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 Path: eternal-september.org!reader01.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED.BbH97sg9o6mM6D9Le5/JeQ.user.gioia.aioe.org!not-for-mail From: Simon Wright Newsgroups: comp.lang.ada Subject: Re: Ravenscar - release multiple tasks when an event occurs Date: Tue, 05 May 2020 17:05:27 +0100 Organization: Aioe.org NNTP Server Message-ID: References: NNTP-Posting-Host: BbH97sg9o6mM6D9Le5/JeQ.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain X-Complaints-To: abuse@aioe.org User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (darwin) Cancel-Lock: sha1:ZWiEptN8tfuhvPTdn/qAmePjg2k= X-Notice: Filtered by postfilter v. 0.9.2 Xref: reader01.eternal-september.org comp.lang.ada:58594 Date: 2020-05-05T17:05:27+01:00 List-Id: Jere writes: > On Sunday, May 3, 2020 at 6:43:31 AM UTC-4, Simon Wright wrote: >> I have several sensor tasks (in general, 2 at the moment) which will of >> course be created and start execution during elaboration. >> >> I'd like to ensure that they don't actually start reading and reporting >> input data until the system is in a state to receive them. >> >> With the Ravenscar profile it's not obvious how to do this (only one >> entry per PO, only one task allowed to queue). I suppose I could just >> ignore the inputs until the system's ready to receive them! but has >> anyone a scheme which is less clunky? >> >> An alternative would be to try for the Jorvik profile, which does allow >> multiple tasks to queue on one entry. > > I don't have any experience using ravenscar, so this is somewhat of > a question as well as a potential option. I know you cannot do > relative delays, but can you do absolute delays? If so, could that > then give you the option to have a single protected object with a > get function and set procedure (no entries) and you just spin lock > at the beginning of all your tasks looking for that protected > object to change state? With Ravenscar, you can _only_ do absolute delays. Jorvik (not yet in the compiler, GNAT_Extended_Ravenscar is the equivalent) allows relative delays too. I think it would be unwise to spin lock! A loop with a short delay would do.