88 lines
2.8 KiB
C++
88 lines
2.8 KiB
C++
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_METRICS_HISTOGRAM_SAMPLES_H_
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#define BASE_METRICS_HISTOGRAM_SAMPLES_H_
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#include "base/basictypes.h"
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#include "base/metrics/histogram_base.h"
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#include "base/memory/scoped_ptr.h"
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class Pickle;
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class PickleIterator;
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namespace base {
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class SampleCountIterator;
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// HistogramSamples is a container storing all samples of a histogram.
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class BASE_EXPORT HistogramSamples {
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public:
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HistogramSamples();
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virtual ~HistogramSamples();
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virtual void Accumulate(HistogramBase::Sample value,
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HistogramBase::Count count) = 0;
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virtual HistogramBase::Count GetCount(HistogramBase::Sample value) const = 0;
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virtual HistogramBase::Count TotalCount() const = 0;
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virtual void Add(const HistogramSamples& other);
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// Add from serialized samples.
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virtual bool AddFromPickle(PickleIterator* iter);
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virtual void Subtract(const HistogramSamples& other);
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virtual scoped_ptr<SampleCountIterator> Iterator() const = 0;
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virtual bool Serialize(Pickle* pickle) const;
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// Accessor fuctions.
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int64 sum() const { return sum_; }
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HistogramBase::Count redundant_count() const { return redundant_count_; }
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protected:
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// Based on |op| type, add or subtract sample counts data from the iterator.
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enum Operator { ADD, SUBTRACT };
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virtual bool AddSubtractImpl(SampleCountIterator* iter, Operator op) = 0;
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void IncreaseSum(int64 diff);
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void IncreaseRedundantCount(HistogramBase::Count diff);
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private:
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int64 sum_;
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// |redundant_count_| helps identify memory corruption. It redundantly stores
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// the total number of samples accumulated in the histogram. We can compare
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// this count to the sum of the counts (TotalCount() function), and detect
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// problems. Note, depending on the implementation of different histogram
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// types, there might be races during histogram accumulation and snapshotting
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// that we choose to accept. In this case, the tallies might mismatch even
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// when no memory corruption has happened.
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HistogramBase::Count redundant_count_;
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};
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class BASE_EXPORT SampleCountIterator {
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public:
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virtual ~SampleCountIterator();
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virtual bool Done() const = 0;
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virtual void Next() = 0;
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// Get the sample and count at current position.
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// |min| |max| and |count| can be NULL if the value is not of interest.
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// Requires: !Done();
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virtual void Get(HistogramBase::Sample* min,
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HistogramBase::Sample* max,
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HistogramBase::Count* count) const = 0;
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// Get the index of current histogram bucket.
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// For histograms that don't use predefined buckets, it returns false.
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// Requires: !Done();
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virtual bool GetBucketIndex(size_t* index) const;
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};
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} // namespace base
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#endif // BASE_METRICS_HISTOGRAM_SAMPLES_H_
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