base/test/histogram_tester.cc

   1 // Copyright 2014 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/test/histogram_tester.h"
   6
   7 #include "base/metrics/histogram.h"
   8 #include "base/metrics/histogram_samples.h"
   9 #include "base/metrics/statistics_recorder.h"
  10 #include "base/stl_util.h"
  11 #include "testing/gtest/include/gtest/gtest.h"
  12
  13 namespace base {
  14
  15 HistogramTester::HistogramTester() {
  16   StatisticsRecorder::Initialize();  // Safe to call multiple times.
  17
  18   // Record any histogram data that exists when the object is created so it can
  19   // be subtracted later.
  20   StatisticsRecorder::Histograms histograms;
  21   StatisticsRecorder::GetSnapshot(std::string(), &histograms);
  22   for (size_t i = 0; i < histograms.size(); ++i) {
  23     histograms_snapshot_[histograms[i]->histogram_name()] =
  24         histograms[i]->SnapshotSamples().release();
  25   }
  26 }
  27
  28 HistogramTester::~HistogramTester() {
  29   STLDeleteValues(&histograms_snapshot_);
  30 }
  31
  32 void HistogramTester::ExpectUniqueSample(
  33     const std::string& name,
  34     base::HistogramBase::Sample sample,
  35     base::HistogramBase::Count expected_count) const {
  36   base::HistogramBase* histogram =
  37       base::StatisticsRecorder::FindHistogram(name);
  38   EXPECT_NE(static_cast<base::HistogramBase*>(NULL), histogram)
  39       << "Histogram \"" << name << "\" does not exist.";
  40
  41   if (histogram) {
  42     scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
  43     CheckBucketCount(name, sample, expected_count, *samples);
  44     CheckTotalCount(name, expected_count, *samples);
  45   }
  46 }
  47
  48 void HistogramTester::ExpectBucketCount(
  49     const std::string& name,
  50     base::HistogramBase::Sample sample,
  51     base::HistogramBase::Count expected_count) const {
  52   base::HistogramBase* histogram =
  53       base::StatisticsRecorder::FindHistogram(name);
  54   EXPECT_NE(static_cast<base::HistogramBase*>(NULL), histogram)
  55       << "Histogram \"" << name << "\" does not exist.";
  56
  57   if (histogram) {
  58     scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
  59     CheckBucketCount(name, sample, expected_count, *samples);
  60   }
  61 }
  62
  63 void HistogramTester::ExpectTotalCount(const std::string& name,
  64                                        base::HistogramBase::Count count) const {
  65   base::HistogramBase* histogram =
  66       base::StatisticsRecorder::FindHistogram(name);
  67   if (histogram) {
  68     scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
  69     CheckTotalCount(name, count, *samples);
  70   } else {
  71     // No histogram means there were zero samples.
  72     EXPECT_EQ(count, 0) << "Histogram \"" << name << "\" does not exist.";
  73   }
  74 }
  75
  76 std::vector<Bucket> HistogramTester::GetAllSamples(const std::string& name) {
  77   std::vector<Bucket> samples;
  78   scoped_ptr<HistogramSamples> snapshot =
  79       GetHistogramSamplesSinceCreation(name);
  80   for (auto it = snapshot->Iterator(); !it->Done(); it->Next()) {
  81     HistogramBase::Sample sample;
  82     HistogramBase::Count count;
  83     it->Get(&sample, nullptr, &count);
  84     samples.push_back(Bucket(sample, count));
  85   }
  86   return samples;
  87 }
  88
  89 scoped_ptr<HistogramSamples> HistogramTester::GetHistogramSamplesSinceCreation(
  90     const std::string& histogram_name) {
  91   HistogramBase* histogram = StatisticsRecorder::FindHistogram(histogram_name);
  92   if (!histogram)
  93     return scoped_ptr<HistogramSamples>();
  94   scoped_ptr<HistogramSamples> named_samples(histogram->SnapshotSamples());
  95   HistogramSamples* named_original_samples =
  96       histograms_snapshot_[histogram_name];
  97   if (named_original_samples)
  98     named_samples->Subtract(*named_original_samples);
  99   return named_samples.Pass();
 100 }
 101
 102 void HistogramTester::CheckBucketCount(
 103     const std::string& name,
 104     base::HistogramBase::Sample sample,
 105     base::HistogramBase::Count expected_count,
 106     const base::HistogramSamples& samples) const {
 107   int actual_count = samples.GetCount(sample);
 108   std::map<std::string, HistogramSamples*>::const_iterator histogram_data;
 109   histogram_data = histograms_snapshot_.find(name);
 110   if (histogram_data != histograms_snapshot_.end())
 111     actual_count -= histogram_data->second->GetCount(sample);
 112
 113   EXPECT_EQ(expected_count, actual_count)
 114       << "Histogram \"" << name
 115       << "\" does not have the right number of samples (" << expected_count
 116       << ") in the expected bucket (" << sample << "). It has (" << actual_count
 117       << ").";
 118 }
 119
 120 void HistogramTester::CheckTotalCount(
 121     const std::string& name,
 122     base::HistogramBase::Count expected_count,
 123     const base::HistogramSamples& samples) const {
 124   int actual_count = samples.TotalCount();
 125   std::map<std::string, HistogramSamples*>::const_iterator histogram_data;
 126   histogram_data = histograms_snapshot_.find(name);
 127   if (histogram_data != histograms_snapshot_.end())
 128     actual_count -= histogram_data->second->TotalCount();
 129
 130   EXPECT_EQ(expected_count, actual_count)
 131       << "Histogram \"" << name
 132       << "\" does not have the right total number of samples ("
 133       << expected_count << "). It has (" << actual_count << ").";
 134 }
 135
 136 bool Bucket::operator==(const Bucket& other) const {
 137   return min == other.min && count == other.count;
 138 }
 139
 140 void PrintTo(const Bucket& bucket, std::ostream* os) {
 141   *os << "Bucket " << bucket.min << ": " << bucket.count;
 142 }
 143
 144 }  // namespace base