From owner-cvs-all Fri Nov 9 15:29:28 2001 Delivered-To: cvs-all@freebsd.org Received: from peter3.wemm.org (c1315225-a.plstn1.sfba.home.com [24.14.150.180]) by hub.freebsd.org (Postfix) with ESMTP id 2012C37B41D; Fri, 9 Nov 2001 15:29:19 -0800 (PST) Received: from overcee.netplex.com.au (overcee.wemm.org [10.0.0.3]) by peter3.wemm.org (8.11.0/8.11.0) with ESMTP id fA9NTIM02875; Fri, 9 Nov 2001 15:29:18 -0800 (PST) (envelope-from peter@wemm.org) Received: from wemm.org (localhost [127.0.0.1]) by overcee.netplex.com.au (Postfix) with ESMTP id 95638380A; Fri, 9 Nov 2001 15:29:18 -0800 (PST) (envelope-from peter@wemm.org) X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: Bill Fenner Cc: bde@zeta.org.au, alfred@FreeBSD.org, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/fs/fifofs fifo_vnops.c In-Reply-To: <200111091803.KAA24774@windsor.research.att.com> Date: Fri, 09 Nov 2001 15:29:18 -0800 From: Peter Wemm Message-Id: <20011109232918.95638380A@overcee.netplex.com.au> Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Bill Fenner wrote: > > POSIX FIFOs seem relatively useless, unless there's always a > writer present. Without a writer, a reader has to spin (either > in select+read or just read) until a writer is present. > > I can't tell if POSIX really defined FIFOs to be useless, or we're just > misinterpreting the standards-speak. I'd prefer if an "empty FIFO with > no writers" was really an "empty FIFO with no writers where the EOF > condition hasn't been delivered yet"; then read() could block (or return > EAGAIN or EWOULDBLOCK) when there were no writers yet, and could go back > to that condition after the EOF of all the writers leaving was delivered. I would prefer something that didn't violate POLA than something that was strictly standards conformant but useless. Being useless certainly violates POLA. :-) Especially when most of the other significant players have decided to go for the 'working' option rather than the compliant-but-useless option. Windows NT's POSIX compatability-box was also in the compliant-but-useless category too. Cheers, -Peter -- Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message