Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * waiteventset.c
4 : : * ppoll()/pselect() like abstraction
5 : : *
6 : : * WaitEvents are an abstraction for waiting for one or more events at a time.
7 : : * The waiting can be done in a race free fashion, similar ppoll() or
8 : : * pselect() (as opposed to plain poll()/select()).
9 : : *
10 : : * You can wait for:
11 : : * - a latch being set from another process or from signal handler in the same
12 : : * process (WL_LATCH_SET)
13 : : * - data to become readable or writeable on a socket (WL_SOCKET_*)
14 : : * - postmaster death (WL_POSTMASTER_DEATH or WL_EXIT_ON_PM_DEATH)
15 : : * - timeout (WL_TIMEOUT)
16 : : *
17 : : * Implementation
18 : : * --------------
19 : : *
20 : : * The poll() implementation uses the so-called self-pipe trick to overcome the
21 : : * race condition involved with poll() and setting a global flag in the signal
22 : : * handler. When a latch is set and the current process is waiting for it, the
23 : : * signal handler wakes up the poll() in WaitLatch by writing a byte to a pipe.
24 : : * A signal by itself doesn't interrupt poll() on all platforms, and even on
25 : : * platforms where it does, a signal that arrives just before the poll() call
26 : : * does not prevent poll() from entering sleep. An incoming byte on a pipe
27 : : * however reliably interrupts the sleep, and causes poll() to return
28 : : * immediately even if the signal arrives before poll() begins.
29 : : *
30 : : * The epoll() implementation overcomes the race with a different technique: it
31 : : * keeps SIGURG blocked and consumes from a signalfd() descriptor instead. We
32 : : * don't need to register a signal handler or create our own self-pipe. We
33 : : * assume that any system that has Linux epoll() also has Linux signalfd().
34 : : *
35 : : * The kqueue() implementation waits for SIGURG with EVFILT_SIGNAL.
36 : : *
37 : : * The Windows implementation uses Windows events that are inherited by all
38 : : * postmaster child processes. There's no need for the self-pipe trick there.
39 : : *
40 : : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
41 : : * Portions Copyright (c) 1994, Regents of the University of California
42 : : *
43 : : * IDENTIFICATION
44 : : * src/backend/storage/ipc/waiteventset.c
45 : : *
46 : : *-------------------------------------------------------------------------
47 : : */
48 : : #include "postgres.h"
49 : :
50 : : #include <fcntl.h>
51 : : #include <limits.h>
52 : : #include <signal.h>
53 : : #include <unistd.h>
54 : : #ifdef HAVE_SYS_EPOLL_H
55 : : #include <sys/epoll.h>
56 : : #endif
57 : : #ifdef HAVE_SYS_EVENT_H
58 : : #include <sys/event.h>
59 : : #endif
60 : : #ifdef HAVE_SYS_SIGNALFD_H
61 : : #include <sys/signalfd.h>
62 : : #endif
63 : : #ifdef HAVE_POLL_H
64 : : #include <poll.h>
65 : : #endif
66 : :
67 : : #include "libpq/pqsignal.h"
68 : : #include "miscadmin.h"
69 : : #include "pgstat.h"
70 : : #include "portability/instr_time.h"
71 : : #include "postmaster/postmaster.h"
72 : : #include "storage/fd.h"
73 : : #include "storage/ipc.h"
74 : : #include "storage/pmsignal.h"
75 : : #include "storage/latch.h"
76 : : #include "storage/waiteventset.h"
77 : : #include "utils/memutils.h"
78 : : #include "utils/resowner.h"
79 : :
80 : : /*
81 : : * Select the fd readiness primitive to use. Normally the "most modern"
82 : : * primitive supported by the OS will be used, but for testing it can be
83 : : * useful to manually specify the used primitive. If desired, just add a
84 : : * define somewhere before this block.
85 : : */
86 : : #if defined(WAIT_USE_EPOLL) || defined(WAIT_USE_POLL) || \
87 : : defined(WAIT_USE_KQUEUE) || defined(WAIT_USE_WIN32)
88 : : /* don't overwrite manual choice */
89 : : #elif defined(HAVE_SYS_EPOLL_H)
90 : : #define WAIT_USE_EPOLL
91 : : #elif defined(HAVE_KQUEUE)
92 : : #define WAIT_USE_KQUEUE
93 : : #elif defined(HAVE_POLL)
94 : : #define WAIT_USE_POLL
95 : : #elif WIN32
96 : : #define WAIT_USE_WIN32
97 : : #else
98 : : #error "no wait set implementation available"
99 : : #endif
100 : :
101 : : /*
102 : : * By default, we use a self-pipe with poll() and a signalfd with epoll(), if
103 : : * available. For testing the choice can also be manually specified.
104 : : */
105 : : #if defined(WAIT_USE_POLL) || defined(WAIT_USE_EPOLL)
106 : : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
107 : : /* don't overwrite manual choice */
108 : : #elif defined(WAIT_USE_EPOLL) && defined(HAVE_SYS_SIGNALFD_H)
109 : : #define WAIT_USE_SIGNALFD
110 : : #else
111 : : #define WAIT_USE_SELF_PIPE
112 : : #endif
113 : : #endif
114 : :
115 : : /* typedef in waiteventset.h */
116 : : struct WaitEventSet
117 : : {
118 : : ResourceOwner owner;
119 : :
120 : : int nevents; /* number of registered events */
121 : : int nevents_space; /* maximum number of events in this set */
122 : :
123 : : /*
124 : : * Array, of nevents_space length, storing the definition of events this
125 : : * set is waiting for.
126 : : */
127 : : WaitEvent *events;
128 : :
129 : : /*
130 : : * If WL_LATCH_SET is specified in any wait event, latch is a pointer to
131 : : * said latch, and latch_pos the offset in the ->events array. This is
132 : : * useful because we check the state of the latch before performing doing
133 : : * syscalls related to waiting.
134 : : */
135 : : Latch *latch;
136 : : int latch_pos;
137 : :
138 : : /*
139 : : * WL_EXIT_ON_PM_DEATH is converted to WL_POSTMASTER_DEATH, but this flag
140 : : * is set so that we'll exit immediately if postmaster death is detected,
141 : : * instead of returning.
142 : : */
143 : : bool exit_on_postmaster_death;
144 : :
145 : : #if defined(WAIT_USE_EPOLL)
146 : : int epoll_fd;
147 : : /* epoll_wait returns events in a user provided arrays, allocate once */
148 : : struct epoll_event *epoll_ret_events;
149 : : #elif defined(WAIT_USE_KQUEUE)
150 : : int kqueue_fd;
151 : : /* kevent returns events in a user provided arrays, allocate once */
152 : : struct kevent *kqueue_ret_events;
153 : : bool report_postmaster_not_running;
154 : : #elif defined(WAIT_USE_POLL)
155 : : /* poll expects events to be waited on every poll() call, prepare once */
156 : : struct pollfd *pollfds;
157 : : #elif defined(WAIT_USE_WIN32)
158 : :
159 : : /*
160 : : * Array of windows events. The first element always contains
161 : : * pgwin32_signal_event, so the remaining elements are offset by one (i.e.
162 : : * event->pos + 1).
163 : : */
164 : : HANDLE *handles;
165 : : #endif
166 : : };
167 : :
168 : : #ifndef WIN32
169 : : /* Are we currently in WaitLatch? The signal handler would like to know. */
170 : : static volatile sig_atomic_t waiting = false;
171 : : #endif
172 : :
173 : : #ifdef WAIT_USE_SIGNALFD
174 : : /* On Linux, we'll receive SIGURG via a signalfd file descriptor. */
175 : : static int signal_fd = -1;
176 : : #endif
177 : :
178 : : #ifdef WAIT_USE_SELF_PIPE
179 : : /* Read and write ends of the self-pipe */
180 : : static int selfpipe_readfd = -1;
181 : : static int selfpipe_writefd = -1;
182 : :
183 : : /* Process owning the self-pipe --- needed for checking purposes */
184 : : static int selfpipe_owner_pid = 0;
185 : :
186 : : /* Private function prototypes */
187 : : static void latch_sigurg_handler(SIGNAL_ARGS);
188 : : static void sendSelfPipeByte(void);
189 : : #endif
190 : :
191 : : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
192 : : static void drain(void);
193 : : #endif
194 : :
195 : : #if defined(WAIT_USE_EPOLL)
196 : : static void WaitEventAdjustEpoll(WaitEventSet *set, WaitEvent *event, int action);
197 : : #elif defined(WAIT_USE_KQUEUE)
198 : : static void WaitEventAdjustKqueue(WaitEventSet *set, WaitEvent *event, int old_events);
199 : : #elif defined(WAIT_USE_POLL)
200 : : static void WaitEventAdjustPoll(WaitEventSet *set, WaitEvent *event);
201 : : #elif defined(WAIT_USE_WIN32)
202 : : static void WaitEventAdjustWin32(WaitEventSet *set, WaitEvent *event);
203 : : #endif
204 : :
205 : : static inline int WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
206 : : WaitEvent *occurred_events, int nevents);
207 : :
208 : : /* ResourceOwner support to hold WaitEventSets */
209 : : static void ResOwnerReleaseWaitEventSet(Datum res);
210 : :
211 : : static const ResourceOwnerDesc wait_event_set_resowner_desc =
212 : : {
213 : : .name = "WaitEventSet",
214 : : .release_phase = RESOURCE_RELEASE_AFTER_LOCKS,
215 : : .release_priority = RELEASE_PRIO_WAITEVENTSETS,
216 : : .ReleaseResource = ResOwnerReleaseWaitEventSet,
217 : : .DebugPrint = NULL
218 : : };
219 : :
220 : : /* Convenience wrappers over ResourceOwnerRemember/Forget */
221 : : static inline void
184 heikki.linnakangas@i 222 :CBC 106762 : ResourceOwnerRememberWaitEventSet(ResourceOwner owner, WaitEventSet *set)
223 : : {
224 : 106762 : ResourceOwnerRemember(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
225 : 106762 : }
226 : : static inline void
227 : 106761 : ResourceOwnerForgetWaitEventSet(ResourceOwner owner, WaitEventSet *set)
228 : : {
229 : 106761 : ResourceOwnerForget(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
230 : 106761 : }
231 : :
232 : :
233 : : /*
234 : : * Initialize the process-local wait event infrastructure.
235 : : *
236 : : * This must be called once during startup of any process that can wait on
237 : : * latches, before it issues any InitLatch() or OwnLatch() calls.
238 : : */
239 : : void
240 : 20042 : InitializeWaitEventSupport(void)
241 : : {
242 : : #if defined(WAIT_USE_SELF_PIPE)
243 : : int pipefd[2];
244 : :
245 : : if (IsUnderPostmaster)
246 : : {
247 : : /*
248 : : * We might have inherited connections to a self-pipe created by the
249 : : * postmaster. It's critical that child processes create their own
250 : : * self-pipes, of course, and we really want them to close the
251 : : * inherited FDs for safety's sake.
