Monotonic clocks

[Chris Vine]

On Mon, 24 May 2010 09:46:39 -0400 (EDT)
Daniel Eischen <deischen at freebsd.org> wrote:
> On Mon, 24 May 2010, Chris Vine wrote:
> 
> > Hi,
> >
> > I am the upstream maintainer of efax-gtk and I am told recent
> > versions of the program will not compile on the FreeBSD port of
> > debian, because FreeBSD does not appear to provide
> > pthread_condattr_setclock() to set a monotonic clock on condition
> > variables.
> >
> > The program configuration script calls up sysconf() to determine
> > whether the POSIX advanced realtime option (_SC_MONOTONIC_CLOCK) is
> > provided, and FreeBSD's sysconf() indicates that it is.  Is anything
> > else needed to enable monotonic clocks on BSD, or is sysconf()
> > incorrectly advertising the implementation of monotonic clocks in
> > BSD's libc?
> 
> What version of FreeBSD are you using?  The code looks like it
> tries to use CLOCK_MONOTONIC if specified.  From 
> src/lib/libthr/thread/thr_init.c:
> 
> int
> _pthread_condattr_setclock(pthread_condattr_t *attr, clockid_t
> clock_id) {
>  	if (attr == NULL || *attr == NULL)
>  		return (EINVAL);
>  	if (clock_id != CLOCK_REALTIME &&
>  	    clock_id != CLOCK_VIRTUAL &&
>  	    clock_id != CLOCK_PROF &&
>  	    clock_id != CLOCK_MONOTONIC) {
>  		return  (EINVAL);
>  	}
>  	(*attr)->c_clockid = clock_id;
>  	return (0);
> }
> 
> Are you getting an error from pthread_condattr_setclock() or is
> it just not functioning correctly?

The function is entirely missing from the pthread.h header.  I don't use
FreeBSD but the problem arises on the version of FreeBSD used by
debian.  I don't know what that is, I am afraid.

I am hopeful that checking for_POSIX_CLOCK_SELECTION and
_SC_CLOCK_SELECTION, as well as _POSIX_MONOTONIC_CLOCK and
_SC_MONOTONIC_CLOCK will address the problem.  (This means that the
system clock will be used instead.)

Chris