qapi: Don't box struct branch of alternate
There's no reason to do two malloc's for an alternate type visiting
a QAPI struct; let's just inline the struct directly as the C union
branch of the struct.
Surprisingly, no clients were actually using the struct member prior
to this patch outside of the testsuite; an earlier patch in the series
added some testsuite coverage to make the effect of this patch more
obvious.
In qapi.py, c_type() gains a new is_unboxed flag to control when we
are emitting a C struct unboxed within the context of an outer
struct (different from our other two modes of usage with no flags
for normal local variable declarations, and with is_param for adding
'const' in a parameter list). I don't know if there is any more
pythonic way of collapsing the two flags into a single parameter,
as we never have a caller setting both flags at once.
Ultimately, we want to also unbox branches for QAPI unions, but as
that touches a lot more client code, it is better as separate
patches. But since unions and alternates share gen_variants(), I
had to hack in a way to test if we are visiting an alternate type
for setting the is_unboxed flag: look for a non-object branch.
This works because alternates have at least two branches, with at
most one object branch, while unions have only object branches.
The hack will go away in a later patch.
The generated code difference to qapi-types.h is relatively small:
| struct BlockdevRef {
| QType type;
| union { /* union tag is @type */
| void *data;
|- BlockdevOptions *definition;
|+ BlockdevOptions definition;
| char *reference;
| } u;
| };
The corresponding spot in qapi-visit.c calls visit_type_FOO(), which
first calls visit_start_struct() to allocate or deallocate the member
and handle a layer of {} from the JSON stream, then visits the
members. To peel off the indirection and the memory management that
comes with it, we inline this call, then suppress allocation /
deallocation by passing NULL to visit_start_struct(), and adjust the
member visit:
| switch ((*obj)->type) {
| case QTYPE_QDICT:
|- visit_type_BlockdevOptions(v, name, &(*obj)->u.definition, &err);
|+ visit_start_struct(v, name, NULL, 0, &err);
|+ if (err) {
|+ break;
|+ }
|+ visit_type_BlockdevOptions_fields(v, &(*obj)->u.definition, &err);
|+ error_propagate(errp, err);
|+ err = NULL;
|+ visit_end_struct(v, &err);
| break;
| case QTYPE_QSTRING:
| visit_type_str(v, name, &(*obj)->u.reference, &err);
The visit of non-object fields is unchanged.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1455778109-6278-13-git-send-email-eblake@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
diff --git a/tests/test-qmp-input-visitor.c b/tests/test-qmp-input-visitor.c
index ef836d5..47cf6aa 100644
--- a/tests/test-qmp-input-visitor.c
+++ b/tests/test-qmp-input-visitor.c
@@ -327,11 +327,11 @@
"'enum1':'value1', 'boolean':true}");
visit_type_UserDefAlternate(v, NULL, &tmp, &error_abort);
g_assert_cmpint(tmp->type, ==, QTYPE_QDICT);
- g_assert_cmpint(tmp->u.udfu->integer, ==, 1);
- g_assert_cmpstr(tmp->u.udfu->string, ==, "str");
- g_assert_cmpint(tmp->u.udfu->enum1, ==, ENUM_ONE_VALUE1);
- g_assert_cmpint(tmp->u.udfu->u.value1->boolean, ==, true);
- g_assert_cmpint(tmp->u.udfu->u.value1->has_a_b, ==, false);
+ g_assert_cmpint(tmp->u.udfu.integer, ==, 1);
+ g_assert_cmpstr(tmp->u.udfu.string, ==, "str");
+ g_assert_cmpint(tmp->u.udfu.enum1, ==, ENUM_ONE_VALUE1);
+ g_assert_cmpint(tmp->u.udfu.u.value1->boolean, ==, true);
+ g_assert_cmpint(tmp->u.udfu.u.value1->has_a_b, ==, false);
qapi_free_UserDefAlternate(tmp);
v = visitor_input_test_init(data, "false");
@@ -355,11 +355,11 @@
"'enum1':'value1', 'boolean':true} }");
visit_type_WrapAlternate(v, NULL, &wrap, &error_abort);
g_assert_cmpint(wrap->alt->type, ==, QTYPE_QDICT);
- g_assert_cmpint(wrap->alt->u.udfu->integer, ==, 1);
- g_assert_cmpstr(wrap->alt->u.udfu->string, ==, "str");
- g_assert_cmpint(wrap->alt->u.udfu->enum1, ==, ENUM_ONE_VALUE1);
- g_assert_cmpint(wrap->alt->u.udfu->u.value1->boolean, ==, true);
- g_assert_cmpint(wrap->alt->u.udfu->u.value1->has_a_b, ==, false);
+ g_assert_cmpint(wrap->alt->u.udfu.integer, ==, 1);
+ g_assert_cmpstr(wrap->alt->u.udfu.string, ==, "str");
+ g_assert_cmpint(wrap->alt->u.udfu.enum1, ==, ENUM_ONE_VALUE1);
+ g_assert_cmpint(wrap->alt->u.udfu.u.value1->boolean, ==, true);
+ g_assert_cmpint(wrap->alt->u.udfu.u.value1->has_a_b, ==, false);
qapi_free_WrapAlternate(wrap);
}
