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Change the autovacuum launcher to use WaitLatch instead of a poll loop.

Browse Source 
In pursuit of this (and with the expectation that WaitLatch will be needed
in more places), convert the latch field that was already added to PGPROC
for sync rep into a generic latch that is activated for all PGPROC-owning
processes, and change many of the standard backend signal handlers to set
that latch when a signal happens.  This will allow WaitLatch callers to be
wakened properly by these signals.

In passing, fix a whole bunch of signal handlers that had been hacked to do
things that might change errno, without adding the necessary save/restore
logic for errno.  Also make some minor fixes in unix_latch.c, and clean
up bizarre and unsafe scheme for disowning the process's latch.  Much of
this has to be back-patched into 9.1.

Peter Geoghegan, with additional work by Tom
This commit is contained in:
Tom Lane
2011-08-10 12:20:30 -04:00
parent 1f1b70a7cf
commit 4dab3d5ae1
11 changed files with 186 additions and 77 deletions
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20
src/backend/replication/syncrep.c
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@@ -111,9 +111,6 @@ SyncRepWaitForLSN(XLogRecPtr XactCommitLSN)
Assert(SHMQueueIsDetached(&(MyProc->syncRepLinks)));
Assert(WalSndCtl != NULL);
/* Reset the latch before adding ourselves to the queue. */
ResetLatch(&MyProc->waitLatch);
LWLockAcquire(SyncRepLock, LW_EXCLUSIVE);
Assert(MyProc->syncRepState == SYNC_REP_NOT_WAITING);
@@ -167,7 +164,7 @@ SyncRepWaitForLSN(XLogRecPtr XactCommitLSN)
int syncRepState;
/* Must reset the latch before testing state. */
ResetLatch(&MyProc->waitLatch);
ResetLatch(&MyProc->procLatch);
/*
* Try checking the state without the lock first. There's no
@@ -247,11 +244,10 @@ SyncRepWaitForLSN(XLogRecPtr XactCommitLSN)
}
/*
* Wait on latch for up to 60 seconds. This allows us to check for
* cancel/die signal or postmaster death regularly while waiting. Note
* that timeout here does not necessarily release from loop.
* Wait on latch. Any condition that should wake us up will set
* the latch, so no need for timeout.
*/
WaitLatch(&MyProc->waitLatch, WL_LATCH_SET | WL_TIMEOUT, 60000L);
WaitLatch(&MyProc->procLatch, WL_LATCH_SET | WL_POSTMASTER_DEATH, -1);
}
/*
@@ -322,7 +318,7 @@ SyncRepCancelWait(void)
}
void
SyncRepCleanupAtProcExit(int code, Datum arg)
SyncRepCleanupAtProcExit(void)
{
if (!SHMQueueIsDetached(&(MyProc->syncRepLinks)))
{
@@ -330,8 +326,6 @@ SyncRepCleanupAtProcExit(int code, Datum arg)
SHMQueueDelete(&(MyProc->syncRepLinks));
LWLockRelease(SyncRepLock);
}
DisownLatch(&MyProc->waitLatch);
}
/*
@@ -567,9 +561,7 @@ SyncRepWakeQueue(bool all)
/*
* Wake only when we have set state and removed from queue.
*/
Assert(SHMQueueIsDetached(&(thisproc->syncRepLinks)));
Assert(thisproc->syncRepState == SYNC_REP_WAIT_COMPLETE);
SetLatch(&(thisproc->waitLatch));
SetLatch(&(thisproc->procLatch));
numprocs++;
}