from abc import ABCMeta, abstractmethod class VppObject(object): """ Abstract vpp object """ __metaclass__ = ABCMeta def __init__(self): VppObjectRegistry().register(self) @abstractmethod def add_vpp_config(self): """ Add the configuration for this object to vpp. """ pass @abstractmethod def query_vpp_config(self): """Query the vpp configuration. :return: True if the object is configured""" pass @abstractmethod def remove_vpp_config(self): """ Remove the configuration for this object from vpp. """ pass @abstractmethod def object_id(self): """ Return a unique string representing this object. """ pass class VppObjectRegistry(object): """ Class which handles automatic configuration cleanup. """ _shared_state = {} def __init__(self): self.__dict__ = self._shared_state if not hasattr(self, "_object_registry"): self._object_registry = [] if not hasattr(self, "_object_dict"): self._object_dict = dict() def register(self, o, logger): """ Register an object in the registry. """ if not o.object_id() in self._object_dict: self._object_registry.append(o) self._object_dict[o.object_id()] = o else: logger.debug("REG: duplicate add, ignoring (%s)" % o) def remove_vpp_config(self, logger): """ Remove configuration (if present) from vpp and then remove all objects from the registry. """ if not self._object_registry: logger.info("REG: No objects registered for auto-cleanup.") return logger.info("REG: Removing VPP configuration for registered objects") # remove the config in reverse order as there might be dependencies for o in reversed(self._object_registry): if o.query_vpp_config(): logger.info("REG: Removing configuration for %s" % o) o.remove_vpp_config() else: logger.info( "REG: Skipping removal for %s, configuration not present" % o) failed = [] for o in self._object_registry: if o.query_vpp_config(): failed.append(o) self._object_registry = [] self._object_dict = dict() if failed: logger.error("REG: Couldn't remove configuration for object(s):") for x in failed: logger.error(repr(x)) raise Exception("Couldn't remove configuration for object(s): %s" % (", ".join(str(x) for x in failed)))