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 "port/atomics.h"
71 : #include "portability/instr_time.h"
72 : #include "postmaster/postmaster.h"
73 : #include "storage/fd.h"
74 : #include "storage/ipc.h"
75 : #include "storage/pmsignal.h"
76 : #include "storage/latch.h"
77 : #include "storage/waiteventset.h"
78 : #include "utils/memutils.h"
79 : #include "utils/resowner.h"
80 :
81 : /*
82 : * Select the fd readiness primitive to use. Normally the "most modern"
83 : * primitive supported by the OS will be used, but for testing it can be
84 : * useful to manually specify the used primitive. If desired, just add a
85 : * define somewhere before this block.
86 : */
87 : #if defined(WAIT_USE_EPOLL) || defined(WAIT_USE_POLL) || \
88 : defined(WAIT_USE_KQUEUE) || defined(WAIT_USE_WIN32)
89 : /* don't overwrite manual choice */
90 : #elif defined(HAVE_SYS_EPOLL_H)
91 : #define WAIT_USE_EPOLL
92 : #elif defined(HAVE_KQUEUE)
93 : #define WAIT_USE_KQUEUE
94 : #elif defined(HAVE_POLL)
95 : #define WAIT_USE_POLL
96 : #elif WIN32
97 : #define WAIT_USE_WIN32
98 : #else
99 : #error "no wait set implementation available"
100 : #endif
101 :
102 : /*
103 : * By default, we use a self-pipe with poll() and a signalfd with epoll(), if
104 : * available. For testing the choice can also be manually specified.
105 : */
106 : #if defined(WAIT_USE_POLL) || defined(WAIT_USE_EPOLL)
107 : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
108 : /* don't overwrite manual choice */
109 : #elif defined(WAIT_USE_EPOLL) && defined(HAVE_SYS_SIGNALFD_H)
110 : #define WAIT_USE_SIGNALFD
111 : #else
112 : #define WAIT_USE_SELF_PIPE
113 : #endif
114 : #endif
115 :
116 : /* typedef in waiteventset.h */
117 : struct WaitEventSet
118 : {
119 : ResourceOwner owner;
120 :
121 : int nevents; /* number of registered events */
122 : int nevents_space; /* maximum number of events in this set */
123 :
124 : /*
125 : * Array, of nevents_space length, storing the definition of events this
126 : * set is waiting for.
127 : */
128 : WaitEvent *events;
129 :
130 : /*
131 : * If WL_LATCH_SET is specified in any wait event, latch is a pointer to
132 : * said latch, and latch_pos the offset in the ->events array. This is
133 : * useful because we check the state of the latch before performing doing
134 : * syscalls related to waiting.
135 : */
136 : Latch *latch;
137 : int latch_pos;
138 :
139 : /*
140 : * WL_EXIT_ON_PM_DEATH is converted to WL_POSTMASTER_DEATH, but this flag
141 : * is set so that we'll exit immediately if postmaster death is detected,
142 : * instead of returning.
143 : */
144 : bool exit_on_postmaster_death;
145 :
146 : #if defined(WAIT_USE_EPOLL)
147 : int epoll_fd;
148 : /* epoll_wait returns events in a user provided arrays, allocate once */
149 : struct epoll_event *epoll_ret_events;
150 : #elif defined(WAIT_USE_KQUEUE)
151 : int kqueue_fd;
152 : /* kevent returns events in a user provided arrays, allocate once */
153 : struct kevent *kqueue_ret_events;
154 : bool report_postmaster_not_running;
155 : #elif defined(WAIT_USE_POLL)
156 : /* poll expects events to be waited on every poll() call, prepare once */
157 : struct pollfd *pollfds;
158 : #elif defined(WAIT_USE_WIN32)
159 :
160 : /*
161 : * Array of windows events. The first element always contains
162 : * pgwin32_signal_event, so the remaining elements are offset by one (i.e.
163 : * event->pos + 1).
164 : */
165 : HANDLE *handles;
166 : #endif
167 : };
168 :
169 : #ifndef WIN32
170 : /* Are we currently in WaitLatch? The signal handler would like to know. */
171 : static volatile sig_atomic_t waiting = false;
172 : #endif
173 :
174 : #ifdef WAIT_USE_SIGNALFD
175 : /* On Linux, we'll receive SIGURG via a signalfd file descriptor. */
176 : static int signal_fd = -1;
177 : #endif
178 :
179 : #ifdef WAIT_USE_SELF_PIPE
180 : /* Read and write ends of the self-pipe */
181 : static int selfpipe_readfd = -1;
182 : static int selfpipe_writefd = -1;
183 :
184 : /* Process owning the self-pipe --- needed for checking purposes */
185 : static int selfpipe_owner_pid = 0;
186 :
187 : /* Private function prototypes */
188 : static void latch_sigurg_handler(SIGNAL_ARGS);
189 : static void sendSelfPipeByte(void);
190 : #endif
191 :
192 : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
193 : static void drain(void);
194 : #endif
195 :
196 : #if defined(WAIT_USE_EPOLL)
197 : static void WaitEventAdjustEpoll(WaitEventSet *set, WaitEvent *event, int action);
198 : #elif defined(WAIT_USE_KQUEUE)
199 : static void WaitEventAdjustKqueue(WaitEventSet *set, WaitEvent *event, int old_events);
200 : #elif defined(WAIT_USE_POLL)
201 : static void WaitEventAdjustPoll(WaitEventSet *set, WaitEvent *event);
202 : #elif defined(WAIT_USE_WIN32)
203 : static void WaitEventAdjustWin32(WaitEventSet *set, WaitEvent *event);
204 : #endif
205 :
206 : static inline int WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
207 : WaitEvent *occurred_events, int nevents);
208 :
209 : /* ResourceOwner support to hold WaitEventSets */
210 : static void ResOwnerReleaseWaitEventSet(Datum res);
211 :
212 : static const ResourceOwnerDesc wait_event_set_resowner_desc =
213 : {
214 : .name = "WaitEventSet",
215 : .release_phase = RESOURCE_RELEASE_AFTER_LOCKS,
216 : .release_priority = RELEASE_PRIO_WAITEVENTSETS,
217 : .ReleaseResource = ResOwnerReleaseWaitEventSet,
218 : .DebugPrint = NULL
219 : };
220 :
221 : /* Convenience wrappers over ResourceOwnerRemember/Forget */
222 : static inline void
223 167844 : ResourceOwnerRememberWaitEventSet(ResourceOwner owner, WaitEventSet *set)
224 : {
225 167844 : ResourceOwnerRemember(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
226 167844 : }
227 : static inline void
228 167842 : ResourceOwnerForgetWaitEventSet(ResourceOwner owner, WaitEventSet *set)
229 : {
230 167842 : ResourceOwnerForget(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
231 167842 : }
232 :
233 :
234 : /*
235 : * Initialize the process-local wait event infrastructure.
236 : *
237 : * This must be called once during startup of any process that can wait on
238 : * latches, before it issues any InitLatch() or OwnLatch() calls.
239 : */
240 : void
241 48278 : InitializeWaitEventSupport(void)
242 : {
243 : #if defined(WAIT_USE_SELF_PIPE)
244 : int pipefd[2];
245 :
246 : if (IsUnderPostmaster)
247 : {
248 : /*
249 : * We might have inherited connections to a self-pipe created by the
250 : * postmaster. It's critical that child processes create their own
251 : * self-pipes, of course, and we really want them to close the
252 : * inherited FDs for safety's sake.
