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Add a default local latch for use in signal handlers.

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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
pull/14/head
Andres Freund 11 years ago
parent 85a2a8903f
commit 59f71a0d0b
23 changed files with 136 additions and 134 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 13
      src/backend/postmaster/autovacuum.c
  2. 4
      src/backend/postmaster/bgworker.c
  3. 12
      src/backend/postmaster/bgwriter.c
  4. 13
      src/backend/postmaster/checkpointer.c
  5. 21
      src/backend/postmaster/pgarch.c
  6. 19
      src/backend/postmaster/pgstat.c
  7. 21
      src/backend/postmaster/syslogger.c
  8. 10
      src/backend/postmaster/walwriter.c
  9. 4
      src/backend/replication/syncrep.c
  10. 4
      src/backend/storage/ipc/procsignal.c
  11. 12
      src/backend/storage/ipc/shm_mq.c
  12. 42
      src/backend/storage/lmgr/proc.c
  13. 12
      src/backend/tcop/postgres.c
  14. 4
      src/backend/utils/adt/misc.c
  15. 9
      src/backend/utils/init/globals.c
  16. 37
      src/backend/utils/init/miscinit.c
  17. 6
      src/backend/utils/misc/timeout.c
  18. 4
      src/include/miscadmin.h
  19. 2
      src/include/storage/latch.h
  20. 4
      src/test/modules/test_shm_mq/setup.c
  21. 4
      src/test/modules/test_shm_mq/test.c
  22. 3
      src/test/modules/test_shm_mq/worker.c
  23. 10
      src/test/modules/worker_spi/worker_spi.c

13
src/backend/postmaster/autovacuum.c
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@ -589,11 +589,11 @@ AutoVacLauncherMain(int argc, char *argv[])
* Wait until naptime expires or we get some type of signal (all the * Wait until naptime expires or we get some type of signal (all the
* signal handlers will wake us by calling SetLatch). * signal handlers will wake us by calling SetLatch).
*/ */
rc = WaitLatch(&MyProc->procLatch, rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
(nap.tv_sec * 1000L) + (nap.tv_usec / 1000L)); (nap.tv_sec * 1000L) + (nap.tv_usec / 1000L));
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
DisableCatchupInterrupt(); DisableCatchupInterrupt();
@ -1341,8 +1341,7 @@ avl_sighup_handler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_SIGHUP = true; got_SIGHUP = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -1354,8 +1353,7 @@ avl_sigusr2_handler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_SIGUSR2 = true; got_SIGUSR2 = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -1367,8 +1365,7 @@ avl_sigterm_handler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_SIGTERM = true; got_SIGTERM = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }

4
src/backend/postmaster/bgworker.c
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@ -942,7 +942,7 @@ WaitForBackgroundWorkerStartup(BackgroundWorkerHandle *handle, pid_t *pidp)
if (status != BGWH_NOT_YET_STARTED) if (status != BGWH_NOT_YET_STARTED)
break; break;
rc = WaitLatch(&MyProc->procLatch, rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_POSTMASTER_DEATH, 0); WL_LATCH_SET | WL_POSTMASTER_DEATH, 0);
if (rc & WL_POSTMASTER_DEATH) if (rc & WL_POSTMASTER_DEATH)
@ -951,7 +951,7 @@ WaitForBackgroundWorkerStartup(BackgroundWorkerHandle *handle, pid_t *pidp)
break; break;
} }
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
} }
} }
PG_CATCH(); PG_CATCH();

12
src/backend/postmaster/bgwriter.c
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@ -248,7 +248,7 @@ BackgroundWriterMain(void)
int rc; int rc;
/* Clear any already-pending wakeups */ /* Clear any already-pending wakeups */
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
if (got_SIGHUP) if (got_SIGHUP)
{ {
@ -336,7 +336,7 @@ BackgroundWriterMain(void)
* down with latch events that are likely to happen frequently during * down with latch events that are likely to happen frequently during
* normal operation. * normal operation.
*/ */
rc = WaitLatch(&MyProc->procLatch, rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
BgWriterDelay /* ms */ ); BgWriterDelay /* ms */ );
@ -363,7 +363,7 @@ BackgroundWriterMain(void)
/* Ask for notification at next buffer allocation */ /* Ask for notification at next buffer allocation */
StrategyNotifyBgWriter(MyProc->pgprocno); StrategyNotifyBgWriter(MyProc->pgprocno);
/* Sleep ... */ /* Sleep ... */
rc = WaitLatch(&MyProc->procLatch, rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
BgWriterDelay * HIBERNATE_FACTOR); BgWriterDelay * HIBERNATE_FACTOR);
/* Reset the notification request in case we timed out */ /* Reset the notification request in case we timed out */
@ -426,8 +426,7 @@ BgSigHupHandler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_SIGHUP = true; got_SIGHUP = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -439,8 +438,7 @@ ReqShutdownHandler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
shutdown_requested = true; shutdown_requested = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }

