Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * waiteventset.c
4 : : * ppoll()/pselect() like abstraction
5 : : *
6 : : * WaitEvents are an abstraction for waiting for one or more events at a time.
7 : : * The waiting can be done in a race free fashion, similar ppoll() or
8 : : * pselect() (as opposed to plain poll()/select()).
9 : : *
10 : : * You can wait for:
11 : : * - a latch being set from another process or from signal handler in the same
12 : : * process (WL_LATCH_SET)
13 : : * - data to become readable or writeable on a socket (WL_SOCKET_*)
14 : : * - postmaster death (WL_POSTMASTER_DEATH or WL_EXIT_ON_PM_DEATH)
15 : : * - timeout (WL_TIMEOUT)
16 : : *
17 : : * Implementation
18 : : * --------------
19 : : *
20 : : * The poll() implementation uses the so-called self-pipe trick to overcome the
21 : : * race condition involved with poll() and setting a global flag in the signal
22 : : * handler. When a latch is set and the current process is waiting for it, the
23 : : * signal handler wakes up the poll() in WaitLatch by writing a byte to a pipe.
24 : : * A signal by itself doesn't interrupt poll() on all platforms, and even on
25 : : * platforms where it does, a signal that arrives just before the poll() call
26 : : * does not prevent poll() from entering sleep. An incoming byte on a pipe
27 : : * however reliably interrupts the sleep, and causes poll() to return
28 : : * immediately even if the signal arrives before poll() begins.
29 : : *
30 : : * The epoll() implementation overcomes the race with a different technique: it
31 : : * keeps SIGURG blocked and consumes from a signalfd() descriptor instead. We
32 : : * don't need to register a signal handler or create our own self-pipe. We
33 : : * assume that any system that has Linux epoll() also has Linux signalfd().
34 : : *
35 : : * The kqueue() implementation waits for SIGURG with EVFILT_SIGNAL.
36 : : *
37 : : * The Windows implementation uses Windows events that are inherited by all
38 : : * postmaster child processes. There's no need for the self-pipe trick there.
39 : : *
40 : : * Portions Copyright (c) 1996-2026, 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 : : #include "utils/wait_event.h"
81 : :
82 : : /*
83 : : * Select the fd readiness primitive to use. Normally the "most modern"
84 : : * primitive supported by the OS will be used, but for testing it can be
85 : : * useful to manually specify the used primitive. If desired, just add a
86 : : * define somewhere before this block.
87 : : */
88 : : #if defined(WAIT_USE_EPOLL) || defined(WAIT_USE_POLL) || \
89 : : defined(WAIT_USE_KQUEUE) || defined(WAIT_USE_WIN32)
90 : : /* don't overwrite manual choice */
91 : : #elif defined(HAVE_SYS_EPOLL_H)
92 : : #define WAIT_USE_EPOLL
93 : : #elif defined(HAVE_KQUEUE)
94 : : #define WAIT_USE_KQUEUE
95 : : #elif defined(HAVE_POLL)
96 : : #define WAIT_USE_POLL
97 : : #elif WIN32
98 : : #define WAIT_USE_WIN32
99 : : #else
100 : : #error "no wait set implementation available"
101 : : #endif
102 : :
103 : : /*
104 : : * By default, we use a self-pipe with poll() and a signalfd with epoll(), if
105 : : * available. For testing the choice can also be manually specified.
106 : : */
107 : : #if defined(WAIT_USE_POLL) || defined(WAIT_USE_EPOLL)
108 : : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
109 : : /* don't overwrite manual choice */
110 : : #elif defined(WAIT_USE_EPOLL) && defined(HAVE_SYS_SIGNALFD_H)
111 : : #define WAIT_USE_SIGNALFD
112 : : #else
113 : : #define WAIT_USE_SELF_PIPE
114 : : #endif
115 : : #endif
116 : :
117 : : /* typedef in waiteventset.h */
118 : : struct WaitEventSet
119 : : {
120 : : ResourceOwner owner;
121 : :
122 : : int nevents; /* number of registered events */
123 : : int nevents_space; /* maximum number of events in this set */
124 : :
125 : : /*
126 : : * Array, of nevents_space length, storing the definition of events this
127 : : * set is waiting for.
128 : : */
129 : : WaitEvent *events;
130 : :
131 : : /*
132 : : * If WL_LATCH_SET is specified in any wait event, latch is a pointer to
133 : : * said latch, and latch_pos the offset in the ->events array. This is
134 : : * useful because we check the state of the latch before performing doing
135 : : * syscalls related to waiting.
136 : : */
137 : : Latch *latch;
138 : : int latch_pos;
139 : :
140 : : /*
141 : : * WL_EXIT_ON_PM_DEATH is converted to WL_POSTMASTER_DEATH, but this flag
142 : : * is set so that we'll exit immediately if postmaster death is detected,
143 : : * instead of returning.
144 : : */
145 : : bool exit_on_postmaster_death;
146 : :
147 : : #if defined(WAIT_USE_EPOLL)
148 : : int epoll_fd;
149 : : /* epoll_wait returns events in a user provided arrays, allocate once */
150 : : struct epoll_event *epoll_ret_events;
151 : : #elif defined(WAIT_USE_KQUEUE)
152 : : int kqueue_fd;
153 : : /* kevent returns events in a user provided arrays, allocate once */
154 : : struct kevent *kqueue_ret_events;
155 : : bool report_postmaster_not_running;
156 : : #elif defined(WAIT_USE_POLL)
157 : : /* poll expects events to be waited on every poll() call, prepare once */
158 : : struct pollfd *pollfds;
159 : : #elif defined(WAIT_USE_WIN32)
160 : :
161 : : /*
162 : : * Array of windows events. The first element always contains
163 : : * pgwin32_signal_event, so the remaining elements are offset by one (i.e.
164 : : * event->pos + 1).
165 : : */
166 : : HANDLE *handles;
167 : : #endif
168 : : };
169 : :
170 : : #ifndef WIN32
171 : : /* Are we currently in WaitLatch? The signal handler would like to know. */
172 : : static volatile sig_atomic_t waiting = false;
173 : : #endif
174 : :
175 : : #ifdef WAIT_USE_SIGNALFD
176 : : /* On Linux, we'll receive SIGURG via a signalfd file descriptor. */
177 : : static int signal_fd = -1;
178 : : #endif
179 : :
180 : : #ifdef WAIT_USE_SELF_PIPE
181 : : /* Read and write ends of the self-pipe */
182 : : static int selfpipe_readfd = -1;
183 : : static int selfpipe_writefd = -1;
184 : :
185 : : /* Process owning the self-pipe --- needed for checking purposes */
186 : : static int selfpipe_owner_pid = 0;
187 : :
188 : : /* Private function prototypes */
189 : : static void latch_sigurg_handler(SIGNAL_ARGS);
190 : : static void sendSelfPipeByte(void);
191 : : #endif
192 : :
193 : : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
194 : : static void drain(void);
195 : : #endif
196 : :
197 : : #if defined(WAIT_USE_EPOLL)
198 : : static void WaitEventAdjustEpoll(WaitEventSet *set, WaitEvent *event, int action);
199 : : #elif defined(WAIT_USE_KQUEUE)
200 : : static void WaitEventAdjustKqueue(WaitEventSet *set, WaitEvent *event, int old_events);
201 : : #elif defined(WAIT_USE_POLL)
202 : : static void WaitEventAdjustPoll(WaitEventSet *set, WaitEvent *event);
203 : : #elif defined(WAIT_USE_WIN32)
204 : : static void WaitEventAdjustWin32(WaitEventSet *set, WaitEvent *event);
205 : : #endif
206 : :
207 : : static inline int WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
208 : : WaitEvent *occurred_events, int nevents);
209 : :
210 : : /* ResourceOwner support to hold WaitEventSets */
211 : : static void ResOwnerReleaseWaitEventSet(Datum res);
212 : :
213 : : static const ResourceOwnerDesc wait_event_set_resowner_desc =
214 : : {
215 : : .name = "WaitEventSet",
216 : : .release_phase = RESOURCE_RELEASE_AFTER_LOCKS,
217 : : .release_priority = RELEASE_PRIO_WAITEVENTSETS,
218 : : .ReleaseResource = ResOwnerReleaseWaitEventSet,
219 : : .DebugPrint = NULL
220 : : };
221 : :
222 : : /* Convenience wrappers over ResourceOwnerRemember/Forget */
223 : : static inline void
374 heikki.linnakangas@i 224 :CBC 73304 : ResourceOwnerRememberWaitEventSet(ResourceOwner owner, WaitEventSet *set)
225 : : {
226 : 73304 : ResourceOwnerRemember(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
227 : 73304 : }
228 : : static inline void
229 : 73303 : ResourceOwnerForgetWaitEventSet(ResourceOwner owner, WaitEventSet *set)
230 : : {
231 : 73303 : ResourceOwnerForget(owner, PointerGetDatum(set), &wait_event_set_resowner_desc);
232 : 73303 : }
233 : :
234 : :
235 : : /*
236 : : * Initialize the process-local wait event infrastructure.
