601 lines
22 KiB
Python
601 lines
22 KiB
Python
# Copyright 2013 IBM Corp.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Nova common internal object model"""
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import collections
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import copy
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import functools
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import six
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from nova import context
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from nova import exception
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from nova.objects import fields
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from nova.openstack.common.gettextutils import _
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from nova.openstack.common import log as logging
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from nova.openstack.common.rpc import common as rpc_common
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import nova.openstack.common.rpc.serializer
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from nova.openstack.common import versionutils
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LOG = logging.getLogger('object')
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class NotSpecifiedSentinel:
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pass
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def get_attrname(name):
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"""Return the mangled name of the attribute's underlying storage."""
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return '_%s' % name
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def make_class_properties(cls):
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# NOTE(danms/comstud): Inherit fields from super classes.
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# mro() returns the current class first and returns 'object' last, so
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# those can be skipped. Also be careful to not overwrite any fields
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# that already exist. And make sure each cls has its own copy of
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# fields and that it is not sharing the dict with a super class.
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cls.fields = dict(cls.fields)
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for supercls in cls.mro()[1:-1]:
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if not hasattr(supercls, 'fields'):
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continue
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for name, field in supercls.fields.items():
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if name not in cls.fields:
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cls.fields[name] = field
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for name, field in cls.fields.iteritems():
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def getter(self, name=name):
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attrname = get_attrname(name)
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if not hasattr(self, attrname):
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self.obj_load_attr(name)
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return getattr(self, attrname)
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def setter(self, value, name=name, field=field):
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self._changed_fields.add(name)
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try:
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return setattr(self, get_attrname(name),
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field.coerce(self, name, value))
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except Exception:
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attr = "%s.%s" % (self.obj_name(), name)
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LOG.exception(_('Error setting %(attr)s') %
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{'attr': attr})
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raise
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setattr(cls, name, property(getter, setter))
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class NovaObjectMetaclass(type):
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"""Metaclass that allows tracking of object classes."""
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# NOTE(danms): This is what controls whether object operations are
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# remoted. If this is not None, use it to remote things over RPC.
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indirection_api = None
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def __init__(cls, names, bases, dict_):
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if not hasattr(cls, '_obj_classes'):
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# This will be set in the 'NovaObject' class.
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cls._obj_classes = collections.defaultdict(list)
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else:
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# Add the subclass to NovaObject._obj_classes
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make_class_properties(cls)
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cls._obj_classes[cls.obj_name()].append(cls)
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# These are decorators that mark an object's method as remotable.
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# If the metaclass is configured to forward object methods to an
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# indirection service, these will result in making an RPC call
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# instead of directly calling the implementation in the object. Instead,
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# the object implementation on the remote end will perform the
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# requested action and the result will be returned here.
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def remotable_classmethod(fn):
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"""Decorator for remotable classmethods."""
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@functools.wraps(fn)
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def wrapper(cls, context, *args, **kwargs):
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if NovaObject.indirection_api:
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result = NovaObject.indirection_api.object_class_action(
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context, cls.obj_name(), fn.__name__, cls.VERSION,
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args, kwargs)
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else:
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result = fn(cls, context, *args, **kwargs)
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if isinstance(result, NovaObject):
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result._context = context
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return result
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return classmethod(wrapper)
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# See comment above for remotable_classmethod()
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#
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# Note that this will use either the provided context, or the one
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# stashed in the object. If neither are present, the object is
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# "orphaned" and remotable methods cannot be called.
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def remotable(fn):
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"""Decorator for remotable object methods."""
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@functools.wraps(fn)
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def wrapper(self, *args, **kwargs):
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ctxt = self._context
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try:
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if isinstance(args[0], (context.RequestContext,
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rpc_common.CommonRpcContext)):
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ctxt = args[0]
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args = args[1:]
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except IndexError:
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pass
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if ctxt is None:
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raise exception.OrphanedObjectError(method=fn.__name__,
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objtype=self.obj_name())
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# Force this to be set if it wasn't before.
