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 166332 : ResourceOwnerRememberWaitEventSet(ResourceOwner owner, WaitEventSet *set)
224 : {
225 166332 : ResourceOwnerRemember(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
226 166332 : }
227 : static inline void
228 166330 : ResourceOwnerForgetWaitEventSet(ResourceOwner owner, WaitEventSet *set)
229 : {
230 166330 : ResourceOwnerForget(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
231 166330 : }
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 47166 : 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 47166 : 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 44912 : if (signal_fd != -1)
328 : {
329 : /* Release postmaster's signal FD; ignore any error */
330 44912 : (void) close(signal_fd);
331 44912 : signal_fd = -1;
332 44912 : ReleaseExternalFD();
333 : }
334 : }
335 :
336 : /* Block SIGURG, because we'll receive it through a signalfd. */
337 47166 : sigaddset(&UnBlockSig, SIGURG);
338 :
339 : /* Set up the signalfd to receive SIGURG notifications. */
340 47166 : sigemptyset(&signalfd_mask);
341 47166 : sigaddset(&signalfd_mask, SIGURG);
342 47166 : signal_fd = signalfd(-1, &signalfd_mask, SFD_NONBLOCK | SFD_CLOEXEC);
343 47166 : if (signal_fd < 0)
344 0 : elog(FATAL, "signalfd() failed");
345 47166 : 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 47166 : }
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 299154 : CreateWaitEventSet(ResourceOwner resowner, int nevents)
365 : {
366 : WaitEventSet *set;
367 : char *data;
368 299154 : 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 299154 : sz += MAXALIGN(sizeof(WaitEventSet));
377 299154 : sz += MAXALIGN(sizeof(WaitEvent) * nevents);
378 :
379 : #if defined(WAIT_USE_EPOLL)
380 299154 : 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 299154 : if (resowner != NULL)
391 166332 : ResourceOwnerEnlarge(resowner);
392 :
393 299154 : data = (char *) MemoryContextAllocZero(TopMemoryContext, sz);
394 :
395 299154 : set = (WaitEventSet *) data;
396 299154 : data += MAXALIGN(sizeof(WaitEventSet));
397 :
398 299154 : set->events = (WaitEvent *) data;
399 299154 : data += MAXALIGN(sizeof(WaitEvent) * nevents);
400 :
401 : #if defined(WAIT_USE_EPOLL)
402 299154 : set->epoll_ret_events = (struct epoll_event *) data;
403 299154 : 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 299154 : set->latch = NULL;
416 299154 : set->nevents_space = nevents;
417 299154 : set->exit_on_postmaster_death = false;
418 :
419 299154 : if (resowner != NULL)
420 : {
421 166332 : ResourceOwnerRememberWaitEventSet(resowner, set);
422 166332 : set->owner = resowner;
423 : }
424 :
425 : #if defined(WAIT_USE_EPOLL)
426 299154 : if (!AcquireExternalFD())
427 0 : elog(ERROR, "AcquireExternalFD, for epoll_create1, failed: %m");
428 299154 : set->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
429 299154 : 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 : StaticAssertStmt(WSA_INVALID_EVENT == NULL, "");
466 : #endif
467 :
468 299154 : return set;
469 : }
470 :
471 : /*
472 : * Free a previously created WaitEventSet.
473 : *
474 : * Note: preferably, this shouldn't have to free any resources that could be
475 : * inherited across an exec(). If it did, we'd likely leak those resources in
476 : * many scenarios. For the epoll case, we ensure that by setting EPOLL_CLOEXEC
477 : * when the FD is created. For the Windows case, we assume that the handles
478 : * involved are non-inheritable.
479 : */
480 : void
481 225392 : FreeWaitEventSet(WaitEventSet *set)
482 : {
483 225392 : if (set->owner)
484 : {
485 166330 : ResourceOwnerForgetWaitEventSet(set->owner, set);
486 166330 : set->owner = NULL;
487 : }
488 :
489 : #if defined(WAIT_USE_EPOLL)
490 225392 : close(set->epoll_fd);
491 225392 : ReleaseExternalFD();
492 : #elif defined(WAIT_USE_KQUEUE)
493 : close(set->kqueue_fd);
494 : ReleaseExternalFD();
495 : #elif defined(WAIT_USE_WIN32)
496 : for (WaitEvent *cur_event = set->events;
497 : cur_event < (set->events + set->nevents);
498 : cur_event++)
499 : {
500 : if (cur_event->events & WL_LATCH_SET)
501 : {
502 : /* uses the latch's HANDLE */
503 : }
504 : else if (cur_event->events & WL_POSTMASTER_DEATH)
505 : {
506 : /* uses PostmasterHandle */
507 : }
508 : else
509 : {
510 : /* Clean up the event object we created for the socket */
511 : WSAEventSelect(cur_event->fd, NULL, 0);
512 : WSACloseEvent(set->handles[cur_event->pos + 1]);
513 : }
514 : }
515 : #endif
516 :
517 225392 : pfree(set);
518 225392 : }
519 :
520 : /*
521 : * Free a previously created WaitEventSet in a child process after a fork().
522 : */
523 : void
524 37938 : FreeWaitEventSetAfterFork(WaitEventSet *set)
525 : {
526 : #if defined(WAIT_USE_EPOLL)
527 37938 : close(set->epoll_fd);
528 37938 : ReleaseExternalFD();
529 : #elif defined(WAIT_USE_KQUEUE)
530 : /* kqueues are not normally inherited by child processes */
531 : ReleaseExternalFD();
532 : #endif
533 :
534 37938 : pfree(set);
535 37938 : }
536 :
537 : /* ---
538 : * Add an event to the set. Possible events are:
539 : * - WL_LATCH_SET: Wait for the latch to be set
540 : * - WL_POSTMASTER_DEATH: Wait for postmaster to die
541 : * - WL_SOCKET_READABLE: Wait for socket to become readable,
542 : * can be combined in one event with other WL_SOCKET_* events
543 : * - WL_SOCKET_WRITEABLE: Wait for socket to become writeable,
544 : * can be combined with other WL_SOCKET_* events
545 : * - WL_SOCKET_CONNECTED: Wait for socket connection to be established,
546 : * can be combined with other WL_SOCKET_* events (on non-Windows
547 : * platforms, this is the same as WL_SOCKET_WRITEABLE)
548 : * - WL_SOCKET_ACCEPT: Wait for new connection to a server socket,
549 : * can be combined with other WL_SOCKET_* events (on non-Windows
550 : * platforms, this is the same as WL_SOCKET_READABLE)
551 : * - WL_SOCKET_CLOSED: Wait for socket to be closed by remote peer.
552 : * - WL_EXIT_ON_PM_DEATH: Exit immediately if the postmaster dies
553 : *
554 : * Returns the offset in WaitEventSet->events (starting from 0), which can be
555 : * used to modify previously added wait events using ModifyWaitEvent().
556 : *
557 : * In the WL_LATCH_SET case the latch must be owned by the current process,
558 : * i.e. it must be a process-local latch initialized with InitLatch, or a
559 : * shared latch associated with the current process by calling OwnLatch.
560 : *
561 : * In the WL_SOCKET_READABLE/WRITEABLE/CONNECTED/ACCEPT cases, EOF and error
562 : * conditions cause the socket to be reported as readable/writable/connected,
563 : * so that the caller can deal with the condition.
564 : *
565 : * The user_data pointer specified here will be set for the events returned
566 : * by WaitEventSetWait(), allowing to easily associate additional data with
567 : * events.
