelTo(BufferManagerRelation bmr,
1041 : : ForkNumber fork,
1042 : : BufferAccessStrategy strategy,
1043 : : uint32 flags,
1044 : : BlockNumber extend_to,
1045 : : ReadBufferMode mode)
1046 : : {
1047 : : BlockNumber current_size;
1126 andres@anarazel.de 1048 : 55973 : uint32 extended_by = 0;
1049 : 55973 : Buffer buffer = InvalidBuffer;
1050 : : Buffer buffers[64];
1051 : :
986 tmunro@postgresql.or 1052 [ - + ]: 55973 : Assert((bmr.rel != NULL) != (bmr.smgr != NULL));
196 alvherre@kurilemu.de 1053 [ + + - + ]:GNC 55973 : Assert(bmr.smgr == NULL || bmr.relpersistence != '\0');
1126 andres@anarazel.de 1054 [ + - - + ]:CBC 55973 : Assert(extend_to != InvalidBlockNumber && extend_to > 0);
1055 : :
196 alvherre@kurilemu.de 1056 [ + + ]:GNC 55973 : if (bmr.relpersistence == '\0')
986 tmunro@postgresql.or 1057 :CBC 9452 : bmr.relpersistence = bmr.rel->rd_rel->relpersistence;
1058 : :
1059 : : /*
1060 : : * If desired, create the file if it doesn't exist. If
1061 : : * smgr_cached_nblocks[fork] is positive then it must exist, no need for
1062 : : * an smgrexists call.
1063 : : */
1126 andres@anarazel.de 1064 [ + + ]: 55973 : if ((flags & EB_CREATE_FORK_IF_NEEDED) &&
196 alvherre@kurilemu.de 1065 [ + - + + ]:GNC 9452 : (BMR_GET_SMGR(bmr)->smgr_cached_nblocks[fork] == 0 ||
1066 [ + - - + ]: 33 : BMR_GET_SMGR(bmr)->smgr_cached_nblocks[fork] == InvalidBlockNumber) &&
1067 [ + - + + ]: 9419 : !smgrexists(BMR_GET_SMGR(bmr), fork))
1068 : : {
986 tmunro@postgresql.or 1069 :CBC 9382 : LockRelationForExtension(bmr.rel, ExclusiveLock);
1070 : :
1071 : : /* recheck, fork might have been created concurrently */
196 alvherre@kurilemu.de 1072 [ + - + + ]:GNC 9382 : if (!smgrexists(BMR_GET_SMGR(bmr), fork))
1073 [ + - ]: 9379 : smgrcreate(BMR_GET_SMGR(bmr), fork, flags & EB_PERFORMING_RECOVERY);
1074 : :
986 tmunro@postgresql.or 1075 :CBC 9382 : UnlockRelationForExtension(bmr.rel, ExclusiveLock);
1076 : : }
1077 : :
1078 : : /*
1079 : : * If requested, invalidate size cache, so that smgrnblocks asks the
1080 : : * kernel.
1081 : : */
1126 andres@anarazel.de 1082 [ + + ]: 55973 : if (flags & EB_CLEAR_SIZE_CACHE)
196 alvherre@kurilemu.de 1083 [ + - ]:GNC 9452 : BMR_GET_SMGR(bmr)->smgr_cached_nblocks[fork] = InvalidBlockNumber;
1084 : :
1085 : : /*
1086 : : * Estimate how many pages we'll need to extend by. This avoids acquiring
1087 : : * unnecessarily many victim buffers.
1088 : : */
1089 [ + + ]: 55973 : current_size = smgrnblocks(BMR_GET_SMGR(bmr), fork);
1090 : :
1091 : : /*
1092 : : * Since no-one else can be looking at the page contents yet, there is no
1093 : : * difference between an exclusive lock and a cleanup-strength lock. Note
1094 : : * that we pass the original mode to ReadBuffer_common() below, when
1095 : : * falling back to reading the buffer to a concurrent relation extension.
1096 : : */
1117 andres@anarazel.de 1097 [ + + - + ]:CBC 55973 : if (mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK)
1126 1098 : 46129 : flags |= EB_LOCK_TARGET;
1099 : :
1100 [ + + ]: 114142 : while (current_size < extend_to)
1101 : : {
1102 : 58169 : uint32 num_pages = lengthof(buffers);
1103 : : BlockNumber first_block;
1104 : :
1105 [ + + ]: 58169 : if ((uint64) current_size + num_pages > extend_to)
1106 : 58103 : num_pages = extend_to - current_size;
1107 : :
986 tmunro@postgresql.or 1108 : 58169 : first_block = ExtendBufferedRelCommon(bmr, fork, strategy, flags,
1109 : : num_pages, extend_to,
1110 : : buffers, &extended_by);
1111 : :
1126 andres@anarazel.de 1112 : 58169 : current_size = first_block + extended_by;
1113 [ - + - - ]: 58169 : Assert(num_pages != 0 || current_size >= extend_to);
1114 : :
959 peter@eisentraut.org 1115 [ + + ]: 125169 : for (uint32 i = 0; i < extended_by; i++)
1116 : : {
1126 andres@anarazel.de 1117 [ + + ]: 67000 : if (first_block + i != extend_to - 1)
1118 : 11036 : ReleaseBuffer(buffers[i]);
1119 : : else
1120 : 55964 : buffer = buffers[i];
1121 : : }
1122 : : }
1123 : :
1124 : : /*
1125 : : * It's possible that another backend concurrently extended the relation.
1126 : : * In that case read the buffer.
1127 : : *
1128 : : * XXX: Should we control this via a flag?
1129 : : */
1130 [ + + ]: 55973 : if (buffer == InvalidBuffer)
1131 : : {
1132 [ - + ]: 9 : Assert(extended_by == 0);
196 alvherre@kurilemu.de 1133 [ + - ]:GNC 9 : buffer = ReadBuffer_common(bmr.rel, BMR_GET_SMGR(bmr), bmr.relpersistence,
1134 : : fork, extend_to - 1, mode, strategy);
1135 : : }
1136 : :
1126 andres@anarazel.de 1137 :CBC 55973 : return buffer;
1138 : : }
1139 : :
1140 : : /*
1141 : : * Lock and optionally zero a buffer, as part of the implementation of
1142 : : * RBM_ZERO_AND_LOCK or RBM_ZERO_AND_CLEANUP_LOCK. The buffer must be already
1143 : : * pinned. If the buffer is not already valid, it is zeroed and made valid.
1144 : : */
1145 : : static void
694 tmunro@postgresql.or 1146 : 358133 : ZeroAndLockBuffer(Buffer buffer, ReadBufferMode mode, bool already_valid)
1147 : : {
1148 : : BufferDesc *bufHdr;
1149 : : bool need_to_zero;
1150 : 358133 : bool isLocalBuf = BufferIsLocal(buffer);
1151 : : StartBufferIOResult sbres;
1152 : :
762 1153 [ + + - + ]: 358133 : Assert(mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK);
1154 : :
694 1155 [ + + ]: 358133 : if (already_valid)
1156 : : {
1157 : : /*
1158 : : * If the caller already knew the buffer was valid, we can skip some
1159 : : * header interaction. The caller just wants to lock the buffer.
1160 : : */
1161 : 38290 : need_to_zero = false;
1162 : : }
1163 : : else
1164 : : {
39 andres@anarazel.de 1165 [ + + ]:GNC 319843 : if (isLocalBuf)
1166 : : {
1167 : : /* Simple case for non-shared buffers. */
1168 : 45 : bufHdr = GetLocalBufferDescriptor(-buffer - 1);
1169 : 45 : sbres = StartLocalBufferIO(bufHdr, true, true, NULL);
1170 : : }
1171 : : else
1172 : : {
1173 : : /*
1174 : : * Take BM_IO_IN_PROGRESS, or discover that BM_VALID has been set
1175 : : * concurrently. Even though we aren't doing I/O, that ensures
1176 : : * that we don't zero a page that someone else has pinned. An
1177 : : * exclusive content lock wouldn't be enough, because readers are
1178 : : * allowed to drop the content lock after determining that a tuple
1179 : : * is visible (see buffer access rules in README).
1180 : : */
1181 : 319798 : bufHdr = GetBufferDescriptor(buffer - 1);
1182 : 319798 : sbres = StartSharedBufferIO(bufHdr, true, true, NULL);
1183 : : }
1184 : :
1185 [ - + ]: 319843 : Assert(sbres != BUFFER_IO_IN_PROGRESS);
1186 : 319843 : need_to_zero = sbres == BUFFER_IO_READY_FOR_IO;
1187 : : }
1188 : :
694 tmunro@postgresql.or 1189 [ + + ]:CBC 358133 : if (need_to_zero)
1190 : : {
1191 : 319843 : memset(BufferGetPage(buffer), 0, BLCKSZ);
1192 : :
1193 : : /*
1194 : : * Grab the buffer content lock before marking the page as valid, to
1195 : : * make sure that no other backend sees the zeroed page before the
1196 : : * caller has had a chance to initialize it.
1197 : : *
1198 : : * Since no-one else can be looking at the page contents yet, there is
1199 : : * no difference between an exclusive lock and a cleanup-strength
1200 : : * lock. (Note that we cannot use LockBuffer() or
1201 : : * LockBufferForCleanup() here, because they assert that the buffer is
1202 : : * already valid.)
1203 : : */
1204 [ + + ]: 319843 : if (!isLocalBuf)
209 andres@anarazel.de 1205 :GNC 319798 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
1206 : :
1207 : : /* Set BM_VALID, terminate IO, and wake up any waiters */
694 tmunro@postgresql.or 1208 [ + + ]:CBC 319843 : if (isLocalBuf)
401 andres@anarazel.de 1209 : 45 : TerminateLocalBufferIO(bufHdr, false, BM_VALID, false);
1210 : : else
1211 : 319798 : TerminateBufferIO(bufHdr, false, BM_VALID, true, false);
1212 : : }
694 tmunro@postgresql.or 1213 [ + + ]: 38290 : else if (!isLocalBuf)
1214 : : {
1215 : : /*
1216 : : * The buffer is valid, so we can't zero it. The caller still expects
1217 : : * the page to be locked on return.
1218 : : */
1219 [ + + ]: 38260 : if (mode == RBM_ZERO_AND_LOCK)
1220 : 38114 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
1221 : : else
1222 : 146 : LockBufferForCleanup(buffer);
1223 : : }
762 1224 : 358133 : }
1225 : :
1226 : : /*
1227 : : * Pin a buffer for a given block. *foundPtr is set to true if the block was
1228 : : * already present, or false if more work is required to either read it in or
1229 : : * zero it.
1230 : : */
1231 : : static pg_attribute_always_inline Buffer
1232 : 84621197 : PinBufferForBlock(Relation rel,
1233 : : SMgrRelation smgr,
1234 : : char persistence,
1235 : : ForkNumber forkNum,
1236 : : BlockNumber blockNum,
1237 : : BufferAccessStrategy strategy,
1238 : : IOObject io_object,
1239 : : IOContext io_context,
1240 : : bool *foundPtr)
1241 : : {
1242 : : BufferDesc *bufHdr;
1243 : :
1244 [ - + ]: 84621197 : Assert(blockNum != P_NEW);
1245 : :
1246 : : /* Persistence should be set before */
654 noah@leadboat.com 1247 [ + + + + : 84621197 : Assert((persistence == RELPERSISTENCE_TEMP ||
- + ]
1248 : : persistence == RELPERSISTENCE_PERMANENT ||
1249 : : persistence == RELPERSISTENCE_UNLOGGED));
1250 : :
1251 : : TRACE_POSTGRESQL_BUFFER_READ_START(forkNum, blockNum,
1252 : : smgr->smgr_rlocator.locator.spcOid,
1253 : : smgr->smgr_rlocator.locator.dbOid,
1254 : : smgr->smgr_rlocator.locator.relNumber,
1255 : : smgr->smgr_rlocator.backend);
1256 : :
762 tmunro@postgresql.or 1257 [ + + ]: 84621197 : if (persistence == RELPERSISTENCE_TEMP)
1258 : 1912003 : bufHdr = LocalBufferAlloc(smgr, forkNum, blockNum, foundPtr);
1259 : : else
1260 : 82709194 : bufHdr = BufferAlloc(smgr, persistence, forkNum, blockNum,
1261 : : strategy, foundPtr, io_context);
1262 : :
40 andres@anarazel.de 1263 [ + + ]:GNC 84621189 : if (*foundPtr)
1264 : 82645703 : TrackBufferHit(io_object, io_context, rel, persistence, smgr, forkNum, blockNum);
1265 : :
762 tmunro@postgresql.or 1266 [ + + ]:CBC 84621189 : if (rel)
1267 : : {
1268 : : /*
1269 : : * While pgBufferUsage's "read" counter isn't bumped unless we reach
1270 : : * WaitReadBuffers() (so, not for hits, and not for buffers that are
1271 : : * zeroed instead), the per-relation stats always count them.
1272 : : */
1273 [ + + + + : 78389713 : pgstat_count_buffer_read(rel);
+ + ]
1274 : : }
1275 : :
1276 : 84621189 : return BufferDescriptorGetBuffer(bufHdr);
1277 : : }
1278 : :
1279 : : /*
1280 : : * ReadBuffer_common -- common logic for all ReadBuffer variants
1281 : : *
1282 : : * smgr is required, rel is optional unless using P_NEW.
1283 : : */
1284 : : static pg_attribute_always_inline Buffer
1285 : 80120771 : ReadBuffer_common(Relation rel, SMgrRelation smgr, char smgr_persistence,
1286 : : ForkNumber forkNum,
1287 : : BlockNumber blockNum, ReadBufferMode mode,
1288 : : BufferAccessStrategy strategy)
1289 : : {
1290 : : ReadBuffersOperation operation;
1291 : : Buffer buffer;
1292 : : int flags;
1293 : : char persistence;
1294 : :
1295 : : /*
1296 : : * Backward compatibility path, most code should use ExtendBufferedRel()
1297 : : * instead, as acquiring the extension lock inside ExtendBufferedRel()
1298 : : * scales a lot better.
1299 : : */
1300 [ + + ]: 80120771 : if (unlikely(blockNum == P_NEW))
1301 : : {
1302 : 322 : uint32 flags = EB_SKIP_EXTENSION_LOCK;
1303 : :
1304 : : /*
1305 : : * Since no-one else can be looking at the page contents yet, there is
1306 : : * no difference between an exclusive lock and a cleanup-strength
1307 : : * lock.
1308 : : */
1309 [ + - - + ]: 322 : if (mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK)
762 tmunro@postgresql.or 1310 :UBC 0 : flags |= EB_LOCK_FIRST;
1311 : :
762 tmunro@postgresql.or 1312 :CBC 322 : return ExtendBufferedRel(BMR_REL(rel), forkNum, strategy, flags);
1313 : : }
1314 : :
654 noah@leadboat.com 1315 [ + + ]: 80120449 : if (rel)
1316 : 74155064 : persistence = rel->rd_rel->relpersistence;
1317 : : else
1318 : 5965385 : persistence = smgr_persistence;
1319 : :
762 tmunro@postgresql.or 1320 [ + + + + : 80120449 : if (unlikely(mode == RBM_ZERO_AND_CLEANUP_LOCK ||
+ + ]
1321 : : mode == RBM_ZERO_AND_LOCK))
1322 : : {
1323 : : bool found;
1324 : : IOContext io_context;
1325 : : IOObject io_object;
1326 : :
40 andres@anarazel.de 1327 [ + + ]:GNC 358133 : if (persistence == RELPERSISTENCE_TEMP)
1328 : : {
1329 : 75 : io_context = IOCONTEXT_NORMAL;
1330 : 75 : io_object = IOOBJECT_TEMP_RELATION;
1331 : : }
1332 : : else
1333 : : {
1334 : 358058 : io_context = IOContextForStrategy(strategy);
1335 : 358058 : io_object = IOOBJECT_RELATION;
1336 : : }
1337 : :
654 noah@leadboat.com 1338 :CBC 358133 : buffer = PinBufferForBlock(rel, smgr, persistence,
1339 : : forkNum, blockNum, strategy,
1340 : : io_object, io_context, &found);
694 tmunro@postgresql.or 1341 : 358133 : ZeroAndLockBuffer(buffer, mode, found);
762 1342 : 358133 : return buffer;
1343 : : }
1344 : :
1345 : : /*
1346 : : * Signal that we are going to immediately wait. If we're immediately
1347 : : * waiting, there is no benefit in actually executing the IO
1348 : : * asynchronously, it would just add dispatch overhead.
1349 : : */
401 andres@anarazel.de 1350 : 79762316 : flags = READ_BUFFERS_SYNCHRONOUSLY;
762 tmunro@postgresql.or 1351 [ + + ]: 79762316 : if (mode == RBM_ZERO_ON_ERROR)
401 andres@anarazel.de 1352 : 1394192 : flags |= READ_BUFFERS_ZERO_ON_ERROR;
762 tmunro@postgresql.or 1353 : 79762316 : operation.smgr = smgr;
1354 : 79762316 : operation.rel = rel;
654 noah@leadboat.com 1355 : 79762316 : operation.persistence = persistence;
762 tmunro@postgresql.or 1356 : 79762316 : operation.forknum = forkNum;
1357 : 79762316 : operation.strategy = strategy;
1358 [ + + ]: 79762316 : if (StartReadBuffer(&operation,
1359 : : &buffer,
1360 : : blockNum,
1361 : : flags))
1362 : 776120 : WaitReadBuffers(&operation);
1363 : :
1364 : 79762289 : return buffer;
1365 : : }
1366 : :
1367 : : static pg_attribute_always_inline bool
1368 : 84082024 : StartReadBuffersImpl(ReadBuffersOperation *operation,
1369 : : Buffer *buffers,
1370 : : BlockNumber blockNum,
1371 : : int *nblocks,
1372 : : int flags,
1373 : : bool allow_forwarding)
1374 : : {
1375 : 84082024 : int actual_nblocks = *nblocks;
574 andres@anarazel.de 1376 : 84082024 : int maxcombine = 0;
1377 : : bool did_start_io;
1378 : : IOContext io_context;
1379 : : IOObject io_object;
1380 : :
410 tmunro@postgresql.or 1381 [ + + - + ]: 84082024 : Assert(*nblocks == 1 || allow_forwarding);
762 1382 [ - + ]: 84082024 : Assert(*nblocks > 0);
1383 [ - + ]: 84082024 : Assert(*nblocks <= MAX_IO_COMBINE_LIMIT);
1384 : :
40 andres@anarazel.de 1385 [ + + ]:GNC 84082024 : if (operation->persistence == RELPERSISTENCE_TEMP)
1386 : : {
1387 : 1903712 : io_context = IOCONTEXT_NORMAL;
1388 : 1903712 : io_object = IOOBJECT_TEMP_RELATION;
1389 : : }
1390 : : else
1391 : : {
1392 : 82178312 : io_context = IOContextForStrategy(operation->strategy);
1393 : 82178312 : io_object = IOOBJECT_RELATION;
1394 : : }
1395 : :
762 tmunro@postgresql.or 1396 [ + + ]:CBC 85737707 : for (int i = 0; i < actual_nblocks; ++i)
1397 : : {
1398 : : bool found;
1399 : :
410 1400 [ + + + + ]: 84265307 : if (allow_forwarding && buffers[i] != InvalidBuffer)
1401 : 2243 : {
1402 : : BufferDesc *bufHdr;
1403 : :
1404 : : /*
1405 : : * This is a buffer that was pinned by an earlier call to
1406 : : * StartReadBuffers(), but couldn't be handled in one operation at
1407 : : * that time. The operation was split, and the caller has passed
1408 : : * an already pinned buffer back to us to handle the rest of the
1409 : : * operation. It must continue at the expected block number.
1410 : : */
1411 [ - + ]: 2243 : Assert(BufferGetBlockNumber(buffers[i]) == blockNum + i);
1412 : :
1413 : : /*
1414 : : * It might be an already valid buffer (a hit) that followed the
1415 : : * final contiguous block of an earlier I/O (a miss) marking the
1416 : : * end of it, or a buffer that some other backend has since made
1417 : : * valid by performing the I/O for us, in which case we can handle
1418 : : * it as a hit now. It is safe to check for a BM_VALID flag with
1419 : : * a relaxed load, because we got a fresh view of it while pinning
1420 : : * it in the previous call.
1421 : : *
1422 : : * On the other hand if we don't see BM_VALID yet, it must be an
1423 : : * I/O that was split by the previous call and we need to try to
1424 : : * start a new I/O from this block. We're also racing against any
1425 : : * other backend that might start the I/O or even manage to mark
1426 : : * it BM_VALID after this check, but StartBufferIO() will handle
1427 : : * those cases.
1428 : : */
1429 [ + + ]: 2243 : if (BufferIsLocal(buffers[i]))
1430 : 26 : bufHdr = GetLocalBufferDescriptor(-buffers[i] - 1);
1431 : : else
1432 : 2217 : bufHdr = GetBufferDescriptor(buffers[i] - 1);
110 andres@anarazel.de 1433 [ - + ]:GNC 2243 : Assert(pg_atomic_read_u64(&bufHdr->state) & BM_TAG_VALID);
1434 : 2243 : found = pg_atomic_read_u64(&bufHdr->state) & BM_VALID;
1435 : : }
1436 : : else
1437 : : {
410 tmunro@postgresql.or 1438 :CBC 84263056 : buffers[i] = PinBufferForBlock(operation->rel,
410 tmunro@postgresql.or 1439 :ECB (57353754) : operation->smgr,
410 tmunro@postgresql.or 1440 :CBC 84263064 : operation->persistence,
1441 : : operation->forknum,
1442 : : blockNum + i,
1443 : : operation->strategy,
1444 : : io_object, io_context,
1445 : : &found);
1446 : : }
1447 : :
762 1448 [ + + ]: 84265299 : if (found)
1449 : : {
1450 : : /*
1451 : : * We have a hit. If it's the first block in the requested range,
1452 : : * we can return it immediately and report that WaitReadBuffers()
1453 : : * does not need to be called. If the initial value of *nblocks
1454 : : * was larger, the caller will have to call again for the rest.
1455 : : */
410 1456 [ + + ]: 82609616 : if (i == 0)
1457 : : {
1458 : 82607410 : *nblocks = 1;
1459 : :
1460 : : #ifdef USE_ASSERT_CHECKING
1461 : :
1462 : : /*
1463 : : * Initialize enough of ReadBuffersOperation to make
1464 : : * CheckReadBuffersOperation() work. Outside of assertions
1465 : : * that's not necessary when no IO is issued.
1466 : : */
401 andres@anarazel.de 1467 : 82607410 : operation->buffers = buffers;
1468 : 82607410 : operation->blocknum = blockNum;
1469 : 82607410 : operation->nblocks = 1;
1470 : 82607410 : operation->nblocks_done = 1;
1471 : 82607410 : CheckReadBuffersOperation(operation, true);
1472 : : #endif
410 tmunro@postgresql.or 1473 : 82607410 : return false;
1474 : : }
1475 : :
1476 : : /*
1477 : : * Otherwise we already have an I/O to perform, but this block
1478 : : * can't be included as it is already valid. Split the I/O here.
1479 : : * There may or may not be more blocks requiring I/O after this
1480 : : * one, we haven't checked, but they can't be contiguous with this
1481 : : * one in the way. We'll leave this buffer pinned, forwarding it
1482 : : * to the next call, avoiding the need to unpin it here and re-pin
1483 : : * it in the next call.
1484 : : */
1485 : 2206 : actual_nblocks = i;
762 1486 : 2206 : break;
1487 : : }
1488 : : else
1489 : : {
1490 : : /*
1491 : : * Check how many blocks we can cover with the same IO. The smgr
1492 : : * implementation might e.g. be limited due to a segment boundary.
1493 : : */
574 andres@anarazel.de 1494 [ + + + + ]: 1655683 : if (i == 0 && actual_nblocks > 1)
1495 : : {
1496 : 37118 : maxcombine = smgrmaxcombine(operation->smgr,
1497 : : operation->forknum,
1498 : : blockNum);
1499 [ - + ]: 37118 : if (unlikely(maxcombine < actual_nblocks))
1500 : : {
574 andres@anarazel.de 1501 [ # # ]:UBC 0 : elog(DEBUG2, "limiting nblocks at %u from %u to %u",
1502 : : blockNum, actual_nblocks, maxcombine);
1503 : 0 : actual_nblocks = maxcombine;
1504 : : }
1505 : : }
1506 : : }
1507 : : }
762 tmunro@postgresql.or 1508 :CBC 1474606 : *nblocks = actual_nblocks;
1509 : :
1510 : : /* Populate information needed for I/O. */
1511 : 1474606 : operation->buffers = buffers;
1512 : 1474606 : operation->blocknum = blockNum;
1513 : 1474606 : operation->flags = flags;
1514 : 1474606 : operation->nblocks = actual_nblocks;
401 andres@anarazel.de 1515 : 1474606 : operation->nblocks_done = 0;
1516 : 1474606 : pgaio_wref_clear(&operation->io_wref);
1517 : :
1518 : : /*
1519 : : * When using AIO, start the IO in the background. If not, issue prefetch
1520 : : * requests if desired by the caller.
1521 : : *
1522 : : * The reason we have a dedicated path for IOMETHOD_SYNC here is to
1523 : : * de-risk the introduction of AIO somewhat. It's a large architectural
1524 : : * change, with lots of chances for unanticipated performance effects.
1525 : : *
1526 : : * Use of IOMETHOD_SYNC already leads to not actually performing IO
1527 : : * asynchronously, but without the check here we'd execute IO earlier than
1528 : : * we used to. Eventually this IOMETHOD_SYNC specific path should go away.
1529 : : */
1530 [ + + ]: 1474606 : if (io_method != IOMETHOD_SYNC)
1531 : : {
1532 : : /*
1533 : : * Try to start IO asynchronously. It's possible that no IO needs to
1534 : : * be started, if another backend already performed the IO.
1535 : : *
1536 : : * Note that if an IO is started, it might not cover the entire
1537 : : * requested range, e.g. because an intermediary block has been read
1538 : : * in by another backend. In that case any "trailing" buffers we
1539 : : * already pinned above will be "forwarded" by read_stream.c to the
1540 : : * next call to StartReadBuffers().
1541 : : *
1542 : : * This is signalled to the caller by decrementing *nblocks *and*
1543 : : * reducing operation->nblocks. The latter is done here, but not below
1544 : : * WaitReadBuffers(), as in WaitReadBuffers() we can't "shorten" the
1545 : : * overall read size anymore, we need to retry until done in its
1546 : : * entirety or until failed.
1547 : : */
1548 : 1473230 : did_start_io = AsyncReadBuffers(operation, nblocks);
1549 : :
1550 : 1473215 : operation->nblocks = *nblocks;
1551 : : }
1552 : : else
1553 : : {
1554 : 1376 : operation->flags |= READ_BUFFERS_SYNCHRONOUSLY;
1555 : :
1556 [ + + ]: 1376 : if (flags & READ_BUFFERS_ISSUE_ADVICE)
1557 : : {
1558 : : /*
1559 : : * In theory we should only do this if PinBufferForBlock() had to
1560 : : * allocate new buffers above. That way, if two calls to
1561 : : * StartReadBuffers() were made for the same blocks before
1562 : : * WaitReadBuffers(), only the first would issue the advice.
1563 : : * That'd be a better simulation of true asynchronous I/O, which
1564 : : * would only start the I/O once, but isn't done here for
1565 : : * simplicity.
1566 : : */
1567 : 19 : smgrprefetch(operation->smgr,
1568 : : operation->forknum,
1569 : : blockNum,
1570 : : actual_nblocks);
1571 : : }
1572 : :
1573 : : /*
1574 : : * Indicate that WaitReadBuffers() should be called. WaitReadBuffers()
1575 : : * will initiate the necessary IO.
1576 : : */
1577 : 1376 : did_start_io = true;
1578 : : }
1579 : :
1580 : 1474591 : CheckReadBuffersOperation(operation, !did_start_io);
1581 : :
1582 : 1474591 : return did_start_io;
1583 : : }
1584 : :
1585 : : /*
1586 : : * Begin reading a range of blocks beginning at blockNum and extending for
1587 : : * *nblocks. *nblocks and the buffers array are in/out parameters. On entry,
1588 : : * the buffers elements covered by *nblocks must hold either InvalidBuffer or
1589 : : * buffers forwarded by an earlier call to StartReadBuffers() that was split
1590 : : * and is now being continued. On return, *nblocks holds the number of blocks
1591 : : * accepted by this operation. If it is less than the original number then
1592 : : * this operation has been split, but buffer elements up to the original
1593 : : * requested size may hold forwarded buffers to be used for a continuing
1594 : : * operation. The caller must either start a new I/O beginning at the block
1595 : : * immediately following the blocks accepted by this call and pass those
1596 : : * buffers back in, or release them if it chooses not to. It shouldn't make
1597 : : * any other use of or assumptions about forwarded buffers.
1598 : : *
1599 : : * If false is returned, no I/O is necessary and the buffers covered by
1600 : : * *nblocks on exit are valid and ready to be accessed. If true is returned,
1601 : : * an I/O has been started, and WaitReadBuffers() must be called with the same
1602 : : * operation object before the buffers covered by *nblocks on exit can be
1603 : : * accessed. Along with the operation object, the caller-supplied array of
1604 : : * buffers must remain valid until WaitReadBuffers() is called, and any
1605 : : * forwarded buffers must also be preserved for a continuing call unless
1606 : : * they are explicitly released.
1607 : : */
1608 : : bool
762 tmunro@postgresql.or 1609 : 1786469 : StartReadBuffers(ReadBuffersOperation *operation,
1610 : : Buffer *buffers,
1611 : : BlockNumber blockNum,
1612 : : int *nblocks,
1613 : : int flags)
1614 : : {
410 1615 : 1786469 : return StartReadBuffersImpl(operation, buffers, blockNum, nblocks, flags,
1616 : : true /* expect forwarded buffers */ );
1617 : : }
1618 : :
1619 : : /*
1620 : : * Single block version of the StartReadBuffers(). This might save a few
1621 : : * instructions when called from another translation unit, because it is
1622 : : * specialized for nblocks == 1.
1623 : : *
1624 : : * This version does not support "forwarded" buffers: they cannot be created
1625 : : * by reading only one block and *buffer is ignored on entry.
1626 : : */
1627 : : bool
762 1628 : 82295555 : StartReadBuffer(ReadBuffersOperation *operation,
1629 : : Buffer *buffer,
1630 : : BlockNumber blocknum,
1631 : : int flags)
1632 : : {
1633 : 82295555 : int nblocks = 1;
1634 : : bool result;
1635 : :
410 1636 : 82295555 : result = StartReadBuffersImpl(operation, buffer, blocknum, &nblocks, flags,
1637 : : false /* single block, no forwarding */ );
762 1638 [ - + ]: 82295540 : Assert(nblocks == 1); /* single block can't be short */
1639 : :
1640 : 82295540 : return result;
1641 : : }
1642 : :
1643 : : /*
1644 : : * Perform sanity checks on the ReadBuffersOperation.
1645 : : */
1646 : : static void
401 andres@anarazel.de 1647 : 87030838 : CheckReadBuffersOperation(ReadBuffersOperation *operation, bool is_complete)
1648 : : {
1649 : : #ifdef USE_ASSERT_CHECKING
1650 [ - + ]: 87030838 : Assert(operation->nblocks_done <= operation->nblocks);
1651 [ + + - + ]: 87030838 : Assert(!is_complete || operation->nblocks == operation->nblocks_done);
1652 : :
1653 [ + + ]: 174607919 : for (int i = 0; i < operation->nblocks; i++)
1654 : : {
1655 : 87577081 : Buffer buffer = operation->buffers[i];
1656 : 87577081 : BufferDesc *buf_hdr = BufferIsLocal(buffer) ?
1657 [ + + ]: 87577081 : GetLocalBufferDescriptor(-buffer - 1) :
1658 : 85643789 : GetBufferDescriptor(buffer - 1);
1659 : :
1660 [ - + ]: 87577081 : Assert(BufferGetBlockNumber(buffer) == operation->blocknum + i);
110 andres@anarazel.de 1661 [ - + ]:GNC 87577081 : Assert(pg_atomic_read_u64(&buf_hdr->state) & BM_TAG_VALID);
1662 : :
401 andres@anarazel.de 1663 [ + + ]:CBC 87577081 : if (i < operation->nblocks_done)
110 andres@anarazel.de 1664 [ - + ]:GNC 84263747 : Assert(pg_atomic_read_u64(&buf_hdr->state) & BM_VALID);
1665 : : }
1666 : : #endif
401 andres@anarazel.de 1667 :CBC 87030838 : }
1668 : :
1669 : : /*
1670 : : * We track various stats related to buffer hits. Because this is done in a
1671 : : * few separate places, this helper exists for convenience.
1672 : : */
1673 : : static pg_attribute_always_inline void
40 andres@anarazel.de 1674 :GNC 82648374 : TrackBufferHit(IOObject io_object, IOContext io_context,
1675 : : Relation rel, char persistence, SMgrRelation smgr,
1676 : : ForkNumber forknum, BlockNumber blocknum)
1677 : : {
1678 : : TRACE_POSTGRESQL_BUFFER_READ_DONE(forknum,
1679 : : blocknum,
1680 : : smgr->smgr_rlocator.locator.spcOid,
1681 : : smgr->smgr_rlocator.locator.dbOid,
1682 : : smgr->smgr_rlocator.locator.relNumber,
1683 : : smgr->smgr_rlocator.backend,
1684 : : true);
1685 : :
1686 [ + + ]: 82648374 : if (persistence == RELPERSISTENCE_TEMP)
1687 : 1900892 : pgBufferUsage.local_blks_hit += 1;
1688 : : else
1689 : 80747482 : pgBufferUsage.shared_blks_hit += 1;
1690 : :
1691 : 82648374 : pgstat_count_io_op(io_object, io_context, IOOP_HIT, 1, 0);
1692 : :
1693 [ + + ]: 82648374 : if (VacuumCostActive)
1694 : 187737 : VacuumCostBalance += VacuumCostPageHit;
1695 : :
1696 [ + + ]: 82648374 : if (rel)
1697 [ + + + + : 76938798 : pgstat_count_buffer_hit(rel);
+ + ]
40 andres@anarazel.de 1698 :GIC 82648374 : }
1699 : :
1700 : : /*
1701 : : * Helper for WaitReadBuffers() that processes the results of a readv
1702 : : * operation, raising an error if necessary.
1703 : : */
1704 : : static void
401 andres@anarazel.de 1705 :CBC 1471689 : ProcessReadBuffersResult(ReadBuffersOperation *operation)
1706 : : {
1707 : 1471689 : PgAioReturn *aio_ret = &operation->io_return;
1708 : 1471689 : PgAioResultStatus rs = aio_ret->result.status;
1709 : 1471689 : int newly_read_blocks = 0;
1710 : :
1711 [ - + ]: 1471689 : Assert(pgaio_wref_valid(&operation->io_wref));
1712 [ - + ]: 1471689 : Assert(aio_ret->result.status != PGAIO_RS_UNKNOWN);
1713 : :
1714 : : /*
1715 : : * SMGR reports the number of blocks successfully read as the result of
1716 : : * the IO operation. Thus we can simply add that to ->nblocks_done.
1717 : : */
1718 : :
1719 [ + + ]: 1471689 : if (likely(rs != PGAIO_RS_ERROR))
1720 : 1471646 : newly_read_blocks = aio_ret->result.result;
1721 : :
1722 [ + + + + ]: 1471689 : if (rs == PGAIO_RS_ERROR || rs == PGAIO_RS_WARNING)
1723 [ + + ]: 67 : pgaio_result_report(aio_ret->result, &aio_ret->target_data,
1724 : : rs == PGAIO_RS_ERROR ? ERROR : WARNING);
1725 [ + + ]: 1471622 : else if (aio_ret->result.status == PGAIO_RS_PARTIAL)
1726 : : {
1727 : : /*
1728 : : * We'll retry, so we just emit a debug message to the server log (or
1729 : : * not even that in prod scenarios).
1730 : : */
1731 : 163 : pgaio_result_report(aio_ret->result, &aio_ret->target_data, DEBUG1);
1732 [ + - ]: 163 : elog(DEBUG3, "partial read, will retry");
1733 : : }
1734 : :
1735 [ - + ]: 1471646 : Assert(newly_read_blocks > 0);
1736 [ - + ]: 1471646 : Assert(newly_read_blocks <= MAX_IO_COMBINE_LIMIT);
1737 : :
1738 : 1471646 : operation->nblocks_done += newly_read_blocks;
1739 : :
1740 [ - + ]: 1471646 : Assert(operation->nblocks_done <= operation->nblocks);
1741 : 1471646 : }
1742 : :
1743 : : /*
1744 : : * Wait for the IO operation initiated by StartReadBuffers() et al to
1745 : : * complete.
1746 : : *
1747 : : * Returns true if we needed to wait for the IO operation, false otherwise.
1748 : : */
1749 : : bool
762 tmunro@postgresql.or 1750 : 1473667 : WaitReadBuffers(ReadBuffersOperation *operation)
1751 : : {
401 andres@anarazel.de 1752 : 1473667 : PgAioReturn *aio_ret = &operation->io_return;
1753 : : IOContext io_context;
1754 : : IOObject io_object;
34 andres@anarazel.de 1755 :GNC 1473667 : bool needed_wait = false;
1756 : :
401 andres@anarazel.de 1757 [ + + ]:CBC 1473667 : if (operation->persistence == RELPERSISTENCE_TEMP)
1758 : : {
762 tmunro@postgresql.or 1759 : 2455 : io_context = IOCONTEXT_NORMAL;
1760 : 2455 : io_object = IOOBJECT_TEMP_RELATION;
1761 : : }
1762 : : else
1763 : : {
1764 : 1471212 : io_context = IOContextForStrategy(operation->strategy);
1765 : 1471212 : io_object = IOOBJECT_RELATION;
1766 : : }
1767 : :
1768 : : /*
1769 : : * If we get here without an IO operation having been issued, the
1770 : : * io_method == IOMETHOD_SYNC path must have been used. Otherwise the
1771 : : * caller should not have called WaitReadBuffers().
1772 : : *
1773 : : * In the case of IOMETHOD_SYNC, we start - as we used to before the
1774 : : * introducing of AIO - the IO in WaitReadBuffers(). This is done as part
1775 : : * of the retry logic below, no extra code is required.
1776 : : *
1777 : : * This path is expected to eventually go away.
1778 : : */
401 andres@anarazel.de 1779 [ + + + - ]: 1473667 : if (!pgaio_wref_valid(&operation->io_wref) && io_method != IOMETHOD_SYNC)
401 andres@anarazel.de 1780 [ # # ]:UBC 0 : elog(ERROR, "waiting for read operation that didn't read");
1781 : :
1782 : : /*
1783 : : * To handle partial reads, and IOMETHOD_SYNC, we re-issue IO until we're
1784 : : * done. We may need multiple retries, not just because we could get
1785 : : * multiple partial reads, but also because some of the remaining
1786 : : * to-be-read buffers may have been read in by other backends, limiting
1787 : : * the IO size.
1788 : : */
1789 : : while (true)
762 tmunro@postgresql.or 1790 :CBC 1546 : {
1791 : : int ignored_nblocks_progress;
1792 : :
401 andres@anarazel.de 1793 : 1475213 : CheckReadBuffersOperation(operation, false);
1794 : :
1795 : : /*
1796 : : * If there is an IO associated with the operation, we may need to
1797 : : * wait for it.
1798 : : */
1799 [ + + ]: 1475213 : if (pgaio_wref_valid(&operation->io_wref))
1800 : : {
1801 : : /*
1802 : : * Track the time spent waiting for the IO to complete. As
1803 : : * tracking a wait even if we don't actually need to wait
1804 : : *
1805 : : * a) is not cheap, due to the timestamping overhead
1806 : : *
1807 : : * b) reports some time as waiting, even if we never waited
1808 : : *
1809 : : * we first check if we already know the IO is complete.
1810 : : *
1811 : : * Note that operation->io_return is uninitialized for foreign IO,
1812 : : * so we cannot use the cheaper PGAIO_RS_UNKNOWN pre-check.
1813 : : */
39 andres@anarazel.de 1814 [ + + + + ]:GNC 1473828 : if ((operation->foreign_io || aio_ret->result.status == PGAIO_RS_UNKNOWN) &&
401 andres@anarazel.de 1815 [ + + ]:CBC 670198 : !pgaio_wref_check_done(&operation->io_wref))
1816 : 301498 : {
1817 : 301498 : instr_time io_start = pgstat_prepare_io_time(track_io_timing);
1818 : :
1819 : 301498 : pgaio_wref_wait(&operation->io_wref);
34 andres@anarazel.de 1820 :GNC 301498 : needed_wait = true;
1821 : :
1822 : : /*
1823 : : * The IO operation itself was already counted earlier, in
1824 : : * AsyncReadBuffers(), this just accounts for the wait time.
1825 : : */
401 andres@anarazel.de 1826 :CBC 301498 : pgstat_count_io_op_time(io_object, io_context, IOOP_READ,
1827 : : io_start, 0, 0);
1828 : : }
1829 : : else
1830 : : {
1831 [ - + ]: 1172330 : Assert(pgaio_wref_check_done(&operation->io_wref));
1832 : : }
1833 : :
39 andres@anarazel.de 1834 [ + + ]:GNC 1473828 : if (unlikely(operation->foreign_io))
1835 : : {
1836 : 2139 : Buffer buffer = operation->buffers[operation->nblocks_done];
1837 : 2139 : BufferDesc *desc = BufferIsLocal(buffer) ?
1838 [ + + ]: 2139 : GetLocalBufferDescriptor(-buffer - 1) :
1839 : 2136 : GetBufferDescriptor(buffer - 1);
1840 : 2139 : uint64 buf_state = pg_atomic_read_u64(&desc->state);
1841 : :
1842 [ + + ]: 2139 : if (buf_state & BM_VALID)
1843 : : {
1844 : 2135 : BlockNumber blocknum = operation->blocknum + operation->nblocks_done;
1845 : :
1846 : 2135 : operation->nblocks_done += 1;
1847 [ - + ]: 2135 : Assert(operation->nblocks_done <= operation->nblocks);
1848 : :
1849 : : /*
1850 : : * Track this as a 'hit' for this backend. The backend
1851 : : * performing the IO will track it as a 'read'.
1852 : : */
1853 : 2135 : TrackBufferHit(io_object, io_context,
1854 : 2135 : operation->rel, operation->persistence,
1855 : : operation->smgr, operation->forknum,
1856 : : blocknum);
1857 : : }
1858 : :
1859 : : /*
1860 : : * If the foreign IO failed and left the buffer invalid,
1861 : : * nblocks_done is not incremented. The retry loop below will
1862 : : * call AsyncReadBuffers() which will attempt the IO itself.
1863 : : */
1864 : : }
1865 : : else
1866 : : {
1867 : : /*
1868 : : * We now are sure the IO completed. Check the results. This
1869 : : * includes reporting on errors if there were any.
1870 : : */
1871 : 1471689 : ProcessReadBuffersResult(operation);
1872 : : }
1873 : : }
1874 : :
1875 : : /*
1876 : : * Most of the time, the one IO we already started, will read in
1877 : : * everything. But we need to deal with partial reads and buffers not
1878 : : * needing IO anymore.
1879 : : */
401 andres@anarazel.de 1880 [ + + ]:CBC 1475170 : if (operation->nblocks_done == operation->nblocks)
1881 : 1473624 : break;
1882 : :
1883 [ - + ]: 1546 : CHECK_FOR_INTERRUPTS();
1884 : :
1885 : : /*
1886 : : * If the IO completed only partially, we need to perform additional
1887 : : * work, consider that a form of having had to wait.
1888 : : */
34 andres@anarazel.de 1889 :GNC 1546 : needed_wait = true;
1890 : :
1891 : : /*
1892 : : * This may only complete the IO partially, either because some
1893 : : * buffers were already valid, or because of a partial read.
1894 : : *
1895 : : * NB: In contrast to after the AsyncReadBuffers() call in
1896 : : * StartReadBuffers(), we do *not* reduce
1897 : : * ReadBuffersOperation->nblocks here, callers expect the full
1898 : : * operation to be completed at this point (as more operations may
1899 : : * have been queued).
1900 : : */
401 andres@anarazel.de 1901 :CBC 1546 : AsyncReadBuffers(operation, &ignored_nblocks_progress);
1902 : : }
1903 : :
1904 : 1473624 : CheckReadBuffersOperation(operation, true);
1905 : :
1906 : : /* NB: READ_DONE tracepoint was already executed in completion callback */
34 andres@anarazel.de 1907 :GNC 1473624 : return needed_wait;
401 andres@anarazel.de 1908 :ECB (1251753) : }
1909 : :
1910 : : /*
1911 : : * Initiate IO for the ReadBuffersOperation
1912 : : *
1913 : : * This function only starts a single IO at a time. The size of the IO may be
1914 : : * limited to below the to-be-read blocks, if one of the buffers has
1915 : : * concurrently been read in. If the first to-be-read buffer is already valid,
1916 : : * no IO will be issued.
1917 : : *
1918 : : * To support retries after partial reads, the first operation->nblocks_done
1919 : : * buffers are skipped.
1920 : : *
1921 : : * On return *nblocks_progress is updated to reflect the number of buffers
1922 : : * affected by the call. If the first buffer is valid, *nblocks_progress is
1923 : : * set to 1 and operation->nblocks_done is incremented.
1924 : : *
1925 : : * Returns true if IO was initiated or is already in progress (foreign IO),
1926 : : * false if the buffer was already valid.
1927 : : */
1928 : : static bool
401 andres@anarazel.de 1929 :CBC 1474776 : AsyncReadBuffers(ReadBuffersOperation *operation, int *nblocks_progress)
1930 : : {
1931 : 1474776 : Buffer *buffers = &operation->buffers[0];
1932 : 1474776 : int flags = operation->flags;
1933 : 1474776 : ForkNumber forknum = operation->forknum;
1934 : 1474776 : char persistence = operation->persistence;
1935 : 1474776 : int16 nblocks_done = operation->nblocks_done;
40 1936 : 1474776 : BlockNumber blocknum = operation->blocknum + nblocks_done;
401 1937 : 1474776 : Buffer *io_buffers = &operation->buffers[nblocks_done];
1938 : 1474776 : int io_buffers_len = 0;
1939 : : PgAioHandle *ioh;
1940 : 1474776 : uint32 ioh_flags = 0;
1941 : : void *io_pages[MAX_IO_COMBINE_LIMIT];
1942 : : IOContext io_context;
1943 : : IOObject io_object;
1944 : : instr_time io_start;
1945 : : StartBufferIOResult status;
1946 : :
1947 [ + + ]: 1474776 : if (persistence == RELPERSISTENCE_TEMP)
1948 : : {
1949 : 2847 : io_context = IOCONTEXT_NORMAL;
1950 : 2847 : io_object = IOOBJECT_TEMP_RELATION;
1951 : : }
1952 : : else
1953 : : {
1954 : 1471929 : io_context = IOContextForStrategy(operation->strategy);
1955 : 1471929 : io_object = IOOBJECT_RELATION;
1956 : : }
1957 : :
1958 : : /*
1959 : : * When this IO is executed synchronously, either because the caller will
1960 : : * immediately block waiting for the IO or because IOMETHOD_SYNC is used,
1961 : : * the AIO subsystem needs to know.
1962 : : */
40 andres@anarazel.de 1963 [ + + ]:GNC 1474776 : if (flags & READ_BUFFERS_SYNCHRONOUSLY)
1964 : 794219 : ioh_flags |= PGAIO_HF_SYNCHRONOUS;
1965 : :
1966 [ + + ]: 1474776 : if (persistence == RELPERSISTENCE_TEMP)
1967 : 2847 : ioh_flags |= PGAIO_HF_REFERENCES_LOCAL;
1968 : :
1969 : : /*
1970 : : * If zero_damaged_pages is enabled, add the READ_BUFFERS_ZERO_ON_ERROR
1971 : : * flag. The reason for that is that, hopefully, zero_damaged_pages isn't
1972 : : * set globally, but on a per-session basis. The completion callback,
1973 : : * which may be run in other processes, e.g. in IO workers, may have a
1974 : : * different value of the zero_damaged_pages GUC.
1975 : : *
1976 : : * XXX: We probably should eventually use a different flag for
1977 : : * zero_damaged_pages, so we can report different log levels / error codes
1978 : : * for zero_damaged_pages and ZERO_ON_ERROR.
1979 : : */
401 andres@anarazel.de 1980 [ + + ]:CBC 1474776 : if (zero_damaged_pages)
1981 : 24 : flags |= READ_BUFFERS_ZERO_ON_ERROR;
1982 : :
1983 : : /*
1984 : : * For the same reason as with zero_damaged_pages we need to use this
1985 : : * backend's ignore_checksum_failure value.
1986 : : */
1987 [ + + ]: 1474776 : if (ignore_checksum_failure)
1988 : 12 : flags |= READ_BUFFERS_IGNORE_CHECKSUM_FAILURES;
1989 : :
1990 : :
1991 : : /*
1992 : : * To be allowed to report stats in the local completion callback we need
1993 : : * to prepare to report stats now. This ensures we can safely report the
1994 : : * checksum failure even in a critical section.
1995 : : */
1996 : 1474776 : pgstat_prepare_report_checksum_failure(operation->smgr->smgr_rlocator.locator.dbOid);
1997 : :
1998 : : /*
1999 : : * We must get an IO handle before StartBufferIO(), as pgaio_io_acquire()
2000 : : * might block, which we don't want after setting IO_IN_PROGRESS. If we
2001 : : * don't need to do the IO, we'll release the handle.
2002 : : *
2003 : : * If we need to wait for IO before we can get a handle, submit
2004 : : * already-staged IO first, so that other backends don't need to wait.
2005 : : * There wouldn't be a deadlock risk, as pgaio_io_acquire() just needs to
2006 : : * wait for already submitted IO, which doesn't require additional locks,
2007 : : * but it could still cause undesirable waits.
2008 : : *
2009 : : * A secondary benefit is that this would allow us to measure the time in
2010 : : * pgaio_io_acquire() without causing undue timer overhead in the common,
2011 : : * non-blocking, case. However, currently the pgstats infrastructure
2012 : : * doesn't really allow that, as it a) asserts that an operation can't
2013 : : * have time without operations b) doesn't have an API to report
2014 : : * "accumulated" time.
