xge_queue_item_data
void* xge_queue_item_data(xge_queue_item_t *item);
xge_os_memcpy(xge_queue_item_data(item), xge_queue_item_data(elem),
xge_os_memcpy(xge_queue_item_data(elem), data, data_size);
void *item_data = xge_queue_item_data(item);