568 : */
569 : int
570 846198 : AddWaitEventToSet(WaitEventSet *set, uint32 events, pgsocket fd, Latch *latch,
571 : void *user_data)
572 : {
573 : WaitEvent *event;
574 :
575 : /* not enough space */
576 : Assert(set->nevents < set->nevents_space);
577 :
578 846198 : if (events == WL_EXIT_ON_PM_DEATH)
579 : {
580 268554 : events = WL_POSTMASTER_DEATH;
581 268554 : set->exit_on_postmaster_death = true;
582 : }
583 :
584 846198 : if (latch)
585 : {
586 298830 : if (latch->owner_pid != MyProcPid)
587 0 : elog(ERROR, "cannot wait on a latch owned by another process");
588 298830 : if (set->latch)
589 0 : elog(ERROR, "cannot wait on more than one latch");
590 298830 : if ((events & WL_LATCH_SET) != WL_LATCH_SET)
591 0 : elog(ERROR, "latch events only support being set");
592 : }
593 : else
594 : {
595 547368 : if (events & WL_LATCH_SET)
596 0 : elog(ERROR, "cannot wait on latch without a specified latch");
597 : }
598 :
599 : /* waiting for socket readiness without a socket indicates a bug */
600 846198 : if (fd == PGINVALID_SOCKET && (events & WL_SOCKET_MASK))
601 0 : elog(ERROR, "cannot wait on socket event without a socket");
602 :
603 846198 : event = &set->events[set->nevents];
604 846198 : event->pos = set->nevents++;
605 846198 : event->fd = fd;
606 846198 : event->events = events;
607 846198 : event->user_data = user_data;
608 : #ifdef WIN32
609 : event->reset = false;
610 : #endif
611 :
612 846198 : if (events == WL_LATCH_SET)
613 : {
614 298830 : set->latch = latch;
615 298830 : set->latch_pos = event->pos;
616 : #if defined(WAIT_USE_SELF_PIPE)
617 : event->fd = selfpipe_readfd;
618 : #elif defined(WAIT_USE_SIGNALFD)
619 298830 : event->fd = signal_fd;
620 : #else
621 : event->fd = PGINVALID_SOCKET;
622 : #ifdef WAIT_USE_EPOLL
623 : return event->pos;
624 : #endif
625 : #endif
626 : }
627 547368 : else if (events == WL_POSTMASTER_DEATH)
628 : {
629 : #ifndef WIN32
630 295178 : event->fd = postmaster_alive_fds[POSTMASTER_FD_WATCH];
631 : #endif
632 : }
633 :
634 : /* perform wait primitive specific initialization, if needed */
635 : #if defined(WAIT_USE_EPOLL)
636 846198 : WaitEventAdjustEpoll(set, event, EPOLL_CTL_ADD);
637 : #elif defined(WAIT_USE_KQUEUE)
638 : WaitEventAdjustKqueue(set, event, 0);
639 : #elif defined(WAIT_USE_POLL)
640 : WaitEventAdjustPoll(set, event);
641 : #elif defined(WAIT_USE_WIN32)
642 : WaitEventAdjustWin32(set, event);
643 : #endif
644 :
645 846198 : return event->pos;
646 : }
647 :
648 : /*
649 : * Change the event mask and, in the WL_LATCH_SET case, the latch associated
650 : * with the WaitEvent. The latch may be changed to NULL to disable the latch
651 : * temporarily, and then set back to a latch later.
652 : *
653 : * 'pos' is the id returned by AddWaitEventToSet.
654 : */
655 : void
656 4380968 : ModifyWaitEvent(WaitEventSet *set, int pos, uint32 events, Latch *latch)
657 : {
658 : WaitEvent *event;
659 : #if defined(WAIT_USE_KQUEUE)
660 : int old_events;
661 : #endif
662 :
663 : Assert(pos < set->nevents);
664 :
665 4380968 : event = &set->events[pos];
666 : #if defined(WAIT_USE_KQUEUE)
667 : old_events = event->events;
668 : #endif
669 :
670 : /*
671 : * Allow switching between WL_POSTMASTER_DEATH and WL_EXIT_ON_PM_DEATH.
672 : *
673 : * Note that because WL_EXIT_ON_PM_DEATH is mapped to WL_POSTMASTER_DEATH
674 : * in AddWaitEventToSet(), this needs to be checked before the fast-path
675 : * below that checks if 'events' has changed.
676 : */
677 4380968 : if (event->events == WL_POSTMASTER_DEATH)
678 : {
679 1981428 : if (events != WL_POSTMASTER_DEATH && events != WL_EXIT_ON_PM_DEATH)
680 0 : elog(ERROR, "cannot remove postmaster death event");
681 1981428 : set->exit_on_postmaster_death = ((events & WL_EXIT_ON_PM_DEATH) != 0);
682 1981428 : return;
683 : }
684 :
685 : /*
686 : * If neither the event mask nor the associated latch changes, return
687 : * early. That's an important optimization for some sockets, where
688 : * ModifyWaitEvent is frequently used to switch from waiting for reads to
689 : * waiting on writes.
690 : */
691 2399540 : if (events == event->events &&
692 2377130 : (!(event->events & WL_LATCH_SET) || set->latch == latch))
693 2309510 : return;
694 :
695 90030 : if (event->events & WL_LATCH_SET && events != event->events)
696 0 : elog(ERROR, "cannot modify latch event");
697 :
698 : /* FIXME: validate event mask */
699 90030 : event->events = events;
700 :
701 90030 : if (events == WL_LATCH_SET)
702 : {
703 67620 : if (latch && latch->owner_pid != MyProcPid)
704 0 : elog(ERROR, "cannot wait on a latch owned by another process");
705 67620 : set->latch = latch;
706 :
707 : /*
708 : * On Unix, we don't need to modify the kernel object because the
709 : * underlying pipe (if there is one) is the same for all latches so we
710 : * can return immediately. On Windows, we need to update our array of
711 : * handles, but we leave the old one in place and tolerate spurious
712 : * wakeups if the latch is disabled.
713 : */
714 : #if defined(WAIT_USE_WIN32)
715 : if (!latch)
716 : return;
717 : #else
718 67620 : return;
719 : #endif
720 : }
721 :
722 : #if defined(WAIT_USE_EPOLL)
723 22410 : WaitEventAdjustEpoll(set, event, EPOLL_CTL_MOD);
724 : #elif defined(WAIT_USE_KQUEUE)
725 : WaitEventAdjustKqueue(set, event, old_events);
726 : #elif defined(WAIT_USE_POLL)
727 : WaitEventAdjustPoll(set, event);
728 : #elif defined(WAIT_USE_WIN32)
729 : WaitEventAdjustWin32(set, event);
730 : #endif
731 : }
732 :
733 : #if defined(WAIT_USE_EPOLL)
734 : /*
735 : * action can be one of EPOLL_CTL_ADD | EPOLL_CTL_MOD | EPOLL_CTL_DEL
736 : */
737 : static void
738 868608 : WaitEventAdjustEpoll(WaitEventSet *set, WaitEvent *event, int action)
739 : {
740 : struct epoll_event epoll_ev;
741 : int rc;
742 :
743 : /* pointer to our event, returned by epoll_wait */
744 868608 : epoll_ev.data.ptr = event;
745 : /* always wait for errors */
746 868608 : epoll_ev.events = EPOLLERR | EPOLLHUP;
747 :
748 : /* prepare pollfd entry once */
749 868608 : if (event->events == WL_LATCH_SET)
750 : {
751 : Assert(set->latch != NULL);
752 298830 : epoll_ev.events |= EPOLLIN;
753 : }
754 569778 : else if (event->events == WL_POSTMASTER_DEATH)
755 : {
756 295178 : epoll_ev.events |= EPOLLIN;
757 : }
758 : else
759 : {
760 : Assert(event->fd != PGINVALID_SOCKET);
761 : Assert(event->events & (WL_SOCKET_READABLE |
762 : WL_SOCKET_WRITEABLE |
763 : WL_SOCKET_CLOSED));
764 :
765 274600 : if (event->events & WL_SOCKET_READABLE)
766 244514 : epoll_ev.events |= EPOLLIN;
767 274600 : if (event->events & WL_SOCKET_WRITEABLE)
768 33254 : epoll_ev.events |= EPOLLOUT;
769 274600 : if (event->events & WL_SOCKET_CLOSED)
770 0 : epoll_ev.events |= EPOLLRDHUP;
771 : }
772 :
773 : /*
774 : * Even though unused, we also pass epoll_ev as the data argument if
775 : * EPOLL_CTL_DEL is passed as action. There used to be an epoll bug
776 : * requiring that, and actually it makes the code simpler...
