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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "base/metrics/sample_map.h" | 5 #include "base/metrics/sample_map.h" |
6 | 6 |
7 #include "base/logging.h" | 7 #include "base/logging.h" |
8 #include "base/stl_util.h" | |
8 | 9 |
9 namespace base { | 10 namespace base { |
10 | 11 |
11 typedef HistogramBase::Count Count; | 12 typedef HistogramBase::Count Count; |
12 typedef HistogramBase::Sample Sample; | 13 typedef HistogramBase::Sample Sample; |
13 | 14 |
14 SampleMap::SampleMap() : SampleMap(0) {} | 15 SampleMap::SampleMap() : SampleMap(0) {} |
15 | 16 |
16 SampleMap::SampleMap(uint64_t id) : HistogramSamples(id) {} | 17 SampleMap::SampleMap(uint64_t id) : HistogramSamples(id) {} |
17 | 18 |
18 SampleMap::~SampleMap() {} | 19 SampleMap::~SampleMap() {} |
19 | 20 |
20 void SampleMap::Accumulate(Sample value, Count count) { | 21 void SampleMap::Accumulate(Sample value, Count count) { |
21 sample_counts_[value] += count; | 22 sample_counts_[value] += count; |
22 IncreaseSum(static_cast<int64_t>(count) * value); | 23 IncreaseSum(static_cast<int64_t>(count) * value); |
23 IncreaseRedundantCount(count); | 24 IncreaseRedundantCount(count); |
24 } | 25 } |
25 | 26 |
26 Count SampleMap::GetCount(Sample value) const { | 27 Count SampleMap::GetCount(Sample value) const { |
27 std::map<Sample, Count>::const_iterator it = sample_counts_.find(value); | 28 std::map<Sample, Count>::const_iterator it = sample_counts_.find(value); |
28 if (it == sample_counts_.end()) | 29 if (it == sample_counts_.end()) |
29 return 0; | 30 return 0; |
30 return it->second; | 31 return it->second; |
31 } | 32 } |
32 | 33 |
33 Count SampleMap::TotalCount() const { | 34 Count SampleMap::TotalCount() const { |
34 Count count = 0; | 35 Count count = 0; |
35 for (const auto& entry : sample_counts_) { | 36 for (const auto& entry : sample_counts_) |
36 count += entry.second; | 37 count += entry.second; |
37 } | |
38 return count; | 38 return count; |
39 } | 39 } |
40 | 40 |
41 scoped_ptr<SampleCountIterator> SampleMap::Iterator() const { | 41 scoped_ptr<SampleCountIterator> SampleMap::Iterator() const { |
42 return scoped_ptr<SampleCountIterator>(new SampleMapIterator(sample_counts_)); | 42 return make_scoped_ptr(new SampleMapIterator(sample_counts_)); |
43 } | 43 } |
44 | 44 |
45 bool SampleMap::AddSubtractImpl(SampleCountIterator* iter, | 45 bool SampleMap::AddSubtractImpl(SampleCountIterator* iter, Operator op) { |
46 HistogramSamples::Operator op) { | |
47 Sample min; | 46 Sample min; |
48 Sample max; | 47 Sample max; |
49 Count count; | 48 Count count; |
50 for (; !iter->Done(); iter->Next()) { | 49 for (; !iter->Done(); iter->Next()) { |
51 iter->Get(&min, &max, &count); | 50 iter->Get(&min, &max, &count); |
52 if (min + 1 != max) | 51 if (min + 1 != max) |
53 return false; // SparseHistogram only supports bucket with size 1. | 52 return false; // SparseHistogram only supports bucket with size 1. |
54 | 53 |
55 sample_counts_[min] += (op == HistogramSamples::ADD) ? count : -count; | 54 sample_counts_[min] += (op == HistogramSamples::ADD) ? count : -count; |
56 } | 55 } |
(...skipping 13 matching lines...) Expand all Loading... | |
70 } | 69 } |
71 | 70 |
72 void SampleMapIterator::Next() { | 71 void SampleMapIterator::Next() { |
73 DCHECK(!Done()); | 72 DCHECK(!Done()); |
74 ++iter_; | 73 ++iter_; |
75 SkipEmptyBuckets(); | 74 SkipEmptyBuckets(); |
76 } | 75 } |
77 | 76 |
78 void SampleMapIterator::Get(Sample* min, Sample* max, Count* count) const { | 77 void SampleMapIterator::Get(Sample* min, Sample* max, Count* count) const { |
79 DCHECK(!Done()); | 78 DCHECK(!Done()); |
80 if (min != NULL) | 79 if (min) |
81 *min = iter_->first; | 80 *min = iter_->first; |
82 if (max != NULL) | 81 if (max) |
83 *max = iter_->first + 1; | 82 *max = iter_->first + 1; |
84 if (count != NULL) | 83 if (count) |
85 *count = iter_->second; | 84 *count = iter_->second; |
86 } | 85 } |
87 | 86 |
88 void SampleMapIterator::SkipEmptyBuckets() { | 87 void SampleMapIterator::SkipEmptyBuckets() { |
89 while (!Done() && iter_->second == 0) { | 88 while (!Done() && iter_->second == 0) |
90 ++iter_; | 89 ++iter_; |
90 } | |
91 | |
92 | |
93 // ----- PersistentSampleMap --------------------------------------------------- | |