13
src/backend/postmaster/checkpointer.c
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@ -360,7 +360,7 @@ CheckpointerMain(void)
int rc; int rc;
/* Clear any already-pending wakeups */ /* Clear any already-pending wakeups */
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
/* /*
* Process any requests or signals received recently. * Process any requests or signals received recently.
@ -559,7 +559,7 @@ CheckpointerMain(void)
cur_timeout = Min(cur_timeout, XLogArchiveTimeout - elapsed_secs); cur_timeout = Min(cur_timeout, XLogArchiveTimeout - elapsed_secs);
} }
rc = WaitLatch(&MyProc->procLatch, rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
cur_timeout * 1000L /* convert to ms */ ); cur_timeout * 1000L /* convert to ms */ );
@ -832,8 +832,7 @@ ChkptSigHupHandler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_SIGHUP = true; got_SIGHUP = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -845,8 +844,7 @@ ReqCheckpointHandler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
checkpoint_requested = true; checkpoint_requested = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -869,8 +867,7 @@ ReqShutdownHandler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
shutdown_requested = true; shutdown_requested = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }

21
src/backend/postmaster/pgarch.c
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@ -78,11 +78,6 @@ static volatile sig_atomic_t got_SIGTERM = false;
static volatile sig_atomic_t wakened = false; static volatile sig_atomic_t wakened = false;
static volatile sig_atomic_t ready_to_stop = false; static volatile sig_atomic_t ready_to_stop = false;
/*
* Latch used by signal handlers to wake up the sleep in the main loop.
*/
static Latch mainloop_latch;
/* ---------- /* ----------
* Local function forward declarations * Local function forward declarations
* ---------- * ----------
@ -220,10 +215,6 @@ pgarch_forkexec(void)
NON_EXEC_STATIC void NON_EXEC_STATIC void
PgArchiverMain(int argc, char *argv[]) PgArchiverMain(int argc, char *argv[])
{ {
InitializeLatchSupport(); /* needed for latch waits */
InitLatch(&mainloop_latch); /* initialize latch used in main loop */
/* /*
* Ignore all signals usually bound to some action in the postmaster, * Ignore all signals usually bound to some action in the postmaster,
* except for SIGHUP, SIGTERM, SIGUSR1, SIGUSR2, and SIGQUIT. * except for SIGHUP, SIGTERM, SIGUSR1, SIGUSR2, and SIGQUIT.
@ -269,7 +260,7 @@ ArchSigHupHandler(SIGNAL_ARGS)
/* set flag to re-read config file at next convenient time */ /* set flag to re-read config file at next convenient time */
got_SIGHUP = true; got_SIGHUP = true;
SetLatch(&mainloop_latch); SetLatch(MyLatch);
errno = save_errno; errno = save_errno;
} }
@ -287,7 +278,7 @@ ArchSigTermHandler(SIGNAL_ARGS)
* archive commands. * archive commands.
*/ */
got_SIGTERM = true; got_SIGTERM = true;
SetLatch(&mainloop_latch); SetLatch(MyLatch);
errno = save_errno; errno = save_errno;
} }
@ -300,7 +291,7 @@ pgarch_waken(SIGNAL_ARGS)
/* set flag that there is work to be done */ /* set flag that there is work to be done */
wakened = true; wakened = true;
SetLatch(&mainloop_latch); SetLatch(MyLatch);
errno = save_errno; errno = save_errno;
} }
@ -313,7 +304,7 @@ pgarch_waken_stop(SIGNAL_ARGS)
/* set flag to do a final cycle and shut down afterwards */ /* set flag to do a final cycle and shut down afterwards */
ready_to_stop = true; ready_to_stop = true;
SetLatch(&mainloop_latch); SetLatch(MyLatch);
errno = save_errno; errno = save_errno;
} }
@ -344,7 +335,7 @@ pgarch_MainLoop(void)
*/ */
do do
{ {
ResetLatch(&mainloop_latch); ResetLatch(MyLatch);
/* When we get SIGUSR2, we do one more archive cycle, then exit */ /* When we get SIGUSR2, we do one more archive cycle, then exit */
time_to_stop = ready_to_stop; time_to_stop = ready_to_stop;
@ -397,7 +388,7 @@ pgarch_MainLoop(void)
{ {
int rc; int rc;
rc = WaitLatch(&mainloop_latch, rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
timeout * 1000L); timeout * 1000L);
if (rc & WL_TIMEOUT) if (rc & WL_TIMEOUT)

