xact.c

PostgreSQL7.4.6 for Linux

				(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
		/* translator: %s represents an SQL statement name */
				 errmsg("%s cannot run inside a transaction block",
						stmtType)));

	/*
	 * Are we inside a function call?  If the statement's parameter block
	 * was allocated in QueryContext, assume it is an interactive command.
	 * Otherwise assume it is coming from a function.
	 */
	if (!MemoryContextContains(QueryContext, stmtNode))
		ereport(ERROR,
				(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
		/* translator: %s represents an SQL statement name */
			 errmsg("%s cannot be executed from a function", stmtType)));
	/* If we got past IsTransactionBlock test, should be in default state */
	if (CurrentTransactionState->blockState != TBLOCK_DEFAULT)
		elog(ERROR, "cannot prevent transaction chain");
	/* all okay */
}

/*
 *	RequireTransactionChain
 *
 *	This routine is to be called by statements that must run inside
 *	a transaction block, because they have no effects that persist past
 *	transaction end (and so calling them outside a transaction block
 *	is presumably an error).  DECLARE CURSOR is an example.
 *
 *	If we appear to be running inside a user-defined function, we do not
 *	issue an error, since the function could issue more commands that make
 *	use of the current statement's results.  Thus this is an inverse for
 *	PreventTransactionChain.
 *
 *	stmtNode: pointer to parameter block for statement; this is used in
 *	a very klugy way to determine whether we are inside a function.
 *	stmtType: statement type name for error messages.
 */
void
RequireTransactionChain(void *stmtNode, const char *stmtType)
{
	/*
	 * xact block already started?
	 */
	if (IsTransactionBlock())
		return;

	/*
	 * Are we inside a function call?  If the statement's parameter block
	 * was allocated in QueryContext, assume it is an interactive command.
	 * Otherwise assume it is coming from a function.
	 */
	if (!MemoryContextContains(QueryContext, stmtNode))
		return;
	ereport(ERROR,
			(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
	/* translator: %s represents an SQL statement name */
			 errmsg("%s may only be used in transaction blocks",
					stmtType)));
}


/*
 * Register or deregister callback functions for end-of-xact cleanup
 *
 * These functions are intended for use by dynamically loaded modules.
 * For built-in modules we generally just hardwire the appropriate calls
 * (mainly because it's easier to control the order that way, where needed).
 *
 * Note that the callback occurs post-commit or post-abort, so the callback
 * functions can only do noncritical cleanup.
 */
void
RegisterEOXactCallback(EOXactCallback callback, void *arg)
{
	EOXactCallbackItem *item;

	item = (EOXactCallbackItem *)
		MemoryContextAlloc(TopMemoryContext, sizeof(EOXactCallbackItem));
	item->callback = callback;
	item->arg = arg;
	item->next = EOXact_callbacks;
	EOXact_callbacks = item;
}

void
UnregisterEOXactCallback(EOXactCallback callback, void *arg)
{
	EOXactCallbackItem *item;
	EOXactCallbackItem *prev;

	prev = NULL;
	for (item = EOXact_callbacks; item; prev = item, item = item->next)
	{
		if (item->callback == callback && item->arg == arg)
		{
			if (prev)
				prev->next = item->next;
			else
				EOXact_callbacks = item->next;
			pfree(item);
			break;
		}
	}
}

static void
CallEOXactCallbacks(bool isCommit)
{
	EOXactCallbackItem *item;

	for (item = EOXact_callbacks; item; item = item->next)
	{
		(*item->callback) (isCommit, item->arg);
	}
}


/* ----------------------------------------------------------------
 *					   transaction block support
 * ----------------------------------------------------------------
 */
/*
 *	BeginTransactionBlock
 */
void
BeginTransactionBlock(void)
{
	TransactionState s = CurrentTransactionState;

	/*
	 * check the current transaction state
	 */
	if (s->blockState != TBLOCK_DEFAULT)
		ereport(WARNING,
				(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
				 errmsg("there is already a transaction in progress")));

	/*
	 * set the current transaction block state information appropriately
	 * during begin processing
	 */
	s->blockState = TBLOCK_BEGIN;

	/*
	 * do begin processing here.  Nothing to do at present.
	 */

	/*
	 * done with begin processing, set block state to inprogress
	 */
	s->blockState = TBLOCK_INPROGRESS;
}

