net/quic/congestion_control/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 max capacity of the channel.
   7 // We can only use packet pair that are sent out faster than the acctual
   8 // channel capacity.
   9 #ifndef NET_QUIC_CONGESTION_CONTROL_CHANNEL_ESTIMATOR_H_
  10 #define NET_QUIC_CONGESTION_CONTROL_CHANNEL_ESTIMATOR_H_
  11
  12 #include <list>
  13 #include <map>
  14
  15 #include "base/basictypes.h"
  16 #include "net/base/net_export.h"
  17 #include "net/quic/congestion_control/quic_max_sized_map.h"
  18 #include "net/quic/quic_bandwidth.h"
  19 #include "net/quic/quic_protocol.h"
  20 #include "net/quic/quic_time.h"
  21
  22 namespace net {
  23
  24 enum ChannelEstimateState {
  25   kChannelEstimateUnknown = 0,
  26   kChannelEstimateUncertain = 1,
  27   kChannelEstimateGood = 2
  28 };
  29
  30 class NET_EXPORT_PRIVATE ChannelEstimator {
  31  public:
  32   ChannelEstimator();
  33   ~ChannelEstimator();
  34
  35   // This method should be called each time we acquire a receive time for a
  36   // packet we previously sent.  It calculates deltas between consecutive
  37   // receive times, and may use that to update the channel bandwidth estimate.
  38   void OnAcknowledgedPacket(QuicPacketSequenceNumber sequence_number,
  39                             QuicByteCount packet_size,
  40                             QuicTime send_time,
  41                             QuicTime receive_time);
  42
  43   // Get the current estimated state and channel capacity.
  44   // Note: estimate will not be valid when kChannelEstimateUnknown is returned.
  45   ChannelEstimateState GetChannelEstimate(QuicBandwidth* estimate) const;
  46
  47  private:
  48   void UpdateFilter(QuicTime::Delta received_delta, QuicByteCount size_delta,
  49                     QuicPacketSequenceNumber sequence_number);
  50
  51   QuicPacketSequenceNumber last_sequence_number_;
  52   QuicTime last_send_time_;
  53   QuicTime last_receive_time_;
  54   QuicMaxSizedMap<QuicBandwidth, QuicPacketSequenceNumber>
  55       sorted_bitrate_estimates_;
  56
  57   DISALLOW_COPY_AND_ASSIGN(ChannelEstimator);
  58 };
  59
  60 }  // namespace net
  61 #endif  // NET_QUIC_CONGESTION_CONTROL_CHANNEL_ESTIMATOR_H_