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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// RateCounter is defined to measure average rate over a given time window.
// Rate is reported as the sum of values recorded divided by the time window.
// This can be used for measuring bandwidth, bitrate, etc.
// This class is thread-safe.
#ifndef REMOTING_BASE_RATE_COUNTER_H_
#define REMOTING_BASE_RATE_COUNTER_H_
#include <queue>
#include <utility>
#include "base/basictypes.h"
#include "base/synchronization/lock.h"
#include "base/time.h"
namespace remoting {
class RateCounter {
public:
// Construct a counter for a specific time window.
RateCounter(base::TimeDelta time_window);
virtual ~RateCounter();
// Record the data point.
void Record(int64 value);
// Report the rate recorded. At the beginning of recording the numbers before
// |time_window| is reached the reported rate will not be accurate.
double Rate();
private:
// Helper function to evict old data points.
void Evict(base::Time current_time);
// A data point consists of a timestamp and a data value.
typedef std::pair<base::Time, int64> DataPoint;
// Duration of the time window.
base::TimeDelta time_window_;
// Protects |data_points_| and |sum_|.
base::Lock lock_;
// Keep the values of all the data points in a queue.
std::queue<DataPoint> data_points_;
// Sum of values in |data_points_|.
int64 sum_;
DISALLOW_COPY_AND_ASSIGN(RateCounter);
};
} // namespace remoting
#endif // REMOTING_BASE_RATE_COUNTER_H_
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