Re: Class with task destructor

[Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>]

On 12/02/2011 09:20 AM, Adam Beneschan wrote:
>
> It's not entirely the same, though.  In a multi-way entry, if entry
> Entry_Call_2 becomes available first, then that entry is accepted and
> Entry_Call_1 can no longer be accepted.  In the code you've written
> above, if Entry_Call_2 is accepted first, but Entry_Call_1 becomes
> available before the Entry_Call_2 entry is completed, I believe that
> Entry_Call_1 is accepted and an attempt is made to cancel the call to
> Entry_Call_2--which probably doesn't succeed unless a requeue is
> involved, so that the Entry_Call_2 rendezvous still completes, but the
> Entry_Call_1 rendezvous also takes place.  I'm not 100% sure I have
> the semantics right, but I'm pretty sure the behavior would be
> different from a true multi-way entry.  Also, I have no problem
> believing that since the behavior of a multi-way entry would be
> different, the implementation could well be very different from the
> implementation necessary to implement asynchronous transfer of
> control.

I didn't recall the specifics of the Ada-95 proposal, nor am I entirely clear on 
the semantics of ATC. Will the "then abort" part be aborted when the trigger 
entry is accepted, or when it completes? I had thought it was the latter, but if 
you say otherwise then I'm probably wrong.

Anyway, the ATC multiple entry call semantics might be useful in some cases.

-- 
Jeff Carter
"Hello! Smelly English K...niggets."
Monty Python & the Holy Grail
08