2015 : : */
2016 : 1474776 : ioh = pgaio_io_acquire_nb(CurrentResourceOwner, &operation->io_return);
2017 [ + + ]: 1474776 : if (unlikely(!ioh))
2018 : : {
2019 : 3441 : pgaio_submit_staged();
2020 : 3441 : ioh = pgaio_io_acquire(CurrentResourceOwner, &operation->io_return);
2021 : : }
2022 : :
39 andres@anarazel.de 2023 :GNC 1474776 : operation->foreign_io = false;
2024 : 1474776 : pgaio_wref_clear(&operation->io_wref);
2025 : :
2026 : : /*
2027 : : * Try to start IO on the first buffer in a new run of blocks. If AIO is
2028 : : * in progress, be it in this backend or another backend, we just
2029 : : * associate the wait reference with the operation and wait in
2030 : : * WaitReadBuffers(). This turns out to be important for performance in
2031 : : * two workloads:
2032 : : *
2033 : : * 1) A read stream that has to read the same block multiple times within
2034 : : * the readahead distance. This can happen e.g. for the table accesses of
2035 : : * an index scan.
2036 : : *
2037 : : * 2) Concurrent scans by multiple backends on the same relation.
2038 : : *
2039 : : * If we were to synchronously wait for the in-progress IO, we'd not be
2040 : : * able to keep enough I/O in flight.
2041 : : *
2042 : : * If we do find there is ongoing I/O for the buffer, we set up a 1-block
2043 : : * ReadBuffersOperation that WaitReadBuffers then can wait on.
2044 : : *
2045 : : * It's possible that another backend has started IO on the buffer but not
2046 : : * yet set its wait reference. In this case, we have no choice but to wait
2047 : : * for either the wait reference to be valid or the IO to be done.
2048 : : */
2049 : 1474776 : status = StartBufferIO(buffers[nblocks_done], true, true,
2050 : : &operation->io_wref);
2051 [ + + ]: 1474776 : if (status != BUFFER_IO_READY_FOR_IO)
2052 : : {
39 andres@anarazel.de 2053 :CBC 2675 : pgaio_io_release(ioh);
401 andres@anarazel.de 2054 :GNC 2675 : *nblocks_progress = 1;
39 2055 [ + + ]: 2675 : if (status == BUFFER_IO_ALREADY_DONE)
2056 : : {
2057 : : /*
2058 : : * Someone has already completed this block, we're done.
2059 : : *
2060 : : * When IO is necessary, ->nblocks_done is updated in
2061 : : * ProcessReadBuffersResult(), but that is not called if no IO is
2062 : : * necessary. Thus update here.
2063 : : */
2064 : 536 : operation->nblocks_done += 1;
2065 [ - + ]: 536 : Assert(operation->nblocks_done <= operation->nblocks);
2066 : :
2067 [ - + ]: 536 : Assert(!pgaio_wref_valid(&operation->io_wref));
2068 : :
2069 : : /*
2070 : : * Report and track this as a 'hit' for this backend, even though
2071 : : * it must have started out as a miss in PinBufferForBlock(). The
2072 : : * other backend will track this as a 'read'.
2073 : : */
2074 : 536 : TrackBufferHit(io_object, io_context,
2075 : 536 : operation->rel, operation->persistence,
2076 : : operation->smgr, operation->forknum,
2077 : : blocknum);
2078 : 536 : return false;
2079 : : }
2080 : :
2081 : : /* The IO is already in-progress */
2082 [ - + ]: 2139 : Assert(status == BUFFER_IO_IN_PROGRESS);
2083 [ - + ]: 2139 : Assert(pgaio_wref_valid(&operation->io_wref));
2084 : 2139 : operation->foreign_io = true;
2085 : :
2086 : 2139 : return true;
2087 : : }
2088 : :
40 2089 [ - + ]: 1472101 : Assert(io_buffers[0] == buffers[nblocks_done]);
2090 : 1472101 : io_pages[0] = BufferGetBlock(buffers[nblocks_done]);
2091 : 1472101 : io_buffers_len = 1;
2092 : :
2093 : : /*
2094 : : * NB: As little code as possible should be added between the
2095 : : * StartBufferIO() above, the further StartBufferIO()s below and the
2096 : : * smgrstartreadv(), as some of the buffers are now marked as
2097 : : * IO_IN_PROGRESS and will thus cause other backends to wait.
2098 : : */
2099 : :
2100 : : /*
2101 : : * How many neighboring-on-disk blocks can we scatter-read into other
2102 : : * buffers at the same time? In this case we don't wait if we see an I/O
2103 : : * already in progress (see comment above).
2104 : : */
2105 [ + + ]: 1654122 : for (int i = nblocks_done + 1; i < operation->nblocks; i++)
2106 : : {
2107 : : /* Must be consecutive block numbers. */
2108 [ - + ]: 182032 : Assert(BufferGetBlockNumber(buffers[i - 1]) ==
2109 : : BufferGetBlockNumber(buffers[i]) - 1);
2110 : :
39 2111 : 182032 : status = StartBufferIO(buffers[i], true, false, NULL);
2112 [ + + ]: 182032 : if (status != BUFFER_IO_READY_FOR_IO)
40 2113 : 11 : break;
2114 : :
2115 [ - + ]: 182021 : Assert(io_buffers[io_buffers_len] == buffers[i]);
2116 : :
2117 : 182021 : io_pages[io_buffers_len++] = BufferGetBlock(buffers[i]);
2118 : : }
2119 : :
2120 : : /* get a reference to wait for in WaitReadBuffers() */
2121 : 1472101 : pgaio_io_get_wref(ioh, &operation->io_wref);
2122 : :
2123 : : /* provide the list of buffers to the completion callbacks */
2124 : 1472101 : pgaio_io_set_handle_data_32(ioh, (uint32 *) io_buffers, io_buffers_len);
2125 : :
2126 [ + + ]: 1472101 : pgaio_io_register_callbacks(ioh,
2127 : : persistence == RELPERSISTENCE_TEMP ?
2128 : : PGAIO_HCB_LOCAL_BUFFER_READV :
2129 : : PGAIO_HCB_SHARED_BUFFER_READV,
2130 : : flags);
2131 : :
2132 : 1472101 : pgaio_io_set_flag(ioh, ioh_flags);
2133 : :
2134 : : /* ---
2135 : : * Even though we're trying to issue IO asynchronously, track the time
2136 : : * in smgrstartreadv():
2137 : : * - if io_method == IOMETHOD_SYNC, we will always perform the IO
2138 : : * immediately
2139 : : * - the io method might not support the IO (e.g. worker IO for a temp
2140 : : * table)
2141 : : * ---
2142 : : */
2143 : 1472101 : io_start = pgstat_prepare_io_time(track_io_timing);
2144 : 1472101 : smgrstartreadv(ioh, operation->smgr, forknum,
2145 : : blocknum,
2146 : : io_pages, io_buffers_len);
2147 : 1472086 : pgstat_count_io_op_time(io_object, io_context, IOOP_READ,
2148 : 1472086 : io_start, 1, io_buffers_len * BLCKSZ);
2149 : :
2150 [ + + ]: 1472086 : if (persistence == RELPERSISTENCE_TEMP)
2151 : 2842 : pgBufferUsage.local_blks_read += io_buffers_len;
2152 : : else
2153 : 1469244 : pgBufferUsage.shared_blks_read += io_buffers_len;
2154 : :
2155 : : /*
2156 : : * Track vacuum cost when issuing IO, not after waiting for it. Otherwise
2157 : : * we could end up issuing a lot of IO in a short timespan, despite a low
2158 : : * cost limit.
2159 : : */
2160 [ + + ]: 1472086 : if (VacuumCostActive)
2161 : 19139 : VacuumCostBalance += VacuumCostPageMiss * io_buffers_len;
2162 : :
2163 : 1472086 : *nblocks_progress = io_buffers_len;
2164 : :
2165 : 1472086 : return true;
2166 : : }
2167 : :
2168 : : /*
2169 : : * BufferAlloc -- subroutine for PinBufferForBlock. Handles lookup of a shared
2170 : : * buffer. If no buffer exists already, selects a replacement victim and
2171 : : * evicts the old page, but does NOT read in new page.
2172 : : *
2173 : : * "strategy" can be a buffer replacement strategy object, or NULL for
2174 : : * the default strategy. The selected buffer's usage_count is advanced when
2175 : : * using the default strategy, but otherwise possibly not (see PinBuffer).
2176 : : *
2177 : : * The returned buffer is pinned and is already marked as holding the
2178 : : * desired page. If it already did have the desired page, *foundPtr is
2179 : : * set true. Otherwise, *foundPtr is set false.
2180 : : *
2181 : : * io_context is passed as an output parameter to avoid calling
2182 : : * IOContextForStrategy() when there is a shared buffers hit and no IO
2183 : : * statistics need be captured.
2184 : : *
2185 : : * No locks are held either at entry or exit.
2186 : : */
2187 : : static pg_attribute_always_inline BufferDesc *
5606 rhaas@postgresql.org 2188 :CBC 82709194 : BufferAlloc(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
2189 : : BlockNumber blockNum,
2190 : : BufferAccessStrategy strategy,
2191 : : bool *foundPtr, IOContext io_context)
2192 : : {
2193 : : BufferTag newTag; /* identity of requested block */
2194 : : uint32 newHash; /* hash value for newTag */
2195 : : LWLock *newPartitionLock; /* buffer partition lock for it */
2196 : : int existing_buf_id;
2197 : : Buffer victim_buffer;
2198 : : BufferDesc *victim_buf_hdr;
2199 : : uint64 victim_buf_state;
110 andres@anarazel.de 2200 :GNC 82709194 : uint64 set_bits = 0;
2201 : :
2202 : : /* Make sure we will have room to remember the buffer pin */
909 heikki.linnakangas@i 2203 :CBC 82709194 : ResourceOwnerEnlarge(CurrentResourceOwner);
2204 : 82709194 : ReservePrivateRefCountEntry();
2205 : :
2206 : : /* create a tag so we can lookup the buffer */
1378 rhaas@postgresql.org 2207 : 82709194 : InitBufferTag(&newTag, &smgr->smgr_rlocator.locator, forkNum, blockNum);
2208 : :
2209 : : /* determine its hash code and partition lock ID */
7226 tgl@sss.pgh.pa.us 2210 : 82709194 : newHash = BufTableHashCode(&newTag);
2211 : 82709194 : newPartitionLock = BufMappingPartitionLock(newHash);
2212 : :
2213 : : /* see if the block is in the buffer pool already */
2214 : 82709194 : LWLockAcquire(newPartitionLock, LW_SHARED);
1126 andres@anarazel.de 2215 : 82709194 : existing_buf_id = BufTableLookup(&newTag, newHash);
2216 [ + + ]: 82709194 : if (existing_buf_id >= 0)
2217 : : {
2218 : : BufferDesc *buf;
2219 : : bool valid;
2220 : :
2221 : : /*
2222 : : * Found it. Now, pin the buffer so no one can steal it from the
2223 : : * buffer pool, and check to see if the correct data has been loaded
2224 : : * into the buffer.
2225 : : */
2226 : 80746854 : buf = GetBufferDescriptor(existing_buf_id);
2227 : :
209 andres@anarazel.de 2228 :GNC 80746854 : valid = PinBuffer(buf, strategy, false);
2229 : :
2230 : : /* Can release the mapping lock as soon as we've pinned it */
7226 tgl@sss.pgh.pa.us 2231 :CBC 80746854 : LWLockRelease(newPartitionLock);
2232 : :
3184 peter_e@gmx.net 2233 : 80746854 : *foundPtr = true;
2234 : :
7732 tgl@sss.pgh.pa.us 2235 [ + + ]: 80746854 : if (!valid)
2236 : : {
2237 : : /*
2238 : : * We can only get here if (a) someone else is still reading in
2239 : : * the page, (b) a previous read attempt failed, or (c) someone
2240 : : * called StartReadBuffers() but not yet WaitReadBuffers().
2241 : : */
762 tmunro@postgresql.or 2242 : 2388 : *foundPtr = false;
2243 : : }
2244 : :
10108 bruce@momjian.us 2245 : 80746854 : return buf;
2246 : : }
2247 : :
2248 : : /*
2249 : : * Didn't find it in the buffer pool. We'll have to initialize a new
2250 : : * buffer. Remember to unlock the mapping lock while doing the work.
2251 : : */
7226 tgl@sss.pgh.pa.us 2252 : 1962340 : LWLockRelease(newPartitionLock);
2253 : :
2254 : : /*
2255 : : * Acquire a victim buffer. Somebody else might try to do the same, we
2256 : : * don't hold any conflicting locks. If so we'll have to undo our work
2257 : : * later.
2258 : : */
1126 andres@anarazel.de 2259 : 1962340 : victim_buffer = GetVictimBuffer(strategy, io_context);
2260 : 1962340 : victim_buf_hdr = GetBufferDescriptor(victim_buffer - 1);
2261 : :
2262 : : /*
2263 : : * Try to make a hashtable entry for the buffer under its new tag. If
2264 : : * somebody else inserted another buffer for the tag, we'll release the
2265 : : * victim buffer we acquired and use the already inserted one.
2266 : : */
2267 : 1962340 : LWLockAcquire(newPartitionLock, LW_EXCLUSIVE);
2268 : 1962340 : existing_buf_id = BufTableInsert(&newTag, newHash, victim_buf_hdr->buf_id);
2269 [ + + ]: 1962340 : if (existing_buf_id >= 0)
2270 : : {
2271 : : BufferDesc *existing_buf_hdr;
2272 : : bool valid;
2273 : :
2274 : : /*
2275 : : * Got a collision. Someone has already done what we were about to do.
2276 : : * We'll just handle this as if it were found in the buffer pool in
2277 : : * the first place. First, give up the buffer we were planning to
2278 : : * use.
2279 : : *
2280 : : * We could do this after releasing the partition lock, but then we'd
2281 : : * have to call ResourceOwnerEnlarge() & ReservePrivateRefCountEntry()
2282 : : * before acquiring the lock, for the rare case of such a collision.
2283 : : */
2284 : 701 : UnpinBuffer(victim_buf_hdr);
2285 : :
2286 : : /* remaining code should match code at top of routine */
2287 : :
2288 : 701 : existing_buf_hdr = GetBufferDescriptor(existing_buf_id);
2289 : :
209 andres@anarazel.de 2290 :GNC 701 : valid = PinBuffer(existing_buf_hdr, strategy, false);
2291 : :
2292 : : /* Can release the mapping lock as soon as we've pinned it */
1126 andres@anarazel.de 2293 :CBC 701 : LWLockRelease(newPartitionLock);
2294 : :
2295 : 701 : *foundPtr = true;
2296 : :
2297 [ + + ]: 701 : if (!valid)
2298 : : {
2299 : : /*
2300 : : * We can only get here if (a) someone else is still reading in
2301 : : * the page, (b) a previous read attempt failed, or (c) someone
2302 : : * called StartReadBuffers() but not yet WaitReadBuffers().
2303 : : */
762 tmunro@postgresql.or 2304 : 351 : *foundPtr = false;
2305 : : }
2306 : :
1126 andres@anarazel.de 2307 : 701 : return existing_buf_hdr;
2308 : : }
2309 : :
2310 : : /*
2311 : : * Need to lock the buffer header too in order to change its tag.
2312 : : */
2313 : 1961639 : victim_buf_state = LockBufHdr(victim_buf_hdr);
2314 : :
2315 : : /* some sanity checks while we hold the buffer header lock */
2316 [ - + ]: 1961639 : Assert(BUF_STATE_GET_REFCOUNT(victim_buf_state) == 1);
2317 [ - + ]: 1961639 : Assert(!(victim_buf_state & (BM_TAG_VALID | BM_VALID | BM_DIRTY | BM_IO_IN_PROGRESS)));
2318 : :
2319 : 1961639 : victim_buf_hdr->tag = newTag;
2320 : :
2321 : : /*
2322 : : * Make sure BM_PERMANENT is set for buffers that must be written at every
2323 : : * checkpoint. Unlogged buffers only need to be written at shutdown
2324 : : * checkpoints, except for their "init" forks, which need to be treated
2325 : : * just like permanent relations.
2326 : : */
180 andres@anarazel.de 2327 :GNC 1961639 : set_bits |= BM_TAG_VALID | BUF_USAGECOUNT_ONE;
3339 rhaas@postgresql.org 2328 [ + + - + ]:CBC 1961639 : if (relpersistence == RELPERSISTENCE_PERMANENT || forkNum == INIT_FORKNUM)
180 andres@anarazel.de 2329 :GNC 1961279 : set_bits |= BM_PERMANENT;
2330 : :
2331 : 1961639 : UnlockBufHdrExt(victim_buf_hdr, victim_buf_state,
2332 : : set_bits, 0, 0);
2333 : :
7226 tgl@sss.pgh.pa.us 2334 :CBC 1961639 : LWLockRelease(newPartitionLock);
2335 : :
2336 : : /*
2337 : : * Buffer contents are currently invalid.
2338 : : */
762 tmunro@postgresql.or 2339 : 1961639 : *foundPtr = false;
2340 : :
1126 andres@anarazel.de 2341 : 1961639 : return victim_buf_hdr;
2342 : : }
2343 : :
2344 : : /*
2345 : : * InvalidateBuffer -- mark a shared buffer invalid.
2346 : : *
2347 : : * The buffer header spinlock must be held at entry. We drop it before
2348 : : * returning. (This is sane because the caller must have locked the
2349 : : * buffer in order to be sure it should be dropped.)
2350 : : *
2351 : : * This is used only in contexts such as dropping a relation. We assume
2352 : : * that no other backend could possibly be interested in using the page,
2353 : : * so the only reason the buffer might be pinned is if someone else is
2354 : : * trying to write it out. We have to let them finish before we can
2355 : : * reclaim the buffer.
2356 : : *
2357 : : * The buffer could get reclaimed by someone else while we are waiting
2358 : : * to acquire the necessary locks; if so, don't mess it up.
2359 : : */
2360 : : static void
3823 rhaas@postgresql.org 2361 : 127888 : InvalidateBuffer(BufferDesc *buf)
2362 : : {
2363 : : BufferTag oldTag;
2364 : : uint32 oldHash; /* hash value for oldTag */
2365 : : LWLock *oldPartitionLock; /* buffer partition lock for it */
2366 : : uint32 oldFlags;
2367 : : uint64 buf_state;
2368 : :
2369 : : /* Save the original buffer tag before dropping the spinlock */
7732 tgl@sss.pgh.pa.us 2370 : 127888 : oldTag = buf->tag;
2371 : :
180 andres@anarazel.de 2372 :GNC 127888 : UnlockBufHdr(buf);
2373 : :
2374 : : /*
2375 : : * Need to compute the old tag's hashcode and partition lock ID. XXX is it
2376 : : * worth storing the hashcode in BufferDesc so we need not recompute it
2377 : : * here? Probably not.
2378 : : */
7226 tgl@sss.pgh.pa.us 2379 :CBC 127888 : oldHash = BufTableHashCode(&oldTag);
2380 : 127888 : oldPartitionLock = BufMappingPartitionLock(oldHash);
2381 : :
7732 2382 : 127890 : retry:
2383 : :
2384 : : /*
2385 : : * Acquire exclusive mapping lock in preparation for changing the buffer's
2386 : : * association.
2387 : : */
7226 2388 : 127890 : LWLockAcquire(oldPartitionLock, LW_EXCLUSIVE);
2389 : :
2390 : : /* Re-lock the buffer header */
3677 andres@anarazel.de 2391 : 127890 : buf_state = LockBufHdr(buf);
2392 : :
2393 : : /* If it's changed while we were waiting for lock, do nothing */
1378 rhaas@postgresql.org 2394 [ + + ]: 127890 : if (!BufferTagsEqual(&buf->tag, &oldTag))
2395 : : {
180 andres@anarazel.de 2396 :GNC 1 : UnlockBufHdr(buf);
7226 tgl@sss.pgh.pa.us 2397 :CBC 1 : LWLockRelease(oldPartitionLock);
7732 2398 : 1 : return;
2399 : : }
2400 : :
2401 : : /*
2402 : : * We assume the reason for it to be pinned is that either we were
2403 : : * asynchronously reading the page in before erroring out or someone else
2404 : : * is flushing the page out. Wait for the IO to finish. (This could be
2405 : : * an infinite loop if the refcount is messed up... it would be nice to
2406 : : * time out after awhile, but there seems no way to be sure how many loops
2407 : : * may be needed. Note that if the other guy has pinned the buffer but
2408 : : * not yet done StartBufferIO, WaitIO will fall through and we'll
2409 : : * effectively be busy-looping here.)
2410 : : */
3677 andres@anarazel.de 2411 [ + + ]: 127889 : if (BUF_STATE_GET_REFCOUNT(buf_state) != 0)
2412 : : {
180 andres@anarazel.de 2413 :GNC 2 : UnlockBufHdr(buf);
7226 tgl@sss.pgh.pa.us 2414 :CBC 2 : LWLockRelease(oldPartitionLock);
2415 : : /* safety check: should definitely not be our *own* pin */
3919 andres@anarazel.de 2416 [ - + ]: 2 : if (GetPrivateRefCount(BufferDescriptorGetBuffer(buf)) > 0)
7718 tgl@sss.pgh.pa.us 2417 [ # # ]:UBC 0 : elog(ERROR, "buffer is pinned in InvalidateBuffer");
7732 tgl@sss.pgh.pa.us 2418 :CBC 2 : WaitIO(buf);
2419 : 2 : goto retry;
2420 : : }
2421 : :
2422 : : /*
2423 : : * An invalidated buffer should not have any backends waiting to lock the
2424 : : * buffer, therefore BM_LOCK_WAKE_IN_PROGRESS should not be set.
2425 : : */
110 andres@anarazel.de 2426 [ - + ]:GNC 127887 : Assert(!(buf_state & BM_LOCK_WAKE_IN_PROGRESS));
2427 : :
2428 : : /*
2429 : : * Clear out the buffer's tag and flags. We must do this to ensure that
2430 : : * linear scans of the buffer array don't think the buffer is valid.
2431 : : */
3677 andres@anarazel.de 2432 :CBC 127887 : oldFlags = buf_state & BUF_FLAG_MASK;
1378 rhaas@postgresql.org 2433 : 127887 : ClearBufferTag(&buf->tag);
2434 : :
180 andres@anarazel.de 2435 :GNC 127887 : UnlockBufHdrExt(buf, buf_state,
2436 : : 0,
2437 : : BUF_FLAG_MASK | BUF_USAGECOUNT_MASK,
2438 : : 0);
2439 : :
2440 : : /*
2441 : : * Remove the buffer from the lookup hashtable, if it was in there.
2442 : : */
7732 tgl@sss.pgh.pa.us 2443 [ + - ]:CBC 127887 : if (oldFlags & BM_TAG_VALID)
7226 2444 : 127887 : BufTableDelete(&oldTag, oldHash);
2445 : :
2446 : : /*
2447 : : * Done with mapping lock.
2448 : : */
2449 : 127887 : LWLockRelease(oldPartitionLock);
2450 : : }
2451 : :
2452 : : /*
2453 : : * Helper routine for GetVictimBuffer()
2454 : : *
2455 : : * Needs to be called on a buffer with a valid tag, pinned, but without the
2456 : : * buffer header spinlock held.
2457 : : *
2458 : : * Returns true if the buffer can be reused, in which case the buffer is only
2459 : : * pinned by this backend and marked as invalid, false otherwise.
2460 : : */
2461 : : static bool
1126 andres@anarazel.de 2462 : 1407780 : InvalidateVictimBuffer(BufferDesc *buf_hdr)
2463 : : {
2464 : : uint64 buf_state;
2465 : : uint32 hash;
2466 : : LWLock *partition_lock;
2467 : : BufferTag tag;
2468 : :
2469 [ - + ]: 1407780 : Assert(GetPrivateRefCount(BufferDescriptorGetBuffer(buf_hdr)) == 1);
2470 : :
2471 : : /* have buffer pinned, so it's safe to read tag without lock */
2472 : 1407780 : tag = buf_hdr->tag;
2473 : :
2474 : 1407780 : hash = BufTableHashCode(&tag);
2475 : 1407780 : partition_lock = BufMappingPartitionLock(hash);
2476 : :
2477 : 1407780 : LWLockAcquire(partition_lock, LW_EXCLUSIVE);
2478 : :
2479 : : /* lock the buffer header */
2480 : 1407780 : buf_state = LockBufHdr(buf_hdr);
2481 : :
2482 : : /*
2483 : : * We have the buffer pinned nobody else should have been able to unset
2484 : : * this concurrently.
2485 : : */
2486 [ - + ]: 1407780 : Assert(buf_state & BM_TAG_VALID);
2487 [ - + ]: 1407780 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
2488 [ - + ]: 1407780 : Assert(BufferTagsEqual(&buf_hdr->tag, &tag));
2489 : :
2490 : : /*
2491 : : * If somebody else pinned the buffer since, or even worse, dirtied it,
2492 : : * give up on this buffer: It's clearly in use.
2493 : : */
2494 [ + + + + ]: 1407780 : if (BUF_STATE_GET_REFCOUNT(buf_state) != 1 || (buf_state & BM_DIRTY))
2495 : : {
2496 [ - + ]: 535 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
2497 : :
180 andres@anarazel.de 2498 :GNC 535 : UnlockBufHdr(buf_hdr);
1126 andres@anarazel.de 2499 :CBC 535 : LWLockRelease(partition_lock);
2500 : :
2501 : 535 : return false;
2502 : : }
2503 : :
2504 : : /*
2505 : : * An invalidated buffer should not have any backends waiting to lock the
2506 : : * buffer, therefore BM_LOCK_WAKE_IN_PROGRESS should not be set.
2507 : : */
110 andres@anarazel.de 2508 [ - + ]:GNC 1407245 : Assert(!(buf_state & BM_LOCK_WAKE_IN_PROGRESS));
2509 : :
2510 : : /*
2511 : : * Clear out the buffer's tag and flags and usagecount. This is not
2512 : : * strictly required, as BM_TAG_VALID/BM_VALID needs to be checked before
2513 : : * doing anything with the buffer. But currently it's beneficial, as the
2514 : : * cheaper pre-check for several linear scans of shared buffers use the
2515 : : * tag (see e.g. FlushDatabaseBuffers()).
2516 : : */
1126 andres@anarazel.de 2517 :CBC 1407245 : ClearBufferTag(&buf_hdr->tag);
180 andres@anarazel.de 2518 :GNC 1407245 : UnlockBufHdrExt(buf_hdr, buf_state,
2519 : : 0,
2520 : : BUF_FLAG_MASK | BUF_USAGECOUNT_MASK,
2521 : : 0);
2522 : :
1126 andres@anarazel.de 2523 [ - + ]:CBC 1407245 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
2524 : :
2525 : : /* finally delete buffer from the buffer mapping table */
2526 : 1407245 : BufTableDelete(&tag, hash);
2527 : :
2528 : 1407245 : LWLockRelease(partition_lock);
2529 : :
110 andres@anarazel.de 2530 :GNC 1407245 : buf_state = pg_atomic_read_u64(&buf_hdr->state);
1126 andres@anarazel.de 2531 [ - + ]:CBC 1407245 : Assert(!(buf_state & (BM_DIRTY | BM_VALID | BM_TAG_VALID)));
2532 [ - + ]: 1407245 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
110 andres@anarazel.de 2533 [ - + ]:GNC 1407245 : Assert(BUF_STATE_GET_REFCOUNT(pg_atomic_read_u64(&buf_hdr->state)) > 0);
2534 : :
1126 andres@anarazel.de 2535 :CBC 1407245 : return true;
2536 : : }
2537 : :
2538 : : static Buffer
2539 : 2241606 : GetVictimBuffer(BufferAccessStrategy strategy, IOContext io_context)
2540 : : {
2541 : : BufferDesc *buf_hdr;
2542 : : Buffer buf;
2543 : : uint64 buf_state;
2544 : : bool from_ring;
2545 : :
2546 : : /*
2547 : : * Ensure, before we pin a victim buffer, that there's a free refcount
2548 : : * entry and resource owner slot for the pin.
2549 : : */
2550 : 2241606 : ReservePrivateRefCountEntry();
909 heikki.linnakangas@i 2551 : 2241606 : ResourceOwnerEnlarge(CurrentResourceOwner);
2552 : :
2553 : : /* we return here if a prospective victim buffer gets used concurrently */
1126 andres@anarazel.de 2554 : 23035 : again:
2555 : :
2556 : : /*
2557 : : * Select a victim buffer. The buffer is returned pinned and owned by
2558 : : * this backend.
2559 : : */
2560 : 2264641 : buf_hdr = StrategyGetBuffer(strategy, &buf_state, &from_ring);
2561 : 2264641 : buf = BufferDescriptorGetBuffer(buf_hdr);
2562 : :
2563 : : /*
2564 : : * We shouldn't have any other pins for this buffer.
2565 : : */
2566 : 2264641 : CheckBufferIsPinnedOnce(buf);
2567 : :
2568 : : /*
2569 : : * If the buffer was dirty, try to write it out. There is a race
2570 : : * condition here, another backend could dirty the buffer between
2571 : : * StrategyGetBuffer() checking that it is not in use and invalidating the
2572 : : * buffer below. That's addressed by InvalidateVictimBuffer() verifying
2573 : : * that the buffer is not dirty.
2574 : : */
2575 [ + + ]: 2264641 : if (buf_state & BM_DIRTY)
2576 : : {
2577 [ - + ]: 371125 : Assert(buf_state & BM_TAG_VALID);
2578 [ - + ]: 371125 : Assert(buf_state & BM_VALID);
2579 : :
2580 : : /*
2581 : : * We need a share-exclusive lock on the buffer contents to write it
2582 : : * out (else we might write invalid data, eg because someone else is
2583 : : * compacting the page contents while we write). We must use a
2584 : : * conditional lock acquisition here to avoid deadlock. Even though
2585 : : * the buffer was not pinned (and therefore surely not locked) when
2586 : : * StrategyGetBuffer returned it, someone else could have pinned and
2587 : : * (share-)exclusive-locked it by the time we get here. If we try to
2588 : : * get the lock unconditionally, we'd block waiting for them; if they
2589 : : * later block waiting for us, deadlock ensues. (This has been
2590 : : * observed to happen when two backends are both trying to split btree
2591 : : * index pages, and the second one just happens to be trying to split
2592 : : * the page the first one got from StrategyGetBuffer.)
2593 : : */
56 andres@anarazel.de 2594 [ - + ]:GNC 371125 : if (!BufferLockConditional(buf, buf_hdr, BUFFER_LOCK_SHARE_EXCLUSIVE))
2595 : : {
2596 : : /*
2597 : : * Someone else has locked the buffer, so give it up and loop back
2598 : : * to get another one.
2599 : : */
1126 andres@anarazel.de 2600 :UBC 0 : UnpinBuffer(buf_hdr);
2601 : 0 : goto again;
2602 : : }
2603 : :
2604 : : /*
2605 : : * If using a nondefault strategy, and this victim came from the
2606 : : * strategy ring, let the strategy decide whether to reject it when
2607 : : * reusing it would require a WAL flush. This only applies to
2608 : : * permanent buffers; unlogged buffers can have fake LSNs, so
2609 : : * XLogNeedsFlush() is not meaningful for them.
2610 : : *
2611 : : * We need to hold the content lock in at least share-exclusive mode
2612 : : * to safely inspect the page LSN, so this couldn't have been done
2613 : : * inside StrategyGetBuffer().
2614 : : */
55 melanieplageman@gmai 2615 [ + + + + ]:GNC 371125 : if (strategy && from_ring &&
2616 [ + - + + ]: 191998 : buf_state & BM_PERMANENT &&
2617 [ + + ]: 122826 : XLogNeedsFlush(BufferGetLSN(buf_hdr)) &&
2618 : 26827 : StrategyRejectBuffer(strategy, buf_hdr, from_ring))
2619 : : {
39 andres@anarazel.de 2620 : 22500 : UnlockReleaseBuffer(buf);
55 melanieplageman@gmai 2621 : 22500 : goto again;
2622 : : }
2623 : :
2624 : : /* OK, do the I/O */
1126 andres@anarazel.de 2625 :CBC 348625 : FlushBuffer(buf_hdr, NULL, IOOBJECT_RELATION, io_context);
110 andres@anarazel.de 2626 :GNC 348625 : LockBuffer(buf, BUFFER_LOCK_UNLOCK);
2627 : :
1084 andres@anarazel.de 2628 :CBC 348625 : ScheduleBufferTagForWriteback(&BackendWritebackContext, io_context,
2629 : : &buf_hdr->tag);
2630 : : }
2631 : :
2632 : :
1126 2633 [ + + ]: 2242141 : if (buf_state & BM_VALID)
2634 : : {
2635 : : /*
2636 : : * When a BufferAccessStrategy is in use, blocks evicted from shared
2637 : : * buffers are counted as IOOP_EVICT in the corresponding context
2638 : : * (e.g. IOCONTEXT_BULKWRITE). Shared buffers are evicted by a
2639 : : * strategy in two cases: 1) while initially claiming buffers for the
2640 : : * strategy ring 2) to replace an existing strategy ring buffer
2641 : : * because it is pinned or in use and cannot be reused.
2642 : : *
2643 : : * Blocks evicted from buffers already in the strategy ring are
2644 : : * counted as IOOP_REUSE in the corresponding strategy context.
2645 : : *
2646 : : * At this point, we can accurately count evictions and reuses,
2647 : : * because we have successfully claimed the valid buffer. Previously,
2648 : : * we may have been forced to release the buffer due to concurrent
2649 : : * pinners or erroring out.
2650 : : */
2651 : 1404984 : pgstat_count_io_op(IOOBJECT_RELATION, io_context,
476 michael@paquier.xyz 2652 [ + + ]: 1404984 : from_ring ? IOOP_REUSE : IOOP_EVICT, 1, 0);
2653 : : }
2654 : :
2655 : : /*
2656 : : * If the buffer has an entry in the buffer mapping table, delete it. This
2657 : : * can fail because another backend could have pinned or dirtied the
2658 : : * buffer.
2659 : : */
1126 andres@anarazel.de 2660 [ + + + + ]: 2242141 : if ((buf_state & BM_TAG_VALID) && !InvalidateVictimBuffer(buf_hdr))
2661 : : {
2662 : 535 : UnpinBuffer(buf_hdr);
2663 : 535 : goto again;
2664 : : }
2665 : :
2666 : : /* a final set of sanity checks */
2667 : : #ifdef USE_ASSERT_CHECKING
110 andres@anarazel.de 2668 :GNC 2241606 : buf_state = pg_atomic_read_u64(&buf_hdr->state);
2669 : :
1126 andres@anarazel.de 2670 [ - + ]:CBC 2241606 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) == 1);
2671 [ - + ]: 2241606 : Assert(!(buf_state & (BM_TAG_VALID | BM_VALID | BM_DIRTY)));
2672 : :
2673 : 2241606 : CheckBufferIsPinnedOnce(buf);
2674 : : #endif
2675 : :
2676 : 2241606 : return buf;
2677 : : }
2678 : :
2679 : : /*
2680 : : * Return the maximum number of buffers that a backend should try to pin once,
2681 : : * to avoid exceeding its fair share. This is the highest value that
2682 : : * GetAdditionalPinLimit() could ever return. Note that it may be zero on a
2683 : : * system with a very small buffer pool relative to max_connections.
2684 : : */
2685 : : uint32
417 tmunro@postgresql.or 2686 : 656230 : GetPinLimit(void)
2687 : : {
2688 : 656230 : return MaxProportionalPins;
2689 : : }
2690 : :
2691 : : /*
2692 : : * Return the maximum number of additional buffers that this backend should
2693 : : * pin if it wants to stay under the per-backend limit, considering the number
2694 : : * of buffers it has already pinned. Unlike LimitAdditionalPins(), the limit
2695 : : * return by this function can be zero.
2696 : : */
2697 : : uint32
2698 : 3555326 : GetAdditionalPinLimit(void)
2699 : : {
2700 : : uint32 estimated_pins_held;
2701 : :
2702 : : /*
2703 : : * We get the number of "overflowed" pins for free, but don't know the
2704 : : * number of pins in PrivateRefCountArray. The cost of calculating that
2705 : : * exactly doesn't seem worth it, so just assume the max.
2706 : : */
2707 : 3555326 : estimated_pins_held = PrivateRefCountOverflowed + REFCOUNT_ARRAY_ENTRIES;
2708 : :
2709 : : /* Is this backend already holding more than its fair share? */
2710 [ + + ]: 3555326 : if (estimated_pins_held > MaxProportionalPins)
2711 : 1489615 : return 0;
2712 : :
2713 : 2065711 : return MaxProportionalPins - estimated_pins_held;
2714 : : }
2715 : :
2716 : : /*
2717 : : * Limit the number of pins a batch operation may additionally acquire, to
2718 : : * avoid running out of pinnable buffers.
2719 : : *
2720 : : * One additional pin is always allowed, on the assumption that the operation
2721 : : * requires at least one to make progress.
2722 : : */
2723 : : void
1126 andres@anarazel.de 2724 : 252381 : LimitAdditionalPins(uint32 *additional_pins)
2725 : : {
2726 : : uint32 limit;
2727 : :
2728 [ + + ]: 252381 : if (*additional_pins <= 1)
2729 : 236863 : return;
2730 : :
417 tmunro@postgresql.or 2731 : 15518 : limit = GetAdditionalPinLimit();
2732 : 15518 : limit = Max(limit, 1);
2733 [ + + ]: 15518 : if (limit < *additional_pins)
2734 : 10037 : *additional_pins = limit;
2735 : : }
2736 : :
2737 : : /*
2738 : : * Logic shared between ExtendBufferedRelBy(), ExtendBufferedRelTo(). Just to
2739 : : * avoid duplicating the tracing and relpersistence related logic.
2740 : : */
2741 : : static BlockNumber
986 2742 : 268393 : ExtendBufferedRelCommon(BufferManagerRelation bmr,
2743 : : ForkNumber fork,
2744 : : BufferAccessStrategy strategy,
2745 : : uint32 flags,
2746 : : uint32 extend_by,
2747 : : BlockNumber extend_upto,
2748 : : Buffer *buffers,
2749 : : uint32 *extended_by)
2750 : : {
2751 : : BlockNumber first_block;
2752 : :
2753 : : TRACE_POSTGRESQL_BUFFER_EXTEND_START(fork,
2754 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.spcOid,
2755 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.dbOid,
2756 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.relNumber,
2757 : : BMR_GET_SMGR(bmr)->smgr_rlocator.backend,
2758 : : extend_by);
2759 : :
2760 [ + + ]: 268393 : if (bmr.relpersistence == RELPERSISTENCE_TEMP)
2761 : 16012 : first_block = ExtendBufferedRelLocal(bmr, fork, flags,
2762 : : extend_by, extend_upto,
2763 : : buffers, &extend_by);
2764 : : else
2765 : 252381 : first_block = ExtendBufferedRelShared(bmr, fork, strategy, flags,
2766 : : extend_by, extend_upto,
2767 : : buffers, &extend_by);
1126 andres@anarazel.de 2768 : 268393 : *extended_by = extend_by;
2769 : :
2770 : : TRACE_POSTGRESQL_BUFFER_EXTEND_DONE(fork,
2771 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.spcOid,
2772 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.dbOid,
2773 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.relNumber,
2774 : : BMR_GET_SMGR(bmr)->smgr_rlocator.backend,
2775 : : *extended_by,
2776 : : first_block);
2777 : :
2778 : 268393 : return first_block;
2779 : : }
2780 : :
2781 : : /*
2782 : : * Implementation of ExtendBufferedRelBy() and ExtendBufferedRelTo() for
2783 : : * shared buffers.
2784 : : */
2785 : : static BlockNumber
986 tmunro@postgresql.or 2786 : 252381 : ExtendBufferedRelShared(BufferManagerRelation bmr,
2787 : : ForkNumber fork,
2788 : : BufferAccessStrategy strategy,
2789 : : uint32 flags,
2790 : : uint32 extend_by,
2791 : : BlockNumber extend_upto,
2792 : : Buffer *buffers,
2793 : : uint32 *extended_by)
2794 : : {
2795 : : BlockNumber first_block;
1126 andres@anarazel.de 2796 : 252381 : IOContext io_context = IOContextForStrategy(strategy);
2797 : : instr_time io_start;
2798 : :
2799 : 252381 : LimitAdditionalPins(&extend_by);
2800 : :
2801 : : /*
2802 : : * Acquire victim buffers for extension without holding extension lock.
2803 : : * Writing out victim buffers is the most expensive part of extending the
2804 : : * relation, particularly when doing so requires WAL flushes. Zeroing out
2805 : : * the buffers is also quite expensive, so do that before holding the
2806 : : * extension lock as well.
2807 : : *
2808 : : * These pages are pinned by us and not valid. While we hold the pin they
2809 : : * can't be acquired as victim buffers by another backend.
2810 : : */
2811 [ + + ]: 531647 : for (uint32 i = 0; i < extend_by; i++)
2812 : : {
2813 : : Block buf_block;
2814 : :
2815 : 279266 : buffers[i] = GetVictimBuffer(strategy, io_context);
2816 : 279266 : buf_block = BufHdrGetBlock(GetBufferDescriptor(buffers[i] - 1));
2817 : :
2818 : : /* new buffers are zero-filled */
447 peter@eisentraut.org 2819 [ + - + - : 279266 : MemSet(buf_block, 0, BLCKSZ);
+ - - + -
- ]
2820 : : }
2821 : :
2822 : : /*
2823 : : * Lock relation against concurrent extensions, unless requested not to.
2824 : : *
2825 : : * We use the same extension lock for all forks. That's unnecessarily
2826 : : * restrictive, but currently extensions for forks don't happen often
2827 : : * enough to make it worth locking more granularly.
2828 : : *
2829 : : * Note that another backend might have extended the relation by the time
2830 : : * we get the lock.
2831 : : */
1126 andres@anarazel.de 2832 [ + + ]: 252381 : if (!(flags & EB_SKIP_EXTENSION_LOCK))
986 tmunro@postgresql.or 2833 : 196754 : LockRelationForExtension(bmr.rel, ExclusiveLock);
2834 : :
2835 : : /*
2836 : : * If requested, invalidate size cache, so that smgrnblocks asks the
2837 : : * kernel.
2838 : : */
1126 andres@anarazel.de 2839 [ + + ]: 252381 : if (flags & EB_CLEAR_SIZE_CACHE)
196 alvherre@kurilemu.de 2840 [ + - ]:GNC 9955 : BMR_GET_SMGR(bmr)->smgr_cached_nblocks[fork] = InvalidBlockNumber;
2841 : :
2842 [ + + ]: 252381 : first_block = smgrnblocks(BMR_GET_SMGR(bmr), fork);
2843 : :
2844 : : /*
2845 : : * Now that we have the accurate relation size, check if the caller wants
2846 : : * us to extend to only up to a specific size. If there were concurrent
2847 : : * extensions, we might have acquired too many buffers and need to release
2848 : : * them.
2849 : : */
1126 andres@anarazel.de 2850 [ + + ]:CBC 252381 : if (extend_upto != InvalidBlockNumber)
2851 : : {
2852 : 57785 : uint32 orig_extend_by = extend_by;
2853 : :
2854 [ - + ]: 57785 : if (first_block > extend_upto)
1126 andres@anarazel.de 2855 :UBC 0 : extend_by = 0;
1126 andres@anarazel.de 2856 [ + + ]:CBC 57785 : else if ((uint64) first_block + extend_by > extend_upto)
2857 : 9 : extend_by = extend_upto - first_block;
2858 : :
2859 [ + + ]: 57804 : for (uint32 i = extend_by; i < orig_extend_by; i++)
2860 : : {
2861 : 19 : BufferDesc *buf_hdr = GetBufferDescriptor(buffers[i] - 1);
2862 : :
2863 : 19 : UnpinBuffer(buf_hdr);
2864 : : }
2865 : :
2866 [ + + ]: 57785 : if (extend_by == 0)
2867 : : {
2868 [ + - ]: 9 : if (!(flags & EB_SKIP_EXTENSION_LOCK))
986 tmunro@postgresql.or 2869 : 9 : UnlockRelationForExtension(bmr.rel, ExclusiveLock);
1126 andres@anarazel.de 2870 : 9 : *extended_by = extend_by;
2871 : 9 : return first_block;
2872 : : }
2873 : : }
2874 : :
2875 : : /* Fail if relation is already at maximum possible length */
2876 [ - + ]: 252372 : if ((uint64) first_block + extend_by >= MaxBlockNumber)
1126 andres@anarazel.de 2877 [ # # # # :UBC 0 : ereport(ERROR,
# # # # #
# ]
2878 : : (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
2879 : : errmsg("cannot extend relation %s beyond %u blocks",
2880 : : relpath(BMR_GET_SMGR(bmr)->smgr_rlocator, fork).str,
2881 : : MaxBlockNumber)));
2882 : :
2883 : : /*
2884 : : * Insert buffers into buffer table, mark as IO_IN_PROGRESS.
2885 : : *
2886 : : * This needs to happen before we extend the relation, because as soon as
2887 : : * we do, other backends can start to read in those pages.
2888 : : */
959 peter@eisentraut.org 2889 [ + + ]:CBC 531619 : for (uint32 i = 0; i < extend_by; i++)
2890 : : {
1126 andres@anarazel.de 2891 : 279247 : Buffer victim_buf = buffers[i];
2892 : 279247 : BufferDesc *victim_buf_hdr = GetBufferDescriptor(victim_buf - 1);
2893 : : BufferTag tag;
2894 : : uint32 hash;
2895 : : LWLock *partition_lock;
2896 : : int existing_id;
2897 : :
2898 : : /* in case we need to pin an existing buffer below */
909 heikki.linnakangas@i 2899 : 279247 : ResourceOwnerEnlarge(CurrentResourceOwner);
2900 : 279247 : ReservePrivateRefCountEntry();
2901 : :
196 alvherre@kurilemu.de 2902 [ + + ]:GNC 279247 : InitBufferTag(&tag, &BMR_GET_SMGR(bmr)->smgr_rlocator.locator, fork,
2903 : : first_block + i);
1126 andres@anarazel.de 2904 :CBC 279247 : hash = BufTableHashCode(&tag);
2905 : 279247 : partition_lock = BufMappingPartitionLock(hash);
2906 : :
2907 : 279247 : LWLockAcquire(partition_lock, LW_EXCLUSIVE);
2908 : :
2909 : 279247 : existing_id = BufTableInsert(&tag, hash, victim_buf_hdr->buf_id);
2910 : :
2911 : : /*
2912 : : * We get here only in the corner case where we are trying to extend
2913 : : * the relation but we found a pre-existing buffer. This can happen
2914 : : * because a prior attempt at extending the relation failed, and
2915 : : * because mdread doesn't complain about reads beyond EOF (when
2916 : : * zero_damaged_pages is ON) and so a previous attempt to read a block
2917 : : * beyond EOF could have left a "valid" zero-filled buffer.
2918 : : *
2919 : : * This has also been observed when relation was overwritten by
2920 : : * external process. Since the legitimate cases should always have
2921 : : * left a zero-filled buffer, complain if not PageIsNew.
2922 : : */
2923 [ - + ]: 279247 : if (existing_id >= 0)
2924 : : {
1126 andres@anarazel.de 2925 :UBC 0 : BufferDesc *existing_hdr = GetBufferDescriptor(existing_id);
2926 : : Block buf_block;
2927 : : bool valid;
2928 : :
2929 : : /*
2930 : : * Pin the existing buffer before releasing the partition lock,
2931 : : * preventing it from being evicted.
2932 : : */
209 andres@anarazel.de 2933 :UNC 0 : valid = PinBuffer(existing_hdr, strategy, false);
2934 : :
1126 andres@anarazel.de 2935 :UBC 0 : LWLockRelease(partition_lock);
2936 : 0 : UnpinBuffer(victim_buf_hdr);
2937 : :
2938 : 0 : buffers[i] = BufferDescriptorGetBuffer(existing_hdr);
2939 : 0 : buf_block = BufHdrGetBlock(existing_hdr);
2940 : :
2941 [ # # # # ]: 0 : if (valid && !PageIsNew((Page) buf_block))
2942 [ # # # # : 0 : ereport(ERROR,
# # # # #
# ]
2943 : : (errmsg("unexpected data beyond EOF in block %u of relation \"%s\"",
2944 : : existing_hdr->tag.blockNum,
2945 : : relpath(BMR_GET_SMGR(bmr)->smgr_rlocator, fork).str)));
2946 : :
2947 : : /*
2948 : : * We *must* do smgr[zero]extend before succeeding, else the page
2949 : : * will not be reserved by the kernel, and the next P_NEW call
2950 : : * will decide to return the same page. Clear the BM_VALID bit,
2951 : : * do StartSharedBufferIO() and proceed.
2952 : : *
2953 : : * Loop to handle the very small possibility that someone re-sets
2954 : : * BM_VALID between our clearing it and StartSharedBufferIO
2955 : : * inspecting it.
2956 : : */
2957 : : while (true)
1126 andres@anarazel.de 2958 :UIC 0 : {
2959 : : StartBufferIOResult sbres;
2960 : :
110 andres@anarazel.de 2961 :UNC 0 : pg_atomic_fetch_and_u64(&existing_hdr->state, ~BM_VALID);
2962 : :
39 2963 : 0 : sbres = StartSharedBufferIO(existing_hdr, true, true, NULL);
2964 : :
2965 [ # # ]: 0 : if (sbres != BUFFER_IO_ALREADY_DONE)
2966 : 0 : break;
2967 : : }
2968 : : }
2969 : : else
2970 : : {
2971 : : uint64 buf_state;
110 andres@anarazel.de 2972 :GNC 279247 : uint64 set_bits = 0;
2973 : :
1126 andres@anarazel.de 2974 :CBC 279247 : buf_state = LockBufHdr(victim_buf_hdr);
2975 : :
2976 : : /* some sanity checks while we hold the buffer header lock */
55 andres@anarazel.de 2977 [ - + ]:GNC 279247 : Assert(!(buf_state & (BM_VALID | BM_TAG_VALID | BM_DIRTY)));
1126 andres@anarazel.de 2978 [ - + ]:CBC 279247 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) == 1);
2979 : :
2980 : 279247 : victim_buf_hdr->tag = tag;
2981 : :
180 andres@anarazel.de 2982 :GNC 279247 : set_bits |= BM_TAG_VALID | BUF_USAGECOUNT_ONE;
986 tmunro@postgresql.or 2983 [ + + + + ]:CBC 279247 : if (bmr.relpersistence == RELPERSISTENCE_PERMANENT || fork == INIT_FORKNUM)
180 andres@anarazel.de 2984 :GNC 273267 : set_bits |= BM_PERMANENT;
2985 : :
2986 : 279247 : UnlockBufHdrExt(victim_buf_hdr, buf_state,
2987 : : set_bits, 0,
2988 : : 0);
2989 : :
1126 andres@anarazel.de 2990 :CBC 279247 : LWLockRelease(partition_lock);
2991 : :
2992 : : /* XXX: could combine the locked operations in it with the above */
39 andres@anarazel.de 2993 :GNC 279247 : StartSharedBufferIO(victim_buf_hdr, true, true, NULL);
2994 : : }
2995 : : }
2996 : :
433 michael@paquier.xyz 2997 :CBC 252372 : io_start = pgstat_prepare_io_time(track_io_timing);
2998 : :
2999 : : /*
3000 : : * Note: if smgrzeroextend fails, we will end up with buffers that are
3001 : : * allocated but not marked BM_VALID. The next relation extension will
3002 : : * still select the same block number (because the relation didn't get any
3003 : : * longer on disk) and so future attempts to extend the relation will find
3004 : : * the same buffers (if they have not been recycled) but come right back
3005 : : * here to try smgrzeroextend again.
