media/base/scoped_histogram_timer.h

   1 // Copyright 2013 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 MEDIA_BASE_SCOPED_HISTOGRAM_TIMER_H_
   6 #define MEDIA_BASE_SCOPED_HISTOGRAM_TIMER_H_
   7
   8 #include "base/metrics/histogram.h"
   9 #include "base/time/time.h"
  10
  11 // Scoped class which logs its time on this earth as a UMA statistic.  Must be
  12 // a #define macro since UMA macros prevent variables as names.  The nested
  13 // macro is necessary to expand __COUNTER__ to an actual value.
  14 #define SCOPED_UMA_HISTOGRAM_TIMER(name) \
  15   SCOPED_UMA_HISTOGRAM_TIMER_EXPANDER(name, __COUNTER__)
  16
  17 #define SCOPED_UMA_HISTOGRAM_TIMER_EXPANDER(name, key) \
  18   SCOPED_UMA_HISTOGRAM_TIMER_UNIQUE(name, key)
  19
  20 #define SCOPED_UMA_HISTOGRAM_TIMER_UNIQUE(name, key) \
  21   class ScopedHistogramTimer##key { \
  22    public: \
  23     ScopedHistogramTimer##key() : constructed_(base::TimeTicks::Now()) {} \
  24     ~ScopedHistogramTimer##key() { \
  25       base::TimeDelta elapsed = base::TimeTicks::Now() - constructed_; \
  26       UMA_HISTOGRAM_TIMES(name, elapsed); \
  27     } \
  28    private: \
  29     base::TimeTicks constructed_; \
  30   } scoped_histogram_timer_##key
  31
  32 #endif  // MEDIA_BASE_SCOPED_HISTOGRAM_TIMER_H_