net/quic/congestion_control/send_algorithm_interface.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 // The pure virtual class for send side congestion control algorithm.
   6
   7 #ifndef NET_QUIC_CONGESTION_CONTROL_SEND_ALGORITHM_INTERFACE_H_
   8 #define NET_QUIC_CONGESTION_CONTROL_SEND_ALGORITHM_INTERFACE_H_
   9
  10 #include <algorithm>
  11 #include <map>
  12
  13 #include "base/basictypes.h"
  14 #include "net/base/net_export.h"
  15 #include "net/quic/crypto/cached_network_parameters.h"
  16 #include "net/quic/quic_bandwidth.h"
  17 #include "net/quic/quic_clock.h"
  18 #include "net/quic/quic_config.h"
  19 #include "net/quic/quic_connection_stats.h"
  20 #include "net/quic/quic_protocol.h"
  21 #include "net/quic/quic_time.h"
  22
  23 namespace net {
  24
  25 class RttStats;
  26
  27 class NET_EXPORT_PRIVATE SendAlgorithmInterface {
  28  public:
  29   // A sorted vector of packets.
  30   typedef std::vector<std::pair<QuicPacketSequenceNumber, TransmissionInfo>>
  31       CongestionVector;
  32
  33   static SendAlgorithmInterface* Create(
  34       const QuicClock* clock,
  35       const RttStats* rtt_stats,
  36       CongestionControlType type,
  37       QuicConnectionStats* stats,
  38       QuicPacketCount initial_congestion_window);
  39
  40   virtual ~SendAlgorithmInterface() {}
  41
  42   virtual void SetFromConfig(
  43       const QuicConfig& config, bool is_server, bool using_pacing) = 0;
  44
  45   // Sets the number of connections to emulate when doing congestion control,
  46   // particularly for congestion avoidance.  Can be set any time.
  47   virtual void SetNumEmulatedConnections(int num_connections) = 0;
  48
  49   // Indicates an update to the congestion state, caused either by an incoming
  50   // ack or loss event timeout.  |rtt_updated| indicates whether a new
  51   // latest_rtt sample has been taken, |byte_in_flight| the bytes in flight
  52   // prior to the congestion event.  |acked_packets| and |lost_packets| are
  53   // any packets considered acked or lost as a result of the congestion event.
  54   virtual void OnCongestionEvent(bool rtt_updated,
  55                                  QuicByteCount bytes_in_flight,
  56                                  const CongestionVector& acked_packets,
  57                                  const CongestionVector& lost_packets) = 0;
  58
  59   // Inform that we sent |bytes| to the wire, and if the packet is
  60   // retransmittable. Returns true if the packet should be tracked by the
  61   // congestion manager and included in bytes_in_flight, false otherwise.
  62   // |bytes_in_flight| is the number of bytes in flight before the packet was
  63   // sent.
  64   // Note: this function must be called for every packet sent to the wire.
  65   virtual bool OnPacketSent(QuicTime sent_time,
  66                             QuicByteCount bytes_in_flight,
  67                             QuicPacketSequenceNumber sequence_number,
  68                             QuicByteCount bytes,
  69                             HasRetransmittableData is_retransmittable) = 0;
  70
  71   // Called when the retransmission timeout fires.  Neither OnPacketAbandoned
  72   // nor OnPacketLost will be called for these packets.
  73   virtual void OnRetransmissionTimeout(bool packets_retransmitted) = 0;
  74
  75   // Calculate the time until we can send the next packet.
  76   virtual QuicTime::Delta TimeUntilSend(
  77       QuicTime now,
  78       QuicByteCount bytes_in_flight,
  79       HasRetransmittableData has_retransmittable_data) const = 0;
  80
  81   // The pacing rate of the send algorithm.  May be zero if the rate is unknown.
  82   virtual QuicBandwidth PacingRate() const = 0;
  83
  84   // What's the current estimated bandwidth in bytes per second.
  85   // Returns 0 when it does not have an estimate.
  86   virtual QuicBandwidth BandwidthEstimate() const = 0;
  87
  88   // Returns true if the current bandwidth estimate is reliable.
  89   virtual bool HasReliableBandwidthEstimate() const = 0;
  90
  91   // Get the send algorithm specific retransmission delay, called RTO in TCP,
  92   // Note 1: the caller is responsible for sanity checking this value.
  93   // Note 2: this will return zero if we don't have enough data for an estimate.
  94   virtual QuicTime::Delta RetransmissionDelay() const = 0;
  95
  96   // Returns the size of the current congestion window in bytes.  Note, this is
  97   // not the *available* window.  Some send algorithms may not use a congestion
  98   // window and will return 0.
  99   virtual QuicByteCount GetCongestionWindow() const = 0;
 100
 101   // Whether the send algorithm is currently in slow start.  When true, the
 102   // BandwidthEstimate is expected to be too low.
 103   virtual bool InSlowStart() const = 0;
 104
 105   // Whether the send algorithm is currently in recovery.
 106   virtual bool InRecovery() const = 0;
 107
 108   // Returns the size of the slow start congestion window in bytes,
 109   // aka ssthresh.  Some send algorithms do not define a slow start
 110   // threshold and will return 0.
 111   virtual QuicByteCount GetSlowStartThreshold() const = 0;
 112
 113   virtual CongestionControlType GetCongestionControlType() const = 0;
 114
 115   // Called by the Session when we get a bandwidth estimate from the client.
 116   // Returns true if initial connection state is changed as a result.
 117   virtual bool ResumeConnectionState(
 118       const CachedNetworkParameters& cached_network_params) = 0;
 119 };
 120
 121 }  // namespace net
 122
 123 #endif  // NET_QUIC_CONGESTION_CONTROL_SEND_ALGORITHM_INTERFACE_H_