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
222 102454 : ResourceOwnerRememberWaitEventSet(ResourceOwner owner, WaitEventSet *set)
223 : {
224 102454 : ResourceOwnerRemember(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
225 102454 : }
226 : static inline void
227 102452 : ResourceOwnerForgetWaitEventSet(ResourceOwner owner, WaitEventSet *set)
228 : {
229 102452 : ResourceOwnerForget(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
230 102452 : }
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 44578 : 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 44578 : 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 42478 : if (signal_fd != -1)
327 : {
328 : /* Release postmaster's signal FD; ignore any error */
329 42478 : (void) close(signal_fd);
330 42478 : signal_fd = -1;
331 42478 : ReleaseExternalFD();
332 : }
333 : }
334 :
335 : /* Block SIGURG, because we'll receive it through a signalfd. */
336 44578 : sigaddset(&UnBlockSig, SIGURG);
337 :
338 : /* Set up the signalfd to receive SIGURG notifications. */
339 44578 : sigemptyset(&signalfd_mask);
340 44578 : sigaddset(&signalfd_mask, SIGURG);
341 44578 : signal_fd = signalfd(-1, &signalfd_mask, SFD_NONBLOCK | SFD_CLOEXEC);
342 44578 : if (signal_fd < 0)
343 0 : elog(FATAL, "signalfd() failed");
344 44578 : 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 44578 : }
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 213164 : CreateWaitEventSet(ResourceOwner resowner, int nevents)
364 : {
365 : WaitEventSet *set;
366 : char *data;
367 213164 : 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 213164 : sz += MAXALIGN(sizeof(WaitEventSet));
376 213164 : sz += MAXALIGN(sizeof(WaitEvent) * nevents);
377 :
378 : #if defined(WAIT_USE_EPOLL)
379 213164 : 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 213164 : if (resowner != NULL)
390 102454 : ResourceOwnerEnlarge(resowner);
391 :
392 213164 : data = (char *) MemoryContextAllocZero(TopMemoryContext, sz);
393 :
394 213164 : set = (WaitEventSet *) data;
395 213164 : data += MAXALIGN(sizeof(WaitEventSet));
396 :
397 213164 : set->events = (WaitEvent *) data;
398 213164 : data += MAXALIGN(sizeof(WaitEvent) * nevents);
399 :
400 : #if defined(WAIT_USE_EPOLL)
401 213164 : set->epoll_ret_events = (struct epoll_event *) data;
402 213164 : 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 213164 : set->latch = NULL;
415 213164 : set->nevents_space = nevents;
416 213164 : set->exit_on_postmaster_death = false;
417 :
418 213164 : if (resowner != NULL)
419 : {
420 102454 : ResourceOwnerRememberWaitEventSet(resowner, set);
421 102454 : set->owner = resowner;
422 : }
423 :
424 : #if defined(WAIT_USE_EPOLL)
425 213164 : if (!AcquireExternalFD())
426 0 : elog(ERROR, "AcquireExternalFD, for epoll_create1, failed: %m");
427 213164 : set->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
428 213164 : if (set->epoll_fd < 0)
429 : {
430 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 :
467 213164 : 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 141480 : FreeWaitEventSet(WaitEventSet *set)
481 : {
482 141480 : if (set->owner)
483 : {
484 102452 : ResourceOwnerForgetWaitEventSet(set->owner, set);
485 102452 : set->owner = NULL;
486 : }
487 :
488 : #if defined(WAIT_USE_EPOLL)
489 141480 : close(set->epoll_fd);
490 141480 : 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 141480 : pfree(set);
517 141480 : }
518 :
519 : /*
520 : * Free a previously created WaitEventSet in a child process after a fork().