237 : : *
238 : : * This must be called once during startup of any process that can wait on
239 : : * latches, before it issues any InitLatch() or OwnLatch() calls.
240 : : */
241 : : void
242 : 22976 : InitializeWaitEventSupport(void)
243 : : {
244 : : #if defined(WAIT_USE_SELF_PIPE)
245 : : int pipefd[2];
246 : :
247 : : if (IsUnderPostmaster)
248 : : {
249 : : /*
250 : : * We might have inherited connections to a self-pipe created by the
251 : : * postmaster. It's critical that child processes create their own
252 : : * self-pipes, of course, and we really want them to close the
253 : : * inherited FDs for safety's sake.
254 : : */
255 : : if (selfpipe_owner_pid != 0)
256 : : {
257 : : /* Assert we go through here but once in a child process */
258 : : Assert(selfpipe_owner_pid != MyProcPid);
259 : : /* Release postmaster's pipe FDs; ignore any error */
260 : : (void) close(selfpipe_readfd);
261 : : (void) close(selfpipe_writefd);
262 : : /* Clean up, just for safety's sake; we'll set these below */
263 : : selfpipe_readfd = selfpipe_writefd = -1;
264 : : selfpipe_owner_pid = 0;
265 : : /* Keep fd.c's accounting straight */
266 : : ReleaseExternalFD();
267 : : ReleaseExternalFD();
268 : : }
269 : : else
270 : : {
271 : : /*
272 : : * Postmaster didn't create a self-pipe ... or else we're in an
273 : : * EXEC_BACKEND build, in which case it doesn't matter since the
274 : : * postmaster's pipe FDs were closed by the action of FD_CLOEXEC.
275 : : * fd.c won't have state to clean up, either.
276 : : */
277 : : Assert(selfpipe_readfd == -1);
278 : : }
279 : : }
280 : : else
281 : : {
282 : : /* In postmaster or standalone backend, assert we do this but once */
283 : : Assert(selfpipe_readfd == -1);
284 : : Assert(selfpipe_owner_pid == 0);
285 : : }
286 : :
287 : : /*
288 : : * Set up the self-pipe that allows a signal handler to wake up the
289 : : * poll()/epoll_wait() in WaitLatch. Make the write-end non-blocking, so
290 : : * that SetLatch won't block if the event has already been set many times
291 : : * filling the kernel buffer. Make the read-end non-blocking too, so that
292 : : * we can easily clear the pipe by reading until EAGAIN or EWOULDBLOCK.
293 : : * Also, make both FDs close-on-exec, since we surely do not want any
294 : : * child processes messing with them.
295 : : */
296 : : if (pipe(pipefd) < 0)
297 : : elog(FATAL, "pipe() failed: %m");
298 : : if (fcntl(pipefd[0], F_SETFL, O_NONBLOCK) == -1)
299 : : elog(FATAL, "fcntl(F_SETFL) failed on read-end of self-pipe: %m");
300 : : if (fcntl(pipefd[1], F_SETFL, O_NONBLOCK) == -1)
301 : : elog(FATAL, "fcntl(F_SETFL) failed on write-end of self-pipe: %m");
302 : : if (fcntl(pipefd[0], F_SETFD, FD_CLOEXEC) == -1)
303 : : elog(FATAL, "fcntl(F_SETFD) failed on read-end of self-pipe: %m");
304 : : if (fcntl(pipefd[1], F_SETFD, FD_CLOEXEC) == -1)
305 : : elog(FATAL, "fcntl(F_SETFD) failed on write-end of self-pipe: %m");
306 : :
307 : : selfpipe_readfd = pipefd[0];
308 : : selfpipe_writefd = pipefd[1];
309 : : selfpipe_owner_pid = MyProcPid;
310 : :
311 : : /* Tell fd.c about these two long-lived FDs */
312 : : ReserveExternalFD();
313 : : ReserveExternalFD();
314 : :
315 : : pqsignal(SIGURG, latch_sigurg_handler);
316 : : #endif
317 : :
318 : : #ifdef WAIT_USE_SIGNALFD
319 : : sigset_t signalfd_mask;
320 : :
321 [ + + ]: 22976 : if (IsUnderPostmaster)
322 : : {
323 : : /*
324 : : * It would probably be safe to re-use the inherited signalfd since
325 : : * signalfds only see the current process's pending signals, but it
326 : : * seems less surprising to close it and create our own.
327 : : */
328 [ + - ]: 21792 : if (signal_fd != -1)
329 : : {
330 : : /* Release postmaster's signal FD; ignore any error */
331 : 21792 : (void) close(signal_fd);
332 : 21792 : signal_fd = -1;
333 : 21792 : ReleaseExternalFD();
334 : : }
335 : : }
336 : :
337 : : /* Block SIGURG, because we'll receive it through a signalfd. */
338 : 22976 : sigaddset(&UnBlockSig, SIGURG);
339 : :
340 : : /* Set up the signalfd to receive SIGURG notifications. */
341 : 22976 : sigemptyset(&signalfd_mask);
342 : 22976 : sigaddset(&signalfd_mask, SIGURG);
343 : 22976 : signal_fd = signalfd(-1, &signalfd_mask, SFD_NONBLOCK | SFD_CLOEXEC);
344 [ - + ]: 22976 : if (signal_fd < 0)
374 heikki.linnakangas@i 345 [ # # ]:UBC 0 : elog(FATAL, "signalfd() failed");
374 heikki.linnakangas@i 346 :CBC 22976 : ReserveExternalFD();
347 : : #endif
348 : :
349 : : #ifdef WAIT_USE_KQUEUE
350 : : /* Ignore SIGURG, because we'll receive it via kqueue. */
351 : : pqsignal(SIGURG, SIG_IGN);
352 : : #endif
353 : 22976 : }
354 : :
355 : : /*
356 : : * Create a WaitEventSet with space for nevents different events to wait for.
357 : : *
358 : : * These events can then be efficiently waited upon together, using
359 : : * WaitEventSetWait().
360 : : *
361 : : * The WaitEventSet is tracked by the given 'resowner'. Use NULL for session
362 : : * lifetime.
363 : : */
364 : : WaitEventSet *
365 : 124946 : CreateWaitEventSet(ResourceOwner resowner, int nevents)
366 : : {
367 : : WaitEventSet *set;
368 : : char *data;
369 : 124946 : Size sz = 0;
370 : :
371 : : /*
372 : : * Use MAXALIGN size/alignment to guarantee that later uses of memory are
373 : : * aligned correctly. E.g. epoll_event might need 8 byte alignment on some
374 : : * platforms, but earlier allocations like WaitEventSet and WaitEvent
375 : : * might not be sized to guarantee that when purely using sizeof().
376 : : */
377 : 124946 : sz += MAXALIGN(sizeof(WaitEventSet));
378 : 124946 : sz += MAXALIGN(sizeof(WaitEvent) * nevents);
379 : :
380 : : #if defined(WAIT_USE_EPOLL)
381 : 124946 : sz += MAXALIGN(sizeof(struct epoll_event) * nevents);
382 : : #elif defined(WAIT_USE_KQUEUE)
383 : : sz += MAXALIGN(sizeof(struct kevent) * nevents);
384 : : #elif defined(WAIT_USE_POLL)
385 : : sz += MAXALIGN(sizeof(struct pollfd) * nevents);
386 : : #elif defined(WAIT_USE_WIN32)
387 : : /* need space for the pgwin32_signal_event */
388 : : sz += MAXALIGN(sizeof(HANDLE) * (nevents + 1));
389 : : #endif
390 : :
391 [ + + ]: 124946 : if (resowner != NULL)
392 : 73304 : ResourceOwnerEnlarge(resowner);
393 : :
394 : 124946 : data = (char *) MemoryContextAllocZero(TopMemoryContext, sz);
395 : :
396 : 124946 : set = (WaitEventSet *) data;
397 : 124946 : data += MAXALIGN(sizeof(WaitEventSet));
398 : :
399 : 124946 : set->events = (WaitEvent *) data;
400 : 124946 : data += MAXALIGN(sizeof(WaitEvent) * nevents);
401 : :
402 : : #if defined(WAIT_USE_EPOLL)
403 : 124946 : set->epoll_ret_events = (struct epoll_event *) data;
404 : 124946 : data += MAXALIGN(sizeof(struct epoll_event) * nevents);
405 : : #elif defined(WAIT_USE_KQUEUE)
406 : : set->kqueue_ret_events = (struct kevent *) data;
407 : : data += MAXALIGN(sizeof(struct kevent) * nevents);
408 : : #elif defined(WAIT_USE_POLL)
409 : : set->pollfds = (struct pollfd *) data;
410 : : data += MAXALIGN(sizeof(struct pollfd) * nevents);
411 : : #elif defined(WAIT_USE_WIN32)
412 : : set->handles = (HANDLE) data;
413 : : data += MAXALIGN(sizeof(HANDLE) * nevents);
414 : : #endif
415 : :
416 : 124946 : set->latch = NULL;
417 : 124946 : set->nevents_space = nevents;
418 : 124946 : set->exit_on_postmaster_death = false;
419 : :
420 [ + + ]: 124946 : if (resowner != NULL)
421 : : {
422 : 73304 : ResourceOwnerRememberWaitEventSet(resowner, set);
423 : 73304 : set->owner = resowner;
424 : : }
425 : :
426 : : #if defined(WAIT_USE_EPOLL)
427 [ - + ]: 124946 : if (!AcquireExternalFD())
374 heikki.linnakangas@i 428 [ # # ]:UBC 0 : elog(ERROR, "AcquireExternalFD, for epoll_create1, failed: %m");
374 heikki.linnakangas@i 429 :CBC 124946 : set->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
430 [ - + ]: 124946 : if (set->epoll_fd < 0)
431 : : {
374 heikki.linnakangas@i 432 :UBC 0 : ReleaseExternalFD();
433 [ # # ]: 0 : elog(ERROR, "epoll_create1 failed: %m");
434 : : }
435 : : #elif defined(WAIT_USE_KQUEUE)
436 : : if (!AcquireExternalFD())
437 : : elog(ERROR, "AcquireExternalFD, for kqueue, failed: %m");
438 : : set->kqueue_fd = kqueue();
439 : : if (set->kqueue_fd < 0)
440 : : {
441 : : ReleaseExternalFD();
442 : : elog(ERROR, "kqueue failed: %m");
443 : : }
444 : : if (fcntl(set->kqueue_fd, F_SETFD, FD_CLOEXEC) == -1)
445 : : {
446 : : int save_errno = errno;
447 : :
448 : : close(set->kqueue_fd);
449 : : ReleaseExternalFD();
450 : : errno = save_errno;
451 : : elog(ERROR, "fcntl(F_SETFD) failed on kqueue descriptor: %m");
452 : : }
453 : : set->report_postmaster_not_running = false;
454 : : #elif defined(WAIT_USE_WIN32)
455 : :
456 : : /*
457 : : * To handle signals while waiting, we need to add a win32 specific event.
