Method SendData

library/cpp/netliba/v6/udp_client_server.cpp:687–803

    }

    void TUdpHost::SendData(TList<TTransferKey>* order, float deltaT1, bool needCheckAlive) {
        for (TList<TTransferKey>::iterator z = order->begin(); z != order->end();) {
            // pick connection to send
            const TTransferKey& transferKey = *z;
            TUdpOutXferHash::iterator i = SendQueue.find(transferKey);
            if (i == SendQueue.end()) {
                z = order->erase(z);
                continue;
            }
            ++z;

            // perform sending
            int transferId = transferKey.Id;
            TUdpOutTransfer& xfer = i->second;

            if (!xfer.AckTracker.IsInitialized()) {
                TIntrusivePtr<TCongestionControl> congestion = xfer.AckTracker.GetCongestionControl();
                Y_ASSERT(congestion.Get() != nullptr);
                if (!congestion->IsKnownMTU()) {
                    TLameMTUDiscovery* md = congestion->GetMTUDiscovery();
                    if (md->IsTimedOut()) {
                        congestion->SetMTU(UDP_PACKET_SIZE_SMALL);
                    } else {
                        if (md->CanSend()) {
                            SendPing(s, xfer.ToAddress, s.GetNetworkOrderPort());
                            md->PingSent();
                        }
                        continue;
                    }
                }
                // try to use large mtu, we could have selected small mtu due to connectivity problems
                if (congestion->GetMTU() == UDP_PACKET_SIZE_SMALL || IB.Get() != nullptr) {
                    // recheck every ~50mb
                    int chkDenom = (50000000 / xfer.Data->GetSize()) | 1;
                    if ((NetAckRnd() % chkDenom) == 0) {
                        //printf("send rechecking ping\n");
                        if (congestion->GetMTU() == UDP_PACKET_SIZE_SMALL) {
                            SendPing(s, xfer.ToAddress, s.GetNetworkOrderPort());
                        } else {
                            SendFakePing(s, xfer.ToAddress, s.GetNetworkOrderPort());
                        }
                    }
                }
                xfer.PacketSize = congestion->GetMTU();
                xfer.LastPacketSize = xfer.Data->GetSize() % xfer.PacketSize;
                xfer.PacketCount = xfer.Data->GetSize() / xfer.PacketSize + 1;
                xfer.AckTracker.SetPacketCount(xfer.PacketCount);
            }

            xfer.AckTracker.Step(deltaT1);
            MaxWaitTime = Min(MaxWaitTime, xfer.AckTracker.GetTimeToNextPacketTimeout());
            if (needCheckAlive && !xfer.AckTracker.IsAlive()) {
                FailedSend(transferId);
                SendQueue.erase(i);
                continue;
            }
            bool sendBufferOverflow = false;
            while (xfer.AckTracker.CanSend()) {