def _autoSave(self):
        """save state into 'autosave' """
        a = 'autoSave'
        path = self.path
        if not path:
            path = self.dir.join('%s.%s' % (a, self.FTYPE))
            self._createdAutosaveFile = path
        self.tmp_dir_save_session = self.tmp_dir_session.join(a).mkdir()
        self._save(a, path)
save state into 'autosave'