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 TCP cubic.
   6
   7 #ifndef NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_SENDER_H_
   8 #define NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_SENDER_H_
   9
  10 #include "base/basictypes.h"
  11 #include "base/compiler_specific.h"
  12 #include "net/base/net_export.h"
  13 #include "net/quic/congestion_control/cubic.h"
  14 #include "net/quic/congestion_control/hybrid_slow_start.h"
  15 #include "net/quic/congestion_control/prr_sender.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                  QuicPacketCount initial_tcp_congestion_window,
  37                  QuicPacketCount max_tcp_congestion_window,
  38                  QuicConnectionStats* stats);
  39   ~TcpCubicSender() override;
  40
  41   // Start implementation of SendAlgorithmInterface.
  42   void SetFromConfig(const QuicConfig& config,
  43                      Perspective perspective) override;
  44   void ResumeConnectionState(
  45       const CachedNetworkParameters& cached_network_params,
  46       bool max_bandwidth_resumption) override;
  47   void SetNumEmulatedConnections(int num_connections) override;
  48   void SetMaxCongestionWindow(QuicByteCount max_congestion_window) override;
  49   void OnCongestionEvent(bool rtt_updated,
  50                          QuicByteCount bytes_in_flight,
  51                          const CongestionVector& acked_packets,
  52                          const CongestionVector& lost_packets) override;
  53   bool OnPacketSent(QuicTime sent_time,
  54                     QuicByteCount bytes_in_flight,
  55                     QuicPacketNumber packet_number,
  56                     QuicByteCount bytes,
  57                     HasRetransmittableData is_retransmittable) override;
  58   void OnRetransmissionTimeout(bool packets_retransmitted) override;
  59   QuicTime::Delta TimeUntilSend(
  60       QuicTime now,
  61       QuicByteCount bytes_in_flight,
  62       HasRetransmittableData has_retransmittable_data) const override;
  63   QuicBandwidth PacingRate() const override;
  64   QuicBandwidth BandwidthEstimate() const override;
  65   QuicTime::Delta RetransmissionDelay() const override;
  66   QuicByteCount GetCongestionWindow() const override;
  67   bool InSlowStart() const override;
  68   bool InRecovery() const override;
  69   QuicByteCount GetSlowStartThreshold() const override;
  70   CongestionControlType GetCongestionControlType() const override;
  71   // End implementation of SendAlgorithmInterface.
  72
  73  private:
  74   friend class test::TcpCubicSenderPeer;
  75
  76   // Compute the TCP Reno beta based on the current number of connections.
  77   float RenoBeta() const;
  78
  79   // TODO(ianswett): Remove these and migrate to OnCongestionEvent.
  80   void OnPacketAcked(QuicPacketNumber acked_packet_number,
  81                      QuicByteCount acked_bytes,
  82                      QuicByteCount bytes_in_flight);
  83   void OnPacketLost(QuicPacketNumber largest_loss,
  84                     QuicByteCount bytes_in_flight);
  85
  86   void MaybeIncreaseCwnd(QuicPacketNumber acked_packet_number,
  87                          QuicByteCount bytes_in_flight);
  88   bool IsCwndLimited(QuicByteCount bytes_in_flight) const;
  89
  90   HybridSlowStart hybrid_slow_start_;
  91   Cubic cubic_;
  92   PrrSender prr_;
  93   const RttStats* rtt_stats_;
  94   QuicConnectionStats* stats_;
  95
  96   // If true, Reno congestion control is used instead of Cubic.
  97   const bool reno_;
  98
  99   // Number of connections to simulate.
 100   uint32 num_connections_;
 101
 102   // ACK counter for the Reno implementation.
 103   uint64 congestion_window_count_;
 104
 105   // Track the largest packet that has been sent.
 106   QuicPacketNumber largest_sent_packet_number_;
 107
 108   // Track the largest packet that has been acked.
 109   QuicPacketNumber largest_acked_packet_number_;
 110
 111   // Track the largest packet number outstanding when a CWND cutback occurs.
 112   QuicPacketNumber largest_sent_at_last_cutback_;
 113
 114   // Congestion window in packets.
 115   QuicPacketCount congestion_window_;
 116
 117   // Minimum congestion window in packets.
 118   QuicPacketCount min_congestion_window_;
 119
 120   // Whether to use 4 packets as the actual min, but pace lower.
 121   bool min4_mode_;
 122
 123   // Slow start congestion window in packets, aka ssthresh.
 124   QuicPacketCount slowstart_threshold_;
 125
 126   // Whether the last loss event caused us to exit slowstart.
 127   // Used for stats collection of slowstart_packets_lost
 128   bool last_cutback_exited_slowstart_;
 129
 130   // Maximum number of outstanding packets for tcp.
 131   QuicPacketCount max_tcp_congestion_window_;
 132
 133   const QuicClock* clock_;
 134
 135   DISALLOW_COPY_AND_ASSIGN(TcpCubicSender);
 136 };
 137
 138 }  // namespace net
 139
 140 #endif  // NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_SENDER_H_