nova/nova/objects/base.py

789 lines
31 KiB
Python

# Copyright 2013 IBM Corp.
#
# 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 contextlib
import copy
import datetime
import functools
import traceback
import netaddr
from oslo_log import log as logging
import oslo_messaging as messaging
from oslo_utils import timeutils
from oslo_utils import versionutils
from oslo_versionedobjects import base as ovoo_base
import six
from nova import context
from nova import exception
from nova.i18n import _, _LE
from nova import objects
from nova.objects import fields as obj_fields
from nova import utils
LOG = logging.getLogger('object')
def get_attrname(name):
"""Return the mangled name of the attribute's underlying storage."""
# FIXME(danms): This is just until we use o.vo's class properties
# and object base.
return '_obj_' + name
class NovaObjectRegistry(ovoo_base.VersionedObjectRegistry):
def registration_hook(self, cls, index):
# NOTE(danms): Set the *latest* version of this class
newest = self._registry._obj_classes[cls.obj_name()][0]
setattr(objects, cls.obj_name(), newest)
# 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)
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
# NOTE(danms): Make this discoverable
wrapper.remotable = True
wrapper.original_fn = fn
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)
def wrapper(self, *args, **kwargs):
if args and isinstance(args[0], context.RequestContext):
raise exception.ObjectActionError(
action=fn.__name__,
reason='Calling remotables with context is deprecated')
if self._context is None:
raise exception.OrphanedObjectError(method=fn.__name__,
objtype=self.obj_name())
if NovaObject.indirection_api:
updates, result = NovaObject.indirection_api.object_action(
self._context, self, fn.__name__, args, kwargs)
for key, value in six.iteritems(updates):
if key in self.fields:
field = self.fields[key]
# NOTE(ndipanov): Since NovaObjectSerializer will have
# deserialized any object fields into objects already,
# we do not try to deserialize them again here.
if isinstance(value, NovaObject):
setattr(self, key, value)
else:
setattr(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, *args, **kwargs)
wrapper.remotable = True
wrapper.original_fn = fn
return wrapper
class NovaObject(object):
"""Base class and object factory.
This forms the base of all objects that can be remoted or instantiated
via RPC. Simply defining a class that inherits from this base class
will make it remotely instantiatable. Objects should implement the
necessary "get" classmethod routines as well as "save" object methods
as appropriate.
"""
# Object versioning rules
#
# Each service has its set of objects, each with a version attached. When
# a client attempts to call an object method, the server checks to see if
# the version of that object matches (in a compatible way) its object
# implementation. If so, cool, and if not, fail.
#
# This version is allowed to have three parts, X.Y.Z, where the .Z element
# is reserved for stable branch backports. The .Z is ignored for the
# purposes of triggering a backport, which means anything changed under
# a .Z must be additive and non-destructive such that a node that knows
# about X.Y can consider X.Y.Z equivalent.
VERSION = '1.0'
# The fields present in this object as key:field pairs. For example:
#
# fields = { 'foo': fields.IntegerField(),
# 'bar': fields.StringField(),
# }
fields = {}
obj_extra_fields = []
# Table of sub-object versioning information
#
# This contains a list of version mappings, by the field name of
# the subobject. The mappings must be in order of oldest to
# newest, and are tuples of (my_version, subobject_version). A
# request to backport this object to $my_version will cause the
# subobject to be backported to $subobject_version.
#
# obj_relationships = {
# 'subobject1': [('1.2', '1.1'), ('1.4', '1.2')],
# 'subobject2': [('1.2', '1.0')],
# }
#
# In the above example:
#
# - If we are asked to backport our object to version 1.3,
# subobject1 will be backported to version 1.1, since it was
# bumped to version 1.2 when our version was 1.4.
# - If we are asked to backport our object to version 1.5,
# no changes will be made to subobject1 or subobject2, since
# they have not changed since version 1.4.
# - If we are asked to backlevel our object to version 1.1, we
# will remove both subobject1 and subobject2 from the primitive,
# since they were not added until version 1.2.
obj_relationships = {}
# Temporary until we inherit from o.vo.base.VersionedObject
indirection_api = None
def __init__(self, context=None, **kwargs):
self._changed_fields = set()
self._context = context
for key in kwargs.keys():
setattr(self, key, kwargs[key])
def __repr__(self):
return '%s(%s)' % (
self.obj_name(),
','.join(['%s=%s' % (name,
(self.obj_attr_is_set(name) and
field.stringify(getattr(self, name)) or
'<?>'))
for name, field in sorted(self.fields.items())]))
@classmethod
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
def obj_class_from_name(cls, objname, objver):
"""Returns a class from the registry based on a name and version."""
