base/metrics/sample_vector.h

   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 // SampleVector implements HistogramSamples interface. It is used by all
   6 // Histogram based classes to store samples.
   7
   8 #ifndef BASE_METRICS_SAMPLE_VECTOR_H_
   9 #define BASE_METRICS_SAMPLE_VECTOR_H_
  10
  11 #include <vector>
  12
  13 #include "base/compiler_specific.h"
  14 #include "base/gtest_prod_util.h"
  15 #include "base/memory/scoped_ptr.h"
  16 #include "base/metrics/histogram_base.h"
  17 #include "base/metrics/histogram_samples.h"
  18
  19 namespace base {
  20
  21 class BucketRanges;
  22
  23 class BASE_EXPORT_PRIVATE SampleVector : public HistogramSamples {
  24  public:
  25   explicit SampleVector(const BucketRanges* bucket_ranges);
  26   ~SampleVector() override;
  27
  28   // HistogramSamples implementation:
  29   void Accumulate(HistogramBase::Sample value,
  30                   HistogramBase::Count count) override;
  31   HistogramBase::Count GetCount(HistogramBase::Sample value) const override;
  32   HistogramBase::Count TotalCount() const override;
  33   scoped_ptr<SampleCountIterator> Iterator() const override;
  34
  35   // Get count of a specific bucket.
  36   HistogramBase::Count GetCountAtIndex(size_t bucket_index) const;
  37
  38  protected:
  39   bool AddSubtractImpl(
  40       SampleCountIterator* iter,
  41       HistogramSamples::Operator op) override;  // |op| is ADD or SUBTRACT.
  42
  43   virtual size_t GetBucketIndex(HistogramBase::Sample value) const;
  44
  45  private:
  46   FRIEND_TEST_ALL_PREFIXES(HistogramTest, CorruptSampleCounts);
  47
  48   std::vector<HistogramBase::AtomicCount> counts_;
  49
  50   // Shares the same BucketRanges with Histogram object.
  51   const BucketRanges* const bucket_ranges_;
  52
  53   DISALLOW_COPY_AND_ASSIGN(SampleVector);
  54 };
  55
  56 class BASE_EXPORT_PRIVATE SampleVectorIterator : public SampleCountIterator {
  57  public:
  58   SampleVectorIterator(const std::vector<HistogramBase::AtomicCount>* counts,
  59                        const BucketRanges* bucket_ranges);
  60   ~SampleVectorIterator() override;
  61
  62   // SampleCountIterator implementation:
  63   bool Done() const override;
  64   void Next() override;
  65   void Get(HistogramBase::Sample* min,
  66            HistogramBase::Sample* max,
  67            HistogramBase::Count* count) const override;
  68
  69   // SampleVector uses predefined buckets, so iterator can return bucket index.
  70   bool GetBucketIndex(size_t* index) const override;
  71
  72  private:
  73   void SkipEmptyBuckets();
  74
  75   const std::vector<HistogramBase::AtomicCount>* counts_;
  76   const BucketRanges* bucket_ranges_;
  77
  78   size_t index_;
  79 };
  80
  81 }  // namespace base
  82
  83 #endif  // BASE_METRICS_SAMPLE_VECTOR_H_