[Xcb] [PATCH 5/7] Add event queue splitting

Josh Triplett josh at joshtriplett.org
Fri Nov 8 16:40:46 CET 2013

On Wed, Nov 06, 2013 at 06:39:19PM -0800, Keith Packard wrote:
> Josh Triplett <josh at joshtriplett.org> writes:
> > The last time that Jamey and I spoke about this, we agreed that this
> > type of mechanism would be required to make GL work, and that there's
> > really no other way to support it.  However, I'd like to see it not
> > XGE-specific, so that it could support the existing events GL needs
> > today, not just the new Present/DRI3 approach.
> If you have concrete requirements for additional filtering, we can
> easily construct additional API in the future offering those. In
> particular, figuring out how to handle the DRI2 event stream should be
> straight forward.
> I would suggest that the 'xcb_register_for_special_event' API might want
> a different name to make it clear that this is only one of potentially
> many ways to construct an event filter. Perhaps
> 'xcb_register_special_event_xge' or some such? 

That sounds good.

> > The architecture we'd discussed was effectively that it should be
> > possible to create one or more separate event queues from the primary
> > one, add filters that peel off events into those queues (which XCB will
> > automatically apply as events arrive), and then read the next event from
> > a queue.
> That's precisely what this patch does, except that the only filter
> method offered today is driven by the requirements for the Present
> extension. Attempts to construct a completely general matching algebra
> should wait until we have a system requiring such a mechanism.

I have no interest in a general matching algebra right now; I'd prefer
to see the API only matching on event numbers as it does now.

- Josh Triplett

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