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   virtual ~SampleVector();
  27
  28   // HistogramSamples implementation:
  29   virtual void Accumulate(HistogramBase::Sample value,
  30                           HistogramBase::Count count) OVERRIDE;
  31   virtual HistogramBase::Count GetCount(
  32       HistogramBase::Sample value) const OVERRIDE;
  33   virtual HistogramBase::Count TotalCount() const OVERRIDE;
  34   virtual scoped_ptr<SampleCountIterator> Iterator() const OVERRIDE;
  35
  36   // Get count of a specific bucket.
  37   HistogramBase::Count GetCountAtIndex(size_t bucket_index) const;
  38
  39  protected:
  40   virtual bool AddSubtractImpl(
  41       SampleCountIterator* iter,
  42       HistogramSamples::Operator op) OVERRIDE;  // |op| is ADD or SUBTRACT.
  43
  44   virtual size_t GetBucketIndex(HistogramBase::Sample value) const;
  45
  46  private:
  47   FRIEND_TEST_ALL_PREFIXES(HistogramTest, CorruptSampleCounts);
  48
  49   std::vector<HistogramBase::AtomicCount> counts_;
  50
  51   // Shares the same BucketRanges with Histogram object.
  52   const BucketRanges* const bucket_ranges_;
  53
  54   DISALLOW_COPY_AND_ASSIGN(SampleVector);
  55 };
  56
  57 class BASE_EXPORT_PRIVATE SampleVectorIterator : public SampleCountIterator {
  58  public:
  59   SampleVectorIterator(const std::vector<HistogramBase::AtomicCount>* counts,
  60                        const BucketRanges* bucket_ranges);
  61   virtual ~SampleVectorIterator();
  62
  63   // SampleCountIterator implementation:
  64   virtual bool Done() const OVERRIDE;
  65   virtual void Next() OVERRIDE;
  66   virtual void Get(HistogramBase::Sample* min,
  67                    HistogramBase::Sample* max,
  68                    HistogramBase::Count* count) const OVERRIDE;
  69
  70   // SampleVector uses predefined buckets, so iterator can return bucket index.
  71   virtual bool GetBucketIndex(size_t* index) const OVERRIDE;
  72
  73  private:
  74   void SkipEmptyBuckets();
  75
  76   const std::vector<HistogramBase::AtomicCount>* counts_;
  77   const BucketRanges* bucket_ranges_;
  78
  79   size_t index_;
  80 };
  81
  82 }  // namespace base
  83
  84 #endif  // BASE_METRICS_SAMPLE_VECTOR_H_