protected function _lockAdd($key)
{
if ($this->_memcache instanceof Memcached) {
$this->_memcache->add($this->_key($key . self::LOCK_SUFFIX), 1, self::LOCK_TIMEOUT);
} else {
$this->_memcache->add($this->_key($key . self::LOCK_SUFFIX), 1, 0, self::LOCK_TIMEOUT);
}
}