[Qemu-devel] [PATCH v2] qobject: Replace property list with GHashTable

[Pavel Fedin]

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 modify their objects 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 <address@hidden>
---
v1 => v2:
- Fixed stupid bug in object_unparent(), use correct object
---
 include/qom/object.h |  4 +--
 qmp.c                |  8 +++--
 qom/object.c         | 98 +++++++++++++++++++++++-----------------------------
 vl.c                 |  4 ++-
 4 files changed, 54 insertions(+), 60 deletions(-)

diff --git a/include/qom/object.h b/include/qom/object.h
index be7280c..b100923 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -345,7 +345,7 @@ typedef struct ObjectProperty
     ObjectPropertyRelease *release;
     void *opaque;
 
-    QTAILQ_ENTRY(ObjectProperty) node;
+    Object *obj;
 } ObjectProperty;
 
 /**
@@ -405,7 +405,7 @@ struct Object
     /*< private >*/
     ObjectClass *class;
     ObjectFree *free;
-    QTAILQ_HEAD(, ObjectProperty) properties;
+    GHashTable *properties;
     uint32_t ref;
     Object *parent;
 };
diff --git a/qmp.c b/qmp.c
index 057a7cb..683f427 100644
--- a/qmp.c
+++ b/qmp.c
@@ -207,6 +207,7 @@ ObjectPropertyInfoList *qmp_qom_list(const char *path, 
Error **errp)
     Object *obj;
     bool ambiguous = false;
     ObjectPropertyInfoList *props = NULL;
+    GHashTableIter iter;
     ObjectProperty *prop;
 
     obj = object_resolve_path(path, &ambiguous);
@@ -220,7 +221,8 @@ ObjectPropertyInfoList *qmp_qom_list(const char *path, 
Error **errp)
         return NULL;
     }
 
-    QTAILQ_FOREACH(prop, &obj->properties, node) {
+    g_hash_table_iter_init(&iter, obj->properties);
+    while (g_hash_table_iter_next(&iter, NULL, (gpointer *)&prop)) {
         ObjectPropertyInfoList *entry = g_malloc0(sizeof(*entry));
 
         entry->value = g_malloc0(sizeof(ObjectPropertyInfo));
@@ -499,6 +501,7 @@ DevicePropertyInfoList *qmp_device_list_properties(const 
char *typename,
 {
     ObjectClass *klass;
     Object *obj;
+    GHashTableIter iter;
     ObjectProperty *prop;
     DevicePropertyInfoList *prop_list = NULL;
 
@@ -517,7 +520,8 @@ DevicePropertyInfoList *qmp_device_list_properties(const 
char *typename,
 
     obj = object_new(typename);
 
-    QTAILQ_FOREACH(prop, &obj->properties, node) {
+    g_hash_table_iter_init(&iter, obj->properties);
+    while (g_hash_table_iter_next(&iter, NULL, (gpointer *)&prop)) {
         DevicePropertyInfo *info;
         DevicePropertyInfoList *entry;
 
diff --git a/qom/object.c b/qom/object.c
index 4805328..1c7c42a 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -326,6 +326,20 @@ static void object_post_init_with_type(Object *obj, 
TypeImpl *ti)
     }
 }
 
+static void property_destroy(gpointer data)
+{
+    ObjectProperty *prop = data;
+
+    if (prop->release) {
+        prop->release(prop->obj, prop->name, prop->opaque);
+    }
+
+    g_free(prop->name);
+    g_free(prop->type);
+    g_free(prop->description);
+    g_free(prop);
+}
+
 void object_initialize_with_type(void *data, size_t size, TypeImpl *type)
 {
     Object *obj = data;
@@ -340,7 +354,8 @@ void object_initialize_with_type(void *data, size_t size, 
TypeImpl *type)
     memset(obj, 0, type->instance_size);
     obj->class = type->class;
     object_ref(obj);
-    QTAILQ_INIT(&obj->properties);
+    obj->properties = g_hash_table_new_full(g_str_hash, g_str_equal,
+                                            NULL, property_destroy);
     object_init_with_type(obj, type);
     object_post_init_with_type(obj, type);
 }
@@ -357,40 +372,19 @@ static inline bool 
object_property_is_child(ObjectProperty *prop)
     return strstart(prop->type, "child<", NULL);
 }
 
-static void object_property_del_all(Object *obj)
+static gboolean object_property_del_child(gpointer key, gpointer value,
+                                          gpointer child)
 {
-    while (!QTAILQ_EMPTY(&obj->properties)) {
-        ObjectProperty *prop = QTAILQ_FIRST(&obj->properties);
-
-        QTAILQ_REMOVE(&obj->properties, prop, node);
+    ObjectProperty *prop = value;
 
-        if (prop->release) {
-            prop->release(obj, prop->name, prop->opaque);
-        }
-
-        g_free(prop->name);
-        g_free(prop->type);
-        g_free(prop->description);
-        g_free(prop);
-    }
-}
-
-static void object_property_del_child(Object *obj, Object *child, Error **errp)
-{
-    ObjectProperty *prop;
-
-    QTAILQ_FOREACH(prop, &obj->properties, node) {
-        if (object_property_is_child(prop) && prop->opaque == child) {
-            object_property_del(obj, prop->name, errp);
-            break;
-        }
-    }
+    return object_property_is_child(prop) && prop->opaque == child;
 }
 
 void object_unparent(Object *obj)
 {
     if (obj->parent) {
-        object_property_del_child(obj->parent, obj, NULL);
+        g_hash_table_foreach_remove(obj->parent->properties,
+                                    object_property_del_child, obj);
     }
 }
 
