media/base/moving_average.h

   1 // Copyright 2015 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 MEDIA_BASE_MOVING_AVERAGE_H_
   6 #define MEDIA_BASE_MOVING_AVERAGE_H_
   7
   8 #include <vector>
   9
  10 #include "base/time/time.h"
  11 #include "media/base/media_export.h"
  12
  13 namespace media {
  14
  15 // Simple class for calculating a moving average of fixed size.
  16 class MEDIA_EXPORT MovingAverage {
  17  public:
  18   // Creates a MovingAverage instance with space for |depth| samples.
  19   explicit MovingAverage(size_t depth);
  20   ~MovingAverage();
  21
  22   // Adds a new sample to the average; replaces the oldest sample if |depth_|
  23   // has been exceeded.  Updates |total_| to the new sum of values.
  24   void AddSample(base::TimeDelta sample);
  25
  26   // Returns the current average of all held samples.
  27   base::TimeDelta Average() const;
  28
  29   // Resets the state of the class to its initial post-construction state.
  30   void Reset();
  31
  32   size_t count() const { return count_; }
  33
  34  private:
  35   // Maximum number of elements allowed in the average.
  36   const size_t depth_;
  37
  38   // Number of elements seen thus far.
  39   uint64_t count_;
  40
  41   std::vector<base::TimeDelta> samples_;
  42   base::TimeDelta total_;
  43
  44   DISALLOW_COPY_AND_ASSIGN(MovingAverage);
  45 };
  46
  47 }  // namespace media
  48
  49 #endif  // MEDIA_BASE_MOVING_AVERAGE_H_