253 : */
254 : if (selfpipe_owner_pid != 0)
255 : {
256 : /* Assert we go through here but once in a child process */
257 : Assert(selfpipe_owner_pid != MyProcPid);
258 : /* Release postmaster's pipe FDs; ignore any error */
259 : (void) close(selfpipe_readfd);
260 : (void) close(selfpipe_writefd);
261 : /* Clean up, just for safety's sake; we'll set these below */
262 : selfpipe_readfd = selfpipe_writefd = -1;
263 : selfpipe_owner_pid = 0;
264 : /* Keep fd.c's accounting straight */
265 : ReleaseExternalFD();
266 : ReleaseExternalFD();
267 : }
268 : else
269 : {
270 : /*
271 : * Postmaster didn't create a self-pipe ... or else we're in an
272 : * EXEC_BACKEND build, in which case it doesn't matter since the
273 : * postmaster's pipe FDs were closed by the action of FD_CLOEXEC.
274 : * fd.c won't have state to clean up, either.
275 : */
276 : Assert(selfpipe_readfd == -1);
277 : }
278 : }
279 : else
280 : {
281 : /* In postmaster or standalone backend, assert we do this but once */
282 : Assert(selfpipe_readfd == -1);
283 : Assert(selfpipe_owner_pid == 0);
284 : }
285 :
286 : /*
287 : * Set up the self-pipe that allows a signal handler to wake up the
288 : * poll()/epoll_wait() in WaitLatch. Make the write-end non-blocking, so
289 : * that SetLatch won't block if the event has already been set many times
290 : * filling the kernel buffer. Make the read-end non-blocking too, so that
291 : * we can easily clear the pipe by reading until EAGAIN or EWOULDBLOCK.
292 : * Also, make both FDs close-on-exec, since we surely do not want any
293 : * child processes messing with them.
294 : */
295 : if (pipe(pipefd) < 0)
296 : elog(FATAL, "pipe() failed: %m");
297 : if (fcntl(pipefd[0], F_SETFL, O_NONBLOCK) == -1)
298 : elog(FATAL, "fcntl(F_SETFL) failed on read-end of self-pipe: %m");
299 : if (fcntl(pipefd[1], F_SETFL, O_NONBLOCK) == -1)
300 : elog(FATAL, "fcntl(F_SETFL) failed on write-end of self-pipe: %m");
301 : if (fcntl(pipefd[0], F_SETFD, FD_CLOEXEC) == -1)
302 : elog(FATAL, "fcntl(F_SETFD) failed on read-end of self-pipe: %m");
303 : if (fcntl(pipefd[1], F_SETFD, FD_CLOEXEC) == -1)
304 : elog(FATAL, "fcntl(F_SETFD) failed on write-end of self-pipe: %m");
305 :
306 : selfpipe_readfd = pipefd[0];
307 : selfpipe_writefd = pipefd[1];
308 : selfpipe_owner_pid = MyProcPid;
309 :
310 : /* Tell fd.c about these two long-lived FDs */
311 : ReserveExternalFD();
312 : ReserveExternalFD();
313 :
314 : pqsignal(SIGURG, latch_sigurg_handler);
315 : #endif
316 :
317 : #ifdef WAIT_USE_SIGNALFD
318 : sigset_t signalfd_mask;
319 :
320 48278 : if (IsUnderPostmaster)
321 : {
322 : /*
323 : * It would probably be safe to re-use the inherited signalfd since
324 : * signalfds only see the current process's pending signals, but it
325 : * seems less surprising to close it and create our own.
326 : */
327 45968 : if (signal_fd != -1)
328 : {
329 : /* Release postmaster's signal FD; ignore any error */
330 45968 : (void) close(signal_fd);
331 45968 : signal_fd = -1;
332 45968 : ReleaseExternalFD();
333 : }
334 : }
335 :
336 : /* Block SIGURG, because we'll receive it through a signalfd. */
337 48278 : sigaddset(&UnBlockSig, SIGURG);
338 :
339 : /* Set up the signalfd to receive SIGURG notifications. */
340 48278 : sigemptyset(&signalfd_mask);
341 48278 : sigaddset(&signalfd_mask, SIGURG);
342 48278 : signal_fd = signalfd(-1, &signalfd_mask, SFD_NONBLOCK | SFD_CLOEXEC);
343 48278 : if (signal_fd < 0)
344 0 : elog(FATAL, "signalfd() failed");
345 48278 : ReserveExternalFD();
346 : #endif
347 :
348 : #ifdef WAIT_USE_KQUEUE
349 : /* Ignore SIGURG, because we'll receive it via kqueue. */
350 : pqsignal(SIGURG, SIG_IGN);
351 : #endif
352 48278 : }
353 :
354 : /*
355 : * Create a WaitEventSet with space for nevents different events to wait for.
356 : *
357 : * These events can then be efficiently waited upon together, using
358 : * WaitEventSetWait().
359 : *
360 : * The WaitEventSet is tracked by the given 'resowner'. Use NULL for session
361 : * lifetime.
362 : */
363 : WaitEventSet *
364 318386 : CreateWaitEventSet(ResourceOwner resowner, int nevents)
365 : {
366 : WaitEventSet *set;
367 : char *data;
368 318386 : Size sz = 0;
369 :
370 : /*
371 : * Use MAXALIGN size/alignment to guarantee that later uses of memory are
372 : * aligned correctly. E.g. epoll_event might need 8 byte alignment on some
373 : * platforms, but earlier allocations like WaitEventSet and WaitEvent
374 : * might not be sized to guarantee that when purely using sizeof().
375 : */
376 318386 : sz += MAXALIGN(sizeof(WaitEventSet));
377 318386 : sz += MAXALIGN(sizeof(WaitEvent) * nevents);
378 :
379 : #if defined(WAIT_USE_EPOLL)
380 318386 : sz += MAXALIGN(sizeof(struct epoll_event) * nevents);
381 : #elif defined(WAIT_USE_KQUEUE)
382 : sz += MAXALIGN(sizeof(struct kevent) * nevents);
383 : #elif defined(WAIT_USE_POLL)
384 : sz += MAXALIGN(sizeof(struct pollfd) * nevents);
385 : #elif defined(WAIT_USE_WIN32)
386 : /* need space for the pgwin32_signal_event */
387 : sz += MAXALIGN(sizeof(HANDLE) * (nevents + 1));
388 : #endif
389 :
390 318386 : if (resowner != NULL)
391 167844 : ResourceOwnerEnlarge(resowner);
392 :
393 318386 : data = (char *) MemoryContextAllocZero(TopMemoryContext, sz);
394 :
395 318386 : set = (WaitEventSet *) data;
396 318386 : data += MAXALIGN(sizeof(WaitEventSet));
397 :
398 318386 : set->events = (WaitEvent *) data;
399 318386 : data += MAXALIGN(sizeof(WaitEvent) * nevents);
400 :
401 : #if defined(WAIT_USE_EPOLL)
402 318386 : set->epoll_ret_events = (struct epoll_event *) data;
403 318386 : data += MAXALIGN(sizeof(struct epoll_event) * nevents);
404 : #elif defined(WAIT_USE_KQUEUE)
405 : set->kqueue_ret_events = (struct kevent *) data;
406 : data += MAXALIGN(sizeof(struct kevent) * nevents);
407 : #elif defined(WAIT_USE_POLL)
408 : set->pollfds = (struct pollfd *) data;
409 : data += MAXALIGN(sizeof(struct pollfd) * nevents);
410 : #elif defined(WAIT_USE_WIN32)
411 : set->handles = (HANDLE) data;
412 : data += MAXALIGN(sizeof(HANDLE) * nevents);
413 : #endif
414 :
415 318386 : set->latch = NULL;
416 318386 : set->nevents_space = nevents;
417 318386 : set->exit_on_postmaster_death = false;
418 :
419 318386 : if (resowner != NULL)
420 : {
421 167844 : ResourceOwnerRememberWaitEventSet(resowner, set);
422 167844 : set->owner = resowner;
423 : }
424 :
425 : #if defined(WAIT_USE_EPOLL)
426 318386 : if (!AcquireExternalFD())
427 0 : elog(ERROR, "AcquireExternalFD, for epoll_create1, failed: %m");
428 318386 : set->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
429 318386 : if (set->epoll_fd < 0)
430 : {
431 0 : ReleaseExternalFD();
432 0 : elog(ERROR, "epoll_create1 failed: %m");
433 : }
434 : #elif defined(WAIT_USE_KQUEUE)
435 : if (!AcquireExternalFD())
436 : elog(ERROR, "AcquireExternalFD, for kqueue, failed: %m");
437 : set->kqueue_fd = kqueue();
438 : if (set->kqueue_fd < 0)
439 : {
440 : ReleaseExternalFD();
441 : elog(ERROR, "kqueue failed: %m");
442 : }
443 : if (fcntl(set->kqueue_fd, F_SETFD, FD_CLOEXEC) == -1)
444 : {
445 : int save_errno = errno;
446 :
447 : close(set->kqueue_fd);
448 : ReleaseExternalFD();
449 : errno = save_errno;
450 : elog(ERROR, "fcntl(F_SETFD) failed on kqueue descriptor: %m");
451 : }
452 : set->report_postmaster_not_running = false;
453 : #elif defined(WAIT_USE_WIN32)
454 :
455 : /*
456 : * To handle signals while waiting, we need to add a win32 specific event.
