| // 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/memory/scoped_ptr.h" |
| #include "base/metrics/histogram_flattener.h" |
| #include "base/metrics/histogram_samples.h" |
| #include "base/metrics/statistics_recorder.h" |
| #include "base/stl_util.h" |
| |
| namespace base { |
| |
| HistogramSnapshotManager::HistogramSnapshotManager( |
| HistogramFlattener* histogram_flattener) |
| : preparing_deltas_(false), |
| histogram_flattener_(histogram_flattener) { |
| DCHECK(histogram_flattener_); |
| } |
| |
| HistogramSnapshotManager::~HistogramSnapshotManager() { |
| } |
| |
| void HistogramSnapshotManager::StartDeltas() { |
| // Ensure that start/finish calls do not get nested. |
| DCHECK(!preparing_deltas_); |
| preparing_deltas_ = true; |
| |
| DCHECK(owned_histograms_.empty()); |
| |
| #ifdef DEBUG |
| CHECK(!iter->second.histogram); |
| CHECK(!iter->second.accumulated_samples); |
| CHECK(!(iter->second.inconsistencies & |
| HistogramBase::NEW_INCONSISTENCY_FOUND)); |
| } |
| #endif |
| } |
| |
| void HistogramSnapshotManager::PrepareDelta(HistogramBase* histogram) { |
| PrepareSamples(histogram, histogram->SnapshotDelta()); |
| } |
| |
| void HistogramSnapshotManager::PrepareDeltaTakingOwnership( |
| scoped_ptr<HistogramBase> histogram) { |
| PrepareSamples(histogram.get(), histogram->SnapshotDelta()); |
| owned_histograms_.push_back(std::move(histogram)); |
| } |
| |
| void HistogramSnapshotManager::PrepareAbsolute(const HistogramBase* histogram) { |
| PrepareSamples(histogram, histogram->SnapshotSamples()); |
| } |
| |
| void HistogramSnapshotManager::PrepareAbsoluteTakingOwnership( |
| scoped_ptr<const HistogramBase> histogram) { |
| PrepareSamples(histogram.get(), histogram->SnapshotSamples()); |
| owned_histograms_.push_back(std::move(histogram)); |
| } |
| |
| void HistogramSnapshotManager::FinishDeltas() { |
| DCHECK(preparing_deltas_); |
| |
| // Iterate over all known histograms to see what should be recorded. |
| for (auto& hash_and_info : known_histograms_) { |
| SampleInfo* sample_info = &hash_and_info.second; |
| |
| // First, record any histograms in which corruption was detected. |
| if (sample_info->inconsistencies & HistogramBase::NEW_INCONSISTENCY_FOUND) { |
| sample_info->inconsistencies &= ~HistogramBase::NEW_INCONSISTENCY_FOUND; |
| histogram_flattener_->UniqueInconsistencyDetected( |
| static_cast<HistogramBase::Inconsistency>( |
| sample_info->inconsistencies)); |
| } |
| |
| // Second, record actual accumulated deltas. |
| if (sample_info->accumulated_samples) { |
| // TODO(bcwhite): Investigate using redundant_count() below to avoid |
| // additional pass through all the samples to calculate real total. |
| if (sample_info->accumulated_samples->TotalCount() > 0) { |
| histogram_flattener_->RecordDelta(*sample_info->histogram, |
| *sample_info->accumulated_samples); |
| } |
| delete sample_info->accumulated_samples; |
| sample_info->accumulated_samples = nullptr; |
| } |
| |
| // The Histogram pointer must be cleared at this point because the owner |
| // is only required to keep it alive until FinishDeltas() completes. |
| sample_info->histogram = nullptr; |
| } |
| |
| owned_histograms_.clear(); |
| preparing_deltas_ = false; |
| } |
| |
| void HistogramSnapshotManager::PrepareSamples( |
| const HistogramBase* histogram, |
| scoped_ptr<HistogramSamples> samples) { |
| DCHECK(histogram_flattener_); |
| |
| // Get information known about this histogram. |
| SampleInfo* sample_info = &known_histograms_[histogram->name_hash()]; |
| if (sample_info->histogram) { |
| DCHECK_EQ(sample_info->histogram->histogram_name(), |
| histogram->histogram_name()) << "hash collision"; |
| } else { |
| // First time this histogram has been seen; datafill. |
| sample_info->histogram = histogram; |
| } |
| |
| // 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. |
| uint32_t corruption = histogram->FindCorruption(*samples); |
| if (HistogramBase::BUCKET_ORDER_ERROR & corruption) { |
| // The checksum should have caught this, so crash separately if it didn't. |
| CHECK_NE(0U, HistogramBase::RANGE_CHECKSUM_ERROR & corruption); |
| CHECK(false); // Crash for the bucket order corruption. |
| } |
| // Checksum corruption might not have caused order corruption. |
| CHECK_EQ(0U, HistogramBase::RANGE_CHECKSUM_ERROR & corruption); |
| |
| // Note, at this point corruption can only be COUNT_HIGH_ERROR or |
| // COUNT_LOW_ERROR and they never arise together, so we don't need to extract |
| // bits from corruption. |
| if (corruption) { |
| DLOG(ERROR) << "Histogram: \"" << histogram->histogram_name() |
| << "\" has data corruption: " << corruption; |
| histogram_flattener_->InconsistencyDetected( |
| static_cast<HistogramBase::Inconsistency>(corruption)); |
| // Don't record corrupt data to metrics services. |
| const uint32_t old_corruption = sample_info->inconsistencies; |
| if (old_corruption == (corruption | old_corruption)) |
| return; // We've already seen this corruption for this histogram. |
| sample_info->inconsistencies |= |
| corruption | HistogramBase::NEW_INCONSISTENCY_FOUND; |
| // TODO(bcwhite): Can we clear the inconsistency for future collection? |
| return; |
| } |
| |
| if (!sample_info->accumulated_samples) { |
| // This histogram has not been seen before; add it as a new entry. |
| sample_info->accumulated_samples = samples.release(); |
| } else { |
| // There are previous values from this histogram; add them together. |
| sample_info->accumulated_samples->Add(*samples); |
| } |
| } |
| |
| void HistogramSnapshotManager::InspectLoggedSamplesInconsistency( |
| const HistogramSamples& new_snapshot, |
| HistogramSamples* logged_samples) { |
| HistogramBase::Count discrepancy = |
| logged_samples->TotalCount() - logged_samples->redundant_count(); |
| if (!discrepancy) |
| return; |
| |
| histogram_flattener_->InconsistencyDetectedInLoggedCount(discrepancy); |
| if (discrepancy > Histogram::kCommonRaceBasedCountMismatch) { |
| // Fix logged_samples. |
| logged_samples->Subtract(*logged_samples); |
| logged_samples->Add(new_snapshot); |
| } |
| } |
| |
| } // namespace base |