From e25370368e98e6d8766e50b7f13e3543e1c3ef9b Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 9 Sep 2013 14:28:12 +0200 Subject: [PATCH 21/38] qapi: Flat unions with arbitrary discriminator RH-Author: Kevin Wolf Message-id: <1378736903-18489-22-git-send-email-kwolf@redhat.com> Patchwork-id: 54208 O-Subject: [RHEL-7.0 qemu-kvm PATCH 21/32] qapi: Flat unions with arbitrary discriminator Bugzilla: 1005818 RH-Acked-by: Fam Zheng RH-Acked-by: Max Reitz RH-Acked-by: Miroslav Rezanina Bugzilla: 1005818 Instead of the rather verbose syntax that distinguishes base and subclass fields... { "type": "file", "read-only": true, "data": { "filename": "test" } } ...we can now have both in the same namespace, allowing a more direct mapping of the command line, and moving fields between the common base and subclasses without breaking the API: { "driver": "file", "read-only": true, "filename": "test" } Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake (cherry picked from commit 50f2bdc75c5ee00617ad874c9ceac2cea660aa1e) Signed-off-by: Kevin Wolf --- docs/qapi-code-gen.txt | 22 ++++++++++++ scripts/qapi-types.py | 11 ++++-- scripts/qapi-visit.py | 90 +++++++++++++++++++++++++++++++++++++------------- 3 files changed, 98 insertions(+), 25 deletions(-) Signed-off-by: Miroslav Rezanina --- docs/qapi-code-gen.txt | 22 ++++++++++++ scripts/qapi-types.py | 11 +++++- scripts/qapi-visit.py | 90 +++++++++++++++++++++++++++++++++++------------ 3 files changed, 98 insertions(+), 25 deletions(-) diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt index f6f8d33..11f19cf 100644 --- a/docs/qapi-code-gen.txt +++ b/docs/qapi-code-gen.txt @@ -103,6 +103,28 @@ And it looks like this on the wire: "data" : { "backing-file": "/some/place/my-image", "lazy-refcounts": true } } + +Flat union types avoid the nesting on the wire. They are used whenever a +specific field of the base type is declared as the discriminator ('type' is +then no longer generated). The discriminator must always be a string field. +The above example can then be modified as follows: + + { 'type': 'BlockdevCommonOptions', + 'data': { 'driver': 'str', 'readonly': 'bool' } } + { 'union': 'BlockdevOptions', + 'base': 'BlockdevCommonOptions', + 'discriminator': 'driver', + 'data': { 'raw': 'RawOptions', + 'qcow2': 'Qcow2Options' } } + +Resulting in this JSON object: + + { "driver": "qcow2", + "readonly": false, + "backing-file": "/some/place/my-image", + "lazy-refcounts": true } + + === Commands === Commands are defined by using a list containing three members. The first diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py index c0684a7..f139bfe 100644 --- a/scripts/qapi-types.py +++ b/scripts/qapi-types.py @@ -135,7 +135,9 @@ def generate_union(expr): name = expr['union'] typeinfo = expr['data'] + base = expr.get('base') + discriminator = expr.get('discriminator') ret = mcgen(''' struct %(name)s @@ -158,8 +160,13 @@ struct %(name)s ''') if base: - struct = find_struct(base) - ret += generate_struct_fields(struct['data']) + base_fields = find_struct(base)['data'] + if discriminator: + base_fields = base_fields.copy() + del base_fields[discriminator] + ret += generate_struct_fields(base_fields) + else: + assert not discriminator ret += mcgen(''' }; diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py index be56ba4..b1c1ad6 100644 --- a/scripts/qapi-visit.py +++ b/scripts/qapi-visit.py @@ -17,8 +17,30 @@ import os import getopt import errno -def generate_visit_struct_fields(field_prefix, members): +def generate_visit_struct_fields(name, field_prefix, fn_prefix, members): + substructs = [] ret = '' + full_name = name if not fn_prefix else "%s_%s" % (name, fn_prefix) + + for argname, argentry, optional, structured in parse_args(members): + if structured: + if not fn_prefix: + nested_fn_prefix = argname + else: + nested_fn_prefix = "%s_%s" % (fn_prefix, argname) + + nested_field_prefix = "%s%s." % (field_prefix, argname) + ret += generate_visit_struct_fields(name, nested_field_prefix, + nested_fn_prefix, argentry) + + ret += mcgen(''' + +static void visit_type_%(full_name)s_fields(Visitor *m, %(name)s ** obj, Error **errp) +{ + Error *err = NULL; +''', + name=name, full_name=full_name) + push_indent() for argname, argentry, optional, structured in parse_args(members): if optional: @@ -31,7 +53,7 @@ if (obj && (*obj)->%(prefix)shas_%(c_name)s) { push_indent() if structured: - ret += generate_visit_struct_body(field_prefix + argname, argname, argentry) + ret += generate_visit_struct_body(full_name, argname, argentry) else: ret += mcgen(''' visit_type_%(type)s(m, obj ? &(*obj)->%(c_prefix)s%(c_name)s : NULL, "%(name)s", &err); @@ -47,6 +69,12 @@ visit_type_%(type)s(m, obj ? &(*obj)->%(c_prefix)s%(c_name)s : NULL, "%(name)s", visit_end_optional(m, &err); ''') + pop_indent() + ret += mcgen(''' + + error_propagate(errp, err); +} +''') return ret @@ -56,8 +84,9 @@ if (!error_is_set(errp)) { ''') push_indent() + full_name = name if not field_prefix else "%s_%s" % (field_prefix, name) + if len(field_prefix): - field_prefix = field_prefix + "." ret += mcgen(''' Error **errp = &err; /* from outer scope */ Error *err = NULL; @@ -74,20 +103,14 @@ visit_start_struct(m, (void **)obj, "%(name)s", name, sizeof(%(name)s), &err); ret += mcgen(''' if (!err) { if (!obj || *obj) { -''') - push_indent() - push_indent() - - ret += generate_visit_struct_fields(field_prefix, members) - pop_indent() - ret += mcgen(''' - error_propagate(errp, err); - err = NULL; -} -''') + visit_type_%(name)s_fields(m, obj, &err); + error_propagate(errp, err); + err = NULL; + } +''', + name=full_name) pop_indent() - pop_indent() ret += mcgen(''' /* Always call end_struct if start_struct succeeded. */ visit_end_struct(m, &err); @@ -98,7 +121,9 @@ if (!err) { return ret def generate_visit_struct(name, members): - ret = mcgen(''' + ret = generate_visit_struct_fields(name, "", "", members) + + ret += mcgen(''' void visit_type_%(name)s(Visitor *m, %(name)s ** obj, const char *name, Error **errp) { @@ -157,9 +182,17 @@ def generate_visit_union(expr): members = expr['data'] base = expr.get('base') + discriminator = expr.get('discriminator') ret = generate_visit_enum('%sKind' % name, members.keys()) + if base: + base_fields = find_struct(base)['data'] + if discriminator: + base_fields = base_fields.copy() + del base_fields[discriminator] + ret += generate_visit_struct_fields(name, "", "", base_fields) + ret += mcgen(''' void visit_type_%(name)s(Visitor *m, %(name)s ** obj, const char *name, Error **errp) @@ -179,23 +212,34 @@ void visit_type_%(name)s(Visitor *m, %(name)s ** obj, const char *name, Error ** push_indent() if base: - struct = find_struct(base) - push_indent() - ret += generate_visit_struct_fields("", struct['data']) - pop_indent() + ret += mcgen(''' + visit_type_%(name)s_fields(m, obj, &err); +''', + name=name) pop_indent() ret += mcgen(''' - visit_type_%(name)sKind(m, &(*obj)->kind, "type", &err); + visit_type_%(name)sKind(m, &(*obj)->kind, "%(type)s", &err); if (!err) { switch ((*obj)->kind) { ''', - name=name) + name=name, type="type" if not discriminator else discriminator) for key in members: + if not discriminator: + fmt = 'visit_type_%(c_type)s(m, &(*obj)->%(c_name)s, "data", &err);' + else: + fmt = '''visit_start_implicit_struct(m, (void**) &(*obj)->%(c_name)s, sizeof(%(c_type)s), &err); + if (!err) { + visit_type_%(c_type)s_fields(m, &(*obj)->%(c_name)s, &err); + error_propagate(errp, err); + err = NULL; + visit_end_implicit_struct(m, &err); + }''' + ret += mcgen(''' case %(abbrev)s_KIND_%(enum)s: - visit_type_%(c_type)s(m, &(*obj)->%(c_name)s, "data", &err); + ''' + fmt + ''' break; ''', abbrev = de_camel_case(name).upper(), -- 1.7.1