lmgr.c

postgresql8.3.4源码,开源数据库

					  relation->rd_lockInfo.lockRelId.dbId,
					  relation->rd_lockInfo.lockRelId.relId,
					  ItemPointerGetBlockNumber(tid),
					  ItemPointerGetOffsetNumber(tid));

	(void) LockAcquire(&tag, lockmode, false, false);
}

/*
 *		ConditionalLockTuple
 *
 * As above, but only lock if we can get the lock without blocking.
 * Returns TRUE iff the lock was acquired.
 */
bool
ConditionalLockTuple(Relation relation, ItemPointer tid, LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SET_LOCKTAG_TUPLE(tag,
					  relation->rd_lockInfo.lockRelId.dbId,
					  relation->rd_lockInfo.lockRelId.relId,
					  ItemPointerGetBlockNumber(tid),
					  ItemPointerGetOffsetNumber(tid));

	return (LockAcquire(&tag, lockmode, false, true) != LOCKACQUIRE_NOT_AVAIL);
}

/*
 *		UnlockTuple
 */
void
UnlockTuple(Relation relation, ItemPointer tid, LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SET_LOCKTAG_TUPLE(tag,
					  relation->rd_lockInfo.lockRelId.dbId,
					  relation->rd_lockInfo.lockRelId.relId,
					  ItemPointerGetBlockNumber(tid),
					  ItemPointerGetOffsetNumber(tid));

	LockRelease(&tag, lockmode, false);
}

/*
 *		XactLockTableInsert
 *
 * Insert a lock showing that the given transaction ID is running ---
 * this is done when an XID is acquired by a transaction or subtransaction.
 * The lock can then be used to wait for the transaction to finish.
 */
void
XactLockTableInsert(TransactionId xid)
{
	LOCKTAG		tag;

	SET_LOCKTAG_TRANSACTION(tag, xid);

	(void) LockAcquire(&tag, ExclusiveLock, false, false);
}

/*
 *		XactLockTableDelete
 *
 * Delete the lock showing that the given transaction ID is running.
 * (This is never used for main transaction IDs; those locks are only
 * released implicitly at transaction end.	But we do use it for subtrans IDs.)
 */
void
XactLockTableDelete(TransactionId xid)
{
	LOCKTAG		tag;

	SET_LOCKTAG_TRANSACTION(tag, xid);

	LockRelease(&tag, ExclusiveLock, false);
}

/*
 *		XactLockTableWait
 *
 * Wait for the specified transaction to commit or abort.
 *
 * Note that this does the right thing for subtransactions: if we wait on a
 * subtransaction, we will exit as soon as it aborts or its top parent commits.
 * It takes some extra work to ensure this, because to save on shared memory
 * the XID lock of a subtransaction is released when it ends, whether
 * successfully or unsuccessfully.	So we have to check if it's "still running"
 * and if so wait for its parent.
 */
void
XactLockTableWait(TransactionId xid)
{
	LOCKTAG		tag;

	for (;;)
	{
		Assert(TransactionIdIsValid(xid));
		Assert(!TransactionIdEquals(xid, GetTopTransactionIdIfAny()));

		SET_LOCKTAG_TRANSACTION(tag, xid);

		(void) LockAcquire(&tag, ShareLock, false, false);

		LockRelease(&tag, ShareLock, false);

		if (!TransactionIdIsInProgress(xid))
			break;
		xid = SubTransGetParent(xid);
	}
}

/*
 *		ConditionalXactLockTableWait
 *
 * As above, but only lock if we can get the lock without blocking.
 * Returns TRUE if the lock was acquired.
 */
bool
ConditionalXactLockTableWait(TransactionId xid)
{
	LOCKTAG		tag;

	for (;;)
	{
		Assert(TransactionIdIsValid(xid));
		Assert(!TransactionIdEquals(xid, GetTopTransactionIdIfAny()));

		SET_LOCKTAG_TRANSACTION(tag, xid);

		if (LockAcquire(&tag, ShareLock, false, true) == LOCKACQUIRE_NOT_AVAIL)
			return false;

		LockRelease(&tag, ShareLock, false);

		if (!TransactionIdIsInProgress(xid))
			break;
		xid = SubTransGetParent(xid);
	}

	return true;
}


/*
 *		VirtualXactLockTableInsert
 *
 * Insert a lock showing that the given virtual transaction ID is running ---
 * this is done at main transaction start when its VXID is assigned.
 * The lock can then be used to wait for the transaction to finish.
 */
void
VirtualXactLockTableInsert(VirtualTransactionId vxid)
{
	LOCKTAG		tag;

	Assert(VirtualTransactionIdIsValid(vxid));

	SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);

	(void) LockAcquire(&tag, ExclusiveLock, false, false);
}

/*
 *		VirtualXactLockTableWait
 *
 * Waits until the lock on the given VXID is released, which shows that
 * the top-level transaction owning the VXID has ended.
 */
void
VirtualXactLockTableWait(VirtualTransactionId vxid)
{
	LOCKTAG		tag;

	Assert(VirtualTransactionIdIsValid(vxid));

	SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);

	(void) LockAcquire(&tag, ShareLock, false, false);

	LockRelease(&tag, ShareLock, false);
}

/*
 *		ConditionalVirtualXactLockTableWait
 *
 * As above, but only lock if we can get the lock without blocking.
 * Returns TRUE if the lock was acquired.
 */
bool
ConditionalVirtualXactLockTableWait(VirtualTransactionId vxid)
{
	LOCKTAG		tag;

	Assert(VirtualTransactionIdIsValid(vxid));

	SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);

	if (LockAcquire(&tag, ShareLock, false, true) == LOCKACQUIRE_NOT_AVAIL)
		return false;

	LockRelease(&tag, ShareLock, false);

	return true;
}


/*
 *		LockDatabaseObject
 *
 * Obtain a lock on a general object of the current database.  Don't use
 * this for shared objects (such as tablespaces).  It's unwise to apply it
 * to relations, also, since a lock taken this way will NOT conflict with
 * locks taken via LockRelation and friends.
 */
void
LockDatabaseObject(Oid classid, Oid objid, uint16 objsubid,
				   LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SET_LOCKTAG_OBJECT(tag,
					   MyDatabaseId,
					   classid,
					   objid,
					   objsubid);

	(void) LockAcquire(&tag, lockmode, false, false);
}

/*
 *		UnlockDatabaseObject
 */
void
UnlockDatabaseObject(Oid classid, Oid objid, uint16 objsubid,
					 LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SET_LOCKTAG_OBJECT(tag,
					   MyDatabaseId,
					   classid,
					   objid,
					   objsubid);

	LockRelease(&tag, lockmode, false);
}

/*
 *		LockSharedObject
 *
 * Obtain a lock on a shared-across-databases object.
 */
void
LockSharedObject(Oid classid, Oid objid, uint16 objsubid,
				 LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SET_LOCKTAG_OBJECT(tag,
					   InvalidOid,
					   classid,
					   objid,
					   objsubid);

	(void) LockAcquire(&tag, lockmode, false, false);

	/* Make sure syscaches are up-to-date with any changes we waited for */
	AcceptInvalidationMessages();
}

/*
 *		UnlockSharedObject
 */
void
UnlockSharedObject(Oid classid, Oid objid, uint16 objsubid,
				   LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SET_LOCKTAG_OBJECT(tag,
					   InvalidOid,
					   classid,
					   objid,
					   objsubid);

	LockRelease(&tag, lockmode, false);
}


/*
 * Append a description of a lockable object to buf.
 *
 * Ideally we would print names for the numeric values, but that requires
 * getting locks on system tables, which might cause problems since this is
 * typically used to report deadlock situations.
 */
void
DescribeLockTag(StringInfo buf, const LOCKTAG *tag)
{
	switch ((LockTagType) tag->locktag_type)
	{
		case LOCKTAG_RELATION:
			appendStringInfo(buf,
							 _("relation %u of database %u"),
							 tag->locktag_field2,
							 tag->locktag_field1);
			break;
		case LOCKTAG_RELATION_EXTEND:
			appendStringInfo(buf,
							 _("extension of relation %u of database %u"),
							 tag->locktag_field2,
							 tag->locktag_field1);
			break;
		case LOCKTAG_PAGE:
			appendStringInfo(buf,
							 _("page %u of relation %u of database %u"),
							 tag->locktag_field3,
							 tag->locktag_field2,
							 tag->locktag_field1);
			break;
		case LOCKTAG_TUPLE:
			appendStringInfo(buf,
							 _("tuple (%u,%u) of relation %u of database %u"),
							 tag->locktag_field3,
							 tag->locktag_field4,
							 tag->locktag_field2,
							 tag->locktag_field1);
			break;
		case LOCKTAG_TRANSACTION:
			appendStringInfo(buf,
							 _("transaction %u"),
							 tag->locktag_field1);
			break;
		case LOCKTAG_VIRTUALTRANSACTION:
			appendStringInfo(buf,
							 _("virtual transaction %d/%u"),
							 tag->locktag_field1,
							 tag->locktag_field2);
			break;
		case LOCKTAG_OBJECT:
			appendStringInfo(buf,
							 _("object %u of class %u of database %u"),
							 tag->locktag_field3,
							 tag->locktag_field2,
							 tag->locktag_field1);
			break;
		case LOCKTAG_USERLOCK:
			/* reserved for old contrib code, now on pgfoundry */
			appendStringInfo(buf,
							 _("user lock [%u,%u,%u]"),
							 tag->locktag_field1,
							 tag->locktag_field2,
							 tag->locktag_field3);
			break;
		case LOCKTAG_ADVISORY:
			appendStringInfo(buf,
							 _("advisory lock [%u,%u,%u,%u]"),
							 tag->locktag_field1,
							 tag->locktag_field2,
							 tag->locktag_field3,
							 tag->locktag_field4);
			break;
		default:
			appendStringInfo(buf,
							 _("unrecognized locktag type %d"),
							 (int) tag->locktag_type);
			break;
	}
}