net/disk_cache/stats_histogram.cc

   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 "net/disk_cache/stats_histogram.h"
   6
   7 #include "base/debug/leak_annotations.h"
   8 #include "base/logging.h"
   9 #include "base/metrics/bucket_ranges.h"
  10 #include "base/metrics/histogram_base.h"
  11 #include "base/metrics/sample_vector.h"
  12 #include "base/metrics/statistics_recorder.h"
  13 #include "net/disk_cache/stats.h"
  14
  15 namespace disk_cache {
  16
  17 using base::BucketRanges;
  18 using base::Histogram;
  19 using base::HistogramSamples;
  20 using base::SampleVector;
  21 using base::StatisticsRecorder;
  22
  23 StatsHistogram::StatsHistogram(const std::string& name,
  24                                Sample minimum,
  25                                Sample maximum,
  26                                const BucketRanges* ranges,
  27                                const Stats* stats)
  28     : Histogram(name, minimum, maximum, ranges),
  29       stats_(stats) {}
  30
  31 StatsHistogram::~StatsHistogram() {}
  32
  33 // static
  34 void StatsHistogram::InitializeBucketRanges(const Stats* stats,
  35                                             BucketRanges* ranges) {
  36   for (size_t i = 0; i < ranges->size(); ++i) {
  37     ranges->set_range(i, stats->GetBucketRange(i));
  38   }
  39   ranges->ResetChecksum();
  40 }
  41
  42 StatsHistogram* StatsHistogram::FactoryGet(const std::string& name,
  43                                            const Stats* stats) {
  44   Sample minimum = 1;
  45   Sample maximum = disk_cache::Stats::kDataSizesLength - 1;
  46   size_t bucket_count = disk_cache::Stats::kDataSizesLength;
  47   HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
  48   if (!histogram) {
  49     DCHECK(stats);
  50
  51     // To avoid racy destruction at shutdown, the following will be leaked.
  52     BucketRanges* ranges = new BucketRanges(bucket_count + 1);
  53     InitializeBucketRanges(stats, ranges);
  54     const BucketRanges* registered_ranges =
  55         StatisticsRecorder::RegisterOrDeleteDuplicateRanges(ranges);
  56
  57     // To avoid racy destruction at shutdown, the following will be leaked.
  58     StatsHistogram* stats_histogram =
  59         new StatsHistogram(name, minimum, maximum, registered_ranges, stats);
  60     stats_histogram->SetFlags(kUmaTargetedHistogramFlag);
  61     histogram = StatisticsRecorder::RegisterOrDeleteDuplicate(stats_histogram);
  62   }
  63
  64   DCHECK(base::HISTOGRAM == histogram->GetHistogramType());
  65   DCHECK(histogram->HasConstructionArguments(minimum, maximum, bucket_count));
  66
  67   // We're preparing for an otherwise unsafe upcast by ensuring we have the
  68   // proper class type.
  69   StatsHistogram* return_histogram = static_cast<StatsHistogram*>(histogram);
  70   return return_histogram;
  71 }
  72
  73 void StatsHistogram::Disable() {
  74   stats_ = NULL;
  75 }
  76
  77 scoped_ptr<HistogramSamples> StatsHistogram::SnapshotSamples() const {
  78   scoped_ptr<SampleVector> samples(new SampleVector(bucket_ranges()));
  79   if (stats_)
  80      stats_->Snapshot(samples.get());
  81
  82   // Only report UMA data once.
  83   StatsHistogram* mutable_me = const_cast<StatsHistogram*>(this);
  84   mutable_me->ClearFlags(kUmaTargetedHistogramFlag);
  85
  86   return samples.PassAs<HistogramSamples>();
  87 }
  88
  89 int StatsHistogram::FindCorruption(const HistogramSamples& samples) const {
  90   // This class won't monitor inconsistencies.
  91   return HistogramBase::NO_INCONSISTENCIES;
  92 }
  93
  94 }  // namespace disk_cache