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<?php
/*
* $Id: Pessimistic.php 6484 2009-10-12 17:40:41Z jwage $
*
* 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.org>.
*/
/**
* 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.
*
* @package Doctrine
* @subpackage Locking
* @link www.phpdoctrine.org
* @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
* @version $Revision: 6484 $
*/
class Doctrine_Locking_Manager_Pessimistic
{
/**
* The conn that is used by the locking manager
*
* @var Doctrine_Connection object
*/
private $conn;
/**
* 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 $conn The database connection to use
*/
public function __construct(Doctrine_Connection $conn)
{
$this->conn = $conn;
if ($this->conn->getAttribute(Doctrine_Core::ATTR_EXPORT) & Doctrine_Core::EXPORT_TABLES) {
$columns = array();
$columns['object_type'] = array('type' => 'string',
'length' => 50,
'notnull' => true,
'primary' => true);
$columns['object_key'] = array('type' => 'string',
'length' => 250,
'notnull' => true,
'primary' => true);
$columns['user_ident'] = array('type' => 'string',
'length' => 50,
'notnull' => true);
$columns['timestamp_obtained'] = array('type' => 'integer',
'length' => 10,
'notnull' => true);
$options = array('primary' => array('object_type', 'object_key'));
try {
$this->conn->export->createTable($this->_lockTable, $columns, $options);
} catch(Exception $e) {
}
}
}
/**
* 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->getTable()->getIdentifier();
$gotLock = false;
$time = time();
if (is_array($key)) {
// Composite key
$key = implode('|', $key);
}
try {
$dbh = $this->conn->getDbh();
$this->conn->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();
}
}
$this->conn->commit();
} catch (Exception $pdoe) {
$this->conn->rollback();
throw new Doctrine_Locking_Exception($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 = $record->getTable()->getIdentifier();
if (is_array($key)) {
// Composite key
$key = implode('|', $key);
}
try {
$dbh = $this->conn->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 $key The unique key of the object. Can be string or array
* @return string The unique user identifier for the specified lock
* @throws Doctrine_Locking_Exception If the query failed due to database errors
*/
private function _getLockingUserIdent($objectType, $key)
{
if (is_array($key)) {
// Composite key
$key = implode('|', $key);
}
try {
$dbh = $this->conn->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->getTable()->getIdentifier();
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->conn->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());
}
}
}
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