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/*-------------------------------------------------------------------------
*
* lmgr.c
* POSTGRES lock manager code
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lmgr.c,v 1.48 2001/06/22 00:04:59 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "miscadmin.h"
#include "storage/lmgr.h"
#include "utils/inval.h"
static LOCKMASK LockConflicts[] = {
0,
/* AccessShareLock */
(1 << AccessExclusiveLock),
/* RowShareLock */
(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
/* RowExclusiveLock */
(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) | (1 << ShareLock) |
(1 << AccessExclusiveLock),
/* ShareLock */
(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) |
(1 << RowExclusiveLock) | (1 << AccessExclusiveLock),
/* ShareRowExclusiveLock */
(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) |
(1 << ShareLock) | (1 << RowExclusiveLock) | (1 << AccessExclusiveLock),
/* ExclusiveLock */
(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) | (1 << ShareLock) |
(1 << RowExclusiveLock) | (1 << RowShareLock) | (1 << AccessExclusiveLock),
/* AccessExclusiveLock */
(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) | (1 << ShareLock) |
(1 << RowExclusiveLock) | (1 << RowShareLock) |
(1 << AccessExclusiveLock) | (1 << AccessShareLock)
};
static int LockPrios[] = {
0,
/* AccessShareLock */
1,
/* RowShareLock */
2,
/* RowExclusiveLock */
3,
/* ShareLock */
4,
/* ShareRowExclusiveLock */
5,
/* ExclusiveLock */
6,
/* AccessExclusiveLock */
7
};
LOCKMETHOD LockTableId = (LOCKMETHOD) NULL;
LOCKMETHOD LongTermTableId = (LOCKMETHOD) NULL;
/*
* Create the lock table described by LockConflicts and LockPrios.
*/
LOCKMETHOD
InitLockTable(int maxBackends)
{
int lockmethod;
lockmethod = LockMethodTableInit("LockTable",
LockConflicts, LockPrios,
MAX_LOCKMODES - 1, maxBackends);
LockTableId = lockmethod;
if (!(LockTableId))
elog(ERROR, "InitLockTable: couldn't initialize lock table");
#ifdef USER_LOCKS
/*
* Allocate another tableId for long-term locks
*/
LongTermTableId = LockMethodTableRename(LockTableId);
if (!(LongTermTableId))
elog(ERROR, "InitLockTable: couldn't rename long-term lock table");
#endif
return LockTableId;
}
/*
* RelationInitLockInfo
* Initializes the lock information in a relation descriptor.
*
* relcache.c must call this during creation of any reldesc.
*/
void
RelationInitLockInfo(Relation relation)
{
Assert(RelationIsValid(relation));
Assert(OidIsValid(RelationGetRelid(relation)));
relation->rd_lockInfo.lockRelId.relId = RelationGetRelid(relation);
if (relation->rd_rel->relisshared)
relation->rd_lockInfo.lockRelId.dbId = InvalidOid;
else
relation->rd_lockInfo.lockRelId.dbId = MyDatabaseId;
}
/*
* LockRelation
*/
void
LockRelation(Relation relation, LOCKMODE lockmode)
{
LOCKTAG tag;
if (LockingDisabled())
return;
MemSet(&tag, 0, sizeof(tag));
tag.relId = relation->rd_lockInfo.lockRelId.relId;
tag.dbId = relation->rd_lockInfo.lockRelId.dbId;
tag.objId.blkno = InvalidBlockNumber;
if (!LockAcquire(LockTableId, &tag, GetCurrentTransactionId(),
lockmode, false))
elog(ERROR, "LockRelation: LockAcquire failed");
/*
* Check to see if the relcache entry has been invalidated while we
* were waiting to lock it. If so, rebuild it, or elog() trying.
* Increment the refcount to ensure that RelationFlushRelation will
* rebuild it and not just delete it.
*/
RelationIncrementReferenceCount(relation);
AcceptInvalidationMessages();
RelationDecrementReferenceCount(relation);
}
/*
* ConditionalLockRelation
*
* As above, but only lock if we can get the lock without blocking.
* Returns TRUE iff the lock was acquired.
*
* NOTE: we do not currently need conditional versions of the other
* LockXXX routines in this file, but they could easily be added if needed.
*/
bool
ConditionalLockRelation(Relation relation, LOCKMODE lockmode)
{
LOCKTAG tag;
if (LockingDisabled())
return true;
MemSet(&tag, 0, sizeof(tag));
tag.relId = relation->rd_lockInfo.lockRelId.relId;
tag.dbId = relation->rd_lockInfo.lockRelId.dbId;
tag.objId.blkno = InvalidBlockNumber;
if (!LockAcquire(LockTableId, &tag, GetCurrentTransactionId(),
lockmode, true))
return false;
/*
* Check to see if the relcache entry has been invalidated while we
* were waiting to lock it. If so, rebuild it, or elog() trying.
