From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <e207e6e2919e77c62863069a80f63e21@davidashen.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] qunlock
Date: Thu, 24 Jun 2004 16:02:16 +0500
From: dvd@davidashen.net
In-Reply-To: <ab397ad4f84f44cfed5f8242258a5e3b@plan9.escet.urjc.es>
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>> 	/* canqlock(b); */
>> 	qunlock(b);
> 
> This is very weird for me.
> Can't you rework your scheme to avoid such things?
> Perhaps this code is suggesting that your locking
> conventions may need more work.

That's why I am asking. What exactly is weird? The code actually works
in SPIN (as a model), and in Python (but I check locked() before unlocking).

The purpose is to have multiple producers and consumers on an queue
with exclusive access, with priority always given to consumers if there
are waiting ones and the queue is not empty.

The implementation of qlock/qunlock allows to unlock when not locked;
I am asking whether it is by design or by a coincidence?

David