Re: Timeouts in Ada

[Simon Wright <simon@pushface.org>]

NiGHTS <nights@unku.us> writes:

> So even if the entry call takes an hour, it will still wait the full
> hour until it completes before entering the "or delay" section? This
> is what I am understanding so far.

After the entry call has been accepted, the timeout is cancelled; Adam's
pseudocode had Wait_For_Rendezvous_To_Complete at that point. It could
wait for days to complete (not that that's a good idea).

> Also, can two entry calls be placed like this?
>
>     select call_1(params)
>         ...
>     or call_2(params)
>         ...
>     or delay 10
>         ...
>     end select
>
> If so, how would it know which finishes first without having them run
> concurrently? Don't see a point in having them run one after the
> other.

Not allowed: ARM 9.7.2 [1].

> I have also seen the select used with an "else". What exactly is the
> difference between "or" and "else"? Is "else" used when a "delay" is
> not involved? Otherwise I don't see the point in the "else" path.

This is in ARM 9.7.3. If the entry_call_alternative (the part after the
select) can't be accepted immediately, the else part is executed.

[1] http://www.ada-auth.org/standards/12rm/html/RM-9-7-2.html