¡@
OpenStack Study: base.py**** CubicPower OpenStack Study ****
# # Licensed under the Apache License, Version 2.0 (the "License"); you may # not use this file except in compliance with the License. You may obtain # a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the # License for the specific language governing permissions and limitations # under the License. """Nova common internal object model""" import collections import copy import functools import netaddr from oslo import messaging import six from nova import context from nova import exception from nova.objects import fields from nova.openstack.common.gettextutils import _ from nova.openstack.common import log as logging from nova.openstack.common import versionutils LOG = logging.getLogger('object')
**** CubicPower OpenStack Study **** class NotSpecifiedSentinel: pass
**** CubicPower OpenStack Study **** def get_attrname(name): """Return the mangled name of the attribute's underlying storage.""" return '_%s' % name
**** CubicPower OpenStack Study **** def make_class_properties(cls): # NOTE(danms/comstud): Inherit fields from super classes. # mro() returns the current class first and returns 'object' last, so # those can be skipped. Also be careful to not overwrite any fields # that already exist. And make sure each cls has its own copy of # fields and that it is not sharing the dict with a super class. cls.fields = dict(cls.fields) for supercls in cls.mro()[1:-1]: if not hasattr(supercls, 'fields'): continue for name, field in supercls.fields.items(): if name not in cls.fields: cls.fields[name] = field for name, field in cls.fields.iteritems(): def getter(self, name=name): attrname = get_attrname(name) if not hasattr(self, attrname): self.obj_load_attr(name) return getattr(self, attrname) def setter(self, value, name=name, field=field): self._changed_fields.add(name) try: return setattr(self, get_attrname(name), field.coerce(self, name, value)) except Exception: attr = "%s.%s" % (self.obj_name(), name) LOG.exception(_('Error setting %(attr)s') % {'attr': attr}) raise setattr(cls, name, property(getter, setter))
**** CubicPower OpenStack Study **** class NovaObjectMetaclass(type): """Metaclass that allows tracking of object classes.""" # NOTE(danms): This is what controls whether object operations are # remoted. If this is not None, use it to remote things over RPC. indirection_api = None
**** CubicPower OpenStack Study **** def __init__(cls, names, bases, dict_): if not hasattr(cls, '_obj_classes'): # This will be set in the 'NovaObject' class. cls._obj_classes = collections.defaultdict(list) else: # Add the subclass to NovaObject._obj_classes make_class_properties(cls) cls._obj_classes[cls.obj_name()].append(cls) # These are decorators that mark an object's method as remotable. # If the metaclass is configured to forward object methods to an # indirection service, these will result in making an RPC call # instead of directly calling the implementation in the object. Instead, # the object implementation on the remote end will perform the # requested action and the result will be returned here. def remotable_classmethod(fn): """Decorator for remotable classmethods.""" @functools.wraps(fn)
**** CubicPower OpenStack Study **** def remotable_classmethod(fn): """Decorator for remotable classmethods.""" @functools.wraps(fn)
**** CubicPower OpenStack Study **** def wrapper(cls, context, *args, **kwargs): if NovaObject.indirection_api: result = NovaObject.indirection_api.object_class_action( context, cls.obj_name(), fn.__name__, cls.VERSION, args, kwargs) else: result = fn(cls, context, *args, **kwargs) if isinstance(result, NovaObject): result._context = context return result return classmethod(wrapper) # See comment above for remotable_classmethod() # # Note that this will use either the provided context, or the one # stashed in the object. If neither are present, the object is # "orphaned" and remotable methods cannot be called. def remotable(fn): """Decorator for remotable object methods.""" @functools.wraps(fn)
**** CubicPower OpenStack Study **** def remotable(fn): """Decorator for remotable object methods.""" @functools.wraps(fn)
**** CubicPower OpenStack Study **** def wrapper(self, *args, **kwargs): ctxt = self._context try: if isinstance(args[0], (context.RequestContext)): ctxt = args[0] args = args[1:] except IndexError: pass if ctxt is None: raise exception.OrphanedObjectError(method=fn.