*
* Example usage:
* @code
- * $dbw->begin(); // start of request
+ * $dbw->begin( __METHOD__ ); // start of request
* ... <execute some stuff> ...
* // Update the row in the DB
* $dbw->update( ... );
* $cache->delete( $key );
* } );
* ... <execute some stuff> ...
- * $dbw->commit(); // end of request
+ * $dbw->commit( __METHOD__ ); // end of request
* @endcode
*
* The $ttl parameter can be used when purging values that have not actually changed