1// Copyright 2014 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#ifndef NET_QUIC_CONGESTION_CONTROL_TIME_LOSS_ALGORITHM_H_
6#define NET_QUIC_CONGESTION_CONTROL_TIME_LOSS_ALGORITHM_H_
7
8#include <algorithm>
9#include <map>
10
11#include "base/basictypes.h"
12#include "net/quic/congestion_control/loss_detection_interface.h"
13#include "net/quic/quic_protocol.h"
14#include "net/quic/quic_time.h"
15#include "net/quic/quic_unacked_packet_map.h"
16
17namespace net {
18
19// A loss detection algorithm which avoids spurious losses and retransmissions
20// by waiting 1.25 RTTs after a packet was sent instead of nack count.
21class NET_EXPORT_PRIVATE TimeLossAlgorithm : public LossDetectionInterface {
22 public:
23  TimeLossAlgorithm();
24  virtual ~TimeLossAlgorithm() {}
25
26  virtual LossDetectionType GetLossDetectionType() const OVERRIDE;
27
28  // Declares pending packets less than the largest observed lost when it has
29  // been 1.25 RTT since they were sent.  Packets larger than the largest
30  // observed are retransmitted via TLP.
31  virtual SequenceNumberSet DetectLostPackets(
32      const QuicUnackedPacketMap& unacked_packets,
33      const QuicTime& time,
34      QuicPacketSequenceNumber largest_observed,
35      const RttStats& rtt_stats) OVERRIDE;
36
37  // Returns the time the next packet will be lost, or zero if there
38  // are no nacked pending packets outstanding.
39  // TODO(ianswett): Ideally the RTT variance and the RTT would be used to
40  // determine the time a packet is considered lost.
41  // TODO(ianswett): Consider using Max(1.25 * srtt, 1.125 * last_rtt).
42  virtual QuicTime GetLossTimeout() const OVERRIDE;
43
44 private:
45  QuicTime loss_detection_timeout_;
46
47  DISALLOW_COPY_AND_ASSIGN(TimeLossAlgorithm);
48};
49
50}  // namespace net
51
52#endif  // NET_QUIC_CONGESTION_CONTROL_TIME_LOSS_ALGORITHM_H_
53