base/metrics/histogram_delta_serialization.h

   1 // Copyright 2013 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_DELTA_SERIALIZATION_H_
   6 #define BASE_METRICS_HISTOGRAM_DELTA_SERIALIZATION_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/base_export.h"
  12 #include "base/basictypes.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/metrics/histogram_flattener.h"
  15 #include "base/metrics/histogram_snapshot_manager.h"
  16
  17 namespace base {
  18
  19 class HistogramBase;
  20
  21 // Serializes and restores histograms deltas.
  22 class BASE_EXPORT HistogramDeltaSerialization : public HistogramFlattener {
  23  public:
  24   // |caller_name| is string used in histograms for counting inconsistencies.
  25   explicit HistogramDeltaSerialization(const std::string& caller_name);
  26   ~HistogramDeltaSerialization() override;
  27
  28   // Computes deltas in histogram bucket counts relative to the previous call to
  29   // this method. Stores the deltas in serialized form into |serialized_deltas|.
  30   // If |serialized_deltas| is NULL, no data is serialized, though the next call
  31   // will compute the deltas relative to this one.
  32   void PrepareAndSerializeDeltas(std::vector<std::string>* serialized_deltas);
  33
  34   // Deserialize deltas and add samples to corresponding histograms, creating
  35   // them if necessary. Silently ignores errors in |serialized_deltas|.
  36   static void DeserializeAndAddSamples(
  37       const std::vector<std::string>& serialized_deltas);
  38
  39  private:
  40   // HistogramFlattener implementation.
  41   void RecordDelta(const HistogramBase& histogram,
  42                    const HistogramSamples& snapshot) override;
  43   void InconsistencyDetected(HistogramBase::Inconsistency problem) override;
  44   void UniqueInconsistencyDetected(
  45       HistogramBase::Inconsistency problem) override;
  46   void InconsistencyDetectedInLoggedCount(int amount) override;
  47
  48   // Calculates deltas in histogram counters.
  49   HistogramSnapshotManager histogram_snapshot_manager_;
  50
  51   // Output buffer for serialized deltas.
  52   std::vector<std::string>* serialized_deltas_;
  53
  54   // Histograms to count inconsistencies in snapshots.
  55   HistogramBase* inconsistencies_histogram_;
  56   HistogramBase* inconsistencies_unique_histogram_;
  57   HistogramBase* inconsistent_snapshot_histogram_;
  58
  59   DISALLOW_COPY_AND_ASSIGN(HistogramDeltaSerialization);
  60 };
  61
  62 }  // namespace base
  63
  64 #endif  // BASE_METRICS_HISTOGRAM_DELTA_SERIALIZATION_H_