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
4073 andres@anarazel.de 309 :CBC 68752286 : ReservePrivateRefCountEntry(void)
310 : : {
311 : : /* Already reserved (or freed), nothing to do */
91 andres@anarazel.de 312 [ + + ]:GNC 68752286 : if (ReservedRefCountSlot != -1)
4073 andres@anarazel.de 313 :CBC 63886789 : 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 [ + + ]: 43789473 : for (i = 0; i < REFCOUNT_ARRAY_ENTRIES; i++)
323 : : {
91 andres@anarazel.de 324 [ + + ]:GNC 38923976 : if (PrivateRefCountArrayKeys[i] == InvalidBuffer)
325 : : {
326 : 28876282 : 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 [ + + ]: 4865497 : if (ReservedRefCountSlot != -1)
336 : 4677464 : 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 : 188033 : victim_slot = PrivateRefCountClock++ % REFCOUNT_ARRAY_ENTRIES;
355 : 188033 : victim_entry = &PrivateRefCountArray[victim_slot];
356 : 188033 : ReservedRefCountSlot = victim_slot;
357 : :
358 : : /* Better be used, otherwise we shouldn't get here. */
359 [ - + ]: 188033 : Assert(PrivateRefCountArrayKeys[victim_slot] != InvalidBuffer);
360 [ - + ]: 188033 : Assert(PrivateRefCountArray[victim_slot].buffer != InvalidBuffer);
361 [ - + ]: 188033 : Assert(PrivateRefCountArrayKeys[victim_slot] == PrivateRefCountArray[victim_slot].buffer);
362 : :
363 : : /* enter victim array entry into hashtable */
3 pg@bowt.ie 364 : 188033 : hashent = refcount_insert(PrivateRefCountHash,
365 : : PrivateRefCountArrayKeys[victim_slot],
366 : : &found);
4073 andres@anarazel.de 367 [ - + ]:CBC 188033 : Assert(!found);
368 : : /* move data from the entry in the array to the hash entry */
91 andres@anarazel.de 369 :GNC 188033 : hashent->data = victim_entry->data;
370 : :
371 : : /* clear the now free array slot */
372 : 188033 : PrivateRefCountArrayKeys[victim_slot] = InvalidBuffer;
373 : 188033 : victim_entry->buffer = InvalidBuffer;
374 : :
375 : : /* clear the whole data member, just for future proofing */
376 : 188033 : memset(&victim_entry->data, 0, sizeof(victim_entry->data));
377 : 188033 : victim_entry->data.refcount = 0;
59 378 : 188033 : victim_entry->data.lockmode = BUFFER_LOCK_UNLOCK;
379 : :
4073 andres@anarazel.de 380 :CBC 188033 : PrivateRefCountOverflowed++;
381 : : }
382 : : }
383 : :
384 : : /*
385 : : * Fill a previously reserved refcount entry.
386 : : */
387 : : static PrivateRefCountEntry *
388 : 62139575 : NewPrivateRefCountEntry(Buffer buffer)
389 : : {
390 : : PrivateRefCountEntry *res;
391 : :
392 : : /* only allowed to be called when a reservation has been made */
91 andres@anarazel.de 393 [ - + ]:GNC 62139575 : Assert(ReservedRefCountSlot != -1);
394 : :
395 : : /* use up the reserved entry */
396 : 62139575 : res = &PrivateRefCountArray[ReservedRefCountSlot];
397 : :
398 : : /* and fill it */
399 : 62139575 : PrivateRefCountArrayKeys[ReservedRefCountSlot] = buffer;
4073 andres@anarazel.de 400 :CBC 62139575 : res->buffer = buffer;
91 andres@anarazel.de 401 :GNC 62139575 : res->data.refcount = 0;
59 402 : 62139575 : res->data.lockmode = BUFFER_LOCK_UNLOCK;
403 : :
404 : : /* update cache for the next lookup */
91 405 : 62139575 : PrivateRefCountEntryLast = ReservedRefCountSlot;
406 : :
407 : 62139575 : ReservedRefCountSlot = -1;
408 : :
4073 andres@anarazel.de 409 :CBC 62139575 : 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 *
91 andres@anarazel.de 419 :GNC 84174187 : GetPrivateRefCountEntrySlow(Buffer buffer, bool do_move)
420 : : {
421 : : PrivateRefCountEntry *res;
422 : 84174187 : 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 : : */
4215 andres@anarazel.de 429 [ + + ]:CBC 757567683 : for (i = 0; i < REFCOUNT_ARRAY_ENTRIES; i++)
430 : : {
91 andres@anarazel.de 431 [ + + ]:GNC 673393496 : if (PrivateRefCountArrayKeys[i] == buffer)
432 : : {
433 : 22681881 : match = i;
434 : : /* see ReservePrivateRefCountEntry() for why we don't return */
435 : : }
436 : : }
437 : :
438 [ + + ]: 84174187 : if (likely(match != -1))
439 : : {
440 : : /* update cache for the next lookup */
441 : 22681881 : PrivateRefCountEntryLast = match;
442 : :
443 : 22681881 : 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 : : */
4073 andres@anarazel.de 453 [ + + ]:CBC 61492306 : if (PrivateRefCountOverflowed == 0)
454 : 59894366 : return NULL;
455 : :
3 pg@bowt.ie 456 :GNC 1597940 : res = refcount_lookup(PrivateRefCountHash, buffer);
457 : :
4073 andres@anarazel.de 458 [ + + ]:CBC 1597940 : if (res == NULL)
459 : 210342 : return NULL;
460 [ + + ]: 1387598 : else if (!do_move)
461 : : {
462 : : /* caller doesn't want us to move the hash entry into the array */
463 : 1289209 : 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 */
3 pg@bowt.ie 472 :GNC 98389 : data = res->data;
473 : 98389 : refcount_delete_item(PrivateRefCountHash, res);
474 [ - + ]: 98389 : Assert(PrivateRefCountOverflowed > 0);
475 : 98389 : PrivateRefCountOverflowed--;
476 : :
477 : : /* Ensure there's a free array slot */
4073 andres@anarazel.de 478 :CBC 98389 : ReservePrivateRefCountEntry();
479 : :
480 : : /* Use up the reserved slot */
91 andres@anarazel.de 481 [ - + ]:GNC 98389 : Assert(ReservedRefCountSlot != -1);
482 : 98389 : free = &PrivateRefCountArray[ReservedRefCountSlot];
483 [ - + ]: 98389 : Assert(PrivateRefCountArrayKeys[ReservedRefCountSlot] == free->buffer);
4073 andres@anarazel.de 484 [ - + ]:CBC 98389 : Assert(free->buffer == InvalidBuffer);
485 : :
486 : : /* and fill it */
487 : 98389 : free->buffer = buffer;
3 pg@bowt.ie 488 :GNC 98389 : free->data = data;
91 andres@anarazel.de 489 : 98389 : PrivateRefCountArrayKeys[ReservedRefCountSlot] = buffer;
490 : : /* update cache for the next lookup */
4 491 : 98389 : PrivateRefCountEntryLast = ReservedRefCountSlot;
492 : :
91 493 : 98389 : ReservedRefCountSlot = -1;
494 : :
4073 andres@anarazel.de 495 :CBC 98389 : 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 *
91 andres@anarazel.de 507 :GNC 984637662 : GetPrivateRefCountEntry(Buffer buffer, bool do_move)
508 : : {
509 [ - + ]: 984637662 : Assert(BufferIsValid(buffer));
510 [ - + ]: 984637662 : 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 [ + + ]: 984637662 : if (likely(PrivateRefCountEntryLast != -1) &&
523 [ + + ]: 984623785 : likely(PrivateRefCountArray[PrivateRefCountEntryLast].buffer == buffer))
524 : : {
525 : 900463475 : 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 : 84174187 : 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
4215 andres@anarazel.de 542 :CBC 506102302 : GetPrivateRefCount(Buffer buffer)
543 : : {
544 : : PrivateRefCountEntry *ref;
545 : :
546 [ - + ]: 506102302 : Assert(BufferIsValid(buffer));
547 [ - + ]: 506102302 : 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 : : */
4073 553 : 506102302 : ref = GetPrivateRefCountEntry(buffer, false);
554 : :
4215 555 [ + + ]: 506102302 : if (ref == NULL)
556 : 37 : return 0;
91 andres@anarazel.de 557 :GNC 506102265 : 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
4215 andres@anarazel.de 565 :CBC 62139575 : ForgetPrivateRefCountEntry(PrivateRefCountEntry *ref)
566 : : {
91 andres@anarazel.de 567 [ - + ]:GNC 62139575 : Assert(ref->data.refcount == 0);
59 568 [ - + ]: 62139575 : Assert(ref->data.lockmode == BUFFER_LOCK_UNLOCK);
569 : :
4215 andres@anarazel.de 570 [ + - + + ]:CBC 62139575 : if (ref >= &PrivateRefCountArray[0] &&
571 : : ref < &PrivateRefCountArray[REFCOUNT_ARRAY_ENTRIES])
572 : : {
573 : 62049931 : ref->buffer = InvalidBuffer;
91 andres@anarazel.de 574 :GNC 62049931 : 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 : 62049931 : ReservedRefCountSlot = ref - PrivateRefCountArray;
583 : : }
584 : : else
585 : : {
3 pg@bowt.ie 586 : 89644 : refcount_delete_item(PrivateRefCountHash, ref);
4215 andres@anarazel.de 587 [ - + ]:CBC 89644 : Assert(PrivateRefCountOverflowed > 0);
588 : 89644 : PrivateRefCountOverflowed--;
589 : : }
590 : 62139575 : }
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 : : static Buffer GetVictimBuffer(BufferAccessStrategy strategy, IOContext io_context);
652 : : static void FlushUnlockedBuffer(BufferDesc *buf, SMgrRelation reln,
653 : : IOObject io_object, IOContext io_context);
654 : : static void FlushBuffer(BufferDesc *buf, SMgrRelation reln,
655 : : IOObject io_object, IOContext io_context);
656 : : static void FindAndDropRelationBuffers(RelFileLocator rlocator,
657 : : ForkNumber forkNum,
658 : : BlockNumber nForkBlock,
659 : : BlockNumber firstDelBlock);
660 : : static void RelationCopyStorageUsingBuffer(RelFileLocator srclocator,
661 : : RelFileLocator dstlocator,
662 : : ForkNumber forkNum, bool permanent);
663 : : static void AtProcExit_Buffers(int code, Datum arg);
664 : : static void CheckForBufferLeaks(void);
665 : : #ifdef USE_ASSERT_CHECKING
666 : : static void AssertNotCatalogBufferLock(Buffer buffer, BufferLockMode mode);
667 : : #endif
668 : : static int rlocator_comparator(const void *p1, const void *p2);
669 : : static inline int buffertag_comparator(const BufferTag *ba, const BufferTag *bb);
670 : : static inline int ckpt_buforder_comparator(const CkptSortItem *a, const CkptSortItem *b);
671 : : static int ts_ckpt_progress_comparator(Datum a, Datum b, void *arg);
672 : :
673 : : static void BufferLockAcquire(Buffer buffer, BufferDesc *buf_hdr, BufferLockMode mode);
674 : : static void BufferLockUnlock(Buffer buffer, BufferDesc *buf_hdr);
675 : : static bool BufferLockConditional(Buffer buffer, BufferDesc *buf_hdr, BufferLockMode mode);
676 : : static bool BufferLockHeldByMeInMode(BufferDesc *buf_hdr, BufferLockMode mode);
677 : : static bool BufferLockHeldByMe(BufferDesc *buf_hdr);
678 : : static inline void BufferLockDisown(Buffer buffer, BufferDesc *buf_hdr);
679 : : static inline int BufferLockDisownInternal(Buffer buffer, BufferDesc *buf_hdr);
680 : : static inline bool BufferLockAttempt(BufferDesc *buf_hdr, BufferLockMode mode);
681 : : static void BufferLockQueueSelf(BufferDesc *buf_hdr, BufferLockMode mode);
682 : : static void BufferLockDequeueSelf(BufferDesc *buf_hdr);
683 : : static void BufferLockWakeup(BufferDesc *buf_hdr, bool unlocked);
684 : : static void BufferLockProcessRelease(BufferDesc *buf_hdr, BufferLockMode mode, uint64 lockstate);
685 : : static inline uint64 BufferLockReleaseSub(BufferLockMode mode);
686 : :
687 : :
688 : : /*
689 : : * Implementation of PrefetchBuffer() for shared buffers.
690 : : */
691 : : PrefetchBufferResult
2167 tmunro@postgresql.or 692 : 32912 : PrefetchSharedBuffer(SMgrRelation smgr_reln,
693 : : ForkNumber forkNum,
694 : : BlockNumber blockNum)
695 : : {
696 : 32912 : PrefetchBufferResult result = {InvalidBuffer, false};
697 : : BufferTag newTag; /* identity of requested block */
698 : : uint32 newHash; /* hash value for newTag */
699 : : LWLock *newPartitionLock; /* buffer partition lock for it */
700 : : int buf_id;
701 : :
702 [ - + ]: 32912 : Assert(BlockNumberIsValid(blockNum));
703 : :
704 : : /* create a tag so we can lookup the buffer */
1327 rhaas@postgresql.org 705 : 32912 : InitBufferTag(&newTag, &smgr_reln->smgr_rlocator.locator,
706 : : forkNum, blockNum);
707 : :
708 : : /* determine its hash code and partition lock ID */
2167 tmunro@postgresql.or 709 : 32912 : newHash = BufTableHashCode(&newTag);
710 : 32912 : newPartitionLock = BufMappingPartitionLock(newHash);
711 : :
712 : : /* see if the block is in the buffer pool already */
713 : 32912 : LWLockAcquire(newPartitionLock, LW_SHARED);
714 : 32912 : buf_id = BufTableLookup(&newTag, newHash);
715 : 32912 : LWLockRelease(newPartitionLock);
716 : :
717 : : /* If not in buffers, initiate prefetch */
718 [ + + ]: 32912 : if (buf_id < 0)
719 : : {
720 : : #ifdef USE_PREFETCH
721 : : /*
722 : : * Try to initiate an asynchronous read. This returns false in
723 : : * recovery if the relation file doesn't exist.
724 : : */
1072 725 [ + + + - ]: 17574 : if ((io_direct_flags & IO_DIRECT_DATA) == 0 &&
820 726 : 8676 : smgrprefetch(smgr_reln, forkNum, blockNum, 1))
727 : : {
2167 728 : 8676 : result.initiated_io = true;
729 : : }
730 : : #endif /* USE_PREFETCH */
731 : : }
732 : : else
733 : : {
734 : : /*
735 : : * Report the buffer it was in at that time. The caller may be able
736 : : * to avoid a buffer table lookup, but it's not pinned and it must be
737 : : * rechecked!
738 : : */
739 : 24014 : result.recent_buffer = buf_id + 1;
740 : : }
741 : :
742 : : /*
743 : : * If the block *is* in buffers, we do nothing. This is not really ideal:
744 : : * the block might be just about to be evicted, which would be stupid
745 : : * since we know we are going to need it soon. But the only easy answer
746 : : * is to bump the usage_count, which does not seem like a great solution:
747 : : * when the caller does ultimately touch the block, usage_count would get
748 : : * bumped again, resulting in too much favoritism for blocks that are
749 : : * involved in a prefetch sequence. A real fix would involve some
750 : : * additional per-buffer state, and it's not clear that there's enough of
751 : : * a problem to justify that.
752 : : */
753 : :
754 : 32912 : return result;
755 : : }
756 : :
757 : : /*
758 : : * PrefetchBuffer -- initiate asynchronous read of a block of a relation
759 : : *
760 : : * This is named by analogy to ReadBuffer but doesn't actually allocate a
761 : : * buffer. Instead it tries to ensure that a future ReadBuffer for the given
762 : : * block will not be delayed by the I/O. Prefetching is optional.
763 : : *
764 : : * There are three possible outcomes:
765 : : *
766 : : * 1. If the block is already cached, the result includes a valid buffer that
767 : : * could be used by the caller to avoid the need for a later buffer lookup, but
768 : : * it's not pinned, so the caller must recheck it.
769 : : *
770 : : * 2. If the kernel has been asked to initiate I/O, the initiated_io member is
771 : : * true. Currently there is no way to know if the data was already cached by
772 : : * the kernel and therefore didn't really initiate I/O, and no way to know when
773 : : * the I/O completes other than using synchronous ReadBuffer().
774 : : *
775 : : * 3. Otherwise, the buffer wasn't already cached by PostgreSQL, and
776 : : * USE_PREFETCH is not defined (this build doesn't support prefetching due to
777 : : * lack of a kernel facility), direct I/O is enabled, or the underlying
778 : : * relation file wasn't found and we are in recovery. (If the relation file
779 : : * wasn't found and we are not in recovery, an error is raised).
780 : : */
781 : : PrefetchBufferResult
6271 tgl@sss.pgh.pa.us 782 : 22347 : PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum)
783 : : {
784 [ - + ]: 22347 : Assert(RelationIsValid(reln));
785 [ - + ]: 22347 : Assert(BlockNumberIsValid(blockNum));
786 : :
5571 rhaas@postgresql.org 787 [ + + ]: 22347 : if (RelationUsesLocalBuffers(reln))
788 : : {
789 : : /* see comments in ReadBufferExtended */
6193 tgl@sss.pgh.pa.us 790 [ + - - + ]: 799 : if (RELATION_IS_OTHER_TEMP(reln))
6193 tgl@sss.pgh.pa.us 791 [ # # ]:UBC 0 : ereport(ERROR,
792 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
793 : : errmsg("cannot access temporary tables of other sessions")));
794 : :
795 : : /* pass it off to localbuf.c */
1707 tgl@sss.pgh.pa.us 796 :CBC 799 : return PrefetchLocalBuffer(RelationGetSmgr(reln), forkNum, blockNum);
797 : : }
798 : : else
799 : : {
800 : : /* pass it to the shared buffer version */
801 : 21548 : return PrefetchSharedBuffer(RelationGetSmgr(reln), forkNum, blockNum);
802 : : }
803 : : }
804 : :
805 : : /*
806 : : * ReadRecentBuffer -- try to pin a block in a recently observed buffer
807 : : *
808 : : * Compared to ReadBuffer(), this avoids a buffer mapping lookup when it's
809 : : * successful. Return true if the buffer is valid and still has the expected
810 : : * tag. In that case, the buffer is pinned and the usage count is bumped.
811 : : */
812 : : bool
1348 rhaas@postgresql.org 813 : 4538 : ReadRecentBuffer(RelFileLocator rlocator, ForkNumber forkNum, BlockNumber blockNum,
814 : : Buffer recent_buffer)
815 : : {
816 : : BufferDesc *bufHdr;
817 : : BufferTag tag;
818 : : uint64 buf_state;
819 : :
1802 tmunro@postgresql.or 820 [ - + ]: 4538 : Assert(BufferIsValid(recent_buffer));
821 : :
858 heikki.linnakangas@i 822 : 4538 : ResourceOwnerEnlarge(CurrentResourceOwner);
1802 tmunro@postgresql.or 823 : 4538 : ReservePrivateRefCountEntry();
1327 rhaas@postgresql.org 824 : 4538 : InitBufferTag(&tag, &rlocator, forkNum, blockNum);
825 : :
1802 tmunro@postgresql.or 826 [ + + ]: 4538 : if (BufferIsLocal(recent_buffer))
827 : : {
1329 heikki.linnakangas@i 828 : 48 : int b = -recent_buffer - 1;
829 : :
830 : 48 : bufHdr = GetLocalBufferDescriptor(b);
59 andres@anarazel.de 831 :GNC 48 : buf_state = pg_atomic_read_u64(&bufHdr->state);
832 : :
833 : : /* Is it still valid and holding the right tag? */
1327 rhaas@postgresql.org 834 [ + - + - ]:CBC 48 : if ((buf_state & BM_VALID) && BufferTagsEqual(&tag, &bufHdr->tag))
835 : : {
1075 andres@anarazel.de 836 : 48 : PinLocalBuffer(bufHdr, true);
837 : :
1438 tmunro@postgresql.or 838 : 48 : pgBufferUsage.local_blks_hit++;
839 : :
1802 840 : 48 : return true;
841 : : }
842 : : }
843 : : else
844 : : {
845 : 4490 : bufHdr = GetBufferDescriptor(recent_buffer - 1);
846 : :
847 : : /*
848 : : * Is it still valid and holding the right tag? We do an unlocked tag
849 : : * comparison first, to make it unlikely that we'll increment the
850 : : * usage counter of the wrong buffer, if someone calls us with a very
851 : : * out of date recent_buffer. Then we'll check it again if we get the
852 : : * pin.
853 : : */
158 andres@anarazel.de 854 [ + + + + ]:GNC 8941 : if (BufferTagsEqual(&tag, &bufHdr->tag) &&
855 : 4451 : PinBuffer(bufHdr, NULL, true))
856 : : {
857 [ + - ]: 4442 : if (BufferTagsEqual(&tag, &bufHdr->tag))
858 : : {
859 : 4442 : pgBufferUsage.shared_blks_hit++;
860 : 4442 : return true;
861 : : }
158 andres@anarazel.de 862 :UNC 0 : UnpinBuffer(bufHdr);
863 : : }
864 : : }
865 : :
1802 tmunro@postgresql.or 866 :CBC 48 : return false;
867 : : }
868 : :
869 : : /*
870 : : * ReadBuffer -- a shorthand for ReadBufferExtended, for reading from main
871 : : * fork with RBM_NORMAL mode and default strategy.
872 : : */
873 : : Buffer
6344 heikki.linnakangas@i 874 : 46494040 : ReadBuffer(Relation reln, BlockNumber blockNum)
875 : : {
876 : 46494040 : return ReadBufferExtended(reln, MAIN_FORKNUM, blockNum, RBM_NORMAL, NULL);
877 : : }
878 : :
879 : : /*
880 : : * ReadBufferExtended -- returns a buffer containing the requested
881 : : * block of the requested relation. If the blknum
882 : : * requested is P_NEW, extend the relation file and
883 : : * allocate a new block. (Caller is responsible for
884 : : * ensuring that only one backend tries to extend a
885 : : * relation at the same time!)
886 : : *
887 : : * Returns: the buffer number for the buffer containing
888 : : * the block read. The returned buffer has been pinned.
889 : : * Does not return on error --- elog's instead.
890 : : *
891 : : * Assume when this function is called, that reln has been opened already.
892 : : *
893 : : * In RBM_NORMAL mode, the page is read from disk, and the page header is
894 : : * validated. An error is thrown if the page header is not valid. (But
895 : : * note that an all-zero page is considered "valid"; see
896 : : * PageIsVerified().)
897 : : *
898 : : * RBM_ZERO_ON_ERROR is like the normal mode, but if the page header is not
899 : : * valid, the page is zeroed instead of throwing an error. This is intended
900 : : * for non-critical data, where the caller is prepared to repair errors.
901 : : *
902 : : * In RBM_ZERO_AND_LOCK mode, if the page isn't in buffer cache already, it's
903 : : * filled with zeros instead of reading it from disk. Useful when the caller
904 : : * is going to fill the page from scratch, since this saves I/O and avoids
905 : : * unnecessary failure if the page-on-disk has corrupt page headers.
906 : : * The page is returned locked to ensure that the caller has a chance to
907 : : * initialize the page before it's made visible to others.
908 : : * Caution: do not use this mode to read a page that is beyond the relation's
909 : : * current physical EOF; that is likely to cause problems in md.c when
910 : : * the page is modified and written out. P_NEW is OK, though.
911 : : *
912 : : * RBM_ZERO_AND_CLEANUP_LOCK is the same as RBM_ZERO_AND_LOCK, but acquires
913 : : * a cleanup-strength lock on the page.
914 : : *
915 : : * RBM_NORMAL_NO_LOG mode is treated the same as RBM_NORMAL here.
916 : : *
917 : : * If strategy is not NULL, a nondefault buffer access strategy is used.
918 : : * See buffer/README for details.
919 : : */
920 : : inline Buffer
921 : 55974777 : ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum,
922 : : ReadBufferMode mode, BufferAccessStrategy strategy)
923 : : {
924 : : Buffer buf;
925 : :
926 : : /*
927 : : * Reject attempts to read non-local temporary relations; we would be
928 : : * likely to get wrong data since we have no visibility into the owning
929 : : * session's local buffers.
930 : : */
6193 tgl@sss.pgh.pa.us 931 [ + + - + ]: 55974777 : if (RELATION_IS_OTHER_TEMP(reln))
6193 tgl@sss.pgh.pa.us 932 [ # # ]:UBC 0 : ereport(ERROR,
933 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
934 : : errmsg("cannot access temporary tables of other sessions")));
935 : :
936 : : /*
937 : : * Read the buffer, and update pgstat counters to reflect a cache hit or
938 : : * miss.
939 : : */
711 tmunro@postgresql.or 940 :CBC 55974777 : buf = ReadBuffer_common(reln, RelationGetSmgr(reln), 0,
941 : : forkNum, blockNum, mode, strategy);
942 : :
6485 heikki.linnakangas@i 943 : 55974750 : return buf;
944 : : }
945 : :
946 : :
947 : : /*
948 : : * ReadBufferWithoutRelcache -- like ReadBufferExtended, but doesn't require
949 : : * a relcache entry for the relation.
950 : : *
951 : : * Pass permanent = true for a RELPERSISTENCE_PERMANENT relation, and
952 : : * permanent = false for a RELPERSISTENCE_UNLOGGED relation. This function
953 : : * cannot be used for temporary relations (and making that work might be
954 : : * difficult, unless we only want to read temporary relations for our own
955 : : * ProcNumber).
956 : : */
957 : : Buffer
1348 rhaas@postgresql.org 958 : 5798588 : ReadBufferWithoutRelcache(RelFileLocator rlocator, ForkNumber forkNum,
959 : : BlockNumber blockNum, ReadBufferMode mode,
960 : : BufferAccessStrategy strategy, bool permanent)
961 : : {
742 heikki.linnakangas@i 962 : 5798588 : SMgrRelation smgr = smgropen(rlocator, INVALID_PROC_NUMBER);
963 : :
711 tmunro@postgresql.or 964 [ + - ]: 5798588 : return ReadBuffer_common(NULL, smgr,
965 : : permanent ? RELPERSISTENCE_PERMANENT : RELPERSISTENCE_UNLOGGED,
966 : : forkNum, blockNum,
967 : : mode, strategy);
968 : : }
969 : :
970 : : /*
971 : : * Convenience wrapper around ExtendBufferedRelBy() extending by one block.
972 : : */
973 : : Buffer
935 974 : 47464 : ExtendBufferedRel(BufferManagerRelation bmr,
975 : : ForkNumber forkNum,
976 : : BufferAccessStrategy strategy,
977 : : uint32 flags)
978 : : {
979 : : Buffer buf;
1075 andres@anarazel.de 980 : 47464 : uint32 extend_by = 1;
981 : :
935 tmunro@postgresql.or 982 : 47464 : ExtendBufferedRelBy(bmr, forkNum, strategy, flags, extend_by,
983 : : &buf, &extend_by);
984 : :
1075 andres@anarazel.de 985 : 47464 : return buf;
986 : : }
987 : :
988 : : /*
989 : : * Extend relation by multiple blocks.
990 : : *
991 : : * Tries to extend the relation by extend_by blocks. Depending on the
992 : : * availability of resources the relation may end up being extended by a
993 : : * smaller number of pages (unless an error is thrown, always by at least one
994 : : * page). *extended_by is updated to the number of pages the relation has been
995 : : * extended to.
996 : : *
997 : : * buffers needs to be an array that is at least extend_by long. Upon
998 : : * completion, the first extend_by array elements will point to a pinned
999 : : * buffer.
1000 : : *
1001 : : * If EB_LOCK_FIRST is part of flags, the first returned buffer is
1002 : : * locked. This is useful for callers that want a buffer that is guaranteed to
1003 : : * be empty.
1004 : : */
1005 : : BlockNumber
935 tmunro@postgresql.or 1006 : 166244 : ExtendBufferedRelBy(BufferManagerRelation bmr,
1007 : : ForkNumber fork,
1008 : : BufferAccessStrategy strategy,
1009 : : uint32 flags,
1010 : : uint32 extend_by,
1011 : : Buffer *buffers,
1012 : : uint32 *extended_by)
1013 : : {
1014 [ - + ]: 166244 : Assert((bmr.rel != NULL) != (bmr.smgr != NULL));
145 alvherre@kurilemu.de 1015 [ - + - - ]:GNC 166244 : Assert(bmr.smgr == NULL || bmr.relpersistence != '\0');
1075 andres@anarazel.de 1016 [ - + ]:CBC 166244 : Assert(extend_by > 0);
1017 : :
145 alvherre@kurilemu.de 1018 [ + - ]:GNC 166244 : if (bmr.relpersistence == '\0')
935 tmunro@postgresql.or 1019 :CBC 166244 : bmr.relpersistence = bmr.rel->rd_rel->relpersistence;
1020 : :
1021 : 166244 : return ExtendBufferedRelCommon(bmr, fork, strategy, flags,
1022 : : extend_by, InvalidBlockNumber,
1023 : : buffers, extended_by);
1024 : : }
1025 : :
1026 : : /*
1027 : : * Extend the relation so it is at least extend_to blocks large, return buffer
1028 : : * (extend_to - 1).
1029 : : *
1030 : : * This is useful for callers that want to write a specific page, regardless
1031 : : * of the current size of the relation (e.g. useful for visibilitymap and for
1032 : : * crash recovery).
1033 : : */
1034 : : Buffer
1035 : 52783 : ExtendBufferedRelTo(BufferManagerRelation bmr,
1036 : : ForkNumber fork,
1037 : : BufferAccessStrategy strategy,
1038 : : uint32 flags,
1039 : : BlockNumber extend_to,
1040 : : ReadBufferMode mode)
1041 : : {
1042 : : BlockNumber current_size;
1075 andres@anarazel.de 1043 : 52783 : uint32 extended_by = 0;
1044 : 52783 : Buffer buffer = InvalidBuffer;
1045 : : Buffer buffers[64];
1046 : :
935 tmunro@postgresql.or 1047 [ - + ]: 52783 : Assert((bmr.rel != NULL) != (bmr.smgr != NULL));
145 alvherre@kurilemu.de 1048 [ + + - + ]:GNC 52783 : Assert(bmr.smgr == NULL || bmr.relpersistence != '\0');
1075 andres@anarazel.de 1049 [ + - - + ]:CBC 52783 : Assert(extend_to != InvalidBlockNumber && extend_to > 0);
1050 : :
145 alvherre@kurilemu.de 1051 [ + + ]:GNC 52783 : if (bmr.relpersistence == '\0')
935 tmunro@postgresql.or 1052 :CBC 7269 : bmr.relpersistence = bmr.rel->rd_rel->relpersistence;
1053 : :
1054 : : /*
1055 : : * If desired, create the file if it doesn't exist. If
1056 : : * smgr_cached_nblocks[fork] is positive then it must exist, no need for
1057 : : * an smgrexists call.
1058 : : */
1075 andres@anarazel.de 1059 [ + + ]: 52783 : if ((flags & EB_CREATE_FORK_IF_NEEDED) &&
145 alvherre@kurilemu.de 1060 [ + - + + ]:GNC 7269 : (BMR_GET_SMGR(bmr)->smgr_cached_nblocks[fork] == 0 ||
1061 [ + - - + ]: 24 : BMR_GET_SMGR(bmr)->smgr_cached_nblocks[fork] == InvalidBlockNumber) &&
1062 [ + - + + ]: 7245 : !smgrexists(BMR_GET_SMGR(bmr), fork))
1063 : : {
935 tmunro@postgresql.or 1064 :CBC 7228 : LockRelationForExtension(bmr.rel, ExclusiveLock);
1065 : :
1066 : : /* recheck, fork might have been created concurrently */
145 alvherre@kurilemu.de 1067 [ + - + - ]:GNC 7228 : if (!smgrexists(BMR_GET_SMGR(bmr), fork))
1068 [ + - ]: 7228 : smgrcreate(BMR_GET_SMGR(bmr), fork, flags & EB_PERFORMING_RECOVERY);
1069 : :
935 tmunro@postgresql.or 1070 :CBC 7228 : UnlockRelationForExtension(bmr.rel, ExclusiveLock);
1071 : : }
1072 : :
1073 : : /*
1074 : : * If requested, invalidate size cache, so that smgrnblocks asks the
1075 : : * kernel.
1076 : : */
1075 andres@anarazel.de 1077 [ + + ]: 52783 : if (flags & EB_CLEAR_SIZE_CACHE)
145 alvherre@kurilemu.de 1078 [ + - ]:GNC 7269 : BMR_GET_SMGR(bmr)->smgr_cached_nblocks[fork] = InvalidBlockNumber;
1079 : :
1080 : : /*
1081 : : * Estimate how many pages we'll need to extend by. This avoids acquiring
1082 : : * unnecessarily many victim buffers.
1083 : : */
1084 [ + + ]: 52783 : current_size = smgrnblocks(BMR_GET_SMGR(bmr), fork);
1085 : :
1086 : : /*
1087 : : * Since no-one else can be looking at the page contents yet, there is no
1088 : : * difference between an exclusive lock and a cleanup-strength lock. Note
1089 : : * that we pass the original mode to ReadBuffer_common() below, when
1090 : : * falling back to reading the buffer to a concurrent relation extension.
1091 : : */
1066 andres@anarazel.de 1092 [ + + - + ]:CBC 52783 : if (mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK)
1075 1093 : 45145 : flags |= EB_LOCK_TARGET;
1094 : :
1095 [ + + ]: 107720 : while (current_size < extend_to)
1096 : : {
1097 : 54937 : uint32 num_pages = lengthof(buffers);
1098 : : BlockNumber first_block;
1099 : :
1100 [ + + ]: 54937 : if ((uint64) current_size + num_pages > extend_to)
1101 : 54871 : num_pages = extend_to - current_size;
1102 : :
935 tmunro@postgresql.or 1103 : 54937 : first_block = ExtendBufferedRelCommon(bmr, fork, strategy, flags,
1104 : : num_pages, extend_to,
1105 : : buffers, &extended_by);
1106 : :
1075 andres@anarazel.de 1107 : 54937 : current_size = first_block + extended_by;
1108 [ - + - - ]: 54937 : Assert(num_pages != 0 || current_size >= extend_to);
1109 : :
908 peter@eisentraut.org 1110 [ + + ]: 117316 : for (uint32 i = 0; i < extended_by; i++)
1111 : : {
1075 andres@anarazel.de 1112 [ + + ]: 62379 : if (first_block + i != extend_to - 1)
1113 : 9602 : ReleaseBuffer(buffers[i]);
1114 : : else
1115 : 52777 : buffer = buffers[i];
1116 : : }
1117 : : }
1118 : :
1119 : : /*
1120 : : * It's possible that another backend concurrently extended the relation.
1121 : : * In that case read the buffer.
1122 : : *
1123 : : * XXX: Should we control this via a flag?
1124 : : */
1125 [ + + ]: 52783 : if (buffer == InvalidBuffer)
1126 : : {
1127 [ - + ]: 6 : Assert(extended_by == 0);
145 alvherre@kurilemu.de 1128 [ + - ]:GNC 6 : buffer = ReadBuffer_common(bmr.rel, BMR_GET_SMGR(bmr), bmr.relpersistence,
1129 : : fork, extend_to - 1, mode, strategy);
1130 : : }
1131 : :
1075 andres@anarazel.de 1132 :CBC 52783 : return buffer;
1133 : : }
1134 : :
1135 : : /*
1136 : : * Lock and optionally zero a buffer, as part of the implementation of
1137 : : * RBM_ZERO_AND_LOCK or RBM_ZERO_AND_CLEANUP_LOCK. The buffer must be already
1138 : : * pinned. If the buffer is not already valid, it is zeroed and made valid.
1139 : : */
1140 : : static void
643 tmunro@postgresql.or 1141 : 332406 : ZeroAndLockBuffer(Buffer buffer, ReadBufferMode mode, bool already_valid)
1142 : : {
1143 : : BufferDesc *bufHdr;
1144 : : bool need_to_zero;
1145 : 332406 : bool isLocalBuf = BufferIsLocal(buffer);
1146 : :
711 1147 [ + + - + ]: 332406 : Assert(mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK);
1148 : :
643 1149 [ + + ]: 332406 : if (already_valid)
1150 : : {
1151 : : /*
1152 : : * If the caller already knew the buffer was valid, we can skip some
1153 : : * header interaction. The caller just wants to lock the buffer.
1154 : : */
1155 : 37700 : need_to_zero = false;
1156 : : }
1157 [ + + ]: 294706 : else if (isLocalBuf)
1158 : : {
1159 : : /* Simple case for non-shared buffers. */
711 1160 : 36 : bufHdr = GetLocalBufferDescriptor(-buffer - 1);
350 andres@anarazel.de 1161 : 36 : need_to_zero = StartLocalBufferIO(bufHdr, true, false);
1162 : : }
1163 : : else
1164 : : {
1165 : : /*
1166 : : * Take BM_IO_IN_PROGRESS, or discover that BM_VALID has been set
1167 : : * concurrently. Even though we aren't doing I/O, that ensures that
1168 : : * we don't zero a page that someone else has pinned. An exclusive
1169 : : * content lock wouldn't be enough, because readers are allowed to
1170 : : * drop the content lock after determining that a tuple is visible
1171 : : * (see buffer access rules in README).
1172 : : */
711 tmunro@postgresql.or 1173 : 294670 : bufHdr = GetBufferDescriptor(buffer - 1);
643 1174 : 294670 : need_to_zero = StartBufferIO(bufHdr, true, false);
1175 : : }
1176 : :
1177 [ + + ]: 332406 : if (need_to_zero)
1178 : : {
1179 : 294706 : memset(BufferGetPage(buffer), 0, BLCKSZ);
1180 : :
1181 : : /*
1182 : : * Grab the buffer content lock before marking the page as valid, to
1183 : : * make sure that no other backend sees the zeroed page before the
1184 : : * caller has had a chance to initialize it.
1185 : : *
1186 : : * Since no-one else can be looking at the page contents yet, there is
1187 : : * no difference between an exclusive lock and a cleanup-strength
1188 : : * lock. (Note that we cannot use LockBuffer() or
1189 : : * LockBufferForCleanup() here, because they assert that the buffer is
1190 : : * already valid.)
1191 : : */
1192 [ + + ]: 294706 : if (!isLocalBuf)
158 andres@anarazel.de 1193 :GNC 294670 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
1194 : :
1195 : : /* Set BM_VALID, terminate IO, and wake up any waiters */
643 tmunro@postgresql.or 1196 [ + + ]:CBC 294706 : if (isLocalBuf)
350 andres@anarazel.de 1197 : 36 : TerminateLocalBufferIO(bufHdr, false, BM_VALID, false);
1198 : : else
1199 : 294670 : TerminateBufferIO(bufHdr, false, BM_VALID, true, false);
1200 : : }
643 tmunro@postgresql.or 1201 [ + + ]: 37700 : else if (!isLocalBuf)
1202 : : {
1203 : : /*
1204 : : * The buffer is valid, so we can't zero it. The caller still expects
1205 : : * the page to be locked on return.
1206 : : */
1207 [ + + ]: 37670 : if (mode == RBM_ZERO_AND_LOCK)
1208 : 37597 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
1209 : : else
1210 : 73 : LockBufferForCleanup(buffer);
1211 : : }
711 1212 : 332406 : }
1213 : :
1214 : : /*
1215 : : * Pin a buffer for a given block. *foundPtr is set to true if the block was
1216 : : * already present, or false if more work is required to either read it in or
1217 : : * zero it.
1218 : : */
1219 : : static pg_attribute_always_inline Buffer
1220 : 65729788 : PinBufferForBlock(Relation rel,
1221 : : SMgrRelation smgr,
1222 : : char persistence,
1223 : : ForkNumber forkNum,
1224 : : BlockNumber blockNum,
1225 : : BufferAccessStrategy strategy,
1226 : : bool *foundPtr)
1227 : : {
1228 : : BufferDesc *bufHdr;
1229 : : IOContext io_context;
1230 : : IOObject io_object;
1231 : :
1232 [ - + ]: 65729788 : Assert(blockNum != P_NEW);
1233 : :
1234 : : /* Persistence should be set before */
603 noah@leadboat.com 1235 [ + + + + : 65729788 : Assert((persistence == RELPERSISTENCE_TEMP ||
- + ]
1236 : : persistence == RELPERSISTENCE_PERMANENT ||
1237 : : persistence == RELPERSISTENCE_UNLOGGED));
1238 : :
711 tmunro@postgresql.or 1239 [ + + ]: 65729788 : if (persistence == RELPERSISTENCE_TEMP)
1240 : : {
1241 : 1538946 : io_context = IOCONTEXT_NORMAL;
1242 : 1538946 : io_object = IOOBJECT_TEMP_RELATION;
1243 : : }
1244 : : else
1245 : : {
1246 : 64190842 : io_context = IOContextForStrategy(strategy);
1247 : 64190842 : io_object = IOOBJECT_RELATION;
1248 : : }
1249 : :
1250 : : TRACE_POSTGRESQL_BUFFER_READ_START(forkNum, blockNum,
1251 : : smgr->smgr_rlocator.locator.spcOid,
1252 : : smgr->smgr_rlocator.locator.dbOid,
1253 : : smgr->smgr_rlocator.locator.relNumber,
1254 : : smgr->smgr_rlocator.backend);
1255 : :
1256 [ + + ]: 65729788 : if (persistence == RELPERSISTENCE_TEMP)
1257 : : {
1258 : 1538946 : bufHdr = LocalBufferAlloc(smgr, forkNum, blockNum, foundPtr);
1259 [ + + ]: 1538940 : if (*foundPtr)
5934 rhaas@postgresql.org 1260 : 1530514 : pgBufferUsage.local_blks_hit++;
1261 : : }
1262 : : else
1263 : : {
711 tmunro@postgresql.or 1264 : 64190842 : bufHdr = BufferAlloc(smgr, persistence, forkNum, blockNum,
1265 : : strategy, foundPtr, io_context);
1266 [ + + ]: 64190842 : if (*foundPtr)
1267 : 62390693 : pgBufferUsage.shared_blks_hit++;
1268 : : }
1269 [ + + ]: 65729782 : if (rel)
1270 : : {
1271 : : /*
1272 : : * While pgBufferUsage's "read" counter isn't bumped unless we reach
1273 : : * WaitReadBuffers() (so, not for hits, and not for buffers that are
1274 : : * zeroed instead), the per-relation stats always count them.
1275 : : */
1276 [ + + + + : 59684485 : pgstat_count_buffer_read(rel);
+ + ]
1277 [ + + ]: 59684485 : if (*foundPtr)
1278 [ + + - + : 58359554 : pgstat_count_buffer_hit(rel);
+ + ]
1279 : : }
1280 [ + + ]: 65729782 : if (*foundPtr)
1281 : : {
425 michael@paquier.xyz 1282 : 63921207 : pgstat_count_io_op(io_object, io_context, IOOP_HIT, 1, 0);
1075 andres@anarazel.de 1283 [ + + ]: 63921207 : if (VacuumCostActive)
1284 : 128820 : VacuumCostBalance += VacuumCostPageHit;
1285 : :
1286 : : TRACE_POSTGRESQL_BUFFER_READ_DONE(forkNum, blockNum,
1287 : : smgr->smgr_rlocator.locator.spcOid,
1288 : : smgr->smgr_rlocator.locator.dbOid,
1289 : : smgr->smgr_rlocator.locator.relNumber,
1290 : : smgr->smgr_rlocator.backend,
1291 : : true);
1292 : : }
1293 : :
711 tmunro@postgresql.or 1294 : 65729782 : return BufferDescriptorGetBuffer(bufHdr);
1295 : : }
1296 : :
1297 : : /*
1298 : : * ReadBuffer_common -- common logic for all ReadBuffer variants
1299 : : *
1300 : : * smgr is required, rel is optional unless using P_NEW.
1301 : : */
1302 : : static pg_attribute_always_inline Buffer
1303 : 61773371 : ReadBuffer_common(Relation rel, SMgrRelation smgr, char smgr_persistence,
1304 : : ForkNumber forkNum,
1305 : : BlockNumber blockNum, ReadBufferMode mode,
1306 : : BufferAccessStrategy strategy)
1307 : : {
1308 : : ReadBuffersOperation operation;
1309 : : Buffer buffer;
1310 : : int flags;
1311 : : char persistence;
1312 : :
1313 : : /*
1314 : : * Backward compatibility path, most code should use ExtendBufferedRel()
1315 : : * instead, as acquiring the extension lock inside ExtendBufferedRel()
1316 : : * scales a lot better.
1317 : : */
1318 [ + + ]: 61773371 : if (unlikely(blockNum == P_NEW))
1319 : : {
1320 : 262 : uint32 flags = EB_SKIP_EXTENSION_LOCK;
1321 : :
1322 : : /*
1323 : : * Since no-one else can be looking at the page contents yet, there is
1324 : : * no difference between an exclusive lock and a cleanup-strength
1325 : : * lock.
1326 : : */
1327 [ + - - + ]: 262 : if (mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK)
711 tmunro@postgresql.or 1328 :UBC 0 : flags |= EB_LOCK_FIRST;
1329 : :
711 tmunro@postgresql.or 1330 :CBC 262 : return ExtendBufferedRel(BMR_REL(rel), forkNum, strategy, flags);
1331 : : }
1332 : :
603 noah@leadboat.com 1333 [ + + ]: 61773109 : if (rel)
1334 : 55974521 : persistence = rel->rd_rel->relpersistence;
1335 : : else
1336 : 5798588 : persistence = smgr_persistence;
1337 : :
711 tmunro@postgresql.or 1338 [ + + + + : 61773109 : if (unlikely(mode == RBM_ZERO_AND_CLEANUP_LOCK ||
+ + ]
1339 : : mode == RBM_ZERO_AND_LOCK))
1340 : : {
1341 : : bool found;
1342 : :
603 noah@leadboat.com 1343 : 332406 : buffer = PinBufferForBlock(rel, smgr, persistence,
1344 : : forkNum, blockNum, strategy, &found);
643 tmunro@postgresql.or 1345 : 332406 : ZeroAndLockBuffer(buffer, mode, found);
711 1346 : 332406 : return buffer;
1347 : : }
1348 : :
1349 : : /*
1350 : : * Signal that we are going to immediately wait. If we're immediately
1351 : : * waiting, there is no benefit in actually executing the IO
1352 : : * asynchronously, it would just add dispatch overhead.
1353 : : */
350 andres@anarazel.de 1354 : 61440703 : flags = READ_BUFFERS_SYNCHRONOUSLY;
711 tmunro@postgresql.or 1355 [ + + ]: 61440703 : if (mode == RBM_ZERO_ON_ERROR)
350 andres@anarazel.de 1356 : 1200063 : flags |= READ_BUFFERS_ZERO_ON_ERROR;
711 tmunro@postgresql.or 1357 : 61440703 : operation.smgr = smgr;
1358 : 61440703 : operation.rel = rel;
603 noah@leadboat.com 1359 : 61440703 : operation.persistence = persistence;
711 tmunro@postgresql.or 1360 : 61440703 : operation.forknum = forkNum;
1361 : 61440703 : operation.strategy = strategy;
1362 [ + + ]: 61440703 : if (StartReadBuffer(&operation,
1363 : : &buffer,
1364 : : blockNum,
1365 : : flags))
1366 : 708517 : WaitReadBuffers(&operation);
1367 : :
1368 : 61440676 : return buffer;
1369 : : }
1370 : :
1371 : : static pg_attribute_always_inline bool
1372 : 65223309 : StartReadBuffersImpl(ReadBuffersOperation *operation,
1373 : : Buffer *buffers,
1374 : : BlockNumber blockNum,
1375 : : int *nblocks,
1376 : : int flags,
1377 : : bool allow_forwarding)
1378 : : {
1379 : 65223309 : int actual_nblocks = *nblocks;
523 andres@anarazel.de 1380 : 65223309 : int maxcombine = 0;
1381 : : bool did_start_io;
1382 : :
359 tmunro@postgresql.or 1383 [ + + - + ]: 65223309 : Assert(*nblocks == 1 || allow_forwarding);
711 1384 [ - + ]: 65223309 : Assert(*nblocks > 0);
1385 [ - + ]: 65223309 : Assert(*nblocks <= MAX_IO_COMBINE_LIMIT);
1386 : :
1387 [ + + ]: 66737178 : for (int i = 0; i < actual_nblocks; ++i)
1388 : : {
1389 : : bool found;
1390 : :
359 1391 [ + + + + ]: 65399051 : if (allow_forwarding && buffers[i] != InvalidBuffer)
1392 : 1669 : {
1393 : : BufferDesc *bufHdr;
1394 : :
1395 : : /*
1396 : : * This is a buffer that was pinned by an earlier call to
1397 : : * StartReadBuffers(), but couldn't be handled in one operation at
1398 : : * that time. The operation was split, and the caller has passed
1399 : : * an already pinned buffer back to us to handle the rest of the
1400 : : * operation. It must continue at the expected block number.
1401 : : */
1402 [ - + ]: 1669 : Assert(BufferGetBlockNumber(buffers[i]) == blockNum + i);
1403 : :
1404 : : /*
1405 : : * It might be an already valid buffer (a hit) that followed the
1406 : : * final contiguous block of an earlier I/O (a miss) marking the
1407 : : * end of it, or a buffer that some other backend has since made
1408 : : * valid by performing the I/O for us, in which case we can handle
1409 : : * it as a hit now. It is safe to check for a BM_VALID flag with
1410 : : * a relaxed load, because we got a fresh view of it while pinning
1411 : : * it in the previous call.
1412 : : *
1413 : : * On the other hand if we don't see BM_VALID yet, it must be an
1414 : : * I/O that was split by the previous call and we need to try to
1415 : : * start a new I/O from this block. We're also racing against any
1416 : : * other backend that might start the I/O or even manage to mark
1417 : : * it BM_VALID after this check, but StartBufferIO() will handle
1418 : : * those cases.
1419 : : */
1420 [ + + ]: 1669 : if (BufferIsLocal(buffers[i]))
1421 : 3 : bufHdr = GetLocalBufferDescriptor(-buffers[i] - 1);
1422 : : else
1423 : 1666 : bufHdr = GetBufferDescriptor(buffers[i] - 1);
59 andres@anarazel.de 1424 [ - + ]:GNC 1669 : Assert(pg_atomic_read_u64(&bufHdr->state) & BM_TAG_VALID);
1425 : 1669 : found = pg_atomic_read_u64(&bufHdr->state) & BM_VALID;
1426 : : }
1427 : : else
1428 : : {
359 tmunro@postgresql.or 1429 :CBC 65397376 : buffers[i] = PinBufferForBlock(operation->rel,
359 tmunro@postgresql.or 1430 :ECB (57237179) : operation->smgr,
359 tmunro@postgresql.or 1431 :CBC 65397382 : operation->persistence,
1432 : : operation->forknum,
1433 : : blockNum + i,
1434 : : operation->strategy,
1435 : : &found);
1436 : : }
1437 : :
711 1438 [ + + ]: 65399045 : if (found)
1439 : : {
1440 : : /*
1441 : : * We have a hit. If it's the first block in the requested range,
1442 : : * we can return it immediately and report that WaitReadBuffers()
1443 : : * does not need to be called. If the initial value of *nblocks
1444 : : * was larger, the caller will have to call again for the rest.
1445 : : */
359 1446 [ + + ]: 63885176 : if (i == 0)
1447 : : {
1448 : 63883505 : *nblocks = 1;
1449 : :
1450 : : #ifdef USE_ASSERT_CHECKING
1451 : :
1452 : : /*
1453 : : * Initialize enough of ReadBuffersOperation to make
1454 : : * CheckReadBuffersOperation() work. Outside of assertions
1455 : : * that's not necessary when no IO is issued.
1456 : : */
350 andres@anarazel.de 1457 : 63883505 : operation->buffers = buffers;
1458 : 63883505 : operation->blocknum = blockNum;
1459 : 63883505 : operation->nblocks = 1;
1460 : 63883505 : operation->nblocks_done = 1;
1461 : 63883505 : CheckReadBuffersOperation(operation, true);
1462 : : #endif
359 tmunro@postgresql.or 1463 : 63883505 : return false;
1464 : : }
1465 : :
1466 : : /*
1467 : : * Otherwise we already have an I/O to perform, but this block
1468 : : * can't be included as it is already valid. Split the I/O here.
1469 : : * There may or may not be more blocks requiring I/O after this
1470 : : * one, we haven't checked, but they can't be contiguous with this
1471 : : * one in the way. We'll leave this buffer pinned, forwarding it
1472 : : * to the next call, avoiding the need to unpin it here and re-pin
1473 : : * it in the next call.
1474 : : */
1475 : 1671 : actual_nblocks = i;
711 1476 : 1671 : break;
1477 : : }
1478 : : else
1479 : : {
1480 : : /*
1481 : : * Check how many blocks we can cover with the same IO. The smgr
1482 : : * implementation might e.g. be limited due to a segment boundary.