252 : : */
253 : : if (selfpipe_owner_pid != 0)
254 : : {
255 : : /* Assert we go through here but once in a child process */
256 : : Assert(selfpipe_owner_pid != MyProcPid);
257 : : /* Release postmaster's pipe FDs; ignore any error */
258 : : (void) close(selfpipe_readfd);
259 : : (void) close(selfpipe_writefd);
260 : : /* Clean up, just for safety's sake; we'll set these below */
261 : : selfpipe_readfd = selfpipe_writefd = -1;
262 : : selfpipe_owner_pid = 0;
263 : : /* Keep fd.c's accounting straight */
264 : : ReleaseExternalFD();
265 : : ReleaseExternalFD();
266 : : }
267 : : else
268 : : {
269 : : /*
270 : : * Postmaster didn't create a self-pipe ... or else we're in an
271 : : * EXEC_BACKEND build, in which case it doesn't matter since the
272 : : * postmaster's pipe FDs were closed by the action of FD_CLOEXEC.
273 : : * fd.c won't have state to clean up, either.
274 : : */
275 : : Assert(selfpipe_readfd == -1);
276 : : }
277 : : }
278 : : else
279 : : {
280 : : /* In postmaster or standalone backend, assert we do this but once */
281 : : Assert(selfpipe_readfd == -1);
282 : : Assert(selfpipe_owner_pid == 0);
283 : : }
284 : :
285 : : /*
286 : : * Set up the self-pipe that allows a signal handler to wake up the
287 : : * poll()/epoll_wait() in WaitLatch. Make the write-end non-blocking, so
288 : : * that SetLatch won't block if the event has already been set many times
289 : : * filling the kernel buffer. Make the read-end non-blocking too, so that
290 : : * we can easily clear the pipe by reading until EAGAIN or EWOULDBLOCK.
291 : : * Also, make both FDs close-on-exec, since we surely do not want any
292 : : * child processes messing with them.
293 : : */
294 : : if (pipe(pipefd) < 0)
295 : : elog(FATAL, "pipe() failed: %m");
296 : : if (fcntl(pipefd[0], F_SETFL, O_NONBLOCK) == -1)
297 : : elog(FATAL, "fcntl(F_SETFL) failed on read-end of self-pipe: %m");
298 : : if (fcntl(pipefd[1], F_SETFL, O_NONBLOCK) == -1)
299 : : elog(FATAL, "fcntl(F_SETFL) failed on write-end of self-pipe: %m");
300 : : if (fcntl(pipefd[0], F_SETFD, FD_CLOEXEC) == -1)
301 : : elog(FATAL, "fcntl(F_SETFD) failed on read-end of self-pipe: %m");
302 : : if (fcntl(pipefd[1], F_SETFD, FD_CLOEXEC) == -1)
303 : : elog(FATAL, "fcntl(F_SETFD) failed on write-end of self-pipe: %m");
304 : :
305 : : selfpipe_readfd = pipefd[0];
306 : : selfpipe_writefd = pipefd[1];
307 : : selfpipe_owner_pid = MyProcPid;
308 : :
309 : : /* Tell fd.c about these two long-lived FDs */
310 : : ReserveExternalFD();
311 : : ReserveExternalFD();
312 : :
313 : : pqsignal(SIGURG, latch_sigurg_handler);
314 : : #endif
315 : :
316 : : #ifdef WAIT_USE_SIGNALFD
317 : : sigset_t signalfd_mask;
318 : :
319 [ + + ]: 20042 : if (IsUnderPostmaster)
320 : : {
321 : : /*
322 : : * It would probably be safe to re-use the inherited signalfd since
323 : : * signalfds only see the current process's pending signals, but it
324 : : * seems less surprising to close it and create our own.
325 : : */
326 [ + - ]: 18975 : if (signal_fd != -1)
327 : : {
328 : : /* Release postmaster's signal FD; ignore any error */
329 : 18975 : (void) close(signal_fd);
330 : 18975 : signal_fd = -1;
331 : 18975 : ReleaseExternalFD();
332 : : }
333 : : }
334 : :
335 : : /* Block SIGURG, because we'll receive it through a signalfd. */
336 : 20042 : sigaddset(&UnBlockSig, SIGURG);
337 : :
338 : : /* Set up the signalfd to receive SIGURG notifications. */
339 : 20042 : sigemptyset(&signalfd_mask);
340 : 20042 : sigaddset(&signalfd_mask, SIGURG);
341 : 20042 : signal_fd = signalfd(-1, &signalfd_mask, SFD_NONBLOCK | SFD_CLOEXEC);
342 [ - + ]: 20042 : if (signal_fd < 0)
184 heikki.linnakangas@i 343 [ # # ]:UBC 0 : elog(FATAL, "signalfd() failed");
184 heikki.linnakangas@i 344 :CBC 20042 : ReserveExternalFD();
345 : : #endif
346 : :
347 : : #ifdef WAIT_USE_KQUEUE
348 : : /* Ignore SIGURG, because we'll receive it via kqueue. */
349 : : pqsignal(SIGURG, SIG_IGN);
350 : : #endif
351 : 20042 : }
352 : :
353 : : /*
354 : : * Create a WaitEventSet with space for nevents different events to wait for.
355 : : *
356 : : * These events can then be efficiently waited upon together, using
357 : : * WaitEventSetWait().
358 : : *
359 : : * The WaitEventSet is tracked by the given 'resowner'. Use NULL for session
360 : : * lifetime.
361 : : */
362 : : WaitEventSet *
363 : 150139 : CreateWaitEventSet(ResourceOwner resowner, int nevents)
364 : : {
365 : : WaitEventSet *set;
366 : : char *data;
367 : 150139 : Size sz = 0;
368 : :
369 : : /*
370 : : * Use MAXALIGN size/alignment to guarantee that later uses of memory are
371 : : * aligned correctly. E.g. epoll_event might need 8 byte alignment on some
372 : : * platforms, but earlier allocations like WaitEventSet and WaitEvent
373 : : * might not be sized to guarantee that when purely using sizeof().
374 : : */
375 : 150139 : sz += MAXALIGN(sizeof(WaitEventSet));
376 : 150139 : sz += MAXALIGN(sizeof(WaitEvent) * nevents);
377 : :
378 : : #if defined(WAIT_USE_EPOLL)
379 : 150139 : sz += MAXALIGN(sizeof(struct epoll_event) * nevents);
380 : : #elif defined(WAIT_USE_KQUEUE)
381 : : sz += MAXALIGN(sizeof(struct kevent) * nevents);
382 : : #elif defined(WAIT_USE_POLL)
383 : : sz += MAXALIGN(sizeof(struct pollfd) * nevents);
384 : : #elif defined(WAIT_USE_WIN32)
385 : : /* need space for the pgwin32_signal_event */
386 : : sz += MAXALIGN(sizeof(HANDLE) * (nevents + 1));
387 : : #endif
388 : :
389 [ + + ]: 150139 : if (resowner != NULL)
390 : 106762 : ResourceOwnerEnlarge(resowner);
391 : :
392 : 150139 : data = (char *) MemoryContextAllocZero(TopMemoryContext, sz);
393 : :
394 : 150139 : set = (WaitEventSet *) data;
395 : 150139 : data += MAXALIGN(sizeof(WaitEventSet));
396 : :
397 : 150139 : set->events = (WaitEvent *) data;
398 : 150139 : data += MAXALIGN(sizeof(WaitEvent) * nevents);
399 : :
400 : : #if defined(WAIT_USE_EPOLL)
401 : 150139 : set->epoll_ret_events = (struct epoll_event *) data;
402 : 150139 : data += MAXALIGN(sizeof(struct epoll_event) * nevents);
403 : : #elif defined(WAIT_USE_KQUEUE)
404 : : set->kqueue_ret_events = (struct kevent *) data;
405 : : data += MAXALIGN(sizeof(struct kevent) * nevents);
406 : : #elif defined(WAIT_USE_POLL)
407 : : set->pollfds = (struct pollfd *) data;
408 : : data += MAXALIGN(sizeof(struct pollfd) * nevents);
409 : : #elif defined(WAIT_USE_WIN32)
410 : : set->handles = (HANDLE) data;
411 : : data += MAXALIGN(sizeof(HANDLE) * nevents);
412 : : #endif
413 : :
414 : 150139 : set->latch = NULL;
415 : 150139 : set->nevents_space = nevents;
416 : 150139 : set->exit_on_postmaster_death = false;
417 : :
418 [ + + ]: 150139 : if (resowner != NULL)
419 : : {
420 : 106762 : ResourceOwnerRememberWaitEventSet(resowner, set);
421 : 106762 : set->owner = resowner;
422 : : }
423 : :
424 : : #if defined(WAIT_USE_EPOLL)
425 [ - + ]: 150139 : if (!AcquireExternalFD())
184 heikki.linnakangas@i 426 [ # # ]:UBC 0 : elog(ERROR, "AcquireExternalFD, for epoll_create1, failed: %m");
184 heikki.linnakangas@i 427 :CBC 150139 : set->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
428 [ - + ]: 150139 : if (set->epoll_fd < 0)
429 : : {
184 heikki.linnakangas@i 430 :UBC 0 : ReleaseExternalFD();
431 [ # # ]: 0 : elog(ERROR, "epoll_create1 failed: %m");
432 : : }
433 : : #elif defined(WAIT_USE_KQUEUE)
434 : : if (!AcquireExternalFD())
435 : : elog(ERROR, "AcquireExternalFD, for kqueue, failed: %m");
436 : : set->kqueue_fd = kqueue();
437 : : if (set->kqueue_fd < 0)
438 : : {
439 : : ReleaseExternalFD();
440 : : elog(ERROR, "kqueue failed: %m");
441 : : }
442 : : if (fcntl(set->kqueue_fd, F_SETFD, FD_CLOEXEC) == -1)
443 : : {
444 : : int save_errno = errno;
445 : :
446 : : close(set->kqueue_fd);
447 : : ReleaseExternalFD();
448 : : errno = save_errno;
449 : : elog(ERROR, "fcntl(F_SETFD) failed on kqueue descriptor: %m");
450 : : }
451 : : set->report_postmaster_not_running = false;
452 : : #elif defined(WAIT_USE_WIN32)
453 : :
454 : : /*
455 : : * To handle signals while waiting, we need to add a win32 specific event.
456 : : * We accounted for the additional event at the top of this routine. See
457 : : * port/win32/signal.c for more details.
458 : : *
459 : : * Note: pgwin32_signal_event should be first to ensure that it will be
460 : : * reported when multiple events are set. We want to guarantee that
461 : : * pending signals are serviced.
462 : : */
463 : : set->handles[0] = pgwin32_signal_event;
464 : : StaticAssertStmt(WSA_INVALID_EVENT == NULL, "");
465 : : #endif
466 : :
184 heikki.linnakangas@i 467 :CBC 150139 : return set;
468 : : }
469 : :
470 : : /*
471 : : * Free a previously created WaitEventSet.
472 : : *
473 : : * Note: preferably, this shouldn't have to free any resources that could be
474 : : * inherited across an exec(). If it did, we'd likely leak those resources in
475 : : * many scenarios. For the epoll case, we ensure that by setting EPOLL_CLOEXEC
476 : : * when the FD is created. For the Windows case, we assume that the handles
477 : : * involved are non-inheritable.