19
src/backend/postmaster/pgstat.c
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@ -130,8 +130,6 @@ PgStat_MsgBgWriter BgWriterStats;
*/ */
NON_EXEC_STATIC pgsocket pgStatSock = PGINVALID_SOCKET; NON_EXEC_STATIC pgsocket pgStatSock = PGINVALID_SOCKET;
static Latch pgStatLatch;
static struct sockaddr_storage pgStatAddr; static struct sockaddr_storage pgStatAddr;
static time_t last_pgstat_start_time; static time_t last_pgstat_start_time;
@ -3151,15 +3149,10 @@ PgstatCollectorMain(int argc, char *argv[])
PgStat_Msg msg; PgStat_Msg msg;
int wr; int wr;
InitializeLatchSupport(); /* needed for latch waits */
/* Initialize private latch for use by signal handlers */
InitLatch(&pgStatLatch);
/* /*
* Ignore all signals usually bound to some action in the postmaster, * Ignore all signals usually bound to some action in the postmaster,
* except SIGHUP and SIGQUIT. Note we don't need a SIGUSR1 handler to * except SIGHUP and SIGQUIT. Note we don't need a SIGUSR1 handler to
* support latch operations, because pgStatLatch is local not shared. * support latch operations, because we only use a local latch.
*/ */
pqsignal(SIGHUP, pgstat_sighup_handler); pqsignal(SIGHUP, pgstat_sighup_handler);
pqsignal(SIGINT, SIG_IGN); pqsignal(SIGINT, SIG_IGN);
@ -3205,7 +3198,7 @@ PgstatCollectorMain(int argc, char *argv[])
for (;;) for (;;)
{ {
/* Clear any already-pending wakeups */ /* Clear any already-pending wakeups */
ResetLatch(&pgStatLatch); ResetLatch(MyLatch);
/* /*
* Quit if we get SIGQUIT from the postmaster. * Quit if we get SIGQUIT from the postmaster.
@ -3363,7 +3356,7 @@ PgstatCollectorMain(int argc, char *argv[])
/* Sleep until there's something to do */ /* Sleep until there's something to do */
#ifndef WIN32 #ifndef WIN32
wr = WaitLatchOrSocket(&pgStatLatch, wr = WaitLatchOrSocket(MyLatch,
WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE, WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE,
pgStatSock, pgStatSock,
-1L); -1L);
@ -3379,7 +3372,7 @@ PgstatCollectorMain(int argc, char *argv[])
* to not provoke "pgstat wait timeout" complaints from * to not provoke "pgstat wait timeout" complaints from
* backend_read_statsfile. * backend_read_statsfile.
*/ */
wr = WaitLatchOrSocket(&pgStatLatch, wr = WaitLatchOrSocket(MyLatch,
WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE | WL_TIMEOUT, WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE | WL_TIMEOUT,
pgStatSock, pgStatSock,
2 * 1000L /* msec */ ); 2 * 1000L /* msec */ );
@ -3409,7 +3402,7 @@ pgstat_exit(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
need_exit = true; need_exit = true;
SetLatch(&pgStatLatch); SetLatch(MyLatch);
errno = save_errno; errno = save_errno;
} }
@ -3421,7 +3414,7 @@ pgstat_sighup_handler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_SIGHUP = true; got_SIGHUP = true;
SetLatch(&pgStatLatch); SetLatch(MyLatch);
errno = save_errno; errno = save_errno;
} }

