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      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 #include <stdint.h>
      9 
     10 #include "base/base_export.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_t InMilliseconds() const;
     40 
     41  private:
     42   friend class TrackedTime;
     43   explicit Duration(int32_t duration);
     44 
     45   // Internal time is stored directly in milliseconds.
     46   int32_t 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_t ms) { return TrackedTime(ms); }
     60 
     61  private:
     62   friend class Duration;
     63   explicit TrackedTime(int32_t ms);
     64 
     65   // Internal duration is stored directly in milliseconds.
     66   uint32_t ms_;
     67 };
     68 
     69 }  // namespace tracked_objects
     70 
     71 #endif  // BASE_PROFILER_TRACKED_TIME_H_
     72