263 lines
9.6 KiB
PHP
263 lines
9.6 KiB
PHP
<?php
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/*
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* $Id$
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* This software consists of voluntary contributions made by many individuals
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* and is licensed under the LGPL. For more information, see
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* <http://www.phpdoctrine.com>.
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*/
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/**
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* Class for handling the pessimistic offline locking of {@link Doctrine_Record}s.
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* Offline locking of records comes in handy where you need to make sure that
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* a time-consuming task on a record or many records, which is spread over several
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* page requests can't be interfered by other users.
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*
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* @author Roman Borschel <roman@code-factory.org>
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* @license LGPL
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* @since 1.0
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*/
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class Doctrine_Locking_Manager_Pessimistic
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{
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/**
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* The datasource that is used by the locking manager
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*
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* @var Doctrine_Connection object
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*/
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private $_dataSource;
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/**
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* The database table name for the lock tracking
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*/
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private $_lockTable = 'doctrine_lock_tracking';
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/**
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* Constructs a new locking manager object
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*
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* When the CREATE_TABLES attribute of the connection on which the manager
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* is supposed to work on is set to true, the locking table is created.
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*
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* @param Doctrine_Connection $dataSource The database connection to use
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*/
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public function __construct(Doctrine_Connection $dataSource)
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{
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$this->_dataSource = $dataSource;
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if($this->_dataSource->getAttribute(Doctrine::ATTR_CREATE_TABLES) === true)
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{
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$columns = array();
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$columns['object_type'] = array('string', 50, array('notnull' => true, 'primary'));
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$columns['object_key'] = array('string', 250, array('notnull' => true, 'primary'));
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$columns['user_ident'] = array('string', 50, array('notnull' => true));
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$columns['timestamp_obtained'] = array('integer', 10, array('notnull' => true));
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$dataDict = new Doctrine_DataDict($this->_dataSource->getDBH());
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$dataDict->createTable($this->_lockTable, $columns);
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}
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}
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/**
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* Obtains a lock on a {@link Doctrine_Record}
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*
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* @param Doctrine_Record $record The record that has to be locked
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* @param mixed $userIdent A unique identifier of the locking user
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* @return boolean TRUE if the locking was successful, FALSE if another user
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* holds a lock on this record
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* @throws Doctrine_Locking_Exception If the locking failed due to database errors
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*/
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public function getLock(Doctrine_Record $record, $userIdent)
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{
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$objectType = $record->getTable()->getComponentName();
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$key = $record->getID();
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$gotLock = false;
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if(is_array($key))
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{
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// Composite key
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$key = implode('|', $key);
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}
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try
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{
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$dbh = $this->_dataSource->getDBH();
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$dbh->beginTransaction();
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$stmt = $dbh->prepare("INSERT INTO $this->_lockTable
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(object_type, object_key, user_ident, timestamp_obtained)
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VALUES (:object_type, :object_key, :user_ident, :ts_obtained)");
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$stmt->bindParam(':object_type', $objectType);
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$stmt->bindParam(':object_key', $key);
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$stmt->bindParam(':user_ident', $userIdent);
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$stmt->bindParam(':ts_obtained', time());
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try {
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$stmt->execute();
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$gotLock = true;
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// we catch an Exception here instead of PDOException since we might also be catching Doctrine_Exception
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} catch(Exception $pkviolation) {
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// PK violation occured => existing lock!
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}
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if(!$gotLock)
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{
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$lockingUserIdent = $this->_getLockingUserIdent($objectType, $key);
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if($lockingUserIdent !== null && $lockingUserIdent == $userIdent)
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{
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$gotLock = true; // The requesting user already has a lock
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// Update timestamp
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$stmt = $dbh->prepare("UPDATE $this->_lockTable SET timestamp_obtained = :ts
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WHERE object_type = :object_type AND
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object_key = :object_key AND
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user_ident = :user_ident");
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$stmt->bindParam(':ts', time());
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$stmt->bindParam(':object_type', $objectType);
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$stmt->bindParam(':object_key', $key);
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$stmt->bindParam(':user_ident', $lockingUserIdent);
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$stmt->execute();
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}
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}
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$dbh->commit();
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}
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catch(Exception $pdoe)
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{
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$dbh->rollback();
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throw new Doctrine_Locking_Exception($pdoe->getMessage());
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}
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return $gotLock;
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}
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/**
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* Releases a lock on a {@link Doctrine_Record}
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*
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* @param Doctrine_Record $record The record for which the lock has to be released
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* @param mixed $userIdent The unique identifier of the locking user
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* @return boolean TRUE if a lock was released, FALSE if no lock was released
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* @throws Doctrine_Locking_Exception If the release procedure failed due to database errors
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*/
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public function releaseLock(Doctrine_Record $record, $userIdent)
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{
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$objectType = $record->getTable()->getComponentName();
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$key = $record->getID();
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if(is_array($key))
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{
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// Composite key
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$key = implode('|', $key);
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}
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try
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{
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$dbh = $this->_dataSource->getDBH();
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$stmt = $dbh->prepare("DELETE FROM $this->_lockTable WHERE
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object_type = :object_type AND
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object_key = :object_key AND
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user_ident = :user_ident");
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$stmt->bindParam(':object_type', $objectType);
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$stmt->bindParam(':object_key', $key);
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$stmt->bindParam(':user_ident', $userIdent);
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$stmt->execute();
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$count = $stmt->rowCount();
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return ($count > 0);
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}
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catch(PDOException $pdoe)
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{
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throw new Doctrine_Locking_Exception($pdoe->getMessage());
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}
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}
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/**
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* Gets the unique user identifier of a lock
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*
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* @param string $objectType The type of the object (component name)
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* @param mixed $key The unique key of the object
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* @return mixed The unique user identifier for the specified lock
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* @throws Doctrine_Locking_Exception If the query failed due to database errors
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*/
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private function _getLockingUserIdent($objectType, $key)
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{
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if(is_array($key))
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{
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// Composite key
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$key = implode('|', $key);
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}
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try
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{
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$dbh = $this->_dataSource->getDBH();
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$stmt = $dbh->prepare("SELECT user_ident
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FROM $this->_lockTable
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WHERE object_type = :object_type AND object_key = :object_key");
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$stmt->bindParam(':object_type', $objectType);
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$stmt->bindParam(':object_key', $key);
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$success = $stmt->execute();
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if(!$success)
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{
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throw new Doctrine_Locking_Exception("Failed to determine locking user");
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}
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$user_ident = $stmt->fetchColumn();
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}
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catch(PDOException $pdoe)
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{
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throw new Doctrine_Locking_Exception($pdoe->getMessage());
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}
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return $user_ident;
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}
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/**
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* Releases locks older than a defined amount of seconds
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*
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* When called without parameters all locks older than 15 minutes are released.
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*
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* @param integer $age The maximum valid age of locks in seconds
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* @return integer The number of locks that have been released
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* @throws Doctrine_Locking_Exception If the release process failed due to database errors
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*/
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public function releaseAgedLocks($age = 900)
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{
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$age = time() - $age;
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try
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{
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$dbh = $this->_dataSource->getDBH();
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$stmt = $dbh->prepare("DELETE FROM $this->_lockTable WHERE timestamp_obtained < :age");
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$stmt->bindParam(':age', $age);
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$stmt->execute();
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$count = $stmt->rowCount();
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return $count;
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}
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catch(PDOException $pdoe)
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{
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throw new Doctrine_Locking_Exception($pdoe->getMessage());
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}
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}
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}
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