478 : : */
479 : : void
480 : 117756 : FreeWaitEventSet(WaitEventSet *set)
481 : : {
482 [ + + ]: 117756 : if (set->owner)
483 : : {
484 : 106761 : ResourceOwnerForgetWaitEventSet(set->owner, set);
485 : 106761 : set->owner = NULL;
486 : : }
487 : :
488 : : #if defined(WAIT_USE_EPOLL)
489 : 117756 : close(set->epoll_fd);
490 : 117756 : ReleaseExternalFD();
491 : : #elif defined(WAIT_USE_KQUEUE)
492 : : close(set->kqueue_fd);
493 : : ReleaseExternalFD();
494 : : #elif defined(WAIT_USE_WIN32)
495 : : for (WaitEvent *cur_event = set->events;
496 : : cur_event < (set->events + set->nevents);
497 : : cur_event++)
498 : : {
499 : : if (cur_event->events & WL_LATCH_SET)
500 : : {
501 : : /* uses the latch's HANDLE */
502 : : }
503 : : else if (cur_event->events & WL_POSTMASTER_DEATH)
504 : : {
505 : : /* uses PostmasterHandle */
506 : : }
507 : : else
508 : : {
509 : : /* Clean up the event object we created for the socket */
510 : : WSAEventSelect(cur_event->fd, NULL, 0);
511 : : WSACloseEvent(set->handles[cur_event->pos + 1]);
512 : : }
513 : : }
514 : : #endif
515 : :
516 : 117756 : pfree(set);
517 : 117756 : }
518 : :
519 : : /*
520 : : * Free a previously created WaitEventSet in a child process after a fork().
521 : : */
522 : : void
523 : 15771 : FreeWaitEventSetAfterFork(WaitEventSet *set)
524 : : {
525 : : #if defined(WAIT_USE_EPOLL)
526 : 15771 : close(set->epoll_fd);
527 : 15771 : ReleaseExternalFD();
528 : : #elif defined(WAIT_USE_KQUEUE)
529 : : /* kqueues are not normally inherited by child processes */
530 : : ReleaseExternalFD();
531 : : #endif
532 : :
533 : 15771 : pfree(set);
534 : 15771 : }
535 : :
536 : : /* ---
537 : : * Add an event to the set. Possible events are:
538 : : * - WL_LATCH_SET: Wait for the latch to be set
539 : : * - WL_POSTMASTER_DEATH: Wait for postmaster to die
540 : : * - WL_SOCKET_READABLE: Wait for socket to become readable,
541 : : * can be combined in one event with other WL_SOCKET_* events
542 : : * - WL_SOCKET_WRITEABLE: Wait for socket to become writeable,
543 : : * can be combined with other WL_SOCKET_* events
544 : : * - WL_SOCKET_CONNECTED: Wait for socket connection to be established,
545 : : * can be combined with other WL_SOCKET_* events (on non-Windows
546 : : * platforms, this is the same as WL_SOCKET_WRITEABLE)
547 : : * - WL_SOCKET_ACCEPT: Wait for new connection to a server socket,
548 : : * can be combined with other WL_SOCKET_* events (on non-Windows
549 : : * platforms, this is the same as WL_SOCKET_READABLE)
550 : : * - WL_SOCKET_CLOSED: Wait for socket to be closed by remote peer.
551 : : * - WL_EXIT_ON_PM_DEATH: Exit immediately if the postmaster dies
552 : : *
553 : : * Returns the offset in WaitEventSet->events (starting from 0), which can be
554 : : * used to modify previously added wait events using ModifyWaitEvent().
555 : : *
556 : : * In the WL_LATCH_SET case the latch must be owned by the current process,
557 : : * i.e. it must be a process-local latch initialized with InitLatch, or a
558 : : * shared latch associated with the current process by calling OwnLatch.
559 : : *
560 : : * In the WL_SOCKET_READABLE/WRITEABLE/CONNECTED/ACCEPT cases, EOF and error
561 : : * conditions cause the socket to be reported as readable/writable/connected,
562 : : * so that the caller can deal with the condition.
563 : : *
564 : : * The user_data pointer specified here will be set for the events returned
565 : : * by WaitEventSetWait(), allowing to easily associate additional data with
566 : : * events.
567 : : */
568 : : int
569 : 428241 : AddWaitEventToSet(WaitEventSet *set, uint32 events, pgsocket fd, Latch *latch,
570 : : void *user_data)
571 : : {
572 : : WaitEvent *event;
573 : :
574 : : /* not enough space */
575 [ - + ]: 428241 : Assert(set->nevents < set->nevents_space);
576 : :
577 [ + + ]: 428241 : if (events == WL_EXIT_ON_PM_DEATH)
578 : : {
579 : 135918 : events = WL_POSTMASTER_DEATH;
580 : 135918 : set->exit_on_postmaster_death = true;
581 : : }
582 : :
583 [ + + ]: 428241 : if (latch)
584 : : {
585 [ - + ]: 149744 : if (latch->owner_pid != MyProcPid)
184 heikki.linnakangas@i 586 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on a latch owned by another process");
184 heikki.linnakangas@i 587 [ - + ]:CBC 149744 : if (set->latch)
184 heikki.linnakangas@i 588 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on more than one latch");
184 heikki.linnakangas@i 589 [ - + ]:CBC 149744 : if ((events & WL_LATCH_SET) != WL_LATCH_SET)
184 heikki.linnakangas@i 590 [ # # ]:UBC 0 : elog(ERROR, "latch events only support being set");
591 : : }
592 : : else
593 : : {
184 heikki.linnakangas@i 594 [ - + ]:CBC 278497 : if (events & WL_LATCH_SET)
184 heikki.linnakangas@i 595 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on latch without a specified latch");
596 : : }
597 : :
598 : : /* waiting for socket readiness without a socket indicates a bug */
184 heikki.linnakangas@i 599 [ + + - + ]:CBC 428241 : if (fd == PGINVALID_SOCKET && (events & WL_SOCKET_MASK))
184 heikki.linnakangas@i 600 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on socket event without a socket");
601 : :
184 heikki.linnakangas@i 602 :CBC 428241 : event = &set->events[set->nevents];
603 : 428241 : event->pos = set->nevents++;
604 : 428241 : event->fd = fd;
605 : 428241 : event->events = events;
606 : 428241 : event->user_data = user_data;
607 : : #ifdef WIN32
608 : : event->reset = false;
609 : : #endif
610 : :
611 [ + + ]: 428241 : if (events == WL_LATCH_SET)
612 : : {
613 : 149744 : set->latch = latch;
614 : 149744 : set->latch_pos = event->pos;
615 : : #if defined(WAIT_USE_SELF_PIPE)
616 : : event->fd = selfpipe_readfd;
617 : : #elif defined(WAIT_USE_SIGNALFD)
618 : 149744 : event->fd = signal_fd;
619 : : #else
620 : : event->fd = PGINVALID_SOCKET;
621 : : #ifdef WAIT_USE_EPOLL
622 : : return event->pos;
623 : : #endif
624 : : #endif
625 : : }
626 [ + + ]: 278497 : else if (events == WL_POSTMASTER_DEATH)
627 : : {
628 : : #ifndef WIN32
629 : 148274 : event->fd = postmaster_alive_fds[POSTMASTER_FD_WATCH];
630 : : #endif
631 : : }
632 : :
633 : : /* perform wait primitive specific initialization, if needed */
634 : : #if defined(WAIT_USE_EPOLL)
635 : 428241 : WaitEventAdjustEpoll(set, event, EPOLL_CTL_ADD);
636 : : #elif defined(WAIT_USE_KQUEUE)
637 : : WaitEventAdjustKqueue(set, event, 0);
638 : : #elif defined(WAIT_USE_POLL)
639 : : WaitEventAdjustPoll(set, event);
640 : : #elif defined(WAIT_USE_WIN32)
641 : : WaitEventAdjustWin32(set, event);
642 : : #endif
643 : :
644 : 428241 : return event->pos;
645 : : }
646 : :
647 : : /*
648 : : * Change the event mask and, in the WL_LATCH_SET case, the latch associated
649 : : * with the WaitEvent. The latch may be changed to NULL to disable the latch
650 : : * temporarily, and then set back to a latch later.
651 : : *
652 : : * 'pos' is the id returned by AddWaitEventToSet.
653 : : */
654 : : void
655 : 2295482 : ModifyWaitEvent(WaitEventSet *set, int pos, uint32 events, Latch *latch)
656 : : {
657 : : WaitEvent *event;
658 : : #if defined(WAIT_USE_KQUEUE)
659 : : int old_events;
660 : : #endif
661 : :
662 [ - + ]: 2295482 : Assert(pos < set->nevents);
663 : :
664 : 2295482 : event = &set->events[pos];
665 : : #if defined(WAIT_USE_KQUEUE)
666 : : old_events = event->events;
667 : : #endif
668 : :
669 : : /*
670 : : * Allow switching between WL_POSTMASTER_DEATH and WL_EXIT_ON_PM_DEATH.
671 : : *
672 : : * Note that because WL_EXIT_ON_PM_DEATH is mapped to WL_POSTMASTER_DEATH
673 : : * in AddWaitEventToSet(), this needs to be checked before the fast-path
674 : : * below that checks if 'events' has changed.
675 : : */
676 [ + + ]: 2295482 : if (event->events == WL_POSTMASTER_DEATH)
677 : : {
678 [ + + - + ]: 1005828 : if (events != WL_POSTMASTER_DEATH && events != WL_EXIT_ON_PM_DEATH)
184 heikki.linnakangas@i 679 [ # # ]:UBC 0 : elog(ERROR, "cannot remove postmaster death event");
184 heikki.linnakangas@i 680 :CBC 1005828 : set->exit_on_postmaster_death = ((events & WL_EXIT_ON_PM_DEATH) != 0);
681 : 1005828 : return;
682 : : }
683 : :
684 : : /*
685 : : * If neither the event mask nor the associated latch changes, return
686 : : * early. That's an important optimization for some sockets, where
687 : : * ModifyWaitEvent is frequently used to switch from waiting for reads to
688 : : * waiting on writes.
689 : : */
690 [ + + ]: 1289654 : if (events == event->events &&
691 [ + + + + ]: 1269195 : (!(event->events & WL_LATCH_SET) || set->latch == latch))
692 : 1237387 : return;
693 : :
694 [ + + - + ]: 52267 : if (event->events & WL_LATCH_SET && events != event->events)
184 heikki.linnakangas@i 695 [ # # ]:UBC 0 : elog(ERROR, "cannot modify latch event");
696 : :
697 : : /* FIXME: validate event mask */
184 heikki.linnakangas@i 698 :CBC 52267 : event->events = events;
699 : :
700 [ + + ]: 52267 : if (events == WL_LATCH_SET)
701 : : {
702 [ + + - + ]: 31808 : if (latch && latch->owner_pid != MyProcPid)
184 heikki.linnakangas@i 703 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on a latch owned by another process");
184 heikki.linnakangas@i 704 :CBC 31808 : set->latch = latch;
705 : :
706 : : /*
707 : : * On Unix, we don't need to modify the kernel object because the
708 : : * underlying pipe (if there is one) is the same for all latches so we
709 : : * can return immediately. On Windows, we need to update our array of
710 : : * handles, but we leave the old one in place and tolerate spurious
711 : : * wakeups if the latch is disabled.
