Jeff Garland:
Now I also understand better the sentence that appear in N2320 in all timed functions: "ElapsedTime shall be explicitly convertible to nanoseconds". It's because nanoseconds are the basic for all. Now lets
I'll check, but that's incorrect and has been removed. They don't need to be convertible to nanoseconds, they need to provide get_count and a ticks_per_second trait to allow conversion to the system time resolution.
This strikes me as overgeneralization (speaking strictly of the thread-related portions of the standard). I don't quite see why struct std::abstime: public timespec { // constructors... }; struct std::reltime: public timespec { // constructors... }; // overloaded operators, a way to obtain the system time... isn't enough. POSIX uses timespec and Windows uses milliseconds.
Yes, it will, but the time duration type provides all the machinery to support the needed rounding. Frankly rounding will be the majority of the cases if you use nanoseconds because few systems currently have clock support at that resolution.
POSIX systems use nanoseconds in the interface. timespec is struct timespec { time_t tv_sec; long tv_nsec; }; or to be precise, its definition is: "The <time.h> header shall declare the structure timespec, which has at least the following members: time_t tv_sec Seconds. long tv_nsec Nanoseconds."