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Date: Thu, 25 Sep 1997 18:38:01 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199709250838.SAA06295@godzilla.zeta.org.au>
To: gibbs@plutotech.com, julian@whistle.com
Subject: Re: new timeout routines
Cc: bde@zeta.org.au, current@FreeBSD.ORG, nate@mt.sri.com,
        tlambert@primenet.com
Sender: owner-freebsd-current@FreeBSD.ORG
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>there is an assumption in a lot of code that untimeout is idempotent
>(did I get that right?). It can be called whenever you are recovering
>from unknown situations with the sure knowledge that the appropriate
>timeout will be removed.

This was an invalid assumption, since timeout() was only (almost)
nilpotent (calling it N+1 times has the same effect as calling it N
times for some value of N, provided there are no calls to timeout()
mixed with the calls to untimeout()).

Now it is (almost) idempotent (N = 1 in the above), provided the
cookies are managed properly.  Correct cookie management corresponds
to using the correct value of N in the old version.

Bruce