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Implement LockBufferForCleanup(), which will allow concurrent VACUUM

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to wait until it's safe to remove tuples and compact free space in a
shared buffer page.  Miscellaneous small code cleanups in bufmgr, too.
This commit is contained in:
Tom Lane
2001-07-06 21:04:26 +00:00
parent 1e9e5defc2
commit 55432fedd2
11 changed files with 418 additions and 254 deletions
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47
src/backend/storage/lmgr/proc.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.103 2001/06/16 22:58:16 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.104 2001/07/06 21:04:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -74,6 +74,7 @@
#include "access/xact.h"
#include "storage/proc.h"
#include "storage/sinval.h"
int DeadlockTimeout = 1000;
@ -92,6 +93,7 @@ static PROC_HDR *ProcGlobal = NULL;
PROC *MyProc = NULL;
static bool waitingForLock = false;
static bool waitingForSignal = false;
static void ProcKill(void);
static void ProcGetNewSemIdAndNum(IpcSemaphoreId *semId, int *semNum);
@ -894,6 +896,49 @@ ProcReleaseSpins(PROC *proc)
AbortBufferIO();
}
/*
* ProcWaitForSignal - wait for a signal from another backend.
*
* This can share the semaphore normally used for waiting for locks,
* since a backend could never be waiting for a lock and a signal at
* the same time. As with locks, it's OK if the signal arrives just
* before we actually reach the waiting state.
*/
void
ProcWaitForSignal(void)
{
waitingForSignal = true;
IpcSemaphoreLock(MyProc->sem.semId, MyProc->sem.semNum, true);
waitingForSignal = false;
}
/*
* ProcCancelWaitForSignal - clean up an aborted wait for signal
*
* We need this in case the signal arrived after we aborted waiting,
* or if it arrived but we never reached ProcWaitForSignal() at all.
* Caller should call this after resetting the signal request status.
*/
void
ProcCancelWaitForSignal(void)
{
ZeroProcSemaphore(MyProc);
waitingForSignal = false;
}
/*
* ProcSendSignal - send a signal to a backend identified by BackendId
*/
void
ProcSendSignal(BackendId procId)
{
PROC *proc = BackendIdGetProc(procId);
if (proc != NULL)
IpcSemaphoreUnlock(proc->sem.semId, proc->sem.semNum);
}
/*****************************************************************************
*
*****************************************************************************/