/*
 *	EndTransactionBlock
 */
void
EndTransactionBlock(void)
{
	TransactionState s = CurrentTransactionState;

	/*
	 * check the current transaction state
	 */
	if (s->blockState == TBLOCK_INPROGRESS)
	{
		/*
		 * here we are in a transaction block which should commit when we
		 * get to the upcoming CommitTransactionCommand() so we set the
		 * state to "END".	CommitTransactionCommand() will recognize this
		 * and commit the transaction and return us to the default state
		 */
		s->blockState = TBLOCK_END;
		return;
	}

	if (s->blockState == TBLOCK_ABORT)
	{
		/*
		 * here, we are in a transaction block which aborted and since the
		 * AbortTransaction() was already done, we do whatever is needed
		 * and change to the special "END ABORT" state.  The upcoming
		 * CommitTransactionCommand() will recognise this and then put us
		 * back in the default state.
		 */
		s->blockState = TBLOCK_ENDABORT;
		return;
	}

	/*
	 * here, the user issued COMMIT when not inside a transaction. Issue a
	 * WARNING and go to abort state.  The upcoming call to
	 * CommitTransactionCommand() will then put us back into the default
	 * state.
	 */
	ereport(WARNING,
			(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
			 errmsg("there is no transaction in progress")));
	AbortTransaction();
	s->blockState = TBLOCK_ENDABORT;
}

/*
 *	AbortTransactionBlock
 */
#ifdef NOT_USED
static void
AbortTransactionBlock(void)
{
	TransactionState s = CurrentTransactionState;

	/*
	 * check the current transaction state
	 */
	if (s->blockState == TBLOCK_INPROGRESS)
	{
		/*
		 * here we were inside a transaction block something screwed up
		 * inside the system so we enter the abort state, do the abort
		 * processing and then return. We remain in the abort state until
		 * we see an END TRANSACTION command.
		 */
		s->blockState = TBLOCK_ABORT;
		AbortTransaction();
		return;
	}

	/*
	 * here, the user issued ABORT when not inside a transaction. Issue a
	 * WARNING and go to abort state.  The upcoming call to
	 * CommitTransactionCommand() will then put us back into the default
	 * state.
	 */
	ereport(WARNING,
			(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
			 errmsg("there is no transaction in progress")));
	AbortTransaction();
	s->blockState = TBLOCK_ENDABORT;
}
#endif

/*
 *	UserAbortTransactionBlock
 */
void
UserAbortTransactionBlock(void)
{
	TransactionState s = CurrentTransactionState;

	/*
	 * if the transaction has already been automatically aborted with an
	 * error, and the user subsequently types 'abort', allow it.  (the
	 * behavior is the same as if they had typed 'end'.)
	 */
	if (s->blockState == TBLOCK_ABORT)
	{
		s->blockState = TBLOCK_ENDABORT;
		return;
	}

	if (s->blockState == TBLOCK_INPROGRESS)
	{
		/*
		 * here we were inside a transaction block and we got an abort
		 * command from the user, so we move to the abort state, do the
		 * abort processing and then change to the ENDABORT state so we
		 * will end up in the default state after the upcoming
		 * CommitTransactionCommand().
		 */
		s->blockState = TBLOCK_ABORT;
		AbortTransaction();
		s->blockState = TBLOCK_ENDABORT;
		return;
	}

	/*
	 * here, the user issued ABORT when not inside a transaction. Issue a
	 * WARNING and go to abort state.  The upcoming call to
	 * CommitTransactionCommand() will then put us back into the default
	 * state.
	 */
	ereport(WARNING,
			(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
			 errmsg("there is no transaction in progress")));
	AbortTransaction();
	s->blockState = TBLOCK_ENDABORT;
}

/*
 *	AbortOutOfAnyTransaction
 *
 *	This routine is provided for error recovery purposes.  It aborts any
 *	active transaction or transaction block, leaving the system in a known
 *	idle state.
 */
void
AbortOutOfAnyTransaction(void)
{
	TransactionState s = CurrentTransactionState;

	/*
	 * Get out of any low-level transaction
	 */
	switch (s->state)
	{
		case TRANS_START:
		case TRANS_INPROGRESS:
		case TRANS_COMMIT:
			/* In a transaction, so clean up */
			AbortTransaction();
			CleanupTransaction();
			break;
		case TRANS_ABORT:
			/* AbortTransaction already done, still need Cleanup */
			CleanupTransaction();
			break;
		case TRANS_DEFAULT:
			/* Not in a transaction, do nothing */
			break;
	}

