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=-2.9 required=5.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.4 X-Google-Thread: 103376,ff7d8060c8210f40 X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Return-Path: From: "Randy Brukardt" To: Subject: RE: real_time.clock is not monotonic Date: Wed, 21 Feb 2007 20:34:11 -0600 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1807 In-Reply-To: <1172109952.949446.215540@l53g2000cwa.googlegroups.com> Importance: Normal X-Trash-Finder: Limited filtering for message, local (outbound) source X-Virus-Scanned: amavisd-new at ada-france.org X-BeenThere: comp.lang.ada@ada-france.org X-Mailman-Version: 2.1.9rc1 Precedence: list List-Id: "Gateway to the comp.lang.ada Usenet newsgroup" List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.ada Message-ID: X-Leafnode-NNTP-Posting-Host: 88.191.17.134 Organization: Guest of ProXad - France NNTP-Posting-Date: 22 Feb 2007 03:35:04 MET NNTP-Posting-Host: 88.191.14.223 X-Trace: 1172111704 news-2.free.fr 15283 88.191.14.223:59074 X-Complaints-To: abuse@proxad.net Path: g2news2.google.com!news2.google.com!news1.google.com!news.maxwell.syr.edu!newsfeed.icl.net!newsfeed.fjserv.net!oleane.net!oleane!feed.ac-versailles.fr!exabot.com!proxad.net!cleanfeed1-b.proxad.net!nnrp13-1.free.fr!not-for-mail Xref: g2news2.google.com comp.lang.ada:9392 Date: 2007-02-22T03:35:04+01:00 Adam writes: > Actually, I don't see in the LRM where it says "Ada.Real_Time.Clock > shall be monotonic", in such forceful language. D.8(32): "There shall be no backward clock jumps". What's not forceful about that?? An implementation could allow setting the clock forward, but not back (so Gnat is OK until fall ;-). > D.8(1) implies that > it's supposed to be. However, D.8(36) says, "The implementation shall > document any aspects of the external environment that could interfere > with the clock behavior as defined in this clause", and a note in the > AARM says, "For example, the implementation is allowed to rely on the > time services of an underlying operating system, and this operating > system clock can implement time zones or allow the clock to be reset > by an operator. This dependence has to be documented". Unless I'm > over-interpreting things, this last AARM note seems to imply that, in > some cases (such as the user manually changing the date or time), > Clock might *not* be monotonic. I think it is a statement of reality, because 1.1.3(6) always allows variations if they are "impossible or impractical" to avoid. I'm not sure why there is an explicit mention in this case; when I tried to get something similar added to D.14 (because Windows provides CPU information with a tick of 0.01 seconds in practice, even if documentation claims to have greater resolution), I was told to rely on 1.1.3(6). > Is my interpretation correct? Does this mean that GNAT's > implementation is correct (if possibly undesirable to some users) as > long as it's documented? That's practically true of virtually any implementation: 1.1.3(6) is pretty vague and the deviation would have to be pretty silly to not qualify. Randy.