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#include "base/metrics/sample_map.h"
6
7#include "base/logging.h"
8#include "base/memory/ptr_util.h"
9#include "base/stl_util.h"
10
11namespace base {
12
13typedef HistogramBase::Count Count;
14typedef HistogramBase::Sample Sample;
15
16namespace {
17
18// An iterator for going through a SampleMap. The logic here is identical
19// to that of PersistentSampleMapIterator but with different data structures.
20// Changes here likely need to be duplicated there.
21class SampleMapIterator : public SampleCountIterator {
22 public:
23  typedef std::map<HistogramBase::Sample, HistogramBase::Count>
24      SampleToCountMap;
25
26  explicit SampleMapIterator(const SampleToCountMap& sample_counts);
27  ~SampleMapIterator() override;
28
29  // SampleCountIterator:
30  bool Done() const override;
31  void Next() override;
32  void Get(HistogramBase::Sample* min,
33           HistogramBase::Sample* max,
34           HistogramBase::Count* count) const override;
35
36 private:
37  void SkipEmptyBuckets();
38
39  SampleToCountMap::const_iterator iter_;
40  const SampleToCountMap::const_iterator end_;
41};
42
43SampleMapIterator::SampleMapIterator(const SampleToCountMap& sample_counts)
44    : iter_(sample_counts.begin()),
45      end_(sample_counts.end()) {
46  SkipEmptyBuckets();
47}
48
49SampleMapIterator::~SampleMapIterator() {}
50
51bool SampleMapIterator::Done() const {
52  return iter_ == end_;
53}
54
55void SampleMapIterator::Next() {
56  DCHECK(!Done());
57  ++iter_;
58  SkipEmptyBuckets();
59}
60
61void SampleMapIterator::Get(Sample* min, Sample* max, Count* count) const {
62  DCHECK(!Done());
63  if (min)
64    *min = iter_->first;
65  if (max)
66    *max = iter_->first + 1;
67  if (count)
68    *count = iter_->second;
69}
70
71void SampleMapIterator::SkipEmptyBuckets() {
72  while (!Done() && iter_->second == 0) {
73    ++iter_;
74  }
75}
76
77}  // namespace
78
79SampleMap::SampleMap() : SampleMap(0) {}
80
81SampleMap::SampleMap(uint64_t id) : HistogramSamples(id) {}
82
83SampleMap::~SampleMap() {}
84
85void SampleMap::Accumulate(Sample value, Count count) {
86  sample_counts_[value] += count;
87  IncreaseSum(static_cast<int64_t>(count) * value);
88  IncreaseRedundantCount(count);
89}
90
91Count SampleMap::GetCount(Sample value) const {
92  std::map<Sample, Count>::const_iterator it = sample_counts_.find(value);
93  if (it == sample_counts_.end())
94    return 0;
95  return it->second;
96}
97
98Count SampleMap::TotalCount() const {
99  Count count = 0;
100  for (const auto& entry : sample_counts_) {
101    count += entry.second;
102  }
103  return count;
104}
105
106std::unique_ptr<SampleCountIterator> SampleMap::Iterator() const {
107  return WrapUnique(new SampleMapIterator(sample_counts_));
108}
109
110bool SampleMap::AddSubtractImpl(SampleCountIterator* iter, Operator op) {
111  Sample min;
112  Sample max;
113  Count count;
114  for (; !iter->Done(); iter->Next()) {
115    iter->Get(&min, &max, &count);
116    if (min + 1 != max)
117      return false;  // SparseHistogram only supports bucket with size 1.
118
119    sample_counts_[min] += (op == HistogramSamples::ADD) ? count : -count;
120  }
121  return true;
122}
123
124}  // namespace base
125