	/*
	 * Now reset the high-level state
	 */
	s->blockState = TBLOCK_DEFAULT;
}

/*
 * IsTransactionBlock --- are we within a transaction block?
 */
bool
IsTransactionBlock(void)
{
	TransactionState s = CurrentTransactionState;

	if (s->blockState == TBLOCK_DEFAULT)
		return false;

	return true;
}

/*
 * IsTransactionOrTransactionBlock --- are we within either a transaction
 * or a transaction block?  (The backend is only really "idle" when this
 * returns false.)
 *
 * This should match up with IsTransactionBlock and IsTransactionState.
 */
bool
IsTransactionOrTransactionBlock(void)
{
	TransactionState s = CurrentTransactionState;

	if (s->blockState == TBLOCK_DEFAULT && s->state == TRANS_DEFAULT)
		return false;

	return true;
}

/*
 * TransactionBlockStatusCode - return status code to send in ReadyForQuery
 */
char
TransactionBlockStatusCode(void)
{
	TransactionState s = CurrentTransactionState;

	switch (s->blockState)
	{
		case TBLOCK_DEFAULT:
			return 'I';			/* idle --- not in transaction */
		case TBLOCK_BEGIN:
		case TBLOCK_INPROGRESS:
		case TBLOCK_END:
			return 'T';			/* in transaction */
		case TBLOCK_ABORT:
		case TBLOCK_ENDABORT:
			return 'E';			/* in failed transaction */
	}

	/* should never get here */
	elog(ERROR, "invalid transaction block state: %d",
		 (int) s->blockState);
	return 0;					/* keep compiler quiet */
}


/*
 *	XLOG support routines
 */

void
xact_redo(XLogRecPtr lsn, XLogRecord *record)
{
	uint8		info = record->xl_info & ~XLR_INFO_MASK;

	if (info == XLOG_XACT_COMMIT)
	{
		TransactionIdCommit(record->xl_xid);
		/* SHOULD REMOVE FILES OF ALL DROPPED RELATIONS */
	}
	else if (info == XLOG_XACT_ABORT)
	{
		TransactionIdAbort(record->xl_xid);
		/* SHOULD REMOVE FILES OF ALL FAILED-TO-BE-CREATED RELATIONS */
	}
	else
		elog(PANIC, "xact_redo: unknown op code %u", info);
}

void
xact_undo(XLogRecPtr lsn, XLogRecord *record)
{
	uint8		info = record->xl_info & ~XLR_INFO_MASK;

	if (info == XLOG_XACT_COMMIT)		/* shouldn't be called by XLOG */
		elog(PANIC, "xact_undo: can't undo committed xaction");
	else if (info != XLOG_XACT_ABORT)
		elog(PANIC, "xact_redo: unknown op code %u", info);
}

void
xact_desc(char *buf, uint8 xl_info, char *rec)
{
	uint8		info = xl_info & ~XLR_INFO_MASK;

	if (info == XLOG_XACT_COMMIT)
	{
		xl_xact_commit *xlrec = (xl_xact_commit *) rec;
		struct tm  *tm = localtime(&xlrec->xtime);

		sprintf(buf + strlen(buf), "commit: %04u-%02u-%02u %02u:%02u:%02u",
				tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
				tm->tm_hour, tm->tm_min, tm->tm_sec);
	}
	else if (info == XLOG_XACT_ABORT)
	{
		xl_xact_abort *xlrec = (xl_xact_abort *) rec;
		struct tm  *tm = localtime(&xlrec->xtime);

		sprintf(buf + strlen(buf), "abort: %04u-%02u-%02u %02u:%02u:%02u",
				tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
				tm->tm_hour, tm->tm_min, tm->tm_sec);
	}
	else
		strcat(buf, "UNKNOWN");
}

void
			XactPushRollback(void (*func) (void *), void *data)
{
#ifdef XLOG_II
	if (_RollbackFunc != NULL)
		elog(PANIC, "XactPushRollback: already installed");
#endif

	_RollbackFunc = func;
	_RollbackData = data;
}

void
XactPopRollback(void)
{
	_RollbackFunc = NULL;
}