94 | |
95 namespace { | |
96 | |
97 // This structure holds an entry for a PersistentSampleMap within a persistent | |
98 // memory allocator. The "id" must be unique across all maps held by an | |
99 // allocator or they will get attached to the wrong sample map. | |
100 struct SampleRecord { | |
101 uint64_t id; // Unique identifier of owner. | |
102 Sample value; // The value for which this record holds a count. | |
103 Count count; // The count associated with the above value. | |
104 }; | |
105 | |
106 // The type-id used to identify sample records inside an allocator. | |
107 const uint32_t kTypeIdSampleRecord = 0x8FE6A69F + 1; // SHA1(SampleRecord) v1 | |
108 | |
109 } // namespace | |
110 | |
111 PersistentSampleMap::PersistentSampleMap( | |
112 uint64_t id, | |
113 PersistentMemoryAllocator* allocator, | |
114 Metadata* meta) | |
115 : HistogramSamples(id, meta), | |
116 allocator_(allocator) { | |
117 // This is created once but will continue to return new iterables even when | |
118 // it has previously reached the end. | |
119 allocator->CreateIterator(&sample_iter_); | |
120 | |
121 // Load all existing samples during construction. It's no worse to do it | |
122 // here than at some point in the future and could be better if construction | |
123 // takes place on some background thread. New samples could be created at | |
124 // any time by parallel threads; if so, they'll get loaded when needed. | |
125 ImportSamples(kAllSamples); | |
126 } | |
127 | |
128 PersistentSampleMap::~PersistentSampleMap() {} | |
129 | |
130 void PersistentSampleMap::Accumulate(Sample value, Count count) { | |
131 *GetSampleCountStorage(value, /*create=*/true) += count; | |
132 IncreaseSum(static_cast<int64_t>(count) * value); | |
133 IncreaseRedundantCount(count); | |
134 } | |
135 | |
136 Count PersistentSampleMap::GetCount(Sample value) const { | |
137 // Have to override "const" to make sure all samples have been loaded before | |
138 // being able to know what value to return. | |
139 Count* count_pointer = | |
140 const_cast<PersistentSampleMap*>(this)->GetSampleCountStorage( | |
141 value, /*create=*/false); | |
142 return count_pointer ? *count_pointer : 0; | |
143 } | |
144 | |
145 Count PersistentSampleMap::TotalCount() const { | |
146 // Have to override "const" in order to make sure all samples have been | |
147 // loaded before trying to iterate over the map. | |
148 const_cast<PersistentSampleMap*>(this)->ImportSamples(kAllSamples); | |
149 | |
150 Count count = 0; | |
151 for (const auto& entry : sample_counts_) | |
152 count += *entry.second; | |
153 return count; | |
154 } | |
155 | |
156 scoped_ptr<SampleCountIterator> PersistentSampleMap::Iterator() const { | |
157 // Have to override "const" in order to make sure all samples have been | |
158 // loaded before trying to iterate over the map. | |
159 const_cast<PersistentSampleMap*>(this)->ImportSamples(kAllSamples); | |
160 return make_scoped_ptr(new PersistentSampleMapIterator(sample_counts_)); | |
161 } | |
162 | |
163 bool PersistentSampleMap::AddSubtractImpl(SampleCountIterator* iter, | |
164 Operator op) { | |
165 Sample min; | |
166 Sample max; | |
167 Count count; | |
168 for (; !iter->Done(); iter->Next()) { | |
169 iter->Get(&min, &max, &count); | |
170 if (min + 1 != max) | |
171 return false; // SparseHistogram only supports bucket with size 1. | |
172 | |
173 *GetSampleCountStorage(min, /*create=*/true) += | |
174 (op == HistogramSamples::ADD) ? count : -count; | |
91 } | 175 } |
176 return true; | |
177 } | |
178 | |
179 Count* PersistentSampleMap::GetSampleCountStorage(Sample value, | |
180 bool create_if_necessary) { | |
181 DCHECK_LE(0, value); | |
182 | |
183 // If |value| is already in the map, just return that. | |
184 auto it = sample_counts_.find(value); | |
185 if (it != sample_counts_.end()) | |
186 return it->second; | |
187 | |
188 // Import any new samples from persistent memory looking for the value. | |
189 Count* count_pointer = ImportSamples(value); | |
190 if (count_pointer) | |
191 return count_pointer; | |
192 | |
193 // Stop here if no creation of new samples is desired. | |
Alexei Svitkine (slow)
2016/03/03 17:43:38
I prefer these to be separate methods. You can hav
bcwhite
2016/03/07 15:30:39
Done.