1483 : : */
523 andres@anarazel.de 1484 [ + + + + ]: 1513869 : if (i == 0 && actual_nblocks > 1)
1485 : : {
1486 : 35405 : maxcombine = smgrmaxcombine(operation->smgr,
1487 : : operation->forknum,
1488 : : blockNum);
1489 [ - + ]: 35405 : if (unlikely(maxcombine < actual_nblocks))
1490 : : {
523 andres@anarazel.de 1491 [ # # ]:UBC 0 : elog(DEBUG2, "limiting nblocks at %u from %u to %u",
1492 : : blockNum, actual_nblocks, maxcombine);
1493 : 0 : actual_nblocks = maxcombine;
1494 : : }
1495 : : }
1496 : : }
1497 : : }
711 tmunro@postgresql.or 1498 :CBC 1339798 : *nblocks = actual_nblocks;
1499 : :
1500 : : /* Populate information needed for I/O. */
1501 : 1339798 : operation->buffers = buffers;
1502 : 1339798 : operation->blocknum = blockNum;
1503 : 1339798 : operation->flags = flags;
1504 : 1339798 : operation->nblocks = actual_nblocks;
350 andres@anarazel.de 1505 : 1339798 : operation->nblocks_done = 0;
1506 : 1339798 : pgaio_wref_clear(&operation->io_wref);
1507 : :
1508 : : /*
1509 : : * When using AIO, start the IO in the background. If not, issue prefetch
1510 : : * requests if desired by the caller.
1511 : : *
1512 : : * The reason we have a dedicated path for IOMETHOD_SYNC here is to
1513 : : * de-risk the introduction of AIO somewhat. It's a large architectural
1514 : : * change, with lots of chances for unanticipated performance effects.
1515 : : *
1516 : : * Use of IOMETHOD_SYNC already leads to not actually performing IO
1517 : : * asynchronously, but without the check here we'd execute IO earlier than
1518 : : * we used to. Eventually this IOMETHOD_SYNC specific path should go away.
1519 : : */
1520 [ + + ]: 1339798 : if (io_method != IOMETHOD_SYNC)
1521 : : {
1522 : : /*
1523 : : * Try to start IO asynchronously. It's possible that no IO needs to
1524 : : * be started, if another backend already performed the IO.
1525 : : *
1526 : : * Note that if an IO is started, it might not cover the entire
1527 : : * requested range, e.g. because an intermediary block has been read
1528 : : * in by another backend. In that case any "trailing" buffers we
1529 : : * already pinned above will be "forwarded" by read_stream.c to the
1530 : : * next call to StartReadBuffers().
1531 : : *
1532 : : * This is signalled to the caller by decrementing *nblocks *and*
1533 : : * reducing operation->nblocks. The latter is done here, but not below
1534 : : * WaitReadBuffers(), as in WaitReadBuffers() we can't "shorten" the
1535 : : * overall read size anymore, we need to retry until done in its
1536 : : * entirety or until failed.
1537 : : */
1538 : 1338728 : did_start_io = AsyncReadBuffers(operation, nblocks);
1539 : :
1540 : 1338713 : operation->nblocks = *nblocks;
1541 : : }
1542 : : else
1543 : : {
1544 : 1070 : operation->flags |= READ_BUFFERS_SYNCHRONOUSLY;
1545 : :
1546 [ + + ]: 1070 : if (flags & READ_BUFFERS_ISSUE_ADVICE)
1547 : : {
1548 : : /*
1549 : : * In theory we should only do this if PinBufferForBlock() had to
1550 : : * allocate new buffers above. That way, if two calls to
1551 : : * StartReadBuffers() were made for the same blocks before
1552 : : * WaitReadBuffers(), only the first would issue the advice.
1553 : : * That'd be a better simulation of true asynchronous I/O, which
1554 : : * would only start the I/O once, but isn't done here for
1555 : : * simplicity.
1556 : : */
1557 : 2 : smgrprefetch(operation->smgr,
1558 : : operation->forknum,
1559 : : blockNum,
1560 : : actual_nblocks);
1561 : : }
1562 : :
1563 : : /*
1564 : : * Indicate that WaitReadBuffers() should be called. WaitReadBuffers()
1565 : : * will initiate the necessary IO.
1566 : : */
1567 : 1070 : did_start_io = true;
1568 : : }
1569 : :
1570 : 1339783 : CheckReadBuffersOperation(operation, !did_start_io);
1571 : :
1572 : 1339783 : return did_start_io;
1573 : : }
1574 : :
1575 : : /*
1576 : : * Begin reading a range of blocks beginning at blockNum and extending for
1577 : : * *nblocks. *nblocks and the buffers array are in/out parameters. On entry,
1578 : : * the buffers elements covered by *nblocks must hold either InvalidBuffer or
1579 : : * buffers forwarded by an earlier call to StartReadBuffers() that was split
1580 : : * and is now being continued. On return, *nblocks holds the number of blocks
1581 : : * accepted by this operation. If it is less than the original number then
1582 : : * this operation has been split, but buffer elements up to the original
1583 : : * requested size may hold forwarded buffers to be used for a continuing
1584 : : * operation. The caller must either start a new I/O beginning at the block
1585 : : * immediately following the blocks accepted by this call and pass those
1586 : : * buffers back in, or release them if it chooses not to. It shouldn't make
1587 : : * any other use of or assumptions about forwarded buffers.
1588 : : *
1589 : : * If false is returned, no I/O is necessary and the buffers covered by
1590 : : * *nblocks on exit are valid and ready to be accessed. If true is returned,
1591 : : * an I/O has been started, and WaitReadBuffers() must be called with the same
1592 : : * operation object before the buffers covered by *nblocks on exit can be
1593 : : * accessed. Along with the operation object, the caller-supplied array of
1594 : : * buffers must remain valid until WaitReadBuffers() is called, and any
1595 : : * forwarded buffers must also be preserved for a continuing call unless
1596 : : * they are explicitly released.
1597 : : */
1598 : : bool
711 tmunro@postgresql.or 1599 : 1840842 : StartReadBuffers(ReadBuffersOperation *operation,
1600 : : Buffer *buffers,
1601 : : BlockNumber blockNum,
1602 : : int *nblocks,
1603 : : int flags)
1604 : : {
359 1605 : 1840842 : return StartReadBuffersImpl(operation, buffers, blockNum, nblocks, flags,
1606 : : true /* expect forwarded buffers */ );
1607 : : }
1608 : :
1609 : : /*
1610 : : * Single block version of the StartReadBuffers(). This might save a few
1611 : : * instructions when called from another translation unit, because it is
1612 : : * specialized for nblocks == 1.
1613 : : *
1614 : : * This version does not support "forwarded" buffers: they cannot be created
1615 : : * by reading only one block and *buffer is ignored on entry.
1616 : : */
1617 : : bool
711 1618 : 63382467 : StartReadBuffer(ReadBuffersOperation *operation,
1619 : : Buffer *buffer,
1620 : : BlockNumber blocknum,
1621 : : int flags)
1622 : : {
1623 : 63382467 : int nblocks = 1;
1624 : : bool result;
1625 : :
359 1626 : 63382467 : result = StartReadBuffersImpl(operation, buffer, blocknum, &nblocks, flags,
1627 : : false /* single block, no forwarding */ );
711 1628 [ - + ]: 63382452 : Assert(nblocks == 1); /* single block can't be short */
1629 : :
1630 : 63382452 : return result;
1631 : : }
1632 : :
1633 : : /*
1634 : : * Perform sanity checks on the ReadBuffersOperation.
1635 : : */
1636 : : static void
350 andres@anarazel.de 1637 : 67896801 : CheckReadBuffersOperation(ReadBuffersOperation *operation, bool is_complete)
1638 : : {
1639 : : #ifdef USE_ASSERT_CHECKING
1640 [ - + ]: 67896801 : Assert(operation->nblocks_done <= operation->nblocks);
1641 [ + + - + ]: 67896801 : Assert(!is_complete || operation->nblocks == operation->nblocks_done);
1642 : :
1643 [ + + ]: 136316646 : for (int i = 0; i < operation->nblocks; i++)
1644 : : {
1645 : 68419845 : Buffer buffer = operation->buffers[i];
1646 : 68419845 : BufferDesc *buf_hdr = BufferIsLocal(buffer) ?
1647 [ + + ]: 68419845 : GetLocalBufferDescriptor(-buffer - 1) :
1648 : 66864777 : GetBufferDescriptor(buffer - 1);
1649 : :
1650 [ - + ]: 68419845 : Assert(BufferGetBlockNumber(buffer) == operation->blocknum + i);
59 andres@anarazel.de 1651 [ - + ]:GNC 68419845 : Assert(pg_atomic_read_u64(&buf_hdr->state) & BM_TAG_VALID);
1652 : :
350 andres@anarazel.de 1653 [ + + ]:CBC 68419845 : if (i < operation->nblocks_done)
59 andres@anarazel.de 1654 [ - + ]:GNC 65397011 : Assert(pg_atomic_read_u64(&buf_hdr->state) & BM_VALID);
1655 : : }
1656 : : #endif
350 andres@anarazel.de 1657 :CBC 67896801 : }
1658 : :
1659 : : /* helper for ReadBuffersCanStartIO(), to avoid repetition */
1660 : : static inline bool
1661 : 1513895 : ReadBuffersCanStartIOOnce(Buffer buffer, bool nowait)
1662 : : {
711 tmunro@postgresql.or 1663 [ + + ]: 1513895 : if (BufferIsLocal(buffer))
350 andres@anarazel.de 1664 : 8390 : return StartLocalBufferIO(GetLocalBufferDescriptor(-buffer - 1),
1665 : : true, nowait);
1666 : : else
711 tmunro@postgresql.or 1667 : 1505505 : return StartBufferIO(GetBufferDescriptor(buffer - 1), true, nowait);
1668 : : }
1669 : :
1670 : : /*
1671 : : * Helper for AsyncReadBuffers that tries to get the buffer ready for IO.
1672 : : */
1673 : : static inline bool
350 andres@anarazel.de 1674 : 1513895 : ReadBuffersCanStartIO(Buffer buffer, bool nowait)
1675 : : {
1676 : : /*
1677 : : * If this backend currently has staged IO, we need to submit the pending
1678 : : * IO before waiting for the right to issue IO, to avoid the potential for
1679 : : * deadlocks (and, more commonly, unnecessary delays for other backends).
1680 : : */
1681 [ + + + + ]: 1513895 : if (!nowait && pgaio_have_staged())
1682 : : {
1683 [ + - ]: 550 : if (ReadBuffersCanStartIOOnce(buffer, true))
1684 : 550 : return true;
1685 : :
1686 : : /*
1687 : : * Unfortunately StartBufferIO() returning false doesn't allow to
1688 : : * distinguish between the buffer already being valid and IO already
1689 : : * being in progress. Since IO already being in progress is quite
1690 : : * rare, this approach seems fine.
1691 : : */
350 andres@anarazel.de 1692 :UBC 0 : pgaio_submit_staged();
1693 : : }
1694 : :
350 andres@anarazel.de 1695 :CBC 1513345 : return ReadBuffersCanStartIOOnce(buffer, nowait);
1696 : : }
1697 : :
1698 : : /*
1699 : : * Helper for WaitReadBuffers() that processes the results of a readv
1700 : : * operation, raising an error if necessary.
1701 : : */
1702 : : static void
1703 : 1336250 : ProcessReadBuffersResult(ReadBuffersOperation *operation)
1704 : : {
1705 : 1336250 : PgAioReturn *aio_ret = &operation->io_return;
1706 : 1336250 : PgAioResultStatus rs = aio_ret->result.status;
1707 : 1336250 : int newly_read_blocks = 0;
1708 : :
1709 [ - + ]: 1336250 : Assert(pgaio_wref_valid(&operation->io_wref));
1710 [ - + ]: 1336250 : Assert(aio_ret->result.status != PGAIO_RS_UNKNOWN);
1711 : :
1712 : : /*
1713 : : * SMGR reports the number of blocks successfully read as the result of
1714 : : * the IO operation. Thus we can simply add that to ->nblocks_done.
1715 : : */
1716 : :
1717 [ + + ]: 1336250 : if (likely(rs != PGAIO_RS_ERROR))
1718 : 1336207 : newly_read_blocks = aio_ret->result.result;
1719 : :
1720 [ + + + + ]: 1336250 : if (rs == PGAIO_RS_ERROR || rs == PGAIO_RS_WARNING)
1721 [ + + ]: 67 : pgaio_result_report(aio_ret->result, &aio_ret->target_data,
1722 : : rs == PGAIO_RS_ERROR ? ERROR : WARNING);
1723 [ + + ]: 1336183 : else if (aio_ret->result.status == PGAIO_RS_PARTIAL)
1724 : : {
1725 : : /*
1726 : : * We'll retry, so we just emit a debug message to the server log (or
1727 : : * not even that in prod scenarios).
1728 : : */
1729 : 15 : pgaio_result_report(aio_ret->result, &aio_ret->target_data, DEBUG1);
1730 [ + - ]: 15 : elog(DEBUG3, "partial read, will retry");
1731 : : }
1732 : :
1733 [ - + ]: 1336207 : Assert(newly_read_blocks > 0);
1734 [ - + ]: 1336207 : Assert(newly_read_blocks <= MAX_IO_COMBINE_LIMIT);
1735 : :
1736 : 1336207 : operation->nblocks_done += newly_read_blocks;
1737 : :
1738 [ - + ]: 1336207 : Assert(operation->nblocks_done <= operation->nblocks);
1739 : 1336207 : }
1740 : :
1741 : : void
711 tmunro@postgresql.or 1742 : 1336236 : WaitReadBuffers(ReadBuffersOperation *operation)
1743 : : {
350 andres@anarazel.de 1744 : 1336236 : PgAioReturn *aio_ret = &operation->io_return;
1745 : : IOContext io_context;
1746 : : IOObject io_object;
1747 : :
1748 [ + + ]: 1336236 : if (operation->persistence == RELPERSISTENCE_TEMP)
1749 : : {
711 tmunro@postgresql.or 1750 : 1502 : io_context = IOCONTEXT_NORMAL;
1751 : 1502 : io_object = IOOBJECT_TEMP_RELATION;
1752 : : }
1753 : : else
1754 : : {
1755 : 1334734 : io_context = IOContextForStrategy(operation->strategy);
1756 : 1334734 : io_object = IOOBJECT_RELATION;
1757 : : }
1758 : :
1759 : : /*
1760 : : * If we get here without an IO operation having been issued, the
1761 : : * io_method == IOMETHOD_SYNC path must have been used. Otherwise the
1762 : : * caller should not have called WaitReadBuffers().
1763 : : *
1764 : : * In the case of IOMETHOD_SYNC, we start - as we used to before the
1765 : : * introducing of AIO - the IO in WaitReadBuffers(). This is done as part
1766 : : * of the retry logic below, no extra code is required.
1767 : : *
1768 : : * This path is expected to eventually go away.
1769 : : */
350 andres@anarazel.de 1770 [ + + + - ]: 1336236 : if (!pgaio_wref_valid(&operation->io_wref) && io_method != IOMETHOD_SYNC)
350 andres@anarazel.de 1771 [ # # ]:UBC 0 : elog(ERROR, "waiting for read operation that didn't read");
1772 : :
1773 : : /*
1774 : : * To handle partial reads, and IOMETHOD_SYNC, we re-issue IO until we're
1775 : : * done. We may need multiple retries, not just because we could get
1776 : : * multiple partial reads, but also because some of the remaining
1777 : : * to-be-read buffers may have been read in by other backends, limiting
1778 : : * the IO size.
1779 : : */
1780 : : while (true)
711 tmunro@postgresql.or 1781 :CBC 1085 : {
1782 : : int ignored_nblocks_progress;
1783 : :
350 andres@anarazel.de 1784 : 1337321 : CheckReadBuffersOperation(operation, false);
1785 : :
1786 : : /*
1787 : : * If there is an IO associated with the operation, we may need to
1788 : : * wait for it.
1789 : : */
1790 [ + + ]: 1337321 : if (pgaio_wref_valid(&operation->io_wref))
1791 : : {
1792 : : /*
1793 : : * Track the time spent waiting for the IO to complete. As
1794 : : * tracking a wait even if we don't actually need to wait
1795 : : *
1796 : : * a) is not cheap, due to the timestamping overhead
1797 : : *
1798 : : * b) reports some time as waiting, even if we never waited
1799 : : *
1800 : : * we first check if we already know the IO is complete.
1801 : : */
1802 [ + + ]: 1336251 : if (aio_ret->result.status == PGAIO_RS_UNKNOWN &&
1803 [ + + ]: 617942 : !pgaio_wref_check_done(&operation->io_wref))
1804 : 271628 : {
1805 : 271629 : instr_time io_start = pgstat_prepare_io_time(track_io_timing);
1806 : :
1807 : 271629 : pgaio_wref_wait(&operation->io_wref);
1808 : :
1809 : : /*
1810 : : * The IO operation itself was already counted earlier, in
1811 : : * AsyncReadBuffers(), this just accounts for the wait time.
1812 : : */
1813 : 271628 : pgstat_count_io_op_time(io_object, io_context, IOOP_READ,
1814 : : io_start, 0, 0);
1815 : : }
1816 : : else
1817 : : {
1818 [ - + ]: 1064622 : Assert(pgaio_wref_check_done(&operation->io_wref));
1819 : : }
1820 : :
1821 : : /*
1822 : : * We now are sure the IO completed. Check the results. This
1823 : : * includes reporting on errors if there were any.
1824 : : */
1825 : 1336250 : ProcessReadBuffersResult(operation);
1826 : : }
1827 : :
1828 : : /*
1829 : : * Most of the time, the one IO we already started, will read in
1830 : : * everything. But we need to deal with partial reads and buffers not
1831 : : * needing IO anymore.
1832 : : */
1833 [ + + ]: 1337277 : if (operation->nblocks_done == operation->nblocks)
1834 : 1336192 : break;
1835 : :
1836 [ - + ]: 1085 : CHECK_FOR_INTERRUPTS();
1837 : :
1838 : : /*
1839 : : * This may only complete the IO partially, either because some
1840 : : * buffers were already valid, or because of a partial read.
1841 : : *
1842 : : * NB: In contrast to after the AsyncReadBuffers() call in
1843 : : * StartReadBuffers(), we do *not* reduce
1844 : : * ReadBuffersOperation->nblocks here, callers expect the full
1845 : : * operation to be completed at this point (as more operations may
1846 : : * have been queued).
1847 : : */
1848 : 1085 : AsyncReadBuffers(operation, &ignored_nblocks_progress);
1849 : : }
1850 : :
1851 : 1336192 : CheckReadBuffersOperation(operation, true);
1852 : :
1853 : : /* NB: READ_DONE tracepoint was already executed in completion callback */
1854 : 1336192 : }
1855 : :
1856 : : /*
1857 : : * Initiate IO for the ReadBuffersOperation
1858 : : *
1859 : : * This function only starts a single IO at a time. The size of the IO may be
1860 : : * limited to below the to-be-read blocks, if one of the buffers has
1861 : : * concurrently been read in. If the first to-be-read buffer is already valid,
1862 : : * no IO will be issued.
1863 : : *
1864 : : * To support retries after partial reads, the first operation->nblocks_done
1865 : : * buffers are skipped.
1866 : : *
1867 : : * On return *nblocks_progress is updated to reflect the number of buffers
1868 : : * affected by the call. If the first buffer is valid, *nblocks_progress is
1869 : : * set to 1 and operation->nblocks_done is incremented.
1870 : : *
1871 : : * Returns true if IO was initiated, false if no IO was necessary.
1872 : : */
1873 : : static bool
1874 : 1339813 : AsyncReadBuffers(ReadBuffersOperation *operation, int *nblocks_progress)
1875 : : {
1876 : 1339813 : Buffer *buffers = &operation->buffers[0];
1877 : 1339813 : int flags = operation->flags;
1878 : 1339813 : BlockNumber blocknum = operation->blocknum;
1879 : 1339813 : ForkNumber forknum = operation->forknum;
1880 : 1339813 : char persistence = operation->persistence;
1881 : 1339813 : int16 nblocks_done = operation->nblocks_done;
1882 : 1339813 : Buffer *io_buffers = &operation->buffers[nblocks_done];
1883 : 1339813 : int io_buffers_len = 0;
1884 : : PgAioHandle *ioh;
1885 : 1339813 : uint32 ioh_flags = 0;
1886 : : void *io_pages[MAX_IO_COMBINE_LIMIT];
1887 : : IOContext io_context;
1888 : : IOObject io_object;
1889 : : bool did_start_io;
1890 : :
1891 : : /*
1892 : : * When this IO is executed synchronously, either because the caller will
1893 : : * immediately block waiting for the IO or because IOMETHOD_SYNC is used,
1894 : : * the AIO subsystem needs to know.
1895 : : */
1896 [ + + ]: 1339813 : if (flags & READ_BUFFERS_SYNCHRONOUSLY)
1897 : 710295 : ioh_flags |= PGAIO_HF_SYNCHRONOUS;
1898 : :
1899 [ + + ]: 1339813 : if (persistence == RELPERSISTENCE_TEMP)
1900 : : {
1901 : 1796 : io_context = IOCONTEXT_NORMAL;
1902 : 1796 : io_object = IOOBJECT_TEMP_RELATION;
1903 : 1796 : ioh_flags |= PGAIO_HF_REFERENCES_LOCAL;
1904 : : }
1905 : : else
1906 : : {
1907 : 1338017 : io_context = IOContextForStrategy(operation->strategy);
1908 : 1338017 : io_object = IOOBJECT_RELATION;
1909 : : }
1910 : :
1911 : : /*
1912 : : * If zero_damaged_pages is enabled, add the READ_BUFFERS_ZERO_ON_ERROR
1913 : : * flag. The reason for that is that, hopefully, zero_damaged_pages isn't
1914 : : * set globally, but on a per-session basis. The completion callback,
1915 : : * which may be run in other processes, e.g. in IO workers, may have a
1916 : : * different value of the zero_damaged_pages GUC.
1917 : : *
1918 : : * XXX: We probably should eventually use a different flag for
1919 : : * zero_damaged_pages, so we can report different log levels / error codes
1920 : : * for zero_damaged_pages and ZERO_ON_ERROR.
1921 : : */
1922 [ + + ]: 1339813 : if (zero_damaged_pages)
1923 : 24 : flags |= READ_BUFFERS_ZERO_ON_ERROR;
1924 : :
1925 : : /*
1926 : : * For the same reason as with zero_damaged_pages we need to use this
1927 : : * backend's ignore_checksum_failure value.
1928 : : */
1929 [ + + ]: 1339813 : if (ignore_checksum_failure)
1930 : 12 : flags |= READ_BUFFERS_IGNORE_CHECKSUM_FAILURES;
1931 : :
1932 : :
1933 : : /*
1934 : : * To be allowed to report stats in the local completion callback we need
1935 : : * to prepare to report stats now. This ensures we can safely report the
1936 : : * checksum failure even in a critical section.
1937 : : */
1938 : 1339813 : pgstat_prepare_report_checksum_failure(operation->smgr->smgr_rlocator.locator.dbOid);
1939 : :
1940 : : /*
1941 : : * Get IO handle before ReadBuffersCanStartIO(), as pgaio_io_acquire()
1942 : : * might block, which we don't want after setting IO_IN_PROGRESS.
1943 : : *
1944 : : * If we need to wait for IO before we can get a handle, submit
1945 : : * already-staged IO first, so that other backends don't need to wait.
1946 : : * There wouldn't be a deadlock risk, as pgaio_io_acquire() just needs to
1947 : : * wait for already submitted IO, which doesn't require additional locks,
1948 : : * but it could still cause undesirable waits.
1949 : : *
1950 : : * A secondary benefit is that this would allow us to measure the time in
1951 : : * pgaio_io_acquire() without causing undue timer overhead in the common,
1952 : : * non-blocking, case. However, currently the pgstats infrastructure
1953 : : * doesn't really allow that, as it a) asserts that an operation can't
1954 : : * have time without operations b) doesn't have an API to report
1955 : : * "accumulated" time.
1956 : : */
1957 : 1339813 : ioh = pgaio_io_acquire_nb(CurrentResourceOwner, &operation->io_return);
1958 [ + + ]: 1339813 : if (unlikely(!ioh))
1959 : : {
1960 : 3456 : pgaio_submit_staged();
1961 : :
1962 : 3456 : ioh = pgaio_io_acquire(CurrentResourceOwner, &operation->io_return);
1963 : : }
1964 : :
1965 : : /*
1966 : : * Check if we can start IO on the first to-be-read buffer.
1967 : : *
1968 : : * If an I/O is already in progress in another backend, we want to wait
1969 : : * for the outcome: either done, or something went wrong and we will
1970 : : * retry.
1971 : : */
1972 [ + + ]: 1339813 : if (!ReadBuffersCanStartIO(buffers[nblocks_done], false))
1973 : : {
1974 : : /*
1975 : : * Someone else has already completed this block, we're done.
1976 : : *
1977 : : * When IO is necessary, ->nblocks_done is updated in
1978 : : * ProcessReadBuffersResult(), but that is not called if no IO is
1979 : : * necessary. Thus update here.
1980 : : */
1981 : 3247 : operation->nblocks_done += 1;
1982 : 3247 : *nblocks_progress = 1;
1983 : :
1984 : 3247 : pgaio_io_release(ioh);
1985 : 3247 : pgaio_wref_clear(&operation->io_wref);
1986 : 3247 : did_start_io = false;
1987 : :
1988 : : /*
1989 : : * Report and track this as a 'hit' for this backend, even though it
1990 : : * must have started out as a miss in PinBufferForBlock(). The other
1991 : : * backend will track this as a 'read'.
1992 : : */
1993 : : TRACE_POSTGRESQL_BUFFER_READ_DONE(forknum, blocknum + operation->nblocks_done,
1994 : : operation->smgr->smgr_rlocator.locator.spcOid,
1995 : : operation->smgr->smgr_rlocator.locator.dbOid,
1996 : : operation->smgr->smgr_rlocator.locator.relNumber,
1997 : : operation->smgr->smgr_rlocator.backend,
1998 : : true);
1999 : :
2000 [ - + ]: 3247 : if (persistence == RELPERSISTENCE_TEMP)
350 andres@anarazel.de 2001 :UBC 0 : pgBufferUsage.local_blks_hit += 1;
2002 : : else
350 andres@anarazel.de 2003 :CBC 3247 : pgBufferUsage.shared_blks_hit += 1;
2004 : :
2005 [ + - ]: 3247 : if (operation->rel)
2006 [ - + - - : 3247 : pgstat_count_buffer_hit(operation->rel);
+ - ]
2007 : :
2008 : 3247 : pgstat_count_io_op(io_object, io_context, IOOP_HIT, 1, 0);
2009 : :
2010 [ + + ]: 3247 : if (VacuumCostActive)
2011 : 9 : VacuumCostBalance += VacuumCostPageHit;
2012 : : }
2013 : : else
2014 : : {
2015 : : instr_time io_start;
2016 : :
2017 : : /* We found a buffer that we need to read in. */
2018 [ - + ]: 1336566 : Assert(io_buffers[0] == buffers[nblocks_done]);
2019 : 1336566 : io_pages[0] = BufferGetBlock(buffers[nblocks_done]);
711 tmunro@postgresql.or 2020 : 1336566 : io_buffers_len = 1;
2021 : :
2022 : : /*
2023 : : * How many neighboring-on-disk blocks can we scatter-read into other
2024 : : * buffers at the same time? In this case we don't wait if we see an
2025 : : * I/O already in progress. We already set BM_IO_IN_PROGRESS for the
2026 : : * head block, so we should get on with that I/O as soon as possible.
2027 : : */
350 andres@anarazel.de 2028 [ + + ]: 1510648 : for (int i = nblocks_done + 1; i < operation->nblocks; i++)
2029 : : {
2030 [ - + ]: 174082 : if (!ReadBuffersCanStartIO(buffers[i], true))
350 andres@anarazel.de 2031 :UBC 0 : break;
2032 : : /* Must be consecutive block numbers. */
350 andres@anarazel.de 2033 [ - + ]:CBC 174082 : Assert(BufferGetBlockNumber(buffers[i - 1]) ==
2034 : : BufferGetBlockNumber(buffers[i]) - 1);
2035 [ - + ]: 174082 : Assert(io_buffers[io_buffers_len] == buffers[i]);
2036 : :
711 tmunro@postgresql.or 2037 : 174082 : io_pages[io_buffers_len++] = BufferGetBlock(buffers[i]);
2038 : : }
2039 : :
2040 : : /* get a reference to wait for in WaitReadBuffers() */
350 andres@anarazel.de 2041 : 1336566 : pgaio_io_get_wref(ioh, &operation->io_wref);
2042 : :
2043 : : /* provide the list of buffers to the completion callbacks */
2044 : 1336566 : pgaio_io_set_handle_data_32(ioh, (uint32 *) io_buffers, io_buffers_len);
2045 : :
2046 [ + + ]: 1336566 : pgaio_io_register_callbacks(ioh,
2047 : : persistence == RELPERSISTENCE_TEMP ?
2048 : : PGAIO_HCB_LOCAL_BUFFER_READV :
2049 : : PGAIO_HCB_SHARED_BUFFER_READV,
2050 : : flags);
2051 : :
2052 : 1336566 : pgaio_io_set_flag(ioh, ioh_flags);
2053 : :
2054 : : /* ---
2055 : : * Even though we're trying to issue IO asynchronously, track the time
2056 : : * in smgrstartreadv():
2057 : : * - if io_method == IOMETHOD_SYNC, we will always perform the IO
2058 : : * immediately
2059 : : * - the io method might not support the IO (e.g. worker IO for a temp
2060 : : * table)
2061 : : * ---
2062 : : */
2063 : 1336566 : io_start = pgstat_prepare_io_time(track_io_timing);
2064 : 1336566 : smgrstartreadv(ioh, operation->smgr, forknum,
2065 : : blocknum + nblocks_done,
2066 : : io_pages, io_buffers_len);
2067 : 1336551 : pgstat_count_io_op_time(io_object, io_context, IOOP_READ,
2068 : 1336551 : io_start, 1, io_buffers_len * BLCKSZ);
2069 : :
360 2070 [ + + ]: 1336551 : if (persistence == RELPERSISTENCE_TEMP)
2071 : 1796 : pgBufferUsage.local_blks_read += io_buffers_len;
2072 : : else
2073 : 1334755 : pgBufferUsage.shared_blks_read += io_buffers_len;
2074 : :
2075 : : /*
2076 : : * Track vacuum cost when issuing IO, not after waiting for it.
2077 : : * Otherwise we could end up issuing a lot of IO in a short timespan,
2078 : : * despite a low cost limit.
2079 : : */
711 tmunro@postgresql.or 2080 [ + + ]: 1336551 : if (VacuumCostActive)
2081 : 13443 : VacuumCostBalance += VacuumCostPageMiss * io_buffers_len;
2082 : :
350 andres@anarazel.de 2083 : 1336551 : *nblocks_progress = io_buffers_len;
2084 : 1336551 : did_start_io = true;
2085 : : }
2086 : :
2087 : 1339798 : return did_start_io;
2088 : : }
2089 : :
2090 : : /*
2091 : : * BufferAlloc -- subroutine for PinBufferForBlock. Handles lookup of a shared
2092 : : * buffer. If no buffer exists already, selects a replacement victim and
2093 : : * evicts the old page, but does NOT read in new page.
2094 : : *
2095 : : * "strategy" can be a buffer replacement strategy object, or NULL for
2096 : : * the default strategy. The selected buffer's usage_count is advanced when
2097 : : * using the default strategy, but otherwise possibly not (see PinBuffer).
2098 : : *
2099 : : * The returned buffer is pinned and is already marked as holding the
2100 : : * desired page. If it already did have the desired page, *foundPtr is
2101 : : * set true. Otherwise, *foundPtr is set false.
2102 : : *
2103 : : * io_context is passed as an output parameter to avoid calling
2104 : : * IOContextForStrategy() when there is a shared buffers hit and no IO
2105 : : * statistics need be captured.
2106 : : *
2107 : : * No locks are held either at entry or exit.
2108 : : */
2109 : : static pg_attribute_always_inline BufferDesc *
5555 rhaas@postgresql.org 2110 : 64190842 : BufferAlloc(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
2111 : : BlockNumber blockNum,
2112 : : BufferAccessStrategy strategy,
2113 : : bool *foundPtr, IOContext io_context)
2114 : : {
2115 : : BufferTag newTag; /* identity of requested block */
2116 : : uint32 newHash; /* hash value for newTag */
2117 : : LWLock *newPartitionLock; /* buffer partition lock for it */
2118 : : int existing_buf_id;
2119 : : Buffer victim_buffer;
2120 : : BufferDesc *victim_buf_hdr;
2121 : : uint64 victim_buf_state;
59 andres@anarazel.de 2122 :GNC 64190842 : uint64 set_bits = 0;
2123 : :
2124 : : /* Make sure we will have room to remember the buffer pin */
858 heikki.linnakangas@i 2125 :CBC 64190842 : ResourceOwnerEnlarge(CurrentResourceOwner);
2126 : 64190842 : ReservePrivateRefCountEntry();
2127 : :
2128 : : /* create a tag so we can lookup the buffer */
1327 rhaas@postgresql.org 2129 : 64190842 : InitBufferTag(&newTag, &smgr->smgr_rlocator.locator, forkNum, blockNum);
2130 : :
2131 : : /* determine its hash code and partition lock ID */
7175 tgl@sss.pgh.pa.us 2132 : 64190842 : newHash = BufTableHashCode(&newTag);
2133 : 64190842 : newPartitionLock = BufMappingPartitionLock(newHash);
2134 : :
2135 : : /* see if the block is in the buffer pool already */
2136 : 64190842 : LWLockAcquire(newPartitionLock, LW_SHARED);
1075 andres@anarazel.de 2137 : 64190842 : existing_buf_id = BufTableLookup(&newTag, newHash);
2138 [ + + ]: 64190842 : if (existing_buf_id >= 0)
2139 : : {
2140 : : BufferDesc *buf;
2141 : : bool valid;
2142 : :
2143 : : /*
2144 : : * Found it. Now, pin the buffer so no one can steal it from the
2145 : : * buffer pool, and check to see if the correct data has been loaded
2146 : : * into the buffer.
2147 : : */
2148 : 62393331 : buf = GetBufferDescriptor(existing_buf_id);
2149 : :
158 andres@anarazel.de 2150 :GNC 62393331 : valid = PinBuffer(buf, strategy, false);
2151 : :
2152 : : /* Can release the mapping lock as soon as we've pinned it */
7175 tgl@sss.pgh.pa.us 2153 :CBC 62393331 : LWLockRelease(newPartitionLock);
2154 : :
3133 peter_e@gmx.net 2155 : 62393331 : *foundPtr = true;
2156 : :
7681 tgl@sss.pgh.pa.us 2157 [ + + ]: 62393331 : if (!valid)
2158 : : {
2159 : : /*
2160 : : * We can only get here if (a) someone else is still reading in
2161 : : * the page, (b) a previous read attempt failed, or (c) someone
2162 : : * called StartReadBuffers() but not yet WaitReadBuffers().
2163 : : */
711 tmunro@postgresql.or 2164 : 2975 : *foundPtr = false;
2165 : : }
2166 : :
10057 bruce@momjian.us 2167 : 62393331 : return buf;
2168 : : }
2169 : :
2170 : : /*
2171 : : * Didn't find it in the buffer pool. We'll have to initialize a new
2172 : : * buffer. Remember to unlock the mapping lock while doing the work.
2173 : : */
7175 tgl@sss.pgh.pa.us 2174 : 1797511 : LWLockRelease(newPartitionLock);
2175 : :
2176 : : /*
2177 : : * Acquire a victim buffer. Somebody else might try to do the same, we
2178 : : * don't hold any conflicting locks. If so we'll have to undo our work
2179 : : * later.
2180 : : */
1075 andres@anarazel.de 2181 : 1797511 : victim_buffer = GetVictimBuffer(strategy, io_context);
2182 : 1797511 : victim_buf_hdr = GetBufferDescriptor(victim_buffer - 1);
2183 : :
2184 : : /*
2185 : : * Try to make a hashtable entry for the buffer under its new tag. If
2186 : : * somebody else inserted another buffer for the tag, we'll release the
2187 : : * victim buffer we acquired and use the already inserted one.
2188 : : */
2189 : 1797511 : LWLockAcquire(newPartitionLock, LW_EXCLUSIVE);
2190 : 1797511 : existing_buf_id = BufTableInsert(&newTag, newHash, victim_buf_hdr->buf_id);
2191 [ + + ]: 1797511 : if (existing_buf_id >= 0)
2192 : : {
2193 : : BufferDesc *existing_buf_hdr;
2194 : : bool valid;
2195 : :
2196 : : /*
2197 : : * Got a collision. Someone has already done what we were about to do.
2198 : : * We'll just handle this as if it were found in the buffer pool in
2199 : : * the first place. First, give up the buffer we were planning to
2200 : : * use.
2201 : : *
2202 : : * We could do this after releasing the partition lock, but then we'd
2203 : : * have to call ResourceOwnerEnlarge() & ReservePrivateRefCountEntry()
2204 : : * before acquiring the lock, for the rare case of such a collision.
2205 : : */
2206 : 676 : UnpinBuffer(victim_buf_hdr);
2207 : :
2208 : : /* remaining code should match code at top of routine */
2209 : :
2210 : 676 : existing_buf_hdr = GetBufferDescriptor(existing_buf_id);
2211 : :
158 andres@anarazel.de 2212 :GNC 676 : valid = PinBuffer(existing_buf_hdr, strategy, false);
2213 : :
2214 : : /* Can release the mapping lock as soon as we've pinned it */
1075 andres@anarazel.de 2215 :CBC 676 : LWLockRelease(newPartitionLock);
2216 : :
2217 : 676 : *foundPtr = true;
2218 : :
2219 [ + + ]: 676 : if (!valid)
2220 : : {
2221 : : /*
2222 : : * We can only get here if (a) someone else is still reading in
2223 : : * the page, (b) a previous read attempt failed, or (c) someone
2224 : : * called StartReadBuffers() but not yet WaitReadBuffers().
2225 : : */
711 tmunro@postgresql.or 2226 : 339 : *foundPtr = false;
2227 : : }
2228 : :
1075 andres@anarazel.de 2229 : 676 : return existing_buf_hdr;
2230 : : }
2231 : :
2232 : : /*
2233 : : * Need to lock the buffer header too in order to change its tag.
2234 : : */
2235 : 1796835 : victim_buf_state = LockBufHdr(victim_buf_hdr);
2236 : :
2237 : : /* some sanity checks while we hold the buffer header lock */
2238 [ - + ]: 1796835 : Assert(BUF_STATE_GET_REFCOUNT(victim_buf_state) == 1);
2239 [ - + ]: 1796835 : Assert(!(victim_buf_state & (BM_TAG_VALID | BM_VALID | BM_DIRTY | BM_IO_IN_PROGRESS)));
2240 : :
2241 : 1796835 : victim_buf_hdr->tag = newTag;
2242 : :
2243 : : /*
2244 : : * Make sure BM_PERMANENT is set for buffers that must be written at every
2245 : : * checkpoint. Unlogged buffers only need to be written at shutdown
2246 : : * checkpoints, except for their "init" forks, which need to be treated
2247 : : * just like permanent relations.
2248 : : */
129 andres@anarazel.de 2249 :GNC 1796835 : set_bits |= BM_TAG_VALID | BUF_USAGECOUNT_ONE;
3288 rhaas@postgresql.org 2250 [ + + - + ]:CBC 1796835 : if (relpersistence == RELPERSISTENCE_PERMANENT || forkNum == INIT_FORKNUM)
129 andres@anarazel.de 2251 :GNC 1796478 : set_bits |= BM_PERMANENT;
2252 : :
2253 : 1796835 : UnlockBufHdrExt(victim_buf_hdr, victim_buf_state,
2254 : : set_bits, 0, 0);
2255 : :
7175 tgl@sss.pgh.pa.us 2256 :CBC 1796835 : LWLockRelease(newPartitionLock);
2257 : :
2258 : : /*
2259 : : * Buffer contents are currently invalid.
2260 : : */
711 tmunro@postgresql.or 2261 : 1796835 : *foundPtr = false;
2262 : :
1075 andres@anarazel.de 2263 : 1796835 : return victim_buf_hdr;
2264 : : }
2265 : :
2266 : : /*
2267 : : * InvalidateBuffer -- mark a shared buffer invalid.
2268 : : *
2269 : : * The buffer header spinlock must be held at entry. We drop it before
2270 : : * returning. (This is sane because the caller must have locked the
2271 : : * buffer in order to be sure it should be dropped.)
2272 : : *
2273 : : * This is used only in contexts such as dropping a relation. We assume
2274 : : * that no other backend could possibly be interested in using the page,
2275 : : * so the only reason the buffer might be pinned is if someone else is
2276 : : * trying to write it out. We have to let them finish before we can
2277 : : * reclaim the buffer.
2278 : : *
2279 : : * The buffer could get reclaimed by someone else while we are waiting
2280 : : * to acquire the necessary locks; if so, don't mess it up.
2281 : : */
2282 : : static void
3772 rhaas@postgresql.org 2283 : 107178 : InvalidateBuffer(BufferDesc *buf)
2284 : : {
2285 : : BufferTag oldTag;
2286 : : uint32 oldHash; /* hash value for oldTag */
2287 : : LWLock *oldPartitionLock; /* buffer partition lock for it */
2288 : : uint32 oldFlags;
2289 : : uint64 buf_state;
2290 : :
2291 : : /* Save the original buffer tag before dropping the spinlock */
7681 tgl@sss.pgh.pa.us 2292 : 107178 : oldTag = buf->tag;
2293 : :
129 andres@anarazel.de 2294 :GNC 107178 : UnlockBufHdr(buf);
2295 : :
2296 : : /*
2297 : : * Need to compute the old tag's hashcode and partition lock ID. XXX is it
2298 : : * worth storing the hashcode in BufferDesc so we need not recompute it
2299 : : * here? Probably not.
2300 : : */
7175 tgl@sss.pgh.pa.us 2301 :CBC 107178 : oldHash = BufTableHashCode(&oldTag);
2302 : 107178 : oldPartitionLock = BufMappingPartitionLock(oldHash);
2303 : :
7681 2304 : 107179 : retry:
2305 : :
2306 : : /*
2307 : : * Acquire exclusive mapping lock in preparation for changing the buffer's
2308 : : * association.
2309 : : */
7175 2310 : 107179 : LWLockAcquire(oldPartitionLock, LW_EXCLUSIVE);
2311 : :
2312 : : /* Re-lock the buffer header */
3626 andres@anarazel.de 2313 : 107179 : buf_state = LockBufHdr(buf);
2314 : :
2315 : : /* If it's changed while we were waiting for lock, do nothing */
1327 rhaas@postgresql.org 2316 [ + + ]: 107179 : if (!BufferTagsEqual(&buf->tag, &oldTag))
2317 : : {
129 andres@anarazel.de 2318 :GNC 1 : UnlockBufHdr(buf);
7175 tgl@sss.pgh.pa.us 2319 :GBC 1 : LWLockRelease(oldPartitionLock);
7681 2320 : 1 : return;
2321 : : }
2322 : :
2323 : : /*
2324 : : * We assume the reason for it to be pinned is that either we were
2325 : : * asynchronously reading the page in before erroring out or someone else
2326 : : * is flushing the page out. Wait for the IO to finish. (This could be
2327 : : * an infinite loop if the refcount is messed up... it would be nice to
2328 : : * time out after awhile, but there seems no way to be sure how many loops
2329 : : * may be needed. Note that if the other guy has pinned the buffer but
2330 : : * not yet done StartBufferIO, WaitIO will fall through and we'll
2331 : : * effectively be busy-looping here.)
2332 : : */
3626 andres@anarazel.de 2333 [ + + ]:CBC 107178 : if (BUF_STATE_GET_REFCOUNT(buf_state) != 0)
2334 : : {
129 andres@anarazel.de 2335 :GNC 1 : UnlockBufHdr(buf);
7175 tgl@sss.pgh.pa.us 2336 :GBC 1 : LWLockRelease(oldPartitionLock);
2337 : : /* safety check: should definitely not be our *own* pin */
3868 andres@anarazel.de 2338 [ - + ]: 1 : if (GetPrivateRefCount(BufferDescriptorGetBuffer(buf)) > 0)
7667 tgl@sss.pgh.pa.us 2339 [ # # ]:UBC 0 : elog(ERROR, "buffer is pinned in InvalidateBuffer");
7681 tgl@sss.pgh.pa.us 2340 :GBC 1 : WaitIO(buf);
2341 : 1 : goto retry;
2342 : : }
2343 : :
2344 : : /*
2345 : : * An invalidated buffer should not have any backends waiting to lock the
2346 : : * buffer, therefore BM_LOCK_WAKE_IN_PROGRESS should not be set.
2347 : : */
59 andres@anarazel.de 2348 [ - + ]:GNC 107177 : Assert(!(buf_state & BM_LOCK_WAKE_IN_PROGRESS));
2349 : :
2350 : : /*
2351 : : * Clear out the buffer's tag and flags. We must do this to ensure that
2352 : : * linear scans of the buffer array don't think the buffer is valid.
2353 : : */
3626 andres@anarazel.de 2354 :CBC 107177 : oldFlags = buf_state & BUF_FLAG_MASK;
1327 rhaas@postgresql.org 2355 : 107177 : ClearBufferTag(&buf->tag);
2356 : :
129 andres@anarazel.de 2357 :GNC 107177 : UnlockBufHdrExt(buf, buf_state,
2358 : : 0,
2359 : : BUF_FLAG_MASK | BUF_USAGECOUNT_MASK,
2360 : : 0);
2361 : :
2362 : : /*
2363 : : * Remove the buffer from the lookup hashtable, if it was in there.
2364 : : */
7681 tgl@sss.pgh.pa.us 2365 [ + - ]:CBC 107177 : if (oldFlags & BM_TAG_VALID)
7175 2366 : 107177 : BufTableDelete(&oldTag, oldHash);
2367 : :
2368 : : /*
2369 : : * Done with mapping lock.
2370 : : */
2371 : 107177 : LWLockRelease(oldPartitionLock);
2372 : : }
2373 : :
2374 : : /*
2375 : : * Helper routine for GetVictimBuffer()
2376 : : *
2377 : : * Needs to be called on a buffer with a valid tag, pinned, but without the
2378 : : * buffer header spinlock held.
2379 : : *
2380 : : * Returns true if the buffer can be reused, in which case the buffer is only
2381 : : * pinned by this backend and marked as invalid, false otherwise.
2382 : : */
2383 : : static bool
1075 andres@anarazel.de 2384 : 1274541 : InvalidateVictimBuffer(BufferDesc *buf_hdr)
2385 : : {
2386 : : uint64 buf_state;
2387 : : uint32 hash;
2388 : : LWLock *partition_lock;
2389 : : BufferTag tag;
2390 : :
2391 [ - + ]: 1274541 : Assert(GetPrivateRefCount(BufferDescriptorGetBuffer(buf_hdr)) == 1);
2392 : :
2393 : : /* have buffer pinned, so it's safe to read tag without lock */
2394 : 1274541 : tag = buf_hdr->tag;
2395 : :
2396 : 1274541 : hash = BufTableHashCode(&tag);
2397 : 1274541 : partition_lock = BufMappingPartitionLock(hash);
2398 : :
2399 : 1274541 : LWLockAcquire(partition_lock, LW_EXCLUSIVE);
2400 : :
2401 : : /* lock the buffer header */
2402 : 1274541 : buf_state = LockBufHdr(buf_hdr);
2403 : :
2404 : : /*
2405 : : * We have the buffer pinned nobody else should have been able to unset
2406 : : * this concurrently.
2407 : : */
2408 [ - + ]: 1274541 : Assert(buf_state & BM_TAG_VALID);
2409 [ - + ]: 1274541 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
2410 [ - + ]: 1274541 : Assert(BufferTagsEqual(&buf_hdr->tag, &tag));
2411 : :
2412 : : /*
2413 : : * If somebody else pinned the buffer since, or even worse, dirtied it,
2414 : : * give up on this buffer: It's clearly in use.
2415 : : */
2416 [ + + + + ]: 1274541 : if (BUF_STATE_GET_REFCOUNT(buf_state) != 1 || (buf_state & BM_DIRTY))
2417 : : {
2418 [ - + ]: 516 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
2419 : :
129 andres@anarazel.de 2420 :GNC 516 : UnlockBufHdr(buf_hdr);
1075 andres@anarazel.de 2421 :CBC 516 : LWLockRelease(partition_lock);
2422 : :
2423 : 516 : return false;
2424 : : }
2425 : :
2426 : : /*
2427 : : * An invalidated buffer should not have any backends waiting to lock the
2428 : : * buffer, therefore BM_LOCK_WAKE_IN_PROGRESS should not be set.
2429 : : */
59 andres@anarazel.de 2430 [ - + ]:GNC 1274025 : Assert(!(buf_state & BM_LOCK_WAKE_IN_PROGRESS));
2431 : :
2432 : : /*
2433 : : * Clear out the buffer's tag and flags and usagecount. This is not
2434 : : * strictly required, as BM_TAG_VALID/BM_VALID needs to be checked before
2435 : : * doing anything with the buffer. But currently it's beneficial, as the
2436 : : * cheaper pre-check for several linear scans of shared buffers use the
2437 : : * tag (see e.g. FlushDatabaseBuffers()).
2438 : : */
1075 andres@anarazel.de 2439 :CBC 1274025 : ClearBufferTag(&buf_hdr->tag);
129 andres@anarazel.de 2440 :GNC 1274025 : UnlockBufHdrExt(buf_hdr, buf_state,
2441 : : 0,
2442 : : BUF_FLAG_MASK | BUF_USAGECOUNT_MASK,
2443 : : 0);
2444 : :
1075 andres@anarazel.de 2445 [ - + ]:CBC 1274025 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
2446 : :
2447 : : /* finally delete buffer from the buffer mapping table */
2448 : 1274025 : BufTableDelete(&tag, hash);
2449 : :
2450 : 1274025 : LWLockRelease(partition_lock);
2451 : :
59 andres@anarazel.de 2452 :GNC 1274025 : buf_state = pg_atomic_read_u64(&buf_hdr->state);
1075 andres@anarazel.de 2453 [ - + ]:CBC 1274025 : Assert(!(buf_state & (BM_DIRTY | BM_VALID | BM_TAG_VALID)));
2454 [ - + ]: 1274025 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
59 andres@anarazel.de 2455 [ - + ]:GNC 1274025 : Assert(BUF_STATE_GET_REFCOUNT(pg_atomic_read_u64(&buf_hdr->state)) > 0);
2456 : :
1075 andres@anarazel.de 2457 :CBC 1274025 : return true;
2458 : : }
2459 : :
2460 : : static Buffer
2461 : 2027529 : GetVictimBuffer(BufferAccessStrategy strategy, IOContext io_context)
2462 : : {
2463 : : BufferDesc *buf_hdr;
2464 : : Buffer buf;
2465 : : uint64 buf_state;
2466 : : bool from_ring;
2467 : :
2468 : : /*
2469 : : * Ensure, before we pin a victim buffer, that there's a free refcount
2470 : : * entry and resource owner slot for the pin.
2471 : : */
2472 : 2027529 : ReservePrivateRefCountEntry();
858 heikki.linnakangas@i 2473 : 2027529 : ResourceOwnerEnlarge(CurrentResourceOwner);
2474 : :
2475 : : /* we return here if a prospective victim buffer gets used concurrently */
1075 andres@anarazel.de 2476 : 7384 : again:
2477 : :
2478 : : /*
2479 : : * Select a victim buffer. The buffer is returned pinned and owned by
2480 : : * this backend.
2481 : : */
2482 : 2034913 : buf_hdr = StrategyGetBuffer(strategy, &buf_state, &from_ring);
2483 : 2034913 : buf = BufferDescriptorGetBuffer(buf_hdr);
2484 : :
2485 : : /*
2486 : : * We shouldn't have any other pins for this buffer.
2487 : : */
2488 : 2034913 : CheckBufferIsPinnedOnce(buf);
2489 : :
2490 : : /*
2491 : : * If the buffer was dirty, try to write it out. There is a race
2492 : : * condition here, another backend could dirty the buffer between
2493 : : * StrategyGetBuffer() checking that it is not in use and invalidating the
2494 : : * buffer below. That's addressed by InvalidateVictimBuffer() verifying
2495 : : * that the buffer is not dirty.
