From: Charles Forsyth <forsyth@terzarima.net>
To: 9fans@9fans.net
Subject: Re: [9fans] double wakeup disallowed
Date: Wed, 28 Oct 2009 09:43:28 +0000 [thread overview]
Message-ID: <d73c6a7a4b7a22bffde73a5b0ec7a0b7@terzarima.net> (raw)
In-Reply-To: <8c9a75f61b57905d955240c33d4d805c@ladd.quanstro.net>
it isn't protecting against double wakeups, but
instead detects a bug in the code. there's an invariant
that the rendez and the process point to each other
while the process is asleep.
wakeup checks that invariant.
there are three primitives (sleep, wakeup and note)
and at different times in the past at least one of them
has been wrong; it's wise to check the invariant.
>and only disallows waking up a process that's not
>sleeping or sleeping on another Rendez.
but wakeup doesn't wakeup a particular process, it
wakes up exactly the process sleeping on the given Rendez,
so the situation can't arise.
next prev parent reply other threads:[~2009-10-28 9:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-27 23:38 erik quanstrom
2009-10-28 9:43 ` Charles Forsyth [this message]
[not found] <<d73c6a7a4b7a22bffde73a5b0ec7a0b7@terzarima.net>
2009-10-28 13:24 ` erik quanstrom
2009-10-28 15:29 ` Russ Cox
2009-10-28 15:45 ` Charles Forsyth
2009-10-28 16:14 ` erik quanstrom
2009-10-30 5:45 ` Russ Cox
[not found] <<dd6fe68a0910292245x70f83d7bl8957356abda38201@mail.gmail.com>
2009-10-30 14:11 ` erik quanstrom
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