__name__, objtype=self.obj_name()) # Force this to be set if it wasn't before. self._context = ctxt if NovaObject.indirection_api: updates, result = NovaObject.indirection_api.object_action( ctxt, self, fn.__name__, args, kwargs) for key, value in updates.iteritems(): if key in self.fields: field = self.fields[key] self[key] = field.from_primitive(self, key, value) self.obj_reset_changes() self._changed_fields = set(updates.get('obj_what_changed', [])) return result else: return fn(self, ctxt, *args, **kwargs) return wrapper @six.add_metaclass(NovaObjectMetaclass)
**** CubicPower OpenStack Study **** class NovaObject(object): """Base class and object factory. This forms the base of all objects that can be remoted or instantiated via RPC. Simply
**** CubicPower OpenStack Study **** def __init__(self, context=None, **kwargs): self._changed_fields = set() self._context = context for key in kwargs.keys(): self[key] = kwargs[key] @classmethod
**** CubicPower OpenStack Study **** def obj_name(cls): """Return a canonical name for this object which will be used over the wire for remote hydration. """ return cls.__name__ @classmethod
**** CubicPower OpenStack Study **** def obj_class_from_name(cls, objname, objver): """Returns a class from the registry based on a name and version.""" if objname not in cls._obj_classes: LOG.error(_('Unable to instantiate unregistered object type ' '%(objtype)s') % dict(objtype=objname)) raise exception.UnsupportedObjectError(objtype=objname) latest = None compatible_match = None for objclass in cls._obj_classes[objname]: if objclass.VERSION == objver: return objclass version_bits = tuple([int(x) for x in objclass.VERSION.split(".")]) if latest is None: latest = version_bits elif latest < version_bits: latest = version_bits if versionutils.is_compatible(objver, objclass.VERSION): compatible_match = objclass if compatible_match: return compatible_match latest_ver = '%i.%i' % latest raise exception.IncompatibleObjectVersion(objname=objname, objver=objver, supported=latest_ver) @classmethod
**** CubicPower OpenStack Study **** def _obj_from_primitive(cls, context, objver, primitive): self = cls() self._context = context self.VERSION = objver objdata = primitive['nova_object.data'] changes = primitive.get('nova_object.changes', []) for name, field in self.fields.items(): if name in objdata: setattr(self, name, field.from_primitive(self, name, objdata[name])) self._changed_fields = set([x for x in changes if x in self.fields]) return self @classmethod
**** CubicPower OpenStack Study **** def obj_from_primitive(cls, primitive, context=None): """Object field-by-field hydration.""" if primitive['nova_object.namespace'] != 'nova': # NOTE(danms): We don't do anything with this now, but it's # there for "the future" raise exception.UnsupportedObjectError( objtype='%s.%s' % (primitive['nova_object.namespace'], primitive['nova_object.name'])) objname = primitive['nova_object.name'] objver = primitive['nova_object.version'] objclass = cls.obj_class_from_name(objname, objver) return objclass._obj_from_primitive(context, objver, primitive)
**** CubicPower OpenStack Study **** def __deepcopy__(self, memo): """Efficiently make a deep copy of this object.""" # NOTE(danms): A naive deepcopy would copy more than we need, # and since we have knowledge of the volatile bits of the # object, we can be smarter here. Also, nested entities within # some objects may be uncopyable, so we can avoid those sorts # of issues by copying only our field data. nobj = self.