Re: change to gtk-1.2/threads.scm

[Jonathan Wilson]

Hi Kevin,
thanks for your response!

Kevin Ryde wrote:
> Please post a failing sample program if you can.
I can probably do this tonight when I get home.

> >                          (while #t
> >                                 (if (gtk-events-pending)
> >                                   (gtk-main-iteration)
> >                                   (yield))))
>
> That's meant to be unnecessary, the glib threads hooks stuff is
> supposed to be initialized so the "select"s within gtk-main (etc) will
> cooperate with the guile threading.

I've been looking at the gtk+-1.2 and glib source.  gtk_main() calls 
g_main_run(loop), which calls g_main_iterate(TRUE,TRUE).  The first 
argument is called "block".  I take this to mean that if it is true, the 
thread will block when there is no input.  So, I think we need to leave 
guile mode whenever we call gtk_main, so that blocking doesn't screw up 
guile.  From the 1.8 guile manual (I am using guile 1.8, btw):

Consequently, when a thread in guile mode blocks and does no longer 
frequent safe points, it might cause all other guile mode threads to 
block as well. To prevent this from happening, a guile mode thread 
should either only block in libguile functions (who know how to do it 
right), or should temporarily leave guile mode with scm_without_guile.

So it seems that we either must leave guile mode to run the gtk event 
loop, or else run it in such a way that it does not block ever.

I suppose that we'd have to wrap all callbacks to scheme function in 
scm_with_guile or something.

Regards,
Jon