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Commit 59f71a0

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anarazelanarazel
committed
Add a default local latch for use in signal handlers.
To do so, move InitializeLatchSupport() into the new common process initialization functions, and add a new global variable MyLatch. MyLatch is usable as soon InitPostmasterChild() has been called (i.e. very early during startup). Initially it points to a process local latch that exists in all processes. InitProcess/InitAuxiliaryProcess then replaces that local latch with PGPROC->procLatch. During shutdown the reverse happens. This is primarily advantageous for two reasons: For one it simplifies dealing with the shared process latch, especially in signal handlers, because instead of having to check for MyProc, MyLatch can be used unconditionally. For another, a later patch that makes FEs/BE communication use latches, now can rely on the existence of a latch, even before having gone through InitProcess. Discussion: 20140927191243.GD5423@alap3.anarazel.de
1 parent 85a2a89 commit 59f71a0

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23 files changed

+136
-134
lines changed

23 files changed

+136
-134
lines changed

‎src/backend/postmaster/autovacuum.c

Lines changed: 5 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -589,11 +589,11 @@ AutoVacLauncherMain(int argc, char *argv[])
589589
* Wait until naptime expires or we get some type of signal (all the
590590
* signal handlers will wake us by calling SetLatch).
591591
*/
592-
rc = WaitLatch(&MyProc->procLatch,
592+
rc = WaitLatch(MyLatch,
593593
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
594594
(nap.tv_sec * 1000L) + (nap.tv_usec / 1000L));
595595

596-
ResetLatch(&MyProc->procLatch);
596+
ResetLatch(MyLatch);
597597

598598
DisableCatchupInterrupt();
599599

@@ -1341,8 +1341,7 @@ avl_sighup_handler(SIGNAL_ARGS)
13411341
int save_errno = errno;
13421342

13431343
got_SIGHUP = true;
1344-
if (MyProc)
1345-
SetLatch(&MyProc->procLatch);
1344+
SetLatch(MyLatch);
13461345

13471346
errno = save_errno;
13481347
}
@@ -1354,8 +1353,7 @@ avl_sigusr2_handler(SIGNAL_ARGS)
13541353
int save_errno = errno;
13551354

13561355
got_SIGUSR2 = true;
1357-
if (MyProc)
1358-
SetLatch(&MyProc->procLatch);
1356+
SetLatch(MyLatch);
13591357

13601358
errno = save_errno;
13611359
}
@@ -1367,8 +1365,7 @@ avl_sigterm_handler(SIGNAL_ARGS)
13671365
int save_errno = errno;
13681366

13691367
got_SIGTERM = true;
1370-
if (MyProc)
1371-
SetLatch(&MyProc->procLatch);
1368+
SetLatch(MyLatch);
13721369

13731370
errno = save_errno;
13741371
}

‎src/backend/postmaster/bgworker.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -942,7 +942,7 @@ WaitForBackgroundWorkerStartup(BackgroundWorkerHandle *handle, pid_t *pidp)
942942
if (status != BGWH_NOT_YET_STARTED)
943943
break;
944944

945-
rc = WaitLatch(&MyProc->procLatch,
945+
rc = WaitLatch(MyLatch,
946946
WL_LATCH_SET | WL_POSTMASTER_DEATH, 0);
947947

948948
if (rc & WL_POSTMASTER_DEATH)
@@ -951,7 +951,7 @@ WaitForBackgroundWorkerStartup(BackgroundWorkerHandle *handle, pid_t *pidp)
951951
break;
952952
}
953953

954-
ResetLatch(&MyProc->procLatch);
954+
ResetLatch(MyLatch);
955955
}
956956
}
957957
PG_CATCH();

‎src/backend/postmaster/bgwriter.c

Lines changed: 5 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -248,7 +248,7 @@ BackgroundWriterMain(void)
248248
int rc;
249249

250250
/* Clear any already-pending wakeups */
251-
ResetLatch(&MyProc->procLatch);
251+
ResetLatch(MyLatch);
252252

253253
if (got_SIGHUP)
254254
{
@@ -336,7 +336,7 @@ BackgroundWriterMain(void)
336336
* down with latch events that are likely to happen frequently during
337337
* normal operation.
338338
*/
339-
rc = WaitLatch(&MyProc->procLatch,
339+
rc = WaitLatch(MyLatch,
340340
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
341341
BgWriterDelay /* ms */ );
342342