457 : * We accounted for the additional event at the top of this routine. See
458 : * port/win32/signal.c for more details.
459 : *
460 : * Note: pgwin32_signal_event should be first to ensure that it will be
461 : * reported when multiple events are set. We want to guarantee that
462 : * pending signals are serviced.
463 : */
464 : set->handles[0] = pgwin32_signal_event;
465 : #endif
466 :
467 318386 : 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 242782 : FreeWaitEventSet(WaitEventSet *set)
481 : {
482 242782 : if (set->owner)
483 : {
484 167842 : ResourceOwnerForgetWaitEventSet(set->owner, set);
485 167842 : set->owner = NULL;
486 : }
487 :
488 : #if defined(WAIT_USE_EPOLL)
489 242782 : close(set->epoll_fd);
490 242782 : 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 242782 : pfree(set);
517 242782 : }
518 :
519 : /*
520 : * Free a previously created WaitEventSet in a child process after a fork().
521 : */
522 : void
523 38776 : FreeWaitEventSetAfterFork(WaitEventSet *set)
524 : {
525 : #if defined(WAIT_USE_EPOLL)
526 38776 : close(set->epoll_fd);
527 38776 : ReleaseExternalFD();
528 : #elif defined(WAIT_USE_KQUEUE)
529 : /* kqueues are not normally inherited by child processes */
530 : ReleaseExternalFD();
531 : #endif
532 :
533 38776 : pfree(set);
534 38776 : }
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 902734 : AddWaitEventToSet(WaitEventSet *set, uint32 events, pgsocket fd, Latch *latch,
570 : void *user_data)
571 : {
572 : WaitEvent *event;
573 :
574 : /* not enough space */
575 : Assert(set->nevents < set->nevents_space);
576 :
577 902734 : if (events == WL_EXIT_ON_PM_DEATH)
578 : {
579 286954 : events = WL_POSTMASTER_DEATH;
580 286954 : set->exit_on_postmaster_death = true;
581 : }
582 :
583 902734 : if (latch)
584 : {
585 318106 : if (latch->owner_pid != MyProcPid)
586 0 : elog(ERROR, "cannot wait on a latch owned by another process");
587 318106 : if (set->latch)
588 0 : elog(ERROR, "cannot wait on more than one latch");
589 318106 : if ((events & WL_LATCH_SET) != WL_LATCH_SET)
590 0 : elog(ERROR, "latch events only support being set");
591 : }
592 : else
593 : {
594 584628 : if (events & WL_LATCH_SET)
595 0 : elog(ERROR, "cannot wait on latch without a specified latch");
596 : }
597 :
598 : /* waiting for socket readiness without a socket indicates a bug */
599 902734 : if (fd == PGINVALID_SOCKET && (events & WL_SOCKET_MASK))
600 0 : elog(ERROR, "cannot wait on socket event without a socket");
601 :
602 902734 : event = &set->events[set->nevents];
603 902734 : event->pos = set->nevents++;
604 902734 : event->fd = fd;
605 902734 : event->events = events;
606 902734 : event->user_data = user_data;
607 : #ifdef WIN32
608 : event->reset = false;
609 : #endif
610 :
611 902734 : if (events == WL_LATCH_SET)
612 : {
613 318106 : set->latch = latch;
614 318106 : set->latch_pos = event->pos;
615 : #if defined(WAIT_USE_SELF_PIPE)
616 : event->fd = selfpipe_readfd;
617 : #elif defined(WAIT_USE_SIGNALFD)
618 318106 : 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 584628 : else if (events == WL_POSTMASTER_DEATH)
627 : {
628 : #ifndef WIN32
629 314308 : 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 902734 : 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 902734 : 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 4586958 : 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 : Assert(pos < set->nevents);
663 :
664 4586958 : 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 4586958 : if (event->events == WL_POSTMASTER_DEATH)
677 : {
678 2059188 : if (events != WL_POSTMASTER_DEATH && events != WL_EXIT_ON_PM_DEATH)
679 0 : elog(ERROR, "cannot remove postmaster death event");
680 2059188 : set->exit_on_postmaster_death = ((events & WL_EXIT_ON_PM_DEATH) != 0);
681 2059188 : 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 2527770 : if (events == event->events &&
691 2498478 : (!(event->events & WL_LATCH_SET) || set->latch == latch))
692 2429166 : return;
693 :
694 98604 : if (event->events & WL_LATCH_SET && events != event->events)
695 0 : elog(ERROR, "cannot modify latch event");
696 :
697 : /* FIXME: validate event mask */
698 98604 : event->events = events;
699 :
700 98604 : if (events == WL_LATCH_SET)
701 : {
702 69312 : if (latch && latch->owner_pid != MyProcPid)
703 0 : elog(ERROR, "cannot wait on a latch owned by another process");
704 69312 : 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 69312 : return;
718 : #endif
719 : }
720 :
721 : #if defined(WAIT_USE_EPOLL)
722 29292 : 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 932026 : 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 932026 : epoll_ev.data.ptr = event;
744 : /* always wait for errors */
745 932026 : epoll_ev.events = EPOLLERR | EPOLLHUP;
746 :
747 : /* prepare pollfd entry once */
748 932026 : if (event->events == WL_LATCH_SET)
749 : {
750 : Assert(set->latch != NULL);
751 318106 : epoll_ev.events |= EPOLLIN;
752 : }
753 613920 : else if (event->events == WL_POSTMASTER_DEATH)
754 : {
755 314308 : epoll_ev.events |= EPOLLIN;
756 : }
757 : else
758 : {
759 : Assert(event->fd != PGINVALID_SOCKET);
760 : Assert(event->events & (WL_SOCKET_READABLE |
761 : WL_SOCKET_WRITEABLE |
762 : WL_SOCKET_CLOSED));
763 :
764 299612 : if (event->events & WL_SOCKET_READABLE)
765 268688 : epoll_ev.events |= EPOLLIN;
766 299612 : if (event->events & WL_SOCKET_WRITEABLE)
767 37216 : epoll_ev.events |= EPOLLOUT;
768 299612 : if (event->events & WL_SOCKET_CLOSED)
769 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 : */
777 932026 : rc = epoll_ctl(set->epoll_fd, action, event->fd, &epoll_ev);
778 :
779 932026 : if (rc < 0)
780 0 : ereport(ERROR,
781 : (errcode_for_socket_access(),
782 : errmsg("%s() failed: %m",
783 : "epoll_ctl")));
784 932026 : }
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 : StaticAssertDecl(WSA_INVALID_EVENT == NULL, "");
982 :
983 : static void
984 : WaitEventAdjustWin32(WaitEventSet *set, WaitEvent *event)
985 : {
986 : HANDLE *handle = &set->handles[event->pos + 1];
987 :
988 : if (event->events == WL_LATCH_SET)
989 : {
990 : Assert(set->latch != NULL);
991 : *handle = set->latch->event;
992 : }
993 : else if (event->events == WL_POSTMASTER_DEATH)
994 : {
995 : *handle = PostmasterHandle;
996 : }
997 : else
998 : {
999 : int flags = FD_CLOSE; /* always check for errors/EOF */
1000 :
1001 : if (event->events & WL_SOCKET_READABLE)
1002 : flags |= FD_READ;
1003 : if (event->events & WL_SOCKET_WRITEABLE)
1004 : flags |= FD_WRITE;
1005 : if (event->events & WL_SOCKET_CONNECTED)
1006 : flags |= FD_CONNECT;
1007 : if (event->events & WL_SOCKET_ACCEPT)
1008 : flags |= FD_ACCEPT;
1009 :
1010 : if (*handle == WSA_INVALID_EVENT)
1011 : {
1012 : *handle = WSACreateEvent();
1013 : if (*handle == WSA_INVALID_EVENT)
1014 : elog(ERROR, "failed to create event for socket: error code %d",
1015 : WSAGetLastError());
1016 : }
1017 : if (WSAEventSelect(event->fd, *handle, flags) != 0)
1018 : elog(ERROR, "failed to set up event for socket: error code %d",
1019 : WSAGetLastError());
1020 :
1021 : Assert(event->fd != PGINVALID_SOCKET);
1022 : }
1023 : }
1024 : #endif
1025 :
1026 : /*
1027 : * Wait for events added to the set to happen, or until the timeout is
1028 : * reached. At most nevents occurred events are returned.