if objname not in NovaObjectRegistry.obj_classes():
LOG.error(_LE('Unable to instantiate unregistered object type '
'%(objtype)s'), dict(objtype=objname))
raise exception.UnsupportedObjectError(objtype=objname)
# NOTE(comstud): If there's not an exact match, return the highest
# compatible version. The objects stored in the class are sorted
# such that highest version is first, so only set compatible_match
# once below.
compatible_match = None
obj_classes = NovaObjectRegistry.obj_classes()
for objclass in obj_classes[objname]:
if objclass.VERSION == objver:
return objclass
if (not compatible_match and
versionutils.is_compatible(objver, objclass.VERSION)):
compatible_match = objclass
if compatible_match:
return compatible_match
# As mentioned above, latest version is always first in the list.
latest_ver = obj_classes[objname][0].VERSION
raise exception.IncompatibleObjectVersion(objname=objname,
objver=objver,
supported=latest_ver)
@classmethod
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
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)
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
def obj_clone(self):
"""Create a copy."""
return copy.deepcopy(self)
def obj_calculate_child_version(self, target_version, child):
"""Calculate the appropriate version for a child object.
This is to be used when backporting an object for an older client.
A sub-object will need to be backported to a suitable version for
the client as well, and this method will calculate what that
version should be, based on obj_relationships.
:param target_version: Version this object is being backported to
:param child: The child field for which the appropriate version
is to be calculated
:returns: None if the child should be omitted from the backport,
otherwise, the version to which the child should be
backported
"""
target_version = utils.convert_version_to_tuple(target_version)
for index, versions in enumerate(self.obj_relationships[child]):
my_version, child_version = versions
my_version = utils.convert_version_to_tuple(my_version)
if target_version < my_version:
if index == 0:
# We're backporting to a version from before this
# subobject was added: delete it from the primitive.
return None
else:
# We're in the gap between index-1 and index, so
# backport to the older version
return self.obj_relationships[child][index - 1][1]
elif target_version == my_version:
# This is the first mapping that satisfies the
# target_version request: backport the object.
return child_version
# No need to backport, as far as we know, so return the latest
# version of the sub-object we know about
return self.obj_relationships[child][-1][1]
def _obj_make_obj_compatible(self, primitive, target_version, field):
"""Backlevel a sub-object based on our versioning rules.
This is responsible for backporting objects contained within
this object's primitive according to a set of rules we
maintain about version dependencies between objects. This
requires that the obj_relationships table in this object is
correct and up-to-date.
:param:primitive: The primitive version of this object
:param:target_version: The version string requested for this object
:param:field: The name of the field in this object containing the
sub-object to be backported
"""
def _do_backport(to_version):
obj = getattr(self, field)
if obj is None:
return
if isinstance(obj, NovaObject):
if to_version != primitive[field]['nova_object.version']:
obj.obj_make_compatible(
primitive[field]['nova_object.data'],
to_version)
primitive[field]['nova_object.version'] = to_version
elif isinstance(obj, list):
for i, element in enumerate(obj):
element.obj_make_compatible(
primitive[field][i]['nova_object.data'],
to_version)
primitive[field][i]['nova_object.version'] = to_version
child_version = self.obj_calculate_child_version(target_version, field)
if child_version is None:
del primitive[field]
else:
_do_backport(child_version)
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. In
general:
- If a new version of an object adds a field, this routine
should remove it for older versions.
- If a new version changed or restricted the format of a field, this
should convert it back to something a client knowing only of the
older version will tolerate.
- If an object that this object depends on is bumped, then this
object should also take a version bump. Then, this routine should
backlevel the dependent object (by calling its obj_make_compatible())
if the requested version of this object is older than the version
where the new dependent object was added.