2496 : : */
2497 [ + + ]: 2034913 : if (buf_state & BM_DIRTY)
2498 : : {
2499 [ - + ]: 279429 : Assert(buf_state & BM_TAG_VALID);
2500 [ - + ]: 279429 : Assert(buf_state & BM_VALID);
2501 : :
2502 : : /*
2503 : : * We need a share-exclusive lock on the buffer contents to write it
2504 : : * out (else we might write invalid data, eg because someone else is
2505 : : * compacting the page contents while we write). We must use a
2506 : : * conditional lock acquisition here to avoid deadlock. Even though
2507 : : * the buffer was not pinned (and therefore surely not locked) when
2508 : : * StrategyGetBuffer returned it, someone else could have pinned and
2509 : : * (share-)exclusive-locked it by the time we get here. If we try to
2510 : : * get the lock unconditionally, we'd block waiting for them; if they
2511 : : * later block waiting for us, deadlock ensues. (This has been
2512 : : * observed to happen when two backends are both trying to split btree
2513 : : * index pages, and the second one just happens to be trying to split
2514 : : * the page the first one got from StrategyGetBuffer.)
2515 : : */
5 andres@anarazel.de 2516 [ - + ]:GNC 279429 : if (!BufferLockConditional(buf, buf_hdr, BUFFER_LOCK_SHARE_EXCLUSIVE))
2517 : : {
2518 : : /*
2519 : : * Someone else has locked the buffer, so give it up and loop back
2520 : : * to get another one.
2521 : : */
1075 andres@anarazel.de 2522 :UBC 0 : UnpinBuffer(buf_hdr);
2523 : 0 : goto again;
2524 : : }
2525 : :
2526 : : /*
2527 : : * If using a nondefault strategy, and this victim came from the
2528 : : * strategy ring, let the strategy decide whether to reject it when
2529 : : * reusing it would require a WAL flush. This only applies to
2530 : : * permanent buffers; unlogged buffers can have fake LSNs, so
2531 : : * XLogNeedsFlush() is not meaningful for them.
2532 : : *
2533 : : * We need to hold the content lock in at least share-exclusive mode
2534 : : * to safely inspect the page LSN, so this couldn't have been done
2535 : : * inside StrategyGetBuffer().
2536 : : */
4 melanieplageman@gmai 2537 [ + + + + ]:GNC 279429 : if (strategy && from_ring &&
2538 [ + - + + ]: 70186 : buf_state & BM_PERMANENT &&
2539 [ + + ]: 44177 : XLogNeedsFlush(BufferGetLSN(buf_hdr)) &&
2540 : 9084 : StrategyRejectBuffer(strategy, buf_hdr, from_ring))
2541 : : {
2542 : 6868 : LockBuffer(buf, BUFFER_LOCK_UNLOCK);
2543 : 6868 : UnpinBuffer(buf_hdr);
2544 : 6868 : goto again;
2545 : : }
2546 : :
2547 : : /* OK, do the I/O */
1075 andres@anarazel.de 2548 :CBC 272561 : FlushBuffer(buf_hdr, NULL, IOOBJECT_RELATION, io_context);
59 andres@anarazel.de 2549 :GNC 272561 : LockBuffer(buf, BUFFER_LOCK_UNLOCK);
2550 : :
1033 andres@anarazel.de 2551 :CBC 272561 : ScheduleBufferTagForWriteback(&BackendWritebackContext, io_context,
2552 : : &buf_hdr->tag);
2553 : : }
2554 : :
2555 : :
1075 2556 [ + + ]: 2028045 : if (buf_state & BM_VALID)
2557 : : {
2558 : : /*
2559 : : * When a BufferAccessStrategy is in use, blocks evicted from shared
2560 : : * buffers are counted as IOOP_EVICT in the corresponding context
2561 : : * (e.g. IOCONTEXT_BULKWRITE). Shared buffers are evicted by a
2562 : : * strategy in two cases: 1) while initially claiming buffers for the
2563 : : * strategy ring 2) to replace an existing strategy ring buffer
2564 : : * because it is pinned or in use and cannot be reused.
2565 : : *
2566 : : * Blocks evicted from buffers already in the strategy ring are
2567 : : * counted as IOOP_REUSE in the corresponding strategy context.
2568 : : *
2569 : : * At this point, we can accurately count evictions and reuses,
2570 : : * because we have successfully claimed the valid buffer. Previously,
2571 : : * we may have been forced to release the buffer due to concurrent
2572 : : * pinners or erroring out.
2573 : : */
2574 : 1272305 : pgstat_count_io_op(IOOBJECT_RELATION, io_context,
425 michael@paquier.xyz 2575 [ + + ]: 1272305 : from_ring ? IOOP_REUSE : IOOP_EVICT, 1, 0);
2576 : : }
2577 : :
2578 : : /*
2579 : : * If the buffer has an entry in the buffer mapping table, delete it. This
2580 : : * can fail because another backend could have pinned or dirtied the
2581 : : * buffer.
2582 : : */
1075 andres@anarazel.de 2583 [ + + + + ]: 2028045 : if ((buf_state & BM_TAG_VALID) && !InvalidateVictimBuffer(buf_hdr))
2584 : : {
2585 : 516 : UnpinBuffer(buf_hdr);
2586 : 516 : goto again;
2587 : : }
2588 : :
2589 : : /* a final set of sanity checks */
2590 : : #ifdef USE_ASSERT_CHECKING
59 andres@anarazel.de 2591 :GNC 2027529 : buf_state = pg_atomic_read_u64(&buf_hdr->state);
2592 : :
1075 andres@anarazel.de 2593 [ - + ]:CBC 2027529 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) == 1);
2594 [ - + ]: 2027529 : Assert(!(buf_state & (BM_TAG_VALID | BM_VALID | BM_DIRTY)));
2595 : :
2596 : 2027529 : CheckBufferIsPinnedOnce(buf);
2597 : : #endif
2598 : :
2599 : 2027529 : return buf;
2600 : : }
2601 : :
2602 : : /*
2603 : : * Return the maximum number of buffers that a backend should try to pin once,
2604 : : * to avoid exceeding its fair share. This is the highest value that
2605 : : * GetAdditionalPinLimit() could ever return. Note that it may be zero on a
2606 : : * system with a very small buffer pool relative to max_connections.
2607 : : */
2608 : : uint32
366 tmunro@postgresql.or 2609 : 855297 : GetPinLimit(void)
2610 : : {
2611 : 855297 : return MaxProportionalPins;
2612 : : }
2613 : :
2614 : : /*
2615 : : * Return the maximum number of additional buffers that this backend should
2616 : : * pin if it wants to stay under the per-backend limit, considering the number
2617 : : * of buffers it has already pinned. Unlike LimitAdditionalPins(), the limit
2618 : : * return by this function can be zero.
2619 : : */
2620 : : uint32
2621 : 3670081 : GetAdditionalPinLimit(void)
2622 : : {
2623 : : uint32 estimated_pins_held;
2624 : :
2625 : : /*
2626 : : * We get the number of "overflowed" pins for free, but don't know the
2627 : : * number of pins in PrivateRefCountArray. The cost of calculating that
2628 : : * exactly doesn't seem worth it, so just assume the max.
2629 : : */
2630 : 3670081 : estimated_pins_held = PrivateRefCountOverflowed + REFCOUNT_ARRAY_ENTRIES;
2631 : :
2632 : : /* Is this backend already holding more than its fair share? */
2633 [ + + ]: 3670081 : if (estimated_pins_held > MaxProportionalPins)
2634 : 1348854 : return 0;
2635 : :
2636 : 2321227 : return MaxProportionalPins - estimated_pins_held;
2637 : : }
2638 : :
2639 : : /*
2640 : : * Limit the number of pins a batch operation may additionally acquire, to
2641 : : * avoid running out of pinnable buffers.
2642 : : *
2643 : : * One additional pin is always allowed, on the assumption that the operation
2644 : : * requires at least one to make progress.
2645 : : */
2646 : : void
1075 andres@anarazel.de 2647 : 208626 : LimitAdditionalPins(uint32 *additional_pins)
2648 : : {
2649 : : uint32 limit;
2650 : :
2651 [ + + ]: 208626 : if (*additional_pins <= 1)
2652 : 198547 : return;
2653 : :
366 tmunro@postgresql.or 2654 : 10079 : limit = GetAdditionalPinLimit();
2655 : 10079 : limit = Max(limit, 1);
2656 [ + + ]: 10079 : if (limit < *additional_pins)
2657 : 5526 : *additional_pins = limit;
2658 : : }
2659 : :
2660 : : /*
2661 : : * Logic shared between ExtendBufferedRelBy(), ExtendBufferedRelTo(). Just to
2662 : : * avoid duplicating the tracing and relpersistence related logic.
2663 : : */
2664 : : static BlockNumber
935 2665 : 221181 : ExtendBufferedRelCommon(BufferManagerRelation bmr,
2666 : : ForkNumber fork,
2667 : : BufferAccessStrategy strategy,
2668 : : uint32 flags,
2669 : : uint32 extend_by,
2670 : : BlockNumber extend_upto,
2671 : : Buffer *buffers,
2672 : : uint32 *extended_by)
2673 : : {
2674 : : BlockNumber first_block;
2675 : :
2676 : : TRACE_POSTGRESQL_BUFFER_EXTEND_START(fork,
2677 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.spcOid,
2678 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.dbOid,
2679 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.relNumber,
2680 : : BMR_GET_SMGR(bmr)->smgr_rlocator.backend,
2681 : : extend_by);
2682 : :
2683 [ + + ]: 221181 : if (bmr.relpersistence == RELPERSISTENCE_TEMP)
2684 : 12555 : first_block = ExtendBufferedRelLocal(bmr, fork, flags,
2685 : : extend_by, extend_upto,
2686 : : buffers, &extend_by);
2687 : : else
2688 : 208626 : first_block = ExtendBufferedRelShared(bmr, fork, strategy, flags,
2689 : : extend_by, extend_upto,
2690 : : buffers, &extend_by);
1075 andres@anarazel.de 2691 : 221181 : *extended_by = extend_by;
2692 : :
2693 : : TRACE_POSTGRESQL_BUFFER_EXTEND_DONE(fork,
2694 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.spcOid,
2695 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.dbOid,
2696 : : BMR_GET_SMGR(bmr)->smgr_rlocator.locator.relNumber,
2697 : : BMR_GET_SMGR(bmr)->smgr_rlocator.backend,
2698 : : *extended_by,
2699 : : first_block);
2700 : :
2701 : 221181 : return first_block;
2702 : : }
2703 : :
2704 : : /*
2705 : : * Implementation of ExtendBufferedRelBy() and ExtendBufferedRelTo() for
2706 : : * shared buffers.
2707 : : */
2708 : : static BlockNumber
935 tmunro@postgresql.or 2709 : 208626 : ExtendBufferedRelShared(BufferManagerRelation bmr,
2710 : : ForkNumber fork,
2711 : : BufferAccessStrategy strategy,
2712 : : uint32 flags,
2713 : : uint32 extend_by,
2714 : : BlockNumber extend_upto,
2715 : : Buffer *buffers,
2716 : : uint32 *extended_by)
2717 : : {
2718 : : BlockNumber first_block;
1075 andres@anarazel.de 2719 : 208626 : IOContext io_context = IOContextForStrategy(strategy);
2720 : : instr_time io_start;
2721 : :
2722 : 208626 : LimitAdditionalPins(&extend_by);
2723 : :
2724 : : /*
2725 : : * Acquire victim buffers for extension without holding extension lock.
2726 : : * Writing out victim buffers is the most expensive part of extending the
2727 : : * relation, particularly when doing so requires WAL flushes. Zeroing out
2728 : : * the buffers is also quite expensive, so do that before holding the
2729 : : * extension lock as well.
2730 : : *
2731 : : * These pages are pinned by us and not valid. While we hold the pin they
2732 : : * can't be acquired as victim buffers by another backend.
2733 : : */
2734 [ + + ]: 438644 : for (uint32 i = 0; i < extend_by; i++)
2735 : : {
2736 : : Block buf_block;
2737 : :
2738 : 230018 : buffers[i] = GetVictimBuffer(strategy, io_context);
2739 : 230018 : buf_block = BufHdrGetBlock(GetBufferDescriptor(buffers[i] - 1));
2740 : :
2741 : : /* new buffers are zero-filled */
396 peter@eisentraut.org 2742 [ + - + - : 230018 : MemSet(buf_block, 0, BLCKSZ);
+ - - + -
- ]
2743 : : }
2744 : :
2745 : : /*
2746 : : * Lock relation against concurrent extensions, unless requested not to.
2747 : : *
2748 : : * We use the same extension lock for all forks. That's unnecessarily
2749 : : * restrictive, but currently extensions for forks don't happen often
2750 : : * enough to make it worth locking more granularly.
2751 : : *
2752 : : * Note that another backend might have extended the relation by the time
2753 : : * we get the lock.
2754 : : */
1075 andres@anarazel.de 2755 [ + + ]: 208626 : if (!(flags & EB_SKIP_EXTENSION_LOCK))
935 tmunro@postgresql.or 2756 : 155761 : LockRelationForExtension(bmr.rel, ExclusiveLock);
2757 : :
2758 : : /*
2759 : : * If requested, invalidate size cache, so that smgrnblocks asks the
2760 : : * kernel.
2761 : : */
1075 andres@anarazel.de 2762 [ + + ]: 208626 : if (flags & EB_CLEAR_SIZE_CACHE)
145 alvherre@kurilemu.de 2763 [ + - ]:GNC 7959 : BMR_GET_SMGR(bmr)->smgr_cached_nblocks[fork] = InvalidBlockNumber;
2764 : :
2765 [ + + ]: 208626 : first_block = smgrnblocks(BMR_GET_SMGR(bmr), fork);
2766 : :
2767 : : /*
2768 : : * Now that we have the accurate relation size, check if the caller wants
2769 : : * us to extend to only up to a specific size. If there were concurrent
2770 : : * extensions, we might have acquired too many buffers and need to release
2771 : : * them.
2772 : : */
1075 andres@anarazel.de 2773 [ + + ]:CBC 208626 : if (extend_upto != InvalidBlockNumber)
2774 : : {
2775 : 54761 : uint32 orig_extend_by = extend_by;
2776 : :
2777 [ - + ]: 54761 : if (first_block > extend_upto)
1075 andres@anarazel.de 2778 :UBC 0 : extend_by = 0;
1075 andres@anarazel.de 2779 [ + + ]:CBC 54761 : else if ((uint64) first_block + extend_by > extend_upto)
2780 : 6 : extend_by = extend_upto - first_block;
2781 : :
2782 [ + + ]: 54770 : for (uint32 i = extend_by; i < orig_extend_by; i++)
2783 : : {
2784 : 9 : BufferDesc *buf_hdr = GetBufferDescriptor(buffers[i] - 1);
2785 : :
2786 : 9 : UnpinBuffer(buf_hdr);
2787 : : }
2788 : :
2789 [ + + ]: 54761 : if (extend_by == 0)
2790 : : {
2791 [ + - ]: 6 : if (!(flags & EB_SKIP_EXTENSION_LOCK))
935 tmunro@postgresql.or 2792 : 6 : UnlockRelationForExtension(bmr.rel, ExclusiveLock);
1075 andres@anarazel.de 2793 : 6 : *extended_by = extend_by;
2794 : 6 : return first_block;
2795 : : }
2796 : : }
2797 : :
2798 : : /* Fail if relation is already at maximum possible length */
2799 [ - + ]: 208620 : if ((uint64) first_block + extend_by >= MaxBlockNumber)
1075 andres@anarazel.de 2800 [ # # # # :UBC 0 : ereport(ERROR,
# # # # #
# ]
2801 : : (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
2802 : : errmsg("cannot extend relation %s beyond %u blocks",
2803 : : relpath(BMR_GET_SMGR(bmr)->smgr_rlocator, fork).str,
2804 : : MaxBlockNumber)));
2805 : :
2806 : : /*
2807 : : * Insert buffers into buffer table, mark as IO_IN_PROGRESS.
2808 : : *
2809 : : * This needs to happen before we extend the relation, because as soon as
2810 : : * we do, other backends can start to read in those pages.
2811 : : */
908 peter@eisentraut.org 2812 [ + + ]:CBC 438629 : for (uint32 i = 0; i < extend_by; i++)
2813 : : {
1075 andres@anarazel.de 2814 : 230009 : Buffer victim_buf = buffers[i];
2815 : 230009 : BufferDesc *victim_buf_hdr = GetBufferDescriptor(victim_buf - 1);
2816 : : BufferTag tag;
2817 : : uint32 hash;
2818 : : LWLock *partition_lock;
2819 : : int existing_id;
2820 : :
2821 : : /* in case we need to pin an existing buffer below */
858 heikki.linnakangas@i 2822 : 230009 : ResourceOwnerEnlarge(CurrentResourceOwner);
2823 : 230009 : ReservePrivateRefCountEntry();
2824 : :
145 alvherre@kurilemu.de 2825 [ + + ]:GNC 230009 : InitBufferTag(&tag, &BMR_GET_SMGR(bmr)->smgr_rlocator.locator, fork,
2826 : : first_block + i);
1075 andres@anarazel.de 2827 :CBC 230009 : hash = BufTableHashCode(&tag);
2828 : 230009 : partition_lock = BufMappingPartitionLock(hash);
2829 : :
2830 : 230009 : LWLockAcquire(partition_lock, LW_EXCLUSIVE);
2831 : :
2832 : 230009 : existing_id = BufTableInsert(&tag, hash, victim_buf_hdr->buf_id);
2833 : :
2834 : : /*
2835 : : * We get here only in the corner case where we are trying to extend
2836 : : * the relation but we found a pre-existing buffer. This can happen
2837 : : * because a prior attempt at extending the relation failed, and
2838 : : * because mdread doesn't complain about reads beyond EOF (when
2839 : : * zero_damaged_pages is ON) and so a previous attempt to read a block
2840 : : * beyond EOF could have left a "valid" zero-filled buffer.
2841 : : *
2842 : : * This has also been observed when relation was overwritten by
2843 : : * external process. Since the legitimate cases should always have
2844 : : * left a zero-filled buffer, complain if not PageIsNew.
2845 : : */
2846 [ - + ]: 230009 : if (existing_id >= 0)
2847 : : {
1075 andres@anarazel.de 2848 :UBC 0 : BufferDesc *existing_hdr = GetBufferDescriptor(existing_id);
2849 : : Block buf_block;
2850 : : bool valid;
2851 : :
2852 : : /*
2853 : : * Pin the existing buffer before releasing the partition lock,
2854 : : * preventing it from being evicted.
2855 : : */
158 andres@anarazel.de 2856 :UNC 0 : valid = PinBuffer(existing_hdr, strategy, false);
2857 : :
1075 andres@anarazel.de 2858 :UBC 0 : LWLockRelease(partition_lock);
2859 : 0 : UnpinBuffer(victim_buf_hdr);
2860 : :
2861 : 0 : buffers[i] = BufferDescriptorGetBuffer(existing_hdr);
2862 : 0 : buf_block = BufHdrGetBlock(existing_hdr);
2863 : :
2864 [ # # # # ]: 0 : if (valid && !PageIsNew((Page) buf_block))
2865 [ # # # # : 0 : ereport(ERROR,
# # # # #
# ]
2866 : : (errmsg("unexpected data beyond EOF in block %u of relation \"%s\"",
2867 : : existing_hdr->tag.blockNum,
2868 : : relpath(BMR_GET_SMGR(bmr)->smgr_rlocator, fork).str)));
2869 : :
2870 : : /*
2871 : : * We *must* do smgr[zero]extend before succeeding, else the page
2872 : : * will not be reserved by the kernel, and the next P_NEW call
2873 : : * will decide to return the same page. Clear the BM_VALID bit,
2874 : : * do StartBufferIO() and proceed.
2875 : : *
2876 : : * Loop to handle the very small possibility that someone re-sets
2877 : : * BM_VALID between our clearing it and StartBufferIO inspecting
2878 : : * it.
2879 : : */
2880 : : do
2881 : : {
59 andres@anarazel.de 2882 :UNC 0 : pg_atomic_fetch_and_u64(&existing_hdr->state, ~BM_VALID);
711 tmunro@postgresql.or 2883 [ # # ]:UBC 0 : } while (!StartBufferIO(existing_hdr, true, false));
2884 : : }
2885 : : else
2886 : : {
2887 : : uint64 buf_state;
59 andres@anarazel.de 2888 :GNC 230009 : uint64 set_bits = 0;
2889 : :
1075 andres@anarazel.de 2890 :CBC 230009 : buf_state = LockBufHdr(victim_buf_hdr);
2891 : :
2892 : : /* some sanity checks while we hold the buffer header lock */
4 andres@anarazel.de 2893 [ - + ]:GNC 230009 : Assert(!(buf_state & (BM_VALID | BM_TAG_VALID | BM_DIRTY)));
1075 andres@anarazel.de 2894 [ - + ]:CBC 230009 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) == 1);
2895 : :
2896 : 230009 : victim_buf_hdr->tag = tag;
2897 : :
129 andres@anarazel.de 2898 :GNC 230009 : set_bits |= BM_TAG_VALID | BUF_USAGECOUNT_ONE;
935 tmunro@postgresql.or 2899 [ + + + + ]:CBC 230009 : if (bmr.relpersistence == RELPERSISTENCE_PERMANENT || fork == INIT_FORKNUM)
129 andres@anarazel.de 2900 :GNC 224085 : set_bits |= BM_PERMANENT;
2901 : :
2902 : 230009 : UnlockBufHdrExt(victim_buf_hdr, buf_state,
2903 : : set_bits, 0,
2904 : : 0);
2905 : :
1075 andres@anarazel.de 2906 :CBC 230009 : LWLockRelease(partition_lock);
2907 : :
2908 : : /* XXX: could combine the locked operations in it with the above */
711 tmunro@postgresql.or 2909 : 230009 : StartBufferIO(victim_buf_hdr, true, false);
2910 : : }
2911 : : }
2912 : :
382 michael@paquier.xyz 2913 : 208620 : io_start = pgstat_prepare_io_time(track_io_timing);
2914 : :
2915 : : /*
2916 : : * Note: if smgrzeroextend fails, we will end up with buffers that are
2917 : : * allocated but not marked BM_VALID. The next relation extension will
2918 : : * still select the same block number (because the relation didn't get any
2919 : : * longer on disk) and so future attempts to extend the relation will find
2920 : : * the same buffers (if they have not been recycled) but come right back
2921 : : * here to try smgrzeroextend again.
2922 : : *
2923 : : * We don't need to set checksum for all-zero pages.
2924 : : */
145 alvherre@kurilemu.de 2925 [ + + ]:GNC 208620 : smgrzeroextend(BMR_GET_SMGR(bmr), fork, first_block, extend_by, false);
2926 : :
2927 : : /*
2928 : : * Release the file-extension lock; it's now OK for someone else to extend
2929 : : * the relation some more.
2930 : : *
2931 : : * We remove IO_IN_PROGRESS after this, as waking up waiting backends can
2932 : : * take noticeable time.
2933 : : */
1075 andres@anarazel.de 2934 [ + + ]:CBC 208620 : if (!(flags & EB_SKIP_EXTENSION_LOCK))
935 tmunro@postgresql.or 2935 : 155755 : UnlockRelationForExtension(bmr.rel, ExclusiveLock);
2936 : :
1073 andres@anarazel.de 2937 : 208620 : pgstat_count_io_op_time(IOOBJECT_RELATION, io_context, IOOP_EXTEND,
425 michael@paquier.xyz 2938 : 208620 : io_start, 1, extend_by * BLCKSZ);
2939 : :
2940 : : /* Set BM_VALID, terminate IO, and wake up any waiters */
908 peter@eisentraut.org 2941 [ + + ]: 438629 : for (uint32 i = 0; i < extend_by; i++)
2942 : : {
1075 andres@anarazel.de 2943 : 230009 : Buffer buf = buffers[i];
2944 : 230009 : BufferDesc *buf_hdr = GetBufferDescriptor(buf - 1);
2945 : 230009 : bool lock = false;
2946 : :
2947 [ + + + + ]: 230009 : if (flags & EB_LOCK_FIRST && i == 0)
2948 : 153594 : lock = true;
2949 [ + + ]: 76415 : else if (flags & EB_LOCK_TARGET)
2950 : : {
2951 [ - + ]: 45731 : Assert(extend_upto != InvalidBlockNumber);
2952 [ + + ]: 45731 : if (first_block + i + 1 == extend_upto)
2953 : 45145 : lock = true;
2954 : : }
2955 : :
2956 [ + + ]: 230009 : if (lock)
158 andres@anarazel.de 2957 :GNC 198739 : LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
2958 : :
350 andres@anarazel.de 2959 :CBC 230009 : TerminateBufferIO(buf_hdr, false, BM_VALID, true, false);
2960 : : }
2961 : :
1075 2962 : 208620 : pgBufferUsage.shared_blks_written += extend_by;
2963 : :
2964 : 208620 : *extended_by = extend_by;
2965 : :
2966 : 208620 : return first_block;
2967 : : }
2968 : :
2969 : : /*
2970 : : * BufferIsLockedByMe
2971 : : *
2972 : : * Checks if this backend has the buffer locked in any mode.
2973 : : *
2974 : : * Buffer must be pinned.
2975 : : */
2976 : : bool
158 andres@anarazel.de 2977 :GNC 104 : BufferIsLockedByMe(Buffer buffer)
2978 : : {
2979 : : BufferDesc *bufHdr;
2980 : :
2981 [ - + - + : 104 : Assert(BufferIsPinned(buffer));
- + ]
2982 : :
2983 [ - + ]: 104 : if (BufferIsLocal(buffer))
2984 : : {
2985 : : /* Content locks are not maintained for local buffers. */
158 andres@anarazel.de 2986 :UNC 0 : return true;
2987 : : }
2988 : : else
2989 : : {
158 andres@anarazel.de 2990 :GNC 104 : bufHdr = GetBufferDescriptor(buffer - 1);
59 2991 : 104 : return BufferLockHeldByMe(bufHdr);
2992 : : }
2993 : : }
2994 : :
2995 : : /*
2996 : : * BufferIsLockedByMeInMode
2997 : : *
2998 : : * Checks if this backend has the buffer locked in the specified mode.
2999 : : *
3000 : : * Buffer must be pinned.
3001 : : */
3002 : : bool
102 3003 : 72765987 : BufferIsLockedByMeInMode(Buffer buffer, BufferLockMode mode)
3004 : : {
3005 : : BufferDesc *bufHdr;
3006 : :
410 tgl@sss.pgh.pa.us 3007 [ - + + + :CBC 72765987 : Assert(BufferIsPinned(buffer));
- + ]
3008 : :
874 jdavis@postgresql.or 3009 [ + + ]: 72765987 : if (BufferIsLocal(buffer))
3010 : : {
3011 : : /* Content locks are not maintained for local buffers. */
410 tgl@sss.pgh.pa.us 3012 :GBC 1532 : return true;
3013 : : }
3014 : : else
3015 : : {
874 jdavis@postgresql.or 3016 :CBC 72764455 : bufHdr = GetBufferDescriptor(buffer - 1);
59 andres@anarazel.de 3017 :GNC 72764455 : return BufferLockHeldByMeInMode(bufHdr, mode);
3018 : : }
3019 : : }
3020 : :
3021 : : /*
3022 : : * BufferIsDirty
3023 : : *
3024 : : * Checks if buffer is already dirty.
3025 : : *
3026 : : * Buffer must be pinned and [share-]exclusive-locked. (Without such a lock,
3027 : : * the result may be stale before it's returned.)
3028 : : */
3029 : : bool
874 jdavis@postgresql.or 3030 :CBC 16930486 : BufferIsDirty(Buffer buffer)
3031 : : {
3032 : : BufferDesc *bufHdr;
3033 : :
410 tgl@sss.pgh.pa.us 3034 [ - + - + : 16930486 : Assert(BufferIsPinned(buffer));
- + ]
3035 : :
874 jdavis@postgresql.or 3036 [ - + ]: 16930486 : if (BufferIsLocal(buffer))
3037 : : {
874 jdavis@postgresql.or 3038 :UBC 0 : int bufid = -buffer - 1;
3039 : :
3040 : 0 : bufHdr = GetLocalBufferDescriptor(bufid);
3041 : : /* Content locks are not maintained for local buffers. */
3042 : : }
3043 : : else
3044 : : {
874 jdavis@postgresql.or 3045 :CBC 16930486 : bufHdr = GetBufferDescriptor(buffer - 1);
5 andres@anarazel.de 3046 [ + + - + ]:GNC 16930486 : Assert(BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_SHARE_EXCLUSIVE) ||
3047 : : BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_EXCLUSIVE));
3048 : : }
3049 : :
59 3050 : 16930486 : return pg_atomic_read_u64(&bufHdr->state) & BM_DIRTY;
3051 : : }
3052 : :
3053 : : /*
3054 : : * MarkBufferDirty
3055 : : *
3056 : : * Marks buffer contents as dirty (actual write happens later).
3057 : : *
3058 : : * Buffer must be pinned and exclusive-locked. (If caller does not hold
3059 : : * exclusive lock, then somebody could be in process of writing the buffer,
3060 : : * leading to risk of bad data written to disk.)
3061 : : */
3062 : : void
7289 tgl@sss.pgh.pa.us 3063 :CBC 23086694 : MarkBufferDirty(Buffer buffer)
3064 : : {
3065 : : BufferDesc *bufHdr;
3066 : : uint64 buf_state;
3067 : : uint64 old_buf_state;
3068 : :
7821 3069 [ - + ]: 23086694 : if (!BufferIsValid(buffer))
5383 peter_e@gmx.net 3070 [ # # ]:UBC 0 : elog(ERROR, "bad buffer ID: %d", buffer);
3071 : :
9480 tgl@sss.pgh.pa.us 3072 [ + + ]:CBC 23086694 : if (BufferIsLocal(buffer))
3073 : : {
7289 3074 : 1383377 : MarkLocalBufferDirty(buffer);
8674 bruce@momjian.us 3075 : 1383377 : return;
3076 : : }
3077 : :
4063 andres@anarazel.de 3078 : 21703317 : bufHdr = GetBufferDescriptor(buffer - 1);
3079 : :
4215 3080 [ - + - + : 21703317 : Assert(BufferIsPinned(buffer));
- + ]
158 andres@anarazel.de 3081 [ - + ]:GNC 21703317 : Assert(BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_EXCLUSIVE));
3082 : :
3083 : : /*
3084 : : * NB: We have to wait for the buffer header spinlock to be not held, as
3085 : : * TerminateBufferIO() relies on the spinlock.
3086 : : */
59 3087 : 21703317 : old_buf_state = pg_atomic_read_u64(&bufHdr->state);
3088 : : for (;;)
3089 : : {
3626 andres@anarazel.de 3090 [ + + ]:CBC 21703409 : if (old_buf_state & BM_LOCKED)
3091 : 198 : old_buf_state = WaitBufHdrUnlocked(bufHdr);
3092 : :
3093 : 21703409 : buf_state = old_buf_state;
3094 : :
3095 [ - + ]: 21703409 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
4 andres@anarazel.de 3096 :GNC 21703409 : buf_state |= BM_DIRTY;
3097 : :
59 3098 [ + + ]: 21703409 : if (pg_atomic_compare_exchange_u64(&bufHdr->state, &old_buf_state,
3099 : : buf_state))
3626 andres@anarazel.de 3100 :CBC 21703317 : break;
3101 : : }
3102 : :
3103 : : /*
3104 : : * If the buffer was not dirty already, do vacuum accounting.
3105 : : */
3106 [ + + ]: 21703317 : if (!(old_buf_state & BM_DIRTY))
3107 : : {
5135 rhaas@postgresql.org 3108 : 684621 : pgBufferUsage.shared_blks_dirtied++;
5224 alvherre@alvh.no-ip. 3109 [ + + ]: 684621 : if (VacuumCostActive)
3110 : 10788 : VacuumCostBalance += VacuumCostPageDirty;
3111 : : }
3112 : : }
3113 : :
3114 : : /*
3115 : : * ReleaseAndReadBuffer -- combine ReleaseBuffer() and ReadBuffer()
3116 : : *
3117 : : * Formerly, this saved one cycle of acquiring/releasing the BufMgrLock
3118 : : * compared to calling the two routines separately. Now it's mainly just
3119 : : * a convenience function. However, if the passed buffer is valid and
3120 : : * already contains the desired block, we just return it as-is; and that
3121 : : * does save considerable work compared to a full release and reacquire.
3122 : : *
3123 : : * Note: it is OK to pass buffer == InvalidBuffer, indicating that no old
3124 : : * buffer actually needs to be released. This case is the same as ReadBuffer,
3125 : : * but can save some tests in the caller.
3126 : : */
3127 : : Buffer
10841 scrappy@hub.org 3128 : 30084750 : ReleaseAndReadBuffer(Buffer buffer,
3129 : : Relation relation,
3130 : : BlockNumber blockNum)
3131 : : {
6121 bruce@momjian.us 3132 : 30084750 : ForkNumber forkNum = MAIN_FORKNUM;
3133 : : BufferDesc *bufHdr;
3134 : :
9073 tgl@sss.pgh.pa.us 3135 [ + + ]: 30084750 : if (BufferIsValid(buffer))
3136 : : {
4215 andres@anarazel.de 3137 [ - + + + : 18954087 : Assert(BufferIsPinned(buffer));
- + ]
9073 tgl@sss.pgh.pa.us 3138 [ + + ]: 18954087 : if (BufferIsLocal(buffer))
3139 : : {
4063 andres@anarazel.de 3140 : 136844 : bufHdr = GetLocalBufferDescriptor(-buffer - 1);
9045 tgl@sss.pgh.pa.us 3141 [ + + + - ]: 140663 : if (bufHdr->tag.blockNum == blockNum &&
1299 rhaas@postgresql.org 3142 [ + - ]: 7638 : BufTagMatchesRelFileLocator(&bufHdr->tag, &relation->rd_locator) &&
3143 : 3819 : BufTagGetForkNum(&bufHdr->tag) == forkNum)
9045 tgl@sss.pgh.pa.us 3144 : 3819 : return buffer;
1075 andres@anarazel.de 3145 : 133025 : UnpinLocalBuffer(buffer);
3146 : : }
3147 : : else
3148 : : {
4063 3149 : 18817243 : bufHdr = GetBufferDescriptor(buffer - 1);
3150 : : /* we have pin, so it's ok to examine tag without spinlock */
9045 tgl@sss.pgh.pa.us 3151 [ + + + - ]: 24539204 : if (bufHdr->tag.blockNum == blockNum &&
1299 rhaas@postgresql.org 3152 [ + - ]: 11443922 : BufTagMatchesRelFileLocator(&bufHdr->tag, &relation->rd_locator) &&
3153 : 5721961 : BufTagGetForkNum(&bufHdr->tag) == forkNum)
9045 tgl@sss.pgh.pa.us 3154 : 5721961 : return buffer;
1262 michael@paquier.xyz 3155 : 13095282 : UnpinBuffer(bufHdr);
3156 : : }
3157 : : }
3158 : :
7681 tgl@sss.pgh.pa.us 3159 : 24358970 : return ReadBuffer(relation, blockNum);
3160 : : }
3161 : :
3162 : : /*
3163 : : * PinBuffer -- make buffer unavailable for replacement.
3164 : : *
3165 : : * For the default access strategy, the buffer's usage_count is incremented
3166 : : * when we first pin it; for other strategies we just make sure the usage_count
3167 : : * isn't zero. (The idea of the latter is that we don't want synchronized
3168 : : * heap scans to inflate the count, but we need it to not be zero to discourage
3169 : : * other backends from stealing buffers from our ring. As long as we cycle
3170 : : * through the ring faster than the global clock-sweep cycles, buffers in
3171 : : * our ring won't be chosen as victims for replacement by other backends.)
3172 : : *
3173 : : * This should be applied only to shared buffers, never local ones.
3174 : : *
3175 : : * Since buffers are pinned/unpinned very frequently, pin buffers without
3176 : : * taking the buffer header lock; instead update the state variable in loop of
3177 : : * CAS operations. Hopefully it's just a single CAS.
3178 : : *
3179 : : * Note that ResourceOwnerEnlarge() and ReservePrivateRefCountEntry()
3180 : : * must have been done already.
3181 : : *
3182 : : * Returns true if buffer is BM_VALID, else false. This provision allows
3183 : : * some callers to avoid an extra spinlock cycle. If skip_if_not_valid is
3184 : : * true, then a false return value also indicates that the buffer was
3185 : : * (recently) invalid and has not been pinned.
3186 : : */
3187 : : static bool
158 andres@anarazel.de 3188 :GNC 62398458 : PinBuffer(BufferDesc *buf, BufferAccessStrategy strategy,
3189 : : bool skip_if_not_valid)
3190 : : {
3868 andres@anarazel.de 3191 :CBC 62398458 : Buffer b = BufferDescriptorGetBuffer(buf);
3192 : : bool result;
3193 : : PrivateRefCountEntry *ref;
3194 : :
1075 3195 [ - + ]: 62398458 : Assert(!BufferIsLocal(b));
91 andres@anarazel.de 3196 [ - + ]:GNC 62398458 : Assert(ReservedRefCountSlot != -1);
3197 : :
3868 andres@anarazel.de 3198 :CBC 62398458 : ref = GetPrivateRefCountEntry(b, true);
3199 : :
4073 3200 [ + + ]: 62398458 : if (ref == NULL)
3201 : : {
3202 : : uint64 buf_state;
3203 : : uint64 old_buf_state;
3204 : :
59 andres@anarazel.de 3205 :GNC 59777094 : old_buf_state = pg_atomic_read_u64(&buf->state);
3206 : : for (;;)
3207 : : {
158 3208 [ + + + + : 59786576 : if (unlikely(skip_if_not_valid && !(old_buf_state & BM_VALID)))
+ + ]
3209 : 9 : return false;
3210 : :
3211 : : /*
3212 : : * We're not allowed to increase the refcount while the buffer
3213 : : * header spinlock is held. Wait for the lock to be released.
3214 : : */
3626 andres@anarazel.de 3215 [ + + ]:CBC 59786567 : if (old_buf_state & BM_LOCKED)
3216 : 71 : old_buf_state = WaitBufHdrUnlocked(buf);
3217 : :
3218 : 59786567 : buf_state = old_buf_state;
3219 : :
3220 : : /* increase refcount */
3221 : 59786567 : buf_state += BUF_REFCOUNT_ONE;
3222 : :
3282 teodor@sigaev.ru 3223 [ + + ]: 59786567 : if (strategy == NULL)
3224 : : {
3225 : : /* Default case: increase usagecount unless already max. */
3226 [ + + ]: 59280775 : if (BUF_STATE_GET_USAGECOUNT(buf_state) < BM_MAX_USAGE_COUNT)
3227 : 3517460 : buf_state += BUF_USAGECOUNT_ONE;
3228 : : }
3229 : : else
3230 : : {
3231 : : /*
3232 : : * Ring buffers shouldn't evict others from pool. Thus we
3233 : : * don't make usagecount more than 1.
3234 : : */
3235 [ + + ]: 505792 : if (BUF_STATE_GET_USAGECOUNT(buf_state) == 0)
3236 : 34229 : buf_state += BUF_USAGECOUNT_ONE;
3237 : : }
3238 : :
59 andres@anarazel.de 3239 [ + + ]:GNC 59786567 : if (pg_atomic_compare_exchange_u64(&buf->state, &old_buf_state,
3240 : : buf_state))
3241 : : {
3626 andres@anarazel.de 3242 :CBC 59777085 : result = (buf_state & BM_VALID) != 0;
3243 : :
158 andres@anarazel.de 3244 :GNC 59777085 : TrackNewBufferPin(b);
3626 andres@anarazel.de 3245 :CBC 59777085 : break;
3246 : : }
3247 : : }
3248 : : }
3249 : : else
3250 : : {
3251 : : /*
3252 : : * If we previously pinned the buffer, it is likely to be valid, but
3253 : : * it may not be if StartReadBuffers() was called and
3254 : : * WaitReadBuffers() hasn't been called yet. We'll check by loading
3255 : : * the flags without locking. This is racy, but it's OK to return
3256 : : * false spuriously: when WaitReadBuffers() calls StartBufferIO(),
3257 : : * it'll see that it's now valid.
3258 : : *
3259 : : * Note: We deliberately avoid a Valgrind client request here.
3260 : : * Individual access methods can optionally superimpose buffer page
3261 : : * client requests on top of our client requests to enforce that
3262 : : * buffers are only accessed while locked (and pinned). It's possible
3263 : : * that the buffer page is legitimately non-accessible here. We
3264 : : * cannot meddle with that.
3265 : : */
59 andres@anarazel.de 3266 :GNC 2621364 : result = (pg_atomic_read_u64(&buf->state) & BM_VALID) != 0;
3267 : :
91 3268 [ - + ]: 2621364 : Assert(ref->data.refcount > 0);
3269 : 2621364 : ref->data.refcount++;
158 3270 : 2621364 : ResourceOwnerRememberBuffer(CurrentResourceOwner, b);
3271 : : }
3272 : :
7681 tgl@sss.pgh.pa.us 3273 :CBC 62398449 : return result;
3274 : : }
3275 : :
3276 : : /*
3277 : : * PinBuffer_Locked -- as above, but caller already locked the buffer header.
3278 : : * The spinlock is released before return.
3279 : : *
3280 : : * As this function is called with the spinlock held, the caller has to
3281 : : * previously call ReservePrivateRefCountEntry() and
3282 : : * ResourceOwnerEnlarge(CurrentResourceOwner);
3283 : : *
3284 : : * Currently, no callers of this function want to modify the buffer's
3285 : : * usage_count at all, so there's no need for a strategy parameter.
3286 : : * Also we don't bother with a BM_VALID test (the caller could check that for
3287 : : * itself).
3288 : : *
3289 : : * Also all callers only ever use this function when it's known that the
3290 : : * buffer can't have a preexisting pin by this backend. That allows us to skip
3291 : : * searching the private refcount array & hash, which is a boon, because the
3292 : : * spinlock is still held.
3293 : : *
3294 : : * Note: use of this routine is frequently mandatory, not just an optimization
3295 : : * to save a spin lock/unlock cycle, because we need to pin a buffer before
3296 : : * its state can change under us.
3297 : : */
3298 : : static void
3772 rhaas@postgresql.org 3299 : 327577 : PinBuffer_Locked(BufferDesc *buf)
3300 : : {
3301 : : uint64 old_buf_state;
3302 : :
3303 : : /*
3304 : : * As explained, We don't expect any preexisting pins. That allows us to
3305 : : * manipulate the PrivateRefCount after releasing the spinlock
3306 : : */
3868 andres@anarazel.de 3307 [ - + ]: 327577 : Assert(GetPrivateRefCountEntry(BufferDescriptorGetBuffer(buf), false) == NULL);
3308 : :
3309 : : /*
3310 : : * Since we hold the buffer spinlock, we can update the buffer state and
3311 : : * release the lock in one operation.
3312 : : */
59 andres@anarazel.de 3313 :GNC 327577 : old_buf_state = pg_atomic_read_u64(&buf->state);
3314 : :
129 3315 : 327577 : UnlockBufHdrExt(buf, old_buf_state,
3316 : : 0, 0, 1);
3317 : :
158 3318 : 327577 : TrackNewBufferPin(BufferDescriptorGetBuffer(buf));
8000 tgl@sss.pgh.pa.us 3319 :CBC 327577 : }
3320 : :
3321 : : /*
3322 : : * Support for waking up another backend that is waiting for the cleanup lock
3323 : : * to be released using BM_PIN_COUNT_WAITER.
3324 : : *
3325 : : * See LockBufferForCleanup().
3326 : : *
3327 : : * Expected to be called just after releasing a buffer pin (in a BufferDesc,
3328 : : * not just reducing the backend-local pincount for the buffer).
3329 : : */
3330 : : static void
350 andres@anarazel.de 3331 : 94 : WakePinCountWaiter(BufferDesc *buf)
3332 : : {
3333 : : /*
3334 : : * Acquire the buffer header lock, re-check that there's a waiter. Another
3335 : : * backend could have unpinned this buffer, and already woken up the
3336 : : * waiter.
3337 : : *
3338 : : * There's no danger of the buffer being replaced after we unpinned it
3339 : : * above, as it's pinned by the waiter. The waiter removes
3340 : : * BM_PIN_COUNT_WAITER if it stops waiting for a reason other than this
3341 : : * backend waking it up.
3342 : : */
59 andres@anarazel.de 3343 :GNC 94 : uint64 buf_state = LockBufHdr(buf);
3344 : :
350 andres@anarazel.de 3345 [ + - ]:CBC 94 : if ((buf_state & BM_PIN_COUNT_WAITER) &&
3346 [ + + ]: 94 : BUF_STATE_GET_REFCOUNT(buf_state) == 1)
3347 : 92 : {
3348 : : /* we just released the last pin other than the waiter's */
3349 : 92 : int wait_backend_pgprocno = buf->wait_backend_pgprocno;
3350 : :
129 andres@anarazel.de 3351 :GNC 92 : UnlockBufHdrExt(buf, buf_state,
3352 : : 0, BM_PIN_COUNT_WAITER,
3353 : : 0);
350 andres@anarazel.de 3354 :CBC 92 : ProcSendSignal(wait_backend_pgprocno);
3355 : : }
3356 : : else
129 andres@anarazel.de 3357 :GNC 2 : UnlockBufHdr(buf);
350 andres@anarazel.de 3358 :CBC 94 : }
3359 : :
3360 : : /*
3361 : : * UnpinBuffer -- make buffer available for replacement.
3362 : : *
3363 : : * This should be applied only to shared buffers, never local ones. This
3364 : : * always adjusts CurrentResourceOwner.
3365 : : */
3366 : : static void
1262 michael@paquier.xyz 3367 : 76100078 : UnpinBuffer(BufferDesc *buf)
3368 : : {
858 heikki.linnakangas@i 3369 : 76100078 : Buffer b = BufferDescriptorGetBuffer(buf);
3370 : :
3371 : 76100078 : ResourceOwnerForgetBuffer(CurrentResourceOwner, b);
3372 : 76100078 : UnpinBufferNoOwner(buf);
3373 : 76100078 : }
3374 : :
3375 : : static void
3376 : 76104946 : UnpinBufferNoOwner(BufferDesc *buf)
3377 : : {
3378 : : PrivateRefCountEntry *ref;
3868 andres@anarazel.de 3379 : 76104946 : Buffer b = BufferDescriptorGetBuffer(buf);
3380 : :
1075 3381 [ - + ]: 76104946 : Assert(!BufferIsLocal(b));
3382 : :
3383 : : /* not moving as we're likely deleting it soon anyway */
3868 3384 : 76104946 : ref = GetPrivateRefCountEntry(b, false);
4215 3385 [ - + ]: 76104946 : Assert(ref != NULL);
91 andres@anarazel.de 3386 [ - + ]:GNC 76104946 : Assert(ref->data.refcount > 0);
3387 : 76104946 : ref->data.refcount--;
3388 [ + + ]: 76104946 : if (ref->data.refcount == 0)
3389 : : {
3390 : : uint64 old_buf_state;
3391 : :
3392 : : /*
3393 : : * Mark buffer non-accessible to Valgrind.
3394 : : *
3395 : : * Note that the buffer may have already been marked non-accessible
3396 : : * within access method code that enforces that buffers are only
3397 : : * accessed while a buffer lock is held.
3398 : : */
3399 : : VALGRIND_MAKE_MEM_NOACCESS(BufHdrGetBlock(buf), BLCKSZ);
3400 : :
3401 : : /*
3402 : : * I'd better not still hold the buffer content lock. Can't use
3403 : : * BufferIsLockedByMe(), as that asserts the buffer is pinned.
3404 : : */
59 3405 [ - + ]: 62139575 : Assert(!BufferLockHeldByMe(buf));
3406 : :
3407 : : /* decrement the shared reference count */
3408 : 62139575 : old_buf_state = pg_atomic_fetch_sub_u64(&buf->state, BUF_REFCOUNT_ONE);
3409 : :
3410 : : /* Support LockBufferForCleanup() */
129 3411 [ + + ]: 62139575 : if (old_buf_state & BM_PIN_COUNT_WAITER)
350 andres@anarazel.de 3412 :CBC 94 : WakePinCountWaiter(buf);
3413 : :
4215 3414 : 62139575 : ForgetPrivateRefCountEntry(ref);
3415 : : }
8000 tgl@sss.pgh.pa.us 3416 : 76104946 : }
3417 : :
3418 : : /*
3419 : : * Set up backend-local tracking of a buffer pinned the first time by this
3420 : : * backend.
3421 : : */
3422 : : inline void
158 andres@anarazel.de 3423 :GNC 62139575 : TrackNewBufferPin(Buffer buf)
3424 : : {
3425 : : PrivateRefCountEntry *ref;
3426 : :
3427 : 62139575 : ref = NewPrivateRefCountEntry(buf);
91 3428 : 62139575 : ref->data.refcount++;
3429 : :
158 3430 : 62139575 : ResourceOwnerRememberBuffer(CurrentResourceOwner, buf);
3431 : :
3432 : : /*
3433 : : * This is the first pin for this page by this backend, mark its page as
3434 : : * defined to valgrind. While the page contents might not actually be
3435 : : * valid yet, we don't currently guarantee that such pages are marked
3436 : : * undefined or non-accessible.
3437 : : *
3438 : : * It's not necessarily the prettiest to do this here, but otherwise we'd
3439 : : * need this block of code in multiple places.
3440 : : */
3441 : : VALGRIND_MAKE_MEM_DEFINED(BufHdrGetBlock(GetBufferDescriptor(buf - 1)),
3442 : : BLCKSZ);
3443 : 62139575 : }
3444 : :
3445 : : #define ST_SORT sort_checkpoint_bufferids
3446 : : #define ST_ELEMENT_TYPE CkptSortItem
3447 : : #define ST_COMPARE(a, b) ckpt_buforder_comparator(a, b)
3448 : : #define ST_SCOPE static
3449 : : #define ST_DEFINE
3450 : : #include "lib/sort_template.h"
3451 : :
3452 : : /*
3453 : : * BufferSync -- Write out all dirty buffers in the pool.
3454 : : *
3455 : : * This is called at checkpoint time to write out all dirty shared buffers.
3456 : : * The checkpoint request flags should be passed in. If CHECKPOINT_FAST is
3457 : : * set, we disable delays between writes; if CHECKPOINT_IS_SHUTDOWN,
3458 : : * CHECKPOINT_END_OF_RECOVERY or CHECKPOINT_FLUSH_UNLOGGED is set, we write
3459 : : * even unlogged buffers, which are otherwise skipped. The remaining flags
3460 : : * currently have no effect here.
3461 : : */
3462 : : static void
6835 tgl@sss.pgh.pa.us 3463 :CBC 1802 : BufferSync(int flags)
3464 : : {
3465 : : uint64 buf_state;
3466 : : int buf_id;
3467 : : int num_to_scan;
3468 : : int num_spaces;
3469 : : int num_processed;
3470 : : int num_written;
3677 andres@anarazel.de 3471 : 1802 : CkptTsStatus *per_ts_stat = NULL;
3472 : : Oid last_tsid;
3473 : : binaryheap *ts_heap;
3474 : : int i;
59 andres@anarazel.de 3475 :GNC 1802 : uint64 mask = BM_DIRTY;
3476 : : WritebackContext wb_context;
3477 : :
3478 : : /*
3479 : : * Unless this is a shutdown checkpoint or we have been explicitly told,
3480 : : * we write only permanent, dirty buffers. But at shutdown or end of
3481 : : * recovery, we write all dirty buffers.
3482 : : */
4164 andres@anarazel.de 3483 [ + + ]:CBC 1802 : if (!((flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY |
3484 : : CHECKPOINT_FLUSH_UNLOGGED))))
5182 rhaas@postgresql.org 3485 : 1003 : mask |= BM_PERMANENT;
3486 : :
3487 : : /*
3488 : : * Loop over all buffers, and mark the ones that need to be written with
3489 : : * BM_CHECKPOINT_NEEDED. Count them as we go (num_to_scan), so that we
3490 : : * can estimate how much work needs to be done.
3491 : : *
3492 : : * This allows us to write only those pages that were dirty when the
3493 : : * checkpoint began, and not those that get dirtied while it proceeds.
3494 : : * Whenever a page with BM_CHECKPOINT_NEEDED is written out, either by us
3495 : : * later in this function, or by normal backends or the bgwriter cleaning
3496 : : * scan, the flag is cleared. Any buffer dirtied after this point won't
3497 : : * have the flag set.
3498 : : *
3499 : : * Note that if we fail to write some buffer, we may leave buffers with
3500 : : * BM_CHECKPOINT_NEEDED still set. This is OK since any such buffer would
3501 : : * certainly need to be written for the next checkpoint attempt, too.
3502 : : */
3677 andres@anarazel.de 3503 : 1802 : num_to_scan = 0;
6835 tgl@sss.pgh.pa.us 3504 [ + + ]: 12440410 : for (buf_id = 0; buf_id < NBuffers; buf_id++)
3505 : : {
3772 rhaas@postgresql.org 3506 : 12438608 : BufferDesc *bufHdr = GetBufferDescriptor(buf_id);
59 andres@anarazel.de 3507 :GNC 12438608 : uint64 set_bits = 0;
3508 : :
3509 : : /*
3510 : : * Header spinlock is enough to examine BM_DIRTY, see comment in
3511 : : * SyncOneBuffer.