458 : : * We accounted for the additional event at the top of this routine. See
459 : : * port/win32/signal.c for more details.
460 : : *
461 : : * Note: pgwin32_signal_event should be first to ensure that it will be
462 : : * reported when multiple events are set. We want to guarantee that
463 : : * pending signals are serviced.
464 : : */
465 : : set->handles[0] = pgwin32_signal_event;
466 : : #endif
467 : :
374 heikki.linnakangas@i 468 :CBC 124946 : 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 : 87788 : FreeWaitEventSet(WaitEventSet *set)
482 : : {
483 [ + + ]: 87788 : if (set->owner)
484 : : {
485 : 73303 : ResourceOwnerForgetWaitEventSet(set->owner, set);
486 : 73303 : set->owner = NULL;
487 : : }
488 : :
489 : : #if defined(WAIT_USE_EPOLL)
490 : 87788 : close(set->epoll_fd);
491 : 87788 : 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 : 87788 : pfree(set);
518 : 87788 : }
519 : :
520 : : /*
521 : : * Free a previously created WaitEventSet in a child process after a fork().
522 : : */
523 : : void
524 : 18034 : FreeWaitEventSetAfterFork(WaitEventSet *set)
525 : : {
526 : : #if defined(WAIT_USE_EPOLL)
527 : 18034 : close(set->epoll_fd);
528 : 18034 : ReleaseExternalFD();
529 : : #elif defined(WAIT_USE_KQUEUE)
530 : : /* kqueues are not normally inherited by child processes */
531 : : ReleaseExternalFD();
532 : : #endif
533 : :
534 : 18034 : pfree(set);
535 : 18034 : }
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 : 349407 : AddWaitEventToSet(WaitEventSet *set, uint32 events, pgsocket fd, Latch *latch,
571 : : void *user_data)
572 : : {
573 : : WaitEvent *event;
574 : :
575 : : /* not enough space */
576 [ - + ]: 349407 : Assert(set->nevents < set->nevents_space);
577 : :
578 [ + + ]: 349407 : if (events == WL_EXIT_ON_PM_DEATH)
579 : : {
580 : 108653 : events = WL_POSTMASTER_DEATH;
581 : 108653 : set->exit_on_postmaster_death = true;
582 : : }
583 : :
584 [ + + ]: 349407 : if (latch)
585 : : {
586 [ - + ]: 124458 : if (latch->owner_pid != MyProcPid)
374 heikki.linnakangas@i 587 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on a latch owned by another process");
374 heikki.linnakangas@i 588 [ - + ]:CBC 124458 : if (set->latch)
374 heikki.linnakangas@i 589 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on more than one latch");
374 heikki.linnakangas@i 590 [ - + ]:CBC 124458 : if ((events & WL_LATCH_SET) != WL_LATCH_SET)
374 heikki.linnakangas@i 591 [ # # ]:UBC 0 : elog(ERROR, "latch events only support being set");
592 : : }
593 : : else
594 : : {
374 heikki.linnakangas@i 595 [ - + ]:CBC 224949 : if (events & WL_LATCH_SET)
374 heikki.linnakangas@i 596 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on latch without a specified latch");
597 : : }
598 : :
599 : : /* waiting for socket readiness without a socket indicates a bug */
374 heikki.linnakangas@i 600 [ + + - + ]:CBC 349407 : if (fd == PGINVALID_SOCKET && (events & WL_SOCKET_MASK))
374 heikki.linnakangas@i 601 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on socket event without a socket");
602 : :
374 heikki.linnakangas@i 603 :CBC 349407 : event = &set->events[set->nevents];
604 : 349407 : event->pos = set->nevents++;
605 : 349407 : event->fd = fd;
606 : 349407 : event->events = events;
607 : 349407 : event->user_data = user_data;
608 : : #ifdef WIN32
609 : : event->reset = false;
610 : : #endif
611 : :
612 [ + + ]: 349407 : if (events == WL_LATCH_SET)
613 : : {
614 : 124458 : set->latch = latch;
615 : 124458 : set->latch_pos = event->pos;
616 : : #if defined(WAIT_USE_SELF_PIPE)
617 : : event->fd = selfpipe_readfd;
618 : : #elif defined(WAIT_USE_SIGNALFD)
619 : 124458 : 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 [ + + ]: 224949 : else if (events == WL_POSTMASTER_DEATH)
628 : : {
629 : : #ifndef WIN32
630 : 122847 : 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 : 349407 : 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 : 349407 : 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 : 2376557 : 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 [ - + ]: 2376557 : Assert(pos < set->nevents);
664 : :
665 : 2376557 : 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 [ + + ]: 2376557 : if (event->events == WL_POSTMASTER_DEATH)
678 : : {
679 [ + + - + ]: 1030063 : if (events != WL_POSTMASTER_DEATH && events != WL_EXIT_ON_PM_DEATH)
374 heikki.linnakangas@i 680 [ # # ]:UBC 0 : elog(ERROR, "cannot remove postmaster death event");
374 heikki.linnakangas@i 681 :CBC 1030063 : set->exit_on_postmaster_death = ((events & WL_EXIT_ON_PM_DEATH) != 0);
682 : 1030063 : 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 [ + + ]: 1346494 : if (events == event->events &&
692 [ + + + + ]: 1321756 : (!(event->events & WL_LATCH_SET) || set->latch == latch))
693 : 1284747 : return;
694 : :
695 [ + + - + ]: 61747 : if (event->events & WL_LATCH_SET && events != event->events)
374 heikki.linnakangas@i 696 [ # # ]:UBC 0 : elog(ERROR, "cannot modify latch event");
697 : :
698 : : /* FIXME: validate event mask */
374 heikki.linnakangas@i 699 :CBC 61747 : event->events = events;
700 : :
701 [ + + ]: 61747 : if (events == WL_LATCH_SET)
702 : : {
703 [ + + - + ]: 37009 : if (latch && latch->owner_pid != MyProcPid)
374 heikki.linnakangas@i 704 [ # # ]:UBC 0 : elog(ERROR, "cannot wait on a latch owned by another process");
374 heikki.linnakangas@i 705 :CBC 37009 : 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 : 37009 : return;
719 : : #endif
720 : : }
721 : :
722 : : #if defined(WAIT_USE_EPOLL)
723 : 24738 : 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 : 374145 : 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 : 374145 : epoll_ev.data.ptr = event;
745 : : /* always wait for errors */
746 : 374145 : epoll_ev.events = EPOLLERR | EPOLLHUP;
747 : :
748 : : /* prepare pollfd entry once */
749 [ + + ]: 374145 : if (event->events == WL_LATCH_SET)
750 : : {
751 [ - + ]: 124458 : Assert(set->latch != NULL);
752 : 124458 : epoll_ev.events |= EPOLLIN;
753 : : }
754 [ + + ]: 249687 : else if (event->events == WL_POSTMASTER_DEATH)
755 : : {
756 : 122847 : epoll_ev.events |= EPOLLIN;
757 : : }
758 : : else
759 : : {
760 [ - + ]: 126840 : Assert(event->fd != PGINVALID_SOCKET);
761 [ - + ]: 126840 : Assert(event->events & (WL_SOCKET_READABLE |
762 : : WL_SOCKET_WRITEABLE |
763 : : WL_SOCKET_CLOSED));
764 : :
765 [ + + ]: 126840 : if (event->events & WL_SOCKET_READABLE)
766 : 110731 : epoll_ev.events |= EPOLLIN;
767 [ + + ]: 126840 : if (event->events & WL_SOCKET_WRITEABLE)
768 : 22525 : epoll_ev.events |= EPOLLOUT;
769 [ - + ]: 126840 : if (event->events & WL_SOCKET_CLOSED)
374 heikki.linnakangas@i 770 :UBC 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 : : */
374 heikki.linnakangas@i 778 :CBC 374145 : rc = epoll_ctl(set->epoll_fd, action, event->fd, &epoll_ev);
779 : :
780 [ - + ]: 374145 : if (rc < 0)
374 heikki.linnakangas@i 781 [ # # ]:UBC 0 : ereport(ERROR,
782 : : (errcode_for_socket_access(),
783 : : errmsg("%s() failed: %m",
784 : : "epoll_ctl")));
374 heikki.linnakangas@i 785 :CBC 374145 : }
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 : : StaticAssertDecl(WSA_INVALID_EVENT == NULL, "");
983 : :
984 : : static void
985 : : WaitEventAdjustWin32(WaitEventSet *set, WaitEvent *event)
986 : : {
