C++ LockRelease函数代码示例

/*
 * update hash entry with state 
 */		
static int 
FaultInjector_UpdateHashEntry(
							FaultInjectorEntry_s	*entry)
{
	
	FaultInjectorEntry_s	*entryLocal;
	bool					exists;
	int						status = STATUS_OK;

	LockAcquire();

	entryLocal = FaultInjector_InsertHashEntry(entry->faultInjectorIdentifier, &exists);
	
	/* entry should be found since fault has not been injected yet */			
	Assert(entryLocal != NULL);
	
	if (!exists) {
		LockRelease();
		status = STATUS_ERROR;
		ereport(WARNING,
				(errmsg("could not update fault injection hash entry with fault injection status, "
						"no entry found, "
						"fault name:'%s' fault type:'%s' ",
						FaultInjectorIdentifierEnumToString[entry->faultInjectorIdentifier],
						FaultInjectorTypeEnumToString[entry->faultInjectorType])));
		goto exit;
	}
	
	if (entry->faultInjectorType == FaultInjectorTypeResume)
	{
		entryLocal->faultInjectorType = FaultInjectorTypeResume;
	}
	else
	{	
		entryLocal->faultInjectorState = entry->faultInjectorState;
		entryLocal->occurrence = entry->occurrence;
	}
	
	LockRelease();
	
	ereport(DEBUG1,
			(errmsg("LOG(fault injector): update fault injection hash entry "
					"identifier:'%s' state:'%s' occurrence:'%d' ",
					FaultInjectorIdentifierEnumToString[entry->faultInjectorIdentifier], 
					FaultInjectorStateEnumToString[entryLocal->faultInjectorState],
					entry->occurrence)));
	
exit:	
	
	return status;			
}

/*
 *		XactLockTableWait
 *
 * Wait for the specified transaction to commit or abort.
 */
void
XactLockTableWait(TransactionId xid)
{
	LOCKTAG		tag;
	TransactionId myxid = GetCurrentTransactionId();

	Assert(!TransactionIdEquals(xid, myxid));

	MemSet(&tag, 0, sizeof(tag));
	tag.relId = XactLockTableId;
	tag.dbId = InvalidOid;
	tag.objId.xid = xid;

	if (!LockAcquire(LockTableId, &tag, myxid,
					 ShareLock, false))
		elog(ERROR, "LockAcquire failed");

	LockRelease(LockTableId, &tag, myxid, ShareLock);

	/*
	 * Transaction was committed/aborted/crashed - we have to update
	 * pg_clog if transaction is still marked as running.
	 */
	if (!TransactionIdDidCommit(xid) && !TransactionIdDidAbort(xid))
		TransactionIdAbort(xid);
}

//---------------------------------------------------------------------------
//	CondHandleWait
//
//	This function makes the calling process block on the condition variable
//	till either ConditionHandleSignal or ConditionHandleBroadcast is
//	received. The process calling CondHandleWait must have acquired the
//	lock associated with the condition variable (the lock that was passed
//	to CondCreate. This implies the lock handle needs to be stored
//	somewhere. hint! hint!) for this function to
//	succeed. If the calling process has not acquired the lock, it does not
//	block on the condition variable, but a value of 1 is returned
//	indicating that the call was not successful. Return value of 0 implies
//	that the call was successful.
//
//	This function should be written in such a way that the calling process
//	should release the lock associated with this condition variable before
//	going to sleep, so that the process that intends to signal this
//	process could acquire the lock for that purpose. After waking up, the
//	blocked process should acquire (i.e. wait on) the lock associated with
//	the condition variable. In other words, this process does not
//	"actually" wake up until the process calling CondHandleSignal or
//	CondHandleBroadcast releases the lock explicitly.
//---------------------------------------------------------------------------
int CondWait(Cond *c) {
  Link	*l;
  int   intrval;
    
  if (!c) return SYNC_FAIL;

  // Conds are atomic
  intrval = DisableIntrs ();
  dbprintf ('I', "CondWait: Old interrupt value was 0x%x.\n", intrval);

  // Check to see if the current process owns the lock
  if (c->lock->pid != GetCurrentPid()) {
    dbprintf('s', "CondWait: Proc %d does not own cond %d\n", GetCurrentPid(), (int)(c-conds));
    RestoreIntrs(intrval);
    return SYNC_FAIL;
  }

  dbprintf ('s', "CondWait: Proc %d waiting on cond %d.  Putting to sleep.\n", GetCurrentPid(), (int)(c-conds));
  if ((l = AQueueAllocLink ((void *)currentPCB)) == NULL) {
    printf("FATAL ERROR: could not allocate link for cond queue in CondWait!\n");
    exitsim();
  }
  if (AQueueInsertLast (&c->waiting, l) != QUEUE_SUCCESS) {
    printf("FATAL ERROR: could not insert new link into cond waiting queue in CondWait!\n");
    exitsim();
  }
  // Release the lock before going to sleep
  LockRelease(c->lock);
  RestoreIntrs(intrval); // Don't want interrupts disabled while we sleep
  ProcessSleep();
  // Immediately acquire the lock upon waking
  LockAcquire(c->lock);
  return SYNC_SUCCESS;
}

bool
FaultInjector_IsFaultInjected(
							  FaultInjectorIdentifier_e identifier)
{
	FaultInjectorEntry_s	*entry = NULL;
	bool					isCompleted = FALSE;
	bool					retval = FALSE;
	bool					isRemoved;
		
