1 // Copyright 2013 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 CONTENT_BROWSER_DOWNLOAD_RATE_ESTIMATOR_H_ 6 #define CONTENT_BROWSER_DOWNLOAD_RATE_ESTIMATOR_H_ 7 8 #include <string> 9 #include <vector> 10 11 #include "base/basictypes.h" 12 #include "base/time/time.h" 13 #include "content/common/content_export.h" 14 15 namespace content { 16 17 // RateEstimator generates rate estimates based on recent activity. 18 // 19 // Internally it uses a fixed-size ring buffer, and develops estimates 20 // based on a small sliding window of activity. 21 class CONTENT_EXPORT RateEstimator { 22 public: 23 RateEstimator(); 24 RateEstimator(base::TimeDelta bucket_time, 25 size_t num_buckets, 26 base::TimeTicks now); 27 ~RateEstimator(); 28 29 // Increment the counter by |count|. The first variant uses the current time, 30 // the second variant provides the time that |count| is observed. 31 void Increment(uint32 count); 32 void Increment(uint32 count, base::TimeTicks now); 33 34 // Get a rate estimate, in terms of counts/second. The first variant uses the 35 // current time, the second variant provides the time. 36 uint64 GetCountPerSecond() const; 37 uint64 GetCountPerSecond(base::TimeTicks now) const; 38 39 private: 40 void ClearOldBuckets(base::TimeTicks now); 41 void ResetBuckets(base::TimeTicks now); 42 43 std::vector<uint32> history_; 44 base::TimeDelta bucket_time_; 45 size_t oldest_index_; 46 size_t bucket_count_; 47 base::TimeTicks oldest_time_; 48 }; 49 50 } // namespace content 51 52 #endif // CONTENT_BROWSER_DOWNLOAD_RATE_ESTIMATOR_H_ 53
