* A copy can be made with gst_mini_object_copy().
*
* gst_mini_object_is_writable() will return %TRUE when the refcount of the
- * object is exactly 1, meaning the current caller has the only reference to the
- * object. gst_mini_object_make_writable() will return a writable version of the
- * object, which might be a new copy when the refcount was not 1.
+ * object is exactly 1 and there is no parent or a single parent exists and is
+ * writable itself, meaning the current caller has the only reference to the
+ * object. gst_mini_object_make_writable() will return a writable version of
+ * the object, which might be a new copy when the refcount was not 1.
*
* Opaque data can be associated with a #GstMiniObject with
* gst_mini_object_set_qdata() and gst_mini_object_get_qdata(). The data is
#define LOCK_MASK ((SHARE_ONE - 1) - FLAG_MASK)
#define LOCK_FLAG_MASK (SHARE_ONE - 1)
+/* For backwards compatibility reasons we use the
+ * guint and gpointer in the GstMiniObject struct in
+ * a rather complicated way to store the parent(s) and qdata.
+ * Originally the were just the number of qdatas and the qdata.
+ *
+ * The guint is used as an atomic state integer with the following
+ * states:
+ * - Locked: 0, basically a spinlock
+ * - No parent, no qdata: 1 (pointer is NULL)
+ * - One parent: 2 (pointer contains the parent)
+ * - Multiple parents or qdata: 3 (pointer contains a PrivData struct)
+ *
+ * Unless we're in state 3, we always have to move to Locking state
+ * atomically and release that again later to the target state whenever
+ * accessing the pointer. When we're in state 3, we will never move to lower
+ * states again
+ *
+ * FIXME 2.0: We should store this directly inside the struct, possibly
+ * keeping space directly allocated for a couple of parents
+ */
+
+enum
+{
+ PRIV_DATA_STATE_LOCKED = 0,
+ PRIV_DATA_STATE_NO_PARENT = 1,
+ PRIV_DATA_STATE_ONE_PARENT = 2,
+ PRIV_DATA_STATE_PARENTS_OR_QDATA = 3,
+};
+
typedef struct
{
GQuark quark;
GDestroyNotify destroy;
} GstQData;
-#define QDATA(o,i) ((GstQData *)(o)->qdata)[(i)]
+typedef struct
+{
+ /* Atomic spinlock: 1 if locked, 0 otherwise */
+ gint parent_lock;
+ guint n_parents, n_parents_len;
+ GstMiniObject **parents;
+
+ guint n_qdata, n_qdata_len;
+ GstQData *qdata;
+} PrivData;
+
+#define QDATA(q,i) (q->qdata)[(i)]
#define QDATA_QUARK(o,i) (QDATA(o,i).quark)
#define QDATA_NOTIFY(o,i) (QDATA(o,i).notify)
#define QDATA_DATA(o,i) (QDATA(o,i).data)
mini_object->dispose = dispose_func;
mini_object->free = free_func;
- mini_object->n_qdata = 0;
- mini_object->qdata = NULL;
+ g_atomic_int_set ((gint *) & mini_object->priv_uint,
+ PRIV_DATA_STATE_NO_PARENT);
+ mini_object->priv_pointer = NULL;
GST_TRACER_MINI_OBJECT_CREATED (mini_object);
}
*
* MT safe
*
- * Returns: (transfer full): the new mini-object.
+ * Returns: (transfer full) (nullable): the new mini-object if copying is
+ * possible, %NULL otherwise.
*/
GstMiniObject *
gst_mini_object_copy (const GstMiniObject * mini_object)
newstate));
}
+/* Locks the priv pointer and sets the priv uint to PRIV_DATA_STATE_LOCKED,
+ * unless the full struct was already stored in the priv pointer.
