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Provide support for multiplexing SIGUSR1 signal. The upcoming synchronous

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replication patch needs a signal, but we've already used SIGUSR1 and
SIGUSR2 in normal backends. This patch allows reusing SIGUSR1 for that,
and for other purposes too if the need arises.
This commit is contained in:
Heikki Linnakangas
2008-12-09 14:28:20 +00:00
parent 9edd720050
commit 7b05b3fa39
10 changed files with 143 additions and 45 deletions
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23
src/backend/storage/ipc/sinval.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.86 2008/06/19 21:32:56 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.87 2008/12/09 14:28:20 heikki Exp $
*
*-------------------------------------------------------------------------
*/
@@ -26,8 +26,8 @@
* Because backends sitting idle will not be reading sinval events, we
* need a way to give an idle backend a swift kick in the rear and make
* it catch up before the sinval queue overflows and forces it to go
* through a cache reset exercise. This is done by sending SIGUSR1
* to any backend that gets too far behind.
* through a cache reset exercise. This is done by sending
* PROCSIG_CATCHUP_INTERRUPT to any backend that gets too far behind.
*
* State for catchup events consists of two flags: one saying whether
* the signal handler is currently allowed to call ProcessCatchupEvent
@@ -144,9 +144,9 @@ ReceiveSharedInvalidMessages(
/*
* CatchupInterruptHandler
* HandleCatchupInterrupt
*
* This is the signal handler for SIGUSR1.
* This is called when PROCSIG_CATCHUP_INTERRUPT signal is received.
*
* If we are idle (catchupInterruptEnabled is set), we can safely
* invoke ProcessCatchupEvent directly. Otherwise, just set a flag
@@ -156,13 +156,11 @@ ReceiveSharedInvalidMessages(
* since there's no longer any reason to do anything.)
*/
void
CatchupInterruptHandler(SIGNAL_ARGS)
HandleCatchupInterrupt(void)
{
int save_errno = errno;
/*
* Note: this is a SIGNAL HANDLER. You must be very wary what you do
* here.
* Note: this is called by a SIGNAL HANDLER.
* You must be very wary what you do here.
*/
/* Don't joggle the elbow of proc_exit */
@@ -216,8 +214,6 @@ CatchupInterruptHandler(SIGNAL_ARGS)
*/
catchupInterruptOccurred = 1;
}
errno = save_errno;
}
/*
@@ -289,7 +285,8 @@ DisableCatchupInterrupt(void)
/*
* ProcessCatchupEvent
*
* Respond to a catchup event (SIGUSR1) from another backend.
* Respond to a catchup event (PROCSIG_CATCHUP_INTERRUPT) from another
* backend.
*
* This is called either directly from the SIGUSR1 signal handler,
* or the next time control reaches the outer idle loop (assuming