@@ -363,7 +363,7 @@ BackgroundWriterMain(void)
363363
/* Ask for notification at next buffer allocation */
364364
StrategyNotifyBgWriter(MyProc->pgprocno);
365365
/* Sleep ... */
366-
rc = WaitLatch(&MyProc->procLatch,
366+
rc = WaitLatch(MyLatch,
367367
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
368368
BgWriterDelay * HIBERNATE_FACTOR);
369369
/* Reset the notification request in case we timed out */
@@ -426,8 +426,7 @@ BgSigHupHandler(SIGNAL_ARGS)
426426
int save_errno = errno;
427427

428428
got_SIGHUP = true;
429-
if (MyProc)
430-
SetLatch(&MyProc->procLatch);
429+
SetLatch(MyLatch);
431430

432431
errno = save_errno;
433432
}
@@ -439,8 +438,7 @@ ReqShutdownHandler(SIGNAL_ARGS)
439438
int save_errno = errno;
440439

441440
shutdown_requested = true;
442-
if (MyProc)
443-
SetLatch(&MyProc->procLatch);
441+
SetLatch(MyLatch);
444442

445443
errno = save_errno;
446444
}

‎src/backend/postmaster/checkpointer.c

Lines changed: 5 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -360,7 +360,7 @@ CheckpointerMain(void)
360360
int rc;
361361

362362
/* Clear any already-pending wakeups */
363-
ResetLatch(&MyProc->procLatch);
363+
ResetLatch(MyLatch);
364364

365365
/*
366366
* Process any requests or signals received recently.
@@ -559,7 +559,7 @@ CheckpointerMain(void)
559559
cur_timeout = Min(cur_timeout, XLogArchiveTimeout - elapsed_secs);
560560
}
561561

562-
rc = WaitLatch(&MyProc->procLatch,
562+
rc = WaitLatch(MyLatch,
563563
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
564564
cur_timeout * 1000L /* convert to ms */ );
565565

@@ -832,8 +832,7 @@ ChkptSigHupHandler(SIGNAL_ARGS)
832832
int save_errno = errno;
833833

834834
got_SIGHUP = true;
835-
if (MyProc)
836-
SetLatch(&MyProc->procLatch);
835+
SetLatch(MyLatch);
837836

838837
errno = save_errno;
839838
}
@@ -845,8 +844,7 @@ ReqCheckpointHandler(SIGNAL_ARGS)
845844
int save_errno = errno;
846845

847846
checkpoint_requested = true;
848-
if (MyProc)
849-
SetLatch(&MyProc->procLatch);
847+
SetLatch(MyLatch);
850848

851849
errno = save_errno;
852850
}
@@ -869,8 +867,7 @@ ReqShutdownHandler(SIGNAL_ARGS)
869867
int save_errno = errno;
870868

871869
shutdown_requested = true;
872-
if (MyProc)
873-
SetLatch(&MyProc->procLatch);
870+
SetLatch(MyLatch);
874871

875872
errno = save_errno;
876873
}

‎src/backend/postmaster/pgarch.c

Lines changed: 6 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -78,11 +78,6 @@ static volatile sig_atomic_t got_SIGTERM = false;
7878
static volatile sig_atomic_t wakened = false;
7979
static volatile sig_atomic_t ready_to_stop = false;
8080

81-
/*
82-
* Latch used by signal handlers to wake up the sleep in the main loop.
83-
*/
84-
static Latch mainloop_latch;
85-
8681
/* ----------
8782
* Local function forward declarations
8883
* ----------
@@ -220,10 +215,6 @@ pgarch_forkexec(void)
220215
NON_EXEC_STATIC void
221216
PgArchiverMain(int argc, char *argv[])
222217
{
223-
InitializeLatchSupport(); /* needed for latch waits */
224-
225-
InitLatch(&mainloop_latch); /* initialize latch used in main loop */
226-
227218
/*
228219
* Ignore all signals usually bound to some action in the postmaster,
229220
* except for SIGHUP, SIGTERM, SIGUSR1, SIGUSR2, and SIGQUIT.
@@ -269,7 +260,7 @@ ArchSigHupHandler(SIGNAL_ARGS)
269260

