Date: Fri, 11 Aug 2000 20:22:46 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Stephen McKay <mckay@thehub.com.au> Cc: freebsd-current@FreeBSD.ORG, David Greenman <dg@root.com>, Alfred Perlstein <bright@wintelcom.net> Subject: Re: Ugly, slow shutdown Message-ID: <23502.966018166@critter> In-Reply-To: Your message of "Sat, 12 Aug 2000 03:02:40 %2B1000." <20000812030240.A668@gift.home>
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In message <20000812030240.A668@gift.home>, Stephen McKay writes: >Regardless of the history of it all, FreeBSD is full of places where >unexpected wakeups can stuff you right up. Should we regard tsleep() like >the older sleep() call, as suspect, and program defensively? Should we >be pragmatic, admit "We've gotten away with it so far", and document the >"no sudden wakeups" behaviour? > >I quite like the general principle outlined in one of the earlier replies, >that a while loop can be shown to be correct through a local code reading, >but a simple conditional must be verified by reading all the rest of the >code. That's close to the same argument I use against global variables. >Their use is too hard to verify as correct. I support this notion with a footnote to the effect that if the test is expensive the while() can be left out if a comment points out exactly why the while() isn't needed. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD coreteam member | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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