C++ representation of time duration, time point, and clocks

This package forms part of the Boost C++ Libraries collection.

The Boost.Chrono library provides:

 * A means to represent time durations: managed by the generic

duration class . Examples of time durations include days, minutes, seconds and nanoseconds, which can be represented with a fixed number of clock ticks per unit. All of these units of time duration are united with a generic interface by the duration facility.

 * A type for representing points in time: time_point. A time_point

represents an epoch plus or minus a duration. The library leaves epochs unspecified. A time_point is associated with a clock.

 * Several clocks, some of which may not be available on a

particular platform: system_clock, steady_clock and high_resolution_clock. A clock is a pairing of a time_point and duration, and a function which returns a time_point representing now.

To make the timing facilities more generally useful, Boost.Chrono provides a number of clocks that are thin wrappers around the operating system's time APIs, thereby allowing the extraction of wall clock time, user CPU time, system CPU time spent by the process:

 * process_real_cpu_clock, captures wall clock CPU time spent by the

current process.

 * process_user_cpu_clock, captures user-CPU time

spent by the current process.

 * process_system_cpu_clock, captures

system-CPU time spent by the current process.

 * A tuple-like class

process_cpu_clock, that captures real, user-CPU, and system-CPU process times together.

 * A thread_clock thread steady clock giving

the time spent by the current thread (when supported by a platform).

Lastly, Boost.Chrono includes typeof registration for duration and time_point to permit using emulated auto with C++03 compilers.

标签: 软件开发: 函数库, 角色: 开发用函数库

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