+ *
+ * Returns the previous state of the priv uint
+ */
+static guint
+lock_priv_pointer (GstMiniObject * object)
+{
+ gint priv_state = g_atomic_int_get ((gint *) & object->priv_uint);
+
+ if (priv_state != PRIV_DATA_STATE_PARENTS_OR_QDATA) {
+ /* As long as the struct was not allocated yet and either someone else
+ * locked it or our priv_state is out of date, try to lock it */
+ while (priv_state != PRIV_DATA_STATE_PARENTS_OR_QDATA &&
+ (priv_state == PRIV_DATA_STATE_LOCKED ||
+ !g_atomic_int_compare_and_exchange ((gint *) & object->priv_uint,
+ priv_state, PRIV_DATA_STATE_LOCKED)))
+ priv_state = g_atomic_int_get ((gint *) & object->priv_uint);
+
+ /* Note that if we got the full struct, we did not store
+ * PRIV_DATA_STATE_LOCKED and did not actually lock the priv pointer */
+ }
+
+ return priv_state;
+}
+
/**
* gst_mini_object_is_writable:
* @mini_object: the mini-object to check
gst_mini_object_is_writable (const GstMiniObject * mini_object)
{
gboolean result;
+ gint priv_state;
g_return_val_if_fail (mini_object != NULL, FALSE);
+ /* Let's first check our own writability. If this already fails there's
+ * no point in checking anything else */
if (GST_MINI_OBJECT_IS_LOCKABLE (mini_object)) {
result = !IS_SHARED (g_atomic_int_get (&mini_object->lockstate));
} else {
result = (GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) == 1);
}
+ if (!result)
+ return result;
+
+ /* We are writable ourselves, but are there parents and are they all
+ * writable too? */
+ priv_state = lock_priv_pointer (GST_MINI_OBJECT_CAST (mini_object));
+
+ /* Now we either have to check the full struct and all the
+ * parents in there, or if there is exactly one parent we
+ * can check that one */
+ if (priv_state == PRIV_DATA_STATE_PARENTS_OR_QDATA) {
+ PrivData *priv_data = mini_object->priv_pointer;
+
+ /* Lock parents */
+ while (!g_atomic_int_compare_and_exchange (&priv_data->parent_lock, 0, 1));
+
+ /* If we have one parent, we're only writable if that parent is writable.
+ * Otherwise if we have multiple parents we are not writable, and if
+ * we have no parent, we are writable */
+ if (priv_data->n_parents == 1)
+ result = gst_mini_object_is_writable (priv_data->parents[0]);
+ else if (priv_data->n_parents == 0)
+ result = TRUE;
+ else
+ result = FALSE;
+
+ /* Unlock again */
+ g_atomic_int_set (&priv_data->parent_lock, 0);
+ } else {
+ if (priv_state == PRIV_DATA_STATE_ONE_PARENT) {
+ result = gst_mini_object_is_writable (mini_object->priv_pointer);
+ } else {
+ g_assert (priv_state == PRIV_DATA_STATE_NO_PARENT);
+ result = TRUE;
+ }
+
+ /* Unlock again */
+ g_atomic_int_set ((gint *) & mini_object->priv_uint, priv_state);
+ }
+
return result;
}
g_return_val_if_fail (mini_object != NULL, NULL);
/* we can't assert that the refcount > 0 since the _free functions
- * increments the refcount from 0 to 1 again to allow resurecting
+ * increments the refcount from 0 to 1 again to allow resurrecting
* the object
g_return_val_if_fail (mini_object->refcount > 0, NULL);
*/
return mini_object;
}
+/* Called with global qdata lock */
static gint
find_notify (GstMiniObject * object, GQuark quark, gboolean match_notify,
GstMiniObjectNotify notify, gpointer data)
{
guint i;
+ gint priv_state = g_atomic_int_get ((gint *) & object->priv_uint);
+ PrivData *priv_data;
- for (i = 0; i < object->n_qdata; i++) {
- if (QDATA_QUARK (object, i) == quark) {
+ if (priv_state != PRIV_DATA_STATE_PARENTS_OR_QDATA)
+ return -1;
+
+ priv_data = object->priv_pointer;
+
+ for (i = 0; i < priv_data->n_qdata; i++) {
+ if (QDATA_QUARK (priv_data, i) == quark) {
/* check if we need to match the callback too */
- if (!match_notify || (QDATA_NOTIFY (object, i) == notify &&
