protected function getCacheKey($itemkey)
    {
        $key = self::CACHE_PREFIX;

        // Add global identifier
        if ($this->config()->get('lock_bypage')) {
            $key .= '_' . md5($itemkey);
        }

        // Add user-specific identifier
        if ($this->config()->get('lock_byuserip') && Controller::has_curr()) {
            $ip = Controller::curr()->getRequest()->getIP();
            $key .= '_' . md5($ip);
        }

        return $key;
    }