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=unavailable autolearn_force=no version=3.4.4
X-Received: by 2002:a6b:1e05:: with SMTP id
 e5-v6mr2650991ioe.38.1524517843105;
        Mon, 23 Apr 2018 14:10:43 -0700 (PDT)
X-Received: by 2002:a9d:5c8d:: with SMTP id
 a13-v6mr1509643oti.6.1524517842740;
 Mon, 23 Apr 2018 14:10:42 -0700 (PDT)
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.org!news.unit0.net!peer03.am4!peer.am4.highwinds-media.com!peer02.iad!feed-me.highwinds-media.com!news.highwinds-media.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!k65-v6no3335782ita.0!news-out.google.com!15-v6ni4054itg.0!nntp.google.com!f63-v6no3340716itc.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups: comp.lang.ada
Date: Mon, 23 Apr 2018 14:10:42 -0700 (PDT)
In-Reply-To: <pblgbq$75q$1@gioia.aioe.org>
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com;
 posting-host=73.205.150.94;
 posting-account=Ru7E4QoAAAC_HiQ2D8LjZ7rh1mbTNcVn
NNTP-Posting-Host: 73.205.150.94
References: <f425a473-eee5-4ac4-8f0b-2413af36f508@googlegroups.com>
 <pblgbq$75q$1@gioia.aioe.org>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <5f7bce5c-b584-4cda-b1a7-2f3c7294d4ab@googlegroups.com>
Subject: Re: A question about task's select delay alternative
From: NiGHTS <nights@unku.us>
Injection-Date: Mon, 23 Apr 2018 21:10:43 +0000
Content-Type: text/plain; charset="UTF-8"
X-Received-Bytes: 2390
X-Received-Body-CRC: 305573263
Xref: reader02.eternal-september.org comp.lang.ada:51688
Date: 2018-04-23T14:10:42-07:00
List-Id: <comp.lang.ada>

On Monday, April 23, 2018 at 4:40:30 PM UTC-4, Dmitry A. Kazakov wrote:
> On 2018-04-23 19:32, NiGHTS wrote:
> > In a task with a select like this...
> > 
> > task body X is
> > begin
> >      loop
> >          select
> >              accept Y;
> >          or
> >              delay 10.0;
> >              exit;
> >          end select;
> >      end loop;
> > end X;
> > 
> > What does "delay" actually do to the CPU? In this case I am using the Adacore GNAT compiler for a PC. Is it a loop constantly evaluating elapsed time? Or is it some kind of timed interrupt?
> 
> On most systems there is a way to do it in a non-busy manner. E.g. by 
> waiting for a system waitable object with 10s timeout under Windows or 
> doing same with a futex under Linux or by using pthreads API, whatever 
> pleases the Ada RTS provider. When the entry is accepted/completed by 
> the task scheduler, the object is signaled. Otherwise the timeout is 
> expired and the thread is released with a different return code. In 
> short, do not worry.
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de

Thank you for your input. I worry too much.