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(StringPiece name,HistogramBase::Sample sample,HistogramBase::Count expected_count) const32 void HistogramTester::ExpectUniqueSample(
33 StringPiece name,
34 HistogramBase::Sample sample,
35 HistogramBase::Count expected_count) const {
36 HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
37 if (histogram) {
38 std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
39 CheckBucketCount(name, sample, expected_count, *samples);
40 CheckTotalCount(name, expected_count, *samples);
41 } else {
42 // No histogram means there were zero samples.
43 EXPECT_EQ(0, expected_count)
44 << "Zero samples found for Histogram \"" << name << "\".";
45 }
46 }
47
ExpectUniqueTimeSample(StringPiece name,TimeDelta sample,HistogramBase::Count expected_count) const48 void HistogramTester::ExpectUniqueTimeSample(
49 StringPiece name,
50 TimeDelta sample,
51 HistogramBase::Count expected_count) const {
52 ExpectUniqueSample(name, sample.InMilliseconds(), expected_count);
53 }
54
ExpectBucketCount(StringPiece name,HistogramBase::Sample sample,HistogramBase::Count expected_count) const55 void HistogramTester::ExpectBucketCount(
56 StringPiece name,
57 HistogramBase::Sample sample,
58 HistogramBase::Count expected_count) const {
59 HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
60 if (histogram) {
61 std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
62 CheckBucketCount(name, sample, expected_count, *samples);
63 } else {
64 // No histogram means there were zero samples.
65 EXPECT_EQ(0, expected_count)
66 << "Histogram \"" << name << "\" does not exist.";
67 }
68 }
69
ExpectTotalCount(StringPiece name,HistogramBase::Count count) const70 void HistogramTester::ExpectTotalCount(StringPiece name,
71 HistogramBase::Count count) const {
72 HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
73 if (histogram) {
74 std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
75 CheckTotalCount(name, count, *samples);
76 } else {
77 // No histogram means there were zero samples.
78 EXPECT_EQ(count, 0) << "Histogram \"" << name << "\" does not exist.";
79 }
80 }
81
ExpectTimeBucketCount(StringPiece name,TimeDelta sample,HistogramBase::Count count) const82 void HistogramTester::ExpectTimeBucketCount(StringPiece name,
83 TimeDelta sample,
84 HistogramBase::Count count) const {
85 ExpectBucketCount(name, sample.InMilliseconds(), count);
86 }
87
GetAllSamples(StringPiece name) const88 std::vector<Bucket> HistogramTester::GetAllSamples(StringPiece name) const {
89 std::vector<Bucket> samples;
90 std::unique_ptr<HistogramSamples> snapshot =
91 GetHistogramSamplesSinceCreation(name);
92 if (snapshot) {
93 for (auto it = snapshot->Iterator(); !it->Done(); it->Next()) {
94 HistogramBase::Sample sample;
95 HistogramBase::Count count;
96 it->Get(&sample, nullptr, &count);
97 samples.push_back(Bucket(sample, count));
98 }
99 }
100 return samples;
101 }
102
GetBucketCount(StringPiece name,HistogramBase::Sample sample) const103 HistogramBase::Count HistogramTester::GetBucketCount(
104 StringPiece name,
105 HistogramBase::Sample sample) const {
106 HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
107 HistogramBase::Count count = 0;
108 if (histogram) {
109 std::unique_ptr<HistogramSamples> samples = histogram->SnapshotSamples();
110 GetBucketCountForSamples(name, sample, *samples, &count);
111 }
112 return count;
113 }
114
GetBucketCountForSamples(StringPiece name,HistogramBase::Sample sample,const HistogramSamples & samples,HistogramBase::Count * count) const115 void HistogramTester::GetBucketCountForSamples(
116 StringPiece name,
117 HistogramBase::Sample sample,
118 const HistogramSamples& samples,
119 HistogramBase::Count* count) const {
120 *count = samples.GetCount(sample);
121 auto histogram_data = histograms_snapshot_.find(name);
122 if (histogram_data != histograms_snapshot_.end())
123 *count -= histogram_data->second->GetCount(sample);
124 }
125
GetTotalCountsForPrefix(StringPiece prefix) const126 HistogramTester::CountsMap HistogramTester::GetTotalCountsForPrefix(
127 StringPiece prefix) const {
128 EXPECT_TRUE(prefix.find('.') != StringPiece::npos)
129 << "|prefix| ought to contain at least one period, to avoid matching too"
130 << " many histograms.";
131
132 CountsMap result;
133
134 // Find candidate matches by using the logic built into GetSnapshot().
