net/quic/congestion_control/time_loss_algorithm.h

   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
  17 namespace 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.
  21 class NET_EXPORT_PRIVATE TimeLossAlgorithm : public LossDetectionInterface {
  22  public:
  23   TimeLossAlgorithm();
  24   ~TimeLossAlgorithm() override {}
  25
  26   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   PacketNumberSet DetectLostPackets(const QuicUnackedPacketMap& unacked_packets,
  32                                     const QuicTime& time,
  33                                     QuicPacketNumber largest_observed,
  34                                     const RttStats& rtt_stats) override;
  35
  36   // Returns the time the next packet will be lost, or zero if there
  37   // are no nacked pending packets outstanding.
  38   // TODO(ianswett): Ideally the RTT variance and the RTT would be used to
  39   // determine the time a packet is considered lost.
  40   // TODO(ianswett): Consider using Max(1.25 * srtt, 1.125 * last_rtt).
  41   QuicTime GetLossTimeout() const override;
  42
  43  private:
  44   QuicTime loss_detection_timeout_;
  45
  46   DISALLOW_COPY_AND_ASSIGN(TimeLossAlgorithm);
  47 };
  48
  49 }  // namespace net
  50
  51 #endif  // NET_QUIC_CONGESTION_CONTROL_TIME_LOSS_ALGORITHM_H_