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_RATE_COUNTER_H_ 6 #define REMOTING_BASE_RATE_COUNTER_H_ 7 8 #include <queue> 9 #include <utility> 10 11 #include "base/basictypes.h" 12 #include "base/threading/non_thread_safe.h" 13 #include "base/time/time.h" 14 15 namespace remoting { 16 17 // Measures average rate per second of a sequence of point rate samples 18 // over a specified time window. This can be used to measure bandwidth, frame 19 // rates, etc. 20 class RateCounter : public base::NonThreadSafe { 21 public: 22 // Constructs a rate counter over the specified |time_window|. 23 explicit RateCounter(base::TimeDelta time_window); 24 virtual ~RateCounter(); 25 26 // Records a point event count to include in the rate. 27 void Record(int64 value); 28 29 // Returns the rate-per-second of values recorded over the time window. 30 // Note that rates reported before |time_window| has elapsed are not accurate. 31 double Rate(); 32 33 // Overrides the current time for testing. 34 void SetCurrentTimeForTest(base::Time current_time); 35 36 private: 37 // Type used to store data points with timestamps. 38 typedef std::pair<base::Time, int64> DataPoint; 39 40 // Removes data points more than |time_window| older than |current_time|. 41 void EvictOldDataPoints(base::Time current_time); 42 43 // Returns the current time specified for test, if set, or base::Time::Now(). 44 base::Time CurrentTime() const; 45 46 // Time window over which to calculate the rate. 47 const base::TimeDelta time_window_; 48 49 // Queue containing data points in the order in which they were recorded. 50 std::queue<DataPoint> data_points_; 51 52 // Sum of values in |data_points_|. 53 int64 sum_; 54 55 // If set, used to calculate the running average, in place of Now(). 56 base::Time current_time_for_test_; 57 58 DISALLOW_COPY_AND_ASSIGN(RateCounter); 59 }; 60 61 } // namespace remoting 62 63 #endif // REMOTING_BASE_RATE_COUNTER_H_ 64