1029 : *
1030 : * If timeout = -1, block until an event occurs; if 0, check sockets for
1031 : * readiness, but don't block; if > 0, block for at most timeout milliseconds.
1032 : *
1033 : * Returns the number of events occurred, or 0 if the timeout was reached.
1034 : *
1035 : * Returned events will have the fd, pos, user_data fields set to the
1036 : * values associated with the registered event.
1037 : */
1038 : int
1039 2955968 : WaitEventSetWait(WaitEventSet *set, long timeout,
1040 : WaitEvent *occurred_events, int nevents,
1041 : uint32 wait_event_info)
1042 : {
1043 2955968 : int returned_events = 0;
1044 : instr_time start_time;
1045 : instr_time cur_time;
1046 2955968 : long cur_timeout = -1;
1047 :
1048 : Assert(nevents > 0);
1049 :
1050 : /*
1051 : * Initialize timeout if requested. We must record the current time so
1052 : * that we can determine the remaining timeout if interrupted.
1053 : */
1054 2955968 : if (timeout >= 0)
1055 : {
1056 694882 : INSTR_TIME_SET_CURRENT(start_time);
1057 : Assert(timeout >= 0 && timeout <= INT_MAX);
1058 694882 : cur_timeout = timeout;
1059 : }
1060 : else
1061 2261086 : INSTR_TIME_SET_ZERO(start_time);
1062 :
1063 2955968 : pgstat_report_wait_start(wait_event_info);
1064 :
1065 : #ifndef WIN32
1066 2955968 : waiting = true;
1067 : #else
1068 : /* Ensure that signals are serviced even if latch is already set */
1069 : pgwin32_dispatch_queued_signals();
1070 : #endif
1071 5978362 : while (returned_events == 0)
1072 : {
1073 : int rc;
1074 :
1075 : /*
1076 : * Check if the latch is set already first. If so, we either exit
1077 : * immediately or ask the kernel for further events available right
1078 : * now without waiting, depending on how many events the caller wants.
1079 : *
1080 : * If someone sets the latch between this and the
1081 : * WaitEventSetWaitBlock() below, the setter will write a byte to the
1082 : * pipe (or signal us and the signal handler will do that), and the
1083 : * readiness routine will return immediately.
1084 : *
1085 : * On unix, If there's a pending byte in the self pipe, we'll notice
1086 : * whenever blocking. Only clearing the pipe in that case avoids
1087 : * having to drain it every time WaitLatchOrSocket() is used. Should
1088 : * the pipe-buffer fill up we're still ok, because the pipe is in
1089 : * nonblocking mode. It's unlikely for that to happen, because the
1090 : * self pipe isn't filled unless we're blocking (waiting = true), or
1091 : * from inside a signal handler in latch_sigurg_handler().
1092 : *
1093 : * On windows, we'll also notice if there's a pending event for the
1094 : * latch when blocking, but there's no danger of anything filling up,
1095 : * as "Setting an event that is already set has no effect.".
1096 : *
1097 : * Note: we assume that the kernel calls involved in latch management
1098 : * will provide adequate synchronization on machines with weak memory
1099 : * ordering, so that we cannot miss seeing is_set if a notification
1100 : * has already been queued.
1101 : */
1102 3225112 : if (set->latch && !set->latch->is_set)
1103 : {
1104 : /* about to sleep on a latch */
1105 2871844 : set->latch->maybe_sleeping = true;
1106 2871844 : pg_memory_barrier();
1107 : /* and recheck */
1108 : }
1109 :
1110 3225112 : if (set->latch && set->latch->is_set)
1111 : {
1112 352600 : occurred_events->fd = PGINVALID_SOCKET;
1113 352600 : occurred_events->pos = set->latch_pos;
1114 352600 : occurred_events->user_data =
1115 352600 : set->events[set->latch_pos].user_data;
1116 352600 : occurred_events->events = WL_LATCH_SET;
1117 352600 : occurred_events++;
1118 352600 : returned_events++;
1119 :
1120 : /* could have been set above */
1121 352600 : set->latch->maybe_sleeping = false;
1122 :
1123 352600 : if (returned_events == nevents)
1124 140102 : break; /* output buffer full already */
1125 :
1126 : /*
1127 : * Even though we already have an event, we'll poll just once with
1128 : * zero timeout to see what non-latch events we can fit into the
1129 : * output buffer at the same time.
1130 : */
1131 212498 : cur_timeout = 0;
1132 212498 : timeout = 0;
1133 : }
1134 :
1135 : /*
1136 : * Wait for events using the readiness primitive chosen at the top of
1137 : * this file. If -1 is returned, a timeout has occurred, if 0 we have
1138 : * to retry, everything >= 1 is the number of returned events.
1139 : */
1140 3085010 : rc = WaitEventSetWaitBlock(set, cur_timeout,
1141 : occurred_events, nevents - returned_events);
1142 :
1143 3084942 : if (set->latch &&
1144 3084196 : set->latch->maybe_sleeping)
1145 2871698 : set->latch->maybe_sleeping = false;
1146 :
1147 3084942 : if (rc == -1)
1148 62544 : break; /* timeout occurred */
1149 : else
1150 3022398 : returned_events += rc;
1151 :
1152 : /* If we're not done, update cur_timeout for next iteration */
1153 3022398 : if (returned_events == 0 && timeout >= 0)
1154 : {
1155 249958 : INSTR_TIME_SET_CURRENT(cur_time);
1156 249958 : INSTR_TIME_SUBTRACT(cur_time, start_time);
1157 249958 : cur_timeout = timeout - (long) INSTR_TIME_GET_MILLISEC(cur_time);
1158 249958 : if (cur_timeout <= 0)
1159 4 : break;
1160 : }
1161 : }
1162 : #ifndef WIN32
1163 2955900 : waiting = false;
1164 : #endif
1165 :
1166 2955900 : pgstat_report_wait_end();
1167 :
1168 2955900 : return returned_events;
1169 : }
1170 :
1171 :
1172 : #if defined(WAIT_USE_EPOLL)
1173 :
1174 : /*
1175 : * Wait using linux's epoll_wait(2).
