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 00BBEC282DE for ; Thu, 13 Mar 2025 15:58:38 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tskwP-000164-GE; Thu, 13 Mar 2025 11:57:50 -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 1tskwN-00015R-Rd for qemu-devel@nongnu.org; Thu, 13 Mar 2025 11:57:47 -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 1tskwL-0007Vq-Sn for qemu-devel@nongnu.org; Thu, 13 Mar 2025 11:57:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741881463; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XlIg4zirSIiEmOXchb6QjT/I2WDkuFb2PW1vHYvBfRM=; b=MSWoW2eh8+JY0A0vEuhBNqZnJyXHQmJwUs0xdIKsBW5fzNThi6ObSfAoKrosICY92x2c5J e9LZCpvd9YnQxVS+3uz1U6qoRHOSqKdCCxkuDAN4T9N/SkaZVrQOVzFChRdyLqbAmI8c9v eTCoQZVHBk0VXrYX9fIF1qahYdVonis= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-597-344qb4IMMgu3u91HOdZByg-1; Thu, 13 Mar 2025 11:57:40 -0400 X-MC-Unique: 344qb4IMMgu3u91HOdZByg-1 X-Mimecast-MFC-AGG-ID: 344qb4IMMgu3u91HOdZByg_1741881459 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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 mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5415C1801A1A; Thu, 13 Mar 2025 15:57:38 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.22.74.4]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6E48B1801758; Thu, 13 Mar 2025 15:57:36 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id C629A21E675E; Thu, 13 Mar 2025 16:57:32 +0100 (CET) From: Markus Armbruster To: John Snow Cc: qemu-devel@nongnu.org, Konstantin Kostiuk , Peter Maydell , Eric Blake , qemu-block@nongnu.org, Michael Roth , Kevin Wolf Subject: Re: [PATCH 07/11] docs/qapi_domain: add namespace support to cross-references In-Reply-To: (John Snow's message of "Thu, 13 Mar 2025 11:10:33 -0400") References: <20250313044312.189276-1-jsnow@redhat.com> <20250313044312.189276-8-jsnow@redhat.com> <8734fhe8ag.fsf@pond.sub.org> <87ikod56zf.fsf@pond.sub.org> Date: Thu, 13 Mar 2025 16:57:32 +0100 Message-ID: <87o6y43our.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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 John Snow writes: > On Thu, Mar 13, 2025 at 10:41=E2=80=AFAM Markus Armbruster > wrote: > >> John Snow writes: >> >> > On Thu, Mar 13, 2025 at 2:47=E2=80=AFAM Markus Armbruster wrote: >> > >> >> John Snow writes: >> >> >> >> > This patch does three things: >> >> > >> >> > 1. Record the current namespace context in pending_xrefs so it can = be >> >> > used for link resolution later, >> >> > 2. Pass that recorded namespace context to find_obj() when resolvin= g a >> >> > reference, and >> >> > 3. Wildly and completely rewrite find_obj(). >> >> > >> >> > cross-reference support is expanded to tolerate the presence or abs= ence >> >> > of either namespace or module, and to cope with the presence or abs= ence >> >> > of contextual information for either. >> >> > >> >> > References now work like this: >> >> > >> >> > 1. If the explicit reference target is recorded in the domain's obj= ect >> >> > registry, we link to that target and stop looking. We do this lo= okup >> >> > regardless of how fully qualified the target is, which allows di= rect >> >> > references to modules (which don't have a module component to th= eir >> >> > names) or direct references to definitions that may or may not b= elong >> >> > to a namespace or module. >> >> > >> >> > 2. If contextual information is available from qapi:namespace or >> >> > qapi:module directives, try using those components to find a dir= ect >> >> > match to the implied target name. >> >> > >> >> > 3. If both prior lookups fail, generate a series of regular express= ions >> >> > looking for wildcard matches in order from most to least >> >> > specific. Any explicitly provided components (namespace, module) >> >> > *must* match exactly, but both contextual and entirely omitted >> >> > components are allowed to differ from the search result. Note th= at if >> >> > more than one result is found, Sphinx will emit a warning (a bui= ld >> >> > error for QEMU) and list all of the candidate references. >> >> > >> >> > The practical upshot is that in the large majority of cases, namesp= ace >> >> > and module information is not required when creating simple `refere= nces` >> >> > to definitions from within the same context -- even when identical >> >> > definitions exist in other contexts. >> >> >> >> Can you illustrate this this examples? >> >> >> > >> > do wha? >> >> Sorry, I went into the curve too fast. >> >> The stuff under "References now work like this" confuses me. I guess it >> describes a series of lookups to try one after the other. >> >> I understand a cross-reference consists of namespace (optional), module >> (optional), name, and role. >> >> Let's assume role is "any" for simplicity's sake. >> >> Regarding "1. If the explicit ...": >> >> What is a reference's "explicit reference target"? Examples might >> help me understand. >> > > explicit lookup: `QMP:block-core:block-dirty-bitmap-add` > > If that explicit target matches an object in the object database > *directly*, we match immediately and don't consider other potential > targets. This also applies to things like modules, e.g. `QMP:block-core` > even though the "module" is absent (it IS the module) > > We always search for the explicit target no matter how un/fully qualified > it is. > > >> >> What is "recorded