__class__() nobj._context = self._context for name in self.fields: if self.obj_attr_is_set(name): nval = copy.deepcopy(getattr(self, name), memo) setattr(nobj, name, nval) nobj._changed_fields = set(self._changed_fields) return nobj
**** CubicPower OpenStack Study **** def obj_clone(self): """Create a copy.""" return copy.deepcopy(self)
**** CubicPower OpenStack Study **** def obj_make_compatible(self, primitive, target_version): """Make an object representation compatible with a target version. This is responsible for taking the primitive representation of an object and making it suitable for the given target_version. This may mean converting the format of object attributes, removing attributes that have been added since the target version, etc. :param:primitive: The result of self.obj_to_primitive() :param:target_version: The version string requested by the recipient of the object. :param:raises: nova.exception.UnsupportedObjectError if conversion is not possible for some reason. """ pass
**** CubicPower OpenStack Study **** def obj_to_primitive(self, target_version=None): """Simple base-case dehydration. This calls to_primitive() for each item in fields. """ primitive = dict() for name, field in self.fields.items(): if self.obj_attr_is_set(name): primitive[name] = field.to_primitive(self, name, getattr(self, name)) if target_version: self.obj_make_compatible(primitive, target_version) obj = {'nova_object.name': self.obj_name(), 'nova_object.namespace': 'nova', 'nova_object.version': target_version or self.VERSION, 'nova_object.data': primitive} if self.obj_what_changed(): obj['nova_object.changes'] = list(self.obj_what_changed()) return obj
**** CubicPower OpenStack Study **** def obj_load_attr(self, attrname): """Load an additional attribute from the real object. This should use self._conductor, and cache any data that might be useful for future load operations. """ raise NotImplementedError( _("Cannot load '%s' in the base class") % attrname)
**** CubicPower OpenStack Study **** def save(self, context): """Save the changed fields back to the store. This is optional for subclasses, but is presented here in the base class for consistency among those that do. """ raise NotImplementedError('Cannot save anything in the base class')
**** CubicPower OpenStack Study **** def obj_what_changed(self): """Returns a set of fields that have been modified.""" changes = set(self._changed_fields) for field in self.fields: if (self.obj_attr_is_set(field) and isinstance(self[field], NovaObject) and self[field].obj_what_changed()): changes.add(field) return changes
**** CubicPower OpenStack Study **** def obj_get_changes(self): """Returns a dict of changed fields and their new values.""" changes = {} for key in self.obj_what_changed(): changes[key] = self[key] return changes
**** CubicPower OpenStack Study **** def obj_reset_changes(self, fields=None): """Reset the list of fields that have been changed. Note that this is NOT "revert to previous values" """ if fields: self._changed_fields -= set(fields) else: self._changed_fields.clear()
**** CubicPower OpenStack Study **** def obj_attr_is_set(self, attrname): """Test object to see if attrname is present. Returns True if the named attribute has a value set, or False if not. Raises AttributeError if attrname is not a valid attribute for this object. """ if attrname not in self.obj_fields: raise AttributeError( _("%(objname)s object has no attribute '%(attrname)s'") % {'objname': self.obj_name(), 'attrname': attrname}) return hasattr(self, get_attrname(attrname)) @property
**** CubicPower OpenStack Study **** def obj_fields(self): return self.fields.keys() + self.obj_extra_fields # dictish syntactic sugar
**** CubicPower OpenStack Study **** def iteritems(self): """For backwards-compatibility with dict-based objects. NOTE(danms): May be removed in the future. """ for name in self.obj_fields: if (self.obj_attr_is_set(name) or name in self.obj_extra_fields): yield name, getattr(self, name) items = lambda self: list(self.iteritems())
**** CubicPower OpenStack Study **** def __getitem__(self, name): """For backwards-compatibility with dict-based objects. NOTE(danms): May be removed in the future. """ return getattr(self, name)
**** CubicPower OpenStack Study **** def __setitem__(self, name, value): """For backwards-compatibility with dict-based objects. NOTE(danms): May be removed in the future. """ setattr(self, name, value)
**** CubicPower OpenStack Study **** def __contains__(self, name): """For backwards-compatibility with dict-based objects. NOTE(danms): May be removed in the future. """ try: return self.obj_attr_is_set(name) except AttributeError: return False
**** CubicPower OpenStack Study **** def get(self, key, value=NotSpecifiedSentinel): """For backwards-compatibility with dict-based objects. NOTE(danms): May be removed in the future. """ if key not in self.obj_fields: raise AttributeError("'%s' object has no attribute '%s'" % ( self.