712 : : */
713 : : #if defined(WAIT_USE_WIN32)
714 : : if (!latch)
715 : : return;
716 : : #else
717 : 31808 : return;
718 : : #endif
719 : : }
720 : :
721 : : #if defined(WAIT_USE_EPOLL)
722 : 20459 : WaitEventAdjustEpoll(set, event, EPOLL_CTL_MOD);
723 : : #elif defined(WAIT_USE_KQUEUE)
724 : : WaitEventAdjustKqueue(set, event, old_events);
725 : : #elif defined(WAIT_USE_POLL)
726 : : WaitEventAdjustPoll(set, event);
727 : : #elif defined(WAIT_USE_WIN32)
728 : : WaitEventAdjustWin32(set, event);
729 : : #endif
730 : : }
731 : :
732 : : #if defined(WAIT_USE_EPOLL)
733 : : /*
734 : : * action can be one of EPOLL_CTL_ADD | EPOLL_CTL_MOD | EPOLL_CTL_DEL
735 : : */
736 : : static void
737 : 448700 : WaitEventAdjustEpoll(WaitEventSet *set, WaitEvent *event, int action)
738 : : {
739 : : struct epoll_event epoll_ev;
740 : : int rc;
741 : :
742 : : /* pointer to our event, returned by epoll_wait */
743 : 448700 : epoll_ev.data.ptr = event;
744 : : /* always wait for errors */
745 : 448700 : epoll_ev.events = EPOLLERR | EPOLLHUP;
746 : :
747 : : /* prepare pollfd entry once */
748 [ + + ]: 448700 : if (event->events == WL_LATCH_SET)
749 : : {
750 [ - + ]: 149744 : Assert(set->latch != NULL);
751 : 149744 : epoll_ev.events |= EPOLLIN;
752 : : }
753 [ + + ]: 298956 : else if (event->events == WL_POSTMASTER_DEATH)
754 : : {
755 : 148274 : epoll_ev.events |= EPOLLIN;
756 : : }
757 : : else
758 : : {
759 [ - + ]: 150682 : Assert(event->fd != PGINVALID_SOCKET);
760 [ - + ]: 150682 : Assert(event->events & (WL_SOCKET_READABLE |
761 : : WL_SOCKET_WRITEABLE |
762 : : WL_SOCKET_CLOSED));
763 : :
764 [ + + ]: 150682 : if (event->events & WL_SOCKET_READABLE)
765 : 136599 : epoll_ev.events |= EPOLLIN;
766 [ + + ]: 150682 : if (event->events & WL_SOCKET_WRITEABLE)
767 : 19093 : epoll_ev.events |= EPOLLOUT;
768 [ - + ]: 150682 : if (event->events & WL_SOCKET_CLOSED)
184 heikki.linnakangas@i 769 :UBC 0 : epoll_ev.events |= EPOLLRDHUP;
770 : : }
771 : :
772 : : /*
773 : : * Even though unused, we also pass epoll_ev as the data argument if
774 : : * EPOLL_CTL_DEL is passed as action. There used to be an epoll bug
775 : : * requiring that, and actually it makes the code simpler...
776 : : */
184 heikki.linnakangas@i 777 :CBC 448700 : rc = epoll_ctl(set->epoll_fd, action, event->fd, &epoll_ev);
778 : :
779 [ - + ]: 448700 : if (rc < 0)
184 heikki.linnakangas@i 780 [ # # ]:UBC 0 : ereport(ERROR,
781 : : (errcode_for_socket_access(),
782 : : errmsg("%s() failed: %m",
783 : : "epoll_ctl")));
184 heikki.linnakangas@i 784 :CBC 448700 : }
785 : : #endif
786 : :
787 : : #if defined(WAIT_USE_POLL)
788 : : static void
789 : : WaitEventAdjustPoll(WaitEventSet *set, WaitEvent *event)
790 : : {
791 : : struct pollfd *pollfd = &set->pollfds[event->pos];
792 : :
793 : : pollfd->revents = 0;
794 : : pollfd->fd = event->fd;
795 : :
796 : : /* prepare pollfd entry once */
797 : : if (event->events == WL_LATCH_SET)
798 : : {
799 : : Assert(set->latch != NULL);
800 : : pollfd->events = POLLIN;
801 : : }
802 : : else if (event->events == WL_POSTMASTER_DEATH)
803 : : {
804 : : pollfd->events = POLLIN;
805 : : }
806 : : else
807 : : {
808 : : Assert(event->events & (WL_SOCKET_READABLE |
809 : : WL_SOCKET_WRITEABLE |
810 : : WL_SOCKET_CLOSED));
811 : : pollfd->events = 0;
812 : : if (event->events & WL_SOCKET_READABLE)
813 : : pollfd->events |= POLLIN;
814 : : if (event->events & WL_SOCKET_WRITEABLE)
815 : : pollfd->events |= POLLOUT;
816 : : #ifdef POLLRDHUP
817 : : if (event->events & WL_SOCKET_CLOSED)
818 : : pollfd->events |= POLLRDHUP;
819 : : #endif
820 : : }
821 : :
822 : : Assert(event->fd != PGINVALID_SOCKET);
823 : : }
824 : : #endif
825 : :
826 : : #if defined(WAIT_USE_KQUEUE)
827 : :
828 : : /*
829 : : * On most BSD family systems, the udata member of struct kevent is of type
830 : : * void *, so we could directly convert to/from WaitEvent *. Unfortunately,
831 : : * NetBSD has it as intptr_t, so here we wallpaper over that difference with
832 : : * an lvalue cast.
833 : : */
834 : : #define AccessWaitEvent(k_ev) (*((WaitEvent **)(&(k_ev)->udata)))
835 : :
836 : : static inline void
837 : : WaitEventAdjustKqueueAdd(struct kevent *k_ev, int filter, int action,
838 : : WaitEvent *event)
839 : : {
840 : : k_ev->ident = event->fd;
841 : : k_ev->filter = filter;
842 : : k_ev->flags = action;
843 : : k_ev->fflags = 0;
844 : : k_ev->data = 0;
845 : : AccessWaitEvent(k_ev) = event;
846 : : }
847 : :
848 : : static inline void
849 : : WaitEventAdjustKqueueAddPostmaster(struct kevent *k_ev, WaitEvent *event)
850 : : {
851 : : /* For now postmaster death can only be added, not removed. */
852 : : k_ev->ident = PostmasterPid;
853 : : k_ev->filter = EVFILT_PROC;
854 : : k_ev->flags = EV_ADD;
855 : : k_ev->fflags = NOTE_EXIT;
856 : : k_ev->data = 0;
857 : : AccessWaitEvent(k_ev) = event;
858 : : }
859 : :
860 : : static inline void
861 : : WaitEventAdjustKqueueAddLatch(struct kevent *k_ev, WaitEvent *event)
862 : : {
863 : : /* For now latch can only be added, not removed. */
864 : : k_ev->ident = SIGURG;
865 : : k_ev->filter = EVFILT_SIGNAL;
866 : : k_ev->flags = EV_ADD;
867 : : k_ev->fflags = 0;
868 : : k_ev->data = 0;
869 : : AccessWaitEvent(k_ev) = event;
870 : : }
871 : :
872 : : /*
873 : : * old_events is the previous event mask, used to compute what has changed.
874 : : */
875 : : static void
876 : : WaitEventAdjustKqueue(WaitEventSet *set, WaitEvent *event, int old_events)
877 : : {
878 : : int rc;
879 : : struct kevent k_ev[2];
880 : : int count = 0;
881 : : bool new_filt_read = false;
882 : : bool old_filt_read = false;
883 : : bool new_filt_write = false;
884 : : bool old_filt_write = false;
885 : :
886 : : if (old_events == event->events)
887 : : return;
888 : :
889 : : Assert(event->events != WL_LATCH_SET || set->latch != NULL);
890 : : Assert(event->events == WL_LATCH_SET ||
891 : : event->events == WL_POSTMASTER_DEATH ||
892 : : (event->events & (WL_SOCKET_READABLE |
893 : : WL_SOCKET_WRITEABLE |
894 : : WL_SOCKET_CLOSED)));
895 : :
896 : : if (event->events == WL_POSTMASTER_DEATH)
897 : : {
898 : : /*
899 : : * Unlike all the other implementations, we detect postmaster death
900 : : * using process notification instead of waiting on the postmaster
901 : : * alive pipe.
902 : : */
903 : : WaitEventAdjustKqueueAddPostmaster(&k_ev[count++], event);
904 : : }
905 : : else if (event->events == WL_LATCH_SET)
906 : : {
907 : : /* We detect latch wakeup using a signal event. */
908 : : WaitEventAdjustKqueueAddLatch(&k_ev[count++], event);
909 : : }
910 : : else
911 : : {
912 : : /*
913 : : * We need to compute the adds and deletes required to get from the
914 : : * old event mask to the new event mask, since kevent treats readable
915 : : * and writable as separate events.
916 : : */
917 : : if (old_events & (WL_SOCKET_READABLE | WL_SOCKET_CLOSED))
918 : : old_filt_read = true;
919 : : if (event->events & (WL_SOCKET_READABLE | WL_SOCKET_CLOSED))
920 : : new_filt_read = true;
921 : : if (old_events & WL_SOCKET_WRITEABLE)
922 : : old_filt_write = true;
923 : : if (event->events & WL_SOCKET_WRITEABLE)
924 : : new_filt_write = true;
925 : : if (old_filt_read && !new_filt_read)
926 : : WaitEventAdjustKqueueAdd(&k_ev[count++], EVFILT_READ, EV_DELETE,
927 : : event);
928 : : else if (!old_filt_read && new_filt_read)
929 : : WaitEventAdjustKqueueAdd(&k_ev[count++], EVFILT_READ, EV_ADD,
930 : : event);
931 : : if (old_filt_write && !new_filt_write)
932 : : WaitEventAdjustKqueueAdd(&k_ev[count++], EVFILT_WRITE, EV_DELETE,
933 : : event);
934 : : else if (!old_filt_write && new_filt_write)
935 : : WaitEventAdjustKqueueAdd(&k_ev[count++], EVFILT_WRITE, EV_ADD,
936 : : event);
937 : : }
938 : :
939 : : /* For WL_SOCKET_READ -> WL_SOCKET_CLOSED, no change needed. */
940 : : if (count == 0)
941 : : return;
942 : :
943 : : Assert(count <= 2);
944 : :
945 : : rc = kevent(set->kqueue_fd, &k_ev[0], count, NULL, 0, NULL);
946 : :
947 : : /*
948 : : * When adding the postmaster's pid, we have to consider that it might
949 : : * already have exited and perhaps even been replaced by another process
950 : : * with the same pid. If so, we have to defer reporting this as an event
951 : : * until the next call to WaitEventSetWaitBlock().
