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/metrics/histogram_tester.h"
6
7 #include <stddef.h>
8
9 #include "base/metrics/histogram.h"
10 #include "base/metrics/histogram_samples.h"
11 #include "base/metrics/metrics_hashes.h"
12 #include "base/metrics/sample_map.h"
13 #include "base/metrics/sparse_histogram.h"
14 #include "base/metrics/statistics_recorder.h"
15 #include "base/strings/string_util.h"
16 #include "base/strings/stringprintf.h"
17 #include "testing/gtest/include/gtest/gtest.h"
18
19 namespace base {
20
HistogramTester()21 HistogramTester::HistogramTester() {
22 // Record any histogram data that exists when the object is created so it can
23 // be subtracted later.
24 for (const auto* const histogram : StatisticsRecorder::GetHistograms()) {
25 histograms_snapshot_[histogram->histogram_name()] =
26 histogram->SnapshotSamples();
27 }
28 }
29
30 HistogramTester::~HistogramTester() = default;
31
ExpectUniqueSample(const std::string & name,HistogramBase::Sample sample,HistogramBase::Count expected_count) const32 void HistogramTester::ExpectUniqueSample(
33 const std::string& name,
34 HistogramBase::Sample sample,
35 HistogramBase::Count expected_count) const {
36 HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
37 EXPECT_NE(nullptr, histogram)
38 << "Histogram \"" << name << "\" does not exist.";
39
40 if (histogram) {
41 std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
42 CheckBucketCount(name, sample, expected_count, *samples);
43 CheckTotalCount(name, expected_count, *samples);
44 }
45 }
46
ExpectBucketCount(const std::string & name,HistogramBase::Sample sample,HistogramBase::Count expected_count) const47 void HistogramTester::ExpectBucketCount(
48 const std::string& name,
49 HistogramBase::Sample sample,
50 HistogramBase::Count expected_count) const {
51 HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
52 EXPECT_NE(nullptr, histogram)
53 << "Histogram \"" << name << "\" does not exist.";
54
55 if (histogram) {
56 std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
57 CheckBucketCount(name, sample, expected_count, *samples);
58 }
59 }
60
ExpectTotalCount(const std::string & name,HistogramBase::Count count) const61 void HistogramTester::ExpectTotalCount(const std::string& name,
62 HistogramBase::Count count) const {
63 HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
64 if (histogram) {
65 std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
66 CheckTotalCount(name, count, *samples);
67 } else {
68 // No histogram means there were zero samples.
69 EXPECT_EQ(count, 0) << "Histogram \"" << name << "\" does not exist.";
70 }
71 }
72
ExpectTimeBucketCount(const std::string & name,TimeDelta sample,HistogramBase::Count count) const73 void HistogramTester::ExpectTimeBucketCount(const std::string& name,
74 TimeDelta sample,
75 HistogramBase::Count count) const {
76 ExpectBucketCount(name, sample.InMilliseconds(), count);
77 }
78
GetAllSamples(const std::string & name) const79 std::vector<Bucket> HistogramTester::GetAllSamples(
80 const std::string& name) const {
81 std::vector<Bucket> samples;
82 std::unique_ptr<HistogramSamples> snapshot =
83 GetHistogramSamplesSinceCreation(name);
84 if (snapshot) {
85 for (auto it = snapshot->Iterator(); !it->Done(); it->Next()) {
86 HistogramBase::Sample sample;
87 HistogramBase::Count count;
88 it->Get(&sample, nullptr, &count);
89 samples.push_back(Bucket(sample, count));
90 }
91 }
92 return samples;
93 }
94
GetBucketCount(const std::string & name,HistogramBase::Sample sample) const95 HistogramBase::Count HistogramTester::GetBucketCount(
96 const std::string& name,
97 HistogramBase::Sample sample) const {
98 HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
99 EXPECT_NE(nullptr, histogram)
100 << "Histogram \"" << name << "\" does not exist.";
101 HistogramBase::Count count = 0;
102 if (histogram) {
103 std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
104 GetBucketCountForSamples(name, sample, *samples, &count);
105 }
106 return count;
107 }
108
GetBucketCountForSamples(const std::string & name,HistogramBase::Sample sample,const HistogramSamples & samples,HistogramBase::Count * count) const109 void HistogramTester::GetBucketCountForSamples(
110 const std::string& name,
111 HistogramBase::Sample sample,
112 const HistogramSamples& samples,
113 HistogramBase::Count* count) const {
114 *count = samples.GetCount(sample);
115 auto histogram_data = histograms_snapshot_.find(name);
116 if (histogram_data != histograms_snapshot_.end())
117 *count -= histogram_data->second->GetCount(sample);
118 }
119
GetTotalCountsForPrefix(const std::string & prefix) const120 HistogramTester::CountsMap HistogramTester::GetTotalCountsForPrefix(
121 const std::string& prefix) const {
122 EXPECT_TRUE(prefix.find('.') != std::string::npos)
123 << "|prefix| ought to contain at least one period, to avoid matching too"
124 << " many histograms.";
125
126 CountsMap result;
127
128 // Find candidate matches by using the logic built into GetSnapshot().
