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/quic_bandwidth.h"
16#include "net/quic/quic_clock.h"
17#include "net/quic/quic_config.h"
18#include "net/quic/quic_connection_stats.h"
19#include "net/quic/quic_protocol.h"
20#include "net/quic/quic_time.h"
21
22namespace net {
23
24class RttStats;
25
26class NET_EXPORT_PRIVATE SendAlgorithmInterface {
27 public:
28  // A sorted vector of packets.
29  typedef std::vector<std::pair<QuicPacketSequenceNumber, TransmissionInfo>>
30      CongestionVector;
31
32  static SendAlgorithmInterface* Create(const QuicClock* clock,
33                                        const RttStats* rtt_stats,
34                                        CongestionControlType type,
35                                        QuicConnectionStats* stats);
36
37  virtual ~SendAlgorithmInterface() {}
38
39  virtual void SetFromConfig(const QuicConfig& config, bool is_server) = 0;
40
41  // Called when we receive congestion feedback from remote peer.
42  virtual void OnIncomingQuicCongestionFeedbackFrame(
43      const QuicCongestionFeedbackFrame& feedback,
44      QuicTime feedback_receive_time) = 0;
45
46  // Indicates an update to the congestion state, caused either by an incoming
47  // ack or loss event timeout.  |rtt_updated| indicates whether a new
48  // latest_rtt sample has been taken, |byte_in_flight| the bytes in flight
49  // prior to the congestion event.  |acked_packets| and |lost_packets| are
50  // any packets considered acked or lost as a result of the congestion event.
51  virtual void OnCongestionEvent(bool rtt_updated,
52                                 QuicByteCount bytes_in_flight,
53                                 const CongestionVector& acked_packets,
54                                 const CongestionVector& lost_packets) = 0;
55
56  // Inform that we sent |bytes| to the wire, and if the packet is
57  // retransmittable. Returns true if the packet should be tracked by the
58  // congestion manager and included in bytes_in_flight, false otherwise.
59  // |bytes_in_flight| is the number of bytes in flight before the packet was
60  // sent.
61  // Note: this function must be called for every packet sent to the wire.
62  virtual bool OnPacketSent(QuicTime sent_time,
63                            QuicByteCount bytes_in_flight,
64                            QuicPacketSequenceNumber sequence_number,
65                            QuicByteCount bytes,
66                            HasRetransmittableData is_retransmittable) = 0;
67
68  // Called when the retransmission timeout fires.  Neither OnPacketAbandoned
69  // nor OnPacketLost will be called for these packets.
70  virtual void OnRetransmissionTimeout(bool packets_retransmitted) = 0;
71
72  // Called when the last retransmission timeout was spurious.
73  virtual void RevertRetransmissionTimeout() = 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  // What's the current estimated bandwidth in bytes per second.
82  // Returns 0 when it does not have an estimate.
83  virtual QuicBandwidth BandwidthEstimate() const = 0;
84
85  // Returns true if the current bandwidth estimate is reliable.
86  virtual bool HasReliableBandwidthEstimate() const = 0;
87
88  // Get the send algorithm specific retransmission delay, called RTO in TCP,
89  // Note 1: the caller is responsible for sanity checking this value.
90  // Note 2: this will return zero if we don't have enough data for an estimate.
91  virtual QuicTime::Delta RetransmissionDelay() const = 0;
92
93  // Returns the size of the current congestion window in bytes.  Note, this is
94  // not the *available* window.  Some send algorithms may not use a congestion
95  // window and will return 0.
96  virtual QuicByteCount GetCongestionWindow() const = 0;
97
98  // Whether the send algorithm is currently in slow start.  When true, the
99  // BandwidthEstimate is expected to be too low.
100  virtual bool InSlowStart() const = 0;
101
102  // Whether the send algorithm is currently in recovery.
103  virtual bool InRecovery() const = 0;
104
105  // Returns the size of the slow start congestion window in bytes,
106  // aka ssthresh.  Some send algorithms do not define a slow start
107  // threshold and will return 0.
108  virtual QuicByteCount GetSlowStartThreshold() const = 0;
109
110  virtual CongestionControlType GetCongestionControlType() const = 0;
111};
112
113}  // namespace net
114
115#endif  // NET_QUIC_CONGESTION_CONTROL_SEND_ALGORITHM_INTERFACE_H_
116