in the domain's object registry"? >> > > domain.objects{} - essentially a record of every ObjectDefinition's > "fullname" - the return value from QAPIDefinition._get_fqn(). > > >> >> Can you show me a reference where this lookup succeeds? >> > > `QMP:block-core` > `QMP:block-core.block-dirty-bitmap-add` So, for this lookup to work, the reference must either be of the form NAMESPACE:MODULE and resolve to that module in that namespace, or of the form NAMESPACE:MODULE:DEFN and resolve to that definition in that module in that namespace. Correct? These a "fully qualified names (FQN)" in your parlance, right? Note that the first form is syntactically indistinguishable from NAMESPACE:DEFN, i.e. a reference to a definition that specifies the namespace, but not the module. If the NAMESPACE:MODULE interpretation resolves, we never try the NAMESPACE:DEFN interpretation, because that happens in later steps. Correct? The first form is fully qualified only if it resolves as FQN. So, whether such a reference is fully qualified is not syntactically decidable. Hmm. >> Regarding "2. If contextual information ...": >> >> I guess "contextual information" is the context established by >> qapi:namespace and qapi:module directives, i.e. the current >> namespace and module, if any. >> > > Yep! > > >> >> If the cross reference lacks a namespace, we substitute the current >> namespace. Same for module. >> >> We then use that "to find a direct match to the implied target >> name". Sounds greek to me. Example(s) might help. >> > > If namespace or module is missing from the link target, we try to fill in > the blanks with the contextual information if present. > > Example, we are in the block-core section of the QEMU QMP reference manual > document and we reference `block-dirty-bitmap-add`. With context, we are > able to assemble a fully qualified name: > "QMP:block-core.block-dirty-bitmap-add`. This matches an item in the > registry directly, so it matches and no further search is performed. We try this lookup only when the reference lacks a namespace and we are "in" a namespace, or when it lacks a module and we are "in" a module. Correct? We then subsitute current namespace / module for the lacking one(s), and try the same lookup as in 1. Correct? If we have a reference of the form MYSTERY, it could either be a reference to module MYSTERY in the current namespace, or to definition MYSTERY in the current namespace and module. How do we decide? >> Regarding "3. If both prior lookups fail ...": >> >> I guess we get here when namespace or module are absent, and >> substituting the current namespace or module doesn't resolve. We >> then substitute a wildcard, so to speak, i.e. look in all namespaces >> / modules, and succeed if we find exactly one resolution. Fair? >> > > More or less, though the mechanics are quite a bit more complex than your > overview (and what I wrote in qapi-domain.rst.) We can get here for a few > reasons: > > (1) We didn't provide a fully qualified target, and we don't have full > context to construct one. For example, we are not "in" a namespace and/or > not "in" a module. This is quite likely to happen when writing simple > references to a definition name from outside of the transmogfrified QAPI > documentation, e.g. from qapi-domain.rst itself, or dirty-bitmaps.rst, et= c. > > (2) We didn't provide a fully qualified target, and we are referencing > something from outside of the local context. For example, we are "in" a > module but we are trying to link to a different module's definition. e.g. > we are in QMP:transaction and we reference `block-dirty-bitmap-add`. The > implied FQN will be QMP:transaction.block-dirty-bitmap.add, which will not > resolve. > > The fuzzy search portion has an order of precedence for how it searches - > and not all searches are tried universally, they are conditional to what > was provided in the reference target and what context is available. > > 1. match against the explicitly provided namespace (module was not > explicitly provided) Look for the name in all of the namespace's modules? > 2. match against the explicitly provided module (namespace was not > explicitly provided) Look for the name in all modules so named in all namespaces? > 3. match against the implied namespace (neither namespace/module was > explicitly provided) ? > 4. match against the implied module (neither namespace/module was > explicitly provided) ? > 5. match against the definition name only, from anywhere (neither > namespace/module was explicitly provided) Look for the name anywhere? I need examples :) > The searches are performed in order: if a search returns zero results, the > next search is tried. If any search returns one or more results, those > results are returned and we stop searching down the list. The priority > order ensures that any explicitly provided information is *always* used to > find a match, but contextually provided information is merely a "hint" and > can be ignored for the sake of a match. > > If find_obj() as a whole returns zero results, Sphinx emits a warning for= a > dangling reference. if find_obj() as a whole returns multiple results, > Sphinx emits a warning for the ambiguous cross-reference. > > QEMU errors out on any such warnings under our normal build settings. > > Clear as mud? Clearer, but not quite mud, yet. > --js > > >> [...] >> >>