Function SDW_lck_update

src/jrd/sdw.cpp:620–671

bool SDW_lck_update(thread_db* tdbb, SLONG sdw_update_flags)
{
/**************************************
 *
 *	 S D W _ l c k _ u p d a t e
 *
 **************************************
 *
 * Functional description
 *  update the Lock struct with the flag
 *  The update type flag indicates the type of corrective action
 *  to be taken by the ASTs of other procs attached to this DB.
 *
 *  A non zero sdw_update_flag is passed, it indicates error handling
 *  Two processes may encounter the Shadow array at the same time
 *  and both will want to perform corrective action. Only one should
 *  be allowed. For that,
 *		check if current data is zero, else return
 *  	write the pid into the lock data, read back to verify
 *      if pid is different, another process has updated behind you, so
 *		let him handle it and return
 *  	Update the data with sdw_update_flag passed to the function
 *
 **************************************/
	Database* dbb = GET_DBB();

	SyncLockGuard guard(&dbb->dbb_shadow_sync, SYNC_EXCLUSIVE, "SDW_lck_update");

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

	if (lock->lck_physical != LCK_SR)
	{
		// fb_assert (lock->lck_physical == LCK_none);
		return false;
	}

	if (!sdw_update_flags) {
		return !LCK_read_data(tdbb, lock);
	}

	if (LCK_read_data(tdbb, lock))
		return false;

	LCK_write_data(tdbb, lock, lock->lck_id);
	if (LCK_read_data(tdbb, lock) != lock->lck_id)
		return false;

	LCK_write_data(tdbb, lock, sdw_update_flags);
	return true;
}


void SDW_notify(thread_db* tdbb)