Hprose\Swoole\Http\Transporter::fetch PHP Method

    public function fetch()
    {
        while (!empty($this->pool)) {
            $conn = array_pop($this->pool);
            if ($conn->isConnected()) {
                swoole_timer_clear($conn->timer);
                $conn->timer = null;
                return $conn;
            }
        }
        return null;
    }