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 // RunningAverage defined in this file is used to generate statistics for
   6 // bandwidth, latency and other performance metrics for remoting. Usually
   7 // this data comes in as a stream and fluctuates a lot. They are processed by
   8 // this class to generate a more stable value by taking average within a
   9 // window of data points.
  10
  11 // All classes defined are thread-safe.
  12
  13 #ifndef REMOTING_BASE_RUNNING_AVERAGE_H_
  14 #define REMOTING_BASE_RUNNING_AVERAGE_H_
  15
  16 #include <deque>
  17
  18 #include "base/basictypes.h"
  19 #include "base/synchronization/lock.h"
  20
  21 namespace remoting {
  22
  23 class RunningAverage {
  24  public:
  25   // Construct a running average counter for a specific window size. The
  26   // |windows_size| most recent values are kept and the average is reported.
  27   explicit RunningAverage(int window_size);
  28
  29   virtual ~RunningAverage();
  30
  31   // Record the provided data point.
  32   void Record(int64 value);
  33
  34   // Return the average of data points in the last window.
  35   double Average();
  36
  37  private:
  38   // Size of the window. This is of type size_t to avoid casting when comparing
  39   // with the size of |data_points_|.
  40   size_t window_size_;
  41
  42   // Protects |data_points_| and |sum_|.
  43   base::Lock lock_;
  44
  45   // Keep the values of all the data points.
  46   std::deque<int64> data_points_;
  47
  48   // Sum of values in |data_points_|.
  49   int64 sum_;
  50
  51   DISALLOW_COPY_AND_ASSIGN(RunningAverage);
  52 };
  53
  54 }  // namespace remoting
  55
  56 #endif  // REMOTING_BASE_RUNNING_AVERAGE_H_