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From: resnick@cogsci.uiuc.edu (Pete Resnick)
Newsgroups: comp.sys.mac.programmer
Subject: Re: asynchronous question
Message-ID: <1990Nov19.233738.24954@ux1.cso.uiuc.edu>
Date: 19 Nov 90 23:37:38 GMT
References: <1990Nov19.130139.35978@eagle.wesleyan.edu>
Sender: news@ux1.cso.uiuc.edu (News)
Organization: University of Illinois at Urbana
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rcook@eagle.wesleyan.edu writes:

>Assuming the first AppleTalk call has not yet been completed by the time the
>second call is made, is it safe to reuse MyParmBlock in this way?  Ignore for
>now the fact that I can't go back and check if the first call was completed
>successfully.  In other words, when something is placed in an I/O queue, is a
>copy of the parameter block made or is a pointer to your data placed in the
>queue instead?  I assume it makes a copy, but I want to hear this from someone
>who knows for sure.  Thanks.

First, the Device Manager does not make copies, it uses your parameter
block. And I *know* that if you do this making the Device Manager calls
in MacTCP, MacTCP will yell and scream about it being a duplicate block.
I don't know if Appletalk depends on or even will check if you are using
the same block for two operations simultaneously, but either way it cannot
be safe.

pr
--
Pete Resnick             (...so what is a mojo, and why would one be rising?)
Graduate assistant - Philosophy Department, Gregory Hall, UIUC
System manager - Cognitive Science Group, Beckman Institute, UIUC
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