	LockAcquire();
		
	entry = FaultInjector_LookupHashEntry(identifier);
		
	if (entry == NULL) {
		retval = TRUE;
		isCompleted = TRUE;
		goto exit;
	}
		
	switch (entry->faultInjectorState) {
		case FaultInjectorStateWaiting:
			/* No operation */
			break;
		case FaultInjectorStateTriggered:	
			/* No operation */
			break;
		case FaultInjectorStateCompleted:
			
			retval = TRUE;
			/* NO break */
		case FaultInjectorStateFailed:
			
			isCompleted = TRUE;
			isRemoved = FaultInjector_RemoveHashEntry(identifier);
			
			if (isRemoved == FALSE) {
				ereport(DEBUG1,
						(errmsg("LOG(fault injector): could not remove fault injection from hash"
								"identifier:'%s' ",
								FaultInjectorIdentifierEnumToString[identifier])));
			} else {
				faultInjectorShmem->faultInjectorSlots--;
			}

			break;
		default:
			Assert(0);
	}

exit:
	LockRelease();						
	
	if ((isCompleted == TRUE) && (retval == FALSE)) {
		ereport(WARNING,
				(errmsg("could not complete fault injection, fault name:'%s' fault type:'%s' ",
						FaultInjectorIdentifierEnumToString[identifier],
						FaultInjectorTypeEnumToString[entry->faultInjectorType])));
	}
	return isCompleted;
}

/*
 *		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);
}

/*
 *		UnlockRelationOid
 *
 * Unlock, given only a relation Oid.  Use UnlockRelationId if you can.
 */
void
UnlockRelationOid(Oid relid, LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SetLocktagRelationOid(&tag, relid);

	LockRelease(&tag, lockmode, false);
}

/*
 *		UnlockRelationIdForSession
 */
void
UnlockRelationIdForSession(LockRelId *relid, LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SET_LOCKTAG_RELATION(tag, relid->dbId, relid->relId);

	LockRelease(&tag, lockmode, true);
}

/*
 *		SpeculativeInsertionLockRelease
 *
 * Delete the lock showing that the given transaction is speculatively
 * inserting a tuple.
 */
void
SpeculativeInsertionLockRelease(TransactionId xid)
{
	LOCKTAG		tag;

	SET_LOCKTAG_SPECULATIVE_INSERTION(tag, xid, speculativeInsertionToken);

	LockRelease(&tag, ExclusiveLock, false);
}

/* Releases the lock associated with the relay file fetching/DML task. */
void
UnlockShardResource(uint64 shardId, LOCKMODE lockmode)
{
	LOCKTAG tag;
	const bool sessionLock = false;

	SET_LOCKTAG_SHARD_RESOURCE(tag, MyDatabaseId, shardId);

	LockRelease(&tag, lockmode, sessionLock);
}

/* Releases the lock for resources associated with the given job id. */
void
UnlockJobResource(uint64 jobId, LOCKMODE lockmode)
{
	LOCKTAG tag;
	const bool sessionLock = false;

	SET_LOCKTAG_JOB_RESOURCE(tag, MyDatabaseId, jobId);

	LockRelease(&tag, lockmode, sessionLock);
}

/*
 *		VirtualXactLockTableDelete
 *
 * Release a Virtual Transaction lock. Only called by Startup process
 * at end of Hot Standby.
 */
void
VirtualXactLockTableDelete(VirtualTransactionId vxid)
{
	LOCKTAG		tag;

	Assert(VirtualTransactionIdIsValid(vxid));

	SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);

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

/*
 *		UnlockRelationForExtension
 */
void
UnlockRelationForExtension(Relation relation, LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SET_LOCKTAG_RELATION_EXTEND(tag,
								relation->rd_lockInfo.lockRelId.dbId,
								relation->rd_lockInfo.lockRelId.relId);

	LockRelease(&tag, lockmode, false);
}

void
UnlockRelationForResynchronize(RelFileNode *relFileNode, LOCKMODE lockmode)
{
	LOCKTAG		tag;

	SET_LOCKTAG_RELATION_RESYNCHRONIZE(tag,
						 relFileNode->dbNode,
						 relFileNode->relNode);

	LockRelease(&tag, lockmode, false);
}

/*
 * Separate routine for UnlockRelationForExtension() because resync workers do not have relation.
 */
void
UnlockRelationForResyncExtension(RelFileNode *relFileNode, LOCKMODE lockmode)
{
	LOCKTAG		tag;
	
	SET_LOCKTAG_RELATION_EXTEND(tag,
								relFileNode->dbNode,
								relFileNode->relNode);
	
	LockRelease(&tag, lockmode, false);
}

/*
 *		UnlockPage
 */
void
UnlockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode)
{
	LOCKTAG		tag;

	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);
}