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      1 // Copyright 2014 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 CC_BASE_ROLLING_TIME_DELTA_HISTORY_H_
      6 #define CC_BASE_ROLLING_TIME_DELTA_HISTORY_H_
      7 
      8 #include <deque>
      9 #include <set>
     10 
     11 #include "base/time/time.h"
     12 #include "cc/base/cc_export.h"
     13 
     14 namespace cc {
     15 
     16 // Stores a limited number of samples. When the maximum size is reached, each
     17 // insertion results in the deletion of the oldest remaining sample.
     18 class CC_EXPORT RollingTimeDeltaHistory {
     19  public:
     20   explicit RollingTimeDeltaHistory(size_t max_size);
     21 
     22   ~RollingTimeDeltaHistory();
     23 
     24   void InsertSample(base::TimeDelta time);
     25 
     26   void Clear();
     27 
     28   // Returns the smallest sample that is greater than or equal to the specified
     29   // percent of samples. If there aren't any samples, returns base::TimeDelta().
     30   base::TimeDelta Percentile(double percent) const;
     31 
     32  private:
     33   typedef std::multiset<base::TimeDelta> TimeDeltaMultiset;
     34 
     35   TimeDeltaMultiset sample_set_;
     36   std::deque<TimeDeltaMultiset::iterator> chronological_sample_deque_;
     37   size_t max_size_;
     38 
     39   DISALLOW_COPY_AND_ASSIGN(RollingTimeDeltaHistory);
     40 };
     41 
     42 }  // namespace cc
     43 
     44 #endif  // CC_BASE_ROLLING_TIME_DELTA_HISTORY_H_
     45