protected function getPool($pool = null)
    {
        if (!is_null($pool)) {
            $result = (string) $pool;
        } elseif (isset($_SERVER['SERVER_ADDR']) && isset($_SERVER['SERVER_PORT'])) {
            $result = $_SERVER['SERVER_ADDR'] . '-' . $_SERVER['SERVER_PORT'];
        } else {
            $result = $this->generateUniqueID();
        }
        return $result;
    }