135 for (const HistogramBase* histogram : StatisticsRecorder::GetHistograms()) {
136 if (!StartsWith(histogram->histogram_name(), prefix,
137 CompareCase::SENSITIVE)) {
138 continue;
139 }
140 std::unique_ptr<HistogramSamples> new_samples =
141 GetHistogramSamplesSinceCreation(histogram->histogram_name());
142 // Omit unchanged histograms from the result.
143 if (new_samples->TotalCount()) {
144 result[histogram->histogram_name()] = new_samples->TotalCount();
145 }
146 }
147 return result;
148 }
149
150 std::unique_ptr<HistogramSamples>
GetHistogramSamplesSinceCreation(StringPiece histogram_name) const151 HistogramTester::GetHistogramSamplesSinceCreation(
152 StringPiece histogram_name) const {
153 HistogramBase* histogram = StatisticsRecorder::FindHistogram(histogram_name);
154 // Whether the histogram exists or not may not depend on the current test
155 // calling this method, but rather on which tests ran before and possibly
156 // generated a histogram or not (see http://crbug.com/473689). To provide a
157 // response which is independent of the previously run tests, this method
158 // creates empty samples in the absence of the histogram, rather than
159 // returning null.
160 if (!histogram) {
161 return std::unique_ptr<HistogramSamples>(
162 new SampleMap(HashMetricName(histogram_name)));
163 }
164 std::unique_ptr<HistogramSamples> named_samples =
165 histogram->SnapshotSamples();
166 auto original_samples_it = histograms_snapshot_.find(histogram_name);
167 if (original_samples_it != histograms_snapshot_.end())
168 named_samples->Subtract(*original_samples_it->second.get());
169 return named_samples;
170 }
171
GetAllHistogramsRecorded() const172 std::string HistogramTester::GetAllHistogramsRecorded() const {
173 std::string output;
174
175 for (const auto* const histogram : StatisticsRecorder::GetHistograms()) {
176 std::unique_ptr<HistogramSamples> named_samples =
177 histogram->SnapshotSamples();
178
179 for (const auto& histogram_data : histograms_snapshot_) {
180 if (histogram_data.first == histogram->histogram_name())
181 named_samples->Subtract(*histogram_data.second);
182 }
183
184 if (named_samples->TotalCount()) {
185 auto current_count = histogram->SnapshotSamples()->TotalCount();
186 StringAppendF(&output, "Histogram: %s recorded %d new samples.\n",
187 histogram->histogram_name(), named_samples->TotalCount());
188 if (current_count != named_samples->TotalCount()) {
189 StringAppendF(&output,
190 "WARNING: There were samples recorded to this histogram "
191 "before tester instantiation.\n");
192 }
193 histogram->WriteAscii(&output);
194 StringAppendF(&output, "\n");
195 }
196 }
197
198 return output;
199 }
200
CheckBucketCount(StringPiece name,HistogramBase::Sample sample,HistogramBase::Count expected_count,const HistogramSamples & samples) const201 void HistogramTester::CheckBucketCount(StringPiece name,
202 HistogramBase::Sample sample,
203 HistogramBase::Count expected_count,
204 const HistogramSamples& samples) const {
205 int actual_count;
206 GetBucketCountForSamples(name, sample, samples, &actual_count);
207
208 EXPECT_EQ(expected_count, actual_count)
209 << "Histogram \"" << name
210 << "\" does not have the right number of samples (" << expected_count
211 << ") in the expected bucket (" << sample << "). It has (" << actual_count
212 << ").";
213 }
214
CheckTotalCount(StringPiece name,HistogramBase::Count expected_count,const HistogramSamples & samples) const215 void HistogramTester::CheckTotalCount(StringPiece name,
216 HistogramBase::Count expected_count,
217 const HistogramSamples& samples) const {
218 int actual_count = samples.TotalCount();
219 auto histogram_data = histograms_snapshot_.find(name);
220 if (histogram_data != histograms_snapshot_.end())
221 actual_count -= histogram_data->second->TotalCount();
222
223 EXPECT_EQ(expected_count, actual_count)
224 << "Histogram \"" << name
225 << "\" does not have the right total number of samples ("
226 << expected_count << "). It has (" << actual_count << ").";
227 }
228
operator ==(const Bucket & other) const229 bool Bucket::operator==(const Bucket& other) const {
230 return min == other.min && count == other.count;
231 }
232
PrintTo(const Bucket & bucket,std::ostream * os)233 void PrintTo(const Bucket& bucket, std::ostream* os) {
234 *os << "Bucket " << bucket.min << ": " << bucket.count;
235 }
236
237 } // namespace base
238