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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/metrics/histogram_snapshot_manager.h"
#include "base/metrics/statistics_recorder.h"
using base::Histogram;
using base::StatisticsRecorder;
namespace base {
HistogramSnapshotManager::HistogramSnapshotManager(
HistogramFlattener* histogram_flattener)
: histogram_flattener_(histogram_flattener) {
DCHECK(histogram_flattener_);
}
HistogramSnapshotManager::~HistogramSnapshotManager() {}
void HistogramSnapshotManager::PrepareDeltas(Histogram::Flags flag_to_set,
bool record_only_uma) {
StatisticsRecorder::Histograms histograms;
StatisticsRecorder::GetHistograms(&histograms);
for (StatisticsRecorder::Histograms::const_iterator it = histograms.begin();
histograms.end() != it;
++it) {
(*it)->SetFlags(flag_to_set);
if (record_only_uma &&
0 == ((*it)->flags() & Histogram::kUmaTargetedHistogramFlag))
continue;
PrepareDelta(**it);
}
}
void HistogramSnapshotManager::PrepareDelta(const Histogram& histogram) {
DCHECK(histogram_flattener_);
// Get up-to-date snapshot of sample stats.
Histogram::SampleSet snapshot;
histogram.SnapshotSample(&snapshot);
const std::string& histogram_name = histogram.histogram_name();
int corruption = histogram.FindCorruption(snapshot);
// Crash if we detect that our histograms have been overwritten. This may be
// a fair distance from the memory smasher, but we hope to correlate these
// crashes with other events, such as plugins, or usage patterns, etc.
if (Histogram::BUCKET_ORDER_ERROR & corruption) {
// The checksum should have caught this, so crash separately if it didn't.
CHECK_NE(0, Histogram::RANGE_CHECKSUM_ERROR & corruption);
CHECK(false); // Crash for the bucket order corruption.
}
// Checksum corruption might not have caused order corruption.
CHECK_EQ(0, Histogram::RANGE_CHECKSUM_ERROR & corruption);
if (corruption) {
NOTREACHED();
histogram_flattener_->InconsistencyDetected(corruption);
// Don't record corrupt data to metrics survices.
if (NULL == inconsistencies_.get())
inconsistencies_.reset(new ProblemMap);
int old_corruption = (*inconsistencies_)[histogram_name];
if (old_corruption == (corruption | old_corruption))
return; // We've already seen this corruption for this histogram.
(*inconsistencies_)[histogram_name] |= corruption;
histogram_flattener_->UniqueInconsistencyDetected(corruption);
return;
}
// Find the already recorded stats, or create an empty set. Remove from our
// snapshot anything that we've already recorded.
LoggedSampleMap::iterator it = logged_samples_.find(histogram_name);
Histogram::SampleSet* already_logged;
if (logged_samples_.end() == it) {
// Add new entry
already_logged = &logged_samples_[histogram.histogram_name()];
// Complete initialization.
already_logged->Resize(histogram.bucket_count());
} else {
already_logged = &(it->second);
int64 discrepancy(already_logged->TotalCount() -
already_logged->redundant_count());
if (discrepancy) {
NOTREACHED(); // Already_logged has become corrupt.
int problem = static_cast<int>(discrepancy);
if (problem != discrepancy)
problem = INT_MAX;
histogram_flattener_->SnapshotProblemResolved(problem);
// With no valid baseline, we'll act like we've recorded everything in our
// snapshot.
already_logged->Subtract(*already_logged);
already_logged->Add(snapshot);
}
// Deduct any stats we've already logged from our snapshot.
snapshot.Subtract(*already_logged);
}
// Snapshot now contains only a delta to what we've already_logged.
if (snapshot.redundant_count() > 0) {
histogram_flattener_->RecordDelta(histogram, snapshot);
// Add new data into our running total.
already_logged->Add(snapshot);
}
}
} // namespace base
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