3006 : : *
3007 : : * We don't need to set checksum for all-zero pages.
3008 : : */
196 alvherre@kurilemu.de 3009 [ + + ]:GNC 252372 : smgrzeroextend(BMR_GET_SMGR(bmr), fork, first_block, extend_by, false);
3010 : :
3011 : : /*
3012 : : * Release the file-extension lock; it's now OK for someone else to extend
3013 : : * the relation some more.
3014 : : *
3015 : : * We remove IO_IN_PROGRESS after this, as waking up waiting backends can
3016 : : * take noticeable time.
3017 : : */
1126 andres@anarazel.de 3018 [ + + ]:CBC 252372 : if (!(flags & EB_SKIP_EXTENSION_LOCK))
986 tmunro@postgresql.or 3019 : 196745 : UnlockRelationForExtension(bmr.rel, ExclusiveLock);
3020 : :
1124 andres@anarazel.de 3021 : 252372 : pgstat_count_io_op_time(IOOBJECT_RELATION, io_context, IOOP_EXTEND,
476 michael@paquier.xyz 3022 : 252372 : io_start, 1, extend_by * BLCKSZ);
3023 : :
3024 : : /* Set BM_VALID, terminate IO, and wake up any waiters */
959 peter@eisentraut.org 3025 [ + + ]: 531619 : for (uint32 i = 0; i < extend_by; i++)
3026 : : {
1126 andres@anarazel.de 3027 : 279247 : Buffer buf = buffers[i];
3028 : 279247 : BufferDesc *buf_hdr = GetBufferDescriptor(buf - 1);
3029 : 279247 : bool lock = false;
3030 : :
3031 [ + + + + ]: 279247 : if (flags & EB_LOCK_FIRST && i == 0)
3032 : 194265 : lock = true;
3033 [ + + ]: 84982 : else if (flags & EB_LOCK_TARGET)
3034 : : {
3035 [ - + ]: 46698 : Assert(extend_upto != InvalidBlockNumber);
3036 [ + + ]: 46698 : if (first_block + i + 1 == extend_upto)
3037 : 46129 : lock = true;
3038 : : }
3039 : :
3040 [ + + ]: 279247 : if (lock)
209 andres@anarazel.de 3041 :GNC 240394 : LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
3042 : :
401 andres@anarazel.de 3043 :CBC 279247 : TerminateBufferIO(buf_hdr, false, BM_VALID, true, false);
3044 : : }
3045 : :
1126 3046 : 252372 : pgBufferUsage.shared_blks_written += extend_by;
3047 : :
3048 : 252372 : *extended_by = extend_by;
3049 : :
3050 : 252372 : return first_block;
3051 : : }
3052 : :
3053 : : /*
3054 : : * BufferIsLockedByMe
3055 : : *
3056 : : * Checks if this backend has the buffer locked in any mode.
3057 : : *
3058 : : * Buffer must be pinned.
3059 : : */
3060 : : bool
209 andres@anarazel.de 3061 :GNC 107 : BufferIsLockedByMe(Buffer buffer)
3062 : : {
3063 : : BufferDesc *bufHdr;
3064 : :
3065 [ - + - + : 107 : Assert(BufferIsPinned(buffer));
- + ]
3066 : :
3067 [ - + ]: 107 : if (BufferIsLocal(buffer))
3068 : : {
3069 : : /* Content locks are not maintained for local buffers. */
209 andres@anarazel.de 3070 :UNC 0 : return true;
3071 : : }
3072 : : else
3073 : : {
209 andres@anarazel.de 3074 :GNC 107 : bufHdr = GetBufferDescriptor(buffer - 1);
110 3075 : 107 : return BufferLockHeldByMe(bufHdr);
3076 : : }
3077 : : }
3078 : :
3079 : : /*
3080 : : * BufferIsLockedByMeInMode
3081 : : *
3082 : : * Checks if this backend has the buffer locked in the specified mode.
3083 : : *
3084 : : * Buffer must be pinned.
3085 : : */
3086 : : bool
153 3087 : 116984158 : BufferIsLockedByMeInMode(Buffer buffer, BufferLockMode mode)
3088 : : {
3089 : : BufferDesc *bufHdr;
3090 : :
461 tgl@sss.pgh.pa.us 3091 [ - + + + :CBC 116984158 : Assert(BufferIsPinned(buffer));
- + ]
3092 : :
925 jdavis@postgresql.or 3093 [ + + ]: 116984158 : if (BufferIsLocal(buffer))
3094 : : {
3095 : : /* Content locks are not maintained for local buffers. */
461 tgl@sss.pgh.pa.us 3096 :GBC 1019 : return true;
3097 : : }
3098 : : else
3099 : : {
925 jdavis@postgresql.or 3100 :CBC 116983139 : bufHdr = GetBufferDescriptor(buffer - 1);
110 andres@anarazel.de 3101 :GNC 116983139 : return BufferLockHeldByMeInMode(bufHdr, mode);
3102 : : }
3103 : : }
3104 : :
3105 : : /*
3106 : : * BufferIsDirty
3107 : : *
3108 : : * Checks if buffer is already dirty.
3109 : : *
3110 : : * Buffer must be pinned and [share-]exclusive-locked. (Without such a lock,
3111 : : * the result may be stale before it's returned.)
3112 : : */
3113 : : bool
925 jdavis@postgresql.or 3114 :CBC 27900320 : BufferIsDirty(Buffer buffer)
3115 : : {
3116 : : BufferDesc *bufHdr;
3117 : :
461 tgl@sss.pgh.pa.us 3118 [ - + + + : 27900320 : Assert(BufferIsPinned(buffer));
- + ]
3119 : :
925 jdavis@postgresql.or 3120 [ + + ]: 27900320 : if (BufferIsLocal(buffer))
3121 : : {
925 jdavis@postgresql.or 3122 :GBC 10005 : int bufid = -buffer - 1;
3123 : :
3124 : 10005 : bufHdr = GetLocalBufferDescriptor(bufid);
3125 : : /* Content locks are not maintained for local buffers. */
3126 : : }
3127 : : else
3128 : : {
925 jdavis@postgresql.or 3129 :CBC 27890315 : bufHdr = GetBufferDescriptor(buffer - 1);
56 andres@anarazel.de 3130 [ + + - + ]:GNC 27890315 : Assert(BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_SHARE_EXCLUSIVE) ||
3131 : : BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_EXCLUSIVE));
3132 : : }
3133 : :
110 3134 : 27900320 : return pg_atomic_read_u64(&bufHdr->state) & BM_DIRTY;
3135 : : }
3136 : :
3137 : : /*
3138 : : * MarkBufferDirty
3139 : : *
3140 : : * Marks buffer contents as dirty (actual write happens later).
3141 : : *
3142 : : * Buffer must be pinned and exclusive-locked. (If caller does not hold
3143 : : * exclusive lock, then somebody could be in process of writing the buffer,
3144 : : * leading to risk of bad data written to disk.)
3145 : : */
3146 : : void
7340 tgl@sss.pgh.pa.us 3147 :CBC 34972274 : MarkBufferDirty(Buffer buffer)
3148 : : {
3149 : : BufferDesc *bufHdr;
3150 : : uint64 buf_state;
3151 : : uint64 old_buf_state;
3152 : :
7872 3153 [ - + ]: 34972274 : if (!BufferIsValid(buffer))
5434 peter_e@gmx.net 3154 [ # # ]:UBC 0 : elog(ERROR, "bad buffer ID: %d", buffer);
3155 : :
9531 tgl@sss.pgh.pa.us 3156 [ + + ]:CBC 34972274 : if (BufferIsLocal(buffer))
3157 : : {
7340 3158 : 1742551 : MarkLocalBufferDirty(buffer);
8725 bruce@momjian.us 3159 : 1742551 : return;
3160 : : }
3161 : :
4114 andres@anarazel.de 3162 : 33229723 : bufHdr = GetBufferDescriptor(buffer - 1);
3163 : :
4266 3164 [ - + - + : 33229723 : Assert(BufferIsPinned(buffer));
- + ]
209 andres@anarazel.de 3165 [ - + ]:GNC 33229723 : Assert(BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_EXCLUSIVE));
3166 : :
3167 : : /*
3168 : : * NB: We have to wait for the buffer header spinlock to be not held, as
3169 : : * TerminateBufferIO() relies on the spinlock.
3170 : : */
110 3171 : 33229723 : old_buf_state = pg_atomic_read_u64(&bufHdr->state);
3172 : : for (;;)
3173 : : {
3677 andres@anarazel.de 3174 [ + + ]:CBC 33229863 : if (old_buf_state & BM_LOCKED)
3175 : 295 : old_buf_state = WaitBufHdrUnlocked(bufHdr);
3176 : :
3177 : 33229863 : buf_state = old_buf_state;
3178 : :
3179 [ - + ]: 33229863 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
55 andres@anarazel.de 3180 :GNC 33229863 : buf_state |= BM_DIRTY;
3181 : :
110 3182 [ + + ]: 33229863 : if (pg_atomic_compare_exchange_u64(&bufHdr->state, &old_buf_state,
3183 : : buf_state))
3677 andres@anarazel.de 3184 :CBC 33229723 : break;
3185 : : }
3186 : :
3187 : : /*
3188 : : * If the buffer was not dirty already, do vacuum accounting.
3189 : : */
3190 [ + + ]: 33229723 : if (!(old_buf_state & BM_DIRTY))
3191 : : {
5186 rhaas@postgresql.org 3192 : 810367 : pgBufferUsage.shared_blks_dirtied++;
5275 alvherre@alvh.no-ip. 3193 [ + + ]: 810367 : if (VacuumCostActive)
3194 : 11530 : VacuumCostBalance += VacuumCostPageDirty;
3195 : : }
3196 : : }
3197 : :
3198 : : /*
3199 : : * ReleaseAndReadBuffer -- combine ReleaseBuffer() and ReadBuffer()
3200 : : *
3201 : : * Formerly, this saved one cycle of acquiring/releasing the BufMgrLock
3202 : : * compared to calling the two routines separately. Now it's mainly just
3203 : : * a convenience function. However, if the passed buffer is valid and
3204 : : * already contains the desired block, we just return it as-is; and that
3205 : : * does save considerable work compared to a full release and reacquire.
3206 : : *
3207 : : * Note: it is OK to pass buffer == InvalidBuffer, indicating that no old
3208 : : * buffer actually needs to be released. This case is the same as ReadBuffer,
3209 : : * but can save some tests in the caller.
3210 : : */
3211 : : Buffer
10892 scrappy@hub.org 3212 : 3646 : ReleaseAndReadBuffer(Buffer buffer,
3213 : : Relation relation,
3214 : : BlockNumber blockNum)
3215 : : {
6172 bruce@momjian.us 3216 : 3646 : ForkNumber forkNum = MAIN_FORKNUM;
3217 : : BufferDesc *bufHdr;
3218 : :
9124 tgl@sss.pgh.pa.us 3219 [ + - ]: 3646 : if (BufferIsValid(buffer))
3220 : : {
4266 andres@anarazel.de 3221 [ - + + + : 3646 : Assert(BufferIsPinned(buffer));
- + ]
9124 tgl@sss.pgh.pa.us 3222 [ + + ]: 3646 : if (BufferIsLocal(buffer))
3223 : : {
4114 andres@anarazel.de 3224 : 50 : bufHdr = GetLocalBufferDescriptor(-buffer - 1);
9096 tgl@sss.pgh.pa.us 3225 [ - + - - ]: 50 : if (bufHdr->tag.blockNum == blockNum &&
1350 rhaas@postgresql.org 3226 [ # # ]:LBC (7044) : BufTagMatchesRelFileLocator(&bufHdr->tag, &relation->rd_locator) &&
3227 : (3522) : BufTagGetForkNum(&bufHdr->tag) == forkNum)
9096 tgl@sss.pgh.pa.us 3228 : (3522) : return buffer;
1126 andres@anarazel.de 3229 :CBC 50 : UnpinLocalBuffer(buffer);
3230 : : }
3231 : : else
3232 : : {
4114 3233 : 3596 : bufHdr = GetBufferDescriptor(buffer - 1);
3234 : : /* we have pin, so it's ok to examine tag without spinlock */
9096 tgl@sss.pgh.pa.us 3235 [ - + - - ]: 3596 : if (bufHdr->tag.blockNum == blockNum &&
1350 rhaas@postgresql.org 3236 [ # # ]:LBC (10961034) : BufTagMatchesRelFileLocator(&bufHdr->tag, &relation->rd_locator) &&
3237 : (5480517) : BufTagGetForkNum(&bufHdr->tag) == forkNum)
9096 tgl@sss.pgh.pa.us 3238 : (5480517) : return buffer;
1313 michael@paquier.xyz 3239 :CBC 3596 : UnpinBuffer(bufHdr);
3240 : : }
3241 : : }
3242 : :
7732 tgl@sss.pgh.pa.us 3243 : 3646 : return ReadBuffer(relation, blockNum);
3244 : : }
3245 : :
3246 : : /*
3247 : : * PinBuffer -- make buffer unavailable for replacement.
3248 : : *
3249 : : * For the default access strategy, the buffer's usage_count is incremented
3250 : : * when we first pin it; for other strategies we just make sure the usage_count
3251 : : * isn't zero. (The idea of the latter is that we don't want synchronized
3252 : : * heap scans to inflate the count, but we need it to not be zero to discourage
3253 : : * other backends from stealing buffers from our ring. As long as we cycle
3254 : : * through the ring faster than the global clock-sweep cycles, buffers in
3255 : : * our ring won't be chosen as victims for replacement by other backends.)
3256 : : *
3257 : : * This should be applied only to shared buffers, never local ones.
3258 : : *
3259 : : * Since buffers are pinned/unpinned very frequently, pin buffers without
3260 : : * taking the buffer header lock; instead update the state variable in loop of
3261 : : * CAS operations. Hopefully it's just a single CAS.
3262 : : *
3263 : : * Note that ResourceOwnerEnlarge() and ReservePrivateRefCountEntry()
3264 : : * must have been done already.
3265 : : *
3266 : : * Returns true if buffer is BM_VALID, else false. This provision allows
3267 : : * some callers to avoid an extra spinlock cycle. If skip_if_not_valid is
3268 : : * true, then a false return value also indicates that the buffer was
3269 : : * (recently) invalid and has not been pinned.
3270 : : */
3271 : : static bool
209 andres@anarazel.de 3272 :GNC 80752342 : PinBuffer(BufferDesc *buf, BufferAccessStrategy strategy,
3273 : : bool skip_if_not_valid)
3274 : : {
3919 andres@anarazel.de 3275 :CBC 80752342 : Buffer b = BufferDescriptorGetBuffer(buf);
3276 : : bool result;
3277 : : PrivateRefCountEntry *ref;
3278 : :
1126 3279 [ - + ]: 80752342 : Assert(!BufferIsLocal(b));
142 andres@anarazel.de 3280 [ - + ]:GNC 80752342 : Assert(ReservedRefCountSlot != -1);
3281 : :
3919 andres@anarazel.de 3282 :CBC 80752342 : ref = GetPrivateRefCountEntry(b, true);
3283 : :
4124 3284 [ + + ]: 80752342 : if (ref == NULL)
3285 : : {
3286 : : uint64 buf_state;
3287 : : uint64 old_buf_state;
3288 : :
110 andres@anarazel.de 3289 :GNC 73491569 : old_buf_state = pg_atomic_read_u64(&buf->state);
3290 : : for (;;)
3291 : : {
209 3292 [ + + + + : 73496599 : if (unlikely(skip_if_not_valid && !(old_buf_state & BM_VALID)))
+ + ]
3293 : 9 : return false;
3294 : :
3295 : : /*
3296 : : * We're not allowed to increase the refcount while the buffer
3297 : : * header spinlock is held. Wait for the lock to be released.
3298 : : */
35 3299 [ + + ]: 73496590 : if (unlikely(old_buf_state & BM_LOCKED))
3300 : : {
3677 andres@anarazel.de 3301 :CBC 89 : old_buf_state = WaitBufHdrUnlocked(buf);
3302 : :
3303 : : /* perform checks at the top of the loop again */
35 andres@anarazel.de 3304 :GNC 89 : continue;
3305 : : }
3306 : :
3677 andres@anarazel.de 3307 :CBC 73496501 : buf_state = old_buf_state;
3308 : :
3309 : : /* increase refcount */
3310 : 73496501 : buf_state += BUF_REFCOUNT_ONE;
3311 : :
3333 teodor@sigaev.ru 3312 [ + + ]: 73496501 : if (strategy == NULL)
3313 : : {
3314 : : /* Default case: increase usagecount unless already max. */
3315 [ + + ]: 72902725 : if (BUF_STATE_GET_USAGECOUNT(buf_state) < BM_MAX_USAGE_COUNT)
3316 : 3807635 : buf_state += BUF_USAGECOUNT_ONE;
3317 : : }
3318 : : else
3319 : : {
3320 : : /*
3321 : : * Ring buffers shouldn't evict others from pool. Thus we
3322 : : * don't make usagecount more than 1.
3323 : : */
3324 [ + + ]: 593776 : if (BUF_STATE_GET_USAGECOUNT(buf_state) == 0)
3325 : 39959 : buf_state += BUF_USAGECOUNT_ONE;
3326 : : }
3327 : :
110 andres@anarazel.de 3328 [ + + ]:GNC 73496501 : if (pg_atomic_compare_exchange_u64(&buf->state, &old_buf_state,
3329 : : buf_state))
3330 : : {
3677 andres@anarazel.de 3331 :CBC 73491560 : result = (buf_state & BM_VALID) != 0;
3332 : :
209 andres@anarazel.de 3333 :GNC 73491560 : TrackNewBufferPin(b);
3677 andres@anarazel.de 3334 :CBC 73491560 : break;
3335 : : }
3336 : : }
3337 : : }
3338 : : else
3339 : : {
3340 : : /*
3341 : : * If we previously pinned the buffer, it is likely to be valid, but
3342 : : * it may not be if StartReadBuffers() was called and
3343 : : * WaitReadBuffers() hasn't been called yet. We'll check by loading
3344 : : * the flags without locking. This is racy, but it's OK to return
3345 : : * false spuriously: when WaitReadBuffers() calls StartBufferIO(),
3346 : : * it'll see that it's now valid.
3347 : : *
3348 : : * Note: We deliberately avoid a Valgrind client request here.
3349 : : * Individual access methods can optionally superimpose buffer page
3350 : : * client requests on top of our client requests to enforce that
3351 : : * buffers are only accessed while locked (and pinned). It's possible
3352 : : * that the buffer page is legitimately non-accessible here. We
3353 : : * cannot meddle with that.
3354 : : */
110 andres@anarazel.de 3355 :GNC 7260773 : result = (pg_atomic_read_u64(&buf->state) & BM_VALID) != 0;
3356 : :
142 3357 [ - + ]: 7260773 : Assert(ref->data.refcount > 0);
3358 : 7260773 : ref->data.refcount++;
209 3359 : 7260773 : ResourceOwnerRememberBuffer(CurrentResourceOwner, b);
3360 : : }
3361 : :
7732 tgl@sss.pgh.pa.us 3362 :CBC 80752333 : return result;
3363 : : }
3364 : :
3365 : : /*
3366 : : * PinBuffer_Locked -- as above, but caller already locked the buffer header.
3367 : : * The spinlock is released before return.
3368 : : *
3369 : : * As this function is called with the spinlock held, the caller has to
3370 : : * previously call ReservePrivateRefCountEntry() and
3371 : : * ResourceOwnerEnlarge(CurrentResourceOwner);
3372 : : *
3373 : : * Currently, no callers of this function want to modify the buffer's
3374 : : * usage_count at all, so there's no need for a strategy parameter.
3375 : : * Also we don't bother with a BM_VALID test (the caller could check that for
3376 : : * itself).
3377 : : *
3378 : : * Also all callers only ever use this function when it's known that the
3379 : : * buffer can't have a preexisting pin by this backend. That allows us to skip
3380 : : * searching the private refcount array & hash, which is a boon, because the
3381 : : * spinlock is still held.
3382 : : *
3383 : : * Note: use of this routine is frequently mandatory, not just an optimization
3384 : : * to save a spin lock/unlock cycle, because we need to pin a buffer before
3385 : : * its state can change under us.
3386 : : */
3387 : : static void
3823 rhaas@postgresql.org 3388 : 364711 : PinBuffer_Locked(BufferDesc *buf)
3389 : : {
3390 : : uint64 old_buf_state;
3391 : :
3392 : : /*
3393 : : * As explained, We don't expect any preexisting pins. That allows us to
3394 : : * manipulate the PrivateRefCount after releasing the spinlock
3395 : : */
3919 andres@anarazel.de 3396 [ - + ]: 364711 : Assert(GetPrivateRefCountEntry(BufferDescriptorGetBuffer(buf), false) == NULL);
3397 : :
3398 : : /*
3399 : : * Since we hold the buffer spinlock, we can update the buffer state and
3400 : : * release the lock in one operation.
3401 : : */
110 andres@anarazel.de 3402 :GNC 364711 : old_buf_state = pg_atomic_read_u64(&buf->state);
3403 : :
180 3404 : 364711 : UnlockBufHdrExt(buf, old_buf_state,
3405 : : 0, 0, 1);
3406 : :
209 3407 : 364711 : TrackNewBufferPin(BufferDescriptorGetBuffer(buf));
8051 tgl@sss.pgh.pa.us 3408 :CBC 364711 : }
3409 : :
3410 : : /*
3411 : : * Support for waking up another backend that is waiting for the cleanup lock
3412 : : * to be released using BM_PIN_COUNT_WAITER.
3413 : : *
3414 : : * See LockBufferForCleanup().
3415 : : *
3416 : : * Expected to be called just after releasing a buffer pin (in a BufferDesc,
3417 : : * not just reducing the backend-local pincount for the buffer).
3418 : : */
3419 : : static void
401 andres@anarazel.de 3420 : 63 : WakePinCountWaiter(BufferDesc *buf)
3421 : : {
3422 : : /*
3423 : : * Acquire the buffer header lock, re-check that there's a waiter. Another
3424 : : * backend could have unpinned this buffer, and already woken up the
3425 : : * waiter.
3426 : : *
3427 : : * There's no danger of the buffer being replaced after we unpinned it
3428 : : * above, as it's pinned by the waiter. The waiter removes
3429 : : * BM_PIN_COUNT_WAITER if it stops waiting for a reason other than this
3430 : : * backend waking it up.
3431 : : */
110 andres@anarazel.de 3432 :GNC 63 : uint64 buf_state = LockBufHdr(buf);
3433 : :
401 andres@anarazel.de 3434 [ + - ]:CBC 63 : if ((buf_state & BM_PIN_COUNT_WAITER) &&
3435 [ + + ]: 63 : BUF_STATE_GET_REFCOUNT(buf_state) == 1)
3436 : 59 : {
3437 : : /* we just released the last pin other than the waiter's */
3438 : 59 : int wait_backend_pgprocno = buf->wait_backend_pgprocno;
3439 : :
180 andres@anarazel.de 3440 :GNC 59 : UnlockBufHdrExt(buf, buf_state,
3441 : : 0, BM_PIN_COUNT_WAITER,
3442 : : 0);
401 andres@anarazel.de 3443 :CBC 59 : ProcSendSignal(wait_backend_pgprocno);
3444 : : }
3445 : : else
180 andres@anarazel.de 3446 :GNC 4 : UnlockBufHdr(buf);
401 andres@anarazel.de 3447 :CBC 63 : }
3448 : :
3449 : : /*
3450 : : * UnpinBuffer -- make buffer available for replacement.
3451 : : *
3452 : : * This should be applied only to shared buffers, never local ones. This
3453 : : * always adjusts CurrentResourceOwner.
3454 : : */
3455 : : static void
1313 michael@paquier.xyz 3456 : 48210631 : UnpinBuffer(BufferDesc *buf)
3457 : : {
909 heikki.linnakangas@i 3458 : 48210631 : Buffer b = BufferDescriptorGetBuffer(buf);
3459 : :
3460 : 48210631 : ResourceOwnerForgetBuffer(CurrentResourceOwner, b);
3461 : 48210631 : UnpinBufferNoOwner(buf);
3462 : 48210631 : }
3463 : :
3464 : : static void
3465 : 48217242 : UnpinBufferNoOwner(BufferDesc *buf)
3466 : : {
3467 : : PrivateRefCountEntry *ref;
3919 andres@anarazel.de 3468 : 48217242 : Buffer b = BufferDescriptorGetBuffer(buf);
3469 : :
1126 3470 [ - + ]: 48217242 : Assert(!BufferIsLocal(b));
3471 : :
3472 : : /* not moving as we're likely deleting it soon anyway */
3919 3473 : 48217242 : ref = GetPrivateRefCountEntry(b, false);
4266 3474 [ - + ]: 48217242 : Assert(ref != NULL);
142 andres@anarazel.de 3475 [ - + ]:GNC 48217242 : Assert(ref->data.refcount > 0);
3476 : 48217242 : ref->data.refcount--;
3477 [ + + ]: 48217242 : if (ref->data.refcount == 0)
3478 : : {
3479 : : uint64 old_buf_state;
3480 : :
3481 : : /*
3482 : : * Mark buffer non-accessible to Valgrind.
3483 : : *
3484 : : * Note that the buffer may have already been marked non-accessible
3485 : : * within access method code that enforces that buffers are only
3486 : : * accessed while a buffer lock is held.
3487 : : */
3488 : : VALGRIND_MAKE_MEM_NOACCESS(BufHdrGetBlock(buf), BLCKSZ);
3489 : :
3490 : : /*
3491 : : * I'd better not still hold the buffer content lock. Can't use
3492 : : * BufferIsLockedByMe(), as that asserts the buffer is pinned.
3493 : : */
110 3494 [ - + ]: 29258394 : Assert(!BufferLockHeldByMe(buf));
3495 : :
3496 : : /* decrement the shared reference count */
3497 : 29258394 : old_buf_state = pg_atomic_fetch_sub_u64(&buf->state, BUF_REFCOUNT_ONE);
3498 : :
3499 : : /* Support LockBufferForCleanup() */
180 3500 [ + + ]: 29258394 : if (old_buf_state & BM_PIN_COUNT_WAITER)
401 andres@anarazel.de 3501 :CBC 58 : WakePinCountWaiter(buf);
3502 : :
4266 3503 : 29258394 : ForgetPrivateRefCountEntry(ref);
3504 : : }
8051 tgl@sss.pgh.pa.us 3505 : 48217242 : }
3506 : :
3507 : : /*
3508 : : * Set up backend-local tracking of a buffer pinned the first time by this
3509 : : * backend.
3510 : : */
3511 : : inline void
209 andres@anarazel.de 3512 :GNC 76120912 : TrackNewBufferPin(Buffer buf)
3513 : : {
3514 : : PrivateRefCountEntry *ref;
3515 : :
3516 : 76120912 : ref = NewPrivateRefCountEntry(buf);
142 3517 : 76120912 : ref->data.refcount++;
3518 : :
209 3519 : 76120912 : ResourceOwnerRememberBuffer(CurrentResourceOwner, buf);
3520 : :
3521 : : /*
3522 : : * This is the first pin for this page by this backend, mark its page as
3523 : : * defined to valgrind. While the page contents might not actually be
3524 : : * valid yet, we don't currently guarantee that such pages are marked
3525 : : * undefined or non-accessible.
3526 : : *
3527 : : * It's not necessarily the prettiest to do this here, but otherwise we'd
3528 : : * need this block of code in multiple places.
3529 : : */
3530 : : VALGRIND_MAKE_MEM_DEFINED(BufHdrGetBlock(GetBufferDescriptor(buf - 1)),
3531 : : BLCKSZ);
3532 : 76120912 : }
3533 : :
3534 : : #define ST_SORT sort_checkpoint_bufferids
3535 : : #define ST_ELEMENT_TYPE CkptSortItem
3536 : : #define ST_COMPARE(a, b) ckpt_buforder_comparator(a, b)
3537 : : #define ST_SCOPE static
3538 : : #define ST_DEFINE
3539 : : #include "lib/sort_template.h"
3540 : :
3541 : : /*
3542 : : * BufferSync -- Write out all dirty buffers in the pool.
3543 : : *
3544 : : * This is called at checkpoint time to write out all dirty shared buffers.
3545 : : * The checkpoint request flags should be passed in. If CHECKPOINT_FAST is
3546 : : * set, we disable delays between writes; if CHECKPOINT_IS_SHUTDOWN,
3547 : : * CHECKPOINT_END_OF_RECOVERY or CHECKPOINT_FLUSH_UNLOGGED is set, we write
3548 : : * even unlogged buffers, which are otherwise skipped. The remaining flags
3549 : : * currently have no effect here.
3550 : : */
3551 : : static void
6886 tgl@sss.pgh.pa.us 3552 :CBC 1944 : BufferSync(int flags)
3553 : : {
3554 : : uint64 buf_state;
3555 : : int buf_id;
3556 : : int num_to_scan;
3557 : : int num_spaces;
3558 : : int num_processed;
3559 : : int num_written;
3728 andres@anarazel.de 3560 : 1944 : CkptTsStatus *per_ts_stat = NULL;
3561 : : Oid last_tsid;
3562 : : binaryheap *ts_heap;
3563 : : int i;
110 andres@anarazel.de 3564 :GNC 1944 : uint64 mask = BM_DIRTY;
3565 : : WritebackContext wb_context;
3566 : :
3567 : : /*
3568 : : * Unless this is a shutdown checkpoint or we have been explicitly told,
3569 : : * we write only permanent, dirty buffers. But at shutdown or end of
3570 : : * recovery, we write all dirty buffers.
3571 : : */
4215 andres@anarazel.de 3572 [ + + ]:CBC 1944 : if (!((flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY |
3573 : : CHECKPOINT_FLUSH_UNLOGGED))))
5233 rhaas@postgresql.org 3574 : 1063 : mask |= BM_PERMANENT;
3575 : :
3576 : : /*
3577 : : * Loop over all buffers, and mark the ones that need to be written with
3578 : : * BM_CHECKPOINT_NEEDED. Count them as we go (num_to_scan), so that we
3579 : : * can estimate how much work needs to be done.
3580 : : *
3581 : : * This allows us to write only those pages that were dirty when the
3582 : : * checkpoint began, and not those that get dirtied while it proceeds.
3583 : : * Whenever a page with BM_CHECKPOINT_NEEDED is written out, either by us
3584 : : * later in this function, or by normal backends or the bgwriter cleaning
3585 : : * scan, the flag is cleared. Any buffer dirtied after this point won't
3586 : : * have the flag set.
3587 : : *
3588 : : * Note that if we fail to write some buffer, we may leave buffers with
3589 : : * BM_CHECKPOINT_NEEDED still set. This is OK since any such buffer would
3590 : : * certainly need to be written for the next checkpoint attempt, too.
3591 : : */
3728 andres@anarazel.de 3592 : 1944 : num_to_scan = 0;
6886 tgl@sss.pgh.pa.us 3593 [ + + ]: 14003048 : for (buf_id = 0; buf_id < NBuffers; buf_id++)
3594 : : {
3823 rhaas@postgresql.org 3595 : 14001104 : BufferDesc *bufHdr = GetBufferDescriptor(buf_id);
110 andres@anarazel.de 3596 :GNC 14001104 : uint64 set_bits = 0;
3597 : :
3598 : : /*
3599 : : * Header spinlock is enough to examine BM_DIRTY, see comment in
3600 : : * SyncOneBuffer.
3601 : : */
3677 andres@anarazel.de 3602 :CBC 14001104 : buf_state = LockBufHdr(bufHdr);
3603 : :
3604 [ + + ]: 14001104 : if ((buf_state & mask) == mask)
3605 : : {
3606 : : CkptSortItem *item;
3607 : :
180 andres@anarazel.de 3608 :GNC 344186 : set_bits = BM_CHECKPOINT_NEEDED;
3609 : :
3728 andres@anarazel.de 3610 :CBC 344186 : item = &CkptBufferIds[num_to_scan++];
3611 : 344186 : item->buf_id = buf_id;
1350 rhaas@postgresql.org 3612 : 344186 : item->tsId = bufHdr->tag.spcOid;
3613 : 344186 : item->relNumber = BufTagGetRelNumber(&bufHdr->tag);
3614 : 344186 : item->forkNum = BufTagGetForkNum(&bufHdr->tag);
3728 andres@anarazel.de 3615 : 344186 : item->blockNum = bufHdr->tag.blockNum;
3616 : : }
3617 : :
180 andres@anarazel.de 3618 :GNC 14001104 : UnlockBufHdrExt(bufHdr, buf_state,
3619 : : set_bits, 0,
3620 : : 0);
3621 : :
3622 : : /* Check for barrier events in case NBuffers is large. */
2329 rhaas@postgresql.org 3623 [ - + ]:CBC 14001104 : if (ProcSignalBarrierPending)
2329 rhaas@postgresql.org 3624 :UBC 0 : ProcessProcSignalBarrier();
3625 : : }
3626 : :
3728 andres@anarazel.de 3627 [ + + ]:CBC 1944 : if (num_to_scan == 0)
6886 tgl@sss.pgh.pa.us 3628 : 738 : return; /* nothing to do */
3629 : :
3728 andres@anarazel.de 3630 : 1206 : WritebackContextInit(&wb_context, &checkpoint_flush_after);
3631 : :
3632 : : TRACE_POSTGRESQL_BUFFER_SYNC_START(NBuffers, num_to_scan);
3633 : :
3634 : : /*
3635 : : * Sort buffers that need to be written to reduce the likelihood of random
3636 : : * IO. The sorting is also important for the implementation of balancing
3637 : : * writes between tablespaces. Without balancing writes we'd potentially
3638 : : * end up writing to the tablespaces one-by-one; possibly overloading the
3639 : : * underlying system.
3640 : : */
1880 tmunro@postgresql.or 3641 : 1206 : sort_checkpoint_bufferids(CkptBufferIds, num_to_scan);
3642 : :
3728 andres@anarazel.de 3643 : 1206 : num_spaces = 0;
3644 : :
3645 : : /*
3646 : : * Allocate progress status for each tablespace with buffers that need to
3647 : : * be flushed. This requires the to-be-flushed array to be sorted.
3648 : : */
3649 : 1206 : last_tsid = InvalidOid;
3650 [ + + ]: 345392 : for (i = 0; i < num_to_scan; i++)
3651 : : {
3652 : : CkptTsStatus *s;
3653 : : Oid cur_tsid;
3654 : :
3655 : 344186 : cur_tsid = CkptBufferIds[i].tsId;
3656 : :
3657 : : /*
3658 : : * Grow array of per-tablespace status structs, every time a new
3659 : : * tablespace is found.
3660 : : */
3661 [ + + + + ]: 344186 : if (last_tsid == InvalidOid || last_tsid != cur_tsid)
3662 : 1807 : {
3663 : : Size sz;
3664 : :
3665 : 1807 : num_spaces++;
3666 : :
3667 : : /*
3668 : : * Not worth adding grow-by-power-of-2 logic here - even with a
3669 : : * few hundred tablespaces this should be fine.
3670 : : */
3671 : 1807 : sz = sizeof(CkptTsStatus) * num_spaces;
3672 : :
3673 [ + + ]: 1807 : if (per_ts_stat == NULL)
3674 : 1206 : per_ts_stat = (CkptTsStatus *) palloc(sz);
3675 : : else
3676 : 601 : per_ts_stat = (CkptTsStatus *) repalloc(per_ts_stat, sz);
3677 : :
3678 : 1807 : s = &per_ts_stat[num_spaces - 1];
3679 : 1807 : memset(s, 0, sizeof(*s));
3680 : 1807 : s->tsId = cur_tsid;
3681 : :
3682 : : /*
3683 : : * The first buffer in this tablespace. As CkptBufferIds is sorted
3684 : : * by tablespace all (s->num_to_scan) buffers in this tablespace
3685 : : * will follow afterwards.
3686 : : */
3687 : 1807 : s->index = i;
3688 : :
3689 : : /*
3690 : : * progress_slice will be determined once we know how many buffers
3691 : : * are in each tablespace, i.e. after this loop.
3692 : : */
3693 : :
3694 : 1807 : last_tsid = cur_tsid;
3695 : : }
3696 : : else
3697 : : {
3698 : 342379 : s = &per_ts_stat[num_spaces - 1];
3699 : : }
3700 : :
3701 : 344186 : s->num_to_scan++;
3702 : :
3703 : : /* Check for barrier events. */
2329 rhaas@postgresql.org 3704 [ - + ]: 344186 : if (ProcSignalBarrierPending)
2329 rhaas@postgresql.org 3705 :UBC 0 : ProcessProcSignalBarrier();
3706 : : }
3707 : :
3728 andres@anarazel.de 3708 [ - + ]:CBC 1206 : Assert(num_spaces > 0);
3709 : :
3710 : : /*
3711 : : * Build a min-heap over the write-progress in the individual tablespaces,
3712 : : * and compute how large a portion of the total progress a single
3713 : : * processed buffer is.
3714 : : */
3715 : 1206 : ts_heap = binaryheap_allocate(num_spaces,
3716 : : ts_ckpt_progress_comparator,
3717 : : NULL);
3718 : :
3719 [ + + ]: 3013 : for (i = 0; i < num_spaces; i++)
3720 : : {
3721 : 1807 : CkptTsStatus *ts_stat = &per_ts_stat[i];
3722 : :
3723 : 1807 : ts_stat->progress_slice = (float8) num_to_scan / ts_stat->num_to_scan;
3724 : :
3725 : 1807 : binaryheap_add_unordered(ts_heap, PointerGetDatum(ts_stat));
3726 : : }
3727 : :
3728 : 1206 : binaryheap_build(ts_heap);
3729 : :
3730 : : /*
3731 : : * Iterate through to-be-checkpointed buffers and write the ones (still)
3732 : : * marked with BM_CHECKPOINT_NEEDED. The writes are balanced between
3733 : : * tablespaces; otherwise the sorting would lead to only one tablespace
3734 : : * receiving writes at a time, making inefficient use of the hardware.
3735 : : */
3736 : 1206 : num_processed = 0;
6886 tgl@sss.pgh.pa.us 3737 : 1206 : num_written = 0;
3728 andres@anarazel.de 3738 [ + + ]: 345392 : while (!binaryheap_empty(ts_heap))
3739 : : {
3740 : 344186 : BufferDesc *bufHdr = NULL;
3741 : : CkptTsStatus *ts_stat = (CkptTsStatus *)
1082 tgl@sss.pgh.pa.us 3742 : 344186 : DatumGetPointer(binaryheap_first(ts_heap));
3743 : :
3728 andres@anarazel.de 3744 : 344186 : buf_id = CkptBufferIds[ts_stat->index].buf_id;
3745 [ - + ]: 344186 : Assert(buf_id != -1);
3746 : :
3747 : 344186 : bufHdr = GetBufferDescriptor(buf_id);
3748 : :
3749 : 344186 : num_processed++;
3750 : :
3751 : : /*
3752 : : * We don't need to acquire the lock here, because we're only looking
3753 : : * at a single bit. It's possible that someone else writes the buffer
3754 : : * and clears the flag right after we check, but that doesn't matter
3755 : : * since SyncOneBuffer will then do nothing. However, there is a
3756 : : * further race condition: it's conceivable that between the time we
3757 : : * examine the bit here and the time SyncOneBuffer acquires the lock,
3758 : : * someone else not only wrote the buffer but replaced it with another
3759 : : * page and dirtied it. In that improbable case, SyncOneBuffer will
3760 : : * write the buffer though we didn't need to. It doesn't seem worth
3761 : : * guarding against this, though.
3762 : : */
110 andres@anarazel.de 3763 [ + + ]:GNC 344186 : if (pg_atomic_read_u64(&bufHdr->state) & BM_CHECKPOINT_NEEDED)
3764 : : {
3728 andres@anarazel.de 3765 [ + + ]:CBC 321605 : if (SyncOneBuffer(buf_id, false, &wb_context) & BUF_WRITTEN)
3766 : : {
3767 : : TRACE_POSTGRESQL_BUFFER_SYNC_WRITTEN(buf_id);
918 michael@paquier.xyz 3768 : 321604 : PendingCheckpointerStats.buffers_written++;
6886 tgl@sss.pgh.pa.us 3769 : 321604 : num_written++;
3770 : : }
3771 : : }
3772 : :
3773 : : /*
3774 : : * Measure progress independent of actually having to flush the buffer
3775 : : * - otherwise writing become unbalanced.
3776 : : */
3728 andres@anarazel.de 3777 : 344186 : ts_stat->progress += ts_stat->progress_slice;
3778 : 344186 : ts_stat->num_scanned++;
3779 : 344186 : ts_stat->index++;
3780 : :
3781 : : /* Have all the buffers from the tablespace been processed? */
3782 [ + + ]: 344186 : if (ts_stat->num_scanned == ts_stat->num_to_scan)
3783 : : {
3784 : 1807 : binaryheap_remove_first(ts_heap);
3785 : : }
3786 : : else
3787 : : {
3788 : : /* update heap with the new progress */
3789 : 342379 : binaryheap_replace_first(ts_heap, PointerGetDatum(ts_stat));
3790 : : }
3791 : :
3792 : : /*
3793 : : * Sleep to throttle our I/O rate.
3794 : : *
3795 : : * (This will check for barrier events even if it doesn't sleep.)
3796 : : */
3797 : 344186 : CheckpointWriteDelay(flags, (double) num_processed / num_to_scan);
3798 : : }
3799 : :
3800 : : /*
3801 : : * Issue all pending flushes. Only checkpointer calls BufferSync(), so
3802 : : * IOContext will always be IOCONTEXT_NORMAL.
3803 : : */
1084 3804 : 1206 : IssuePendingWritebacks(&wb_context, IOCONTEXT_NORMAL);
3805 : :
3728 3806 : 1206 : pfree(per_ts_stat);
3807 : 1206 : per_ts_stat = NULL;
3808 : 1206 : binaryheap_free(ts_heap);
3809 : :
3810 : : /*
3811 : : * Update checkpoint statistics. As noted above, this doesn't include
3812 : : * buffers written by other backends or bgwriter scan.
3813 : : */
6884 tgl@sss.pgh.pa.us 3814 : 1206 : CheckpointStats.ckpt_bufs_written += num_written;
3815 : :
3816 : : TRACE_POSTGRESQL_BUFFER_SYNC_DONE(NBuffers, num_written, num_to_scan);
3817 : : }
3818 : :
3819 : : /*
3820 : : * BgBufferSync -- Write out some dirty buffers in the pool.
3821 : : *
3822 : : * This is called periodically by the background writer process.
3823 : : *
3824 : : * Returns true if it's appropriate for the bgwriter process to go into
3825 : : * low-power hibernation mode. (This happens if the strategy clock-sweep
3826 : : * has been "lapped" and no buffer allocations have occurred recently,
3827 : : * or if the bgwriter has been effectively disabled by setting
3828 : : * bgwriter_lru_maxpages to 0.)
3829 : : */
3830 : : bool
3728 andres@anarazel.de 3831 : 13948 : BgBufferSync(WritebackContext *wb_context)
3832 : : {
3833 : : /* info obtained from freelist.c */
3834 : : int strategy_buf_id;
3835 : : uint32 strategy_passes;
3836 : : uint32 recent_alloc;
3837 : :
3838 : : /*
3839 : : * Information saved between calls so we can determine the strategy
3840 : : * point's advance rate and avoid scanning already-cleaned buffers.
3841 : : */
3842 : : static bool saved_info_valid = false;
3843 : : static int prev_strategy_buf_id;
3844 : : static uint32 prev_strategy_passes;
3845 : : static int next_to_clean;
3846 : : static uint32 next_passes;
3847 : :
3848 : : /* Moving averages of allocation rate and clean-buffer density */
3849 : : static float smoothed_alloc = 0;
3850 : : static float smoothed_density = 10.0;
3851 : :
3852 : : /* Potentially these could be tunables, but for now, not */
6797 tgl@sss.pgh.pa.us 3853 : 13948 : float smoothing_samples = 16;
3854 : 13948 : float scan_whole_pool_milliseconds = 120000.0;
3855 : :
3856 : : /* Used to compute how far we scan ahead */
3857 : : long strategy_delta;
3858 : : int bufs_to_lap;
3859 : : int bufs_ahead;
3860 : : float scans_per_alloc;
3861 : : int reusable_buffers_est;
3862 : : int upcoming_alloc_est;
3863 : : int min_scan_buffers;
3864 : :
3865 : : /* Variables for the scanning loop proper */
3866 : : int num_to_scan;
3867 : : int num_written;
3868 : : int reusable_buffers;
3869 : :
3870 : : /* Variables for final smoothed_density update */
3871 : : long new_strategy_delta;
3872 : : uint32 new_recent_alloc;
3873 : :
3874 : : /*
3875 : : * Find out where the clock-sweep currently is, and how many buffer
3876 : : * allocations have happened since our last call.
3877 : : */
3878 : 13948 : strategy_buf_id = StrategySyncStart(&strategy_passes, &recent_alloc);
3879 : :
3880 : : /* Report buffer alloc counts to pgstat */
1490 andres@anarazel.de 3881 : 13948 : PendingBgWriterStats.buf_alloc += recent_alloc;
3882 : :
3883 : : /*
3884 : : * If we're not running the LRU scan, just stop after doing the stats
3885 : : * stuff. We mark the saved state invalid so that we can recover sanely
3886 : : * if LRU scan is turned back on later.
3887 : : */
6797 tgl@sss.pgh.pa.us 3888 [ + + ]: 13948 : if (bgwriter_lru_maxpages <= 0)
3889 : : {
3890 : 50 : saved_info_valid = false;
5213 heikki.linnakangas@i 3891 : 50 : return true;
3892 : : }
3893 : :
3894 : : /*
3895 : : * Compute strategy_delta = how many buffers have been scanned by the
3896 : : * clock-sweep since last time. If first time through, assume none. Then
3897 : : * see if we are still ahead of the clock-sweep, and if so, how many
3898 : : * buffers we could scan before we'd catch up with it and "lap" it. Note:
3899 : : * weird-looking coding of xxx_passes comparisons are to avoid bogus
3900 : : * behavior when the passes counts wrap around.
3901 : : */
6797 tgl@sss.pgh.pa.us 3902 [ + + ]: 13898 : if (saved_info_valid)
3903 : : {
6746 bruce@momjian.us 3904 : 13266 : int32 passes_delta = strategy_passes - prev_strategy_passes;
3905 : :
6797 tgl@sss.pgh.pa.us 3906 : 13266 : strategy_delta = strategy_buf_id - prev_strategy_buf_id;
3240 3907 : 13266 : strategy_delta += (long) passes_delta * NBuffers;
3908 : :
6797 3909 [ - + ]: 13266 : Assert(strategy_delta >= 0);
3910 : :
3911 [ + + ]: 13266 : if ((int32) (next_passes - strategy_passes) > 0)
3912 : : {
3913 : : /* we're one pass ahead of the strategy point */
3914 : 3117 : bufs_to_lap = strategy_buf_id - next_to_clean;
3915 : : #ifdef BGW_DEBUG
3916 : : elog(DEBUG2, "bgwriter ahead: bgw %u-%u strategy %u-%u delta=%ld lap=%d",
3917 : : next_passes, next_to_clean,
3918 : : strategy_passes, strategy_buf_id,
3919 : : strategy_delta, bufs_to_lap);
3920 : : #endif
3921 : : }
3922 [ + + ]: 10149 : else if (next_passes == strategy_passes &&
3923 [ + + ]: 7068 : next_to_clean >= strategy_buf_id)
3924 : : {
3925 : : /* on same pass, but ahead or at least not behind */
3926 : 6080 : bufs_to_lap = NBuffers - (next_to_clean - strategy_buf_id);
3927 : : #ifdef BGW_DEBUG
3928 : : elog(DEBUG2, "bgwriter ahead: bgw %u-%u strategy %u-%u delta=%ld lap=%d",
3929 : : next_passes, next_to_clean,
3930 : : strategy_passes, strategy_buf_id,
3931 : : strategy_delta, bufs_to_lap);
3932 : : #endif
3933 : : }
3934 : : else
3935 : : {
3936 : : /*
3937 : : * We're behind, so skip forward to the strategy point and start
3938 : : * cleaning from there.
3939 : : */
3940 : : #ifdef BGW_DEBUG
3941 : : elog(DEBUG2, "bgwriter behind: bgw %u-%u strategy %u-%u delta=%ld",
3942 : : next_passes, next_to_clean,
3943 : : strategy_passes, strategy_buf_id,
3944 : : strategy_delta);
3945 : : #endif
3946 : 4069 : next_to_clean = strategy_buf_id;
3947 : 4069 : next_passes = strategy_passes;
3948 : 4069 : bufs_to_lap = NBuffers;
3949 : : }
3950 : : }
3951 : : else
3952 : : {
3953 : : /*
3954 : : * Initializing at startup or after LRU scanning had been off. Always
3955 : : * start at the strategy point.
3956 : : */
3957 : : #ifdef BGW_DEBUG
3958 : : elog(DEBUG2, "bgwriter initializing: strategy %u-%u",
3959 : : strategy_passes, strategy_buf_id);
3960 : : #endif
3961 : 632 : strategy_delta = 0;
3962 : 632 : next_to_clean = strategy_buf_id;
3963 : 632 : next_passes = strategy_passes;
3964 : 632 : bufs_to_lap = NBuffers;
3965 : : }
3966 : :
3967 : : /* Update saved info for next time */
3968 : 13898 : prev_strategy_buf_id = strategy_buf_id;
3969 : 13898 : prev_strategy_passes = strategy_passes;
3970 : 13898 : saved_info_valid = true;
3971 : :
3972 : : /*
3973 : : * Compute how many buffers had to be scanned for each new allocation, ie,
3974 : : * 1/density of reusable buffers, and track a moving average of that.
