Line data    Source code

       1             : /*
       2             :  *  Copyright 2015 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             : 
      11             : #ifndef WEBRTC_BASE_RATETRACKER_H_
      12             : #define WEBRTC_BASE_RATETRACKER_H_
      13             : 
      14             : #include <stdlib.h>
      15             : #include "webrtc/base/basictypes.h"
      16             : 
      17             : namespace rtc {
      18             : 
      19             : // Computes units per second over a given interval by tracking the units over
      20             : // each bucket of a given size and calculating the instantaneous rate assuming
      21             : // that over each bucket the rate was constant.
      22             : class RateTracker {
      23             :  public:
      24             :   RateTracker(int64_t bucket_milliseconds, size_t bucket_count);
      25             :   virtual ~RateTracker();
      26             : 
      27             :   // Computes the average rate over the most recent interval_milliseconds,
      28             :   // or if the first sample was added within this period, computes the rate
      29             :   // since the first sample was added.
      30             :   double ComputeRateForInterval(int64_t interval_milliseconds) const;
      31             : 
      32             :   // Computes the average rate over the rate tracker's recording interval
      33             :   // of bucket_milliseconds * bucket_count.
      34           0 :   double ComputeRate() const {
      35           0 :     return ComputeRateForInterval(bucket_milliseconds_ *
      36           0 :                                   static_cast<int64_t>(bucket_count_));
      37             :   }
      38             : 
      39             :   // Computes the average rate since the first sample was added to the
      40             :   // rate tracker.
      41             :   double ComputeTotalRate() const;
      42             : 
      43             :   // The total number of samples added.
      44             :   size_t TotalSampleCount() const;
      45             : 
      46             :   // Reads the current time in order to determine the appropriate bucket for
      47             :   // these samples, and increments the count for that bucket by sample_count.
      48             :   void AddSamples(size_t sample_count);
      49             : 
      50             :  protected:
      51             :   // overrideable for tests
      52             :   virtual int64_t Time() const;
      53             : 
      54             :  private:
      55             :   void EnsureInitialized();
      56             :   size_t NextBucketIndex(size_t bucket_index) const;
      57             : 
      58             :   const int64_t bucket_milliseconds_;
      59             :   const size_t bucket_count_;
      60             :   size_t* sample_buckets_;
      61             :   size_t total_sample_count_;
      62             :   size_t current_bucket_;
      63             :   int64_t bucket_start_time_milliseconds_;
      64             :   int64_t initialization_time_milliseconds_;
      65             : };
      66             : 
      67             : }  // namespace rtc
      68             : 
      69             : #endif  // WEBRTC_BASE_RATETRACKER_H_