777 : */
778 868608 : rc = epoll_ctl(set->epoll_fd, action, event->fd, &epoll_ev);
779 :
780 868608 : if (rc < 0)
781 0 : ereport(ERROR,
782 : (errcode_for_socket_access(),
783 : errmsg("%s() failed: %m",
784 : "epoll_ctl")));
785 868608 : }
786 : #endif
787 :
788 : #if defined(WAIT_USE_POLL)
789 : static void
790 : WaitEventAdjustPoll(WaitEventSet *set, WaitEvent *event)
791 : {
792 : struct pollfd *pollfd = &set->pollfds[event->pos];
793 :
794 : pollfd->revents = 0;
795 : pollfd->fd = event->fd;
796 :
797 : /* prepare pollfd entry once */
798 : if (event->events == WL_LATCH_SET)
799 : {
800 : Assert(set->latch != NULL);
801 : pollfd->events = POLLIN;
802 : }
803 : else if (event->events == WL_POSTMASTER_DEATH)
804 : {
805 : pollfd->events = POLLIN;
806 : }
807 : else
808 : {
809 : Assert(event->events & (WL_SOCKET_READABLE |
810 : WL_SOCKET_WRITEABLE |
811 : WL_SOCKET_CLOSED));
812 : pollfd->events = 0;
813 : if (event->events & WL_SOCKET_READABLE)
814 : pollfd->events |= POLLIN;
815 : if (event->events & WL_SOCKET_WRITEABLE)
816 : pollfd->events |= POLLOUT;
817 : #ifdef POLLRDHUP
818 : if (event->events & WL_SOCKET_CLOSED)
819 : pollfd->events |= POLLRDHUP;
820 : #endif
821 : }
822 :
823 : Assert(event->fd != PGINVALID_SOCKET);
824 : }
825 : #endif
826 :
827 : #if defined(WAIT_USE_KQUEUE)
828 :
829 : /*
830 : * On most BSD family systems, the udata member of struct kevent is of type
831 : * void *, so we could directly convert to/from WaitEvent *. Unfortunately,
832 : * NetBSD has it as intptr_t, so here we wallpaper over that difference with
833 : * an lvalue cast.
834 : */
835 : #define AccessWaitEvent(k_ev) (*((WaitEvent **)(&(k_ev)->udata)))
836 :
837 : static inline void
838 : WaitEventAdjustKqueueAdd(struct kevent *k_ev, int filter, int action,
839 : WaitEvent *event)
840 : {
841 : k_ev->ident = event->fd;
842 : k_ev->filter = filter;
843 : k_ev->flags = action;
844 : k_ev->fflags = 0;
845 : k_ev->data = 0;
846 : AccessWaitEvent(k_ev) = event;
847 : }
848 :
849 : static inline void
850 : WaitEventAdjustKqueueAddPostmaster(struct kevent *k_ev, WaitEvent *event)
851 : {
852 : /* For now postmaster death can only be added, not removed. */
853 : k_ev->ident = PostmasterPid;
854 : k_ev->filter = EVFILT_PROC;
855 : k_ev->flags = EV_ADD;
856 : k_ev->fflags = NOTE_EXIT;
857 : k_ev->data = 0;
858 : AccessWaitEvent(k_ev) = event;
859 : }
860 :
861 : static inline void
862 : WaitEventAdjustKqueueAddLatch(struct kevent *k_ev, WaitEvent *event)
863 : {
864 : /* For now latch can only be added, not removed. */
865 : k_ev->ident = SIGURG;
866 : k_ev->filter = EVFILT_SIGNAL;
867 : k_ev->flags = EV_ADD;
868 : k_ev->fflags = 0;
869 : k_ev->data = 0;
870 : AccessWaitEvent(k_ev) = event;
871 : }
872 :
873 : /*
874 : * old_events is the previous event mask, used to compute what has changed.
875 : */
876 : static void
877 : WaitEventAdjustKqueue(WaitEventSet *set, WaitEvent *event, int old_events)
878 : {
879 : int rc;
880 : struct kevent k_ev[2];
881 : int count = 0;
882 : bool new_filt_read = false;
883 : bool old_filt_read = false;
884 : bool new_filt_write = false;
885 : bool old_filt_write = false;
886 :
887 : if (old_events == event->events)
888 : return;
889 :
890 : Assert(event->events != WL_LATCH_SET || set->latch != NULL);
891 : Assert(event->events == WL_LATCH_SET ||
892 : event->events == WL_POSTMASTER_DEATH ||
893 : (event->events & (WL_SOCKET_READABLE |
894 : WL_SOCKET_WRITEABLE |
895 : WL_SOCKET_CLOSED)));
896 :
897 : if (event->events == WL_POSTMASTER_DEATH)
898 : {
899 : /*
900 : * Unlike all the other implementations, we detect postmaster death
901 : * using process notification instead of waiting on the postmaster
902 : * alive pipe.
903 : */
904 : WaitEventAdjustKqueueAddPostmaster(&k_ev[count++], event);
905 : }
906 : else if (event->events == WL_LATCH_SET)
907 : {
908 : /* We detect latch wakeup using a signal event. */
909 : WaitEventAdjustKqueueAddLatch(&k_ev[count++], event);
910 : }
911 : else
912 : {
913 : /*
914 : * We need to compute the adds and deletes required to get from the
915 : * old event mask to the new event mask, since kevent treats readable
916 : * and writable as separate events.
917 : */
918 : if (old_events & (WL_SOCKET_READABLE | WL_SOCKET_CLOSED))
919 : old_filt_read = true;
920 : if (event->events & (WL_SOCKET_READABLE | WL_SOCKET_CLOSED))
921 : new_filt_read = true;
922 : if (old_events & WL_SOCKET_WRITEABLE)
923 : old_filt_write = true;
924 : if (event->events & WL_SOCKET_WRITEABLE)
925 : new_filt_write = true;
926 : if (old_filt_read && !new_filt_read)
927 : WaitEventAdjustKqueueAdd(&k_ev[count++], EVFILT_READ, EV_DELETE,
928 : event);
929 : else if (!old_filt_read && new_filt_read)
930 : WaitEventAdjustKqueueAdd(&k_ev[count++], EVFILT_READ, EV_ADD,
931 : event);
932 : if (old_filt_write && !new_filt_write)
933 : WaitEventAdjustKqueueAdd(&k_ev[count++], EVFILT_WRITE, EV_DELETE,
934 : event);
935 : else if (!old_filt_write && new_filt_write)
936 : WaitEventAdjustKqueueAdd(&k_ev[count++], EVFILT_WRITE, EV_ADD,
937 : event);
938 : }
939 :
940 : /* For WL_SOCKET_READ -> WL_SOCKET_CLOSED, no change needed. */
941 : if (count == 0)
942 : return;
943 :
944 : Assert(count <= 2);
945 :
946 : rc = kevent(set->kqueue_fd, &k_ev[0], count, NULL, 0, NULL);
947 :
948 : /*
949 : * When adding the postmaster's pid, we have to consider that it might
950 : * already have exited and perhaps even been replaced by another process
951 : * with the same pid. If so, we have to defer reporting this as an event
952 : * until the next call to WaitEventSetWaitBlock().
953 : */
954 :
955 : if (rc < 0)
956 : {
957 : if (event->events == WL_POSTMASTER_DEATH &&
958 : (errno == ESRCH || errno == EACCES))
959 : set->report_postmaster_not_running = true;
960 : else
961 : ereport(ERROR,
962 : (errcode_for_socket_access(),
963 : errmsg("%s() failed: %m",
964 : "kevent")));
965 : }
966 : else if (event->events == WL_POSTMASTER_DEATH &&
967 : PostmasterPid != getppid() &&
968 : !PostmasterIsAlive())
969 : {
970 : /*
971 : * The extra PostmasterIsAliveInternal() check prevents false alarms
972 : * on systems that give a different value for getppid() while being
973 : * traced by a debugger.