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self._context = ctxt
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if NovaObject.indirection_api:
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updates, result = NovaObject.indirection_api.object_action(
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ctxt, self, fn.__name__, args, kwargs)
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for key, value in updates.iteritems():
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if key in self.fields:
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field = self.fields[key]
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self[key] = field.from_primitive(self, key, value)
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self.obj_reset_changes()
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self._changed_fields = set(updates.get('obj_what_changed', []))
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return result
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else:
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return fn(self, ctxt, *args, **kwargs)
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return wrapper
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@six.add_metaclass(NovaObjectMetaclass)
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class NovaObject(object):
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"""Base class and object factory.
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This forms the base of all objects that can be remoted or instantiated
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via RPC. Simply defining a class that inherits from this base class
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will make it remotely instantiatable. Objects should implement the
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necessary "get" classmethod routines as well as "save" object methods
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as appropriate.
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"""
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# Object versioning rules
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#
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# Each service has its set of objects, each with a version attached. When
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# a client attempts to call an object method, the server checks to see if
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# the version of that object matches (in a compatible way) its object
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# implementation. If so, cool, and if not, fail.
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VERSION = '1.0'
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# The fields present in this object as key:field pairs. For example:
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#
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# fields = { 'foo': fields.IntegerField(),
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# 'bar': fields.StringField(),
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# }
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fields = {}
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obj_extra_fields = []
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def __init__(self, context=None, **kwargs):
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self._changed_fields = set()
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self._context = context
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for key in kwargs.keys():
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self[key] = kwargs[key]
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@classmethod
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def obj_name(cls):
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"""Return a canonical name for this object which will be used over
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the wire for remote hydration.
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"""
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return cls.__name__
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@classmethod
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def obj_class_from_name(cls, objname, objver):
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"""Returns a class from the registry based on a name and version."""
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if objname not in cls._obj_classes:
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LOG.error(_('Unable to instantiate unregistered object type '
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'%(objtype)s') % dict(objtype=objname))
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raise exception.UnsupportedObjectError(objtype=objname)
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latest = None
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compatible_match = None
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for objclass in cls._obj_classes[objname]:
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if objclass.VERSION == objver:
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return objclass
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version_bits = tuple([int(x) for x in objclass.VERSION.split(".")])
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if latest is None:
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latest = version_bits
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elif latest < version_bits:
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latest = version_bits
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if versionutils.is_compatible(objver, objclass.VERSION):
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compatible_match = objclass
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if compatible_match:
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return compatible_match
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latest_ver = '%i.%i' % latest
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raise exception.IncompatibleObjectVersion(objname=objname,
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objver=objver,
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supported=latest_ver)
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@classmethod
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def obj_from_primitive(cls, primitive, context=None):
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"""Object field-by-field hydration."""
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if primitive['nova_object.namespace'] != 'nova':
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# NOTE(danms): We don't do anything with this now, but it's
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# there for "the future"
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raise exception.UnsupportedObjectError(
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objtype='%s.%s' % (primitive['nova_object.namespace'],
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primitive['nova_object.name']))
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objname = primitive['nova_object.name']
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objver = primitive['nova_object.version']
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objdata = primitive['nova_object.data']
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objclass = cls.obj_class_from_name(objname, objver)
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self = objclass()
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self._context = context
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self.VERSION = objver
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for name, field in self.fields.items():
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if name in objdata:
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setattr(self, name, field.from_primitive(self, name,
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objdata[name]))
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changes = primitive.get('nova_object.changes', [])
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self._changed_fields = set([x for x in changes if x in self.fields])
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return self
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def __deepcopy__(self, memo):
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"""Efficiently make a deep copy of this object."""
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# NOTE(danms): A naive deepcopy would copy more than we need,
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# and since we have knowledge of the volatile bits of the
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# object, we can be smarter here. Also, nested entities within
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# some objects may be uncopyable, so we can avoid those sorts
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# of issues by copying only our field data.
