third_party/WebKit/Source/platform/Histogram.h

// Copyright 2016 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.

#ifndef Histogram_h
#define Histogram_h

#include "base/metrics/histogram_base.h"
#include "platform/PlatformExport.h"
#include "wtf/CurrentTime.h"
#include <stdint.h>

namespace base {
class HistogramBase;
};

namespace blink {

class PLATFORM_EXPORT CustomCountHistogram {
 public:
  CustomCountHistogram(const char* name,
                       base::HistogramBase::Sample min,
                       base::HistogramBase::Sample max,
                       int32_t bucketCount);
  void count(base::HistogramBase::Sample);

 protected:
  explicit CustomCountHistogram(base::HistogramBase*);

  base::HistogramBase* m_histogram;
};

class PLATFORM_EXPORT BooleanHistogram : public CustomCountHistogram {
 public:
  BooleanHistogram(const char* name);
};

class PLATFORM_EXPORT EnumerationHistogram : public CustomCountHistogram {
 public:
  EnumerationHistogram(const char* name,
                       base::HistogramBase::Sample boundaryValue);
};

class PLATFORM_EXPORT SparseHistogram {
 public:
  explicit SparseHistogram(const char* name);

  void sample(base::HistogramBase::Sample);

 private:
  base::HistogramBase* m_histogram;
};

class PLATFORM_EXPORT ScopedUsHistogramTimer {
 public:
  ScopedUsHistogramTimer(CustomCountHistogram& counter)
      : m_startTime(WTF::monotonicallyIncreasingTime()), m_counter(counter) {}

  ~ScopedUsHistogramTimer() {
    m_counter.count((WTF::monotonicallyIncreasingTime() - m_startTime) *
                    base::Time::kMicrosecondsPerSecond);
  }

 private:
  // In seconds.
  double m_startTime;
  CustomCountHistogram& m_counter;
};

// Use code like this to record time, in microseconds, to execute a block of
// code:
//
// {
//     SCOPED_BLINK_UMA_HISTOGRAM_TIMER(myUmaStatName)
//     RunMyCode();
// }
// This macro records all times between 0us and 10 seconds.
// Do not change this macro without renaming all metrics that use it!
#define SCOPED_BLINK_UMA_HISTOGRAM_TIMER(name)               \
  DEFINE_STATIC_LOCAL(CustomCountHistogram, scopedUsCounter, \
                      (name, 0, 10000000, 50));              \
  ScopedUsHistogramTimer timer(scopedUsCounter);

}  // namespace blink

#endif  // Histogram_h