owncloud/core

<?php
/**
 * @author Robin Appelman <icewind@owncloud.com>
 *
 * @copyright Copyright (c) 2018, ownCloud GmbH
 * @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\Memcache;

trait CADTrait {
    abstract public function get($key);

    abstract public function remove($key);

    abstract public function add($key, $value, $ttl = 0);

    /**
     * Compare and delete
     *
     * @param string $key
     * @param mixed $old
     * @return bool
     */
    public function cad($key, $old) {
        //no native cas, emulate with locking
        if ($this->add($key . '_lock', true)) {
            if ($this->get($key) === $old) {
                $this->remove($key);
                $this->remove($key . '_lock');
                return true;
            } else {
                $this->remove($key . '_lock');
                return false;
            }
        } else {
            return false;
        }
    }
}