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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Asynchronous Transfer of Control
Date: Thu, 10 Apr 2014 17:49:31 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2014-04-10T17:49:31-05:00
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"Adam Beneschan" <adambeneschan@gmail.com> wrote in message 
news:b00eabf3-5933-4c43-a75f-7137cd3fb95d@googlegroups.com...
...
>If it's a mathematical calculation, chances are that it doesn't; however, 
>adding
>"delay 0.0;" statements at key places in the calculation would add abort
>compeltion points, and hopefully this statement would be implemented in a 
>way
>so that it isn't a severe drag on efficiency.

It shouldn't be, but our experience with Claw was that not all implementers 
got the memo. (At least not until we submitted Claw bug reports to them.)

>(There's also Ada.Dispatching.Yield, which the RM says is a "task 
>dispatching
>point", but it's not clear to me whether all task dispatching points are 
>also
>abort completion points--seems like they should be, but I'd have to check 
>the
>RM further.)

I don't think they are, but it doesn't matter. Annex D requires immediate 
abort, so if you have Ada.Dispatching.Yield, you also have made everything 
essentially an abort completion point.

I'm not sure why abort completion points and task dispatching points are 
different in the RM; I'm pretty sure our implementation treats them as the 
same thing. Maybe that's also because of Annex D - task dispatching point is 
defined there and that's too late for the formal semantics of abort.

                                  Randy.