base/metrics/sparse_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 "base/metrics/sparse_histogram.h"
   6
   7 #include "base/metrics/sample_map.h"
   8 #include "base/metrics/statistics_recorder.h"
   9 #include "base/pickle.h"
  10 #include "base/strings/stringprintf.h"
  11 #include "base/synchronization/lock.h"
  12
  13 namespace base {
  14
  15 typedef HistogramBase::Count Count;
  16 typedef HistogramBase::Sample Sample;
  17
  18 // static
  19 HistogramBase* SparseHistogram::FactoryGet(const std::string& name,
  20                                            int32 flags) {
  21   HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);
  22
  23   if (!histogram) {
  24     // To avoid racy destruction at shutdown, the following will be leaked.
  25     HistogramBase* tentative_histogram = new SparseHistogram(name);
  26     tentative_histogram->SetFlags(flags);
  27     histogram =
  28         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
  29   }
  30   DCHECK_EQ(SPARSE_HISTOGRAM, histogram->GetHistogramType());
  31   return histogram;
  32 }
  33
  34 SparseHistogram::~SparseHistogram() {}
  35
  36 HistogramType SparseHistogram::GetHistogramType() const {
  37   return SPARSE_HISTOGRAM;
  38 }
  39
  40 bool SparseHistogram::HasConstructionArguments(
  41     Sample expected_minimum,
  42     Sample expected_maximum,
  43     size_t expected_bucket_count) const {
  44   // SparseHistogram never has min/max/bucket_count limit.
  45   return false;
  46 }
  47
  48 void SparseHistogram::Add(Sample value) {
  49   base::AutoLock auto_lock(lock_);
  50   samples_.Accumulate(value, 1);
  51 }
  52
  53 scoped_ptr<HistogramSamples> SparseHistogram::SnapshotSamples() const {
  54   scoped_ptr<SampleMap> snapshot(new SampleMap());
  55
  56   base::AutoLock auto_lock(lock_);
  57   snapshot->Add(samples_);
  58   return snapshot.Pass();
  59 }
  60
  61 void SparseHistogram::AddSamples(const HistogramSamples& samples) {
  62   base::AutoLock auto_lock(lock_);
  63   samples_.Add(samples);
  64 }
  65
  66 bool SparseHistogram::AddSamplesFromPickle(PickleIterator* iter) {
  67   base::AutoLock auto_lock(lock_);
  68   return samples_.AddFromPickle(iter);
  69 }
  70
  71 void SparseHistogram::WriteHTMLGraph(std::string* output) const {
  72   output->append("<PRE>");
  73   WriteAsciiImpl(true, "<br>", output);
  74   output->append("</PRE>");
  75 }
  76
  77 void SparseHistogram::WriteAscii(std::string* output) const {
  78   WriteAsciiImpl(true, "\n", output);
  79 }
  80
  81 bool SparseHistogram::SerializeInfoImpl(Pickle* pickle) const {
  82   return pickle->WriteString(histogram_name()) && pickle->WriteInt(flags());
  83 }
  84
  85 SparseHistogram::SparseHistogram(const std::string& name)
  86     : HistogramBase(name) {}
  87
  88 HistogramBase* SparseHistogram::DeserializeInfoImpl(PickleIterator* iter) {
  89   std::string histogram_name;
  90   int flags;
  91   if (!iter->ReadString(&histogram_name) || !iter->ReadInt(&flags)) {
  92     DLOG(ERROR) << "Pickle error decoding Histogram: " << histogram_name;
  93     return NULL;
  94   }
  95
  96   DCHECK(flags & HistogramBase::kIPCSerializationSourceFlag);
  97   flags &= ~HistogramBase::kIPCSerializationSourceFlag;
  98
  99   return SparseHistogram::FactoryGet(histogram_name, flags);
 100 }
 101
 102 void SparseHistogram::GetParameters(DictionaryValue* params) const {
 103   // TODO(kaiwang): Implement. (See HistogramBase::WriteJSON.)
 104 }
 105
 106 void SparseHistogram::GetCountAndBucketData(Count* count,
 107                                             int64* sum,
 108                                             ListValue* buckets) const {
 109   // TODO(kaiwang): Implement. (See HistogramBase::WriteJSON.)
 110 }
 111
 112 void SparseHistogram::WriteAsciiImpl(bool graph_it,
 113                                      const std::string& newline,
 114                                      std::string* output) const {
 115   // Get a local copy of the data so we are consistent.
 116   scoped_ptr<HistogramSamples> snapshot = SnapshotSamples();
 117   Count total_count = snapshot->TotalCount();
 118   double scaled_total_count = total_count / 100.0;
 119
 120   WriteAsciiHeader(total_count, output);
 121   output->append(newline);
 122
 123   // Determine how wide the largest bucket range is (how many digits to print),
 124   // so that we'll be able to right-align starts for the graphical bars.
 125   // Determine which bucket has the largest sample count so that we can
 126   // normalize the graphical bar-width relative to that sample count.
 127   Count largest_count = 0;
 128   Sample largest_sample = 0;
 129   scoped_ptr<SampleCountIterator> it = snapshot->Iterator();
 130   while (!it->Done()) {
 131     Sample min;
 132     Sample max;
 133     Count count;
 134     it->Get(&min, &max, &count);
 135     if (min > largest_sample)
 136       largest_sample = min;
 137     if (count > largest_count)
 138       largest_count = count;
 139     it->Next();
 140   }
 141   size_t print_width = GetSimpleAsciiBucketRange(largest_sample).size() + 1;
 142
 143   // iterate over each item and display them
 144   it = snapshot->Iterator();
 145   while (!it->Done()) {
 146     Sample min;
 147     Sample max;
 148     Count count;
 149     it->Get(&min, &max, &count);
 150
 151     // value is min, so display it
 152     std::string range = GetSimpleAsciiBucketRange(min);
 153     output->append(range);
 154     for (size_t j = 0; range.size() + j < print_width + 1; ++j)
 155       output->push_back(' ');
 156
 157     if (graph_it)
 158       WriteAsciiBucketGraph(count, largest_count, output);
 159     WriteAsciiBucketValue(count, scaled_total_count, output);
 160     output->append(newline);
 161     it->Next();
 162   }
 163 }
 164
 165 void SparseHistogram::WriteAsciiHeader(const Count total_count,
 166                                        std::string* output) const {
 167   StringAppendF(output,
 168                 "Histogram: %s recorded %d samples",
 169                 histogram_name().c_str(),
 170                 total_count);
 171   if (flags() & ~kHexRangePrintingFlag)
 172     StringAppendF(output, " (flags = 0x%x)", flags() & ~kHexRangePrintingFlag);
 173 }
 174
 175 }  // namespace base