[Xcb] problem with xcb_poll_for_reply (or xcb_wait_for_reply)

Julien Danjou julien at danjou.info
Wed Aug 6 03:02:24 PDT 2008

At 1218009864 time_t, Barton C Massey wrote:
> I haven't dug around inside this code for a while, but I
> it's hard to use select() followed by poll_for_reply() in
> general.  Whenever XCB gets a chance, it likes to pull
> replies off the wire in big chunks and stick them in its
> internal queues.

Well, I can confirme this behaviour which is very annoying.

My current hack is to do something like:

while((ev = xcb_poll_for_event(globalconf.connection)))
    xcb_handle_event(globalconf.evenths, ev);

/* do some other stuff */

 /* synchronize can wake up X and pull new events in the queue */
 if((ev = xcb_poll_for_event(globalconf.connection)))
     goto xev_restart;

But I think in theory select() can miss events since there's a race.
In practise it works quite well.

Julien Danjou
// ᐰ <julien at danjou.info>   http://julien.danjou.info
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