Index: t3lib/stddb/tables.sql
===================================================================
--- t3lib/stddb/tables.sql	(Revision 8246)
+++ t3lib/stddb/tables.sql	(Arbeitskopie)
@@ -413,6 +413,15 @@
 ) ENGINE=InnoDB;
 
 #
+# Table structure for table 'sys_lock'
+#
+CREATE TABLE sys_lock (
+  id varchar(64) DEFAULT '' NOT NULL,
+  expires int(11) unsigned DEFAULT '0' NOT NULL,
+  PRIMARY KEY (id)
+) ENGINE=InnoDB;
+
+#
 # Table structure for table 'sys_language'
 #
 CREATE TABLE sys_language (
Index: t3lib/class.t3lib_lock.php
===================================================================
--- t3lib/class.t3lib_lock.php	(Revision 8246)
+++ t3lib/class.t3lib_lock.php	(Arbeitskopie)
@@ -59,6 +59,12 @@
  * @see	class.t3lib_tstemplate.php, class.tslib_fe.php
  */
 class t3lib_lock {
+	const METHOD_SIMPLE = 'simple';
+	const METHOD_FLOCK = 'flock';
+	const METHOD_SEMAPHORE = 'semaphore';
+	const METHOD_DATABASE = 'database';
+	const METHOD_DISABLE = 'disable';
+
 	protected $method;
 	protected $id;		// Identifier used for this lock
 	protected $resource;	// Resource used for this lock (can be a file or a semaphore resource)
@@ -67,6 +73,7 @@
 
 	protected $loops = 150;	// Number of times a locked resource is tried to be acquired. This is only used by manual locks like the "simple" method.
 	protected $step = 200;	// Milliseconds after lock acquire is retried. $loops * $step results in the maximum delay of a lock. Only used by manual locks like the "simple" method.
+	protected $expiration = 300;	// Number of seconds after a resource shall expire
 
 
 
@@ -94,7 +101,7 @@
 		}
 
 			// Detect locking method
-		if (in_array($method, array('disable', 'simple', 'flock', 'semaphore'))) {
+		if (in_array($method, array('disable', 'simple', 'flock', 'semaphore', 'database'))) {
 			$this->method = $method;
 		} else {
 			throw new Exception('No such method "' . $method . '"');
@@ -118,6 +125,11 @@
 					$success = TRUE;
 				}
 			break;
+			case 'database':
+				$this->id = sha1($id);
+				$this->resource = $GLOBALS['TYPO3_DB']->fullQuoteStr($this->id, 'sys_lock');
+				$success = TRUE;
+				break;
 			case 'disable':
 				return FALSE;
 			break;
@@ -150,6 +162,7 @@
 		switch ($this->method) {
 			case 'simple':
 				if (is_file($this->resource)) {
+					$noWait = FALSE;
 					$this->sysLog('Waiting for a different process to release the lock');
 					$i = 0;
 					while ($i<$this->loops) {
@@ -158,7 +171,6 @@
 						clearstatcache();
 						if (!is_file($this->resource)) {	// Lock became free, leave the loop
 							$this->sysLog('Different process released the lock');
-							$noWait = FALSE;
 							break;
 						}
 					}
@@ -189,6 +201,32 @@
 					$noWait = FALSE;
 				}
 			break;
+			case 'database':
+				$GLOBALS['TYPO3_DB']->exec_DELETEquery('sys_lock', 'expires<' . $GLOBALS['EXEC_TIME']);
+				$noWait = FALSE;
+
+				while ($i < $this->loops) {
+					if ($this->isDatabaseLockActive()) {
+						$i++;
+						usleep($this->step * 1000);
+					} else {
+						$noWait = TRUE;
+						break;
+					}
+				}
+
+				$fields = array(
+					'expires' => $GLOBALS['EXEC_TIME'] + $this->expiration,
+					'id' => $this->id,
+				);
+
+				if ($noWait || !$this->isDatabaseLockActive()) {
+					$GLOBALS['TYPO3_DB']->exec_INSERTquery('sys_lock', $fields);
+				} else {
+					$GLOBALS['TYPO3_DB']->exec_UPDATEquery('sys_lock', 'id=' . $this->resource, $fields);
+				}
+
+				break;
 			case 'disable':
 				$noWait = FALSE;
 				$isAcquired = FALSE;
@@ -230,6 +268,9 @@
 					$success = FALSE;
 				}
 			break;
+			case 'database':
+				$GLOBALS['TYPO3_DB']->exec_DELETEquery('sys_lock', 'id=' . $this->resource);
+				$success = ($GLOBALS['TYPO3_DB']->sql_affected_rows() > 0);
 			case 'disable':
 				$success = FALSE;
 			break;
@@ -287,6 +328,15 @@
 	public function sysLog($message, $severity=0) {
 		t3lib_div::sysLog('Locking [' . $this->method . '::' . $this->id.']: ' . trim($message), 'cms', $severity);
 	}
+
+	/**
+	 * Determines whether a database lock is active.
+	 *
+	 * @return boolean
+	 */
+	protected function isDatabaseLockActive() {
+		return ($GLOBALS['TYPO3_DB']->exec_SELECTcountRows('id', 'sys_lock', 'id=' . $this->resource) != 0);
+	}
 }