1176 : *
1177 : * This is the preferable wait method, as several readiness notifications are
1178 : * delivered, without having to iterate through all of set->events. The return
1179 : * epoll_event struct contain a pointer to our events, making association
1180 : * easy.
1181 : */
1182 : static inline int
1183 3085010 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1184 : WaitEvent *occurred_events, int nevents)
1185 : {
1186 3085010 : int returned_events = 0;
1187 : int rc;
1188 : WaitEvent *cur_event;
1189 : struct epoll_event *cur_epoll_event;
1190 :
1191 : /* Sleep */
1192 3085010 : rc = epoll_wait(set->epoll_fd, set->epoll_ret_events,
1193 3085010 : Min(nevents, set->nevents_space), cur_timeout);
1194 :
1195 : /* Check return code */
1196 3085010 : if (rc < 0)
1197 : {
1198 : /* EINTR is okay, otherwise complain */
1199 244084 : if (errno != EINTR)
1200 : {
1201 0 : waiting = false;
1202 0 : ereport(ERROR,
1203 : (errcode_for_socket_access(),
1204 : errmsg("%s() failed: %m",
1205 : "epoll_wait")));
1206 : }
1207 244084 : return 0;
1208 : }
1209 2840926 : else if (rc == 0)
1210 : {
1211 : /* timeout exceeded */
1212 62544 : return -1;
1213 : }
1214 :
1215 : /*
1216 : * At least one event occurred, iterate over the returned epoll events
1217 : * until they're either all processed, or we've returned all the events
1218 : * the caller desired.
1219 : */
1220 2778382 : for (cur_epoll_event = set->epoll_ret_events;
1221 5556788 : cur_epoll_event < (set->epoll_ret_events + rc) &&
1222 : returned_events < nevents;
1223 2778406 : cur_epoll_event++)
1224 : {
1225 : /* epoll's data pointer is set to the associated WaitEvent */
1226 2778474 : cur_event = (WaitEvent *) cur_epoll_event->data.ptr;
1227 :
1228 2778474 : occurred_events->pos = cur_event->pos;
1229 2778474 : occurred_events->user_data = cur_event->user_data;
1230 2778474 : occurred_events->events = 0;
1231 :
1232 2778474 : if (cur_event->events == WL_LATCH_SET &&
1233 2181190 : cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP))
1234 : {
1235 : /* Drain the signalfd. */
1236 2181190 : drain();
1237 :
1238 2181190 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1239 : {
1240 1945278 : occurred_events->fd = PGINVALID_SOCKET;
1241 1945278 : occurred_events->events = WL_LATCH_SET;
1242 1945278 : occurred_events++;
1243 1945278 : returned_events++;
1244 : }
1245 : }
1246 597284 : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1247 68 : cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP))
1248 : {
1249 : /*
1250 : * We expect an EPOLLHUP when the remote end is closed, but
1251 : * because we don't expect the pipe to become readable or to have
1252 : * any errors either, treat those cases as postmaster death, too.
1253 : *
1254 : * Be paranoid about a spurious event signaling the postmaster as
1255 : * being dead. There have been reports about that happening with
1256 : * older primitives (select(2) to be specific), and a spurious
1257 : * WL_POSTMASTER_DEATH event would be painful. Re-checking doesn't
1258 : * cost much.
1259 : */
1260 68 : if (!PostmasterIsAliveInternal())
1261 : {
1262 68 : if (set->exit_on_postmaster_death)
1263 68 : proc_exit(1);
1264 0 : occurred_events->fd = PGINVALID_SOCKET;
1265 0 : occurred_events->events = WL_POSTMASTER_DEATH;
1266 0 : occurred_events++;
1267 0 : returned_events++;
1268 : }
1269 : }
1270 597216 : else if (cur_event->events & (WL_SOCKET_READABLE |
1271 : WL_SOCKET_WRITEABLE |
1272 : WL_SOCKET_CLOSED))
1273 : {
1274 : Assert(cur_event->fd != PGINVALID_SOCKET);
1275 :
1276 597216 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1277 569904 : (cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP)))
1278 : {
1279 : /* data available in socket, or EOF */
1280 540950 : occurred_events->events |= WL_SOCKET_READABLE;
1281 : }
1282 :
1283 597216 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1284 65668 : (cur_epoll_event->events & (EPOLLOUT | EPOLLERR | EPOLLHUP)))
1285 : {
1286 : /* writable, or EOF */
1287 65026 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1288 : }
1289 :
1290 597216 : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1291 0 : (cur_epoll_event->events & (EPOLLRDHUP | EPOLLERR | EPOLLHUP)))
1292 : {
1293 : /* remote peer shut down, or error */
1294 0 : occurred_events->events |= WL_SOCKET_CLOSED;
1295 : }
1296 :
1297 597216 : if (occurred_events->events != 0)
1298 : {
1299 597216 : occurred_events->fd = cur_event->fd;
1300 597216 : occurred_events++;
1301 597216 : returned_events++;
1302 : }
1303 : }
1304 : }
1305 :
1306 2778314 : return returned_events;
1307 : }
1308 :
1309 : #elif defined(WAIT_USE_KQUEUE)
1310 :
1311 : /*
1312 : * Wait using kevent(2) on BSD-family systems and macOS.
1313 : *
1314 : * For now this mirrors the epoll code, but in future it could modify the fd
1315 : * set in the same call to kevent as it uses for waiting instead of doing that
1316 : * with separate system calls.
1317 : */
1318 : static int
1319 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1320 : WaitEvent *occurred_events, int nevents)
1321 : {
1322 : int returned_events = 0;
1323 : int rc;
1324 : WaitEvent *cur_event;
1325 : struct kevent *cur_kqueue_event;
1326 : struct timespec timeout;
1327 : struct timespec *timeout_p;
1328 :
1329 : if (cur_timeout < 0)
1330 : timeout_p = NULL;
1331 : else
1332 : {
1333 : timeout.tv_sec = cur_timeout / 1000;
1334 : timeout.tv_nsec = (cur_timeout % 1000) * 1000000;
1335 : timeout_p = &timeout;
1336 : }
1337 :
1338 : /*
1339 : * Report postmaster events discovered by WaitEventAdjustKqueue() or an
1340 : * earlier call to WaitEventSetWait().
1341 : */
1342 : if (unlikely(set->report_postmaster_not_running))
1343 : {
1344 : if (set->exit_on_postmaster_death)
1345 : proc_exit(1);
1346 : occurred_events->fd = PGINVALID_SOCKET;
1347 : occurred_events->events = WL_POSTMASTER_DEATH;
1348 : return 1;
1349 : }
1350 :
1351 : /* Sleep */
1352 : rc = kevent(set->kqueue_fd, NULL, 0,
1353 : set->kqueue_ret_events,
1354 : Min(nevents, set->nevents_space),
1355 : timeout_p);
1356 :
1357 : /* Check return code */
1358 : if (rc < 0)
1359 : {
1360 : /* EINTR is okay, otherwise complain */
1361 : if (errno != EINTR)
1362 : {
1363 : waiting = false;
1364 : ereport(ERROR,
1365 : (errcode_for_socket_access(),
1366 : errmsg("%s() failed: %m",
1367 : "kevent")));
1368 : }
1369 : return 0;
1370 : }
1371 : else if (rc == 0)
1372 : {
1373 : /* timeout exceeded */
1374 : return -1;
1375 : }
1376 :
1377 : /*
1378 : * At least one event occurred, iterate over the returned kqueue events
1379 : * until they're either all processed, or we've returned all the events
1380 : * the caller desired.