3512 : : */
3626 andres@anarazel.de 3513 :CBC 12438608 : buf_state = LockBufHdr(bufHdr);
3514 : :
3515 [ + + ]: 12438608 : if ((buf_state & mask) == mask)
3516 : : {
3517 : : CkptSortItem *item;
3518 : :
129 andres@anarazel.de 3519 :GNC 315826 : set_bits = BM_CHECKPOINT_NEEDED;
3520 : :
3677 andres@anarazel.de 3521 :CBC 315826 : item = &CkptBufferIds[num_to_scan++];
3522 : 315826 : item->buf_id = buf_id;
1299 rhaas@postgresql.org 3523 : 315826 : item->tsId = bufHdr->tag.spcOid;
3524 : 315826 : item->relNumber = BufTagGetRelNumber(&bufHdr->tag);
3525 : 315826 : item->forkNum = BufTagGetForkNum(&bufHdr->tag);
3677 andres@anarazel.de 3526 : 315826 : item->blockNum = bufHdr->tag.blockNum;
3527 : : }
3528 : :
129 andres@anarazel.de 3529 :GNC 12438608 : UnlockBufHdrExt(bufHdr, buf_state,
3530 : : set_bits, 0,
3531 : : 0);
3532 : :
3533 : : /* Check for barrier events in case NBuffers is large. */
2278 rhaas@postgresql.org 3534 [ - + ]:CBC 12438608 : if (ProcSignalBarrierPending)
2278 rhaas@postgresql.org 3535 :UBC 0 : ProcessProcSignalBarrier();
3536 : : }
3537 : :
3677 andres@anarazel.de 3538 [ + + ]:CBC 1802 : if (num_to_scan == 0)
6835 tgl@sss.pgh.pa.us 3539 : 699 : return; /* nothing to do */
3540 : :
3677 andres@anarazel.de 3541 : 1103 : WritebackContextInit(&wb_context, &checkpoint_flush_after);
3542 : :
3543 : : TRACE_POSTGRESQL_BUFFER_SYNC_START(NBuffers, num_to_scan);
3544 : :
3545 : : /*
3546 : : * Sort buffers that need to be written to reduce the likelihood of random
3547 : : * IO. The sorting is also important for the implementation of balancing
3548 : : * writes between tablespaces. Without balancing writes we'd potentially
3549 : : * end up writing to the tablespaces one-by-one; possibly overloading the
3550 : : * underlying system.
3551 : : */
1829 tmunro@postgresql.or 3552 : 1103 : sort_checkpoint_bufferids(CkptBufferIds, num_to_scan);
3553 : :
3677 andres@anarazel.de 3554 : 1103 : num_spaces = 0;
3555 : :
3556 : : /*
3557 : : * Allocate progress status for each tablespace with buffers that need to
3558 : : * be flushed. This requires the to-be-flushed array to be sorted.
3559 : : */
3560 : 1103 : last_tsid = InvalidOid;
3561 [ + + ]: 316929 : for (i = 0; i < num_to_scan; i++)
3562 : : {
3563 : : CkptTsStatus *s;
3564 : : Oid cur_tsid;
3565 : :
3566 : 315826 : cur_tsid = CkptBufferIds[i].tsId;
3567 : :
3568 : : /*
3569 : : * Grow array of per-tablespace status structs, every time a new
3570 : : * tablespace is found.
3571 : : */
3572 [ + + + + ]: 315826 : if (last_tsid == InvalidOid || last_tsid != cur_tsid)
3573 : 1673 : {
3574 : : Size sz;
3575 : :
3576 : 1673 : num_spaces++;
3577 : :
3578 : : /*
3579 : : * Not worth adding grow-by-power-of-2 logic here - even with a
3580 : : * few hundred tablespaces this should be fine.
3581 : : */
3582 : 1673 : sz = sizeof(CkptTsStatus) * num_spaces;
3583 : :
3584 [ + + ]: 1673 : if (per_ts_stat == NULL)
3585 : 1103 : per_ts_stat = (CkptTsStatus *) palloc(sz);
3586 : : else
3587 : 570 : per_ts_stat = (CkptTsStatus *) repalloc(per_ts_stat, sz);
3588 : :
3589 : 1673 : s = &per_ts_stat[num_spaces - 1];
3590 : 1673 : memset(s, 0, sizeof(*s));
3591 : 1673 : s->tsId = cur_tsid;
3592 : :
3593 : : /*
3594 : : * The first buffer in this tablespace. As CkptBufferIds is sorted
3595 : : * by tablespace all (s->num_to_scan) buffers in this tablespace
3596 : : * will follow afterwards.
3597 : : */
3598 : 1673 : s->index = i;
3599 : :
3600 : : /*
3601 : : * progress_slice will be determined once we know how many buffers
3602 : : * are in each tablespace, i.e. after this loop.
3603 : : */
3604 : :
3605 : 1673 : last_tsid = cur_tsid;
3606 : : }
3607 : : else
3608 : : {
3609 : 314153 : s = &per_ts_stat[num_spaces - 1];
3610 : : }
3611 : :
3612 : 315826 : s->num_to_scan++;
3613 : :
3614 : : /* Check for barrier events. */
2278 rhaas@postgresql.org 3615 [ - + ]: 315826 : if (ProcSignalBarrierPending)
2278 rhaas@postgresql.org 3616 :UBC 0 : ProcessProcSignalBarrier();
3617 : : }
3618 : :
3677 andres@anarazel.de 3619 [ - + ]:CBC 1103 : Assert(num_spaces > 0);
3620 : :
3621 : : /*
3622 : : * Build a min-heap over the write-progress in the individual tablespaces,
3623 : : * and compute how large a portion of the total progress a single
3624 : : * processed buffer is.
3625 : : */
3626 : 1103 : ts_heap = binaryheap_allocate(num_spaces,
3627 : : ts_ckpt_progress_comparator,
3628 : : NULL);
3629 : :
3630 [ + + ]: 2776 : for (i = 0; i < num_spaces; i++)
3631 : : {
3632 : 1673 : CkptTsStatus *ts_stat = &per_ts_stat[i];
3633 : :
3634 : 1673 : ts_stat->progress_slice = (float8) num_to_scan / ts_stat->num_to_scan;
3635 : :
3636 : 1673 : binaryheap_add_unordered(ts_heap, PointerGetDatum(ts_stat));
3637 : : }
3638 : :
3639 : 1103 : binaryheap_build(ts_heap);
3640 : :
3641 : : /*
3642 : : * Iterate through to-be-checkpointed buffers and write the ones (still)
3643 : : * marked with BM_CHECKPOINT_NEEDED. The writes are balanced between
3644 : : * tablespaces; otherwise the sorting would lead to only one tablespace
3645 : : * receiving writes at a time, making inefficient use of the hardware.
3646 : : */
3647 : 1103 : num_processed = 0;
6835 tgl@sss.pgh.pa.us 3648 : 1103 : num_written = 0;
3677 andres@anarazel.de 3649 [ + + ]: 316929 : while (!binaryheap_empty(ts_heap))
3650 : : {
3651 : 315826 : BufferDesc *bufHdr = NULL;
3652 : : CkptTsStatus *ts_stat = (CkptTsStatus *)
1031 tgl@sss.pgh.pa.us 3653 : 315826 : DatumGetPointer(binaryheap_first(ts_heap));
3654 : :
3677 andres@anarazel.de 3655 : 315826 : buf_id = CkptBufferIds[ts_stat->index].buf_id;
3656 [ - + ]: 315826 : Assert(buf_id != -1);
3657 : :
3658 : 315826 : bufHdr = GetBufferDescriptor(buf_id);
3659 : :
3660 : 315826 : num_processed++;
3661 : :
3662 : : /*
3663 : : * We don't need to acquire the lock here, because we're only looking
3664 : : * at a single bit. It's possible that someone else writes the buffer
3665 : : * and clears the flag right after we check, but that doesn't matter
3666 : : * since SyncOneBuffer will then do nothing. However, there is a
3667 : : * further race condition: it's conceivable that between the time we
3668 : : * examine the bit here and the time SyncOneBuffer acquires the lock,
3669 : : * someone else not only wrote the buffer but replaced it with another
3670 : : * page and dirtied it. In that improbable case, SyncOneBuffer will
3671 : : * write the buffer though we didn't need to. It doesn't seem worth
3672 : : * guarding against this, though.
3673 : : */
59 andres@anarazel.de 3674 [ + + ]:GNC 315826 : if (pg_atomic_read_u64(&bufHdr->state) & BM_CHECKPOINT_NEEDED)
3675 : : {
3677 andres@anarazel.de 3676 [ + - ]:CBC 293847 : if (SyncOneBuffer(buf_id, false, &wb_context) & BUF_WRITTEN)
3677 : : {
3678 : : TRACE_POSTGRESQL_BUFFER_SYNC_WRITTEN(buf_id);
867 michael@paquier.xyz 3679 : 293847 : PendingCheckpointerStats.buffers_written++;
6835 tgl@sss.pgh.pa.us 3680 : 293847 : num_written++;
3681 : : }
3682 : : }
3683 : :
3684 : : /*
3685 : : * Measure progress independent of actually having to flush the buffer
3686 : : * - otherwise writing become unbalanced.
3687 : : */
3677 andres@anarazel.de 3688 : 315826 : ts_stat->progress += ts_stat->progress_slice;
3689 : 315826 : ts_stat->num_scanned++;
3690 : 315826 : ts_stat->index++;
3691 : :
3692 : : /* Have all the buffers from the tablespace been processed? */
3693 [ + + ]: 315826 : if (ts_stat->num_scanned == ts_stat->num_to_scan)
3694 : : {
3695 : 1673 : binaryheap_remove_first(ts_heap);
3696 : : }
3697 : : else
3698 : : {
3699 : : /* update heap with the new progress */
3700 : 314153 : binaryheap_replace_first(ts_heap, PointerGetDatum(ts_stat));
3701 : : }
3702 : :
3703 : : /*
3704 : : * Sleep to throttle our I/O rate.
3705 : : *
3706 : : * (This will check for barrier events even if it doesn't sleep.)
3707 : : */
3708 : 315826 : CheckpointWriteDelay(flags, (double) num_processed / num_to_scan);
3709 : : }
3710 : :
3711 : : /*
3712 : : * Issue all pending flushes. Only checkpointer calls BufferSync(), so
3713 : : * IOContext will always be IOCONTEXT_NORMAL.
3714 : : */
1033 3715 : 1103 : IssuePendingWritebacks(&wb_context, IOCONTEXT_NORMAL);
3716 : :
3677 3717 : 1103 : pfree(per_ts_stat);
3718 : 1103 : per_ts_stat = NULL;
3719 : 1103 : binaryheap_free(ts_heap);
3720 : :
3721 : : /*
3722 : : * Update checkpoint statistics. As noted above, this doesn't include
3723 : : * buffers written by other backends or bgwriter scan.
3724 : : */
6833 tgl@sss.pgh.pa.us 3725 : 1103 : CheckpointStats.ckpt_bufs_written += num_written;
3726 : :
3727 : : TRACE_POSTGRESQL_BUFFER_SYNC_DONE(NBuffers, num_written, num_to_scan);
3728 : : }
3729 : :
3730 : : /*
3731 : : * BgBufferSync -- Write out some dirty buffers in the pool.
3732 : : *
3733 : : * This is called periodically by the background writer process.
3734 : : *
3735 : : * Returns true if it's appropriate for the bgwriter process to go into
3736 : : * low-power hibernation mode. (This happens if the strategy clock-sweep
3737 : : * has been "lapped" and no buffer allocations have occurred recently,
3738 : : * or if the bgwriter has been effectively disabled by setting
3739 : : * bgwriter_lru_maxpages to 0.)
3740 : : */
3741 : : bool
3677 andres@anarazel.de 3742 : 13592 : BgBufferSync(WritebackContext *wb_context)
3743 : : {
3744 : : /* info obtained from freelist.c */
3745 : : int strategy_buf_id;
3746 : : uint32 strategy_passes;
3747 : : uint32 recent_alloc;
3748 : :
3749 : : /*
3750 : : * Information saved between calls so we can determine the strategy
3751 : : * point's advance rate and avoid scanning already-cleaned buffers.
3752 : : */
3753 : : static bool saved_info_valid = false;
3754 : : static int prev_strategy_buf_id;
3755 : : static uint32 prev_strategy_passes;
3756 : : static int next_to_clean;
3757 : : static uint32 next_passes;
3758 : :
3759 : : /* Moving averages of allocation rate and clean-buffer density */
3760 : : static float smoothed_alloc = 0;
3761 : : static float smoothed_density = 10.0;
3762 : :
3763 : : /* Potentially these could be tunables, but for now, not */
6746 tgl@sss.pgh.pa.us 3764 : 13592 : float smoothing_samples = 16;
3765 : 13592 : float scan_whole_pool_milliseconds = 120000.0;
3766 : :
3767 : : /* Used to compute how far we scan ahead */
3768 : : long strategy_delta;
3769 : : int bufs_to_lap;
3770 : : int bufs_ahead;
3771 : : float scans_per_alloc;
3772 : : int reusable_buffers_est;
3773 : : int upcoming_alloc_est;
3774 : : int min_scan_buffers;
3775 : :
3776 : : /* Variables for the scanning loop proper */
3777 : : int num_to_scan;
3778 : : int num_written;
3779 : : int reusable_buffers;
3780 : :
3781 : : /* Variables for final smoothed_density update */
3782 : : long new_strategy_delta;
3783 : : uint32 new_recent_alloc;
3784 : :
3785 : : /*
3786 : : * Find out where the clock-sweep currently is, and how many buffer
3787 : : * allocations have happened since our last call.
3788 : : */
3789 : 13592 : strategy_buf_id = StrategySyncStart(&strategy_passes, &recent_alloc);
3790 : :
3791 : : /* Report buffer alloc counts to pgstat */
1439 andres@anarazel.de 3792 : 13592 : PendingBgWriterStats.buf_alloc += recent_alloc;
3793 : :
3794 : : /*
3795 : : * If we're not running the LRU scan, just stop after doing the stats
3796 : : * stuff. We mark the saved state invalid so that we can recover sanely
3797 : : * if LRU scan is turned back on later.
3798 : : */
6746 tgl@sss.pgh.pa.us 3799 [ + + ]: 13592 : if (bgwriter_lru_maxpages <= 0)
3800 : : {
3801 : 51 : saved_info_valid = false;
5162 heikki.linnakangas@i 3802 : 51 : return true;
3803 : : }
3804 : :
3805 : : /*
3806 : : * Compute strategy_delta = how many buffers have been scanned by the
3807 : : * clock-sweep since last time. If first time through, assume none. Then
3808 : : * see if we are still ahead of the clock-sweep, and if so, how many
3809 : : * buffers we could scan before we'd catch up with it and "lap" it. Note:
3810 : : * weird-looking coding of xxx_passes comparisons are to avoid bogus
3811 : : * behavior when the passes counts wrap around.
3812 : : */
6746 tgl@sss.pgh.pa.us 3813 [ + + ]: 13541 : if (saved_info_valid)
3814 : : {
6695 bruce@momjian.us 3815 : 12968 : int32 passes_delta = strategy_passes - prev_strategy_passes;
3816 : :
6746 tgl@sss.pgh.pa.us 3817 : 12968 : strategy_delta = strategy_buf_id - prev_strategy_buf_id;
3189 3818 : 12968 : strategy_delta += (long) passes_delta * NBuffers;
3819 : :
6746 3820 [ - + ]: 12968 : Assert(strategy_delta >= 0);
3821 : :
3822 [ + + ]: 12968 : if ((int32) (next_passes - strategy_passes) > 0)
3823 : : {
3824 : : /* we're one pass ahead of the strategy point */
3825 : 2531 : bufs_to_lap = strategy_buf_id - next_to_clean;
3826 : : #ifdef BGW_DEBUG
3827 : : elog(DEBUG2, "bgwriter ahead: bgw %u-%u strategy %u-%u delta=%ld lap=%d",
3828 : : next_passes, next_to_clean,
3829 : : strategy_passes, strategy_buf_id,
3830 : : strategy_delta, bufs_to_lap);
3831 : : #endif
3832 : : }
3833 [ + + ]: 10437 : else if (next_passes == strategy_passes &&
3834 [ + + ]: 7566 : next_to_clean >= strategy_buf_id)
3835 : : {
3836 : : /* on same pass, but ahead or at least not behind */
3837 : 6678 : bufs_to_lap = NBuffers - (next_to_clean - strategy_buf_id);
3838 : : #ifdef BGW_DEBUG
3839 : : elog(DEBUG2, "bgwriter ahead: bgw %u-%u strategy %u-%u delta=%ld lap=%d",
3840 : : next_passes, next_to_clean,
3841 : : strategy_passes, strategy_buf_id,
3842 : : strategy_delta, bufs_to_lap);
3843 : : #endif
3844 : : }
3845 : : else
3846 : : {
3847 : : /*
3848 : : * We're behind, so skip forward to the strategy point and start
3849 : : * cleaning from there.
3850 : : */
3851 : : #ifdef BGW_DEBUG
3852 : : elog(DEBUG2, "bgwriter behind: bgw %u-%u strategy %u-%u delta=%ld",
3853 : : next_passes, next_to_clean,
3854 : : strategy_passes, strategy_buf_id,
3855 : : strategy_delta);
3856 : : #endif
3857 : 3759 : next_to_clean = strategy_buf_id;
3858 : 3759 : next_passes = strategy_passes;
3859 : 3759 : bufs_to_lap = NBuffers;
3860 : : }
3861 : : }
3862 : : else
3863 : : {
3864 : : /*
3865 : : * Initializing at startup or after LRU scanning had been off. Always
3866 : : * start at the strategy point.
3867 : : */
3868 : : #ifdef BGW_DEBUG
3869 : : elog(DEBUG2, "bgwriter initializing: strategy %u-%u",
3870 : : strategy_passes, strategy_buf_id);
3871 : : #endif
3872 : 573 : strategy_delta = 0;
3873 : 573 : next_to_clean = strategy_buf_id;
3874 : 573 : next_passes = strategy_passes;
3875 : 573 : bufs_to_lap = NBuffers;
3876 : : }
3877 : :
3878 : : /* Update saved info for next time */
3879 : 13541 : prev_strategy_buf_id = strategy_buf_id;
3880 : 13541 : prev_strategy_passes = strategy_passes;
3881 : 13541 : saved_info_valid = true;
3882 : :
3883 : : /*
3884 : : * Compute how many buffers had to be scanned for each new allocation, ie,
3885 : : * 1/density of reusable buffers, and track a moving average of that.
3886 : : *
3887 : : * If the strategy point didn't move, we don't update the density estimate
3888 : : */
3889 [ + + + - ]: 13541 : if (strategy_delta > 0 && recent_alloc > 0)
3890 : : {
3891 : 8801 : scans_per_alloc = (float) strategy_delta / (float) recent_alloc;
3892 : 8801 : smoothed_density += (scans_per_alloc - smoothed_density) /
3893 : : smoothing_samples;
3894 : : }
3895 : :
3896 : : /*
3897 : : * Estimate how many reusable buffers there are between the current
3898 : : * strategy point and where we've scanned ahead to, based on the smoothed
3899 : : * density estimate.
3900 : : */
3901 : 13541 : bufs_ahead = NBuffers - bufs_to_lap;
3902 : 13541 : reusable_buffers_est = (float) bufs_ahead / smoothed_density;
3903 : :
3904 : : /*
3905 : : * Track a moving average of recent buffer allocations. Here, rather than
3906 : : * a true average we want a fast-attack, slow-decline behavior: we
3907 : : * immediately follow any increase.
3908 : : */
3909 [ + + ]: 13541 : if (smoothed_alloc <= (float) recent_alloc)
3910 : 2879 : smoothed_alloc = recent_alloc;
3911 : : else
3912 : 10662 : smoothed_alloc += ((float) recent_alloc - smoothed_alloc) /
3913 : : smoothing_samples;
3914 : :
3915 : : /* Scale the estimate by a GUC to allow more aggressive tuning. */
5230 3916 : 13541 : upcoming_alloc_est = (int) (smoothed_alloc * bgwriter_lru_multiplier);
3917 : :
3918 : : /*
3919 : : * If recent_alloc remains at zero for many cycles, smoothed_alloc will
3920 : : * eventually underflow to zero, and the underflows produce annoying
3921 : : * kernel warnings on some platforms. Once upcoming_alloc_est has gone to
3922 : : * zero, there's no point in tracking smaller and smaller values of
3923 : : * smoothed_alloc, so just reset it to exactly zero to avoid this
3924 : : * syndrome. It will pop back up as soon as recent_alloc increases.
3925 : : */
3926 [ + + ]: 13541 : if (upcoming_alloc_est == 0)
3927 : 1185 : smoothed_alloc = 0;
3928 : :
3929 : : /*
3930 : : * Even in cases where there's been little or no buffer allocation
3931 : : * activity, we want to make a small amount of progress through the buffer
3932 : : * cache so that as many reusable buffers as possible are clean after an
3933 : : * idle period.
3934 : : *
3935 : : * (scan_whole_pool_milliseconds / BgWriterDelay) computes how many times
3936 : : * the BGW will be called during the scan_whole_pool time; slice the
3937 : : * buffer pool into that many sections.
3938 : : */
6746 3939 : 13541 : min_scan_buffers = (int) (NBuffers / (scan_whole_pool_milliseconds / BgWriterDelay));
3940 : :
3941 [ + + ]: 13541 : if (upcoming_alloc_est < (min_scan_buffers + reusable_buffers_est))
3942 : : {
3943 : : #ifdef BGW_DEBUG
3944 : : elog(DEBUG2, "bgwriter: alloc_est=%d too small, using min=%d + reusable_est=%d",
3945 : : upcoming_alloc_est, min_scan_buffers, reusable_buffers_est);
3946 : : #endif
3947 : 6392 : upcoming_alloc_est = min_scan_buffers + reusable_buffers_est;
3948 : : }
3949 : :
3950 : : /*
3951 : : * Now write out dirty reusable buffers, working forward from the
3952 : : * next_to_clean point, until we have lapped the strategy scan, or cleaned
3953 : : * enough buffers to match our estimate of the next cycle's allocation
3954 : : * requirements, or hit the bgwriter_lru_maxpages limit.
3955 : : */
3956 : :
3957 : 13541 : num_to_scan = bufs_to_lap;
3958 : 13541 : num_written = 0;
3959 : 13541 : reusable_buffers = reusable_buffers_est;
3960 : :
3961 : : /* Execute the LRU scan */
3962 [ + + + + ]: 1915160 : while (num_to_scan > 0 && reusable_buffers < upcoming_alloc_est)
3963 : : {
3626 andres@anarazel.de 3964 : 1901620 : int sync_state = SyncOneBuffer(next_to_clean, true,
3965 : : wb_context);
3966 : :
6746 tgl@sss.pgh.pa.us 3967 [ + + ]: 1901620 : if (++next_to_clean >= NBuffers)
3968 : : {
3969 : 3590 : next_to_clean = 0;
3970 : 3590 : next_passes++;
3971 : : }
3972 : 1901620 : num_to_scan--;
3973 : :
3626 andres@anarazel.de 3974 [ + + ]: 1901620 : if (sync_state & BUF_WRITTEN)
3975 : : {
6746 tgl@sss.pgh.pa.us 3976 : 28736 : reusable_buffers++;
3977 [ + + ]: 28736 : if (++num_written >= bgwriter_lru_maxpages)
3978 : : {
1439 andres@anarazel.de 3979 : 1 : PendingBgWriterStats.maxwritten_clean++;
6746 tgl@sss.pgh.pa.us 3980 : 1 : break;
3981 : : }
3982 : : }
3626 andres@anarazel.de 3983 [ + + ]: 1872884 : else if (sync_state & BUF_REUSABLE)
6746 tgl@sss.pgh.pa.us 3984 : 1397876 : reusable_buffers++;
3985 : : }
3986 : :
1439 andres@anarazel.de 3987 : 13541 : PendingBgWriterStats.buf_written_clean += num_written;
3988 : :
3989 : : #ifdef BGW_DEBUG
3990 : : 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",
3991 : : recent_alloc, smoothed_alloc, strategy_delta, bufs_ahead,
3992 : : smoothed_density, reusable_buffers_est, upcoming_alloc_est,
3993 : : bufs_to_lap - num_to_scan,
3994 : : num_written,
3995 : : reusable_buffers - reusable_buffers_est);
3996 : : #endif
3997 : :
3998 : : /*
3999 : : * Consider the above scan as being like a new allocation scan.
4000 : : * Characterize its density and update the smoothed one based on it. This
4001 : : * effectively halves the moving average period in cases where both the
4002 : : * strategy and the background writer are doing some useful scanning,
4003 : : * which is helpful because a long memory isn't as desirable on the
4004 : : * density estimates.
4005 : : */
5058 tgl@sss.pgh.pa.us 4006 : 13541 : new_strategy_delta = bufs_to_lap - num_to_scan;
4007 : 13541 : new_recent_alloc = reusable_buffers - reusable_buffers_est;
4008 [ + + + + ]: 13541 : if (new_strategy_delta > 0 && new_recent_alloc > 0)
4009 : : {
4010 : 11724 : scans_per_alloc = (float) new_strategy_delta / (float) new_recent_alloc;
6746 4011 : 11724 : smoothed_density += (scans_per_alloc - smoothed_density) /
4012 : : smoothing_samples;
4013 : :
4014 : : #ifdef BGW_DEBUG
4015 : : elog(DEBUG2, "bgwriter: cleaner density alloc=%u scan=%ld density=%.2f new smoothed=%.2f",
4016 : : new_recent_alloc, new_strategy_delta,
4017 : : scans_per_alloc, smoothed_density);
4018 : : #endif
4019 : : }
4020 : :
4021 : : /* Return true if OK to hibernate */
5058 4022 [ + + + - ]: 13541 : return (bufs_to_lap == 0 && recent_alloc == 0);
4023 : : }
4024 : :
4025 : : /*
4026 : : * SyncOneBuffer -- process a single buffer during syncing.
4027 : : *
4028 : : * If skip_recently_used is true, we don't write currently-pinned buffers, nor
4029 : : * buffers marked recently used, as these are not replacement candidates.
4030 : : *
4031 : : * Returns a bitmask containing the following flag bits:
4032 : : * BUF_WRITTEN: we wrote the buffer.
4033 : : * BUF_REUSABLE: buffer is available for replacement, ie, it has
4034 : : * pin count 0 and usage count 0.
4035 : : *
4036 : : * (BUF_WRITTEN could be set in error if FlushBuffer finds the buffer clean
4037 : : * after locking it, but we don't care all that much.)
4038 : : */
4039 : : static int
3677 andres@anarazel.de 4040 : 2195467 : SyncOneBuffer(int buf_id, bool skip_recently_used, WritebackContext *wb_context)
4041 : : {
3772 rhaas@postgresql.org 4042 : 2195467 : BufferDesc *bufHdr = GetBufferDescriptor(buf_id);
6695 bruce@momjian.us 4043 : 2195467 : int result = 0;
4044 : : uint64 buf_state;
4045 : : BufferTag tag;
4046 : :
4047 : : /* Make sure we can handle the pin */
4073 andres@anarazel.de 4048 : 2195467 : ReservePrivateRefCountEntry();
858 heikki.linnakangas@i 4049 : 2195467 : ResourceOwnerEnlarge(CurrentResourceOwner);
4050 : :
4051 : : /*
4052 : : * Check whether buffer needs writing.
4053 : : *
4054 : : * We can make this check without taking the buffer content lock so long
4055 : : * as we mark pages dirty in access methods *before* logging changes with
4056 : : * XLogInsert(): if someone marks the buffer dirty just after our check we
4057 : : * don't worry because our checkpoint.redo points before log record for
4058 : : * upcoming changes and so we are not required to write such dirty buffer.
4059 : : */
3626 andres@anarazel.de 4060 : 2195467 : buf_state = LockBufHdr(bufHdr);
4061 : :
4062 [ + + ]: 2195467 : if (BUF_STATE_GET_REFCOUNT(buf_state) == 0 &&
4063 [ + + ]: 2189765 : BUF_STATE_GET_USAGECOUNT(buf_state) == 0)
4064 : : {
6746 tgl@sss.pgh.pa.us 4065 : 1428745 : result |= BUF_REUSABLE;
4066 : : }
4067 [ + + ]: 766722 : else if (skip_recently_used)
4068 : : {
4069 : : /* Caller told us not to write recently-used buffers */
129 andres@anarazel.de 4070 :GNC 475008 : UnlockBufHdr(bufHdr);
6746 tgl@sss.pgh.pa.us 4071 :CBC 475008 : return result;
4072 : : }
4073 : :
3626 andres@anarazel.de 4074 [ + + + + ]: 1720459 : if (!(buf_state & BM_VALID) || !(buf_state & BM_DIRTY))
4075 : : {
4076 : : /* It's clean, so nothing to do */
129 andres@anarazel.de 4077 :GNC 1397876 : UnlockBufHdr(bufHdr);
6746 tgl@sss.pgh.pa.us 4078 :CBC 1397876 : return result;
4079 : : }
4080 : :
4081 : : /*
4082 : : * Pin it, share-exclusive-lock it, write it. (FlushBuffer will do
4083 : : * nothing if the buffer is clean by the time we've locked it.)
4084 : : */
7681 4085 : 322583 : PinBuffer_Locked(bufHdr);
4086 : :
158 andres@anarazel.de 4087 :GNC 322583 : FlushUnlockedBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
4088 : :
3677 andres@anarazel.de 4089 :CBC 322583 : tag = bufHdr->tag;
4090 : :
1262 michael@paquier.xyz 4091 : 322583 : UnpinBuffer(bufHdr);
4092 : :
4093 : : /*
4094 : : * SyncOneBuffer() is only called by checkpointer and bgwriter, so
4095 : : * IOContext will always be IOCONTEXT_NORMAL.
4096 : : */
1033 andres@anarazel.de 4097 : 322583 : ScheduleBufferTagForWriteback(wb_context, IOCONTEXT_NORMAL, &tag);
4098 : :
6746 tgl@sss.pgh.pa.us 4099 : 322583 : return result | BUF_WRITTEN;
4100 : : }
4101 : :
4102 : : /*
4103 : : * AtEOXact_Buffers - clean up at end of transaction.
4104 : : *
4105 : : * As of PostgreSQL 8.0, buffer pins should get released by the
4106 : : * ResourceOwner mechanism. This routine is just a debugging
4107 : : * cross-check that no pins remain.
4108 : : */
4109 : : void
8622 4110 : 337792 : AtEOXact_Buffers(bool isCommit)
4111 : : {
4286 andres@anarazel.de 4112 : 337792 : CheckForBufferLeaks();
4113 : :
7820 tgl@sss.pgh.pa.us 4114 : 337792 : AtEOXact_LocalBuffers(isCommit);
4115 : :
4215 andres@anarazel.de 4116 [ - + ]: 337792 : Assert(PrivateRefCountOverflowed == 0);
4117 : 337792 : }
4118 : :
4119 : : /*
4120 : : * Initialize access to shared buffer pool
4121 : : *
4122 : : * This is called during backend startup (whether standalone or under the
4123 : : * postmaster). It sets up for this backend's access to the already-existing
4124 : : * buffer pool.
4125 : : */
4126 : : void
563 heikki.linnakangas@i 4127 : 21552 : InitBufferManagerAccess(void)
4128 : : {
4129 : : /*
4130 : : * An advisory limit on the number of pins each backend should hold, based
4131 : : * on shared_buffers and the maximum number of connections possible.
4132 : : * That's very pessimistic, but outside toy-sized shared_buffers it should
4133 : : * allow plenty of pins. LimitAdditionalPins() and
4134 : : * GetAdditionalPinLimit() can be used to check the remaining balance.
4135 : : */
366 tmunro@postgresql.or 4136 : 21552 : MaxProportionalPins = NBuffers / (MaxBackends + NUM_AUXILIARY_PROCS);
4137 : :
4215 andres@anarazel.de 4138 : 21552 : memset(&PrivateRefCountArray, 0, sizeof(PrivateRefCountArray));
91 andres@anarazel.de 4139 :GNC 21552 : memset(&PrivateRefCountArrayKeys, 0, sizeof(PrivateRefCountArrayKeys));
4140 : :
3 pg@bowt.ie 4141 : 21552 : PrivateRefCountHash = refcount_create(CurrentMemoryContext, 100, NULL);
4142 : :
4143 : : /*
4144 : : * AtProcExit_Buffers needs LWLock access, and thereby has to be called at
4145 : : * the corresponding phase of backend shutdown.
4146 : : */
1683 andres@anarazel.de 4147 [ - + ]:CBC 21552 : Assert(MyProc != NULL);
7524 tgl@sss.pgh.pa.us 4148 : 21552 : on_shmem_exit(AtProcExit_Buffers, 0);
4149 : 21552 : }
4150 : :
4151 : : /*
4152 : : * During backend exit, ensure that we released all shared-buffer locks and
4153 : : * assert that we have no remaining pins.
4154 : : */
4155 : : static void
4156 : 21552 : AtProcExit_Buffers(int code, Datum arg)
4157 : : {
7820 4158 : 21552 : UnlockBuffers();
4159 : :
4286 andres@anarazel.de 4160 : 21552 : CheckForBufferLeaks();
4161 : :
4162 : : /* localbuf.c needs a chance too */
4163 : 21552 : AtProcExit_LocalBuffers();
4164 : 21552 : }
4165 : :
4166 : : /*
4167 : : * CheckForBufferLeaks - ensure this backend holds no buffer pins
4168 : : *
4169 : : * As of PostgreSQL 8.0, buffer pins should get released by the
4170 : : * ResourceOwner mechanism. This routine is just a debugging
4171 : : * cross-check that no pins remain.
4172 : : */
4173 : : static void
4174 : 359344 : CheckForBufferLeaks(void)
4175 : : {
4176 : : #ifdef USE_ASSERT_CHECKING
4177 : 359344 : int RefCountErrors = 0;
4178 : : PrivateRefCountEntry *res;
4179 : : int i;
4180 : : char *s;
4181 : :
4182 : : /* check the array */
4215 4183 [ + + ]: 3234096 : for (i = 0; i < REFCOUNT_ARRAY_ENTRIES; i++)
4184 : : {
91 andres@anarazel.de 4185 [ - + ]:GNC 2874752 : if (PrivateRefCountArrayKeys[i] != InvalidBuffer)
4186 : : {
91 andres@anarazel.de 4187 :UNC 0 : res = &PrivateRefCountArray[i];
4188 : :
858 heikki.linnakangas@i 4189 :UBC 0 : s = DebugPrintBufferRefcount(res->buffer);
4190 [ # # ]: 0 : elog(WARNING, "buffer refcount leak: %s", s);
4191 : 0 : pfree(s);
4192 : :
4215 andres@anarazel.de 4193 : 0 : RefCountErrors++;
4194 : : }
4195 : : }
4196 : :
4197 : : /* if necessary search the hash */
4215 andres@anarazel.de 4198 [ - + ]:CBC 359344 : if (PrivateRefCountOverflowed)
4199 : : {
4200 : : refcount_iterator iter;
4201 : :
3 pg@bowt.ie 4202 :UNC 0 : refcount_start_iterate(PrivateRefCountHash, &iter);
4203 [ # # ]: 0 : while ((res = refcount_iterate(PrivateRefCountHash, &iter)) != NULL)
4204 : : {
858 heikki.linnakangas@i 4205 :UBC 0 : s = DebugPrintBufferRefcount(res->buffer);
4206 [ # # ]: 0 : elog(WARNING, "buffer refcount leak: %s", s);
4207 : 0 : pfree(s);
4286 andres@anarazel.de 4208 : 0 : RefCountErrors++;
4209 : : }
4210 : : }
4211 : :
4286 andres@anarazel.de 4212 [ - + ]:CBC 359344 : Assert(RefCountErrors == 0);
4213 : : #endif
7820 tgl@sss.pgh.pa.us 4214 : 359344 : }
4215 : :
4216 : : #ifdef USE_ASSERT_CHECKING
4217 : : /*
4218 : : * Check for exclusive-locked catalog buffers. This is the core of
4219 : : * AssertCouldGetRelation().
4220 : : *
4221 : : * A backend would self-deadlock on the content lock if the catalog scan read
4222 : : * the exclusive-locked buffer. The main threat is exclusive-locked buffers
4223 : : * of catalogs used in relcache, because a catcache search on any catalog may
4224 : : * build that catalog's relcache entry. We don't have an inventory of
4225 : : * catalogs relcache uses, so just check buffers of most catalogs.
4226 : : *
4227 : : * It's better to minimize waits while holding an exclusive buffer lock, so it
4228 : : * would be nice to broaden this check not to be catalog-specific. However,
4229 : : * bttextcmp() accesses pg_collation, and non-core opclasses might similarly
4230 : : * read tables. That is deadlock-free as long as there's no loop in the
4231 : : * dependency graph: modifying table A may cause an opclass to read table B,
4232 : : * but it must not cause a read of table A.
4233 : : */
4234 : : void
332 noah@leadboat.com 4235 : 116884225 : AssertBufferLocksPermitCatalogRead(void)
4236 : : {
4237 : : PrivateRefCountEntry *res;
4238 : :
4239 : : /* check the array */
59 andres@anarazel.de 4240 [ + + ]:GNC 1051958025 : for (int i = 0; i < REFCOUNT_ARRAY_ENTRIES; i++)
4241 : : {
4242 [ + + ]: 935073800 : if (PrivateRefCountArrayKeys[i] != InvalidBuffer)
4243 : : {
4244 : 26811066 : res = &PrivateRefCountArray[i];
4245 : :
4246 [ - + ]: 26811066 : if (res->buffer == InvalidBuffer)
59 andres@anarazel.de 4247 :UNC 0 : continue;
4248 : :
59 andres@anarazel.de 4249 :GNC 26811066 : AssertNotCatalogBufferLock(res->buffer, res->data.lockmode);
4250 : : }
4251 : : }
4252 : :
4253 : : /* if necessary search the hash */
4254 [ + + ]: 116884225 : if (PrivateRefCountOverflowed)
4255 : : {
4256 : : refcount_iterator iter;
4257 : :
3 pg@bowt.ie 4258 : 24667 : refcount_start_iterate(PrivateRefCountHash, &iter);
4259 [ + + ]: 334049 : while ((res = refcount_iterate(PrivateRefCountHash, &iter)) != NULL)
4260 : : {
59 andres@anarazel.de 4261 : 309382 : AssertNotCatalogBufferLock(res->buffer, res->data.lockmode);
4262 : : }
4263 : : }
332 noah@leadboat.com 4264 :CBC 116884225 : }
4265 : :
4266 : : static void
59 andres@anarazel.de 4267 :GNC 27120448 : AssertNotCatalogBufferLock(Buffer buffer, BufferLockMode mode)
4268 : : {
4269 : 27120448 : BufferDesc *bufHdr = GetBufferDescriptor(buffer - 1);
4270 : : BufferTag tag;
4271 : : Oid relid;
4272 : :
4273 [ + + ]: 27120448 : if (mode != BUFFER_LOCK_EXCLUSIVE)
332 noah@leadboat.com 4274 :CBC 27110264 : return;
4275 : :
4276 : 10184 : tag = bufHdr->tag;
4277 : :
4278 : : /*
4279 : : * This relNumber==relid assumption holds until a catalog experiences
4280 : : * VACUUM FULL or similar. After a command like that, relNumber will be
4281 : : * in the normal (non-catalog) range, and we lose the ability to detect
4282 : : * hazardous access to that catalog. Calling RelidByRelfilenumber() would
4283 : : * close that gap, but RelidByRelfilenumber() might then deadlock with a
4284 : : * held lock.
4285 : : */
4286 : 10184 : relid = tag.relNumber;
4287 : :
4288 [ - + ]: 10184 : if (IsCatalogTextUniqueIndexOid(relid)) /* see comments at the callee */
332 noah@leadboat.com 4289 :UBC 0 : return;
4290 : :
332 noah@leadboat.com 4291 [ - + ]:CBC 10184 : Assert(!IsCatalogRelationOid(relid));
4292 : : }
4293 : : #endif
4294 : :
4295 : :
4296 : : /*
4297 : : * Helper routine to issue warnings when a buffer is unexpectedly pinned
4298 : : */
4299 : : char *
858 heikki.linnakangas@i 4300 : 60 : DebugPrintBufferRefcount(Buffer buffer)
4301 : : {
4302 : : BufferDesc *buf;
4303 : : int32 loccount;
4304 : : char *result;
4305 : : ProcNumber backend;
4306 : : uint64 buf_state;
4307 : :
7820 tgl@sss.pgh.pa.us 4308 [ - + ]: 60 : Assert(BufferIsValid(buffer));
4309 [ + + ]: 60 : if (BufferIsLocal(buffer))
4310 : : {
4063 andres@anarazel.de 4311 : 24 : buf = GetLocalBufferDescriptor(-buffer - 1);
7820 tgl@sss.pgh.pa.us 4312 : 24 : loccount = LocalRefCount[-buffer - 1];
742 heikki.linnakangas@i 4313 : 24 : backend = MyProcNumber;
4314 : : }
4315 : : else
4316 : : {
4063 andres@anarazel.de 4317 : 36 : buf = GetBufferDescriptor(buffer - 1);
4215 4318 : 36 : loccount = GetPrivateRefCount(buffer);
742 heikki.linnakangas@i 4319 : 36 : backend = INVALID_PROC_NUMBER;
4320 : : }
4321 : :
4322 : : /* theoretically we should lock the bufHdr here */
59 andres@anarazel.de 4323 :GNC 60 : buf_state = pg_atomic_read_u64(&buf->state);
4324 : :
4325 : 60 : result = psprintf("[%03d] (rel=%s, blockNum=%u, flags=0x%" PRIx64 ", refcount=%u %d)",
4326 : : buffer,
383 andres@anarazel.de 4327 :CBC 60 : relpathbackend(BufTagGetRelFileLocator(&buf->tag), backend,
4328 : : BufTagGetForkNum(&buf->tag)).str,
4329 : : buf->tag.blockNum, buf_state & BUF_FLAG_MASK,
4330 : : BUF_STATE_GET_REFCOUNT(buf_state), loccount);
858 heikki.linnakangas@i 4331 : 60 : return result;
4332 : : }
4333 : :
4334 : : /*
4335 : : * CheckPointBuffers
4336 : : *
4337 : : * Flush all dirty blocks in buffer pool to disk at checkpoint time.
4338 : : *
4339 : : * Note: temporary relations do not participate in checkpoints, so they don't
4340 : : * need to be flushed.
4341 : : */
4342 : : void
6835 tgl@sss.pgh.pa.us 4343 : 1802 : CheckPointBuffers(int flags)
4344 : : {
4345 : 1802 : BufferSync(flags);
9236 vadim4o@yahoo.com 4346 : 1802 : }
4347 : :
4348 : : /*
4349 : : * BufferGetBlockNumber
4350 : : * Returns the block number associated with a buffer.
4351 : : *
4352 : : * Note:
4353 : : * Assumes that the buffer is valid and pinned, else the
4354 : : * value may be obsolete immediately...
4355 : : */
4356 : : BlockNumber
10841 scrappy@hub.org 4357 : 150669587 : BufferGetBlockNumber(Buffer buffer)
4358 : : {
4359 : : BufferDesc *bufHdr;
4360 : :
8735 bruce@momjian.us 4361 [ - + + + : 150669587 : Assert(BufferIsPinned(buffer));
- + ]
4362 : :
10416 4363 [ + + ]: 150669587 : if (BufferIsLocal(buffer))
4063 andres@anarazel.de 4364 : 4253287 : bufHdr = GetLocalBufferDescriptor(-buffer - 1);
4365 : : else
4366 : 146416300 : bufHdr = GetBufferDescriptor(buffer - 1);
4367 : :
4368 : : /* pinned, so OK to read tag without spinlock */
7681 tgl@sss.pgh.pa.us 4369 : 150669587 : return bufHdr->tag.blockNum;
4370 : : }
4371 : :
4372 : : /*
4373 : : * BufferGetTag
4374 : : * Returns the relfilelocator, fork number and block number associated with
4375 : : * a buffer.
4376 : : */
4377 : : void
1348 rhaas@postgresql.org 4378 : 17008296 : BufferGetTag(Buffer buffer, RelFileLocator *rlocator, ForkNumber *forknum,
4379 : : BlockNumber *blknum)
4380 : : {
4381 : : BufferDesc *bufHdr;
4382 : :
4383 : : /* Do the same checks as BufferGetBlockNumber. */
6425 heikki.linnakangas@i 4384 [ - + - + : 17008296 : Assert(BufferIsPinned(buffer));
- + ]
4385 : :
8000 tgl@sss.pgh.pa.us 4386 [ - + ]: 17008296 : if (BufferIsLocal(buffer))
4063 andres@anarazel.de 4387 :UBC 0 : bufHdr = GetLocalBufferDescriptor(-buffer - 1);
4388 : : else
4063 andres@anarazel.de 4389 :CBC 17008296 : bufHdr = GetBufferDescriptor(buffer - 1);
4390 : :
4391 : : /* pinned, so OK to read tag without spinlock */
1299 rhaas@postgresql.org 4392 : 17008296 : *rlocator = BufTagGetRelFileLocator(&bufHdr->tag);
4393 : 17008296 : *forknum = BufTagGetForkNum(&bufHdr->tag);
6425 heikki.linnakangas@i 4394 : 17008296 : *blknum = bufHdr->tag.blockNum;
8000 tgl@sss.pgh.pa.us 4395 : 17008296 : }
4396 : :
4397 : : /*
4398 : : * FlushBuffer
4399 : : * Physically write out a shared buffer.
4400 : : *
4401 : : * NOTE: this actually just passes the buffer contents to the kernel; the
4402 : : * real write to disk won't happen until the kernel feels like it. This
4403 : : * is okay from our point of view since we can redo the changes from WAL.
4404 : : * However, we will need to force the changes to disk via fsync before
4405 : : * we can checkpoint WAL.
4406 : : *
4407 : : * The caller must hold a pin on the buffer and have
4408 : : * (share-)exclusively-locked the buffer contents.
4409 : : *
4410 : : * If the caller has an smgr reference for the buffer's relation, pass it
4411 : : * as the second parameter. If not, pass NULL.
4412 : : */
4413 : : static void
1130 andres@anarazel.de 4414 : 598964 : FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object,
4415 : : IOContext io_context)
4416 : : {
4417 : : XLogRecPtr recptr;
4418 : : ErrorContextCallback errcallback;
4419 : : instr_time io_start;
4420 : : Block bufBlock;
4421 : : char *bufToWrite;
4422 : :
5 andres@anarazel.de 4423 [ + + - + ]:GNC 598964 : Assert(BufferLockHeldByMeInMode(buf, BUFFER_LOCK_EXCLUSIVE) ||
4424 : : BufferLockHeldByMeInMode(buf, BUFFER_LOCK_SHARE_EXCLUSIVE));
4425 : :
4426 : : /*
4427 : : * Try to start an I/O operation. If StartBufferIO returns false, then
4428 : : * someone else flushed the buffer before we could, so we need not do
4429 : : * anything.
4430 : : */
711 tmunro@postgresql.or 4431 [ + + ]:CBC 598964 : if (!StartBufferIO(buf, false, false))
7681 tgl@sss.pgh.pa.us 4432 : 4 : return;
4433 : :
4434 : : /* Setup error traceback support for ereport() */
4871 heikki.linnakangas@i 4435 : 598960 : errcallback.callback = shared_buffer_write_error_callback;
472 peter@eisentraut.org 4436 : 598960 : errcallback.arg = buf;
4871 heikki.linnakangas@i 4437 : 598960 : errcallback.previous = error_context_stack;
4438 : 598960 : error_context_stack = &errcallback;
4439 : :
4440 : : /* Find smgr relation for buffer */
7998 tgl@sss.pgh.pa.us 4441 [ + + ]: 598960 : if (reln == NULL)
742 heikki.linnakangas@i 4442 : 596263 : reln = smgropen(BufTagGetRelFileLocator(&buf->tag), INVALID_PROC_NUMBER);
4443 : :
4444 : : TRACE_POSTGRESQL_BUFFER_FLUSH_START(BufTagGetForkNum(&buf->tag),
4445 : : buf->tag.blockNum,
4446 : : reln->smgr_rlocator.locator.spcOid,
4447 : : reln->smgr_rlocator.locator.dbOid,
4448 : : reln->smgr_rlocator.locator.relNumber);
4449 : :
4450 : : /*
4451 : : * As we hold at least a share-exclusive lock on the buffer, the LSN
4452 : : * cannot change during the flush (and thus can't be torn).
4453 : : */
4741 simon@2ndQuadrant.co 4454 : 598960 : recptr = BufferGetLSN(buf);
4455 : :
4456 : : /*
4457 : : * Force XLOG flush up to buffer's LSN. This implements the basic WAL
4458 : : * rule that log updates must hit disk before any of the data-file changes
4459 : : * they describe do.
4460 : : *
4461 : : * However, this rule does not apply to unlogged relations, which will be
4462 : : * lost after a crash anyway. Most unlogged relation pages do not bear
4463 : : * LSNs since we never emit WAL records for them, and therefore flushing
4464 : : * up through the buffer LSN would be useless, but harmless. However,
4465 : : * some index AMs use LSNs internally to detect concurrent page
4466 : : * modifications, and therefore unlogged index pages bear "fake" LSNs
4467 : : * generated by XLogGetFakeLSN. It is unlikely but possible that the fake
4468 : : * LSN counter could advance past the WAL insertion point; and if it did
4469 : : * happen, attempting to flush WAL through that location would fail, with
4470 : : * disastrous system-wide consequences. To make sure that can't happen,
4471 : : * skip the flush if the buffer isn't permanent.
4472 : : */
4 andres@anarazel.de 4473 [ + + ]:GNC 598960 : if (pg_atomic_read_u64(&buf->state) & BM_PERMANENT)
4780 heikki.linnakangas@i 4474 :CBC 597160 : XLogFlush(recptr);
4475 : :
4476 : : /*
4477 : : * Now it's safe to write the buffer to disk. Note that no one else should
4478 : : * have been able to write it, while we were busy with log flushing,
4479 : : * because we got the exclusive right to perform I/O by setting the
4480 : : * BM_IO_IN_PROGRESS bit.
4481 : : */
4741 simon@2ndQuadrant.co 4482 : 598960 : bufBlock = BufHdrGetBlock(buf);
4483 : :
4484 : : /*
4485 : : * Update page checksum if desired. Since we have only shared lock on the
4486 : : * buffer, other processes might be updating hint bits in it, so we must
4487 : : * copy the page to private storage if we do checksumming.
4488 : : */
4489 : 598960 : bufToWrite = PageSetChecksumCopy((Page) bufBlock, buf->tag.blockNum);
4490 : :
382 michael@paquier.xyz 4491 : 598960 : io_start = pgstat_prepare_io_time(track_io_timing);
4492 : :
4493 : : /*
4494 : : * bufToWrite is either the shared buffer or a copy, as appropriate.
4495 : : */
8069 tgl@sss.pgh.pa.us 4496 : 598960 : smgrwrite(reln,
1299 rhaas@postgresql.org 4497 : 598960 : BufTagGetForkNum(&buf->tag),
4498 : : buf->tag.blockNum,
4499 : : bufToWrite,
4500 : : false);
4501 : :
4502 : : /*
4503 : : * When a strategy is in use, only flushes of dirty buffers already in the
4504 : : * strategy ring are counted as strategy writes (IOCONTEXT
4505 : : * [BULKREAD|BULKWRITE|VACUUM] IOOP_WRITE) for the purpose of IO
4506 : : * statistics tracking.
4507 : : *
4508 : : * If a shared buffer initially added to the ring must be flushed before
4509 : : * being used, this is counted as an IOCONTEXT_NORMAL IOOP_WRITE.
4510 : : *
4511 : : * If a shared buffer which was added to the ring later because the
4512 : : * current strategy buffer is pinned or in use or because all strategy
4513 : : * buffers were dirty and rejected (for BAS_BULKREAD operations only)
4514 : : * requires flushing, this is counted as an IOCONTEXT_NORMAL IOOP_WRITE
4515 : : * (from_ring will be false).
4516 : : *
4517 : : * When a strategy is not in use, the write can only be a "regular" write
4518 : : * of a dirty shared buffer (IOCONTEXT_NORMAL IOOP_WRITE).
4519 : : */
1073 andres@anarazel.de 4520 : 598960 : pgstat_count_io_op_time(IOOBJECT_RELATION, io_context,
4521 : : IOOP_WRITE, io_start, 1, BLCKSZ);
4522 : :
5934 rhaas@postgresql.org 4523 : 598960 : pgBufferUsage.shared_blks_written++;
4524 : :
4525 : : /*
4526 : : * Mark the buffer as clean and end the BM_IO_IN_PROGRESS state.
