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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_
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#define BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_
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#include "base/basictypes.h"
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#include "base/metrics/histogram_base.h"
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class HistogramSamples;
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class HistogramFlattener;
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// HistogramSnapshotManager handles the logistics of gathering up available
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// histograms for recording either to disk or for transmission (such as from
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// renderer to browser, or from browser to UMA upload). Since histograms can sit
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// in memory for an extended period of time, and are vulnerable to memory
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// corruption, this class also validates as much rendundancy as it can before
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// calling for the marginal change (a.k.a., delta) in a histogram to be
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class BASE_EXPORT HistogramSnapshotManager {
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explicit HistogramSnapshotManager(HistogramFlattener* histogram_flattener);
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virtual ~HistogramSnapshotManager();
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// Snapshot all histograms, and ask |histogram_flattener_| to record the
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// delta. |flags_to_set| is used to set flags for each histogram.
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// |required_flags| is used to select histograms to be recorded.
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// Only histograms that have all the flags specified by the argument will be
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// chosen. If all histograms should be recorded, set it to
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// |Histogram::kNoFlags|.
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void PrepareDeltas(HistogramBase::Flags flags_to_set,
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HistogramBase::Flags required_flags);
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// Snapshot this histogram, and record the delta.
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void PrepareDelta(const HistogramBase& histogram);
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// Try to detect and fix count inconsistency of logged samples.
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void InspectLoggedSamplesInconsistency(
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const HistogramSamples& new_snapshot,
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HistogramSamples* logged_samples);
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// For histograms, track what we've already recorded (as a sample for
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// each histogram) so that we can record only the delta with the next log.
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std::map<std::string, HistogramSamples*> logged_samples_;
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// List of histograms found to be corrupt, and their problems.
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std::map<std::string, int> inconsistencies_;
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// |histogram_flattener_| handles the logistics of recording the histogram
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HistogramFlattener* histogram_flattener_; // Weak.
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DISALLOW_COPY_AND_ASSIGN(HistogramSnapshotManager);
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#endif // BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_