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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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52
src/backend/storage/lmgr/proc.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.202 2008/11/02 21:24:52 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.203 2008/12/09 14:28:20 heikki Exp $
*
*-------------------------------------------------------------------------
*/
@ -289,6 +289,7 @@ InitProcess(void)
MyProc->databaseId = InvalidOid;
MyProc->roleId = InvalidOid;
MyProc->inCommit = false;
MemSet(MyProc->signalFlags, 0, NUM_PROCSIGNALS * sizeof(sig_atomic_t));
MyProc->vacuumFlags = 0;
if (IsAutoVacuumWorkerProcess())
MyProc->vacuumFlags |= PROC_IS_AUTOVACUUM;
@ -428,6 +429,7 @@ InitAuxiliaryProcess(void)
MyProc->databaseId = InvalidOid;
MyProc->roleId = InvalidOid;
MyProc->inCommit = false;
MemSet(MyProc->signalFlags, 0, NUM_PROCSIGNALS * sizeof(sig_atomic_t));
/* we don't set the "is autovacuum" flag in the launcher */
MyProc->vacuumFlags = 0;
MyProc->lwWaiting = false;
@ -1277,6 +1279,54 @@ ProcSendSignal(int pid)
PGSemaphoreUnlock(&proc->sem);
}
/*
* SendProcSignal - send the signal with the reason to a process.
*
* The process can be a backend or an auxiliary process that has a PGPROC
* entry, like an autovacuum worker.
*/
void
SendProcSignal(PGPROC *proc, ProcSignalReason reason)
{
pid_t pid;
/*
* If the process is gone, do nothing.
*
* Since there's no locking, it's possible that the process detaches
* from shared memory and exits right after this test, before we set
* the flag and send signal. And the PGPROC entry might even be recycled
* by a new process, so it's remotely possible that we signal a wrong
* process. That's OK, all the signals are such that no harm is done.
*/
pid = proc->pid;
if (pid == 0)
return;
/* Atomically set the proper flag */
proc->signalFlags[reason] = true;
/* Send SIGUSR1 to the process */
kill(pid, SIGUSR1);
}
/*
* CheckProcSignal - check to see if the particular reason has been
* signaled, and clear the signal flag. Should be called after
* receiving SIGUSR1.
*/
bool
CheckProcSignal(ProcSignalReason reason)
{
/* Careful here --- don't clear flag if we haven't seen it set */
if (MyProc->signalFlags[reason])
{
MyProc->signalFlags[reason] = false;
return true;
}
return false;
}
/*****************************************************************************
* SIGALRM interrupt support