pthread_mutex_trylock and glib-2

[Pascal Hofstee]

On Mon, 6 Sep 2004 15:12:08 -0700, Pascal Hofstee <caelian at gmail.com> wrote:
> After a few hours of digging through both the glib-2 as well as the
> beep-media-player sources i finally managed to figure out why
> beep-media-player apprently crashes on startup when using libpthread,
> but not when using libc_r.
> 
> i filed a bugreport against this problem on bugzilla.gnome.org ... in
> the hope to get some feedback from glib-developers ...
> 
> http://bugzilla.gnome.org/show_bug.cgi?id=152009
> 
> The problem is with the actual return value of pthread_mutex_trylock
> returning EDEADLK instead of EBUSY.
> 
> from what i have been able to glance from this previous discussion
> regarding this particular subject
> (http://lists.freebsd.org/pipermail/freebsd-threads/2004-January/001539.html)
> 
> pthread_mutex_trylock should behave identical to pthread_mutex_lock
> except return immediately in case of a blocking mutex, which would
> suggest EDEADLK as a possible return value.
> 
> This Seems to be the current implementation of both libpthread as well
> as libthr ... with libc_r being the sole exception.
> 
> The pthread_mutex_trylock manpage however does not reflect this actual
> implementation and only mentions EBUSY and EINVAL.
> 
> I was wondering assuming the implementation is actually correct if
> this could be rectified in the pthread_mutex_trylock manpage ... and
> if my assumption is wrong if the implementation could be changed to
> reflect the manpage.
> 
> In the former case i will have to bug the glib-devs to change the
> implementation of their pthread_mutex_trylock wrapper ... to also
> check for EDEADLK.

I am hereby including an updated
/usr/ports/devel/glib20/files/patch-gthread_gthread-posix.c

that includes the additional check for EDEADLK besides EBUSY in glib's
g_mutex_trylock_posix_impl function.

With this fix applied to my installation of glib beep-media-player now
works as expected with libpthread, and this is very likely to resolve
similar behaviour with other ports that try to use glib's threading
functions.

I CC-ed glib20 port-maintainer (gnome at FreeBSD.org) in the hope this
(or appropriate alternative) fix makes it in time for 5.3-RELEASE.

-- 
  Pascal Hofstee
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