Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!ucsd!ucbvax!hoptoad!tim
From: tim@hoptoad.uucp (Tim Maroney)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Safety of using async _Control from ioCompletion?
Message-ID: <10614@hoptoad.uucp>
Date: 6 Mar 90 00:04:48 GMT
References: <1990Mar5.031521.4774@caen.engin.umich.edu>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Organization: Eclectic Software, San Francisco
Lines: 21

In article <1990Mar5.031521.4774@caen.engin.umich.edu>
mystone@mondo.engin.umich.edu (Dean Yu) writes:
>  I know the old litany of not moving memory from a completion routine.  What
>I'm wondering is if it's safe to make an asynchronous _Control call from a
>completion routine.  I was thinking about the AppleTalk drivers specifically;
>if I have all the response and request buffers allocated beforehand, is it
>safe to send an async SendResponse in the completion routine of a GetRequest?

Sure, but just to be safe, use a different parameter block.  And at all
costs avoid the situation where you set up a possibly bottomless
recursion, where the completion routine for operation A starts
operation B and the completion routine for operation B starts operation
A.  You wouldn't think these things would complete immediately and
overflow the stack, and they usually don't, but I have seen some cases
where they do.
-- 
Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, tim@toad.com

"I see little divinity about them or you.  You talk to me of Christianity
 when you are in the act of hanging your enemies.  Was there ever such
 blasphemous nonsense!" - Shaw, "The Devil's Disciple"