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nobj = self.__class__()
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nobj._context = self._context
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for name in self.fields:
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if self.obj_attr_is_set(name):
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nval = copy.deepcopy(getattr(self, name), memo)
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setattr(nobj, name, nval)
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nobj._changed_fields = set(self._changed_fields)
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return nobj
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def obj_clone(self):
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"""Create a copy."""
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return copy.deepcopy(self)
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def obj_make_compatible(self, primitive, target_version):
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"""Make an object representation compatible with a target version.
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This is responsible for taking the primitive representation of
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an object and making it suitable for the given target_version.
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This may mean converting the format of object attributes, removing
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attributes that have been added since the target version, etc.
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:param:primitive: The result of self.obj_to_primitive()
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:param:target_version: The version string requested by the recipient
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of the object.
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:param:raises: nova.exception.UnsupportedObjectError if conversion
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is not possible for some reason.
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"""
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pass
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def obj_to_primitive(self, target_version=None):
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"""Simple base-case dehydration.
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This calls to_primitive() for each item in fields.
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"""
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primitive = dict()
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for name, field in self.fields.items():
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if self.obj_attr_is_set(name):
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primitive[name] = field.to_primitive(self, name,
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getattr(self, name))
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if target_version:
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self.obj_make_compatible(primitive, target_version)
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obj = {'nova_object.name': self.obj_name(),
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'nova_object.namespace': 'nova',
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'nova_object.version': target_version or self.VERSION,
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'nova_object.data': primitive}
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if self.obj_what_changed():
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obj['nova_object.changes'] = list(self.obj_what_changed())
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return obj
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def obj_load_attr(self, attrname):
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"""Load an additional attribute from the real object.
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This should use self._conductor, and cache any data that might
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be useful for future load operations.
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"""
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raise NotImplementedError(
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_("Cannot load '%s' in the base class") % attrname)
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def save(self, context):
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"""Save the changed fields back to the store.
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This is optional for subclasses, but is presented here in the base
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class for consistency among those that do.
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"""
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raise NotImplementedError('Cannot save anything in the base class')
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def obj_what_changed(self):
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"""Returns a set of fields that have been modified."""
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return self._changed_fields
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def obj_get_changes(self):
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"""Returns a dict of changed fields and their new values."""
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changes = {}
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for key in self.obj_what_changed():
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changes[key] = self[key]
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return changes
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def obj_reset_changes(self, fields=None):
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"""Reset the list of fields that have been changed.
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Note that this is NOT "revert to previous values"
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"""
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if fields:
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self._changed_fields -= set(fields)
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else:
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self._changed_fields.clear()
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def obj_attr_is_set(self, attrname):
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"""Test object to see if attrname is present.
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Returns True if the named attribute has a value set, or
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False if not. Raises AttributeError if attrname is not
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a valid attribute for this object.
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"""
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if attrname not in self.obj_fields:
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raise AttributeError(
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_("%(objname)s object has no attribute '%(attrname)s'") %
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{'objname': self.obj_name(), 'attrname': attrname})
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return hasattr(self, get_attrname(attrname))
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@property
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def obj_fields(self):
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return self.fields.keys() + self.obj_extra_fields
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# dictish syntactic sugar
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def iteritems(self):
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"""For backwards-compatibility with dict-based objects.
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NOTE(danms): May be removed in the future.
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"""
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for name in self.obj_fields:
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if (self.obj_attr_is_set(name) or
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name in self.obj_extra_fields):
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yield name, getattr(self, name)
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items = lambda self: list(self.iteritems())
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def __getitem__(self, name):
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"""For backwards-compatibility with dict-based objects.
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NOTE(danms): May be removed in the future.
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"""
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return getattr(self, name)
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def __setitem__(self, name, value):
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"""For backwards-compatibility with dict-based objects.
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NOTE(danms): May be removed in the future.
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"""
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setattr(self, name, value)
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def __contains__(self, name):
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"""For backwards-compatibility with dict-based objects.
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NOTE(danms): May be removed in the future.
