getUTCtime() increases irregularly

[Frits van Bommel]

david wrote:
> I was just playing with a slow down class, when I noticed
> getUTCtime() from std.date works a bit unexpected:
> 
> import std.stdio;
> import std.date : getUTCtime;
> 
> int main(char[][] args)
> {
>     for (int i=0;i<500;i++)
>         writefln(getUTCtime());
>     return 0;
> }
> 
> results in (shortened version, for obvious reasons):
> 
[snip]
> 
> So, it increases as well in large increments
> and also in irregular ones, namely
> 15 and 16 milliseconds.
> 
> Since I found nothing in the phobos docs,
> how can I access the current time at a more
> precise level?

The precision of the clock is operating-system dependent AFAIK. 
(including the version of the OS and obviously the type of machine it's 
running on)
D can't make it more accurate than the OS is willing to provide :(.

(Your post header indicates you're running Windows)
On Windows, there are (at least) two functions to get the current time: 
one returns it as a SYSTEMTIME structure, one as a FILETIME structure. 
It looks like std.date uses GetSystemTime; you could try to see if 
GetFileTime is more accurate. (no idea why it would be, but you could 
try...)
Try this:
---
import std.c.windows.windows : GetSystemTimeAsFileTime, FILETIME;
import std.date;

d_time currentFileTime() {
     FILETIME ft;
     GetSystemTimeAsFileTime(&ft);
     return std.date.FILETIME2D_time(ft);
}
---
(Coded with no access to a Windows computer, so completely untested. I 
just had the std.date source and pages referenced from 
http://msdn2.microsoft.com/en-us/library/ms725479.aspx to work with)