* Increment the refcount to ensure that RelationFlushRelation will
* rebuild it and not just delete it.
*/
RelationIncrementReferenceCount(relation);
AcceptInvalidationMessages();
RelationDecrementReferenceCount(relation);
return true;
}
/*
* UnlockRelation
*/
void
UnlockRelation(Relation relation, LOCKMODE lockmode)
{
LOCKTAG tag;
if (LockingDisabled())
return;
MemSet(&tag, 0, sizeof(tag));
tag.relId = relation->rd_lockInfo.lockRelId.relId;
tag.dbId = relation->rd_lockInfo.lockRelId.dbId;
tag.objId.blkno = InvalidBlockNumber;
LockRelease(LockTableId, &tag, GetCurrentTransactionId(), lockmode);
}
/*
* LockRelationForSession
*
* This routine grabs a session-level lock on the target relation. The
* session lock persists across transaction boundaries. It will be removed
* when UnlockRelationForSession() is called, or if an elog(ERROR) occurs,
* or if the backend exits.
*
* Note that one should also grab a transaction-level lock on the rel
* in any transaction that actually uses the rel, to ensure that the
* relcache entry is up to date.
*/
void
LockRelationForSession(LockRelId *relid, LOCKMODE lockmode)
{
LOCKTAG tag;
if (LockingDisabled())
return;
MemSet(&tag, 0, sizeof(tag));
tag.relId = relid->relId;
tag.dbId = relid->dbId;
tag.objId.blkno = InvalidBlockNumber;
if (!LockAcquire(LockTableId, &tag, InvalidTransactionId,
lockmode, false))
elog(ERROR, "LockRelationForSession: LockAcquire failed");
}
/*
* UnlockRelationForSession
*/
void
UnlockRelationForSession(LockRelId *relid, LOCKMODE lockmode)
{
LOCKTAG tag;
if (LockingDisabled())
return;
MemSet(&tag, 0, sizeof(tag));
tag.relId = relid->relId;
tag.dbId = relid->dbId;
tag.objId.blkno = InvalidBlockNumber;
LockRelease(LockTableId, &tag, InvalidTransactionId, lockmode);
}
/*
* LockPage
*/
void
LockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode)
{
LOCKTAG tag;
if (LockingDisabled())
return;
MemSet(&tag, 0, sizeof(tag));
tag.relId = relation->rd_lockInfo.lockRelId.relId;
tag.dbId = relation->rd_lockInfo.lockRelId.dbId;
tag.objId.blkno = blkno;
if (!LockAcquire(LockTableId, &tag, GetCurrentTransactionId(),
lockmode, false))
elog(ERROR, "LockPage: LockAcquire failed");
}
/*
* UnlockPage
*/
void
UnlockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode)
{
LOCKTAG tag;
if (LockingDisabled())
return;
MemSet(&tag, 0, sizeof(tag));
tag.relId = relation->rd_lockInfo.lockRelId.relId;
tag.dbId = relation->rd_lockInfo.lockRelId.dbId;
tag.objId.blkno = blkno;
LockRelease(LockTableId, &tag, GetCurrentTransactionId(), lockmode);
}
void
XactLockTableInsert(TransactionId xid)
{
LOCKTAG tag;
if (LockingDisabled())
return;
MemSet(&tag, 0, sizeof(tag));
tag.relId = XactLockTableId;
tag.dbId = InvalidOid; /* xids are globally unique */
tag.objId.xid = xid;
if (!LockAcquire(LockTableId, &tag, xid,
ExclusiveLock, false))
elog(ERROR, "XactLockTableInsert: LockAcquire failed");
}
#ifdef NOT_USED
void
XactLockTableDelete(TransactionId xid)
{
LOCKTAG tag;
if (LockingDisabled())
return;
MemSet(&tag, 0, sizeof(tag));
tag.relId = XactLockTableId;
tag.dbId = InvalidOid;
tag.objId.xid = xid;
LockRelease(LockTableId, &tag, xid, ExclusiveLock);
}
#endif
void
XactLockTableWait(TransactionId xid)
{
LOCKTAG tag;
if (LockingDisabled())
return;
MemSet(&tag, 0, sizeof(tag));
tag.relId = XactLockTableId;
tag.dbId = InvalidOid;
tag.objId.xid = xid;
if (!LockAcquire(LockTableId, &tag, GetCurrentTransactionId(),
ShareLock, false))
elog(ERROR, "XactLockTableWait: LockAcquire failed");
LockRelease(LockTableId, &tag, GetCurrentTransactionId(), ShareLock);
/*
* Transaction was committed/aborted/crashed - we have to update
* pg_log if transaction is still marked as running.
*/
if (!TransactionIdDidCommit(xid) && !TransactionIdDidAbort(xid))
TransactionIdAbort(xid);
}