| |
194 if (!create_if_necessary) | |
195 return nullptr; | |
196 | |
197 // Create a new record in persistent memory for the value. | |
198 PersistentMemoryAllocator::Reference ref = | |
199 allocator_->Allocate(sizeof(SampleRecord), kTypeIdSampleRecord); | |
200 SampleRecord* record = | |
201 allocator_->GetAsObject<SampleRecord>(ref, kTypeIdSampleRecord); | |
202 if (!record) { | |
203 // If the allocator was unable to create a record then it is full or | |
204 // corrupt. Instead, allocate the counter from the heap. This sample will | |
205 // not be persistent, will not be shared, and will leak but it's better | |
206 // than crashing. | |
207 NOTREACHED() << "full=" << allocator_->IsFull() | |
208 << ", corrupt=" << allocator_->IsCorrupt(); | |
209 count_pointer = new Count(0); | |
210 sample_counts_[value] = count_pointer; | |
211 return count_pointer; | |
212 } | |
213 record->id = id(); | |
214 record->value = value; | |
215 // record->count = 0 because allocator guarantees zero'd memory. | |
216 allocator_->MakeIterable(ref); | |
217 | |
218 // A race condition could cause two of the above records to be created. The | |
219 // allocator, however, forces a strict ordering on iterable objects so use | |
220 // the import method to actually add the just-created record. This ensures | |
221 // that all PersistentSampleMap objects will always use the same record, | |
222 // whichever was first made iterable. | |
223 count_pointer = ImportSamples(value); | |
224 DCHECK(count_pointer); | |
225 return count_pointer; | |
226 } | |
227 | |
228 Count* PersistentSampleMap::ImportSamples(Sample until_value) { | |
229 // TODO(bcwhite): This import operates in O(V+N) total time per sparse | |
230 // histogram where V is the number of values for this object and N is | |
231 // the number of other iterable objects in the allocator. This becomes | |
232 // O(S*(SV+N)) or O(S^2*V + SN) overall where S is the number of sparse | |
233 // histograms. | |
234 // | |
235 // This is actually okay when histograms are expected to exist for the | |
236 // lifetime of the program, spreading the cost out, and S and V are | |
237 // relatively small, as is the current case. | |
238 // | |
239 // However, it is not so good for objects that are created, detroyed, and | |
240 // recreated on a periodic basis, such as when making a snapshot of | |
241 // sparse histograms owned by another, ongoing process. In that case, the | |
242 // entire cost is compressed into a single sequential operation... on the | |
243 // UI thread no less. | |
244 // | |
245 // This will be addressed in a future CL. | |
246 | |
247 uint32_t type_id; | |
248 PersistentMemoryAllocator::Reference ref; | |
249 while ((ref = allocator_->GetNextIterable(&sample_iter_, &type_id)) != 0) { | |
250 if (type_id == kTypeIdSampleRecord) { | |
251 SampleRecord* record = | |
252 allocator_->GetAsObject<SampleRecord>(ref, kTypeIdSampleRecord); | |
253 if (!record) | |
254 continue; | |
255 | |
256 // A sample record has been found but may not be for this histogram. | |
257 if (record->id != id()) | |
258 continue; | |
259 | |
260 // Check if the record's value is already known. | |
261 if (!ContainsKey(sample_counts_, record->value)) { | |
262 // No: Add it to map of known values if the value is valid. | |
263 if (record->value >= 0) | |
264 sample_counts_[record->value] = &record->count; | |
265 } else { | |
266 // Yes: Ignore it; it's a duplicate caused by a race condition. | |
267 DCHECK_EQ(0, record->count); // Duplicate record should never be used. | |
268 } | |
269 | |
270 // Stop if it's the value being searched for. | |
271 if (record->value == until_value) | |
272 return &record->count; | |
273 } | |
274 } | |
275 | |
276 return nullptr; | |
277 } | |
278 | |
279 PersistentSampleMapIterator::PersistentSampleMapIterator( | |
280 const SampleToCountMap& sample_counts) | |
281 : iter_(sample_counts.begin()), | |
282 end_(sample_counts.end()) { | |
283 SkipEmptyBuckets(); | |
284 } | |
285 | |
286 PersistentSampleMapIterator::~PersistentSampleMapIterator() {} | |
287 | |
288 bool PersistentSampleMapIterator::Done() const { | |
289 return iter_ == end_; | |
290 } | |
291 | |
292 void PersistentSampleMapIterator::Next() { | |
293 DCHECK(!Done()); | |
294 ++iter_; | |
295 SkipEmptyBuckets(); | |
296 } | |
297 | |
298 void PersistentSampleMapIterator::Get(Sample* min, | |
299 Sample* max, | |
300 Count* count) const { | |
301 DCHECK(!Done()); | |
302 if (min) | |
303 *min = iter_->first; | |
304 if (max) | |
305 *max = iter_->first + 1; | |
306 if (count) | |
307 *count = *iter_->second; | |
308 } | |
309 | |
310 void PersistentSampleMapIterator::SkipEmptyBuckets() { | |
311 while (!Done() && *iter_->second == 0) | |
312 ++iter_; | |
92 } | 313 } |
93 | 314 |
94 } // namespace base | 315 } // namespace base |
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