net/quic/quic_sustained_bandwidth_recorder.cc

   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 #include "net/quic/quic_sustained_bandwidth_recorder.h"
   6
   7 #include "base/logging.h"
   8 #include "net/quic/quic_bandwidth.h"
   9 #include "net/quic/quic_time.h"
  10
  11 namespace net {
  12
  13 QuicSustainedBandwidthRecorder::QuicSustainedBandwidthRecorder()
  14     : has_estimate_(false),
  15       is_recording_(false),
  16       bandwidth_estimate_recorded_during_slow_start_(false),
  17       bandwidth_estimate_(QuicBandwidth::Zero()),
  18       max_bandwidth_estimate_(QuicBandwidth::Zero()),
  19       max_bandwidth_timestamp_(0),
  20       start_time_(QuicTime::Zero()) {}
  21
  22 void QuicSustainedBandwidthRecorder::RecordEstimate(bool in_recovery,
  23                                                     bool in_slow_start,
  24                                                     QuicBandwidth bandwidth,
  25                                                     QuicTime estimate_time,
  26                                                     QuicWallTime wall_time,
  27                                                     QuicTime::Delta srtt) {
  28   if (in_recovery) {
  29     is_recording_ = false;
  30     DVLOG(1) << "Stopped recording at: " << estimate_time.ToDebuggingValue();
  31     return;
  32   }
  33
  34   if (!is_recording_) {
  35     // This is the first estimate of a new recording period.
  36     start_time_ = estimate_time;
  37     is_recording_ = true;
  38     DVLOG(1) << "Started recording at: " << start_time_.ToDebuggingValue();
  39     return;
  40   }
  41
  42   // If we have been recording for at least 3 * srtt, then record the latest
  43   // bandwidth estimate as a valid sustained bandwidth estimate.
  44   if (estimate_time.Subtract(start_time_) >= srtt.Multiply(3)) {
  45     has_estimate_ = true;
  46     bandwidth_estimate_recorded_during_slow_start_ = in_slow_start;
  47     bandwidth_estimate_ = bandwidth;
  48     DVLOG(1) << "New sustained bandwidth estimate (KBytes/s): "
  49              << bandwidth_estimate_.ToKBytesPerSecond();
  50   }
  51
  52   // Check for an increase in max bandwidth.
  53   if (bandwidth > max_bandwidth_estimate_) {
  54     max_bandwidth_estimate_ = bandwidth;
  55     max_bandwidth_timestamp_ = wall_time.ToUNIXSeconds();
  56     DVLOG(1) << "New max bandwidth estimate (KBytes/s): "
  57              << max_bandwidth_estimate_.ToKBytesPerSecond();
  58   }
  59 }
  60
  61 }  // namespace net