4527 : : */
350 andres@anarazel.de 4528 : 598960 : TerminateBufferIO(buf, true, 0, true, false);
4529 : :
4530 : : TRACE_POSTGRESQL_BUFFER_FLUSH_DONE(BufTagGetForkNum(&buf->tag),
4531 : : buf->tag.blockNum,
4532 : : reln->smgr_rlocator.locator.spcOid,
4533 : : reln->smgr_rlocator.locator.dbOid,
4534 : : reln->smgr_rlocator.locator.relNumber);
4535 : :
4536 : : /* Pop the error context stack */
4871 heikki.linnakangas@i 4537 : 598960 : error_context_stack = errcallback.previous;
4538 : : }
4539 : :
4540 : : /*
4541 : : * Convenience wrapper around FlushBuffer() that locks/unlocks the buffer
4542 : : * before/after calling FlushBuffer().
4543 : : */
4544 : : static void
158 andres@anarazel.de 4545 :GNC 326299 : FlushUnlockedBuffer(BufferDesc *buf, SMgrRelation reln,
4546 : : IOObject io_object, IOContext io_context)
4547 : : {
59 4548 : 326299 : Buffer buffer = BufferDescriptorGetBuffer(buf);
4549 : :
5 4550 : 326299 : BufferLockAcquire(buffer, buf, BUFFER_LOCK_SHARE_EXCLUSIVE);
158 4551 : 326299 : FlushBuffer(buf, reln, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
59 4552 : 326299 : BufferLockUnlock(buffer, buf);
158 4553 : 326299 : }
4554 : :
4555 : : /*
4556 : : * RelationGetNumberOfBlocksInFork
4557 : : * Determines the current number of pages in the specified relation fork.
4558 : : *
4559 : : * Note that the accuracy of the result will depend on the details of the
4560 : : * relation's storage. For builtin AMs it'll be accurate, but for external AMs
4561 : : * it might not be.
4562 : : */
4563 : : BlockNumber
5555 rhaas@postgresql.org 4564 :CBC 2410428 : RelationGetNumberOfBlocksInFork(Relation relation, ForkNumber forkNum)
4565 : : {
1563 peter@eisentraut.org 4566 [ + + + + : 2410428 : if (RELKIND_HAS_TABLE_AM(relation->rd_rel->relkind))
+ + ]
4567 : : {
4568 : : /*
4569 : : * Not every table AM uses BLCKSZ wide fixed size blocks. Therefore
4570 : : * tableam returns the size in bytes - but for the purpose of this
4571 : : * routine, we want the number of blocks. Therefore divide, rounding
4572 : : * up.
4573 : : */
4574 : : uint64 szbytes;
4575 : :
4576 : 1904487 : szbytes = table_relation_size(relation, forkNum);
4577 : :
4578 : 1904468 : return (szbytes + (BLCKSZ - 1)) / BLCKSZ;
4579 : : }
4580 [ + - + + : 505941 : else if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind))
- + - - -
- ]
4581 : : {
1403 tgl@sss.pgh.pa.us 4582 : 505941 : return smgrnblocks(RelationGetSmgr(relation), forkNum);
4583 : : }
4584 : : else
1563 peter@eisentraut.org 4585 :UBC 0 : Assert(false);
4586 : :
4587 : : return 0; /* keep compiler quiet */
4588 : : }
4589 : :
4590 : : /*
4591 : : * BufferIsPermanent
4592 : : * Determines whether a buffer will potentially still be around after
4593 : : * a crash. Caller must hold a buffer pin.
4594 : : */
4595 : : bool
5252 rhaas@postgresql.org 4596 :CBC 10397459 : BufferIsPermanent(Buffer buffer)
4597 : : {
4598 : : BufferDesc *bufHdr;
4599 : :
4600 : : /* Local buffers are used only for temp relations. */
4601 [ + + ]: 10397459 : if (BufferIsLocal(buffer))
4602 : 739269 : return false;
4603 : :
4604 : : /* Make sure we've got a real buffer, and that we hold a pin on it. */
4605 [ - + ]: 9658190 : Assert(BufferIsValid(buffer));
4606 [ - + - + : 9658190 : Assert(BufferIsPinned(buffer));
- + ]
4607 : :
4608 : : /*
4609 : : * BM_PERMANENT can't be changed while we hold a pin on the buffer, so we
4610 : : * need not bother with the buffer header spinlock. Even if someone else
4611 : : * changes the buffer header state while we're doing this, the state is
4612 : : * changed atomically, so we'll read the old value or the new value, but
4613 : : * not random garbage.
4614 : : */
4063 andres@anarazel.de 4615 : 9658190 : bufHdr = GetBufferDescriptor(buffer - 1);
59 andres@anarazel.de 4616 :GNC 9658190 : return (pg_atomic_read_u64(&bufHdr->state) & BM_PERMANENT) != 0;
4617 : : }
4618 : :
4619 : : /*
4620 : : * BufferGetLSNAtomic
4621 : : * Retrieves the LSN of the buffer atomically.
4622 : : *
4623 : : * This is necessary for some callers who may only hold a share lock on
4624 : : * the buffer. A share lock allows a concurrent backend to set hint bits
4625 : : * on the page, which in turn may require a WAL record to be emitted.
4626 : : *
4627 : : * On platforms with 8 byte atomic reads/writes, we don't need to do any
4628 : : * additional locking. On platforms not supporting such 8 byte atomic
4629 : : * reads/writes, we need to actually take the header lock.
4630 : : */
4631 : : XLogRecPtr
4741 simon@2ndQuadrant.co 4632 :CBC 6530211 : BufferGetLSNAtomic(Buffer buffer)
4633 : : {
4634 : : /* Make sure we've got a real buffer, and that we hold a pin on it. */
4635 [ - + ]: 6530211 : Assert(BufferIsValid(buffer));
4636 [ - + + + : 6530211 : Assert(BufferIsPinned(buffer));
- + ]
4637 : :
4638 : : #ifdef PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY
4 tomas.vondra@postgre 4639 :GNC 6530211 : return PageGetLSN(BufferGetPage(buffer));
4640 : : #else
4641 : : {
4642 : : char *page = BufferGetPage(buffer);
4643 : : BufferDesc *bufHdr;
4644 : : XLogRecPtr lsn;
4645 : :
4646 : : /*
4647 : : * If we don't need locking for correctness, fastpath out.
4648 : : */
4649 : : if (!XLogHintBitIsNeeded() || BufferIsLocal(buffer))
4650 : : return PageGetLSN(page);
4651 : :
4652 : : bufHdr = GetBufferDescriptor(buffer - 1);
4653 : : LockBufHdr(bufHdr);
4654 : : lsn = PageGetLSN(page);
4655 : : UnlockBufHdr(bufHdr);
4656 : :
4657 : : return lsn;
4658 : : }
4659 : : #endif
4660 : : }
4661 : :
4662 : : /* ---------------------------------------------------------------------
4663 : : * DropRelationBuffers
4664 : : *
4665 : : * This function removes from the buffer pool all the pages of the
4666 : : * specified relation forks that have block numbers >= firstDelBlock.
4667 : : * (In particular, with firstDelBlock = 0, all pages are removed.)
4668 : : * Dirty pages are simply dropped, without bothering to write them
4669 : : * out first. Therefore, this is NOT rollback-able, and so should be
4670 : : * used only with extreme caution!
4671 : : *
4672 : : * Currently, this is called only from smgr.c when the underlying file
4673 : : * is about to be deleted or truncated (firstDelBlock is needed for
4674 : : * the truncation case). The data in the affected pages would therefore
4675 : : * be deleted momentarily anyway, and there is no point in writing it.
4676 : : * It is the responsibility of higher-level code to ensure that the
4677 : : * deletion or truncation does not lose any data that could be needed
4678 : : * later. It is also the responsibility of higher-level code to ensure
4679 : : * that no other process could be trying to load more pages of the
4680 : : * relation into buffers.
4681 : : * --------------------------------------------------------------------
4682 : : */
4683 : : void
1342 rhaas@postgresql.org 4684 :CBC 626 : DropRelationBuffers(SMgrRelation smgr_reln, ForkNumber *forkNum,
4685 : : int nforks, BlockNumber *firstDelBlock)
4686 : : {
4687 : : int i;
4688 : : int j;
4689 : : RelFileLocatorBackend rlocator;
4690 : : BlockNumber nForkBlock[MAX_FORKNUM];
1768 tgl@sss.pgh.pa.us 4691 : 626 : uint64 nBlocksToInvalidate = 0;
4692 : :
1348 rhaas@postgresql.org 4693 : 626 : rlocator = smgr_reln->smgr_rlocator;
4694 : :
4695 : : /* If it's a local relation, it's localbuf.c's problem. */
4696 [ + + ]: 626 : if (RelFileLocatorBackendIsTemp(rlocator))
4697 : : {
742 heikki.linnakangas@i 4698 [ + - ]: 375 : if (rlocator.backend == MyProcNumber)
254 fujii@postgresql.org 4699 :GNC 375 : DropRelationLocalBuffers(rlocator.locator, forkNum, nforks,
4700 : : firstDelBlock);
4701 : :
8622 tgl@sss.pgh.pa.us 4702 :CBC 416 : return;
4703 : : }
4704 : :
4705 : : /*
4706 : : * To remove all the pages of the specified relation forks from the buffer
4707 : : * pool, we need to scan the entire buffer pool but we can optimize it by
4708 : : * finding the buffers from BufMapping table provided we know the exact
4709 : : * size of each fork of the relation. The exact size is required to ensure
4710 : : * that we don't leave any buffer for the relation being dropped as
4711 : : * otherwise the background writer or checkpointer can lead to a PANIC
4712 : : * error while flushing buffers corresponding to files that don't exist.
4713 : : *
4714 : : * To know the exact size, we rely on the size cached for each fork by us
4715 : : * during recovery which limits the optimization to recovery and on
4716 : : * standbys but we can easily extend it once we have shared cache for
4717 : : * relation size.
4718 : : *
4719 : : * In recovery, we cache the value returned by the first lseek(SEEK_END)
4720 : : * and the future writes keeps the cached value up-to-date. See
4721 : : * smgrextend. It is possible that the value of the first lseek is smaller
4722 : : * than the actual number of existing blocks in the file due to buggy
4723 : : * Linux kernels that might not have accounted for the recent write. But
4724 : : * that should be fine because there must not be any buffers after that
4725 : : * file size.
4726 : : */
1888 akapila@postgresql.o 4727 [ + + ]: 352 : for (i = 0; i < nforks; i++)
4728 : : {
4729 : : /* Get the number of blocks for a relation's fork */
4730 : 298 : nForkBlock[i] = smgrnblocks_cached(smgr_reln, forkNum[i]);
4731 : :
4732 [ + + ]: 298 : if (nForkBlock[i] == InvalidBlockNumber)
4733 : : {
4734 : 197 : nBlocksToInvalidate = InvalidBlockNumber;
4735 : 197 : break;
4736 : : }
4737 : :
4738 : : /* calculate the number of blocks to be invalidated */
4739 : 101 : nBlocksToInvalidate += (nForkBlock[i] - firstDelBlock[i]);
4740 : : }
4741 : :
4742 : : /*
4743 : : * We apply the optimization iff the total number of blocks to invalidate
4744 : : * is below the BUF_DROP_FULL_SCAN_THRESHOLD.
4745 : : */
4746 [ + + ]: 251 : if (BlockNumberIsValid(nBlocksToInvalidate) &&
4747 [ + + ]: 54 : nBlocksToInvalidate < BUF_DROP_FULL_SCAN_THRESHOLD)
4748 : : {
4749 [ + + ]: 111 : for (j = 0; j < nforks; j++)
1342 rhaas@postgresql.org 4750 : 70 : FindAndDropRelationBuffers(rlocator.locator, forkNum[j],
4751 : 70 : nForkBlock[j], firstDelBlock[j]);
1888 akapila@postgresql.o 4752 : 41 : return;
4753 : : }
4754 : :
7681 tgl@sss.pgh.pa.us 4755 [ + + ]: 2660562 : for (i = 0; i < NBuffers; i++)
4756 : : {
3772 rhaas@postgresql.org 4757 : 2660352 : BufferDesc *bufHdr = GetBufferDescriptor(i);
4758 : :
4759 : : /*
4760 : : * We can make this a tad faster by prechecking the buffer tag before
4761 : : * we attempt to lock the buffer; this saves a lot of lock
4762 : : * acquisitions in typical cases. It should be safe because the
4763 : : * caller must have AccessExclusiveLock on the relation, or some other
4764 : : * reason to be certain that no one is loading new pages of the rel
4765 : : * into the buffer pool. (Otherwise we might well miss such pages
4766 : : * entirely.) Therefore, while the tag might be changing while we
4767 : : * look at it, it can't be changing *to* a value we care about, only
4768 : : * *away* from such a value. So false negatives are impossible, and
4769 : : * false positives are safe because we'll recheck after getting the
4770 : : * buffer lock.
4771 : : *
4772 : : * We could check forkNum and blockNum as well as the rlocator, but
4773 : : * the incremental win from doing so seems small.
4774 : : */
1299 4775 [ + + ]: 2660352 : if (!BufTagMatchesRelFileLocator(&bufHdr->tag, &rlocator.locator))
5029 tgl@sss.pgh.pa.us 4776 : 2651168 : continue;
4777 : :
129 andres@anarazel.de 4778 :GNC 9184 : LockBufHdr(bufHdr);
4779 : :
2364 fujii@postgresql.org 4780 [ + + ]:CBC 22852 : for (j = 0; j < nforks; j++)
4781 : : {
1299 rhaas@postgresql.org 4782 [ + - ]: 16160 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rlocator.locator) &&
4783 [ + + ]: 16160 : BufTagGetForkNum(&bufHdr->tag) == forkNum[j] &&
2364 fujii@postgresql.org 4784 [ + + ]: 9069 : bufHdr->tag.blockNum >= firstDelBlock[j])
4785 : : {
2131 tgl@sss.pgh.pa.us 4786 : 2492 : InvalidateBuffer(bufHdr); /* releases spinlock */
2364 fujii@postgresql.org 4787 : 2492 : break;
4788 : : }
4789 : : }
4790 [ + + ]: 9184 : if (j >= nforks)
129 andres@anarazel.de 4791 :GNC 6692 : UnlockBufHdr(bufHdr);
4792 : : }
4793 : : }
4794 : :
4795 : : /* ---------------------------------------------------------------------
4796 : : * DropRelationsAllBuffers
4797 : : *
4798 : : * This function removes from the buffer pool all the pages of all
4799 : : * forks of the specified relations. It's equivalent to calling
4800 : : * DropRelationBuffers once per fork per relation with firstDelBlock = 0.
4801 : : * --------------------------------------------------------------------
4802 : : */
4803 : : void
1342 rhaas@postgresql.org 4804 :CBC 14456 : DropRelationsAllBuffers(SMgrRelation *smgr_reln, int nlocators)
4805 : : {
4806 : : int i;
1887 akapila@postgresql.o 4807 : 14456 : int n = 0;
4808 : : SMgrRelation *rels;
4809 : : BlockNumber (*block)[MAX_FORKNUM + 1];
1768 tgl@sss.pgh.pa.us 4810 : 14456 : uint64 nBlocksToInvalidate = 0;
4811 : : RelFileLocator *locators;
1887 akapila@postgresql.o 4812 : 14456 : bool cached = true;
4813 : : bool use_bsearch;
4814 : :
1348 rhaas@postgresql.org 4815 [ - + ]: 14456 : if (nlocators == 0)
4805 alvherre@alvh.no-ip. 4816 :UBC 0 : return;
4817 : :
94 michael@paquier.xyz 4818 :GNC 14456 : rels = palloc_array(SMgrRelation, nlocators); /* non-local relations */
4819 : :
4820 : : /* If it's a local relation, it's localbuf.c's problem. */
1348 rhaas@postgresql.org 4821 [ + + ]:CBC 63075 : for (i = 0; i < nlocators; i++)
4822 : : {
4823 [ + + ]: 48619 : if (RelFileLocatorBackendIsTemp(smgr_reln[i]->smgr_rlocator))
4824 : : {
742 heikki.linnakangas@i 4825 [ + - ]: 3311 : if (smgr_reln[i]->smgr_rlocator.backend == MyProcNumber)
1342 rhaas@postgresql.org 4826 : 3311 : DropRelationAllLocalBuffers(smgr_reln[i]->smgr_rlocator.locator);
4827 : : }
4828 : : else
1887 akapila@postgresql.o 4829 : 45308 : rels[n++] = smgr_reln[i];
4830 : : }
4831 : :
4832 : : /*
4833 : : * If there are no non-local relations, then we're done. Release the
4834 : : * memory and return.
4835 : : */
4805 alvherre@alvh.no-ip. 4836 [ + + ]: 14456 : if (n == 0)
4837 : : {
1887 akapila@postgresql.o 4838 : 891 : pfree(rels);
5029 tgl@sss.pgh.pa.us 4839 : 891 : return;
4840 : : }
4841 : :
4842 : : /*
4843 : : * This is used to remember the number of blocks for all the relations
4844 : : * forks.
4845 : : */
4846 : : block = (BlockNumber (*)[MAX_FORKNUM + 1])
1887 akapila@postgresql.o 4847 : 13565 : palloc(sizeof(BlockNumber) * n * (MAX_FORKNUM + 1));
4848 : :
4849 : : /*
4850 : : * We can avoid scanning the entire buffer pool if we know the exact size
4851 : : * of each of the given relation forks. See DropRelationBuffers.
4852 : : */
4853 [ + + + + ]: 28418 : for (i = 0; i < n && cached; i++)
4854 : : {
1299 drowley@postgresql.o 4855 [ + + ]: 23363 : for (int j = 0; j <= MAX_FORKNUM; j++)
4856 : : {
4857 : : /* Get the number of blocks for a relation's fork. */
1887 akapila@postgresql.o 4858 : 21249 : block[i][j] = smgrnblocks_cached(rels[i], j);
4859 : :
4860 : : /* We need to only consider the relation forks that exists. */
4861 [ + + ]: 21249 : if (block[i][j] == InvalidBlockNumber)
4862 : : {
4863 [ + + ]: 18971 : if (!smgrexists(rels[i], j))
4864 : 6232 : continue;
4865 : 12739 : cached = false;
4866 : 12739 : break;
4867 : : }
4868 : :
4869 : : /* calculate the total number of blocks to be invalidated */
4870 : 2278 : nBlocksToInvalidate += block[i][j];
4871 : : }
4872 : : }
4873 : :
4874 : : /*
4875 : : * We apply the optimization iff the total number of blocks to invalidate
4876 : : * is below the BUF_DROP_FULL_SCAN_THRESHOLD.
4877 : : */
4878 [ + + + + ]: 13565 : if (cached && nBlocksToInvalidate < BUF_DROP_FULL_SCAN_THRESHOLD)
4879 : : {
4880 [ + + ]: 1380 : for (i = 0; i < n; i++)
4881 : : {
1299 drowley@postgresql.o 4882 [ + + ]: 3795 : for (int j = 0; j <= MAX_FORKNUM; j++)
4883 : : {
4884 : : /* ignore relation forks that doesn't exist */
1887 akapila@postgresql.o 4885 [ + + ]: 3036 : if (!BlockNumberIsValid(block[i][j]))
4886 : 2266 : continue;
4887 : :
4888 : : /* drop all the buffers for a particular relation fork */
1342 rhaas@postgresql.org 4889 : 770 : FindAndDropRelationBuffers(rels[i]->smgr_rlocator.locator,
4890 : 770 : j, block[i][j], 0);
4891 : : }
4892 : : }
4893 : :
1887 akapila@postgresql.o 4894 : 621 : pfree(block);
4895 : 621 : pfree(rels);
4896 : 621 : return;
4897 : : }
4898 : :
4899 : 12944 : pfree(block);
94 michael@paquier.xyz 4900 :GNC 12944 : locators = palloc_array(RelFileLocator, n); /* non-local relations */
1887 akapila@postgresql.o 4901 [ + + ]:CBC 57493 : for (i = 0; i < n; i++)
1348 rhaas@postgresql.org 4902 : 44549 : locators[i] = rels[i]->smgr_rlocator.locator;
4903 : :
4904 : : /*
4905 : : * For low number of relations to drop just use a simple walk through, to
4906 : : * save the bsearch overhead. The threshold to use is rather a guess than
4907 : : * an exactly determined value, as it depends on many factors (CPU and RAM
4908 : : * speeds, amount of shared buffers etc.).
4909 : : */
2171 noah@leadboat.com 4910 : 12944 : use_bsearch = n > RELS_BSEARCH_THRESHOLD;
4911 : :
4912 : : /* sort the list of rlocators if necessary */
4805 alvherre@alvh.no-ip. 4913 [ + + ]: 12944 : if (use_bsearch)
758 nathan@postgresql.or 4914 : 178 : qsort(locators, n, sizeof(RelFileLocator), rlocator_comparator);
4915 : :
5029 tgl@sss.pgh.pa.us 4916 [ + + ]: 139146768 : for (i = 0; i < NBuffers; i++)
4917 : : {
1348 rhaas@postgresql.org 4918 : 139133824 : RelFileLocator *rlocator = NULL;
3772 4919 : 139133824 : BufferDesc *bufHdr = GetBufferDescriptor(i);
4920 : :
4921 : : /*
4922 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
4923 : : * saves some cycles.
4924 : : */
4925 : :
4805 alvherre@alvh.no-ip. 4926 [ + + ]: 139133824 : if (!use_bsearch)
4927 : : {
4928 : : int j;
4929 : :
4930 [ + + ]: 556823986 : for (j = 0; j < n; j++)
4931 : : {
1299 rhaas@postgresql.org 4932 [ + + ]: 419687529 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &locators[j]))
4933 : : {
1348 4934 : 88887 : rlocator = &locators[j];
4805 alvherre@alvh.no-ip. 4935 : 88887 : break;
4936 : : }
4937 : : }
4938 : : }
4939 : : else
4940 : : {
4941 : : RelFileLocator locator;
4942 : :
1299 rhaas@postgresql.org 4943 : 1908480 : locator = BufTagGetRelFileLocator(&bufHdr->tag);
464 peter@eisentraut.org 4944 : 1908480 : rlocator = bsearch(&locator,
4945 : : locators, n, sizeof(RelFileLocator),
4946 : : rlocator_comparator);
4947 : : }
4948 : :
4949 : : /* buffer doesn't belong to any of the given relfilelocators; skip it */
1348 rhaas@postgresql.org 4950 [ + + ]: 139133824 : if (rlocator == NULL)
5029 tgl@sss.pgh.pa.us 4951 : 139043412 : continue;
4952 : :
129 andres@anarazel.de 4953 :GNC 90412 : LockBufHdr(bufHdr);
1299 rhaas@postgresql.org 4954 [ + - ]:CBC 90412 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, rlocator))
5029 tgl@sss.pgh.pa.us 4955 : 90412 : InvalidateBuffer(bufHdr); /* releases spinlock */
4956 : : else
129 andres@anarazel.de 4957 :UNC 0 : UnlockBufHdr(bufHdr);
4958 : : }
4959 : :
1348 rhaas@postgresql.org 4960 :CBC 12944 : pfree(locators);
1887 akapila@postgresql.o 4961 : 12944 : pfree(rels);
4962 : : }
4963 : :
4964 : : /* ---------------------------------------------------------------------
4965 : : * FindAndDropRelationBuffers
4966 : : *
4967 : : * This function performs look up in BufMapping table and removes from the
4968 : : * buffer pool all the pages of the specified relation fork that has block
4969 : : * number >= firstDelBlock. (In particular, with firstDelBlock = 0, all
4970 : : * pages are removed.)
4971 : : * --------------------------------------------------------------------
4972 : : */
4973 : : static void
1342 rhaas@postgresql.org 4974 : 840 : FindAndDropRelationBuffers(RelFileLocator rlocator, ForkNumber forkNum,
4975 : : BlockNumber nForkBlock,
4976 : : BlockNumber firstDelBlock)
4977 : : {
4978 : : BlockNumber curBlock;
4979 : :
1888 akapila@postgresql.o 4980 [ + + ]: 2018 : for (curBlock = firstDelBlock; curBlock < nForkBlock; curBlock++)
4981 : : {
4982 : : uint32 bufHash; /* hash value for tag */
4983 : : BufferTag bufTag; /* identity of requested block */
4984 : : LWLock *bufPartitionLock; /* buffer partition lock for it */
4985 : : int buf_id;
4986 : : BufferDesc *bufHdr;
4987 : :
4988 : : /* create a tag so we can lookup the buffer */
1327 rhaas@postgresql.org 4989 : 1178 : InitBufferTag(&bufTag, &rlocator, forkNum, curBlock);
4990 : :
4991 : : /* determine its hash code and partition lock ID */
1888 akapila@postgresql.o 4992 : 1178 : bufHash = BufTableHashCode(&bufTag);
4993 : 1178 : bufPartitionLock = BufMappingPartitionLock(bufHash);
4994 : :
4995 : : /* Check that it is in the buffer pool. If not, do nothing. */
4996 : 1178 : LWLockAcquire(bufPartitionLock, LW_SHARED);
4997 : 1178 : buf_id = BufTableLookup(&bufTag, bufHash);
4998 : 1178 : LWLockRelease(bufPartitionLock);
4999 : :
5000 [ + + ]: 1178 : if (buf_id < 0)
5001 : 112 : continue;
5002 : :
5003 : 1066 : bufHdr = GetBufferDescriptor(buf_id);
5004 : :
5005 : : /*
5006 : : * We need to lock the buffer header and recheck if the buffer is
5007 : : * still associated with the same block because the buffer could be
5008 : : * evicted by some other backend loading blocks for a different
5009 : : * relation after we release lock on the BufMapping table.
5010 : : */
129 andres@anarazel.de 5011 :GNC 1066 : LockBufHdr(bufHdr);
5012 : :
1299 rhaas@postgresql.org 5013 [ + - + - ]:CBC 2132 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rlocator) &&
5014 : 1066 : BufTagGetForkNum(&bufHdr->tag) == forkNum &&
1888 akapila@postgresql.o 5015 [ + - ]: 1066 : bufHdr->tag.blockNum >= firstDelBlock)
5016 : 1066 : InvalidateBuffer(bufHdr); /* releases spinlock */
5017 : : else
129 andres@anarazel.de 5018 :UNC 0 : UnlockBufHdr(bufHdr);
5019 : : }
1888 akapila@postgresql.o 5020 :CBC 840 : }
5021 : :
5022 : : /* ---------------------------------------------------------------------
5023 : : * DropDatabaseBuffers
5024 : : *
5025 : : * This function removes all the buffers in the buffer cache for a
5026 : : * particular database. Dirty pages are simply dropped, without
5027 : : * bothering to write them out first. This is used when we destroy a
5028 : : * database, to avoid trying to flush data to disk when the directory
5029 : : * tree no longer exists. Implementation is pretty similar to
5030 : : * DropRelationBuffers() which is for destroying just one relation.
5031 : : * --------------------------------------------------------------------
5032 : : */
5033 : : void
7291 tgl@sss.pgh.pa.us 5034 : 76 : DropDatabaseBuffers(Oid dbid)
5035 : : {
5036 : : int i;
5037 : :
5038 : : /*
5039 : : * We needn't consider local buffers, since by assumption the target
5040 : : * database isn't our own.
5041 : : */
5042 : :
7681 5043 [ + + ]: 546252 : for (i = 0; i < NBuffers; i++)
5044 : : {
3772 rhaas@postgresql.org 5045 : 546176 : BufferDesc *bufHdr = GetBufferDescriptor(i);
5046 : :
5047 : : /*
5048 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
5049 : : * saves some cycles.
5050 : : */
1299 5051 [ + + ]: 546176 : if (bufHdr->tag.dbOid != dbid)
5029 tgl@sss.pgh.pa.us 5052 : 532968 : continue;
5053 : :
129 andres@anarazel.de 5054 :GNC 13208 : LockBufHdr(bufHdr);
1299 rhaas@postgresql.org 5055 [ + - ]:CBC 13208 : if (bufHdr->tag.dbOid == dbid)
7456 bruce@momjian.us 5056 : 13208 : InvalidateBuffer(bufHdr); /* releases spinlock */
5057 : : else
129 andres@anarazel.de 5058 :UNC 0 : UnlockBufHdr(bufHdr);
5059 : : }
10841 scrappy@hub.org 5060 :CBC 76 : }
5061 : :
5062 : : /* ---------------------------------------------------------------------
5063 : : * FlushRelationBuffers
5064 : : *
5065 : : * This function writes all dirty pages of a relation out to disk
5066 : : * (or more accurately, out to kernel disk buffers), ensuring that the
5067 : : * kernel has an up-to-date view of the relation.
5068 : : *
5069 : : * Generally, the caller should be holding AccessExclusiveLock on the
5070 : : * target relation to ensure that no other backend is busy dirtying
5071 : : * more blocks of the relation; the effects can't be expected to last
5072 : : * after the lock is released.
5073 : : *
5074 : : * XXX currently it sequentially searches the buffer pool, should be
5075 : : * changed to more clever ways of searching. This routine is not
5076 : : * used in any performance-critical code paths, so it's not worth
5077 : : * adding additional overhead to normal paths to make it go faster.
5078 : : * --------------------------------------------------------------------
5079 : : */
5080 : : void
7665 tgl@sss.pgh.pa.us 5081 : 138 : FlushRelationBuffers(Relation rel)
5082 : : {
5083 : : int i;
5084 : : BufferDesc *bufHdr;
774 heikki.linnakangas@i 5085 : 138 : SMgrRelation srel = RelationGetSmgr(rel);
5086 : :
5571 rhaas@postgresql.org 5087 [ + + ]: 138 : if (RelationUsesLocalBuffers(rel))
5088 : : {
10401 vadim4o@yahoo.com 5089 [ + + ]: 909 : for (i = 0; i < NLocBuffer; i++)
5090 : : {
5091 : : uint64 buf_state;
5092 : :
4063 andres@anarazel.de 5093 : 900 : bufHdr = GetLocalBufferDescriptor(i);
1299 rhaas@postgresql.org 5094 [ + + ]: 900 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rel->rd_locator) &&
59 andres@anarazel.de 5095 [ + - ]:GNC 300 : ((buf_state = pg_atomic_read_u64(&bufHdr->state)) &
5096 : : (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
5097 : : {
5098 : : ErrorContextCallback errcallback;
5099 : :
5100 : : /* Setup error traceback support for ereport() */
4871 heikki.linnakangas@i 5101 :CBC 300 : errcallback.callback = local_buffer_write_error_callback;
472 peter@eisentraut.org 5102 : 300 : errcallback.arg = bufHdr;
4871 heikki.linnakangas@i 5103 : 300 : errcallback.previous = error_context_stack;
5104 : 300 : error_context_stack = &errcallback;
5105 : :
5106 : : /* Make sure we can handle the pin */
342 andres@anarazel.de 5107 : 300 : ReservePrivateRefCountEntry();
5108 : 300 : ResourceOwnerEnlarge(CurrentResourceOwner);
5109 : :
5110 : : /*
5111 : : * Pin/unpin mostly to make valgrind work, but it also seems
5112 : : * like the right thing to do.
5113 : : */
5114 : 300 : PinLocalBuffer(bufHdr, false);
5115 : :
5116 : :
365 5117 : 300 : FlushLocalBuffer(bufHdr, srel);
5118 : :
342 5119 : 300 : UnpinLocalBuffer(BufferDescriptorGetBuffer(bufHdr));
5120 : :
5121 : : /* Pop the error context stack */
4871 heikki.linnakangas@i 5122 : 300 : error_context_stack = errcallback.previous;
5123 : : }
5124 : : }
5125 : :
7958 tgl@sss.pgh.pa.us 5126 : 9 : return;
5127 : : }
5128 : :
10401 vadim4o@yahoo.com 5129 [ + + ]: 1512193 : for (i = 0; i < NBuffers; i++)
5130 : : {
5131 : : uint64 buf_state;
5132 : :
4063 andres@anarazel.de 5133 : 1512064 : bufHdr = GetBufferDescriptor(i);
5134 : :
5135 : : /*
5136 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
5137 : : * saves some cycles.
5138 : : */
1299 rhaas@postgresql.org 5139 [ + + ]: 1512064 : if (!BufTagMatchesRelFileLocator(&bufHdr->tag, &rel->rd_locator))
5029 tgl@sss.pgh.pa.us 5140 : 1511853 : continue;
5141 : :
5142 : : /* Make sure we can handle the pin */
4073 andres@anarazel.de 5143 : 211 : ReservePrivateRefCountEntry();
858 heikki.linnakangas@i 5144 : 211 : ResourceOwnerEnlarge(CurrentResourceOwner);
5145 : :
3626 andres@anarazel.de 5146 : 211 : buf_state = LockBufHdr(bufHdr);
1299 rhaas@postgresql.org 5147 [ + - ]: 211 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rel->rd_locator) &&
3626 andres@anarazel.de 5148 [ + + ]: 211 : (buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
5149 : : {
7665 tgl@sss.pgh.pa.us 5150 : 171 : PinBuffer_Locked(bufHdr);
158 andres@anarazel.de 5151 :GNC 171 : FlushUnlockedBuffer(bufHdr, srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
1262 michael@paquier.xyz 5152 :CBC 171 : UnpinBuffer(bufHdr);
5153 : : }
5154 : : else
129 andres@anarazel.de 5155 :GNC 40 : UnlockBufHdr(bufHdr);
5156 : : }
5157 : : }
5158 : :
5159 : : /* ---------------------------------------------------------------------
5160 : : * FlushRelationsAllBuffers
5161 : : *
5162 : : * This function flushes out of the buffer pool all the pages of all
5163 : : * forks of the specified smgr relations. It's equivalent to calling
5164 : : * FlushRelationBuffers once per relation. The relations are assumed not
5165 : : * to use local buffers.
5166 : : * --------------------------------------------------------------------
5167 : : */
5168 : : void
2171 noah@leadboat.com 5169 :CBC 5 : FlushRelationsAllBuffers(SMgrRelation *smgrs, int nrels)
5170 : : {
5171 : : int i;
5172 : : SMgrSortArray *srels;
5173 : : bool use_bsearch;
5174 : :
5175 [ - + ]: 5 : if (nrels == 0)
2171 noah@leadboat.com 5176 :UBC 0 : return;
5177 : :
5178 : : /* fill-in array for qsort */
94 michael@paquier.xyz 5179 :GNC 5 : srels = palloc_array(SMgrSortArray, nrels);
5180 : :
2171 noah@leadboat.com 5181 [ + + ]:CBC 10 : for (i = 0; i < nrels; i++)
5182 : : {
1348 rhaas@postgresql.org 5183 [ - + ]: 5 : Assert(!RelFileLocatorBackendIsTemp(smgrs[i]->smgr_rlocator));
5184 : :
5185 : 5 : srels[i].rlocator = smgrs[i]->smgr_rlocator.locator;
2171 noah@leadboat.com 5186 : 5 : srels[i].srel = smgrs[i];
5187 : : }
5188 : :
5189 : : /*
5190 : : * Save the bsearch overhead for low number of relations to sync. See
5191 : : * DropRelationsAllBuffers for details.
5192 : : */
5193 : 5 : use_bsearch = nrels > RELS_BSEARCH_THRESHOLD;
5194 : :
5195 : : /* sort the list of SMgrRelations if necessary */
5196 [ - + ]: 5 : if (use_bsearch)
758 nathan@postgresql.or 5197 :UBC 0 : qsort(srels, nrels, sizeof(SMgrSortArray), rlocator_comparator);
5198 : :
2171 noah@leadboat.com 5199 [ + + ]:CBC 81925 : for (i = 0; i < NBuffers; i++)
5200 : : {
5201 : 81920 : SMgrSortArray *srelent = NULL;
5202 : 81920 : BufferDesc *bufHdr = GetBufferDescriptor(i);
5203 : : uint64 buf_state;
5204 : :
5205 : : /*
5206 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
5207 : : * saves some cycles.
5208 : : */
5209 : :
5210 [ + - ]: 81920 : if (!use_bsearch)
5211 : : {
5212 : : int j;
5213 : :
5214 [ + + ]: 161277 : for (j = 0; j < nrels; j++)
5215 : : {
1299 rhaas@postgresql.org 5216 [ + + ]: 81920 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &srels[j].rlocator))
5217 : : {
2171 noah@leadboat.com 5218 : 2563 : srelent = &srels[j];
5219 : 2563 : break;
5220 : : }
5221 : : }
5222 : : }
5223 : : else
5224 : : {
5225 : : RelFileLocator rlocator;
5226 : :
1299 rhaas@postgresql.org 5227 :UBC 0 : rlocator = BufTagGetRelFileLocator(&bufHdr->tag);
464 peter@eisentraut.org 5228 : 0 : srelent = bsearch(&rlocator,
5229 : : srels, nrels, sizeof(SMgrSortArray),
5230 : : rlocator_comparator);
5231 : : }
5232 : :
5233 : : /* buffer doesn't belong to any of the given relfilelocators; skip it */
2171 noah@leadboat.com 5234 [ + + ]:CBC 81920 : if (srelent == NULL)
5235 : 79357 : continue;
5236 : :
5237 : : /* Make sure we can handle the pin */
5238 : 2563 : ReservePrivateRefCountEntry();
858 heikki.linnakangas@i 5239 : 2563 : ResourceOwnerEnlarge(CurrentResourceOwner);
5240 : :
2171 noah@leadboat.com 5241 : 2563 : buf_state = LockBufHdr(bufHdr);
1299 rhaas@postgresql.org 5242 [ + - ]: 2563 : if (BufTagMatchesRelFileLocator(&bufHdr->tag, &srelent->rlocator) &&
2171 noah@leadboat.com 5243 [ + + ]: 2563 : (buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
5244 : : {
5245 : 2526 : PinBuffer_Locked(bufHdr);
158 andres@anarazel.de 5246 :GNC 2526 : FlushUnlockedBuffer(bufHdr, srelent->srel, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
1262 michael@paquier.xyz 5247 :CBC 2526 : UnpinBuffer(bufHdr);
5248 : : }
5249 : : else
129 andres@anarazel.de 5250 :GNC 37 : UnlockBufHdr(bufHdr);
5251 : : }
5252 : :
2171 noah@leadboat.com 5253 :CBC 5 : pfree(srels);
5254 : : }
5255 : :
5256 : : /* ---------------------------------------------------------------------
5257 : : * RelationCopyStorageUsingBuffer
5258 : : *
5259 : : * Copy fork's data using bufmgr. Same as RelationCopyStorage but instead
5260 : : * of using smgrread and smgrextend this will copy using bufmgr APIs.
5261 : : *
5262 : : * Refer comments atop CreateAndCopyRelationData() for details about
5263 : : * 'permanent' parameter.
5264 : : * --------------------------------------------------------------------
5265 : : */
5266 : : static void
1311 rhaas@postgresql.org 5267 : 77217 : RelationCopyStorageUsingBuffer(RelFileLocator srclocator,
5268 : : RelFileLocator dstlocator,
5269 : : ForkNumber forkNum, bool permanent)
5270 : : {
5271 : : Buffer srcBuf;
5272 : : Buffer dstBuf;
5273 : : Page srcPage;
5274 : : Page dstPage;
5275 : : bool use_wal;
5276 : : BlockNumber nblocks;
5277 : : BlockNumber blkno;
5278 : : PGIOAlignedBlock buf;
5279 : : BufferAccessStrategy bstrategy_src;
5280 : : BufferAccessStrategy bstrategy_dst;
5281 : : BlockRangeReadStreamPrivate p;
5282 : : ReadStream *src_stream;
5283 : : SMgrRelation src_smgr;
5284 : :
5285 : : /*
5286 : : * In general, we want to write WAL whenever wal_level > 'minimal', but we
5287 : : * can skip it when copying any fork of an unlogged relation other than
5288 : : * the init fork.
5289 : : */
1447 5290 [ + + - + : 77217 : use_wal = XLogIsNeeded() && (permanent || forkNum == INIT_FORKNUM);
- - ]
5291 : :
5292 : : /* Get number of blocks in the source relation. */
742 heikki.linnakangas@i 5293 : 77217 : nblocks = smgrnblocks(smgropen(srclocator, INVALID_PROC_NUMBER),
5294 : : forkNum);
5295 : :
5296 : : /* Nothing to copy; just return. */
1447 rhaas@postgresql.org 5297 [ + + ]: 77217 : if (nblocks == 0)
5298 : 13471 : return;
5299 : :
5300 : : /*
5301 : : * Bulk extend the destination relation of the same size as the source
5302 : : * relation before starting to copy block by block.
5303 : : */
1305 5304 : 63746 : memset(buf.data, 0, BLCKSZ);
742 heikki.linnakangas@i 5305 : 63746 : smgrextend(smgropen(dstlocator, INVALID_PROC_NUMBER), forkNum, nblocks - 1,
5306 : : buf.data, true);
5307 : :
5308 : : /* This is a bulk operation, so use buffer access strategies. */
1447 rhaas@postgresql.org 5309 : 63746 : bstrategy_src = GetAccessStrategy(BAS_BULKREAD);
5310 : 63746 : bstrategy_dst = GetAccessStrategy(BAS_BULKWRITE);
5311 : :
5312 : : /* Initialize streaming read */
558 noah@leadboat.com 5313 : 63746 : p.current_blocknum = 0;
5314 : 63746 : p.last_exclusive = nblocks;
603 5315 : 63746 : src_smgr = smgropen(srclocator, INVALID_PROC_NUMBER);
5316 : :
5317 : : /*
5318 : : * It is safe to use batchmode as block_range_read_stream_cb takes no
5319 : : * locks.
5320 : : */
350 andres@anarazel.de 5321 [ + - ]: 63746 : src_stream = read_stream_begin_smgr_relation(READ_STREAM_FULL |
5322 : : READ_STREAM_USE_BATCHING,
5323 : : bstrategy_src,
5324 : : src_smgr,
5325 : : permanent ? RELPERSISTENCE_PERMANENT : RELPERSISTENCE_UNLOGGED,
5326 : : forkNum,
5327 : : block_range_read_stream_cb,
5328 : : &p,
5329 : : 0);
5330 : :
5331 : : /* Iterate over each block of the source relation file. */
1447 rhaas@postgresql.org 5332 [ + + ]: 310449 : for (blkno = 0; blkno < nblocks; blkno++)
5333 : : {
5334 [ - + ]: 246706 : CHECK_FOR_INTERRUPTS();
5335 : :
5336 : : /* Read block from source relation. */
603 noah@leadboat.com 5337 : 246706 : srcBuf = read_stream_next_buffer(src_stream, NULL);
1317 tgl@sss.pgh.pa.us 5338 : 246703 : LockBuffer(srcBuf, BUFFER_LOCK_SHARE);
1447 rhaas@postgresql.org 5339 : 246703 : srcPage = BufferGetPage(srcBuf);
5340 : :
603 noah@leadboat.com 5341 : 246703 : dstBuf = ReadBufferWithoutRelcache(dstlocator, forkNum,
5342 : : BufferGetBlockNumber(srcBuf),
5343 : : RBM_ZERO_AND_LOCK, bstrategy_dst,
5344 : : permanent);
1317 tgl@sss.pgh.pa.us 5345 : 246703 : dstPage = BufferGetPage(dstBuf);
5346 : :
1447 rhaas@postgresql.org 5347 : 246703 : START_CRIT_SECTION();
5348 : :
5349 : : /* Copy page data from the source to the destination. */
5350 : 246703 : memcpy(dstPage, srcPage, BLCKSZ);
5351 : 246703 : MarkBufferDirty(dstBuf);
5352 : :
5353 : : /* WAL-log the copied page. */
5354 [ + + ]: 246703 : if (use_wal)
5355 : 139086 : log_newpage_buffer(dstBuf, true);
5356 : :
5357 [ - + ]: 246703 : END_CRIT_SECTION();
5358 : :
5359 : 246703 : UnlockReleaseBuffer(dstBuf);
1317 tgl@sss.pgh.pa.us 5360 : 246703 : UnlockReleaseBuffer(srcBuf);
5361 : : }
603 noah@leadboat.com 5362 [ - + ]: 63743 : Assert(read_stream_next_buffer(src_stream, NULL) == InvalidBuffer);
5363 : 63743 : read_stream_end(src_stream);
5364 : :
1091 andres@anarazel.de 5365 : 63743 : FreeAccessStrategy(bstrategy_src);
5366 : 63743 : FreeAccessStrategy(bstrategy_dst);
5367 : : }
5368 : :
5369 : : /* ---------------------------------------------------------------------
5370 : : * CreateAndCopyRelationData
5371 : : *
5372 : : * Create destination relation storage and copy all forks from the
5373 : : * source relation to the destination.
5374 : : *
5375 : : * Pass permanent as true for permanent relations and false for
5376 : : * unlogged relations. Currently this API is not supported for
5377 : : * temporary relations.
5378 : : * --------------------------------------------------------------------
5379 : : */
5380 : : void
1348 rhaas@postgresql.org 5381 : 58046 : CreateAndCopyRelationData(RelFileLocator src_rlocator,
5382 : : RelFileLocator dst_rlocator, bool permanent)
5383 : : {
5384 : : char relpersistence;
5385 : : SMgrRelation src_rel;
5386 : : SMgrRelation dst_rel;
5387 : :
5388 : : /* Set the relpersistence. */
1447 5389 [ + - ]: 58046 : relpersistence = permanent ?
5390 : : RELPERSISTENCE_PERMANENT : RELPERSISTENCE_UNLOGGED;
5391 : :
742 heikki.linnakangas@i 5392 : 58046 : src_rel = smgropen(src_rlocator, INVALID_PROC_NUMBER);
5393 : 58046 : dst_rel = smgropen(dst_rlocator, INVALID_PROC_NUMBER);
5394 : :
5395 : : /*
5396 : : * Create and copy all forks of the relation. During create database we
5397 : : * have a separate cleanup mechanism which deletes complete database
5398 : : * directory. Therefore, each individual relation doesn't need to be
5399 : : * registered for cleanup.
5400 : : */
1348 rhaas@postgresql.org 5401 : 58046 : RelationCreateStorage(dst_rlocator, relpersistence, false);
5402 : :
5403 : : /* copy main fork. */
1311 5404 : 58046 : RelationCopyStorageUsingBuffer(src_rlocator, dst_rlocator, MAIN_FORKNUM,
5405 : : permanent);
5406 : :
5407 : : /* copy those extra forks that exist */
1447 5408 : 58043 : for (ForkNumber forkNum = MAIN_FORKNUM + 1;
5409 [ + + ]: 232172 : forkNum <= MAX_FORKNUM; forkNum++)
5410 : : {
774 heikki.linnakangas@i 5411 [ + + ]: 174129 : if (smgrexists(src_rel, forkNum))
5412 : : {
5413 : 19171 : smgrcreate(dst_rel, forkNum, false);
5414 : :
5415 : : /*
5416 : : * WAL log creation if the relation is persistent, or this is the
5417 : : * init fork of an unlogged relation.
5418 : : */
1447 rhaas@postgresql.org 5419 [ - + - - ]: 19171 : if (permanent || forkNum == INIT_FORKNUM)
1348 5420 : 19171 : log_smgrcreate(&dst_rlocator, forkNum);
5421 : :
5422 : : /* Copy a fork's data, block by block. */
1311 5423 : 19171 : RelationCopyStorageUsingBuffer(src_rlocator, dst_rlocator, forkNum,
5424 : : permanent);
5425 : : }
5426 : : }
1447 5427 : 58043 : }
5428 : :
5429 : : /* ---------------------------------------------------------------------
5430 : : * FlushDatabaseBuffers
5431 : : *
5432 : : * This function writes all dirty pages of a database out to disk
5433 : : * (or more accurately, out to kernel disk buffers), ensuring that the
5434 : : * kernel has an up-to-date view of the database.
5435 : : *
5436 : : * Generally, the caller should be holding an appropriate lock to ensure
5437 : : * no other backend is active in the target database; otherwise more
5438 : : * pages could get dirtied.
5439 : : *
5440 : : * Note we don't worry about flushing any pages of temporary relations.
5441 : : * It's assumed these wouldn't be interesting.
5442 : : * --------------------------------------------------------------------
5443 : : */
5444 : : void
6835 tgl@sss.pgh.pa.us 5445 : 5 : FlushDatabaseBuffers(Oid dbid)
5446 : : {
5447 : : int i;
5448 : : BufferDesc *bufHdr;
5449 : :
5450 [ + + ]: 645 : for (i = 0; i < NBuffers; i++)
5451 : : {
5452 : : uint64 buf_state;
5453 : :
4063 andres@anarazel.de 5454 : 640 : bufHdr = GetBufferDescriptor(i);
5455 : :
5456 : : /*
5457 : : * As in DropRelationBuffers, an unlocked precheck should be safe and
5458 : : * saves some cycles.
5459 : : */
1299 rhaas@postgresql.org 5460 [ + + ]: 640 : if (bufHdr->tag.dbOid != dbid)
5029 tgl@sss.pgh.pa.us 5461 : 474 : continue;
5462 : :
5463 : : /* Make sure we can handle the pin */
4073 andres@anarazel.de 5464 : 166 : ReservePrivateRefCountEntry();
858 heikki.linnakangas@i 5465 : 166 : ResourceOwnerEnlarge(CurrentResourceOwner);
5466 : :
3626 andres@anarazel.de 5467 : 166 : buf_state = LockBufHdr(bufHdr);
1299 rhaas@postgresql.org 5468 [ + - ]: 166 : if (bufHdr->tag.dbOid == dbid &&
3626 andres@anarazel.de 5469 [ + + ]: 166 : (buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID | BM_DIRTY))
5470 : : {
6835 tgl@sss.pgh.pa.us 5471 : 26 : PinBuffer_Locked(bufHdr);
158 andres@anarazel.de 5472 :GNC 26 : FlushUnlockedBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
1262 michael@paquier.xyz 5473 :CBC 26 : UnpinBuffer(bufHdr);
5474 : : }
5475 : : else
129 andres@anarazel.de 5476 :GNC 140 : UnlockBufHdr(bufHdr);
5477 : : }
6835 tgl@sss.pgh.pa.us 5478 :CBC 5 : }
5479 : :
5480 : : /*
5481 : : * Flush a previously, share-exclusively or exclusively, locked and pinned
5482 : : * buffer to the OS.
5483 : : */
5484 : : void
3748 andres@anarazel.de 5485 : 104 : FlushOneBuffer(Buffer buffer)
5486 : : {
5487 : : BufferDesc *bufHdr;
5488 : :
5489 : : /* currently not needed, but no fundamental reason not to support */
5490 [ - + ]: 104 : Assert(!BufferIsLocal(buffer));
5491 : :
5492 [ - + - + : 104 : Assert(BufferIsPinned(buffer));
- + ]
5493 : :
5494 : 104 : bufHdr = GetBufferDescriptor(buffer - 1);
5495 : :
158 andres@anarazel.de 5496 [ - + ]:GNC 104 : Assert(BufferIsLockedByMe(buffer));
5497 : :
1130 andres@anarazel.de 5498 :CBC 104 : FlushBuffer(bufHdr, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
3748 5499 : 104 : }
5500 : :
5501 : : /*
5502 : : * ReleaseBuffer -- release the pin on a buffer
5503 : : */
5504 : : void
8622 tgl@sss.pgh.pa.us 5505 : 64444827 : ReleaseBuffer(Buffer buffer)
5506 : : {
7821 5507 [ - + ]: 64444827 : if (!BufferIsValid(buffer))
5383 peter_e@gmx.net 5508 [ # # ]:UBC 0 : elog(ERROR, "bad buffer ID: %d", buffer);
5509 : :
10416 bruce@momjian.us 5510 [ + + ]:CBC 64444827 : if (BufferIsLocal(buffer))
1075 andres@anarazel.de 5511 : 1775677 : UnpinLocalBuffer(buffer);
5512 : : else
5513 : 62669150 : UnpinBuffer(GetBufferDescriptor(buffer - 1));
10841 scrappy@hub.org 5514 : 64444827 : }
5515 : :
5516 : : /*
5517 : : * UnlockReleaseBuffer -- release the content lock and pin on a buffer
5518 : : *
5519 : : * This is just a shorthand for a common combination.
5520 : : */
5521 : : void
7289 tgl@sss.pgh.pa.us 5522 : 18956392 : UnlockReleaseBuffer(Buffer buffer)
5523 : : {
5524 : 18956392 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
5525 : 18956392 : ReleaseBuffer(buffer);
5526 : 18956392 : }
5527 : :
5528 : : /*
5529 : : * IncrBufferRefCount
5530 : : * Increment the pin count on a buffer that we have *already* pinned
5531 : : * at least once.
5532 : : *
5533 : : * This function cannot be used on a buffer we do not have pinned,
5534 : : * because it doesn't change the shared buffer state.