987 : : HANDLE *handle = &set->handles[event->pos + 1];
988 : :
989 : : if (event->events == WL_LATCH_SET)
990 : : {
991 : : Assert(set->latch != NULL);
992 : : *handle = set->latch->event;
993 : : }
994 : : else if (event->events == WL_POSTMASTER_DEATH)
995 : : {
996 : : *handle = PostmasterHandle;
997 : : }
998 : : else
999 : : {
1000 : : int flags = FD_CLOSE; /* always check for errors/EOF */
1001 : :
1002 : : if (event->events & WL_SOCKET_READABLE)
1003 : : flags |= FD_READ;
1004 : : if (event->events & WL_SOCKET_WRITEABLE)
1005 : : flags |= FD_WRITE;
1006 : : if (event->events & WL_SOCKET_CONNECTED)
1007 : : flags |= FD_CONNECT;
1008 : : if (event->events & WL_SOCKET_ACCEPT)
1009 : : flags |= FD_ACCEPT;
1010 : :
1011 : : if (*handle == WSA_INVALID_EVENT)
1012 : : {
1013 : : *handle = WSACreateEvent();
1014 : : if (*handle == WSA_INVALID_EVENT)
1015 : : elog(ERROR, "failed to create event for socket: error code %d",
1016 : : WSAGetLastError());
1017 : : }
1018 : : if (WSAEventSelect(event->fd, *handle, flags) != 0)
1019 : : elog(ERROR, "failed to set up event for socket: error code %d",
1020 : : WSAGetLastError());
1021 : :
1022 : : Assert(event->fd != PGINVALID_SOCKET);
1023 : : }
1024 : : }
1025 : : #endif
1026 : :
1027 : : /*
1028 : : * Wait for events added to the set to happen, or until the timeout is
1029 : : * reached. At most nevents occurred events are returned.
1030 : : *
1031 : : * If timeout = -1, block until an event occurs; if 0, check sockets for
1032 : : * readiness, but don't block; if > 0, block for at most timeout milliseconds.
1033 : : *
1034 : : * Returns the number of events occurred, or 0 if the timeout was reached.
1035 : : *
1036 : : * Returned events will have the fd, pos, user_data fields set to the
1037 : : * values associated with the registered event.
1038 : : */
1039 : : int
1040 : 1447656 : WaitEventSetWait(WaitEventSet *set, long timeout,
1041 : : WaitEvent *occurred_events, int nevents,
1042 : : uint32 wait_event_info)
1043 : : {
1044 : 1447656 : int returned_events = 0;
1045 : : instr_time start_time;
1046 : : instr_time cur_time;
1047 : 1447656 : long cur_timeout = -1;
1048 : :
1049 [ - + ]: 1447656 : Assert(nevents > 0);
1050 : :
1051 : : /*
1052 : : * Initialize timeout if requested. We must record the current time so
1053 : : * that we can determine the remaining timeout if interrupted.
1054 : : */
1055 [ + + ]: 1447656 : if (timeout >= 0)
1056 : : {
1057 : 251308 : INSTR_TIME_SET_CURRENT(start_time);
1058 [ + - - + ]: 251308 : Assert(timeout >= 0 && timeout <= INT_MAX);
1059 : 251308 : cur_timeout = timeout;
1060 : : }
1061 : : else
1062 : 1196348 : INSTR_TIME_SET_ZERO(start_time);
1063 : :
1064 : 1447656 : pgstat_report_wait_start(wait_event_info);
1065 : :
1066 : : #ifndef WIN32
1067 : 1447656 : waiting = true;
1068 : : #else
1069 : : /* Ensure that signals are serviced even if latch is already set */
1070 : : pgwin32_dispatch_queued_signals();
1071 : : #endif
1072 [ + + ]: 2813335 : while (returned_events == 0)
1073 : : {
1074 : : int rc;
1075 : :
1076 : : /*
1077 : : * Check if the latch is set already first. If so, we either exit
1078 : : * immediately or ask the kernel for further events available right
1079 : : * now without waiting, depending on how many events the caller wants.
1080 : : *
1081 : : * If someone sets the latch between this and the
1082 : : * WaitEventSetWaitBlock() below, the setter will write a byte to the
1083 : : * pipe (or signal us and the signal handler will do that), and the
1084 : : * readiness routine will return immediately.
1085 : : *
1086 : : * On unix, If there's a pending byte in the self pipe, we'll notice
1087 : : * whenever blocking. Only clearing the pipe in that case avoids
1088 : : * having to drain it every time WaitLatchOrSocket() is used. Should
1089 : : * the pipe-buffer fill up we're still ok, because the pipe is in
1090 : : * nonblocking mode. It's unlikely for that to happen, because the
1091 : : * self pipe isn't filled unless we're blocking (waiting = true), or
1092 : : * from inside a signal handler in latch_sigurg_handler().
1093 : : *
1094 : : * On windows, we'll also notice if there's a pending event for the
1095 : : * latch when blocking, but there's no danger of anything filling up,
1096 : : * as "Setting an event that is already set has no effect.".
1097 : : *
1098 : : * Note: we assume that the kernel calls involved in latch management
1099 : : * will provide adequate synchronization on machines with weak memory
1100 : : * ordering, so that we cannot miss seeing is_set if a notification
1101 : : * has already been queued.
1102 : : */
1103 [ + + + + ]: 1499496 : if (set->latch && !set->latch->is_set)
1104 : : {
1105 : : /* about to sleep on a latch */
1106 : 1366893 : set->latch->maybe_sleeping = true;
1107 : 1366893 : pg_memory_barrier();
1108 : : /* and recheck */
1109 : : }
1110 : :
1111 [ + + + + ]: 1499496 : if (set->latch && set->latch->is_set)
1112 : : {
1113 : 132129 : occurred_events->fd = PGINVALID_SOCKET;
1114 : 132129 : occurred_events->pos = set->latch_pos;
1115 : 132129 : occurred_events->user_data =
1116 : 132129 : set->events[set->latch_pos].user_data;
1117 : 132129 : occurred_events->events = WL_LATCH_SET;
1118 : 132129 : occurred_events++;
1119 : 132129 : returned_events++;
1120 : :
1121 : : /* could have been set above */
1122 : 132129 : set->latch->maybe_sleeping = false;
1123 : :
1124 [ + + ]: 132129 : if (returned_events == nevents)
1125 : 104658 : break; /* output buffer full already */
1126 : :
1127 : : /*
1128 : : * Even though we already have an event, we'll poll just once with
1129 : : * zero timeout to see what non-latch events we can fit into the
1130 : : * output buffer at the same time.
1131 : : */
1132 : 27471 : cur_timeout = 0;
1133 : 27471 : timeout = 0;
1134 : : }
1135 : :
1136 : : /*
1137 : : * Wait for events using the readiness primitive chosen at the top of
1138 : : * this file. If -1 is returned, a timeout has occurred, if 0 we have
1139 : : * to retry, everything >= 1 is the number of returned events.
1140 : : */
1141 : 1394838 : rc = WaitEventSetWaitBlock(set, cur_timeout,
1142 : : occurred_events, nevents - returned_events);
1143 : :
1144 [ + + ]: 1394794 : if (set->latch &&
1145 [ + + ]: 1394295 : set->latch->maybe_sleeping)
1146 : 1366824 : set->latch->maybe_sleeping = false;
1147 : :
1148 [ + + ]: 1394794 : if (rc == -1)
1149 : 29111 : break; /* timeout occurred */
1150 : : else
1151 : 1365683 : returned_events += rc;
1152 : :
1153 : : /* If we're not done, update cur_timeout for next iteration */
1154 [ + + + + ]: 1365683 : if (returned_events == 0 && timeout >= 0)
1155 : : {
1156 : 40882 : INSTR_TIME_SET_CURRENT(cur_time);
1157 : 40882 : INSTR_TIME_SUBTRACT(cur_time, start_time);
1158 : 40882 : cur_timeout = timeout - (long) INSTR_TIME_GET_MILLISEC(cur_time);
1159 [ + + ]: 40882 : if (cur_timeout <= 0)
374 heikki.linnakangas@i 1160 :GBC 4 : break;
1161 : : }
1162 : : }
1163 : : #ifndef WIN32
374 heikki.linnakangas@i 1164 :CBC 1447612 : waiting = false;
1165 : : #endif
1166 : :
1167 : 1447612 : pgstat_report_wait_end();
1168 : :
1169 : 1447612 : return returned_events;
1170 : : }
1171 : :
1172 : :
1173 : : #if defined(WAIT_USE_EPOLL)
1174 : :
1175 : : /*
1176 : : * Wait using linux's epoll_wait(2).
