qom: Replace object property list with GHashTable

ARM GICv3 systems with large number of CPUs create lots of IRQ pins. Since
every pin is represented as a property, number of these properties becomes
very large. Every property add first makes sure there's no duplicates.
Traversing the list becomes very slow, therefore QEMU initialization takes
significant time (several seconds for e. g. 16 CPUs).

This patch replaces list with GHashTable, making lookup very fast. The only
drawback is that object_child_foreach() and object_child_foreach_recursive()
cannot add or remove properties during traversal, since GHashTableIter does
not have modify-safe version. However, the code seems not to modify objects
via these functions.

Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Tested-by: Pavel Fedin <p.fedin@samsung.com>
[AF: Fixed object_property_del_{all,child}() issues;
     g_hash_table_contains() -> g_hash_table_lookup(), suggested by Daniel]
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

1 files changed, 7 insertions, 3 deletions

diff --git a/include/qom/object.h b/include/qom/object.h
index 9f703140bd..f172fea0b6 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -344,8 +344,6 @@ typedef struct ObjectProperty
     ObjectPropertyResolve *resolve;
     ObjectPropertyRelease *release;
     void *opaque;
-
-    QTAILQ_ENTRY(ObjectProperty) node;
 } ObjectProperty;
 
 /**
@@ -405,7 +403,7 @@ struct Object
     /*< private >*/
     ObjectClass *class;
     ObjectFree *free;
-    QTAILQ_HEAD(, ObjectProperty) properties;
+    GHashTable *properties;
     uint32_t ref;
     Object *parent;
 };
@@ -1537,6 +1535,9 @@ void object_property_set_description(Object *obj, const char *name,
  * Call @fn passing each child of @obj and @opaque to it, until @fn returns
  * non-zero.
  *
+ * It is forbidden to add or remove children from @obj from the @fn
+ * callback.
+ *
  * Returns: The last value returned by @fn, or 0 if there is no child.
  */
 int object_child_foreach(Object *obj, int (*fn)(Object *child, void *opaque),
@@ -1552,6 +1553,9 @@ int object_child_foreach(Object *obj, int (*fn)(Object *child, void *opaque),
  * non-zero. Calls recursively, all child nodes of @obj will also be passed
  * all the way down to the leaf nodes of the tree. Depth first ordering.
  *
+ * It is forbidden to add or remove children from @obj (or its
+ * child nodes) from the @fn callback.
+ *
  * Returns: The last value returned by @fn, or 0 if there is no child.
  */
 int object_child_foreach_recursive(Object *obj,