net/quic/congestion_control/tcp_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_TCP_LOSS_ALGORITHM_H_
   6 #define NET_QUIC_CONGESTION_CONTROL_TCP_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 // Class which implement's TCP's approach of detecting loss when 3 nacks have
  20 // been received for a packet.  Also implements TCP's early retransmit(RFC5827).
  21 class NET_EXPORT_PRIVATE TCPLossAlgorithm : public LossDetectionInterface {
  22  public:
  23   // TCP retransmits after 3 nacks.
  24   static const QuicPacketCount kNumberOfNacksBeforeRetransmission = 3;
  25
  26   TCPLossAlgorithm();
  27   ~TCPLossAlgorithm() override {}
  28
  29   LossDetectionType GetLossDetectionType() const override;
  30
  31   // Uses nack counts to decide when packets are lost.
  32   SequenceNumberSet DetectLostPackets(
  33       const QuicUnackedPacketMap& unacked_packets,
  34       const QuicTime& time,
  35       QuicPacketSequenceNumber largest_observed,
  36       const RttStats& rtt_stats) override;
  37
  38   // Returns a non-zero value when the early retransmit timer is active.
  39   QuicTime GetLossTimeout() const override;
  40
  41  private:
  42   QuicTime loss_detection_timeout_;
  43
  44   DISALLOW_COPY_AND_ASSIGN(TCPLossAlgorithm);
  45 };
  46
  47 }  // namespace net
  48
  49 #endif  // NET_QUIC_CONGESTION_CONTROL_TCP_LOSS_ALGORITHM_H_