- QDATA_DATA (object, i) == data))
+ if (!match_notify || (QDATA_NOTIFY (priv_data, i) == notify &&
+ QDATA_DATA (priv_data, i) == data))
return i;
}
}
static void
remove_notify (GstMiniObject * object, gint index)
{
+ gint priv_state = g_atomic_int_get ((gint *) & object->priv_uint);
+ PrivData *priv_data;
+
+ g_assert (priv_state == PRIV_DATA_STATE_PARENTS_OR_QDATA);
+ priv_data = object->priv_pointer;
+
/* remove item */
- if (--object->n_qdata == 0) {
+ priv_data->n_qdata--;
+ if (priv_data->n_qdata == 0) {
/* we don't shrink but free when everything is gone */
- g_free (object->qdata);
- object->qdata = NULL;
- } else if (index != object->n_qdata)
- QDATA (object, index) = QDATA (object, object->n_qdata);
+ g_free (priv_data->qdata);
+ priv_data->qdata = NULL;
+ priv_data->n_qdata_len = 0;
+ } else if (index != priv_data->n_qdata) {
+ QDATA (priv_data, index) = QDATA (priv_data, priv_data->n_qdata);
+ }
+}
+
+/* Make sure we allocate the PrivData of this object if not happened yet */
+static void
+ensure_priv_data (GstMiniObject * object)
+{
+ gint priv_state;
+ PrivData *priv_data;
+ GstMiniObject *parent = NULL;
+
+ GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
+ "allocating private data %s miniobject %p",
+ g_type_name (GST_MINI_OBJECT_TYPE (object)), object);
+
+ priv_state = lock_priv_pointer (object);
+ if (priv_state == PRIV_DATA_STATE_PARENTS_OR_QDATA)
+ return;
+
+ /* Now we're either locked, or someone has already allocated the struct
+ * before us and we can just go ahead
+ *
+ * Note: if someone else allocated it in the meantime, we don't have to
+ * unlock as we didn't lock! */
+ if (priv_state != PRIV_DATA_STATE_PARENTS_OR_QDATA) {
+ if (priv_state == PRIV_DATA_STATE_ONE_PARENT)
+ parent = object->priv_pointer;
+
+ object->priv_pointer = priv_data = g_new0 (PrivData, 1);
+
+ if (parent) {
+ priv_data->parents = g_new (GstMiniObject *, 16);
+ priv_data->n_parents_len = 16;
+ priv_data->n_parents = 1;
+ priv_data->parents[0] = parent;
+ }
+
+ /* Unlock */
+ g_atomic_int_set ((gint *) & object->priv_uint,
+ PRIV_DATA_STATE_PARENTS_OR_QDATA);
+ }
}
static void
set_notify (GstMiniObject * object, gint index, GQuark quark,
GstMiniObjectNotify notify, gpointer data, GDestroyNotify destroy)
{
+ PrivData *priv_data;
+
+ ensure_priv_data (object);
+ priv_data = object->priv_pointer;
+
if (index == -1) {
/* add item */
- index = object->n_qdata++;
- object->qdata =
- g_realloc (object->qdata, sizeof (GstQData) * object->n_qdata);
+ index = priv_data->n_qdata++;
+ if (index >= priv_data->n_qdata_len) {
+ priv_data->n_qdata_len *= 2;
+ if (priv_data->n_qdata_len == 0)
+ priv_data->n_qdata_len = 16;
+
+ priv_data->qdata =
+ g_realloc (priv_data->qdata,
+ sizeof (GstQData) * priv_data->n_qdata_len);
+ }
}
- QDATA_QUARK (object, index) = quark;
- QDATA_NOTIFY (object, index) = notify;
- QDATA_DATA (object, index) = data;
- QDATA_DESTROY (object, index) = destroy;
+
+ QDATA_QUARK (priv_data, index) = quark;
+ QDATA_NOTIFY (priv_data, index) = notify;
+ QDATA_DATA (priv_data, index) = data;
+ QDATA_DESTROY (priv_data, index) = destroy;
}
static void
-call_finalize_notify (GstMiniObject * obj)
+free_priv_data (GstMiniObject * obj)
{
guint i;
+ gint priv_state = g_atomic_int_get ((gint *) & obj->priv_uint);
+ PrivData *priv_data;
+
+ if (priv_state != PRIV_DATA_STATE_PARENTS_OR_QDATA) {
+ if (priv_state == PRIV_DATA_STATE_LOCKED) {
+ g_warning
+ ("%s: object finalizing but has locked private data (object:%p)",
+ G_STRFUNC, obj);
+ } else if (priv_state == PRIV_DATA_STATE_ONE_PARENT) {
+ g_warning
+ ("%s: object finalizing but still has parent (object:%p, parent:%p)",
+ G_STRFUNC, obj, obj->priv_pointer);
+ }
- for (i = 0; i < obj->n_qdata; i++) {
