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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B405BC4332F for ; Fri, 3 Nov 2023 15:57:07 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qywX3-0000Dc-Pt; Fri, 03 Nov 2023 11:56:25 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qywX2-0000D2-0v for qemu-devel@nongnu.org; Fri, 03 Nov 2023 11:56:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qywX0-00033d-4j for qemu-devel@nongnu.org; Fri, 03 Nov 2023 11:56:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699026980; 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=BEjJiIQthPPktbfXOjRgyqU7/620QG5bi24SPV3+O3Q=; b=WGCHEJqNMmpocLcMBV9D2/NRkGVjorM5XlO7trr2VPJgelHSWoTX/DbMuoC+bu1WSLeQ6N by9ZfBYbTkWqMyoBN19nB0ufKDENhWbnmJhGxL5trmhYDN84TkTsBdh7djFd91nlrJhXZn aDVR+gMlaRZSWMnSTo7QvY01s2RY8Tc= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-53-zba0I6HINK2-Pwc3YQNbUQ-1; Fri, 03 Nov 2023 11:56:17 -0400 X-MC-Unique: zba0I6HINK2-Pwc3YQNbUQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D13FB3822E8F; Fri, 3 Nov 2023 15:56:16 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.193.56]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5E98B2166B27; Fri, 3 Nov 2023 15:56:16 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 5205521E6A1F; Fri, 3 Nov 2023 16:56:15 +0100 (CET) From: Markus Armbruster To: Kevin Wolf Cc: Vladimir Sementsov-Ogievskiy , Fiona Ebner , qemu-devel@nongnu.org, qemu-block@nongnu.org, eblake@redhat.com, hreitz@redhat.com, jsnow@redhat.com, den@virtuozzo.com, t.lamprecht@proxmox.com, alexander.ivanov@virtuozzo.com Subject: Re: [PATCH v2 00/10] mirror: allow switching from background to active mode References: <20231009094619.469668-1-f.ebner@proxmox.com> <993bfa5d-1a91-4b32-9bd8-165b7abba4f0@proxmox.com> <99dd287b-816b-4f4f-b156-32f94bbb62c2@yandex-team.ru> <87o7gbyy8w.fsf@pond.sub.org> Date: Fri, 03 Nov 2023 16:56:15 +0100 In-Reply-To: (Kevin Wolf's message of "Fri, 3 Nov 2023 12:54:36 +0100") Message-ID: <87cywqn84g.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.47, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Kevin Wolf writes: > Am 03.11.2023 um 10:36 hat Markus Armbruster geschrieben: >> Vladimir Sementsov-Ogievskiy writes: >> >> > On 11.10.23 13:18, Fiona Ebner wrote: >> >> Am 10.10.23 um 19:55 schrieb Vladimir Sementsov-Ogievskiy: >> >>> On 09.10.23 12:46, Fiona Ebner wrote: >> >>>> >> >>>> Initially, I tried to go for a more general 'job-change' command, but >> >>>> I couldn't figure out a way to avoid mutual inclusion between >> >>>> block-core.json and job.json. >> >>>> >> >>> >> >>> What is the problem with it? I still think that job-change would be better. >> >>> >> >> If going for job-change in job.json, the dependencies would be >> >> job-change -> JobChangeOptions -> JobChangeOptionsMirror -> MirrorCopyMode >> >> query-jobs -> JobInfo -> JobInfoMirror >> >> and we can't include block-core.json in job.json, because an inclusion >> >> loop gives a build error. >> >> Let me try to understand this. >> >> Command job-change needs its argument type JobChangeOptions. >> >> JobChangeOptions is a union, and JobChangeOptionsMirror is one of its >> branches. >> >> JobChangeOptionsMirror needs MirrorCopyMode from block-core.json. >> >> block-core.json needs job.json for JobType and JobStatus. >> >> >> Could be made to work by moving MirrorCopyMode (and >> >> JobChangeOptionsMirror, JobInfoMirror) to job.json or some place that >> >> can be included by both job.json and block-core.json. Moving the >> >> type-specific definitions to the general job.json didn't feel right to >> >> me. Including another file with type-specific definitions in job.json >> >> feels slightly less wrong, but still not quite right and I didn't want >> >> to create a new file just for MirrorCopyMode (and >> >> JobChangeOptionsMirror, JobInfoMirror). >> >> And going further and moving all mirror-related things to a separate >> >> file would require moving along things like NewImageMode with it or >> >> create yet another file for such general things used by multiple block-jobs. >> >> If preferred, I can try and go with some version of the above. >> >> >> > >> > OK, I see the problem. Seems, that all requires some good refactoring. But that's a preexisting big work, and should not hold up your series. I'm OK to proceed with block-job-change. >> >> Saving ourselves some internal refactoring is a poor excuse for >> undesirable external interfaces. > > I'm not sure how undesirable it is. We have block-job-* commands for > pretty much every other operation, so it's only consistent to have > block-job-change, too. Is the job abstraction a failure? We have block-job- command since job- command since ----------------------------------------------------- block-job-set-speed 1.1 block-job-cancel 1.1 job-cancel 3.0 block-job-pause 1.3 job-pause 3.0 block-job-resume 1.3 job-resume 3.0 block-job-complete 1.3 job-complete 3.0 block-job-dismiss 2.12 job-dismiss 3.0 block-job-finalize 2.12 job-finalize 3.0 block-job-change 8.2 query-block-jobs 1.1 query-jobs I was under the impression that we added the (more general) job- commands to replace the (less general) block-job commands, and we're keeping the latter just for compatibility. Am I mistaken? Which one should be used? Why not deprecate the one that shouldn't be used? The addition of block-job-change without even trying to do job-change makes me wonder: have we given up on the job- interface? I'm okay with giving up on failures. All I want is clarity. Right now, I feel thoroughly confused about the status block-jobs and jobs, and how they're related. > Having job-change, too, might be nice in theory, but we don't have even > a potential user for it at this point (i.e. a job type that isn't a > block job, but for which changing options at runtime makes sense). > >> We need to answer two questions before we do that: >> >> 1. How much work would the refactoring be? >> >> 2. Is the interface improvement this enables worth the work? >> >> Let's start with 1. >> >> An obvious solution is to split JobType and JobStatus off job.json to >> break the dependency of block-core.json on job.json. >> >> But I'd like us to investigate another one. block-core.json is *huge*. >> It's almost a quarter of the entire QAPI schema. Can we spin out block >> jobs into block-job.json? Moves the dependency on job.json from >> block-core.json to block-job.json. > > It also makes job.json depend on block-job.json instead of > block-core.json, so you only moved the problem without solving it. block-job.json needs block-core.json and job.json. job.json needs block-core.json. No circle so far.