protected function setup_data() {
		if ( ! $storage = $this->get_storage() ) {
			return;
		}

		$_hash = spl_object_hash( $storage );

		if ( $storage instanceof Deferred_Storage && ! isset( static::$storages_was_read[ $_hash ] ) ) {
			$storage->read();
			static::$storages_was_read[ $_hash ] = true;
		}

		$this->set_value(
			$storage->get( $this->get_map_key() )
		);
	}