cc/base/histograms.h

   1 // Copyright 2015 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 #ifndef CC_BASE_HISTOGRAMS_H_
   6 #define CC_BASE_HISTOGRAMS_H_
   7
   8 #include "base/compiler_specific.h"
   9 #include "base/metrics/histogram_base.h"
  10 #include "base/metrics/histogram_macros.h"
  11 #include "base/numerics/safe_math.h"
  12 #include "base/time/time.h"
  13 #include "base/timer/elapsed_timer.h"
  14 #include "cc/base/cc_export.h"
  15
  16 namespace cc {
  17
  18 // Emits UMA histogram trackers for time spent as well as area (in pixels)
  19 // processed per unit time. Time is measured in microseconds, and work in
  20 // pixels per millisecond.
  21 //
  22 // Usage:
  23 //   // Outside of a method, perhaps in a namespace.
  24 //   DEFINE_SCOPED_UMA_HISTOGRAM_AREA_TIMER(ScopedReticulateSplinesTimer,
  25 //                                          "ReticulateSplinesUs",
  26 //                                          "ReticulateSplinesPixelsPerMs");
  27 //
  28 //   // Inside a method.
  29 //   ScopedReticulateSplinesTimer timer;
  30 //   timer.AddArea(some_rect.size().GetArea());
  31 #define DEFINE_SCOPED_UMA_HISTOGRAM_AREA_TIMER(class_name, time_histogram, \
  32                                                area_histogram)             \
  33   class class_name : public ::cc::ScopedUMAHistogramAreaTimerBase {        \
  34    public:                                                                 \
  35     ~class_name();                                                         \
  36   };                                                                       \
  37   class_name::~class_name() {                                              \
  38     Sample time_sample;                                                    \
  39     Sample area_sample;                                                    \
  40     if (GetHistogramValues(&time_sample, &area_sample)) {                  \
  41       UMA_HISTOGRAM_COUNTS(time_histogram, time_sample);                   \
  42       UMA_HISTOGRAM_COUNTS(area_histogram, area_sample);                   \
  43     }                                                                      \
  44   }
  45
  46 class CC_EXPORT ScopedUMAHistogramAreaTimerBase {
  47  public:
  48   void AddArea(int area) { area_ += area; }
  49   void SetArea(int area) { area_ = area; }
  50
  51  protected:
  52   using Sample = base::HistogramBase::Sample;
  53
  54   ScopedUMAHistogramAreaTimerBase();
  55   ~ScopedUMAHistogramAreaTimerBase();
  56
  57   // Returns true if histograms should be recorded (i.e. values are valid).
  58   bool GetHistogramValues(Sample* time_microseconds,
  59                           Sample* pixels_per_ms) const;
  60
  61  private:
  62   static bool GetHistogramValues(base::TimeDelta elapsed,
  63                                  int area,
  64                                  Sample* time_microseconds,
  65                                  Sample* pixels_per_ms);
  66
  67   base::ElapsedTimer timer_;
  68   base::CheckedNumeric<int> area_;
  69
  70   friend class ScopedUMAHistogramAreaTimerBaseTest;
  71   DISALLOW_COPY_AND_ASSIGN(ScopedUMAHistogramAreaTimerBase);
  72 };
  73
  74 }  // namespace cc
  75
  76 #endif  // CC_BASE_HISTOGRAMS_H_