net/quic/congestion_control/tcp_cubic_sender.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4 //
   5 // TCP cubic send side congestion algorithm, emulates the behavior of
   6 // TCP cubic.
   7
   8 #ifndef NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_SENDER_H_
   9 #define NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_SENDER_H_
  10
  11 #include "base/basictypes.h"
  12 #include "base/compiler_specific.h"
  13 #include "net/base/net_export.h"
  14 #include "net/quic/congestion_control/cubic.h"
  15 #include "net/quic/congestion_control/hybrid_slow_start.h"
  16 #include "net/quic/congestion_control/send_algorithm_interface.h"
  17 #include "net/quic/quic_bandwidth.h"
  18 #include "net/quic/quic_connection_stats.h"
  19 #include "net/quic/quic_protocol.h"
  20 #include "net/quic/quic_time.h"
  21
  22 namespace net {
  23
  24 class RttStats;
  25
  26 namespace test {
  27 class TcpCubicSenderPeer;
  28 }  // namespace test
  29
  30 class NET_EXPORT_PRIVATE TcpCubicSender : public SendAlgorithmInterface {
  31  public:
  32   // Reno option and max_tcp_congestion_window are provided for testing.
  33   TcpCubicSender(const QuicClock* clock,
  34                  const RttStats* rtt_stats,
  35                  bool reno,
  36                  QuicTcpCongestionWindow max_tcp_congestion_window,
  37                  QuicConnectionStats* stats);
  38   ~TcpCubicSender() override;
  39
  40   // Start implementation of SendAlgorithmInterface.
  41   void SetFromConfig(const QuicConfig& config, bool is_server) override;
  42   void SetNumEmulatedConnections(int num_connections) override;
  43   void OnIncomingQuicCongestionFeedbackFrame(
  44       const QuicCongestionFeedbackFrame& feedback,
  45       QuicTime feedback_receive_time) override;
  46   void OnCongestionEvent(bool rtt_updated,
  47                          QuicByteCount bytes_in_flight,
  48                          const CongestionVector& acked_packets,
  49                          const CongestionVector& lost_packets) override;
  50   bool OnPacketSent(QuicTime sent_time,
  51                     QuicByteCount bytes_in_flight,
  52                     QuicPacketSequenceNumber sequence_number,
  53                     QuicByteCount bytes,
  54                     HasRetransmittableData is_retransmittable) override;
  55   void OnRetransmissionTimeout(bool packets_retransmitted) override;
  56   void RevertRetransmissionTimeout() override;
  57   QuicTime::Delta TimeUntilSend(
  58       QuicTime now,
  59       QuicByteCount bytes_in_flight,
  60       HasRetransmittableData has_retransmittable_data) const override;
  61   QuicBandwidth PacingRate() const override;
  62   QuicBandwidth BandwidthEstimate() const override;
  63   bool HasReliableBandwidthEstimate() const override;
  64   QuicTime::Delta RetransmissionDelay() const override;
  65   QuicByteCount GetCongestionWindow() const override;
  66   bool InSlowStart() const override;
  67   bool InRecovery() const override;
  68   QuicByteCount GetSlowStartThreshold() const override;
  69   CongestionControlType GetCongestionControlType() const override;
  70   // End implementation of SendAlgorithmInterface.
  71
  72  private:
  73   friend class test::TcpCubicSenderPeer;
  74
  75   // TODO(ianswett): Remove these and migrate to OnCongestionEvent.
  76   void OnPacketAcked(QuicPacketSequenceNumber acked_sequence_number,
  77                      QuicByteCount acked_bytes,
  78                      QuicByteCount bytes_in_flight);
  79   void OnPacketLost(QuicPacketSequenceNumber largest_loss,
  80                     QuicByteCount bytes_in_flight);
  81
  82   QuicByteCount SendWindow() const;
  83   void MaybeIncreaseCwnd(QuicPacketSequenceNumber acked_sequence_number,
  84                          QuicByteCount bytes_in_flight);
  85   bool IsCwndLimited(QuicByteCount bytes_in_flight) const;
  86   // Methods for isolating PRR from the rest of TCP Cubic.
  87   void PrrOnPacketLost(QuicByteCount bytes_in_flight);
  88   void PrrOnPacketAcked(QuicByteCount acked_bytes);
  89   QuicTime::Delta PrrTimeUntilSend(QuicByteCount bytes_in_flight) const;
  90
  91
  92   HybridSlowStart hybrid_slow_start_;
  93   Cubic cubic_;
  94   const RttStats* rtt_stats_;
  95   QuicConnectionStats* stats_;
  96
  97   // If true, Reno congestion control is used instead of Cubic.
  98   const bool reno_;
  99
 100   // Number of connections to simulate.
 101   int num_connections_;
 102
 103   // ACK counter for the Reno implementation.
 104   int64 congestion_window_count_;
 105
 106   // Receiver side advertised window.
 107   QuicByteCount receive_window_;
 108
 109   // Bytes sent and acked since the last loss event.  Used for PRR.
 110   QuicByteCount prr_out_;
 111   QuicByteCount prr_delivered_;
 112   size_t ack_count_since_loss_;
 113
 114   // The congestion window before the last loss event.
 115   QuicByteCount bytes_in_flight_before_loss_;
 116
 117   // Track the largest packet that has been sent.
 118   QuicPacketSequenceNumber largest_sent_sequence_number_;
 119
 120   // Track the largest packet that has been acked.
 121   QuicPacketSequenceNumber largest_acked_sequence_number_;
 122
 123   // Track the largest sequence number outstanding when a CWND cutback occurs.
 124   QuicPacketSequenceNumber largest_sent_at_last_cutback_;
 125
 126   // Congestion window in packets.
 127   QuicTcpCongestionWindow congestion_window_;
 128
 129   // Congestion window before the last loss event or RTO.
 130   QuicByteCount previous_congestion_window_;
 131
 132   // Slow start congestion window in packets, aka ssthresh.
 133   QuicTcpCongestionWindow slowstart_threshold_;
 134
 135   // Slow start threshold before the last loss event or RTO.
 136   QuicTcpCongestionWindow previous_slowstart_threshold_;
 137
 138   // Whether the last loss event caused us to exit slowstart.
 139   // Used for stats collection of slowstart_packets_lost
 140   bool last_cutback_exited_slowstart_;
 141
 142   // Maximum number of outstanding packets for tcp.
 143   QuicTcpCongestionWindow max_tcp_congestion_window_;
 144
 145   DISALLOW_COPY_AND_ASSIGN(TcpCubicSender);
 146 };
 147
 148 }  // namespace net
 149
 150 #endif  // NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_SENDER_H_