base/metrics/sample_map.h

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// SampleMap implements HistogramSamples interface. It is used by the
// SparseHistogram class to store samples.

#ifndef BASE_METRICS_SAMPLE_MAP_H_
#define BASE_METRICS_SAMPLE_MAP_H_

#include <map>

#include "base/compiler_specific.h"
#include "base/memory/scoped_ptr.h"
#include "base/metrics/histogram_base.h"
#include "base/metrics/histogram_samples.h"

namespace base {

class BASE_EXPORT SampleMap : public HistogramSamples {
 public:
  SampleMap();
  explicit SampleMap(uint64_t id);
  ~SampleMap() override;

  // HistogramSamples implementation:
  void Accumulate(HistogramBase::Sample value,
                  HistogramBase::Count count) override;
  HistogramBase::Count GetCount(HistogramBase::Sample value) const override;
  HistogramBase::Count TotalCount() const override;
  scoped_ptr<SampleCountIterator> Iterator() const override;

 protected:
  bool AddSubtractImpl(
      SampleCountIterator* iter,
      HistogramSamples::Operator op) override;  // |op| is ADD or SUBTRACT.

 private:
  std::map<HistogramBase::Sample, HistogramBase::Count> sample_counts_;

  DISALLOW_COPY_AND_ASSIGN(SampleMap);
};

class BASE_EXPORT SampleMapIterator : public SampleCountIterator {
 public:
  typedef std::map<HistogramBase::Sample, HistogramBase::Count>
      SampleToCountMap;

  explicit SampleMapIterator(const SampleToCountMap& sample_counts);
  ~SampleMapIterator() override;

  // SampleCountIterator implementation:
  bool Done() const override;
  void Next() override;
  void Get(HistogramBase::Sample* min,
           HistogramBase::Sample* max,
           HistogramBase::Count* count) const override;

 private:
  void SkipEmptyBuckets();

  SampleToCountMap::const_iterator iter_;
  const SampleToCountMap::const_iterator end_;
};

}  // namespace base

#endif  // BASE_METRICS_SAMPLE_MAP_H_