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      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 <stddef.h>
     12 #include <stdint.h>
     13 
     14 #include <memory>
     15 #include <vector>
     16 
     17 #include "base/compiler_specific.h"
     18 #include "base/gtest_prod_util.h"
     19 #include "base/macros.h"
     20 #include "base/metrics/histogram_base.h"
     21 #include "base/metrics/histogram_samples.h"
     22 
     23 namespace base {
     24 
     25 class BucketRanges;
     26 
     27 class BASE_EXPORT SampleVector : public HistogramSamples {
     28  public:
     29   explicit SampleVector(const BucketRanges* bucket_ranges);
     30   SampleVector(uint64_t id, const BucketRanges* bucket_ranges);
     31   SampleVector(uint64_t id,
     32                HistogramBase::AtomicCount* counts,
     33                size_t counts_size,
     34                Metadata* meta,
     35                const BucketRanges* bucket_ranges);
     36   ~SampleVector() override;
     37 
     38   // HistogramSamples implementation:
     39   void Accumulate(HistogramBase::Sample value,
     40                   HistogramBase::Count count) override;
     41   HistogramBase::Count GetCount(HistogramBase::Sample value) const override;
     42   HistogramBase::Count TotalCount() const override;
     43   std::unique_ptr<SampleCountIterator> Iterator() const override;
     44 
     45   // Get count of a specific bucket.
     46   HistogramBase::Count GetCountAtIndex(size_t bucket_index) const;
     47 
     48  protected:
     49   bool AddSubtractImpl(
     50       SampleCountIterator* iter,
     51       HistogramSamples::Operator op) override;  // |op| is ADD or SUBTRACT.
     52 
     53   virtual size_t GetBucketIndex(HistogramBase::Sample value) const;
     54 
     55  private:
     56   FRIEND_TEST_ALL_PREFIXES(HistogramTest, CorruptSampleCounts);
     57   FRIEND_TEST_ALL_PREFIXES(SharedHistogramTest, CorruptSampleCounts);
     58 
     59   // In the case where this class manages the memory, here it is.
     60   std::vector<HistogramBase::AtomicCount> local_counts_;
     61 
     62   // These are raw pointers rather than objects for flexibility. The actual
     63   // memory is either managed by local_counts_ above or by an external object
     64   // and passed in directly.
     65   HistogramBase::AtomicCount* counts_;
     66   size_t counts_size_;
     67 
     68   // Shares the same BucketRanges with Histogram object.
     69   const BucketRanges* const bucket_ranges_;
     70 
     71   DISALLOW_COPY_AND_ASSIGN(SampleVector);
     72 };
     73 
     74 class BASE_EXPORT SampleVectorIterator : public SampleCountIterator {
     75  public:
     76   SampleVectorIterator(const std::vector<HistogramBase::AtomicCount>* counts,
     77                        const BucketRanges* bucket_ranges);
     78   SampleVectorIterator(const HistogramBase::AtomicCount* counts,
     79                        size_t counts_size,
     80                        const BucketRanges* bucket_ranges);
     81   ~SampleVectorIterator() override;
     82 
     83   // SampleCountIterator implementation:
     84   bool Done() const override;
     85   void Next() override;
     86   void Get(HistogramBase::Sample* min,
     87            HistogramBase::Sample* max,
     88            HistogramBase::Count* count) const override;
     89 
     90   // SampleVector uses predefined buckets, so iterator can return bucket index.
     91   bool GetBucketIndex(size_t* index) const override;
     92 
     93  private:
     94   void SkipEmptyBuckets();
     95 
     96   const HistogramBase::AtomicCount* counts_;
     97   size_t counts_size_;
     98   const BucketRanges* bucket_ranges_;
     99 
    100   size_t index_;
    101 };
    102 
    103 }  // namespace base
    104 
    105 #endif  // BASE_METRICS_SAMPLE_VECTOR_H_
    106