From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=FROM_EXCESS_BASE64, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D045C31E49 for ; Wed, 19 Jun 2019 09:23:06 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CCA06206BF for ; Wed, 19 Jun 2019 09:23:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CCA06206BF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:36068 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdWo4-0007TK-Vx for qemu-devel@archiver.kernel.org; Wed, 19 Jun 2019 05:23:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34124) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdWlV-0004XE-9v for qemu-devel@nongnu.org; Wed, 19 Jun 2019 05:20:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hdWlS-0007kY-Aa for qemu-devel@nongnu.org; Wed, 19 Jun 2019 05:20:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47922) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hdWlN-0007ao-8n for qemu-devel@nongnu.org; Wed, 19 Jun 2019 05:20:17 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C47D0772EE for ; Wed, 19 Jun 2019 09:20:13 +0000 (UTC) Received: from redhat.com (ovpn-112-48.ams2.redhat.com [10.36.112.48]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 47C225C221; Wed, 19 Jun 2019 09:20:12 +0000 (UTC) Date: Wed, 19 Jun 2019 10:20:09 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Kevin Wolf Message-ID: <20190619092009.GD24236@redhat.com> References: <20190617184903.19436-1-armbru@redhat.com> <20190617184903.19436-17-armbru@redhat.com> <20190618090153.GE28525@redhat.com> <20190618103449.GE4296@localhost.localdomain> <87lfxy5b4p.fsf@dusky.pond.sub.org> <20190619091852.GA15551@linux.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190619091852.GA15551@linux.fritz.box> User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Wed, 19 Jun 2019 09:20:13 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PULL 16/16] vl: Deprecate -mon pretty=... for HMP monitors X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Markus Armbruster , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jun 19, 2019 at 11:18:52AM +0200, Kevin Wolf wrote: > Am 19.06.2019 um 08:42 hat Markus Armbruster geschrieben: > > Kevin Wolf writes: > >=20 > > > Am 18.06.2019 um 11:01 hat Daniel P. Berrang=C3=A9 geschrieben: > > >> On Mon, Jun 17, 2019 at 08:49:03PM +0200, Markus Armbruster wrote: > > >> > From: Kevin Wolf > > >> >=20 > > >> > The -mon pretty=3Don|off switch of the -mon option applies only = to QMP > > >> > monitors. It's silently ignored for HMP. Deprecate this combinat= ion so > > >> > that we can make it an error in future versions. > > >>=20 > > >> No objection to merging this PR as is, but how about we extend the > > >> deprecation to QMP too ? > > >>=20 > > >> I was responsible for adding this option back in 2010 and I don't > > >> think I've used it since 2012 when I added pretty printing support > > >> to scripts/qmp/qmp-shell. I struggle to imagine good reasons for > > >> using QMP directly with pretty printing, as opposed to doing it > > >> via qmp-shell or another wrapper tool. > > > > > > qemu-iotests uses it. It doesn't only make the output (and espeical= ly > > > diffs on failure) much more readable, but in fact also avoids very = long > > > lines in the refernce output that used to break patch emails when w= e > > > didn't use pretty printing yet. > > > > > > So let's keep it for QMP, please. > >=20 > > Perhaps we can get rid of it if we find a suitable filter. > >=20 > > Hmm, Python comes with one: "python -m json.tool". It expects just o= ne > > expression, and fails if anything follows: > >=20 > > $ printf '{"execute": "qmp_capabilities"}\n{"execute": "query-ver= sion"}\n' | socat UNIX:/work/armbru/images/test-qmp STDIO | python3 -m js= on.tool > > Extra data: line 2 column 1 (char 134) > >=20 > > To pretty print a sequence of expressions, you have to wrap a loop > > around it: > >=20 > > $ printf '{"execute": "qmp_capabilities"}\n{"execute": "query-ver= sion"}\n' | socat UNIX:/work/armbru/images/test-qmp STDIO | { while read = line; do echo "$line" | python3 -m json.tool; done; } >=20 > Yes, it's doable. It's not a very nice command line, but it does its > job. >=20 > What do we win by removing pretty printing from qemu? We invest some > work doing the patches, reviewing them, etc. and save the whole > complexity of adding a few newlines and spaces to an already existing > string buffer in a single place (qjson.c). >=20 > In exchange, we have to add the above overlong command line to every > qemu-iotests case for which pretty printed QMP is useful, and lose the > ability to just do -qmp-pretty stdio manually (which I do every now and > then) instead of having to dig up the above line in some script to copy > it. >=20 > It doesn't look like a net win to me. >=20 > > I figure we'd want to loop in Python instead of shell. > >=20 > > My point is: pretty-printing is trivial in Python. The case for > > maintaining C code to do it seems weak. >=20 > The pretty printing is fairly trivial in C, too, when you already > generate JSON. The code seems to have been last touched in 2014, and > before that in 2010 when it was introduced. The maintenance burden > doesn't seem to be that bad. >=20 > Removing features that have users can be justified sometimes, but it > does need a justification, in my opinion. I'm fine with keeping the print-printing in QEMU given that you illustrat= ed an existing usage of it I wasn't aware of & its not difficult code to maintain. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberran= ge :| |: https://libvirt.org -o- https://fstop138.berrange.c= om :| |: https://entangle-photo.org -o- https://www.instagram.com/dberran= ge :|