__class__, key)) if value != NotSpecifiedSentinel and not self.obj_attr_is_set(key): return value else: return self[key]
**** CubicPower OpenStack Study **** def update(self, updates): """For backwards-compatibility with dict-base objects. NOTE(danms): May be removed in the future. """ for key, value in updates.items(): self[key] = value
**** CubicPower OpenStack Study **** class NovaPersistentObject(object): """Mixin class for Persistent objects. This adds the fields that we use in common for all persisent objects. """ fields = { 'created_at': fields.DateTimeField(nullable=True), 'updated_at': fields.DateTimeField(nullable=True), 'deleted_at': fields.DateTimeField(nullable=True), 'deleted': fields.BooleanField(
**** CubicPower OpenStack Study **** class ObjectListBase(object): """Mixin class for lists of objects. This mixin class can be added as a base class for an object that is implementing a list of objects. It adds a single field of 'objects', which is the list store, and behaves like a list itself. It supports serialization of the list of objects automatically. """ fields = { 'objects': fields.ListOfObjectsField('NovaObject'), } # This is a dictionary of my_version:child_version mappings so that # we can support backleveling our contents based on the version # requested of the list object. child_versions = {}
**** CubicPower OpenStack Study **** def __iter__(self): """List iterator interface.""" return iter(self.objects)
**** CubicPower OpenStack Study **** def __len__(self): """List length.""" return len(self.objects)
**** CubicPower OpenStack Study **** def __getitem__(self, index): """List index access.""" if isinstance(index, slice): new_obj = self.__class__() new_obj.objects = self.objects[index] # NOTE(danms): We must be mixed in with a NovaObject! new_obj.obj_reset_changes() new_obj._context = self._context return new_obj return self.objects[index]
**** CubicPower OpenStack Study **** def __contains__(self, value): """List membership test.""" return value in self.objects
**** CubicPower OpenStack Study **** def count(self, value): """List count of value occurrences.""" return self.objects.count(value)
**** CubicPower OpenStack Study **** def index(self, value): """List index of value.""" return self.objects.index(value)
**** CubicPower OpenStack Study **** def sort(self, cmp=None, key=None, reverse=False): self.objects.sort(cmp=cmp, key=key, reverse=reverse)
**** CubicPower OpenStack Study **** def _attr_objects_to_primitive(self): """Serialization of object list.""" return [x.obj_to_primitive() for x in self.objects]
**** CubicPower OpenStack Study **** def _attr_objects_from_primitive(self, value): """Deserialization of object list.""" objects = [] for entity in value: obj = NovaObject.obj_from_primitive(entity, context=self._context) objects.append(obj) return objects
**** CubicPower OpenStack Study **** def obj_make_compatible(self, primitive, target_version): primitives = primitive['objects'] child_target_version = self.child_versions.get(target_version, '1.0') for index, item in enumerate(self.objects): self.objects[index].obj_make_compatible( primitives[index]['nova_object.data'], child_target_version) primitives[index]['nova_object.version'] = child_target_version
**** CubicPower OpenStack Study **** def obj_what_changed(self): changes = set(self._changed_fields) for child in self.objects: if child.obj_what_changed(): changes.add('objects') return changes
**** CubicPower OpenStack Study **** class NovaObjectSerializer(messaging.NoOpSerializer): """A NovaObject-aware Serializer. This implements the Oslo Serializer interface and provides the ability to serialize and deserialize NovaObject entities. Any service that needs to accept or return NovaObjects as arguments or result values should pass this to its RPCClient and RPCServer objects. """ @property
**** CubicPower OpenStack Study **** def conductor(self): if not hasattr(self, '_conductor'): from nova.conductor import api as conductor_api self._conductor = conductor_api.API() return self._conductor
**** CubicPower