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Clean up latch related code.

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The larger part of this patch replaces usages of MyProc->procLatch
with MyLatch.  The latter works even early during backend startup,
where MyProc->procLatch doesn't yet.  While the affected code
shouldn't run in cases where it's not initialized, it might get copied
into places where it might.  Using MyLatch is simpler and a bit faster
to boot, so there's little point to stick with the previous coding.

While doing so I noticed some weaknesses around newly introduced uses
of latches that could lead to missed events, and an omitted
CHECK_FOR_INTERRUPTS() call in worker_spi.

As all the actual bugs are in v10 code, there doesn't seem to be
sufficient reason to backpatch this.

Author: Andres Freund
Discussion:
    https://postgr.es/m/20170606195321.sjmenrfgl2nu6j63@alap3.anarazel.de
    https://postgr.es/m/20170606210405.sim3yl6vpudhmufo@alap3.anarazel.de
Backpatch: -
This commit is contained in:
Andres Freund
2017-06-06 16:13:00 -07:00
parent e3a815d2fa
commit 9206ced1dc
9 changed files with 56 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

35
src/backend/replication/logical/launcher.c
View File

@@ -208,10 +208,15 @@ WaitForReplicationWorkerAttach(LogicalRepWorker *worker,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
1000L, WAIT_EVENT_BGWORKER_STARTUP);
/* emergency bailout if postmaster has died */
if (rc & WL_POSTMASTER_DEATH)
proc_exit(1);
ResetLatch(MyLatch);
if (rc & WL_LATCH_SET)
{
ResetLatch(MyLatch);
CHECK_FOR_INTERRUPTS();
}
}
return;
@@ -440,10 +445,8 @@ logicalrep_worker_stop(Oid subid, Oid relid)
LWLockRelease(LogicalRepWorkerLock);
CHECK_FOR_INTERRUPTS();
/* Wait for signal. */
rc = WaitLatch(&MyProc->procLatch,
rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
1000L, WAIT_EVENT_BGWORKER_STARTUP);
@@ -451,7 +454,11 @@ logicalrep_worker_stop(Oid subid, Oid relid)
if (rc & WL_POSTMASTER_DEATH)
proc_exit(1);
ResetLatch(&MyProc->procLatch);
if (rc & WL_LATCH_SET)
{
ResetLatch(MyLatch);
CHECK_FOR_INTERRUPTS();
}
/* Check worker status. */
LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
@@ -492,7 +499,7 @@ logicalrep_worker_stop(Oid subid, Oid relid)
CHECK_FOR_INTERRUPTS();
/* Wait for more work. */
rc = WaitLatch(&MyProc->procLatch,
rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
1000L, WAIT_EVENT_BGWORKER_SHUTDOWN);
@@ -500,7 +507,11 @@ logicalrep_worker_stop(Oid subid, Oid relid)
if (rc & WL_POSTMASTER_DEATH)
proc_exit(1);
ResetLatch(&MyProc->procLatch);
if (rc & WL_LATCH_SET)
{
ResetLatch(MyLatch);
CHECK_FOR_INTERRUPTS();
}
}
}
@@ -876,7 +887,7 @@ ApplyLauncherMain(Datum main_arg)
}
/* Wait for more work. */
rc = WaitLatch(&MyProc->procLatch,
rc = WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
wait_time,
WAIT_EVENT_LOGICAL_LAUNCHER_MAIN);
@@ -885,13 +896,17 @@ ApplyLauncherMain(Datum main_arg)
if (rc & WL_POSTMASTER_DEATH)
proc_exit(1);
if (rc & WL_LATCH_SET)
{
ResetLatch(MyLatch);
CHECK_FOR_INTERRUPTS();
}
if (got_SIGHUP)
{
got_SIGHUP = false;
ProcessConfigFile(PGC_SIGHUP);
}
ResetLatch(&MyProc->procLatch);
}
LogicalRepCtx->launcher_pid = 0;