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