1177 : : *
1178 : : * This is the preferable wait method, as several readiness notifications are
1179 : : * delivered, without having to iterate through all of set->events. The return
1180 : : * epoll_event struct contain a pointer to our events, making association
1181 : : * easy.
1182 : : */
1183 : : static inline int
1184 : 1394838 : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1185 : : WaitEvent *occurred_events, int nevents)
1186 : : {
1187 : 1394838 : int returned_events = 0;
1188 : : int rc;
1189 : : WaitEvent *cur_event;
1190 : : struct epoll_event *cur_epoll_event;
1191 : :
1192 : : /* Sleep */
1193 : 1394838 : rc = epoll_wait(set->epoll_fd, set->epoll_ret_events,
1194 : 1394838 : Min(nevents, set->nevents_space), cur_timeout);
1195 : :
1196 : : /* Check return code */
1197 [ + + ]: 1394838 : if (rc < 0)
1198 : : {
1199 : : /* EINTR is okay, otherwise complain */
1200 [ - + ]: 40691 : if (errno != EINTR)
1201 : : {
374 heikki.linnakangas@i 1202 :UBC 0 : waiting = false;
1203 [ # # ]: 0 : ereport(ERROR,
1204 : : (errcode_for_socket_access(),
1205 : : errmsg("%s() failed: %m",
1206 : : "epoll_wait")));
1207 : : }
374 heikki.linnakangas@i 1208 :CBC 40691 : return 0;
1209 : : }
1210 [ + + ]: 1354147 : else if (rc == 0)
1211 : : {
1212 : : /* timeout exceeded */
1213 : 29111 : return -1;
1214 : : }
1215 : :
1216 : : /*
1217 : : * At least one event occurred, iterate over the returned epoll events
1218 : : * until they're either all processed, or we've returned all the events
1219 : : * the caller desired.
1220 : : */
1221 : 1325036 : for (cur_epoll_event = set->epoll_ret_events;
1222 [ + + + - ]: 2650051 : cur_epoll_event < (set->epoll_ret_events + rc) &&
1223 : : returned_events < nevents;
1224 : 1325015 : cur_epoll_event++)
1225 : : {
1226 : : /* epoll's data pointer is set to the associated WaitEvent */
1227 : 1325059 : cur_event = (WaitEvent *) cur_epoll_event->data.ptr;
1228 : :
1229 : 1325059 : occurred_events->pos = cur_event->pos;
1230 : 1325059 : occurred_events->user_data = cur_event->user_data;
1231 : 1325059 : occurred_events->events = 0;
1232 : :
1233 [ + + ]: 1325059 : if (cur_event->events == WL_LATCH_SET &&
1234 [ + - ]: 981880 : cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP))
1235 : : {
1236 : : /* Drain the signalfd. */
1237 : 981880 : drain();
1238 : :
1239 [ + - + + : 981880 : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
+ + ]
1240 : : {
1241 : 943835 : occurred_events->fd = PGINVALID_SOCKET;
1242 : 943835 : occurred_events->events = WL_LATCH_SET;
1243 : 943835 : occurred_events++;
1244 : 943835 : returned_events++;
1245 : : }
1246 : : }
1247 [ + + ]: 343179 : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1248 [ + - ]: 44 : cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP))
1249 : : {
1250 : : /*
1251 : : * We expect an EPOLLHUP when the remote end is closed, but
1252 : : * because we don't expect the pipe to become readable or to have
1253 : : * any errors either, treat those cases as postmaster death, too.
1254 : : *
1255 : : * Be paranoid about a spurious event signaling the postmaster as
1256 : : * being dead. There have been reports about that happening with
1257 : : * older primitives (select(2) to be specific), and a spurious
1258 : : * WL_POSTMASTER_DEATH event would be painful. Re-checking doesn't
1259 : : * cost much.
1260 : : */
1261 [ + - ]: 44 : if (!PostmasterIsAliveInternal())
1262 : : {
1263 [ + - ]: 44 : if (set->exit_on_postmaster_death)
1264 : 44 : proc_exit(1);
374 heikki.linnakangas@i 1265 :UBC 0 : occurred_events->fd = PGINVALID_SOCKET;
1266 : 0 : occurred_events->events = WL_POSTMASTER_DEATH;
1267 : 0 : occurred_events++;
1268 : 0 : returned_events++;
1269 : : }
1270 : : }
374 heikki.linnakangas@i 1271 [ + - ]:CBC 343135 : else if (cur_event->events & (WL_SOCKET_READABLE |
1272 : : WL_SOCKET_WRITEABLE |
1273 : : WL_SOCKET_CLOSED))
1274 : : {
1275 [ - + ]: 343135 : Assert(cur_event->fd != PGINVALID_SOCKET);
1276 : :
1277 [ + + ]: 343135 : if ((cur_event->events & WL_SOCKET_READABLE) &&
1278 [ + + ]: 324068 : (cur_epoll_event->events & (EPOLLIN | EPOLLERR | EPOLLHUP)))
1279 : : {
1280 : : /* data available in socket, or EOF */
1281 : 309426 : occurred_events->events |= WL_SOCKET_READABLE;
1282 : : }
1283 : :
1284 [ + + ]: 343135 : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1285 [ + + ]: 54135 : (cur_epoll_event->events & (EPOLLOUT | EPOLLERR | EPOLLHUP)))
1286 : : {
1287 : : /* writable, or EOF */
1288 : 53690 : occurred_events->events |= WL_SOCKET_WRITEABLE;
1289 : : }
1290 : :
1291 [ - + ]: 343135 : if ((cur_event->events & WL_SOCKET_CLOSED) &&
374 heikki.linnakangas@i 1292 [ # # ]:UBC 0 : (cur_epoll_event->events & (EPOLLRDHUP | EPOLLERR | EPOLLHUP)))
1293 : : {
1294 : : /* remote peer shut down, or error */
1295 : 0 : occurred_events->events |= WL_SOCKET_CLOSED;
1296 : : }
1297 : :
374 heikki.linnakangas@i 1298 [ + - ]:CBC 343135 : if (occurred_events->events != 0)
1299 : : {
1300 : 343135 : occurred_events->fd = cur_event->fd;
1301 : 343135 : occurred_events++;
1302 : 343135 : returned_events++;
1303 : : }
1304 : : }
1305 : : }
1306 : :
1307 : 1324992 : return returned_events;
1308 : : }
1309 : :
1310 : : #elif defined(WAIT_USE_KQUEUE)
1311 : :
1312 : : /*
1313 : : * Wait using kevent(2) on BSD-family systems and macOS.
1314 : : *
1315 : : * For now this mirrors the epoll code, but in future it could modify the fd
1316 : : * set in the same call to kevent as it uses for waiting instead of doing that
1317 : : * with separate system calls.
1318 : : */
1319 : : static int
1320 : : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1321 : : WaitEvent *occurred_events, int nevents)
1322 : : {
1323 : : int returned_events = 0;
1324 : : int rc;
1325 : : WaitEvent *cur_event;
1326 : : struct kevent *cur_kqueue_event;
1327 : : struct timespec timeout;
1328 : : struct timespec *timeout_p;
1329 : :
1330 : : if (cur_timeout < 0)
1331 : : timeout_p = NULL;
1332 : : else
1333 : : {
1334 : : timeout.tv_sec = cur_timeout / 1000;
1335 : : timeout.tv_nsec = (cur_timeout % 1000) * 1000000;
1336 : : timeout_p = &timeout;
1337 : : }
1338 : :
1339 : : /*
1340 : : * Report postmaster events discovered by WaitEventAdjustKqueue() or an
1341 : : * earlier call to WaitEventSetWait().
1342 : : */
1343 : : if (unlikely(set->report_postmaster_not_running))
1344 : : {
1345 : : if (set->exit_on_postmaster_death)
1346 : : proc_exit(1);
1347 : : occurred_events->fd = PGINVALID_SOCKET;
1348 : : occurred_events->events = WL_POSTMASTER_DEATH;
1349 : : return 1;
1350 : : }
1351 : :
1352 : : /* Sleep */
1353 : : rc = kevent(set->kqueue_fd, NULL, 0,
1354 : : set->kqueue_ret_events,
1355 : : Min(nevents, set->nevents_space),
1356 : : timeout_p);
1357 : :
1358 : : /* Check return code */
1359 : : if (rc < 0)
1360 : : {
1361 : : /* EINTR is okay, otherwise complain */
1362 : : if (errno != EINTR)
1363 : : {
1364 : : waiting = false;
1365 : : ereport(ERROR,
1366 : : (errcode_for_socket_access(),
1367 : : errmsg("%s() failed: %m",
1368 : : "kevent")));
1369 : : }
1370 : : return 0;
1371 : : }
1372 : : else if (rc == 0)
1373 : : {
1374 : : /* timeout exceeded */
1375 : : return -1;
1376 : : }
1377 : :
1378 : : /*
1379 : : * At least one event occurred, iterate over the returned kqueue events
1380 : : * until they're either all processed, or we've returned all the events
1381 : : * the caller desired.
