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 <memory> 8 9#include "base/debug/alias.h" 10#include "base/metrics/histogram_flattener.h" 11#include "base/metrics/histogram_samples.h" 12#include "base/metrics/statistics_recorder.h" 13#include "base/stl_util.h" 14 15namespace base { 16 17HistogramSnapshotManager::HistogramSnapshotManager( 18 HistogramFlattener* histogram_flattener) 19 : histogram_flattener_(histogram_flattener) { 20 DCHECK(histogram_flattener_); 21} 22 23HistogramSnapshotManager::~HistogramSnapshotManager() { 24} 25 26void HistogramSnapshotManager::PrepareDelta(HistogramBase* histogram) { 27 PrepareSamples(histogram, histogram->SnapshotDelta()); 28} 29 30void HistogramSnapshotManager::PrepareFinalDelta( 31 const HistogramBase* histogram) { 32 PrepareSamples(histogram, histogram->SnapshotFinalDelta()); 33} 34 35void HistogramSnapshotManager::PrepareSamples( 36 const HistogramBase* histogram, 37 std::unique_ptr<HistogramSamples> samples) { 38 DCHECK(histogram_flattener_); 39 40 // Get information known about this histogram. If it did not previously 41 // exist, one will be created and initialized. 42 SampleInfo* sample_info = &known_histograms_[histogram->name_hash()]; 43 44 // Crash if we detect that our histograms have been overwritten. This may be 45 // a fair distance from the memory smasher, but we hope to correlate these 46 // crashes with other events, such as plugins, or usage patterns, etc. 47 uint32_t corruption = histogram->FindCorruption(*samples); 48 if (HistogramBase::BUCKET_ORDER_ERROR & corruption) { 49 // Extract fields useful during debug. 50 const BucketRanges* ranges = 51 static_cast<const Histogram*>(histogram)->bucket_ranges(); 52 std::vector<HistogramBase::Sample> ranges_copy; 53 for (size_t i = 0; i < ranges->size(); ++i) 54 ranges_copy.push_back(ranges->range(i)); 55 HistogramBase::Sample* ranges_ptr = &ranges_copy[0]; 56 const char* histogram_name = histogram->histogram_name().c_str(); 57 int32_t flags = histogram->flags(); 58 // The checksum should have caught this, so crash separately if it didn't. 59 CHECK_NE(0U, HistogramBase::RANGE_CHECKSUM_ERROR & corruption); 60 CHECK(false); // Crash for the bucket order corruption. 61 // Ensure that compiler keeps around pointers to |histogram| and its 62 // internal |bucket_ranges_| for any minidumps. 63 base::debug::Alias(&ranges_ptr); 64 base::debug::Alias(&histogram_name); 65 base::debug::Alias(&flags); 66 } 67 // Checksum corruption might not have caused order corruption. 68 CHECK_EQ(0U, HistogramBase::RANGE_CHECKSUM_ERROR & corruption); 69 70 // Note, at this point corruption can only be COUNT_HIGH_ERROR or 71 // COUNT_LOW_ERROR and they never arise together, so we don't need to extract 72 // bits from corruption. 73 if (corruption) { 74 DLOG(ERROR) << "Histogram: \"" << histogram->histogram_name() 75 << "\" has data corruption: " << corruption; 76 histogram_flattener_->InconsistencyDetected( 77 static_cast<HistogramBase::Inconsistency>(corruption)); 78 // Don't record corrupt data to metrics services. 79 const uint32_t old_corruption = sample_info->inconsistencies; 80 if (old_corruption == (corruption | old_corruption)) 81 return; // We've already seen this corruption for this histogram. 82 sample_info->inconsistencies |= corruption; 83 histogram_flattener_->UniqueInconsistencyDetected( 84 static_cast<HistogramBase::Inconsistency>(corruption)); 85 return; 86 } 87 88 if (samples->TotalCount() > 0) 89 histogram_flattener_->RecordDelta(*histogram, *samples); 90} 91 92void HistogramSnapshotManager::InspectLoggedSamplesInconsistency( 93 const HistogramSamples& new_snapshot, 94 HistogramSamples* logged_samples) { 95 HistogramBase::Count discrepancy = 96 logged_samples->TotalCount() - logged_samples->redundant_count(); 97 if (!discrepancy) 98 return; 99 100 histogram_flattener_->InconsistencyDetectedInLoggedCount(discrepancy); 101 if (discrepancy > Histogram::kCommonRaceBasedCountMismatch) { 102 // Fix logged_samples. 103 logged_samples->Subtract(*logged_samples); 104 logged_samples->Add(new_snapshot); 105 } 106} 107 108} // namespace base 109