From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: a07f3367d7,8e11100f675ea2df
X-Google-Attributes: gida07f3367d7,public,usenet
X-Google-NewGroupId: yes
X-Google-Language: ENGLISH,ASCII-7-bit
X-Received: by 10.66.88.129 with SMTP id bg1mr10350822pab.46.1357498040580;
        Sun, 06 Jan 2013 10:47:20 -0800 (PST)
From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: asynchronous task communication
Date: Mon, 31 Dec 2012 09:04:41 +0000
Organization: A noiseless patient Spider
Message-ID: <lysj6mwq1i.fsf@pushface.org>
References: <1c2dnd5E6PMDR33NnZ2dnUVZ_sednZ2d@earthlink.com>
Mime-Version: 1.0
Injection-Info: mx04.eternal-september.org;
 posting-host="585248293da7adcafb924c79c19cf5ec";
	logging-data="29912"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX19NW/akY3vE3qPGMUelOD6IVmt4yCUULLg="
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.2 (darwin)
Cancel-Lock: sha1:eoOB4x2+YHtmWdkNHGPOISe3ARU=
	sha1:ZUS27Afei0SxXn1gQc+Bv/IChFc=
Path: 
 s9ni89192pbb.0!nntp.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!news.mccarragher.com!news.grnet.gr!de-l.enfer-du-nord.net!feeder1.enfer-du-nord.net!eternal-september.org!feeder.eternal-september.org!mx04.eternal-september.org!.POSTED!not-for-mail
Content-Type: text/plain
Date: 2012-12-31T09:04:41+00:00
List-Id: <comp.lang.ada>

Charles Hixson <charleshixsn@earthlink.net> writes:

> Is it possible to call an entry point of a task from another task and
> not wait for the task to finish?
> I'm thinking of an entry point that would have only _in_ parameters,
> and which is not expected to fail, but the thread called might be
> busy, so I'd like to just queue it and go on to something else.  This
> doesn't appear to be what an "asynchronous select" does, though I'll
> admit I'm not sure, as I can't tell why they call it
> asynchronous...timed seems more reasonable than asynchronous,

Requeue[1] (with abort)?

> What I'm after is sort of like sending a letter from one task to
> another.  The sender doesn't need to wait for the receiver to accept
> the message (though, ideally, there would also be a "return receipt
> requested" option).

Not quite so straightforward.

> The only alternative that I've come up with is to have each task have
> an access variable to a protected type instance.  This can be done,
> but it makes the control in other parts of the program trickier.

If you can use Ada2012, you could try a synchronized queue[2, 3] just
for these two tasks.

[1] http://www.ada-auth.org/standards/12rm/html/RM-9-5-4.html
[2] http://www.ada-auth.org/standards/12rm/html/RM-A-18-27.html
[3] http://www.ada-auth.org/standards/12rm/html/RM-A-18-28.html