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Add type_data_ref_U() and use it in g_type_class_ref()

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The function returns TRUE if the type was previously initialized and can
be easily reused. It returns FALSE and does not take a reference if the
type is not referenced yet.

g_type_class_ref() uses this to avoid taking locks in the common path,
which speeds up object creation a lot - in particular in multithreaded
applications.

https://bugzilla.gnome.org/show_bug.cgi?id=585375
This commit is contained in:
Edward Hervey 2009-09-24 12:42:49 +02:00 committed by Alexander Larsson
parent 5160175656
commit 35c376a8a6
1 changed files with 42 additions and 20 deletions
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48
gobject/gtype.c
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@ -1203,6 +1203,21 @@ type_data_ref_Wm (TypeNode *node)
} }
} }
static inline gboolean
type_data_ref_U (TypeNode *node)
{
guint current;
do {
current = NODE_REFCOUNT (node);
if (current < 1)
return FALSE;
} while (!g_atomic_int_compare_and_exchange ((int *) &node->ref_count, current, current + 1));
return TRUE;
}
static gboolean static gboolean
iface_node_has_available_offset_L (TypeNode *iface_node, iface_node_has_available_offset_L (TypeNode *iface_node,
int offset, int offset,
@ -2816,6 +2831,8 @@ g_type_class_ref (GType type)
{ {
TypeNode *node; TypeNode *node;
GType ptype; GType ptype;
gboolean holds_ref;
GTypeClass *pclass;
/* optimize for common code path */ /* optimize for common code path */
node = lookup_type_node_I (type); node = lookup_type_node_I (type);
@ -2826,34 +2843,39 @@ g_type_class_ref (GType type)
return NULL; return NULL;
} }
G_WRITE_LOCK (&type_rw_lock); if (G_LIKELY (type_data_ref_U (node)))
type_data_ref_Wm (node);
if (g_atomic_int_get (&node->data->class.init_state) == INITIALIZED)
{ {
G_WRITE_UNLOCK (&type_rw_lock); if (G_LIKELY (g_atomic_int_get (&node->data->class.init_state) == INITIALIZED))
return node->data->class.class; return node->data->class.class;
holds_ref = TRUE;
} }
ptype = NODE_PARENT_TYPE (node); else
G_WRITE_UNLOCK (&type_rw_lock); holds_ref = FALSE;
g_static_rec_mutex_lock (&class_init_rec_mutex); /* required locking order: 1) class_init_rec_mutex, 2) type_rw_lock */
/* here, we either have node->data->class.class == NULL, or a recursive /* here, we either have node->data->class.class == NULL, or a recursive
* call to g_type_class_ref() with a partly initialized class, or * call to g_type_class_ref() with a partly initialized class, or
* node->data->class.init_state == INITIALIZED, because any * node->data->class.init_state == INITIALIZED, because any
* concurrently running initialization was guarded by class_init_rec_mutex. * concurrently running initialization was guarded by class_init_rec_mutex.
*/ */
if (!node->data->class.class) /* class uninitialized */ g_static_rec_mutex_lock (&class_init_rec_mutex); /* required locking order: 1) class_init_rec_mutex, 2) type_rw_lock */
{
/* we need an initialized parent class for initializing derived classes */ /* we need an initialized parent class for initializing derived classes */
GTypeClass *pclass = ptype ? g_type_class_ref (ptype) : NULL; ptype = NODE_PARENT_TYPE (node);
pclass = ptype ? g_type_class_ref (ptype) : NULL;
G_WRITE_LOCK (&type_rw_lock); G_WRITE_LOCK (&type_rw_lock);
if (node->data->class.class) /* class was initialized during parent class initialization? */
INVALID_RECURSION ("g_type_plugin_*", node->plugin, NODE_NAME (node)); if (!holds_ref)
type_data_ref_Wm (node);
if (!node->data->class.class) /* class uninitialized */
type_class_init_Wm (node, pclass); type_class_init_Wm (node, pclass);
G_WRITE_UNLOCK (&type_rw_lock); G_WRITE_UNLOCK (&type_rw_lock);
if (pclass) if (pclass)
g_type_class_unref (pclass); g_type_class_unref (pclass);
}
g_static_rec_mutex_unlock (&class_init_rec_mutex); g_static_rec_mutex_unlock (&class_init_rec_mutex);
return node->data->class.class; return node->data->class.class;