make send rate actually send rate, don't sync as sender

libraries/networking/src/udt/Connection.cpp

@@ -72,16 +72,18 @@ void Connection::sendReliablePacket(unique_ptr<Packet> packet) {
 }
 
 void Connection::sync() {
-    // we send out a periodic ACK every rate control interval
-    sendACK();
-    
-    // check if we need to re-transmit a loss list
-    // we do this if it has been longer than the current nakInterval since we last sent
-    auto now = high_resolution_clock::now();
-
-    if (duration_cast<microseconds>(now - _lastNAKTime).count() >= _nakInterval) {
-        // Send a timeout NAK packet
-        sendTimeoutNAK();
+    if (_hasReceivedFirstPacket) {
+        // we send out a periodic ACK every rate control interval
+        sendACK();
+        
+        // check if we need to re-transmit a loss list
+        // we do this if it has been longer than the current nakInterval since we last sent
+        auto now = high_resolution_clock::now();
+        
+        if (duration_cast<microseconds>(now - _lastNAKTime).count() >= _nakInterval) {
+            // Send a timeout NAK packet
+            sendTimeoutNAK();
+        }
     }
 }
 
@@ -265,6 +267,9 @@ SequenceNumber Connection::nextACK() const {
 }
 
 bool Connection::processReceivedSequenceNumber(SequenceNumber sequenceNumber, int packetSize, int payloadSize) {
+    
+    _hasReceivedFirstPacket = true;
+    
     // check if this is a packet pair we should estimate bandwidth from, or just a regular packet
     if (((uint32_t) sequenceNumber & 0xF) == 0) {
         _receiveWindow.onProbePair1Arrival();
@@ -424,7 +429,7 @@ void Connection::processACK(std::unique_ptr<ControlPacket> controlPacket) {
         static const int EMWA_ALPHA_NUMERATOR = 8;
         
         // record these samples in connection stats
-        _stats.recordReceiveRate(receiveRate);
+        _stats.recordSendRate(receiveRate);
         _stats.recordEstimatedBandwidth(bandwidth);
         
         _deliveryRate = (_deliveryRate * (EMWA_ALPHA_NUMERATOR - 1) + receiveRate) / EMWA_ALPHA_NUMERATOR;

libraries/networking/src/udt/Connection.h

@@ -86,6 +86,8 @@ private:
     int _minNAKInterval { 100000 }; // NAK timeout interval lower bound, default of 100ms
     std::chrono::high_resolution_clock::time_point _lastNAKTime;
     
+    bool _hasReceivedFirstPacket { false };
+    
     LossList _lossList; // List of all missing packets
     SequenceNumber _lastReceivedSequenceNumber; // The largest sequence number received from the peer
     SequenceNumber _lastReceivedACK; // The last ACK received

libraries/networking/src/udt/ConnectionStats.cpp

@@ -139,6 +139,11 @@ void ConnectionStats::recordDuplicates() {
 static const double EWMA_CURRENT_SAMPLE_WEIGHT = 0.125;
 static const double EWMA_PREVIOUS_SAMPLES_WEIGHT = 1 - 0.125;
 
+void ConnectionStats::recordSendRate(int sample) {
+    _currentSample.sendRate = sample;
+    _total.sendRate = (_total.sendRate * EWMA_PREVIOUS_SAMPLES_WEIGHT) + (sample * EWMA_CURRENT_SAMPLE_WEIGHT);
+}
+
 void ConnectionStats::recordReceiveRate(int sample) {
     _currentSample.receiveRate = sample;
     _total.receiveRate = (_total.receiveRate * EWMA_PREVIOUS_SAMPLES_WEIGHT) + (sample * EWMA_CURRENT_SAMPLE_WEIGHT);

libraries/networking/src/udt/ConnectionStats.h

@@ -52,6 +52,7 @@ public:
         int duplicates { 0 };
        
         // the following stats are trailing averages in the result, not totals
+        int sendRate { 0 };
         int receiveRate { 0 };
         int estimatedBandwith { 0 };
         int rtt { 0 };
@@ -84,6 +85,7 @@ public:
     void recordRetransmission();
     void recordDuplicates();
     
+    void recordSendRate(int sample);
     void recordReceiveRate(int sample);
     void recordEstimatedBandwidth(int sample);
     void recordRTT(int sample);

libraries/networking/src/udt/SendQueue.cpp

@@ -108,6 +108,8 @@ void SendQueue::overrideNAKListFromPacket(ControlPacket& packet) {
         packet.readPrimitive(&first);
         packet.readPrimitive(&second);
         
+        qDebug() << "NAK" << (uint32_t) first << (uint32_t) second;
+        
         if (first == second) {
             _naks.append(first);
         } else {

tools/udt-test/src/UDTTest.cpp

@@ -222,7 +222,7 @@ void UDTTest::sampleStats() {
     
     // setup a list of left justified values
     QStringList values {
-        QString::number(stats.receiveRate).leftJustified(STATS_TABLE_HEADERS[++headerIndex].size()),
+        QString::number(stats.sendRate).leftJustified(STATS_TABLE_HEADERS[++headerIndex].size()),
         QString::number(stats.rtt / USECS_PER_MSEC).leftJustified(STATS_TABLE_HEADERS[++headerIndex].size()),
         QString::number(stats.congestionWindowSize).leftJustified(STATS_TABLE_HEADERS[++headerIndex].size()),
         QString::number(stats.packetSendPeriod).leftJustified(STATS_TABLE_HEADERS[++headerIndex].size()),