From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
Subject: Re: [9fans] locking
From: "Russ Cox" <rsc@swtch.com>
Date: Wed, 18 Apr 2007 12:35:42 -0400
In-Reply-To: <93f386afe6d3798ebd79035d9675a65d@quintile.net>
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Message-Id: <20070418163542.D1D3B1E8C3A@holo.morphisms.net>
Topicbox-Message-UUID: 4c0a9ce6-ead2-11e9-9d60-3106f5b1d025

> I want to run this multithreaded, but the requests
> and replies are not atomic on the same file descriptor.
> Thus I need to have each thread request on its own file
> descriptor, or, have a Qlock in the requesting program
> to interlock requests and replies.

does the synethetic file protocol have request ids so that
it can allow multiple outstanding requests
and can send replies out-of-order?

if so, then you need only multiplex the requests onto
the synthetic file.  see libmux in the p9p distribution
for a simple encapsulation of the relevant logic.

if not, then you really need one fd per active request.
you could use a cache of already-opened fds; 
that would only grow to the number of active requests,
not the number of threads.

russ