129 for (const HistogramBase* histogram : StatisticsRecorder::GetHistograms()) {
130 if (!StartsWith(histogram->histogram_name(), prefix,
131 CompareCase::SENSITIVE)) {
132 continue;
133 }
134 std::unique_ptr<HistogramSamples> new_samples =
135 GetHistogramSamplesSinceCreation(histogram->histogram_name());
136 // Omit unchanged histograms from the result.
137 if (new_samples->TotalCount()) {
138 result[histogram->histogram_name()] = new_samples->TotalCount();
139 }
140 }
141 return result;
142 }
143
144 std::unique_ptr<HistogramSamples>
GetHistogramSamplesSinceCreation(const std::string & histogram_name) const145 HistogramTester::GetHistogramSamplesSinceCreation(
146 const std::string& histogram_name) const {
147 HistogramBase* histogram = StatisticsRecorder::FindHistogram(histogram_name);
148 // Whether the histogram exists or not may not depend on the current test
149 // calling this method, but rather on which tests ran before and possibly
150 // generated a histogram or not (see http://crbug.com/473689). To provide a
151 // response which is independent of the previously run tests, this method
152 // creates empty samples in the absence of the histogram, rather than
153 // returning null.
154 if (!histogram) {
155 return std::unique_ptr<HistogramSamples>(
156 new SampleMap(HashMetricName(histogram_name)));
157 }
158 std::unique_ptr<HistogramSamples> named_samples =
159 histogram->SnapshotSamples();
160 auto original_samples_it = histograms_snapshot_.find(histogram_name);
161 if (original_samples_it != histograms_snapshot_.end())
162 named_samples->Subtract(*original_samples_it->second.get());
163 return named_samples;
164 }
165
GetAllHistogramsRecorded() const166 std::string HistogramTester::GetAllHistogramsRecorded() const {
167 std::string output;
168
169 for (const auto* const histogram : StatisticsRecorder::GetHistograms()) {
170 std::unique_ptr<HistogramSamples> named_samples =
171 histogram->SnapshotSamples();
172
173 for (const auto& histogram_data : histograms_snapshot_) {
174 if (histogram_data.first == histogram->histogram_name())
175 named_samples->Subtract(*histogram_data.second);
176 }
177
178 if (named_samples->TotalCount()) {
179 auto current_count = histogram->SnapshotSamples()->TotalCount();
180 StringAppendF(&output, "Histogram: %s recorded %d new samples.\n",
181 histogram->histogram_name(), named_samples->TotalCount());
182 if (current_count != named_samples->TotalCount()) {
183 StringAppendF(&output,
184 "WARNING: There were samples recorded to this histogram "
185 "before tester instantiation.\n");
186 }
187 histogram->WriteAscii(&output);
188 StringAppendF(&output, "\n");
189 }
190 }
191
192 return output;
193 }
194
CheckBucketCount(const std::string & name,HistogramBase::Sample sample,HistogramBase::Count expected_count,const HistogramSamples & samples) const195 void HistogramTester::CheckBucketCount(const std::string& name,
196 HistogramBase::Sample sample,
197 HistogramBase::Count expected_count,
198 const HistogramSamples& samples) const {
199 int actual_count;
200 GetBucketCountForSamples(name, sample, samples, &actual_count);
201
202 EXPECT_EQ(expected_count, actual_count)
203 << "Histogram \"" << name
204 << "\" does not have the right number of samples (" << expected_count
205 << ") in the expected bucket (" << sample << "). It has (" << actual_count
206 << ").";
207 }
208
CheckTotalCount(const std::string & name,HistogramBase::Count expected_count,const HistogramSamples & samples) const209 void HistogramTester::CheckTotalCount(const std::string& name,
210 HistogramBase::Count expected_count,
211 const HistogramSamples& samples) const {
212 int actual_count = samples.TotalCount();
213 auto histogram_data = histograms_snapshot_.find(name);
214 if (histogram_data != histograms_snapshot_.end())
215 actual_count -= histogram_data->second->TotalCount();
216
217 EXPECT_EQ(expected_count, actual_count)
218 << "Histogram \"" << name
219 << "\" does not have the right total number of samples ("
220 << expected_count << "). It has (" << actual_count << ").";
221 }
222
operator ==(const Bucket & other) const223 bool Bucket::operator==(const Bucket& other) const {
224 return min == other.min && count == other.count;
225 }
226
PrintTo(const Bucket & bucket,std::ostream * os)227 void PrintTo(const Bucket& bucket, std::ostream* os) {
228 *os << "Bucket " << bucket.min << ": " << bucket.count;
229 }
230
231 } // namespace base
232