3975 : : *
3976 : : * If the strategy point didn't move, we don't update the density estimate
3977 : : */
3978 [ + + + - ]: 13898 : if (strategy_delta > 0 && recent_alloc > 0)
3979 : : {
3980 : 9469 : scans_per_alloc = (float) strategy_delta / (float) recent_alloc;
3981 : 9469 : smoothed_density += (scans_per_alloc - smoothed_density) /
3982 : : smoothing_samples;
3983 : : }
3984 : :
3985 : : /*
3986 : : * Estimate how many reusable buffers there are between the current
3987 : : * strategy point and where we've scanned ahead to, based on the smoothed
3988 : : * density estimate.
3989 : : */
3990 : 13898 : bufs_ahead = NBuffers - bufs_to_lap;
3991 : 13898 : reusable_buffers_est = (float) bufs_ahead / smoothed_density;
3992 : :
3993 : : /*
3994 : : * Track a moving average of recent buffer allocations. Here, rather than
3995 : : * a true average we want a fast-attack, slow-decline behavior: we
3996 : : * immediately follow any increase.
3997 : : */
3998 [ + + ]: 13898 : if (smoothed_alloc <= (float) recent_alloc)
3999 : 2857 : smoothed_alloc = recent_alloc;
4000 : : else
4001 : 11041 : smoothed_alloc += ((float) recent_alloc - smoothed_alloc) /
4002 : : smoothing_samples;
4003 : :
4004 : : /* Scale the estimate by a GUC to allow more aggressive tuning. */
5281 4005 : 13898 : upcoming_alloc_est = (int) (smoothed_alloc * bgwriter_lru_multiplier);
4006 : :
4007 : : /*
4008 : : * If recent_alloc remains at zero for many cycles, smoothed_alloc will
4009 : : * eventually underflow to zero, and the underflows produce annoying
4010 : : * kernel warnings on some platforms. Once upcoming_alloc_est has gone to
4011 : : * zero, there's no point in tracking smaller and smaller values of
4012 : : * smoothed_alloc, so just reset it to exactly zero to avoid this
4013 : : * syndrome. It will pop back up as soon as recent_alloc increases.
4014 : : */
4015 [ + + ]: 13898 : if (upcoming_alloc_est == 0)
4016 : 1081 : smoothed_alloc = 0;
4017 : :
4018 : : /*
4019 : : * Even in cases where there's been little or no buffer allocation
4020 : : * activity, we want to make a small amount of progress through the buffer
4021 : : * cache so that as many reusable buffers as possible are clean after an
4022 : : * idle period.
4023 : : *
4024 : : * (scan_whole_pool_milliseconds / BgWriterDelay) computes how many times
4025 : : * the BGW will be called during the scan_whole_pool time; slice the
4026 : : * buffer pool into that many sections.
4027 : : */
6797 4028 : 13898 : min_scan_buffers = (int) (NBuffers / (scan_whole_pool_milliseconds / BgWriterDelay));
4029 : :
4030 [ + + ]: 13898 : if (upcoming_alloc_est < (min_scan_buffers + reusable_buffers_est))
4031 : : {
4032 : : #ifdef BGW_DEBUG
4033 : : elog(DEBUG2, "bgwriter: alloc_est=%d too small, using min=%d + reusable_est=%d",
4034 : : upcoming_alloc_est, min_scan_buffers, reusable_buffers_est);
4035 : : #endif
4036 : 6362 : upcoming_alloc_est = min_scan_buffers + reusable_buffers_est;
4037 : : }
4038 : :
4039 : : /*
4040 : : * Now write out dirty reusable buffers, working forward from the
4041 : : * next_to_clean point, until we have lapped the strategy scan, or cleaned
4042 : : * enough buffers to match our estimate of the next cycle's allocation
4043 : : * requirements, or hit the bgwriter_lru_maxpages limit.
4044 : : */
4045 : :
4046 : 13898 : num_to_scan = bufs_to_lap;
4047 : 13898 : num_written = 0;
4048 : 13898 : reusable_buffers = reusable_buffers_est;
4049 : :
4050 : : /* Execute the LRU scan */
4051 [ + + + + ]: 2069212 : while (num_to_scan > 0 && reusable_buffers < upcoming_alloc_est)
4052 : : {
3677 andres@anarazel.de 4053 : 2055316 : int sync_state = SyncOneBuffer(next_to_clean, true,
4054 : : wb_context);
4055 : :
6797 tgl@sss.pgh.pa.us 4056 [ + + ]: 2055316 : if (++next_to_clean >= NBuffers)
4057 : : {
4058 : 3867 : next_to_clean = 0;
4059 : 3867 : next_passes++;
4060 : : }
4061 : 2055316 : num_to_scan--;
4062 : :
3677 andres@anarazel.de 4063 [ + + ]: 2055316 : if (sync_state & BUF_WRITTEN)
4064 : : {
6797 tgl@sss.pgh.pa.us 4065 : 37521 : reusable_buffers++;
4066 [ + + ]: 37521 : if (++num_written >= bgwriter_lru_maxpages)
4067 : : {
1490 andres@anarazel.de 4068 : 2 : PendingBgWriterStats.maxwritten_clean++;
6797 tgl@sss.pgh.pa.us 4069 : 2 : break;
4070 : : }
4071 : : }
3677 andres@anarazel.de 4072 [ + + ]: 2017795 : else if (sync_state & BUF_REUSABLE)
6797 tgl@sss.pgh.pa.us 4073 : 1507796 : reusable_buffers++;
4074 : : }
4075 : :
1490 andres@anarazel.de 4076 : 13898 : PendingBgWriterStats.buf_written_clean += num_written;
4077 : :
4078 : : #ifdef BGW_DEBUG
4079 : : elog(DEBUG1, "bgwriter: recent_alloc=%u smoothed=%.2f delta=%ld ahead=%d density=%.2f reusable_est=%d upcoming_est=%d scanned=%d wrote=%d reusable=%d",
4080 : : recent_alloc, smoothed_alloc, strategy_delta, bufs_ahead,
4081 : : smoothed_density, reusable_buffers_est, upcoming_alloc_est,
4082 : : bufs_to_lap - num_to_scan,
4083 : : num_written,
4084 : : reusable_buffers - reusable_buffers_est);
4085 : : #endif
4086 : :
4087 : : /*
4088 : : * Consider the above scan as being like a new allocation scan.
4089 : : * Characterize its density and update the smoothed one based on it. This
4090 : : * effectively halves the moving average period in cases where both the
4091 : : * strategy and the background writer are doing some useful scanning,
4092 : : * which is helpful because a long memory isn't as desirable on the
4093 : : * density estimates.
4094 : : */
5109 tgl@sss.pgh.pa.us 4095 : 13898 : new_strategy_delta = bufs_to_lap - num_to_scan;
4096 : 13898 : new_recent_alloc = reusable_buffers - reusable_buffers_est;
4097 [ + + + + ]: 13898 : if (new_strategy_delta > 0 && new_recent_alloc > 0)
4098 : : {
4099 : 11972 : scans_per_alloc = (float) new_strategy_delta / (float) new_recent_alloc;
6797 4100 : 11972 : smoothed_density += (scans_per_alloc - smoothed_density) /
4101 : : smoothing_samples;
4102 : :
4103 : : #ifdef BGW_DEBUG
4104 : : elog(DEBUG2, "bgwriter: cleaner density alloc=%u scan=%ld density=%.2f new smoothed=%.2f",
4105 : : new_recent_alloc, new_strategy_delta,
4106 : : scans_per_alloc, smoothed_density);
4107 : : #endif
4108 : : }
4109 : :
4110 : : /* Return true if OK to hibernate */
5109 4111 [ + + + - ]: 13898 : return (bufs_to_lap == 0 && recent_alloc == 0);
4112 : : }
4113 : :
4114 : : /*
4115 : : * SyncOneBuffer -- process a single buffer during syncing.
4116 : : *
4117 : : * If skip_recently_used is true, we don't write currently-pinned buffers, nor
4118 : : * buffers marked recently used, as these are not replacement candidates.
4119 : : *
4120 : : * Returns a bitmask containing the following flag bits:
4121 : : * BUF_WRITTEN: we wrote the buffer.
4122 : : * BUF_REUSABLE: buffer is available for replacement, ie, it has
4123 : : * pin count 0 and usage count 0.
4124 : : *
4125 : : * (BUF_WRITTEN could be set in error if FlushBuffer finds the buffer clean
4126 : : * after locking it, but we don't care all that much.)
4127 : : */
4128 : : static int
3728 andres@anarazel.de 4129 : 2376921 : SyncOneBuffer(int buf_id, bool skip_recently_used, WritebackContext *wb_context)
4130 : : {
3823 rhaas@postgresql.org 4131 : 2376921 : BufferDesc *bufHdr = GetBufferDescriptor(buf_id);
6746 bruce@momjian.us 4132 : 2376921 : int result = 0;
4133 : : uint64 buf_state;
4134 : : BufferTag tag;
4135 : :
4136 : : /* Make sure we can handle the pin */
4124 andres@anarazel.de 4137 : 2376921 : ReservePrivateRefCountEntry();
909 heikki.linnakangas@i 4138 : 2376921 : ResourceOwnerEnlarge(CurrentResourceOwner);
4139 : :
4140 : : /*
4141 : : * Check whether buffer needs writing.
4142 : : *
4143 : : * We can make this check without taking the buffer content lock so long
4144 : : * as we mark pages dirty in access methods *before* logging changes with
4145 : : * XLogInsert(): if someone marks the buffer dirty just after our check we
4146 : : * don't worry because our checkpoint.redo points before log record for
4147 : : * upcoming changes and so we are not required to write such dirty buffer.
4148 : : */
3677 andres@anarazel.de 4149 : 2376921 : buf_state = LockBufHdr(bufHdr);
4150 : :
4151 [ + + ]: 2376921 : if (BUF_STATE_GET_REFCOUNT(buf_state) == 0 &&
4152 [ + + ]: 2370701 : BUF_STATE_GET_USAGECOUNT(buf_state) == 0)
4153 : : {
6797 tgl@sss.pgh.pa.us 4154 : 1547342 : result |= BUF_REUSABLE;
4155 : : }
4156 [ + + ]: 829579 : else if (skip_recently_used)
4157 : : {
4158 : : /* Caller told us not to write recently-used buffers */
180 andres@anarazel.de 4159 :GNC 509999 : UnlockBufHdr(bufHdr);
6797 tgl@sss.pgh.pa.us 4160 :CBC 509999 : return result;
4161 : : }
4162 : :
3677 andres@anarazel.de 4163 [ + + + + ]: 1866922 : if (!(buf_state & BM_VALID) || !(buf_state & BM_DIRTY))
4164 : : {
4165 : : /* It's clean, so nothing to do */
180 andres@anarazel.de 4166 :GNC 1507797 : UnlockBufHdr(bufHdr);
6797 tgl@sss.pgh.pa.us 4167 :CBC 1507797 : return result;
4168 : : }
4169 : :
4170 : : /*
4171 : : * Pin it, share-exclusive-lock it, write it. (FlushBuffer will do
4172 : : * nothing if the buffer is clean by the time we've locked it.)
4173 : : */
7732 4174 : 359125 : PinBuffer_Locked(bufHdr);
4175 : :
209 andres@anarazel.de 4176 :GNC 359125 : FlushUnlockedBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
4177 : :
3728 andres@anarazel.de 4178 :CBC 359125 : tag = bufHdr->tag;
4179 : :
1313 michael@paquier.xyz 4180 : 359125 : UnpinBuffer(bufHdr);
4181 : :
4182 : : /*
4183 : : * SyncOneBuffer() is only called by checkpointer and bgwriter, so
4184 : : * IOContext will always be IOCONTEXT_NORMAL.
4185 : : */
1084 andres@anarazel.de 4186 : 359125 : ScheduleBufferTagForWriteback(wb_context, IOCONTEXT_NORMAL, &tag);
4187 : :
6797 tgl@sss.pgh.pa.us 4188 : 359125 : return result | BUF_WRITTEN;
4189 : : }
4190 : :
4191 : : /*
4192 : : * AtEOXact_Buffers - clean up at end of transaction.
4193 : : *
4194 : : * As of PostgreSQL 8.0, buffer pins should get released by the
4195 : : * ResourceOwner mechanism. This routine is just a debugging
4196 : : * cross-check that no pins remain.
4197 : : */
4198 : : void
8673 4199 : 423297 : AtEOXact_Buffers(bool isCommit)
4200 : : {
4337 andres@anarazel.de 4201 : 423297 : CheckForBufferLeaks();
4202 : :
7871 tgl@sss.pgh.pa.us 4203 : 423297 : AtEOXact_LocalBuffers(isCommit);
4204 : :
4266 andres@anarazel.de 4205 [ - + ]: 423297 : Assert(PrivateRefCountOverflowed == 0);
4206 : 423297 : }
4207 : :
4208 : : /*
4209 : : * Initialize access to shared buffer pool
4210 : : *
4211 : : * This is called during backend startup (whether standalone or under the
4212 : : * postmaster). It sets up for this backend's access to the already-existing
4213 : : * buffer pool.
4214 : : */
4215 : : void
614 heikki.linnakangas@i 4216 : 22963 : InitBufferManagerAccess(void)
4217 : : {
4218 : : /*
4219 : : * An advisory limit on the number of pins each backend should hold, based
4220 : : * on shared_buffers and the maximum number of connections possible.
4221 : : * That's very pessimistic, but outside toy-sized shared_buffers it should
4222 : : * allow plenty of pins. LimitAdditionalPins() and
4223 : : * GetAdditionalPinLimit() can be used to check the remaining balance.
4224 : : */
417 tmunro@postgresql.or 4225 : 22963 : MaxProportionalPins = NBuffers / (MaxBackends + NUM_AUXILIARY_PROCS);
4226 : :
4266 andres@anarazel.de 4227 : 22963 : memset(&PrivateRefCountArray, 0, sizeof(PrivateRefCountArray));
142 andres@anarazel.de 4228 :GNC 22963 : memset(&PrivateRefCountArrayKeys, 0, sizeof(PrivateRefCountArrayKeys));
4229 : :
54 pg@bowt.ie 4230 : 22963 : PrivateRefCountHash = refcount_create(CurrentMemoryContext, 100, NULL);
4231 : :
4232 : : /*
4233 : : * AtProcExit_Buffers needs LWLock access, and thereby has to be called at
4234 : : * the corresponding phase of backend shutdown.
4235 : : */
1734 andres@anarazel.de 4236 [ - + ]:CBC 22963 : Assert(MyProc != NULL);
7575 tgl@sss.pgh.pa.us 4237 : 22963 : on_shmem_exit(AtProcExit_Buffers, 0);
4238 : 22963 : }
4239 : :
4240 : : /*
4241 : : * During backend exit, ensure that we released all shared-buffer locks and
4242 : : * assert that we have no remaining pins.
4243 : : */
4244 : : static void
4245 : 22963 : AtProcExit_Buffers(int code, Datum arg)
4246 : : {
7871 4247 : 22963 : UnlockBuffers();
4248 : :
4337 andres@anarazel.de 4249 : 22963 : CheckForBufferLeaks();
4250 : :
4251 : : /* localbuf.c needs a chance too */
4252 : 22963 : AtProcExit_LocalBuffers();
4253 : 22963 : }
4254 : :
4255 : : /*
4256 : : * CheckForBufferLeaks - ensure this backend holds no buffer pins
4257 : : *
4258 : : * As of PostgreSQL 8.0, buffer pins should get released by the
4259 : : * ResourceOwner mechanism. This routine is just a debugging
4260 : : * cross-check that no pins remain.
4261 : : */
4262 : : static void
4263 : 446260 : CheckForBufferLeaks(void)
4264 : : {
4265 : : #ifdef USE_ASSERT_CHECKING
4266 : 446260 : int RefCountErrors = 0;
4267 : : PrivateRefCountEntry *res;
4268 : : int i;
4269 : : char *s;
4270 : :
4271 : : /* check the array */
4266 4272 [ + + ]: 4016340 : for (i = 0; i < REFCOUNT_ARRAY_ENTRIES; i++)
4273 : : {
142 andres@anarazel.de 4274 [ - + ]:GNC 3570080 : if (PrivateRefCountArrayKeys[i] != InvalidBuffer)
4275 : : {
142 andres@anarazel.de 4276 :UNC 0 : res = &PrivateRefCountArray[i];
4277 : :
909 heikki.linnakangas@i 4278 :UBC 0 : s = DebugPrintBufferRefcount(res->buffer);
4279 [ # # ]: 0 : elog(WARNING, "buffer refcount leak: %s", s);
4280 : 0 : pfree(s);
4281 : :
4266 andres@anarazel.de 4282 : 0 : RefCountErrors++;
4283 : : }
4284 : : }
4285 : :
4286 : : /* if necessary search the hash */
4266 andres@anarazel.de 4287 [ - + ]:CBC 446260 : if (PrivateRefCountOverflowed)
4288 : : {
4289 : : refcount_iterator iter;
4290 : :
54 pg@bowt.ie 4291 :UNC 0 : refcount_start_iterate(PrivateRefCountHash, &iter);
4292 [ # # ]: 0 : while ((res = refcount_iterate(PrivateRefCountHash, &iter)) != NULL)
4293 : : {
909 heikki.linnakangas@i 4294 :UBC 0 : s = DebugPrintBufferRefcount(res->buffer);
4295 [ # # ]: 0 : elog(WARNING, "buffer refcount leak: %s", s);
4296 : 0 : pfree(s);
4337 andres@anarazel.de 4297 : 0 : RefCountErrors++;
4298 : : }
4299 : : }
4300 : :
4337 andres@anarazel.de 4301 [ - + ]:CBC 446260 : Assert(RefCountErrors == 0);
4302 : : #endif
7871 tgl@sss.pgh.pa.us 4303 : 446260 : }
4304 : :
4305 : : #ifdef USE_ASSERT_CHECKING
4306 : : /*
4307 : : * Check for exclusive-locked catalog buffers. This is the core of
4308 : : * AssertCouldGetRelation().
4309 : : *
4310 : : * A backend would self-deadlock on the content lock if the catalog scan read
4311 : : * the exclusive-locked buffer. The main threat is exclusive-locked buffers
4312 : : * of catalogs used in relcache, because a catcache search on any catalog may
4313 : : * build that catalog's relcache entry. We don't have an inventory of
4314 : : * catalogs relcache uses, so just check buffers of most catalogs.
4315 : : *
4316 : : * It's better to minimize waits while holding an exclusive buffer lock, so it
4317 : : * would be nice to broaden this check not to be catalog-specific. However,
4318 : : * bttextcmp() accesses pg_collation, and non-core opclasses might similarly
4319 : : * read tables. That is deadlock-free as long as there's no loop in the
4320 : : * dependency graph: modifying table A may cause an opclass to read table B,
4321 : : * but it must not cause a read of table A.
4322 : : */
4323 : : void
383 noah@leadboat.com 4324 : 143281422 : AssertBufferLocksPermitCatalogRead(void)
4325 : : {
4326 : : PrivateRefCountEntry *res;
4327 : :
4328 : : /* check the array */
110 andres@anarazel.de 4329 [ + + ]:GNC 1289532798 : for (int i = 0; i < REFCOUNT_ARRAY_ENTRIES; i++)
4330 : : {
4331 [ + + ]: 1146251376 : if (PrivateRefCountArrayKeys[i] != InvalidBuffer)
4332 : : {
4333 : 44807195 : res = &PrivateRefCountArray[i];
4334 : :
4335 [ - + ]: 44807195 : if (res->buffer == InvalidBuffer)
110 andres@anarazel.de 4336 :UNC 0 : continue;
4337 : :
110 andres@anarazel.de 4338 :GNC 44807195 : AssertNotCatalogBufferLock(res->buffer, res->data.lockmode);
4339 : : }
4340 : : }
4341 : :
4342 : : /* if necessary search the hash */
4343 [ + + ]: 143281422 : if (PrivateRefCountOverflowed)
4344 : : {
4345 : : refcount_iterator iter;
4346 : :
54 pg@bowt.ie 4347 : 189537 : refcount_start_iterate(PrivateRefCountHash, &iter);
4348 [ + + ]: 446849 : while ((res = refcount_iterate(PrivateRefCountHash, &iter)) != NULL)
4349 : : {
110 andres@anarazel.de 4350 : 257312 : AssertNotCatalogBufferLock(res->buffer, res->data.lockmode);
4351 : : }
4352 : : }
383 noah@leadboat.com 4353 :CBC 143281422 : }
4354 : :
4355 : : static void
110 andres@anarazel.de 4356 :GNC 45064507 : AssertNotCatalogBufferLock(Buffer buffer, BufferLockMode mode)
4357 : : {
4358 : 45064507 : BufferDesc *bufHdr = GetBufferDescriptor(buffer - 1);
4359 : : BufferTag tag;
4360 : : Oid relid;
4361 : :
4362 [ + + ]: 45064507 : if (mode != BUFFER_LOCK_EXCLUSIVE)
383 noah@leadboat.com 4363 :CBC 45053182 : return;
4364 : :
4365 : 11325 : tag = bufHdr->tag;
4366 : :
4367 : : /*
4368 : : * This relNumber==relid assumption holds until a catalog experiences
4369 : : * VACUUM FULL or similar. After a command like that, relNumber will be
4370 : : * in the normal (non-catalog) range, and we lose the ability to detect
4371 : : * hazardous access to that catalog. Calling RelidByRelfilenumber() would
4372 : : * close that gap, but RelidByRelfilenumber() might then deadlock with a
4373 : : * held lock.
4374 : : */
4375 : 11325 : relid = tag.relNumber;
4376 : :
4377 [ - + ]: 11325 : if (IsCatalogTextUniqueIndexOid(relid)) /* see comments at the callee */
383 noah@leadboat.com 4378 :UBC 0 : return;
4379 : :
383 noah@leadboat.com 4380 [ - + ]:CBC 11325 : Assert(!IsCatalogRelationOid(relid));
4381 : : }
4382 : : #endif
4383 : :
4384 : :
4385 : : /*
4386 : : * Helper routine to issue warnings when a buffer is unexpectedly pinned
4387 : : */
4388 : : char *
909 heikki.linnakangas@i 4389 : 72 : DebugPrintBufferRefcount(Buffer buffer)
4390 : : {
4391 : : BufferDesc *buf;
4392 : : int32 loccount;
4393 : : char *result;
4394 : : ProcNumber backend;
4395 : : uint64 buf_state;
4396 : :
7871 tgl@sss.pgh.pa.us 4397 [ - + ]: 72 : Assert(BufferIsValid(buffer));
4398 [ + + ]: 72 : if (BufferIsLocal(buffer))
4399 : : {
4114 andres@anarazel.de 4400 : 24 : buf = GetLocalBufferDescriptor(-buffer - 1);
7871 tgl@sss.pgh.pa.us 4401 : 24 : loccount = LocalRefCount[-buffer - 1];
793 heikki.linnakangas@i 4402 : 24 : backend = MyProcNumber;
4403 : : }
4404 : : else
4405 : : {
4114 andres@anarazel.de 4406 : 48 : buf = GetBufferDescriptor(buffer - 1);
4266 4407 : 48 : loccount = GetPrivateRefCount(buffer);
793 heikki.linnakangas@i 4408 : 48 : backend = INVALID_PROC_NUMBER;
4409 : : }
4410 : :
4411 : : /* theoretically we should lock the bufHdr here */
110 andres@anarazel.de 4412 :GNC 72 : buf_state = pg_atomic_read_u64(&buf->state);
4413 : :
4414 : 72 : result = psprintf("[%03d] (rel=%s, blockNum=%u, flags=0x%" PRIx64 ", refcount=%u %d)",
4415 : : buffer,
434 andres@anarazel.de 4416 :CBC 72 : relpathbackend(BufTagGetRelFileLocator(&buf->tag), backend,
4417 : : BufTagGetForkNum(&buf->tag)).str,
4418 : : buf->tag.blockNum, buf_state & BUF_FLAG_MASK,
4419 : : BUF_STATE_GET_REFCOUNT(buf_state), loccount);
909 heikki.linnakangas@i 4420 : 72 : return result;
4421 : : }
4422 : :
4423 : : /*
4424 : : * CheckPointBuffers
4425 : : *
4426 : : * Flush all dirty blocks in buffer pool to disk at checkpoint time.
4427 : : *
4428 : : * Note: temporary relations do not participate in checkpoints, so they don't
4429 : : * need to be flushed.
4430 : : */
4431 : : void
6886 tgl@sss.pgh.pa.us 4432 : 1944 : CheckPointBuffers(int flags)
4433 : : {
4434 : 1944 : BufferSync(flags);
9287 vadim4o@yahoo.com 4435 : 1944 : }
4436 : :
4437 : : /*
4438 : : * BufferGetBlockNumber
4439 : : * Returns the block number associated with a buffer.
4440 : : *
4441 : : * Note:
4442 : : * Assumes that the buffer is valid and pinned, else the
4443 : : * value may be obsolete immediately...
4444 : : */
4445 : : BlockNumber
10892 scrappy@hub.org 4446 : 236345017 : BufferGetBlockNumber(Buffer buffer)
4447 : : {
4448 : : BufferDesc *bufHdr;
4449 : :
8786 bruce@momjian.us 4450 [ - + + + : 236345017 : Assert(BufferIsPinned(buffer));
- + ]
4451 : :
10467 4452 [ + + ]: 236345017 : if (BufferIsLocal(buffer))
4114 andres@anarazel.de 4453 : 5507359 : bufHdr = GetLocalBufferDescriptor(-buffer - 1);
4454 : : else
4455 : 230837658 : bufHdr = GetBufferDescriptor(buffer - 1);
4456 : :
4457 : : /* pinned, so OK to read tag without spinlock */
7732 tgl@sss.pgh.pa.us 4458 : 236345017 : return bufHdr->tag.blockNum;
4459 : : }
4460 : :
4461 : : /*
4462 : : * BufferGetTag
4463 : : * Returns the relfilelocator, fork number and block number associated with
4464 : : * a buffer.
4465 : : */
4466 : : void
1399 rhaas@postgresql.org 4467 : 27813979 : BufferGetTag(Buffer buffer, RelFileLocator *rlocator, ForkNumber *forknum,
4468 : : BlockNumber *blknum)
4469 : : {
4470 : : BufferDesc *bufHdr;
4471 : :
4472 : : /* Do the same checks as BufferGetBlockNumber. */
6476 heikki.linnakangas@i 4473 [ - + - + : 27813979 : Assert(BufferIsPinned(buffer));
- + ]
4474 : :
8051 tgl@sss.pgh.pa.us 4475 [ - + ]: 27813979 : if (BufferIsLocal(buffer))
4114 andres@anarazel.de 4476 :UBC 0 : bufHdr = GetLocalBufferDescriptor(-buffer - 1);
4477 : : else
4114 andres@anarazel.de 4478 :CBC 27813979 : bufHdr = GetBufferDescriptor(buffer - 1);
4479 : :
4480 : : /* pinned, so OK to read tag without spinlock */
1350 rhaas@postgresql.org 4481 : 27813979 : *rlocator = BufTagGetRelFileLocator(&bufHdr->tag);
4482 : 27813979 : *forknum = BufTagGetForkNum(&bufHdr->tag);
6476 heikki.linnakangas@i 4483 : 27813979 : *blknum = bufHdr->tag.blockNum;
8051 tgl@sss.pgh.pa.us 4484 : 27813979 : }
4485 : :
4486 : : /*
4487 : : * FlushBuffer
4488 : : * Physically write out a shared buffer.
4489 : : *
4490 : : * NOTE: this actually just passes the buffer contents to the kernel; the
4491 : : * real write to disk won't happen until the kernel feels like it. This
4492 : : * is okay from our point of view since we can redo the changes from WAL.
4493 : : * However, we will need to force the changes to disk via fsync before
4494 : : * we can checkpoint WAL.
4495 : : *
4496 : : * The caller must hold a pin on the buffer and have
4497 : : * (share-)exclusively-locked the buffer contents.
4498 : : *
4499 : : * If the caller has an smgr reference for the buffer's relation, pass it
4500 : : * as the second parameter. If not, pass NULL.
4501 : : */
4502 : : static void
1181 andres@anarazel.de 4503 : 711755 : FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object,
4504 : : IOContext io_context)
4505 : : {
4506 : : XLogRecPtr recptr;
4507 : : ErrorContextCallback errcallback;
4508 : : instr_time io_start;
4509 : : Block bufBlock;
4510 : :
56 andres@anarazel.de 4511 [ + + - + ]:GNC 711755 : Assert(BufferLockHeldByMeInMode(buf, BUFFER_LOCK_EXCLUSIVE) ||
4512 : : BufferLockHeldByMeInMode(buf, BUFFER_LOCK_SHARE_EXCLUSIVE));
4513 : :
4514 : : /*
4515 : : * Try to start an I/O operation. If StartBufferIO returns false, then
4516 : : * someone else flushed the buffer before we could, so we need not do
4517 : : * anything.
4518 : : */
39 4519 [ + + ]: 711755 : if (StartSharedBufferIO(buf, false, true, NULL) == BUFFER_IO_ALREADY_DONE)
7732 tgl@sss.pgh.pa.us 4520 :CBC 7 : return;
4521 : :
4522 : : /* Setup error traceback support for ereport() */
4922 heikki.linnakangas@i 4523 : 711748 : errcallback.callback = shared_buffer_write_error_callback;
523 peter@eisentraut.org 4524 : 711748 : errcallback.arg = buf;
4922 heikki.linnakangas@i 4525 : 711748 : errcallback.previous = error_context_stack;
4526 : 711748 : error_context_stack = &errcallback;
4527 : :
4528 : : /* Find smgr relation for buffer */
8049 tgl@sss.pgh.pa.us 4529 [ + + ]: 711748 : if (reln == NULL)
793 heikki.linnakangas@i 4530 : 709018 : reln = smgropen(BufTagGetRelFileLocator(&buf->tag), INVALID_PROC_NUMBER);
4531 : :
4532 : : TRACE_POSTGRESQL_BUFFER_FLUSH_START(BufTagGetForkNum(&buf->tag),
4533 : : buf->tag.blockNum,
4534 : : reln->smgr_rlocator.locator.spcOid,
4535 : : reln->smgr_rlocator.locator.dbOid,
4536 : : reln->smgr_rlocator.locator.relNumber);
4537 : :
4538 : : /*
4539 : : * As we hold at least a share-exclusive lock on the buffer, the LSN
4540 : : * cannot change during the flush (and thus can't be torn).
4541 : : */
4792 simon@2ndQuadrant.co 4542 : 711748 : recptr = BufferGetLSN(buf);
4543 : :
4544 : : /*
4545 : : * Force XLOG flush up to buffer's LSN. This implements the basic WAL
4546 : : * rule that log updates must hit disk before any of the data-file changes
4547 : : * they describe do.
4548 : : *
4549 : : * However, this rule does not apply to unlogged relations, which will be
4550 : : * lost after a crash anyway. Most unlogged relation pages do not bear
4551 : : * LSNs since we never emit WAL records for them, and therefore flushing
4552 : : * up through the buffer LSN would be useless, but harmless. However,
4553 : : * some index AMs use LSNs internally to detect concurrent page
4554 : : * modifications, and therefore unlogged index pages bear "fake" LSNs
4555 : : * generated by XLogGetFakeLSN. It is unlikely but possible that the fake
4556 : : * LSN counter could advance past the WAL insertion point; and if it did
4557 : : * happen, attempting to flush WAL through that location would fail, with
4558 : : * disastrous system-wide consequences. To make sure that can't happen,
4559 : : * skip the flush if the buffer isn't permanent.
4560 : : */
55 andres@anarazel.de 4561 [ + + ]:GNC 711748 : if (pg_atomic_read_u64(&buf->state) & BM_PERMANENT)
4831 heikki.linnakangas@i 4562 :CBC 709928 : XLogFlush(recptr);
4563 : :
4564 : : /*
4565 : : * Now it's safe to write the buffer to disk. Note that no one else should
4566 : : * have been able to write it, while we were busy with log flushing,
4567 : : * because we got the exclusive right to perform I/O by setting the
4568 : : * BM_IO_IN_PROGRESS bit.
4569 : : */
4792 simon@2ndQuadrant.co 4570 : 711748 : bufBlock = BufHdrGetBlock(buf);
4571 : :
4572 : : /* Update page checksum if desired. */
39 andres@anarazel.de 4573 :GNC 711748 : PageSetChecksum((Page) bufBlock, buf->tag.blockNum);
4574 : :
433 michael@paquier.xyz 4575 :CBC 711748 : io_start = pgstat_prepare_io_time(track_io_timing);
4576 : :
8120 tgl@sss.pgh.pa.us 4577 : 711748 : smgrwrite(reln,
1350 rhaas@postgresql.org 4578 : 711748 : BufTagGetForkNum(&buf->tag),
4579 : : buf->tag.blockNum,
4580 : : bufBlock,
4581 : : false);
4582 : :
4583 : : /*
4584 : : * When a strategy is in use, only flushes of dirty buffers already in the
4585 : : * strategy ring are counted as strategy writes (IOCONTEXT
4586 : : * [BULKREAD|BULKWRITE|VACUUM] IOOP_WRITE) for the purpose of IO
4587 : : * statistics tracking.
4588 : : *
4589 : : * If a shared buffer initially added to the ring must be flushed before
4590 : : * being used, this is counted as an IOCONTEXT_NORMAL IOOP_WRITE.
4591 : : *
4592 : : * If a shared buffer which was added to the ring later because the
4593 : : * current strategy buffer is pinned or in use or because all strategy
4594 : : * buffers were dirty and rejected (for BAS_BULKREAD operations only)
4595 : : * requires flushing, this is counted as an IOCONTEXT_NORMAL IOOP_WRITE
4596 : : * (from_ring will be false).
4597 : : *
4598 : : * When a strategy is not in use, the write can only be a "regular" write
4599 : : * of a dirty shared buffer (IOCONTEXT_NORMAL IOOP_WRITE).
4600 : : */
14 melanieplageman@gmai 4601 :GNC 711748 : pgstat_count_io_op_time(io_object, io_context,
4602 : : IOOP_WRITE, io_start, 1, BLCKSZ);
4603 : :
5985 rhaas@postgresql.org 4604 :CBC 711748 : pgBufferUsage.shared_blks_written++;
4605 : :
4606 : : /*
4607 : : * Mark the buffer as clean and end the BM_IO_IN_PROGRESS state.
4608 : : */
401 andres@anarazel.de 4609 : 711748 : TerminateBufferIO(buf, true, 0, true, false);
4610 : :
4611 : : TRACE_POSTGRESQL_BUFFER_FLUSH_DONE(BufTagGetForkNum(&buf->tag),
4612 : : buf->tag.blockNum,
4613 : : reln->smgr_rlocator.locator.spcOid,
4614 : : reln->smgr_rlocator.locator.dbOid,
4615 : : reln->smgr_rlocator.locator.relNumber);
4616 : :
4617 : : /* Pop the error context stack */
4922 heikki.linnakangas@i 4618 : 711748 : error_context_stack = errcallback.previous;
4619 : : }
4620 : :
4621 : : /*
4622 : : * Convenience wrapper around FlushBuffer() that locks/unlocks the buffer
4623 : : * before/after calling FlushBuffer().
4624 : : */
4625 : : static void
209 andres@anarazel.de 4626 :GNC 363023 : FlushUnlockedBuffer(BufferDesc *buf, SMgrRelation reln,
4627 : : IOObject io_object, IOContext io_context)
4628 : : {
110 4629 : 363023 : Buffer buffer = BufferDescriptorGetBuffer(buf);
4630 : :
56 4631 : 363023 : BufferLockAcquire(buffer, buf, BUFFER_LOCK_SHARE_EXCLUSIVE);
14 melanieplageman@gmai 4632 : 363023 : FlushBuffer(buf, reln, io_object, io_context);
110 andres@anarazel.de 4633 : 363023 : BufferLockUnlock(buffer, buf);
209 4634 : 363023 : }
4635 : :
4636 : : /*
4637 : : * RelationGetNumberOfBlocksInFork
4638 : : * Determines the current number of pages in the specified relation fork.
4639 : : *
4640 : : * Note that the accuracy of the result will depend on the details of the
4641 : : * relation's storage. For builtin AMs it'll be accurate, but for external AMs
4642 : : * it might not be.
4643 : : */
4644 : : BlockNumber
5606 rhaas@postgresql.org 4645 :CBC 2507276 : RelationGetNumberOfBlocksInFork(Relation relation, ForkNumber forkNum)
4646 : : {
1614 peter@eisentraut.org 4647 [ + + + + : 2507276 : if (RELKIND_HAS_TABLE_AM(relation->rd_rel->relkind))
+ + ]
4648 : : {
4649 : : /*
4650 : : * Not every table AM uses BLCKSZ wide fixed size blocks. Therefore
4651 : : * tableam returns the size in bytes - but for the purpose of this
4652 : : * routine, we want the number of blocks. Therefore divide, rounding
4653 : : * up.
4654 : : */
4655 : : uint64 szbytes;
4656 : :
4657 : 1819422 : szbytes = table_relation_size(relation, forkNum);
4658 : :
4659 : 1819403 : return (szbytes + (BLCKSZ - 1)) / BLCKSZ;
4660 : : }
4661 [ + - + + : 687854 : else if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind))
- + - - -
- ]
4662 : : {
1454 tgl@sss.pgh.pa.us 4663 : 687854 : return smgrnblocks(RelationGetSmgr(relation), forkNum);
4664 : : }
4665 : : else
1614 peter@eisentraut.org 4666 :UBC 0 : Assert(false);
4667 : :
4668 : : return 0; /* keep compiler quiet */
4669 : : }
4670 : :
4671 : : /*
4672 : : * BufferIsPermanent
4673 : : * Determines whether a buffer will potentially still be around after
4674 : : * a crash. Caller must hold a buffer pin.
4675 : : */
4676 : : bool
5303 rhaas@postgresql.org 4677 :CBC 17654831 : BufferIsPermanent(Buffer buffer)
4678 : : {
4679 : : BufferDesc *bufHdr;
4680 : :
4681 : : /* Local buffers are used only for temp relations. */
4682 [ + + ]: 17654831 : if (BufferIsLocal(buffer))
4683 : 937354 : return false;
4684 : :
4685 : : /* Make sure we've got a real buffer, and that we hold a pin on it. */
4686 [ - + ]: 16717477 : Assert(BufferIsValid(buffer));
4687 [ - + - + : 16717477 : Assert(BufferIsPinned(buffer));
- + ]
4688 : :
4689 : : /*
4690 : : * BM_PERMANENT can't be changed while we hold a pin on the buffer, so we
4691 : : * need not bother with the buffer header spinlock. Even if someone else
4692 : : * changes the buffer header state while we're doing this, the state is
4693 : : * changed atomically, so we'll read the old value or the new value, but
4694 : : * not random garbage.
4695 : : */
4114 andres@anarazel.de 4696 : 16717477 : bufHdr = GetBufferDescriptor(buffer - 1);
110 andres@anarazel.de 4697 :GNC 16717477 : return (pg_atomic_read_u64(&bufHdr->state) & BM_PERMANENT) != 0;
4698 : : }
4699 : :
4700 : : /*
4701 : : * BufferGetLSNAtomic
4702 : : * Retrieves the LSN of the buffer atomically.
4703 : : *
4704 : : * This is necessary for some callers who may only hold a share lock on
4705 : : * the buffer. A share lock allows a concurrent backend to set hint bits
4706 : : * on the page, which in turn may require a WAL record to be emitted.
4707 : : *
4708 : : * On platforms with 8 byte atomic reads/writes, we don't need to do any
4709 : : * additional locking. On platforms not supporting such 8 byte atomic
4710 : : * reads/writes, we need to actually take the header lock.
4711 : : */
4712 : : XLogRecPtr
4792 simon@2ndQuadrant.co 4713 :CBC 8106325 : BufferGetLSNAtomic(Buffer buffer)
4714 : : {
4715 : : /* Make sure we've got a real buffer, and that we hold a pin on it. */
4716 [ - + ]: 8106325 : Assert(BufferIsValid(buffer));
4717 [ - + + + : 8106325 : Assert(BufferIsPinned(buffer));
- + ]
4718 : :
4719 : : #ifdef PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY
55 tomas.vondra@postgre 4720 :GNC 8106325 : return PageGetLSN(BufferGetPage(buffer));
4721 : : #else
4722 : : {
4723 : : char *page = BufferGetPage(buffer);
4724 : : BufferDesc *bufHdr;
4725 : : XLogRecPtr lsn;
4726 : :
4727 : : /*
4728 : : * If we don't need locking for correctness, fastpath out.
4729 : : */
4730 : : if (!XLogHintBitIsNeeded() || BufferIsLocal(buffer))
4731 : : return PageGetLSN(page);
4732 : :
4733 : : bufHdr = GetBufferDescriptor(buffer - 1);
4734 : : LockBufHdr(bufHdr);
4735 : : lsn = PageGetLSN(page);
4736 : : UnlockBufHdr(bufHdr);
4737 : :
4738 : : return lsn;
4739 : : }
4740 : : #endif
4741 : : }
4742 : :
4743 : : /* ---------------------------------------------------------------------
4744 : : * DropRelationBuffers
4745 : : *
4746 : : * This function removes from the buffer pool all the pages of the
4747 : : * specified relation forks that have block numbers >= firstDelBlock.
4748 : : * (In particular, with firstDelBlock = 0, all pages are removed.)
4749 : : * Dirty pages are simply dropped, without bothering to write them
4750 : : * out first. Therefore, this is NOT rollback-able, and so should be
4751 : : * used only with extreme caution!
4752 : : *
4753 : : * Currently, this is called only from smgr.c when the underlying file
4754 : : * is about to be deleted or truncated (firstDelBlock is needed for
4755 : : * the truncation case). The data in the affected pages would therefore
4756 : : * be deleted momentarily anyway, and there is no point in writing it.
4757 : : * It is the responsibility of higher-level code to ensure that the
4758 : : * deletion or truncation does not lose any data that could be needed
4759 : : * later. It is also the responsibility of higher-level code to ensure
4760 : : * that no other process could be trying to load more pages of the
4761 : : * relation into buffers.
4762 : : * --------------------------------------------------------------------
4763 : : */
4764 : : void
1393 rhaas@postgresql.org 4765 :CBC 804 : DropRelationBuffers(SMgrRelation smgr_reln, ForkNumber *forkNum,
4766 : : int nforks, BlockNumber *firstDelBlock)
4767 : : {
4768 : : int i;
4769 : : int j;
4770 : : RelFileLocatorBackend rlocator;
4771 : : BlockNumber nForkBlock[MAX_FORKNUM];
1819 tgl@sss.pgh.pa.us 4772 : 804 : uint64 nBlocksToInvalidate = 0;
4773 : :
1399 rhaas@postgresql.org 4774 : 804 : rlocator = smgr_reln->smgr_rlocator;
4775 : :
4776 : : /* If it's a local relation, it's localbuf.c's problem. */
4777 [ + + ]: 804 : if (RelFileLocatorBackendIsTemp(rlocator))
4778 : : {
793 heikki.linnakangas@i 4779 [ + - ]: 498 : if (rlocator.backend == MyProcNumber)
305 fujii@postgresql.org 4780 :GNC 498 : DropRelationLocalBuffers(rlocator.locator, forkNum, nforks,
4781 : : firstDelBlock);
4782 : :
8673 tgl@sss.pgh.pa.us 4783 :CBC 541 : return;
4784 : : }
4785 : :
4786 : : /*
4787 : : * To remove all the pages of the specified relation forks from the buffer
4788 : : * pool, we need to scan the entire buffer pool but we can optimize it by
4789 : : * finding the buffers from BufMapping table provided we know the exact
4790 : : * size of each fork of the relation. The exact size is required to ensure
4791 : : * that we don't leave any buffer for the relation being dropped as
4792 : : * otherwise the background writer or checkpointer can lead to a PANIC
4793 : : * error while flushing buffers corresponding to files that don't exist.
4794 : : *
4795 : : * To know the exact size, we rely on the size cached for each fork by us
4796 : : * during recovery which limits the optimization to recovery and on
4797 : : * standbys but we can easily extend it once we have shared cache for
4798 : : * relation size.
4799 : : *
4800 : : * In recovery, we cache the value returned by the first lseek(SEEK_END)
4801 : : * and the future writes keeps the cached value up-to-date. See
4802 : : * smgrextend. It is possible that the value of the first lseek is smaller
4803 : : * than the actual number of existing blocks in the file due to buggy
4804 : : * Linux kernels that might not have accounted for the recent write. But
4805 : : * that should be fine because there must not be any buffers after that
4806 : : * file size.
4807 : : */
1939 akapila@postgresql.o 4808 [ + + ]: 416 : for (i = 0; i < nforks; i++)
4809 : : {
4810 : : /* Get the number of blocks for a relation's fork */
4811 : 360 : nForkBlock[i] = smgrnblocks_cached(smgr_reln, forkNum[i]);
4812 : :
4813 [ + + ]: 360 : if (nForkBlock[i] == InvalidBlockNumber)
4814 : : {
4815 : 250 : nBlocksToInvalidate = InvalidBlockNumber;
4816 : 250 : break;
4817 : : }
4818 : :
4819 : : /* calculate the number of blocks to be invalidated */
4820 : 110 : nBlocksToInvalidate += (nForkBlock[i] - firstDelBlock[i]);
4821 : : }
4822 : :
4823 : : /*
4824 : : * We apply the optimization iff the total number of blocks to invalidate
4825 : : * is below the BUF_DROP_FULL_SCAN_THRESHOLD.
4826 : : */
4827 [ + + ]: 306 : if (BlockNumberIsValid(nBlocksToInvalidate) &&
4828 [ + + ]: 56 : nBlocksToInvalidate < BUF_DROP_FULL_SCAN_THRESHOLD)
4829 : : {
4830 [ + + ]: 121 : for (j = 0; j < nforks; j++)
1393 rhaas@postgresql.org 4831 : 78 : FindAndDropRelationBuffers(rlocator.locator, forkNum[j],
4832 : 78 : nForkBlock[j], firstDelBlock[j]);
1939 akapila@postgresql.o 4833 : 43 : return;
4834 : : }
4835 : :
7732 tgl@sss.pgh.pa.us 4836 [ + + ]: 3480199 : for (i = 0; i < NBuffers; i++)
4837 : : {
3823 rhaas@postgresql.org 4838 : 3479936 : BufferDesc *bufHdr = GetBufferDescriptor(i);
4839 : :
4840 : : /*
4841 : : * We can make this a tad faster by prechecking the buffer tag before
4842 : : * we attempt to lock the buffer; this saves a lot of lock
4843 : : * acquisitions in typical cases. It should be safe because the
4844 : : * caller must have AccessExclusiveLock on the relation, or some other
4845 : : * reason to be certain that no one is loading new pages of the rel
4846 : : * into the buffer pool. (Otherwise we might well miss such pages
4847 : : * entirely.) Therefore, while the tag might be changing while we
4848 : : * look at it, it can't be changing *to* a value we care about, only
4849 : : * *away* from such a value. So false negatives are impossible, and
4850 : : * false positives are safe because we'll recheck after getting the
4851 : : * buffer lock.
4852 : : *
4853 : : * We could check forkNum and blockNum as well as the rlocator, but
4854 : : * the incremental win from doing so seems small.
4855 : : */
1350 4856 [ + + ]: 3479936 : if (!BufTagMatchesRelFileLocator(&bufHdr->tag, &rlocator.locator))
5080 tgl@sss.pgh.pa.us 4857 : 3467796 : continue;
4858 : :
180 andres@anarazel.de 4859 :GNC 12140 : LockBufHdr(bufHdr);
4860 : :
2415 fujii@postgresql.org 4861 [ + + ]:CBC 30027 : for (j = 0; j < nforks; j++)
4862 : : {
1350 rhaas@postgresql.org 4863 [ + - ]: 21277 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rlocator.locator) &&
4864 [ + + ]: 21277 : BufTagGetForkNum(&bufHdr->tag) == forkNum[j] &&
2415 fujii@postgresql.org 4865 [ + + ]: 11996 : bufHdr->tag.blockNum >= firstDelBlock[j])
4866 : : {
2182 tgl@sss.pgh.pa.us 4867 : 3390 : InvalidateBuffer(bufHdr); /* releases spinlock */
2415 fujii@postgresql.org 4868 : 3390 : break;
4869 : : }
4870 : : }
4871 [ + + ]: 12140 : if (j >= nforks)
180 andres@anarazel.de 4872 :GNC 8750 : UnlockBufHdr(bufHdr);
4873 : : }
4874 : : }
4875 : :
4876 : : /* ---------------------------------------------------------------------
4877 : : * DropRelationsAllBuffers
4878 : : *
4879 : : * This function removes from the buffer pool all the pages of all
4880 : : * forks of the specified relations. It's equivalent to calling
4881 : : * DropRelationBuffers once per fork per relation with firstDelBlock = 0.
4882 : : * --------------------------------------------------------------------
4883 : : */
4884 : : void
1393 rhaas@postgresql.org 4885 :CBC 17832 : DropRelationsAllBuffers(SMgrRelation *smgr_reln, int nlocators)
4886 : : {
4887 : : int i;
1938 akapila@postgresql.o 4888 : 17832 : int n = 0;
4889 : : SMgrRelation *rels;
4890 : : BlockNumber (*block)[MAX_FORKNUM + 1];
1819 tgl@sss.pgh.pa.us 4891 : 17832 : uint64 nBlocksToInvalidate = 0;
4892 : : RelFileLocator *locators;
1938 akapila@postgresql.o 4893 : 17832 : bool cached = true;
4894 : : bool use_bsearch;
4895 : :
1399 rhaas@postgresql.org 4896 [ - + ]: 17832 : if (nlocators == 0)
4856 alvherre@alvh.no-ip. 4897 :UBC 0 : return;
4898 : :
145 michael@paquier.xyz 4899 :GNC 17832 : rels = palloc_array(SMgrRelation, nlocators); /* non-local relations */
4900 : :
4901 : : /* If it's a local relation, it's localbuf.c's problem. */
1399 rhaas@postgresql.org 4902 [ + + ]:CBC 78346 : for (i = 0; i < nlocators; i++)
4903 : : {
4904 [ + + ]: 60514 : if (RelFileLocatorBackendIsTemp(smgr_reln[i]->smgr_rlocator))
4905 : : {
793 heikki.linnakangas@i 4906 [ + - ]: 4407 : if (smgr_reln[i]->smgr_rlocator.backend == MyProcNumber)
1393 rhaas@postgresql.org 4907 : 4407 : DropRelationAllLocalBuffers(smgr_reln[i]->smgr_rlocator.locator);
4908 : : }
4909 : : else
1938 akapila@postgresql.o 4910 : 56107 : rels[n++] = smgr_reln[i];
4911 : : }
4912 : :
4913 : : /*
4914 : : * If there are no non-local relations, then we're done. Release the
4915 : : * memory and return.
