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/sample_map.h"
  10 #include "base/metrics/statistics_recorder.h"
  11 #include "base/stl_util.h"
  12 #include "testing/gtest/include/gtest/gtest.h"
  13
  14 namespace base {
  15
  16 HistogramTester::HistogramTester() {
  17   StatisticsRecorder::Initialize();  // Safe to call multiple times.
  18
  19   // Record any histogram data that exists when the object is created so it can
  20   // be subtracted later.
  21   StatisticsRecorder::Histograms histograms;
  22   StatisticsRecorder::GetSnapshot(std::string(), &histograms);
  23   for (size_t i = 0; i < histograms.size(); ++i) {
  24     histograms_snapshot_[histograms[i]->histogram_name()] =
  25         histograms[i]->SnapshotSamples().release();
  26   }
  27 }
  28
  29 HistogramTester::~HistogramTester() {
  30   STLDeleteValues(&histograms_snapshot_);
  31 }
  32
  33 void HistogramTester::ExpectUniqueSample(
  34     const std::string& name,
  35     base::HistogramBase::Sample sample,
  36     base::HistogramBase::Count expected_count) const {
  37   base::HistogramBase* histogram =
  38       base::StatisticsRecorder::FindHistogram(name);
  39   EXPECT_NE(static_cast<base::HistogramBase*>(NULL), histogram)
  40       << "Histogram \"" << name << "\" does not exist.";
  41
  42   if (histogram) {
  43     scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
  44     CheckBucketCount(name, sample, expected_count, *samples);
  45     CheckTotalCount(name, expected_count, *samples);
  46   }
  47 }
  48
  49 void HistogramTester::ExpectBucketCount(
  50     const std::string& name,
  51     base::HistogramBase::Sample sample,
  52     base::HistogramBase::Count expected_count) const {
  53   base::HistogramBase* histogram =
  54       base::StatisticsRecorder::FindHistogram(name);
  55   EXPECT_NE(static_cast<base::HistogramBase*>(NULL), histogram)
  56       << "Histogram \"" << name << "\" does not exist.";
  57
  58   if (histogram) {
  59     scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
  60     CheckBucketCount(name, sample, expected_count, *samples);
  61   }
  62 }
  63
  64 void HistogramTester::ExpectTotalCount(const std::string& name,
  65                                        base::HistogramBase::Count count) const {
  66   base::HistogramBase* histogram =
  67       base::StatisticsRecorder::FindHistogram(name);
  68   if (histogram) {
  69     scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
  70     CheckTotalCount(name, count, *samples);
  71   } else {
  72     // No histogram means there were zero samples.
  73     EXPECT_EQ(count, 0) << "Histogram \"" << name << "\" does not exist.";
  74   }
  75 }
  76
  77 std::vector<Bucket> HistogramTester::GetAllSamples(
  78     const std::string& name) const {
  79   std::vector<Bucket> samples;
  80   scoped_ptr<HistogramSamples> snapshot =
  81       GetHistogramSamplesSinceCreation(name);
  82   if (snapshot) {
  83     for (auto it = snapshot->Iterator(); !it->Done(); it->Next()) {
  84       HistogramBase::Sample sample;
  85       HistogramBase::Count count;
  86       it->Get(&sample, nullptr, &count);
  87       samples.push_back(Bucket(sample, count));
  88     }
  89   }
  90   return samples;
  91 }
  92
  93 HistogramTester::CountsMap HistogramTester::GetTotalCountsForPrefix(
  94     const std::string& query) const {
  95   EXPECT_TRUE(query.find('.') != std::string::npos)
  96       << "|query| ought to contain at least one period, to avoid matching too"
  97       << " many histograms.";
  98
  99   // Find matches by using the prefix-matching logic built into GetSnapshot().
 100   StatisticsRecorder::Histograms query_matches;
 101   StatisticsRecorder::GetSnapshot(query, &query_matches);
 102
 103   CountsMap result;
 104   for (base::HistogramBase* histogram : query_matches) {
 105     scoped_ptr<HistogramSamples> new_samples =
 106         GetHistogramSamplesSinceCreation(histogram->histogram_name());
 107     // Omit unchanged histograms from the result.
 108     if (new_samples->TotalCount()) {
 109       result[histogram->histogram_name()] = new_samples->TotalCount();
 110     }
 111   }
 112   return result;
 113 }
 114
 115 scoped_ptr<HistogramSamples> HistogramTester::GetHistogramSamplesSinceCreation(
 116     const std::string& histogram_name) const {
 117   HistogramBase* histogram = StatisticsRecorder::FindHistogram(histogram_name);
 118   // Whether the histogram exists or not may not depend on the current test
 119   // calling this method, but rather on which tests ran before and possibly
 120   // generated a histogram or not (see http://crbug.com/473689). To provide a
 121   // response which is independent of the previously run tests, this method
 122   // creates empty samples in the absence of the histogram, rather than
 123   // returning null.
 124   if (!histogram)
 125     return scoped_ptr<HistogramSamples>(new SampleMap);
 126   scoped_ptr<HistogramSamples> named_samples(histogram->SnapshotSamples());
 127   auto original_samples_it = histograms_snapshot_.find(histogram_name);
 128   if (original_samples_it != histograms_snapshot_.end())
 129     named_samples->Subtract(*original_samples_it->second);
 130   return named_samples.Pass();
 131 }
 132
 133 void HistogramTester::CheckBucketCount(
 134     const std::string& name,
 135     base::HistogramBase::Sample sample,
 136     base::HistogramBase::Count expected_count,
 137     const base::HistogramSamples& samples) const {
 138   int actual_count = samples.GetCount(sample);
 139   std::map<std::string, HistogramSamples*>::const_iterator histogram_data;
 140   histogram_data = histograms_snapshot_.find(name);
 141   if (histogram_data != histograms_snapshot_.end())
 142     actual_count -= histogram_data->second->GetCount(sample);
 143
 144   EXPECT_EQ(expected_count, actual_count)
 145       << "Histogram \"" << name
 146       << "\" does not have the right number of samples (" << expected_count
 147       << ") in the expected bucket (" << sample << "). It has (" << actual_count
 148       << ").";
 149 }
 150
 151 void HistogramTester::CheckTotalCount(
 152     const std::string& name,
 153     base::HistogramBase::Count expected_count,
 154     const base::HistogramSamples& samples) const {
 155   int actual_count = samples.TotalCount();
 156   std::map<std::string, HistogramSamples*>::const_iterator histogram_data;
 157   histogram_data = histograms_snapshot_.find(name);
 158   if (histogram_data != histograms_snapshot_.end())
 159     actual_count -= histogram_data->second->TotalCount();
 160
 161   EXPECT_EQ(expected_count, actual_count)
 162       << "Histogram \"" << name
 163       << "\" does not have the right total number of samples ("
 164       << expected_count << "). It has (" << actual_count << ").";
 165 }
 166
 167 bool Bucket::operator==(const Bucket& other) const {
 168   return min == other.min && count == other.count;
 169 }
 170
 171 void PrintTo(const Bucket& bucket, std::ostream* os) {
 172   *os << "Bucket " << bucket.min << ": " << bucket.count;
 173 }
 174
 175 }  // namespace base