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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B21A0C433EF for ; Tue, 12 Oct 2021 10:10:44 +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 220FE60C40 for ; Tue, 12 Oct 2021 10:10:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 220FE60C40 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:38514 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1maEk7-0007jZ-5B for qemu-devel@archiver.kernel.org; Tue, 12 Oct 2021 06:10:43 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49852) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1maEiW-0006tM-6D for qemu-devel@nongnu.org; Tue, 12 Oct 2021 06:09:04 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46577) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1maEiT-0004gt-BF for qemu-devel@nongnu.org; Tue, 12 Oct 2021 06:09:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634033339; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cQQoSt4KmVvQzx0HPP+MGWP8ebimsJpivE+pfEJglDM=; b=PCZtPSK6DUu/y+4KyJ3orWcoF7Zo1PUkdQfnTMjWhrU+zVxw7r8KAoOPnx7xvAideUuuVI Xt11GXz1ttEnwU97Zmy0U77zsCsM7PG67b2C26kENbbci3RHvCj4crNh4iV10RAW4ZlsKl 3qyxnp75OJPpkvhRV5HRS0lzGG0Gskg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-571-go1FiQDtOM-qURTmQIgxkQ-1; Tue, 12 Oct 2021 06:08:56 -0400 X-MC-Unique: go1FiQDtOM-qURTmQIgxkQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 57E958042EF; Tue, 12 Oct 2021 10:08:55 +0000 (UTC) Received: from redhat.com (unknown [10.39.193.219]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CD49F100239F; Tue, 12 Oct 2021 10:08:35 +0000 (UTC) Date: Tue, 12 Oct 2021 12:08:33 +0200 From: Kevin Wolf To: Markus Armbruster Subject: Re: [PATCH v2 1/5] qapi: Enable enum member introspection to show more than name Message-ID: References: <20211009120944.2858887-1-armbru@redhat.com> <20211009120944.2858887-2-armbru@redhat.com> MIME-Version: 1.0 In-Reply-To: <20211009120944.2858887-2-armbru@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.049, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: , Cc: vsementsov@virtuozzo.com, berrange@redhat.com, libvir-list@redhat.com, eblake@redhat.com, mdroth@linux.vnet.ibm.com, qemu-devel@nongnu.org, pkrempa@redhat.com, marcandre.lureau@redhat.com, jsnow@redhat.com, libguestfs@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 09.10.2021 um 14:09 hat Markus Armbruster geschrieben: > The next commit will add feature flags to enum members. There's a > problem, though: query-qmp-schema shows an enum type's members as an > array of member names (SchemaInfoEnum member @values). If it showed > an array of objects with a name member, we could simply add more > members to these objects. Since it's just strings, we can't. > > I can see three ways to correct this design mistake: > > 1. Do it the way we should have done it, plus compatibility goo. > > We want a ['SchemaInfoEnumMember'] member in SchemaInfoEnum. Since > changing @values would be a compatibility break, add a new member > @members instead. > > @values is now redundant. In my testing, output of > qemu-system-x86_64's query-qmp-schema grows by 11% (18.5KiB). > > We can deprecate @values now and drop it later. This will break > outmoded clients. Well-behaved clients such as libvirt are > expected to break cleanly. > > 2. Like 1, but omit "boring" elements of @member, and empty @member. > > @values does not become redundant. @members augments it. Somewhat > cumbersome, but output of query-qmp-schema grows only as we make > enum members non-boring. > > There is nothing to deprecate here. > > 3. Versioned query-qmp-schema. > > query-qmp-schema provides either @values or @members. The QMP > client can select which version it wants. There is no redundant > output. > > We can deprecate old versions and eventually drop them. This will > break outmoded clients. Breaking cleanly is easier than for 1. > > While 1 and 2 operate within the common rules for compatible > evolution apply (section "Compatibility considerations" in > docs/devel/qapi-code-gen.rst), 3 bypasses them. Attractive when > operating within the rules is just too awkward. Not the case here. > > This commit implements 1. Libvirt developers prefer it. > > Signed-off-by: Markus Armbruster > --- > qapi/introspect.json | 21 +++++++++++++++++++-- > scripts/qapi/introspect.py | 18 ++++++++++++++---- > 2 files changed, 33 insertions(+), 6 deletions(-) docs/devel/qapi-code-gen.rst still says: The SchemaInfo for an enumeration type has meta-type "enum" and variant member "values". The values are listed in no particular order; clients must search the entire enum when learning whether a particular value is supported. Example: the SchemaInfo for MyEnum from section `Enumeration types`_ :: { "name": "MyEnum", "meta-type": "enum", "values": [ "value1", "value2", "value3" ] } It probably needs an update. Kevin