1// Copyright (c) 2011 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#ifndef REMOTING_BASE_RUNNING_AVERAGE_H_
6#define REMOTING_BASE_RUNNING_AVERAGE_H_
7
8#include <deque>
9
10#include "base/basictypes.h"
11#include "base/synchronization/lock.h"
12
13namespace remoting {
14
15// Calculates the average of the most recent N recorded samples.
16// This is typically used to smooth out random variation in point samples
17// over bandwidth, frame rate, etc.
18class RunningAverage {
19 public:
20  // Constructs a helper to average over the |window_size| most recent samples.
21  explicit RunningAverage(int window_size);
22  virtual ~RunningAverage();
23
24  // Records a point sample.
25  void Record(int64 value);
26
27  // Returns the average over up to |window_size| of the most recent samples.
28  double Average();
29
30 private:
31  // Stores the desired window size, as size_t to avoid casting when comparing
32  // with the size of |data_points_|.
33  const size_t window_size_;
34
35  // Protects |data_points_| and |sum_|.
36  base::Lock lock_;
37
38  // Stores the |window_size| most recently recorded samples.
39  std::deque<int64> data_points_;
40
41  // Holds the sum of the samples in |data_points_|.
42  int64 sum_;
43
44  DISALLOW_COPY_AND_ASSIGN(RunningAverage);
45};
46
47}  // namespace remoting
48
49#endif  // REMOTING_BASE_RUNNING_AVERAGE_H_
50