base/profiler/tracked_time.h

   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 #ifndef BASE_PROFILER_TRACKED_TIME_H_
   6 #define BASE_PROFILER_TRACKED_TIME_H_
   7
   8
   9 #include "base/base_export.h"
  10 #include "base/basictypes.h"
  11 #include "base/time/time.h"
  12
  13 namespace tracked_objects {
  14
  15 //------------------------------------------------------------------------------
  16
  17 // TimeTicks maintains a wasteful 64 bits of data (we need less than 32), and on
  18 // windows, a 64 bit timer is expensive to even obtain. We use a simple
  19 // millisecond counter for most of our time values, as well as millisecond units
  20 // of duration between those values.  This means we can only handle durations
  21 // up to 49 days (range), or 24 days (non-negative time durations).
  22 // We only define enough methods to service the needs of the tracking classes,
  23 // and our interfaces are modeled after what TimeTicks and TimeDelta use (so we
  24 // can swap them into place if we want to use the "real" classes).
  25
  26 class BASE_EXPORT Duration {  // Similar to base::TimeDelta.
  27  public:
  28   Duration();
  29
  30   Duration& operator+=(const Duration& other);
  31   Duration operator+(const Duration& other) const;
  32
  33   bool operator==(const Duration& other) const;
  34   bool operator!=(const Duration& other) const;
  35   bool operator>(const Duration& other) const;
  36
  37   static Duration FromMilliseconds(int ms);
  38
  39   int32 InMilliseconds() const;
  40
  41  private:
  42   friend class TrackedTime;
  43   explicit Duration(int32 duration);
  44
  45   // Internal time is stored directly in milliseconds.
  46   int32 ms_;
  47 };
  48
  49 class BASE_EXPORT TrackedTime {  // Similar to base::TimeTicks.
  50  public:
  51   TrackedTime();
  52   explicit TrackedTime(const base::TimeTicks& time);
  53
  54   static TrackedTime Now();
  55   Duration operator-(const TrackedTime& other) const;
  56   TrackedTime operator+(const Duration& other) const;
  57   bool is_null() const;
  58
  59   static TrackedTime FromMilliseconds(int32 ms) { return TrackedTime(ms); }
  60
  61  private:
  62   friend class Duration;
  63   explicit TrackedTime(int32 ms);
  64
  65   // Internal duration is stored directly in milliseconds.
  66   uint32 ms_;
  67 };
  68
  69 }  // namespace tracked_objects
  70
  71 #endif  // BASE_PROFILER_TRACKED_TIME_H_