952 : : */
953 : :
954 : : if (rc < 0)
955 : : {
956 : : if (event->events == WL_POSTMASTER_DEATH &&
957 : : (errno == ESRCH || errno == EACCES))
958 : : set->report_postmaster_not_running = true;
959 : : else
960 : : ereport(ERROR,
961 : : (errcode_for_socket_access(),
962 : : errmsg("%s() failed: %m",
963 : : "kevent")));
964 : : }
965 : : else if (event->events == WL_POSTMASTER_DEATH &&
966 : : PostmasterPid != getppid() &&
967 : : !PostmasterIsAlive())
968 : : {
969 : : /*
970 : : * The extra PostmasterIsAliveInternal() check prevents false alarms
971 : : * on systems that give a different value for getppid() while being
972 : : * traced by a debugger.
973 : : */
974 : : set->report_postmaster_not_running = true;
975 : : }
976 : : }
977 : :
978 : : #endif
979 : :
980 : : #if defined(WAIT_USE_WIN32)
981 : : static void
982 : : WaitEventAdjustWin32(WaitEventSet *set, WaitEvent *event)
983 : : {
984 : : HANDLE *handle = &set->handles[event->pos + 1];
985 : :
986 : : if (event->events == WL_LATCH_SET)
987 : : {
988 : : Assert(set->latch != NULL);
989 : : *handle = set->latch->event;
990 : : }
991 : : else if (event->events == WL_POSTMASTER_DEATH)
992 : : {
993 : : *handle = PostmasterHandle;
994 : : }
995 : : else
996 : : {
997 : : int flags = FD_CLOSE; /* always check for errors/EOF */
998 : :
999 : : if (event->events & WL_SOCKET_READABLE)
1000 : : flags |= FD_READ;
1001 : : if (event->events & WL_SOCKET_WRITEABLE)
1002 : : flags |= FD_WRITE;
1003 : : if (event->events & WL_SOCKET_CONNECTED)
1004 : : flags |= FD_CONNECT;
1005 : : if (event->events & WL_SOCKET_ACCEPT)
1006 : : flags |= FD_ACCEPT;
1007 : :
1008 : : if (*handle == WSA_INVALID_EVENT)
1009 : : {
1010 : : *handle = WSACreateEvent();
1011 : : if (*handle == WSA_INVALID_EVENT)
1012 : : elog(ERROR, "failed to create event for socket: error code %d",
1013 : : WSAGetLastError());
1014 : : }
1015 : : if (WSAEventSelect(event->fd, *handle, flags) != 0)
1016 : : elog(ERROR, "failed to set up event for socket: error code %d",
1017 : : WSAGetLastError());
1018 : :
1019 : : Assert(event->fd != PGINVALID_SOCKET);
1020 : : }
1021 : : }
1022 : : #endif
1023 : :
1024 : : /*
1025 : : * Wait for events added to the set to happen, or until the timeout is
1026 : : * reached. At most nevents occurred events are returned.
1027 : : *
1028 : : * If timeout = -1, block until an event occurs; if 0, check sockets for
1029 : : * readiness, but don't block; if > 0, block for at most timeout milliseconds.
1030 : : *
1031 : : * Returns the number of events occurred, or 0 if the timeout was reached.
1032 : : *
1033 : : * Returned events will have the fd, pos, user_data fields set to the
1034 : : * values associated with the registered event.
1035 : : */
1036 : : int
1037 : 1419447 : WaitEventSetWait(WaitEventSet *set, long timeout,
1038 : : WaitEvent *occurred_events, int nevents,
1039 : : uint32 wait_event_info)
1040 : : {
1041 : 1419447 : int returned_events = 0;
1042 : : instr_time start_time;
1043 : : instr_time cur_time;
1044 : 1419447 : long cur_timeout = -1;
1045 : :
1046 [ - + ]: 1419447 : Assert(nevents > 0);
1047 : :
1048 : : /*
1049 : : * Initialize timeout if requested. We must record the current time so
1050 : : * that we can determine the remaining timeout if interrupted.
1051 : : */
1052 [ + + ]: 1419447 : if (timeout >= 0)
1053 : : {
1054 : 256617 : INSTR_TIME_SET_CURRENT(start_time);
1055 [ + - - + ]: 256617 : Assert(timeout >= 0 && timeout <= INT_MAX);
1056 : 256617 : cur_timeout = timeout;
1057 : : }
1058 : : else
1059 : 1162830 : INSTR_TIME_SET_ZERO(start_time);
1060 : :
1061 : 1419447 : pgstat_report_wait_start(wait_event_info);
1062 : :
1063 : : #ifndef WIN32
1064 : 1419447 : waiting = true;
1065 : : #else
1066 : : /* Ensure that signals are serviced even if latch is already set */
1067 : : pgwin32_dispatch_queued_signals();
1068 : : #endif
1069 [ + + ]: 2796014 : while (returned_events == 0)
1070 : : {
1071 : : int rc;
1072 : :
1073 : : /*
1074 : : * Check if the latch is set already first. If so, we either exit
1075 : : * immediately or ask the kernel for further events available right
1076 : : * now without waiting, depending on how many events the caller wants.
1077 : : *
1078 : : * If someone sets the latch between this and the
1079 : : * WaitEventSetWaitBlock() below, the setter will write a byte to the
1080 : : * pipe (or signal us and the signal handler will do that), and the
1081 : : * readiness routine will return immediately.
1082 : : *
1083 : : * On unix, If there's a pending byte in the self pipe, we'll notice
1084 : : * whenever blocking. Only clearing the pipe in that case avoids
1085 : : * having to drain it every time WaitLatchOrSocket() is used. Should
1086 : : * the pipe-buffer fill up we're still ok, because the pipe is in
1087 : : * nonblocking mode. It's unlikely for that to happen, because the
1088 : : * self pipe isn't filled unless we're blocking (waiting = true), or
1089 : : * from inside a signal handler in latch_sigurg_handler().
1090 : : *
1091 : : * On windows, we'll also notice if there's a pending event for the
1092 : : * latch when blocking, but there's no danger of anything filling up,
1093 : : * as "Setting an event that is already set has no effect.".
1094 : : *
1095 : : * Note: we assume that the kernel calls involved in latch management
1096 : : * will provide adequate synchronization on machines with weak memory
1097 : : * ordering, so that we cannot miss seeing is_set if a notification
1098 : : * has already been queued.
1099 : : */
1100 [ + + + + ]: 1463921 : if (set->latch && !set->latch->is_set)
1101 : : {
1102 : : /* about to sleep on a latch */
1103 : 1376515 : set->latch->maybe_sleeping = true;
1104 : 1376515 : pg_memory_barrier();
1105 : : /* and recheck */
1106 : : }
1107 : :
1108 [ + + + + ]: 1463921 : if (set->latch && set->latch->is_set)
1109 : : {
1110 : 87047 : occurred_events->fd = PGINVALID_SOCKET;
1111 : 87047 : occurred_events->pos = set->latch_pos;
1112 : 87047 : occurred_events->user_data =
1113 : 87047 : set->events[set->latch_pos].user_data;
1114 : 87047 : occurred_events->events = WL_LATCH_SET;
1115 : 87047 : occurred_events++;
1116 : 87047 : returned_events++;
1117 : :
1118 : : /* could have been set above */
1119 : 87047 : set->latch->maybe_sleeping = false;
1120 : :
1121 [ + + ]: 87047 : if (returned_events == nevents)
1122 : 62786 : break; /* output buffer full already */
1123 : :
1124 : : /*
1125 : : * Even though we already have an event, we'll poll just once with
1126 : : * zero timeout to see what non-latch events we can fit into the
1127 : : * output buffer at the same time.
1128 : : */
1129 : 24261 : cur_timeout = 0;
1130 : 24261 : timeout = 0;
1131 : : }
1132 : :
1133 : : /*
1134 : : * Wait for events using the readiness primitive chosen at the top of
1135 : : * this file. If -1 is returned, a timeout has occurred, if 0 we have
1136 : : * to retry, everything >= 1 is the number of returned events.
1137 : : */
1138 : 1401135 : rc = WaitEventSetWaitBlock(set, cur_timeout,
1139 : : occurred_events, nevents - returned_events);
1140 : :
1141 [ + + ]: 1401111 : if (set->latch &&
1142 [ + + ]: 1400708 : set->latch->maybe_sleeping)
1143 : 1376447 : set->latch->maybe_sleeping = false;
1144 : :
1145 [ + + ]: 1401111 : if (rc == -1)
1146 : 24544 : break; /* timeout occurred */
1147 : : else
1148 : 1376567 : returned_events += rc;
1149 : :
1150 : : /* If we're not done, update cur_timeout for next iteration */
1151 [ + + + + ]: 1376567 : if (returned_events == 0 && timeout >= 0)
1152 : : {
1153 : 36591 : INSTR_TIME_SET_CURRENT(cur_time);
1154 : 36591 : INSTR_TIME_SUBTRACT(cur_time, start_time);
1155 : 36591 : cur_timeout = timeout - (long) INSTR_TIME_GET_MILLISEC(cur_time);
1156 [ - + ]: 36591 : if (cur_timeout <= 0)
184 heikki.linnakangas@i 1157 :LBC (1) : break;
1158 : : }
1159 : : }
1160 : : #ifndef WIN32
184 heikki.linnakangas@i 1161 :CBC 1419423 : waiting = false;
1162 : : #endif
1163 : :
1164 : 1419423 : pgstat_report_wait_end();
1165 : :
1166 : 1419423 : return returned_events;
1167 : : }
1168 : :
1169 : :
1170 : : #if defined(WAIT_USE_EPOLL)
1171 : :
1172 : : /*
1173 : : * Wait using linux's epoll_wait(2).
1174 : : *
1175 : : * This is the preferable wait method, as several readiness notifications are
1176 : : * delivered, without having to iterate through all of set->events. The return
1177 : : * epoll_event struct contain a pointer to our events, making association
1178 : : * easy.
1179 : : */
1180 : : static inline int
1181 : 1401135 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1182 : : WaitEvent *occurred_events, int nevents)
1183 : : {
1184 : 1401135 : int returned_events = 0;
1185 : : int rc;
1186 : : WaitEvent *cur_event;
1187 : : struct epoll_event *cur_epoll_event;
1188 : :
1189 : : /* Sleep */
1190 : 1401135 : rc = epoll_wait(set->epoll_fd, set->epoll_ret_events,
1191 : 1401135 : Min(nevents, set->nevents_space), cur_timeout);
1192 : :
1193 : : /* Check return code */
1194 [ + + ]: 1401135 : if (rc < 0)
1195 : : {
1196 : : /* EINTR is okay, otherwise complain */
1197 [ - + ]: 34527 : if (errno != EINTR)
1198 : : {
184 heikki.linnakangas@i 1199 :UBC 0 : waiting = false;
1200 [ # # ]: 0 : ereport(ERROR,
1201 : : (errcode_for_socket_access(),
1202 : : errmsg("%s() failed: %m",
1203 : : "epoll_wait")));
1204 : : }
184 heikki.linnakangas@i 1205 :CBC 34527 : return 0;
1206 : : }
1207 [ + + ]: 1366608 : else if (rc == 0)
1208 : : {
1209 : : /* timeout exceeded */
1210 : 24544 : return -1;
1211 : : }
1212 : :
1213 : : /*
1214 : : * At least one event occurred, iterate over the returned epoll events
1215 : : * until they're either all processed, or we've returned all the events
1216 : : * the caller desired.