974 : */
975 : set->report_postmaster_not_running = true;
976 : }
977 : }
978 :
979 : #endif
980 :
981 : #if defined(WAIT_USE_WIN32)
982 : static void
983 : WaitEventAdjustWin32(WaitEventSet *set, WaitEvent *event)
984 : {
985 : HANDLE *handle = &set->handles[event->pos + 1];
986 :
987 : if (event->events == WL_LATCH_SET)
988 : {
989 : Assert(set->latch != NULL);
990 : *handle = set->latch->event;
991 : }
992 : else if (event->events == WL_POSTMASTER_DEATH)
993 : {
994 : *handle = PostmasterHandle;
995 : }
996 : else
997 : {
998 : int flags = FD_CLOSE; /* always check for errors/EOF */
999 :
1000 : if (event->events & WL_SOCKET_READABLE)
1001 : flags |= FD_READ;
1002 : if (event->events & WL_SOCKET_WRITEABLE)
1003 : flags |= FD_WRITE;
1004 : if (event->events & WL_SOCKET_CONNECTED)
1005 : flags |= FD_CONNECT;
1006 : if (event->events & WL_SOCKET_ACCEPT)
1007 : flags |= FD_ACCEPT;
1008 :
1009 : if (*handle == WSA_INVALID_EVENT)
1010 : {
1011 : *handle = WSACreateEvent();
1012 : if (*handle == WSA_INVALID_EVENT)
1013 : elog(ERROR, "failed to create event for socket: error code %d",
1014 : WSAGetLastError());
1015 : }
1016 : if (WSAEventSelect(event->fd, *handle, flags) != 0)
1017 : elog(ERROR, "failed to set up event for socket: error code %d",
1018 : WSAGetLastError());
1019 :
1020 : Assert(event->fd != PGINVALID_SOCKET);
1021 : }
1022 : }
1023 : #endif
1024 :
1025 : /*
1026 : * Wait for events added to the set to happen, or until the timeout is
1027 : * reached. At most nevents occurred events are returned.
1028 : *
1029 : * If timeout = -1, block until an event occurs; if 0, check sockets for
1030 : * readiness, but don't block; if > 0, block for at most timeout milliseconds.
1031 : *
1032 : * Returns the number of events occurred, or 0 if the timeout was reached.
1033 : *
1034 : * Returned events will have the fd, pos, user_data fields set to the
1035 : * values associated with the registered event.
1036 : */
1037 : int
1038 2805708 : WaitEventSetWait(WaitEventSet *set, long timeout,
1039 : WaitEvent *occurred_events, int nevents,
1040 : uint32 wait_event_info)
1041 : {
1042 2805708 : int returned_events = 0;
1043 : instr_time start_time;
1044 : instr_time cur_time;
1045 2805708 : long cur_timeout = -1;
1046 :
1047 : Assert(nevents > 0);
1048 :
1049 : /*
1050 : * Initialize timeout if requested. We must record the current time so
1051 : * that we can determine the remaining timeout if interrupted.
1052 : */
1053 2805708 : if (timeout >= 0)
1054 : {
1055 639366 : INSTR_TIME_SET_CURRENT(start_time);
1056 : Assert(timeout >= 0 && timeout <= INT_MAX);
1057 639366 : cur_timeout = timeout;
1058 : }
1059 : else
1060 2166342 : INSTR_TIME_SET_ZERO(start_time);
1061 :
1062 2805708 : pgstat_report_wait_start(wait_event_info);
1063 :
1064 : #ifndef WIN32
1065 2805708 : waiting = true;
1066 : #else
1067 : /* Ensure that signals are serviced even if latch is already set */
1068 : pgwin32_dispatch_queued_signals();
1069 : #endif
1070 5670872 : while (returned_events == 0)
1071 : {
1072 : int rc;
1073 :
1074 : /*
1075 : * Check if the latch is set already first. If so, we either exit
1076 : * immediately or ask the kernel for further events available right
1077 : * now without waiting, depending on how many events the caller wants.
1078 : *
1079 : * If someone sets the latch between this and the
1080 : * WaitEventSetWaitBlock() below, the setter will write a byte to the
1081 : * pipe (or signal us and the signal handler will do that), and the
1082 : * readiness routine will return immediately.
1083 : *
1084 : * On unix, If there's a pending byte in the self pipe, we'll notice
1085 : * whenever blocking. Only clearing the pipe in that case avoids
1086 : * having to drain it every time WaitLatchOrSocket() is used. Should
1087 : * the pipe-buffer fill up we're still ok, because the pipe is in
1088 : * nonblocking mode. It's unlikely for that to happen, because the
1089 : * self pipe isn't filled unless we're blocking (waiting = true), or
1090 : * from inside a signal handler in latch_sigurg_handler().
1091 : *
1092 : * On windows, we'll also notice if there's a pending event for the
1093 : * latch when blocking, but there's no danger of anything filling up,
1094 : * as "Setting an event that is already set has no effect.".
1095 : *
1096 : * Note: we assume that the kernel calls involved in latch management
1097 : * will provide adequate synchronization on machines with weak memory
1098 : * ordering, so that we cannot miss seeing is_set if a notification
1099 : * has already been queued.
1100 : */
1101 3068972 : if (set->latch && !set->latch->is_set)
1102 : {
1103 : /* about to sleep on a latch */
1104 2718348 : set->latch->maybe_sleeping = true;
1105 2718348 : pg_memory_barrier();
1106 : /* and recheck */
1107 : }
1108 :
1109 3068972 : if (set->latch && set->latch->is_set)
1110 : {
1111 349746 : occurred_events->fd = PGINVALID_SOCKET;
1112 349746 : occurred_events->pos = set->latch_pos;
1113 349746 : occurred_events->user_data =
1114 349746 : set->events[set->latch_pos].user_data;
1115 349746 : occurred_events->events = WL_LATCH_SET;
1116 349746 : occurred_events++;
1117 349746 : returned_events++;
1118 :
1119 : /* could have been set above */
1120 349746 : set->latch->maybe_sleeping = false;
1121 :
1122 349746 : if (returned_events == nevents)
1123 142588 : break; /* output buffer full already */
1124 :
1125 : /*
1126 : * Even though we already have an event, we'll poll just once with
1127 : * zero timeout to see what non-latch events we can fit into the
1128 : * output buffer at the same time.
1129 : */
1130 207158 : cur_timeout = 0;
1131 207158 : timeout = 0;
1132 : }
1133 :
1134 : /*
1135 : * Wait for events using the readiness primitive chosen at the top of
1136 : * this file. If -1 is returned, a timeout has occurred, if 0 we have
1137 : * to retry, everything >= 1 is the number of returned events.
1138 : */
1139 2926384 : rc = WaitEventSetWaitBlock(set, cur_timeout,
1140 : occurred_events, nevents - returned_events);
1141 :
1142 2926326 : if (set->latch &&
1143 2925268 : set->latch->maybe_sleeping)
1144 2718110 : set->latch->maybe_sleeping = false;
1145 :
1146 2926326 : if (rc == -1)
1147 61160 : break; /* timeout occurred */
1148 : else
1149 2865166 : returned_events += rc;
1150 :
1151 : /* If we're not done, update cur_timeout for next iteration */
1152 2865166 : if (returned_events == 0 && timeout >= 0)
1153 : {
1154 243912 : INSTR_TIME_SET_CURRENT(cur_time);
1155 243912 : INSTR_TIME_SUBTRACT(cur_time, start_time);
1156 243912 : cur_timeout = timeout - (long) INSTR_TIME_GET_MILLISEC(cur_time);
1157 243912 : if (cur_timeout <= 0)
1158 2 : break;
1159 : }
1160 : }
1161 : #ifndef WIN32
1162 2805650 : waiting = false;
1163 : #endif
1164 :
1165 2805650 : pgstat_report_wait_end();
1166 :
1167 2805650 : return returned_events;
1168 : }
1169 :
1170 :
1171 : #if defined(WAIT_USE_EPOLL)
1172 :
1173 : /*
1174 : * Wait using linux's epoll_wait(2).
