locking_method_default.inc

<?php
require_once SQ_CORE_PACKAGE_PATH.'/system/locking/locking_method/locking_method.inc';


class Locking_Method_Default extends Locking_Method
{


    public function __construct($assetid=0)
    {
        parent::__construct($assetid);

    }//end __construct()


    public static function acquireLock($lockid, $source_lockid='', $expires=0)
    {
        $current_lock = $GLOBALS['SQ_SYSTEM']->getLockInfo($lockid);

        // is this asset already locked
        if (!empty($current_lock)) {
            // the user is asking to acquire a lock they already had
            // so just update the lock expiry date
            if ($current_lock['userid'] == $GLOBALS['SQ_SYSTEM']->currentUserid()) {
                return self::updateLock($lockid, $expires);
            } else {
                $user = $GLOBALS['SQ_SYSTEM']->am->getAsset($current_lock['userid']);
                throw new Exception('Lock already held by "'.$user->name.'"');
            }
        }

        // if we have no source, we are the asset aquiring the locks
        if (empty($source_lockid)) $source_lockid = $lockid;

        if (!is_null($expires)) {
            $expires = (empty($expires)) ? (time() + SQ_CONF_LOCK_LENGTH) : (int) $expires;
            $expires = ts_iso8601($expires);
        }

        $GLOBALS['SQ_SYSTEM']->changeDatabaseConnection('db3');
        $GLOBALS['SQ_SYSTEM']->doTransaction('BEGIN');

        $sql = 'INSERT INTO sq_lock
                (lockid, source_lockid, userid, expires)
                VALUES
                (:lockid, :source_lockid, :userid, :expires)';

        try {
            $query = MatrixDAL::preparePdoQuery($sql);
            MatrixDAL::bindValueToPdo($query, 'lockid',        $lockid);
            MatrixDAL::bindValueToPdo($query, 'source_lockid', $source_lockid);
            MatrixDAL::bindValueToPdo($query, 'userid',        $GLOBALS['SQ_SYSTEM']->currentUserId());
            MatrixDAL::bindValueToPdo($query, 'expires',       $expires);
            MatrixDAL::execPdoQuery($query);
        } catch (Exception $e) {
            // Rather than throwing our own exception, keep the previous format
            // of returning an error message for now
            $GLOBALS['SQ_SYSTEM']->doTransaction('ROLLBACK');
            $GLOBALS['SQ_SYSTEM']->restoreDatabaseConnection();
            throw new Exception('DB error: '.$e->getMessage());
        }

        $GLOBALS['SQ_SYSTEM']->doTransaction('COMMIT');
        $GLOBALS['SQ_SYSTEM']->restoreDatabaseConnection();
        return TRUE;

    }//end acquireLock()


    public static function updateLock($lockid, $expires=0)
    {
        $current_lock = self::getLockInfo($lockid);

        // If there is no current lock (it may have expired), or if the lock
        // is indefinite, do nothing
        if (empty($current_lock) || empty($current_lock['expires'])) {
            return TRUE;
        }

        if (!is_null($expires)) {
            $expires = (!$expires) ? (time() + SQ_CONF_LOCK_LENGTH) : (int) $expires;
            $expires = ts_iso8601($expires);
        }

        $GLOBALS['SQ_SYSTEM']->changeDatabaseConnection('db3');
        $GLOBALS['SQ_SYSTEM']->doTransaction('BEGIN');

        $sql = 'UPDATE sq_lock
                   SET expires = :expires
                   WHERE source_lockid = :source_lockid';

        try {
            $query = MatrixDAL::preparePdoQuery($sql);
            MatrixDAL::bindValueToPdo($query, 'expires',       $expires);
            MatrixDAL::bindValueToPdo($query, 'source_lockid', $current_lock['source_lockid']);
            MatrixDAL::execPdoQuery($query);
        } catch (Exception $e) {
            // Rollback and then re-throw, let parent call handle the exception
            $GLOBALS['SQ_SYSTEM']->doTransaction('ROLLBACK');
            $GLOBALS['SQ_SYSTEM']->restoreDatabaseConnection();
            throw new Exception('DB error: '.$e->getMessage());
        }

        $GLOBALS['SQ_SYSTEM']->doTransaction('COMMIT');
        $GLOBALS['SQ_SYSTEM']->restoreDatabaseConnection();
        return TRUE;

    }//end acquireLock()


    public static function releaseLock($lockid)
    {
        $current_lock = self::getLockInfo($lockid, FALSE, FALSE);
        if (empty($current_lock)) return TRUE;

        $GLOBALS['SQ_SYSTEM']->changeDatabaseConnection('db3');
        $GLOBALS['SQ_SYSTEM']->doTransaction('BEGIN');

        $sql = 'DELETE FROM sq_lock
            WHERE source_lockid = :source_lockid';

        try {
            $query = MatrixDAL::preparePdoQuery($sql);
            MatrixDAL::bindValueToPdo($query, 'source_lockid', $current_lock['source_lockid']);
            $result = MatrixDAL::execPdoQuery($query);
        } catch (Exception $e) {
            // Rather than throwing our own exception, keep the previous format
            // of returning an error message for now
            $GLOBALS['SQ_SYSTEM']->doTransaction('ROLLBACK');
            $GLOBALS['SQ_SYSTEM']->restoreDatabaseConnection();
            throw new Exception('DB error: '.$e->getMessage());
        }

