src/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 // Default maximum packet size used in Linux TCP implementations.
  25 const QuicByteCount kDefaultTCPMSS = 1460;
  26
  27 class RttStats;
  28
  29 namespace test {
  30 class TcpCubicSenderPeer;
  31 }  // namespace test
  32
  33 class NET_EXPORT_PRIVATE TcpCubicSender : public SendAlgorithmInterface {
  34  public:
  35   // Reno option and max_tcp_congestion_window are provided for testing.
  36   TcpCubicSender(const QuicClock* clock,
  37                  const RttStats* rtt_stats,
  38                  bool reno,
  39                  QuicTcpCongestionWindow max_tcp_congestion_window,
  40                  QuicConnectionStats* stats);
  41   virtual ~TcpCubicSender();
  42
  43   bool InSlowStart() const;
  44
  45   // Start implementation of SendAlgorithmInterface.
  46   virtual void SetFromConfig(const QuicConfig& config, bool is_server) OVERRIDE;
  47   virtual void OnIncomingQuicCongestionFeedbackFrame(
  48       const QuicCongestionFeedbackFrame& feedback,
  49       QuicTime feedback_receive_time) OVERRIDE;
  50   virtual void OnCongestionEvent(bool rtt_updated,
  51                                  QuicByteCount bytes_in_flight,
  52                                  const CongestionMap& acked_packets,
  53                                  const CongestionMap& lost_packets) OVERRIDE;
  54   virtual bool OnPacketSent(QuicTime sent_time,
  55                             QuicByteCount bytes_in_flight,
  56                             QuicPacketSequenceNumber sequence_number,
  57                             QuicByteCount bytes,
  58                             HasRetransmittableData is_retransmittable) OVERRIDE;
  59   virtual void OnRetransmissionTimeout(bool packets_retransmitted) OVERRIDE;
  60   virtual QuicTime::Delta TimeUntilSend(
  61       QuicTime now,
  62       QuicByteCount bytes_in_flight,
  63       HasRetransmittableData has_retransmittable_data) OVERRIDE;
  64   virtual QuicBandwidth BandwidthEstimate() const OVERRIDE;
  65   virtual QuicTime::Delta RetransmissionDelay() const OVERRIDE;
  66   virtual QuicByteCount GetCongestionWindow() const OVERRIDE;
  67   // End implementation of SendAlgorithmInterface.
  68
  69  private:
  70   friend class test::TcpCubicSenderPeer;
  71
  72   // TODO(ianswett): Remove these and migrate to OnCongestionEvent.
  73   void OnPacketAcked(QuicPacketSequenceNumber acked_sequence_number,
  74                      QuicByteCount acked_bytes,
  75                      QuicByteCount bytes_in_flight);
  76   void OnPacketLost(QuicPacketSequenceNumber largest_loss,
  77                     QuicByteCount bytes_in_flight);
  78
  79   QuicByteCount SendWindow();
  80   void MaybeIncreaseCwnd(QuicPacketSequenceNumber acked_sequence_number,
  81                          QuicByteCount bytes_in_flight);
  82   bool IsCwndLimited(QuicByteCount bytes_in_flight) const;
  83   bool InRecovery() const;
  84   // Methods for isolating PRR from the rest of TCP Cubic.
  85   void PrrOnPacketLost(QuicByteCount bytes_in_flight);
  86   void PrrOnPacketAcked(QuicByteCount acked_bytes);
  87   QuicTime::Delta PrrTimeUntilSend(QuicByteCount bytes_in_flight);
  88
  89
  90   HybridSlowStart hybrid_slow_start_;
  91   Cubic cubic_;
  92   const RttStats* rtt_stats_;
  93   QuicConnectionStats* stats_;
  94
  95   // Reno provided for testing.
  96   const bool reno_;
  97
  98   // ACK counter for the Reno implementation.
  99   int64 congestion_window_count_;
 100
 101   // Receiver side advertised window.
 102   QuicByteCount receive_window_;
 103
 104   // Bytes sent and acked since the last loss event.  Used for PRR.
 105   QuicByteCount prr_out_;
 106   QuicByteCount prr_delivered_;
 107   size_t ack_count_since_loss_;
 108
 109   // The congestion window before the last loss event.
 110   QuicByteCount bytes_in_flight_before_loss_;
 111
 112   // Track the largest packet that has been sent.
 113   QuicPacketSequenceNumber largest_sent_sequence_number_;
 114
 115   // Track the largest packet that has been acked.
 116   QuicPacketSequenceNumber largest_acked_sequence_number_;
 117
 118   // Track the largest sequence number outstanding when a CWND cutback occurs.
 119   QuicPacketSequenceNumber largest_sent_at_last_cutback_;
 120
 121   // Congestion window in packets.
 122   QuicTcpCongestionWindow congestion_window_;
 123
 124   // Slow start congestion window in packets, aka ssthresh.
 125   QuicTcpCongestionWindow slowstart_threshold_;
 126
 127   // Whether the last loss event caused us to exit slowstart.
 128   // Used for stats collection of slowstart_packets_lost
 129   bool last_cutback_exited_slowstart_;
 130
 131   // Maximum number of outstanding packets for tcp.
 132   QuicTcpCongestionWindow max_tcp_congestion_window_;
 133
 134   DISALLOW_COPY_AND_ASSIGN(TcpCubicSender);
 135 };
 136
 137 }  // namespace net
 138
 139 #endif  // NET_QUIC_CONGESTION_CONTROL_TCP_CUBIC_SENDER_H_