Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
       3             :  *
       4             :  *  Use of this source code is governed by a BSD-style license
       5             :  *  that can be found in the LICENSE file in the root of the source
       6             :  *  tree. An additional intellectual property rights grant can be found
       7             :  *  in the file PATENTS.  All contributing project authors may
       8             :  *  be found in the AUTHORS file in the root of the source tree.
       9             :  */
      10             : #ifndef WEBRTC_MODULES_CONGESTION_CONTROLLER_MEDIAN_SLOPE_ESTIMATOR_H_
      11             : #define WEBRTC_MODULES_CONGESTION_CONTROLLER_MEDIAN_SLOPE_ESTIMATOR_H_
      12             : 
      13             : #include <stddef.h>
      14             : #include <stdint.h>
      15             : 
      16             : #include <list>
      17             : #include <vector>
      18             : 
      19             : #include "webrtc/base/constructormagic.h"
      20             : #include "webrtc/base/numerics/percentile_filter.h"
      21             : 
      22             : namespace webrtc {
      23             : 
      24             : class MedianSlopeEstimator {
      25             :  public:
      26             :   // |window_size| is the number of points required to compute a trend line.
      27             :   // |threshold_gain| is used to scale the trendline slope for comparison to
      28             :   // the old threshold. Once the old estimator has been removed (or the
      29             :   // thresholds been merged into the estimators), we can just set the
      30             :   // threshold instead of setting a gain.
      31             :   MedianSlopeEstimator(size_t window_size, double threshold_gain);
      32             :   ~MedianSlopeEstimator();
      33             : 
      34             :   // Update the estimator with a new sample. The deltas should represent deltas
      35             :   // between timestamp groups as defined by the InterArrival class.
      36             :   void Update(double recv_delta_ms,
      37             :               double send_delta_ms,
      38             :               int64_t arrival_time_ms);
      39             : 
      40             :   // Returns the estimated trend k multiplied by some gain.
      41             :   // 0 < k < 1   ->  the delay increases, queues are filling up
      42             :   //   k == 0    ->  the delay does not change
      43             :   //   k <  0    ->  the delay decreases, queues are being emptied
      44           0 :   double trendline_slope() const { return trendline_ * threshold_gain_; }
      45             : 
      46             :   // Returns the number of deltas which the current estimator state is based on.
      47           0 :   unsigned int num_of_deltas() const { return num_of_deltas_; }
      48             : 
      49             :  private:
      50           0 :   struct DelayInfo {
      51           0 :     DelayInfo(int64_t time, double delay, size_t slope_count)
      52           0 :         : time(time), delay(delay) {
      53           0 :       slopes.reserve(slope_count);
      54           0 :     }
      55             :     int64_t time;
      56             :     double delay;
      57             :     std::vector<double> slopes;
      58             :   };
      59             :   // Parameters.
      60             :   const size_t window_size_;
      61             :   const double threshold_gain_;
      62             :   // Used by the existing threshold.
      63             :   unsigned int num_of_deltas_;
      64             :   // Theil-Sen robust line fitting
      65             :   double accumulated_delay_;
      66             :   std::list<DelayInfo> delay_hist_;
      67             :   PercentileFilter<double> median_filter_;
      68             :   double trendline_;
      69             : 
      70             :   RTC_DISALLOW_COPY_AND_ASSIGN(MedianSlopeEstimator);
      71             : };
      72             : }  // namespace webrtc
      73             : 
      74             : #endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_MEDIAN_SLOPE_ESTIMATOR_H_