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/*-------------------------------------------------------------------------
*
* single.c--
* set single locks in the multi-level lock hierarchy
*
* Sometimes we don't want to set all levels of the multi-level
* lock hierarchy at once. This allows us to set and release
* one level at a time. It's useful in index scans when
* you can set an intent lock at the beginning and thereafter
* only set page locks. Tends to speed things up.
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/Attic/single.c,v 1.5 1997/09/18 20:21:40 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include <string.h>
#include "postgres.h"
#include "storage/lmgr.h" /* where the declarations go */
#include "storage/lock.h"
#include "storage/multilev.h"
#include "utils/rel.h"
/*
* SingleLockReln -- lock a relation
*
* Returns: TRUE if the lock can be set, FALSE otherwise.
*/
bool
SingleLockReln(LockInfo linfo, LOCKT lockt, int action)
{
LOCKTAG tag;
/*
* LOCKTAG has two bytes of padding, unfortunately. The hash function
* will return miss if the padding bytes aren't zero'd.
*/
MemSet(&tag, 0, sizeof(tag));
tag.relId = linfo->lRelId.relId;
tag.dbId = linfo->lRelId.dbId;
BlockIdSet(&(tag.tupleId.ip_blkid), InvalidBlockNumber);
tag.tupleId.ip_posid = InvalidOffsetNumber;
if (action == UNLOCK)
return (LockRelease(MultiTableId, &tag, lockt));
else
return (LockAcquire(MultiTableId, &tag, lockt));
}
/*
* SingleLockPage -- use multi-level lock table, but lock
* only at the page level.
*
* Assumes that an INTENT lock has already been set in the
* multi-level lock table.
*
*/
bool
SingleLockPage(LockInfo linfo,
ItemPointer tidPtr,
LOCKT lockt,
int action)
{
LOCKTAG tag;
/*
* LOCKTAG has two bytes of padding, unfortunately. The hash function
* will return miss if the padding bytes aren't zero'd.
*/
MemSet(&tag, 0, sizeof(tag));
tag.relId = linfo->lRelId.relId;
tag.dbId = linfo->lRelId.dbId;
BlockIdCopy(&(tag.tupleId.ip_blkid), &(tidPtr->ip_blkid));
tag.tupleId.ip_posid = InvalidOffsetNumber;
if (action == UNLOCK)
return (LockRelease(MultiTableId, &tag, lockt));
else
return (LockAcquire(MultiTableId, &tag, lockt));
}
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