21
src/backend/postmaster/syslogger.c
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@ -85,7 +85,6 @@ static FILE *csvlogFile = NULL;
NON_EXEC_STATIC pg_time_t first_syslogger_file_time = 0; NON_EXEC_STATIC pg_time_t first_syslogger_file_time = 0;
static char *last_file_name = NULL; static char *last_file_name = NULL;
static char *last_csv_file_name = NULL; static char *last_csv_file_name = NULL;
static Latch sysLoggerLatch;
/* /*
* Buffers for saving partial messages from different backends. * Buffers for saving partial messages from different backends.
@ -231,12 +230,6 @@ SysLoggerMain(int argc, char *argv[])
syslogPipe[1] = 0; syslogPipe[1] = 0;
#endif #endif
InitializeLatchSupport(); /* needed for latch waits */
/* Initialize private latch for use by signal handlers */
InitLatch(&sysLoggerLatch);
/* /*
* Properly accept or ignore signals the postmaster might send us * Properly accept or ignore signals the postmaster might send us
* *
@ -302,7 +295,7 @@ SysLoggerMain(int argc, char *argv[])
#endif #endif
/* Clear any already-pending wakeups */ /* Clear any already-pending wakeups */
ResetLatch(&sysLoggerLatch); ResetLatch(MyLatch);
/* /*
* Process any requests or signals received recently. * Process any requests or signals received recently.
@ -428,7 +421,7 @@ SysLoggerMain(int argc, char *argv[])
* Sleep until there's something to do * Sleep until there's something to do
*/ */
#ifndef WIN32 #ifndef WIN32
rc = WaitLatchOrSocket(&sysLoggerLatch, rc = WaitLatchOrSocket(MyLatch,
WL_LATCH_SET | WL_SOCKET_READABLE | cur_flags, WL_LATCH_SET | WL_SOCKET_READABLE | cur_flags,
syslogPipe[0], syslogPipe[0],
cur_timeout); cur_timeout);
@ -480,7 +473,7 @@ SysLoggerMain(int argc, char *argv[])
*/ */
LeaveCriticalSection(&sysloggerSection); LeaveCriticalSection(&sysloggerSection);
(void) WaitLatch(&sysLoggerLatch, (void) WaitLatch(MyLatch,
WL_LATCH_SET | cur_flags, WL_LATCH_SET | cur_flags,
cur_timeout); cur_timeout);
@ -1061,7 +1054,7 @@ pipeThread(void *arg)
{ {
if (ftell(syslogFile) >= Log_RotationSize * 1024L || if (ftell(syslogFile) >= Log_RotationSize * 1024L ||
(csvlogFile != NULL && ftell(csvlogFile) >= Log_RotationSize * 1024L)) (csvlogFile != NULL && ftell(csvlogFile) >= Log_RotationSize * 1024L))
SetLatch(&sysLoggerLatch); SetLatch(MyLatch);
} }
LeaveCriticalSection(&sysloggerSection); LeaveCriticalSection(&sysloggerSection);
} }
@ -1073,7 +1066,7 @@ pipeThread(void *arg)
flush_pipe_input(logbuffer, &bytes_in_logbuffer); flush_pipe_input(logbuffer, &bytes_in_logbuffer);
/* set the latch to waken the main thread, which will quit */ /* set the latch to waken the main thread, which will quit */
SetLatch(&sysLoggerLatch); SetLatch(MyLatch);
LeaveCriticalSection(&sysloggerSection); LeaveCriticalSection(&sysloggerSection);
_endthread(); _endthread();
@ -1353,7 +1346,7 @@ sigHupHandler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_SIGHUP = true; got_SIGHUP = true;
SetLatch(&sysLoggerLatch); SetLatch(MyLatch);
errno = save_errno; errno = save_errno;
} }
@ -1365,7 +1358,7 @@ sigUsr1Handler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
rotation_requested = true; rotation_requested = true;
SetLatch(&sysLoggerLatch); SetLatch(MyLatch);
errno = save_errno; errno = save_errno;
} }

10
src/backend/postmaster/walwriter.c
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@ -252,7 +252,7 @@ WalWriterMain(void)
} }
/* Clear any already-pending wakeups */ /* Clear any already-pending wakeups */
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
/* /*
* Process any requests or signals received recently. * Process any requests or signals received recently.
@ -287,7 +287,7 @@ WalWriterMain(void)
else else
cur_timeout = WalWriterDelay * HIBERNATE_FACTOR; cur_timeout = WalWriterDelay * HIBERNATE_FACTOR;
rc = WaitLatch(&MyProc->procLatch, rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
cur_timeout); cur_timeout);
@ -345,8 +345,7 @@ WalSigHupHandler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_SIGHUP = true; got_SIGHUP = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -358,8 +357,7 @@ WalShutdownHandler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
shutdown_requested = true; shutdown_requested = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }

4
src/backend/replication/syncrep.c
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@ -162,7 +162,7 @@ SyncRepWaitForLSN(XLogRecPtr XactCommitLSN)
int syncRepState; int syncRepState;
/* Must reset the latch before testing state. */ /* Must reset the latch before testing state. */
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
/* /*
* Try checking the state without the lock first. There's no * Try checking the state without the lock first. There's no
@ -235,7 +235,7 @@ SyncRepWaitForLSN(XLogRecPtr XactCommitLSN)
* Wait on latch. Any condition that should wake us up will set the * Wait on latch. Any condition that should wake us up will set the
* latch, so no need for timeout. * latch, so no need for timeout.
*/ */
WaitLatch(&MyProc->procLatch, WL_LATCH_SET | WL_POSTMASTER_DEATH, -1); WaitLatch(MyLatch, WL_LATCH_SET | WL_POSTMASTER_DEATH, -1);
} }
/* /*

4
src/backend/storage/ipc/procsignal.c
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@ -292,8 +292,8 @@ procsignal_sigusr1_handler(SIGNAL_ARGS)
if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN)) if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))
RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN); RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
if (set_latch_on_sigusr1 && MyProc != NULL) if (set_latch_on_sigusr1)
SetLatch(&MyProc->procLatch); SetLatch(MyLatch);
latch_sigusr1_handler(); latch_sigusr1_handler();

12
src/backend/storage/ipc/shm_mq.c
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@ -827,13 +827,13 @@ shm_mq_send_bytes(shm_mq_handle *mqh, Size nbytes, const void *data,
* at top of loop, because setting an already-set latch is much * at top of loop, because setting an already-set latch is much
* cheaper than setting one that has been reset. * cheaper than setting one that has been reset.
*/ */
WaitLatch(&MyProc->procLatch, WL_LATCH_SET, 0); WaitLatch(MyLatch, WL_LATCH_SET, 0);
/* An interrupt may have occurred while we were waiting. */ /* An interrupt may have occurred while we were waiting. */
CHECK_FOR_INTERRUPTS(); CHECK_FOR_INTERRUPTS();
/* Reset the latch so we don't spin. */ /* Reset the latch so we don't spin. */
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
} }
else else
{ {
@ -924,13 +924,13 @@ shm_mq_receive_bytes(shm_mq *mq, Size bytes_needed, bool nowait,
* loop, because setting an already-set latch is much cheaper than * loop, because setting an already-set latch is much cheaper than
* setting one that has been reset. * setting one that has been reset.
*/ */
WaitLatch(&MyProc->procLatch, WL_LATCH_SET, 0); WaitLatch(MyLatch, WL_LATCH_SET, 0);
/* An interrupt may have occurred while we were waiting. */ /* An interrupt may have occurred while we were waiting. */
CHECK_FOR_INTERRUPTS(); CHECK_FOR_INTERRUPTS();
/* Reset the latch so we don't spin. */ /* Reset the latch so we don't spin. */
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
} }
} }
@ -991,13 +991,13 @@ shm_mq_wait_internal(volatile shm_mq *mq, PGPROC *volatile * ptr,
} }
/* Wait to be signalled. */ /* Wait to be signalled. */
WaitLatch(&MyProc->procLatch, WL_LATCH_SET, 0); WaitLatch(MyLatch, WL_LATCH_SET, 0);
/* An interrupt may have occurred while we were waiting. */ /* An interrupt may have occurred while we were waiting. */
CHECK_FOR_INTERRUPTS(); CHECK_FOR_INTERRUPTS();
/* Reset the latch so we don't spin. */ /* Reset the latch so we don't spin. */
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
} }
} }
PG_CATCH(); PG_CATCH();