270261
/* set flag to re-read config file at next convenient time */
271262
got_SIGHUP = true;
272-
SetLatch(&mainloop_latch);
263+
SetLatch(MyLatch);
273264

274265
errno = save_errno;
275266
}
@@ -287,7 +278,7 @@ ArchSigTermHandler(SIGNAL_ARGS)
287278
* archive commands.
288279
*/
289280
got_SIGTERM = true;
290-
SetLatch(&mainloop_latch);
281+
SetLatch(MyLatch);
291282

292283
errno = save_errno;
293284
}
@@ -300,7 +291,7 @@ pgarch_waken(SIGNAL_ARGS)
300291

301292
/* set flag that there is work to be done */
302293
wakened = true;
303-
SetLatch(&mainloop_latch);
294+
SetLatch(MyLatch);
304295

305296
errno = save_errno;
306297
}
@@ -313,7 +304,7 @@ pgarch_waken_stop(SIGNAL_ARGS)
313304

314305
/* set flag to do a final cycle and shut down afterwards */
315306
ready_to_stop = true;
316-
SetLatch(&mainloop_latch);
307+
SetLatch(MyLatch);
317308

318309
errno = save_errno;
319310
}
@@ -344,7 +335,7 @@ pgarch_MainLoop(void)
344335
*/
345336
do
346337
{
347-
ResetLatch(&mainloop_latch);
338+
ResetLatch(MyLatch);
348339

349340
/* When we get SIGUSR2, we do one more archive cycle, then exit */
350341
time_to_stop = ready_to_stop;
@@ -397,7 +388,7 @@ pgarch_MainLoop(void)
397388
{
398389
int rc;
399390

400-
rc = WaitLatch(&mainloop_latch,
391+
rc = WaitLatch(MyLatch,
401392
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
402393
timeout * 1000L);
403394
if (rc & WL_TIMEOUT)

‎src/backend/postmaster/pgstat.c

Lines changed: 6 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -130,8 +130,6 @@ PgStat_MsgBgWriter BgWriterStats;
130130
*/
131131
NON_EXEC_STATIC pgsocket pgStatSock = PGINVALID_SOCKET;
132132

133-
static Latch pgStatLatch;
134-
135133
static struct sockaddr_storage pgStatAddr;
136134

137135
static time_t last_pgstat_start_time;
@@ -3151,15 +3149,10 @@ PgstatCollectorMain(int argc, char *argv[])
31513149
PgStat_Msg msg;
31523150
int wr;
31533151

3154-
InitializeLatchSupport(); /* needed for latch waits */
3155-
3156-
/* Initialize private latch for use by signal handlers */
3157-
InitLatch(&pgStatLatch);
3158-
31593152
/*
31603153
* Ignore all signals usually bound to some action in the postmaster,
31613154
* except SIGHUP and SIGQUIT. Note we don't need a SIGUSR1 handler to
3162-
* support latch operations, because pgStatLatch is local not shared.
3155+
* support latch operations, because we only use a local latch.
31633156
*/
31643157
pqsignal(SIGHUP, pgstat_sighup_handler);
31653158
pqsignal(SIGINT, SIG_IGN);
@@ -3205,7 +3198,7 @@ PgstatCollectorMain(int argc, char *argv[])
32053198
for (;;)
32063199
{
32073200
/* Clear any already-pending wakeups */
3208-
ResetLatch(&pgStatLatch);
3201+
ResetLatch(MyLatch);
32093202

32103203
/*
32113204
* Quit if we get SIGQUIT from the postmaster.
@@ -3363,7 +3356,7 @@ PgstatCollectorMain(int argc, char *argv[])
33633356

33643357
/* Sleep until there's something to do */
33653358
#ifndef WIN32
3366-
wr = WaitLatchOrSocket(&pgStatLatch,
3359+
wr = WaitLatchOrSocket(MyLatch,
33673360
WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE,
33683361
pgStatSock,
33693362
-1L);
@@ -3379,7 +3372,7 @@ PgstatCollectorMain(int argc, char *argv[])
33793372
* to not provoke "pgstat wait timeout" complaints from
33803373
* backend_read_statsfile.
33813374
*/
3382-
wr = WaitLatchOrSocket(&pgStatLatch,
3375+
wr = WaitLatchOrSocket(MyLatch,
33833376
WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE | WL_TIMEOUT,
33843377
pgStatSock,
33853378
2 * 1000L /* msec */ );
@@ -3409,7 +3402,7 @@ pgstat_exit(SIGNAL_ARGS)
34093402
int save_errno = errno;
34103403

