+ if (sibling == NULL)
+ {
+ /* We don't use g_list_insert_before() with a NULL sibling because it
+ * would be a O(n) operation and we would need to update manually the tail
+ * pointer.
+ */
+ g_queue_push_tail (queue, data);
+ }
+ else
+ {
+ queue->head = g_list_insert_before (queue->head, sibling, data);
+ queue->length++;
+ }