net/quic/congestion_control/available_channel_estimator.h

   1 // Copyright (c) 2013 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 // Based on the inter arrival time of the received packets relative to the time
   6 // those packets where sent we can estimate the available capacity of the
   7 // channel.
   8 // We can only use packet trains that are sent out faster than the acctual
   9 // available channel capacity.
  10 // Note 1: this is intended to be a temporary class created when you send out a
  11 // channel probing burst. Once the last packet have arrived you ask it for an
  12 // estimate.
  13 // Note 2: During this phase we should not update the overuse detector.
  14 #ifndef NET_QUIC_CONGESTION_CONTROL_AVAILABLE_CHANNEL_ESTIMATOR_H_
  15 #define NET_QUIC_CONGESTION_CONTROL_AVAILABLE_CHANNEL_ESTIMATOR_H_
  16
  17 #include "base/basictypes.h"
  18 #include "net/base/net_export.h"
  19 #include "net/quic/quic_bandwidth.h"
  20 #include "net/quic/quic_protocol.h"
  21 #include "net/quic/quic_time.h"
  22
  23 namespace net {
  24
  25 enum NET_EXPORT_PRIVATE AvailableChannelEstimateState {
  26   kAvailableChannelEstimateUnknown = 0,
  27   kAvailableChannelEstimateUncertain = 1,
  28   kAvailableChannelEstimateGood = 2,
  29   kAvailableChannelEstimateSenderLimited = 3,
  30 };
  31
  32 class NET_EXPORT_PRIVATE AvailableChannelEstimator {
  33  public:
  34   explicit AvailableChannelEstimator(
  35       QuicPacketSequenceNumber first_sequence_number,
  36       QuicTime first_send_time,
  37       QuicTime first_receive_time);
  38
  39   // Update the statistics with each receive time, for every packet we get a
  40   // feedback message for.
  41   void OnIncomingFeedback(QuicPacketSequenceNumber sequence_number,
  42                           QuicByteCount packet_size,
  43                           QuicTime sent_time,
  44                           QuicTime receive_time);
  45
  46   // Get the current estimated available channel capacity.
  47   // bandwidth_estimate is invalid if kAvailableChannelEstimateUnknown
  48   // is returned.
  49   AvailableChannelEstimateState GetAvailableChannelEstimate(
  50       QuicBandwidth* bandwidth_estimate) const;
  51
  52  private:
  53   const QuicPacketSequenceNumber first_sequence_number_;
  54   const QuicTime first_send_time_;
  55   const QuicTime first_receive_time_;
  56   QuicPacketSequenceNumber last_incorporated_sequence_number_;
  57   QuicTime last_time_sent_;
  58   QuicTime last_receive_time_;
  59   int number_of_sequence_numbers_;
  60   QuicByteCount received_bytes_;
  61 };
  62
  63 }  // namespace net
  64 #endif  // NET_QUIC_CONGESTION_CONTROL_AVAILABLE_CHANNEL_ESTIMATOR_H_