521 : */
522 : void
523 36002 : FreeWaitEventSetAfterFork(WaitEventSet *set)
524 : {
525 : #if defined(WAIT_USE_EPOLL)
526 36002 : close(set->epoll_fd);
527 36002 : ReleaseExternalFD();
528 : #elif defined(WAIT_USE_KQUEUE)
529 : /* kqueues are not normally inherited by child processes */
530 : ReleaseExternalFD();
531 : #endif
532 :
533 36002 : pfree(set);
534 36002 : }
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 591220 : 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 591220 : if (events == WL_EXIT_ON_PM_DEATH)
578 : {
579 182302 : events = WL_POSTMASTER_DEATH;
580 182302 : set->exit_on_postmaster_death = true;
581 : }
582 :
583 591220 : if (latch)
584 : {
585 212940 : if (latch->owner_pid != MyProcPid)
586 0 : elog(ERROR, "cannot wait on a latch owned by another process");
587 212940 : if (set->latch)
588 0 : elog(ERROR, "cannot wait on more than one latch");
589 212940 : if ((events & WL_LATCH_SET) != WL_LATCH_SET)
590 0 : elog(ERROR, "latch events only support being set");
591 : }
592 : else
593 : {
594 378280 : 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 591220 : if (fd == PGINVALID_SOCKET && (events & WL_SOCKET_MASK))
600 0 : elog(ERROR, "cannot wait on socket event without a socket");
601 :
602 591220 : event = &set->events[set->nevents];
603 591220 : event->pos = set->nevents++;
604 591220 : event->fd = fd;
605 591220 : event->events = events;
606 591220 : event->user_data = user_data;
607 : #ifdef WIN32
608 : event->reset = false;
609 : #endif
610 :
611 591220 : if (events == WL_LATCH_SET)
612 : {
613 212940 : set->latch = latch;
614 212940 : set->latch_pos = event->pos;
615 : #if defined(WAIT_USE_SELF_PIPE)
616 : event->fd = selfpipe_readfd;
617 : #elif defined(WAIT_USE_SIGNALFD)
618 212940 : 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 378280 : else if (events == WL_POSTMASTER_DEATH)
627 : {
628 : #ifndef WIN32
629 209430 : 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 591220 : 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 591220 : 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 4816834 : 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 4816834 : 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 4816834 : if (event->events == WL_POSTMASTER_DEATH)
677 : {
678 2158364 : if (events != WL_POSTMASTER_DEATH && events != WL_EXIT_ON_PM_DEATH)
679 0 : elog(ERROR, "cannot remove postmaster death event");
680 2158364 : set->exit_on_postmaster_death = ((events & WL_EXIT_ON_PM_DEATH) != 0);
681 2158364 : 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 2658470 : if (events == event->events &&
691 2631300 : (!(event->events & WL_LATCH_SET) || set->latch == latch))
692 2562898 : return;
693 :
694 95572 : if (event->events & WL_LATCH_SET && events != event->events)
695 0 : elog(ERROR, "cannot modify latch event");
696 :
697 : /* FIXME: validate event mask */
698 95572 : event->events = events;
699 :
700 95572 : if (events == WL_LATCH_SET)
701 : {
702 68402 : if (latch && latch->owner_pid != MyProcPid)
703 0 : elog(ERROR, "cannot wait on a latch owned by another process");
704 68402 : 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 68402 : return;
718 : #endif
719 : }
720 :
721 : #if defined(WAIT_USE_EPOLL)
722 27170 : 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 618390 : 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 618390 : epoll_ev.data.ptr = event;
744 : /* always wait for errors */
745 618390 : epoll_ev.events = EPOLLERR | EPOLLHUP;
746 :
747 : /* prepare pollfd entry once */
748 618390 : if (event->events == WL_LATCH_SET)
749 : {
750 : Assert(set->latch != NULL);
751 212940 : epoll_ev.events |= EPOLLIN;
752 : }
753 405450 : else if (event->events == WL_POSTMASTER_DEATH)
754 : {
755 209430 : 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 196020 : if (event->events & WL_SOCKET_READABLE)
765 165712 : epoll_ev.events |= EPOLLIN;
766 196020 : if (event->events & WL_SOCKET_WRITEABLE)
767 32610 : epoll_ev.events |= EPOLLOUT;
768 196020 : 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 618390 : rc = epoll_ctl(set->epoll_fd, action, event->fd, &epoll_ev);
778 :