1175 : *
1176 : * This is the preferable wait method, as several readiness notifications are
1177 : * delivered, without having to iterate through all of set->events. The return
1178 : * epoll_event struct contain a pointer to our events, making association
1179 : * easy.
1180 : */
1181 : static inline int
1182 2926384 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1183 : WaitEvent *occurred_events, int nevents)
1184 : {
1185 2926384 : int returned_events = 0;
1186 : int rc;
1187 : WaitEvent *cur_event;
1188 : struct epoll_event *cur_epoll_event;
1189 :
1190 : /* Sleep */
1191 2926384 : rc = epoll_wait(set->epoll_fd, set->epoll_ret_events,
1192 2926384 : Min(nevents, set->nevents_space), cur_timeout);
1193 :
1194 : /* Check return code */
1195 2926384 : if (rc < 0)
1196 : {
1197 : /* EINTR is okay, otherwise complain */
1198 238354 : if (errno != EINTR)
1199 : {
1200 0 : waiting = false;
1201 0 : ereport(ERROR,
1202 : (errcode_for_socket_access(),
1203 : errmsg("%s() failed: %m",
1204 : "epoll_wait")));
1205 : }
1206 238354 : return 0;
1207 : }
1208 2688030 : else if (rc == 0)
1209 : {
1210 : /* timeout exceeded */
1211 61160 : return -1;
1212 : }
1213 :
1214 : /*
1215 : * At least one event occurred, iterate over the returned epoll events
1216 : * until they're either all processed, or we've returned all the events
1217 : * the caller desired.
1218 : */
1219 2626870 : for (cur_epoll_event = set->epoll_ret_events;
1220 5253790 : cur_epoll_event < (set->epoll_ret_events + rc) &&
1221 : returned_events < nevents;
1222 2626920 : cur_epoll_event++)
1223 : {
1224 : /* epoll's data pointer is set to the associated WaitEvent */
1225 2626978 : cur_event = (WaitEvent *) cur_epoll_event->data.ptr;
1226 :
1227 2626978 : occurred_events->pos = cur_event->pos;
1228 2626978 : occurred_events->user_data = cur_event->user_data;
1229 2626978 : occurred_events->events = 0;
1230 :
1231 2626978 : if (cur_event->events == WL_LATCH_SET &&
1232 2084306 : cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP))
1233 : {
1234 : /* Drain the signalfd. */
1235 2084306 : drain();
1236 :
1237 2084306 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1238 : {
1239 1853996 : occurred_events->fd = PGINVALID_SOCKET;
1240 1853996 : occurred_events->events = WL_LATCH_SET;
1241 1853996 : occurred_events++;
1242 1853996 : returned_events++;
1243 : }
1244 : }
1245 542672 : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1246 58 : cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP))
1247 : {
1248 : /*
1249 : * We expect an EPOLLHUP when the remote end is closed, but
1250 : * because we don't expect the pipe to become readable or to have
1251 : * any errors either, treat those cases as postmaster death, too.
1252 : *
1253 : * Be paranoid about a spurious event signaling the postmaster as
1254 : * being dead. There have been reports about that happening with
1255 : * older primitives (select(2) to be specific), and a spurious
1256 : * WL_POSTMASTER_DEATH event would be painful. Re-checking doesn't
1257 : * cost much.
1258 : */
1259 58 : if (!PostmasterIsAliveInternal())
1260 : {
1261 58 : if (set->exit_on_postmaster_death)
1262 58 : proc_exit(1);
1263 0 : occurred_events->fd = PGINVALID_SOCKET;
1264 0 : occurred_events->events = WL_POSTMASTER_DEATH;
1265 0 : occurred_events++;
1266 0 : returned_events++;
1267 : }
1268 : }
1269 542614 : else if (cur_event->events & (WL_SOCKET_READABLE |
1270 : WL_SOCKET_WRITEABLE |
1271 : WL_SOCKET_CLOSED))
1272 : {
1273 : Assert(cur_event->fd != PGINVALID_SOCKET);
1274 :
1275 542614 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1276 514576 : (cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP)))
1277 : {
1278 : /* data available in socket, or EOF */
1279 486026 : occurred_events->events |= WL_SOCKET_READABLE;
1280 : }
1281 :
1282 542614 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1283 65936 : (cur_epoll_event->events & (EPOLLOUT | EPOLLERR | EPOLLHUP)))
1284 : {
1285 : /* writable, or EOF */
1286 65368 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1287 : }
1288 :
1289 542614 : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1290 0 : (cur_epoll_event->events & (EPOLLRDHUP | EPOLLERR | EPOLLHUP)))
1291 : {
1292 : /* remote peer shut down, or error */
1293 0 : occurred_events->events |= WL_SOCKET_CLOSED;
1294 : }
1295 :
1296 542614 : if (occurred_events->events != 0)
1297 : {
1298 542614 : occurred_events->fd = cur_event->fd;
1299 542614 : occurred_events++;
1300 542614 : returned_events++;
1301 : }
1302 : }
1303 : }
1304 :
1305 2626812 : return returned_events;
1306 : }
1307 :
1308 : #elif defined(WAIT_USE_KQUEUE)
1309 :
1310 : /*
1311 : * Wait using kevent(2) on BSD-family systems and macOS.
1312 : *
1313 : * For now this mirrors the epoll code, but in future it could modify the fd
1314 : * set in the same call to kevent as it uses for waiting instead of doing that
1315 : * with separate system calls.
1316 : */
1317 : static int
1318 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1319 : WaitEvent *occurred_events, int nevents)
1320 : {
1321 : int returned_events = 0;
1322 : int rc;
1323 : WaitEvent *cur_event;
1324 : struct kevent *cur_kqueue_event;
1325 : struct timespec timeout;
1326 : struct timespec *timeout_p;
1327 :
1328 : if (cur_timeout < 0)
1329 : timeout_p = NULL;
1330 : else
1331 : {
1332 : timeout.tv_sec = cur_timeout / 1000;
1333 : timeout.tv_nsec = (cur_timeout % 1000) * 1000000;
1334 : timeout_p = &timeout;
1335 : }
1336 :
1337 : /*
1338 : * Report postmaster events discovered by WaitEventAdjustKqueue() or an
1339 : * earlier call to WaitEventSetWait().
1340 : */
1341 : if (unlikely(set->report_postmaster_not_running))
1342 : {
1343 : if (set->exit_on_postmaster_death)
1344 : proc_exit(1);
1345 : occurred_events->fd = PGINVALID_SOCKET;
1346 : occurred_events->events = WL_POSTMASTER_DEATH;
1347 : return 1;
1348 : }
1349 :
1350 : /* Sleep */
1351 : rc = kevent(set->kqueue_fd, NULL, 0,
1352 : set->kqueue_ret_events,
1353 : Min(nevents, set->nevents_space),
1354 : timeout_p);
1355 :
1356 : /* Check return code */
1357 : if (rc < 0)
1358 : {
1359 : /* EINTR is okay, otherwise complain */
1360 : if (errno != EINTR)
1361 : {
1362 : waiting = false;
1363 : ereport(ERROR,
1364 : (errcode_for_socket_access(),
1365 : errmsg("%s() failed: %m",
1366 : "kevent")));
1367 : }
1368 : return 0;
1369 : }
1370 : else if (rc == 0)
1371 : {
1372 : /* timeout exceeded */
1373 : return -1;
1374 : }
1375 :
1376 : /*
1377 : * At least one event occurred, iterate over the returned kqueue events
1378 : * until they're either all processed, or we've returned all the events
1379 : * the caller desired.