4916 : : */
4856 alvherre@alvh.no-ip. 4917 [ + + ]: 17832 : if (n == 0)
4918 : : {
1938 akapila@postgresql.o 4919 : 1183 : pfree(rels);
5080 tgl@sss.pgh.pa.us 4920 : 1183 : return;
4921 : : }
4922 : :
4923 : : /*
4924 : : * This is used to remember the number of blocks for all the relations
4925 : : * forks.
4926 : : */
4927 : : block = (BlockNumber (*)[MAX_FORKNUM + 1])
1938 akapila@postgresql.o 4928 : 16649 : palloc(sizeof(BlockNumber) * n * (MAX_FORKNUM + 1));
4929 : :
4930 : : /*
4931 : : * We can avoid scanning the entire buffer pool if we know the exact size
4932 : : * of each of the given relation forks. See DropRelationBuffers.
4933 : : */
4934 [ + + + + ]: 34681 : for (i = 0; i < n && cached; i++)
4935 : : {
1350 drowley@postgresql.o 4936 [ + + ]: 27072 : for (int j = 0; j <= MAX_FORKNUM; j++)
4937 : : {
4938 : : /* Get the number of blocks for a relation's fork. */
1938 akapila@postgresql.o 4939 : 24831 : block[i][j] = smgrnblocks_cached(rels[i], j);
4940 : :
4941 : : /* We need to only consider the relation forks that exists. */
4942 [ + + ]: 24831 : if (block[i][j] == InvalidBlockNumber)
4943 : : {
4944 [ + + ]: 22411 : if (!smgrexists(rels[i], j))
4945 : 6620 : continue;
4946 : 15791 : cached = false;
4947 : 15791 : break;
4948 : : }
4949 : :
4950 : : /* calculate the total number of blocks to be invalidated */
4951 : 2420 : nBlocksToInvalidate += block[i][j];
4952 : : }
4953 : : }
4954 : :
4955 : : /*
4956 : : * We apply the optimization iff the total number of blocks to invalidate
4957 : : * is below the BUF_DROP_FULL_SCAN_THRESHOLD.
4958 : : */
4959 [ + + + + ]: 16649 : if (cached && nBlocksToInvalidate < BUF_DROP_FULL_SCAN_THRESHOLD)
4960 : : {
4961 [ + + ]: 1418 : for (i = 0; i < n; i++)
4962 : : {
1350 drowley@postgresql.o 4963 [ + + ]: 3915 : for (int j = 0; j <= MAX_FORKNUM; j++)
4964 : : {
4965 : : /* ignore relation forks that doesn't exist */
1938 akapila@postgresql.o 4966 [ + + ]: 3132 : if (!BlockNumberIsValid(block[i][j]))
4967 : 2338 : continue;
4968 : :
4969 : : /* drop all the buffers for a particular relation fork */
1393 rhaas@postgresql.org 4970 : 794 : FindAndDropRelationBuffers(rels[i]->smgr_rlocator.locator,
4971 : 794 : j, block[i][j], 0);
4972 : : }
4973 : : }
4974 : :
1938 akapila@postgresql.o 4975 : 635 : pfree(block);
4976 : 635 : pfree(rels);
4977 : 635 : return;
4978 : : }
4979 : :
4980 : 16014 : pfree(block);
145 michael@paquier.xyz 4981 :GNC 16014 : locators = palloc_array(RelFileLocator, n); /* non-local relations */
1938 akapila@postgresql.o 4982 [ + + ]:CBC 71338 : for (i = 0; i < n; i++)
1399 rhaas@postgresql.org 4983 : 55324 : locators[i] = rels[i]->smgr_rlocator.locator;
4984 : :
4985 : : /*
4986 : : * For low number of relations to drop just use a simple walk through, to
4987 : : * save the bsearch overhead. The threshold to use is rather a guess than
4988 : : * an exactly determined value, as it depends on many factors (CPU and RAM
4989 : : * speeds, amount of shared buffers etc.).
4990 : : */
2222 noah@leadboat.com 4991 : 16014 : use_bsearch = n > RELS_BSEARCH_THRESHOLD;
4992 : :
4993 : : /* sort the list of rlocators if necessary */
4856 alvherre@alvh.no-ip. 4994 [ + + ]: 16014 : if (use_bsearch)
809 nathan@postgresql.or 4995 : 218 : qsort(locators, n, sizeof(RelFileLocator), rlocator_comparator);
4996 : :
5080 tgl@sss.pgh.pa.us 4997 [ + + ]: 186815246 : for (i = 0; i < NBuffers; i++)
4998 : : {
1399 rhaas@postgresql.org 4999 : 186799232 : RelFileLocator *rlocator = NULL;
3823 5000 : 186799232 : BufferDesc *bufHdr = GetBufferDescriptor(i);
5001 : :
5002 : : /*
5003 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
5004 : : * saves some cycles.
5005 : : */
5006 : :
4856 alvherre@alvh.no-ip. 5007 [ + + ]: 186799232 : if (!use_bsearch)
5008 : : {
5009 : : int j;
5010 : :
5011 [ + + ]: 742489842 : for (j = 0; j < n; j++)
5012 : : {
1350 rhaas@postgresql.org 5013 [ + + ]: 558296172 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &locators[j]))
5014 : : {
1399 5015 : 106746 : rlocator = &locators[j];
4856 alvherre@alvh.no-ip. 5016 : 106746 : break;
5017 : : }
5018 : : }
5019 : : }
5020 : : else
5021 : : {
5022 : : RelFileLocator locator;
5023 : :
1350 rhaas@postgresql.org 5024 : 2498816 : locator = BufTagGetRelFileLocator(&bufHdr->tag);
515 peter@eisentraut.org 5025 : 2498816 : rlocator = bsearch(&locator,
5026 : : locators, n, sizeof(RelFileLocator),
5027 : : rlocator_comparator);
5028 : : }
5029 : :
5030 : : /* buffer doesn't belong to any of the given relfilelocators; skip it */
1399 rhaas@postgresql.org 5031 [ + + ]: 186799232 : if (rlocator == NULL)
5080 tgl@sss.pgh.pa.us 5032 : 186690717 : continue;
5033 : :
180 andres@anarazel.de 5034 :GNC 108515 : LockBufHdr(bufHdr);
1350 rhaas@postgresql.org 5035 [ + - ]:CBC 108515 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, rlocator))
5080 tgl@sss.pgh.pa.us 5036 : 108515 : InvalidateBuffer(bufHdr); /* releases spinlock */
5037 : : else
180 andres@anarazel.de 5038 :UNC 0 : UnlockBufHdr(bufHdr);
5039 : : }
5040 : :
1399 rhaas@postgresql.org 5041 :CBC 16014 : pfree(locators);
1938 akapila@postgresql.o 5042 : 16014 : pfree(rels);
5043 : : }
5044 : :
5045 : : /* ---------------------------------------------------------------------
5046 : : * FindAndDropRelationBuffers
5047 : : *
5048 : : * This function performs look up in BufMapping table and removes from the
5049 : : * buffer pool all the pages of the specified relation fork that has block
5050 : : * number >= firstDelBlock. (In particular, with firstDelBlock = 0, all
5051 : : * pages are removed.)
5052 : : * --------------------------------------------------------------------
5053 : : */
5054 : : static void
1393 rhaas@postgresql.org 5055 : 872 : FindAndDropRelationBuffers(RelFileLocator rlocator, ForkNumber forkNum,
5056 : : BlockNumber nForkBlock,
5057 : : BlockNumber firstDelBlock)
5058 : : {
5059 : : BlockNumber curBlock;
5060 : :
1939 akapila@postgresql.o 5061 [ + + ]: 2087 : for (curBlock = firstDelBlock; curBlock < nForkBlock; curBlock++)
5062 : : {
5063 : : uint32 bufHash; /* hash value for tag */
5064 : : BufferTag bufTag; /* identity of requested block */
5065 : : LWLock *bufPartitionLock; /* buffer partition lock for it */
5066 : : int buf_id;
5067 : : BufferDesc *bufHdr;
5068 : :
5069 : : /* create a tag so we can lookup the buffer */
1378 rhaas@postgresql.org 5070 : 1215 : InitBufferTag(&bufTag, &rlocator, forkNum, curBlock);
5071 : :
5072 : : /* determine its hash code and partition lock ID */
1939 akapila@postgresql.o 5073 : 1215 : bufHash = BufTableHashCode(&bufTag);
5074 : 1215 : bufPartitionLock = BufMappingPartitionLock(bufHash);
5075 : :
5076 : : /* Check that it is in the buffer pool. If not, do nothing. */
5077 : 1215 : LWLockAcquire(bufPartitionLock, LW_SHARED);
5078 : 1215 : buf_id = BufTableLookup(&bufTag, bufHash);
5079 : 1215 : LWLockRelease(bufPartitionLock);
5080 : :
5081 [ + + ]: 1215 : if (buf_id < 0)
5082 : 108 : continue;
5083 : :
5084 : 1107 : bufHdr = GetBufferDescriptor(buf_id);
5085 : :
5086 : : /*
5087 : : * We need to lock the buffer header and recheck if the buffer is
5088 : : * still associated with the same block because the buffer could be
5089 : : * evicted by some other backend loading blocks for a different
5090 : : * relation after we release lock on the BufMapping table.
5091 : : */
180 andres@anarazel.de 5092 :GNC 1107 : LockBufHdr(bufHdr);
5093 : :
1350 rhaas@postgresql.org 5094 [ + - + - ]:CBC 2214 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rlocator) &&
5095 : 1107 : BufTagGetForkNum(&bufHdr->tag) == forkNum &&
1939 akapila@postgresql.o 5096 [ + - ]: 1107 : bufHdr->tag.blockNum >= firstDelBlock)
5097 : 1107 : InvalidateBuffer(bufHdr); /* releases spinlock */
5098 : : else
180 andres@anarazel.de 5099 :UNC 0 : UnlockBufHdr(bufHdr);
5100 : : }
1939 akapila@postgresql.o 5101 :CBC 872 : }
5102 : :
5103 : : /* ---------------------------------------------------------------------
5104 : : * DropDatabaseBuffers
5105 : : *
5106 : : * This function removes all the buffers in the buffer cache for a
5107 : : * particular database. Dirty pages are simply dropped, without
5108 : : * bothering to write them out first. This is used when we destroy a
5109 : : * database, to avoid trying to flush data to disk when the directory
5110 : : * tree no longer exists. Implementation is pretty similar to
5111 : : * DropRelationBuffers() which is for destroying just one relation.
5112 : : * --------------------------------------------------------------------
5113 : : */
5114 : : void
7342 tgl@sss.pgh.pa.us 5115 : 81 : DropDatabaseBuffers(Oid dbid)
5116 : : {
5117 : : int i;
5118 : :
5119 : : /*
5120 : : * We needn't consider local buffers, since by assumption the target
5121 : : * database isn't our own.
5122 : : */
5123 : :
7732 5124 [ + + ]: 628177 : for (i = 0; i < NBuffers; i++)
5125 : : {
3823 rhaas@postgresql.org 5126 : 628096 : BufferDesc *bufHdr = GetBufferDescriptor(i);
5127 : :
5128 : : /*
5129 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
5130 : : * saves some cycles.
5131 : : */
1350 5132 [ + + ]: 628096 : if (bufHdr->tag.dbOid != dbid)
5080 tgl@sss.pgh.pa.us 5133 : 613220 : continue;
5134 : :
180 andres@anarazel.de 5135 :GNC 14876 : LockBufHdr(bufHdr);
1350 rhaas@postgresql.org 5136 [ + - ]:CBC 14876 : if (bufHdr->tag.dbOid == dbid)
7507 bruce@momjian.us 5137 : 14876 : InvalidateBuffer(bufHdr); /* releases spinlock */
5138 : : else
180 andres@anarazel.de 5139 :UNC 0 : UnlockBufHdr(bufHdr);
5140 : : }
10892 scrappy@hub.org 5141 :CBC 81 : }
5142 : :
5143 : : /* ---------------------------------------------------------------------
5144 : : * FlushRelationBuffers
5145 : : *
5146 : : * This function writes all dirty pages of a relation out to disk
5147 : : * (or more accurately, out to kernel disk buffers), ensuring that the
5148 : : * kernel has an up-to-date view of the relation.
5149 : : *
5150 : : * Generally, the caller should be holding AccessExclusiveLock on the
5151 : : * target relation to ensure that no other backend is busy dirtying
5152 : : * more blocks of the relation; the effects can't be expected to last
5153 : : * after the lock is released.
5154 : : *
5155 : : * XXX currently it sequentially searches the buffer pool, should be
5156 : : * changed to more clever ways of searching. This routine is not
5157 : : * used in any performance-critical code paths, so it's not worth
5158 : : * adding additional overhead to normal paths to make it go faster.
5159 : : * --------------------------------------------------------------------
5160 : : */
5161 : : void
7716 tgl@sss.pgh.pa.us 5162 : 167 : FlushRelationBuffers(Relation rel)
5163 : : {
5164 : : int i;
5165 : : BufferDesc *bufHdr;
825 heikki.linnakangas@i 5166 : 167 : SMgrRelation srel = RelationGetSmgr(rel);
5167 : :
5622 rhaas@postgresql.org 5168 [ + + ]: 167 : if (RelationUsesLocalBuffers(rel))
5169 : : {
10452 vadim4o@yahoo.com 5170 [ + + ]: 1212 : for (i = 0; i < NLocBuffer; i++)
5171 : : {
5172 : : uint64 buf_state;
5173 : :
4114 andres@anarazel.de 5174 : 1200 : bufHdr = GetLocalBufferDescriptor(i);
1350 rhaas@postgresql.org 5175 [ + + ]: 1200 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rel->rd_locator) &&
110 andres@anarazel.de 5176 [ + + ]:GNC 400 : ((buf_state = pg_atomic_read_u64(&bufHdr->state)) &
5177 : : (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
5178 : : {
5179 : : ErrorContextCallback errcallback;
5180 : :
5181 : : /* Setup error traceback support for ereport() */
4922 heikki.linnakangas@i 5182 :CBC 392 : errcallback.callback = local_buffer_write_error_callback;
523 peter@eisentraut.org 5183 : 392 : errcallback.arg = bufHdr;
4922 heikki.linnakangas@i 5184 : 392 : errcallback.previous = error_context_stack;
5185 : 392 : error_context_stack = &errcallback;
5186 : :
5187 : : /* Make sure we can handle the pin */
393 andres@anarazel.de 5188 : 392 : ReservePrivateRefCountEntry();
5189 : 392 : ResourceOwnerEnlarge(CurrentResourceOwner);
5190 : :
5191 : : /*
5192 : : * Pin/unpin mostly to make valgrind work, but it also seems
5193 : : * like the right thing to do.
5194 : : */
5195 : 392 : PinLocalBuffer(bufHdr, false);
5196 : :
5197 : :
416 5198 : 392 : FlushLocalBuffer(bufHdr, srel);
5199 : :
393 5200 : 392 : UnpinLocalBuffer(BufferDescriptorGetBuffer(bufHdr));
5201 : :
5202 : : /* Pop the error context stack */
4922 heikki.linnakangas@i 5203 : 392 : error_context_stack = errcallback.previous;
5204 : : }
5205 : : }
5206 : :
8009 tgl@sss.pgh.pa.us 5207 : 12 : return;
5208 : : }
5209 : :
10452 vadim4o@yahoo.com 5210 [ + + ]: 1938203 : for (i = 0; i < NBuffers; i++)
5211 : : {
5212 : : uint64 buf_state;
5213 : :
4114 andres@anarazel.de 5214 : 1938048 : bufHdr = GetBufferDescriptor(i);
5215 : :
5216 : : /*
5217 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
5218 : : * saves some cycles.
5219 : : */
1350 rhaas@postgresql.org 5220 [ + + ]: 1938048 : if (!BufTagMatchesRelFileLocator(&bufHdr->tag, &rel->rd_locator))
5080 tgl@sss.pgh.pa.us 5221 : 1937802 : continue;
5222 : :
5223 : : /* Make sure we can handle the pin */
4124 andres@anarazel.de 5224 : 246 : ReservePrivateRefCountEntry();
909 heikki.linnakangas@i 5225 : 246 : ResourceOwnerEnlarge(CurrentResourceOwner);
5226 : :
3677 andres@anarazel.de 5227 : 246 : buf_state = LockBufHdr(bufHdr);
1350 rhaas@postgresql.org 5228 [ + - ]: 246 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rel->rd_locator) &&
3677 andres@anarazel.de 5229 [ + + ]: 246 : (buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
5230 : : {
7716 tgl@sss.pgh.pa.us 5231 : 204 : PinBuffer_Locked(bufHdr);
209 andres@anarazel.de 5232 :GNC 204 : FlushUnlockedBuffer(bufHdr, srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
1313 michael@paquier.xyz 5233 :CBC 204 : UnpinBuffer(bufHdr);
5234 : : }
5235 : : else
180 andres@anarazel.de 5236 :GNC 42 : UnlockBufHdr(bufHdr);
5237 : : }
5238 : : }
5239 : :
5240 : : /* ---------------------------------------------------------------------
5241 : : * FlushRelationsAllBuffers
5242 : : *
5243 : : * This function flushes out of the buffer pool all the pages of all
5244 : : * forks of the specified smgr relations. It's equivalent to calling
5245 : : * FlushRelationBuffers once per relation. The relations are assumed not
5246 : : * to use local buffers.
5247 : : * --------------------------------------------------------------------
5248 : : */
5249 : : void
2222 noah@leadboat.com 5250 :CBC 5 : FlushRelationsAllBuffers(SMgrRelation *smgrs, int nrels)
5251 : : {
5252 : : int i;
5253 : : SMgrSortArray *srels;
5254 : : bool use_bsearch;
5255 : :
5256 [ - + ]: 5 : if (nrels == 0)
2222 noah@leadboat.com 5257 :UBC 0 : return;
5258 : :
5259 : : /* fill-in array for qsort */
145 michael@paquier.xyz 5260 :GNC 5 : srels = palloc_array(SMgrSortArray, nrels);
5261 : :
2222 noah@leadboat.com 5262 [ + + ]:CBC 10 : for (i = 0; i < nrels; i++)
5263 : : {
1399 rhaas@postgresql.org 5264 [ - + ]: 5 : Assert(!RelFileLocatorBackendIsTemp(smgrs[i]->smgr_rlocator));
5265 : :
5266 : 5 : srels[i].rlocator = smgrs[i]->smgr_rlocator.locator;
2222 noah@leadboat.com 5267 : 5 : srels[i].srel = smgrs[i];
5268 : : }
5269 : :
5270 : : /*
5271 : : * Save the bsearch overhead for low number of relations to sync. See
5272 : : * DropRelationsAllBuffers for details.
5273 : : */
5274 : 5 : use_bsearch = nrels > RELS_BSEARCH_THRESHOLD;
5275 : :
5276 : : /* sort the list of SMgrRelations if necessary */
5277 [ - + ]: 5 : if (use_bsearch)
809 nathan@postgresql.or 5278 :UBC 0 : qsort(srels, nrels, sizeof(SMgrSortArray), rlocator_comparator);
5279 : :
2222 noah@leadboat.com 5280 [ + + ]:CBC 81925 : for (i = 0; i < NBuffers; i++)
5281 : : {
5282 : 81920 : SMgrSortArray *srelent = NULL;
5283 : 81920 : BufferDesc *bufHdr = GetBufferDescriptor(i);
5284 : : uint64 buf_state;
5285 : :
5286 : : /*
5287 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
5288 : : * saves some cycles.
5289 : : */
5290 : :
5291 [ + - ]: 81920 : if (!use_bsearch)
5292 : : {
5293 : : int j;
5294 : :
5295 [ + + ]: 161277 : for (j = 0; j < nrels; j++)
5296 : : {
1350 rhaas@postgresql.org 5297 [ + + ]: 81920 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &srels[j].rlocator))
5298 : : {
2222 noah@leadboat.com 5299 : 2563 : srelent = &srels[j];
5300 : 2563 : break;
5301 : : }
5302 : : }
5303 : : }
5304 : : else
5305 : : {
5306 : : RelFileLocator rlocator;
5307 : :
1350 rhaas@postgresql.org 5308 :UBC 0 : rlocator = BufTagGetRelFileLocator(&bufHdr->tag);
515 peter@eisentraut.org 5309 : 0 : srelent = bsearch(&rlocator,
5310 : : srels, nrels, sizeof(SMgrSortArray),
5311 : : rlocator_comparator);
5312 : : }
5313 : :
5314 : : /* buffer doesn't belong to any of the given relfilelocators; skip it */
2222 noah@leadboat.com 5315 [ + + ]:CBC 81920 : if (srelent == NULL)
5316 : 79357 : continue;
5317 : :
5318 : : /* Make sure we can handle the pin */
5319 : 2563 : ReservePrivateRefCountEntry();
909 heikki.linnakangas@i 5320 : 2563 : ResourceOwnerEnlarge(CurrentResourceOwner);
5321 : :
2222 noah@leadboat.com 5322 : 2563 : buf_state = LockBufHdr(bufHdr);
1350 rhaas@postgresql.org 5323 [ + - ]: 2563 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &srelent->rlocator) &&
2222 noah@leadboat.com 5324 [ + + ]: 2563 : (buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
5325 : : {
5326 : 2526 : PinBuffer_Locked(bufHdr);
209 andres@anarazel.de 5327 :GNC 2526 : FlushUnlockedBuffer(bufHdr, srelent->srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
1313 michael@paquier.xyz 5328 :CBC 2526 : UnpinBuffer(bufHdr);
5329 : : }
5330 : : else
180 andres@anarazel.de 5331 :GNC 37 : UnlockBufHdr(bufHdr);
5332 : : }
5333 : :
2222 noah@leadboat.com 5334 :CBC 5 : pfree(srels);
5335 : : }
5336 : :
5337 : : /* ---------------------------------------------------------------------
5338 : : * RelationCopyStorageUsingBuffer
5339 : : *
5340 : : * Copy fork's data using bufmgr. Same as RelationCopyStorage but instead
5341 : : * of using smgrread and smgrextend this will copy using bufmgr APIs.
5342 : : *
5343 : : * Refer comments atop CreateAndCopyRelationData() for details about
5344 : : * 'permanent' parameter.
5345 : : * --------------------------------------------------------------------
5346 : : */
5347 : : static void
1362 rhaas@postgresql.org 5348 : 85895 : RelationCopyStorageUsingBuffer(RelFileLocator srclocator,
5349 : : RelFileLocator dstlocator,
5350 : : ForkNumber forkNum, bool permanent)
5351 : : {
5352 : : Buffer srcBuf;
5353 : : Buffer dstBuf;
5354 : : Page srcPage;
5355 : : Page dstPage;
5356 : : bool use_wal;
5357 : : BlockNumber nblocks;
5358 : : BlockNumber blkno;
5359 : : PGIOAlignedBlock buf;
5360 : : BufferAccessStrategy bstrategy_src;
5361 : : BufferAccessStrategy bstrategy_dst;
5362 : : BlockRangeReadStreamPrivate p;
5363 : : ReadStream *src_stream;
5364 : : SMgrRelation src_smgr;
5365 : :
5366 : : /*
5367 : : * In general, we want to write WAL whenever wal_level > 'minimal', but we
5368 : : * can skip it when copying any fork of an unlogged relation other than
5369 : : * the init fork.
5370 : : */
1498 5371 [ + + - + : 85895 : use_wal = XLogIsNeeded() && (permanent || forkNum == INIT_FORKNUM);
- - ]
5372 : :
5373 : : /* Get number of blocks in the source relation. */
793 heikki.linnakangas@i 5374 : 85895 : nblocks = smgrnblocks(smgropen(srclocator, INVALID_PROC_NUMBER),
5375 : : forkNum);
5376 : :
5377 : : /* Nothing to copy; just return. */
1498 rhaas@postgresql.org 5378 [ + + ]: 85895 : if (nblocks == 0)
5379 : 15933 : return;
5380 : :
5381 : : /*
5382 : : * Bulk extend the destination relation of the same size as the source
5383 : : * relation before starting to copy block by block.
5384 : : */
1356 5385 : 69962 : memset(buf.data, 0, BLCKSZ);
793 heikki.linnakangas@i 5386 : 69962 : smgrextend(smgropen(dstlocator, INVALID_PROC_NUMBER), forkNum, nblocks - 1,
5387 : : buf.data, true);
5388 : :
5389 : : /* This is a bulk operation, so use buffer access strategies. */
1498 rhaas@postgresql.org 5390 : 69962 : bstrategy_src = GetAccessStrategy(BAS_BULKREAD);
5391 : 69962 : bstrategy_dst = GetAccessStrategy(BAS_BULKWRITE);
5392 : :
5393 : : /* Initialize streaming read */
609 noah@leadboat.com 5394 : 69962 : p.current_blocknum = 0;
5395 : 69962 : p.last_exclusive = nblocks;
654 5396 : 69962 : src_smgr = smgropen(srclocator, INVALID_PROC_NUMBER);
5397 : :
5398 : : /*
5399 : : * It is safe to use batchmode as block_range_read_stream_cb takes no
5400 : : * locks.
5401 : : */
401 andres@anarazel.de 5402 [ + - ]: 69962 : src_stream = read_stream_begin_smgr_relation(READ_STREAM_FULL |
5403 : : READ_STREAM_USE_BATCHING,
5404 : : bstrategy_src,
5405 : : src_smgr,
5406 : : permanent ? RELPERSISTENCE_PERMANENT : RELPERSISTENCE_UNLOGGED,
5407 : : forkNum,
5408 : : block_range_read_stream_cb,
5409 : : &p,
5410 : : 0);
5411 : :
5412 : : /* Iterate over each block of the source relation file. */
1498 rhaas@postgresql.org 5413 [ + + ]: 336047 : for (blkno = 0; blkno < nblocks; blkno++)
5414 : : {
5415 [ - + ]: 266088 : CHECK_FOR_INTERRUPTS();
5416 : :
5417 : : /* Read block from source relation. */
654 noah@leadboat.com 5418 : 266088 : srcBuf = read_stream_next_buffer(src_stream, NULL);
1368 tgl@sss.pgh.pa.us 5419 : 266085 : LockBuffer(srcBuf, BUFFER_LOCK_SHARE);
1498 rhaas@postgresql.org 5420 : 266085 : srcPage = BufferGetPage(srcBuf);
5421 : :
654 noah@leadboat.com 5422 : 266085 : dstBuf = ReadBufferWithoutRelcache(dstlocator, forkNum,
5423 : : BufferGetBlockNumber(srcBuf),
5424 : : RBM_ZERO_AND_LOCK, bstrategy_dst,
5425 : : permanent);
1368 tgl@sss.pgh.pa.us 5426 : 266085 : dstPage = BufferGetPage(dstBuf);
5427 : :
1498 rhaas@postgresql.org 5428 : 266085 : START_CRIT_SECTION();
5429 : :
5430 : : /* Copy page data from the source to the destination. */
5431 : 266085 : memcpy(dstPage, srcPage, BLCKSZ);
5432 : 266085 : MarkBufferDirty(dstBuf);
5433 : :
5434 : : /* WAL-log the copied page. */
5435 [ + + ]: 266085 : if (use_wal)
5436 : 147845 : log_newpage_buffer(dstBuf, true);
5437 : :
5438 [ - + ]: 266085 : END_CRIT_SECTION();
5439 : :
5440 : 266085 : UnlockReleaseBuffer(dstBuf);
1368 tgl@sss.pgh.pa.us 5441 : 266085 : UnlockReleaseBuffer(srcBuf);
5442 : : }
654 noah@leadboat.com 5443 [ - + ]: 69959 : Assert(read_stream_next_buffer(src_stream, NULL) == InvalidBuffer);
5444 : 69959 : read_stream_end(src_stream);
5445 : :
1142 andres@anarazel.de 5446 : 69959 : FreeAccessStrategy(bstrategy_src);
5447 : 69959 : FreeAccessStrategy(bstrategy_dst);
5448 : : }
5449 : :
5450 : : /* ---------------------------------------------------------------------
5451 : : * CreateAndCopyRelationData
5452 : : *
5453 : : * Create destination relation storage and copy all forks from the
5454 : : * source relation to the destination.
5455 : : *
5456 : : * Pass permanent as true for permanent relations and false for
5457 : : * unlogged relations. Currently this API is not supported for
5458 : : * temporary relations.
5459 : : * --------------------------------------------------------------------
5460 : : */
5461 : : void
1399 rhaas@postgresql.org 5462 : 65910 : CreateAndCopyRelationData(RelFileLocator src_rlocator,
5463 : : RelFileLocator dst_rlocator, bool permanent)
5464 : : {
5465 : : char relpersistence;
5466 : : SMgrRelation src_rel;
5467 : : SMgrRelation dst_rel;
5468 : :
5469 : : /* Set the relpersistence. */
1498 5470 [ + - ]: 65910 : relpersistence = permanent ?
5471 : : RELPERSISTENCE_PERMANENT : RELPERSISTENCE_UNLOGGED;
5472 : :
793 heikki.linnakangas@i 5473 : 65910 : src_rel = smgropen(src_rlocator, INVALID_PROC_NUMBER);
5474 : 65910 : dst_rel = smgropen(dst_rlocator, INVALID_PROC_NUMBER);
5475 : :
5476 : : /*
5477 : : * Create and copy all forks of the relation. During create database we
5478 : : * have a separate cleanup mechanism which deletes complete database
5479 : : * directory. Therefore, each individual relation doesn't need to be
5480 : : * registered for cleanup.
5481 : : */
1399 rhaas@postgresql.org 5482 : 65910 : RelationCreateStorage(dst_rlocator, relpersistence, false);
5483 : :
5484 : : /* copy main fork. */
1362 5485 : 65910 : RelationCopyStorageUsingBuffer(src_rlocator, dst_rlocator, MAIN_FORKNUM,
5486 : : permanent);
5487 : :
5488 : : /* copy those extra forks that exist */
1498 5489 : 65907 : for (ForkNumber forkNum = MAIN_FORKNUM + 1;
5490 [ + + ]: 263628 : forkNum <= MAX_FORKNUM; forkNum++)
5491 : : {
825 heikki.linnakangas@i 5492 [ + + ]: 197721 : if (smgrexists(src_rel, forkNum))
5493 : : {
5494 : 19985 : smgrcreate(dst_rel, forkNum, false);
5495 : :
5496 : : /*
5497 : : * WAL log creation if the relation is persistent, or this is the
5498 : : * init fork of an unlogged relation.
5499 : : */
1498 rhaas@postgresql.org 5500 [ - + - - ]: 19985 : if (permanent || forkNum == INIT_FORKNUM)
1399 5501 : 19985 : log_smgrcreate(&dst_rlocator, forkNum);
5502 : :
5503 : : /* Copy a fork's data, block by block. */
1362 5504 : 19985 : RelationCopyStorageUsingBuffer(src_rlocator, dst_rlocator, forkNum,
5505 : : permanent);
5506 : : }
5507 : : }
1498 5508 : 65907 : }
5509 : :
5510 : : /* ---------------------------------------------------------------------
5511 : : * FlushDatabaseBuffers
5512 : : *
5513 : : * This function writes all dirty pages of a database out to disk
5514 : : * (or more accurately, out to kernel disk buffers), ensuring that the
5515 : : * kernel has an up-to-date view of the database.
5516 : : *
5517 : : * Generally, the caller should be holding an appropriate lock to ensure
5518 : : * no other backend is active in the target database; otherwise more
5519 : : * pages could get dirtied.
5520 : : *
5521 : : * Note we don't worry about flushing any pages of temporary relations.
5522 : : * It's assumed these wouldn't be interesting.
5523 : : * --------------------------------------------------------------------
5524 : : */
5525 : : void
6886 tgl@sss.pgh.pa.us 5526 : 5 : FlushDatabaseBuffers(Oid dbid)
5527 : : {
5528 : : int i;
5529 : : BufferDesc *bufHdr;
5530 : :
5531 [ + + ]: 645 : for (i = 0; i < NBuffers; i++)
5532 : : {
5533 : : uint64 buf_state;
5534 : :
4114 andres@anarazel.de 5535 : 640 : bufHdr = GetBufferDescriptor(i);
5536 : :
5537 : : /*
5538 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
5539 : : * saves some cycles.
5540 : : */
1350 rhaas@postgresql.org 5541 [ + + ]: 640 : if (bufHdr->tag.dbOid != dbid)
5080 tgl@sss.pgh.pa.us 5542 : 474 : continue;
5543 : :
5544 : : /* Make sure we can handle the pin */
4124 andres@anarazel.de 5545 : 166 : ReservePrivateRefCountEntry();
909 heikki.linnakangas@i 5546 : 166 : ResourceOwnerEnlarge(CurrentResourceOwner);
5547 : :
3677 andres@anarazel.de 5548 : 166 : buf_state = LockBufHdr(bufHdr);
1350 rhaas@postgresql.org 5549 [ + - ]: 166 : if (bufHdr->tag.dbOid == dbid &&
3677 andres@anarazel.de 5550 [ + + ]: 166 : (buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
5551 : : {
6886 tgl@sss.pgh.pa.us 5552 : 25 : PinBuffer_Locked(bufHdr);
209 andres@anarazel.de 5553 :GNC 25 : FlushUnlockedBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
1313 michael@paquier.xyz 5554 :CBC 25 : UnpinBuffer(bufHdr);
5555 : : }
5556 : : else
180 andres@anarazel.de 5557 :GNC 141 : UnlockBufHdr(bufHdr);
5558 : : }
6886 tgl@sss.pgh.pa.us 5559 :CBC 5 : }
5560 : :
5561 : : /*
5562 : : * Flush a previously, share-exclusively or exclusively, locked and pinned
5563 : : * buffer to the OS.
5564 : : */
5565 : : void
3799 andres@anarazel.de 5566 : 107 : FlushOneBuffer(Buffer buffer)
5567 : : {
5568 : : BufferDesc *bufHdr;
5569 : :
5570 : : /* currently not needed, but no fundamental reason not to support */
5571 [ - + ]: 107 : Assert(!BufferIsLocal(buffer));
5572 : :
5573 [ - + - + : 107 : Assert(BufferIsPinned(buffer));
- + ]
5574 : :
5575 : 107 : bufHdr = GetBufferDescriptor(buffer - 1);
5576 : :
209 andres@anarazel.de 5577 [ - + ]:GNC 107 : Assert(BufferIsLockedByMe(buffer));
5578 : :
1181 andres@anarazel.de 5579 :CBC 107 : FlushBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
3799 5580 : 107 : }
5581 : :
5582 : : /*
5583 : : * ReleaseBuffer -- release the pin on a buffer
5584 : : */
5585 : : void
8673 tgl@sss.pgh.pa.us 5586 : 48595076 : ReleaseBuffer(Buffer buffer)
5587 : : {
7872 5588 [ - + ]: 48595076 : if (!BufferIsValid(buffer))
5434 peter_e@gmx.net 5589 [ # # ]:UBC 0 : elog(ERROR, "bad buffer ID: %d", buffer);
5590 : :
10467 bruce@momjian.us 5591 [ + + ]:CBC 48595076 : if (BufferIsLocal(buffer))
1126 andres@anarazel.de 5592 : 754007 : UnpinLocalBuffer(buffer);
5593 : : else
5594 : 47841069 : UnpinBuffer(GetBufferDescriptor(buffer - 1));
10892 scrappy@hub.org 5595 : 48595076 : }
5596 : :
5597 : : /*
5598 : : * UnlockReleaseBuffer -- release the content lock and pin on a buffer
5599 : : *
5600 : : * This is just a, more efficient, shorthand for a common combination.
5601 : : */
5602 : : void
7340 tgl@sss.pgh.pa.us 5603 : 50896038 : UnlockReleaseBuffer(Buffer buffer)
5604 : : {
5605 : : int mode;
5606 : : BufferDesc *buf;
5607 : : PrivateRefCountEntry *ref;
5608 : : uint64 sub;
5609 : : uint64 lockstate;
5610 : :
39 andres@anarazel.de 5611 [ - + + + :GNC 50896038 : Assert(BufferIsPinned(buffer));
- + ]
5612 : :
5613 [ + + ]: 50896038 : if (BufferIsLocal(buffer))
5614 : : {
5615 : 1646201 : UnpinLocalBuffer(buffer);
5616 : 1646201 : return;
5617 : : }
5618 : :
5619 : 49249837 : ResourceOwnerForgetBuffer(CurrentResourceOwner, buffer);
5620 : :
5621 : 49249837 : buf = GetBufferDescriptor(buffer - 1);
5622 : :
5623 : 49249837 : mode = BufferLockDisownInternal(buffer, buf);
5624 : :
5625 : : /* compute state modification for lock release */
5626 : 49249837 : sub = BufferLockReleaseSub(mode);
5627 : :
5628 : : /* compute state modification for pin release */
5629 : 49249837 : ref = GetPrivateRefCountEntry(buffer, false);
5630 [ - + ]: 49249837 : Assert(ref != NULL);
5631 [ - + ]: 49249837 : Assert(ref->data.refcount > 0);
5632 : 49249837 : ref->data.refcount--;
5633 : :
5634 : : /* no more backend local pins, reduce shared pin count */
5635 [ + + ]: 49249837 : if (likely(ref->data.refcount == 0))
5636 : : {
5637 : : /* See comment in UnpinBufferNoOwner() */
5638 : : VALGRIND_MAKE_MEM_NOACCESS(BufHdrGetBlock(buf), BLCKSZ);
5639 : :
5640 : 46862518 : sub |= BUF_REFCOUNT_ONE;
5641 : 46862518 : ForgetPrivateRefCountEntry(ref);
5642 : : }
5643 : :
5644 : : /* perform the lock and pin release in one atomic op */
5645 : 49249837 : lockstate = pg_atomic_sub_fetch_u64(&buf->state, sub);
5646 : :
5647 : : /* wake up waiters for the lock */
5648 : 49249837 : BufferLockProcessRelease(buf, mode, lockstate);
5649 : :
5650 : : /* wake up waiter for the pin release */
5651 [ + + ]: 49249837 : if (lockstate & BM_PIN_COUNT_WAITER)
5652 : 5 : WakePinCountWaiter(buf);
5653 : :
5654 : : /*
5655 : : * Now okay to allow cancel/die interrupts again, which were held when the
5656 : : * lock was acquired.
5657 : : */
5658 [ - + ]: 49249837 : RESUME_INTERRUPTS();
7340 tgl@sss.pgh.pa.us 5659 :ECB (17962458) : }
5660 : :
5661 : : /*
5662 : : * IncrBufferRefCount
5663 : : * Increment the pin count on a buffer that we have *already* pinned
5664 : : * at least once.
5665 : : *
5666 : : * This function cannot be used on a buffer we do not have pinned,
5667 : : * because it doesn't change the shared buffer state.
5668 : : */
5669 : : void
7962 tgl@sss.pgh.pa.us 5670 :CBC 14556593 : IncrBufferRefCount(Buffer buffer)
5671 : : {
7832 neilc@samurai.com 5672 [ - + + + : 14556593 : Assert(BufferIsPinned(buffer));
- + ]
909 heikki.linnakangas@i 5673 : 14556593 : ResourceOwnerEnlarge(CurrentResourceOwner);
7962 tgl@sss.pgh.pa.us 5674 [ + + ]: 14556593 : if (BufferIsLocal(buffer))
5675 : 471199 : LocalRefCount[-buffer - 1]++;
5676 : : else
5677 : : {
5678 : : PrivateRefCountEntry *ref;
5679 : :
4124 andres@anarazel.de 5680 : 14085394 : ref = GetPrivateRefCountEntry(buffer, true);
4266 5681 [ - + ]: 14085394 : Assert(ref != NULL);
142 andres@anarazel.de 5682 :GNC 14085394 : ref->data.refcount++;
5683 : : }
3100 tgl@sss.pgh.pa.us 5684 :CBC 14556593 : ResourceOwnerRememberBuffer(CurrentResourceOwner, buffer);
7962 5685 : 14556593 : }
5686 : :
5687 : : /*
5688 : : * Shared-buffer only helper for MarkBufferDirtyHint() and
5689 : : * BufferSetHintBits16().
5690 : : *
5691 : : * This is separated out because it turns out that the repeated checks for
5692 : : * local buffers, repeated GetBufferDescriptor() and repeated reading of the
5693 : : * buffer's state sufficiently hurts the performance of BufferSetHintBits16().
5694 : : */
5695 : : static inline void
56 andres@anarazel.de 5696 :GNC 15320964 : MarkSharedBufferDirtyHint(Buffer buffer, BufferDesc *bufHdr, uint64 lockstate,
5697 : : bool buffer_std)
5698 : : {
3667 kgrittn@postgresql.o 5699 :CBC 15320964 : Page page = BufferGetPage(buffer);
5700 : :
4266 andres@anarazel.de 5701 [ - + ]: 15320964 : Assert(GetPrivateRefCount(buffer) > 0);
5702 : :
5703 : : /* here, either share-exclusive or exclusive lock is OK */
56 andres@anarazel.de 5704 [ + + - + ]:GNC 15320964 : Assert(BufferLockHeldByMeInMode(bufHdr, BUFFER_LOCK_EXCLUSIVE) ||
5705 : : BufferLockHeldByMeInMode(bufHdr, BUFFER_LOCK_SHARE_EXCLUSIVE));
5706 : :
5707 : : /*
5708 : : * This routine might get called many times on the same page, if we are
5709 : : * making the first scan after commit of an xact that added/deleted many
5710 : : * tuples. So, be as quick as we can if the buffer is already dirty.
5711 : : *
5712 : : * As we are holding (at least) a share-exclusive lock, nobody could have
5713 : : * cleaned or dirtied the page concurrently, so we can just rely on the
5714 : : * previously fetched value here without any danger of races.
5715 : : */
55 5716 [ + + ]: 15320964 : if (unlikely(!(lockstate & BM_DIRTY)))
5717 : : {
4792 simon@2ndQuadrant.co 5718 :CBC 428407 : XLogRecPtr lsn = InvalidXLogRecPtr;
55 andres@anarazel.de 5719 :GNC 428407 : bool wal_log = false;
5720 : : uint64 buf_state;
5721 : :
5722 : : /*
5723 : : * If we need to protect hint bit updates from torn writes, WAL-log a
5724 : : * full page image of the page. This full page image is only necessary
5725 : : * if the hint bit update is the first change to the page since the
5726 : : * last checkpoint.
5727 : : *
5728 : : * We don't check full_page_writes here because that logic is included
5729 : : * when we call XLogInsert() since the value changes dynamically.
5730 : : */
56 5731 [ + + + + : 428407 : if (XLogHintBitIsNeeded() && (lockstate & BM_PERMANENT))
+ + ]
5732 : : {
5733 : : /*
5734 : : * If we must not write WAL, due to a relfilelocator-specific
5735 : : * condition or being in recovery, don't dirty the page. We can
5736 : : * set the hint, just not dirty the page as a result so the hint
5737 : : * is lost when we evict the page or shutdown.
5738 : : *
5739 : : * See src/backend/storage/page/README for longer discussion.
5740 : : */
2222 noah@leadboat.com 5741 [ + + + + ]:CBC 514412 : if (RecoveryInProgress() ||
1350 rhaas@postgresql.org 5742 : 87989 : RelFileLocatorSkippingWAL(BufTagGetRelFileLocator(&bufHdr->tag)))
4792 simon@2ndQuadrant.co 5743 : 340270 : return;
5744 : :
55 andres@anarazel.de 5745 :GNC 86153 : wal_log = true;
5746 : : }
5747 : :
5748 : : /*
5749 : : * We must mark the page dirty before we emit the WAL record, as per
5750 : : * the usual rules, to ensure that BufferSync()/SyncOneBuffer() try to
5751 : : * flush the buffer, even if we haven't inserted the WAL record yet.
5752 : : * As we hold at least a share-exclusive lock, checkpoints will wait
5753 : : * for this backend to be done with the buffer before continuing. If
5754 : : * we did it the other way round, a checkpoint could start between
5755 : : * writing the WAL record and marking the buffer dirty.
5756 : : */
3677 andres@anarazel.de 5757 :CBC 88137 : buf_state = LockBufHdr(bufHdr);
5758 : :
5759 : : /*
5760 : : * It should not be possible for the buffer to already be dirty, see
5761 : : * comment above.
5762 : : */
56 andres@anarazel.de 5763 [ - + ]:GNC 88137 : Assert(!(buf_state & BM_DIRTY));
3677 andres@anarazel.de 5764 [ - + ]:CBC 88137 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
55 andres@anarazel.de 5765 :GNC 88137 : UnlockBufHdrExt(bufHdr, buf_state,
5766 : : BM_DIRTY,
5767 : : 0, 0);
5768 : :
5769 : : /*
5770 : : * If the block is already dirty because we either made a change or
5771 : : * set a hint already, then we don't need to write a full page image.
5772 : : * Note that aggressive cleaning of blocks dirtied by hint bit setting
5773 : : * would increase the call rate. Bulk setting of hint bits would
5774 : : * reduce the call rate...
5775 : : */
5776 [ + + ]: 88137 : if (wal_log)
5777 : 86153 : lsn = XLogSaveBufferForHint(buffer, buffer_std);
5778 : :
56 5779 [ + + ]: 88137 : if (XLogRecPtrIsValid(lsn))
5780 : : {
5781 : : /*
5782 : : * Set the page LSN if we wrote a backup block. To allow backends
5783 : : * that only hold a share lock on the buffer to read the LSN in a
5784 : : * tear-free manner, we set the page LSN while holding the buffer
5785 : : * header lock. This allows any reader of an LSN who holds only a
5786 : : * share lock to also obtain a buffer header lock before using
5787 : : * PageGetLSN() to read the LSN in a tear free way. This is done
5788 : : * in BufferGetLSNAtomic().
5789 : : *
5790 : : * If checksums are enabled, you might think we should reset the
5791 : : * checksum here. That will happen when the page is written
5792 : : * sometime later in this checkpoint cycle.
5793 : : */
55 5794 : 58084 : buf_state = LockBufHdr(bufHdr);
56 5795 : 58084 : PageSetLSN(page, lsn);
55 5796 : 58084 : UnlockBufHdr(bufHdr);
5797 : : }
5798 : :
56 5799 : 88137 : pgBufferUsage.shared_blks_dirtied++;
5800 [ + + ]: 88137 : if (VacuumCostActive)
5801 : 2479 : VacuumCostBalance += VacuumCostPageDirty;
5802 : : }
5803 : : }
5804 : :
5805 : : /*
5806 : : * MarkBufferDirtyHint
5807 : : *
5808 : : * Mark a buffer dirty for non-critical changes.
5809 : : *
5810 : : * This is essentially the same as MarkBufferDirty, except:
5811 : : *
5812 : : * 1. The caller does not write WAL; so if checksums are enabled, we may need
5813 : : * to write an XLOG_FPI_FOR_HINT WAL record to protect against torn pages.
5814 : : * 2. The caller might have only a share-exclusive-lock instead of an
5815 : : * exclusive-lock on the buffer's content lock.
5816 : : * 3. This function does not guarantee that the buffer is always marked dirty
5817 : : * (it e.g. can't always on a hot standby), so it cannot be used for
5818 : : * important changes.
5819 : : */
5820 : : inline void
5821 : 440796 : MarkBufferDirtyHint(Buffer buffer, bool buffer_std)
5822 : : {
5823 : : BufferDesc *bufHdr;
5824 : :
5825 : 440796 : bufHdr = GetBufferDescriptor(buffer - 1);
5826 : :
5827 [ - + ]: 440796 : if (!BufferIsValid(buffer))
56 andres@anarazel.de 5828 [ # # ]:UNC 0 : elog(ERROR, "bad buffer ID: %d", buffer);
5829 : :
56 andres@anarazel.de 5830 [ + + ]:GNC 440796 : if (BufferIsLocal(buffer))
5831 : : {
5832 : 23969 : MarkLocalBufferDirty(buffer);
5833 : 23969 : return;
5834 : : }
5835 : :
5836 : 416827 : MarkSharedBufferDirtyHint(buffer, bufHdr,
5837 : 416827 : pg_atomic_read_u64(&bufHdr->state),
5838 : : buffer_std);
5839 : : }
5840 : :
5841 : : /*
5842 : : * Release buffer content locks for shared buffers.
5843 : : *
5844 : : * Used to clean up after errors.
5845 : : *
5846 : : * Currently, we can expect that resource owner cleanup, via
5847 : : * ResOwnerReleaseBuffer(), took care of releasing buffer content locks per
5848 : : * se; the only thing we need to deal with here is clearing any PIN_COUNT
5849 : : * request that was in progress.
5850 : : */
5851 : : void
9244 tgl@sss.pgh.pa.us 5852 :CBC 63696 : UnlockBuffers(void)
5853 : : {
3823 rhaas@postgresql.org 5854 : 63696 : BufferDesc *buf = PinCountWaitBuf;
5855 : :
7871 tgl@sss.pgh.pa.us 5856 [ - + ]: 63696 : if (buf)
5857 : : {
5858 : : uint64 buf_state;
110 andres@anarazel.de 5859 :UNC 0 : uint64 unset_bits = 0;
5860 : :
3677 andres@anarazel.de 5861 :UBC 0 : buf_state = LockBufHdr(buf);
5862 : :
5863 : : /*
5864 : : * Don't complain if flag bit not set; it could have been reset but we
5865 : : * got a cancel/die interrupt before getting the signal.
5866 : : */
5867 [ # # ]: 0 : if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
803 heikki.linnakangas@i 5868 [ # # ]: 0 : buf->wait_backend_pgprocno == MyProcNumber)
180 andres@anarazel.de 5869 :UNC 0 : unset_bits = BM_PIN_COUNT_WAITER;
5870 : :
5871 : 0 : UnlockBufHdrExt(buf, buf_state,
5872 : : 0, unset_bits,
5873 : : 0);
5874 : :
7732 tgl@sss.pgh.pa.us 5875 :UBC 0 : PinCountWaitBuf = NULL;
5876 : : }
10003 vadim4o@yahoo.com 5877 :CBC 63696 : }
5878 : :
5879 : : /*
5880 : : * Acquire the buffer content lock in the specified mode
5881 : : *
5882 : : * If the lock is not available, sleep until it is.
5883 : : *
5884 : : * Side effect: cancel/die interrupts are held off until lock release.
5885 : : *
5886 : : * This uses almost the same locking approach as lwlock.c's
5887 : : * LWLockAcquire(). See documentation at the top of lwlock.c for a more
5888 : : * detailed discussion.
5889 : : *
5890 : : * The reason that this, and most of the other BufferLock* functions, get both
5891 : : * the Buffer and BufferDesc* as parameters, is that looking up one from the
5892 : : * other repeatedly shows up noticeably in profiles.
5893 : : *
5894 : : * Callers should provide a constant for mode, for more efficient code
5895 : : * generation.