34113404
need_exit = true;
3412-
SetLatch(&pgStatLatch);
3405+
SetLatch(MyLatch);
34133406

34143407
errno = save_errno;
34153408
}
@@ -3421,7 +3414,7 @@ pgstat_sighup_handler(SIGNAL_ARGS)
34213414
int save_errno = errno;
34223415

34233416
got_SIGHUP = true;
3424-
SetLatch(&pgStatLatch);
3417+
SetLatch(MyLatch);
34253418

34263419
errno = save_errno;
34273420
}

‎src/backend/postmaster/syslogger.c

Lines changed: 7 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -85,7 +85,6 @@ static FILE *csvlogFile = NULL;
8585
NON_EXEC_STATIC pg_time_t first_syslogger_file_time = 0;
8686
static char *last_file_name = NULL;
8787
static char *last_csv_file_name = NULL;
88-
static Latch sysLoggerLatch;
8988

9089
/*
9190
* Buffers for saving partial messages from different backends.
@@ -231,12 +230,6 @@ SysLoggerMain(int argc, char *argv[])
231230
syslogPipe[1] = 0;
232231
#endif
233232

234-
InitializeLatchSupport(); /* needed for latch waits */
235-
236-
237-
/* Initialize private latch for use by signal handlers */
238-
InitLatch(&sysLoggerLatch);
239-
240233
/*
241234
* Properly accept or ignore signals the postmaster might send us
242235
*
@@ -302,7 +295,7 @@ SysLoggerMain(int argc, char *argv[])
302295
#endif
303296

304297
/* Clear any already-pending wakeups */
305-
ResetLatch(&sysLoggerLatch);
298+
ResetLatch(MyLatch);
306299

307300
/*
308301
* Process any requests or signals received recently.
@@ -428,7 +421,7 @@ SysLoggerMain(int argc, char *argv[])
428421
* Sleep until there's something to do
429422
*/
430423
#ifndef WIN32
431-
rc = WaitLatchOrSocket(&sysLoggerLatch,
424+
rc = WaitLatchOrSocket(MyLatch,
432425
WL_LATCH_SET | WL_SOCKET_READABLE | cur_flags,
433426
syslogPipe[0],
434427
cur_timeout);
@@ -480,7 +473,7 @@ SysLoggerMain(int argc, char *argv[])
480473
*/
481474
LeaveCriticalSection(&sysloggerSection);
482475

483-
(void) WaitLatch(&sysLoggerLatch,
476+
(void) WaitLatch(MyLatch,
484477
WL_LATCH_SET | cur_flags,
485478
cur_timeout);
486479

@@ -1061,7 +1054,7 @@ pipeThread(void *arg)
10611054
{
10621055
if (ftell(syslogFile) >= Log_RotationSize * 1024L ||
10631056
(csvlogFile != NULL && ftell(csvlogFile) >= Log_RotationSize * 1024L))
1064-
SetLatch(&sysLoggerLatch);
1057+
SetLatch(MyLatch);
10651058
}
10661059
LeaveCriticalSection(&sysloggerSection);
10671060
}
@@ -1073,7 +1066,7 @@ pipeThread(void *arg)
10731066
flush_pipe_input(logbuffer, &bytes_in_logbuffer);
10741067

10751068
/* set the latch to waken the main thread, which will quit */
1076-
SetLatch(&sysLoggerLatch);
1069+
SetLatch(MyLatch);
10771070

10781071
LeaveCriticalSection(&sysloggerSection);
10791072
_endthread();
@@ -1353,7 +1346,7 @@ sigHupHandler(SIGNAL_ARGS)
13531346
int save_errno = errno;
13541347

13551348
got_SIGHUP = true;
1356-
SetLatch(&sysLoggerLatch);
1349+
SetLatch(MyLatch);
13571350

13581351
errno = save_errno;
13591352
}
@@ -1365,7 +1358,7 @@ sigUsr1Handler(SIGNAL_ARGS)
13651358
int save_errno = errno;
13661359

13671360
rotation_requested = true;
1368-
SetLatch(&sysLoggerLatch);
1361+
SetLatch(MyLatch);
13691362

13701363
errno = save_errno;
13711364
}

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