Path: utzoo!attcan!uunet!samsung!sdd.hp.com!elroy.jpl.nasa.gov!forsight!jato!mars!kaleb
From: kaleb@mars.jpl.nasa.gov (Kaleb Keithley)
Newsgroups: comp.windows.x
Subject: Re: What is the politically correct way...
Message-ID: <3837@jato.Jpl.Nasa.Gov>
Date: 25 May 90 23:17:01 GMT
References: <3833@jato.Jpl.Nasa.Gov>
Sender: news@jato.Jpl.Nasa.Gov
Reply-To: kaleb@mars.UUCP (Kaleb Keithley)
Organization: Jet Propulsion Laboratory, Pasadena, CA.
Lines: 28

I know it's bad form to follow up your own article, but...

In article <3833@jato.Jpl.Nasa.Gov> I wrote
>to detect that the server has closed the connection to a client?
>
>I have a (psuedo?) client that only sends XEvents to other clients.
>When the user ends a session and logs out (under xdm) the server resets
>and closes all client connections.  Since my client is not reading
>the event queue, it does not detect the closure until the next time it
>tries to send.  I'd like to detect the closure, and do a gracefull exit,
>rather than suffer the consequences of Xlib exit()ing for me.

What I have found to work is to periodically do a select(), testing the
ability to write on display->fd.  When select returns an indication that
write is not possible, then I assume the server has closed the connection,
and exit gracefully.

Two questions:
1.  Is this approach reasonable/acceptable.

2.  What risk, if any, is there in never reading from display->fd, i.e.
    never doing a XNextEvent().  In the same vein, does the server ever
    send anything to a client that doesn't create any windows, never
    registers for events, in short, I just XOpenDisplay (), and then
    loop forever doing XSendEvent ()?

kaleb@thyme.jpl.nasa.gov            Jet Propeller Labs
Kaleb Keithley