5535 : : */
5536 : : void
7911 5537 : 11700427 : IncrBufferRefCount(Buffer buffer)
5538 : : {
7781 neilc@samurai.com 5539 [ - + + + : 11700427 : Assert(BufferIsPinned(buffer));
- + ]
858 heikki.linnakangas@i 5540 : 11700427 : ResourceOwnerEnlarge(CurrentResourceOwner);
7911 tgl@sss.pgh.pa.us 5541 [ + + ]: 11700427 : if (BufferIsLocal(buffer))
5542 : 356420 : LocalRefCount[-buffer - 1]++;
5543 : : else
5544 : : {
5545 : : PrivateRefCountEntry *ref;
5546 : :
4073 andres@anarazel.de 5547 : 11344007 : ref = GetPrivateRefCountEntry(buffer, true);
4215 5548 [ - + ]: 11344007 : Assert(ref != NULL);
91 andres@anarazel.de 5549 :GNC 11344007 : ref->data.refcount++;
5550 : : }
3049 tgl@sss.pgh.pa.us 5551 :CBC 11700427 : ResourceOwnerRememberBuffer(CurrentResourceOwner, buffer);
7911 5552 : 11700427 : }
5553 : :
5554 : : /*
5555 : : * Shared-buffer only helper for MarkBufferDirtyHint() and
5556 : : * BufferSetHintBits16().
5557 : : *
5558 : : * This is separated out because it turns out that the repeated checks for
5559 : : * local buffers, repeated GetBufferDescriptor() and repeated reading of the
5560 : : * buffer's state sufficiently hurts the performance of BufferSetHintBits16().
5561 : : */
5562 : : static inline void
5 andres@anarazel.de 5563 :GNC 7458231 : MarkSharedBufferDirtyHint(Buffer buffer, BufferDesc *bufHdr, uint64 lockstate,
5564 : : bool buffer_std)
5565 : : {
3616 kgrittn@postgresql.o 5566 :CBC 7458231 : Page page = BufferGetPage(buffer);
5567 : :
4215 andres@anarazel.de 5568 [ - + ]: 7458231 : Assert(GetPrivateRefCount(buffer) > 0);
5569 : :
5570 : : /* here, either share-exclusive or exclusive lock is OK */
5 andres@anarazel.de 5571 [ + + - + ]:GNC 7458231 : Assert(BufferLockHeldByMeInMode(bufHdr, BUFFER_LOCK_EXCLUSIVE) ||
5572 : : BufferLockHeldByMeInMode(bufHdr, BUFFER_LOCK_SHARE_EXCLUSIVE));
5573 : :
5574 : : /*
5575 : : * This routine might get called many times on the same page, if we are
5576 : : * making the first scan after commit of an xact that added/deleted many
5577 : : * tuples. So, be as quick as we can if the buffer is already dirty.
5578 : : *
5579 : : * As we are holding (at least) a share-exclusive lock, nobody could have
5580 : : * cleaned or dirtied the page concurrently, so we can just rely on the
5581 : : * previously fetched value here without any danger of races.
5582 : : */
4 5583 [ + + ]: 7458231 : if (unlikely(!(lockstate & BM_DIRTY)))
5584 : : {
4741 simon@2ndQuadrant.co 5585 :CBC 625155 : XLogRecPtr lsn = InvalidXLogRecPtr;
4 andres@anarazel.de 5586 :GNC 625155 : bool wal_log = false;
5587 : : uint64 buf_state;
5588 : :
5589 : : /*
5590 : : * If we need to protect hint bit updates from torn writes, WAL-log a
5591 : : * full page image of the page. This full page image is only necessary
5592 : : * if the hint bit update is the first change to the page since the
5593 : : * last checkpoint.
5594 : : *
5595 : : * We don't check full_page_writes here because that logic is included
5596 : : * when we call XLogInsert() since the value changes dynamically.
5597 : : */
5 5598 [ + + - + : 625155 : if (XLogHintBitIsNeeded() && (lockstate & BM_PERMANENT))
+ + ]
5599 : : {
5600 : : /*
5601 : : * If we must not write WAL, due to a relfilelocator-specific
5602 : : * condition or being in recovery, don't dirty the page. We can
5603 : : * set the hint, just not dirty the page as a result so the hint
5604 : : * is lost when we evict the page or shutdown.
5605 : : *
5606 : : * See src/backend/storage/page/README for longer discussion.
5607 : : */
2171 noah@leadboat.com 5608 [ + + + + ]:CBC 689259 : if (RecoveryInProgress() ||
1299 rhaas@postgresql.org 5609 : 65230 : RelFileLocatorSkippingWAL(BufTagGetRelFileLocator(&bufHdr->tag)))
4741 simon@2ndQuadrant.co 5610 : 560635 : return;
5611 : :
4 andres@anarazel.de 5612 :GNC 63394 : wal_log = true;
5613 : : }
5614 : :
5615 : : /*
5616 : : * We must mark the page dirty before we emit the WAL record, as per
5617 : : * the usual rules, to ensure that BufferSync()/SyncOneBuffer() try to
5618 : : * flush the buffer, even if we haven't inserted the WAL record yet.
5619 : : * As we hold at least a share-exclusive lock, checkpoints will wait
5620 : : * for this backend to be done with the buffer before continuing. If
5621 : : * we did it the other way round, a checkpoint could start between
5622 : : * writing the WAL record and marking the buffer dirty.
5623 : : */
3626 andres@anarazel.de 5624 :CBC 64520 : buf_state = LockBufHdr(bufHdr);
5625 : :
5626 : : /*
5627 : : * It should not be possible for the buffer to already be dirty, see
5628 : : * comment above.
5629 : : */
5 andres@anarazel.de 5630 [ - + ]:GNC 64520 : Assert(!(buf_state & BM_DIRTY));
3626 andres@anarazel.de 5631 [ - + ]:CBC 64520 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
4 andres@anarazel.de 5632 :GNC 64520 : UnlockBufHdrExt(bufHdr, buf_state,
5633 : : BM_DIRTY,
5634 : : 0, 0);
5635 : :
5636 : : /*
5637 : : * If the block is already dirty because we either made a change or
5638 : : * set a hint already, then we don't need to write a full page image.
5639 : : * Note that aggressive cleaning of blocks dirtied by hint bit setting
5640 : : * would increase the call rate. Bulk setting of hint bits would
5641 : : * reduce the call rate...
5642 : : */
5643 [ + + ]: 64520 : if (wal_log)
5644 : 63394 : lsn = XLogSaveBufferForHint(buffer, buffer_std);
5645 : :
5 5646 [ + + ]: 64520 : if (XLogRecPtrIsValid(lsn))
5647 : : {
5648 : : /*
5649 : : * Set the page LSN if we wrote a backup block. To allow backends
5650 : : * that only hold a share lock on the buffer to read the LSN in a
5651 : : * tear-free manner, we set the page LSN while holding the buffer
5652 : : * header lock. This allows any reader of an LSN who holds only a
5653 : : * share lock to also obtain a buffer header lock before using
5654 : : * PageGetLSN() to read the LSN in a tear free way. This is done
5655 : : * in BufferGetLSNAtomic().
5656 : : *
5657 : : * If checksums are enabled, you might think we should reset the
5658 : : * checksum here. That will happen when the page is written
5659 : : * sometime later in this checkpoint cycle.
5660 : : */
4 5661 : 32935 : buf_state = LockBufHdr(bufHdr);
5 5662 : 32935 : PageSetLSN(page, lsn);
4 5663 : 32935 : UnlockBufHdr(bufHdr);
5664 : : }
5665 : :
5 5666 : 64520 : pgBufferUsage.shared_blks_dirtied++;
5667 [ + + ]: 64520 : if (VacuumCostActive)
5668 : 2227 : VacuumCostBalance += VacuumCostPageDirty;
5669 : : }
5670 : : }
5671 : :
5672 : : /*
5673 : : * MarkBufferDirtyHint
5674 : : *
5675 : : * Mark a buffer dirty for non-critical changes.
5676 : : *
5677 : : * This is essentially the same as MarkBufferDirty, except:
5678 : : *
5679 : : * 1. The caller does not write WAL; so if checksums are enabled, we may need
5680 : : * to write an XLOG_FPI_FOR_HINT WAL record to protect against torn pages.
5681 : : * 2. The caller might have only a share-exclusive-lock instead of an
5682 : : * exclusive-lock on the buffer's content lock.
5683 : : * 3. This function does not guarantee that the buffer is always marked dirty
5684 : : * (it e.g. can't always on a hot standby), so it cannot be used for
5685 : : * important changes.
5686 : : */
5687 : : inline void
5688 : 638418 : MarkBufferDirtyHint(Buffer buffer, bool buffer_std)
5689 : : {
5690 : : BufferDesc *bufHdr;
5691 : :
5692 : 638418 : bufHdr = GetBufferDescriptor(buffer - 1);
5693 : :
5694 [ - + ]: 638418 : if (!BufferIsValid(buffer))
5 andres@anarazel.de 5695 [ # # ]:UNC 0 : elog(ERROR, "bad buffer ID: %d", buffer);
5696 : :
5 andres@anarazel.de 5697 [ + + ]:GNC 638418 : if (BufferIsLocal(buffer))
5698 : : {
5699 : 15198 : MarkLocalBufferDirty(buffer);
5700 : 15198 : return;
5701 : : }
5702 : :
5703 : 623220 : MarkSharedBufferDirtyHint(buffer, bufHdr,
5704 : 623220 : pg_atomic_read_u64(&bufHdr->state),
5705 : : buffer_std);
5706 : : }
5707 : :
5708 : : /*
5709 : : * Release buffer content locks for shared buffers.
5710 : : *
5711 : : * Used to clean up after errors.
5712 : : *
5713 : : * Currently, we can expect that resource owner cleanup, via
5714 : : * ResOwnerReleaseBufferPin(), took care of releasing buffer content locks per
5715 : : * se; the only thing we need to deal with here is clearing any PIN_COUNT
5716 : : * request that was in progress.
5717 : : */
5718 : : void
9193 tgl@sss.pgh.pa.us 5719 :CBC 53037 : UnlockBuffers(void)
5720 : : {
3772 rhaas@postgresql.org 5721 : 53037 : BufferDesc *buf = PinCountWaitBuf;
5722 : :
7820 tgl@sss.pgh.pa.us 5723 [ - + ]: 53037 : if (buf)
5724 : : {
5725 : : uint64 buf_state;
59 andres@anarazel.de 5726 :UNC 0 : uint64 unset_bits = 0;
5727 : :
3626 andres@anarazel.de 5728 :UBC 0 : buf_state = LockBufHdr(buf);
5729 : :
5730 : : /*
5731 : : * Don't complain if flag bit not set; it could have been reset but we
5732 : : * got a cancel/die interrupt before getting the signal.
5733 : : */
5734 [ # # ]: 0 : if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
752 heikki.linnakangas@i 5735 [ # # ]: 0 : buf->wait_backend_pgprocno == MyProcNumber)
129 andres@anarazel.de 5736 :UNC 0 : unset_bits = BM_PIN_COUNT_WAITER;
5737 : :
5738 : 0 : UnlockBufHdrExt(buf, buf_state,
5739 : : 0, unset_bits,
5740 : : 0);
5741 : :
7681 tgl@sss.pgh.pa.us 5742 :UBC 0 : PinCountWaitBuf = NULL;
5743 : : }
9952 vadim4o@yahoo.com 5744 :CBC 53037 : }
5745 : :
5746 : : /*
5747 : : * Acquire the buffer content lock in the specified mode
5748 : : *
5749 : : * If the lock is not available, sleep until it is.
5750 : : *
5751 : : * Side effect: cancel/die interrupts are held off until lock release.
5752 : : *
5753 : : * This uses almost the same locking approach as lwlock.c's
5754 : : * LWLockAcquire(). See documentation at the top of lwlock.c for a more
5755 : : * detailed discussion.
5756 : : *
5757 : : * The reason that this, and most of the other BufferLock* functions, get both
5758 : : * the Buffer and BufferDesc* as parameters, is that looking up one from the
5759 : : * other repeatedly shows up noticeably in profiles.
5760 : : *
5761 : : * Callers should provide a constant for mode, for more efficient code
5762 : : * generation.
5763 : : */
5764 : : static inline void
59 andres@anarazel.de 5765 :GNC 85197538 : BufferLockAcquire(Buffer buffer, BufferDesc *buf_hdr, BufferLockMode mode)
5766 : : {
5767 : : PrivateRefCountEntry *entry;
5768 : 85197538 : int extraWaits = 0;
5769 : :
5770 : : /*
5771 : : * Get reference to the refcount entry before we hold the lock, it seems
5772 : : * better to do before holding the lock.
5773 : : */
5774 : 85197538 : entry = GetPrivateRefCountEntry(buffer, true);
5775 : :
5776 : : /*
5777 : : * We better not already hold a lock on the buffer.
5778 : : */
5779 [ - + ]: 85197538 : Assert(entry->data.lockmode == BUFFER_LOCK_UNLOCK);
5780 : :
5781 : : /*
5782 : : * Lock out cancel/die interrupts until we exit the code section protected
5783 : : * by the content lock. This ensures that interrupts will not interfere
5784 : : * with manipulations of data structures in shared memory.
5785 : : */
5786 : 85197538 : HOLD_INTERRUPTS();
5787 : :
5788 : : for (;;)
5789 : 23746 : {
58 5790 : 85221284 : uint32 wait_event = 0; /* initialized to avoid compiler warning */
5791 : : bool mustwait;
5792 : :
5793 : : /*
5794 : : * Try to grab the lock the first time, we're not in the waitqueue
5795 : : * yet/anymore.
5796 : : */
59 5797 : 85221284 : mustwait = BufferLockAttempt(buf_hdr, mode);
5798 : :
5799 [ + + ]: 85221284 : if (likely(!mustwait))
5800 : : {
5801 : 85196862 : break;
5802 : : }
5803 : :
5804 : : /*
5805 : : * Ok, at this point we couldn't grab the lock on the first try. We
5806 : : * cannot simply queue ourselves to the end of the list and wait to be
5807 : : * woken up because by now the lock could long have been released.
5808 : : * Instead add us to the queue and try to grab the lock again. If we
5809 : : * succeed we need to revert the queuing and be happy, otherwise we
5810 : : * recheck the lock. If we still couldn't grab it, we know that the
5811 : : * other locker will see our queue entries when releasing since they
5812 : : * existed before we checked for the lock.
5813 : : */
5814 : :
5815 : : /* add to the queue */
5816 : 24422 : BufferLockQueueSelf(buf_hdr, mode);
5817 : :
5818 : : /* we're now guaranteed to be woken up if necessary */
5819 : 24422 : mustwait = BufferLockAttempt(buf_hdr, mode);
5820 : :
5821 : : /* ok, grabbed the lock the second time round, need to undo queueing */
5822 [ + + ]: 24422 : if (!mustwait)
5823 : : {
5824 : 676 : BufferLockDequeueSelf(buf_hdr);
5825 : 676 : break;
5826 : : }
5827 : :
5828 [ + + + - : 23746 : switch (mode)
- ]
5829 : : {
5830 : 13552 : case BUFFER_LOCK_EXCLUSIVE:
5831 : 13552 : wait_event = WAIT_EVENT_BUFFER_EXCLUSIVE;
5832 : 13552 : break;
5833 : 91 : case BUFFER_LOCK_SHARE_EXCLUSIVE:
5834 : 91 : wait_event = WAIT_EVENT_BUFFER_SHARE_EXCLUSIVE;
5835 : 91 : break;
5836 : 10103 : case BUFFER_LOCK_SHARE:
5837 : 10103 : wait_event = WAIT_EVENT_BUFFER_SHARED;
5838 : 10103 : break;
59 andres@anarazel.de 5839 :UNC 0 : case BUFFER_LOCK_UNLOCK:
5840 : 0 : pg_unreachable();
5841 : :
5842 : : }
59 andres@anarazel.de 5843 :GNC 23746 : pgstat_report_wait_start(wait_event);
5844 : :
5845 : : /*
5846 : : * Wait until awakened.
5847 : : *
5848 : : * It is possible that we get awakened for a reason other than being
5849 : : * signaled by BufferLockWakeup(). If so, loop back and wait again.
5850 : : * Once we've gotten the lock, re-increment the sema by the number of
5851 : : * additional signals received.
5852 : : */
5853 : : for (;;)
5854 : : {
5855 : 23746 : PGSemaphoreLock(MyProc->sem);
5856 [ + - ]: 23746 : if (MyProc->lwWaiting == LW_WS_NOT_WAITING)
5857 : 23746 : break;
59 andres@anarazel.de 5858 :UNC 0 : extraWaits++;
5859 : : }
5860 : :
59 andres@anarazel.de 5861 :GNC 23746 : pgstat_report_wait_end();
5862 : :
5863 : : /* Retrying, allow BufferLockRelease to release waiters again. */
5864 : 23746 : pg_atomic_fetch_and_u64(&buf_hdr->state, ~BM_LOCK_WAKE_IN_PROGRESS);
5865 : : }
5866 : :
5867 : : /* Remember that we now hold this lock */
5868 : 85197538 : entry->data.lockmode = mode;
5869 : :
5870 : : /*
5871 : : * Fix the process wait semaphore's count for any absorbed wakeups.
5872 : : */
5873 [ - + ]: 85197538 : while (unlikely(extraWaits-- > 0))
59 andres@anarazel.de 5874 :UNC 0 : PGSemaphoreUnlock(MyProc->sem);
59 andres@anarazel.de 5875 :GNC 85197538 : }
5876 : :
5877 : : /*
5878 : : * Release a previously acquired buffer content lock.
5879 : : */
5880 : : static void
5881 : 86473517 : BufferLockUnlock(Buffer buffer, BufferDesc *buf_hdr)
5882 : : {
5883 : : BufferLockMode mode;
5884 : : uint64 oldstate;
5885 : : uint64 sub;
5886 : :
5887 : 86473517 : mode = BufferLockDisownInternal(buffer, buf_hdr);
5888 : :
5889 : : /*
5890 : : * Release my hold on lock, after that it can immediately be acquired by
5891 : : * others, even if we still have to wakeup other waiters.
5892 : : */
5893 : 86473517 : sub = BufferLockReleaseSub(mode);
5894 : :
5895 : 86473517 : oldstate = pg_atomic_sub_fetch_u64(&buf_hdr->state, sub);
5896 : :
5897 : 86473517 : BufferLockProcessRelease(buf_hdr, mode, oldstate);
5898 : :
5899 : : /*
5900 : : * Now okay to allow cancel/die interrupts.
5901 : : */
5902 [ - + ]: 86473517 : RESUME_INTERRUPTS();
5903 : 86473517 : }
5904 : :
5905 : :
5906 : : /*
5907 : : * Acquire the content lock for the buffer, but only if we don't have to wait.
5908 : : *
5909 : : * It is allowed to try to conditionally acquire a lock on a buffer that this
5910 : : * backend has already locked, but the lock acquisition will always fail, even
5911 : : * if the new lock acquisition does not conflict with an already held lock
5912 : : * (e.g. two share locks). This is because we currently do not have space to
5913 : : * track multiple lock ownerships of the same buffer within one backend. That
5914 : : * is ok for the current uses of BufferLockConditional().
5915 : : */
5916 : : static bool
5917 : 1276886 : BufferLockConditional(Buffer buffer, BufferDesc *buf_hdr, BufferLockMode mode)
5918 : : {
5919 : 1276886 : PrivateRefCountEntry *entry = GetPrivateRefCountEntry(buffer, true);
5920 : : bool mustwait;
5921 : :
5922 : : /*
5923 : : * As described above, if we're trying to lock a buffer this backend
5924 : : * already has locked, return false, independent of the existing and
5925 : : * desired lock level.
5926 : : */
45 5927 [ - + ]: 1276886 : if (entry->data.lockmode != BUFFER_LOCK_UNLOCK)
45 andres@anarazel.de 5928 :UNC 0 : return false;
5929 : :
5930 : : /*
5931 : : * Lock out cancel/die interrupts until we exit the code section protected
5932 : : * by the content lock. This ensures that interrupts will not interfere
5933 : : * with manipulations of data structures in shared memory.
5934 : : */
59 andres@anarazel.de 5935 :GNC 1276886 : HOLD_INTERRUPTS();
5936 : :
5937 : : /* Check for the lock */
5938 : 1276886 : mustwait = BufferLockAttempt(buf_hdr, mode);
5939 : :
5940 [ + + ]: 1276886 : if (mustwait)
5941 : : {
5942 : : /* Failed to get lock, so release interrupt holdoff */
5943 [ - + ]: 907 : RESUME_INTERRUPTS();
5944 : : }
5945 : : else
5946 : : {
5947 : 1275979 : entry->data.lockmode = mode;
5948 : : }
5949 : :
5950 : 1276886 : return !mustwait;
5951 : : }
5952 : :
5953 : : /*
5954 : : * Internal function that tries to atomically acquire the content lock in the
5955 : : * passed in mode.
5956 : : *
5957 : : * This function will not block waiting for a lock to become free - that's the
5958 : : * caller's job.
5959 : : *
5960 : : * Similar to LWLockAttemptLock().
5961 : : */
5962 : : static inline bool
5963 : 86522592 : BufferLockAttempt(BufferDesc *buf_hdr, BufferLockMode mode)
5964 : : {
5965 : : uint64 old_state;
5966 : :
5967 : : /*
5968 : : * Read once outside the loop, later iterations will get the newer value
5969 : : * via compare & exchange.
5970 : : */
5971 : 86522592 : old_state = pg_atomic_read_u64(&buf_hdr->state);
5972 : :
5973 : : /* loop until we've determined whether we could acquire the lock or not */
5974 : : while (true)
5975 : 10523 : {
5976 : : uint64 desired_state;
5977 : : bool lock_free;
5978 : :
5979 : 86533115 : desired_state = old_state;
5980 : :
5981 [ + + ]: 86533115 : if (mode == BUFFER_LOCK_EXCLUSIVE)
5982 : : {
5983 : 26227707 : lock_free = (old_state & BM_LOCK_MASK) == 0;
5984 [ + + ]: 26227707 : if (lock_free)
5985 : 26199166 : desired_state += BM_LOCK_VAL_EXCLUSIVE;
5986 : : }
5987 [ + + ]: 60305408 : else if (mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
5988 : : {
5989 : 605911 : lock_free = (old_state & (BM_LOCK_VAL_EXCLUSIVE | BM_LOCK_VAL_SHARE_EXCLUSIVE)) == 0;
5990 [ + + ]: 605911 : if (lock_free)
5991 : 605729 : desired_state += BM_LOCK_VAL_SHARE_EXCLUSIVE;
5992 : : }
5993 : : else
5994 : : {
5995 : 59699497 : lock_free = (old_state & BM_LOCK_VAL_EXCLUSIVE) == 0;
5996 [ + + ]: 59699497 : if (lock_free)
5997 : 59678979 : desired_state += BM_LOCK_VAL_SHARED;
5998 : : }
5999 : :
6000 : : /*
6001 : : * Attempt to swap in the state we are expecting. If we didn't see
6002 : : * lock to be free, that's just the old value. If we saw it as free,
6003 : : * we'll attempt to mark it acquired. The reason that we always swap
6004 : : * in the value is that this doubles as a memory barrier. We could try
6005 : : * to be smarter and only swap in values if we saw the lock as free,
6006 : : * but benchmark haven't shown it as beneficial so far.
6007 : : *
6008 : : * Retry if the value changed since we last looked at it.
6009 : : */
6010 [ + + ]: 86533115 : if (likely(pg_atomic_compare_exchange_u64(&buf_hdr->state,
6011 : : &old_state, desired_state)))
6012 : : {
6013 [ + + ]: 86522592 : if (lock_free)
6014 : : {
6015 : : /* Great! Got the lock. */
6016 : 86473517 : return false;
6017 : : }
6018 : : else
6019 : 49075 : return true; /* somebody else has the lock */
6020 : : }
6021 : : }
6022 : :
6023 : : pg_unreachable();
6024 : : }
6025 : :
6026 : : /*
6027 : : * Add ourselves to the end of the content lock's wait queue.
6028 : : */
6029 : : static void
6030 : 24422 : BufferLockQueueSelf(BufferDesc *buf_hdr, BufferLockMode mode)
6031 : : {
6032 : : /*
6033 : : * If we don't have a PGPROC structure, there's no way to wait. This
6034 : : * should never occur, since MyProc should only be null during shared
6035 : : * memory initialization.
6036 : : */
6037 [ - + ]: 24422 : if (MyProc == NULL)
59 andres@anarazel.de 6038 [ # # ]:UNC 0 : elog(PANIC, "cannot wait without a PGPROC structure");
6039 : :
59 andres@anarazel.de 6040 [ - + ]:GNC 24422 : if (MyProc->lwWaiting != LW_WS_NOT_WAITING)
59 andres@anarazel.de 6041 [ # # ]:UNC 0 : elog(PANIC, "queueing for lock while waiting on another one");
6042 : :
59 andres@anarazel.de 6043 :GNC 24422 : LockBufHdr(buf_hdr);
6044 : :
6045 : : /* setting the flag is protected by the spinlock */
6046 : 24422 : pg_atomic_fetch_or_u64(&buf_hdr->state, BM_LOCK_HAS_WAITERS);
6047 : :
6048 : : /*
6049 : : * These are currently used both for lwlocks and buffer content locks,
6050 : : * which is acceptable, although not pretty, because a backend can't wait
6051 : : * for both types of locks at the same time.
6052 : : */
6053 : 24422 : MyProc->lwWaiting = LW_WS_WAITING;
6054 : 24422 : MyProc->lwWaitMode = mode;
6055 : :
6056 : 24422 : proclist_push_tail(&buf_hdr->lock_waiters, MyProcNumber, lwWaitLink);
6057 : :
6058 : : /* Can release the mutex now */
6059 : 24422 : UnlockBufHdr(buf_hdr);
6060 : 24422 : }
6061 : :
6062 : : /*
6063 : : * Remove ourselves from the waitlist.
6064 : : *
6065 : : * This is used if we queued ourselves because we thought we needed to sleep
6066 : : * but, after further checking, we discovered that we don't actually need to
6067 : : * do so.
6068 : : */
6069 : : static void
6070 : 676 : BufferLockDequeueSelf(BufferDesc *buf_hdr)
6071 : : {
6072 : : bool on_waitlist;
6073 : :
6074 : 676 : LockBufHdr(buf_hdr);
6075 : :
6076 : 676 : on_waitlist = MyProc->lwWaiting == LW_WS_WAITING;
6077 [ + + ]: 676 : if (on_waitlist)
6078 : 429 : proclist_delete(&buf_hdr->lock_waiters, MyProcNumber, lwWaitLink);
6079 : :
6080 [ + + ]: 676 : if (proclist_is_empty(&buf_hdr->lock_waiters) &&
6081 [ + + ]: 654 : (pg_atomic_read_u64(&buf_hdr->state) & BM_LOCK_HAS_WAITERS) != 0)
6082 : : {
6083 : 408 : pg_atomic_fetch_and_u64(&buf_hdr->state, ~BM_LOCK_HAS_WAITERS);
6084 : : }
6085 : :
6086 : : /* XXX: combine with fetch_and above? */
6087 : 676 : UnlockBufHdr(buf_hdr);
6088 : :
6089 : : /* clear waiting state again, nice for debugging */
6090 [ + + ]: 676 : if (on_waitlist)
6091 : 429 : MyProc->lwWaiting = LW_WS_NOT_WAITING;
6092 : : else
6093 : : {
6094 : 247 : int extraWaits = 0;
6095 : :
6096 : :
6097 : : /*
6098 : : * Somebody else dequeued us and has or will wake us up. Deal with the
6099 : : * superfluous absorption of a wakeup.
6100 : : */
6101 : :
6102 : : /*
6103 : : * Clear BM_LOCK_WAKE_IN_PROGRESS if somebody woke us before we
6104 : : * removed ourselves - they'll have set it.
6105 : : */
6106 : 247 : pg_atomic_fetch_and_u64(&buf_hdr->state, ~BM_LOCK_WAKE_IN_PROGRESS);
6107 : :
6108 : : /*
6109 : : * Now wait for the scheduled wakeup, otherwise our ->lwWaiting would
6110 : : * get reset at some inconvenient point later. Most of the time this
6111 : : * will immediately return.
6112 : : */
6113 : : for (;;)
6114 : : {
6115 : 247 : PGSemaphoreLock(MyProc->sem);
6116 [ + - ]: 247 : if (MyProc->lwWaiting == LW_WS_NOT_WAITING)
6117 : 247 : break;
59 andres@anarazel.de 6118 :UNC 0 : extraWaits++;
6119 : : }
6120 : :
6121 : : /*
6122 : : * Fix the process wait semaphore's count for any absorbed wakeups.
6123 : : */
59 andres@anarazel.de 6124 [ - + ]:GNC 247 : while (extraWaits-- > 0)
59 andres@anarazel.de 6125 :UNC 0 : PGSemaphoreUnlock(MyProc->sem);
6126 : : }
59 andres@anarazel.de 6127 :GNC 676 : }
6128 : :
6129 : : /*
6130 : : * Stop treating lock as held by current backend.
6131 : : *
6132 : : * After calling this function it's the callers responsibility to ensure that
6133 : : * the lock gets released, even in case of an error. This only is desirable if
6134 : : * the lock is going to be released in a different process than the process
6135 : : * that acquired it.
6136 : : */
6137 : : static inline void
59 andres@anarazel.de 6138 :UNC 0 : BufferLockDisown(Buffer buffer, BufferDesc *buf_hdr)
6139 : : {
6140 : 0 : BufferLockDisownInternal(buffer, buf_hdr);
6141 [ # # ]: 0 : RESUME_INTERRUPTS();
6142 : 0 : }
6143 : :
6144 : : /*
6145 : : * Stop treating lock as held by current backend.
6146 : : *
6147 : : * This is the code that can be shared between actually releasing a lock
6148 : : * (BufferLockUnlock()) and just not tracking ownership of the lock anymore
6149 : : * without releasing the lock (BufferLockDisown()).
6150 : : */
6151 : : static inline int
59 andres@anarazel.de 6152 :GNC 86473517 : BufferLockDisownInternal(Buffer buffer, BufferDesc *buf_hdr)
6153 : : {
6154 : : BufferLockMode mode;
6155 : : PrivateRefCountEntry *ref;
6156 : :
6157 : 86473517 : ref = GetPrivateRefCountEntry(buffer, false);
6158 [ - + ]: 86473517 : if (ref == NULL)
59 andres@anarazel.de 6159 [ # # ]:UNC 0 : elog(ERROR, "lock %d is not held", buffer);
59 andres@anarazel.de 6160 :GNC 86473517 : mode = ref->data.lockmode;
6161 : 86473517 : ref->data.lockmode = BUFFER_LOCK_UNLOCK;
6162 : :
6163 : 86473517 : return mode;
6164 : : }
6165 : :
6166 : : /*
6167 : : * Wakeup all the lockers that currently have a chance to acquire the lock.
6168 : : *
6169 : : * wake_exclusive indicates whether exclusive lock waiters should be woken up.
6170 : : */
6171 : : static void
6172 : 22367 : BufferLockWakeup(BufferDesc *buf_hdr, bool wake_exclusive)
6173 : : {
6174 : 22367 : bool new_wake_in_progress = false;
6175 : 22367 : bool wake_share_exclusive = true;
6176 : : proclist_head wakeup;
6177 : : proclist_mutable_iter iter;
6178 : :
6179 : 22367 : proclist_init(&wakeup);
6180 : :
6181 : : /* lock wait list while collecting backends to wake up */
6182 : 22367 : LockBufHdr(buf_hdr);
6183 : :
6184 [ + + + + : 33837 : proclist_foreach_modify(iter, &buf_hdr->lock_waiters, lwWaitLink)
+ + ]
6185 : : {
6186 : 25187 : PGPROC *waiter = GetPGProcByNumber(iter.cur);
6187 : :
6188 : : /*
6189 : : * Already woke up a conflicting lock, so skip over this wait list
6190 : : * entry.
6191 : : */
6192 [ + + + + ]: 25187 : if (!wake_exclusive && waiter->lwWaitMode == BUFFER_LOCK_EXCLUSIVE)
6193 : 1194 : continue;
6194 [ + + - + ]: 23993 : if (!wake_share_exclusive && waiter->lwWaitMode == BUFFER_LOCK_SHARE_EXCLUSIVE)
59 andres@anarazel.de 6195 :UNC 0 : continue;
6196 : :
59 andres@anarazel.de 6197 :GNC 23993 : proclist_delete(&buf_hdr->lock_waiters, iter.cur, lwWaitLink);
6198 : 23993 : proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
6199 : :
6200 : : /*
6201 : : * Prevent additional wakeups until retryer gets to run. Backends that
6202 : : * are just waiting for the lock to become free don't retry
6203 : : * automatically.
6204 : : */
6205 : 23993 : new_wake_in_progress = true;
6206 : :
6207 : : /*
6208 : : * Signal that the process isn't on the wait list anymore. This allows
6209 : : * BufferLockDequeueSelf() to remove itself from the waitlist with a
6210 : : * proclist_delete(), rather than having to check if it has been
6211 : : * removed from the list.
6212 : : */
6213 [ - + ]: 23993 : Assert(waiter->lwWaiting == LW_WS_WAITING);
6214 : 23993 : waiter->lwWaiting = LW_WS_PENDING_WAKEUP;
6215 : :
6216 : : /*
6217 : : * Don't wakeup further waiters after waking a conflicting waiter.
6218 : : */
6219 [ + + ]: 23993 : if (waiter->lwWaitMode == BUFFER_LOCK_SHARE)
6220 : : {
6221 : : /*
6222 : : * Share locks conflict with exclusive locks.
6223 : : */
6224 : 10185 : wake_exclusive = false;
6225 : : }
6226 [ + + ]: 13808 : else if (waiter->lwWaitMode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6227 : : {
6228 : : /*
6229 : : * Share-exclusive locks conflict with share-exclusive and
6230 : : * exclusive locks.
6231 : : */
6232 : 91 : wake_exclusive = false;
6233 : 91 : wake_share_exclusive = false;
6234 : : }
6235 [ + - ]: 13717 : else if (waiter->lwWaitMode == BUFFER_LOCK_EXCLUSIVE)
6236 : : {
6237 : : /*
6238 : : * Exclusive locks conflict with all other locks, there's no point
6239 : : * in waking up anybody else.
6240 : : */
6241 : 13717 : break;
6242 : : }
6243 : : }
6244 : :
6245 [ + + - + ]: 22367 : Assert(proclist_is_empty(&wakeup) || pg_atomic_read_u64(&buf_hdr->state) & BM_LOCK_HAS_WAITERS);
6246 : :
6247 : : /* unset required flags, and release lock, in one fell swoop */
6248 : : {
6249 : : uint64 old_state;
6250 : : uint64 desired_state;
6251 : :
6252 : 22367 : old_state = pg_atomic_read_u64(&buf_hdr->state);
6253 : : while (true)
6254 : : {
6255 : 22368 : desired_state = old_state;
6256 : :
6257 : : /* compute desired flags */
6258 : :
6259 [ + + ]: 22368 : if (new_wake_in_progress)
6260 : 22269 : desired_state |= BM_LOCK_WAKE_IN_PROGRESS;
6261 : : else
6262 : 99 : desired_state &= ~BM_LOCK_WAKE_IN_PROGRESS;
6263 : :
6264 [ + + ]: 22368 : if (proclist_is_empty(&buf_hdr->lock_waiters))
6265 : 18590 : desired_state &= ~BM_LOCK_HAS_WAITERS;
6266 : :
6267 : 22368 : desired_state &= ~BM_LOCKED; /* release lock */
6268 : :
6269 [ + + ]: 22368 : if (pg_atomic_compare_exchange_u64(&buf_hdr->state, &old_state,
6270 : : desired_state))
6271 : 22367 : break;
6272 : : }
6273 : : }
6274 : :
6275 : : /* Awaken any waiters I removed from the queue. */
6276 [ + + + + : 46360 : proclist_foreach_modify(iter, &wakeup, lwWaitLink)
+ + ]
6277 : : {
6278 : 23993 : PGPROC *waiter = GetPGProcByNumber(iter.cur);
6279 : :
6280 : 23993 : proclist_delete(&wakeup, iter.cur, lwWaitLink);
6281 : :
6282 : : /*
6283 : : * Guarantee that lwWaiting being unset only becomes visible once the
6284 : : * unlink from the link has completed. Otherwise the target backend
6285 : : * could be woken up for other reason and enqueue for a new lock - if
6286 : : * that happens before the list unlink happens, the list would end up
6287 : : * being corrupted.
6288 : : *
6289 : : * The barrier pairs with the LockBufHdr() when enqueuing for another
6290 : : * lock.
6291 : : */
6292 : 23993 : pg_write_barrier();
6293 : 23993 : waiter->lwWaiting = LW_WS_NOT_WAITING;
6294 : 23993 : PGSemaphoreUnlock(waiter->sem);
6295 : : }
6296 : 22367 : }
6297 : :
6298 : : /*
6299 : : * Compute subtraction from buffer state for a release of a held lock in
6300 : : * `mode`.
6301 : : *
6302 : : * This is separated from BufferLockUnlock() as we want to combine the lock
6303 : : * release with other atomic operations when possible, leading to the lock
6304 : : * release being done in multiple places, each needing to compute what to
6305 : : * subtract from the lock state.
6306 : : */
6307 : : static inline uint64
6308 : 86473517 : BufferLockReleaseSub(BufferLockMode mode)
6309 : : {
6310 : : /*
6311 : : * Turns out that a switch() leads gcc to generate sufficiently worse code
6312 : : * for this to show up in profiles...
6313 : : */
6314 [ + + ]: 86473517 : if (mode == BUFFER_LOCK_EXCLUSIVE)
6315 : 26198945 : return BM_LOCK_VAL_EXCLUSIVE;
6316 [ + + ]: 60274572 : else if (mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6317 : 3613169 : return BM_LOCK_VAL_SHARE_EXCLUSIVE;
6318 : : else
6319 : : {
6320 [ - + ]: 56661403 : Assert(mode == BUFFER_LOCK_SHARE);
6321 : 56661403 : return BM_LOCK_VAL_SHARED;
6322 : : }
6323 : :
6324 : : return 0; /* keep compiler quiet */
6325 : : }
6326 : :
6327 : : /*
6328 : : * Handle work that needs to be done after releasing a lock that was held in
6329 : : * `mode`, where `lockstate` is the result of the atomic operation modifying
6330 : : * the state variable.
6331 : : *
6332 : : * This is separated from BufferLockUnlock() as we want to combine the lock
6333 : : * release with other atomic operations when possible, leading to the lock
6334 : : * release being done in multiple places.
6335 : : */
6336 : : static void
6337 : 86473517 : BufferLockProcessRelease(BufferDesc *buf_hdr, BufferLockMode mode, uint64 lockstate)
6338 : : {
6339 : 86473517 : bool check_waiters = false;
6340 : 86473517 : bool wake_exclusive = false;
6341 : :
6342 : : /* nobody else can have that kind of lock */
6343 [ - + ]: 86473517 : Assert(!(lockstate & BM_LOCK_VAL_EXCLUSIVE));
6344 : :
6345 : : /*
6346 : : * If we're still waiting for backends to get scheduled, don't wake them
6347 : : * up again. Otherwise check if we need to look through the waitqueue to
6348 : : * wake other backends.
6349 : : */
6350 [ + + ]: 86473517 : if ((lockstate & BM_LOCK_HAS_WAITERS) &&
6351 [ + + ]: 86321 : !(lockstate & BM_LOCK_WAKE_IN_PROGRESS))
6352 : : {
6353 [ + + ]: 51571 : if ((lockstate & BM_LOCK_MASK) == 0)
6354 : : {
6355 : : /*
6356 : : * We released a lock and the lock was, in that moment, free. We
6357 : : * therefore can wake waiters for any kind of lock.
6358 : : */
6359 : 22364 : check_waiters = true;
6360 : 22364 : wake_exclusive = true;
6361 : : }
6362 [ + + ]: 29207 : else if (mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6363 : : {
6364 : : /*
6365 : : * We released the lock, but another backend still holds a lock.
6366 : : * We can't have released an exclusive lock, as there couldn't
6367 : : * have been other lock holders. If we released a share lock, no
6368 : : * waiters need to be woken up, as there must be other share
6369 : : * lockers. However, if we held a share-exclusive lock, another
6370 : : * backend now could acquire a share-exclusive lock.
6371 : : */
6372 : 3 : check_waiters = true;
6373 : 3 : wake_exclusive = false;
6374 : : }
6375 : : }
6376 : :
6377 : : /*
6378 : : * As waking up waiters requires the spinlock to be acquired, only do so
6379 : : * if necessary.
6380 : : */
6381 [ + + ]: 86473517 : if (check_waiters)
6382 : 22367 : BufferLockWakeup(buf_hdr, wake_exclusive);
6383 : 86473517 : }
6384 : :
6385 : : /*
6386 : : * BufferLockHeldByMeInMode - test whether my process holds the content lock
6387 : : * in the specified mode
6388 : : *
6389 : : * This is meant as debug support only.
6390 : : */
6391 : : static bool
6392 : 86155415 : BufferLockHeldByMeInMode(BufferDesc *buf_hdr, BufferLockMode mode)
6393 : : {
6394 : : PrivateRefCountEntry *entry =
6395 : 86155415 : GetPrivateRefCountEntry(BufferDescriptorGetBuffer(buf_hdr), false);
6396 : :
6397 [ - + ]: 86155415 : if (!entry)
59 andres@anarazel.de 6398 :UNC 0 : return false;
6399 : : else
59 andres@anarazel.de 6400 :GNC 86155415 : return entry->data.lockmode == mode;
6401 : : }
6402 : :
6403 : : /*
6404 : : * BufferLockHeldByMe - test whether my process holds the content lock in any
6405 : : * mode
6406 : : *
6407 : : * This is meant as debug support only.
6408 : : */
6409 : : static bool
6410 : 62139679 : BufferLockHeldByMe(BufferDesc *buf_hdr)
6411 : : {
6412 : : PrivateRefCountEntry *entry =
6413 : 62139679 : GetPrivateRefCountEntry(BufferDescriptorGetBuffer(buf_hdr), false);
6414 : :
6415 [ - + ]: 62139679 : if (!entry)
59 andres@anarazel.de 6416 :UNC 0 : return false;
6417 : : else
59 andres@anarazel.de 6418 :GNC 62139679 : return entry->data.lockmode != BUFFER_LOCK_UNLOCK;
6419 : : }
6420 : :
6421 : : /*
6422 : : * Release the content lock for the buffer.
6423 : : */
6424 : : void
6425 : 91400711 : UnlockBuffer(Buffer buffer)
6426 : : {
6427 : : BufferDesc *buf_hdr;
6428 : :
2064 pg@bowt.ie 6429 [ - + + + :CBC 91400711 : Assert(BufferIsPinned(buffer));
- + ]
9952 vadim4o@yahoo.com 6430 [ + + ]: 91400711 : if (BufferIsLocal(buffer))
7289 tgl@sss.pgh.pa.us 6431 : 5253621 : return; /* local buffers need no lock */
6432 : :
59 andres@anarazel.de 6433 :GNC 86147090 : buf_hdr = GetBufferDescriptor(buffer - 1);
6434 : 86147090 : BufferLockUnlock(buffer, buf_hdr);
6435 : : }
6436 : :
6437 : : /*
6438 : : * Acquire the content_lock for the buffer.
6439 : : */
6440 : : void
6441 : 90047005 : LockBufferInternal(Buffer buffer, BufferLockMode mode)
6442 : : {
6443 : : BufferDesc *buf_hdr;
6444 : :
6445 : : /*
6446 : : * We can't wait if we haven't got a PGPROC. This should only occur
6447 : : * during bootstrap or shared memory initialization. Put an Assert here
6448 : : * to catch unsafe coding practices.
6449 : : */
6450 [ - + - - ]: 90047005 : Assert(!(MyProc == NULL && IsUnderPostmaster));
6451 : :
6452 : : /* handled in LockBuffer() wrapper */
6453 [ - + ]: 90047005 : Assert(mode != BUFFER_LOCK_UNLOCK);
6454 : :
6455 [ - + + + : 90047005 : Assert(BufferIsPinned(buffer));
- + ]
6456 [ + + ]: 90047005 : if (BufferIsLocal(buffer))
6457 : 5175782 : return; /* local buffers need no lock */
6458 : :
6459 : 84871223 : buf_hdr = GetBufferDescriptor(buffer - 1);
6460 : :
6461 : : /*
6462 : : * Test the most frequent lock modes first. While a switch (mode) would be
6463 : : * nice, at least gcc generates considerably worse code for it.
6464 : : *
6465 : : * Call BufferLockAcquire() with a constant argument for mode, to generate
6466 : : * more efficient code for the different lock modes.
6467 : : */
6468 [ + + ]: 84871223 : if (mode == BUFFER_LOCK_SHARE)
6469 : 59668844 : BufferLockAcquire(buffer, buf_hdr, BUFFER_LOCK_SHARE);
9952 vadim4o@yahoo.com 6470 [ + - ]:CBC 25202379 : else if (mode == BUFFER_LOCK_EXCLUSIVE)
59 andres@anarazel.de 6471 :GNC 25202379 : BufferLockAcquire(buffer, buf_hdr, BUFFER_LOCK_EXCLUSIVE);
59 andres@anarazel.de 6472 [ # # ]:UNC 0 : else if (mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6473 : 0 : BufferLockAcquire(buffer, buf_hdr, BUFFER_LOCK_SHARE_EXCLUSIVE);
6474 : : else
8270 tgl@sss.pgh.pa.us 6475 [ # # ]:UBC 0 : elog(ERROR, "unrecognized buffer lock mode: %d", mode);
6476 : : }
6477 : :
6478 : : /*
6479 : : * Acquire the content_lock for the buffer, but only if we don't have to wait.
6480 : : *
6481 : : * This assumes the caller wants BUFFER_LOCK_EXCLUSIVE mode.
6482 : : */
6483 : : bool
8253 tgl@sss.pgh.pa.us 6484 :CBC 1062053 : ConditionalLockBuffer(Buffer buffer)
6485 : : {
6486 : : BufferDesc *buf;
6487 : :
2064 pg@bowt.ie 6488 [ - + + + : 1062053 : Assert(BufferIsPinned(buffer));
- + ]
8253 tgl@sss.pgh.pa.us 6489 [ + + ]: 1062053 : if (BufferIsLocal(buffer))
6490 : 64596 : return true; /* act as though we got it */
6491 : :
4063 andres@anarazel.de 6492 : 997457 : buf = GetBufferDescriptor(buffer - 1);
6493 : :
59 andres@anarazel.de 6494 :GNC 997457 : return BufferLockConditional(buffer, buf, BUFFER_LOCK_EXCLUSIVE);
6495 : : }
6496 : :
6497 : : /*
6498 : : * Verify that this backend is pinning the buffer exactly once.
6499 : : *
6500 : : * NOTE: Like in BufferIsPinned(), what we check here is that *this* backend
6501 : : * holds a pin on the buffer. We do not care whether some other backend does.
6502 : : */
6503 : : void
1075 andres@anarazel.de 6504 :CBC 4164147 : CheckBufferIsPinnedOnce(Buffer buffer)
6505 : : {
6506 [ + + ]: 4164147 : if (BufferIsLocal(buffer))
6507 : : {
6508 [ - + ]: 791 : if (LocalRefCount[-buffer - 1] != 1)
1075 andres@anarazel.de 6509 [ # # ]:UBC 0 : elog(ERROR, "incorrect local pin count: %d",
6510 : : LocalRefCount[-buffer - 1]);
6511 : : }
6512 : : else
6513 : : {
1075 andres@anarazel.de 6514 [ - + ]:CBC 4163356 : if (GetPrivateRefCount(buffer) != 1)
1075 andres@anarazel.de 6515 [ # # ]:UBC 0 : elog(ERROR, "incorrect local pin count: %d",
6516 : : GetPrivateRefCount(buffer));
6517 : : }
1075 andres@anarazel.de 6518 :CBC 4164147 : }
6519 : :
6520 : : /*
6521 : : * LockBufferForCleanup - lock a buffer in preparation for deleting items
6522 : : *
6523 : : * Items may be deleted from a disk page only when the caller (a) holds an
6524 : : * exclusive lock on the buffer and (b) has observed that no other backend
6525 : : * holds a pin on the buffer. If there is a pin, then the other backend
6526 : : * might have a pointer into the buffer (for example, a heapscan reference
6527 : : * to an item --- see README for more details). It's OK if a pin is added
6528 : : * after the cleanup starts, however; the newly-arrived backend will be
6529 : : * unable to look at the page until we release the exclusive lock.
6530 : : *
6531 : : * To implement this protocol, a would-be deleter must pin the buffer and
6532 : : * then call LockBufferForCleanup(). LockBufferForCleanup() is similar to
6533 : : * LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE), except that it loops until
6534 : : * it has successfully observed pin count = 1.
6535 : : */
6536 : : void
9018 tgl@sss.pgh.pa.us 6537 : 24887 : LockBufferForCleanup(Buffer buffer)
6538 : : {
6539 : : BufferDesc *bufHdr;
1892 fujii@postgresql.org 6540 : 24887 : TimestampTz waitStart = 0;
1119 drowley@postgresql.o 6541 : 24887 : bool waiting = false;
1892 fujii@postgresql.org 6542 : 24887 : bool logged_recovery_conflict = false;
6543 : :
2064 pg@bowt.ie 6544 [ - + + + : 24887 : Assert(BufferIsPinned(buffer));
- + ]
7820 tgl@sss.pgh.pa.us 6545 [ - + ]: 24887 : Assert(PinCountWaitBuf == NULL);
6546 : :
1075 andres@anarazel.de 6547 : 24887 : CheckBufferIsPinnedOnce(buffer);
6548 : :
6549 : : /*
6550 : : * We do not yet need to be worried about in-progress AIOs holding a pin,
6551 : : * as we, so far, only support doing reads via AIO and this function can
6552 : : * only be called once the buffer is valid (i.e. no read can be in
6553 : : * flight).
6554 : : */
6555 : :
6556 : : /* Nobody else to wait for */
9018 tgl@sss.pgh.pa.us 6557 [ + + ]: 24887 : if (BufferIsLocal(buffer))
6558 : 16 : return;
6559 : :
4063 andres@anarazel.de 6560 : 24871 : bufHdr = GetBufferDescriptor(buffer - 1);
6561 : :
6562 : : for (;;)
9018 tgl@sss.pgh.pa.us 6563 : 100 : {
6564 : : uint64 buf_state;
59 andres@anarazel.de 6565 :GNC 24971 : uint64 unset_bits = 0;
6566 : :
6567 : : /* Try to acquire lock */
9018 tgl@sss.pgh.pa.us 6568 :CBC 24971 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
3626 andres@anarazel.de 6569 : 24971 : buf_state = LockBufHdr(bufHdr);
6570 : :
6571 [ - + ]: 24971 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
6572 [ + + ]: 24971 : if (BUF_STATE_GET_REFCOUNT(buf_state) == 1)
6573 : : {
6574 : : /* Successfully acquired exclusive lock with pincount 1 */
129 andres@anarazel.de 6575 :GNC 24871 : UnlockBufHdr(bufHdr);
6576 : :
6577 : : /*
6578 : : * Emit the log message if recovery conflict on buffer pin was
6579 : : * resolved but the startup process waited longer than
6580 : : * deadlock_timeout for it.
6581 : : */
1887 fujii@postgresql.org 6582 [ + + ]:CBC 24871 : if (logged_recovery_conflict)
33 heikki.linnakangas@i 6583 :GNC 2 : LogRecoveryConflict(RECOVERY_CONFLICT_BUFFERPIN,
6584 : : waitStart, GetCurrentTimestamp(),
6585 : : NULL, false);
6586 : :
1119 drowley@postgresql.o 6587 [ + + ]:CBC 24871 : if (waiting)
6588 : : {
6589 : : /* reset ps display to remove the suffix if we added one */
6590 : 2 : set_ps_display_remove_suffix();
6591 : 2 : waiting = false;
6592 : : }
9018 tgl@sss.pgh.pa.us 6593 : 24871 : return;
6594 : : }
6595 : : /* Failed, so mark myself as waiting for pincount 1 */
3626 andres@anarazel.de 6596 [ - + ]: 100 : if (buf_state & BM_PIN_COUNT_WAITER)
6597 : : {
129 andres@anarazel.de 6598 :UNC 0 : UnlockBufHdr(bufHdr);
9018 tgl@sss.pgh.pa.us 6599 :UBC 0 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
8270 6600 [ # # ]: 0 : elog(ERROR, "multiple backends attempting to wait for pincount 1");
6601 : : }
752 heikki.linnakangas@i 6602 :CBC 100 : bufHdr->wait_backend_pgprocno = MyProcNumber;
7820 tgl@sss.pgh.pa.us 6603 : 100 : PinCountWaitBuf = bufHdr;
129 andres@anarazel.de 6604 :GNC 100 : UnlockBufHdrExt(bufHdr, buf_state,
6605 : : BM_PIN_COUNT_WAITER, 0,
6606 : : 0);
9018 tgl@sss.pgh.pa.us 6607 :CBC 100 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
6608 : :
6609 : : /* Wait to be signaled by UnpinBuffer() */
5895 simon@2ndQuadrant.co 6610 [ + + ]: 100 : if (InHotStandby)
6611 : : {
1119 drowley@postgresql.o 6612 [ + + ]: 10 : if (!waiting)
6613 : : {
6614 : : /* adjust the process title to indicate that it's waiting */
6615 : 2 : set_ps_display_suffix("waiting");
6616 : 2 : waiting = true;
6617 : : }
6618 : :
6619 : : /*
6620 : : * Emit the log message if the startup process is waiting longer
6621 : : * than deadlock_timeout for recovery conflict on buffer pin.