1217 : : */
1218 : 1342064 : for (cur_epoll_event = set->epoll_ret_events;
1219 [ + + + - ]: 2684141 : cur_epoll_event < (set->epoll_ret_events + rc) &&
1220 : : returned_events < nevents;
1221 : 1342077 : cur_epoll_event++)
1222 : : {
1223 : : /* epoll's data pointer is set to the associated WaitEvent */
1224 : 1342101 : cur_event = (WaitEvent *) cur_epoll_event->data.ptr;
1225 : :
1226 : 1342101 : occurred_events->pos = cur_event->pos;
1227 : 1342101 : occurred_events->user_data = cur_event->user_data;
1228 : 1342101 : occurred_events->events = 0;
1229 : :
1230 [ + + ]: 1342101 : if (cur_event->events == WL_LATCH_SET &&
1231 [ + - ]: 994000 : cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP))
1232 : : {
1233 : : /* Drain the signalfd. */
1234 : 994000 : drain();
1235 : :
1236 [ + - + + : 994000 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
+ + ]
1237 : : {
1238 : 960212 : occurred_events->fd = PGINVALID_SOCKET;
1239 : 960212 : occurred_events->events = WL_LATCH_SET;
1240 : 960212 : occurred_events++;
1241 : 960212 : returned_events++;
1242 : : }
1243 : : }
1244 [ + + ]: 348101 : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1245 [ + - ]: 24 : cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP))
1246 : : {
1247 : : /*
1248 : : * We expect an EPOLLHUP when the remote end is closed, but
1249 : : * because we don't expect the pipe to become readable or to have
1250 : : * any errors either, treat those cases as postmaster death, too.
1251 : : *
1252 : : * Be paranoid about a spurious event signaling the postmaster as
1253 : : * being dead. There have been reports about that happening with
1254 : : * older primitives (select(2) to be specific), and a spurious
1255 : : * WL_POSTMASTER_DEATH event would be painful. Re-checking doesn't
1256 : : * cost much.
1257 : : */
1258 [ + - ]: 24 : if (!PostmasterIsAliveInternal())
1259 : : {
1260 [ + - ]: 24 : if (set->exit_on_postmaster_death)
1261 : 24 : proc_exit(1);
184 heikki.linnakangas@i 1262 :UBC 0 : occurred_events->fd = PGINVALID_SOCKET;
1263 : 0 : occurred_events->events = WL_POSTMASTER_DEATH;
1264 : 0 : occurred_events++;
1265 : 0 : returned_events++;
1266 : : }
1267 : : }
184 heikki.linnakangas@i 1268 [ + - ]:CBC 348077 : else if (cur_event->events & (WL_SOCKET_READABLE |
1269 : : WL_SOCKET_WRITEABLE |
1270 : : WL_SOCKET_CLOSED))
1271 : : {
1272 [ - + ]: 348077 : Assert(cur_event->fd != PGINVALID_SOCKET);
1273 : :
1274 [ + + ]: 348077 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1275 [ + + ]: 333350 : (cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP)))
1276 : : {
1277 : : /* data available in socket, or EOF */
1278 : 326624 : occurred_events->events |= WL_SOCKET_READABLE;
1279 : : }
1280 : :
1281 [ + + ]: 348077 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1282 [ + + ]: 48006 : (cur_epoll_event->events & (EPOLLOUT | EPOLLERR | EPOLLHUP)))
1283 : : {
1284 : : /* writable, or EOF */
1285 : 47715 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1286 : : }
1287 : :
1288 [ - + ]: 348077 : if ((cur_event->events & WL_SOCKET_CLOSED) &&
184 heikki.linnakangas@i 1289 [ # # ]:UBC 0 : (cur_epoll_event->events & (EPOLLRDHUP | EPOLLERR | EPOLLHUP)))
1290 : : {
1291 : : /* remote peer shut down, or error */
1292 : 0 : occurred_events->events |= WL_SOCKET_CLOSED;
1293 : : }
1294 : :
184 heikki.linnakangas@i 1295 [ + - ]:CBC 348077 : if (occurred_events->events != 0)
1296 : : {
1297 : 348077 : occurred_events->fd = cur_event->fd;
1298 : 348077 : occurred_events++;
1299 : 348077 : returned_events++;
1300 : : }
1301 : : }
1302 : : }
1303 : :
1304 : 1342040 : return returned_events;
1305 : : }
1306 : :
1307 : : #elif defined(WAIT_USE_KQUEUE)
1308 : :
1309 : : /*
1310 : : * Wait using kevent(2) on BSD-family systems and macOS.
1311 : : *
1312 : : * For now this mirrors the epoll code, but in future it could modify the fd
1313 : : * set in the same call to kevent as it uses for waiting instead of doing that
1314 : : * with separate system calls.
1315 : : */
1316 : : static int
1317 : : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1318 : : WaitEvent *occurred_events, int nevents)
1319 : : {
1320 : : int returned_events = 0;
1321 : : int rc;
1322 : : WaitEvent *cur_event;
1323 : : struct kevent *cur_kqueue_event;
1324 : : struct timespec timeout;
1325 : : struct timespec *timeout_p;
1326 : :
1327 : : if (cur_timeout < 0)
1328 : : timeout_p = NULL;
1329 : : else
1330 : : {
1331 : : timeout.tv_sec = cur_timeout / 1000;
1332 : : timeout.tv_nsec = (cur_timeout % 1000) * 1000000;
1333 : : timeout_p = &timeout;
1334 : : }
1335 : :
1336 : : /*
1337 : : * Report postmaster events discovered by WaitEventAdjustKqueue() or an
1338 : : * earlier call to WaitEventSetWait().
1339 : : */
1340 : : if (unlikely(set->report_postmaster_not_running))
1341 : : {
1342 : : if (set->exit_on_postmaster_death)
1343 : : proc_exit(1);
1344 : : occurred_events->fd = PGINVALID_SOCKET;
1345 : : occurred_events->events = WL_POSTMASTER_DEATH;
1346 : : return 1;
1347 : : }
1348 : :
1349 : : /* Sleep */
1350 : : rc = kevent(set->kqueue_fd, NULL, 0,
1351 : : set->kqueue_ret_events,
1352 : : Min(nevents, set->nevents_space),
1353 : : timeout_p);
1354 : :
1355 : : /* Check return code */
1356 : : if (rc < 0)
1357 : : {
1358 : : /* EINTR is okay, otherwise complain */
1359 : : if (errno != EINTR)
1360 : : {
1361 : : waiting = false;
1362 : : ereport(ERROR,
1363 : : (errcode_for_socket_access(),
1364 : : errmsg("%s() failed: %m",
1365 : : "kevent")));
1366 : : }
1367 : : return 0;
1368 : : }
1369 : : else if (rc == 0)
1370 : : {
1371 : : /* timeout exceeded */
1372 : : return -1;
1373 : : }
1374 : :
1375 : : /*
1376 : : * At least one event occurred, iterate over the returned kqueue events
1377 : : * until they're either all processed, or we've returned all the events
1378 : : * the caller desired.
1379 : : */
1380 : : for (cur_kqueue_event = set->kqueue_ret_events;
1381 : : cur_kqueue_event < (set->kqueue_ret_events + rc) &&
1382 : : returned_events < nevents;
1383 : : cur_kqueue_event++)
1384 : : {
1385 : : /* kevent's udata points to the associated WaitEvent */
1386 : : cur_event = AccessWaitEvent(cur_kqueue_event);
1387 : :
1388 : : occurred_events->pos = cur_event->pos;
1389 : : occurred_events->user_data = cur_event->user_data;
1390 : : occurred_events->events = 0;
1391 : :
1392 : : if (cur_event->events == WL_LATCH_SET &&
1393 : : cur_kqueue_event->filter == EVFILT_SIGNAL)
1394 : : {
1395 : : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1396 : : {
1397 : : occurred_events->fd = PGINVALID_SOCKET;
1398 : : occurred_events->events = WL_LATCH_SET;
1399 : : occurred_events++;
1400 : : returned_events++;
1401 : : }
1402 : : }
1403 : : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1404 : : cur_kqueue_event->filter == EVFILT_PROC &&
1405 : : (cur_kqueue_event->fflags & NOTE_EXIT) != 0)
1406 : : {
1407 : : /*
1408 : : * The kernel will tell this kqueue object only once about the
1409 : : * exit of the postmaster, so let's remember that for next time so
1410 : : * that we provide level-triggered semantics.
1411 : : */
1412 : : set->report_postmaster_not_running = true;
1413 : :
1414 : : if (set->exit_on_postmaster_death)
1415 : : proc_exit(1);
1416 : : occurred_events->fd = PGINVALID_SOCKET;
1417 : : occurred_events->events = WL_POSTMASTER_DEATH;
1418 : : occurred_events++;
1419 : : returned_events++;
1420 : : }
1421 : : else if (cur_event->events & (WL_SOCKET_READABLE |
1422 : : WL_SOCKET_WRITEABLE |
1423 : : WL_SOCKET_CLOSED))
1424 : : {
1425 : : Assert(cur_event->fd >= 0);
1426 : :
1427 : : if ((cur_event->events & WL_SOCKET_READABLE) &&
1428 : : (cur_kqueue_event->filter == EVFILT_READ))
1429 : : {
1430 : : /* readable, or EOF */
1431 : : occurred_events->events |= WL_SOCKET_READABLE;
1432 : : }
1433 : :
1434 : : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1435 : : (cur_kqueue_event->filter == EVFILT_READ) &&
1436 : : (cur_kqueue_event->flags & EV_EOF))
1437 : : {
1438 : : /* the remote peer has shut down */
1439 : : occurred_events->events |= WL_SOCKET_CLOSED;
1440 : : }
1441 : :
1442 : : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1443 : : (cur_kqueue_event->filter == EVFILT_WRITE))
1444 : : {
1445 : : /* writable, or EOF */
1446 : : occurred_events->events |= WL_SOCKET_WRITEABLE;
1447 : : }
1448 : :
1449 : : if (occurred_events->events != 0)
1450 : : {
1451 : : occurred_events->fd = cur_event->fd;
1452 : : occurred_events++;
1453 : : returned_events++;
1454 : : }
1455 : : }
1456 : : }
1457 : :
1458 : : return returned_events;
1459 : : }
1460 : :
1461 : : #elif defined(WAIT_USE_POLL)
1462 : :
1463 : : /*
1464 : : * Wait using poll(2).
1465 : : *
1466 : : * This allows to receive readiness notifications for several events at once,
1467 : : * but requires iterating through all of set->pollfds.
