PHPDaemon\Clients\Mongo\Pool::aggregate PHP Method

    public function aggregate($p, $cb)
    {
        $this->_params($p);
        $e = explode('.', $p['col'], 2);
        $query = ['aggregate' => $e[1]];
        if (isset($p['rp'])) {
            $query['$readPreference'] = $p['rp'];
            unset($p['rp']);
        }
        foreach ($p as $k => $v) {
            if (substr($k, 0, 1) === '$' || $k === 'pipeline') {
                $query[$k] = $v;
            }
        }
        $cb = CallbackWrapper::wrap($cb);
        try {
            $this->request(self::OP_QUERY, pack('V', $p['opts']) . $e[0] . '.$cmd' . "" . pack('VV', $p['offset'], $p['limit']) . bson_encode($query) . (isset($p['fields']) ? bson_encode($p['fields']) : ''), true, null, function ($conn, $reqId = null) use($p, $cb) {
                if (!$conn) {
                    !$cb || $cb(['$err' => 'Connection error.']);
                    return;
                }
                $conn->requests[$reqId] = [$p['col'], $cb, false];
            });
        } catch (\MongoException $e) {
            Daemon::log('MongoClient exception: ' . $e->getMessage() . ': ' . $e->getTraceAsString());
            if ($cb !== null) {
                $cb(['$err' => $e->getMessage(), '$query' => $query, '$fields' => isset($p['fields']) ? $p['fields'] : null]);
            }
        }
    }