[Qemu-devel] [PATCH 23/25] qom: add realized property

[Paolo Bonzini <pbonzini@redhat.com>]

Since we had to move the state field from DeviceState to Object, we cannot
delay the implementation of the "realized" property.  The property is
a trigger for two actions that propagate through the composition tree.
"Realize" is called when the property becomes true, and propagates in
pre-order; realize can fail if the values of the properties are not valid.
"Unrealize" is called when the property becomes false, and propagates in
post-order; unrealize cannot fail.

Unrealize is also called by object_deinit, as a separate step before
finalization.

Realize/unrealize is separate from reset.  Reset propagation is a thorny
issue of its own.  We expect classes that care to implement a reset method
and call it from realize or realize_children, depending on whether
pre-order or post-order is more appropriate.

This patch adds four methods (realize, realize_children, unrealize,
unrealize_children) to ObjectClass, together with a default implementation
of realize_children and unrealize_children.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/qemu/object.h |   20 +++++++++++
 qom/object.c          |   93 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)

diff --git a/include/qemu/object.h b/include/qemu/object.h
index 6db376d..6bded2a 100644
--- a/include/qemu/object.h
+++ b/include/qemu/object.h
@@ -245,6 +245,10 @@ struct ObjectClass
 
     /*< public >*/
     Property *props;
+    void (*realize)(Object *obj, struct Error **errp);
+    void (*realize_children)(Object *obj, struct Error **errp);
+    void (*unrealize)(Object *obj);
+    void (*unrealize_children)(Object *obj);
 };
 
 typedef enum ObjectState {
@@ -463,6 +467,22 @@ Object *object_new_with_type(Type type);
 void object_delete(Object *obj);
 
 /**
+ * object_realize_children:
+ * @obj: The object whose children should be realized.
+ *
+ * The default implementation of realize_children.
+ */
+void object_realize_children(Object *obj, struct Error **errp);
+
+/**
+ * object_unrealize_children:
+ * @obj: The object whose children should be unrealize.
+ *
+ * The default implementation of unrealize_children.
+ */
+void object_unrealize_children(Object *obj);
+
+/**
  * object_initialize_with_type:
  * @obj: A pointer to the memory to be used for the object.
  * @type: The type of the object to instantiate.
diff --git a/qom/object.c b/qom/object.c
index 3a6b37b..2a3753a 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -259,6 +259,87 @@ static void object_interface_init(Object *obj, InterfaceImpl *iface)
     obj->interfaces = g_slist_prepend(obj->interfaces, iface_obj);
 }
 
+static void object_get_realized(Object *obj, Visitor *v, void *opaque,
+                                const char *name, Error **errp)
+{
+    bool value = object_is_realized(obj);
+
+    visit_type_bool(v, &value, name, errp);
+}
+
+static void object_unrealize(Object *obj)
+{
+    ObjectClass *klass = object_get_class(obj);
+
+    if (klass->unrealize_children) {
+        klass->unrealize_children(obj);
+    }
+    if (obj->state != OBJECT_STATE_CREATED && klass->unrealize) {
+        klass->unrealize(obj);
+    }
+    obj->state = OBJECT_STATE_CREATED;
+}
+
+static int object_unrealize_1(Object *obj, void *unused)
+{
+    object_unrealize(obj);
+    return 0;
+}
+
+void object_unrealize_children(Object *obj)
+{
+    object_child_foreach(obj, object_unrealize_1, NULL);
+}
+
+static void object_realize(Object *obj, Error **errp)
+{
+    ObjectClass *klass = object_get_class(obj);
+
+    if (obj->state != OBJECT_STATE_REALIZED && klass->realize) {
+        klass->realize(obj, errp);
+    }
+    obj->state = OBJECT_STATE_REALIZED;
+    if (klass->realize_children) {
+        klass->realize_children(obj, errp);
+    }
+}
+
+static int object_realize_1(Object *obj, void *errp)
+{
+    Error *err = NULL;
+    object_realize(obj, &err);
+    if (err) {
+        error_propagate((Error **)errp, err);
+        return 1;
+    }
+
+    return 0;
+}
+
+void object_realize_children(Object *obj, Error **errp)
+{
+    object_child_foreach(obj, object_realize_1, errp);
+}
+
+static void object_set_realized(Object *obj, Visitor *v, void *opaque,
+                                const char *name, Error **errp)
+{
+    bool value;
+    Error *err = NULL;
+
+    visit_type_bool(v, &value, name, &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
+    }
+
+    if (value) {
+        object_realize(obj, errp);
+    } else {
+        object_unrealize(obj);
+    }
+}
+
 static void object_init_with_type(Object *obj, TypeImpl *ti)
 {
     int i;
@@ -337,6 +418,8 @@ void object_unparent(Object *obj)
 
 static void object_deinit(Object *obj, TypeImpl *type)
 {
+    object_property_set_bool(obj, false, "realized", NULL);
+
     if (type->instance_finalize) {
         type->instance_finalize(obj);
     }
@@ -1239,7 +1322,10 @@ static void object_instance_init(Object *obj)
     Property *prop;
 
     object_property_add_str(obj, "type", qdev_get_type, NULL, NULL);
+
     obj->state = OBJECT_STATE_CREATED;
+    object_property_add(obj, "realized", "bool", object_get_realized,
+                        object_set_realized, NULL, NULL, NULL);
 
     class = object_get_class(obj);
     do {
@@ -1250,6 +1336,12 @@ static void object_instance_init(Object *obj)
     } while (class != object_class_by_name(TYPE_OBJECT));
 }
 
+static void object_class_init(ObjectClass *klass, void *class_data)
+{
+    klass->realize_children = object_realize_children;
+    klass->unrealize_children = object_unrealize_children;
+}
+
 static void register_types(void)
 {
     static TypeInfo interface_info = {
@@ -1262,6 +1354,7 @@ static void register_types(void)
         .name = TYPE_OBJECT,
         .instance_size = sizeof(Object),
         .class_base_init = object_class_base_init,
+        .class_init = object_class_init,
         .instance_init = object_instance_init,
         .abstract = true,
     };
-- 
1.7.9.3