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 3 // found in the LICENSE file. 4 5 #ifndef BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_ 6 #define BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_ 7 8 #include <stdint.h> 9 10 #include <map> 11 #include <string> 12 13 #include "base/macros.h" 14 #include "base/metrics/histogram_base.h" 15 16 namespace base { 17 18 class HistogramSamples; 19 class HistogramFlattener; 20 21 // HistogramSnapshotManager handles the logistics of gathering up available 22 // histograms for recording either to disk or for transmission (such as from 23 // renderer to browser, or from browser to UMA upload). Since histograms can sit 24 // in memory for an extended period of time, and are vulnerable to memory 25 // corruption, this class also validates as much rendundancy as it can before 26 // calling for the marginal change (a.k.a., delta) in a histogram to be 27 // recorded. 28 class BASE_EXPORT HistogramSnapshotManager { 29 public: 30 explicit HistogramSnapshotManager(HistogramFlattener* histogram_flattener); 31 virtual ~HistogramSnapshotManager(); 32 33 // Snapshot all histograms, and ask |histogram_flattener_| to record the 34 // delta. |flags_to_set| is used to set flags for each histogram. 35 // |required_flags| is used to select histograms to be recorded. 36 // Only histograms that have all the flags specified by the argument will be 37 // chosen. If all histograms should be recorded, set it to 38 // |Histogram::kNoFlags|. 39 void PrepareDeltas(HistogramBase::Flags flags_to_set, 40 HistogramBase::Flags required_flags); 41 42 private: 43 // Snapshot this histogram, and record the delta. 44 void PrepareDelta(const HistogramBase& histogram); 45 46 // Try to detect and fix count inconsistency of logged samples. 47 void InspectLoggedSamplesInconsistency( 48 const HistogramSamples& new_snapshot, 49 HistogramSamples* logged_samples); 50 51 // For histograms, track what we've already recorded (as a sample for 52 // each histogram) so that we can record only the delta with the next log. 53 // The information is indexed by the hash of the histogram name. 54 std::map<uint64_t, HistogramSamples*> logged_samples_; 55 56 // Set of histograms found to be corrupt and their problems, indexed 57 // by the hash of the histogram name. 58 std::map<uint64_t, int> inconsistencies_; 59 60 // |histogram_flattener_| handles the logistics of recording the histogram 61 // deltas. 62 HistogramFlattener* histogram_flattener_; // Weak. 63 64 DISALLOW_COPY_AND_ASSIGN(HistogramSnapshotManager); 65 }; 66 67 } // namespace base 68 69 #endif // BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_ 70
