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| 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 #include "base/metrics/histogram_snapshot_manager.h" | |
| 6 | |
| 7 #include "base/memory/scoped_ptr.h" | |
| 8 #include "base/metrics/histogram_flattener.h" | |
| 9 #include "base/metrics/histogram_samples.h" | |
| 10 #include "base/metrics/statistics_recorder.h" | |
| 11 #include "base/stl_util.h" | |
| 12 | |
| 13 namespace base { | |
| 14 | |
| 15 HistogramSnapshotManager::HistogramSnapshotManager( | |
| 16 HistogramFlattener* histogram_flattener) | |
| 17 : histogram_flattener_(histogram_flattener) { | |
| 18 DCHECK(histogram_flattener_); | |
| 19 } | |
| 20 | |
| 21 HistogramSnapshotManager::~HistogramSnapshotManager() { | |
| 22 STLDeleteValues(&logged_samples_); | |
| 23 } | |
| 24 | |
| 25 void HistogramSnapshotManager::PrepareDeltas( | |
| 26 HistogramBase::Flags flag_to_set, | |
| 27 HistogramBase::Flags required_flags) { | |
| 28 StatisticsRecorder::Histograms histograms; | |
| 29 StatisticsRecorder::GetHistograms(&histograms); | |
| 30 for (StatisticsRecorder::Histograms::const_iterator it = histograms.begin(); | |
| 31 histograms.end() != it; | |
| 32 ++it) { | |
| 33 (*it)->SetFlags(flag_to_set); | |
| 34 if (((*it)->flags() & required_flags) == required_flags) | |
| 35 PrepareDelta(**it); | |
| 36 } | |
| 37 } | |
| 38 | |
| 39 void HistogramSnapshotManager::PrepareDelta(const HistogramBase& histogram) { | |
| 40 DCHECK(histogram_flattener_); | |
| 41 | |
| 42 // Get up-to-date snapshot of sample stats. | |
| 43 scoped_ptr<HistogramSamples> snapshot(histogram.SnapshotSamples()); | |
| 44 const std::string& histogram_name = histogram.histogram_name(); | |
| 45 | |
| 46 int corruption = histogram.FindCorruption(*snapshot); | |
| 47 | |
| 48 // Crash if we detect that our histograms have been overwritten. This may be | |
| 49 // a fair distance from the memory smasher, but we hope to correlate these | |
| 50 // crashes with other events, such as plugins, or usage patterns, etc. | |
| 51 if (HistogramBase::BUCKET_ORDER_ERROR & corruption) { | |
| 52 // The checksum should have caught this, so crash separately if it didn't. | |
| 53 CHECK_NE(0, HistogramBase::RANGE_CHECKSUM_ERROR & corruption); | |
| 54 CHECK(false); // Crash for the bucket order corruption. | |
| 55 } | |
| 56 // Checksum corruption might not have caused order corruption. | |
| 57 CHECK_EQ(0, HistogramBase::RANGE_CHECKSUM_ERROR & corruption); | |
| 58 | |
| 59 // Note, at this point corruption can only be COUNT_HIGH_ERROR or | |
| 60 // COUNT_LOW_ERROR and they never arise together, so we don't need to extract | |
| 61 // bits from corruption. | |
| 62 if (corruption) { | |
| 63 DLOG(ERROR) << "Histogram: " << histogram_name | |
| 64 << " has data corruption: " << corruption; | |
| 65 histogram_flattener_->InconsistencyDetected( | |
| 66 static_cast<HistogramBase::Inconsistency>(corruption)); | |
| 67 // Don't record corrupt data to metrics services. | |
| 68 int old_corruption = inconsistencies_[histogram_name]; | |
| 69 if (old_corruption == (corruption | old_corruption)) | |
| 70 return; // We've already seen this corruption for this histogram. | |
| 71 inconsistencies_[histogram_name] |= corruption; | |
| 72 histogram_flattener_->UniqueInconsistencyDetected( | |
| 73 static_cast<HistogramBase::Inconsistency>(corruption)); | |
| 74 return; | |
| 75 } | |
| 76 | |
| 77 HistogramSamples* to_log; | |
| 78 std::map<std::string, HistogramSamples*>::iterator it = | |
| 79 logged_samples_.find(histogram_name); | |
| 80 if (it == logged_samples_.end()) { | |
| 81 to_log = snapshot.release(); | |
| 82 | |
| 83 // This histogram has not been logged before, add a new entry. | |
| 84 logged_samples_[histogram_name] = to_log; | |
| 85 } else { | |
| 86 HistogramSamples* already_logged = it->second; | |
| 87 InspectLoggedSamplesInconsistency(*snapshot, already_logged); | |
| 88 snapshot->Subtract(*already_logged); | |
| 89 already_logged->Add(*snapshot); | |
| 90 to_log = snapshot.get(); | |
| 91 } | |
| 92 | |
| 93 if (to_log->TotalCount() > 0) | |
| 94 histogram_flattener_->RecordDelta(histogram, *to_log); | |
| 95 } | |
| 96 | |
| 97 void HistogramSnapshotManager::InspectLoggedSamplesInconsistency( | |
| 98 const HistogramSamples& new_snapshot, | |
| 99 HistogramSamples* logged_samples) { | |
| 100 HistogramBase::Count discrepancy = | |
| 101 logged_samples->TotalCount() - logged_samples->redundant_count(); | |
| 102 if (!discrepancy) | |
| 103 return; | |
| 104 | |
| 105 histogram_flattener_->InconsistencyDetectedInLoggedCount(discrepancy); | |
| 106 if (discrepancy > Histogram::kCommonRaceBasedCountMismatch) { | |
| 107 // Fix logged_samples. | |
| 108 logged_samples->Subtract(*logged_samples); | |
| 109 logged_samples->Add(new_snapshot); | |
| 110 } | |
| 111 } | |
| 112 | |
| 113 } // namespace base | |
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