net/quic/congestion_control/tcp_cubic_bytes_sender.h

   1 // Copyright (c) 2015 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_BYTES_SENDER_H_
   8 #define NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_BYTES_SENDER_H_
   9
  10 #include "base/basictypes.h"
  11 #include "net/base/net_export.h"
  12 #include "net/quic/congestion_control/cubic_bytes.h"
  13 #include "net/quic/congestion_control/hybrid_slow_start.h"
  14 #include "net/quic/congestion_control/prr_sender.h"
  15 #include "net/quic/congestion_control/send_algorithm_interface.h"
  16 #include "net/quic/quic_bandwidth.h"
  17 #include "net/quic/quic_connection_stats.h"
  18 #include "net/quic/quic_protocol.h"
  19 #include "net/quic/quic_time.h"
  20
  21 namespace net {
  22
  23 class RttStats;
  24
  25 namespace test {
  26 class TcpCubicBytesSenderPeer;
  27 }  // namespace test
  28
  29 class NET_EXPORT_PRIVATE TcpCubicBytesSender : public SendAlgorithmInterface {
  30  public:
  31   TcpCubicBytesSender(const QuicClock* clock,
  32                       const RttStats* rtt_stats,
  33                       bool reno,
  34                       QuicPacketCount initial_tcp_congestion_window,
  35                       QuicPacketCount max_congestion_window,
  36                       QuicConnectionStats* stats);
  37   ~TcpCubicBytesSender() override;
  38
  39   // Start implementation of SendAlgorithmInterface.
  40   void SetFromConfig(const QuicConfig& config,
  41                      Perspective perspective) override;
  42   void ResumeConnectionState(
  43       const CachedNetworkParameters& cached_network_params,
  44       bool max_bandwidth_resumption) override;
  45   void SetNumEmulatedConnections(int num_connections) override;
  46   void SetMaxCongestionWindow(QuicByteCount max_congestion_window) override;
  47   void OnCongestionEvent(bool rtt_updated,
  48                          QuicByteCount bytes_in_flight,
  49                          const CongestionVector& acked_packets,
  50                          const CongestionVector& lost_packets) override;
  51   bool OnPacketSent(QuicTime sent_time,
  52                     QuicByteCount bytes_in_flight,
  53                     QuicPacketSequenceNumber sequence_number,
  54                     QuicByteCount bytes,
  55                     HasRetransmittableData is_retransmittable) override;
  56   void OnRetransmissionTimeout(bool packets_retransmitted) 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   QuicTime::Delta RetransmissionDelay() const override;
  64   QuicByteCount GetCongestionWindow() const override;
  65   bool InSlowStart() const override;
  66   bool InRecovery() const override;
  67   QuicByteCount GetSlowStartThreshold() const override;
  68   CongestionControlType GetCongestionControlType() const override;
  69   // End implementation of SendAlgorithmInterface.
  70
  71  private:
  72   friend class test::TcpCubicBytesSenderPeer;
  73
  74   // Compute the TCP Reno beta based on the current number of connections.
  75   float RenoBeta() const;
  76
  77   // TODO(ianswett): Remove these and migrate to OnCongestionEvent.
  78   void OnPacketAcked(QuicPacketSequenceNumber acked_sequence_number,
  79                      QuicByteCount acked_bytes,
  80                      QuicByteCount bytes_in_flight);
  81   void OnPacketLost(QuicPacketSequenceNumber largest_loss,
  82                     QuicByteCount bytes_in_flight);
  83
  84   void MaybeIncreaseCwnd(QuicPacketSequenceNumber acked_sequence_number,
  85                          QuicByteCount acked_bytes,
  86                          QuicByteCount bytes_in_flight);
  87   bool IsCwndLimited(QuicByteCount bytes_in_flight) const;
  88
  89   HybridSlowStart hybrid_slow_start_;
  90   CubicBytes cubic_;
  91   PrrSender prr_;
  92   const RttStats* rtt_stats_;
  93   QuicConnectionStats* stats_;
  94
  95   // If true, Reno congestion control is used instead of Cubic.
  96   const bool reno_;
  97
  98   // Number of connections to simulate.
  99   uint32 num_connections_;
 100
 101   // ACK counter for the Reno implementation.
 102   uint64 num_acked_packets_;
 103
 104   // Track the largest packet that has been sent.
 105   QuicPacketSequenceNumber largest_sent_sequence_number_;
 106
 107   // Track the largest packet that has been acked.
 108   QuicPacketSequenceNumber largest_acked_sequence_number_;
 109
 110   // Track the largest sequence number outstanding when a CWND cutback occurs.
 111   QuicPacketSequenceNumber largest_sent_at_last_cutback_;
 112
 113   // Congestion window in bytes.
 114   QuicByteCount congestion_window_;
 115
 116   // Minimum congestion window in bytes.
 117   QuicByteCount min_congestion_window_;
 118
 119   // Whether to use 4 packets as the actual min, but pace lower.
 120   bool min4_mode_;
 121
 122   // Maximum congestion window in bytes.
 123   QuicByteCount max_congestion_window_;
 124
 125   // Slow start congestion window in bytes, aka ssthresh.
 126   QuicByteCount slowstart_threshold_;
 127
 128   // Whether the last loss event caused us to exit slowstart. Used for stats
 129   // collection of slowstart_packets_lost.
 130   bool last_cutback_exited_slowstart_;
 131
 132   const QuicClock* clock_;
 133
 134   DISALLOW_COPY_AND_ASSIGN(TcpCubicBytesSender);
 135 };
 136
 137 }  // namespace net
 138
 139 #endif  // NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_BYTES_SENDER_H_