42
src/backend/storage/lmgr/proc.c
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@ -290,13 +290,6 @@ InitProcess(void)
if (MyProc != NULL) if (MyProc != NULL)
elog(ERROR, "you already exist"); elog(ERROR, "you already exist");
/*
* Initialize process-local latch support. This could fail if the kernel
* is low on resources, and if so we want to exit cleanly before acquiring
* any shared-memory resources.
*/
InitializeLatchSupport();
/* /*
* Try to get a proc struct from the free list. If this fails, we must be * Try to get a proc struct from the free list. If this fails, we must be
* out of PGPROC structures (not to mention semaphores). * out of PGPROC structures (not to mention semaphores).
@ -391,10 +384,12 @@ InitProcess(void)
SHMQueueElemInit(&(MyProc->syncRepLinks)); SHMQueueElemInit(&(MyProc->syncRepLinks));
/* /*
* Acquire ownership of the PGPROC's latch, so that we can use WaitLatch. * Acquire ownership of the PGPROC's latch, so that we can use WaitLatch
* Note that there's no particular need to do ResetLatch here. * on it. That allows us to repoint the process latch, which so far
* points to process local one, to the shared one.
*/ */
OwnLatch(&MyProc->procLatch); OwnLatch(&MyProc->procLatch);
SwitchToSharedLatch();
/* /*
* We might be reusing a semaphore that belonged to a failed process. So * We might be reusing a semaphore that belonged to a failed process. So
@ -474,13 +469,6 @@ InitAuxiliaryProcess(void)
if (MyProc != NULL) if (MyProc != NULL)
elog(ERROR, "you already exist"); elog(ERROR, "you already exist");
/*
* Initialize process-local latch support. This could fail if the kernel
* is low on resources, and if so we want to exit cleanly before acquiring
* any shared-memory resources.
*/
InitializeLatchSupport();
/* /*
* We use the ProcStructLock to protect assignment and releasing of * We use the ProcStructLock to protect assignment and releasing of
* AuxiliaryProcs entries. * AuxiliaryProcs entries.
@ -547,10 +535,12 @@ InitAuxiliaryProcess(void)
#endif #endif
/* /*
* Acquire ownership of the PGPROC's latch, so that we can use WaitLatch. * Acquire ownership of the PGPROC's latch, so that we can use WaitLatch
* Note that there's no particular need to do ResetLatch here. * on it. That allows us to repoint the process latch, which so far
* points to process local one, to the shared one.
*/ */
OwnLatch(&MyProc->procLatch); OwnLatch(&MyProc->procLatch);
SwitchToSharedLatch();
/* /*
* We might be reusing a semaphore that belonged to a failed process. So * We might be reusing a semaphore that belonged to a failed process. So
@ -800,10 +790,12 @@ ProcKill(int code, Datum arg)
ReplicationSlotRelease(); ReplicationSlotRelease();
/* /*
* Clear MyProc first; then disown the process latch. This is so that * Reset MyLatch to the process local one. This is so that signal
* signal handlers won't try to clear the process latch after it's no * handlers et al can continue using the latch after the shared latch
* longer ours. * isn't ours anymore. After that clear MyProc and disown the shared
* latch.
*/ */
SwitchBackToLocalLatch();
proc = MyProc; proc = MyProc;
MyProc = NULL; MyProc = NULL;
DisownLatch(&proc->procLatch); DisownLatch(&proc->procLatch);
@ -867,10 +859,12 @@ AuxiliaryProcKill(int code, Datum arg)
LWLockReleaseAll(); LWLockReleaseAll();
/* /*
* Clear MyProc first; then disown the process latch. This is so that * Reset MyLatch to the process local one. This is so that signal
* signal handlers won't try to clear the process latch after it's no * handlers et al can continue using the latch after the shared latch
* longer ours. * isn't ours anymore. After that clear MyProc and disown the shared
* latch.
*/ */
SwitchBackToLocalLatch();
proc = MyProc; proc = MyProc;
MyProc = NULL; MyProc = NULL;
DisownLatch(&proc->procLatch); DisownLatch(&proc->procLatch);

12
src/backend/tcop/postgres.c
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@ -2607,8 +2607,7 @@ die(SIGNAL_ARGS)
} }
/* If we're still here, waken anything waiting on the process latch */ /* If we're still here, waken anything waiting on the process latch */
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -2649,8 +2648,7 @@ StatementCancelHandler(SIGNAL_ARGS)
} }
/* If we're still here, waken anything waiting on the process latch */ /* If we're still here, waken anything waiting on the process latch */
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -2675,8 +2673,7 @@ SigHupHandler(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_SIGHUP = true; got_SIGHUP = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -2814,8 +2811,7 @@ RecoveryConflictInterrupt(ProcSignalReason reason)
* waiting on that latch, expecting to get interrupted by query cancels et * waiting on that latch, expecting to get interrupted by query cancels et
* al., would also need to set set_latch_on_sigusr1. * al., would also need to set set_latch_on_sigusr1.
*/ */
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }

4
src/backend/utils/adt/misc.c
Unescape View File

@ -413,10 +413,10 @@ pg_sleep(PG_FUNCTION_ARGS)
else else
break; break;
(void) WaitLatch(&MyProc->procLatch, (void) WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT, WL_LATCH_SET | WL_TIMEOUT,
delay_ms); delay_ms);
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
} }
PG_RETURN_VOID(); PG_RETURN_VOID();

