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authorPaolo Bonzini <pbonzini@redhat.com>2012-02-03 11:57:23 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2012-02-07 13:51:37 +0100
commitacc4af3fec335bb0778456f72bfb2c3591c11da4 (patch)
treec2180829712cd178b4fffdb4f06727be8af4aa41 /qom
parent0815a859492e87e120efa7feaa836ecf6ecffaf7 (diff)
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qom: clean up/optimize object_dynamic_cast
The interface loop can be performed only on the parent object. It does not need to be done on each interface. Similarly, we can simplify the code by switching early from the implementation object to the parent object. Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'qom')
-rw-r--r--qom/object.c62
1 files changed, 38 insertions, 24 deletions
diff --git a/qom/object.c b/qom/object.c
index 4261944..669acc5 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -368,11 +368,9 @@ void object_delete(Object *obj)
g_free(obj);
}
-static bool object_is_type(Object *obj, const char *typename)
+static bool type_is_ancestor(TypeImpl *type, TypeImpl *target_type)
{
- TypeImpl *target_type = type_get_by_name(typename);
- TypeImpl *type = obj->class->type;
- GSList *i;
+ assert(target_type);
/* Check if typename is a direct ancestor of type */
while (type) {
@@ -383,24 +381,50 @@ static bool object_is_type(Object *obj, const char *typename)
type = type_get_parent(type);
}
- /* Check if obj has an interface of typename */
- for (i = obj->interfaces; i; i = i->next) {
- Interface *iface = i->data;
+ return false;
+}
- if (object_is_type(OBJECT(iface), typename)) {
- return true;
- }
- }
+static bool object_is_type(Object *obj, const char *typename)
+{
+ TypeImpl *target_type;
- return false;
+ if (typename == TYPE_OBJECT) {
+ return true;
+ }
+ target_type = type_get_by_name(typename);
+ return type_is_ancestor(obj->class->type, target_type);
}
Object *object_dynamic_cast(Object *obj, const char *typename)
{
GSList *i;
- /* Check if typename is a direct ancestor */
- if (object_is_type(obj, typename)) {
+ /* Check if typename is a direct ancestor. Special-case TYPE_OBJECT,
+ * we want to go back from interfaces to the parent.
+ */
+ if (typename && object_is_type(obj, typename)) {
+ return obj;
+ }
+
+ /* Check if obj is an interface and its containing object is a direct
+ * ancestor of typename. In principle we could do this test at the very
+ * beginning of object_dynamic_cast, avoiding a second call to
+ * object_is_type. However, casting between interfaces is relatively
+ * rare, and object_is_type(obj, TYPE_INTERFACE) would fail almost always.
+ *
+ * Perhaps we could add a magic value to the object header for increased
+ * (run-time) type safety and to speed up tests like this one. If we ever
+ * do that we can revisit the order here.
+ */
+ if (object_is_type(obj, TYPE_INTERFACE)) {
+ assert(!obj->interfaces);
+ obj = INTERFACE(obj)->obj;
+ if (object_is_type(obj, typename)) {
+ return obj;
+ }
+ }
+
+ if (typename == TYPE_OBJECT) {
return obj;
}
@@ -413,16 +437,6 @@ Object *object_dynamic_cast(Object *obj, const char *typename)
}
}
- /* Check if obj is an interface and its containing object is a direct
- * ancestor of typename */
- if (object_is_type(obj, TYPE_INTERFACE)) {
- Interface *iface = INTERFACE(obj);
-
- if (object_is_type(iface->obj, typename)) {
- return iface->obj;
- }
- }
-
return NULL;
}