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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 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 | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // Time represents an absolute point in coordinated universal time (UTC), | 5 // Time represents an absolute point in coordinated universal time (UTC), |
6 // internally represented as microseconds (s/1,000,000) since the Windows epoch | 6 // internally represented as microseconds (s/1,000,000) since the Windows epoch |
7 // (1601-01-01 00:00:00 UTC). System-dependent clock interface routines are | 7 // (1601-01-01 00:00:00 UTC). System-dependent clock interface routines are |
8 // defined in time_PLATFORM.cc. Note that values for Time may skew and jump | 8 // defined in time_PLATFORM.cc. Note that values for Time may skew and jump |
9 // around as the operating system makes adjustments to synchronize (e.g., with | 9 // around as the operating system makes adjustments to synchronize (e.g., with |
10 // NTP servers). Thus, client code that uses the Time class must account for | 10 // NTP servers). Thus, client code that uses the Time class must account for |
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67 | 67 |
68 #if defined(OS_POSIX) | 68 #if defined(OS_POSIX) |
69 #include <unistd.h> | 69 #include <unistd.h> |
70 #include <sys/time.h> | 70 #include <sys/time.h> |
71 #endif | 71 #endif |
72 | 72 |
73 #if defined(OS_WIN) | 73 #if defined(OS_WIN) |
74 // For FILETIME in FromFileTime, until it moves to a new converter class. | 74 // For FILETIME in FromFileTime, until it moves to a new converter class. |
75 // See TODO(iyengar) below. | 75 // See TODO(iyengar) below. |
76 #include <windows.h> | 76 #include <windows.h> |
77 | |
78 #include "base/gtest_prod_util.h" | 77 #include "base/gtest_prod_util.h" |
79 #endif | 78 #endif |
80 | 79 |
81 namespace base { | 80 namespace base { |
82 | 81 |
82 class PlatformThreadHandle; | |
83 class TimeDelta; | 83 class TimeDelta; |
84 | 84 |
85 // The functions in the time_internal namespace are meant to be used only by the | 85 // The functions in the time_internal namespace are meant to be used only by the |
86 // time classes and functions. Please use the math operators defined in the | 86 // time classes and functions. Please use the math operators defined in the |
87 // time classes instead. | 87 // time classes instead. |
88 namespace time_internal { | 88 namespace time_internal { |
89 | 89 |
90 // Add or subtract |value| from a TimeDelta. The int64_t argument and return | 90 // Add or subtract |value| from a TimeDelta. The int64_t argument and return |
91 // value are in terms of a microsecond timebase. | 91 // value are in terms of a microsecond timebase. |
92 BASE_EXPORT int64_t SaturatedAdd(TimeDelta delta, int64_t value); | 92 BASE_EXPORT int64_t SaturatedAdd(TimeDelta delta, int64_t value); |
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742 | 742 |
743 // Returns thread-specific CPU-time on systems that support this feature. | 743 // Returns thread-specific CPU-time on systems that support this feature. |
744 // Needs to be guarded with a call to IsSupported(). Use this timer | 744 // Needs to be guarded with a call to IsSupported(). Use this timer |
745 // to (approximately) measure how much time the calling thread spent doing | 745 // to (approximately) measure how much time the calling thread spent doing |
746 // actual work vs. being de-scheduled. May return bogus results if the thread | 746 // actual work vs. being de-scheduled. May return bogus results if the thread |
747 // migrates to another CPU between two calls. Returns an empty ThreadTicks | 747 // migrates to another CPU between two calls. Returns an empty ThreadTicks |
748 // object until the initialization is completed. If a clock reading is | 748 // object until the initialization is completed. If a clock reading is |
749 // absolutely needed, call WaitUntilInitialized() before this method. | 749 // absolutely needed, call WaitUntilInitialized() before this method. |
750 static ThreadTicks Now(); | 750 static ThreadTicks Now(); |
751 | 751 |
752 #if defined(OS_WIN) | |
753 // Similar to Now() above except this returns thread-specific CPU time for an | |
754 // arbitrary thread. All comments for Now() method above apply apply to this | |
755 // method as well. | |
756 static ThreadTicks GetForThread(const PlatformThreadHandle& thread_handle); | |
757 #endif | |
758 | |
752 private: | 759 private: |
753 friend class time_internal::TimeBase<ThreadTicks>; | 760 friend class time_internal::TimeBase<ThreadTicks>; |
754 | 761 |
755 // Please use Now() to create a new object. This is for internal use | 762 // Please use Now() or GetForThread to create a new object. This is for |
Mark Mentovai
2016/04/22 01:14:47
GetForThread() with parentheses to match how Now()
| |
756 // and testing. | 763 // internal use and testing. |
757 explicit ThreadTicks(int64_t us) : TimeBase(us) {} | 764 explicit ThreadTicks(int64_t us) : TimeBase(us) {} |
758 | 765 |
759 #if defined(OS_WIN) | 766 #if defined(OS_WIN) |
760 FRIEND_TEST_ALL_PREFIXES(TimeTicks, TSCTicksPerSecond); | 767 FRIEND_TEST_ALL_PREFIXES(TimeTicks, TSCTicksPerSecond); |
761 | 768 |
762 // Returns the frequency of the TSC in ticks per second, or 0 if it hasn't | 769 // Returns the frequency of the TSC in ticks per second, or 0 if it hasn't |
763 // been measured yet. Needs to be guarded with a call to IsSupported(). | 770 // been measured yet. Needs to be guarded with a call to IsSupported(). |
764 // This method is declared here rather than in the anonymous namespace to | 771 // This method is declared here rather than in the anonymous namespace to |
765 // allow testing. | 772 // allow testing. |
766 static double TSCTicksPerSecond(); | 773 static double TSCTicksPerSecond(); |
767 | 774 |
768 static bool IsSupportedWin(); | 775 static bool IsSupportedWin(); |
769 static void WaitUntilInitializedWin(); | 776 static void WaitUntilInitializedWin(); |
770 #endif | 777 #endif |
771 }; | 778 }; |
772 | 779 |
773 // For logging use only. | 780 // For logging use only. |
774 BASE_EXPORT std::ostream& operator<<(std::ostream& os, ThreadTicks time_ticks); | 781 BASE_EXPORT std::ostream& operator<<(std::ostream& os, ThreadTicks time_ticks); |
775 | 782 |
776 } // namespace base | 783 } // namespace base |
777 | 784 |
778 #endif // BASE_TIME_TIME_H_ | 785 #endif // BASE_TIME_TIME_H_ |
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