histogram_snapshot_manager.h revision 5d1f7b1de12d16ceb2c938c56701a3e8bfa558f7 
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 <map>
9#include <string>
10
11#include "base/basictypes.h"
12#include "base/metrics/histogram_base.h"
13
14namespace base {
15
16class HistogramSamples;
17class HistogramFlattener;
18
19// HistogramSnapshotManager handles the logistics of gathering up available
20// histograms for recording either to disk or for transmission (such as from
21// renderer to browser, or from browser to UMA upload). Since histograms can sit
22// in memory for an extended period of time, and are vulnerable to memory
23// corruption, this class also validates as much rendundancy as it can before
24// calling for the marginal change (a.k.a., delta) in a histogram to be
25// recorded.
26class BASE_EXPORT HistogramSnapshotManager {
27 public:
28  explicit HistogramSnapshotManager(HistogramFlattener* histogram_flattener);
29  virtual ~HistogramSnapshotManager();
30
31  // Snapshot all histograms, and ask |histogram_flattener_| to record the
32  // delta. |flags_to_set| is used to set flags for each histogram.
33  // |required_flags| is used to select histograms to be recorded.
34  // Only histograms that have all the flags specified by the argument will be
35  // chosen. If all histograms should be recorded, set it to
36  // |Histogram::kNoFlags|.
37  void PrepareDeltas(HistogramBase::Flags flags_to_set,
38                     HistogramBase::Flags required_flags);
39
40 private:
41  // Snapshot this histogram, and record the delta.
42  void PrepareDelta(const HistogramBase& histogram);
43
44  // Try to detect and fix count inconsistency of logged samples.
45  void InspectLoggedSamplesInconsistency(
46      const HistogramSamples& new_snapshot,
47      HistogramSamples* logged_samples);
48
49  // For histograms, track what we've already recorded (as a sample for
50  // each histogram) so that we can record only the delta with the next log.
51  std::map<std::string, HistogramSamples*> logged_samples_;
52
53  // List of histograms found to be corrupt, and their problems.
54  std::map<std::string, int> inconsistencies_;
55
56  // |histogram_flattener_| handles the logistics of recording the histogram
57  // deltas.
58  HistogramFlattener* histogram_flattener_;  // Weak.
59
60  DISALLOW_COPY_AND_ASSIGN(HistogramSnapshotManager);
61};
62
63}  // namespace base
64
65#endif  // BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_
66