| // 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 <memory> |
| |
| #include "base/debug/alias.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) |
| : histogram_flattener_(histogram_flattener) { |
| DCHECK(histogram_flattener_); |
| } |
| |
| HistogramSnapshotManager::~HistogramSnapshotManager() { |
| } |
| |
| void HistogramSnapshotManager::PrepareDelta(HistogramBase* histogram) { |
| PrepareSamples(histogram, histogram->SnapshotDelta()); |
| } |
| |
| void HistogramSnapshotManager::PrepareFinalDelta( |
| const HistogramBase* histogram) { |
| PrepareSamples(histogram, histogram->SnapshotFinalDelta()); |
| } |
| |
| void HistogramSnapshotManager::PrepareSamples( |
| const HistogramBase* histogram, |
| std::unique_ptr<HistogramSamples> samples) { |
| DCHECK(histogram_flattener_); |
| |
| // Get information known about this histogram. If it did not previously |
| // exist, one will be created and initialized. |
| SampleInfo* sample_info = &known_histograms_[histogram->name_hash()]; |
| |
| // 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) { |
| // Extract fields useful during debug. |
| const BucketRanges* ranges = |
| static_cast<const Histogram*>(histogram)->bucket_ranges(); |
| std::vector<HistogramBase::Sample> ranges_copy; |
| for (size_t i = 0; i < ranges->size(); ++i) |
| ranges_copy.push_back(ranges->range(i)); |
| HistogramBase::Sample* ranges_ptr = &ranges_copy[0]; |
| const char* histogram_name = histogram->histogram_name().c_str(); |
| int32_t flags = histogram->flags(); |
| // 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. |
| // Ensure that compiler keeps around pointers to |histogram| and its |
| // internal |bucket_ranges_| for any minidumps. |
| base::debug::Alias(&ranges_ptr); |
| base::debug::Alias(&histogram_name); |
| base::debug::Alias(&flags); |
| } |
| // 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; |
| histogram_flattener_->UniqueInconsistencyDetected( |
| static_cast<HistogramBase::Inconsistency>(corruption)); |
| return; |
| } |
| |
| if (samples->TotalCount() > 0) |
| histogram_flattener_->RecordDelta(*histogram, *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 |