public static function createId($queue, $class, $data = null, $run_at = 0)
    {
        $id = dechex(crc32($queue)).
            dechex(microtime(true) * 1000).
            md5(json_encode($class).json_encode($data).$run_at.uniqid('', true));

        return substr($id, 0, self::ID_LENGTH);
    }