From 2e65230485d84b685858c196f5d64b83bfe3bb94 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Fri, 28 Feb 2025 21:19:08 +0200 Subject: [PATCH 2/3] Use ModifyWaitEvent to update exit_on_postmaster_death This is in preparation for splitting WaitEventSet related functions to a separate source file. That will hide the details of WaitEventSet from WaitLatch, so it must use an exposed function instead of modifying WaitEventSet->exit_on_postmaster_death directly. --- src/backend/storage/ipc/latch.c | 42 +++++++++++++++++++++++---------- 1 file changed, 30 insertions(+), 12 deletions(-) diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c index cd09a10f3d1..ab601c748f8 100644 --- a/src/backend/storage/ipc/latch.c +++ b/src/backend/storage/ipc/latch.c @@ -154,8 +154,9 @@ struct WaitEventSet /* A common WaitEventSet used to implement WaitLatch() */ static WaitEventSet *LatchWaitSet; -/* The position of the latch in LatchWaitSet. */ +/* The positions of the latch and PM death events in LatchWaitSet */ #define LatchWaitSetLatchPos 0 +#define LatchWaitSetPostmasterDeathPos 1 #ifndef WIN32 /* Are we currently in WaitLatch? The signal handler would like to know. */ @@ -353,11 +354,18 @@ InitializeLatchWaitSet(void) LatchWaitSet = CreateWaitEventSet(NULL, 2); latch_pos = AddWaitEventToSet(LatchWaitSet, WL_LATCH_SET, PGINVALID_SOCKET, MyLatch, NULL); - if (IsUnderPostmaster) - AddWaitEventToSet(LatchWaitSet, WL_EXIT_ON_PM_DEATH, - PGINVALID_SOCKET, NULL, NULL); - Assert(latch_pos == LatchWaitSetLatchPos); + + /* + * WaitLatch will modify this to WL_EXIT_ON_PM_DEATH or + * WL_POSTMASTER_DEATH on each call. + */ + if (IsUnderPostmaster) + { + latch_pos = AddWaitEventToSet(LatchWaitSet, WL_EXIT_ON_PM_DEATH, + PGINVALID_SOCKET, NULL, NULL); + Assert(latch_pos == LatchWaitSetPostmasterDeathPos); + } } /* @@ -505,8 +513,14 @@ WaitLatch(Latch *latch, int wakeEvents, long timeout, if (!(wakeEvents & WL_LATCH_SET)) latch = NULL; ModifyWaitEvent(LatchWaitSet, LatchWaitSetLatchPos, WL_LATCH_SET, latch); - LatchWaitSet->exit_on_postmaster_death = - ((wakeEvents & WL_EXIT_ON_PM_DEATH) != 0); + + /* + * Update the event set for whether WL_EXIT_ON_PM_DEATH or + * WL_POSTMASTER_DEATH was requested. This is also cheap. + */ + ModifyWaitEvent(LatchWaitSet, LatchWaitSetPostmasterDeathPos, + (wakeEvents & (WL_EXIT_ON_PM_DEATH | WL_POSTMASTER_DEATH)), + 0); if (WaitEventSetWait(LatchWaitSet, (wakeEvents & WL_TIMEOUT) ? timeout : -1, @@ -1037,15 +1051,19 @@ ModifyWaitEvent(WaitEventSet *set, int pos, uint32 events, Latch *latch) (!(event->events & WL_LATCH_SET) || set->latch == latch)) return; - if (event->events & WL_LATCH_SET && - events != event->events) + /* Allow switching between WL_POSTMASTER_DEATH and WL_EXIT_ON_PM_DEATH */ + if (event->events & WL_POSTMASTER_DEATH) { - elog(ERROR, "cannot modify latch event"); + if (events != WL_POSTMASTER_DEATH && events != WL_EXIT_ON_PM_DEATH) + elog(ERROR, "cannot modify postmaster death event"); + set->exit_on_postmaster_death = ((events & WL_EXIT_ON_PM_DEATH) != 0); + return; } - if (event->events & WL_POSTMASTER_DEATH) + if (event->events & WL_LATCH_SET && + events != event->events) { - elog(ERROR, "cannot modify postmaster death event"); + elog(ERROR, "cannot modify latch event"); } /* FIXME: validate event mask */ -- 2.39.5