6622 : : *
6623 : : * Skip this if first time through because the startup process has
6624 : : * not started waiting yet in this case. So, the wait start
6625 : : * timestamp is set after this logic.
6626 : : */
1892 fujii@postgresql.org 6627 [ + + + + ]: 10 : if (waitStart != 0 && !logged_recovery_conflict)
6628 : : {
6629 : 3 : TimestampTz now = GetCurrentTimestamp();
6630 : :
6631 [ + + ]: 3 : if (TimestampDifferenceExceeds(waitStart, now,
6632 : : DeadlockTimeout))
6633 : : {
33 heikki.linnakangas@i 6634 :GNC 2 : LogRecoveryConflict(RECOVERY_CONFLICT_BUFFERPIN,
6635 : : waitStart, now, NULL, true);
1892 fujii@postgresql.org 6636 :CBC 2 : logged_recovery_conflict = true;
6637 : : }
6638 : : }
6639 : :
6640 : : /*
6641 : : * Set the wait start timestamp if logging is enabled and first
6642 : : * time through.
6643 : : */
6644 [ + - + + ]: 10 : if (log_recovery_conflict_waits && waitStart == 0)
6645 : 2 : waitStart = GetCurrentTimestamp();
6646 : :
6647 : : /* Publish the bufid that Startup process waits on */
5895 simon@2ndQuadrant.co 6648 : 10 : SetStartupBufferPinWaitBufId(buffer - 1);
6649 : : /* Set alarm and then wait to be signaled by UnpinBuffer() */
6650 : 10 : ResolveRecoveryConflictWithBufferPin();
6651 : : /* Reset the published bufid */
6652 : 10 : SetStartupBufferPinWaitBufId(-1);
6653 : : }
6654 : : else
102 andres@anarazel.de 6655 :GNC 90 : ProcWaitForSignal(WAIT_EVENT_BUFFER_CLEANUP);
6656 : :
6657 : : /*
6658 : : * Remove flag marking us as waiter. Normally this will not be set
6659 : : * anymore, but ProcWaitForSignal() can return for other signals as
6660 : : * well. We take care to only reset the flag if we're the waiter, as
6661 : : * theoretically another backend could have started waiting. That's
6662 : : * impossible with the current usages due to table level locking, but
6663 : : * better be safe.
6664 : : */
3626 andres@anarazel.de 6665 :CBC 100 : buf_state = LockBufHdr(bufHdr);
6666 [ + + ]: 100 : if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
752 heikki.linnakangas@i 6667 [ + - ]: 8 : bufHdr->wait_backend_pgprocno == MyProcNumber)
129 andres@anarazel.de 6668 :GNC 8 : unset_bits |= BM_PIN_COUNT_WAITER;
6669 : :
6670 : 100 : UnlockBufHdrExt(bufHdr, buf_state,
6671 : : 0, unset_bits,
6672 : : 0);
6673 : :
7820 tgl@sss.pgh.pa.us 6674 :CBC 100 : PinCountWaitBuf = NULL;
6675 : : /* Loop back and try again */
6676 : : }
6677 : : }
6678 : :
6679 : : /*
6680 : : * Check called from ProcessRecoveryConflictInterrupts() when Startup process
6681 : : * requests cancellation of all pin holders that are blocking it.
6682 : : */
6683 : : bool
5895 simon@2ndQuadrant.co 6684 : 4 : HoldingBufferPinThatDelaysRecovery(void)
6685 : : {
5861 bruce@momjian.us 6686 : 4 : int bufid = GetStartupBufferPinWaitBufId();
6687 : :
6688 : : /*
6689 : : * If we get woken slowly then it's possible that the Startup process was
6690 : : * already woken by other backends before we got here. Also possible that
6691 : : * we get here by multiple interrupts or interrupts at inappropriate
6692 : : * times, so make sure we do nothing if the bufid is not set.
6693 : : */
5895 simon@2ndQuadrant.co 6694 [ + + ]: 4 : if (bufid < 0)
6695 : 2 : return false;
6696 : :
4215 andres@anarazel.de 6697 [ + - ]: 2 : if (GetPrivateRefCount(bufid + 1) > 0)
5895 simon@2ndQuadrant.co 6698 : 2 : return true;
6699 : :
5895 simon@2ndQuadrant.co 6700 :UBC 0 : return false;
6701 : : }
6702 : :
6703 : : /*
6704 : : * ConditionalLockBufferForCleanup - as above, but don't wait to get the lock
6705 : : *
6706 : : * We won't loop, but just check once to see if the pin count is OK. If
6707 : : * not, return false with no lock held.
6708 : : */
6709 : : bool
6751 tgl@sss.pgh.pa.us 6710 :CBC 115453 : ConditionalLockBufferForCleanup(Buffer buffer)
6711 : : {
6712 : : BufferDesc *bufHdr;
6713 : : uint64 buf_state,
6714 : : refcount;
6715 : :
6716 [ - + ]: 115453 : Assert(BufferIsValid(buffer));
6717 : :
6718 : : /* see AIO related comment in LockBufferForCleanup() */
6719 : :
6720 [ + + ]: 115453 : if (BufferIsLocal(buffer))
6721 : : {
3626 andres@anarazel.de 6722 : 803 : refcount = LocalRefCount[-buffer - 1];
6723 : : /* There should be exactly one pin */
6724 [ - + ]: 803 : Assert(refcount > 0);
6725 [ + + ]: 803 : if (refcount != 1)
6751 tgl@sss.pgh.pa.us 6726 : 21 : return false;
6727 : : /* Nobody else to wait for */
6728 : 782 : return true;
6729 : : }
6730 : :
6731 : : /* There should be exactly one local pin */
3626 andres@anarazel.de 6732 : 114650 : refcount = GetPrivateRefCount(buffer);
6733 [ - + ]: 114650 : Assert(refcount);
6734 [ + + ]: 114650 : if (refcount != 1)
6751 tgl@sss.pgh.pa.us 6735 : 259 : return false;
6736 : :
6737 : : /* Try to acquire lock */
6738 [ + + ]: 114391 : if (!ConditionalLockBuffer(buffer))
6739 : 27 : return false;
6740 : :
4063 andres@anarazel.de 6741 : 114364 : bufHdr = GetBufferDescriptor(buffer - 1);
3626 6742 : 114364 : buf_state = LockBufHdr(bufHdr);
6743 : 114364 : refcount = BUF_STATE_GET_REFCOUNT(buf_state);
6744 : :
6745 [ - + ]: 114364 : Assert(refcount > 0);
6746 [ + + ]: 114364 : if (refcount == 1)
6747 : : {
6748 : : /* Successfully acquired exclusive lock with pincount 1 */
129 andres@anarazel.de 6749 :GNC 114178 : UnlockBufHdr(bufHdr);
6751 tgl@sss.pgh.pa.us 6750 :CBC 114178 : return true;
6751 : : }
6752 : :
6753 : : /* Failed, so release the lock */
129 andres@anarazel.de 6754 :GNC 186 : UnlockBufHdr(bufHdr);
6751 tgl@sss.pgh.pa.us 6755 :CBC 186 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
6756 : 186 : return false;
6757 : : }
6758 : :
6759 : : /*
6760 : : * IsBufferCleanupOK - as above, but we already have the lock
6761 : : *
6762 : : * Check whether it's OK to perform cleanup on a buffer we've already
6763 : : * locked. If we observe that the pin count is 1, our exclusive lock
6764 : : * happens to be a cleanup lock, and we can proceed with anything that
6765 : : * would have been allowable had we sought a cleanup lock originally.
6766 : : */
6767 : : bool
3418 rhaas@postgresql.org 6768 : 2030 : IsBufferCleanupOK(Buffer buffer)
6769 : : {
6770 : : BufferDesc *bufHdr;
6771 : : uint64 buf_state;
6772 : :
6773 [ - + ]: 2030 : Assert(BufferIsValid(buffer));
6774 : :
6775 : : /* see AIO related comment in LockBufferForCleanup() */
6776 : :
6777 [ - + ]: 2030 : if (BufferIsLocal(buffer))
6778 : : {
6779 : : /* There should be exactly one pin */
3418 rhaas@postgresql.org 6780 [ # # ]:UBC 0 : if (LocalRefCount[-buffer - 1] != 1)
6781 : 0 : return false;
6782 : : /* Nobody else to wait for */
6783 : 0 : return true;
6784 : : }
6785 : :
6786 : : /* There should be exactly one local pin */
3418 rhaas@postgresql.org 6787 [ - + ]:CBC 2030 : if (GetPrivateRefCount(buffer) != 1)
3418 rhaas@postgresql.org 6788 :UBC 0 : return false;
6789 : :
3418 rhaas@postgresql.org 6790 :CBC 2030 : bufHdr = GetBufferDescriptor(buffer - 1);
6791 : :
6792 : : /* caller must hold exclusive lock on buffer */
158 andres@anarazel.de 6793 [ - + ]:GNC 2030 : Assert(BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_EXCLUSIVE));
6794 : :
3418 rhaas@postgresql.org 6795 :CBC 2030 : buf_state = LockBufHdr(bufHdr);
6796 : :
6797 [ - + ]: 2030 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
6798 [ + - ]: 2030 : if (BUF_STATE_GET_REFCOUNT(buf_state) == 1)
6799 : : {
6800 : : /* pincount is OK. */
129 andres@anarazel.de 6801 :GNC 2030 : UnlockBufHdr(bufHdr);
3418 rhaas@postgresql.org 6802 : 2030 : return true;
6803 : : }
6804 : :
129 andres@anarazel.de 6805 :UNC 0 : UnlockBufHdr(bufHdr);
3418 rhaas@postgresql.org 6806 : 0 : return false;
6807 : : }
6808 : :
6809 : : /*
6810 : : * Helper for BufferBeginSetHintBits() and BufferSetHintBits16().
6811 : : *
6812 : : * This checks if the current lock mode already suffices to allow hint bits
6813 : : * being set and, if not, whether the current lock can be upgraded.
6814 : : *
6815 : : * Updates *lockstate when returning true.
6816 : : */
6817 : : static inline bool
5 andres@anarazel.de 6818 :GNC 7112469 : SharedBufferBeginSetHintBits(Buffer buffer, BufferDesc *buf_hdr, uint64 *lockstate)
6819 : : {
6820 : : uint64 old_state;
6821 : : PrivateRefCountEntry *ref;
6822 : : BufferLockMode mode;
6823 : :
6824 : 7112469 : ref = GetPrivateRefCountEntry(buffer, true);
6825 : :
6826 [ - + ]: 7112469 : if (ref == NULL)
5 andres@anarazel.de 6827 [ # # ]:UNC 0 : elog(ERROR, "buffer is not pinned");
6828 : :
5 andres@anarazel.de 6829 :GNC 7112469 : mode = ref->data.lockmode;
6830 [ - + ]: 7112469 : if (mode == BUFFER_LOCK_UNLOCK)
5 andres@anarazel.de 6831 [ # # ]:UNC 0 : elog(ERROR, "buffer is not locked");
6832 : :
6833 : : /* we're done if we are already holding a sufficient lock level */
5 andres@anarazel.de 6834 [ + + + + ]:GNC 7112469 : if (mode == BUFFER_LOCK_EXCLUSIVE || mode == BUFFER_LOCK_SHARE_EXCLUSIVE)
6835 : : {
6836 : 4104881 : *lockstate = pg_atomic_read_u64(&buf_hdr->state);
6837 : 4104881 : return true;
6838 : : }
6839 : :
6840 : : /*
6841 : : * We are only holding a share lock right now, try to upgrade it to
6842 : : * SHARE_EXCLUSIVE.
6843 : : */
6844 [ - + ]: 3007588 : Assert(mode == BUFFER_LOCK_SHARE);
6845 : :
6846 : 3007588 : old_state = pg_atomic_read_u64(&buf_hdr->state);
6847 : : while (true)
6848 : 3 : {
6849 : : uint64 desired_state;
6850 : :
6851 : 3007591 : desired_state = old_state;
6852 : :
6853 : : /*
6854 : : * Can't upgrade if somebody else holds the lock in exclusive or
6855 : : * share-exclusive mode.
6856 : : */
6857 [ + + ]: 3007591 : if (unlikely((old_state & (BM_LOCK_VAL_EXCLUSIVE | BM_LOCK_VAL_SHARE_EXCLUSIVE)) != 0))
6858 : : {
6859 : 147 : return false;
6860 : : }
6861 : :
6862 : : /* currently held lock state */
6863 : 3007444 : desired_state -= BM_LOCK_VAL_SHARED;
6864 : :
6865 : : /* new lock level */
6866 : 3007444 : desired_state += BM_LOCK_VAL_SHARE_EXCLUSIVE;
6867 : :
6868 [ + + ]: 3007444 : if (likely(pg_atomic_compare_exchange_u64(&buf_hdr->state,
6869 : : &old_state, desired_state)))
6870 : : {
6871 : 3007441 : ref->data.lockmode = BUFFER_LOCK_SHARE_EXCLUSIVE;
6872 : 3007441 : *lockstate = desired_state;
6873 : :
6874 : 3007441 : return true;
6875 : : }
6876 : : }
6877 : : }
6878 : :
6879 : : /*
6880 : : * Try to acquire the right to set hint bits on the buffer.
6881 : : *
6882 : : * To be allowed to set hint bits, this backend needs to hold either a
6883 : : * share-exclusive or an exclusive lock. In case this backend only holds a
6884 : : * share lock, this function will try to upgrade the lock to
6885 : : * share-exclusive. The caller is only allowed to set hint bits if true is
6886 : : * returned.
6887 : : *
6888 : : * Once BufferBeginSetHintBits() has returned true, hint bits may be set
6889 : : * without further calls to BufferBeginSetHintBits(), until the buffer is
6890 : : * unlocked.
6891 : : *
6892 : : *
6893 : : * Requiring a share-exclusive lock to set hint bits prevents setting hint
6894 : : * bits on buffers that are currently being written out, which could corrupt
6895 : : * the checksum on the page. Flushing buffers also requires a share-exclusive
6896 : : * lock.
6897 : : *
6898 : : * Due to a lock >= share-exclusive being required to set hint bits, only one
6899 : : * backend can set hint bits at a time. Allowing multiple backends to set hint
6900 : : * bits would require more complicated locking: For setting hint bits we'd
6901 : : * need to store the count of backends currently setting hint bits, for I/O we
6902 : : * would need another lock-level conflicting with the hint-setting
6903 : : * lock-level. Given that the share-exclusive lock for setting hint bits is
6904 : : * only held for a short time, that backends often would just set the same
6905 : : * hint bits and that the cost of occasionally not setting hint bits in hotly
6906 : : * accessed pages is fairly low, this seems like an acceptable tradeoff.
6907 : : */
6908 : : bool
6909 : 283459 : BufferBeginSetHintBits(Buffer buffer)
6910 : : {
6911 : : BufferDesc *buf_hdr;
6912 : : uint64 lockstate;
6913 : :
6914 [ + + ]: 283459 : if (BufferIsLocal(buffer))
6915 : : {
6916 : : /*
6917 : : * NB: Will need to check if there is a write in progress, once it is
6918 : : * possible for writes to be done asynchronously.
6919 : : */
6920 : 6134 : return true;
6921 : : }
6922 : :
6923 : 277325 : buf_hdr = GetBufferDescriptor(buffer - 1);
6924 : :
6925 : 277325 : return SharedBufferBeginSetHintBits(buffer, buf_hdr, &lockstate);
6926 : : }
6927 : :
6928 : : /*
6929 : : * End a phase of setting hint bits on this buffer, started with
6930 : : * BufferBeginSetHintBits().
6931 : : *
6932 : : * This would strictly speaking not be required (i.e. the caller could do
6933 : : * MarkBufferDirtyHint() if so desired), but allows us to perform some sanity
6934 : : * checks.
6935 : : */
6936 : : void
6937 : 283445 : BufferFinishSetHintBits(Buffer buffer, bool mark_dirty, bool buffer_std)
6938 : : {
6939 [ + + ]: 283445 : if (!BufferIsLocal(buffer))
6940 [ + + - + ]: 277311 : Assert(BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_SHARE_EXCLUSIVE) ||
6941 : : BufferIsLockedByMeInMode(buffer, BUFFER_LOCK_EXCLUSIVE));
6942 : :
6943 [ + + ]: 283445 : if (mark_dirty)
6944 : 222335 : MarkBufferDirtyHint(buffer, buffer_std);
6945 : 283445 : }
6946 : :
6947 : : /*
6948 : : * Try to set hint bits on a single 16bit value in a buffer.
6949 : : *
6950 : : * If hint bits are allowed to be set, set *ptr = val, try to mark the buffer
6951 : : * dirty and return true. Otherwise false is returned.
6952 : : *
6953 : : * *ptr needs to be a pointer to memory within the buffer.
6954 : : *
6955 : : * This is a bit faster than BufferBeginSetHintBits() /
6956 : : * BufferFinishSetHintBits() when setting hints once in a buffer, but slower
6957 : : * than the former when setting hint bits multiple times in the same buffer.
6958 : : */
6959 : : bool
6960 : 7074618 : BufferSetHintBits16(uint16 *ptr, uint16 val, Buffer buffer)
6961 : : {
6962 : : BufferDesc *buf_hdr;
6963 : : uint64 lockstate;
6964 : : #ifdef USE_ASSERT_CHECKING
6965 : : char *page;
6966 : :
6967 : : /* verify that the address is on the page */
6968 : 7074618 : page = BufferGetPage(buffer);
6969 [ + - - + ]: 7074618 : Assert((char *) ptr >= page && (char *) ptr < (page + BLCKSZ));
6970 : : #endif
6971 : :
6972 [ + + ]: 7074618 : if (BufferIsLocal(buffer))
6973 : : {
6974 : 239474 : *ptr = val;
6975 : :
6976 : 239474 : MarkLocalBufferDirty(buffer);
6977 : :
6978 : 239474 : return true;
6979 : : }
6980 : :
6981 : 6835144 : buf_hdr = GetBufferDescriptor(buffer - 1);
6982 : :
6983 [ + + ]: 6835144 : if (SharedBufferBeginSetHintBits(buffer, buf_hdr, &lockstate))
6984 : : {
6985 : 6835011 : *ptr = val;
6986 : :
6987 : 6835011 : MarkSharedBufferDirtyHint(buffer, buf_hdr, lockstate, true);
6988 : :
5 andres@anarazel.de 6989 :CBC 6835011 : return true;
6990 : : }
6991 : :
5 andres@anarazel.de 6992 :GBC 133 : return false;
6993 : : }
6994 : :
6995 : :
6996 : : /*
6997 : : * Functions for buffer I/O handling
6998 : : *
6999 : : * Also note that these are used only for shared buffers, not local ones.
7000 : : */
7001 : :
7002 : : /*
7003 : : * WaitIO -- Block until the IO_IN_PROGRESS flag on 'buf' is cleared.
7004 : : */
7005 : : static void
3772 rhaas@postgresql.org 7006 :CBC 2719 : WaitIO(BufferDesc *buf)
7007 : : {
1830 tmunro@postgresql.or 7008 : 2719 : ConditionVariable *cv = BufferDescriptorGetIOCV(buf);
7009 : :
7010 : 2719 : ConditionVariablePrepareToSleep(cv);
7011 : : for (;;)
7681 tgl@sss.pgh.pa.us 7012 : 2707 : {
7013 : : uint64 buf_state;
7014 : : PgAioWaitRef iow;
7015 : :
7016 : : /*
7017 : : * It may not be necessary to acquire the spinlock to check the flag
7018 : : * here, but since this test is essential for correctness, we'd better
7019 : : * play it safe.
7020 : : */
3626 andres@anarazel.de 7021 : 5426 : buf_state = LockBufHdr(buf);
7022 : :
7023 : : /*
7024 : : * Copy the wait reference while holding the spinlock. This protects
7025 : : * against a concurrent TerminateBufferIO() in another backend from
7026 : : * clearing the wref while it's being read.
7027 : : */
350 7028 : 5426 : iow = buf->io_wref;
129 andres@anarazel.de 7029 :GNC 5426 : UnlockBufHdr(buf);
7030 : :
7031 : : /* no IO in progress, we don't need to wait */
3626 andres@anarazel.de 7032 [ + + ]:CBC 5426 : if (!(buf_state & BM_IO_IN_PROGRESS))
7681 tgl@sss.pgh.pa.us 7033 : 2719 : break;
7034 : :
7035 : : /*
7036 : : * The buffer has asynchronous IO in progress, wait for it to
7037 : : * complete.
7038 : : */
350 andres@anarazel.de 7039 [ + + ]: 2707 : if (pgaio_wref_valid(&iow))
7040 : : {
7041 : 2410 : pgaio_wref_wait(&iow);
7042 : :
7043 : : /*
7044 : : * The AIO subsystem internally uses condition variables and thus
7045 : : * might remove this backend from the BufferDesc's CV. While that
7046 : : * wouldn't cause a correctness issue (the first CV sleep just
7047 : : * immediately returns if not already registered), it seems worth
7048 : : * avoiding unnecessary loop iterations, given that we take care
7049 : : * to do so at the start of the function.
7050 : : */
7051 : 2410 : ConditionVariablePrepareToSleep(cv);
7052 : 2410 : continue;
7053 : : }
7054 : :
7055 : : /* wait on BufferDesc->cv, e.g. for concurrent synchronous IO */
1830 tmunro@postgresql.or 7056 : 297 : ConditionVariableSleep(cv, WAIT_EVENT_BUFFER_IO);
7057 : : }
7058 : 2719 : ConditionVariableCancelSleep();
7681 tgl@sss.pgh.pa.us 7059 : 2719 : }
7060 : :
7061 : : /*
7062 : : * StartBufferIO: begin I/O on this buffer
7063 : : * (Assumptions)
7064 : : * My process is executing no IO on this buffer
7065 : : * The buffer is Pinned
7066 : : *
7067 : : * In some scenarios multiple backends could attempt the same I/O operation
7068 : : * concurrently. If someone else has already started I/O on this buffer then
7069 : : * we will wait for completion of the IO using WaitIO().
7070 : : *
7071 : : * Input operations are only attempted on buffers that are not BM_VALID,
7072 : : * and output operations only on buffers that are BM_VALID and BM_DIRTY,
7073 : : * so we can always tell if the work is already done.
7074 : : *
7075 : : * Returns true if we successfully marked the buffer as I/O busy,
7076 : : * false if someone else already did the work.
7077 : : *
7078 : : * If nowait is true, then we don't wait for an I/O to be finished by another
7079 : : * backend. In that case, false indicates either that the I/O was already
7080 : : * finished, or is still in progress. This is useful for callers that want to
7081 : : * find out if they can perform the I/O as part of a larger operation, without
7082 : : * waiting for the answer or distinguishing the reasons why not.
7083 : : */
7084 : : bool
711 tmunro@postgresql.or 7085 : 2629289 : StartBufferIO(BufferDesc *buf, bool forInput, bool nowait)
7086 : : {
7087 : : uint64 buf_state;
7088 : :
858 heikki.linnakangas@i 7089 : 2629289 : ResourceOwnerEnlarge(CurrentResourceOwner);
7090 : :
7091 : : for (;;)
7092 : : {
3626 andres@anarazel.de 7093 : 2632007 : buf_state = LockBufHdr(buf);
7094 : :
7095 [ + + ]: 2632007 : if (!(buf_state & BM_IO_IN_PROGRESS))
7681 tgl@sss.pgh.pa.us 7096 : 2629283 : break;
129 andres@anarazel.de 7097 :GNC 2724 : UnlockBufHdr(buf);
711 tmunro@postgresql.or 7098 [ + + ]:CBC 2724 : if (nowait)
7099 : 6 : return false;
7681 tgl@sss.pgh.pa.us 7100 : 2718 : WaitIO(buf);
7101 : : }
7102 : :
7103 : : /* Once we get here, there is definitely no I/O active on this buffer */
7104 : :
7105 : : /* Check if someone else already did the I/O */
3626 andres@anarazel.de 7106 [ + + + + ]: 2629283 : if (forInput ? (buf_state & BM_VALID) : !(buf_state & BM_DIRTY))
7107 : : {
129 andres@anarazel.de 7108 :GNC 3254 : UnlockBufHdr(buf);
7681 tgl@sss.pgh.pa.us 7109 :CBC 3254 : return false;
7110 : : }
7111 : :
129 andres@anarazel.de 7112 :GNC 2626029 : UnlockBufHdrExt(buf, buf_state,
7113 : : BM_IO_IN_PROGRESS, 0,
7114 : : 0);
7115 : :
1075 andres@anarazel.de 7116 :CBC 2626029 : ResourceOwnerRememberBufferIO(CurrentResourceOwner,
7117 : : BufferDescriptorGetBuffer(buf));
7118 : :
7681 tgl@sss.pgh.pa.us 7119 : 2626029 : return true;
7120 : : }
7121 : :
7122 : : /*
7123 : : * TerminateBufferIO: release a buffer we were doing I/O on
7124 : : * (Assumptions)
7125 : : * My process is executing IO for the buffer
7126 : : * BM_IO_IN_PROGRESS bit is set for the buffer
7127 : : * The buffer is Pinned
7128 : : *
7129 : : * If clear_dirty is true, we clear the buffer's BM_DIRTY flag. This is
7130 : : * appropriate when terminating a successful write.
7131 : : *
7132 : : * set_flag_bits gets ORed into the buffer's flags. It must include
7133 : : * BM_IO_ERROR in a failure case. For successful completion it could
7134 : : * be 0, or BM_VALID if we just finished reading in the page.
7135 : : *
7136 : : * If forget_owner is true, we release the buffer I/O from the current
7137 : : * resource owner. (forget_owner=false is used when the resource owner itself
7138 : : * is being released)
7139 : : */
7140 : : void
59 andres@anarazel.de 7141 :GNC 2458214 : TerminateBufferIO(BufferDesc *buf, bool clear_dirty, uint64 set_flag_bits,
7142 : : bool forget_owner, bool release_aio)
7143 : : {
7144 : : uint64 buf_state;
7145 : 2458214 : uint64 unset_flag_bits = 0;
129 7146 : 2458214 : int refcount_change = 0;
7147 : :
3626 andres@anarazel.de 7148 :CBC 2458214 : buf_state = LockBufHdr(buf);
7149 : :
7150 [ - + ]: 2458214 : Assert(buf_state & BM_IO_IN_PROGRESS);
129 andres@anarazel.de 7151 :GNC 2458214 : unset_flag_bits |= BM_IO_IN_PROGRESS;
7152 : :
7153 : : /* Clear earlier errors, if this IO failed, it'll be marked again */
7154 : 2458214 : unset_flag_bits |= BM_IO_ERROR;
7155 : :
4 7156 [ + + ]: 2458214 : if (clear_dirty)
129 7157 : 598960 : unset_flag_bits |= BM_DIRTY | BM_CHECKPOINT_NEEDED;
7158 : :
350 andres@anarazel.de 7159 [ + + ]:CBC 2458214 : if (release_aio)
7160 : : {
7161 : : /* release ownership by the AIO subsystem */
7162 [ - + ]: 1334551 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
129 andres@anarazel.de 7163 :GNC 1334551 : refcount_change = -1;
350 andres@anarazel.de 7164 :CBC 1334551 : pgaio_wref_clear(&buf->io_wref);
7165 : : }
7166 : :
129 andres@anarazel.de 7167 :GNC 2458214 : buf_state = UnlockBufHdrExt(buf, buf_state,
7168 : : set_flag_bits, unset_flag_bits,
7169 : : refcount_change);
7170 : :
858 heikki.linnakangas@i 7171 [ + + ]:CBC 2458214 : if (forget_owner)
7172 : 1123639 : ResourceOwnerForgetBufferIO(CurrentResourceOwner,
7173 : : BufferDescriptorGetBuffer(buf));
7174 : :
1830 tmunro@postgresql.or 7175 : 2458214 : ConditionVariableBroadcast(BufferDescriptorGetIOCV(buf));
7176 : :
7177 : : /*
7178 : : * Support LockBufferForCleanup()
7179 : : *
7180 : : * We may have just released the last pin other than the waiter's. In most
7181 : : * cases, this backend holds another pin on the buffer. But, if, for
7182 : : * example, this backend is completing an IO issued by another backend, it
7183 : : * may be time to wake the waiter.
7184 : : */
350 andres@anarazel.de 7185 [ + + - + ]: 2458214 : if (release_aio && (buf_state & BM_PIN_COUNT_WAITER))
350 andres@anarazel.de 7186 :UBC 0 : WakePinCountWaiter(buf);
9554 inoue@tpf.co.jp 7187 :CBC 2458214 : }
7188 : :
7189 : : /*
7190 : : * AbortBufferIO: Clean up active buffer I/O after an error.
7191 : : *
7192 : : * All LWLocks & content locks we might have held have been released, but we
7193 : : * haven't yet released buffer pins, so the buffer is still pinned.
7194 : : *
7195 : : * If I/O was in progress, we always set BM_IO_ERROR, even though it's
7196 : : * possible the error condition wasn't related to the I/O.
7197 : : *
7198 : : * Note: this does not remove the buffer I/O from the resource owner.
7199 : : * That's correct when we're releasing the whole resource owner, but
7200 : : * beware if you use this in other contexts.
7201 : : */
7202 : : static void
1067 pg@bowt.ie 7203 : 15 : AbortBufferIO(Buffer buffer)
7204 : : {
7205 : 15 : BufferDesc *buf_hdr = GetBufferDescriptor(buffer - 1);
7206 : : uint64 buf_state;
7207 : :
1075 andres@anarazel.de 7208 : 15 : buf_state = LockBufHdr(buf_hdr);
7209 [ - + ]: 15 : Assert(buf_state & (BM_IO_IN_PROGRESS | BM_TAG_VALID));
7210 : :
7211 [ + - ]: 15 : if (!(buf_state & BM_VALID))
7212 : : {
7213 [ - + ]: 15 : Assert(!(buf_state & BM_DIRTY));
129 andres@anarazel.de 7214 :GNC 15 : UnlockBufHdr(buf_hdr);
7215 : : }
7216 : : else
7217 : : {
1073 andres@anarazel.de 7218 [ # # ]:UBC 0 : Assert(buf_state & BM_DIRTY);
129 andres@anarazel.de 7219 :UNC 0 : UnlockBufHdr(buf_hdr);
7220 : :
7221 : : /* Issue notice if this is not the first failure... */
1075 andres@anarazel.de 7222 [ # # ]:UBC 0 : if (buf_state & BM_IO_ERROR)
7223 : : {
7224 : : /* Buffer is pinned, so we can read tag without spinlock */
7225 [ # # ]: 0 : ereport(WARNING,
7226 : : (errcode(ERRCODE_IO_ERROR),
7227 : : errmsg("could not write block %u of %s",
7228 : : buf_hdr->tag.blockNum,
7229 : : relpathperm(BufTagGetRelFileLocator(&buf_hdr->tag),
7230 : : BufTagGetForkNum(&buf_hdr->tag)).str),
7231 : : errdetail("Multiple failures --- write error might be permanent.")));
7232 : : }
7233 : : }
7234 : :
350 andres@anarazel.de 7235 :CBC 15 : TerminateBufferIO(buf_hdr, false, BM_IO_ERROR, false, false);
9554 inoue@tpf.co.jp 7236 : 15 : }
7237 : :
7238 : : /*
7239 : : * Error context callback for errors occurring during shared buffer writes.
7240 : : */
7241 : : static void
5693 rhaas@postgresql.org 7242 : 37 : shared_buffer_write_error_callback(void *arg)
7243 : : {
3772 7244 : 37 : BufferDesc *bufHdr = (BufferDesc *) arg;
7245 : :
7246 : : /* Buffer is pinned, so we can read the tag without locking the spinlock */
8345 tgl@sss.pgh.pa.us 7247 [ + - ]: 37 : if (bufHdr != NULL)
201 peter@eisentraut.org 7248 : 74 : errcontext("writing block %u of relation \"%s\"",
7249 : : bufHdr->tag.blockNum,
383 andres@anarazel.de 7250 : 37 : relpathperm(BufTagGetRelFileLocator(&bufHdr->tag),
7251 : : BufTagGetForkNum(&bufHdr->tag)).str);
5693 rhaas@postgresql.org 7252 : 37 : }
7253 : :
7254 : : /*
7255 : : * Error context callback for errors occurring during local buffer writes.
7256 : : */
7257 : : static void
5693 rhaas@postgresql.org 7258 :UBC 0 : local_buffer_write_error_callback(void *arg)
7259 : : {
3772 7260 : 0 : BufferDesc *bufHdr = (BufferDesc *) arg;
7261 : :
5693 7262 [ # # ]: 0 : if (bufHdr != NULL)
201 peter@eisentraut.org 7263 : 0 : errcontext("writing block %u of relation \"%s\"",
7264 : : bufHdr->tag.blockNum,
383 andres@anarazel.de 7265 : 0 : relpathbackend(BufTagGetRelFileLocator(&bufHdr->tag),
7266 : : MyProcNumber,
7267 : : BufTagGetForkNum(&bufHdr->tag)).str);
8345 tgl@sss.pgh.pa.us 7268 : 0 : }
7269 : :
7270 : : /*
7271 : : * RelFileLocator qsort/bsearch comparator; see RelFileLocatorEquals.
7272 : : */
7273 : : static int
1348 rhaas@postgresql.org 7274 :CBC 9956982 : rlocator_comparator(const void *p1, const void *p2)
7275 : : {
7276 : 9956982 : RelFileLocator n1 = *(const RelFileLocator *) p1;
7277 : 9956982 : RelFileLocator n2 = *(const RelFileLocator *) p2;
7278 : :
7279 [ + + ]: 9956982 : if (n1.relNumber < n2.relNumber)
4805 alvherre@alvh.no-ip. 7280 : 9923214 : return -1;
1348 rhaas@postgresql.org 7281 [ + + ]: 33768 : else if (n1.relNumber > n2.relNumber)
4805 alvherre@alvh.no-ip. 7282 : 32243 : return 1;
7283 : :
1348 rhaas@postgresql.org 7284 [ - + ]: 1525 : if (n1.dbOid < n2.dbOid)
4805 alvherre@alvh.no-ip. 7285 :UBC 0 : return -1;
1348 rhaas@postgresql.org 7286 [ - + ]:CBC 1525 : else if (n1.dbOid > n2.dbOid)
4805 alvherre@alvh.no-ip. 7287 :UBC 0 : return 1;
7288 : :
1348 rhaas@postgresql.org 7289 [ - + ]:CBC 1525 : if (n1.spcOid < n2.spcOid)
4805 alvherre@alvh.no-ip. 7290 :UBC 0 : return -1;
1348 rhaas@postgresql.org 7291 [ - + ]:CBC 1525 : else if (n1.spcOid > n2.spcOid)
4805 alvherre@alvh.no-ip. 7292 :UBC 0 : return 1;
7293 : : else
4805 alvherre@alvh.no-ip. 7294 :CBC 1525 : return 0;
7295 : : }
7296 : :
7297 : : /*
7298 : : * Lock buffer header - set BM_LOCKED in buffer state.
7299 : : */
7300 : : uint64
3626 andres@anarazel.de 7301 : 25193813 : LockBufHdr(BufferDesc *desc)
7302 : : {
7303 : : uint64 old_buf_state;
7304 : :
1075 7305 [ - + ]: 25193813 : Assert(!BufferIsLocal(BufferDescriptorGetBuffer(desc)));
7306 : :
7307 : : while (true)
7308 : : {
7309 : : /*
7310 : : * Always try once to acquire the lock directly, without setting up
7311 : : * the spin-delay infrastructure. The work necessary for that shows up
7312 : : * in profiles and is rarely necessary.
7313 : : */
59 andres@anarazel.de 7314 :GNC 25194300 : old_buf_state = pg_atomic_fetch_or_u64(&desc->state, BM_LOCKED);
86 7315 [ + + ]: 25194300 : if (likely(!(old_buf_state & BM_LOCKED)))
7316 : 25193813 : break; /* got lock */
7317 : :
7318 : : /* and then spin without atomic operations until lock is released */
7319 : : {
7320 : : SpinDelayStatus delayStatus;
7321 : :
7322 : 487 : init_local_spin_delay(&delayStatus);
7323 : :
7324 [ + + ]: 1254 : while (old_buf_state & BM_LOCKED)
7325 : : {
7326 : 767 : perform_spin_delay(&delayStatus);
59 7327 : 767 : old_buf_state = pg_atomic_read_u64(&desc->state);
7328 : : }
86 7329 : 487 : finish_spin_delay(&delayStatus);
7330 : : }
7331 : :
7332 : : /*
7333 : : * Retry. The lock might obviously already be re-acquired by the time
7334 : : * we're attempting to get it again.
7335 : : */
7336 : : }
7337 : :
3626 andres@anarazel.de 7338 :CBC 25193813 : return old_buf_state | BM_LOCKED;
7339 : : }
7340 : :
7341 : : /*
7342 : : * Wait until the BM_LOCKED flag isn't set anymore and return the buffer's
7343 : : * state at that point.
7344 : : *
7345 : : * Obviously the buffer could be locked by the time the value is returned, so
7346 : : * this is primarily useful in CAS style loops.
7347 : : */
7348 : : pg_noinline uint64
7349 : 281 : WaitBufHdrUnlocked(BufferDesc *buf)
7350 : : {
7351 : : SpinDelayStatus delayStatus;
7352 : : uint64 buf_state;
7353 : :
3622 7354 : 281 : init_local_spin_delay(&delayStatus);
7355 : :
59 andres@anarazel.de 7356 :GNC 281 : buf_state = pg_atomic_read_u64(&buf->state);
7357 : :
3626 andres@anarazel.de 7358 [ + + ]:CBC 4430 : while (buf_state & BM_LOCKED)
7359 : : {
7360 : 4149 : perform_spin_delay(&delayStatus);
59 andres@anarazel.de 7361 :GNC 4149 : buf_state = pg_atomic_read_u64(&buf->state);
7362 : : }
7363 : :
3626 andres@anarazel.de 7364 :CBC 281 : finish_spin_delay(&delayStatus);
7365 : :
7366 : 281 : return buf_state;
7367 : : }
7368 : :
7369 : : /*
7370 : : * BufferTag comparator.
7371 : : */
7372 : : static inline int
1829 tmunro@postgresql.or 7373 :UBC 0 : buffertag_comparator(const BufferTag *ba, const BufferTag *bb)
7374 : : {
7375 : : int ret;
7376 : : RelFileLocator rlocatora;
7377 : : RelFileLocator rlocatorb;
7378 : :
1299 rhaas@postgresql.org 7379 : 0 : rlocatora = BufTagGetRelFileLocator(ba);
7380 : 0 : rlocatorb = BufTagGetRelFileLocator(bb);
7381 : :
7382 : 0 : ret = rlocator_comparator(&rlocatora, &rlocatorb);
7383 : :
3677 andres@anarazel.de 7384 [ # # ]: 0 : if (ret != 0)
7385 : 0 : return ret;
7386 : :
1299 rhaas@postgresql.org 7387 [ # # ]: 0 : if (BufTagGetForkNum(ba) < BufTagGetForkNum(bb))
3677 andres@anarazel.de 7388 : 0 : return -1;
1299 rhaas@postgresql.org 7389 [ # # ]: 0 : if (BufTagGetForkNum(ba) > BufTagGetForkNum(bb))
3677 andres@anarazel.de 7390 : 0 : return 1;
7391 : :
7392 [ # # ]: 0 : if (ba->blockNum < bb->blockNum)
7393 : 0 : return -1;
7394 [ # # ]: 0 : if (ba->blockNum > bb->blockNum)
7395 : 0 : return 1;
7396 : :
7397 : 0 : return 0;
7398 : : }
7399 : :
7400 : : /*
7401 : : * Comparator determining the writeout order in a checkpoint.
7402 : : *
7403 : : * It is important that tablespaces are compared first, the logic balancing
7404 : : * writes between tablespaces relies on it.
7405 : : */
7406 : : static inline int
1829 tmunro@postgresql.or 7407 :CBC 3244384 : ckpt_buforder_comparator(const CkptSortItem *a, const CkptSortItem *b)
7408 : : {
7409 : : /* compare tablespace */
3677 andres@anarazel.de 7410 [ + + ]: 3244384 : if (a->tsId < b->tsId)
7411 : 7824 : return -1;
7412 [ + + ]: 3236560 : else if (a->tsId > b->tsId)
7413 : 24341 : return 1;
7414 : : /* compare relation */
1348 rhaas@postgresql.org 7415 [ + + ]: 3212219 : if (a->relNumber < b->relNumber)
3677 andres@anarazel.de 7416 : 880571 : return -1;
1348 rhaas@postgresql.org 7417 [ + + ]: 2331648 : else if (a->relNumber > b->relNumber)
3677 andres@anarazel.de 7418 : 879716 : return 1;
7419 : : /* compare fork */
7420 [ + + ]: 1451932 : else if (a->forkNum < b->forkNum)
7421 : 61283 : return -1;
7422 [ + + ]: 1390649 : else if (a->forkNum > b->forkNum)
7423 : 64613 : return 1;
7424 : : /* compare block number */
7425 [ + + ]: 1326036 : else if (a->blockNum < b->blockNum)
7426 : 649107 : return -1;
2986 tgl@sss.pgh.pa.us 7427 [ + + ]: 676929 : else if (a->blockNum > b->blockNum)
3677 andres@anarazel.de 7428 : 633321 : return 1;
7429 : : /* equal page IDs are unlikely, but not impossible */
2986 tgl@sss.pgh.pa.us 7430 : 43608 : return 0;
7431 : : }
7432 : :
7433 : : /*
7434 : : * Comparator for a Min-Heap over the per-tablespace checkpoint completion
7435 : : * progress.
7436 : : */
7437 : : static int
3677 andres@anarazel.de 7438 : 263913 : ts_ckpt_progress_comparator(Datum a, Datum b, void *arg)
7439 : : {
219 peter@eisentraut.org 7440 :GNC 263913 : CkptTsStatus *sa = (CkptTsStatus *) DatumGetPointer(a);
7441 : 263913 : CkptTsStatus *sb = (CkptTsStatus *) DatumGetPointer(b);
7442 : :
7443 : : /* we want a min-heap, so return 1 for the a < b */
3677 andres@anarazel.de 7444 [ + + ]:CBC 263913 : if (sa->progress < sb->progress)
7445 : 238142 : return 1;
7446 [ + + ]: 25771 : else if (sa->progress == sb->progress)
7447 : 1269 : return 0;
7448 : : else
7449 : 24502 : return -1;
7450 : : }
7451 : :
7452 : : /*
7453 : : * Initialize a writeback context, discarding potential previous state.
7454 : : *
7455 : : * *max_pending is a pointer instead of an immediate value, so the coalesce
7456 : : * limits can easily changed by the GUC mechanism, and so calling code does
7457 : : * not have to check the current configuration. A value of 0 means that no
7458 : : * writeback control will be performed.
7459 : : */
7460 : : void
7461 : 2832 : WritebackContextInit(WritebackContext *context, int *max_pending)
7462 : : {
7463 [ - + ]: 2832 : Assert(*max_pending <= WRITEBACK_MAX_PENDING_FLUSHES);
7464 : :
7465 : 2832 : context->max_pending = max_pending;
7466 : 2832 : context->nr_pending = 0;
7467 : 2832 : }
7468 : :
7469 : : /*
7470 : : * Add buffer to list of pending writeback requests.
7471 : : */
7472 : : void
1033 7473 : 595144 : ScheduleBufferTagForWriteback(WritebackContext *wb_context, IOContext io_context,
7474 : : BufferTag *tag)
7475 : : {
7476 : : PendingWriteback *pending;
7477 : :
7478 : : /*
7479 : : * As pg_flush_data() doesn't do anything with fsync disabled, there's no
7480 : : * point in tracking in that case.
7481 : : */
523 7482 [ + + ]: 595144 : if (io_direct_flags & IO_DIRECT_DATA ||
7483 [ + + ]: 594620 : !enableFsync)
1072 tmunro@postgresql.or 7484 : 595141 : return;
7485 : :
7486 : : /*
7487 : : * Add buffer to the pending writeback array, unless writeback control is
7488 : : * disabled.
7489 : : */
1033 andres@anarazel.de 7490 [ - + ]: 3 : if (*wb_context->max_pending > 0)
7491 : : {
1033 andres@anarazel.de 7492 [ # # ]:UBC 0 : Assert(*wb_context->max_pending <= WRITEBACK_MAX_PENDING_FLUSHES);
7493 : :
7494 : 0 : pending = &wb_context->pending_writebacks[wb_context->nr_pending++];
7495 : :
3677 7496 : 0 : pending->tag = *tag;
7497 : : }
7498 : :
7499 : : /*
7500 : : * Perform pending flushes if the writeback limit is exceeded. This
7501 : : * includes the case where previously an item has been added, but control
7502 : : * is now disabled.
7503 : : */
1033 andres@anarazel.de 7504 [ + - ]:CBC 3 : if (wb_context->nr_pending >= *wb_context->max_pending)
7505 : 3 : IssuePendingWritebacks(wb_context, io_context);
7506 : : }
7507 : :
7508 : : #define ST_SORT sort_pending_writebacks
7509 : : #define ST_ELEMENT_TYPE PendingWriteback
7510 : : #define ST_COMPARE(a, b) buffertag_comparator(&a->tag, &b->tag)
7511 : : #define ST_SCOPE static
7512 : : #define ST_DEFINE
7513 : : #include "lib/sort_template.h"
7514 : :
7515 : : /*
7516 : : * Issue all pending writeback requests, previously scheduled with
7517 : : * ScheduleBufferTagForWriteback, to the OS.
7518 : : *
7519 : : * Because this is only used to improve the OSs IO scheduling we try to never
7520 : : * error out - it's just a hint.
7521 : : */
7522 : : void
7523 : 1106 : IssuePendingWritebacks(WritebackContext *wb_context, IOContext io_context)
7524 : : {
7525 : : instr_time io_start;
7526 : : int i;
7527 : :
7528 [ + - ]: 1106 : if (wb_context->nr_pending == 0)
3677 7529 : 1106 : return;
7530 : :
7531 : : /*
7532 : : * Executing the writes in-order can make them a lot faster, and allows to
7533 : : * merge writeback requests to consecutive blocks into larger writebacks.
7534 : : */
1033 andres@anarazel.de 7535 :UBC 0 : sort_pending_writebacks(wb_context->pending_writebacks,
7536 : 0 : wb_context->nr_pending);
7537 : :
382 michael@paquier.xyz 7538 : 0 : io_start = pgstat_prepare_io_time(track_io_timing);
7539 : :
7540 : : /*
7541 : : * Coalesce neighbouring writes, but nothing else. For that we iterate
7542 : : * through the, now sorted, array of pending flushes, and look forward to
7543 : : * find all neighbouring (or identical) writes.
7544 : : */
1033 andres@anarazel.de 7545 [ # # ]: 0 : for (i = 0; i < wb_context->nr_pending; i++)
7546 : : {
7547 : : PendingWriteback *cur;
7548 : : PendingWriteback *next;
7549 : : SMgrRelation reln;
7550 : : int ahead;
7551 : : BufferTag tag;
7552 : : RelFileLocator currlocator;
3677 7553 : 0 : Size nblocks = 1;
7554 : :
1033 7555 : 0 : cur = &wb_context->pending_writebacks[i];
3677 7556 : 0 : tag = cur->tag;
1299 rhaas@postgresql.org 7557 : 0 : currlocator = BufTagGetRelFileLocator(&tag);
7558 : :
7559 : : /*
7560 : : * Peek ahead, into following writeback requests, to see if they can
7561 : : * be combined with the current one.
7562 : : */
1033 andres@anarazel.de 7563 [ # # ]: 0 : for (ahead = 0; i + ahead + 1 < wb_context->nr_pending; ahead++)
7564 : : {
7565 : :
7566 : 0 : next = &wb_context->pending_writebacks[i + ahead + 1];
7567 : :
7568 : : /* different file, stop */
1299 rhaas@postgresql.org 7569 [ # # # # : 0 : if (!RelFileLocatorEquals(currlocator,
# # ]
7570 [ # # ]: 0 : BufTagGetRelFileLocator(&next->tag)) ||
7571 : 0 : BufTagGetForkNum(&cur->tag) != BufTagGetForkNum(&next->tag))
7572 : : break;
7573 : :
7574 : : /* ok, block queued twice, skip */
3677 andres@anarazel.de 7575 [ # # ]: 0 : if (cur->tag.blockNum == next->tag.blockNum)
7576 : 0 : continue;
7577 : :
7578 : : /* only merge consecutive writes */
7579 [ # # ]: 0 : if (cur->tag.blockNum + 1 != next->tag.blockNum)
7580 : 0 : break;
7581 : :
7582 : 0 : nblocks++;
7583 : 0 : cur = next;
7584 : : }
7585 : :
7586 : 0 : i += ahead;
7587 : :
7588 : : /* and finally tell the kernel to write the data to storage */
742 heikki.linnakangas@i 7589 : 0 : reln = smgropen(currlocator, INVALID_PROC_NUMBER);
1299 rhaas@postgresql.org 7590 : 0 : smgrwriteback(reln, BufTagGetForkNum(&tag), tag.blockNum, nblocks);
7591 : : }
7592 : :
7593 : : /*
7594 : : * Assume that writeback requests are only issued for buffers containing
7595 : : * blocks of permanent relations.
7596 : : */
1033 andres@anarazel.de 7597 : 0 : pgstat_count_io_op_time(IOOBJECT_RELATION, io_context,
425 michael@paquier.xyz 7598 : 0 : IOOP_WRITEBACK, io_start, wb_context->nr_pending, 0);
7599 : :
1033 andres@anarazel.de 7600 : 0 : wb_context->nr_pending = 0;
7601 : : }
7602 : :
7603 : : /* ResourceOwner callbacks */
7604 : :
7605 : : static void
858 heikki.linnakangas@i 7606 :CBC 15 : ResOwnerReleaseBufferIO(Datum res)
7607 : : {
7608 : 15 : Buffer buffer = DatumGetInt32(res);
7609 : :
7610 : 15 : AbortBufferIO(buffer);
7611 : 15 : }
7612 : :
7613 : : static char *
858 heikki.linnakangas@i 7614 :UBC 0 : ResOwnerPrintBufferIO(Datum res)
7615 : : {
7616 : 0 : Buffer buffer = DatumGetInt32(res);
7617 : :
7618 : 0 : return psprintf("lost track of buffer IO on buffer %d", buffer);
7619 : : }
7620 : :
7621 : : /*
7622 : : * Release buffer as part of resource owner cleanup. This will only be called
7623 : : * if the buffer is pinned. If this backend held the content lock at the time
7624 : : * of the error we also need to release that (note that it is not possible to
7625 : : * hold a content lock without a pin).
7626 : : */
7627 : : static void
59 andres@anarazel.de 7628 :GNC 7888 : ResOwnerReleaseBuffer(Datum res)
7629 : : {
858 heikki.linnakangas@i 7630 :CBC 7888 : Buffer buffer = DatumGetInt32(res);
7631 : :
7632 : : /* Like ReleaseBuffer, but don't call ResourceOwnerForgetBuffer */
7633 [ - + ]: 7888 : if (!BufferIsValid(buffer))
858 heikki.linnakangas@i 7634 [ # # ]:UBC 0 : elog(ERROR, "bad buffer ID: %d", buffer);
7635 : :
858 heikki.linnakangas@i 7636 [ + + ]:CBC 7888 : if (BufferIsLocal(buffer))
7637 : 3020 : UnpinLocalBufferNoOwner(buffer);
7638 : : else
7639 : : {
7640 : : PrivateRefCountEntry *ref;
7641 : :
59 andres@anarazel.de 7642 :GNC 4868 : ref = GetPrivateRefCountEntry(buffer, false);
7643 : :
7644 : : /* not having a private refcount would imply resowner corruption */
7645 [ - + ]: 4868 : Assert(ref != NULL);
7646 : :
7647 : : /*
7648 : : * If the buffer was locked at the time of the resowner release,
7649 : : * release the lock now. This should only happen after errors.
7650 : : */
7651 [ + + ]: 4868 : if (ref->data.lockmode != BUFFER_LOCK_UNLOCK)
7652 : : {
7653 : 112 : BufferDesc *buf = GetBufferDescriptor(buffer - 1);
7654 : :
7655 : 112 : HOLD_INTERRUPTS(); /* match the upcoming RESUME_INTERRUPTS */
7656 : 112 : BufferLockUnlock(buffer, buf);
7657 : : }
7658 : :
858 heikki.linnakangas@i 7659 :CBC 4868 : UnpinBufferNoOwner(GetBufferDescriptor(buffer - 1));
7660 : : }
7661 : 7888 : }
7662 : :
7663 : : static char *
59 andres@anarazel.de 7664 :UNC 0 : ResOwnerPrintBuffer(Datum res)
7665 : : {
858 heikki.linnakangas@i 7666 :UBC 0 : return DebugPrintBufferRefcount(DatumGetInt32(res));
7667 : : }
7668 : :
7669 : : /*
7670 : : * Helper function to evict unpinned buffer whose buffer header lock is
7671 : : * already acquired.
