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=-10.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 A9255C433EF for ; Fri, 17 Sep 2021 14:55:50 +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 5CEF360F38 for ; Fri, 17 Sep 2021 14:55:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5CEF360F38 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]:34302 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mRFHJ-0006yn-Ew for qemu-devel@archiver.kernel.org; Fri, 17 Sep 2021 10:55:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42140) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mRFC0-0006pS-To for qemu-devel@nongnu.org; Fri, 17 Sep 2021 10:50:22 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46241) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mRFBz-00060w-1W for qemu-devel@nongnu.org; Fri, 17 Sep 2021 10:50:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631890217; 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=xz/HoEOYThLgiJpePea/6JVoSbGp9+Bf/q/iDV48SZM=; b=b05jNFsWGN8TkQj+TdsXcmWwiPcOPIpE48MpkO5KmzNfmfLpFNf79A1nwDD87K9jFQJYDQ cnzwkjsCx8Dt919rMBfmM+aMgfxzNbFkJFOaA2isSq08TeDPSQkyJ2Xd0jHAq0Z0VxoCvS z51A1y5bF1eU0p/8Glo+7iAQSr6vuZg= 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-249-P_cPlnSqMUmZh3iBVVOWMw-1; Fri, 17 Sep 2021 10:50:15 -0400 X-MC-Unique: P_cPlnSqMUmZh3iBVVOWMw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A9F0684A5E1; Fri, 17 Sep 2021 14:50:14 +0000 (UTC) Received: from angien.pipo.sk (unknown [10.40.208.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 27FC06A904; Fri, 17 Sep 2021 14:49:36 +0000 (UTC) Date: Fri, 17 Sep 2021 16:49:33 +0200 From: Peter Krempa To: Markus Armbruster Subject: Re: [PATCH RFC 1/5] qapi: Enable enum member introspection to show more than name Message-ID: References: <20210915192425.4104210-1-armbru@redhat.com> <20210915192425.4104210-2-armbru@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210915192425.4104210-2-armbru@redhat.com> User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pkrempa@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=pkrempa@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.392, 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: kwolf@redhat.com, vsementsov@virtuozzo.com, berrange@redhat.com, libvir-list@redhat.com, eblake@redhat.com, mdroth@linux.vnet.ibm.com, qemu-devel@nongnu.org, 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" On Wed, Sep 15, 2021 at 21:24:21 +0200, Markus Armbruster wrote: > 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. We should be able to get rid of it > eventually. > > In my testing, output of qemu-system-x86_64's query-qmp-schema > grows by 11% (18.5KiB). I prefer this one. While the schema output grows, nobody is really reading it manually. The implementation in libvirt is very straightforward: https://gitlab.com/pipo.sk/libvirt/-/commit/24f1709cfae72cd765d02dc2124d6c954554ea55 https://gitlab.com/pipo.sk/libvirt/-/commit/5909db9d4994327b3f64d5c329edd4b175495bfe > 2. Like 1, but omit "boring" elements of @member, and empty @member. > > @values does not become redundant. Output of query-qmp-schema > grows only as we make enum members non-boring. This has 2 drawbacks: - we would never get rid of either of those - clients would have to check both, one for whether the member is present and second whether it's non-boring. IMO it's simpler for clients just to prefer the new approach when present as the old is simply a subset. > 3. Versioned query-qmp-schema. > > query-qmp-schema provides either @values or @members. The QMP > client can select which version it wants. At least for libvirt this poses a chicken & egg problem. We'd have to query the schema to see that it has the switch to do the selection and then probe with the modern one.