1381 : */
1382 : for (cur_kqueue_event = set->kqueue_ret_events;
1383 : cur_kqueue_event < (set->kqueue_ret_events + rc) &&
1384 : returned_events < nevents;
1385 : cur_kqueue_event++)
1386 : {
1387 : /* kevent's udata points to the associated WaitEvent */
1388 : cur_event = AccessWaitEvent(cur_kqueue_event);
1389 :
1390 : occurred_events->pos = cur_event->pos;
1391 : occurred_events->user_data = cur_event->user_data;
1392 : occurred_events->events = 0;
1393 :
1394 : if (cur_event->events == WL_LATCH_SET &&
1395 : cur_kqueue_event->filter == EVFILT_SIGNAL)
1396 : {
1397 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1398 : {
1399 : occurred_events->fd = PGINVALID_SOCKET;
1400 : occurred_events->events = WL_LATCH_SET;
1401 : occurred_events++;
1402 : returned_events++;
1403 : }
1404 : }
1405 : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1406 : cur_kqueue_event->filter == EVFILT_PROC &&
1407 : (cur_kqueue_event->fflags & NOTE_EXIT) != 0)
1408 : {
1409 : /*
1410 : * The kernel will tell this kqueue object only once about the
1411 : * exit of the postmaster, so let's remember that for next time so
1412 : * that we provide level-triggered semantics.
1413 : */
1414 : set->report_postmaster_not_running = true;
1415 :
1416 : if (set->exit_on_postmaster_death)
1417 : proc_exit(1);
1418 : occurred_events->fd = PGINVALID_SOCKET;
1419 : occurred_events->events = WL_POSTMASTER_DEATH;
1420 : occurred_events++;
1421 : returned_events++;
1422 : }
1423 : else if (cur_event->events & (WL_SOCKET_READABLE |
1424 : WL_SOCKET_WRITEABLE |
1425 : WL_SOCKET_CLOSED))
1426 : {
1427 : Assert(cur_event->fd >= 0);
1428 :
1429 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1430 : (cur_kqueue_event->filter == EVFILT_READ))
1431 : {
1432 : /* readable, or EOF */
1433 : occurred_events->events |= WL_SOCKET_READABLE;
1434 : }
1435 :
1436 : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1437 : (cur_kqueue_event->filter == EVFILT_READ) &&
1438 : (cur_kqueue_event->flags & EV_EOF))
1439 : {
1440 : /* the remote peer has shut down */
1441 : occurred_events->events |= WL_SOCKET_CLOSED;
1442 : }
1443 :
1444 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1445 : (cur_kqueue_event->filter == EVFILT_WRITE))
1446 : {
1447 : /* writable, or EOF */
1448 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1449 : }
1450 :
1451 : if (occurred_events->events != 0)
1452 : {
1453 : occurred_events->fd = cur_event->fd;
1454 : occurred_events++;
1455 : returned_events++;
1456 : }
1457 : }
1458 : }
1459 :
1460 : return returned_events;
1461 : }
1462 :
1463 : #elif defined(WAIT_USE_POLL)
1464 :
1465 : /*
1466 : * Wait using poll(2).
1467 : *
1468 : * This allows to receive readiness notifications for several events at once,
1469 : * but requires iterating through all of set->pollfds.
1470 : */
1471 : static inline int
1472 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1473 : WaitEvent *occurred_events, int nevents)
1474 : {
1475 : int returned_events = 0;
1476 : int rc;
1477 : WaitEvent *cur_event;
1478 : struct pollfd *cur_pollfd;
1479 :
1480 : /* Sleep */
1481 : rc = poll(set->pollfds, set->nevents, cur_timeout);
1482 :
1483 : /* Check return code */
1484 : if (rc < 0)
1485 : {
1486 : /* EINTR is okay, otherwise complain */
1487 : if (errno != EINTR)
1488 : {
1489 : waiting = false;
1490 : ereport(ERROR,
1491 : (errcode_for_socket_access(),
1492 : errmsg("%s() failed: %m",
1493 : "poll")));
1494 : }
1495 : return 0;
1496 : }
1497 : else if (rc == 0)
1498 : {
1499 : /* timeout exceeded */
1500 : return -1;
1501 : }
1502 :
1503 : for (cur_event = set->events, cur_pollfd = set->pollfds;
1504 : cur_event < (set->events + set->nevents) &&
1505 : returned_events < nevents;
1506 : cur_event++, cur_pollfd++)
1507 : {
1508 : /* no activity on this FD, skip */
1509 : if (cur_pollfd->revents == 0)
1510 : continue;
1511 :
1512 : occurred_events->pos = cur_event->pos;
1513 : occurred_events->user_data = cur_event->user_data;
1514 : occurred_events->events = 0;
1515 :
1516 : if (cur_event->events == WL_LATCH_SET &&
1517 : (cur_pollfd->revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL)))
1518 : {
1519 : /* There's data in the self-pipe, clear it. */
1520 : drain();
1521 :
1522 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1523 : {
1524 : occurred_events->fd = PGINVALID_SOCKET;
1525 : occurred_events->events = WL_LATCH_SET;
1526 : occurred_events++;
1527 : returned_events++;
1528 : }
1529 : }
1530 : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1531 : (cur_pollfd->revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL)))
1532 : {
1533 : /*
1534 : * We expect an POLLHUP when the remote end is closed, but because
1535 : * we don't expect the pipe to become readable or to have any
1536 : * errors either, treat those cases as postmaster death, too.
1537 : *
1538 : * Be paranoid about a spurious event signaling the postmaster as
1539 : * being dead. There have been reports about that happening with
1540 : * older primitives (select(2) to be specific), and a spurious
1541 : * WL_POSTMASTER_DEATH event would be painful. Re-checking doesn't
1542 : * cost much.
1543 : */
1544 : if (!PostmasterIsAliveInternal())
1545 : {
1546 : if (set->exit_on_postmaster_death)
1547 : proc_exit(1);
1548 : occurred_events->fd = PGINVALID_SOCKET;
1549 : occurred_events->events = WL_POSTMASTER_DEATH;
1550 : occurred_events++;
1551 : returned_events++;
1552 : }
1553 : }
1554 : else if (cur_event->events & (WL_SOCKET_READABLE |
1555 : WL_SOCKET_WRITEABLE |
1556 : WL_SOCKET_CLOSED))
1557 : {
1558 : int errflags = POLLHUP | POLLERR | POLLNVAL;
1559 :
1560 : Assert(cur_event->fd >= PGINVALID_SOCKET);
1561 :
1562 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1563 : (cur_pollfd->revents & (POLLIN | errflags)))
1564 : {
1565 : /* data available in socket, or EOF */
1566 : occurred_events->events |= WL_SOCKET_READABLE;
1567 : }
1568 :
1569 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1570 : (cur_pollfd->revents & (POLLOUT | errflags)))
1571 : {
1572 : /* writeable, or EOF */
1573 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1574 : }
1575 :
1576 : #ifdef POLLRDHUP
1577 : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1578 : (cur_pollfd->revents & (POLLRDHUP | errflags)))
1579 : {
1580 : /* remote peer closed, or error */
1581 : occurred_events->events |= WL_SOCKET_CLOSED;
1582 : }
1583 : #endif
1584 :
1585 : if (occurred_events->events != 0)
1586 : {
1587 : occurred_events->fd = cur_event->fd;
1588 : occurred_events++;
1589 : returned_events++;
1590 : }
1591 : }
1592 : }
1593 : return returned_events;
1594 : }
1595 :
1596 : #elif defined(WAIT_USE_WIN32)
1597 :
1598 : /*
1599 : * Wait using Windows' WaitForMultipleObjects(). Each call only "consumes" one
1600 : * event, so we keep calling until we've filled up our output buffer to match
1601 : * the behavior of the other implementations.
