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From: phorgan@cup.portal.com (Patrick John Horgan)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: General questions regarding Tasks
Message-ID: <42787@cup.portal.com>
Date: Wed, 29 May 91 23:14:32 PDT
Organization: The Portal System (TM)
References: <1991May24.160440.374@m.cs.uiuc.edu>
  <1991May24.120133.31035@kuhub.cc.ukans.edu>

Mark Gooderum said:
>A task function should be an endless loop with some kind of check for
>an exit condition.  Since RemTask(called by DeleteTask) can be picky
>about conditions, it should call Wait(0L) (wait forever) to put itself
>in a safe state to be deleted by the parent.  Alternately a task can
>RemTask(0L) itself, but this doesn't clean up the allocations for the
>stack and TCB.
CreateTask and DeleteTask are not system calls, but rather library routines
provided by your friendly C compiler folks.  I rewrote mine to allocate the
memory for the stack, the TCB and the name of the task as part of the 
tc_MemEntry list so that when a RemTask is done the memory is freed by the
operating system.  I originally started mucking around with it because
Manx's routine didn't allocate memory for the name pointer passed to it,
it just stored the string address passed to it into the Nodes name.  This
non-reentrency broke my code which spawned many tasks (alright it only made
all the tasks have the same name, but debugging was weird!).  I sent the
new code to Manx, but haven't checked since 5.0 came out to see if they
included it.  I also sent them Create/Delete Port code to replace theirs
with the same problem.  I haven't checked to see if they used it either.

It's easy (just a few minutes after using the CreateTask in the RKM's as
a starting point), to create the CreateTask that hangs all the neccessary
memory allocations off of the Task structure, and it's so elegant.  Then
the Task can just RemTask itself:)

Patrick Horgan                      pjh70@zeus.ras.amdahl.com


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