root/base/metrics/sparse_histogram.cc

DEFINITIONS

1. FactoryGet
2. GetHistogramType
3. HasConstructionArguments
4. Add
5. SnapshotSamples
6. AddSamples
7. AddSamplesFromPickle
8. WriteHTMLGraph
9. WriteAscii
10. SerializeInfoImpl
11. DeserializeInfoImpl
12. GetParameters
13. GetCountAndBucketData
14. WriteAsciiImpl
15. WriteAsciiHeader

// 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/sparse_histogram.h"

#include "base/metrics/sample_map.h"
#include "base/metrics/statistics_recorder.h"
#include "base/pickle.h"
#include "base/strings/stringprintf.h"
#include "base/synchronization/lock.h"

using std::map;
using std::string;

namespace base {

typedef HistogramBase::Count Count;
typedef HistogramBase::Sample Sample;

// static
HistogramBase* SparseHistogram::FactoryGet(const string& name, int32 flags) {
  HistogramBase* histogram = StatisticsRecorder::FindHistogram(name);

  if (!histogram) {
    // To avoid racy destruction at shutdown, the following will be leaked.
    HistogramBase* tentative_histogram = new SparseHistogram(name);
    tentative_histogram->SetFlags(flags);
    histogram =
        StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
  }
  DCHECK_EQ(SPARSE_HISTOGRAM, histogram->GetHistogramType());
  return histogram;
}

SparseHistogram::~SparseHistogram() {}

HistogramType SparseHistogram::GetHistogramType() const {
  return SPARSE_HISTOGRAM;
}

bool SparseHistogram::HasConstructionArguments(
    Sample expected_minimum,
    Sample expected_maximum,
    size_t expected_bucket_count) const {
  // SparseHistogram never has min/max/bucket_count limit.
  return false;
}

void SparseHistogram::Add(Sample value) {
  base::AutoLock auto_lock(lock_);
  samples_.Accumulate(value, 1);
}

scoped_ptr<HistogramSamples> SparseHistogram::SnapshotSamples() const {
  scoped_ptr<SampleMap> snapshot(new SampleMap());

  base::AutoLock auto_lock(lock_);
  snapshot->Add(samples_);
  return snapshot.PassAs<HistogramSamples>();
}

void SparseHistogram::AddSamples(const HistogramSamples& samples) {
  base::AutoLock auto_lock(lock_);
  samples_.Add(samples);
}

bool SparseHistogram::AddSamplesFromPickle(PickleIterator* iter) {
  base::AutoLock auto_lock(lock_);
  return samples_.AddFromPickle(iter);
}

void SparseHistogram::WriteHTMLGraph(string* output) const {
  output->append("<PRE>");
  WriteAsciiImpl(true, "<br>", output);
  output->append("</PRE>");
}

void SparseHistogram::WriteAscii(string* output) const {
  WriteAsciiImpl(true, "\n", output);
}

bool SparseHistogram::SerializeInfoImpl(Pickle* pickle) const {
  return pickle->WriteString(histogram_name()) && pickle->WriteInt(flags());
}

SparseHistogram::SparseHistogram(const string& name)
    : HistogramBase(name) {}

HistogramBase* SparseHistogram::DeserializeInfoImpl(PickleIterator* iter) {
  string histogram_name;
  int flags;
  if (!iter->ReadString(&histogram_name) || !iter->ReadInt(&flags)) {
    DLOG(ERROR) << "Pickle error decoding Histogram: " << histogram_name;
    return NULL;
  }

  DCHECK(flags & HistogramBase::kIPCSerializationSourceFlag);
  flags &= ~HistogramBase::kIPCSerializationSourceFlag;

  return SparseHistogram::FactoryGet(histogram_name, flags);
}

void SparseHistogram::GetParameters(DictionaryValue* params) const {
  // TODO(kaiwang): Implement. (See HistogramBase::WriteJSON.)
}

void SparseHistogram::GetCountAndBucketData(Count* count,
                                            int64* sum,
                                            ListValue* buckets) const {
  // TODO(kaiwang): Implement. (See HistogramBase::WriteJSON.)
}

void SparseHistogram::WriteAsciiImpl(bool graph_it,
                                     const std::string& newline,
                                     std::string* output) const {
  // Get a local copy of the data so we are consistent.
  scoped_ptr<HistogramSamples> snapshot = SnapshotSamples();
  Count total_count = snapshot->TotalCount();
  double scaled_total_count = total_count / 100.0;

  WriteAsciiHeader(total_count, output);
  output->append(newline);

  // Determine how wide the largest bucket range is (how many digits to print),
  // so that we'll be able to right-align starts for the graphical bars.
  // Determine which bucket has the largest sample count so that we can
  // normalize the graphical bar-width relative to that sample count.
  Count largest_count = 0;
  Sample largest_sample = 0;
  scoped_ptr<SampleCountIterator> it = snapshot->Iterator();
  while (!it->Done())
  {
    Sample min;
    Sample max;
    Count count;
    it->Get(&min, &max, &count);
    if (min > largest_sample)
      largest_sample = min;
    if (count > largest_count)
      largest_count = count;
    it->Next();
  }
  size_t print_width = GetSimpleAsciiBucketRange(largest_sample).size() + 1;

  // iterate over each item and display them
  it = snapshot->Iterator();
  while (!it->Done())
  {
    Sample min;
    Sample max;
    Count count;
    it->Get(&min, &max, &count);

    // value is min, so display it
    string range = GetSimpleAsciiBucketRange(min);
    output->append(range);
    for (size_t j = 0; range.size() + j < print_width + 1; ++j)
      output->push_back(' ');

    if (graph_it)
      WriteAsciiBucketGraph(count, largest_count, output);
    WriteAsciiBucketValue(count, scaled_total_count, output);
    output->append(newline);
    it->Next();
  }
}

void SparseHistogram::WriteAsciiHeader(const Count total_count,
                                       std::string* output) const {
  StringAppendF(output,
                "Histogram: %s recorded %d samples",
                histogram_name().c_str(),
                total_count);
  if (flags() & ~kHexRangePrintingFlag)
    StringAppendF(output, " (flags = 0x%x)", flags() & ~kHexRangePrintingFlag);
}

}  // namespace base