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<?php
/**
* @author Robin Appelman <icewind@owncloud.com>
*
* @copyright Copyright (c) 2015, ownCloud, Inc.
* @license AGPL-3.0
*
* This code is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License, version 3,
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
*/
namespace OC\Lock;
use OCP\IDBConnection;
use OCP\Lock\LockedException;
/**
* Locking provider that stores the locks in the database
*/
class DBLockingProvider extends AbstractLockingProvider {
/**
* @var \OCP\IDBConnection
*/
private $connection;
/**
* @param \OCP\IDBConnection $connection
*/
public function __construct(IDBConnection $connection) {
$this->connection = $connection;
}
protected function initLockField($path) {
$this->connection->insertIfNotExist('*PREFIX*file_locks', ['key' => $path, 'lock' => 0, 'ttl' => 0], ['key']);
}
/**
* @param string $path
* @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
* @return bool
*/
public function isLocked($path, $type) {
$query = $this->connection->prepare('SELECT `lock` from `*PREFIX*file_locks` WHERE `key` = ?');
$query->execute([$path]);
$lockValue = (int)$query->fetchColumn();
if ($type === self::LOCK_SHARED) {
return $lockValue > 0;
} else if ($type === self::LOCK_EXCLUSIVE) {
return $lockValue === -1;
} else {
return false;
}
}
/**
* @param string $path
* @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
* @throws \OCP\Lock\LockedException
*/
public function acquireLock($path, $type) {
$this->connection->beginTransaction();
$this->initLockField($path);
if ($type === self::LOCK_SHARED) {
$result = $this->connection->executeUpdate(
'UPDATE `*PREFIX*file_locks` SET `lock` = `lock` + 1 WHERE `key` = ? AND `lock` >= 0',
[$path]
);
} else {
$result = $this->connection->executeUpdate(
'UPDATE `*PREFIX*file_locks` SET `lock` = -1 WHERE `key` = ? AND `lock` = 0',
[$path]
);
}
$this->connection->commit();
if ($result !== 1) {
throw new LockedException($path);
}
$this->markAcquire($path, $type);
}
/**
* @param string $path
* @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
*/
public function releaseLock($path, $type) {
$this->initLockField($path);
if ($type === self::LOCK_SHARED) {
$this->connection->executeUpdate(
'UPDATE `*PREFIX*file_locks` SET `lock` = `lock` - 1 WHERE `key` = ? AND `lock` > 0',
[$path]
);
} else {
$this->connection->executeUpdate(
'UPDATE `*PREFIX*file_locks` SET `lock` = 0 WHERE `key` = ? AND `lock` = -1',
[$path]
);
}
$this->markRelease($path, $type);
}
/**
* Change the type of an existing lock
*
* @param string $path
* @param int $targetType self::LOCK_SHARED or self::LOCK_EXCLUSIVE
* @throws \OCP\Lock\LockedException
*/
public function changeLock($path, $targetType) {
$this->initLockField($path);
if ($targetType === self::LOCK_SHARED) {
$result = $this->connection->executeUpdate(
'UPDATE `*PREFIX*file_locks` SET `lock` = 1 WHERE `key` = ? AND `lock` = -1',
[$path]
);
} else {
$result = $this->connection->executeUpdate(
'UPDATE `*PREFIX*file_locks` SET `lock` = -1 WHERE `key` = ? AND `lock` = 1',
[$path]
);
}
if ($result !== 1) {
throw new LockedException($path);
}
$this->markChange($path, $targetType);
}
/**
* cleanup empty locks
*/
public function cleanEmptyLocks() {
$this->connection->executeUpdate(
'DELETE FROM `*PREFIX*file_locks` WHERE `lock` = 0'
);
}
public function __destruct() {
$this->cleanEmptyLocks();
}
}
|