- if (QDATA_QUARK (obj, i) == weak_ref_quark)
- QDATA_NOTIFY (obj, i) (QDATA_DATA (obj, i), obj);
- if (QDATA_DESTROY (obj, i))
- QDATA_DESTROY (obj, i) (QDATA_DATA (obj, i));
+ return;
}
+
+ priv_data = obj->priv_pointer;
+
+ for (i = 0; i < priv_data->n_qdata; i++) {
+ if (QDATA_QUARK (priv_data, i) == weak_ref_quark)
+ QDATA_NOTIFY (priv_data, i) (QDATA_DATA (priv_data, i), obj);
+ if (QDATA_DESTROY (priv_data, i))
+ QDATA_DESTROY (priv_data, i) (QDATA_DATA (priv_data, i));
+ }
+ g_free (priv_data->qdata);
+
+ if (priv_data->n_parents)
+ g_warning ("%s: object finalizing but still has %d parents (object:%p)",
+ G_STRFUNC, priv_data->n_parents, obj);
+ g_free (priv_data->parents);
+
+ g_free (priv_data);
}
/**
g_return_if_fail ((g_atomic_int_get (&mini_object->lockstate) & LOCK_MASK)
< 4);
- if (mini_object->n_qdata) {
- call_finalize_notify (mini_object);
- g_free (mini_object->qdata);
- }
+ free_priv_data (mini_object);
+
GST_TRACER_MINI_OBJECT_DESTROYED (mini_object);
if (mini_object->free)
mini_object->free (mini_object);
}
/**
+ * gst_clear_mini_object: (skip)
+ * @object_ptr: a pointer to a #GstMiniObject reference
+ *
+ * Clears a reference to a #GstMiniObject.
+ *
+ * @object_ptr must not be %NULL.
+ *
+ * If the reference is %NULL then this function does nothing.
+ * Otherwise, the reference count of the object is decreased using
+ * gst_mini_object_unref() and the pointer is set to %NULL.
+ *
+ * A macro is also included that allows this function to be used without
+ * pointer casts.
+ *
+ * Since: 1.16
+ **/
+#undef gst_clear_mini_object
+void
+gst_clear_mini_object (GstMiniObject ** object_ptr)
+{
+ g_clear_pointer (object_ptr, gst_mini_object_unref);
+}
+
+/**
* gst_mini_object_replace:
* @olddata: (inout) (transfer full) (nullable): pointer to a pointer to a
* mini-object to be replaced
* Replace the current #GstMiniObject pointer to by @olddata with %NULL and
* return the old value.
*
- * Returns: the #GstMiniObject at @oldata
+ * Returns: (nullable): the #GstMiniObject at @oldata
*/
GstMiniObject *
gst_mini_object_steal (GstMiniObject ** olddata)
G_LOCK (qdata_mutex);
if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1) {
+ PrivData *priv_data = object->priv_pointer;
- old_data = QDATA_DATA (object, i);
- old_notify = QDATA_DESTROY (object, i);
+ old_data = QDATA_DATA (priv_data, i);
+ old_notify = QDATA_DESTROY (priv_data, i);
if (data == NULL)
remove_notify (object, i);
g_return_val_if_fail (quark > 0, NULL);
G_LOCK (qdata_mutex);
- if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1)
- result = QDATA_DATA (object, i);
- else
+ if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1) {
+ PrivData *priv_data = object->priv_pointer;
+ result = QDATA_DATA (priv_data, i);
+ } else {
result = NULL;
+ }
G_UNLOCK (qdata_mutex);
return result;
G_LOCK (qdata_mutex);
if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1) {
- result = QDATA_DATA (object, i);
+ PrivData *priv_data = object->priv_pointer;
+ result = QDATA_DATA (priv_data, i);
remove_notify (object, i);
} else {
result = NULL;
return result;
}
+
+/**
+ * gst_mini_object_add_parent:
+ * @object: a #GstMiniObject
+ * @parent: a parent #GstMiniObject
+ *
+ * This adds @parent as a parent for @object. Having one ore more parents affects the
+ * writability of @object: if a @parent is not writable, @object is also not
+ * writable, regardless of its refcount. @object is only writable if all
+ * the parents are writable and its own refcount is exactly 1.
+ *
+ * Note: This function does not take ownership of @parent and also does not
+ * take an additional reference. It is the responsibility of the caller to
+ * remove the parent again at a later time.
