Xref: utzoo alt.toolkits.xview:124 comp.windows.open-look:556
Path: utzoo!utgpu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!sdd.hp.com!samsung!uunet!timbuk!ddickey
From: ddickey@aspen04.cray.com (Dan A. Dickey)
Newsgroups: alt.toolkits.xview,comp.windows.open-look
Subject: Re: COME ON G & G! How do I keep a button busy without busy waiting
Message-ID: <113651.22184@timbuk.cray.com>
Date: 8 Feb 91 18:29:12 GMT
References: <1991Feb7.145027.7958@resam.dk>
Reply-To: ddickey@aspen04.cray.com (Dan A. Dickey)
Organization: Cray Research, Inc.
Lines: 45


In article <1991Feb7.145027.7958@resam.dk>, andrew@resam.dk (Leif Andrew Rump) writes:
|> I received three (3) answers to my original very interesting post.  :-)
|> YOU CAN DO BETTER - and I don't accept cheating like making the
|> Reset button inactive or changing it to a Reset button, etc.!!!     :-(
|> 
|> Well instead of writing the whole thing one more time I'll ask only
|> for some suggestions on how to prevent busy waiting if I have the
|> following code (stolen from p.400 in Volume Seven of guess what!):
|> 
|> 	XFlush(dpy);
|> 	while (!reset_pressed)
|> 	{
|> 	  notify_dispatch();
|> 	  XFlush(dpy);
|> 	  /* Here is the problem - I don't have any code to put here! */
|> 	}
|> 
|> The reason I don't have any code to put in is that I'm waiting (using
|> notify_set_input_func & notify_set_itimer_func) for some input or the
|> timer to time out and I'm using this piece of code because I want to
|> stay in the callback routine to keep the button that activated the
|> callback routine in busy state...
|> 
|> Any suggestions? - Please!

Leif (and others),
	What is the problem with putting in a select() call?

I believe this would be the standard solution...do a select() on
the file descriptor associated with the dpy.  I believe you can
use XConnection() to get this (I'm not sure of the name...there is
a macro to get it though).  Check your return value from select(),
you can get a valid return which means there is something for
notify_dispatch() to do, or possibly EINTR which means your
itimer interruped the select.  Oh, also, you may want to put a timeout
value in the select() call... Just to be safe.

Anyone see any problems with this?
	-Dan

	
--
---------
Dan A. Dickey      ddickey@fizban.cray.com, or ddickey@aspen.cray.com