@@ -410,7 +404,7 @@ static void object_finalize(void *data)
     Object *obj = data;
     TypeImpl *ti = obj->class->type;
 
-    object_property_del_all(obj);
+    g_hash_table_unref(obj->properties);
     object_deinit(obj, ti);
 
     g_assert(obj->ref == 0);
@@ -779,10 +773,12 @@ static int do_object_child_foreach(Object *obj,
                                    int (*fn)(Object *child, void *opaque),
                                    void *opaque, bool recurse)
 {
-    ObjectProperty *prop, *next;
+    GHashTableIter iter;
+    ObjectProperty *prop;
     int ret = 0;
 
-    QTAILQ_FOREACH_SAFE(prop, &obj->properties, node, next) {
+    g_hash_table_iter_init(&iter, obj->properties);
+    while (g_hash_table_iter_next(&iter, NULL, (gpointer *)&prop)) {
         if (object_property_is_child(prop)) {
             Object *child = prop->opaque;
 
@@ -879,13 +875,11 @@ object_property_add(Object *obj, const char *name, const 
char *type,
         return ret;
     }
 
-    QTAILQ_FOREACH(prop, &obj->properties, node) {
-        if (strcmp(prop->name, name) == 0) {
-            error_setg(errp, "attempt to add duplicate property '%s'"
+    if (g_hash_table_contains(obj->properties, name)) {
+        error_setg(errp, "attempt to add duplicate property '%s'"
                        " to object (type '%s')", name,
                        object_get_typename(obj));
-            return NULL;
-        }
+        return NULL;
     }
 
     prop = g_malloc0(sizeof(*prop));
@@ -897,8 +891,9 @@ object_property_add(Object *obj, const char *name, const 
char *type,
     prop->set = set;
     prop->release = release;
     prop->opaque = opaque;
+    prop->obj = obj;
 
-    QTAILQ_INSERT_TAIL(&obj->properties, prop, node);
+    g_hash_table_insert(obj->properties, prop->name, prop);
     return prop;
 }
 
@@ -907,10 +902,9 @@ ObjectProperty *object_property_find(Object *obj, const 
char *name,
 {
     ObjectProperty *prop;
 
-    QTAILQ_FOREACH(prop, &obj->properties, node) {
-        if (strcmp(prop->name, name) == 0) {
-            return prop;
-        }
+    prop = g_hash_table_lookup(obj->properties, name);
+    if (prop) {
+        return prop;
     }
 
     error_setg(errp, "Property '.%s' not found", name);
@@ -919,21 +913,11 @@ ObjectProperty *object_property_find(Object *obj, const 
char *name,
 
 void object_property_del(Object *obj, const char *name, Error **errp)
 {
-    ObjectProperty *prop = object_property_find(obj, name, errp);
-    if (prop == NULL) {
+    if (g_hash_table_remove(obj->properties, name)) {
         return;
     }
 
-    if (prop->release) {
-        prop->release(obj, name, prop->opaque);
-    }
-
-    QTAILQ_REMOVE(&obj->properties, prop, node);
-
-    g_free(prop->name);
-    g_free(prop->type);
-    g_free(prop->description);
-    g_free(prop);
+    error_setg(errp, "Property '.%s' not found", name);
 }
 
 void object_property_get(Object *obj, Visitor *v, const char *name,
@@ -1453,11 +1437,13 @@ void object_property_add_const_link(Object *obj, const 
char *name,
 gchar *object_get_canonical_path_component(Object *obj)
 {
     ObjectProperty *prop = NULL;
+    GHashTableIter iter;
 
     g_assert(obj);
     g_assert(obj->parent != NULL);
 
-    QTAILQ_FOREACH(prop, &obj->parent->properties, node) {
+    g_hash_table_iter_init(&iter, obj->parent->properties);
+    while (g_hash_table_iter_next(&iter, NULL, (gpointer *)&prop)) {
         if (!object_property_is_child(prop)) {
             continue;
         }
@@ -1541,11 +1527,13 @@ static Object *object_resolve_partial_path(Object 
*parent,
                                               bool *ambiguous)
 {
     Object *obj;
+    GHashTableIter iter;
     ObjectProperty *prop;
 
     obj = object_resolve_abs_path(parent, parts, typename, 0);
 
-    QTAILQ_FOREACH(prop, &parent->properties, node) {
+    g_hash_table_iter_init(&iter, parent->properties);
+    while (g_hash_table_iter_next(&iter, NULL, (gpointer *)&prop)) {
         Object *found;
 
         if (!object_property_is_child(prop)) {
diff --git a/vl.c b/vl.c
index e211f6a..7065d5f 100644
--- a/vl.c
+++ b/vl.c
@@ -1506,13 +1506,15 @@ MachineInfoList *qmp_query_machines(Error **errp)
 
 static int machine_help_func(QemuOpts *opts, MachineState *machine)
 {
+    GHashTableIter iter;
     ObjectProperty *prop;
 
     if (!qemu_opt_has_help_opt(opts)) {
         return 0;
     }
 
-    QTAILQ_FOREACH(prop, &OBJECT(machine)->properties, node) {
+    g_hash_table_iter_init(&iter, OBJECT(machine)->properties);
+    while (g_hash_table_iter_next(&iter, NULL, (gpointer *)&prop)) {
         if (!prop->set) {
             continue;
         }
-- 
1.9.5.msysgit.0