1468 : : */
1469 : : static inline int
1470 : : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1471 : : WaitEvent *occurred_events, int nevents)
1472 : : {
1473 : : int returned_events = 0;
1474 : : int rc;
1475 : : WaitEvent *cur_event;
1476 : : struct pollfd *cur_pollfd;
1477 : :
1478 : : /* Sleep */
1479 : : rc = poll(set->pollfds, set->nevents, (int) cur_timeout);
1480 : :
1481 : : /* Check return code */
1482 : : if (rc < 0)
1483 : : {
1484 : : /* EINTR is okay, otherwise complain */
1485 : : if (errno != EINTR)
1486 : : {
1487 : : waiting = false;
1488 : : ereport(ERROR,
1489 : : (errcode_for_socket_access(),
1490 : : errmsg("%s() failed: %m",
1491 : : "poll")));
1492 : : }
1493 : : return 0;
1494 : : }
1495 : : else if (rc == 0)
1496 : : {
1497 : : /* timeout exceeded */
1498 : : return -1;
1499 : : }
1500 : :
1501 : : for (cur_event = set->events, cur_pollfd = set->pollfds;
1502 : : cur_event < (set->events + set->nevents) &&
1503 : : returned_events < nevents;
1504 : : cur_event++, cur_pollfd++)
1505 : : {
1506 : : /* no activity on this FD, skip */
1507 : : if (cur_pollfd->revents == 0)
1508 : : continue;
1509 : :
1510 : : occurred_events->pos = cur_event->pos;
1511 : : occurred_events->user_data = cur_event->user_data;
1512 : : occurred_events->events = 0;
1513 : :
1514 : : if (cur_event->events == WL_LATCH_SET &&
1515 : : (cur_pollfd->revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL)))
1516 : : {
1517 : : /* There's data in the self-pipe, clear it. */
1518 : : drain();
1519 : :
1520 : : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1521 : : {
1522 : : occurred_events->fd = PGINVALID_SOCKET;
1523 : : occurred_events->events = WL_LATCH_SET;
1524 : : occurred_events++;
1525 : : returned_events++;
1526 : : }
1527 : : }
1528 : : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1529 : : (cur_pollfd->revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL)))
1530 : : {
1531 : : /*
1532 : : * We expect an POLLHUP when the remote end is closed, but because
1533 : : * we don't expect the pipe to become readable or to have any
1534 : : * errors either, treat those cases as postmaster death, too.
1535 : : *
1536 : : * Be paranoid about a spurious event signaling the postmaster as
1537 : : * being dead. There have been reports about that happening with
1538 : : * older primitives (select(2) to be specific), and a spurious
1539 : : * WL_POSTMASTER_DEATH event would be painful. Re-checking doesn't
1540 : : * cost much.
1541 : : */
1542 : : if (!PostmasterIsAliveInternal())
1543 : : {
1544 : : if (set->exit_on_postmaster_death)
1545 : : proc_exit(1);
1546 : : occurred_events->fd = PGINVALID_SOCKET;
1547 : : occurred_events->events = WL_POSTMASTER_DEATH;
1548 : : occurred_events++;
1549 : : returned_events++;
1550 : : }
1551 : : }
1552 : : else if (cur_event->events & (WL_SOCKET_READABLE |
1553 : : WL_SOCKET_WRITEABLE |
1554 : : WL_SOCKET_CLOSED))
1555 : : {
1556 : : int errflags = POLLHUP | POLLERR | POLLNVAL;
1557 : :
1558 : : Assert(cur_event->fd >= PGINVALID_SOCKET);
1559 : :
1560 : : if ((cur_event->events & WL_SOCKET_READABLE) &&
1561 : : (cur_pollfd->revents & (POLLIN | errflags)))
1562 : : {
1563 : : /* data available in socket, or EOF */
1564 : : occurred_events->events |= WL_SOCKET_READABLE;
1565 : : }
1566 : :
1567 : : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1568 : : (cur_pollfd->revents & (POLLOUT | errflags)))
1569 : : {
1570 : : /* writeable, or EOF */
1571 : : occurred_events->events |= WL_SOCKET_WRITEABLE;
1572 : : }
1573 : :
1574 : : #ifdef POLLRDHUP
1575 : : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1576 : : (cur_pollfd->revents & (POLLRDHUP | errflags)))
1577 : : {
1578 : : /* remote peer closed, or error */
1579 : : occurred_events->events |= WL_SOCKET_CLOSED;
1580 : : }
1581 : : #endif
1582 : :
1583 : : if (occurred_events->events != 0)
1584 : : {
1585 : : occurred_events->fd = cur_event->fd;
1586 : : occurred_events++;
1587 : : returned_events++;
1588 : : }
1589 : : }
1590 : : }
1591 : : return returned_events;
1592 : : }
1593 : :
1594 : : #elif defined(WAIT_USE_WIN32)
1595 : :
1596 : : /*
1597 : : * Wait using Windows' WaitForMultipleObjects(). Each call only "consumes" one
1598 : : * event, so we keep calling until we've filled up our output buffer to match
1599 : : * the behavior of the other implementations.
1600 : : *
1601 : : * https://blogs.msdn.microsoft.com/oldnewthing/20150409-00/?p=44273
1602 : : */
1603 : : static inline int
1604 : : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1605 : : WaitEvent *occurred_events, int nevents)
1606 : : {
1607 : : int returned_events = 0;
1608 : : DWORD rc;
1609 : : WaitEvent *cur_event;
1610 : :
1611 : : /* Reset any wait events that need it */
1612 : : for (cur_event = set->events;
1613 : : cur_event < (set->events + set->nevents);
1614 : : cur_event++)
1615 : : {
1616 : : if (cur_event->reset)
1617 : : {
1618 : : WaitEventAdjustWin32(set, cur_event);
1619 : : cur_event->reset = false;
1620 : : }
1621 : :
1622 : : /*
1623 : : * We associate the socket with a new event handle for each
1624 : : * WaitEventSet. FD_CLOSE is only generated once if the other end
1625 : : * closes gracefully. Therefore we might miss the FD_CLOSE
1626 : : * notification, if it was delivered to another event after we stopped
1627 : : * waiting for it. Close that race by peeking for EOF after setting
1628 : : * up this handle to receive notifications, and before entering the
1629 : : * sleep.
1630 : : *
1631 : : * XXX If we had one event handle for the lifetime of a socket, we
1632 : : * wouldn't need this.
1633 : : */
1634 : : if (cur_event->events & WL_SOCKET_READABLE)
1635 : : {
1636 : : char c;
1637 : : WSABUF buf;
1638 : : DWORD received;
1639 : : DWORD flags;
1640 : :
1641 : : buf.buf = &c;
1642 : : buf.len = 1;
1643 : : flags = MSG_PEEK;
1644 : : if (WSARecv(cur_event->fd, &buf, 1, &received, &flags, NULL, NULL) == 0)
1645 : : {
1646 : : occurred_events->pos = cur_event->pos;
1647 : : occurred_events->user_data = cur_event->user_data;
1648 : : occurred_events->events = WL_SOCKET_READABLE;
1649 : : occurred_events->fd = cur_event->fd;
1650 : : return 1;
1651 : : }
1652 : : }
1653 : :
1654 : : /*
1655 : : * Windows does not guarantee to log an FD_WRITE network event
1656 : : * indicating that more data can be sent unless the previous send()
1657 : : * failed with WSAEWOULDBLOCK. While our caller might well have made
1658 : : * such a call, we cannot assume that here. Therefore, if waiting for
1659 : : * write-ready, force the issue by doing a dummy send(). If the dummy
1660 : : * send() succeeds, assume that the socket is in fact write-ready, and
1661 : : * return immediately. Also, if it fails with something other than
1662 : : * WSAEWOULDBLOCK, return a write-ready indication to let our caller
1663 : : * deal with the error condition.
1664 : : */
1665 : : if (cur_event->events & WL_SOCKET_WRITEABLE)
1666 : : {
1667 : : char c;
1668 : : WSABUF buf;
1669 : : DWORD sent;
1670 : : int r;
1671 : :
1672 : : buf.buf = &c;
1673 : : buf.len = 0;
1674 : :
1675 : : r = WSASend(cur_event->fd, &buf, 1, &sent, 0, NULL, NULL);
1676 : : if (r == 0 || WSAGetLastError() != WSAEWOULDBLOCK)
1677 : : {
1678 : : occurred_events->pos = cur_event->pos;
1679 : : occurred_events->user_data = cur_event->user_data;
1680 : : occurred_events->events = WL_SOCKET_WRITEABLE;
1681 : : occurred_events->fd = cur_event->fd;
1682 : : return 1;
1683 : : }
1684 : : }
1685 : : }
1686 : :
1687 : : /*
1688 : : * Sleep.
1689 : : *
1690 : : * Need to wait for ->nevents + 1, because signal handle is in [0].
1691 : : */
1692 : : rc = WaitForMultipleObjects(set->nevents + 1, set->handles, FALSE,
1693 : : cur_timeout);
1694 : :
1695 : : /* Check return code */
1696 : : if (rc == WAIT_FAILED)
1697 : : elog(ERROR, "WaitForMultipleObjects() failed: error code %lu",
1698 : : GetLastError());
1699 : : else if (rc == WAIT_TIMEOUT)
1700 : : {
1701 : : /* timeout exceeded */
1702 : : return -1;
1703 : : }
1704 : :
1705 : : if (rc == WAIT_OBJECT_0)
1706 : : {
1707 : : /* Service newly-arrived signals */
1708 : : pgwin32_dispatch_queued_signals();
1709 : : return 0; /* retry */
1710 : : }
1711 : :
1712 : : /*
1713 : : * With an offset of one, due to the always present pgwin32_signal_event,
1714 : : * the handle offset directly corresponds to a wait event.
1715 : : */
1716 : : cur_event = (WaitEvent *) &set->events[rc - WAIT_OBJECT_0 - 1];
1717 : :
1718 : : for (;;)
1719 : : {
1720 : : int next_pos;
1721 : : int count;
1722 : :
1723 : : occurred_events->pos = cur_event->pos;
1724 : : occurred_events->user_data = cur_event->user_data;
1725 : : occurred_events->events = 0;
1726 : :
1727 : : if (cur_event->events == WL_LATCH_SET)
1728 : : {
1729 : : /*
1730 : : * We cannot use set->latch->event to reset the fired event if we
1731 : : * aren't waiting on this latch now.
1732 : : */
1733 : : if (!ResetEvent(set->handles[cur_event->pos + 1]))
1734 : : elog(ERROR, "ResetEvent failed: error code %lu", GetLastError());
1735 : :
1736 : : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1737 : : {
1738 : : occurred_events->fd = PGINVALID_SOCKET;
1739 : : occurred_events->events = WL_LATCH_SET;
1740 : : occurred_events++;
1741 : : returned_events++;
1742 : : }
1743 : : }
1744 : : else if (cur_event->events == WL_POSTMASTER_DEATH)
1745 : : {
1746 : : /*
1747 : : * Postmaster apparently died. Since the consequences of falsely
1748 : : * returning WL_POSTMASTER_DEATH could be pretty unpleasant, we
1749 : : * take the trouble to positively verify this with
1750 : : * PostmasterIsAlive(), even though there is no known reason to
1751 : : * think that the event could be falsely set on Windows.
