On 04/23/2014 04:26 AM, Daniel P. Berrange wrote: > The gnulib usleep replacement says > > /* This file is _intentionally_ light-weight. Rather than using > select or nanosleep, both of which drag in external libraries on > some platforms, this merely rounds up to the nearest second if > usleep() does not exist. If sub-second resolution is important, > then use a more powerful interface to begin with. */
Modern mingw provides usleep - it's a version that can't sleep more than
1 second, but it at least has millisecond resolution. The fallback to
1-second granularity only occurs for platforms that lack usleep()
altogether.
>
> And the code confirms it
>
> int
> usleep (useconds_t micro)
> {
> unsigned int seconds = micro / 1000000;
> if (sizeof seconds < sizeof micro && micro / 1000000 != seconds)
> {
> errno = EINVAL;
> return -1;
> }
> if (!HAVE_USLEEP && micro % 1000000)
> seconds++;
> while ((seconds = sleep (seconds)) != 0);
>
> #undef usleep
> #if !HAVE_USLEEP
Have you confirmed the value of HAVE_USLEEP in config.h for the build of
mingw that you are using?
> # define usleep(x) 0
> #endif
> return usleep (micro % 1000000);
> }
>
>
> The 'sleep' replacement on Win32 calls into the Win32-specific Sleep()
> function which allows milli-second granularity. Why doesn't usleep()
> call into Sleep() directly, so it gets milli-second granularity rather
> than rounding up to the nearest second ?
As far as I can tell, mingw would be the only platform that would
benefit by calling Sleep() - but if everyone these days is already using
new enough mingw that provides usleep(), then the granularity problem is
a red herring. So at this point, I think there's nothing further worth
patching in gnulib.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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