remoting/base/running_average.h

   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
  13 namespace 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.
  18 class 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_