779 618390 : if (rc < 0)
780 0 : ereport(ERROR,
781 : (errcode_for_socket_access(),
782 : errmsg("%s() failed: %m",
783 : "epoll_ctl")));
784 618390 : }
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 2987762 : WaitEventSetWait(WaitEventSet *set, long timeout,
1038 : WaitEvent *occurred_events, int nevents,
1039 : uint32 wait_event_info)
1040 : {
1041 2987762 : int returned_events = 0;
1042 : instr_time start_time;
1043 : instr_time cur_time;
1044 2987762 : long cur_timeout = -1;
1045 :
1046 : 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 2987762 : if (timeout >= 0)
1053 : {
1054 542234 : INSTR_TIME_SET_CURRENT(start_time);
1055 : Assert(timeout >= 0 && timeout <= INT_MAX);
1056 542234 : cur_timeout = timeout;
1057 : }
1058 : else
1059 2445528 : INSTR_TIME_SET_ZERO(start_time);
1060 :
1061 2987762 : pgstat_report_wait_start(wait_event_info);
1062 :
1063 : #ifndef WIN32
1064 2987762 : waiting = true;
1065 : #else
1066 : /* Ensure that signals are serviced even if latch is already set */
1067 : pgwin32_dispatch_queued_signals();
1068 : #endif
1069 6025828 : 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 3240546 : if (set->latch && !set->latch->is_set)
1101 : {
1102 : /* about to sleep on a latch */
1103 2883242 : set->latch->maybe_sleeping = true;
1104 2883242 : pg_memory_barrier();
1105 : /* and recheck */
1106 : }
1107 :
1108 3240546 : if (set->latch && set->latch->is_set)
1109 : {
1110 357094 : occurred_events->fd = PGINVALID_SOCKET;
1111 357094 : occurred_events->pos = set->latch_pos;
1112 357094 : occurred_events->user_data =
1113 357094 : set->events[set->latch_pos].user_data;
1114 357094 : occurred_events->events = WL_LATCH_SET;
1115 357094 : occurred_events++;
1116 357094 : returned_events++;
1117 :
1118 : /* could have been set above */
1119 357094 : set->latch->maybe_sleeping = false;
1120 :
1121 357094 : if (returned_events == nevents)
1122 140892 : 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 216202 : cur_timeout = 0;
1130 216202 : 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 3099654 : rc = WaitEventSetWaitBlock(set, cur_timeout,
1139 : occurred_events, nevents - returned_events);
1140 :
1141 3099602 : if (set->latch &&
1142 3099266 : set->latch->maybe_sleeping)
1143 2883064 : set->latch->maybe_sleeping = false;
1144 :
1145 3099602 : if (rc == -1)
1146 61534 : break; /* timeout occurred */
1147 : else
1148 3038068 : returned_events += rc;
1149 :
1150 : /* If we're not done, update cur_timeout for next iteration */
1151 3038068 : if (returned_events == 0 && timeout >= 0)
1152 : {
1153 231370 : INSTR_TIME_SET_CURRENT(cur_time);
1154 231370 : INSTR_TIME_SUBTRACT(cur_time, start_time);
1155 231370 : cur_timeout = timeout - (long) INSTR_TIME_GET_MILLISEC(cur_time);
1156 231370 : if (cur_timeout <= 0)
1157 2 : break;
1158 : }
1159 : }
1160 : #ifndef WIN32
1161 2987710 : waiting = false;
1162 : #endif
1163 :
1164 2987710 : pgstat_report_wait_end();
1165 :
1166 2987710 : 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 3099654 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1182 : WaitEvent *occurred_events, int nevents)
1183 : {
1184 3099654 : int returned_events = 0;
1185 : int rc;
1186 : WaitEvent *cur_event;
1187 : struct epoll_event *cur_epoll_event;
1188 :
1189 : /* Sleep */
1190 3099654 : rc = epoll_wait(set->epoll_fd, set->epoll_ret_events,
1191 3099654 : Min(nevents, set->nevents_space), cur_timeout);
1192 :
1193 : /* Check return code */
1194 3099654 : if (rc < 0)
1195 : {
1196 : /* EINTR is okay, otherwise complain */
1197 230942 : if (errno != EINTR)
1198 : {
1199 0 : waiting = false;
1200 0 : ereport(ERROR,
1201 : (errcode_for_socket_access(),
1202 : errmsg("%s() failed: %m",
1203 : "epoll_wait")));
1204 : }
1205 230942 : return 0;
1206 : }
1207 2868712 : else if (rc == 0)
1208 : {
1209 : /* timeout exceeded */
1210 61534 : 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 2807178 : for (cur_epoll_event = set->epoll_ret_events;
1219 5614340 : cur_epoll_event < (set->epoll_ret_events + rc) &&
1220 : returned_events < nevents;
1221 2807162 : cur_epoll_event++)
1222 : {
