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
17namespace 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.
22class RateTracker {
23 public:
24  RateTracker(uint32_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(uint32_t interval_milliseconds) const;
31
32  // Computes the average rate over the rate tracker's recording interval
33  // of bucket_milliseconds * bucket_count.
34  double ComputeRate() const {
35    return ComputeRateForInterval(bucket_milliseconds_ *
36                                  static_cast<uint32_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 uint32_t Time() const;
53
54 private:
55  void EnsureInitialized();
56  size_t NextBucketIndex(size_t bucket_index) const;
57
58  const uint32_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  uint32_t bucket_start_time_milliseconds_;
64  uint32_t initialization_time_milliseconds_;
65};
66
67}  // namespace rtc
68
69#endif  // WEBRTC_BASE_RATETRACKER_H_
70