Function CCH_exclusive

src/jrd/cch.cpp:469–530

bool CCH_exclusive(thread_db* tdbb, USHORT level, SSHORT wait_flag, Firebird::Sync* guard)
{
/**************************************
 *
 *	C C H _ e x c l u s i v e
 *
 **************************************
 *
 * Functional description
 *	Get exclusive access to a database.  If we get it, return true.
 *	If the wait flag is FALSE, and we can't get it, give up and
 *	return false. There are two levels of database exclusivity: LCK_PW
 *	guarantees there are no normal users in the database while LCK_EX
 *	additionally guarantees background database processes like the
 *	shared cache manager have detached.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();

	if (dbb->dbb_flags & DBB_shared)
	{
		if (!CCH_exclusive_attachment(tdbb, level, wait_flag, guard))
			return false;
	}

	Lock* lock = dbb->dbb_lock;
	if (!lock)
		return false;

	dbb->dbb_flags |= DBB_exclusive;

	switch (level)
	{
	case LCK_PW:
		if (lock->lck_physical >= LCK_PW || LCK_convert(tdbb, lock, LCK_PW, wait_flag))
			return true;
		break;

	case LCK_EX:
		if (lock->lck_physical == LCK_EX || LCK_convert(tdbb, lock, LCK_EX, wait_flag))
			return true;
		break;

	default:
		break;
	}

	// Clear the status vector, as our callers check the return value
	// and throw custom exceptions themselves
	fb_utils::init_status(tdbb->tdbb_status_vector);

	// If we are supposed to wait (presumably patiently),
	// but can't get the lock, generate an error

	if (wait_flag == LCK_WAIT)
		ERR_post(Arg::Gds(isc_deadlock));