TCP congestion control first draft

libraries/networking/src/udt/Socket.h

@@ -24,6 +24,7 @@
 #include "../HifiSockAddr.h"
 #include "CongestionControl.h"
 #include "Connection.h"
+#include "TCPRenoCC.h"
 
 //#define UDT_CONNECTION_DEBUG
 
@@ -131,7 +132,7 @@ private:
 
     int _maxBandwidth { -1 };
     
-    std::unique_ptr<CongestionControlVirtualFactory> _ccFactory { new CongestionControlFactory<DefaultCC>() };
+    std::unique_ptr<CongestionControlVirtualFactory> _ccFactory { new CongestionControlFactory<TCPRenoCC>() };
     
     friend UDTTest;
 };

libraries/networking/src/udt/TCPRenoCC.cpp

@@ -0,0 +1,84 @@
+//
+//  TCPRenoCC.cpp
+//  libraries/networking/src/udt
+//
+//  Created by Clement on 9/20/16.
+//  Copyright 2016 High Fidelity, Inc.
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+#include "TCPRenoCC.h"
+
+
+using namespace udt;
+
+void TCPRenoCC::init() {
+    _slowStart = true;
+    _issThreshold = 83333;
+
+    _packetSendPeriod = 0.0;
+    _congestionWindowSize = 2.0;
+
+    setAckInterval(2);
+    setRTO(1000000);
+}
+
+void TCPRenoCC::onACK(SequenceNumber ackNum) {
+    if (ackNum == _lastACK) {
+        if (3 == ++_duplicateAckCount) {
+            duplicateACKAction();
+        } else if (_duplicateAckCount > 3) {
+            _congestionWindowSize += 1.0;
+        } else {
+            ackAction();
+        }
+    } else {
+        if (_duplicateAckCount >= 3) {
+            _congestionWindowSize = _issThreshold;
+        }
+
+        _lastACK = ackNum;
+        _duplicateAckCount = 1;
+
+        ackAction();
+    }
+}
+
+void TCPRenoCC::onTimeout() {
+    _issThreshold = seqlen(_lastACK, _sendCurrSeqNum) / 2;
+    if (_issThreshold < 2) {
+        _issThreshold = 2;
+    }
+
+    _slowStart = true;
+    _congestionWindowSize = 2.0;
+}
+
+void TCPRenoCC::ackAction() {
+    if (_slowStart) {
+        _congestionWindowSize += 1.0;
+
+        if (_congestionWindowSize >= _issThreshold) {
+            _slowStart = false;
+        }
+    } else {
+        _congestionWindowSize += 1.0 / _congestionWindowSize;
+    }
+}
+
+void TCPRenoCC::duplicateACKAction() {
+    _slowStart = false;
+
+    _issThreshold = seqlen(_lastACK, _sendCurrSeqNum) / 2;
+    if (_issThreshold < 2) {
+        _issThreshold = 2;
+    }
+
+    _congestionWindowSize = _issThreshold + 3;
+}
+
+void TCPRenoCC::setInitialSendSequenceNumber(SequenceNumber seqNum) {
+    _lastACK = seqNum - 1;
+}

libraries/networking/src/udt/TCPRenoCC.h

@@ -0,0 +1,40 @@
+//
+//  TCPRenoCC.h
+//  libraries/networking/src/udt
+//
+//  Created by Clement on 9/20/16.
+//  Copyright 2016 High Fidelity, Inc.
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+#ifndef hifi_TCPRenoCC_h
+#define hifi_TCPRenoCC_h
+
+#include "CongestionControl.h"
+
+namespace udt {
+
+class TCPRenoCC : public CongestionControl {
+public:
+    virtual void init();
+    virtual void onACK(SequenceNumber ackNum);
+    virtual void onTimeout();
+
+protected:
+    virtual void ackAction();
+    virtual void duplicateACKAction();
+    virtual void setInitialSendSequenceNumber(SequenceNumber seqNum);
+
+    int _issThreshold;
+    bool _slowStart;
+    
+    int _duplicateAckCount;
+    SequenceNumber _lastACK;
+};
+
+}
+
+
+#endif // hifi_TCPRenoCC_h

tests/render-perf/src/main.cpp

@@ -18,10 +18,12 @@
 #include <QtCore/QElapsedTimer>
 #include <QtCore/QLoggingCategory>
 #include <QtCore/QRegularExpression>
+#include <QtCore/QSettings>
 #include <QtCore/QTimer>
 #include <QtCore/QThread>
 #include <QtCore/QThreadPool>
 
+
 #include <QtGui/QGuiApplication>
 #include <QtGui/QResizeEvent>
 #include <QtGui/QWindow>

tools/udt-test/src/UDTTest.cpp

@@ -25,7 +25,7 @@ const QCommandLineOption TARGET_OPTION {
     "IP:PORT or HOSTNAME:PORT"
 };
 const QCommandLineOption PACKET_SIZE {
-    "packet-size", "size for sent packets in bytes (defaults to " + QString(MAX_PACKET_SIZE) + ")", "bytes",
+    "packet-size", "size for sent packets in bytes (defaults to " + QString(udt::MAX_PACKET_SIZE) + ")", "bytes",
     QString(udt::MAX_PACKET_SIZE)
 };
 const QCommandLineOption MIN_PACKET_SIZE {