Re: [LAD] alsa sequencer and sysex editing

On Tue, 2008-06-03 at 14:15 +0200, Tim Goetze wrote:
> [Fons Adriaensen]
> >I don't know the details of GTK, but this is a classic problem
> >with high-level GUI toolsets: they don't allow you to wait
> >for X events (which trigger the loop, behind the scenes) and
> >anyhting else at the same time in the same thread. They don't
> >even separate _waiting_ for an X event, and _handling_ it into
> >two separate user calls (which would allow the user to add the
> >missing multiple wait functionality). This is one of the
> >reasons why I wrote my own GUI toolkit.
>
> You should check out g_main_context_set_poll_func() sometime. I admit
> it took me longer than it should have to find it myself. In short, it
> does what you want. In a gtk way, sure, but it does it.

and as an example, the Quartz (OS X) backend for GTK uses this because
it has to wait for events on file descriptors and from Cocoa/Quartz
(equivalent to X11).

sadly, it still ends up using one thread to wait on file descriptors and
this thread "injects" a Cocoa-level event into the other "main" event
thread. this is because OS X, like almost all Unix systems, fails to
provide a single system call to "wait till something happens". you
cannot wait for a file descriptor, semaphore, msgqueue, X event and/or
whatever else with a single blocking system call, and IMHO this is still
one the biggest weaknesses of the POSIX API.

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Received on Tue Jun 3 16:15:03 2008