1380 : */
1381 : for (cur_kqueue_event = set->kqueue_ret_events;
1382 : cur_kqueue_event < (set->kqueue_ret_events + rc) &&
1383 : returned_events < nevents;
1384 : cur_kqueue_event++)
1385 : {
1386 : /* kevent's udata points to the associated WaitEvent */
1387 : cur_event = AccessWaitEvent(cur_kqueue_event);
1388 :
1389 : occurred_events->pos = cur_event->pos;
1390 : occurred_events->user_data = cur_event->user_data;
1391 : occurred_events->events = 0;
1392 :
1393 : if (cur_event->events == WL_LATCH_SET &&
1394 : cur_kqueue_event->filter == EVFILT_SIGNAL)
1395 : {
1396 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1397 : {
1398 : occurred_events->fd = PGINVALID_SOCKET;
1399 : occurred_events->events = WL_LATCH_SET;
1400 : occurred_events++;
1401 : returned_events++;
1402 : }
1403 : }
1404 : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1405 : cur_kqueue_event->filter == EVFILT_PROC &&
1406 : (cur_kqueue_event->fflags & NOTE_EXIT) != 0)
1407 : {
1408 : /*
1409 : * The kernel will tell this kqueue object only once about the
1410 : * exit of the postmaster, so let's remember that for next time so
1411 : * that we provide level-triggered semantics.
1412 : */
1413 : set->report_postmaster_not_running = true;
1414 :
1415 : if (set->exit_on_postmaster_death)
1416 : proc_exit(1);
1417 : occurred_events->fd = PGINVALID_SOCKET;
1418 : occurred_events->events = WL_POSTMASTER_DEATH;
1419 : occurred_events++;
1420 : returned_events++;
1421 : }
1422 : else if (cur_event->events & (WL_SOCKET_READABLE |
1423 : WL_SOCKET_WRITEABLE |
1424 : WL_SOCKET_CLOSED))
1425 : {
1426 : Assert(cur_event->fd >= 0);
1427 :
1428 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1429 : (cur_kqueue_event->filter == EVFILT_READ))
1430 : {
1431 : /* readable, or EOF */
1432 : occurred_events->events |= WL_SOCKET_READABLE;
1433 : }
1434 :
1435 : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1436 : (cur_kqueue_event->filter == EVFILT_READ) &&
1437 : (cur_kqueue_event->flags & EV_EOF))
1438 : {
1439 : /* the remote peer has shut down */
1440 : occurred_events->events |= WL_SOCKET_CLOSED;
1441 : }
1442 :
1443 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1444 : (cur_kqueue_event->filter == EVFILT_WRITE))
1445 : {
1446 : /* writable, or EOF */
1447 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1448 : }
1449 :
1450 : if (occurred_events->events != 0)
1451 : {
1452 : occurred_events->fd = cur_event->fd;
1453 : occurred_events++;
1454 : returned_events++;
1455 : }
1456 : }
1457 : }
1458 :
1459 : return returned_events;
1460 : }
1461 :
1462 : #elif defined(WAIT_USE_POLL)
1463 :
1464 : /*
1465 : * Wait using poll(2).
1466 : *
1467 : * This allows to receive readiness notifications for several events at once,
1468 : * but requires iterating through all of set->pollfds.
1469 : */
1470 : static inline int
1471 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1472 : WaitEvent *occurred_events, int nevents)
1473 : {
1474 : int returned_events = 0;
1475 : int rc;
1476 : WaitEvent *cur_event;
1477 : struct pollfd *cur_pollfd;
1478 :
1479 : /* Sleep */
1480 : rc = poll(set->pollfds, set->nevents, (int) cur_timeout);
1481 :
1482 : /* Check return code */
1483 : if (rc < 0)
1484 : {
1485 : /* EINTR is okay, otherwise complain */
1486 : if (errno != EINTR)
1487 : {
1488 : waiting = false;
1489 : ereport(ERROR,
1490 : (errcode_for_socket_access(),
1491 : errmsg("%s() failed: %m",
1492 : "poll")));
1493 : }
1494 : return 0;
1495 : }
1496 : else if (rc == 0)
1497 : {
1498 : /* timeout exceeded */
1499 : return -1;
1500 : }
1501 :
1502 : for (cur_event = set->events, cur_pollfd = set->pollfds;
1503 : cur_event < (set->events + set->nevents) &&
1504 : returned_events < nevents;
1505 : cur_event++, cur_pollfd++)
1506 : {
1507 : /* no activity on this FD, skip */
1508 : if (cur_pollfd->revents == 0)
1509 : continue;
1510 :
1511 : occurred_events->pos = cur_event->pos;
1512 : occurred_events->user_data = cur_event->user_data;
1513 : occurred_events->events = 0;
1514 :
1515 : if (cur_event->events == WL_LATCH_SET &&
1516 : (cur_pollfd->revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL)))
1517 : {
1518 : /* There's data in the self-pipe, clear it. */
1519 : drain();
1520 :
1521 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1522 : {
1523 : occurred_events->fd = PGINVALID_SOCKET;
1524 : occurred_events->events = WL_LATCH_SET;
1525 : occurred_events++;
1526 : returned_events++;
1527 : }
1528 : }
1529 : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1530 : (cur_pollfd->revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL)))
1531 : {
1532 : /*
1533 : * We expect an POLLHUP when the remote end is closed, but because
1534 : * we don't expect the pipe to become readable or to have any
1535 : * errors either, treat those cases as postmaster death, too.
1536 : *
1537 : * Be paranoid about a spurious event signaling the postmaster as
1538 : * being dead. There have been reports about that happening with
1539 : * older primitives (select(2) to be specific), and a spurious
1540 : * WL_POSTMASTER_DEATH event would be painful. Re-checking doesn't
1541 : * cost much.
1542 : */
1543 : if (!PostmasterIsAliveInternal())
1544 : {
1545 : if (set->exit_on_postmaster_death)
1546 : proc_exit(1);
1547 : occurred_events->fd = PGINVALID_SOCKET;
1548 : occurred_events->events = WL_POSTMASTER_DEATH;
1549 : occurred_events++;
1550 : returned_events++;
1551 : }
1552 : }
1553 : else if (cur_event->events & (WL_SOCKET_READABLE |
1554 : WL_SOCKET_WRITEABLE |
1555 : WL_SOCKET_CLOSED))
1556 : {
1557 : int errflags = POLLHUP | POLLERR | POLLNVAL;
1558 :
1559 : Assert(cur_event->fd >= PGINVALID_SOCKET);
1560 :
1561 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1562 : (cur_pollfd->revents & (POLLIN | errflags)))
1563 : {
1564 : /* data available in socket, or EOF */
1565 : occurred_events->events |= WL_SOCKET_READABLE;
1566 : }
1567 :
1568 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1569 : (cur_pollfd->revents & (POLLOUT | errflags)))
1570 : {
1571 : /* writeable, or EOF */
1572 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1573 : }
1574 :
1575 : #ifdef POLLRDHUP
1576 : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1577 : (cur_pollfd->revents & (POLLRDHUP | errflags)))
1578 : {
1579 : /* remote peer closed, or error */
1580 : occurred_events->events |= WL_SOCKET_CLOSED;
1581 : }
1582 : #endif
1583 :
1584 : if (occurred_events->events != 0)
1585 : {
1586 : occurred_events->fd = cur_event->fd;
1587 : occurred_events++;
1588 : returned_events++;
1589 : }
1590 : }
1591 : }
1592 : return returned_events;
1593 : }
1594 :
1595 : #elif defined(WAIT_USE_WIN32)
1596 :
1597 : /*
1598 : * Wait using Windows' WaitForMultipleObjects(). Each call only "consumes" one
1599 : * event, so we keep calling until we've filled up our output buffer to match
1600 : * the behavior of the other implementations.