1752 : : */
1753 : : if (!PostmasterIsAliveInternal())
1754 : : {
1755 : : if (set->exit_on_postmaster_death)
1756 : : proc_exit(1);
1757 : : occurred_events->fd = PGINVALID_SOCKET;
1758 : : occurred_events->events = WL_POSTMASTER_DEATH;
1759 : : occurred_events++;
1760 : : returned_events++;
1761 : : }
1762 : : }
1763 : : else if (cur_event->events & WL_SOCKET_MASK)
1764 : : {
1765 : : WSANETWORKEVENTS resEvents;
1766 : : HANDLE handle = set->handles[cur_event->pos + 1];
1767 : :
1768 : : Assert(cur_event->fd);
1769 : :
1770 : : occurred_events->fd = cur_event->fd;
1771 : :
1772 : : ZeroMemory(&resEvents, sizeof(resEvents));
1773 : : if (WSAEnumNetworkEvents(cur_event->fd, handle, &resEvents) != 0)
1774 : : elog(ERROR, "failed to enumerate network events: error code %d",
1775 : : WSAGetLastError());
1776 : : if ((cur_event->events & WL_SOCKET_READABLE) &&
1777 : : (resEvents.lNetworkEvents & FD_READ))
1778 : : {
1779 : : /* data available in socket */
1780 : : occurred_events->events |= WL_SOCKET_READABLE;
1781 : :
1782 : : /*------
1783 : : * WaitForMultipleObjects doesn't guarantee that a read event
1784 : : * will be returned if the latch is set at the same time. Even
1785 : : * if it did, the caller might drop that event expecting it to
1786 : : * reoccur on next call. So, we must force the event to be
1787 : : * reset if this WaitEventSet is used again in order to avoid
1788 : : * an indefinite hang.
1789 : : *
1790 : : * Refer
1791 : : * https://msdn.microsoft.com/en-us/library/windows/desktop/ms741576(v=vs.85).aspx
1792 : : * for the behavior of socket events.
1793 : : *------
1794 : : */
1795 : : cur_event->reset = true;
1796 : : }
1797 : : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1798 : : (resEvents.lNetworkEvents & FD_WRITE))
1799 : : {
1800 : : /* writeable */
1801 : : occurred_events->events |= WL_SOCKET_WRITEABLE;
1802 : : }
1803 : : if ((cur_event->events & WL_SOCKET_CONNECTED) &&
1804 : : (resEvents.lNetworkEvents & FD_CONNECT))
1805 : : {
1806 : : /* connected */
1807 : : occurred_events->events |= WL_SOCKET_CONNECTED;
1808 : : }
1809 : : if ((cur_event->events & WL_SOCKET_ACCEPT) &&
1810 : : (resEvents.lNetworkEvents & FD_ACCEPT))
1811 : : {
1812 : : /* incoming connection could be accepted */
1813 : : occurred_events->events |= WL_SOCKET_ACCEPT;
1814 : : }
1815 : : if (resEvents.lNetworkEvents & FD_CLOSE)
1816 : : {
1817 : : /* EOF/error, so signal all caller-requested socket flags */
1818 : : occurred_events->events |= (cur_event->events & WL_SOCKET_MASK);
1819 : : }
1820 : :
1821 : : if (occurred_events->events != 0)
1822 : : {
1823 : : occurred_events++;
1824 : : returned_events++;
1825 : : }
1826 : : }
1827 : :
1828 : : /* Is the output buffer full? */
1829 : : if (returned_events == nevents)
1830 : : break;
1831 : :
1832 : : /* Have we run out of possible events? */
1833 : : next_pos = cur_event->pos + 1;
1834 : : if (next_pos == set->nevents)
1835 : : break;
1836 : :
1837 : : /*
1838 : : * Poll the rest of the event handles in the array starting at
1839 : : * next_pos being careful to skip over the initial signal handle too.
1840 : : * This time we use a zero timeout.
1841 : : */
1842 : : count = set->nevents - next_pos;
1843 : : rc = WaitForMultipleObjects(count,
1844 : : set->handles + 1 + next_pos,
1845 : : false,
1846 : : 0);
1847 : :
1848 : : /*
1849 : : * We don't distinguish between errors and WAIT_TIMEOUT here because
1850 : : * we already have events to report.
1851 : : */
1852 : : if (rc < WAIT_OBJECT_0 || rc >= WAIT_OBJECT_0 + count)
1853 : : break;
1854 : :
1855 : : /* We have another event to decode. */
1856 : : cur_event = &set->events[next_pos + (rc - WAIT_OBJECT_0)];
1857 : : }
1858 : :
1859 : : return returned_events;
1860 : : }
1861 : : #endif
1862 : :
1863 : : /*
1864 : : * Return whether the current build options can report WL_SOCKET_CLOSED.
1865 : : */
1866 : : bool
1867 : 1067 : WaitEventSetCanReportClosed(void)
1868 : : {
1869 : : #if (defined(WAIT_USE_POLL) && defined(POLLRDHUP)) || \
1870 : : defined(WAIT_USE_EPOLL) || \
1871 : : defined(WAIT_USE_KQUEUE)
1872 : 1067 : return true;
1873 : : #else
1874 : : return false;
1875 : : #endif
1876 : : }
1877 : :
1878 : : /*
1879 : : * Get the number of wait events registered in a given WaitEventSet.
1880 : : */
1881 : : int
1882 : 348 : GetNumRegisteredWaitEvents(WaitEventSet *set)
1883 : : {
1884 : 348 : return set->nevents;
1885 : : }
1886 : :
1887 : : #if defined(WAIT_USE_SELF_PIPE)
1888 : :
1889 : : /*
1890 : : * SetLatch uses SIGURG to wake up the process waiting on the latch.
1891 : : *
1892 : : * Wake up WaitLatch, if we're waiting.
1893 : : */
1894 : : static void
1895 : : latch_sigurg_handler(SIGNAL_ARGS)
1896 : : {
1897 : : if (waiting)
1898 : : sendSelfPipeByte();
1899 : : }
1900 : :
1901 : : /* Send one byte to the self-pipe, to wake up WaitLatch */
1902 : : static void
1903 : : sendSelfPipeByte(void)
1904 : : {
1905 : : int rc;
1906 : : char dummy = 0;
1907 : :
1908 : : retry:
1909 : : rc = write(selfpipe_writefd, &dummy, 1);
1910 : : if (rc < 0)
1911 : : {
1912 : : /* If interrupted by signal, just retry */
1913 : : if (errno == EINTR)
1914 : : goto retry;
1915 : :
1916 : : /*
1917 : : * If the pipe is full, we don't need to retry, the data that's there
1918 : : * already is enough to wake up WaitLatch.
1919 : : */
1920 : : if (errno == EAGAIN || errno == EWOULDBLOCK)
1921 : : return;
1922 : :
1923 : : /*
1924 : : * Oops, the write() failed for some other reason. We might be in a
1925 : : * signal handler, so it's not safe to elog(). We have no choice but
1926 : : * silently ignore the error.
1927 : : */
1928 : : return;
1929 : : }
1930 : : }
1931 : :
1932 : : #endif
1933 : :
1934 : : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
1935 : :
1936 : : /*
1937 : : * Read all available data from self-pipe or signalfd.
1938 : : *
1939 : : * Note: this is only called when waiting = true. If it fails and doesn't
1940 : : * return, it must reset that flag first (though ideally, this will never
1941 : : * happen).
1942 : : */
1943 : : static void
1944 : 994000 : drain(void)
1945 : : {
1946 : : char buf[1024];
1947 : : int rc;
1948 : : int fd;
1949 : :
1950 : : #ifdef WAIT_USE_SELF_PIPE
1951 : : fd = selfpipe_readfd;
1952 : : #else
1953 : 994000 : fd = signal_fd;
1954 : : #endif
1955 : :
1956 : : for (;;)
1957 : : {
1958 : 994000 : rc = read(fd, buf, sizeof(buf));
1959 [ - + ]: 994000 : if (rc < 0)
1960 : : {
184 heikki.linnakangas@i 1961 [ # # # # ]:UBC 0 : if (errno == EAGAIN || errno == EWOULDBLOCK)
1962 : : break; /* the descriptor is empty */
1963 [ # # ]: 0 : else if (errno == EINTR)
1964 : 0 : continue; /* retry */
1965 : : else
1966 : : {
1967 : 0 : waiting = false;
1968 : : #ifdef WAIT_USE_SELF_PIPE
1969 : : elog(ERROR, "read() on self-pipe failed: %m");
1970 : : #else
1971 [ # # ]: 0 : elog(ERROR, "read() on signalfd failed: %m");
1972 : : #endif
1973 : : }
1974 : : }
184 heikki.linnakangas@i 1975 [ - + ]:CBC 994000 : else if (rc == 0)
1976 : : {
184 heikki.linnakangas@i 1977 :UBC 0 : waiting = false;
1978 : : #ifdef WAIT_USE_SELF_PIPE
1979 : : elog(ERROR, "unexpected EOF on self-pipe");
1980 : : #else
1981 [ # # ]: 0 : elog(ERROR, "unexpected EOF on signalfd");
1982 : : #endif
1983 : : }
184 heikki.linnakangas@i 1984 [ + - ]:CBC 994000 : else if (rc < sizeof(buf))
1985 : : {
1986 : : /* we successfully drained the pipe; no need to read() again */
1987 : 994000 : break;
1988 : : }
1989 : : /* else buffer wasn't big enough, so read again */
1990 : : }
1991 : 994000 : }
1992 : :
1993 : : #endif
1994 : :
1995 : : static void
1996 : 1 : ResOwnerReleaseWaitEventSet(Datum res)
1997 : : {
1998 : 1 : WaitEventSet *set = (WaitEventSet *) DatumGetPointer(res);
1999 : :
2000 [ - + ]: 1 : Assert(set->owner != NULL);
2001 : 1 : set->owner = NULL;
2002 : 1 : FreeWaitEventSet(set);
2003 : 1 : }
2004 : :
2005 : : #ifndef WIN32
2006 : : /*
2007 : : * Wake up my process if it's currently sleeping in WaitEventSetWaitBlock()
2008 : : *
2009 : : * NB: be sure to save and restore errno around it. (That's standard practice
2010 : : * in most signal handlers, of course, but we used to omit it in handlers that
2011 : : * only set a flag.) XXX
2012 : : *
2013 : : * NB: this function is called from critical sections and signal handlers so
2014 : : * throwing an error is not a good idea.
2015 : : *
2016 : : * On Windows, Latch uses SetEvent directly and this is not used.
2017 : : */
2018 : : void
2019 : 34771 : WakeupMyProc(void)
2020 : : {
2021 : : #if defined(WAIT_USE_SELF_PIPE)
2022 : : if (waiting)
2023 : : sendSelfPipeByte();
2024 : : #else
2025 [ + - ]: 34771 : if (waiting)
2026 : 34771 : kill(MyProcPid, SIGURG);
2027 : : #endif
2028 : 34771 : }
2029 : :
2030 : : /* Similar to WakeupMyProc, but wake up another process */
2031 : : void
2032 : 1021406 : WakeupOtherProc(int pid)
2033 : : {
2034 : 1021406 : kill(pid, SIGURG);
2035 : 1021406 : }
2036 : : #endif
|
