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Use ModifyWaitEvent to update exit_on_postmaster_death

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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.

Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://www.postgresql.org/message-id/8a507fb6-df28-49d3-81a5-ede180d7f0fb@iki.fi
This commit is contained in:
Heikki Linnakangas
2025-03-06 01:26:12 +02:00
parent 9f25b9f739
commit 84e5b2f07a
1 changed files with 32 additions and 16 deletions
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48
src/backend/storage/ipc/latch.c
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@ -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 +513,9 @@ 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);
ModifyWaitEvent(LatchWaitSet, LatchWaitSetPostmasterDeathPos,
(wakeEvents & (WL_EXIT_ON_PM_DEATH | WL_POSTMASTER_DEATH)),
NULL);
if (WaitEventSetWait(LatchWaitSet,
(wakeEvents & WL_TIMEOUT) ? timeout : -1,
@ -1027,6 +1036,21 @@ ModifyWaitEvent(WaitEventSet *set, int pos, uint32 events, Latch *latch)
old_events = event->events;
#endif
/*
* Allow switching between WL_POSTMASTER_DEATH and WL_EXIT_ON_PM_DEATH.
*
* Note that because WL_EXIT_ON_PM_DEATH is mapped to WL_POSTMASTER_DEATH
* in AddWaitEventToSet(), this needs to be checked before the fast-path
* below that checks if 'events' has changed.
*/
if (event->events == WL_POSTMASTER_DEATH)
{
if (events != WL_POSTMASTER_DEATH && events != WL_EXIT_ON_PM_DEATH)
elog(ERROR, "cannot remove postmaster death event");
set->exit_on_postmaster_death = ((events & WL_EXIT_ON_PM_DEATH) != 0);
return;
}
/*
* If neither the event mask nor the associated latch changes, return
* early. That's an important optimization for some sockets, where
@ -1037,16 +1061,8 @@ 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)
{
if (event->events & WL_LATCH_SET && events != event->events)
elog(ERROR, "cannot modify latch event");
}
if (event->events & WL_POSTMASTER_DEATH)
{
elog(ERROR, "cannot modify postmaster death event");
}
/* FIXME: validate event mask */
event->events = events;