5896 : : */
5897 : : static inline void
110 andres@anarazel.de 5898 :GNC 111095916 : BufferLockAcquire(Buffer buffer, BufferDesc *buf_hdr, BufferLockMode mode)
5899 : : {
5900 : : PrivateRefCountEntry *entry;
5901 : 111095916 : int extraWaits = 0;
5902 : :
5903 : : /*
5904 : : * Get reference to the refcount entry before we hold the lock, it seems
5905 : : * better to do before holding the lock.
5906 : : */
5907 : 111095916 : entry = GetPrivateRefCountEntry(buffer, true);
5908 : :
5909 : : /*
5910 : : * We better not already hold a lock on the buffer.
5911 : : */
5912 [ - + ]: 111095916 : Assert(entry->data.lockmode == BUFFER_LOCK_UNLOCK);
5913 : :
5914 : : /*
5915 : : * Lock out cancel/die interrupts until we exit the code section protected
5916 : : * by the content lock. This ensures that interrupts will not interfere
5917 : : * with manipulations of data structures in shared memory.
5918 : : */
5919 : 111095916 : HOLD_INTERRUPTS();
5920 : :
5921 : : for (;;)
5922 : 28803 : {
109 5923 : 111124719 : uint32 wait_event = 0; /* initialized to avoid compiler warning */
5924 : : bool mustwait;
5925 : :
5926 : : /*
5927 : : * Try to grab the lock the first time, we're not in the waitqueue
5928 : : * yet/anymore.
5929 : : */
110 5930 : 111124719 : mustwait = BufferLockAttempt(buf_hdr, mode);
5931 : :
5932 [ + + ]: 111124719 : if (likely(!mustwait))
5933 : : {
5934 : 111095147 : break;
5935 : : }
5936 : :
5937 : : /*
5938 : : * Ok, at this point we couldn't grab the lock on the first try. We
5939 : : * cannot simply queue ourselves to the end of the list and wait to be
5940 : : * woken up because by now the lock could long have been released.
5941 : : * Instead add us to the queue and try to grab the lock again. If we
5942 : : * succeed we need to revert the queuing and be happy, otherwise we
5943 : : * recheck the lock. If we still couldn't grab it, we know that the
5944 : : * other locker will see our queue entries when releasing since they
5945 : : * existed before we checked for the lock.
5946 : : */
5947 : :
5948 : : /* add to the queue */
5949 : 29572 : BufferLockQueueSelf(buf_hdr, mode);
5950 : :
5951 : : /* we're now guaranteed to be woken up if necessary */
5952 : 29572 : mustwait = BufferLockAttempt(buf_hdr, mode);
5953 : :
5954 : : /* ok, grabbed the lock the second time round, need to undo queueing */
5955 [ + + ]: 29572 : if (!mustwait)
5956 : : {
5957 : 769 : BufferLockDequeueSelf(buf_hdr);
5958 : 769 : break;
5959 : : }
5960 : :
5961 [ + + + - : 28803 : switch (mode)
- ]
5962 : : {
5963 : 16215 : case BUFFER_LOCK_EXCLUSIVE:
5964 : 16215 : wait_event = WAIT_EVENT_BUFFER_EXCLUSIVE;
5965 : 16215 : break;
5966 : 104 : case BUFFER_LOCK_SHARE_EXCLUSIVE:
5967 : 104 : wait_event = WAIT_EVENT_BUFFER_SHARE_EXCLUSIVE;
5968 : 104 : break;
5969 : 12484 : case BUFFER_LOCK_SHARE:
5970 : 12484 : wait_event = WAIT_EVENT_BUFFER_SHARED;
5971 : 12484 : break;
110 andres@anarazel.de 5972 :UNC 0 : case BUFFER_LOCK_UNLOCK:
5973 : 0 : pg_unreachable();
5974 : :
5975 : : }
110 andres@anarazel.de 5976 :GNC 28803 : pgstat_report_wait_start(wait_event);
5977 : :
5978 : : /*
5979 : : * Wait until awakened.
5980 : : *
5981 : : * It is possible that we get awakened for a reason other than being
5982 : : * signaled by BufferLockWakeup(). If so, loop back and wait again.
5983 : : * Once we've gotten the lock, re-increment the sema by the number of
5984 : : * additional signals received.
5985 : : */
5986 : : for (;;)
5987 : : {
5988 : 28803 : PGSemaphoreLock(MyProc->sem);
5989 [ + - ]: 28803 : if (MyProc->lwWaiting == LW_WS_NOT_WAITING)
5990 : 28803 : break;
110 andres@anarazel.de 5991 :UNC 0 : extraWaits++;
5992 : : }
5993 : :
110 andres@anarazel.de 5994 :GNC 28803 : pgstat_report_wait_end();
5995 : :
5996 : : /* Retrying, allow BufferLockReleaseSub to release waiters again. */
5997 : 28803 : pg_atomic_fetch_and_u64(&buf_hdr->state, ~BM_LOCK_WAKE_IN_PROGRESS);
5998 : : }
5999 : :
6000 : : /* Remember that we now hold this lock */
6001 : 111095916 : entry->data.lockmode = mode;
6002 : :
6003 : : /*
6004 : : * Fix the process wait semaphore's count for any absorbed wakeups.
6005 : : */
6006 [ - + ]: 111095916 : while (unlikely(extraWaits-- > 0))
110 andres@anarazel.de 6007 :UNC 0 : PGSemaphoreUnlock(MyProc->sem);
110 andres@anarazel.de 6008 :GNC 111095916 : }
6009 : :
6010 : : /*
6011 : : * Release a previously acquired buffer content lock.
6012 : : */
6013 : : static void
6014 : 63598113 : BufferLockUnlock(Buffer buffer, BufferDesc *buf_hdr)
6015 : : {
6016 : : BufferLockMode mode;
6017 : : uint64 oldstate;
6018 : : uint64 sub;
6019 : :
6020 : 63598113 : mode = BufferLockDisownInternal(buffer, buf_hdr);
6021 : :
6022 : : /*
6023 : : * Release my hold on lock, after that it can immediately be acquired by
6024 : : * others, even if we still have to wakeup other waiters.
6025 : : */
6026 : 63598113 : sub = BufferLockReleaseSub(mode);
6027 : :
6028 : 63598113 : oldstate = pg_atomic_sub_fetch_u64(&buf_hdr->state, sub);
6029 : :
6030 : 63598113 : BufferLockProcessRelease(buf_hdr, mode, oldstate);
6031 : :
6032 : : /*
6033 : : * Now okay to allow cancel/die interrupts.
6034 : : */
6035 [ - + ]: 63598113 : RESUME_INTERRUPTS();
6036 : 63598113 : }
6037 : :
6038 : :
6039 : : /*
6040 : : * Acquire the content lock for the buffer, but only if we don't have to wait.
6041 : : *
6042 : : * It is allowed to try to conditionally acquire a lock on a buffer that this
6043 : : * backend has already locked, but the lock acquisition will always fail, even
6044 : : * if the new lock acquisition does not conflict with an already held lock
6045 : : * (e.g. two share locks). This is because we currently do not have space to
6046 : : * track multiple lock ownerships of the same buffer within one backend. That
6047 : : * is ok for the current uses of BufferLockConditional().
6048 : : */
6049 : : static bool
6050 : 1752898 : BufferLockConditional(Buffer buffer, BufferDesc *buf_hdr, BufferLockMode mode)
6051 : : {
6052 : 1752898 : PrivateRefCountEntry *entry = GetPrivateRefCountEntry(buffer, true);
6053 : : bool mustwait;
6054 : :
6055 : : /*
6056 : : * As described above, if we're trying to lock a buffer this backend
6057 : : * already has locked, return false, independent of the existing and
6058 : : * desired lock level.
6059 : : */
96 6060 [ - + ]: 1752898 : if (entry->data.lockmode != BUFFER_LOCK_UNLOCK)
96 andres@anarazel.de 6061 :UNC 0 : return false;
6062 : :
6063 : : /*
6064 : : * Lock out cancel/die interrupts until we exit the code section protected
6065 : : * by the content lock. This ensures that interrupts will not interfere
6066 : : * with manipulations of data structures in shared memory.
6067 : : */
110 andres@anarazel.de 6068 :GNC 1752898 : HOLD_INTERRUPTS();
6069 : :
6070 : : /* Check for the lock */
6071 : 1752898 : mustwait = BufferLockAttempt(buf_hdr, mode);
6072 : :
6073 [ + + ]: 1752898 : if (mustwait)
6074 : : {
6075 : : /* Failed to get lock, so release interrupt holdoff */
6076 [ - + ]: 864 : RESUME_INTERRUPTS();
6077 : : }
6078 : : else
6079 : : {
6080 : 1752034 : entry->data.lockmode = mode;
6081 : : }
6082 : :
6083 : 1752898 : return !mustwait;
6084 : : }
6085 : :
6086 : : /*
6087 : : * Internal function that tries to atomically acquire the content lock in the
6088 : : * passed in mode.
6089 : : *
6090 : : * This function will not block waiting for a lock to become free - that's the
6091 : : * caller's job.
6092 : : *
6093 : : * Similar to LWLockAttemptLock().
6094 : : */
6095 : : static inline bool
6096 : 112907189 : BufferLockAttempt(BufferDesc *buf_hdr, BufferLockMode mode)
6097 : : {
6098 : : uint64 old_state;
6099 : :
6100 : : /*
6101 : : * Read once outside the loop, later iterations will get the newer value
6102 : : * via compare & exchange.
6103 : : */
6104 : 112907189 : old_state = pg_atomic_read_u64(&buf_hdr->state);
6105 : :
6106 : : /* loop until we've determined whether we could acquire the lock or not */
6107 : : while (true)
6108 : 4998 : {
6109 : : uint64 desired_state;
6110 : : bool lock_free;
6111 : :
6112 : 112912187 : desired_state = old_state;
6113 : :
6114 [ + + ]: 112912187 : if (mode == BUFFER_LOCK_EXCLUSIVE)
6115 : : {
6116 : 38014773 : lock_free = (old_state & BM_LOCK_MASK) == 0;
6117 [ + + ]: 38014773 : if (lock_free)
6118 : 37980912 : desired_state += BM_LOCK_VAL_EXCLUSIVE;
6119 : : }
6120 [ + + ]: 74897414 : else if (mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6121 : : {
6122 : 734358 : lock_free = (old_state & (BM_LOCK_VAL_EXCLUSIVE | BM_LOCK_VAL_SHARE_EXCLUSIVE)) == 0;
6123 [ + + ]: 734358 : if (lock_free)
6124 : 734148 : desired_state += BM_LOCK_VAL_SHARE_EXCLUSIVE;
6125 : : }
6126 : : else
6127 : : {
6128 : 74163056 : lock_free = (old_state & BM_LOCK_VAL_EXCLUSIVE) == 0;
6129 [ + + ]: 74163056 : if (lock_free)
6130 : 74137693 : desired_state += BM_LOCK_VAL_SHARED;
6131 : : }
6132 : :
6133 : : /*
6134 : : * Attempt to swap in the state we are expecting. If we didn't see
6135 : : * lock to be free, that's just the old value. If we saw it as free,
6136 : : * we'll attempt to mark it acquired. The reason that we always swap
6137 : : * in the value is that this doubles as a memory barrier. We could try
6138 : : * to be smarter and only swap in values if we saw the lock as free,
6139 : : * but benchmark haven't shown it as beneficial so far.
6140 : : *
6141 : : * Retry if the value changed since we last looked at it.
6142 : : */
6143 [ + + ]: 112912187 : if (likely(pg_atomic_compare_exchange_u64(&buf_hdr->state,
6144 : : &old_state, desired_state)))
6145 : : {
6146 [ + + ]: 112907189 : if (lock_free)
6147 : : {
6148 : : /* Great! Got the lock. */
6149 : 112847950 : return false;
6150 : : }
6151 : : else
6152 : 59239 : return true; /* somebody else has the lock */
6153 : : }
6154 : : }
6155 : :
6156 : : pg_unreachable();
6157 : : }
6158 : :
6159 : : /*
6160 : : * Add ourselves to the end of the content lock's wait queue.
6161 : : */
6162 : : static void
6163 : 29572 : BufferLockQueueSelf(BufferDesc *buf_hdr, BufferLockMode mode)
6164 : : {
6165 : : /*
6166 : : * If we don't have a PGPROC structure, there's no way to wait. This
6167 : : * should never occur, since MyProc should only be null during shared
6168 : : * memory initialization.
6169 : : */
6170 [ - + ]: 29572 : if (MyProc == NULL)
110 andres@anarazel.de 6171 [ # # ]:UNC 0 : elog(PANIC, "cannot wait without a PGPROC structure");
6172 : :
110 andres@anarazel.de 6173 [ - + ]:GNC 29572 : if (MyProc->lwWaiting != LW_WS_NOT_WAITING)
110 andres@anarazel.de 6174 [ # # ]:UNC 0 : elog(PANIC, "queueing for lock while waiting on another one");
6175 : :
110 andres@anarazel.de 6176 :GNC 29572 : LockBufHdr(buf_hdr);
6177 : :
6178 : : /* setting the flag is protected by the spinlock */
6179 : 29572 : pg_atomic_fetch_or_u64(&buf_hdr->state, BM_LOCK_HAS_WAITERS);
6180 : :
6181 : : /*
6182 : : * These are currently used both for lwlocks and buffer content locks,
6183 : : * which is acceptable, although not pretty, because a backend can't wait
6184 : : * for both types of locks at the same time.
6185 : : */
6186 : 29572 : MyProc->lwWaiting = LW_WS_WAITING;
6187 : 29572 : MyProc->lwWaitMode = mode;
6188 : :
6189 : 29572 : proclist_push_tail(&buf_hdr->lock_waiters, MyProcNumber, lwWaitLink);
6190 : :
6191 : : /* Can release the mutex now */
6192 : 29572 : UnlockBufHdr(buf_hdr);
6193 : 29572 : }
6194 : :
6195 : : /*
6196 : : * Remove ourselves from the waitlist.
6197 : : *
6198 : : * This is used if we queued ourselves because we thought we needed to sleep
6199 : : * but, after further checking, we discovered that we don't actually need to
6200 : : * do so.
6201 : : */
6202 : : static void
6203 : 769 : BufferLockDequeueSelf(BufferDesc *buf_hdr)
6204 : : {
6205 : : bool on_waitlist;
6206 : :
6207 : 769 : LockBufHdr(buf_hdr);
6208 : :
6209 : 769 : on_waitlist = MyProc->lwWaiting == LW_WS_WAITING;
6210 [ + + ]: 769 : if (on_waitlist)
6211 : 551 : proclist_delete(&buf_hdr->lock_waiters, MyProcNumber, lwWaitLink);
6212 : :
6213 [ + + ]: 769 : if (proclist_is_empty(&buf_hdr->lock_waiters) &&
6214 [ + + ]: 746 : (pg_atomic_read_u64(&buf_hdr->state) & BM_LOCK_HAS_WAITERS) != 0)
6215 : : {
6216 : 528 : pg_atomic_fetch_and_u64(&buf_hdr->state, ~BM_LOCK_HAS_WAITERS);
6217 : : }
6218 : :
6219 : : /* XXX: combine with fetch_and above? */
6220 : 769 : UnlockBufHdr(buf_hdr);
6221 : :
6222 : : /* clear waiting state again, nice for debugging */
6223 [ + + ]: 769 : if (on_waitlist)
6224 : 551 : MyProc->lwWaiting = LW_WS_NOT_WAITING;
6225 : : else
6226 : : {
6227 : 218 : int extraWaits = 0;
6228 : :
6229 : :
6230 : : /*
6231 : : * Somebody else dequeued us and has or will wake us up. Deal with the
6232 : : * superfluous absorption of a wakeup.
6233 : : */
6234 : :
6235 : : /*
6236 : : * Clear BM_LOCK_WAKE_IN_PROGRESS if somebody woke us before we
6237 : : * removed ourselves - they'll have set it.
6238 : : */
6239 : 218 : pg_atomic_fetch_and_u64(&buf_hdr->state, ~BM_LOCK_WAKE_IN_PROGRESS);
6240 : :
6241 : : /*
6242 : : * Now wait for the scheduled wakeup, otherwise our ->lwWaiting would
6243 : : * get reset at some inconvenient point later. Most of the time this
6244 : : * will immediately return.
6245 : : */
6246 : : for (;;)
6247 : : {
6248 : 218 : PGSemaphoreLock(MyProc->sem);
6249 [ + - ]: 218 : if (MyProc->lwWaiting == LW_WS_NOT_WAITING)
6250 : 218 : break;
110 andres@anarazel.de 6251 :UNC 0 : extraWaits++;
6252 : : }
6253 : :
6254 : : /*
6255 : : * Fix the process wait semaphore's count for any absorbed wakeups.
6256 : : */
110 andres@anarazel.de 6257 [ - + ]:GNC 218 : while (extraWaits-- > 0)
110 andres@anarazel.de 6258 :UNC 0 : PGSemaphoreUnlock(MyProc->sem);
6259 : : }
110 andres@anarazel.de 6260 :GNC 769 : }
6261 : :
6262 : : /*
6263 : : * Stop treating lock as held by current backend.
6264 : : *
6265 : : * After calling this function it's the callers responsibility to ensure that
6266 : : * the lock gets released, even in case of an error. This only is desirable if
6267 : : * the lock is going to be released in a different process than the process
6268 : : * that acquired it.
6269 : : */
6270 : : static inline void
110 andres@anarazel.de 6271 :UNC 0 : BufferLockDisown(Buffer buffer, BufferDesc *buf_hdr)
6272 : : {
6273 : 0 : BufferLockDisownInternal(buffer, buf_hdr);
6274 [ # # ]: 0 : RESUME_INTERRUPTS();
6275 : 0 : }
6276 : :
6277 : : /*
6278 : : * Stop treating lock as held by current backend.
6279 : : *
6280 : : * This is the code that can be shared between actually releasing a lock
6281 : : * (BufferLockUnlock()) and just not tracking ownership of the lock anymore
6282 : : * without releasing the lock (BufferLockDisown()).
6283 : : */
6284 : : static inline int
110 andres@anarazel.de 6285 :GNC 112847950 : BufferLockDisownInternal(Buffer buffer, BufferDesc *buf_hdr)
6286 : : {
6287 : : BufferLockMode mode;
6288 : : PrivateRefCountEntry *ref;
6289 : :
6290 : 112847950 : ref = GetPrivateRefCountEntry(buffer, false);
6291 [ - + ]: 112847950 : if (ref == NULL)
110 andres@anarazel.de 6292 [ # # ]:UNC 0 : elog(ERROR, "lock %d is not held", buffer);
110 andres@anarazel.de 6293 :GNC 112847950 : mode = ref->data.lockmode;
6294 : 112847950 : ref->data.lockmode = BUFFER_LOCK_UNLOCK;
6295 : :
6296 : 112847950 : return mode;
6297 : : }
6298 : :
6299 : : /*
6300 : : * Wakeup all the lockers that currently have a chance to acquire the lock.
6301 : : *
6302 : : * wake_exclusive indicates whether exclusive lock waiters should be woken up.
6303 : : */
6304 : : static void
6305 : 27093 : BufferLockWakeup(BufferDesc *buf_hdr, bool wake_exclusive)
6306 : : {
6307 : 27093 : bool new_wake_in_progress = false;
6308 : 27093 : bool wake_share_exclusive = true;
6309 : : proclist_head wakeup;
6310 : : proclist_mutable_iter iter;
6311 : :
6312 : 27093 : proclist_init(&wakeup);
6313 : :
6314 : : /* lock wait list while collecting backends to wake up */
6315 : 27093 : LockBufHdr(buf_hdr);
6316 : :
6317 [ + + + + : 41269 : proclist_foreach_modify(iter, &buf_hdr->lock_waiters, lwWaitLink)
+ + ]
6318 : : {
6319 : 30506 : PGPROC *waiter = GetPGProcByNumber(iter.cur);
6320 : :
6321 : : /*
6322 : : * Already woke up a conflicting lock, so skip over this wait list
6323 : : * entry.
6324 : : */
6325 [ + + + + ]: 30506 : if (!wake_exclusive && waiter->lwWaitMode == BUFFER_LOCK_EXCLUSIVE)
6326 : 1476 : continue;
6327 [ + + - + ]: 29030 : if (!wake_share_exclusive && waiter->lwWaitMode == BUFFER_LOCK_SHARE_EXCLUSIVE)
110 andres@anarazel.de 6328 :UNC 0 : continue;
6329 : :
110 andres@anarazel.de 6330 :GNC 29030 : proclist_delete(&buf_hdr->lock_waiters, iter.cur, lwWaitLink);
6331 : 29030 : proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
6332 : :
6333 : : /*
6334 : : * Prevent additional wakeups until retryer gets to run. Backends that
6335 : : * are just waiting for the lock to become free don't retry
6336 : : * automatically.
6337 : : */
6338 : 29030 : new_wake_in_progress = true;
6339 : :
6340 : : /*
6341 : : * Signal that the process isn't on the wait list anymore. This allows
6342 : : * BufferLockDequeueSelf() to remove itself from the waitlist with a
6343 : : * proclist_delete(), rather than having to check if it has been
6344 : : * removed from the list.
6345 : : */
6346 [ - + ]: 29030 : Assert(waiter->lwWaiting == LW_WS_WAITING);
6347 : 29030 : waiter->lwWaiting = LW_WS_PENDING_WAKEUP;
6348 : :
6349 : : /*
6350 : : * Don't wakeup further waiters after waking a conflicting waiter.
6351 : : */
6352 [ + + ]: 29030 : if (waiter->lwWaitMode == BUFFER_LOCK_SHARE)
6353 : : {
6354 : : /*
6355 : : * Share locks conflict with exclusive locks.
6356 : : */
6357 : 12588 : wake_exclusive = false;
6358 : : }
6359 [ + + ]: 16442 : else if (waiter->lwWaitMode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6360 : : {
6361 : : /*
6362 : : * Share-exclusive locks conflict with share-exclusive and
6363 : : * exclusive locks.
6364 : : */
6365 : 112 : wake_exclusive = false;
6366 : 112 : wake_share_exclusive = false;
6367 : : }
6368 [ + - ]: 16330 : else if (waiter->lwWaitMode == BUFFER_LOCK_EXCLUSIVE)
6369 : : {
6370 : : /*
6371 : : * Exclusive locks conflict with all other locks, there's no point
6372 : : * in waking up anybody else.
6373 : : */
6374 : 16330 : break;
6375 : : }
6376 : : }
6377 : :
6378 [ + + - + ]: 27093 : Assert(proclist_is_empty(&wakeup) || pg_atomic_read_u64(&buf_hdr->state) & BM_LOCK_HAS_WAITERS);
6379 : :
6380 : : /* unset required flags, and release lock, in one fell swoop */
6381 : : {
6382 : : uint64 old_state;
6383 : : uint64 desired_state;
6384 : :
6385 : 27093 : old_state = pg_atomic_read_u64(&buf_hdr->state);
6386 : : while (true)
6387 : : {
6388 : 27098 : desired_state = old_state;
6389 : :
6390 : : /* compute desired flags */
6391 : :
6392 [ + + ]: 27098 : if (new_wake_in_progress)
6393 : 26972 : desired_state |= BM_LOCK_WAKE_IN_PROGRESS;
6394 : : else
6395 : 126 : desired_state &= ~BM_LOCK_WAKE_IN_PROGRESS;
6396 : :
6397 [ + + ]: 27098 : if (proclist_is_empty(&buf_hdr->lock_waiters))
6398 : 22074 : desired_state &= ~BM_LOCK_HAS_WAITERS;
6399 : :
6400 : 27098 : desired_state &= ~BM_LOCKED; /* release lock */
6401 : :
6402 [ + + ]: 27098 : if (pg_atomic_compare_exchange_u64(&buf_hdr->state, &old_state,
6403 : : desired_state))
6404 : 27093 : break;
6405 : : }
6406 : : }
6407 : :
6408 : : /* Awaken any waiters I removed from the queue. */
6409 [ + + + + : 56123 : proclist_foreach_modify(iter, &wakeup, lwWaitLink)
+ + ]
6410 : : {
6411 : 29030 : PGPROC *waiter = GetPGProcByNumber(iter.cur);
6412 : :
6413 : 29030 : proclist_delete(&wakeup, iter.cur, lwWaitLink);
6414 : :
6415 : : /*
6416 : : * Guarantee that lwWaiting being unset only becomes visible once the
6417 : : * unlink from the link has completed. Otherwise the target backend
6418 : : * could be woken up for other reason and enqueue for a new lock - if
6419 : : * that happens before the list unlink happens, the list would end up
6420 : : * being corrupted.
6421 : : *
6422 : : * The barrier pairs with the LockBufHdr() when enqueuing for another
6423 : : * lock.
6424 : : */
6425 : 29030 : pg_write_barrier();
6426 : 29030 : waiter->lwWaiting = LW_WS_NOT_WAITING;
6427 : 29030 : PGSemaphoreUnlock(waiter->sem);
6428 : : }
6429 : 27093 : }
6430 : :
6431 : : /*
6432 : : * Compute subtraction from buffer state for a release of a held lock in
6433 : : * `mode`.
6434 : : *
6435 : : * This is separated from BufferLockUnlock() as we want to combine the lock
6436 : : * release with other atomic operations when possible, leading to the lock
6437 : : * release being done in multiple places, each needing to compute what to
6438 : : * subtract from the lock state.
6439 : : */
6440 : : static inline uint64
6441 : 112847950 : BufferLockReleaseSub(BufferLockMode mode)
6442 : : {
6443 : : /*
6444 : : * Turns out that a switch() leads gcc to generate sufficiently worse code
6445 : : * for this to show up in profiles...
6446 : : */
6447 [ + + ]: 112847950 : if (mode == BUFFER_LOCK_EXCLUSIVE)
6448 : 37980747 : return BM_LOCK_VAL_EXCLUSIVE;
6449 [ + + ]: 74867203 : else if (mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6450 : 4167237 : return BM_LOCK_VAL_SHARE_EXCLUSIVE;
6451 : : else
6452 : : {
6453 [ - + ]: 70699966 : Assert(mode == BUFFER_LOCK_SHARE);
6454 : 70699966 : return BM_LOCK_VAL_SHARED;
6455 : : }
6456 : :
6457 : : return 0; /* keep compiler quiet */
6458 : : }
6459 : :
6460 : : /*
6461 : : * Handle work that needs to be done after releasing a lock that was held in
6462 : : * `mode`, where `lockstate` is the result of the atomic operation modifying
6463 : : * the state variable.
6464 : : *
6465 : : * This is separated from BufferLockUnlock() as we want to combine the lock
6466 : : * release with other atomic operations when possible, leading to the lock
6467 : : * release being done in multiple places.
6468 : : */
6469 : : static void
6470 : 112847950 : BufferLockProcessRelease(BufferDesc *buf_hdr, BufferLockMode mode, uint64 lockstate)
6471 : : {
6472 : 112847950 : bool check_waiters = false;
6473 : 112847950 : bool wake_exclusive = false;
6474 : :
6475 : : /* nobody else can have that kind of lock */
6476 [ - + ]: 112847950 : Assert(!(lockstate & BM_LOCK_VAL_EXCLUSIVE));
6477 : :
6478 : : /*
6479 : : * If we're still waiting for backends to get scheduled, don't wake them
6480 : : * up again. Otherwise check if we need to look through the waitqueue to
6481 : : * wake other backends.
6482 : : */
6483 [ + + ]: 112847950 : if ((lockstate & BM_LOCK_HAS_WAITERS) &&
6484 [ + + ]: 96856 : !(lockstate & BM_LOCK_WAKE_IN_PROGRESS))
6485 : : {
6486 [ + + ]: 51454 : if ((lockstate & BM_LOCK_MASK) == 0)
6487 : : {
6488 : : /*
6489 : : * We released a lock and the lock was, in that moment, free. We
6490 : : * therefore can wake waiters for any kind of lock.
6491 : : */
6492 : 27088 : check_waiters = true;
6493 : 27088 : wake_exclusive = true;
6494 : : }
6495 [ + + ]: 24366 : else if (mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6496 : : {
6497 : : /*
6498 : : * We released the lock, but another backend still holds a lock.
6499 : : * We can't have released an exclusive lock, as there couldn't
6500 : : * have been other lock holders. If we released a share lock, no
6501 : : * waiters need to be woken up, as there must be other share
6502 : : * lockers. However, if we held a share-exclusive lock, another
6503 : : * backend now could acquire a share-exclusive lock.
6504 : : */
6505 : 5 : check_waiters = true;
6506 : 5 : wake_exclusive = false;
6507 : : }
6508 : : }
6509 : :
6510 : : /*
6511 : : * As waking up waiters requires the spinlock to be acquired, only do so
6512 : : * if necessary.
6513 : : */
6514 [ + + ]: 112847950 : if (check_waiters)
6515 : 27093 : BufferLockWakeup(buf_hdr, wake_exclusive);
6516 : 112847950 : }
6517 : :
6518 : : /*
6519 : : * BufferLockHeldByMeInMode - test whether my process holds the content lock
6520 : : * in the specified mode
6521 : : *
6522 : : * This is meant as debug support only.
6523 : : */
6524 : : static bool
6525 : 139226354 : BufferLockHeldByMeInMode(BufferDesc *buf_hdr, BufferLockMode mode)
6526 : : {
6527 : : PrivateRefCountEntry *entry =
6528 : 139226354 : GetPrivateRefCountEntry(BufferDescriptorGetBuffer(buf_hdr), false);
6529 : :
6530 [ - + ]: 139226354 : if (!entry)
110 andres@anarazel.de 6531 :UNC 0 : return false;
6532 : : else
110 andres@anarazel.de 6533 :GNC 139226354 : return entry->data.lockmode == mode;
6534 : : }
6535 : :
6536 : : /*
6537 : : * BufferLockHeldByMe - test whether my process holds the content lock in any
6538 : : * mode
6539 : : *
6540 : : * This is meant as debug support only.
6541 : : */
6542 : : static bool
6543 : 29258501 : BufferLockHeldByMe(BufferDesc *buf_hdr)
6544 : : {
6545 : : PrivateRefCountEntry *entry =
6546 : 29258501 : GetPrivateRefCountEntry(BufferDescriptorGetBuffer(buf_hdr), false);
6547 : :
6548 [ - + ]: 29258501 : if (!entry)
110 andres@anarazel.de 6549 :UNC 0 : return false;
6550 : : else
110 andres@anarazel.de 6551 :GNC 29258501 : return entry->data.lockmode != BUFFER_LOCK_UNLOCK;
6552 : : }
6553 : :
6554 : : /*
6555 : : * Release the content lock for the buffer.
6556 : : */
6557 : : void
6558 : 68436947 : UnlockBuffer(Buffer buffer)
6559 : : {
6560 : : BufferDesc *buf_hdr;
6561 : :
2115 pg@bowt.ie 6562 [ - + + + :CBC 68436947 : Assert(BufferIsPinned(buffer));
- + ]
10003 vadim4o@yahoo.com 6563 [ + + ]: 68436947 : if (BufferIsLocal(buffer))
7340 tgl@sss.pgh.pa.us 6564 : 5201989 : return; /* local buffers need no lock */
6565 : :
110 andres@anarazel.de 6566 :GNC 63234958 : buf_hdr = GetBufferDescriptor(buffer - 1);
6567 : 63234958 : BufferLockUnlock(buffer, buf_hdr);
6568 : : }
6569 : :
6570 : : /*
6571 : : * Acquire the content_lock for the buffer.
6572 : : */
6573 : : void
6574 : 117467835 : LockBufferInternal(Buffer buffer, BufferLockMode mode)
6575 : : {
6576 : : BufferDesc *buf_hdr;
6577 : :
6578 : : /*
6579 : : * We can't wait if we haven't got a PGPROC. This should only occur
6580 : : * during bootstrap or shared memory initialization. Put an Assert here
6581 : : * to catch unsafe coding practices.
6582 : : */
6583 [ - + - - ]: 117467835 : Assert(!(MyProc == NULL && IsUnderPostmaster));
6584 : :
6585 : : /* handled in LockBuffer() wrapper */
6586 [ - + ]: 117467835 : Assert(mode != BUFFER_LOCK_UNLOCK);
6587 : :
6588 [ - + + + : 117467835 : Assert(BufferIsPinned(buffer));
- + ]
6589 [ + + ]: 117467835 : if (BufferIsLocal(buffer))
6590 : 6734958 : return; /* local buffers need no lock */
6591 : :
6592 : 110732877 : buf_hdr = GetBufferDescriptor(buffer - 1);
6593 : :
6594 : : /*
6595 : : * Test the most frequent lock modes first. While a switch (mode) would be
6596 : : * nice, at least gcc generates considerably worse code for it.
6597 : : *
6598 : : * Call BufferLockAcquire() with a constant argument for mode, to generate
6599 : : * more efficient code for the different lock modes.
6600 : : */
6601 [ + + ]: 110732877 : if (mode == BUFFER_LOCK_SHARE)
6602 : 74133055 : BufferLockAcquire(buffer, buf_hdr, BUFFER_LOCK_SHARE);
10003 vadim4o@yahoo.com 6603 [ + - ]:CBC 36599822 : else if (mode == BUFFER_LOCK_EXCLUSIVE)
110 andres@anarazel.de 6604 :GNC 36599822 : BufferLockAcquire(buffer, buf_hdr, BUFFER_LOCK_EXCLUSIVE);
110 andres@anarazel.de 6605 [ # # ]:UNC 0 : else if (mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6606 : 0 : BufferLockAcquire(buffer, buf_hdr, BUFFER_LOCK_SHARE_EXCLUSIVE);
6607 : : else
8321 tgl@sss.pgh.pa.us 6608 [ # # ]:UBC 0 : elog(ERROR, "unrecognized buffer lock mode: %d", mode);
6609 : : }
6610 : :
6611 : : /*
6612 : : * Acquire the content_lock for the buffer, but only if we don't have to wait.
6613 : : *
6614 : : * This assumes the caller wants BUFFER_LOCK_EXCLUSIVE mode.
6615 : : */
6616 : : bool
8304 tgl@sss.pgh.pa.us 6617 :CBC 1467970 : ConditionalLockBuffer(Buffer buffer)
6618 : : {
6619 : : BufferDesc *buf;
6620 : :
2115 pg@bowt.ie 6621 [ - + + + : 1467970 : Assert(BufferIsPinned(buffer));
- + ]
8304 tgl@sss.pgh.pa.us 6622 [ + + ]: 1467970 : if (BufferIsLocal(buffer))
6623 : 86197 : return true; /* act as though we got it */
6624 : :
4114 andres@anarazel.de 6625 : 1381773 : buf = GetBufferDescriptor(buffer - 1);
6626 : :
110 andres@anarazel.de 6627 :GNC 1381773 : return BufferLockConditional(buffer, buf, BUFFER_LOCK_EXCLUSIVE);
6628 : : }
6629 : :
6630 : : /*
6631 : : * Verify that this backend is pinning the buffer exactly once.
6632 : : *
6633 : : * NOTE: Like in BufferIsPinned(), what we check here is that *this* backend
6634 : : * holds a pin on the buffer. We do not care whether some other backend does.
6635 : : */
6636 : : void
1126 andres@anarazel.de 6637 :CBC 4632669 : CheckBufferIsPinnedOnce(Buffer buffer)
6638 : : {
6639 [ + + ]: 4632669 : if (BufferIsLocal(buffer))
6640 : : {
6641 [ - + ]: 1049 : if (LocalRefCount[-buffer - 1] != 1)
1126 andres@anarazel.de 6642 [ # # ]:UBC 0 : elog(ERROR, "incorrect local pin count: %d",
6643 : : LocalRefCount[-buffer - 1]);
6644 : : }
6645 : : else
6646 : : {
1126 andres@anarazel.de 6647 [ - + ]:CBC 4631620 : if (GetPrivateRefCount(buffer) != 1)
1126 andres@anarazel.de 6648 [ # # ]:UBC 0 : elog(ERROR, "incorrect local pin count: %d",
6649 : : GetPrivateRefCount(buffer));
6650 : : }
1126 andres@anarazel.de 6651 :CBC 4632669 : }
6652 : :
6653 : : /*
6654 : : * LockBufferForCleanup - lock a buffer in preparation for deleting items
6655 : : *
6656 : : * Items may be deleted from a disk page only when the caller (a) holds an
6657 : : * exclusive lock on the buffer and (b) has observed that no other backend
6658 : : * holds a pin on the buffer. If there is a pin, then the other backend
6659 : : * might have a pointer into the buffer (for example, a heapscan reference
6660 : : * to an item --- see README for more details). It's OK if a pin is added
6661 : : * after the cleanup starts, however; the newly-arrived backend will be
6662 : : * unable to look at the page until we release the exclusive lock.
6663 : : *
6664 : : * To implement this protocol, a would-be deleter must pin the buffer and
6665 : : * then call LockBufferForCleanup(). LockBufferForCleanup() is similar to
6666 : : * LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE), except that it loops until
6667 : : * it has successfully observed pin count = 1.
6668 : : */
6669 : : void
9069 tgl@sss.pgh.pa.us 6670 : 33597 : LockBufferForCleanup(Buffer buffer)
6671 : : {
6672 : : BufferDesc *bufHdr;
1943 fujii@postgresql.org 6673 : 33597 : TimestampTz waitStart = 0;
1170 drowley@postgresql.o 6674 : 33597 : bool waiting = false;
1943 fujii@postgresql.org 6675 : 33597 : bool logged_recovery_conflict = false;
6676 : :
2115 pg@bowt.ie 6677 [ - + + + : 33597 : Assert(BufferIsPinned(buffer));
- + ]
7871 tgl@sss.pgh.pa.us 6678 [ - + ]: 33597 : Assert(PinCountWaitBuf == NULL);
6679 : :
1126 andres@anarazel.de 6680 : 33597 : CheckBufferIsPinnedOnce(buffer);
6681 : :
6682 : : /*
6683 : : * We do not yet need to be worried about in-progress AIOs holding a pin,
6684 : : * as we, so far, only support doing reads via AIO and this function can
6685 : : * only be called once the buffer is valid (i.e. no read can be in
6686 : : * flight).
6687 : : */
6688 : :
6689 : : /* Nobody else to wait for */
9069 tgl@sss.pgh.pa.us 6690 [ + + ]: 33597 : if (BufferIsLocal(buffer))
6691 : 18 : return;
6692 : :
4114 andres@anarazel.de 6693 : 33579 : bufHdr = GetBufferDescriptor(buffer - 1);
6694 : :
6695 : : for (;;)
9069 tgl@sss.pgh.pa.us 6696 : 68 : {
6697 : : uint64 buf_state;
110 andres@anarazel.de 6698 :GNC 33647 : uint64 unset_bits = 0;
6699 : :
6700 : : /* Try to acquire lock */
9069 tgl@sss.pgh.pa.us 6701 :CBC 33647 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
3677 andres@anarazel.de 6702 : 33647 : buf_state = LockBufHdr(bufHdr);
6703 : :
6704 [ - + ]: 33647 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
6705 [ + + ]: 33647 : if (BUF_STATE_GET_REFCOUNT(buf_state) == 1)
6706 : : {
6707 : : /* Successfully acquired exclusive lock with pincount 1 */
180 andres@anarazel.de 6708 :GNC 33579 : UnlockBufHdr(bufHdr);
6709 : :
6710 : : /*
6711 : : * Emit the log message if recovery conflict on buffer pin was
6712 : : * resolved but the startup process waited longer than
6713 : : * deadlock_timeout for it.
6714 : : */
1938 fujii@postgresql.org 6715 [ + + ]:CBC 33579 : if (logged_recovery_conflict)
84 heikki.linnakangas@i 6716 :GNC 2 : LogRecoveryConflict(RECOVERY_CONFLICT_BUFFERPIN,
6717 : : waitStart, GetCurrentTimestamp(),
6718 : : NULL, false);
6719 : :
1170 drowley@postgresql.o 6720 [ + + ]:CBC 33579 : if (waiting)
6721 : : {
6722 : : /* reset ps display to remove the suffix if we added one */
6723 : 2 : set_ps_display_remove_suffix();
6724 : 2 : waiting = false;
6725 : : }
9069 tgl@sss.pgh.pa.us 6726 : 33579 : return;
6727 : : }
6728 : : /* Failed, so mark myself as waiting for pincount 1 */
3677 andres@anarazel.de 6729 [ - + ]: 68 : if (buf_state & BM_PIN_COUNT_WAITER)
6730 : : {
180 andres@anarazel.de 6731 :UNC 0 : UnlockBufHdr(bufHdr);
9069 tgl@sss.pgh.pa.us 6732 :UBC 0 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
8321 6733 [ # # ]: 0 : elog(ERROR, "multiple backends attempting to wait for pincount 1");
6734 : : }
803 heikki.linnakangas@i 6735 :CBC 68 : bufHdr->wait_backend_pgprocno = MyProcNumber;
7871 tgl@sss.pgh.pa.us 6736 : 68 : PinCountWaitBuf = bufHdr;
180 andres@anarazel.de 6737 :GNC 68 : UnlockBufHdrExt(bufHdr, buf_state,
6738 : : BM_PIN_COUNT_WAITER, 0,
6739 : : 0);
9069 tgl@sss.pgh.pa.us 6740 :CBC 68 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
6741 : :
6742 : : /* Wait to be signaled by UnpinBuffer() */
5946 simon@2ndQuadrant.co 6743 [ + + ]: 68 : if (InHotStandby)
6744 : : {
1170 drowley@postgresql.o 6745 [ + + ]: 11 : if (!waiting)
6746 : : {
6747 : : /* adjust the process title to indicate that it's waiting */
6748 : 2 : set_ps_display_suffix("waiting");
6749 : 2 : waiting = true;
6750 : : }
6751 : :
6752 : : /*
6753 : : * Emit the log message if the startup process is waiting longer
6754 : : * than deadlock_timeout for recovery conflict on buffer pin.
6755 : : *
6756 : : * Skip this if first time through because the startup process has
6757 : : * not started waiting yet in this case. So, the wait start
6758 : : * timestamp is set after this logic.
6759 : : */
1943 fujii@postgresql.org 6760 [ + + + + ]: 11 : if (waitStart != 0 && !logged_recovery_conflict)
6761 : : {
6762 : 4 : TimestampTz now = GetCurrentTimestamp();
6763 : :
6764 [ + + ]: 4 : if (TimestampDifferenceExceeds(waitStart, now,
6765 : : DeadlockTimeout))
6766 : : {
84 heikki.linnakangas@i 6767 :GNC 2 : LogRecoveryConflict(RECOVERY_CONFLICT_BUFFERPIN,
6768 : : waitStart, now, NULL, true);
1943 fujii@postgresql.org 6769 :CBC 2 : logged_recovery_conflict = true;
6770 : : }
6771 : : }
6772 : :
6773 : : /*
6774 : : * Set the wait start timestamp if logging is enabled and first
6775 : : * time through.
6776 : : */
6777 [ + - + + ]: 11 : if (log_recovery_conflict_waits && waitStart == 0)
6778 : 2 : waitStart = GetCurrentTimestamp();
6779 : :
6780 : : /* Publish the bufid that Startup process waits on */
5946 simon@2ndQuadrant.co 6781 : 11 : SetStartupBufferPinWaitBufId(buffer - 1);
6782 : : /* Set alarm and then wait to be signaled by UnpinBuffer() */
6783 : 11 : ResolveRecoveryConflictWithBufferPin();
6784 : : /* Reset the published bufid */
6785 : 11 : SetStartupBufferPinWaitBufId(-1);
6786 : : }
6787 : : else
153 andres@anarazel.de 6788 :GNC 57 : ProcWaitForSignal(WAIT_EVENT_BUFFER_CLEANUP);
6789 : :
6790 : : /*
6791 : : * Remove flag marking us as waiter. Normally this will not be set
6792 : : * anymore, but ProcWaitForSignal() can return for other signals as
6793 : : * well. We take care to only reset the flag if we're the waiter, as
6794 : : * theoretically another backend could have started waiting. That's
6795 : : * impossible with the current usages due to table level locking, but
6796 : : * better be safe.
6797 : : */
3677 andres@anarazel.de 6798 :CBC 68 : buf_state = LockBufHdr(bufHdr);
6799 [ + + ]: 68 : if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
803 heikki.linnakangas@i 6800 [ + - ]: 9 : bufHdr->wait_backend_pgprocno == MyProcNumber)
180 andres@anarazel.de 6801 :GNC 9 : unset_bits |= BM_PIN_COUNT_WAITER;
6802 : :
6803 : 68 : UnlockBufHdrExt(bufHdr, buf_state,
6804 : : 0, unset_bits,
6805 : : 0);
6806 : :
7871 tgl@sss.pgh.pa.us 6807 :CBC 68 : PinCountWaitBuf = NULL;
6808 : : /* Loop back and try again */
6809 : : }
6810 : : }
6811 : :
6812 : : /*
6813 : : * Check called from ProcessRecoveryConflictInterrupts() when Startup process
6814 : : * requests cancellation of all pin holders that are blocking it.
6815 : : */
6816 : : bool
5946 simon@2ndQuadrant.co 6817 : 4 : HoldingBufferPinThatDelaysRecovery(void)
6818 : : {
5912 bruce@momjian.us 6819 : 4 : int bufid = GetStartupBufferPinWaitBufId();
6820 : :
6821 : : /*
6822 : : * If we get woken slowly then it's possible that the Startup process was
6823 : : * already woken by other backends before we got here. Also possible that
6824 : : * we get here by multiple interrupts or interrupts at inappropriate
6825 : : * times, so make sure we do nothing if the bufid is not set.
6826 : : */
5946 simon@2ndQuadrant.co 6827 [ + + ]: 4 : if (bufid < 0)
6828 : 2 : return false;
6829 : :
4266 andres@anarazel.de 6830 [ + - ]: 2 : if (GetPrivateRefCount(bufid + 1) > 0)
5946 simon@2ndQuadrant.co 6831 : 2 : return true;
6832 : :
5946 simon@2ndQuadrant.co 6833 :UBC 0 : return false;
6834 : : }
6835 : :
6836 : : /*
6837 : : * ConditionalLockBufferForCleanup - as above, but don't wait to get the lock
6838 : : *
6839 : : * We won't loop, but just check once to see if the pin count is OK. If
6840 : : * not, return false with no lock held.
6841 : : */
6842 : : bool
6802 tgl@sss.pgh.pa.us 6843 :CBC 224579 : ConditionalLockBufferForCleanup(Buffer buffer)
6844 : : {
6845 : : BufferDesc *bufHdr;
6846 : : uint64 buf_state,
6847 : : refcount;
6848 : :
6849 [ - + ]: 224579 : Assert(BufferIsValid(buffer));
6850 : :
6851 : : /* see AIO related comment in LockBufferForCleanup() */
6852 : :
6853 [ + + ]: 224579 : if (BufferIsLocal(buffer))
6854 : : {
3677 andres@anarazel.de 6855 : 12854 : refcount = LocalRefCount[-buffer - 1];
6856 : : /* There should be exactly one pin */
6857 [ - + ]: 12854 : Assert(refcount > 0);
6858 [ + + ]: 12854 : if (refcount != 1)
6802 tgl@sss.pgh.pa.us 6859 : 1540 : return false;
6860 : : /* Nobody else to wait for */
6861 : 11314 : return true;
6862 : : }
6863 : :
6864 : : /* There should be exactly one local pin */
3677 andres@anarazel.de 6865 : 211725 : refcount = GetPrivateRefCount(buffer);
6866 [ - + ]: 211725 : Assert(refcount);
6867 [ + + ]: 211725 : if (refcount != 1)
6802 tgl@sss.pgh.pa.us 6868 : 321 : return false;
6869 : :
6870 : : /* Try to acquire lock */
6871 [ + + ]: 211404 : if (!ConditionalLockBuffer(buffer))
6872 : 84 : return false;
6873 : :
4114 andres@anarazel.de 6874 : 211320 : bufHdr = GetBufferDescriptor(buffer - 1);
3677 6875 : 211320 : buf_state = LockBufHdr(bufHdr);
6876 : 211320 : refcount = BUF_STATE_GET_REFCOUNT(buf_state);
6877 : :
6878 [ - + ]: 211320 : Assert(refcount > 0);
6879 [ + + ]: 211320 : if (refcount == 1)
6880 : : {
6881 : : /* Successfully acquired exclusive lock with pincount 1 */
180 andres@anarazel.de 6882 :GNC 211103 : UnlockBufHdr(bufHdr);
6802 tgl@sss.pgh.pa.us 6883 : 211103 : return true;
6884 : : }
6885 : :
6886 : : /* Failed, so release the lock */
180 andres@anarazel.de 6887 : 217 : UnlockBufHdr(bufHdr);
6802 tgl@sss.pgh.pa.us 6888 : 217 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
6889 : 217 : return false;
6890 : : }
6891 : :
6892 : : /*
6893 : : * IsBufferCleanupOK - as above, but we already have the lock
6894 : : *
6895 : : * Check whether it's OK to perform cleanup on a buffer we've already
6896 : : * locked. If we observe that the pin count is 1, our exclusive lock
6897 : : * happens to be a cleanup lock, and we can proceed with anything that
6898 : : * would have been allowable had we sought a cleanup lock originally.
6899 : : */
6900 : : bool
3469 rhaas@postgresql.org 6901 : 2714 : IsBufferCleanupOK(Buffer buffer)
6902 : : {
6903 : : BufferDesc *bufHdr;
6904 : : uint64 buf_state;
6905 : :
6906 [ - + ]: 2714 : Assert(BufferIsValid(buffer));
6907 : :
6908 : : /* see AIO related comment in LockBufferForCleanup() */
6909 : :
6910 [ - + ]: 2714 : if (BufferIsLocal(buffer))
6911 : : {
6912 : : /* There should be exactly one pin */
3469 rhaas@postgresql.org 6913 [ # # ]:UNC 0 : if (LocalRefCount[-buffer - 1] != 1)
6914 : 0 : return false;
6915 : : /* Nobody else to wait for */
6916 : 0 : return true;
6917 : : }
6918 : :
6919 : : /* There should be exactly one local pin */
3469 rhaas@postgresql.org 6920 [ - + ]:GNC 2714 : if (GetPrivateRefCount(buffer) != 1)
3469 rhaas@postgresql.org 6921 :UNC 0 : return false;
6922 : :
3469 rhaas@postgresql.org 6923 :GNC 2714 : bufHdr = GetBufferDescriptor(buffer - 1);
6924 : :
6925 : : /* caller must hold exclusive lock on buffer */
209 andres@anarazel.de 6926 [ - + ]: 2714 : Assert(BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_EXCLUSIVE));
6927 : :
3469 rhaas@postgresql.org 6928 : 2714 : buf_state = LockBufHdr(bufHdr);
6929 : :
6930 [ - + ]: 2714 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
6931 [ + - ]: 2714 : if (BUF_STATE_GET_REFCOUNT(buf_state) == 1)
6932 : : {
6933 : : /* pincount is OK. */
180 andres@anarazel.de 6934 : 2714 : UnlockBufHdr(bufHdr);
3469 rhaas@postgresql.org 6935 : 2714 : return true;
6936 : : }
6937 : :
180 andres@anarazel.de 6938 :UNC 0 : UnlockBufHdr(bufHdr);
3469 rhaas@postgresql.org 6939 : 0 : return false;
6940 : : }
6941 : :
6942 : : /*
6943 : : * Helper for BufferBeginSetHintBits() and BufferSetHintBits16().