        $GLOBALS['SQ_SYSTEM']->doTransaction('COMMIT');

        $GLOBALS['SQ_SYSTEM']->restoreDatabaseConnection();
        return TRUE;

    }//end releaseLock()


    public static function getLockInfo($lockid, $full_chain=FALSE, $check_expires=TRUE, $allow_only_one=TRUE)
    {
        // Change to the "locks" connection
        $GLOBALS['SQ_SYSTEM']->changeDatabaseConnection('db3');

        // Did I get a string or an array?
        $where = '';
        $locks_passed = Array();
        if (is_array($lockid)) {
            $where = ' WHERE lockid IN (';
            foreach ($lockid as $lock_key => $lock_value) {
                $where .= ':lockid'.$lock_key.',';
                $locks_passed['lockid'.$lock_key] = $lock_value;
            }
            $where = rtrim($where, ',');
            $where .= ')';
        } else {
            $where = ' WHERE lockid = :lockid';
            $locks_passed['lockid'] = $lockid;
        }
        
        $sql = 'SELECT lockid, source_lockid, userid, expires
                FROM sq_lock'.$where;

        try {
            $query = MatrixDAL::preparePdoQuery($sql);
            foreach($locks_passed as $bind_var => $bind_val) {
                MatrixDAL::bindValueToPdo($query, $bind_var, $bind_val);
            }
            $results = MatrixDAL::executePdoAssoc($query);
        } catch (Exception $e) {
            $lock_error = (is_array($lockid)) ? ('s '.implode(', ', $lockid)) : (' '.$lockid);
            throw new Exception('Unable to get lock information for lock ID"'.$lock_error.'" due to database error: '.$e->getMessage());
        }
        
        if (!empty($results)) {
            foreach ($results as $result_key => $result) {
                $results[$result_key]['expires'] = empty($result['expires']) ? NULL : iso8601_ts($result['expires']);
                if ($check_expires && !empty($result['expires'])) {
                    if ($results[$result_key]['expires'] < time()) {
                        self::releaseLock($lockid);
                        // this lock has expired
                        if (count($results) > 1) {
                            // More locks to check
                            unset($results[$result_key]);
                            continue;
                        } else {
                            // All done fin
                            $results = Array();
                            break;
                        }//end if
                    }//end if
                }//end if

                if ($full_chain) {
                    $results[$result_key]['chained_assets'] = Array();
                    foreach ($locks_passed as $lock_to_test) {
                        $sql = 'SELECT lockid, source_lockid, userid, expires
                                FROM sq_lock
                                WHERE source_lockid = :source_lockid
                                    AND lockid <> :lockid';

                        try {
                            $query = MatrixDAL::preparePdoQuery($sql);
                            MatrixDAL::bindValueToPdo($query, 'source_lockid', $result['source_lockid']);
                            MatrixDAL::bindValueToPdo($query, 'lockid', $lock_to_test);
                            $chain = MatrixDAL::executePdoAssoc($query);
                        } catch (Exception $e) {
                            throw new Exception('Unable to get lock chain information for source lock ID "'.$result['source_lockid'].'" due to database error: '.$e->getMessage());
                        }

                        foreach ($chain as $lock_row) {
                            $lock_row['expires'] = (empty($lock_row['expires'])) ? NULL : iso8601_ts($lock_row['expires']);
                            $results[$result_key]['chained_assets'][$lock_row['lockid']] = $lock_row;
                        }
                    }//end foreach
                }//end if
            }//end foreach
        }//end if
        if (!empty($results) && $allow_only_one) {
                $results = $results[0];
        }

        $GLOBALS['SQ_SYSTEM']->restoreDatabaseConnection();
        return $results;

    }//end getLockInfo()


    public static function getActiveLocks($owner_assetid=NULL, $include_expired=FALSE)
    {
        try {
            $bind_vars = Array();

            if ($include_expired === FALSE) {
                $bind_vars['expire_time'] = ts_iso8601(time());
            } else {
                $bind_vars['expire_time'] = NULL;
            }

            if ($owner_assetid !== NULL) {
                $bind_vars['owner_assetid'] = $owner_assetid;
            } else {
                $bind_vars['owner_assetid'] = NULL;
            }

            $db_locks = MatrixDAL::executeAll('core', 'getActiveLocks', $bind_vars);

        } catch (Exception $e) {
            throw $e;

        }//end try catch

        return $db_locks;

    }//end getActiveLocks()


    public static function supportsGetActiveLocks()
    {
        return TRUE;

    }//end supportsGetActiveLocks()


    public static function changeLockOwner($old_assetid, $new_assetid)
    {
        $bind_vars = Array(
                    'old_userid'    => $old_assetid,
                    'new_userid'    => $new_assetid,
                 );
        MatrixDAL::executeQuery('core', 'changeAllLocksHeldUser', $bind_vars);
        return TRUE;

    }//end changeLockOwner()


    public static function supportsChangeLockOwner()
    {
        return TRUE;

    }//end supportsChangeLockOwner()


    public static function supportsDeletingExpiredLocks()
    {
        return TRUE;

    }//end supportsDeletingExpiredLocks()


    public static function deleteExpiredLocks()
    {
        $bind_vars['expire_time'] = ts_iso8601(time());

        MatrixDAL::executeQuery('core', 'deleteExpiredLocks', $bind_vars);
        return TRUE;
    }
}//end class

?>