wayland: how should dispatch the default wayland display queue?

[Eugen Friedrich]

2014-07-28 12:29 GMT+02:00 Giulio Camuffo <giuliocamuffo at gmail.com>:

> 2014-07-28 13:19 GMT+03:00 Daniel Stone <daniel at fooishbar.org>:
> > Hi Eugen,
> >
> > On 27 July 2014 22:16, Eugen Friedrich <friedrix at gmail.com> wrote:
> >>
> >> Hi Daniel,
> >>
> >> thanks, i understood we should add the wl_display_dispatch_pending call
> in
> >> the application
> >> there is currently no way to avoid this and basically it does not harm.
> >> I only wanted to understand if there is something missing.
> >
> >
> > Doing that is not enough. Firstly, it requires the application to do
> this,
> > or else EGL will break, which will make your stack appear broken with
> > different applications. Secondly, as an application may do this in any
> > thread, you could run into locking issues.
> >
> > wl_display_sync() does the following (paraphrased):
> >   callback = wl_display_roundtrip(); /* creates wl_callback object on
> > default queue */
> >   while (!callback_signalled)
> >       wl_display_dispatch(); /* dispatch default queue until callback
> > processed */
>
> Daniel, you swapped wl_display_sync() and wl_display_roundtrip() :).
>
> >
> > This violates the rule that EGL must not intefere with the default queue
> -
> > meaning that the wl_callback object _cannot_ be placed on the main queue.
> >
> > In order to do this correctly, you will see Mesa does:
> >   callback = wl_display_roundtrip();
> >   wl_callback_set_queue(callback, internal_egl_queue);
> >   while (!callback_signalled)
> >       wl_display_dispatch_queue(internal_egl_queue);
> >
> > As with all objects created by your EGL implementation, the wl_callback
> > object must be moved to the queue immediately after it is created by
> > wl_display_roundtrip(). Doing this will ensure correctness and also not
> > require apps to be constantly dispatching the main queue. You can search
> the
> > Mesa codebase for uses of wl_display_roundtrip() to find some examples of
> > this pattern.
> >
> > Again - any object created by your EGL implementation that is not
> > immediately moved to your internal event queue is a bug.
> >
>
Understood and our driver is basically is very similar to mesa in this
respect but the wayland-compositor will send the delete_id event(delete the
wl_display_sync callback) which is always goes to the default queue  which
is in some applications not dispatched, therefore the memory consumption is
increasing in those applications.

So as conclusion: each egl wayland client has to dispatch the default
display queue on there own!?

> Cheers,
> > Daniel
> >
> > _______________________________________________
> > wayland-devel mailing list
> > wayland-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/wayland-devel
> >
>
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