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Restructure backend SIGINT/SIGTERM handling so that 'die' interrupts

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are treated more like 'cancel' interrupts: the signal handler sets a
flag that is examined at well-defined spots, rather than trying to cope
with an interrupt that might happen anywhere.  See pghackers discussion
of 1/12/01.
This commit is contained in:
Tom Lane
2001-01-14 05:08:17 +00:00
parent 027f144e39
commit 36839c1927
24 changed files with 614 additions and 479 deletions
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37
src/backend/storage/ipc/spin.c
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@@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/Attic/spin.c,v 1.28 2001/01/12 21:53:59 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/Attic/spin.c,v 1.29 2001/01/14 05:08:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -25,9 +25,11 @@
#include <sys/sem.h>
#endif
#include "miscadmin.h"
#include "storage/proc.h"
#include "storage/s_lock.h"
/* Probably should move these to an appropriate header file */
extern SPINLOCK ShmemLock;
extern SPINLOCK ShmemIndexLock;
@@ -144,20 +146,21 @@ SpinAcquire(SPINLOCK lockid)
SLock *slckP = &(SLockArray[lockid]);
PRINT_SLDEBUG("SpinAcquire", lockid, slckP);
/*
* Lock out die() until we exit the critical section protected by the
* spinlock. This ensures that die() will not interrupt manipulations
* of data structures in shared memory. We don't want die() to
* interrupt this routine between S_LOCK and PROC_INCR_SLOCK, either,
* so must do it before acquiring the lock, not after.
*/
START_CRIT_SECTION();
/*
* Acquire the lock, then record that we have done so (for recovery
* in case of elog(ERROR) during the critical section).
* in case of elog(ERROR) during the critical section). Note we assume
* here that S_LOCK will not accept cancel/die interrupts once it has
* acquired the lock. However, interrupts should be accepted while
* waiting, if CritSectionCount is zero.
*/
S_LOCK(&(slckP->shlock));
PROC_INCR_SLOCK(lockid);
/*
* Lock out cancel/die interrupts until we exit the critical section
* protected by the spinlock. This ensures that interrupts will not
* interfere with manipulations of data structures in shared memory.
*/
START_CRIT_SECTION();
PRINT_SLDEBUG("SpinAcquire/done", lockid, slckP);
}
@@ -317,10 +320,16 @@ SpinFreeAllSemaphores(void)
void
SpinAcquire(SPINLOCK lock)
{
/* See the TAS() version of this routine for commentary */
START_CRIT_SECTION();
IpcSemaphoreLock(SpinLockIds[0], lock);
/*
* See the TAS() version of this routine for primary commentary.
*
* NOTE we must pass interruptOK = false to IpcSemaphoreLock, to ensure
* that a cancel/die interrupt cannot prevent us from recording ownership
* of a lock we have just acquired.
*/
IpcSemaphoreLock(SpinLockIds[0], lock, false);
PROC_INCR_SLOCK(lock);
START_CRIT_SECTION();
}
/*
@@ -338,8 +347,8 @@ SpinRelease(SPINLOCK lock)
semval = IpcSemaphoreGetValue(SpinLockIds[0], lock);
Assert(semval < 1);
Assert(!MyProc || MyProc->sLocks[lockid] > 0);
#endif
Assert(!MyProc || MyProc->sLocks[lockid] > 0);
PROC_DECR_SLOCK(lock);
IpcSemaphoreUnlock(SpinLockIds[0], lock);
END_CRIT_SECTION();