1602 : *
1603 : * https://blogs.msdn.microsoft.com/oldnewthing/20150409-00/?p=44273
1604 : */
1605 : static inline int
1606 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1607 : WaitEvent *occurred_events, int nevents)
1608 : {
1609 : int returned_events = 0;
1610 : DWORD rc;
1611 : WaitEvent *cur_event;
1612 :
1613 : /* Reset any wait events that need it */
1614 : for (cur_event = set->events;
1615 : cur_event < (set->events + set->nevents);
1616 : cur_event++)
1617 : {
1618 : if (cur_event->reset)
1619 : {
1620 : WaitEventAdjustWin32(set, cur_event);
1621 : cur_event->reset = false;
1622 : }
1623 :
1624 : /*
1625 : * We associate the socket with a new event handle for each
1626 : * WaitEventSet. FD_CLOSE is only generated once if the other end
1627 : * closes gracefully. Therefore we might miss the FD_CLOSE
1628 : * notification, if it was delivered to another event after we stopped
1629 : * waiting for it. Close that race by peeking for EOF after setting
1630 : * up this handle to receive notifications, and before entering the
1631 : * sleep.
1632 : *
1633 : * XXX If we had one event handle for the lifetime of a socket, we
1634 : * wouldn't need this.
1635 : */
1636 : if (cur_event->events & WL_SOCKET_READABLE)
1637 : {
1638 : char c;
1639 : WSABUF buf;
1640 : DWORD received;
1641 : DWORD flags;
1642 :
1643 : buf.buf = &c;
1644 : buf.len = 1;
1645 : flags = MSG_PEEK;
1646 : if (WSARecv(cur_event->fd, &buf, 1, &received, &flags, NULL, NULL) == 0)
1647 : {
1648 : occurred_events->pos = cur_event->pos;
1649 : occurred_events->user_data = cur_event->user_data;
1650 : occurred_events->events = WL_SOCKET_READABLE;
1651 : occurred_events->fd = cur_event->fd;
1652 : return 1;
1653 : }
1654 : }
1655 :
1656 : /*
1657 : * Windows does not guarantee to log an FD_WRITE network event
1658 : * indicating that more data can be sent unless the previous send()
1659 : * failed with WSAEWOULDBLOCK. While our caller might well have made
1660 : * such a call, we cannot assume that here. Therefore, if waiting for
1661 : * write-ready, force the issue by doing a dummy send(). If the dummy
1662 : * send() succeeds, assume that the socket is in fact write-ready, and
1663 : * return immediately. Also, if it fails with something other than
1664 : * WSAEWOULDBLOCK, return a write-ready indication to let our caller
1665 : * deal with the error condition.
1666 : */
1667 : if (cur_event->events & WL_SOCKET_WRITEABLE)
1668 : {
1669 : char c;
1670 : WSABUF buf;
1671 : DWORD sent;
1672 : int r;
1673 :
1674 : buf.buf = &c;
1675 : buf.len = 0;
1676 :
1677 : r = WSASend(cur_event->fd, &buf, 1, &sent, 0, NULL, NULL);
1678 : if (r == 0 || WSAGetLastError() != WSAEWOULDBLOCK)
1679 : {
1680 : occurred_events->pos = cur_event->pos;
1681 : occurred_events->user_data = cur_event->user_data;
1682 : occurred_events->events = WL_SOCKET_WRITEABLE;
1683 : occurred_events->fd = cur_event->fd;
1684 : return 1;
1685 : }
1686 : }
1687 : }
1688 :
1689 : /*
1690 : * Sleep.
1691 : *
1692 : * Need to wait for ->nevents + 1, because signal handle is in [0].
1693 : */
1694 : rc = WaitForMultipleObjects(set->nevents + 1, set->handles, FALSE,
1695 : cur_timeout);
1696 :
1697 : /* Check return code */
1698 : if (rc == WAIT_FAILED)
1699 : elog(ERROR, "WaitForMultipleObjects() failed: error code %lu",
1700 : GetLastError());
1701 : else if (rc == WAIT_TIMEOUT)
1702 : {
1703 : /* timeout exceeded */
1704 : return -1;
1705 : }
1706 :
1707 : if (rc == WAIT_OBJECT_0)
1708 : {
1709 : /* Service newly-arrived signals */
1710 : pgwin32_dispatch_queued_signals();
1711 : return 0; /* retry */
1712 : }
1713 :
1714 : /*
1715 : * With an offset of one, due to the always present pgwin32_signal_event,
1716 : * the handle offset directly corresponds to a wait event.
1717 : */
1718 : cur_event = (WaitEvent *) &set->events[rc - WAIT_OBJECT_0 - 1];
1719 :
1720 : for (;;)
1721 : {
1722 : int next_pos;
1723 : int count;
1724 :
1725 : occurred_events->pos = cur_event->pos;
1726 : occurred_events->user_data = cur_event->user_data;
1727 : occurred_events->events = 0;
1728 :
1729 : if (cur_event->events == WL_LATCH_SET)
1730 : {
1731 : /*
1732 : * We cannot use set->latch->event to reset the fired event if we
1733 : * aren't waiting on this latch now.
1734 : */
1735 : if (!ResetEvent(set->handles[cur_event->pos + 1]))
1736 : elog(ERROR, "ResetEvent failed: error code %lu", GetLastError());
1737 :
1738 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1739 : {
1740 : occurred_events->fd = PGINVALID_SOCKET;
1741 : occurred_events->events = WL_LATCH_SET;
1742 : occurred_events++;
1743 : returned_events++;
1744 : }
1745 : }
1746 : else if (cur_event->events == WL_POSTMASTER_DEATH)
1747 : {
1748 : /*
1749 : * Postmaster apparently died. Since the consequences of falsely
1750 : * returning WL_POSTMASTER_DEATH could be pretty unpleasant, we
1751 : * take the trouble to positively verify this with
1752 : * PostmasterIsAlive(), even though there is no known reason to
1753 : * think that the event could be falsely set on Windows.
1754 : */
1755 : if (!PostmasterIsAliveInternal())
1756 : {
1757 : if (set->exit_on_postmaster_death)
1758 : proc_exit(1);
1759 : occurred_events->fd = PGINVALID_SOCKET;
1760 : occurred_events->events = WL_POSTMASTER_DEATH;
1761 : occurred_events++;
1762 : returned_events++;
1763 : }
1764 : }
1765 : else if (cur_event->events & WL_SOCKET_MASK)
1766 : {
1767 : WSANETWORKEVENTS resEvents;
1768 : HANDLE handle = set->handles[cur_event->pos + 1];
1769 :
1770 : Assert(cur_event->fd);
1771 :
1772 : occurred_events->fd = cur_event->fd;
1773 :
1774 : ZeroMemory(&resEvents, sizeof(resEvents));
1775 : if (WSAEnumNetworkEvents(cur_event->fd, handle, &resEvents) != 0)
1776 : elog(ERROR, "failed to enumerate network events: error code %d",
1777 : WSAGetLastError());
1778 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1779 : (resEvents.lNetworkEvents & FD_READ))
1780 : {
1781 : /* data available in socket */
1782 : occurred_events->events |= WL_SOCKET_READABLE;
1783 :
1784 : /*------
1785 : * WaitForMultipleObjects doesn't guarantee that a read event
1786 : * will be returned if the latch is set at the same time. Even
1787 : * if it did, the caller might drop that event expecting it to
1788 : * reoccur on next call. So, we must force the event to be
1789 : * reset if this WaitEventSet is used again in order to avoid
1790 : * an indefinite hang.
1791 : *
1792 : * Refer
1793 : * https://msdn.microsoft.com/en-us/library/windows/desktop/ms741576(v=vs.85).aspx
1794 : * for the behavior of socket events.