7672 : : */
7673 : : static bool
341 andres@anarazel.de 7674 :CBC 2236 : EvictUnpinnedBufferInternal(BufferDesc *desc, bool *buffer_flushed)
7675 : : {
7676 : : uint64 buf_state;
7677 : : bool result;
7678 : :
7679 : 2236 : *buffer_flushed = false;
7680 : :
59 andres@anarazel.de 7681 :GNC 2236 : buf_state = pg_atomic_read_u64(&(desc->state));
341 andres@anarazel.de 7682 [ - + ]:CBC 2236 : Assert(buf_state & BM_LOCKED);
7683 : :
707 tmunro@postgresql.or 7684 [ - + ]: 2236 : if ((buf_state & BM_VALID) == 0)
7685 : : {
129 andres@anarazel.de 7686 :UNC 0 : UnlockBufHdr(desc);
707 tmunro@postgresql.or 7687 :UBC 0 : return false;
7688 : : }
7689 : :
7690 : : /* Check that it's not pinned already. */
707 tmunro@postgresql.or 7691 [ - + ]:CBC 2236 : if (BUF_STATE_GET_REFCOUNT(buf_state) > 0)
7692 : : {
129 andres@anarazel.de 7693 :UNC 0 : UnlockBufHdr(desc);
707 tmunro@postgresql.or 7694 :UBC 0 : return false;
7695 : : }
7696 : :
707 tmunro@postgresql.or 7697 :CBC 2236 : PinBuffer_Locked(desc); /* releases spinlock */
7698 : :
7699 : : /* If it was dirty, try to clean it once. */
7700 [ + + ]: 2236 : if (buf_state & BM_DIRTY)
7701 : : {
158 andres@anarazel.de 7702 :GNC 993 : FlushUnlockedBuffer(desc, NULL, IOOBJECT_RELATION, IOCONTEXT_NORMAL);
341 andres@anarazel.de 7703 :CBC 993 : *buffer_flushed = true;
7704 : : }
7705 : :
7706 : : /* This will return false if it becomes dirty or someone else pins it. */
707 tmunro@postgresql.or 7707 : 2236 : result = InvalidateVictimBuffer(desc);
7708 : :
7709 : 2236 : UnpinBuffer(desc);
7710 : :
7711 : 2236 : return result;
7712 : : }
7713 : :
7714 : : /*
7715 : : * Try to evict the current block in a shared buffer.
7716 : : *
7717 : : * This function is intended for testing/development use only!
7718 : : *
7719 : : * To succeed, the buffer must not be pinned on entry, so if the caller had a
7720 : : * particular block in mind, it might already have been replaced by some other
7721 : : * block by the time this function runs. It's also unpinned on return, so the
7722 : : * buffer might be occupied again by the time control is returned, potentially
7723 : : * even by the same block. This inherent raciness without other interlocking
7724 : : * makes the function unsuitable for non-testing usage.
7725 : : *
7726 : : * *buffer_flushed is set to true if the buffer was dirty and has been
7727 : : * flushed, false otherwise. However, *buffer_flushed=true does not
7728 : : * necessarily mean that we flushed the buffer, it could have been flushed by
7729 : : * someone else.
7730 : : *
7731 : : * Returns true if the buffer was valid and it has now been made invalid.
7732 : : * Returns false if it wasn't valid, if it couldn't be evicted due to a pin,
7733 : : * or if the buffer becomes dirty again while we're trying to write it out.
7734 : : */
7735 : : bool
341 andres@anarazel.de 7736 : 209 : EvictUnpinnedBuffer(Buffer buf, bool *buffer_flushed)
7737 : : {
7738 : : BufferDesc *desc;
7739 : :
7740 [ + - - + ]: 209 : Assert(BufferIsValid(buf) && !BufferIsLocal(buf));
7741 : :
7742 : : /* Make sure we can pin the buffer. */
7743 : 209 : ResourceOwnerEnlarge(CurrentResourceOwner);
7744 : 209 : ReservePrivateRefCountEntry();
7745 : :
7746 : 209 : desc = GetBufferDescriptor(buf - 1);
7747 : 209 : LockBufHdr(desc);
7748 : :
7749 : 209 : return EvictUnpinnedBufferInternal(desc, buffer_flushed);
7750 : : }
7751 : :
7752 : : /*
7753 : : * Try to evict all the shared buffers.
7754 : : *
7755 : : * This function is intended for testing/development use only! See
7756 : : * EvictUnpinnedBuffer().
7757 : : *
7758 : : * The buffers_* parameters are mandatory and indicate the total count of
7759 : : * buffers that:
7760 : : * - buffers_evicted - were evicted
7761 : : * - buffers_flushed - were flushed
7762 : : * - buffers_skipped - could not be evicted
7763 : : */
7764 : : void
7765 : 1 : EvictAllUnpinnedBuffers(int32 *buffers_evicted, int32 *buffers_flushed,
7766 : : int32 *buffers_skipped)
7767 : : {
7768 : 1 : *buffers_evicted = 0;
7769 : 1 : *buffers_skipped = 0;
7770 : 1 : *buffers_flushed = 0;
7771 : :
7772 [ + + ]: 16385 : for (int buf = 1; buf <= NBuffers; buf++)
7773 : : {
7774 : 16384 : BufferDesc *desc = GetBufferDescriptor(buf - 1);
7775 : : uint64 buf_state;
7776 : : bool buffer_flushed;
7777 : :
131 msawada@postgresql.o 7778 [ - + ]: 16384 : CHECK_FOR_INTERRUPTS();
7779 : :
59 andres@anarazel.de 7780 :GNC 16384 : buf_state = pg_atomic_read_u64(&desc->state);
341 andres@anarazel.de 7781 [ + + ]:CBC 16384 : if (!(buf_state & BM_VALID))
7782 : 14357 : continue;
7783 : :
7784 : 2027 : ResourceOwnerEnlarge(CurrentResourceOwner);
7785 : 2027 : ReservePrivateRefCountEntry();
7786 : :
7787 : 2027 : LockBufHdr(desc);
7788 : :
7789 [ + - ]: 2027 : if (EvictUnpinnedBufferInternal(desc, &buffer_flushed))
7790 : 2027 : (*buffers_evicted)++;
7791 : : else
341 andres@anarazel.de 7792 :UBC 0 : (*buffers_skipped)++;
7793 : :
341 andres@anarazel.de 7794 [ + + ]:CBC 2027 : if (buffer_flushed)
7795 : 965 : (*buffers_flushed)++;
7796 : : }
7797 : 1 : }
7798 : :
7799 : : /*
7800 : : * Try to evict all the shared buffers containing provided relation's pages.
7801 : : *
7802 : : * This function is intended for testing/development use only! See
7803 : : * EvictUnpinnedBuffer().
7804 : : *
7805 : : * The caller must hold at least AccessShareLock on the relation to prevent
7806 : : * the relation from being dropped.
7807 : : *
7808 : : * The buffers_* parameters are mandatory and indicate the total count of
7809 : : * buffers that:
7810 : : * - buffers_evicted - were evicted
7811 : : * - buffers_flushed - were flushed
7812 : : * - buffers_skipped - could not be evicted
7813 : : */
7814 : : void
7815 : 1 : EvictRelUnpinnedBuffers(Relation rel, int32 *buffers_evicted,
7816 : : int32 *buffers_flushed, int32 *buffers_skipped)
7817 : : {
7818 [ - + ]: 1 : Assert(!RelationUsesLocalBuffers(rel));
7819 : :
7820 : 1 : *buffers_skipped = 0;
7821 : 1 : *buffers_evicted = 0;
7822 : 1 : *buffers_flushed = 0;
7823 : :
7824 [ + + ]: 16385 : for (int buf = 1; buf <= NBuffers; buf++)
7825 : : {
7826 : 16384 : BufferDesc *desc = GetBufferDescriptor(buf - 1);
59 andres@anarazel.de 7827 :GNC 16384 : uint64 buf_state = pg_atomic_read_u64(&(desc->state));
7828 : : bool buffer_flushed;
7829 : :
131 msawada@postgresql.o 7830 [ - + ]:CBC 16384 : CHECK_FOR_INTERRUPTS();
7831 : :
7832 : : /* An unlocked precheck should be safe and saves some cycles. */
341 andres@anarazel.de 7833 [ + + ]: 16384 : if ((buf_state & BM_VALID) == 0 ||
7834 [ + - ]: 27 : !BufTagMatchesRelFileLocator(&desc->tag, &rel->rd_locator))
7835 : 16384 : continue;
7836 : :
7837 : : /* Make sure we can pin the buffer. */
341 andres@anarazel.de 7838 :UBC 0 : ResourceOwnerEnlarge(CurrentResourceOwner);
7839 : 0 : ReservePrivateRefCountEntry();
7840 : :
7841 : 0 : buf_state = LockBufHdr(desc);
7842 : :
7843 : : /* recheck, could have changed without the lock */
7844 [ # # ]: 0 : if ((buf_state & BM_VALID) == 0 ||
7845 [ # # ]: 0 : !BufTagMatchesRelFileLocator(&desc->tag, &rel->rd_locator))
7846 : : {
129 andres@anarazel.de 7847 :UNC 0 : UnlockBufHdr(desc);
341 andres@anarazel.de 7848 :UBC 0 : continue;
7849 : : }
7850 : :
7851 [ # # ]: 0 : if (EvictUnpinnedBufferInternal(desc, &buffer_flushed))
7852 : 0 : (*buffers_evicted)++;
7853 : : else
7854 : 0 : (*buffers_skipped)++;
7855 : :
7856 [ # # ]: 0 : if (buffer_flushed)
7857 : 0 : (*buffers_flushed)++;
7858 : : }
341 andres@anarazel.de 7859 :CBC 1 : }
7860 : :
7861 : : /*
7862 : : * Helper function to mark unpinned buffer dirty whose buffer header lock is
7863 : : * already acquired.
7864 : : */
7865 : : static bool
107 michael@paquier.xyz 7866 :GNC 36 : MarkDirtyUnpinnedBufferInternal(Buffer buf, BufferDesc *desc,
7867 : : bool *buffer_already_dirty)
7868 : : {
7869 : : uint64 buf_state;
7870 : 36 : bool result = false;
7871 : :
7872 : 36 : *buffer_already_dirty = false;
7873 : :
59 andres@anarazel.de 7874 : 36 : buf_state = pg_atomic_read_u64(&(desc->state));
107 michael@paquier.xyz 7875 [ - + ]: 36 : Assert(buf_state & BM_LOCKED);
7876 : :
7877 [ + + ]: 36 : if ((buf_state & BM_VALID) == 0)
7878 : : {
7879 : 1 : UnlockBufHdr(desc);
7880 : 1 : return false;
7881 : : }
7882 : :
7883 : : /* Check that it's not pinned already. */
7884 [ - + ]: 35 : if (BUF_STATE_GET_REFCOUNT(buf_state) > 0)
7885 : : {
107 michael@paquier.xyz 7886 :UNC 0 : UnlockBufHdr(desc);
7887 : 0 : return false;
7888 : : }
7889 : :
7890 : : /* Pin the buffer and then release the buffer spinlock */
107 michael@paquier.xyz 7891 :GNC 35 : PinBuffer_Locked(desc);
7892 : :
7893 : : /* If it was not already dirty, mark it as dirty. */
7894 [ + + ]: 35 : if (!(buf_state & BM_DIRTY))
7895 : : {
59 andres@anarazel.de 7896 : 16 : BufferLockAcquire(buf, desc, BUFFER_LOCK_EXCLUSIVE);
107 michael@paquier.xyz 7897 : 16 : MarkBufferDirty(buf);
7898 : 16 : result = true;
59 andres@anarazel.de 7899 : 16 : BufferLockUnlock(buf, desc);
7900 : : }
7901 : : else
107 michael@paquier.xyz 7902 : 19 : *buffer_already_dirty = true;
7903 : :
7904 : 35 : UnpinBuffer(desc);
7905 : :
7906 : 35 : return result;
7907 : : }
7908 : :
7909 : : /*
7910 : : * Try to mark the provided shared buffer as dirty.
7911 : : *
7912 : : * This function is intended for testing/development use only!
7913 : : *
7914 : : * Same as EvictUnpinnedBuffer() but with MarkBufferDirty() call inside.
7915 : : *
7916 : : * The buffer_already_dirty parameter is mandatory and indicate if the buffer
7917 : : * could not be dirtied because it is already dirty.
7918 : : *
7919 : : * Returns true if the buffer has successfully been marked as dirty.
7920 : : */
7921 : : bool
7922 : 1 : MarkDirtyUnpinnedBuffer(Buffer buf, bool *buffer_already_dirty)
7923 : : {
7924 : : BufferDesc *desc;
7925 : 1 : bool buffer_dirtied = false;
7926 : :
7927 [ - + ]: 1 : Assert(!BufferIsLocal(buf));
7928 : :
7929 : : /* Make sure we can pin the buffer. */
7930 : 1 : ResourceOwnerEnlarge(CurrentResourceOwner);
7931 : 1 : ReservePrivateRefCountEntry();
7932 : :
7933 : 1 : desc = GetBufferDescriptor(buf - 1);
7934 : 1 : LockBufHdr(desc);
7935 : :
7936 : 1 : buffer_dirtied = MarkDirtyUnpinnedBufferInternal(buf, desc, buffer_already_dirty);
7937 : : /* Both can not be true at the same time */
7938 [ - + - - ]: 1 : Assert(!(buffer_dirtied && *buffer_already_dirty));
7939 : :
7940 : 1 : return buffer_dirtied;
7941 : : }
7942 : :
7943 : : /*
7944 : : * Try to mark all the shared buffers containing provided relation's pages as
7945 : : * dirty.
7946 : : *
7947 : : * This function is intended for testing/development use only! See
7948 : : * MarkDirtyUnpinnedBuffer().
7949 : : *
7950 : : * The buffers_* parameters are mandatory and indicate the total count of
7951 : : * buffers that:
7952 : : * - buffers_dirtied - were dirtied
7953 : : * - buffers_already_dirty - were already dirty
7954 : : * - buffers_skipped - could not be dirtied because of a reason different
7955 : : * than a buffer being already dirty.
7956 : : */
7957 : : void
7958 : 1 : MarkDirtyRelUnpinnedBuffers(Relation rel,
7959 : : int32 *buffers_dirtied,
7960 : : int32 *buffers_already_dirty,
7961 : : int32 *buffers_skipped)
7962 : : {
7963 [ - + ]: 1 : Assert(!RelationUsesLocalBuffers(rel));
7964 : :
7965 : 1 : *buffers_dirtied = 0;
7966 : 1 : *buffers_already_dirty = 0;
7967 : 1 : *buffers_skipped = 0;
7968 : :
7969 [ + + ]: 16385 : for (int buf = 1; buf <= NBuffers; buf++)
7970 : : {
7971 : 16384 : BufferDesc *desc = GetBufferDescriptor(buf - 1);
59 andres@anarazel.de 7972 : 16384 : uint64 buf_state = pg_atomic_read_u64(&(desc->state));
7973 : : bool buffer_already_dirty;
7974 : :
107 michael@paquier.xyz 7975 [ - + ]: 16384 : CHECK_FOR_INTERRUPTS();
7976 : :
7977 : : /* An unlocked precheck should be safe and saves some cycles. */
7978 [ + + ]: 16384 : if ((buf_state & BM_VALID) == 0 ||
7979 [ + - ]: 27 : !BufTagMatchesRelFileLocator(&desc->tag, &rel->rd_locator))
7980 : 16384 : continue;
7981 : :
7982 : : /* Make sure we can pin the buffer. */
107 michael@paquier.xyz 7983 :UNC 0 : ResourceOwnerEnlarge(CurrentResourceOwner);
7984 : 0 : ReservePrivateRefCountEntry();
7985 : :
7986 : 0 : buf_state = LockBufHdr(desc);
7987 : :
7988 : : /* recheck, could have changed without the lock */
7989 [ # # ]: 0 : if ((buf_state & BM_VALID) == 0 ||
7990 [ # # ]: 0 : !BufTagMatchesRelFileLocator(&desc->tag, &rel->rd_locator))
7991 : : {
7992 : 0 : UnlockBufHdr(desc);
7993 : 0 : continue;
7994 : : }
7995 : :
7996 [ # # ]: 0 : if (MarkDirtyUnpinnedBufferInternal(buf, desc, &buffer_already_dirty))
7997 : 0 : (*buffers_dirtied)++;
7998 [ # # ]: 0 : else if (buffer_already_dirty)
7999 : 0 : (*buffers_already_dirty)++;
8000 : : else
8001 : 0 : (*buffers_skipped)++;
8002 : : }
107 michael@paquier.xyz 8003 :GNC 1 : }
8004 : :
8005 : : /*
8006 : : * Try to mark all the shared buffers as dirty.
8007 : : *
8008 : : * This function is intended for testing/development use only! See
8009 : : * MarkDirtyUnpinnedBuffer().
8010 : : *
8011 : : * See MarkDirtyRelUnpinnedBuffers() above for details about the buffers_*
8012 : : * parameters.
8013 : : */
8014 : : void
8015 : 1 : MarkDirtyAllUnpinnedBuffers(int32 *buffers_dirtied,
8016 : : int32 *buffers_already_dirty,
8017 : : int32 *buffers_skipped)
8018 : : {
8019 : 1 : *buffers_dirtied = 0;
8020 : 1 : *buffers_already_dirty = 0;
8021 : 1 : *buffers_skipped = 0;
8022 : :
8023 [ + + ]: 16385 : for (int buf = 1; buf <= NBuffers; buf++)
8024 : : {
8025 : 16384 : BufferDesc *desc = GetBufferDescriptor(buf - 1);
8026 : : uint64 buf_state;
8027 : : bool buffer_already_dirty;
8028 : :
8029 [ - + ]: 16384 : CHECK_FOR_INTERRUPTS();
8030 : :
59 andres@anarazel.de 8031 : 16384 : buf_state = pg_atomic_read_u64(&desc->state);
107 michael@paquier.xyz 8032 [ + + ]: 16384 : if (!(buf_state & BM_VALID))
8033 : 16349 : continue;
8034 : :
8035 : 35 : ResourceOwnerEnlarge(CurrentResourceOwner);
8036 : 35 : ReservePrivateRefCountEntry();
8037 : :
8038 : 35 : LockBufHdr(desc);
8039 : :
8040 [ + + ]: 35 : if (MarkDirtyUnpinnedBufferInternal(buf, desc, &buffer_already_dirty))
8041 : 16 : (*buffers_dirtied)++;
8042 [ + - ]: 19 : else if (buffer_already_dirty)
8043 : 19 : (*buffers_already_dirty)++;
8044 : : else
107 michael@paquier.xyz 8045 :UNC 0 : (*buffers_skipped)++;
8046 : : }
107 michael@paquier.xyz 8047 :GNC 1 : }
8048 : :
8049 : : /*
8050 : : * Generic implementation of the AIO handle staging callback for readv/writev
8051 : : * on local/shared buffers.
8052 : : *
8053 : : * Each readv/writev can target multiple buffers. The buffers have already
8054 : : * been registered with the IO handle.
8055 : : *
8056 : : * To make the IO ready for execution ("staging"), we need to ensure that the
8057 : : * targeted buffers are in an appropriate state while the IO is ongoing. For
8058 : : * that the AIO subsystem needs to have its own buffer pin, otherwise an error
8059 : : * in this backend could lead to this backend's buffer pin being released as
8060 : : * part of error handling, which in turn could lead to the buffer being
8061 : : * replaced while IO is ongoing.
8062 : : */
8063 : : static pg_attribute_always_inline void
350 andres@anarazel.de 8064 :CBC 1336659 : buffer_stage_common(PgAioHandle *ioh, bool is_write, bool is_temp)
8065 : : {
8066 : : uint64 *io_data;
8067 : : uint8 handle_data_len;
8068 : : PgAioWaitRef io_ref;
8069 : 1336659 : BufferTag first PG_USED_FOR_ASSERTS_ONLY = {0};
8070 : :
8071 : 1336659 : io_data = pgaio_io_get_handle_data(ioh, &handle_data_len);
8072 : :
8073 : 1336659 : pgaio_io_get_wref(ioh, &io_ref);
8074 : :
8075 : : /* iterate over all buffers affected by the vectored readv/writev */
8076 [ + + ]: 2847478 : for (int i = 0; i < handle_data_len; i++)
8077 : : {
8078 : 1510819 : Buffer buffer = (Buffer) io_data[i];
8079 : 1510819 : BufferDesc *buf_hdr = is_temp ?
8080 : 8453 : GetLocalBufferDescriptor(-buffer - 1)
8081 [ + + ]: 1510819 : : GetBufferDescriptor(buffer - 1);
8082 : : uint64 buf_state;
8083 : :
8084 : : /*
8085 : : * Check that all the buffers are actually ones that could conceivably
8086 : : * be done in one IO, i.e. are sequential. This is the last
8087 : : * buffer-aware code before IO is actually executed and confusion
8088 : : * about which buffers are targeted by IO can be hard to debug, making
8089 : : * it worth doing extra-paranoid checks.
8090 : : */
8091 [ + + ]: 1510819 : if (i == 0)
8092 : 1336659 : first = buf_hdr->tag;
8093 : : else
8094 : : {
8095 [ - + ]: 174160 : Assert(buf_hdr->tag.relNumber == first.relNumber);
8096 [ - + ]: 174160 : Assert(buf_hdr->tag.blockNum == first.blockNum + i);
8097 : : }
8098 : :
8099 [ + + ]: 1510819 : if (is_temp)
59 andres@anarazel.de 8100 :GNC 8453 : buf_state = pg_atomic_read_u64(&buf_hdr->state);
8101 : : else
350 andres@anarazel.de 8102 :CBC 1502366 : buf_state = LockBufHdr(buf_hdr);
8103 : :
8104 : : /* verify the buffer is in the expected state */
8105 [ - + ]: 1510819 : Assert(buf_state & BM_TAG_VALID);
8106 [ - + ]: 1510819 : if (is_write)
8107 : : {
350 andres@anarazel.de 8108 [ # # ]:UBC 0 : Assert(buf_state & BM_VALID);
8109 [ # # ]: 0 : Assert(buf_state & BM_DIRTY);
8110 : : }
8111 : : else
8112 : : {
350 andres@anarazel.de 8113 [ - + ]:CBC 1510819 : Assert(!(buf_state & BM_VALID));
8114 [ - + ]: 1510819 : Assert(!(buf_state & BM_DIRTY));
8115 : : }
8116 : :
8117 : : /* temp buffers don't use BM_IO_IN_PROGRESS */
8118 [ + + ]: 1510819 : if (!is_temp)
8119 [ - + ]: 1502366 : Assert(buf_state & BM_IO_IN_PROGRESS);
8120 : :
8121 [ - + ]: 1510819 : Assert(BUF_STATE_GET_REFCOUNT(buf_state) >= 1);
8122 : :
8123 : : /*
8124 : : * Reflect that the buffer is now owned by the AIO subsystem.
8125 : : *
8126 : : * For local buffers: This can't be done just via LocalRefCount, as
8127 : : * one might initially think, as this backend could error out while
8128 : : * AIO is still in progress, releasing all the pins by the backend
8129 : : * itself.
8130 : : *
8131 : : * This pin is released again in TerminateBufferIO().
8132 : : */
8133 : 1510819 : buf_hdr->io_wref = io_ref;
8134 : :
8135 [ + + ]: 1510819 : if (is_temp)
8136 : : {
129 andres@anarazel.de 8137 :GNC 8453 : buf_state += BUF_REFCOUNT_ONE;
59 8138 : 8453 : pg_atomic_unlocked_write_u64(&buf_hdr->state, buf_state);
8139 : : }
8140 : : else
129 8141 : 1502366 : UnlockBufHdrExt(buf_hdr, buf_state, 0, 0, 1);
8142 : :
8143 : : /*
8144 : : * Ensure the content lock that prevents buffer modifications while
8145 : : * the buffer is being written out is not released early due to an
8146 : : * error.
8147 : : */
350 andres@anarazel.de 8148 [ - + - - ]:CBC 1510819 : if (is_write && !is_temp)
8149 : : {
59 andres@anarazel.de 8150 [ # # ]:UNC 0 : Assert(BufferLockHeldByMe(buf_hdr));
8151 : :
8152 : : /*
8153 : : * Lock is now owned by AIO subsystem.
8154 : : */
8155 : 0 : BufferLockDisown(buffer, buf_hdr);
8156 : : }
8157 : :
8158 : : /*
8159 : : * Stop tracking this buffer via the resowner - the AIO system now
8160 : : * keeps track.
8161 : : */
350 andres@anarazel.de 8162 [ + + ]:CBC 1510819 : if (!is_temp)
8163 : 1502366 : ResourceOwnerForgetBufferIO(CurrentResourceOwner, buffer);
8164 : : }
8165 : 1336659 : }
8166 : :
8167 : : /*
8168 : : * Decode readv errors as encoded by buffer_readv_encode_error().
8169 : : */
8170 : : static inline void
8171 : 811 : buffer_readv_decode_error(PgAioResult result,
8172 : : bool *zeroed_any,
8173 : : bool *ignored_any,
8174 : : uint8 *zeroed_or_error_count,
8175 : : uint8 *checkfail_count,
8176 : : uint8 *first_off)
8177 : : {
8178 : 811 : uint32 rem_error = result.error_data;
8179 : :
8180 : : /* see static asserts in buffer_readv_encode_error */
8181 : : #define READV_COUNT_BITS 7
8182 : : #define READV_COUNT_MASK ((1 << READV_COUNT_BITS) - 1)
8183 : :
8184 : 811 : *zeroed_any = rem_error & 1;
8185 : 811 : rem_error >>= 1;
8186 : :
8187 : 811 : *ignored_any = rem_error & 1;
8188 : 811 : rem_error >>= 1;
8189 : :
8190 : 811 : *zeroed_or_error_count = rem_error & READV_COUNT_MASK;
8191 : 811 : rem_error >>= READV_COUNT_BITS;
8192 : :
8193 : 811 : *checkfail_count = rem_error & READV_COUNT_MASK;
8194 : 811 : rem_error >>= READV_COUNT_BITS;
8195 : :
8196 : 811 : *first_off = rem_error & READV_COUNT_MASK;
8197 : 811 : rem_error >>= READV_COUNT_BITS;
8198 : 811 : }
8199 : :
8200 : : /*
8201 : : * Helper to encode errors for buffer_readv_complete()
8202 : : *
8203 : : * Errors are encoded as follows:
8204 : : * - bit 0 indicates whether any page was zeroed (1) or not (0)
8205 : : * - bit 1 indicates whether any checksum failure was ignored (1) or not (0)
8206 : : * - next READV_COUNT_BITS bits indicate the number of errored or zeroed pages
8207 : : * - next READV_COUNT_BITS bits indicate the number of checksum failures
8208 : : * - next READV_COUNT_BITS bits indicate the first offset of the first page
8209 : : * that was errored or zeroed or, if no errors/zeroes, the first ignored
8210 : : * checksum
8211 : : */
8212 : : static inline void
8213 : 288 : buffer_readv_encode_error(PgAioResult *result,
8214 : : bool is_temp,
8215 : : bool zeroed_any,
8216 : : bool ignored_any,
8217 : : uint8 error_count,
8218 : : uint8 zeroed_count,
8219 : : uint8 checkfail_count,
8220 : : uint8 first_error_off,
8221 : : uint8 first_zeroed_off,
8222 : : uint8 first_ignored_off)
8223 : : {
8224 : :
8225 : 288 : uint8 shift = 0;
8226 [ + + ]: 288 : uint8 zeroed_or_error_count =
8227 : : error_count > 0 ? error_count : zeroed_count;
8228 : : uint8 first_off;
8229 : :
8230 : : StaticAssertDecl(PG_IOV_MAX <= 1 << READV_COUNT_BITS,
8231 : : "PG_IOV_MAX is bigger than reserved space for error data");
8232 : : StaticAssertDecl((1 + 1 + 3 * READV_COUNT_BITS) <= PGAIO_RESULT_ERROR_BITS,
8233 : : "PGAIO_RESULT_ERROR_BITS is insufficient for buffer_readv");
8234 : :
8235 : : /*
8236 : : * We only have space to encode one offset - but luckily that's good
8237 : : * enough. If there is an error, the error is the interesting offset, same
8238 : : * with a zeroed buffer vs an ignored buffer.
8239 : : */
8240 [ + + ]: 288 : if (error_count > 0)
8241 : 141 : first_off = first_error_off;
8242 [ + + ]: 147 : else if (zeroed_count > 0)
8243 : 120 : first_off = first_zeroed_off;
8244 : : else
8245 : 27 : first_off = first_ignored_off;
8246 : :
8247 [ + + - + ]: 288 : Assert(!zeroed_any || error_count == 0);
8248 : :
8249 : 288 : result->error_data = 0;
8250 : :
8251 : 288 : result->error_data |= zeroed_any << shift;
8252 : 288 : shift += 1;
8253 : :
8254 : 288 : result->error_data |= ignored_any << shift;
8255 : 288 : shift += 1;
8256 : :
8257 : 288 : result->error_data |= ((uint32) zeroed_or_error_count) << shift;
8258 : 288 : shift += READV_COUNT_BITS;
8259 : :
8260 : 288 : result->error_data |= ((uint32) checkfail_count) << shift;
8261 : 288 : shift += READV_COUNT_BITS;
8262 : :
8263 : 288 : result->error_data |= ((uint32) first_off) << shift;
8264 : 288 : shift += READV_COUNT_BITS;
8265 : :
8266 [ + + ]: 288 : result->id = is_temp ? PGAIO_HCB_LOCAL_BUFFER_READV :
8267 : : PGAIO_HCB_SHARED_BUFFER_READV;
8268 : :
8269 [ + + ]: 288 : if (error_count > 0)
8270 : 141 : result->status = PGAIO_RS_ERROR;
8271 : : else
8272 : 147 : result->status = PGAIO_RS_WARNING;
8273 : :
8274 : : /*
8275 : : * The encoding is complicated enough to warrant cross-checking it against
8276 : : * the decode function.
8277 : : */
8278 : : #ifdef USE_ASSERT_CHECKING
8279 : : {
8280 : : bool zeroed_any_2,
8281 : : ignored_any_2;
8282 : : uint8 zeroed_or_error_count_2,
8283 : : checkfail_count_2,
8284 : : first_off_2;
8285 : :
8286 : 288 : buffer_readv_decode_error(*result,
8287 : : &zeroed_any_2, &ignored_any_2,
8288 : : &zeroed_or_error_count_2,
8289 : : &checkfail_count_2,
8290 : : &first_off_2);
8291 [ - + ]: 288 : Assert(zeroed_any == zeroed_any_2);
8292 [ - + ]: 288 : Assert(ignored_any == ignored_any_2);
8293 [ - + ]: 288 : Assert(zeroed_or_error_count == zeroed_or_error_count_2);
8294 [ - + ]: 288 : Assert(checkfail_count == checkfail_count_2);
8295 [ - + ]: 288 : Assert(first_off == first_off_2);
8296 : : }
8297 : : #endif
8298 : :
8299 : : #undef READV_COUNT_BITS
8300 : : #undef READV_COUNT_MASK
8301 : 288 : }
8302 : :
8303 : : /*
8304 : : * Helper for AIO readv completion callbacks, supporting both shared and temp
8305 : : * buffers. Gets called once for each buffer in a multi-page read.
8306 : : */
8307 : : static pg_attribute_always_inline void
8308 : 1343004 : buffer_readv_complete_one(PgAioTargetData *td, uint8 buf_off, Buffer buffer,
8309 : : uint8 flags, bool failed, bool is_temp,
8310 : : bool *buffer_invalid,
8311 : : bool *failed_checksum,
8312 : : bool *ignored_checksum,
8313 : : bool *zeroed_buffer)
8314 : : {
8315 : 1343004 : BufferDesc *buf_hdr = is_temp ?
8316 : 8453 : GetLocalBufferDescriptor(-buffer - 1)
8317 [ + + ]: 1343004 : : GetBufferDescriptor(buffer - 1);
8318 : 1343004 : BufferTag tag = buf_hdr->tag;
8319 : 1343004 : char *bufdata = BufferGetBlock(buffer);
8320 : : uint64 set_flag_bits;
8321 : : int piv_flags;
8322 : :
8323 : : /* check that the buffer is in the expected state for a read */
8324 : : #ifdef USE_ASSERT_CHECKING
8325 : : {
59 andres@anarazel.de 8326 :GNC 1343004 : uint64 buf_state = pg_atomic_read_u64(&buf_hdr->state);
8327 : :
350 andres@anarazel.de 8328 [ - + ]:CBC 1343004 : Assert(buf_state & BM_TAG_VALID);
8329 [ - + ]: 1343004 : Assert(!(buf_state & BM_VALID));
8330 : : /* temp buffers don't use BM_IO_IN_PROGRESS */
8331 [ + + ]: 1343004 : if (!is_temp)
8332 [ - + ]: 1334551 : Assert(buf_state & BM_IO_IN_PROGRESS);
8333 [ - + ]: 1343004 : Assert(!(buf_state & BM_DIRTY));
8334 : : }
8335 : : #endif
8336 : :
8337 : 1343004 : *buffer_invalid = false;
8338 : 1343004 : *failed_checksum = false;
8339 : 1343004 : *ignored_checksum = false;
8340 : 1343004 : *zeroed_buffer = false;
8341 : :
8342 : : /*
8343 : : * We ask PageIsVerified() to only log the message about checksum errors,
8344 : : * as the completion might be run in any backend (or IO workers). We will
8345 : : * report checksum errors in buffer_readv_report().
8346 : : */
8347 : 1343004 : piv_flags = PIV_LOG_LOG;
8348 : :
8349 : : /* the local zero_damaged_pages may differ from the definer's */
8350 [ + + ]: 1343004 : if (flags & READ_BUFFERS_IGNORE_CHECKSUM_FAILURES)
8351 : 57 : piv_flags |= PIV_IGNORE_CHECKSUM_FAILURE;
8352 : :
8353 : : /* Check for garbage data. */
8354 [ + + ]: 1343004 : if (!failed)
8355 : : {
8356 : : /*
8357 : : * If the buffer is not currently pinned by this backend, e.g. because
8358 : : * we're completing this IO after an error, the buffer data will have
8359 : : * been marked as inaccessible when the buffer was unpinned. The AIO
8360 : : * subsystem holds a pin, but that doesn't prevent the buffer from
8361 : : * having been marked as inaccessible. The completion might also be
8362 : : * executed in a different process.
8363 : : */
8364 : : #ifdef USE_VALGRIND
8365 : : if (!BufferIsPinned(buffer))
8366 : : VALGRIND_MAKE_MEM_DEFINED(bufdata, BLCKSZ);
8367 : : #endif
8368 : :
8369 [ + + ]: 1342961 : if (!PageIsVerified((Page) bufdata, tag.blockNum, piv_flags,
8370 : : failed_checksum))
8371 : : {
8372 [ + + ]: 144 : if (flags & READ_BUFFERS_ZERO_ON_ERROR)
8373 : : {
8374 : 69 : memset(bufdata, 0, BLCKSZ);
8375 : 69 : *zeroed_buffer = true;
8376 : : }
8377 : : else
8378 : : {
8379 : 75 : *buffer_invalid = true;
8380 : : /* mark buffer as having failed */
8381 : 75 : failed = true;
8382 : : }
8383 : : }
8384 [ + + ]: 1342817 : else if (*failed_checksum)
8385 : 18 : *ignored_checksum = true;
8386 : :
8387 : : /* undo what we did above */
8388 : : #ifdef USE_VALGRIND
8389 : : if (!BufferIsPinned(buffer))
8390 : : VALGRIND_MAKE_MEM_NOACCESS(bufdata, BLCKSZ);
8391 : : #endif
8392 : :
8393 : : /*
8394 : : * Immediately log a message about the invalid page, but only to the
8395 : : * server log. The reason to do so immediately is that this may be
8396 : : * executed in a different backend than the one that originated the
8397 : : * request. The reason to do so immediately is that the originator
8398 : : * might not process the query result immediately (because it is busy
8399 : : * doing another part of query processing) or at all (e.g. if it was
8400 : : * cancelled or errored out due to another IO also failing). The
8401 : : * definer of the IO will emit an ERROR or WARNING when processing the
8402 : : * IO's results
8403 : : *
8404 : : * To avoid duplicating the code to emit these log messages, we reuse
8405 : : * buffer_readv_report().
8406 : : */
8407 [ + + + + : 1342961 : if (*buffer_invalid || *failed_checksum || *zeroed_buffer)
+ + ]
8408 : : {
345 8409 : 162 : PgAioResult result_one = {0};
8410 : :
350 8411 : 162 : buffer_readv_encode_error(&result_one, is_temp,
8412 : 162 : *zeroed_buffer,
8413 : 162 : *ignored_checksum,
8414 : 162 : *buffer_invalid,
8415 : 162 : *zeroed_buffer ? 1 : 0,
8416 : 162 : *failed_checksum ? 1 : 0,
8417 : : buf_off, buf_off, buf_off);
8418 : 162 : pgaio_result_report(result_one, td, LOG_SERVER_ONLY);
8419 : : }
8420 : : }
8421 : :
8422 : : /* Terminate I/O and set BM_VALID. */
8423 [ + + ]: 1343004 : set_flag_bits = failed ? BM_IO_ERROR : BM_VALID;
8424 [ + + ]: 1343004 : if (is_temp)
8425 : 8453 : TerminateLocalBufferIO(buf_hdr, false, set_flag_bits, true);
8426 : : else
8427 : 1334551 : TerminateBufferIO(buf_hdr, false, set_flag_bits, false, true);
8428 : :
8429 : : /*
8430 : : * Call the BUFFER_READ_DONE tracepoint in the callback, even though the
8431 : : * callback may not be executed in the same backend that called
8432 : : * BUFFER_READ_START. The alternative would be to defer calling the
8433 : : * tracepoint to a later point (e.g. the local completion callback for
8434 : : * shared buffer reads), which seems even less helpful.
8435 : : */
8436 : : TRACE_POSTGRESQL_BUFFER_READ_DONE(tag.forkNum,
8437 : : tag.blockNum,
8438 : : tag.spcOid,
8439 : : tag.dbOid,
8440 : : tag.relNumber,
8441 : : is_temp ? MyProcNumber : INVALID_PROC_NUMBER,
8442 : : false);
8443 : 1343004 : }
8444 : :
8445 : : /*
8446 : : * Perform completion handling of a single AIO read. This read may cover
8447 : : * multiple blocks / buffers.
8448 : : *
8449 : : * Shared between shared and local buffers, to reduce code duplication.
8450 : : */
8451 : : static pg_attribute_always_inline PgAioResult
8452 : 1202622 : buffer_readv_complete(PgAioHandle *ioh, PgAioResult prior_result,
8453 : : uint8 cb_data, bool is_temp)
8454 : : {
8455 : 1202622 : PgAioResult result = prior_result;
8456 : 1202622 : PgAioTargetData *td = pgaio_io_get_target_data(ioh);
8457 : 1202622 : uint8 first_error_off = 0;
8458 : 1202622 : uint8 first_zeroed_off = 0;
8459 : 1202622 : uint8 first_ignored_off = 0;
8460 : 1202622 : uint8 error_count = 0;
8461 : 1202622 : uint8 zeroed_count = 0;
8462 : 1202622 : uint8 ignored_count = 0;
8463 : 1202622 : uint8 checkfail_count = 0;
8464 : : uint64 *io_data;
8465 : : uint8 handle_data_len;
8466 : :
8467 [ + + ]: 1202622 : if (is_temp)
8468 : : {
8469 [ - + ]: 1829 : Assert(td->smgr.is_temp);
8470 [ - + ]: 1829 : Assert(pgaio_io_get_owner(ioh) == MyProcNumber);
8471 : : }
8472 : : else
8473 [ - + ]: 1200793 : Assert(!td->smgr.is_temp);
8474 : :
8475 : : /*
8476 : : * Iterate over all the buffers affected by this IO and call the
8477 : : * per-buffer completion function for each buffer.
8478 : : */
8479 : 1202622 : io_data = pgaio_io_get_handle_data(ioh, &handle_data_len);
8480 [ + + ]: 2545626 : for (uint8 buf_off = 0; buf_off < handle_data_len; buf_off++)
8481 : : {
8482 : 1343004 : Buffer buf = io_data[buf_off];
8483 : : bool failed;
8484 : 1343004 : bool failed_verification = false;
8485 : 1343004 : bool failed_checksum = false;
8486 : 1343004 : bool zeroed_buffer = false;
8487 : 1343004 : bool ignored_checksum = false;
8488 : :
8489 [ - + ]: 1343004 : Assert(BufferIsValid(buf));
8490 : :
8491 : : /*
8492 : : * If the entire I/O failed on a lower-level, each buffer needs to be
8493 : : * marked as failed. In case of a partial read, the first few buffers
8494 : : * may be ok.
8495 : : */
8496 : 1343004 : failed =
8497 : 1343004 : prior_result.status == PGAIO_RS_ERROR
8498 [ + + + + ]: 1343004 : || prior_result.result <= buf_off;
8499 : :
8500 : 1343004 : buffer_readv_complete_one(td, buf_off, buf, cb_data, failed, is_temp,
8501 : : &failed_verification,
8502 : : &failed_checksum,
8503 : : &ignored_checksum,
8504 : : &zeroed_buffer);
8505 : :
8506 : : /*
8507 : : * Track information about the number of different kinds of error
8508 : : * conditions across all pages, as there can be multiple pages failing
8509 : : * verification as part of one IO.
8510 : : */
8511 [ + + + - : 1343004 : if (failed_verification && !zeroed_buffer && error_count++ == 0)
+ + ]
8512 : 66 : first_error_off = buf_off;
8513 [ + + + + ]: 1343004 : if (zeroed_buffer && zeroed_count++ == 0)
8514 : 51 : first_zeroed_off = buf_off;
8515 [ + + + + ]: 1343004 : if (ignored_checksum && ignored_count++ == 0)
8516 : 15 : first_ignored_off = buf_off;
8517 [ + + ]: 1343004 : if (failed_checksum)
8518 : 48 : checkfail_count++;
8519 : : }
8520 : :
8521 : : /*
8522 : : * If the smgr read succeeded [partially] and page verification failed for
8523 : : * some of the pages, adjust the IO's result state appropriately.
8524 : : */
8525 [ + + + + ]: 1202622 : if (prior_result.status != PGAIO_RS_ERROR &&
8526 [ + + + + ]: 1202543 : (error_count > 0 || ignored_count > 0 || zeroed_count > 0))
8527 : : {
8528 : 126 : buffer_readv_encode_error(&result, is_temp,
8529 : : zeroed_count > 0, ignored_count > 0,
8530 : : error_count, zeroed_count, checkfail_count,
8531 : : first_error_off, first_zeroed_off,
8532 : : first_ignored_off);
8533 : 126 : pgaio_result_report(result, td, DEBUG1);
8534 : : }
8535 : :
8536 : : /*
8537 : : * For shared relations this reporting is done in
8538 : : * shared_buffer_readv_complete_local().
8539 : : */
8540 [ + + + + ]: 1202622 : if (is_temp && checkfail_count > 0)
8541 : 3 : pgstat_report_checksum_failures_in_db(td->smgr.rlocator.dbOid,
8542 : : checkfail_count);
8543 : :
8544 : 1202622 : return result;
8545 : : }
8546 : :
8547 : : /*
8548 : : * AIO error reporting callback for aio_shared_buffer_readv_cb and
8549 : : * aio_local_buffer_readv_cb.
8550 : : *
8551 : : * The error is encoded / decoded in buffer_readv_encode_error() /
8552 : : * buffer_readv_decode_error().
8553 : : */
8554 : : static void
8555 : 408 : buffer_readv_report(PgAioResult result, const PgAioTargetData *td,
8556 : : int elevel)
8557 : : {
8558 : 408 : int nblocks = td->smgr.nblocks;
8559 : 408 : BlockNumber first = td->smgr.blockNum;
8560 : 408 : BlockNumber last = first + nblocks - 1;
8561 : 408 : ProcNumber errProc =
8562 [ + + ]: 408 : td->smgr.is_temp ? MyProcNumber : INVALID_PROC_NUMBER;
8563 : : RelPathStr rpath =
8564 : 408 : relpathbackend(td->smgr.rlocator, errProc, td->smgr.forkNum);
8565 : : bool zeroed_any,
8566 : : ignored_any;
8567 : : uint8 zeroed_or_error_count,
8568 : : checkfail_count,
8569 : : first_off;
8570 : : uint8 affected_count;
8571 : : const char *msg_one,
8572 : : *msg_mult,
8573 : : *det_mult,
8574 : : *hint_mult;
8575 : :
8576 : 408 : buffer_readv_decode_error(result, &zeroed_any, &ignored_any,
8577 : : &zeroed_or_error_count,
8578 : : &checkfail_count,
8579 : : &first_off);
8580 : :
8581 : : /*
8582 : : * Treat a read that had both zeroed buffers *and* ignored checksums as a
8583 : : * special case, it's too irregular to be emitted the same way as the
8584 : : * other cases.
8585 : : */
8586 [ + + + + ]: 408 : if (zeroed_any && ignored_any)
8587 : : {
8588 [ + - - + ]: 6 : Assert(zeroed_any && ignored_any);
8589 [ - + ]: 6 : Assert(nblocks > 1); /* same block can't be both zeroed and ignored */
8590 [ - + ]: 6 : Assert(result.status != PGAIO_RS_ERROR);
8591 : 6 : affected_count = zeroed_or_error_count;
8592 : :
8593 [ + - + - ]: 6 : ereport(elevel,
8594 : : errcode(ERRCODE_DATA_CORRUPTED),
8595 : : errmsg("zeroing %u page(s) and ignoring %u checksum failure(s) among blocks %u..%u of relation \"%s\"",
8596 : : affected_count, checkfail_count, first, last, rpath.str),
8597 : : affected_count > 1 ?
8598 : : errdetail("Block %u held the first zeroed page.",
8599 : : first + first_off) : 0,
8600 : : errhint_plural("See server log for details about the other %d invalid block.",
8601 : : "See server log for details about the other %d invalid blocks.",
8602 : : affected_count + checkfail_count - 1,
8603 : : affected_count + checkfail_count - 1));
8604 : 6 : return;
8605 : : }
8606 : :
8607 : : /*
8608 : : * The other messages are highly repetitive. To avoid duplicating a long
8609 : : * and complicated ereport(), gather the translated format strings
8610 : : * separately and then do one common ereport.
8611 : : */
8612 [ + + ]: 402 : if (result.status == PGAIO_RS_ERROR)
8613 : : {
8614 [ - + ]: 204 : Assert(!zeroed_any); /* can't have invalid pages when zeroing them */
8615 : 204 : affected_count = zeroed_or_error_count;
201 peter@eisentraut.org 8616 : 204 : msg_one = _("invalid page in block %u of relation \"%s\"");
8617 : 204 : msg_mult = _("%u invalid pages among blocks %u..%u of relation \"%s\"");
8618 : 204 : det_mult = _("Block %u held the first invalid page.");
350 andres@anarazel.de 8619 : 204 : hint_mult = _("See server log for the other %u invalid block(s).");
8620 : : }
8621 [ + + + - ]: 198 : else if (zeroed_any && !ignored_any)
8622 : : {
8623 : 162 : affected_count = zeroed_or_error_count;
201 peter@eisentraut.org 8624 : 162 : msg_one = _("invalid page in block %u of relation \"%s\"; zeroing out page");
8625 : 162 : msg_mult = _("zeroing out %u invalid pages among blocks %u..%u of relation \"%s\"");
8626 : 162 : det_mult = _("Block %u held the first zeroed page.");
350 andres@anarazel.de 8627 : 162 : hint_mult = _("See server log for the other %u zeroed block(s).");
8628 : : }
8629 [ + - + - ]: 36 : else if (!zeroed_any && ignored_any)
8630 : : {
8631 : 36 : affected_count = checkfail_count;
201 peter@eisentraut.org 8632 : 36 : msg_one = _("ignoring checksum failure in block %u of relation \"%s\"");
8633 : 36 : msg_mult = _("ignoring %u checksum failures among blocks %u..%u of relation \"%s\"");
8634 : 36 : det_mult = _("Block %u held the first ignored page.");
350 andres@anarazel.de 8635 : 36 : hint_mult = _("See server log for the other %u ignored block(s).");
8636 : : }
8637 : : else
350 andres@anarazel.de 8638 :UBC 0 : pg_unreachable();
8639 : :
350 andres@anarazel.de 8640 [ + - + + :CBC 402 : ereport(elevel,
+ + + + ]
8641 : : errcode(ERRCODE_DATA_CORRUPTED),
8642 : : affected_count == 1 ?
8643 : : errmsg_internal(msg_one, first + first_off, rpath.str) :
8644 : : errmsg_internal(msg_mult, affected_count, first, last, rpath.str),
8645 : : affected_count > 1 ? errdetail_internal(det_mult, first + first_off) : 0,
8646 : : affected_count > 1 ? errhint_internal(hint_mult, affected_count - 1) : 0);
8647 : : }
8648 : :
8649 : : static void
8650 : 1334830 : shared_buffer_readv_stage(PgAioHandle *ioh, uint8 cb_data)
8651 : : {
8652 : 1334830 : buffer_stage_common(ioh, false, false);
8653 : 1334830 : }
8654 : :
8655 : : static PgAioResult
8656 : 1200793 : shared_buffer_readv_complete(PgAioHandle *ioh, PgAioResult prior_result,
8657 : : uint8 cb_data)
8658 : : {
8659 : 1200793 : return buffer_readv_complete(ioh, prior_result, cb_data, false);
8660 : : }
8661 : :
8662 : : /*
8663 : : * We need a backend-local completion callback for shared buffers, to be able
8664 : : * to report checksum errors correctly. Unfortunately that can only safely
8665 : : * happen if the reporting backend has previously called
8666 : : * pgstat_prepare_report_checksum_failure(), which we can only guarantee in
8667 : : * the backend that started the IO. Hence this callback.
8668 : : */
8669 : : static PgAioResult
8670 : 1334830 : shared_buffer_readv_complete_local(PgAioHandle *ioh, PgAioResult prior_result,
8671 : : uint8 cb_data)
8672 : : {
8673 : : bool zeroed_any,
8674 : : ignored_any;
8675 : : uint8 zeroed_or_error_count,
8676 : : checkfail_count,
8677 : : first_off;
8678 : :
8679 [ + + ]: 1334830 : if (prior_result.status == PGAIO_RS_OK)
8680 : 1334715 : return prior_result;
8681 : :
8682 : 115 : buffer_readv_decode_error(prior_result,
8683 : : &zeroed_any,
8684 : : &ignored_any,
8685 : : &zeroed_or_error_count,
8686 : : &checkfail_count,
8687 : : &first_off);
8688 : :
8689 [ + + ]: 115 : if (checkfail_count)
8690 : : {
8691 : 36 : PgAioTargetData *td = pgaio_io_get_target_data(ioh);
8692 : :
8693 : 36 : pgstat_report_checksum_failures_in_db(td->smgr.rlocator.dbOid,
8694 : : checkfail_count);
8695 : : }
8696 : :
8697 : 115 : return prior_result;
8698 : : }
8699 : :
8700 : : static void
8701 : 1829 : local_buffer_readv_stage(PgAioHandle *ioh, uint8 cb_data)
8702 : : {
8703 : 1829 : buffer_stage_common(ioh, false, true);
8704 : 1829 : }
8705 : :
8706 : : static PgAioResult
8707 : 1829 : local_buffer_readv_complete(PgAioHandle *ioh, PgAioResult prior_result,
8708 : : uint8 cb_data)
8709 : : {
8710 : 1829 : return buffer_readv_complete(ioh, prior_result, cb_data, true);
8711 : : }
8712 : :
8713 : : /* readv callback is passed READ_BUFFERS_* flags as callback data */
8714 : : const PgAioHandleCallbacks aio_shared_buffer_readv_cb = {
8715 : : .stage = shared_buffer_readv_stage,
8716 : : .complete_shared = shared_buffer_readv_complete,
8717 : : /* need a local callback to report checksum failures */
8718 : : .complete_local = shared_buffer_readv_complete_local,
8719 : : .report = buffer_readv_report,
8720 : : };
8721 : :
8722 : : /* readv callback is passed READ_BUFFERS_* flags as callback data */
8723 : : const PgAioHandleCallbacks aio_local_buffer_readv_cb = {
8724 : : .stage = local_buffer_readv_stage,
8725 : :
8726 : : /*
8727 : : * Note that this, in contrast to the shared_buffers case, uses
8728 : : * complete_local, as only the issuing backend has access to the required
8729 : : * datastructures. This is important in case the IO completion may be
8730 : : * consumed incidentally by another backend.
8731 : : */
8732 : : .complete_local = local_buffer_readv_complete,
8733 : : .report = buffer_readv_report,
8734 : : };
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