OpenStack Study **** def _process_object(self, context, objprim): try: objinst = NovaObject.obj_from_primitive(objprim, context=context) except exception.IncompatibleObjectVersion as e: objinst = self.conductor.object_backport(context, objprim, e.kwargs['supported']) return objinst
**** CubicPower OpenStack Study **** def _process_iterable(self, context, action_fn, values): """Process an iterable, taking an action on each value. :param:context: Request context :param:action_fn: Action to take on each item in values :param:values: Iterable container of things to take action on :returns: A new container of the same type (except set) with items from values having had action applied. """ iterable = values.__class__ if iterable == set: # NOTE(danms): A set can't have an unhashable value inside, such as # a dict. Convert sets to tuples, which is fine, since we can't # send them over RPC anyway. iterable = tuple return iterable([action_fn(context, value) for value in values])
**** CubicPower OpenStack Study **** def serialize_entity(self, context, entity): if isinstance(entity, (tuple, list, set)): entity = self._process_iterable(context, self.serialize_entity, entity) elif (hasattr(entity, 'obj_to_primitive') and callable(entity.obj_to_primitive)): entity = entity.obj_to_primitive() return entity
**** CubicPower OpenStack Study **** def deserialize_entity(self, context, entity): if isinstance(entity, dict) and 'nova_object.name' in entity: entity = self._process_object(context, entity) elif isinstance(entity, (tuple, list, set)): entity = self._process_iterable(context, self.deserialize_entity, entity) return entity def obj_to_primitive(obj): """Recursively turn an object into a python primitive. A NovaObject becomes a dict, and anything that implements ObjectListBase becomes a list. """ if isinstance(obj, ObjectListBase): return [obj_to_primitive(x) for x in obj] elif isinstance(obj, NovaObject): result = {} for key, value in obj.iteritems(): result[key] = obj_to_primitive(value) return result elif isinstance(obj, netaddr.IPAddress): return str(obj) elif isinstance(obj, netaddr.IPNetwork): return str(obj) else: return obj def obj_make_list(context, list_obj, item_cls, db_list, **extra_args): """Construct an object list from a list of primitives. This calls item_cls._from_db_object() on each item of db_list, and adds the resulting object to list_obj. :param:context: Request contextr :param:list_obj: An ObjectListBase object :param:item_cls: The NovaObject class of the objects within the list :param:db_list: The list of primitives to convert to objects :param:extra_args: Extra arguments to pass to _from_db_object() :returns: list_obj """ list_obj.objects = [] for db_item in db_list: item = item_cls._from_db_object(context, item_cls(), db_item, **extra_args) list_obj.objects.append(item) list_obj._context = context list_obj.obj_reset_changes() return list_obj
**** CubicPower OpenStack Study **** def obj_to_primitive(obj): """Recursively turn an object into a python primitive. A NovaObject becomes a dict, and anything that implements ObjectListBase becomes a list. """ if isinstance(obj, ObjectListBase): return [obj_to_primitive(x) for x in obj] elif isinstance(obj, NovaObject): result = {} for key, value in obj.iteritems(): result[key] = obj_to_primitive(value) return result elif isinstance(obj, netaddr.IPAddress): return str(obj) elif isinstance(obj, netaddr.IPNetwork): return str(obj) else: return obj
**** CubicPower OpenStack Study **** def obj_make_list(context, list_obj, item_cls, db_list, **extra_args): """Construct an object list from a list of primitives. This calls item_cls._from_db_object() on each item of db_list, and adds the resulting object to list_obj. :param:context: Request contextr :param:list_obj: An ObjectListBase object :param:item_cls: The NovaObject class of the objects within the list :param:db_list: The list of primitives to convert to objects :param:extra_args: Extra arguments to pass to _from_db_object() :returns: list_obj """ list_obj.objects = [] for db_item in db_list: item = item_cls._from_db_object(context, item_cls(), db_item, **extra_args) list_obj.objects.append(item) list_obj._context = context list_obj.obj_reset_changes() return list_obj
|