1601 : *
1602 : * https://blogs.msdn.microsoft.com/oldnewthing/20150409-00/?p=44273
1603 : */
1604 : static inline int
1605 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1606 : WaitEvent *occurred_events, int nevents)
1607 : {
1608 : int returned_events = 0;
1609 : DWORD rc;
1610 : WaitEvent *cur_event;
1611 :
1612 : /* Reset any wait events that need it */
1613 : for (cur_event = set->events;
1614 : cur_event < (set->events + set->nevents);
1615 : cur_event++)
1616 : {
1617 : if (cur_event->reset)
1618 : {
1619 : WaitEventAdjustWin32(set, cur_event);
1620 : cur_event->reset = false;
1621 : }
1622 :
1623 : /*
1624 : * We associate the socket with a new event handle for each
1625 : * WaitEventSet. FD_CLOSE is only generated once if the other end
1626 : * closes gracefully. Therefore we might miss the FD_CLOSE
1627 : * notification, if it was delivered to another event after we stopped
1628 : * waiting for it. Close that race by peeking for EOF after setting
1629 : * up this handle to receive notifications, and before entering the
1630 : * sleep.
1631 : *
1632 : * XXX If we had one event handle for the lifetime of a socket, we
1633 : * wouldn't need this.
1634 : */
1635 : if (cur_event->events & WL_SOCKET_READABLE)
1636 : {
1637 : char c;
1638 : WSABUF buf;
1639 : DWORD received;
1640 : DWORD flags;
1641 :
1642 : buf.buf = &c;
1643 : buf.len = 1;
1644 : flags = MSG_PEEK;
1645 : if (WSARecv(cur_event->fd, &buf, 1, &received, &flags, NULL, NULL) == 0)
1646 : {
1647 : occurred_events->pos = cur_event->pos;
1648 : occurred_events->user_data = cur_event->user_data;
1649 : occurred_events->events = WL_SOCKET_READABLE;
1650 : occurred_events->fd = cur_event->fd;
1651 : return 1;
1652 : }
1653 : }
1654 :
1655 : /*
1656 : * Windows does not guarantee to log an FD_WRITE network event
1657 : * indicating that more data can be sent unless the previous send()
1658 : * failed with WSAEWOULDBLOCK. While our caller might well have made
1659 : * such a call, we cannot assume that here. Therefore, if waiting for
1660 : * write-ready, force the issue by doing a dummy send(). If the dummy
1661 : * send() succeeds, assume that the socket is in fact write-ready, and
1662 : * return immediately. Also, if it fails with something other than
1663 : * WSAEWOULDBLOCK, return a write-ready indication to let our caller
1664 : * deal with the error condition.
1665 : */
1666 : if (cur_event->events & WL_SOCKET_WRITEABLE)
1667 : {
1668 : char c;
1669 : WSABUF buf;
1670 : DWORD sent;
1671 : int r;
1672 :
1673 : buf.buf = &c;
1674 : buf.len = 0;
1675 :
1676 : r = WSASend(cur_event->fd, &buf, 1, &sent, 0, NULL, NULL);
1677 : if (r == 0 || WSAGetLastError() != WSAEWOULDBLOCK)
1678 : {
1679 : occurred_events->pos = cur_event->pos;
1680 : occurred_events->user_data = cur_event->user_data;
1681 : occurred_events->events = WL_SOCKET_WRITEABLE;
1682 : occurred_events->fd = cur_event->fd;
1683 : return 1;
1684 : }
1685 : }
1686 : }
1687 :
1688 : /*
1689 : * Sleep.
1690 : *
1691 : * Need to wait for ->nevents + 1, because signal handle is in [0].
1692 : */
1693 : rc = WaitForMultipleObjects(set->nevents + 1, set->handles, FALSE,
1694 : cur_timeout);
1695 :
1696 : /* Check return code */
1697 : if (rc == WAIT_FAILED)
1698 : elog(ERROR, "WaitForMultipleObjects() failed: error code %lu",
1699 : GetLastError());
1700 : else if (rc == WAIT_TIMEOUT)
1701 : {
1702 : /* timeout exceeded */
1703 : return -1;
1704 : }
1705 :
1706 : if (rc == WAIT_OBJECT_0)
1707 : {
1708 : /* Service newly-arrived signals */
1709 : pgwin32_dispatch_queued_signals();
1710 : return 0; /* retry */
1711 : }
1712 :
1713 : /*
1714 : * With an offset of one, due to the always present pgwin32_signal_event,
1715 : * the handle offset directly corresponds to a wait event.
1716 : */
1717 : cur_event = (WaitEvent *) &set->events[rc - WAIT_OBJECT_0 - 1];
1718 :
1719 : for (;;)
1720 : {
1721 : int next_pos;
1722 : int count;
1723 :
1724 : occurred_events->pos = cur_event->pos;
1725 : occurred_events->user_data = cur_event->user_data;
1726 : occurred_events->events = 0;
1727 :
1728 : if (cur_event->events == WL_LATCH_SET)
1729 : {
1730 : /*
1731 : * We cannot use set->latch->event to reset the fired event if we
1732 : * aren't waiting on this latch now.
1733 : */
1734 : if (!ResetEvent(set->handles[cur_event->pos + 1]))
1735 : elog(ERROR, "ResetEvent failed: error code %lu", GetLastError());
1736 :
1737 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1738 : {
1739 : occurred_events->fd = PGINVALID_SOCKET;
1740 : occurred_events->events = WL_LATCH_SET;
1741 : occurred_events++;
1742 : returned_events++;
1743 : }
1744 : }
1745 : else if (cur_event->events == WL_POSTMASTER_DEATH)
1746 : {
1747 : /*
1748 : * Postmaster apparently died. Since the consequences of falsely
1749 : * returning WL_POSTMASTER_DEATH could be pretty unpleasant, we
1750 : * take the trouble to positively verify this with
1751 : * PostmasterIsAlive(), even though there is no known reason to
1752 : * think that the event could be falsely set on Windows.
1753 : */
1754 : if (!PostmasterIsAliveInternal())
1755 : {
1756 : if (set->exit_on_postmaster_death)
1757 : proc_exit(1);
1758 : occurred_events->fd = PGINVALID_SOCKET;
1759 : occurred_events->events = WL_POSTMASTER_DEATH;
1760 : occurred_events++;
1761 : returned_events++;
1762 : }
1763 : }
1764 : else if (cur_event->events & WL_SOCKET_MASK)
1765 : {
1766 : WSANETWORKEVENTS resEvents;
1767 : HANDLE handle = set->handles[cur_event->pos + 1];
1768 :
1769 : Assert(cur_event->fd);
1770 :
1771 : occurred_events->fd = cur_event->fd;
1772 :
1773 : ZeroMemory(&resEvents, sizeof(resEvents));
1774 : if (WSAEnumNetworkEvents(cur_event->fd, handle, &resEvents) != 0)
1775 : elog(ERROR, "failed to enumerate network events: error code %d",
1776 : WSAGetLastError());
1777 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1778 : (resEvents.lNetworkEvents & FD_READ))
1779 : {
1780 : /* data available in socket */
1781 : occurred_events->events |= WL_SOCKET_READABLE;
1782 :
1783 : /*------
1784 : * WaitForMultipleObjects doesn't guarantee that a read event
1785 : * will be returned if the latch is set at the same time. Even
1786 : * if it did, the caller might drop that event expecting it to
1787 : * reoccur on next call. So, we must force the event to be
1788 : * reset if this WaitEventSet is used again in order to avoid
1789 : * an indefinite hang.
1790 : *
1791 : * Refer
1792 : * https://msdn.microsoft.com/en-us/library/windows/desktop/ms741576(v=vs.85).aspx
1793 : * for the behavior of socket events.
