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/prr_sender.h"
  17 #include "net/quic/congestion_control/send_algorithm_interface.h"
  18 #include "net/quic/crypto/cached_network_parameters.h"
  19 #include "net/quic/quic_bandwidth.h"
  20 #include "net/quic/quic_connection_stats.h"
  21 #include "net/quic/quic_protocol.h"
  22 #include "net/quic/quic_time.h"
  23
  24 namespace net {
  25
  26 class RttStats;
  27
  28 namespace test {
  29 class TcpCubicSenderPeer;
  30 }  // namespace test
  31
  32 class NET_EXPORT_PRIVATE TcpCubicSender : public SendAlgorithmInterface {
  33  public:
  34   // Reno option and max_tcp_congestion_window are provided for testing.
  35   TcpCubicSender(const QuicClock* clock,
  36                  const RttStats* rtt_stats,
  37                  bool reno,
  38                  QuicPacketCount initial_tcp_congestion_window,
  39                  QuicPacketCount max_tcp_congestion_window,
  40                  QuicConnectionStats* stats);
  41   ~TcpCubicSender() override;
  42
  43   // Start implementation of SendAlgorithmInterface.
  44   void SetFromConfig(const QuicConfig& config,
  45                      bool is_server,
  46                      bool using_pacing) override;
  47   bool ResumeConnectionState(
  48       const CachedNetworkParameters& cached_network_params) override;
  49   void SetNumEmulatedConnections(int num_connections) override;
  50   void OnCongestionEvent(bool rtt_updated,
  51                          QuicByteCount bytes_in_flight,
  52                          const CongestionVector& acked_packets,
  53                          const CongestionVector& lost_packets) override;
  54   bool OnPacketSent(QuicTime sent_time,
  55                     QuicByteCount bytes_in_flight,
  56                     QuicPacketSequenceNumber sequence_number,
  57                     QuicByteCount bytes,
  58                     HasRetransmittableData is_retransmittable) override;
  59   void OnRetransmissionTimeout(bool packets_retransmitted) override;
  60   void RevertRetransmissionTimeout() override;
  61   QuicTime::Delta TimeUntilSend(
  62       QuicTime now,
  63       QuicByteCount bytes_in_flight,
  64       HasRetransmittableData has_retransmittable_data) const override;
  65   QuicBandwidth PacingRate() const override;
  66   QuicBandwidth BandwidthEstimate() const override;
  67   bool HasReliableBandwidthEstimate() const override;
  68   QuicTime::Delta RetransmissionDelay() const override;
  69   QuicByteCount GetCongestionWindow() const override;
  70   bool InSlowStart() const override;
  71   bool InRecovery() const override;
  72   QuicByteCount GetSlowStartThreshold() const override;
  73   CongestionControlType GetCongestionControlType() const override;
  74   // End implementation of SendAlgorithmInterface.
  75
  76  private:
  77   friend class test::TcpCubicSenderPeer;
  78
  79   // Compute the TCP Reno beta based on the current number of connections.
  80   float RenoBeta() const;
  81
  82   // TODO(ianswett): Remove these and migrate to OnCongestionEvent.
  83   void OnPacketAcked(QuicPacketSequenceNumber acked_sequence_number,
  84                      QuicByteCount acked_bytes,
  85                      QuicByteCount bytes_in_flight);
  86   void OnPacketLost(QuicPacketSequenceNumber largest_loss,
  87                     QuicByteCount bytes_in_flight);
  88
  89   void MaybeIncreaseCwnd(QuicPacketSequenceNumber acked_sequence_number,
  90                          QuicByteCount bytes_in_flight);
  91   bool IsCwndLimited(QuicByteCount bytes_in_flight) const;
  92
  93   HybridSlowStart hybrid_slow_start_;
  94   Cubic cubic_;
  95   PrrSender prr_;
  96   const RttStats* rtt_stats_;
  97   QuicConnectionStats* stats_;
  98
  99   // If true, Reno congestion control is used instead of Cubic.
 100   const bool reno_;
 101
 102   // Number of connections to simulate.
 103   uint32 num_connections_;
 104
 105   // ACK counter for the Reno implementation.
 106   uint64 congestion_window_count_;
 107
 108   // Track the largest packet that has been sent.
 109   QuicPacketSequenceNumber largest_sent_sequence_number_;
 110
 111   // Track the largest packet that has been acked.
 112   QuicPacketSequenceNumber largest_acked_sequence_number_;
 113
 114   // Track the largest sequence number outstanding when a CWND cutback occurs.
 115   QuicPacketSequenceNumber largest_sent_at_last_cutback_;
 116
 117   // Congestion window in packets.
 118   QuicPacketCount congestion_window_;
 119
 120   // Congestion window before the last RTO.
 121   // Must be 0 before or after RTO recovery.
 122   QuicPacketCount previous_congestion_window_;
 123
 124   // Slow start congestion window in packets, aka ssthresh.
 125   QuicPacketCount slowstart_threshold_;
 126
 127   // Slow start threshold before the last loss event or RTO.
 128   QuicPacketCount previous_slowstart_threshold_;
 129
 130   // Whether the last loss event caused us to exit slowstart.
 131   // Used for stats collection of slowstart_packets_lost
 132   bool last_cutback_exited_slowstart_;
 133
 134   // Maximum number of outstanding packets for tcp.
 135   QuicPacketCount max_tcp_congestion_window_;
 136
 137   const QuicClock* clock_;
 138
 139   DISALLOW_COPY_AND_ASSIGN(TcpCubicSender);
 140 };
 141
 142 }  // namespace net
 143
 144 #endif  // NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_SENDER_H_