MongoClient::pingHost PHP Method

    private function pingHost($host, $port)
    {
        $host_key = "{$host}:{$port}";
        $this->connectToHost($host, $port);
        $start_time = microtime(true);
        $this->protocols[$host_key]->opQuery('admin.$cmd', ['ping' => 1], 0, -1, 0, MongoCursor::$timeout);
        $this->hosts[$host_key]['ping'] = round((microtime(true) - $start_time) * 1000);
        $this->hosts[$host_key]['lastPing'] = time();
    }