1795 : *------
1796 : */
1797 : cur_event->reset = true;
1798 : }
1799 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1800 : (resEvents.lNetworkEvents & FD_WRITE))
1801 : {
1802 : /* writeable */
1803 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1804 : }
1805 : if ((cur_event->events & WL_SOCKET_CONNECTED) &&
1806 : (resEvents.lNetworkEvents & FD_CONNECT))
1807 : {
1808 : /* connected */
1809 : occurred_events->events |= WL_SOCKET_CONNECTED;
1810 : }
1811 : if ((cur_event->events & WL_SOCKET_ACCEPT) &&
1812 : (resEvents.lNetworkEvents & FD_ACCEPT))
1813 : {
1814 : /* incoming connection could be accepted */
1815 : occurred_events->events |= WL_SOCKET_ACCEPT;
1816 : }
1817 : if (resEvents.lNetworkEvents & FD_CLOSE)
1818 : {
1819 : /* EOF/error, so signal all caller-requested socket flags */
1820 : occurred_events->events |= (cur_event->events & WL_SOCKET_MASK);
1821 : }
1822 :
1823 : if (occurred_events->events != 0)
1824 : {
1825 : occurred_events++;
1826 : returned_events++;
1827 : }
1828 : }
1829 :
1830 : /* Is the output buffer full? */
1831 : if (returned_events == nevents)
1832 : break;
1833 :
1834 : /* Have we run out of possible events? */
1835 : next_pos = cur_event->pos + 1;
1836 : if (next_pos == set->nevents)
1837 : break;
1838 :
1839 : /*
1840 : * Poll the rest of the event handles in the array starting at
1841 : * next_pos being careful to skip over the initial signal handle too.
1842 : * This time we use a zero timeout.
1843 : */
1844 : count = set->nevents - next_pos;
1845 : rc = WaitForMultipleObjects(count,
1846 : set->handles + 1 + next_pos,
1847 : false,
1848 : 0);
1849 :
1850 : /*
1851 : * We don't distinguish between errors and WAIT_TIMEOUT here because
1852 : * we already have events to report.
1853 : */
1854 : if (rc < WAIT_OBJECT_0 || rc >= WAIT_OBJECT_0 + count)
1855 : break;
1856 :
1857 : /* We have another event to decode. */
1858 : cur_event = &set->events[next_pos + (rc - WAIT_OBJECT_0)];
1859 : }
1860 :
1861 : return returned_events;
1862 : }
1863 : #endif
1864 :
1865 : /*
1866 : * Return whether the current build options can report WL_SOCKET_CLOSED.
1867 : */
1868 : bool
1869 2310 : WaitEventSetCanReportClosed(void)
1870 : {
1871 : #if (defined(WAIT_USE_POLL) && defined(POLLRDHUP)) || \
1872 : defined(WAIT_USE_EPOLL) || \
1873 : defined(WAIT_USE_KQUEUE)
1874 2310 : return true;
1875 : #else
1876 : return false;
1877 : #endif
1878 : }
1879 :
1880 : /*
1881 : * Get the number of wait events registered in a given WaitEventSet.
1882 : */
1883 : int
1884 228 : GetNumRegisteredWaitEvents(WaitEventSet *set)
1885 : {
1886 228 : return set->nevents;
1887 : }
1888 :
1889 : #if defined(WAIT_USE_SELF_PIPE)
1890 :
1891 : /*
1892 : * SetLatch uses SIGURG to wake up the process waiting on the latch.
1893 : *
1894 : * Wake up WaitLatch, if we're waiting.
1895 : */
1896 : static void
1897 : latch_sigurg_handler(SIGNAL_ARGS)
1898 : {
1899 : if (waiting)
1900 : sendSelfPipeByte();
1901 : }
1902 :
1903 : /* Send one byte to the self-pipe, to wake up WaitLatch */
1904 : static void
1905 : sendSelfPipeByte(void)
1906 : {
1907 : int rc;
1908 : char dummy = 0;
1909 :
1910 : retry:
1911 : rc = write(selfpipe_writefd, &dummy, 1);
1912 : if (rc < 0)
1913 : {
1914 : /* If interrupted by signal, just retry */
1915 : if (errno == EINTR)
1916 : goto retry;
1917 :
1918 : /*
1919 : * If the pipe is full, we don't need to retry, the data that's there
1920 : * already is enough to wake up WaitLatch.
1921 : */
1922 : if (errno == EAGAIN || errno == EWOULDBLOCK)
1923 : return;
1924 :
1925 : /*
1926 : * Oops, the write() failed for some other reason. We might be in a
1927 : * signal handler, so it's not safe to elog(). We have no choice but
1928 : * silently ignore the error.
1929 : */
1930 : return;
1931 : }
1932 : }
1933 :
1934 : #endif
1935 :
1936 : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
1937 :
1938 : /*
1939 : * Read all available data from self-pipe or signalfd.
1940 : *
1941 : * Note: this is only called when waiting = true. If it fails and doesn't
1942 : * return, it must reset that flag first (though ideally, this will never
1943 : * happen).
1944 : */
1945 : static void
1946 2181190 : drain(void)
1947 : {
1948 : char buf[1024];
1949 : int rc;
1950 : int fd;
1951 :
1952 : #ifdef WAIT_USE_SELF_PIPE
1953 : fd = selfpipe_readfd;
1954 : #else
1955 2181190 : fd = signal_fd;
1956 : #endif
1957 :
1958 : for (;;)
1959 : {
1960 2181190 : rc = read(fd, buf, sizeof(buf));
1961 2181190 : if (rc < 0)
1962 : {
1963 0 : if (errno == EAGAIN || errno == EWOULDBLOCK)
1964 : break; /* the descriptor is empty */
1965 0 : else if (errno == EINTR)
1966 0 : continue; /* retry */
1967 : else
1968 : {
1969 0 : waiting = false;
1970 : #ifdef WAIT_USE_SELF_PIPE
1971 : elog(ERROR, "read() on self-pipe failed: %m");
1972 : #else
1973 0 : elog(ERROR, "read() on signalfd failed: %m");
1974 : #endif
1975 : }
1976 : }
1977 2181190 : else if (rc == 0)
1978 : {
1979 0 : waiting = false;
1980 : #ifdef WAIT_USE_SELF_PIPE
1981 : elog(ERROR, "unexpected EOF on self-pipe");
1982 : #else
1983 0 : elog(ERROR, "unexpected EOF on signalfd");
1984 : #endif
1985 : }
1986 2181190 : else if (rc < sizeof(buf))
1987 : {
1988 : /* we successfully drained the pipe; no need to read() again */
1989 2181190 : break;
1990 : }
1991 : /* else buffer wasn't big enough, so read again */
1992 : }
1993 2181190 : }
1994 :
1995 : #endif
1996 :
1997 : static void
1998 2 : ResOwnerReleaseWaitEventSet(Datum res)
1999 : {
2000 2 : WaitEventSet *set = (WaitEventSet *) DatumGetPointer(res);
2001 :
2002 : Assert(set->owner != NULL);
2003 2 : set->owner = NULL;
2004 2 : FreeWaitEventSet(set);
2005 2 : }
2006 :
2007 : #ifndef WIN32
2008 : /*
2009 : * Wake up my process if it's currently sleeping in WaitEventSetWaitBlock()
2010 : *
2011 : * NB: be sure to save and restore errno around it. (That's standard practice
2012 : * in most signal handlers, of course, but we used to omit it in handlers that
2013 : * only set a flag.) XXX
2014 : *
2015 : * NB: this function is called from critical sections and signal handlers so
2016 : * throwing an error is not a good idea.
2017 : *
2018 : * On Windows, Latch uses SetEvent directly and this is not used.
2019 : */
2020 : void
2021 244120 : WakeupMyProc(void)
2022 : {
2023 : #if defined(WAIT_USE_SELF_PIPE)
2024 : if (waiting)
2025 : sendSelfPipeByte();
2026 : #else
2027 244120 : if (waiting)
2028 244120 : kill(MyProcPid, SIGURG);
2029 : #endif
2030 244120 : }
2031 :
2032 : /* Similar to WakeupMyProc, but wake up another process */
2033 : void
2034 2127674 : WakeupOtherProc(int pid)
2035 : {
2036 2127674 : kill(pid, SIGURG);
2037 2127674 : }
2038 : #endif
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