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   {
  50     base::AutoLock auto_lock(lock_);
  51     samples_.Accumulate(value, 1);
  52   }
  53
  54   FindAndRunCallback(value);
  55 }
  56
  57 scoped_ptr<HistogramSamples> SparseHistogram::SnapshotSamples() const {
  58   scoped_ptr<SampleMap> snapshot(new SampleMap());
  59
  60   base::AutoLock auto_lock(lock_);
  61   snapshot->Add(samples_);
  62   return snapshot.Pass();
  63 }
  64
  65 void SparseHistogram::AddSamples(const HistogramSamples& samples) {
  66   base::AutoLock auto_lock(lock_);
  67   samples_.Add(samples);
  68 }
  69
  70 bool SparseHistogram::AddSamplesFromPickle(PickleIterator* iter) {
  71   base::AutoLock auto_lock(lock_);
  72   return samples_.AddFromPickle(iter);
  73 }
  74
  75 void SparseHistogram::WriteHTMLGraph(std::string* output) const {
  76   output->append("<PRE>");
  77   WriteAsciiImpl(true, "<br>", output);
  78   output->append("</PRE>");
  79 }
  80
  81 void SparseHistogram::WriteAscii(std::string* output) const {
  82   WriteAsciiImpl(true, "\n", output);
  83 }
  84
  85 bool SparseHistogram::SerializeInfoImpl(Pickle* pickle) const {
  86   return pickle->WriteString(histogram_name()) && pickle->WriteInt(flags());
  87 }
  88
  89 SparseHistogram::SparseHistogram(const std::string& name)
  90     : HistogramBase(name) {}
  91
  92 HistogramBase* SparseHistogram::DeserializeInfoImpl(PickleIterator* iter) {
  93   std::string histogram_name;
  94   int flags;
  95   if (!iter->ReadString(&histogram_name) || !iter->ReadInt(&flags)) {
  96     DLOG(ERROR) << "Pickle error decoding Histogram: " << histogram_name;
  97     return NULL;
  98   }
  99
 100   DCHECK(flags & HistogramBase::kIPCSerializationSourceFlag);
 101   flags &= ~HistogramBase::kIPCSerializationSourceFlag;
 102
 103   return SparseHistogram::FactoryGet(histogram_name, flags);
 104 }
 105
 106 void SparseHistogram::GetParameters(DictionaryValue* params) const {
 107   // TODO(kaiwang): Implement. (See HistogramBase::WriteJSON.)
 108 }
 109
 110 void SparseHistogram::GetCountAndBucketData(Count* count,
 111                                             int64* sum,
 112                                             ListValue* buckets) const {
 113   // TODO(kaiwang): Implement. (See HistogramBase::WriteJSON.)
 114 }
 115
 116 void SparseHistogram::WriteAsciiImpl(bool graph_it,
 117                                      const std::string& newline,
 118                                      std::string* output) const {
 119   // Get a local copy of the data so we are consistent.
 120   scoped_ptr<HistogramSamples> snapshot = SnapshotSamples();
 121   Count total_count = snapshot->TotalCount();
 122   double scaled_total_count = total_count / 100.0;
 123
 124   WriteAsciiHeader(total_count, output);
 125   output->append(newline);
 126
 127   // Determine how wide the largest bucket range is (how many digits to print),
 128   // so that we'll be able to right-align starts for the graphical bars.
 129   // Determine which bucket has the largest sample count so that we can
 130   // normalize the graphical bar-width relative to that sample count.
 131   Count largest_count = 0;
 132   Sample largest_sample = 0;
 133   scoped_ptr<SampleCountIterator> it = snapshot->Iterator();
 134   while (!it->Done()) {
 135     Sample min;
 136     Sample max;
 137     Count count;
 138     it->Get(&min, &max, &count);
 139     if (min > largest_sample)
 140       largest_sample = min;
 141     if (count > largest_count)
 142       largest_count = count;
 143     it->Next();
 144   }
 145   size_t print_width = GetSimpleAsciiBucketRange(largest_sample).size() + 1;
 146
 147   // iterate over each item and display them
 148   it = snapshot->Iterator();
 149   while (!it->Done()) {
 150     Sample min;
 151     Sample max;
 152     Count count;
 153     it->Get(&min, &max, &count);
 154
 155     // value is min, so display it
 156     std::string range = GetSimpleAsciiBucketRange(min);
 157     output->append(range);
 158     for (size_t j = 0; range.size() + j < print_width + 1; ++j)
 159       output->push_back(' ');
 160
 161     if (graph_it)
 162       WriteAsciiBucketGraph(count, largest_count, output);
 163     WriteAsciiBucketValue(count, scaled_total_count, output);
 164     output->append(newline);
 165     it->Next();
 166   }
 167 }
 168
 169 void SparseHistogram::WriteAsciiHeader(const Count total_count,
 170                                        std::string* output) const {
 171   StringAppendF(output,
 172                 "Histogram: %s recorded %d samples",
 173                 histogram_name().c_str(),
 174                 total_count);
 175   if (flags() & ~kHexRangePrintingFlag)
 176     StringAppendF(output, " (flags = 0x%x)", flags() & ~kHexRangePrintingFlag);
 177 }
 178
 179 }  // namespace base