1 // Copyright (c) 2012 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 BASE_METRICS_HISTOGRAM_SAMPLES_H_ 6 #define BASE_METRICS_HISTOGRAM_SAMPLES_H_ 7 8 #include "base/basictypes.h" 9 #include "base/metrics/histogram_base.h" 10 #include "base/memory/scoped_ptr.h" 11 12 class Pickle; 13 class PickleIterator; 14 15 namespace base { 16 17 class SampleCountIterator; 18 19 // HistogramSamples is a container storing all samples of a histogram. 20 class BASE_EXPORT HistogramSamples { 21 public: 22 HistogramSamples(); 23 virtual ~HistogramSamples(); 24 25 virtual void Accumulate(HistogramBase::Sample value, 26 HistogramBase::Count count) = 0; 27 virtual HistogramBase::Count GetCount(HistogramBase::Sample value) const = 0; 28 virtual HistogramBase::Count TotalCount() const = 0; 29 30 virtual void Add(const HistogramSamples& other); 31 32 // Add from serialized samples. 33 virtual bool AddFromPickle(PickleIterator* iter); 34 35 virtual void Subtract(const HistogramSamples& other); 36 37 virtual scoped_ptr<SampleCountIterator> Iterator() const = 0; 38 virtual bool Serialize(Pickle* pickle) const; 39 40 // Accessor fuctions. sum()41 int64 sum() const { return sum_; } redundant_count()42 HistogramBase::Count redundant_count() const { 43 return subtle::NoBarrier_Load(&redundant_count_); 44 } 45 46 protected: 47 // Based on |op| type, add or subtract sample counts data from the iterator. 48 enum Operator { ADD, SUBTRACT }; 49 virtual bool AddSubtractImpl(SampleCountIterator* iter, Operator op) = 0; 50 51 void IncreaseSum(int64 diff); 52 void IncreaseRedundantCount(HistogramBase::Count diff); 53 54 private: 55 int64 sum_; 56 57 // |redundant_count_| helps identify memory corruption. It redundantly stores 58 // the total number of samples accumulated in the histogram. We can compare 59 // this count to the sum of the counts (TotalCount() function), and detect 60 // problems. Note, depending on the implementation of different histogram 61 // types, there might be races during histogram accumulation and snapshotting 62 // that we choose to accept. In this case, the tallies might mismatch even 63 // when no memory corruption has happened. 64 HistogramBase::AtomicCount redundant_count_; 65 }; 66 67 class BASE_EXPORT SampleCountIterator { 68 public: 69 virtual ~SampleCountIterator(); 70 71 virtual bool Done() const = 0; 72 virtual void Next() = 0; 73 74 // Get the sample and count at current position. 75 // |min| |max| and |count| can be NULL if the value is not of interest. 76 // Requires: !Done(); 77 virtual void Get(HistogramBase::Sample* min, 78 HistogramBase::Sample* max, 79 HistogramBase::Count* count) const = 0; 80 81 // Get the index of current histogram bucket. 82 // For histograms that don't use predefined buckets, it returns false. 83 // Requires: !Done(); 84 virtual bool GetBucketIndex(size_t* index) const; 85 }; 86 87 } // namespace base 88 89 #endif // BASE_METRICS_HISTOGRAM_SAMPLES_H_ 90