def __create_context(self, main_root):
		context_dir = os.path.join(main_root, 'context')
		safe_mkdir(context_dir)

		action_default = {}
		for unit, param in self.__task.data['workflow'].items():
			action_default[unit] = self.__action_mgr.default_config(param['type'])

		navigators = self.__config_mgr.navigator()
		context_format = self.__navigator_mgr.context_format(navigators)

		self.__context_mgr.create_context_file(self.__task.data, action_default, context_format, context_dir)
def _get_or_create_cached_value(self, key, getter, ttl=None):
        # happy path
        try:
            expiry, value = self._cache[key]
        except KeyError:
            pass
        else:
            if expiry is None or time.time() < expiry:
                logger.debug("Key %s from cache", key)
                return value
            logger.debug("Cache for key %s has expired", key)

        # get value
        value = getter()
        if ttl:
            expiry = time.time() + ttl
        else:
            expiry = None
        self._cache[key] = (expiry, value)
        logger.debug("Set cache for key %s", key)

        return value