From owner-freebsd-hackers@FreeBSD.ORG  Wed Nov 12 09:27:51 2003
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 8D6B416A4DB
	for <freebsd-hackers@freebsd.org>;
	Wed, 12 Nov 2003 09:27:51 -0800 (PST)
Received: from mail.netbsd.org (mail.isc.netbsd.org [204.152.185.212])
	by mx1.FreeBSD.org (Postfix) with SMTP id DCD2943FB1
	for <freebsd-hackers@freebsd.org>;
	Wed, 12 Nov 2003 09:27:50 -0800 (PST)
	(envelope-from wrstuden@netbsd.org)
Received: (qmail 11000 invoked by uid 1130); 12 Nov 2003 17:27:50 -0000
Date: Wed, 12 Nov 2003 09:27:50 -0800
From: Bill Studenmund <wrstuden@netbsd.org>
To: Jaromir Dolecek <jdolecek@NetBSD.org>
Message-ID: <20031112172750.GB14368@netbsd.org>
References: <20031110174109.GA13852@monkey.org>
	<200311120858.hAC8wFfg001905@s102-n054.tele2.cz>
Mime-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha1;
	protocol="application/pgp-signature"; boundary="St7VIuEGZ6dlpu13"
Content-Disposition: inline
In-Reply-To: <200311120858.hAC8wFfg001905@s102-n054.tele2.cz>
User-Agent: Mutt/1.4.1i
cc: freebsd-hackers@freebsd.org
cc: tech-kern@NetBSD.org
cc: Niels Provos <provos@monkey.org>
cc: marius@monkey.org
cc: hackers@openbsd.org
Subject: Re: kqueue, NOTE_EOF
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 12 Nov 2003 17:27:51 -0000


--St7VIuEGZ6dlpu13
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Wed, Nov 12, 2003 at 09:58:15AM +0100, Jaromir Dolecek wrote:
> marius aamodt eriksen wrote:
> > hi -=20
> >=20
> > in order to be able to preserve consistent semantics across poll,
> > select, and kqueue (EVFILT_READ), i propose the following change: on
> > EVFILT_READ, add an fflag NOTE_EOF which will return when the file
> > pointer *is* at the end of the file (effectively always returning on
> > EVFILT_READ, but setting the NOTE_EOF flag when it is at the end).
> >=20
> > specifically, this allows libevent[1] to behave consistently across
> > underlying polling infrastructures (this has become a practical
> > issue).
>=20
> I'm not sure I understand what is the exact issue.

I'm only responding to the notes also.

> Why would this be necessary or what does this exactly solve? AFAIK
> poll() doesn't set any flags in this case neither, so I don't
> see how this is inconsistent.

I think the difference is in the default behavior. When you're at EOF, I=20
know that poll() will give you a read-availability event, so you'll read=20
the EOF. Will kqueue?

> BTW, shouldn't the EOF flag be cleared when the file is extended?

Probably.

Take care,

Bill

--St7VIuEGZ6dlpu13
Content-Type: application/pgp-signature
Content-Disposition: inline

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (NetBSD)

iD8DBQE/sm2VWz+3JHUci9cRAn21AJ92dWa5pTIsSiWOXerBOsAjNjYj7ACfZdXH
ZGm/kil/juuS7l/6YyZF6X8=
=8LPL
-----END PGP SIGNATURE-----

--St7VIuEGZ6dlpu13--