1382 : : */
1383 : : for (cur_kqueue_event = set->kqueue_ret_events;
1384 : : cur_kqueue_event < (set->kqueue_ret_events + rc) &&
1385 : : returned_events < nevents;
1386 : : cur_kqueue_event++)
1387 : : {
1388 : : /* kevent's udata points to the associated WaitEvent */
1389 : : cur_event = AccessWaitEvent(cur_kqueue_event);
1390 : :
1391 : : occurred_events->pos = cur_event->pos;
1392 : : occurred_events->user_data = cur_event->user_data;
1393 : : occurred_events->events = 0;
1394 : :
1395 : : if (cur_event->events == WL_LATCH_SET &&
1396 : : cur_kqueue_event->filter == EVFILT_SIGNAL)
1397 : : {
1398 : : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1399 : : {
1400 : : occurred_events->fd = PGINVALID_SOCKET;
1401 : : occurred_events->events = WL_LATCH_SET;
1402 : : occurred_events++;
1403 : : returned_events++;
1404 : : }
1405 : : }
1406 : : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1407 : : cur_kqueue_event->filter == EVFILT_PROC &&
1408 : : (cur_kqueue_event->fflags & NOTE_EXIT) != 0)
1409 : : {
1410 : : /*
1411 : : * The kernel will tell this kqueue object only once about the
1412 : : * exit of the postmaster, so let's remember that for next time so
1413 : : * that we provide level-triggered semantics.
1414 : : */
1415 : : set->report_postmaster_not_running = true;
1416 : :
1417 : : if (set->exit_on_postmaster_death)
1418 : : proc_exit(1);
1419 : : occurred_events->fd = PGINVALID_SOCKET;
1420 : : occurred_events->events = WL_POSTMASTER_DEATH;
1421 : : occurred_events++;
1422 : : returned_events++;
1423 : : }
1424 : : else if (cur_event->events & (WL_SOCKET_READABLE |
1425 : : WL_SOCKET_WRITEABLE |
1426 : : WL_SOCKET_CLOSED))
1427 : : {
1428 : : Assert(cur_event->fd >= 0);
1429 : :
1430 : : if ((cur_event->events & WL_SOCKET_READABLE) &&
1431 : : (cur_kqueue_event->filter == EVFILT_READ))
1432 : : {
1433 : : /* readable, or EOF */
1434 : : occurred_events->events |= WL_SOCKET_READABLE;
1435 : : }
1436 : :
1437 : : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1438 : : (cur_kqueue_event->filter == EVFILT_READ) &&
1439 : : (cur_kqueue_event->flags & EV_EOF))
1440 : : {
1441 : : /* the remote peer has shut down */
1442 : : occurred_events->events |= WL_SOCKET_CLOSED;
1443 : : }
1444 : :
1445 : : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1446 : : (cur_kqueue_event->filter == EVFILT_WRITE))
1447 : : {
1448 : : /* writable, or EOF */
1449 : : occurred_events->events |= WL_SOCKET_WRITEABLE;
1450 : : }
1451 : :
1452 : : if (occurred_events->events != 0)
1453 : : {
1454 : : occurred_events->fd = cur_event->fd;
1455 : : occurred_events++;
1456 : : returned_events++;
1457 : : }
1458 : : }
1459 : : }
1460 : :
1461 : : return returned_events;
1462 : : }
1463 : :
1464 : : #elif defined(WAIT_USE_POLL)
1465 : :
1466 : : /*
1467 : : * Wait using poll(2).
1468 : : *
1469 : : * This allows to receive readiness notifications for several events at once,
1470 : : * but requires iterating through all of set->pollfds.
1471 : : */
1472 : : static inline int
1473 : : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1474 : : WaitEvent *occurred_events, int nevents)
1475 : : {
1476 : : int returned_events = 0;
1477 : : int rc;
1478 : : WaitEvent *cur_event;
1479 : : struct pollfd *cur_pollfd;
1480 : :
1481 : : /* Sleep */
1482 : : rc = poll(set->pollfds, set->nevents, cur_timeout);
1483 : :
1484 : : /* Check return code */
1485 : : if (rc < 0)
1486 : : {
1487 : : /* EINTR is okay, otherwise complain */
1488 : : if (errno != EINTR)
1489 : : {
1490 : : waiting = false;
1491 : : ereport(ERROR,
1492 : : (errcode_for_socket_access(),
1493 : : errmsg("%s() failed: %m",
1494 : : "poll")));
1495 : : }
1496 : : return 0;
1497 : : }
1498 : : else if (rc == 0)
1499 : : {
1500 : : /* timeout exceeded */
1501 : : return -1;
1502 : : }
1503 : :
1504 : : for (cur_event = set->events, cur_pollfd = set->pollfds;
1505 : : cur_event < (set->events + set->nevents) &&
1506 : : returned_events < nevents;
1507 : : cur_event++, cur_pollfd++)
1508 : : {
1509 : : /* no activity on this FD, skip */
1510 : : if (cur_pollfd->revents == 0)
1511 : : continue;
1512 : :
1513 : : occurred_events->pos = cur_event->pos;
1514 : : occurred_events->user_data = cur_event->user_data;
1515 : : occurred_events->events = 0;
1516 : :
1517 : : if (cur_event->events == WL_LATCH_SET &&
1518 : : (cur_pollfd->revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL)))
1519 : : {
1520 : : /* There's data in the self-pipe, clear it. */
1521 : : drain();
1522 : :
1523 : : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1524 : : {
1525 : : occurred_events->fd = PGINVALID_SOCKET;
1526 : : occurred_events->events = WL_LATCH_SET;
1527 : : occurred_events++;
1528 : : returned_events++;
1529 : : }
1530 : : }
1531 : : else if (cur_event->events == WL_POSTMASTER_DEATH &&
1532 : : (cur_pollfd->revents & (POLLIN | POLLHUP | POLLERR | POLLNVAL)))
1533 : : {
1534 : : /*
1535 : : * We expect a POLLHUP when the remote end is closed, but because
1536 : : * we don't expect the pipe to become readable or to have any
1537 : : * errors either, treat those cases as postmaster death, too.
1538 : : *
1539 : : * Be paranoid about a spurious event signaling the postmaster as
1540 : : * being dead. There have been reports about that happening with
1541 : : * older primitives (select(2) to be specific), and a spurious
1542 : : * WL_POSTMASTER_DEATH event would be painful. Re-checking
1543 : : * doesn't cost much.
1544 : : */
1545 : : if (!PostmasterIsAliveInternal())
1546 : : {
1547 : : if (set->exit_on_postmaster_death)
1548 : : proc_exit(1);
1549 : : occurred_events->fd = PGINVALID_SOCKET;
1550 : : occurred_events->events = WL_POSTMASTER_DEATH;
1551 : : occurred_events++;
1552 : : returned_events++;
1553 : : }
1554 : : }
1555 : : else if (cur_event->events & (WL_SOCKET_READABLE |
1556 : : WL_SOCKET_WRITEABLE |
1557 : : WL_SOCKET_CLOSED))
1558 : : {
1559 : : int errflags = POLLHUP | POLLERR | POLLNVAL;
1560 : :
1561 : : Assert(cur_event->fd >= PGINVALID_SOCKET);
1562 : :
1563 : : if ((cur_event->events & WL_SOCKET_READABLE) &&
1564 : : (cur_pollfd->revents & (POLLIN | errflags)))
1565 : : {
1566 : : /* data available in socket, or EOF */
1567 : : occurred_events->events |= WL_SOCKET_READABLE;
1568 : : }
1569 : :
1570 : : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1571 : : (cur_pollfd->revents & (POLLOUT | errflags)))
1572 : : {
1573 : : /* writeable, or EOF */
1574 : : occurred_events->events |= WL_SOCKET_WRITEABLE;
1575 : : }
1576 : :
1577 : : #ifdef POLLRDHUP
1578 : : if ((cur_event->events & WL_SOCKET_CLOSED) &&
1579 : : (cur_pollfd->revents & (POLLRDHUP | errflags)))
1580 : : {
1581 : : /* remote peer closed, or error */
1582 : : occurred_events->events |= WL_SOCKET_CLOSED;
1583 : : }
1584 : : #endif
1585 : :
1586 : : if (occurred_events->events != 0)
1587 : : {
1588 : : occurred_events->fd = cur_event->fd;
1589 : : occurred_events++;
1590 : : returned_events++;
1591 : : }
1592 : : }
1593 : : }
1594 : : return returned_events;
1595 : : }
1596 : :
1597 : : #elif defined(WAIT_USE_WIN32)
1598 : :
1599 : : /*
1600 : : * Wait using Windows' WaitForMultipleObjects(). Each call only "consumes" one
1601 : : * event, so we keep calling until we've filled up our output buffer to match
1602 : : * the behavior of the other implementations.
