Subversion-Projekte lars-tiefland.php_share

<?php

/*

 *  $Id: Pessimistic.php 7490 2010-03-29 19:53:27Z 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.doctrine-project.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.doctrine-project.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: 7490 $

 */

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());

        }

    }

}