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=0.2 required=5.0 tests=BAYES_00,INVALID_MSGID, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,6ff6ac051491e437 X-Google-Attributes: gid103376,public From: progers@acm.org Subject: Re: Question about the need for requeue as described in Rationale Date: 1996/07/09 Message-ID: <4rskkl$o4q@uuneo.neosoft.com>#1/1 X-Deja-AN: 167312641 references: <31c8fdd4.5a455349@zesi.ruhr.de> <31E16C28.3BE2@csehp3.mdc.com> organization: NeoSoft, Inc. reply-to: progers@acm.org newsgroups: comp.lang.ada Date: 1996-07-09T00:00:00+00:00 List-Id: In <31E16C28.3BE2@csehp3.mdc.com>, "James A. Squire" writes: >progers@ACM.ORG wrote: > >> Requeue is needed to deal with the difficulties associated with >> "avoidance synchronization", which is the model used in Ada. >> The most illustrative example IMHO is the lack >> of expressive power of guard conditions in select statements: >> the conditions may not refer to the formal parameters of the >> accept statements they control. Thus you sometimes have to >> to do two rendezvous instead of one, and this leads to a >> number of other difficulties: the race conditions and potential >> for abort mentioned elsewhere. > >How is this different from barrier conditions on protected entries and >procedures? The same issue applies to protected entry barriers (protected procedures don't have barriers). >> See >> >> A Problem With Ada and Resource Allocation, Ada >> Letters, vol. 3, no. 4 from 1984, >> >> or better yet, to hear how requeue works, >> >> Burns & Wellings' Concurrency In Ada, >> Cambridge University Press, 1995 > >I don't have access to either of these references. Could you be a >little more lucid? The thrust of what you are saying went right by me. Well, I think I was lucid when I wrote that :) but maybe I could have been less succinct! In any case, I strongly suggest you get access to the Burns' and Wellings book, since you seem interested in the subject. >-- >James Squire >MDA Avionics Tools & Processes >ja_squire@csehp3.mdc.com >Opinions expressed here are my own and NOT my company's >"one of these days I'm going to better myself by going to Knight school" >"You'll be a web knight instead of a web page!" pat --------------- Patrick Rogers progers@acm.org