1603 : : *
1604 : : * https://blogs.msdn.microsoft.com/oldnewthing/20150409-00/?p=44273
1605 : : */
1606 : : static inline int
1607 : : WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
1608 : : WaitEvent *occurred_events, int nevents)
1609 : : {
1610 : : int returned_events = 0;
1611 : : DWORD rc;
1612 : : WaitEvent *cur_event;
1613 : :
1614 : : /* Reset any wait events that need it */
1615 : : for (cur_event = set->events;
1616 : : cur_event < (set->events + set->nevents);
1617 : : cur_event++)
1618 : : {
1619 : : if (cur_event->reset)
1620 : : {
1621 : : WaitEventAdjustWin32(set, cur_event);
1622 : : cur_event->reset = false;
1623 : : }
1624 : :
1625 : : /*
1626 : : * We associate the socket with a new event handle for each
1627 : : * WaitEventSet. FD_CLOSE is only generated once if the other end
1628 : : * closes gracefully. Therefore we might miss the FD_CLOSE
1629 : : * notification, if it was delivered to another event after we stopped
1630 : : * waiting for it. Close that race by peeking for EOF after setting
1631 : : * up this handle to receive notifications, and before entering the
1632 : : * sleep.
1633 : : *
1634 : : * XXX If we had one event handle for the lifetime of a socket, we
1635 : : * wouldn't need this.
1636 : : */
1637 : : if (cur_event->events & WL_SOCKET_READABLE)
1638 : : {
1639 : : char c;
1640 : : WSABUF buf;
1641 : : DWORD received;
1642 : : DWORD flags;
1643 : :
1644 : : buf.buf = &c;
1645 : : buf.len = 1;
1646 : : flags = MSG_PEEK;
1647 : : if (WSARecv(cur_event->fd, &buf, 1, &received, &flags, NULL, NULL) == 0)
1648 : : {
1649 : : occurred_events->pos = cur_event->pos;
1650 : : occurred_events->user_data = cur_event->user_data;
1651 : : occurred_events->events = WL_SOCKET_READABLE;
1652 : : occurred_events->fd = cur_event->fd;
1653 : : return 1;
1654 : : }
1655 : : }
1656 : :
1657 : : /*
1658 : : * Windows does not guarantee to log an FD_WRITE network event
1659 : : * indicating that more data can be sent unless the previous send()
1660 : : * failed with WSAEWOULDBLOCK. While our caller might well have made
1661 : : * such a call, we cannot assume that here. Therefore, if waiting for
1662 : : * write-ready, force the issue by doing a dummy send(). If the dummy
1663 : : * send() succeeds, assume that the socket is in fact write-ready, and
1664 : : * return immediately. Also, if it fails with something other than
1665 : : * WSAEWOULDBLOCK, return a write-ready indication to let our caller
1666 : : * deal with the error condition.
1667 : : */
1668 : : if (cur_event->events & WL_SOCKET_WRITEABLE)
1669 : : {
1670 : : char c;
1671 : : WSABUF buf;
1672 : : DWORD sent;
1673 : : int r;
1674 : :
1675 : : buf.buf = &c;
1676 : : buf.len = 0;
1677 : :
1678 : : r = WSASend(cur_event->fd, &buf, 1, &sent, 0, NULL, NULL);
1679 : : if (r == 0 || WSAGetLastError() != WSAEWOULDBLOCK)
1680 : : {
1681 : : occurred_events->pos = cur_event->pos;
1682 : : occurred_events->user_data = cur_event->user_data;
1683 : : occurred_events->events = WL_SOCKET_WRITEABLE;
1684 : : occurred_events->fd = cur_event->fd;
1685 : : return 1;
1686 : : }
1687 : : }
1688 : : }
1689 : :
1690 : : /*
1691 : : * Sleep.
1692 : : *
1693 : : * Need to wait for ->nevents + 1, because signal handle is in [0].
1694 : : */
1695 : : rc = WaitForMultipleObjects(set->nevents + 1, set->handles, FALSE,
1696 : : cur_timeout);
1697 : :
1698 : : /* Check return code */
1699 : : if (rc == WAIT_FAILED)
1700 : : elog(ERROR, "WaitForMultipleObjects() failed: error code %lu",
1701 : : GetLastError());
1702 : : else if (rc == WAIT_TIMEOUT)
1703 : : {
1704 : : /* timeout exceeded */
1705 : : return -1;
1706 : : }
1707 : :
1708 : : if (rc == WAIT_OBJECT_0)
1709 : : {
1710 : : /* Service newly-arrived signals */
1711 : : pgwin32_dispatch_queued_signals();
1712 : : return 0; /* retry */
1713 : : }
1714 : :
1715 : : /*
1716 : : * With an offset of one, due to the always present pgwin32_signal_event,
1717 : : * the handle offset directly corresponds to a wait event.
1718 : : */
1719 : : cur_event = (WaitEvent *) &set->events[rc - WAIT_OBJECT_0 - 1];
1720 : :
1721 : : for (;;)
1722 : : {
1723 : : int next_pos;
1724 : : int count;
1725 : :
1726 : : occurred_events->pos = cur_event->pos;
1727 : : occurred_events->user_data = cur_event->user_data;
1728 : : occurred_events->events = 0;
1729 : :
1730 : : if (cur_event->events == WL_LATCH_SET)
1731 : : {
1732 : : /*
1733 : : * We cannot use set->latch->event to reset the fired event if we
1734 : : * aren't waiting on this latch now.
1735 : : */
1736 : : if (!ResetEvent(set->handles[cur_event->pos + 1]))
1737 : : elog(ERROR, "ResetEvent failed: error code %lu", GetLastError());
1738 : :
1739 : : if (set->latch && set->latch->maybe_sleeping && set->latch->is_set)
1740 : : {
1741 : : occurred_events->fd = PGINVALID_SOCKET;
1742 : : occurred_events->events = WL_LATCH_SET;
1743 : : occurred_events++;
1744 : : returned_events++;
1745 : : }
1746 : : }
1747 : : else if (cur_event->events == WL_POSTMASTER_DEATH)
1748 : : {
1749 : : /*
1750 : : * Postmaster apparently died. Since the consequences of falsely
1751 : : * returning WL_POSTMASTER_DEATH could be pretty unpleasant, we
1752 : : * take the trouble to positively verify this with
1753 : : * PostmasterIsAlive(), even though there is no known reason to
1754 : : * think that the event could be falsely set on Windows.
1755 : : */
1756 : : if (!PostmasterIsAliveInternal())
1757 : : {
1758 : : if (set->exit_on_postmaster_death)
1759 : : proc_exit(1);
1760 : : occurred_events->fd = PGINVALID_SOCKET;
1761 : : occurred_events->events = WL_POSTMASTER_DEATH;
1762 : : occurred_events++;
1763 : : returned_events++;
1764 : : }
1765 : : }
1766 : : else if (cur_event->events & WL_SOCKET_MASK)
1767 : : {
1768 : : WSANETWORKEVENTS resEvents;
1769 : : HANDLE handle = set->handles[cur_event->pos + 1];
1770 : :
1771 : : Assert(cur_event->fd);
1772 : :
1773 : : occurred_events->fd = cur_event->fd;
1774 : :
1775 : : ZeroMemory(&resEvents, sizeof(resEvents));
1776 : : if (WSAEnumNetworkEvents(cur_event->fd, handle, &resEvents) != 0)
1777 : : elog(ERROR, "failed to enumerate network events: error code %d",
1778 : : WSAGetLastError());
1779 : : if ((cur_event->events & WL_SOCKET_READABLE) &&
1780 : : (resEvents.lNetworkEvents & FD_READ))
1781 : : {
1782 : : /* data available in socket */
1783 : : occurred_events->events |= WL_SOCKET_READABLE;
1784 : :
1785 : : /*------
1786 : : * WaitForMultipleObjects doesn't guarantee that a read event
1787 : : * will be returned if the latch is set at the same time. Even
1788 : : * if it did, the caller might drop that event expecting it to
1789 : : * reoccur on next call. So, we must force the event to be
1790 : : * reset if this WaitEventSet is used again in order to avoid
1791 : : * an indefinite hang.
1792 : : *
1793 : : * Refer
1794 : : * https://msdn.microsoft.com/en-us/library/windows/desktop/ms741576(v=vs.85).aspx
1795 : : * for the behavior of socket events.