9
src/backend/utils/init/globals.c
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@ -40,6 +40,15 @@ struct Port *MyProcPort;
long MyCancelKey; long MyCancelKey;
int MyPMChildSlot; int MyPMChildSlot;
/*
* MyLatch points to the latch that should be used for signal handling by the
* current process. It will either point to a process local latch if the
* current process does not have a PGPROC entry in that moment, or to
* PGPROC->procLatch if it has. Thus it can always be used in signal handlers,
* without checking for its existence.
*/
struct Latch *MyLatch;
/* /*
* DataDir is the absolute path to the top level of the PGDATA directory tree. * DataDir is the absolute path to the top level of the PGDATA directory tree.
* Except during early startup, this is also the server's working directory; * Except during early startup, this is also the server's working directory;

37
src/backend/utils/init/miscinit.c
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@ -39,6 +39,7 @@
#include "postmaster/postmaster.h" #include "postmaster/postmaster.h"
#include "storage/fd.h" #include "storage/fd.h"
#include "storage/ipc.h" #include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/pg_shmem.h" #include "storage/pg_shmem.h"
#include "storage/proc.h" #include "storage/proc.h"
#include "storage/procarray.h" #include "storage/procarray.h"
@ -55,6 +56,7 @@ ProcessingMode Mode = InitProcessing;
/* List of lock files to be removed at proc exit */ /* List of lock files to be removed at proc exit */
static List *lock_files = NIL; static List *lock_files = NIL;
static Latch LocalLatchData;
/* ---------------------------------------------------------------- /* ----------------------------------------------------------------
* ignoring system indexes support stuff * ignoring system indexes support stuff
@ -189,6 +191,11 @@ InitPostmasterChild(void)
/* We don't want the postmaster's proc_exit() handlers */ /* We don't want the postmaster's proc_exit() handlers */
on_exit_reset(); on_exit_reset();
/* Initialize process-local latch support */
InitializeLatchSupport();
MyLatch = &LocalLatchData;
InitLatch(MyLatch);
/* /*
* If possible, make this process a group leader, so that the postmaster * If possible, make this process a group leader, so that the postmaster
* can signal any child processes too. Not all processes will have * can signal any child processes too. Not all processes will have
@ -215,6 +222,11 @@ InitStandaloneProcess(const char *argv0)
MyStartTime = time(NULL); /* set our start time in case we call elog */ MyStartTime = time(NULL); /* set our start time in case we call elog */
/* Initialize process-local latch support */
InitializeLatchSupport();
MyLatch = &LocalLatchData;
InitLatch(MyLatch);
/* Compute paths, no postmaster to inherit from */ /* Compute paths, no postmaster to inherit from */
if (my_exec_path[0] == '\0') if (my_exec_path[0] == '\0')
{ {
@ -227,6 +239,31 @@ InitStandaloneProcess(const char *argv0)
get_pkglib_path(my_exec_path, pkglib_path); get_pkglib_path(my_exec_path, pkglib_path);
} }
void
SwitchToSharedLatch(void)
{
Assert(MyLatch == &LocalLatchData);
Assert(MyProc != NULL);
MyLatch = &MyProc->procLatch;
/*
* Set the shared latch as the local one might have been set. This
* shouldn't normally be necessary as code is supposed to check the
* condition before waiting for the latch, but a bit care can't hurt.
*/
SetLatch(MyLatch);
}
void
SwitchBackToLocalLatch(void)
{
Assert(MyLatch != &LocalLatchData);
Assert(MyProc != NULL && MyLatch == &MyProc->procLatch);
MyLatch = &LocalLatchData;
SetLatch(MyLatch);
}
/* /*
* GetUserId - get the current effective user ID. * GetUserId - get the current effective user ID.
* *

6
src/backend/utils/misc/timeout.c
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@ -284,11 +284,9 @@ handle_sig_alarm(SIGNAL_ARGS)
/* /*
* SIGALRM is always cause for waking anything waiting on the process * SIGALRM is always cause for waking anything waiting on the process
* latch. Cope with MyProc not being there, as the startup process also * latch.
* uses this signal handler.
*/ */
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
/* /*
* Fire any pending timeouts, but only if we're enabled to do so. * Fire any pending timeouts, but only if we're enabled to do so.