1794 : *------
1795 : */
1796 : cur_event->reset = true;
1797 : }
1798 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1799 : (resEvents.lNetworkEvents & FD_WRITE))
1800 : {
1801 : /* writeable */
1802 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1803 : }
1804 : if ((cur_event->events & WL_SOCKET_CONNECTED) &&
1805 : (resEvents.lNetworkEvents & FD_CONNECT))
1806 : {
1807 : /* connected */
1808 : occurred_events->events |= WL_SOCKET_CONNECTED;
1809 : }
1810 : if ((cur_event->events & WL_SOCKET_ACCEPT) &&
1811 : (resEvents.lNetworkEvents & FD_ACCEPT))
1812 : {
1813 : /* incoming connection could be accepted */
1814 : occurred_events->events |= WL_SOCKET_ACCEPT;
1815 : }
1816 : if (resEvents.lNetworkEvents & FD_CLOSE)
1817 : {
1818 : /* EOF/error, so signal all caller-requested socket flags */
1819 : occurred_events->events |= (cur_event->events & WL_SOCKET_MASK);
1820 : }
1821 :
1822 : if (occurred_events->events != 0)
1823 : {
1824 : occurred_events++;
1825 : returned_events++;
1826 : }
1827 : }
1828 :
1829 : /* Is the output buffer full? */
1830 : if (returned_events == nevents)
1831 : break;
1832 :
1833 : /* Have we run out of possible events? */
1834 : next_pos = cur_event->pos + 1;
1835 : if (next_pos == set->nevents)
1836 : break;
1837 :
1838 : /*
1839 : * Poll the rest of the event handles in the array starting at
1840 : * next_pos being careful to skip over the initial signal handle too.
1841 : * This time we use a zero timeout.
1842 : */
1843 : count = set->nevents - next_pos;
1844 : rc = WaitForMultipleObjects(count,
1845 : set->handles + 1 + next_pos,
1846 : false,
1847 : 0);
1848 :
1849 : /*
1850 : * We don't distinguish between errors and WAIT_TIMEOUT here because
1851 : * we already have events to report.
1852 : */
1853 : if (rc < WAIT_OBJECT_0 || rc >= WAIT_OBJECT_0 + count)
1854 : break;
1855 :
1856 : /* We have another event to decode. */
1857 : cur_event = &set->events[next_pos + (rc - WAIT_OBJECT_0)];
1858 : }
1859 :
1860 : return returned_events;
1861 : }
1862 : #endif
1863 :
1864 : /*
1865 : * Return whether the current build options can report WL_SOCKET_CLOSED.
1866 : */
1867 : bool
1868 2254 : WaitEventSetCanReportClosed(void)
1869 : {
1870 : #if (defined(WAIT_USE_POLL) && defined(POLLRDHUP)) || \
1871 : defined(WAIT_USE_EPOLL) || \
1872 : defined(WAIT_USE_KQUEUE)
1873 2254 : return true;
1874 : #else
1875 : return false;
1876 : #endif
1877 : }
1878 :
1879 : /*
1880 : * Get the number of wait events registered in a given WaitEventSet.
1881 : */
1882 : int
1883 212 : GetNumRegisteredWaitEvents(WaitEventSet *set)
1884 : {
1885 212 : return set->nevents;
1886 : }
1887 :
1888 : #if defined(WAIT_USE_SELF_PIPE)
1889 :
1890 : /*
1891 : * SetLatch uses SIGURG to wake up the process waiting on the latch.
1892 : *
1893 : * Wake up WaitLatch, if we're waiting.
1894 : */
1895 : static void
1896 : latch_sigurg_handler(SIGNAL_ARGS)
1897 : {
1898 : if (waiting)
1899 : sendSelfPipeByte();
1900 : }
1901 :
1902 : /* Send one byte to the self-pipe, to wake up WaitLatch */
1903 : static void
1904 : sendSelfPipeByte(void)
1905 : {
1906 : int rc;
1907 : char dummy = 0;
1908 :
1909 : retry:
1910 : rc = write(selfpipe_writefd, &dummy, 1);
1911 : if (rc < 0)
1912 : {
1913 : /* If interrupted by signal, just retry */
1914 : if (errno == EINTR)
1915 : goto retry;
1916 :
1917 : /*
1918 : * If the pipe is full, we don't need to retry, the data that's there
1919 : * already is enough to wake up WaitLatch.
1920 : */
1921 : if (errno == EAGAIN || errno == EWOULDBLOCK)
1922 : return;
1923 :
1924 : /*
1925 : * Oops, the write() failed for some other reason. We might be in a
1926 : * signal handler, so it's not safe to elog(). We have no choice but
1927 : * silently ignore the error.
1928 : */
1929 : return;
1930 : }
1931 : }
1932 :
1933 : #endif
1934 :
1935 : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
1936 :
1937 : /*
1938 : * Read all available data from self-pipe or signalfd.
1939 : *
1940 : * Note: this is only called when waiting = true. If it fails and doesn't
1941 : * return, it must reset that flag first (though ideally, this will never
1942 : * happen).
1943 : */
1944 : static void
1945 2084306 : drain(void)
1946 : {
1947 : char buf[1024];
1948 : int rc;
1949 : int fd;
1950 :
1951 : #ifdef WAIT_USE_SELF_PIPE
1952 : fd = selfpipe_readfd;
1953 : #else
1954 2084306 : fd = signal_fd;
1955 : #endif
1956 :
1957 : for (;;)
1958 : {
1959 2084306 : rc = read(fd, buf, sizeof(buf));
1960 2084306 : if (rc < 0)
1961 : {
1962 0 : if (errno == EAGAIN || errno == EWOULDBLOCK)
1963 : break; /* the descriptor is empty */
1964 0 : else if (errno == EINTR)
1965 0 : continue; /* retry */
1966 : else
1967 : {
1968 0 : waiting = false;
1969 : #ifdef WAIT_USE_SELF_PIPE
1970 : elog(ERROR, "read() on self-pipe failed: %m");
1971 : #else
1972 0 : elog(ERROR, "read() on signalfd failed: %m");
1973 : #endif
1974 : }
1975 : }
1976 2084306 : else if (rc == 0)
1977 : {
1978 0 : waiting = false;
1979 : #ifdef WAIT_USE_SELF_PIPE
1980 : elog(ERROR, "unexpected EOF on self-pipe");
1981 : #else
1982 0 : elog(ERROR, "unexpected EOF on signalfd");
1983 : #endif
1984 : }
1985 2084306 : else if (rc < sizeof(buf))
1986 : {
1987 : /* we successfully drained the pipe; no need to read() again */
1988 2084306 : break;
1989 : }
1990 : /* else buffer wasn't big enough, so read again */
1991 : }
1992 2084306 : }
1993 :
1994 : #endif
1995 :
1996 : static void
1997 2 : ResOwnerReleaseWaitEventSet(Datum res)
1998 : {
1999 2 : WaitEventSet *set = (WaitEventSet *) DatumGetPointer(res);
2000 :
2001 : Assert(set->owner != NULL);
2002 2 : set->owner = NULL;
2003 2 : FreeWaitEventSet(set);
2004 2 : }
2005 :
2006 : #ifndef WIN32
2007 : /*
2008 : * Wake up my process if it's currently sleeping in WaitEventSetWaitBlock()
2009 : *
2010 : * NB: be sure to save and restore errno around it. (That's standard practice
2011 : * in most signal handlers, of course, but we used to omit it in handlers that
2012 : * only set a flag.) XXX
2013 : *
2014 : * NB: this function is called from critical sections and signal handlers so
2015 : * throwing an error is not a good idea.
2016 : *
2017 : * On Windows, Latch uses SetEvent directly and this is not used.
2018 : */
2019 : void
2020 238164 : WakeupMyProc(void)
2021 : {
2022 : #if defined(WAIT_USE_SELF_PIPE)
2023 : if (waiting)
2024 : sendSelfPipeByte();
2025 : #else
2026 238164 : if (waiting)
2027 238164 : kill(MyProcPid, SIGURG);
2028 : #endif
2029 238164 : }
2030 :
2031 : /* Similar to WakeupMyProc, but wake up another process */
2032 : void
2033 2036566 : WakeupOtherProc(int pid)
2034 : {
2035 2036566 : kill(pid, SIGURG);
2036 2036566 : }
2037 : #endif
|