6944 : : *
6945 : : * This checks if the current lock mode already suffices to allow hint bits
6946 : : * being set and, if not, whether the current lock can be upgraded.
6947 : : *
6948 : : * Updates *lockstate when returning true.
6949 : : */
6950 : : static inline bool
56 andres@anarazel.de 6951 :GNC 15207755 : SharedBufferBeginSetHintBits(Buffer buffer, BufferDesc *buf_hdr, uint64 *lockstate)
6952 : : {
6953 : : uint64 old_state;
6954 : : PrivateRefCountEntry *ref;
6955 : : BufferLockMode mode;
6956 : :
6957 : 15207755 : ref = GetPrivateRefCountEntry(buffer, true);
6958 : :
6959 [ - + ]: 15207755 : if (ref == NULL)
56 andres@anarazel.de 6960 [ # # ]:UNC 0 : elog(ERROR, "buffer is not pinned");
6961 : :
56 andres@anarazel.de 6962 :GNC 15207755 : mode = ref->data.lockmode;
6963 [ - + ]: 15207755 : if (mode == BUFFER_LOCK_UNLOCK)
56 andres@anarazel.de 6964 [ # # ]:UNC 0 : elog(ERROR, "buffer is not locked");
6965 : :
6966 : : /* we're done if we are already holding a sufficient lock level */
56 andres@anarazel.de 6967 [ + + + + ]:GNC 15207755 : if (mode == BUFFER_LOCK_EXCLUSIVE || mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6968 : : {
6969 : 11774544 : *lockstate = pg_atomic_read_u64(&buf_hdr->state);
6970 : 11774544 : return true;
6971 : : }
6972 : :
6973 : : /*
6974 : : * We are only holding a share lock right now, try to upgrade it to
6975 : : * SHARE_EXCLUSIVE.
6976 : : */
6977 [ - + ]: 3433211 : Assert(mode == BUFFER_LOCK_SHARE);
6978 : :
6979 : 3433211 : old_state = pg_atomic_read_u64(&buf_hdr->state);
6980 : : while (true)
6981 : 7 : {
6982 : : uint64 desired_state;
6983 : :
6984 : 3433218 : desired_state = old_state;
6985 : :
6986 : : /*
6987 : : * Can't upgrade if somebody else holds the lock in exclusive or
6988 : : * share-exclusive mode.
6989 : : */
6990 [ + + ]: 3433218 : if (unlikely((old_state & (BM_LOCK_VAL_EXCLUSIVE | BM_LOCK_VAL_SHARE_EXCLUSIVE)) != 0))
6991 : : {
6992 : 122 : return false;
6993 : : }
6994 : :
6995 : : /* currently held lock state */
6996 : 3433096 : desired_state -= BM_LOCK_VAL_SHARED;
6997 : :
6998 : : /* new lock level */
6999 : 3433096 : desired_state += BM_LOCK_VAL_SHARE_EXCLUSIVE;
7000 : :
7001 [ + + ]: 3433096 : if (likely(pg_atomic_compare_exchange_u64(&buf_hdr->state,
7002 : : &old_state, desired_state)))
7003 : : {
7004 : 3433089 : ref->data.lockmode = BUFFER_LOCK_SHARE_EXCLUSIVE;
7005 : 3433089 : *lockstate = desired_state;
7006 : :
7007 : 3433089 : return true;
7008 : : }
7009 : : }
7010 : : }
7011 : :
7012 : : /*
7013 : : * Try to acquire the right to set hint bits on the buffer.
7014 : : *
7015 : : * To be allowed to set hint bits, this backend needs to hold either a
7016 : : * share-exclusive or an exclusive lock. In case this backend only holds a
7017 : : * share lock, this function will try to upgrade the lock to
7018 : : * share-exclusive. The caller is only allowed to set hint bits if true is
7019 : : * returned.
7020 : : *
7021 : : * Once BufferBeginSetHintBits() has returned true, hint bits may be set
7022 : : * without further calls to BufferBeginSetHintBits(), until the buffer is
7023 : : * unlocked.
7024 : : *
7025 : : *
7026 : : * Requiring a share-exclusive lock to set hint bits prevents setting hint
7027 : : * bits on buffers that are currently being written out, which could corrupt
7028 : : * the checksum on the page. Flushing buffers also requires a share-exclusive
7029 : : * lock.
7030 : : *
7031 : : * Due to a lock >= share-exclusive being required to set hint bits, only one
7032 : : * backend can set hint bits at a time. Allowing multiple backends to set hint
7033 : : * bits would require more complicated locking: For setting hint bits we'd
7034 : : * need to store the count of backends currently setting hint bits, for I/O we
7035 : : * would need another lock-level conflicting with the hint-setting
7036 : : * lock-level. Given that the share-exclusive lock for setting hint bits is
7037 : : * only held for a short time, that backends often would just set the same
7038 : : * hint bits and that the cost of occasionally not setting hint bits in hotly
7039 : : * accessed pages is fairly low, this seems like an acceptable tradeoff.
7040 : : */
7041 : : bool
7042 : 305948 : BufferBeginSetHintBits(Buffer buffer)
7043 : : {
7044 : : BufferDesc *buf_hdr;
7045 : : uint64 lockstate;
7046 : :
7047 [ + + ]: 305948 : if (BufferIsLocal(buffer))
7048 : : {
7049 : : /*
7050 : : * NB: Will need to check if there is a write in progress, once it is
7051 : : * possible for writes to be done asynchronously.
7052 : : */
56 andres@anarazel.de 7053 :CBC 2437 : return true;
7054 : : }
7055 : :
56 andres@anarazel.de 7056 :GNC 303511 : buf_hdr = GetBufferDescriptor(buffer - 1);
7057 : :
7058 : 303511 : return SharedBufferBeginSetHintBits(buffer, buf_hdr, &lockstate);
7059 : : }
7060 : :
7061 : : /*
7062 : : * End a phase of setting hint bits on this buffer, started with
7063 : : * BufferBeginSetHintBits().
7064 : : *
7065 : : * This would strictly speaking not be required (i.e. the caller could do
7066 : : * MarkBufferDirtyHint() if so desired), but allows us to perform some sanity
7067 : : * checks.
7068 : : */
7069 : : void
7070 : 305933 : BufferFinishSetHintBits(Buffer buffer, bool mark_dirty, bool buffer_std)
7071 : : {
7072 [ + + ]: 305933 : if (!BufferIsLocal(buffer))
7073 [ + + - + ]: 303496 : Assert(BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_SHARE_EXCLUSIVE) ||
7074 : : BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_EXCLUSIVE));
7075 : :
7076 [ + + ]: 305933 : if (mark_dirty)
7077 : 232833 : MarkBufferDirtyHint(buffer, buffer_std);
7078 : 305933 : }
7079 : :
7080 : : /*
7081 : : * Try to set hint bits on a single 16bit value in a buffer.
7082 : : *
7083 : : * If hint bits are allowed to be set, set *ptr = val, try to mark the buffer
7084 : : * dirty and return true. Otherwise false is returned.
7085 : : *
7086 : : * *ptr needs to be a pointer to memory within the buffer.
7087 : : *
7088 : : * This is a bit faster than BufferBeginSetHintBits() /
7089 : : * BufferFinishSetHintBits() when setting hints once in a buffer, but slower
7090 : : * than the former when setting hint bits multiple times in the same buffer.
7091 : : */
7092 : : bool
7093 : 15816708 : BufferSetHintBits16(uint16 *ptr, uint16 val, Buffer buffer)
7094 : : {
7095 : : BufferDesc *buf_hdr;
7096 : : uint64 lockstate;
7097 : : #ifdef USE_ASSERT_CHECKING
7098 : : char *page;
7099 : :
7100 : : /* verify that the address is on the page */
7101 : 15816708 : page = BufferGetPage(buffer);
7102 [ + - - + ]: 15816708 : Assert((char *) ptr >= page && (char *) ptr < (page + BLCKSZ));
7103 : : #endif
7104 : :
56 andres@anarazel.de 7105 [ + + ]:CBC 15816708 : if (BufferIsLocal(buffer))
7106 : : {
56 andres@anarazel.de 7107 :GNC 912464 : *ptr = val;
7108 : :
7109 : 912464 : MarkLocalBufferDirty(buffer);
7110 : :
56 andres@anarazel.de 7111 :GBC 912464 : return true;
7112 : : }
7113 : :
56 andres@anarazel.de 7114 :GNC 14904244 : buf_hdr = GetBufferDescriptor(buffer - 1);
7115 : :
7116 [ + + ]: 14904244 : if (SharedBufferBeginSetHintBits(buffer, buf_hdr, &lockstate))
7117 : : {
7118 : 14904137 : *ptr = val;
7119 : :
7120 : 14904137 : MarkSharedBufferDirtyHint(buffer, buf_hdr, lockstate, true);
7121 : :
56 andres@anarazel.de 7122 :CBC 14904137 : return true;
7123 : : }
7124 : :
56 andres@anarazel.de 7125 :GBC 107 : return false;
7126 : : }
7127 : :
7128 : :
7129 : : /*
7130 : : * Functions for buffer I/O handling
7131 : : *
7132 : : * Also note that these are used only for shared buffers, not local ones.
7133 : : */
7134 : :
7135 : : /*
7136 : : * WaitIO -- Block until the IO_IN_PROGRESS flag on 'buf' is cleared.
7137 : : */
7138 : : static void
3823 rhaas@postgresql.org 7139 :CBC 306 : WaitIO(BufferDesc *buf)
7140 : : {
1881 tmunro@postgresql.or 7141 : 306 : ConditionVariable *cv = BufferDescriptorGetIOCV(buf);
7142 : :
7143 : : /*
7144 : : * Should never end up here with unsubmitted IO, as no AIO unaware code
7145 : : * may be used while in batch mode and AIO aware code needs to have
7146 : : * submitted all staged IO to avoid deadlocks & slowness.
7147 : : */
39 andres@anarazel.de 7148 [ - + ]:GNC 306 : Assert(!pgaio_have_staged());
7149 : :
1881 tmunro@postgresql.or 7150 :CBC 306 : ConditionVariablePrepareToSleep(cv);
7151 : : for (;;)
7732 tgl@sss.pgh.pa.us 7152 : 306 : {
7153 : : uint64 buf_state;
7154 : : PgAioWaitRef iow;
7155 : :
7156 : : /*
7157 : : * It may not be necessary to acquire the spinlock to check the flag
7158 : : * here, but since this test is essential for correctness, we'd better
7159 : : * play it safe.
7160 : : */
3677 andres@anarazel.de 7161 : 612 : buf_state = LockBufHdr(buf);
7162 : :
7163 : : /*
7164 : : * Copy the wait reference while holding the spinlock. This protects
7165 : : * against a concurrent TerminateBufferIO() in another backend from
7166 : : * clearing the wref while it's being read.
7167 : : */
401 7168 : 612 : iow = buf->io_wref;
180 andres@anarazel.de 7169 :GNC 612 : UnlockBufHdr(buf);
7170 : :
7171 : : /* no IO in progress, we don't need to wait */
3677 andres@anarazel.de 7172 [ + + ]:CBC 612 : if (!(buf_state & BM_IO_IN_PROGRESS))
7732 tgl@sss.pgh.pa.us 7173 : 306 : break;
7174 : :
7175 : : /*
7176 : : * The buffer has asynchronous IO in progress, wait for it to
7177 : : * complete.
7178 : : */
401 andres@anarazel.de 7179 [ + + ]: 306 : if (pgaio_wref_valid(&iow))
7180 : : {
7181 : 37 : pgaio_wref_wait(&iow);
7182 : :
7183 : : /*
7184 : : * The AIO subsystem internally uses condition variables and thus
7185 : : * might remove this backend from the BufferDesc's CV. While that
7186 : : * wouldn't cause a correctness issue (the first CV sleep just
7187 : : * immediately returns if not already registered), it seems worth
7188 : : * avoiding unnecessary loop iterations, given that we take care
7189 : : * to do so at the start of the function.
7190 : : */
7191 : 37 : ConditionVariablePrepareToSleep(cv);
7192 : 37 : continue;
7193 : : }
7194 : :
7195 : : /* wait on BufferDesc->cv, e.g. for concurrent synchronous IO */
1881 tmunro@postgresql.or 7196 : 269 : ConditionVariableSleep(cv, WAIT_EVENT_BUFFER_IO);
7197 : : }
7198 : 306 : ConditionVariableCancelSleep();
7732 tgl@sss.pgh.pa.us 7199 : 306 : }
7200 : :
7201 : : /*
7202 : : * StartSharedBufferIO: begin I/O on this buffer
7203 : : * (Assumptions)
7204 : : * The buffer is Pinned
7205 : : *
7206 : : * In several scenarios the buffer may already be undergoing I/O in this or
7207 : : * another backend. How to best handle that depends on the caller's
7208 : : * situation. It might be appropriate to wait synchronously (e.g., because the
7209 : : * buffer is about to be invalidated); wait asynchronously, using the buffer's
7210 : : * IO wait reference (e.g., because the caller is doing readahead and doesn't
7211 : : * need the buffer to be ready immediately); or to not wait at all (e.g.,
7212 : : * because the caller is trying to combine IO for this buffer with another
7213 : : * buffer).
7214 : : *
7215 : : * How and whether to wait is controlled by the wait and io_wref
7216 : : * parameters. In detail:
7217 : : *
7218 : : * - If the caller passes a non-NULL io_wref and the buffer has an I/O wait
7219 : : * reference, the *io_wref is set to the buffer's io_wref and
7220 : : * BUFFER_IO_IN_PROGRESS is returned. This is done regardless of the wait
7221 : : * parameter.
7222 : : *
7223 : : * - If the caller passes a NULL io_wref (i.e. the caller does not want to
7224 : : * asynchronously wait for the completion of the IO), wait = false and the
7225 : : * buffer is undergoing IO, BUFFER_IO_IN_PROGRESS is returned.
7226 : : *
7227 : : * - If wait = true and either the buffer does not have a wait reference,
7228 : : * or the caller passes io_wref = NULL, WaitIO() is used to wait for the IO
7229 : : * to complete. To avoid the potential of deadlocks and unnecessary delays,
7230 : : * all staged I/O is submitted before waiting.
7231 : : *
7232 : : * Input operations are only attempted on buffers that are not BM_VALID, and
7233 : : * output operations only on buffers that are BM_VALID and BM_DIRTY, so we can
7234 : : * always tell if the work is already done. If no I/O is necessary,
7235 : : * BUFFER_IO_ALREADY_DONE is returned.
7236 : : *
7237 : : * If we successfully marked the buffer as BM_IO_IN_PROGRESS,
7238 : : * BUFFER_IO_READY_FOR_IO is returned.
7239 : : */
7240 : : StartBufferIOResult
39 andres@anarazel.de 7241 :GNC 2956721 : StartSharedBufferIO(BufferDesc *buf, bool forInput, bool wait, PgAioWaitRef *io_wref)
7242 : : {
7243 : : uint64 buf_state;
7244 : :
909 heikki.linnakangas@i 7245 :CBC 2956721 : ResourceOwnerEnlarge(CurrentResourceOwner);
7246 : :
7247 : : for (;;)
7248 : : {
3677 andres@anarazel.de 7249 : 2957025 : buf_state = LockBufHdr(buf);
7250 : :
7251 [ + + ]: 2957025 : if (!(buf_state & BM_IO_IN_PROGRESS))
7732 tgl@sss.pgh.pa.us 7252 : 2954570 : break;
7253 : :
7254 : : /* Join the existing IO */
39 andres@anarazel.de 7255 [ + + + + ]:GNC 2455 : if (io_wref != NULL && pgaio_wref_valid(&buf->io_wref))
7256 : : {
7257 : 2136 : *io_wref = buf->io_wref;
7258 : 2136 : UnlockBufHdr(buf);
7259 : :
7260 : 2136 : return BUFFER_IO_IN_PROGRESS;
7261 : : }
7262 [ + + ]: 319 : else if (!wait)
7263 : : {
7264 : 15 : UnlockBufHdr(buf);
7265 : 15 : return BUFFER_IO_IN_PROGRESS;
7266 : : }
7267 : : else
7268 : : {
7269 : : /*
7270 : : * With wait = true, we always have to wait if the caller has
7271 : : * passed io_wref = NULL.
7272 : : *
7273 : : * Even with io_wref != NULL, we have to wait if the buffer's wait
7274 : : * ref is not valid but the IO is in progress, someone else
7275 : : * started IO but hasn't set the wait ref yet. We have no choice
7276 : : * but to wait until the IO completes.
7277 : : */
7278 : 304 : UnlockBufHdr(buf);
7279 : :
7280 : : /*
7281 : : * If this backend currently has staged IO, submit it before
7282 : : * waiting for in-progress IO, to avoid potential deadlocks and
7283 : : * unnecessary delays.
7284 : : */
7285 : 304 : pgaio_submit_staged();
7286 : :
7287 : 304 : WaitIO(buf);
7288 : : }
7289 : : }
7290 : :
7291 : : /* Once we get here, there is definitely no I/O active on this buffer */
7292 : :
7293 : : /* Check if someone else already did the I/O */
3677 andres@anarazel.de 7294 [ + + + + ]:CBC 2954570 : if (forInput ? (buf_state & BM_VALID) : !(buf_state & BM_DIRTY))
7295 : : {
180 andres@anarazel.de 7296 :GNC 544 : UnlockBufHdr(buf);
39 7297 : 544 : return BUFFER_IO_ALREADY_DONE;
7298 : : }
7299 : :
7300 : : /*
7301 : : * No IO in progress and not already done; we will start IO. It's possible
7302 : : * that the IO was in progress but we're not done, because the IO errored
7303 : : * out. We'll do the IO ourselves.
7304 : : */
180 7305 : 2954026 : UnlockBufHdrExt(buf, buf_state,
7306 : : BM_IO_IN_PROGRESS, 0,
7307 : : 0);
7308 : :
1126 andres@anarazel.de 7309 :CBC 2954026 : ResourceOwnerRememberBufferIO(CurrentResourceOwner,
7310 : : BufferDescriptorGetBuffer(buf));
7311 : :
39 andres@anarazel.de 7312 :GNC 2954026 : return BUFFER_IO_READY_FOR_IO;
7313 : : }
7314 : :
7315 : : /*
7316 : : * Wrapper around StartSharedBufferIO / StartLocalBufferIO. Only to be used
7317 : : * when the caller doesn't otherwise need to care about local vs shared. See
7318 : : * StartSharedBufferIO() for details.
7319 : : */
7320 : : StartBufferIOResult
7321 : 1656808 : StartBufferIO(Buffer buffer, bool forInput, bool wait, PgAioWaitRef *io_wref)
7322 : : {
7323 : : BufferDesc *buf_hdr;
7324 : :
7325 [ + + ]: 1656808 : if (BufferIsLocal(buffer))
7326 : : {
7327 : 11065 : buf_hdr = GetLocalBufferDescriptor(-buffer - 1);
7328 : :
7329 : 11065 : return StartLocalBufferIO(buf_hdr, forInput, wait, io_wref);
7330 : : }
7331 : : else
7332 : : {
7333 : 1645743 : buf_hdr = GetBufferDescriptor(buffer - 1);
7334 : :
7335 : 1645743 : return StartSharedBufferIO(buf_hdr, forInput, wait, io_wref);
7336 : : }
7337 : : }
7338 : :
7339 : : /*
7340 : : * TerminateBufferIO: release a buffer we were doing I/O on
7341 : : * (Assumptions)
7342 : : * My process is executing IO for the buffer
7343 : : * BM_IO_IN_PROGRESS bit is set for the buffer
7344 : : * The buffer is Pinned
7345 : : *
7346 : : * If clear_dirty is true, we clear the buffer's BM_DIRTY flag. This is
7347 : : * appropriate when terminating a successful write.
7348 : : *
7349 : : * set_flag_bits gets ORed into the buffer's flags. It must include
7350 : : * BM_IO_ERROR in a failure case. For successful completion it could
7351 : : * be 0, or BM_VALID if we just finished reading in the page.
7352 : : *
7353 : : * If forget_owner is true, we release the buffer I/O from the current
7354 : : * resource owner. (forget_owner=false is used when the resource owner itself
7355 : : * is being released)
7356 : : */
7357 : : void
110 7358 : 2785027 : TerminateBufferIO(BufferDesc *buf, bool clear_dirty, uint64 set_flag_bits,
7359 : : bool forget_owner, bool release_aio)
7360 : : {
7361 : : uint64 buf_state;
7362 : 2785027 : uint64 unset_flag_bits = 0;
180 7363 : 2785027 : int refcount_change = 0;
7364 : :
3677 andres@anarazel.de 7365 :CBC 2785027 : buf_state = LockBufHdr(buf);
7366 : :
7367 [ - + ]: 2785027 : Assert(buf_state & BM_IO_IN_PROGRESS);
180 andres@anarazel.de 7368 :GNC 2785027 : unset_flag_bits |= BM_IO_IN_PROGRESS;
7369 : :
7370 : : /* Clear earlier errors, if this IO failed, it'll be marked again */
7371 : 2785027 : unset_flag_bits |= BM_IO_ERROR;
7372 : :
55 7373 [ + + ]: 2785027 : if (clear_dirty)
180 7374 : 711748 : unset_flag_bits |= BM_DIRTY | BM_CHECKPOINT_NEEDED;
7375 : :
401 andres@anarazel.de 7376 [ + + ]:CBC 2785027 : if (release_aio)
7377 : : {
7378 : : /* release ownership by the AIO subsystem */
7379 [ - + ]: 1474206 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
180 andres@anarazel.de 7380 :GNC 1474206 : refcount_change = -1;
401 andres@anarazel.de 7381 :CBC 1474206 : pgaio_wref_clear(&buf->io_wref);
7382 : : }
7383 : :
180 andres@anarazel.de 7384 :GNC 2785027 : buf_state = UnlockBufHdrExt(buf, buf_state,
7385 : : set_flag_bits, unset_flag_bits,
7386 : : refcount_change);
7387 : :
909 heikki.linnakangas@i 7388 [ + + ]:CBC 2785027 : if (forget_owner)
7389 : 1310793 : ResourceOwnerForgetBufferIO(CurrentResourceOwner,
7390 : : BufferDescriptorGetBuffer(buf));
7391 : :
1881 tmunro@postgresql.or 7392 : 2785027 : ConditionVariableBroadcast(BufferDescriptorGetIOCV(buf));
7393 : :
7394 : : /*
7395 : : * Support LockBufferForCleanup()
7396 : : *
7397 : : * We may have just released the last pin other than the waiter's. In most
7398 : : * cases, this backend holds another pin on the buffer. But, if, for
7399 : : * example, this backend is completing an IO issued by another backend, it
7400 : : * may be time to wake the waiter.
7401 : : */
401 andres@anarazel.de 7402 [ + + - + ]: 2785027 : if (release_aio && (buf_state & BM_PIN_COUNT_WAITER))
401 andres@anarazel.de 7403 :UBC 0 : WakePinCountWaiter(buf);
9605 inoue@tpf.co.jp 7404 :CBC 2785027 : }
7405 : :
7406 : : /*
7407 : : * AbortBufferIO: Clean up active buffer I/O after an error.
7408 : : *
7409 : : * All LWLocks & content locks we might have held have been released, but we
7410 : : * haven't yet released buffer pins, so the buffer is still pinned.
7411 : : *
7412 : : * If I/O was in progress, we always set BM_IO_ERROR, even though it's
7413 : : * possible the error condition wasn't related to the I/O.
7414 : : *
7415 : : * Note: this does not remove the buffer I/O from the resource owner.
7416 : : * That's correct when we're releasing the whole resource owner, but
7417 : : * beware if you use this in other contexts.
7418 : : */
7419 : : static void
1118 pg@bowt.ie 7420 : 15 : AbortBufferIO(Buffer buffer)
7421 : : {
7422 : 15 : BufferDesc *buf_hdr = GetBufferDescriptor(buffer - 1);
7423 : : uint64 buf_state;
7424 : :
1126 andres@anarazel.de 7425 : 15 : buf_state = LockBufHdr(buf_hdr);
7426 [ - + ]: 15 : Assert(buf_state & (BM_IO_IN_PROGRESS | BM_TAG_VALID));
7427 : :
7428 [ + - ]: 15 : if (!(buf_state & BM_VALID))
7429 : : {
7430 [ - + ]: 15 : Assert(!(buf_state & BM_DIRTY));
180 andres@anarazel.de 7431 :GNC 15 : UnlockBufHdr(buf_hdr);
7432 : : }
7433 : : else
7434 : : {
1124 andres@anarazel.de 7435 [ # # ]:UBC 0 : Assert(buf_state & BM_DIRTY);
180 andres@anarazel.de 7436 :UNC 0 : UnlockBufHdr(buf_hdr);
7437 : :
7438 : : /* Issue notice if this is not the first failure... */
1126 andres@anarazel.de 7439 [ # # ]:UBC 0 : if (buf_state & BM_IO_ERROR)
7440 : : {
7441 : : /* Buffer is pinned, so we can read tag without spinlock */
7442 [ # # ]: 0 : ereport(WARNING,
7443 : : (errcode(ERRCODE_IO_ERROR),
7444 : : errmsg("could not write block %u of %s",
7445 : : buf_hdr->tag.blockNum,
7446 : : relpathperm(BufTagGetRelFileLocator(&buf_hdr->tag),
7447 : : BufTagGetForkNum(&buf_hdr->tag)).str),
7448 : : errdetail("Multiple failures --- write error might be permanent.")));
7449 : : }
7450 : : }
7451 : :
401 andres@anarazel.de 7452 :CBC 15 : TerminateBufferIO(buf_hdr, false, BM_IO_ERROR, false, false);
9605 inoue@tpf.co.jp 7453 : 15 : }
7454 : :
7455 : : /*
7456 : : * Error context callback for errors occurring during shared buffer writes.
7457 : : */
7458 : : static void
5744 rhaas@postgresql.org 7459 : 41 : shared_buffer_write_error_callback(void *arg)
7460 : : {
3823 7461 : 41 : BufferDesc *bufHdr = (BufferDesc *) arg;
7462 : :
7463 : : /* Buffer is pinned, so we can read the tag without locking the spinlock */
8396 tgl@sss.pgh.pa.us 7464 [ + - ]: 41 : if (bufHdr != NULL)
252 peter@eisentraut.org 7465 : 82 : errcontext("writing block %u of relation \"%s\"",
7466 : : bufHdr->tag.blockNum,
434 andres@anarazel.de 7467 : 41 : relpathperm(BufTagGetRelFileLocator(&bufHdr->tag),
7468 : : BufTagGetForkNum(&bufHdr->tag)).str);
5744 rhaas@postgresql.org 7469 : 41 : }
7470 : :
7471 : : /*
7472 : : * Error context callback for errors occurring during local buffer writes.
7473 : : */
7474 : : static void
5744 rhaas@postgresql.org 7475 :UBC 0 : local_buffer_write_error_callback(void *arg)
7476 : : {
3823 7477 : 0 : BufferDesc *bufHdr = (BufferDesc *) arg;
7478 : :
5744 7479 [ # # ]: 0 : if (bufHdr != NULL)
252 peter@eisentraut.org 7480 : 0 : errcontext("writing block %u of relation \"%s\"",
7481 : : bufHdr->tag.blockNum,
434 andres@anarazel.de 7482 : 0 : relpathbackend(BufTagGetRelFileLocator(&bufHdr->tag),
7483 : : MyProcNumber,
7484 : : BufTagGetForkNum(&bufHdr->tag)).str);
8396 tgl@sss.pgh.pa.us 7485 : 0 : }
7486 : :
7487 : : /*
7488 : : * RelFileLocator qsort/bsearch comparator; see RelFileLocatorEquals.
7489 : : */
7490 : : static int
1399 rhaas@postgresql.org 7491 :CBC 13256335 : rlocator_comparator(const void *p1, const void *p2)
7492 : : {
7493 : 13256335 : RelFileLocator n1 = *(const RelFileLocator *) p1;
7494 : 13256335 : RelFileLocator n2 = *(const RelFileLocator *) p2;
7495 : :
7496 [ + + ]: 13256335 : if (n1.relNumber < n2.relNumber)
4856 alvherre@alvh.no-ip. 7497 : 13207970 : return -1;
1399 rhaas@postgresql.org 7498 [ + + ]: 48365 : else if (n1.relNumber > n2.relNumber)
4856 alvherre@alvh.no-ip. 7499 : 46596 : return 1;
7500 : :
1399 rhaas@postgresql.org 7501 [ - + ]: 1769 : if (n1.dbOid < n2.dbOid)
4856 alvherre@alvh.no-ip. 7502 :UBC 0 : return -1;
1399 rhaas@postgresql.org 7503 [ - + ]:CBC 1769 : else if (n1.dbOid > n2.dbOid)
4856 alvherre@alvh.no-ip. 7504 :UBC 0 : return 1;
7505 : :
1399 rhaas@postgresql.org 7506 [ - + ]:CBC 1769 : if (n1.spcOid < n2.spcOid)
4856 alvherre@alvh.no-ip. 7507 :UBC 0 : return -1;
1399 rhaas@postgresql.org 7508 [ - + ]:CBC 1769 : else if (n1.spcOid > n2.spcOid)
4856 alvherre@alvh.no-ip. 7509 :UBC 0 : return 1;
7510 : : else
4856 alvherre@alvh.no-ip. 7511 :CBC 1769 : return 0;
7512 : : }
7513 : :
7514 : : /*
7515 : : * Lock buffer header - set BM_LOCKED in buffer state.
7516 : : */
7517 : : uint64
3677 andres@anarazel.de 7518 : 28281999 : LockBufHdr(BufferDesc *desc)
7519 : : {
7520 : : uint64 old_buf_state;
7521 : :
1126 7522 [ - + ]: 28281999 : Assert(!BufferIsLocal(BufferDescriptorGetBuffer(desc)));
7523 : :
7524 : : while (true)
7525 : : {
7526 : : /*
7527 : : * Always try once to acquire the lock directly, without setting up
7528 : : * the spin-delay infrastructure. The work necessary for that shows up
7529 : : * in profiles and is rarely necessary.
7530 : : */
110 andres@anarazel.de 7531 :GNC 28282465 : old_buf_state = pg_atomic_fetch_or_u64(&desc->state, BM_LOCKED);
137 7532 [ + + ]: 28282465 : if (likely(!(old_buf_state & BM_LOCKED)))
7533 : 28281999 : break; /* got lock */
7534 : :
7535 : : /* and then spin without atomic operations until lock is released */
7536 : : {
7537 : : SpinDelayStatus delayStatus;
7538 : :
7539 : 466 : init_local_spin_delay(&delayStatus);
7540 : :
7541 [ + + ]: 5850 : while (old_buf_state & BM_LOCKED)
7542 : : {
7543 : 5384 : perform_spin_delay(&delayStatus);
110 7544 : 5384 : old_buf_state = pg_atomic_read_u64(&desc->state);
7545 : : }
137 7546 : 466 : finish_spin_delay(&delayStatus);
7547 : : }
7548 : :
7549 : : /*
7550 : : * Retry. The lock might obviously already be re-acquired by the time
7551 : : * we're attempting to get it again.
7552 : : */
7553 : : }
7554 : :
3677 andres@anarazel.de 7555 :CBC 28281999 : return old_buf_state | BM_LOCKED;
7556 : : }
7557 : :
7558 : : /*
7559 : : * Wait until the BM_LOCKED flag isn't set anymore and return the buffer's
7560 : : * state at that point.
7561 : : *
7562 : : * Obviously the buffer could be locked by the time the value is returned, so
7563 : : * this is primarily useful in CAS style loops.
7564 : : */
7565 : : pg_noinline uint64
7566 : 385 : WaitBufHdrUnlocked(BufferDesc *buf)
7567 : : {
7568 : : SpinDelayStatus delayStatus;
7569 : : uint64 buf_state;
7570 : :
3673 7571 : 385 : init_local_spin_delay(&delayStatus);
7572 : :
110 andres@anarazel.de 7573 :GNC 385 : buf_state = pg_atomic_read_u64(&buf->state);
7574 : :
3677 andres@anarazel.de 7575 [ + + ]:CBC 8855 : while (buf_state & BM_LOCKED)
7576 : : {
7577 : 8470 : perform_spin_delay(&delayStatus);
110 andres@anarazel.de 7578 :GNC 8470 : buf_state = pg_atomic_read_u64(&buf->state);
7579 : : }
7580 : :
3677 andres@anarazel.de 7581 :CBC 385 : finish_spin_delay(&delayStatus);
7582 : :
7583 : 385 : return buf_state;
7584 : : }
7585 : :
7586 : : /*
7587 : : * BufferTag comparator.
7588 : : */
7589 : : static inline int
1880 tmunro@postgresql.or 7590 :UBC 0 : buffertag_comparator(const BufferTag *ba, const BufferTag *bb)
7591 : : {
7592 : : int ret;
7593 : : RelFileLocator rlocatora;
7594 : : RelFileLocator rlocatorb;
7595 : :
1350 rhaas@postgresql.org 7596 : 0 : rlocatora = BufTagGetRelFileLocator(ba);
7597 : 0 : rlocatorb = BufTagGetRelFileLocator(bb);
7598 : :
7599 : 0 : ret = rlocator_comparator(&rlocatora, &rlocatorb);
7600 : :
3728 andres@anarazel.de 7601 [ # # ]: 0 : if (ret != 0)
7602 : 0 : return ret;
7603 : :
1350 rhaas@postgresql.org 7604 [ # # ]: 0 : if (BufTagGetForkNum(ba) < BufTagGetForkNum(bb))
3728 andres@anarazel.de 7605 : 0 : return -1;
1350 rhaas@postgresql.org 7606 [ # # ]: 0 : if (BufTagGetForkNum(ba) > BufTagGetForkNum(bb))
3728 andres@anarazel.de 7607 : 0 : return 1;
7608 : :
7609 [ # # ]: 0 : if (ba->blockNum < bb->blockNum)
7610 : 0 : return -1;
7611 [ # # ]: 0 : if (ba->blockNum > bb->blockNum)
7612 : 0 : return 1;
7613 : :
7614 : 0 : return 0;
7615 : : }
7616 : :
7617 : : /*
7618 : : * Comparator determining the writeout order in a checkpoint.
7619 : : *
7620 : : * It is important that tablespaces are compared first, the logic balancing
7621 : : * writes between tablespaces relies on it.
7622 : : */
7623 : : static inline int
1880 tmunro@postgresql.or 7624 :CBC 3503709 : ckpt_buforder_comparator(const CkptSortItem *a, const CkptSortItem *b)
7625 : : {
7626 : : /* compare tablespace */
3728 andres@anarazel.de 7627 [ + + ]: 3503709 : if (a->tsId < b->tsId)
7628 : 11200 : return -1;
7629 [ + + ]: 3492509 : else if (a->tsId > b->tsId)
7630 : 29707 : return 1;
7631 : : /* compare relation */
1399 rhaas@postgresql.org 7632 [ + + ]: 3462802 : if (a->relNumber < b->relNumber)
3728 andres@anarazel.de 7633 : 973922 : return -1;
1399 rhaas@postgresql.org 7634 [ + + ]: 2488880 : else if (a->relNumber > b->relNumber)
3728 andres@anarazel.de 7635 : 939896 : return 1;
7636 : : /* compare fork */
7637 [ + + ]: 1548984 : else if (a->forkNum < b->forkNum)
7638 : 64720 : return -1;
7639 [ + + ]: 1484264 : else if (a->forkNum > b->forkNum)
7640 : 73711 : return 1;
7641 : : /* compare block number */
7642 [ + + ]: 1410553 : else if (a->blockNum < b->blockNum)
7643 : 684552 : return -1;
3037 tgl@sss.pgh.pa.us 7644 [ + + ]: 726001 : else if (a->blockNum > b->blockNum)
3728 andres@anarazel.de 7645 : 672254 : return 1;
7646 : : /* equal page IDs are unlikely, but not impossible */
3037 tgl@sss.pgh.pa.us 7647 : 53747 : return 0;
7648 : : }
7649 : :
7650 : : /*
7651 : : * Comparator for a Min-Heap over the per-tablespace checkpoint completion
7652 : : * progress.
7653 : : */
7654 : : static int
3728 andres@anarazel.de 7655 : 286676 : ts_ckpt_progress_comparator(Datum a, Datum b, void *arg)
7656 : : {
270 peter@eisentraut.org 7657 :GNC 286676 : CkptTsStatus *sa = (CkptTsStatus *) DatumGetPointer(a);
7658 : 286676 : CkptTsStatus *sb = (CkptTsStatus *) DatumGetPointer(b);
7659 : :
7660 : : /* we want a min-heap, so return 1 for the a < b */
3728 andres@anarazel.de 7661 [ + + ]:CBC 286676 : if (sa->progress < sb->progress)
7662 : 258702 : return 1;
7663 [ + + ]: 27974 : else if (sa->progress == sb->progress)
7664 : 780 : return 0;
7665 : : else
7666 : 27194 : return -1;
7667 : : }
7668 : :
7669 : : /*
7670 : : * Initialize a writeback context, discarding potential previous state.
7671 : : *
7672 : : * *max_pending is a pointer instead of an immediate value, so the coalesce
7673 : : * limits can easily changed by the GUC mechanism, and so calling code does
7674 : : * not have to check the current configuration. A value of 0 means that no
7675 : : * writeback control will be performed.
7676 : : */
7677 : : void
7678 : 3085 : WritebackContextInit(WritebackContext *context, int *max_pending)
7679 : : {
7680 [ - + ]: 3085 : Assert(*max_pending <= WRITEBACK_MAX_PENDING_FLUSHES);
7681 : :
7682 : 3085 : context->max_pending = max_pending;
7683 : 3085 : context->nr_pending = 0;
7684 : 3085 : }
7685 : :
7686 : : /*
7687 : : * Add buffer to list of pending writeback requests.
7688 : : */
7689 : : void
1084 7690 : 707750 : ScheduleBufferTagForWriteback(WritebackContext *wb_context, IOContext io_context,
7691 : : BufferTag *tag)
7692 : : {
7693 : : PendingWriteback *pending;
7694 : :
7695 : : /*
7696 : : * As pg_flush_data() doesn't do anything with fsync disabled, there's no
7697 : : * point in tracking in that case.
7698 : : */
574 7699 [ + + ]: 707750 : if (io_direct_flags & IO_DIRECT_DATA ||
7700 [ + + ]: 707219 : !enableFsync)
1123 tmunro@postgresql.or 7701 : 707748 : return;
7702 : :
7703 : : /*
7704 : : * Add buffer to the pending writeback array, unless writeback control is
7705 : : * disabled.
7706 : : */
1084 andres@anarazel.de 7707 [ - + ]: 2 : if (*wb_context->max_pending > 0)
7708 : : {
1084 andres@anarazel.de 7709 [ # # ]:UBC 0 : Assert(*wb_context->max_pending <= WRITEBACK_MAX_PENDING_FLUSHES);
7710 : :
7711 : 0 : pending = &wb_context->pending_writebacks[wb_context->nr_pending++];
7712 : :
3728 7713 : 0 : pending->tag = *tag;
7714 : : }
7715 : :
7716 : : /*
7717 : : * Perform pending flushes if the writeback limit is exceeded. This
7718 : : * includes the case where previously an item has been added, but control
7719 : : * is now disabled.
7720 : : */
1084 andres@anarazel.de 7721 [ + - ]:CBC 2 : if (wb_context->nr_pending >= *wb_context->max_pending)
7722 : 2 : IssuePendingWritebacks(wb_context, io_context);
7723 : : }
7724 : :
7725 : : #define ST_SORT sort_pending_writebacks
7726 : : #define ST_ELEMENT_TYPE PendingWriteback
7727 : : #define ST_COMPARE(a, b) buffertag_comparator(&a->tag, &b->tag)
7728 : : #define ST_SCOPE static
7729 : : #define ST_DEFINE
7730 : : #include "lib/sort_template.h"
7731 : :
7732 : : /*
7733 : : * Issue all pending writeback requests, previously scheduled with
7734 : : * ScheduleBufferTagForWriteback, to the OS.
7735 : : *
7736 : : * Because this is only used to improve the OSs IO scheduling we try to never
7737 : : * error out - it's just a hint.
7738 : : */
7739 : : void
7740 : 1208 : IssuePendingWritebacks(WritebackContext *wb_context, IOContext io_context)
7741 : : {
7742 : : instr_time io_start;
7743 : : int i;
7744 : :
7745 [ + - ]: 1208 : if (wb_context->nr_pending == 0)
3728 7746 : 1208 : return;
7747 : :
7748 : : /*
7749 : : * Executing the writes in-order can make them a lot faster, and allows to
7750 : : * merge writeback requests to consecutive blocks into larger writebacks.
7751 : : */
1084 andres@anarazel.de 7752 :UBC 0 : sort_pending_writebacks(wb_context->pending_writebacks,
7753 : 0 : wb_context->nr_pending);
7754 : :
433 michael@paquier.xyz 7755 : 0 : io_start = pgstat_prepare_io_time(track_io_timing);
7756 : :
7757 : : /*
7758 : : * Coalesce neighbouring writes, but nothing else. For that we iterate
7759 : : * through the, now sorted, array of pending flushes, and look forward to
7760 : : * find all neighbouring (or identical) writes.
7761 : : */
1084 andres@anarazel.de 7762 [ # # ]: 0 : for (i = 0; i < wb_context->nr_pending; i++)
7763 : : {
7764 : : PendingWriteback *cur;
7765 : : PendingWriteback *next;
7766 : : SMgrRelation reln;
7767 : : int ahead;
7768 : : BufferTag tag;
7769 : : RelFileLocator currlocator;
3728 7770 : 0 : Size nblocks = 1;
7771 : :
1084 7772 : 0 : cur = &wb_context->pending_writebacks[i];
3728 7773 : 0 : tag = cur->tag;
1350 rhaas@postgresql.org 7774 : 0 : currlocator = BufTagGetRelFileLocator(&tag);
7775 : :
7776 : : /*
7777 : : * Peek ahead, into following writeback requests, to see if they can
7778 : : * be combined with the current one.
7779 : : */
1084 andres@anarazel.de 7780 [ # # ]: 0 : for (ahead = 0; i + ahead + 1 < wb_context->nr_pending; ahead++)
7781 : : {
7782 : :
7783 : 0 : next = &wb_context->pending_writebacks[i + ahead + 1];
7784 : :
7785 : : /* different file, stop */
1350 rhaas@postgresql.org 7786 [ # # # # : 0 : if (!RelFileLocatorEquals(currlocator,
# # ]
7787 [ # # ]: 0 : BufTagGetRelFileLocator(&next->tag)) ||
7788 : 0 : BufTagGetForkNum(&cur->tag) != BufTagGetForkNum(&next->tag))
7789 : : break;
7790 : :
7791 : : /* ok, block queued twice, skip */
3728 andres@anarazel.de 7792 [ # # ]: 0 : if (cur->tag.blockNum == next->tag.blockNum)
7793 : 0 : continue;
7794 : :
7795 : : /* only merge consecutive writes */
7796 [ # # ]: 0 : if (cur->tag.blockNum + 1 != next->tag.blockNum)
7797 : 0 : break;
7798 : :
7799 : 0 : nblocks++;
7800 : 0 : cur = next;
7801 : : }
7802 : :
7803 : 0 : i += ahead;
7804 : :
7805 : : /* and finally tell the kernel to write the data to storage */
793 heikki.linnakangas@i 7806 : 0 : reln = smgropen(currlocator, INVALID_PROC_NUMBER);
1350 rhaas@postgresql.org 7807 : 0 : smgrwriteback(reln, BufTagGetForkNum(&tag), tag.blockNum, nblocks);
7808 : : }
7809 : :
7810 : : /*
7811 : : * Assume that writeback requests are only issued for buffers containing
7812 : : * blocks of permanent relations.
7813 : : */
1084 andres@anarazel.de 7814 : 0 : pgstat_count_io_op_time(IOOBJECT_RELATION, io_context,
476 michael@paquier.xyz 7815 : 0 : IOOP_WRITEBACK, io_start, wb_context->nr_pending, 0);
7816 : :
1084 andres@anarazel.de 7817 : 0 : wb_context->nr_pending = 0;
7818 : : }
7819 : :
7820 : : /* ResourceOwner callbacks */
7821 : :
7822 : : static void
909 heikki.linnakangas@i 7823 :CBC 15 : ResOwnerReleaseBufferIO(Datum res)
7824 : : {
7825 : 15 : Buffer buffer = DatumGetInt32(res);
7826 : :
7827 : 15 : AbortBufferIO(buffer);
7828 : 15 : }
7829 : :
7830 : : static char *
909 heikki.linnakangas@i 7831 :UBC 0 : ResOwnerPrintBufferIO(Datum res)
7832 : : {
7833 : 0 : Buffer buffer = DatumGetInt32(res);
7834 : :
7835 : 0 : return psprintf("lost track of buffer IO on buffer %d", buffer);
7836 : : }
7837 : :
7838 : : /*
7839 : : * Release buffer as part of resource owner cleanup. This will only be called
7840 : : * if the buffer is pinned. If this backend held the content lock at the time
7841 : : * of the error we also need to release that (note that it is not possible to
7842 : : * hold a content lock without a pin).
7843 : : */
7844 : : static void
110 andres@anarazel.de 7845 :GNC 10609 : ResOwnerReleaseBuffer(Datum res)
7846 : : {
909 heikki.linnakangas@i 7847 :CBC 10609 : Buffer buffer = DatumGetInt32(res);
7848 : :
7849 : : /* Like ReleaseBuffer, but don't call ResourceOwnerForgetBuffer */
7850 [ - + ]: 10609 : if (!BufferIsValid(buffer))
909 heikki.linnakangas@i 7851 [ # # ]:UBC 0 : elog(ERROR, "bad buffer ID: %d", buffer);
7852 : :
909 heikki.linnakangas@i 7853 [ + + ]:CBC 10609 : if (BufferIsLocal(buffer))
7854 : 3998 : UnpinLocalBufferNoOwner(buffer);
7855 : : else
7856 : : {
7857 : : PrivateRefCountEntry *ref;
7858 : :
110 andres@anarazel.de 7859 :GNC 6611 : ref = GetPrivateRefCountEntry(buffer, false);
7860 : :
7861 : : /* not having a private refcount would imply resowner corruption */
7862 [ - + ]: 6611 : Assert(ref != NULL);
7863 : :
7864 : : /*
7865 : : * If the buffer was locked at the time of the resowner release,
7866 : : * release the lock now. This should only happen after errors.
7867 : : */
7868 [ + + ]: 6611 : if (ref->data.lockmode != BUFFER_LOCK_UNLOCK)
7869 : : {
7870 : 116 : BufferDesc *buf = GetBufferDescriptor(buffer - 1);
7871 : :
7872 : 116 : HOLD_INTERRUPTS(); /* match the upcoming RESUME_INTERRUPTS */
7873 : 116 : BufferLockUnlock(buffer, buf);
7874 : : }
7875 : :
909 heikki.linnakangas@i 7876 :CBC 6611 : UnpinBufferNoOwner(GetBufferDescriptor(buffer - 1));
7877 : : }
7878 : 10609 : }
7879 : :
7880 : : static char *
110 andres@anarazel.de 7881 :UNC 0 : ResOwnerPrintBuffer(Datum res)
7882 : : {
909 heikki.linnakangas@i 7883 :UBC 0 : return DebugPrintBufferRefcount(DatumGetInt32(res));
7884 : : }
7885 : :
7886 : : /*
7887 : : * Helper function to evict unpinned buffer whose buffer header lock is
7888 : : * already acquired.
7889 : : */
7890 : : static bool
392 andres@anarazel.de 7891 :CBC 2796 : EvictUnpinnedBufferInternal(BufferDesc *desc, bool *buffer_flushed)
7892 : : {
7893 : : uint64 buf_state;
7894 : : bool result;
7895 : :
7896 : 2796 : *buffer_flushed = false;
7897 : :
110 andres@anarazel.de 7898 :GNC 2796 : buf_state = pg_atomic_read_u64(&(desc->state));
392 andres@anarazel.de 7899 [ - + ]:CBC 2796 : Assert(buf_state & BM_LOCKED);
7900 : :
758 tmunro@postgresql.or 7901 [ - + ]: 2796 : if ((buf_state & BM_VALID) == 0)
7902 : : {
180 andres@anarazel.de 7903 :UNC 0 : UnlockBufHdr(desc);
758 tmunro@postgresql.or 7904 :UBC 0 : return false;
7905 : : }
7906 : :
7907 : : /* Check that it's not pinned already. */
758 tmunro@postgresql.or 7908 [ - + ]:CBC 2796 : if (BUF_STATE_GET_REFCOUNT(buf_state) > 0)
7909 : : {
180 andres@anarazel.de 7910 :UNC 0 : UnlockBufHdr(desc);
758 tmunro@postgresql.or 7911 :UBC 0 : return false;
7912 : : }
7913 : :
758 tmunro@postgresql.or 7914 :CBC 2796 : PinBuffer_Locked(desc); /* releases spinlock */
7915 : :
7916 : : /* If it was dirty, try to clean it once. */
7917 [ + + ]: 2796 : if (buf_state & BM_DIRTY)
7918 : : {
209 andres@anarazel.de 7919 :GNC 1143 : FlushUnlockedBuffer(desc, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
392 andres@anarazel.de 7920 :CBC 1143 : *buffer_flushed = true;
7921 : : }
7922 : :
7923 : : /* This will return false if it becomes dirty or someone else pins it. */
758 tmunro@postgresql.or 7924 : 2796 : result = InvalidateVictimBuffer(desc);
7925 : :
7926 : 2796 : UnpinBuffer(desc);
7927 : :
7928 : 2796 : return result;
7929 : : }
7930 : :
7931 : : /*
7932 : : * Try to evict the current block in a shared buffer.
7933 : : *
7934 : : * This function is intended for testing/development use only!
7935 : : *
7936 : : * To succeed, the buffer must not be pinned on entry, so if the caller had a
7937 : : * particular block in mind, it might already have been replaced by some other
7938 : : * block by the time this function runs. It's also unpinned on return, so the
7939 : : * buffer might be occupied again by the time control is returned, potentially
7940 : : * even by the same block. This inherent raciness without other interlocking
7941 : : * makes the function unsuitable for non-testing usage.