4
src/include/miscadmin.h
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@ -148,6 +148,7 @@ extern int max_worker_processes;
extern PGDLLIMPORT int MyProcPid; extern PGDLLIMPORT int MyProcPid;
extern PGDLLIMPORT pg_time_t MyStartTime; extern PGDLLIMPORT pg_time_t MyStartTime;
extern PGDLLIMPORT struct Port *MyProcPort; extern PGDLLIMPORT struct Port *MyProcPort;
extern PGDLLIMPORT struct Latch *MyLatch;
extern long MyCancelKey; extern long MyCancelKey;
extern int MyPMChildSlot; extern int MyPMChildSlot;
@ -302,6 +303,9 @@ extern void SetCurrentRoleId(Oid roleid, bool is_superuser);
extern void SetDataDir(const char *dir); extern void SetDataDir(const char *dir);
extern void ChangeToDataDir(void); extern void ChangeToDataDir(void);
extern void SwitchToSharedLatch(void);
extern void SwitchBackToLocalLatch(void);
/* in utils/misc/superuser.c */ /* in utils/misc/superuser.c */
extern bool superuser(void); /* current user is superuser */ extern bool superuser(void); /* current user is superuser */
extern bool superuser_arg(Oid roleid); /* given user is superuser */ extern bool superuser_arg(Oid roleid); /* given user is superuser */

2
src/include/storage/latch.h
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@ -85,7 +85,7 @@
* the public functions. It is defined here to allow embedding Latches as * the public functions. It is defined here to allow embedding Latches as
* part of bigger structs. * part of bigger structs.
*/ */
typedef struct typedef struct Latch
{ {
sig_atomic_t is_set; sig_atomic_t is_set;
bool is_shared; bool is_shared;

4
src/test/modules/test_shm_mq/setup.c
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@ -285,13 +285,13 @@ wait_for_workers_to_become_ready(worker_state *wstate,
} }
/* Wait to be signalled. */ /* Wait to be signalled. */
WaitLatch(&MyProc->procLatch, WL_LATCH_SET, 0); WaitLatch(MyLatch, WL_LATCH_SET, 0);
/* An interrupt may have occurred while we were waiting. */ /* An interrupt may have occurred while we were waiting. */
CHECK_FOR_INTERRUPTS(); CHECK_FOR_INTERRUPTS();
/* Reset the latch so we don't spin. */ /* Reset the latch so we don't spin. */
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
} }
} }
PG_CATCH(); PG_CATCH();

4
src/test/modules/test_shm_mq/test.c
Unescape View File

@ -230,9 +230,9 @@ test_shm_mq_pipelined(PG_FUNCTION_ARGS)
* have read or written data and therefore there may now be work * have read or written data and therefore there may now be work
* for us to do. * for us to do.
*/ */
WaitLatch(&MyProc->procLatch, WL_LATCH_SET, 0); WaitLatch(MyLatch, WL_LATCH_SET, 0);
CHECK_FOR_INTERRUPTS(); CHECK_FOR_INTERRUPTS();
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
} }
} }

3
src/test/modules/test_shm_mq/worker.c
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@ -211,8 +211,7 @@ handle_sigterm(SIGNAL_ARGS)
{ {
int save_errno = errno; int save_errno = errno;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
if (!proc_exit_inprogress) if (!proc_exit_inprogress)
{ {

10
src/test/modules/worker_spi/worker_spi.c
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@ -74,8 +74,7 @@ worker_spi_sigterm(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_sigterm = true; got_sigterm = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -91,8 +90,7 @@ worker_spi_sighup(SIGNAL_ARGS)
int save_errno = errno; int save_errno = errno;
got_sighup = true; got_sighup = true;
if (MyProc) SetLatch(MyLatch);
SetLatch(&MyProc->procLatch);
errno = save_errno; errno = save_errno;
} }
@ -227,10 +225,10 @@ worker_spi_main(Datum main_arg)
* necessary, but is awakened if postmaster dies. That way the * necessary, but is awakened if postmaster dies. That way the
* background process goes away immediately in an emergency. * background process goes away immediately in an emergency.
*/ */
rc = WaitLatch(&MyProc->procLatch, rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
worker_spi_naptime * 1000L); worker_spi_naptime * 1000L);
ResetLatch(&MyProc->procLatch); ResetLatch(MyLatch);
/* emergency bailout if postmaster has died */ /* emergency bailout if postmaster has died */
if (rc & WL_POSTMASTER_DEATH) if (rc & WL_POSTMASTER_DEATH)

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