From patchwork Thu Feb 25 23:38:45 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 8427761 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 347DDC0553 for ; Thu, 25 Feb 2016 23:46:40 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 3461220103 for ; Thu, 25 Feb 2016 23:46:39 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3B3A82025B for ; Thu, 25 Feb 2016 23:46:38 +0000 (UTC) Received: from localhost ([::1]:46495 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aZ5cD-0008LH-M1 for patchwork-qemu-devel@patchwork.kernel.org; Thu, 25 Feb 2016 18:46:37 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51363) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aZ5V8-00037V-RN for qemu-devel@nongnu.org; Thu, 25 Feb 2016 18:39:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aZ5V4-0005U5-5M for qemu-devel@nongnu.org; Thu, 25 Feb 2016 18:39:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53977) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aZ5V3-0005Tn-R7 for qemu-devel@nongnu.org; Thu, 25 Feb 2016 18:39:14 -0500 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id 78541C0C426A; Thu, 25 Feb 2016 23:39:13 +0000 (UTC) Received: from red.redhat.com (ovpn-113-105.phx2.redhat.com [10.3.113.105]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u1PNd2No002433; Thu, 25 Feb 2016 18:39:13 -0500 From: Eric Blake To: qemu-devel@nongnu.org Date: Thu, 25 Feb 2016 16:38:45 -0700 Message-Id: <1456443528-13901-17-git-send-email-eblake@redhat.com> In-Reply-To: <1456443528-13901-1-git-send-email-eblake@redhat.com> References: <1456443528-13901-1-git-send-email-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: armbru@redhat.com, Michael Roth Subject: [Qemu-devel] [PATCH v2 16/19] qapi: Allow anonymous base for flat union X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Rather than requiring all flat unions to explicitly create a separate base struct, we can allow the qapi schema to specify the common members via an inline dictionary. This is similar to how commands can specify an inline anonymous type for its 'data', and matches the fact that our code base already has several flat unions that had to create a separate base type that is used nowhere but in the union. The patch also has to tweak things to avoid calling base.c_name() on an implicit type (since implicit types do not have a name); we already have qapi_FOO_base() which does the trick nicely. Now that anonymous bases are legal, we need to rework the flat-union-bad-base negative test (as previously written, it forms what is now valid QAPI; tweak it to now provide coverage of a new error message path), and add a positive test in qapi-schema-test to use an anonymous base. Note that this patch only allows anonymous bases for flat unions; simple unions are enough syntactic sugar that we do not want to burden them further. Meanwhile, it would be easy to modify qapi.py to also allow an anonymous base for structs; however, there is less of a compelling technical reason to do so, since you can always write the struct to directly contain any members that the anonymous base would have mentioned. Signed-off-by: Eric Blake --- v2: rebase onto s/fields/members/ change v1: rebase and rework to use gen_visit_fields_call(), test new error Previously posted as part of qapi cleanup subset F: v6: avoid redundant error check in gen_visit_union(), rebase to earlier gen_err_check() improvements --- scripts/qapi.py | 11 +++++++++-- scripts/qapi-types.py | 12 +++++++----- scripts/qapi-visit.py | 6 +++--- docs/qapi-code-gen.txt | 28 ++++++++++++++-------------- tests/qapi-schema/flat-union-bad-base.err | 2 +- tests/qapi-schema/flat-union-bad-base.json | 5 ++--- tests/qapi-schema/qapi-schema-test.json | 6 +----- tests/qapi-schema/qapi-schema-test.out | 9 ++++----- 8 files changed, 41 insertions(+), 38 deletions(-) diff --git a/scripts/qapi.py b/scripts/qapi.py index 38121c5..7c76442 100644 --- a/scripts/qapi.py +++ b/scripts/qapi.py @@ -329,6 +329,8 @@ class QAPISchemaParser(object): def find_base_members(base): + if isinstance(base, dict): + return base base_struct_define = find_struct(base) if not base_struct_define: return None @@ -562,9 +564,9 @@ def check_union(expr, expr_info): # Else, it's a flat union. else: - # The object must have a string member 'base'. + # The object must have a string or dictionary 'base'. check_type(expr_info, "'base' for union '%s'" % name, - base, allow_metas=['struct']) + base, allow_dict=True, allow_metas=['struct']) if not base: raise QAPIExprError(expr_info, "Flat union '%s' must have a base" @@ -1039,6 +1041,8 @@ class QAPISchemaMember(object): owner = owner[5:] if owner.endswith('-arg'): return '(parameter of %s)' % owner[:-4] + elif owner.endswith('-base'): + return '(base of %s)' % owner[:-5] else: assert owner.endswith('-wrapper') # Unreachable and not implemented @@ -1323,6 +1327,9 @@ class QAPISchema(object): base = expr.get('base') tag_name = expr.get('discriminator') tag_member = None + if isinstance(base, dict): + base = (self._make_implicit_object_type( + name, info, 'base', self._make_members(base, info))) if tag_name: variants = [self._make_variant(key, value) for (key, value) in data.iteritems()] diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py index 1f090e6..161443e 100644 --- a/scripts/qapi-types.py +++ b/scripts/qapi-types.py @@ -72,13 +72,15 @@ struct %(c_name)s { ''', c_name=c_name(name)) - if base: - ret += mcgen(''' + if base and not base.is_empty(): + if not base.is_implicit(): + ret += mcgen(''' /* Members inherited from %(c_name)s: */ ''', - c_name=base.c_name()) + c_name=base.c_name()) ret += gen_struct_members(base.members) - ret += mcgen(''' + if not base.is_implicit(): + ret += mcgen(''' /* Own members: */ ''') ret += gen_struct_members(members) @@ -238,7 +240,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor): def visit_object_type(self, name, info, base, members, variants): self._fwdecl += gen_fwd_object_or_array(name) self.decl += gen_object(name, base, members, variants) - if base: + if base and not base.is_implicit(): self.decl += gen_upcast(name, base) self._gen_type_cleanup(name) diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py index a17ecc1..aa244cd 100644 --- a/scripts/qapi-visit.py +++ b/scripts/qapi-visit.py @@ -34,13 +34,12 @@ void visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp); c_name=c_name(name)) -def gen_visit_members_call(typ, direct_name, implicit_name=None): +def gen_visit_members_call(typ, direct_name, implicit_name): ret = '' assert isinstance(typ, QAPISchemaObjectType) if typ.is_empty(): pass elif typ.is_implicit(): - assert implicit_name assert not typ.variants ret += gen_visit_members(typ.members, prefix=implicit_name) else: @@ -63,7 +62,8 @@ void visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp) c_name=c_name(name)) if base: - ret += gen_visit_members_call(base, '(%s *)obj' % base.c_name()) + ret += gen_visit_members_call(base, 'qapi_%s_base(obj)' % c_name(name), + 'obj->') ret += gen_visit_members(members, prefix='obj->') diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt index 2519c07..1c8f113 100644 --- a/docs/qapi-code-gen.txt +++ b/docs/qapi-code-gen.txt @@ -283,7 +283,7 @@ better than open-coding the field to be type 'str'. === Union types === Usage: { 'union': STRING, 'data': DICT } -or: { 'union': STRING, 'data': DICT, 'base': STRUCT-NAME, +or: { 'union': STRING, 'data': DICT, 'base': STRUCT-NAME-OR-DICT, 'discriminator': ENUM-MEMBER-OF-BASE } Union types are used to let the user choose between several different @@ -319,13 +319,16 @@ an implicit C enum 'NameKind' is created, corresponding to the union the union can be named 'max', as this would collide with the implicit enum. The value for each branch can be of any type. -A flat union definition specifies a struct as its base, and -avoids nesting on the wire. All branches of the union must be -complex types, and the top-level fields of the union dictionary on -the wire will be combination of fields from both the base type and the -appropriate branch type (when merging two dictionaries, there must be -no keys in common). The 'discriminator' field must be the name of an -enum-typed member of the base struct. +A flat union definition avoids nesting on the wire, and specifies a +set of common fields that occur in all variants of the union. The +'base' key must specifiy either a type name (the type must be a +struct, not a union), or a dictionary representing an anonymous type. +All branches of the union must be complex types, and the top-level +fields of the union dictionary on the wire will be combination of +fields from both the base type and the appropriate branch type (when +merging two dictionaries, there must be no keys in common). The +'discriminator' field must be the name of an enum-typed member of the +base struct. The following example enhances the above simple union example by adding a common field 'readonly', renaming the discriminator to @@ -333,10 +336,8 @@ something more applicable, and reducing the number of {} required on the wire: { 'enum': 'BlockdevDriver', 