+ *
+ * Since: 1.16
+ */
+void
+gst_mini_object_add_parent (GstMiniObject * object, GstMiniObject * parent)
+{
+ gint priv_state;
+
+ g_return_if_fail (object != NULL);
+
+ GST_CAT_TRACE (GST_CAT_REFCOUNTING, "adding parent %p to object %p", parent,
+ object);
+
+ priv_state = lock_priv_pointer (object);
+ /* If we already had one parent, we need to allocate the full struct now */
+ if (priv_state == PRIV_DATA_STATE_ONE_PARENT) {
+ /* Unlock again */
+ g_atomic_int_set ((gint *) & object->priv_uint, priv_state);
+
+ ensure_priv_data (object);
+ priv_state = PRIV_DATA_STATE_PARENTS_OR_QDATA;
+ }
+
+ /* Now we either have to add the new parent to the full struct, or add
+ * our one and only parent to the pointer field */
+ if (priv_state == PRIV_DATA_STATE_PARENTS_OR_QDATA) {
+ PrivData *priv_data = object->priv_pointer;
+
+ /* Lock parents */
+ while (!g_atomic_int_compare_and_exchange (&priv_data->parent_lock, 0, 1));
+
+ if (priv_data->n_parents >= priv_data->n_parents_len) {
+ priv_data->n_parents_len *= 2;
+ if (priv_data->n_parents_len == 0)
+ priv_data->n_parents_len = 16;
+
+ priv_data->parents =
+ g_realloc (priv_data->parents,
+ priv_data->n_parents_len * sizeof (GstMiniObject *));
+ }
+ priv_data->parents[priv_data->n_parents] = parent;
+ priv_data->n_parents++;
+
+ /* Unlock again */
+ g_atomic_int_set (&priv_data->parent_lock, 0);
+ } else if (priv_state == PRIV_DATA_STATE_NO_PARENT) {
+ object->priv_pointer = parent;
+
+ /* Unlock again */
+ g_atomic_int_set ((gint *) & object->priv_uint, PRIV_DATA_STATE_ONE_PARENT);
+ } else {
+ g_assert_not_reached ();
+ }
+}
+
+/**
+ * gst_mini_object_remove_parent:
+ * @object: a #GstMiniObject
+ * @parent: a parent #GstMiniObject
+ *
+ * This removes @parent as a parent for @object. See
+ * gst_mini_object_add_parent().
+ *
+ * Since: 1.16
+ */
+void
+gst_mini_object_remove_parent (GstMiniObject * object, GstMiniObject * parent)
+{
+ gint priv_state;
+
+ g_return_if_fail (object != NULL);
+
+ GST_CAT_TRACE (GST_CAT_REFCOUNTING, "removing parent %p from object %p",
+ parent, object);
+
+ priv_state = lock_priv_pointer (object);
+
+ /* Now we either have to add the new parent to the full struct, or add
+ * our one and only parent to the pointer field */
+ if (priv_state == PRIV_DATA_STATE_PARENTS_OR_QDATA) {
+ PrivData *priv_data = object->priv_pointer;
+ guint i;
+
+ /* Lock parents */
+ while (!g_atomic_int_compare_and_exchange (&priv_data->parent_lock, 0, 1));
+
+ for (i = 0; i < priv_data->n_parents; i++)
+ if (parent == priv_data->parents[i])
+ break;
+
+ if (i != priv_data->n_parents) {
+ priv_data->n_parents--;
+ if (priv_data->n_parents != i)
+ priv_data->parents[i] = priv_data->parents[priv_data->n_parents];
+ } else {
+ g_warning ("%s: couldn't find parent %p (object:%p)", G_STRFUNC,
+ object, parent);
+ }
+
+ /* Unlock again */
+ g_atomic_int_set (&priv_data->parent_lock, 0);
+ } else if (priv_state == PRIV_DATA_STATE_ONE_PARENT) {
+ if (object->priv_pointer != parent) {
+ g_warning ("%s: couldn't find parent %p (object:%p)", G_STRFUNC,
+ object, parent);
+ /* Unlock again */
+ g_atomic_int_set ((gint *) & object->priv_uint, priv_state);
+ } else {
+ object->priv_pointer = NULL;
+ /* Unlock again */
+ g_atomic_int_set ((gint *) & object->priv_uint,
+ PRIV_DATA_STATE_NO_PARENT);
+ }
+ } else {
+ /* Unlock again */
+ g_atomic_int_set ((gint *) & object->priv_uint, PRIV_DATA_STATE_NO_PARENT);
+ }
+}
projects / platform / upstream / gstreamer.git / blobdiff