7942 : : *
7943 : : * *buffer_flushed is set to true if the buffer was dirty and has been
7944 : : * flushed, false otherwise. However, *buffer_flushed=true does not
7945 : : * necessarily mean that we flushed the buffer, it could have been flushed by
7946 : : * someone else.
7947 : : *
7948 : : * Returns true if the buffer was valid and it has now been made invalid.
7949 : : * Returns false if it wasn't valid, if it couldn't be evicted due to a pin,
7950 : : * or if the buffer becomes dirty again while we're trying to write it out.
7951 : : */
7952 : : bool
392 andres@anarazel.de 7953 : 205 : EvictUnpinnedBuffer(Buffer buf, bool *buffer_flushed)
7954 : : {
7955 : : BufferDesc *desc;
7956 : :
7957 [ + - - + ]: 205 : Assert(BufferIsValid(buf) && !BufferIsLocal(buf));
7958 : :
7959 : : /* Make sure we can pin the buffer. */
7960 : 205 : ResourceOwnerEnlarge(CurrentResourceOwner);
7961 : 205 : ReservePrivateRefCountEntry();
7962 : :
7963 : 205 : desc = GetBufferDescriptor(buf - 1);
7964 : 205 : LockBufHdr(desc);
7965 : :
7966 : 205 : return EvictUnpinnedBufferInternal(desc, buffer_flushed);
7967 : : }
7968 : :
7969 : : /*
7970 : : * Try to evict all the shared buffers.
7971 : : *
7972 : : * This function is intended for testing/development use only! See
7973 : : * EvictUnpinnedBuffer().
7974 : : *
7975 : : * The buffers_* parameters are mandatory and indicate the total count of
7976 : : * buffers that:
7977 : : * - buffers_evicted - were evicted
7978 : : * - buffers_flushed - were flushed
7979 : : * - buffers_skipped - could not be evicted
7980 : : */
7981 : : void
7982 : 1 : EvictAllUnpinnedBuffers(int32 *buffers_evicted, int32 *buffers_flushed,
7983 : : int32 *buffers_skipped)
7984 : : {
7985 : 1 : *buffers_evicted = 0;
7986 : 1 : *buffers_skipped = 0;
7987 : 1 : *buffers_flushed = 0;
7988 : :
7989 [ + + ]: 16385 : for (int buf = 1; buf <= NBuffers; buf++)
7990 : : {
7991 : 16384 : BufferDesc *desc = GetBufferDescriptor(buf - 1);
7992 : : uint64 buf_state;
7993 : : bool buffer_flushed;
7994 : :
182 msawada@postgresql.o 7995 [ - + ]: 16384 : CHECK_FOR_INTERRUPTS();
7996 : :
110 andres@anarazel.de 7997 :GNC 16384 : buf_state = pg_atomic_read_u64(&desc->state);
392 andres@anarazel.de 7998 [ + + ]:CBC 16384 : if (!(buf_state & BM_VALID))
7999 : 14316 : continue;
8000 : :
8001 : 2068 : ResourceOwnerEnlarge(CurrentResourceOwner);
8002 : 2068 : ReservePrivateRefCountEntry();
8003 : :
8004 : 2068 : LockBufHdr(desc);
8005 : :
8006 [ + - ]: 2068 : if (EvictUnpinnedBufferInternal(desc, &buffer_flushed))
8007 : 2068 : (*buffers_evicted)++;
8008 : : else
392 andres@anarazel.de 8009 :UBC 0 : (*buffers_skipped)++;
8010 : :
392 andres@anarazel.de 8011 [ + + ]:CBC 2068 : if (buffer_flushed)
8012 : 998 : (*buffers_flushed)++;
8013 : : }
8014 : 1 : }
8015 : :
8016 : : /*
8017 : : * Try to evict all the shared buffers containing provided relation's pages.
8018 : : *
8019 : : * This function is intended for testing/development use only! See
8020 : : * EvictUnpinnedBuffer().
8021 : : *
8022 : : * The caller must hold at least AccessShareLock on the relation to prevent
8023 : : * the relation from being dropped.
8024 : : *
8025 : : * The buffers_* parameters are mandatory and indicate the total count of
8026 : : * buffers that:
8027 : : * - buffers_evicted - were evicted
8028 : : * - buffers_flushed - were flushed
8029 : : * - buffers_skipped - could not be evicted
8030 : : */
8031 : : void
8032 : 44 : EvictRelUnpinnedBuffers(Relation rel, int32 *buffers_evicted,
8033 : : int32 *buffers_flushed, int32 *buffers_skipped)
8034 : : {
8035 [ - + ]: 44 : Assert(!RelationUsesLocalBuffers(rel));
8036 : :
8037 : 44 : *buffers_skipped = 0;
8038 : 44 : *buffers_evicted = 0;
8039 : 44 : *buffers_flushed = 0;
8040 : :
8041 [ + + ]: 720940 : for (int buf = 1; buf <= NBuffers; buf++)
8042 : : {
8043 : 720896 : BufferDesc *desc = GetBufferDescriptor(buf - 1);
110 andres@anarazel.de 8044 :GNC 720896 : uint64 buf_state = pg_atomic_read_u64(&(desc->state));
8045 : : bool buffer_flushed;
8046 : :
182 msawada@postgresql.o 8047 [ - + ]:CBC 720896 : CHECK_FOR_INTERRUPTS();
8048 : :
8049 : : /* An unlocked precheck should be safe and saves some cycles. */
392 andres@anarazel.de 8050 [ + + ]: 720896 : if ((buf_state & BM_VALID) == 0 ||
8051 [ + + ]: 98775 : !BufTagMatchesRelFileLocator(&desc->tag, &rel->rd_locator))
8052 : 720373 : continue;
8053 : :
8054 : : /* Make sure we can pin the buffer. */
392 andres@anarazel.de 8055 :GBC 523 : ResourceOwnerEnlarge(CurrentResourceOwner);
8056 : 523 : ReservePrivateRefCountEntry();
8057 : :
8058 : 523 : buf_state = LockBufHdr(desc);
8059 : :
8060 : : /* recheck, could have changed without the lock */
8061 [ + - ]: 523 : if ((buf_state & BM_VALID) == 0 ||
8062 [ - + ]: 523 : !BufTagMatchesRelFileLocator(&desc->tag, &rel->rd_locator))
8063 : : {
180 andres@anarazel.de 8064 :UNC 0 : UnlockBufHdr(desc);
392 andres@anarazel.de 8065 :UBC 0 : continue;
8066 : : }
8067 : :
392 andres@anarazel.de 8068 [ + - ]:GBC 523 : if (EvictUnpinnedBufferInternal(desc, &buffer_flushed))
8069 : 523 : (*buffers_evicted)++;
8070 : : else
392 andres@anarazel.de 8071 :UBC 0 : (*buffers_skipped)++;
8072 : :
392 andres@anarazel.de 8073 [ + + ]:GBC 523 : if (buffer_flushed)
8074 : 117 : (*buffers_flushed)++;
8075 : : }
392 andres@anarazel.de 8076 :CBC 44 : }
8077 : :
8078 : : /*
8079 : : * Helper function to mark unpinned buffer dirty whose buffer header lock is
8080 : : * already acquired.
8081 : : */
8082 : : static bool
158 michael@paquier.xyz 8083 :GNC 36 : MarkDirtyUnpinnedBufferInternal(Buffer buf, BufferDesc *desc,
8084 : : bool *buffer_already_dirty)
8085 : : {
8086 : : uint64 buf_state;
8087 : 36 : bool result = false;
8088 : :
8089 : 36 : *buffer_already_dirty = false;
8090 : :
110 andres@anarazel.de 8091 : 36 : buf_state = pg_atomic_read_u64(&(desc->state));
158 michael@paquier.xyz 8092 [ - + ]: 36 : Assert(buf_state & BM_LOCKED);
8093 : :
8094 [ + + ]: 36 : if ((buf_state & BM_VALID) == 0)
8095 : : {
8096 : 1 : UnlockBufHdr(desc);
8097 : 1 : return false;
8098 : : }
8099 : :
8100 : : /* Check that it's not pinned already. */
8101 [ - + ]: 35 : if (BUF_STATE_GET_REFCOUNT(buf_state) > 0)
8102 : : {
158 michael@paquier.xyz 8103 :UNC 0 : UnlockBufHdr(desc);
8104 : 0 : return false;
8105 : : }
8106 : :
8107 : : /* Pin the buffer and then release the buffer spinlock */
158 michael@paquier.xyz 8108 :GNC 35 : PinBuffer_Locked(desc);
8109 : :
8110 : : /* If it was not already dirty, mark it as dirty. */
8111 [ + + ]: 35 : if (!(buf_state & BM_DIRTY))
8112 : : {
110 andres@anarazel.de 8113 : 16 : BufferLockAcquire(buf, desc, BUFFER_LOCK_EXCLUSIVE);
158 michael@paquier.xyz 8114 : 16 : MarkBufferDirty(buf);
8115 : 16 : result = true;
110 andres@anarazel.de 8116 : 16 : BufferLockUnlock(buf, desc);
8117 : : }
8118 : : else
158 michael@paquier.xyz 8119 : 19 : *buffer_already_dirty = true;
8120 : :
8121 : 35 : UnpinBuffer(desc);
8122 : :
8123 : 35 : return result;
8124 : : }
8125 : :
8126 : : /*
8127 : : * Try to mark the provided shared buffer as dirty.
8128 : : *
8129 : : * This function is intended for testing/development use only!
8130 : : *
8131 : : * Same as EvictUnpinnedBuffer() but with MarkBufferDirty() call inside.
8132 : : *
8133 : : * The buffer_already_dirty parameter is mandatory and indicate if the buffer
8134 : : * could not be dirtied because it is already dirty.
8135 : : *
8136 : : * Returns true if the buffer has successfully been marked as dirty.
8137 : : */
8138 : : bool
8139 : 1 : MarkDirtyUnpinnedBuffer(Buffer buf, bool *buffer_already_dirty)
8140 : : {
8141 : : BufferDesc *desc;
8142 : 1 : bool buffer_dirtied = false;
8143 : :
8144 [ - + ]: 1 : Assert(!BufferIsLocal(buf));
8145 : :
8146 : : /* Make sure we can pin the buffer. */
8147 : 1 : ResourceOwnerEnlarge(CurrentResourceOwner);
8148 : 1 : ReservePrivateRefCountEntry();
8149 : :
8150 : 1 : desc = GetBufferDescriptor(buf - 1);
8151 : 1 : LockBufHdr(desc);
8152 : :
8153 : 1 : buffer_dirtied = MarkDirtyUnpinnedBufferInternal(buf, desc, buffer_already_dirty);
8154 : : /* Both can not be true at the same time */
8155 [ - + - - ]: 1 : Assert(!(buffer_dirtied && *buffer_already_dirty));
8156 : :
8157 : 1 : return buffer_dirtied;
8158 : : }
8159 : :
8160 : : /*
8161 : : * Try to mark all the shared buffers containing provided relation's pages as
8162 : : * dirty.
8163 : : *
8164 : : * This function is intended for testing/development use only! See
8165 : : * MarkDirtyUnpinnedBuffer().
8166 : : *
8167 : : * The buffers_* parameters are mandatory and indicate the total count of
8168 : : * buffers that:
8169 : : * - buffers_dirtied - were dirtied
8170 : : * - buffers_already_dirty - were already dirty
8171 : : * - buffers_skipped - could not be dirtied because of a reason different
8172 : : * than a buffer being already dirty.
8173 : : */
8174 : : void
8175 : 1 : MarkDirtyRelUnpinnedBuffers(Relation rel,
8176 : : int32 *buffers_dirtied,
8177 : : int32 *buffers_already_dirty,
8178 : : int32 *buffers_skipped)
8179 : : {
8180 [ - + ]: 1 : Assert(!RelationUsesLocalBuffers(rel));
8181 : :
8182 : 1 : *buffers_dirtied = 0;
8183 : 1 : *buffers_already_dirty = 0;
8184 : 1 : *buffers_skipped = 0;
8185 : :
8186 [ + + ]: 16385 : for (int buf = 1; buf <= NBuffers; buf++)
8187 : : {
8188 : 16384 : BufferDesc *desc = GetBufferDescriptor(buf - 1);
110 andres@anarazel.de 8189 : 16384 : uint64 buf_state = pg_atomic_read_u64(&(desc->state));
8190 : : bool buffer_already_dirty;
8191 : :
158 michael@paquier.xyz 8192 [ - + ]: 16384 : CHECK_FOR_INTERRUPTS();
8193 : :
8194 : : /* An unlocked precheck should be safe and saves some cycles. */
8195 [ + + ]: 16384 : if ((buf_state & BM_VALID) == 0 ||
8196 [ + - ]: 27 : !BufTagMatchesRelFileLocator(&desc->tag, &rel->rd_locator))
8197 : 16384 : continue;
8198 : :
8199 : : /* Make sure we can pin the buffer. */
158 michael@paquier.xyz 8200 :UNC 0 : ResourceOwnerEnlarge(CurrentResourceOwner);
8201 : 0 : ReservePrivateRefCountEntry();
8202 : :
8203 : 0 : buf_state = LockBufHdr(desc);
8204 : :
8205 : : /* recheck, could have changed without the lock */
8206 [ # # ]: 0 : if ((buf_state & BM_VALID) == 0 ||
8207 [ # # ]: 0 : !BufTagMatchesRelFileLocator(&desc->tag, &rel->rd_locator))
8208 : : {
8209 : 0 : UnlockBufHdr(desc);
8210 : 0 : continue;
8211 : : }
8212 : :
8213 [ # # ]: 0 : if (MarkDirtyUnpinnedBufferInternal(buf, desc, &buffer_already_dirty))
8214 : 0 : (*buffers_dirtied)++;
8215 [ # # ]: 0 : else if (buffer_already_dirty)
8216 : 0 : (*buffers_already_dirty)++;
8217 : : else
8218 : 0 : (*buffers_skipped)++;
8219 : : }
158 michael@paquier.xyz 8220 :GNC 1 : }
8221 : :
8222 : : /*
8223 : : * Try to mark all the shared buffers as dirty.
8224 : : *
8225 : : * This function is intended for testing/development use only! See
8226 : : * MarkDirtyUnpinnedBuffer().
8227 : : *
8228 : : * See MarkDirtyRelUnpinnedBuffers() above for details about the buffers_*
8229 : : * parameters.
8230 : : */
8231 : : void
8232 : 1 : MarkDirtyAllUnpinnedBuffers(int32 *buffers_dirtied,
8233 : : int32 *buffers_already_dirty,
8234 : : int32 *buffers_skipped)
8235 : : {
8236 : 1 : *buffers_dirtied = 0;
8237 : 1 : *buffers_already_dirty = 0;
8238 : 1 : *buffers_skipped = 0;
8239 : :
8240 [ + + ]: 16385 : for (int buf = 1; buf <= NBuffers; buf++)
8241 : : {
8242 : 16384 : BufferDesc *desc = GetBufferDescriptor(buf - 1);
8243 : : uint64 buf_state;
8244 : : bool buffer_already_dirty;
8245 : :
8246 [ - + ]: 16384 : CHECK_FOR_INTERRUPTS();
8247 : :
110 andres@anarazel.de 8248 : 16384 : buf_state = pg_atomic_read_u64(&desc->state);
158 michael@paquier.xyz 8249 [ + + ]: 16384 : if (!(buf_state & BM_VALID))
8250 : 16349 : continue;
8251 : :
8252 : 35 : ResourceOwnerEnlarge(CurrentResourceOwner);
8253 : 35 : ReservePrivateRefCountEntry();
8254 : :
8255 : 35 : LockBufHdr(desc);
8256 : :
8257 [ + + ]: 35 : if (MarkDirtyUnpinnedBufferInternal(buf, desc, &buffer_already_dirty))
8258 : 16 : (*buffers_dirtied)++;
8259 [ + - ]: 19 : else if (buffer_already_dirty)
8260 : 19 : (*buffers_already_dirty)++;
8261 : : else
158 michael@paquier.xyz 8262 :UNC 0 : (*buffers_skipped)++;
8263 : : }
158 michael@paquier.xyz 8264 :GNC 1 : }
8265 : :
8266 : : /*
8267 : : * Generic implementation of the AIO handle staging callback for readv/writev
8268 : : * on local/shared buffers.
8269 : : *
8270 : : * Each readv/writev can target multiple buffers. The buffers have already
8271 : : * been registered with the IO handle.
8272 : : *
8273 : : * To make the IO ready for execution ("staging"), we need to ensure that the
8274 : : * targeted buffers are in an appropriate state while the IO is ongoing. For
8275 : : * that the AIO subsystem needs to have its own buffer pin, otherwise an error
8276 : : * in this backend could lead to this backend's buffer pin being released as
8277 : : * part of error handling, which in turn could lead to the buffer being
8278 : : * replaced while IO is ongoing.
8279 : : */
8280 : : static pg_attribute_always_inline void
401 andres@anarazel.de 8281 :CBC 1472227 : buffer_stage_common(PgAioHandle *ioh, bool is_write, bool is_temp)
8282 : : {
8283 : : uint64 *io_data;
8284 : : uint8 handle_data_len;
8285 : : PgAioWaitRef io_ref;
8286 : 1472227 : BufferTag first PG_USED_FOR_ASSERTS_ONLY = {0};
8287 : :
8288 : 1472227 : io_data = pgaio_io_get_handle_data(ioh, &handle_data_len);
8289 : :
8290 : 1472227 : pgaio_io_get_wref(ioh, &io_ref);
8291 : :
8292 : : /* iterate over all buffers affected by the vectored readv/writev */
8293 [ + + ]: 3126562 : for (int i = 0; i < handle_data_len; i++)
8294 : : {
8295 : 1654335 : Buffer buffer = (Buffer) io_data[i];
8296 : 1654335 : BufferDesc *buf_hdr = is_temp ?
8297 : 11130 : GetLocalBufferDescriptor(-buffer - 1)
8298 [ + + ]: 1654335 : : GetBufferDescriptor(buffer - 1);
8299 : : uint64 buf_state;
8300 : :
8301 : : /*
8302 : : * Check that all the buffers are actually ones that could conceivably
8303 : : * be done in one IO, i.e. are sequential. This is the last
8304 : : * buffer-aware code before IO is actually executed and confusion
8305 : : * about which buffers are targeted by IO can be hard to debug, making
8306 : : * it worth doing extra-paranoid checks.
8307 : : */
8308 [ + + ]: 1654335 : if (i == 0)
8309 : 1472227 : first = buf_hdr->tag;
8310 : : else
8311 : : {
8312 [ - + ]: 182108 : Assert(buf_hdr->tag.relNumber == first.relNumber);
8313 [ - + ]: 182108 : Assert(buf_hdr->tag.blockNum == first.blockNum + i);
8314 : : }
8315 : :
8316 [ + + ]: 1654335 : if (is_temp)
110 andres@anarazel.de 8317 :GNC 11130 : buf_state = pg_atomic_read_u64(&buf_hdr->state);
8318 : : else
401 andres@anarazel.de 8319 :CBC 1643205 : buf_state = LockBufHdr(buf_hdr);
8320 : :
8321 : : /* verify the buffer is in the expected state */
8322 [ - + ]: 1654335 : Assert(buf_state & BM_TAG_VALID);
8323 [ - + ]: 1654335 : if (is_write)
8324 : : {
401 andres@anarazel.de 8325 [ # # ]:UBC 0 : Assert(buf_state & BM_VALID);
8326 [ # # ]: 0 : Assert(buf_state & BM_DIRTY);
8327 : : }
8328 : : else
8329 : : {
401 andres@anarazel.de 8330 [ - + ]:CBC 1654335 : Assert(!(buf_state & BM_VALID));
8331 [ - + ]: 1654335 : Assert(!(buf_state & BM_DIRTY));
8332 : : }
8333 : :
8334 : : /* temp buffers don't use BM_IO_IN_PROGRESS */
8335 [ + + ]: 1654335 : if (!is_temp)
8336 [ - + ]: 1643205 : Assert(buf_state & BM_IO_IN_PROGRESS);
8337 : :
8338 [ - + ]: 1654335 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) >= 1);
8339 : :
8340 : : /*
8341 : : * Reflect that the buffer is now owned by the AIO subsystem.
8342 : : *
8343 : : * For local buffers: This can't be done just via LocalRefCount, as
8344 : : * one might initially think, as this backend could error out while
8345 : : * AIO is still in progress, releasing all the pins by the backend
8346 : : * itself.
8347 : : *
8348 : : * This pin is released again in TerminateBufferIO().
8349 : : */
8350 : 1654335 : buf_hdr->io_wref = io_ref;
8351 : :
8352 [ + + ]: 1654335 : if (is_temp)
8353 : : {
180 andres@anarazel.de 8354 :GNC 11130 : buf_state += BUF_REFCOUNT_ONE;
110 8355 : 11130 : pg_atomic_unlocked_write_u64(&buf_hdr->state, buf_state);
8356 : : }
8357 : : else
180 8358 : 1643205 : UnlockBufHdrExt(buf_hdr, buf_state, 0, 0, 1);
8359 : :
8360 : : /*
8361 : : * Ensure the content lock that prevents buffer modifications while
8362 : : * the buffer is being written out is not released early due to an
8363 : : * error.
8364 : : */
401 andres@anarazel.de 8365 [ - + - - ]:CBC 1654335 : if (is_write && !is_temp)
8366 : : {
110 andres@anarazel.de 8367 [ # # ]:UNC 0 : Assert(BufferLockHeldByMe(buf_hdr));
8368 : :
8369 : : /*
8370 : : * Lock is now owned by AIO subsystem.
8371 : : */
8372 : 0 : BufferLockDisown(buffer, buf_hdr);
8373 : : }
8374 : :
8375 : : /*
8376 : : * Stop tracking this buffer via the resowner - the AIO system now
8377 : : * keeps track.
8378 : : */
401 andres@anarazel.de 8379 [ + + ]:CBC 1654335 : if (!is_temp)
8380 : 1643205 : ResourceOwnerForgetBufferIO(CurrentResourceOwner, buffer);
8381 : : }
8382 : 1472227 : }
8383 : :
8384 : : /*
8385 : : * Decode readv errors as encoded by buffer_readv_encode_error().
8386 : : */
8387 : : static inline void
8388 : 962 : buffer_readv_decode_error(PgAioResult result,
8389 : : bool *zeroed_any,
8390 : : bool *ignored_any,
8391 : : uint8 *zeroed_or_error_count,
8392 : : uint8 *checkfail_count,
8393 : : uint8 *first_off)
8394 : : {
8395 : 962 : uint32 rem_error = result.error_data;
8396 : :
8397 : : /* see static asserts in buffer_readv_encode_error */
8398 : : #define READV_COUNT_BITS 7
8399 : : #define READV_COUNT_MASK ((1 << READV_COUNT_BITS) - 1)
8400 : :
8401 : 962 : *zeroed_any = rem_error & 1;
8402 : 962 : rem_error >>= 1;
8403 : :
8404 : 962 : *ignored_any = rem_error & 1;
8405 : 962 : rem_error >>= 1;
8406 : :
8407 : 962 : *zeroed_or_error_count = rem_error & READV_COUNT_MASK;
8408 : 962 : rem_error >>= READV_COUNT_BITS;
8409 : :
8410 : 962 : *checkfail_count = rem_error & READV_COUNT_MASK;
8411 : 962 : rem_error >>= READV_COUNT_BITS;
8412 : :
8413 : 962 : *first_off = rem_error & READV_COUNT_MASK;
8414 : 962 : rem_error >>= READV_COUNT_BITS;
8415 : 962 : }
8416 : :
8417 : : /*
8418 : : * Helper to encode errors for buffer_readv_complete()
8419 : : *
8420 : : * Errors are encoded as follows:
8421 : : * - bit 0 indicates whether any page was zeroed (1) or not (0)
8422 : : * - bit 1 indicates whether any checksum failure was ignored (1) or not (0)
8423 : : * - next READV_COUNT_BITS bits indicate the number of errored or zeroed pages
8424 : : * - next READV_COUNT_BITS bits indicate the number of checksum failures
8425 : : * - next READV_COUNT_BITS bits indicate the first offset of the first page
8426 : : * that was errored or zeroed or, if no errors/zeroes, the first ignored
8427 : : * checksum
8428 : : */
8429 : : static inline void
8430 : 288 : buffer_readv_encode_error(PgAioResult *result,
8431 : : bool is_temp,
8432 : : bool zeroed_any,
8433 : : bool ignored_any,
8434 : : uint8 error_count,
8435 : : uint8 zeroed_count,
8436 : : uint8 checkfail_count,
8437 : : uint8 first_error_off,
8438 : : uint8 first_zeroed_off,
8439 : : uint8 first_ignored_off)
8440 : : {
8441 : :
8442 : 288 : uint8 shift = 0;
8443 [ + + ]: 288 : uint8 zeroed_or_error_count =
8444 : : error_count > 0 ? error_count : zeroed_count;
8445 : : uint8 first_off;
8446 : :
8447 : : StaticAssertDecl(PG_IOV_MAX <= 1 << READV_COUNT_BITS,
8448 : : "PG_IOV_MAX is bigger than reserved space for error data");
8449 : : StaticAssertDecl((1 + 1 + 3 * READV_COUNT_BITS) <= PGAIO_RESULT_ERROR_BITS,
8450 : : "PGAIO_RESULT_ERROR_BITS is insufficient for buffer_readv");
8451 : :
8452 : : /*
8453 : : * We only have space to encode one offset - but luckily that's good
8454 : : * enough. If there is an error, the error is the interesting offset, same
8455 : : * with a zeroed buffer vs an ignored buffer.
8456 : : */
8457 [ + + ]: 288 : if (error_count > 0)
8458 : 141 : first_off = first_error_off;
8459 [ + + ]: 147 : else if (zeroed_count > 0)
8460 : 120 : first_off = first_zeroed_off;
8461 : : else
8462 : 27 : first_off = first_ignored_off;
8463 : :
8464 [ + + - + ]: 288 : Assert(!zeroed_any || error_count == 0);
8465 : :
8466 : 288 : result->error_data = 0;
8467 : :
8468 : 288 : result->error_data |= zeroed_any << shift;
8469 : 288 : shift += 1;
8470 : :
8471 : 288 : result->error_data |= ignored_any << shift;
8472 : 288 : shift += 1;
8473 : :
8474 : 288 : result->error_data |= ((uint32) zeroed_or_error_count) << shift;
8475 : 288 : shift += READV_COUNT_BITS;
8476 : :
8477 : 288 : result->error_data |= ((uint32) checkfail_count) << shift;
8478 : 288 : shift += READV_COUNT_BITS;
8479 : :
8480 : 288 : result->error_data |= ((uint32) first_off) << shift;
8481 : 288 : shift += READV_COUNT_BITS;
8482 : :
8483 [ + + ]: 288 : result->id = is_temp ? PGAIO_HCB_LOCAL_BUFFER_READV :
8484 : : PGAIO_HCB_SHARED_BUFFER_READV;
8485 : :
8486 [ + + ]: 288 : if (error_count > 0)
8487 : 141 : result->status = PGAIO_RS_ERROR;
8488 : : else
8489 : 147 : result->status = PGAIO_RS_WARNING;
8490 : :
8491 : : /*
8492 : : * The encoding is complicated enough to warrant cross-checking it against
8493 : : * the decode function.
8494 : : */
8495 : : #ifdef USE_ASSERT_CHECKING
8496 : : {
8497 : : bool zeroed_any_2,
8498 : : ignored_any_2;
8499 : : uint8 zeroed_or_error_count_2,
8500 : : checkfail_count_2,
8501 : : first_off_2;
8502 : :
8503 : 288 : buffer_readv_decode_error(*result,
8504 : : &zeroed_any_2, &ignored_any_2,
8505 : : &zeroed_or_error_count_2,
8506 : : &checkfail_count_2,
8507 : : &first_off_2);
8508 [ - + ]: 288 : Assert(zeroed_any == zeroed_any_2);
8509 [ - + ]: 288 : Assert(ignored_any == ignored_any_2);
8510 [ - + ]: 288 : Assert(zeroed_or_error_count == zeroed_or_error_count_2);
8511 [ - + ]: 288 : Assert(checkfail_count == checkfail_count_2);
8512 [ - + ]: 288 : Assert(first_off == first_off_2);
8513 : : }
8514 : : #endif
8515 : :
8516 : : #undef READV_COUNT_BITS
8517 : : #undef READV_COUNT_MASK
8518 : 288 : }
8519 : :
8520 : : /*
8521 : : * Helper for AIO readv completion callbacks, supporting both shared and temp
8522 : : * buffers. Gets called once for each buffer in a multi-page read.
8523 : : */
8524 : : static pg_attribute_always_inline void
8525 : 1485336 : buffer_readv_complete_one(PgAioTargetData *td, uint8 buf_off, Buffer buffer,
8526 : : uint8 flags, bool failed, bool is_temp,
8527 : : bool *buffer_invalid,
8528 : : bool *failed_checksum,
8529 : : bool *ignored_checksum,
8530 : : bool *zeroed_buffer)
8531 : : {
8532 : 1485336 : BufferDesc *buf_hdr = is_temp ?
8533 : 11130 : GetLocalBufferDescriptor(-buffer - 1)
8534 [ + + ]: 1485336 : : GetBufferDescriptor(buffer - 1);
8535 : 1485336 : BufferTag tag = buf_hdr->tag;
8536 : 1485336 : char *bufdata = BufferGetBlock(buffer);
8537 : : uint64 set_flag_bits;
8538 : : int piv_flags;
8539 : :
8540 : : /* check that the buffer is in the expected state for a read */
8541 : : #ifdef USE_ASSERT_CHECKING
8542 : : {
110 andres@anarazel.de 8543 :GNC 1485336 : uint64 buf_state = pg_atomic_read_u64(&buf_hdr->state);
8544 : :
401 andres@anarazel.de 8545 [ - + ]:CBC 1485336 : Assert(buf_state & BM_TAG_VALID);
8546 [ - + ]: 1485336 : Assert(!(buf_state & BM_VALID));
8547 : : /* temp buffers don't use BM_IO_IN_PROGRESS */
8548 [ + + ]: 1485336 : if (!is_temp)
8549 [ - + ]: 1474206 : Assert(buf_state & BM_IO_IN_PROGRESS);
8550 [ - + ]: 1485336 : Assert(!(buf_state & BM_DIRTY));
8551 : : }
8552 : : #endif
8553 : :
8554 : 1485336 : *buffer_invalid = false;
8555 : 1485336 : *failed_checksum = false;
8556 : 1485336 : *ignored_checksum = false;
8557 : 1485336 : *zeroed_buffer = false;
8558 : :
8559 : : /*
8560 : : * We ask PageIsVerified() to only log the message about checksum errors,
8561 : : * as the completion might be run in any backend (or IO workers). We will
8562 : : * report checksum errors in buffer_readv_report().
8563 : : */
8564 : 1485336 : piv_flags = PIV_LOG_LOG;
8565 : :
8566 : : /* the local zero_damaged_pages may differ from the definer's */
8567 [ + + ]: 1485336 : if (flags & READ_BUFFERS_IGNORE_CHECKSUM_FAILURES)
8568 : 57 : piv_flags |= PIV_IGNORE_CHECKSUM_FAILURE;
8569 : :
8570 : : /*
8571 : : * If the buffers are marked for zero on error, we want to log that in
8572 : : * case of a checksum failure.
8573 : : */
32 dgustafsson@postgres 8574 [ + + ]:GNC 1485336 : if (flags & READ_BUFFERS_ZERO_ON_ERROR)
8575 : 45842 : piv_flags |= PIV_ZERO_BUFFERS_ON_ERROR;
8576 : :
8577 : : /* Check for garbage data. */
401 andres@anarazel.de 8578 [ + + ]:CBC 1485336 : if (!failed)
8579 : : {
8580 : : /*
8581 : : * If the buffer is not currently pinned by this backend, e.g. because
8582 : : * we're completing this IO after an error, the buffer data will have
8583 : : * been marked as inaccessible when the buffer was unpinned. The AIO
8584 : : * subsystem holds a pin, but that doesn't prevent the buffer from
8585 : : * having been marked as inaccessible. The completion might also be
8586 : : * executed in a different process.
8587 : : */
8588 : : #ifdef USE_VALGRIND
8589 : : if (!BufferIsPinned(buffer))
8590 : : VALGRIND_MAKE_MEM_DEFINED(bufdata, BLCKSZ);
8591 : : #endif
8592 : :
8593 [ + + ]: 1484167 : if (!PageIsVerified((Page) bufdata, tag.blockNum, piv_flags,
8594 : : failed_checksum))
8595 : : {
8596 [ + + ]: 144 : if (flags & READ_BUFFERS_ZERO_ON_ERROR)
8597 : : {
8598 : 69 : memset(bufdata, 0, BLCKSZ);
8599 : 69 : *zeroed_buffer = true;
8600 : : }
8601 : : else
8602 : : {
8603 : 75 : *buffer_invalid = true;
8604 : : /* mark buffer as having failed */
8605 : 75 : failed = true;
8606 : : }
8607 : : }
8608 [ + + ]: 1484023 : else if (*failed_checksum)
8609 : 18 : *ignored_checksum = true;
8610 : :
8611 : : /* undo what we did above */
8612 : : #ifdef USE_VALGRIND
8613 : : if (!BufferIsPinned(buffer))
8614 : : VALGRIND_MAKE_MEM_NOACCESS(bufdata, BLCKSZ);
8615 : : #endif
8616 : :
8617 : : /*
8618 : : * Immediately log a message about the invalid page, but only to the
8619 : : * server log. The reason to do so immediately is that this may be
8620 : : * executed in a different backend than the one that originated the
8621 : : * request. The reason to do so immediately is that the originator
8622 : : * might not process the query result immediately (because it is busy
8623 : : * doing another part of query processing) or at all (e.g. if it was
8624 : : * cancelled or errored out due to another IO also failing). The
8625 : : * definer of the IO will emit an ERROR or WARNING when processing the
8626 : : * IO's results
8627 : : *
8628 : : * To avoid duplicating the code to emit these log messages, we reuse
8629 : : * buffer_readv_report().
8630 : : */
8631 [ + + + + : 1484167 : if (*buffer_invalid || *failed_checksum || *zeroed_buffer)
+ + ]
8632 : : {
396 8633 : 162 : PgAioResult result_one = {0};
8634 : :
401 8635 : 162 : buffer_readv_encode_error(&result_one, is_temp,
8636 : 162 : *zeroed_buffer,
8637 : 162 : *ignored_checksum,
8638 : 162 : *buffer_invalid,
8639 : 162 : *zeroed_buffer ? 1 : 0,
8640 : 162 : *failed_checksum ? 1 : 0,
8641 : : buf_off, buf_off, buf_off);
8642 : 162 : pgaio_result_report(result_one, td, LOG_SERVER_ONLY);
8643 : : }
8644 : : }
8645 : :
8646 : : /* Terminate I/O and set BM_VALID. */
8647 [ + + ]: 1485336 : set_flag_bits = failed ? BM_IO_ERROR : BM_VALID;
8648 [ + + ]: 1485336 : if (is_temp)
8649 : 11130 : TerminateLocalBufferIO(buf_hdr, false, set_flag_bits, true);
8650 : : else
8651 : 1474206 : TerminateBufferIO(buf_hdr, false, set_flag_bits, false, true);
8652 : :
8653 : : /*
8654 : : * Call the BUFFER_READ_DONE tracepoint in the callback, even though the
8655 : : * callback may not be executed in the same backend that called
8656 : : * BUFFER_READ_START. The alternative would be to defer calling the
8657 : : * tracepoint to a later point (e.g. the local completion callback for
8658 : : * shared buffer reads), which seems even less helpful.
8659 : : */
8660 : : TRACE_POSTGRESQL_BUFFER_READ_DONE(tag.forkNum,
8661 : : tag.blockNum,
8662 : : tag.spcOid,
8663 : : tag.dbOid,
8664 : : tag.relNumber,
8665 : : is_temp ? MyProcNumber : INVALID_PROC_NUMBER,
8666 : : false);
8667 : 1485336 : }
8668 : :
8669 : : /*
8670 : : * Perform completion handling of a single AIO read. This read may cover
8671 : : * multiple blocks / buffers.
8672 : : *
8673 : : * Shared between shared and local buffers, to reduce code duplication.
8674 : : */
8675 : : static pg_attribute_always_inline PgAioResult
8676 : 1337520 : buffer_readv_complete(PgAioHandle *ioh, PgAioResult prior_result,
8677 : : uint8 cb_data, bool is_temp)
8678 : : {
8679 : 1337520 : PgAioResult result = prior_result;
8680 : 1337520 : PgAioTargetData *td = pgaio_io_get_target_data(ioh);
8681 : 1337520 : uint8 first_error_off = 0;
8682 : 1337520 : uint8 first_zeroed_off = 0;
8683 : 1337520 : uint8 first_ignored_off = 0;
8684 : 1337520 : uint8 error_count = 0;
8685 : 1337520 : uint8 zeroed_count = 0;
8686 : 1337520 : uint8 ignored_count = 0;
8687 : 1337520 : uint8 checkfail_count = 0;
8688 : : uint64 *io_data;
8689 : : uint8 handle_data_len;
8690 : :
8691 [ + + ]: 1337520 : if (is_temp)
8692 : : {
8693 [ - + ]: 2884 : Assert(td->smgr.is_temp);
8694 [ - + ]: 2884 : Assert(pgaio_io_get_owner(ioh) == MyProcNumber);
8695 : : }
8696 : : else
8697 [ - + ]: 1334636 : Assert(!td->smgr.is_temp);
8698 : :
8699 : : /*
8700 : : * Iterate over all the buffers affected by this IO and call the
8701 : : * per-buffer completion function for each buffer.
8702 : : */
8703 : 1337520 : io_data = pgaio_io_get_handle_data(ioh, &handle_data_len);
8704 [ + + ]: 2822856 : for (uint8 buf_off = 0; buf_off < handle_data_len; buf_off++)
8705 : : {
8706 : 1485336 : Buffer buf = io_data[buf_off];
8707 : : bool failed;
8708 : 1485336 : bool failed_verification = false;
8709 : 1485336 : bool failed_checksum = false;
8710 : 1485336 : bool zeroed_buffer = false;
8711 : 1485336 : bool ignored_checksum = false;
8712 : :
8713 [ - + ]: 1485336 : Assert(BufferIsValid(buf));
8714 : :
8715 : : /*
8716 : : * If the entire I/O failed on a lower-level, each buffer needs to be
8717 : : * marked as failed. In case of a partial read, the first few buffers
8718 : : * may be ok.
8719 : : */
8720 : 1485336 : failed =
8721 : 1485336 : prior_result.status == PGAIO_RS_ERROR
8722 [ + + + + ]: 1485336 : || prior_result.result <= buf_off;
8723 : :
8724 : 1485336 : buffer_readv_complete_one(td, buf_off, buf, cb_data, failed, is_temp,
8725 : : &failed_verification,
8726 : : &failed_checksum,
8727 : : &ignored_checksum,
8728 : : &zeroed_buffer);
8729 : :
8730 : : /*
8731 : : * Track information about the number of different kinds of error
8732 : : * conditions across all pages, as there can be multiple pages failing
8733 : : * verification as part of one IO.
8734 : : */
8735 [ + + + - : 1485336 : if (failed_verification && !zeroed_buffer && error_count++ == 0)
+ + ]
8736 : 66 : first_error_off = buf_off;
8737 [ + + + + ]: 1485336 : if (zeroed_buffer && zeroed_count++ == 0)
8738 : 51 : first_zeroed_off = buf_off;
8739 [ + + + + ]: 1485336 : if (ignored_checksum && ignored_count++ == 0)
8740 : 15 : first_ignored_off = buf_off;
8741 [ + + ]: 1485336 : if (failed_checksum)
8742 : 48 : checkfail_count++;
8743 : : }
8744 : :
8745 : : /*
8746 : : * If the smgr read succeeded [partially] and page verification failed for
8747 : : * some of the pages, adjust the IO's result state appropriately.
8748 : : */
8749 [ + + + + ]: 1337520 : if (prior_result.status != PGAIO_RS_ERROR &&
8750 [ + + + + ]: 1337438 : (error_count > 0 || ignored_count > 0 || zeroed_count > 0))
8751 : : {
8752 : 126 : buffer_readv_encode_error(&result, is_temp,
8753 : : zeroed_count > 0, ignored_count > 0,
8754 : : error_count, zeroed_count, checkfail_count,
8755 : : first_error_off, first_zeroed_off,
8756 : : first_ignored_off);
8757 : 126 : pgaio_result_report(result, td, DEBUG1);
8758 : : }
8759 : :
8760 : : /*
8761 : : * For shared relations this reporting is done in
8762 : : * shared_buffer_readv_complete_local().
8763 : : */
8764 [ + + + + ]: 1337520 : if (is_temp && checkfail_count > 0)
8765 : 3 : pgstat_report_checksum_failures_in_db(td->smgr.rlocator.dbOid,
8766 : : checkfail_count);
8767 : :
8768 : 1337520 : return result;
8769 : : }
8770 : :
8771 : : /*
8772 : : * AIO error reporting callback for aio_shared_buffer_readv_cb and
8773 : : * aio_local_buffer_readv_cb.
8774 : : *
8775 : : * The error is encoded / decoded in buffer_readv_encode_error() /
8776 : : * buffer_readv_decode_error().
8777 : : */
8778 : : static void
8779 : 408 : buffer_readv_report(PgAioResult result, const PgAioTargetData *td,
8780 : : int elevel)
8781 : : {
8782 : 408 : int nblocks = td->smgr.nblocks;
8783 : 408 : BlockNumber first = td->smgr.blockNum;
8784 : 408 : BlockNumber last = first + nblocks - 1;
8785 : 408 : ProcNumber errProc =
8786 [ + + ]: 408 : td->smgr.is_temp ? MyProcNumber : INVALID_PROC_NUMBER;
8787 : : RelPathStr rpath =
8788 : 408 : relpathbackend(td->smgr.rlocator, errProc, td->smgr.forkNum);
8789 : : bool zeroed_any,
8790 : : ignored_any;
8791 : : uint8 zeroed_or_error_count,
8792 : : checkfail_count,
8793 : : first_off;
8794 : : uint8 affected_count;
8795 : : const char *msg_one,
8796 : : *msg_mult,
8797 : : *det_mult,
8798 : : *hint_mult;
8799 : :
8800 : 408 : buffer_readv_decode_error(result, &zeroed_any, &ignored_any,
8801 : : &zeroed_or_error_count,
8802 : : &checkfail_count,
8803 : : &first_off);
8804 : :
8805 : : /*
8806 : : * Treat a read that had both zeroed buffers *and* ignored checksums as a
8807 : : * special case, it's too irregular to be emitted the same way as the
8808 : : * other cases.
8809 : : */
8810 [ + + + + ]: 408 : if (zeroed_any && ignored_any)
8811 : : {
8812 [ + - - + ]: 6 : Assert(zeroed_any && ignored_any);
8813 [ - + ]: 6 : Assert(nblocks > 1); /* same block can't be both zeroed and ignored */
8814 [ - + ]: 6 : Assert(result.status != PGAIO_RS_ERROR);
8815 : 6 : affected_count = zeroed_or_error_count;
8816 : :
8817 [ + - + - ]: 6 : ereport(elevel,
8818 : : errcode(ERRCODE_DATA_CORRUPTED),
8819 : : errmsg("zeroing %u page(s) and ignoring %u checksum failure(s) among blocks %u..%u of relation \"%s\"",
8820 : : affected_count, checkfail_count, first, last, rpath.str),
8821 : : affected_count > 1 ?
8822 : : errdetail("Block %u held the first zeroed page.",
8823 : : first + first_off) : 0,
8824 : : errhint_plural("See server log for details about the other %d invalid block.",
8825 : : "See server log for details about the other %d invalid blocks.",
8826 : : affected_count + checkfail_count - 1,
8827 : : affected_count + checkfail_count - 1));
8828 : 6 : return;
8829 : : }
8830 : :
8831 : : /*
8832 : : * The other messages are highly repetitive. To avoid duplicating a long
8833 : : * and complicated ereport(), gather the translated format strings
8834 : : * separately and then do one common ereport.
8835 : : */
8836 [ + + ]: 402 : if (result.status == PGAIO_RS_ERROR)
8837 : : {
8838 [ - + ]: 204 : Assert(!zeroed_any); /* can't have invalid pages when zeroing them */
8839 : 204 : affected_count = zeroed_or_error_count;
252 peter@eisentraut.org 8840 : 204 : msg_one = _("invalid page in block %u of relation \"%s\"");
8841 : 204 : msg_mult = _("%u invalid pages among blocks %u..%u of relation \"%s\"");
8842 : 204 : det_mult = _("Block %u held the first invalid page.");
401 andres@anarazel.de 8843 : 204 : hint_mult = _("See server log for the other %u invalid block(s).");
8844 : : }
8845 [ + + + - ]: 198 : else if (zeroed_any && !ignored_any)
8846 : : {
8847 : 162 : affected_count = zeroed_or_error_count;
252 peter@eisentraut.org 8848 : 162 : msg_one = _("invalid page in block %u of relation \"%s\"; zeroing out page");
8849 : 162 : msg_mult = _("zeroing out %u invalid pages among blocks %u..%u of relation \"%s\"");
8850 : 162 : det_mult = _("Block %u held the first zeroed page.");
401 andres@anarazel.de 8851 : 162 : hint_mult = _("See server log for the other %u zeroed block(s).");
8852 : : }
8853 [ + - + - ]: 36 : else if (!zeroed_any && ignored_any)
8854 : : {
8855 : 36 : affected_count = checkfail_count;
252 peter@eisentraut.org 8856 : 36 : msg_one = _("ignoring checksum failure in block %u of relation \"%s\"");
8857 : 36 : msg_mult = _("ignoring %u checksum failures among blocks %u..%u of relation \"%s\"");
8858 : 36 : det_mult = _("Block %u held the first ignored page.");
401 andres@anarazel.de 8859 : 36 : hint_mult = _("See server log for the other %u ignored block(s).");
8860 : : }
8861 : : else
401 andres@anarazel.de 8862 :UBC 0 : pg_unreachable();
8863 : :
401 andres@anarazel.de 8864 [ + - + + :CBC 402 : ereport(elevel,
+ + + + ]
8865 : : errcode(ERRCODE_DATA_CORRUPTED),
8866 : : affected_count == 1 ?
8867 : : errmsg_internal(msg_one, first + first_off, rpath.str) :
8868 : : errmsg_internal(msg_mult, affected_count, first, last, rpath.str),
8869 : : affected_count > 1 ? errdetail_internal(det_mult, first + first_off) : 0,
8870 : : affected_count > 1 ? errhint_internal(hint_mult, affected_count - 1) : 0);
8871 : : }
8872 : :
8873 : : static void
8874 : 1469343 : shared_buffer_readv_stage(PgAioHandle *ioh, uint8 cb_data)
8875 : : {
8876 : 1469343 : buffer_stage_common(ioh, false, false);
8877 : 1469343 : }
8878 : :
8879 : : static PgAioResult
8880 : 1334636 : shared_buffer_readv_complete(PgAioHandle *ioh, PgAioResult prior_result,
8881 : : uint8 cb_data)
8882 : : {
8883 : 1334636 : return buffer_readv_complete(ioh, prior_result, cb_data, false);
8884 : : }
8885 : :
8886 : : /*
8887 : : * We need a backend-local completion callback for shared buffers, to be able
8888 : : * to report checksum errors correctly. Unfortunately that can only safely
8889 : : * happen if the reporting backend has previously called
8890 : : * pgstat_prepare_report_checksum_failure(), which we can only guarantee in
8891 : : * the backend that started the IO. Hence this callback.
8892 : : */
8893 : : static PgAioResult
8894 : 1469343 : shared_buffer_readv_complete_local(PgAioHandle *ioh, PgAioResult prior_result,
8895 : : uint8 cb_data)
8896 : : {
8897 : : bool zeroed_any,
8898 : : ignored_any;
8899 : : uint8 zeroed_or_error_count,
8900 : : checkfail_count,
8901 : : first_off;
8902 : :
8903 [ + + ]: 1469343 : if (prior_result.status == PGAIO_RS_OK)
8904 : 1469077 : return prior_result;
8905 : :
8906 : 266 : buffer_readv_decode_error(prior_result,
8907 : : &zeroed_any,
8908 : : &ignored_any,
8909 : : &zeroed_or_error_count,
8910 : : &checkfail_count,
8911 : : &first_off);
8912 : :
8913 [ + + ]: 266 : if (checkfail_count)
8914 : : {
8915 : 36 : PgAioTargetData *td = pgaio_io_get_target_data(ioh);
8916 : :
8917 : 36 : pgstat_report_checksum_failures_in_db(td->smgr.rlocator.dbOid,
8918 : : checkfail_count);
8919 : : }
8920 : :
8921 : 266 : return prior_result;
8922 : : }
8923 : :
8924 : : static void
8925 : 2884 : local_buffer_readv_stage(PgAioHandle *ioh, uint8 cb_data)
8926 : : {
8927 : 2884 : buffer_stage_common(ioh, false, true);
8928 : 2884 : }
8929 : :
8930 : : static PgAioResult
8931 : 2884 : local_buffer_readv_complete(PgAioHandle *ioh, PgAioResult prior_result,
8932 : : uint8 cb_data)
8933 : : {
8934 : 2884 : return buffer_readv_complete(ioh, prior_result, cb_data, true);
8935 : : }
8936 : :
8937 : : /* readv callback is passed READ_BUFFERS_* flags as callback data */
8938 : : const PgAioHandleCallbacks aio_shared_buffer_readv_cb = {
8939 : : .stage = shared_buffer_readv_stage,
8940 : : .complete_shared = shared_buffer_readv_complete,
8941 : : /* need a local callback to report checksum failures */
8942 : : .complete_local = shared_buffer_readv_complete_local,
8943 : : .report = buffer_readv_report,
8944 : : };
8945 : :
8946 : : /* readv callback is passed READ_BUFFERS_* flags as callback data */
8947 : : const PgAioHandleCallbacks aio_local_buffer_readv_cb = {
8948 : : .stage = local_buffer_readv_stage,
8949 : :
8950 : : /*
8951 : : * Note that this, in contrast to the shared_buffers case, uses
8952 : : * complete_local, as only the issuing backend has access to the required
8953 : : * datastructures. This is important in case the IO completion may be
8954 : : * consumed incidentally by another backend.
8955 : : */
8956 : : .complete_local = local_buffer_readv_complete,
8957 : : .report = buffer_readv_report,
8958 : : };
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