Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!pt.cs.cmu.edu!andrew.cmu.edu!<UNAUTHENTICATED>+
From: Richard.Draves@CS.CMU.EDU
Newsgroups: comp.os.mach
Subject: Re: timeout on condition_wait()
Message-ID: <sZstG8u00hYPAk2O5m@cs.cmu.edu>
Date: 22 Feb 90 07:28:08 GMT
References: <375@kgw2.bwi.WEC.COM>
Distribution: usa
Organization: Carnegie Mellon, Pittsburgh, PA
Lines: 18
In-Reply-To: <375@kgw2.bwi.WEC.COM>

Excerpts from netnews.comp.os.mach: 16-Feb-90 timeout on
condition_wait() Eric Hammond@kgw2.bwi.WE (2340)

> ===> I want to do a condition_wait() with a timeout. <===

I would solve this problem by developing a new abstract data type,
timer_condition_t.  Export operations like timer_condition_signal,
timer_condition_broadcast, timer_condition_wait (which takes a timeout).

The question then is how to implement the ADT.  One possibility is to
have a service thread that is responsible for waking up timed-out
sleepers.  The service thread would have a queue of wait events.  Each
wait event would also be on a list tied to the timer_condition_t.  The
wait event would contain a normal condition_t that is used to do the
actual sleeps/wakeups; each sleeping cthread would have its own wait
event.  And of course you'd need appropriate locking.

Rich