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| 1 // Copyright 2016 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 // PersistentSampleMap implements HistogramSamples interface. It is used |
| 6 // by the SparseHistogram class to store samples in persistent memory which |
| 7 // allows it to be shared between processes or live across restarts. |
| 8 |
| 9 #ifndef BASE_METRICS_PERSISTENT_SAMPLE_MAP_H_ |
| 10 #define BASE_METRICS_PERSISTENT_SAMPLE_MAP_H_ |
| 11 |
| 12 #include <stdint.h> |
| 13 |
| 14 #include <map> |
| 15 |
| 16 #include "base/compiler_specific.h" |
| 17 #include "base/macros.h" |
| 18 #include "base/memory/scoped_ptr.h" |
| 19 #include "base/metrics/histogram_base.h" |
| 20 #include "base/metrics/histogram_samples.h" |
| 21 #include "base/metrics/persistent_memory_allocator.h" |
| 22 |
| 23 namespace base { |
| 24 |
| 25 // The logic here is similar to that of SampleMap but with different data |
| 26 // structures. Changes here likely need to be duplicated there. |
| 27 class BASE_EXPORT PersistentSampleMap : public HistogramSamples { |
| 28 public: |
| 29 PersistentSampleMap(uint64_t id, |
| 30 PersistentMemoryAllocator* allocator, |
| 31 Metadata* meta); |
| 32 ~PersistentSampleMap() override; |
| 33 |
| 34 // HistogramSamples: |
| 35 void Accumulate(HistogramBase::Sample value, |
| 36 HistogramBase::Count count) override; |
| 37 HistogramBase::Count GetCount(HistogramBase::Sample value) const override; |
| 38 HistogramBase::Count TotalCount() const override; |
| 39 scoped_ptr<SampleCountIterator> Iterator() const override; |
| 40 |
| 41 protected: |
| 42 // Performs arithemetic. |op| is ADD or SUBTRACT. |
| 43 bool AddSubtractImpl(SampleCountIterator* iter, Operator op) override; |
| 44 |
| 45 // Gets a pointer to a "count" corresponding to a given |value|. Returns NULL |
| 46 // if sample does not exist. |
| 47 HistogramBase::Count* GetSampleCountStorage(HistogramBase::Sample value); |
| 48 |
| 49 // Gets a pointer to a "count" corresponding to a given |value|, creating |
| 50 // the sample (initialized to zero) if it does not already exists. |
| 51 HistogramBase::Count* GetOrCreateSampleCountStorage( |
| 52 HistogramBase::Sample value); |
| 53 |
| 54 private: |
| 55 enum : HistogramBase::Sample { kAllSamples = -1 }; |
| 56 |
| 57 // Imports samples from persistent memory by iterating over all sample |
| 58 // records found therein, adding them to the sample_counts_ map. If a |
| 59 // count for the sample |until_value| is found, stop the import and return |
| 60 // a pointer to that counter. If that value is not found, null will be |
| 61 // returned after all currently available samples have been loaded. Pass |
| 62 // kAllSamples to force the importing of all available samples. |
| 63 HistogramBase::Count* ImportSamples(HistogramBase::Sample until_value); |
| 64 |
| 65 // All created/loaded sample values and their associated counts. The storage |
| 66 // for the actual Count numbers is owned by the |allocator_|. |
| 67 std::map<HistogramBase::Sample, HistogramBase::Count*> sample_counts_; |
| 68 |
| 69 // The persistent memory allocator holding samples and an iterator through it. |
| 70 PersistentMemoryAllocator* allocator_; |
| 71 PersistentMemoryAllocator::Iterator sample_iter_; |
| 72 |
| 73 DISALLOW_COPY_AND_ASSIGN(PersistentSampleMap); |
| 74 }; |
| 75 |
| 76 } // namespace base |
| 77 |
| 78 #endif // BASE_METRICS_PERSISTENT_SAMPLE_MAP_H_ |
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