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"""
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try:
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return self.obj_attr_is_set(name)
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except AttributeError:
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return False
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def get(self, key, value=NotSpecifiedSentinel):
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"""For backwards-compatibility with dict-based objects.
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NOTE(danms): May be removed in the future.
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"""
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if key not in self.obj_fields:
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raise AttributeError("'%s' object has no attribute '%s'" % (
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self.__class__, key))
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if value != NotSpecifiedSentinel and not self.obj_attr_is_set(key):
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return value
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else:
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return self[key]
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def update(self, updates):
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"""For backwards-compatibility with dict-base objects.
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NOTE(danms): May be removed in the future.
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"""
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for key, value in updates.items():
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self[key] = value
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class NovaPersistentObject(object):
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"""Mixin class for Persistent objects.
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This adds the fields that we use in common for all persisent objects.
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"""
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fields = {
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'created_at': fields.DateTimeField(nullable=True),
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'updated_at': fields.DateTimeField(nullable=True),
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'deleted_at': fields.DateTimeField(nullable=True),
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'deleted': fields.BooleanField(default=False),
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}
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class ObjectListBase(object):
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"""Mixin class for lists of objects.
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This mixin class can be added as a base class for an object that
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is implementing a list of objects. It adds a single field of 'objects',
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which is the list store, and behaves like a list itself. It supports
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serialization of the list of objects automatically.
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"""
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fields = {
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'objects': fields.ListOfObjectsField('NovaObject'),
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}
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# This is a dictionary of my_version:child_version mappings so that
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# we can support backleveling our contents based on the version
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# requested of the list object.
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child_versions = {}
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def __iter__(self):
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"""List iterator interface."""
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return iter(self.objects)
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def __len__(self):
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"""List length."""
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return len(self.objects)
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def __getitem__(self, index):
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"""List index access."""
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if isinstance(index, slice):
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new_obj = self.__class__()
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new_obj.objects = self.objects[index]
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# NOTE(danms): We must be mixed in with a NovaObject!
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new_obj.obj_reset_changes()
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new_obj._context = self._context
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return new_obj
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return self.objects[index]
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def __contains__(self, value):
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"""List membership test."""
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return value in self.objects
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def count(self, value):
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"""List count of value occurrences."""
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return self.objects.count(value)
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def index(self, value):
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"""List index of value."""
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return self.objects.index(value)
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def _attr_objects_to_primitive(self):
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"""Serialization of object list."""
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return [x.obj_to_primitive() for x in self.objects]
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def _attr_objects_from_primitive(self, value):
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"""Deserialization of object list."""
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objects = []
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for entity in value:
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obj = NovaObject.obj_from_primitive(entity, context=self._context)
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objects.append(obj)
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return objects
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def obj_make_compatible(self, primitive, target_version):
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primitives = primitive['objects']
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child_target_version = self.child_versions.get(target_version, '1.0')
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for index, item in enumerate(self.objects):
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self.objects[index].obj_make_compatible(
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primitives[index]['nova_object.data'],
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child_target_version)
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primitives[index]['nova_object.version'] = child_target_version
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class NovaObjectSerializer(nova.openstack.common.rpc.serializer.Serializer):
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"""A NovaObject-aware Serializer.
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This implements the Oslo Serializer interface and provides the
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ability to serialize and deserialize NovaObject entities. Any service
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that needs to accept or return NovaObjects as arguments or result values
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should pass this to its RpcProxy and RpcDispatcher objects.
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"""
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@property
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def conductor(self):
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if not hasattr(self, '_conductor'):
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from nova.conductor import api as conductor_api
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self._conductor = conductor_api.API()
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return self._conductor
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def _process_object(self, context, objprim):
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try:
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objinst = NovaObject.obj_from_primitive(objprim, context=context)
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except exception.IncompatibleObjectVersion as e:
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objinst = self.conductor.object_backport(context, objprim,
|
|
e.kwargs['supported'])
|
|
return objinst
|
|
|
|
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])
|
|
|
|
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
|
|
|
|
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
|
|
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
|