From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:38938) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SlgyC-0005qZ-NG for qemu-devel@nongnu.org; Mon, 02 Jul 2012 09:47:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Slgy6-0000tV-LJ for qemu-devel@nongnu.org; Mon, 02 Jul 2012 09:47:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33923) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Slgy6-0000tA-DC for qemu-devel@nongnu.org; Mon, 02 Jul 2012 09:47:10 -0400 Date: Mon, 2 Jul 2012 10:47:39 -0300 From: Luiz Capitulino Message-ID: <20120702104739.4358bf61@doriath.home> In-Reply-To: <4FF1987C.8010304@codemonkey.ws> References: <20120613144910.598bfe24@doriath.home> <4FDB6869.1000509@us.ibm.com> <20120615170350.GO16777@redhat.com> <4FDF7418.9070206@codemonkey.ws> <20120619101229.52273d97@doriath.home> <20120620144838.2abb5a4f@doriath.home> <20120621124219.GQ21124@redhat.com> <20120625165651.31f9e0bd@doriath.home> <20120626093511.GD14451@redhat.com> <4FE9E275.40303@codemonkey.ws> <4FF1987C.8010304@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC] Fixing the error failure List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Kevin Wolf , Paolo Bonzini , Markus Armbruster , qemu-devel@nongnu.org On Mon, 02 Jul 2012 07:47:56 -0500 Anthony Liguori wrote: > > So far, there haven't been any calls for a change of the wire protocol. > > Changing all existing errors and repurposing 'desc' is effectively changing the > wire protocol. We're not going to change existing errors and I disagree that making 'desc' a "free" string is an incompatible change, as we note in the spec that it shouldn't be parsed. > > There has been an agreement of sorts that the current "rich errors" have > > been "a failure" (your words). Doesn't mean we all agree on the nature > > of the failure. > > > > Several people pointed out that: > > > > * our "rich" errors are so cumbersome to emit that adoption has been > > slow, > > > > * our "rich" errors' human-readable descriptions lead to piss-poor > > human-readable error messages[*] (pardon my french), and > > > > * the "richness" has no known uses after 2+ years. > > Do you know of *any* QMP user beyond libvirt? Apart from casual people scripting around QMP, no I don't. But that doesn't imply they don't exist. > Let's face it, QMP is a protocol > for libvirt. What it looks like shouldn't be dictated by anything other than > what libvirt wants/needs. > > If libvirt isn't going to do more than look at an error type, then there's no > point in providing more than that. They have asked us to turn 'desc' into a free string and I believe this is a good change. > The real problem we need to solve is not the quality of error messages. > Honestly, we have all of the tools today to improve error messages. > > The problem we need to solve is error propagation because without it, we cannot > have asynchronous commands. We keep ending up with extremely complex/cumbersome > management interfaces that we need to support forever because we still have > out-of-band errors that cannot be associated with a specific QMP command. > > So I don't want to see us focus a bunch of effort on rewriting existing error > users. Is that a hard and fast rule? Of course not. If it makes sense to > tweak an error here and there, that's fine. > > But the problem to solve is killing off error_report. I agree this is an important problem too.