1223 : /* epoll's data pointer is set to the associated WaitEvent */
1224 2807214 : cur_event = (WaitEvent *) cur_epoll_event->data.ptr;
1225 :
1226 2807214 : occurred_events->pos = cur_event->pos;
1227 2807214 : occurred_events->user_data = cur_event->user_data;
1228 2807214 : occurred_events->events = 0;
1229 :
1230 2807214 : if (cur_event->events == WL_LATCH_SET &&
1231 2267506 : cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP))
1232 : {
1233 : /* Drain the signalfd. */
1234 2267506 : drain();
1235 :
1236 2267506 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1237 : {
1238 2043454 : occurred_events->fd = PGINVALID_SOCKET;
1239 2043454 : occurred_events->events = WL_LATCH_SET;
1240 2043454 : occurred_events++;
1241 2043454 : returned_events++;
1242 : }
1243 : }
1244 539708 : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1245 52 : 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 52 : if (!PostmasterIsAliveInternal())
1259 : {
1260 52 : if (set->exit_on_postmaster_death)
1261 52 : proc_exit(1);
1262 0 : occurred_events->fd = PGINVALID_SOCKET;
1263 0 : occurred_events->events = WL_POSTMASTER_DEATH;
1264 0 : occurred_events++;
1265 0 : returned_events++;
1266 : }
1267 : }
1268 539656 : else if (cur_event->events & (WL_SOCKET_READABLE |
1269 : WL_SOCKET_WRITEABLE |
1270 : WL_SOCKET_CLOSED))
1271 : {
1272 : Assert(cur_event->fd != PGINVALID_SOCKET);
1273 :
1274 539656 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1275 516354 : (cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP)))
1276 : {
1277 : /* data available in socket, or EOF */
1278 484598 : occurred_events->events |= WL_SOCKET_READABLE;
1279 : }
1280 :
1281 539656 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1282 61832 : (cur_epoll_event->events & (EPOLLOUT | EPOLLERR | EPOLLHUP)))
1283 : {
1284 : /* writable, or EOF */
1285 60892 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1286 : }
1287 :
1288 539656 : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1289 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 :
1295 539656 : if (occurred_events->events != 0)
1296 : {
1297 539656 : occurred_events->fd = cur_event->fd;
1298 539656 : occurred_events++;
1299 539656 : returned_events++;
1300 : }
1301 : }
1302 : }
1303 :
1304 2807126 : 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 2100 : WaitEventSetCanReportClosed(void)
1868 : {
1869 : #if (defined(WAIT_USE_POLL) && defined(POLLRDHUP)) || \
1870 : defined(WAIT_USE_EPOLL) || \
1871 : defined(WAIT_USE_KQUEUE)
1872 2100 : 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 286 : GetNumRegisteredWaitEvents(WaitEventSet *set)
1883 : {
1884 286 : 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 2267506 : 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 2267506 : fd = signal_fd;
1954 : #endif
1955 :
1956 : for (;;)
1957 : {
1958 2267506 : rc = read(fd, buf, sizeof(buf));
1959 2267506 : if (rc < 0)
1960 : {
1961 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 : }
1975 2267506 : else if (rc == 0)
1976 : {
1977 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 : }
1984 2267506 : else if (rc < sizeof(buf))
1985 : {
1986 : /* we successfully drained the pipe; no need to read() again */
1987 2267506 : break;
1988 : }
1989 : /* else buffer wasn't big enough, so read again */
1990 : }
1991 2267506 : }
1992 :
1993 : #endif
1994 :
1995 : static void
1996 2 : ResOwnerReleaseWaitEventSet(Datum res)
1997 : {
1998 2 : WaitEventSet *set = (WaitEventSet *) DatumGetPointer(res);
1999 :
2000 : Assert(set->owner != NULL);
2001 2 : set->owner = NULL;
2002 2 : FreeWaitEventSet(set);
2003 2 : }
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 231060 : WakeupMyProc(void)
2020 : {
2021 : #if defined(WAIT_USE_SELF_PIPE)
2022 : if (waiting)
2023 : sendSelfPipeByte();
2024 : #else
2025 231060 : if (waiting)
2026 231060 : kill(MyProcPid, SIGURG);
2027 : #endif
2028 231060 : }
2029 :
2030 : /* Similar to WakeupMyProc, but wake up another process */
2031 : void
2032 2217726 : WakeupOtherProc(int pid)
2033 : {
2034 2217726 : kill(pid, SIGURG);
2035 2217726 : }
2036 : #endif
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