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// Copyright 2014 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.
#include "base/test/histogram_tester.h"
#include <stddef.h>
#include "base/metrics/histogram.h"
#include "base/metrics/histogram_samples.h"
#include "base/metrics/metrics_hashes.h"
#include "base/metrics/sample_map.h"
#include "base/metrics/statistics_recorder.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace base {
HistogramTester::HistogramTester() {
StatisticsRecorder::Initialize(); // Safe to call multiple times.
// Record any histogram data that exists when the object is created so it can
// be subtracted later.
StatisticsRecorder::Histograms histograms;
StatisticsRecorder::GetSnapshot(std::string(), &histograms);
for (const auto& histogram : histograms) {
histograms_snapshot_[histogram->histogram_name()] =
histogram->SnapshotSamples();
}
}
HistogramTester::~HistogramTester() {
}
void HistogramTester::ExpectUniqueSample(
const std::string& name,
base::HistogramBase::Sample sample,
base::HistogramBase::Count expected_count) const {
base::HistogramBase* histogram =
base::StatisticsRecorder::FindHistogram(name);
EXPECT_NE(nullptr, histogram) << "Histogram \"" << name
<< "\" does not exist.";
if (histogram) {
std::unique_ptr<base::HistogramSamples> samples =
histogram->SnapshotSamples();
CheckBucketCount(name, sample, expected_count, *samples);
CheckTotalCount(name, expected_count, *samples);
}
}
void HistogramTester::ExpectBucketCount(
const std::string& name,
base::HistogramBase::Sample sample,
base::HistogramBase::Count expected_count) const {
base::HistogramBase* histogram =
base::StatisticsRecorder::FindHistogram(name);
EXPECT_NE(nullptr, histogram) << "Histogram \"" << name
<< "\" does not exist.";
if (histogram) {
std::unique_ptr<base::HistogramSamples> samples =
histogram->SnapshotSamples();
CheckBucketCount(name, sample, expected_count, *samples);
}
}
void HistogramTester::ExpectTotalCount(const std::string& name,
base::HistogramBase::Count count) const {
base::HistogramBase* histogram =
base::StatisticsRecorder::FindHistogram(name);
if (histogram) {
std::unique_ptr<base::HistogramSamples> samples =
histogram->SnapshotSamples();
CheckTotalCount(name, count, *samples);
} else {
// No histogram means there were zero samples.
EXPECT_EQ(count, 0) << "Histogram \"" << name << "\" does not exist.";
}
}
std::vector<Bucket> HistogramTester::GetAllSamples(
const std::string& name) const {
std::vector<Bucket> samples;
std::unique_ptr<HistogramSamples> snapshot =
GetHistogramSamplesSinceCreation(name);
if (snapshot) {
for (auto it = snapshot->Iterator(); !it->Done(); it->Next()) {
HistogramBase::Sample sample;
HistogramBase::Count count;
it->Get(&sample, nullptr, &count);
samples.push_back(Bucket(sample, count));
}
}
return samples;
}
HistogramTester::CountsMap HistogramTester::GetTotalCountsForPrefix(
const std::string& query) const {
EXPECT_TRUE(query.find('.') != std::string::npos)
<< "|query| ought to contain at least one period, to avoid matching too"
<< " many histograms.";
// Find matches by using the prefix-matching logic built into GetSnapshot().
StatisticsRecorder::Histograms query_matches;
StatisticsRecorder::GetSnapshot(query, &query_matches);
CountsMap result;
for (base::HistogramBase* histogram : query_matches) {
std::unique_ptr<HistogramSamples> new_samples =
GetHistogramSamplesSinceCreation(histogram->histogram_name());
// Omit unchanged histograms from the result.
if (new_samples->TotalCount()) {
result[histogram->histogram_name()] = new_samples->TotalCount();
}
}
return result;
}
std::unique_ptr<HistogramSamples>
HistogramTester::GetHistogramSamplesSinceCreation(
const std::string& histogram_name) const {
HistogramBase* histogram = StatisticsRecorder::FindHistogram(histogram_name);
// Whether the histogram exists or not may not depend on the current test
// calling this method, but rather on which tests ran before and possibly
// generated a histogram or not (see http://crbug.com/473689). To provide a
// response which is independent of the previously run tests, this method
// creates empty samples in the absence of the histogram, rather than
// returning null.
if (!histogram) {
return std::unique_ptr<HistogramSamples>(
new SampleMap(HashMetricName(histogram_name)));
}
std::unique_ptr<HistogramSamples> named_samples =
histogram->SnapshotSamples();
auto original_samples_it = histograms_snapshot_.find(histogram_name);
if (original_samples_it != histograms_snapshot_.end())
named_samples->Subtract(*original_samples_it->second.get());
return named_samples;
}
void HistogramTester::CheckBucketCount(
const std::string& name,
base::HistogramBase::Sample sample,
base::HistogramBase::Count expected_count,
const base::HistogramSamples& samples) const {
int actual_count = samples.GetCount(sample);
auto histogram_data = histograms_snapshot_.find(name);
if (histogram_data != histograms_snapshot_.end())
actual_count -= histogram_data->second->GetCount(sample);
EXPECT_EQ(expected_count, actual_count)
<< "Histogram \"" << name
<< "\" does not have the right number of samples (" << expected_count
<< ") in the expected bucket (" << sample << "). It has (" << actual_count
<< ").";
}
void HistogramTester::CheckTotalCount(
const std::string& name,
base::HistogramBase::Count expected_count,
const base::HistogramSamples& samples) const {
int actual_count = samples.TotalCount();
auto histogram_data = histograms_snapshot_.find(name);
if (histogram_data != histograms_snapshot_.end())
actual_count -= histogram_data->second->TotalCount();
EXPECT_EQ(expected_count, actual_count)
<< "Histogram \"" << name
<< "\" does not have the right total number of samples ("
<< expected_count << "). It has (" << actual_count << ").";
}
bool Bucket::operator==(const Bucket& other) const {
return min == other.min && count == other.count;
}
void PrintTo(const Bucket& bucket, std::ostream* os) {
*os << "Bucket " << bucket.min << ": " << bucket.count;
}
} // namespace base