'data': [ 'file', 'qcow2' ] } - { 'struct': 'BlockdevCommonOptions', - 'data': { 'driver': 'BlockdevDriver', 'readonly': 'bool' } } { 'union': 'BlockdevOptions', - 'base': 'BlockdevCommonOptions', + 'base': { 'driver': 'BlockdevDriver', 'readonly': 'bool' }, 'discriminator': 'driver', 'data': { 'file': 'FileOptions', 'qcow2': 'Qcow2Options' } } @@ -354,7 +355,7 @@ code generator can ensure that branches exist for all values of the enum (although the order of the keys need not match the declaration of the enum). In the resulting generated C data types, a flat union is represented as a struct with the base member fields included directly, -and then a union of structures for each branch of the struct. +and then a union of pointers to structures for each branch of the struct. A simple union can always be re-written as a flat union where the base class has a single member named 'type', and where each branch of the @@ -365,10 +366,9 @@ union has a struct with a single member named 'data'. That is, is identical on the wire to: { 'enum': 'Enum', 'data': ['one', 'two'] } - { 'struct': 'Base', 'data': { 'type': 'Enum' } } { 'struct': 'Branch1', 'data': { 'data': 'str' } } { 'struct': 'Branch2', 'data': { 'data': 'int' } } - { 'union': 'Flat', 'base': 'Base', 'discriminator': 'type', + { 'union': 'Flat': 'base': { 'type': 'Enum' }, 'discriminator': 'type', 'data': { 'one': 'Branch1', 'two': 'Branch2' } } diff --git a/tests/qapi-schema/flat-union-bad-base.err b/tests/qapi-schema/flat-union-bad-base.err index 79b8a71..bee24a2 100644 --- a/tests/qapi-schema/flat-union-bad-base.err +++ b/tests/qapi-schema/flat-union-bad-base.err @@ -1 +1 @@ -tests/qapi-schema/flat-union-bad-base.json:9: 'base' for union 'TestUnion' should be a type name +tests/qapi-schema/flat-union-bad-base.json:8: 'string' (member of TestTypeA) collides with 'string' (base of TestUnion) diff --git a/tests/qapi-schema/flat-union-bad-base.json b/tests/qapi-schema/flat-union-bad-base.json index e2e622b..74dd421 100644 --- a/tests/qapi-schema/flat-union-bad-base.json +++ b/tests/qapi-schema/flat-union-bad-base.json @@ -1,5 +1,4 @@ -# we require the base to be an existing struct -# TODO: should we allow an anonymous inline base type? +# we allow anonymous base, but enforce no duplicate keys { 'enum': 'TestEnum', 'data': [ 'value1', 'value2' ] } { 'struct': 'TestTypeA', @@ -7,7 +6,7 @@ { 'struct': 'TestTypeB', 'data': { 'integer': 'int' } } { 'union': 'TestUnion', - 'base': { 'enum1': 'TestEnum', 'kind': 'str' }, + 'base': { 'enum1': 'TestEnum', 'string': 'str' }, 'discriminator': 'enum1', 'data': { 'value1': 'TestTypeA', 'value2': 'TestTypeB' } } diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json index 33e8517..a6989d8 100644 --- a/tests/qapi-schema/qapi-schema-test.json +++ b/tests/qapi-schema/qapi-schema-test.json @@ -75,14 +75,10 @@ 'base': 'UserDefZero', 'data': { 'string': 'str', 'enum1': 'EnumOne' } } -{ 'struct': 'UserDefUnionBase2', - 'base': 'UserDefZero', - 'data': { 'string': 'str', 'enum1': 'QEnumTwo' } } - # this variant of UserDefFlatUnion defaults to a union that uses fields with # allocated types to test corner cases in the cleanup/dealloc visitor { 'union': 'UserDefFlatUnion2', - 'base': 'UserDefUnionBase2', + 'base': { 'string': 'str', 'enum1': 'QEnumTwo' }, 'discriminator': 'enum1', 'data': { 'value1' : 'UserDefC', # intentional forward reference 'value2' : 'UserDefB' } } diff --git a/tests/qapi-schema/qapi-schema-test.out b/tests/qapi-schema/qapi-schema-test.out index 6b97fa5..4ba347e 100644 --- a/tests/qapi-schema/qapi-schema-test.out +++ b/tests/qapi-schema/qapi-schema-test.out @@ -8,6 +8,9 @@ object :obj-EVENT_D-arg member b: str optional=False member c: str optional=True member enum3: EnumOne optional=True +object :obj-UserDefFlatUnion2-base + member string: str optional=False + member enum1: QEnumTwo optional=False object :obj-__org.qemu_x-command-arg member a: __org.qemu_x-EnumList optional=False member b: __org.qemu_x-StructList optional=False @@ -121,7 +124,7 @@ object UserDefFlatUnion case value2: UserDefB case value3: UserDefB object UserDefFlatUnion2 - base UserDefUnionBase2 + base :obj-UserDefFlatUnion2-base tag enum1 case value1: UserDefC case value2: UserDefB @@ -166,10 +169,6 @@ object UserDefUnionBase base UserDefZero member string: str optional=False member enum1: EnumOne optional=False -object UserDefUnionBase2 - base UserDefZero - member string: str optional=False - member enum1: QEnumTwo optional=False object UserDefZero member integer: int optional=False object WrapAlternate