1796 : : *------
1797 : : */
1798 : : cur_event->reset = true;
1799 : : }
1800 : : if ((cur_event->events & WL_SOCKET_WRITEABLE) &&
1801 : : (resEvents.lNetworkEvents & FD_WRITE))
1802 : : {
1803 : : /* writeable */
1804 : : occurred_events->events |= WL_SOCKET_WRITEABLE;
1805 : : }
1806 : : if ((cur_event->events & WL_SOCKET_CONNECTED) &&
1807 : : (resEvents.lNetworkEvents & FD_CONNECT))
1808 : : {
1809 : : /* connected */
1810 : : occurred_events->events |= WL_SOCKET_CONNECTED;
1811 : : }
1812 : : if ((cur_event->events & WL_SOCKET_ACCEPT) &&
1813 : : (resEvents.lNetworkEvents & FD_ACCEPT))
1814 : : {
1815 : : /* incoming connection could be accepted */
1816 : : occurred_events->events |= WL_SOCKET_ACCEPT;
1817 : : }
1818 : : if (resEvents.lNetworkEvents & FD_CLOSE)
1819 : : {
1820 : : /* EOF/error, so signal all caller-requested socket flags */
1821 : : occurred_events->events |= (cur_event->events & WL_SOCKET_MASK);
1822 : : }
1823 : :
1824 : : if (occurred_events->events != 0)
1825 : : {
1826 : : occurred_events++;
1827 : : returned_events++;
1828 : : }
1829 : : }
1830 : :
1831 : : /* Is the output buffer full? */
1832 : : if (returned_events == nevents)
1833 : : break;
1834 : :
1835 : : /* Have we run out of possible events? */
1836 : : next_pos = cur_event->pos + 1;
1837 : : if (next_pos == set->nevents)
1838 : : break;
1839 : :
1840 : : /*
1841 : : * Poll the rest of the event handles in the array starting at
1842 : : * next_pos being careful to skip over the initial signal handle too.
1843 : : * This time we use a zero timeout.
1844 : : */
1845 : : count = set->nevents - next_pos;
1846 : : rc = WaitForMultipleObjects(count,
1847 : : set->handles + 1 + next_pos,
1848 : : false,
1849 : : 0);
1850 : :
1851 : : /*
1852 : : * We don't distinguish between errors and WAIT_TIMEOUT here because
1853 : : * we already have events to report.
1854 : : */
1855 : : if (rc < WAIT_OBJECT_0 || rc >= WAIT_OBJECT_0 + count)
1856 : : break;
1857 : :
1858 : : /* We have another event to decode. */
1859 : : cur_event = &set->events[next_pos + (rc - WAIT_OBJECT_0)];
1860 : : }
1861 : :
1862 : : return returned_events;
1863 : : }
1864 : : #endif
1865 : :
1866 : : /*
1867 : : * Return whether the current build options can report WL_SOCKET_CLOSED.
1868 : : */
1869 : : bool
1870 : 1184 : WaitEventSetCanReportClosed(void)
1871 : : {
1872 : : #if (defined(WAIT_USE_POLL) && defined(POLLRDHUP)) || \
1873 : : defined(WAIT_USE_EPOLL) || \
1874 : : defined(WAIT_USE_KQUEUE)
1875 : 1184 : return true;
1876 : : #else
1877 : : return false;
1878 : : #endif
1879 : : }
1880 : :
1881 : : /*
1882 : : * Get the number of wait events registered in a given WaitEventSet.
1883 : : */
1884 : : int
1885 : 381 : GetNumRegisteredWaitEvents(WaitEventSet *set)
1886 : : {
1887 : 381 : return set->nevents;
1888 : : }
1889 : :
1890 : : #if defined(WAIT_USE_SELF_PIPE)
1891 : :
1892 : : /*
1893 : : * SetLatch uses SIGURG to wake up the process waiting on the latch.
1894 : : *
1895 : : * Wake up WaitLatch, if we're waiting.
1896 : : */
1897 : : static void
1898 : : latch_sigurg_handler(SIGNAL_ARGS)
1899 : : {
1900 : : if (waiting)
1901 : : sendSelfPipeByte();
1902 : : }
1903 : :
1904 : : /* Send one byte to the self-pipe, to wake up WaitLatch */
1905 : : static void
1906 : : sendSelfPipeByte(void)
1907 : : {
1908 : : int rc;
1909 : : char dummy = 0;
1910 : :
1911 : : retry:
1912 : : rc = write(selfpipe_writefd, &dummy, 1);
1913 : : if (rc < 0)
1914 : : {
1915 : : /* If interrupted by signal, just retry */
1916 : : if (errno == EINTR)
1917 : : goto retry;
1918 : :
1919 : : /*
1920 : : * If the pipe is full, we don't need to retry, the data that's there
1921 : : * already is enough to wake up WaitLatch.
1922 : : */
1923 : : if (errno == EAGAIN || errno == EWOULDBLOCK)
1924 : : return;
1925 : :
1926 : : /*
1927 : : * Oops, the write() failed for some other reason. We might be in a
1928 : : * signal handler, so it's not safe to elog(). We have no choice but
1929 : : * silently ignore the error.
1930 : : */
1931 : : return;
1932 : : }
1933 : : }
1934 : :
1935 : : #endif
1936 : :
1937 : : #if defined(WAIT_USE_SELF_PIPE) || defined(WAIT_USE_SIGNALFD)
1938 : :
1939 : : /*
1940 : : * Read all available data from self-pipe or signalfd.
1941 : : *
1942 : : * Note: this is only called when waiting = true. If it fails and doesn't
1943 : : * return, it must reset that flag first (though ideally, this will never
1944 : : * happen).
1945 : : */
1946 : : static void
1947 : 981880 : drain(void)
1948 : : {
1949 : : char buf[1024];
1950 : : int rc;
1951 : : int fd;
1952 : :
1953 : : #ifdef WAIT_USE_SELF_PIPE
1954 : : fd = selfpipe_readfd;
1955 : : #else
1956 : 981880 : fd = signal_fd;
1957 : : #endif
1958 : :
1959 : : for (;;)
1960 : : {
1961 : 981880 : rc = read(fd, buf, sizeof(buf));
1962 [ - + ]: 981880 : if (rc < 0)
1963 : : {
374 heikki.linnakangas@i 1964 [ # # # # ]:UBC 0 : if (errno == EAGAIN || errno == EWOULDBLOCK)
1965 : : break; /* the descriptor is empty */
1966 [ # # ]: 0 : else if (errno == EINTR)
1967 : 0 : continue; /* retry */
1968 : : else
1969 : : {
1970 : 0 : waiting = false;
1971 : : #ifdef WAIT_USE_SELF_PIPE
1972 : : elog(ERROR, "read() on self-pipe failed: %m");
1973 : : #else
1974 [ # # ]: 0 : elog(ERROR, "read() on signalfd failed: %m");
1975 : : #endif
1976 : : }
1977 : : }
374 heikki.linnakangas@i 1978 [ - + ]:CBC 981880 : else if (rc == 0)
1979 : : {
374 heikki.linnakangas@i 1980 :UBC 0 : waiting = false;
1981 : : #ifdef WAIT_USE_SELF_PIPE
1982 : : elog(ERROR, "unexpected EOF on self-pipe");
1983 : : #else
1984 [ # # ]: 0 : elog(ERROR, "unexpected EOF on signalfd");
1985 : : #endif
1986 : : }
374 heikki.linnakangas@i 1987 [ + - ]:CBC 981880 : else if (rc < sizeof(buf))
1988 : : {
1989 : : /* we successfully drained the pipe; no need to read() again */
1990 : 981880 : break;
1991 : : }
1992 : : /* else buffer wasn't big enough, so read again */
1993 : : }
1994 : 981880 : }
1995 : :
1996 : : #endif
1997 : :
1998 : : static void
1999 : 1 : ResOwnerReleaseWaitEventSet(Datum res)
2000 : : {
2001 : 1 : WaitEventSet *set = (WaitEventSet *) DatumGetPointer(res);
2002 : :
2003 [ - + ]: 1 : Assert(set->owner != NULL);
2004 : 1 : set->owner = NULL;
2005 : 1 : FreeWaitEventSet(set);
2006 : 1 : }
2007 : :
2008 : : #ifndef WIN32
2009 : : /*
2010 : : * Wake up my process if it's currently sleeping in WaitEventSetWaitBlock()
2011 : : *
2012 : : * NB: be sure to save and restore errno around it. (That's standard practice
2013 : : * in most signal handlers, of course, but we used to omit it in handlers that
2014 : : * only set a flag.) XXX
2015 : : *
2016 : : * NB: this function is called from critical sections and signal handlers so
2017 : : * throwing an error is not a good idea.
2018 : : *
2019 : : * On Windows, Latch uses SetEvent directly and this is not used.
2020 : : */
2021 : : void
2022 : 40912 : WakeupMyProc(void)
2023 : : {
2024 : : #if defined(WAIT_USE_SELF_PIPE)
2025 : : if (waiting)
2026 : : sendSelfPipeByte();
2027 : : #else
2028 [ + - ]: 40912 : if (waiting)
2029 : 40912 : kill(MyProcPid, SIGURG);
2030 : : #endif
2031 : 40912 : }
2032 : :
2033 : : /* Similar to WakeupMyProc, but wake up another process */
2034 : : void
2035 : 1035718 : WakeupOtherProc(int pid)
2036 : : {
2037 : 1035718 : kill(pid, SIGURG);
2038 : 1035718 : }
2039 : : #endif
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