:param:primitive: The result of self.obj_to_primitive()
:param:target_version: The version string requested by the recipient
of the object
:raises: nova.exception.UnsupportedObjectError if conversion
is not possible for some reason
"""
for key, field in self.fields.items():
if not isinstance(field, (obj_fields.ObjectField,
obj_fields.ListOfObjectsField)):
continue
if not self.obj_attr_is_set(key):
continue
if key not in self.obj_relationships:
# NOTE(danms): This is really a coding error and shouldn't
# happen unless we miss something
raise exception.ObjectActionError(
action='obj_make_compatible',
reason='No rule for %s' % key)
self._obj_make_obj_compatible(primitive, target_version, key)
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
def obj_set_defaults(self, *attrs):
if not attrs:
attrs = [name for name, field in self.fields.items()
if field.default != obj_fields.UnspecifiedDefault]
for attr in attrs:
default = copy.deepcopy(self.fields[attr].default)
if default is obj_fields.UnspecifiedDefault:
raise exception.ObjectActionError(
action='set_defaults',
reason='No default set for field %s' % attr)
if not self.obj_attr_is_set(attr):
setattr(self, attr, default)
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)
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'))
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(getattr(self, field), NovaObject) and
getattr(self, field).obj_what_changed()):
changes.add(field)
return changes
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] = getattr(self, key)
return changes
def obj_reset_changes(self, fields=None, recursive=False):
"""Reset the list of fields that have been changed.
:param fields: List of fields to reset, or "all" if None.
:param recursive: Call obj_reset_changes(recursive=True) on
any sub-objects within the list of fields
being reset.
NOTE: This is NOT "revert to previous values"
NOTE: Specifying fields on recursive resets will only be
honored at the top level. Everything below the top
will reset all.
"""
if recursive:
for field in self.obj_get_changes():
# Ignore fields not in requested set (if applicable)
if fields and field not in fields:
continue
# Skip any fields that are unset
if not self.obj_attr_is_set(field):
continue
value = getattr(self, field)
# Don't reset nulled fields
if value is None:
continue
# Reset straight Object and ListOfObjects fields
if isinstance(self.fields[field], obj_fields.ObjectField):
value.obj_reset_changes(recursive=True)
elif isinstance(self.fields[field],
obj_fields.ListOfObjectsField):
for thing in value:
thing.obj_reset_changes(recursive=True)
if fields:
self._changed_fields -= set(fields)
else:
self._changed_fields.clear()
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
def obj_fields(self):
return self.fields.keys() + self.obj_extra_fields
# NOTE(danms): This is nova-specific, so don't copy this to o.vo
@contextlib.contextmanager
def obj_alternate_context(self, context):
original_context = self._context
self._context = context
try:
yield
finally:
self._context = original_context
@contextlib.contextmanager
def obj_as_admin(self):
"""Context manager to make an object call as an admin.
This temporarily modifies the context embedded in an object to
be elevated() and restores it after the call completes. Example
usage:
with obj.obj_as_admin():
obj.save()
"""
if self._context is None:
raise exception.OrphanedObjectError(method='obj_as_admin',
objtype=self.obj_name())
original_context = self._context
self._context = self._context.elevated()
try:
yield
finally:
self._context = original_context
class NovaObjectDictCompat(ovoo_base.VersionedObjectDictCompat):
def __iter__(self):
for name in self.obj_fields:
if (self.obj_attr_is_set(name) or
name in self.obj_extra_fields):
yield name
def keys(self):
return list(self)
class NovaTimestampObject(object):
"""Mixin class for db backed objects with timestamp fields.
Sqlalchemy models that inherit from the oslo_db TimestampMixin will include
these fields and the corresponding objects will benefit from this mixin.
"""
fields = {
'created_at': obj_fields.DateTimeField(nullable=True),
'updated_at': obj_fields.DateTimeField(nullable=True),
}
class NovaPersistentObject(object):
"""Mixin class for Persistent objects.
This adds the fields that we use in common for most persistent objects.
"""
fields = {
'created_at': obj_fields.DateTimeField(nullable=True),
'updated_at': obj_fields.DateTimeField(nullable=True),
'deleted_at': obj_fields.DateTimeField(nullable=True),
'deleted': obj_fields.BooleanField(default=False),
}
class ObjectListBase(ovoo_base.ObjectListBase):
# NOTE(danms): These are for transition to using the oslo
# base object and can be removed when we move to it.
@classmethod
def _obj_primitive_key(cls, field):
return 'nova_object.%s' % field
@classmethod
def _obj_primitive_field(cls, primitive, field,
default=obj_fields.UnspecifiedDefault):
key = cls._obj_primitive_key(field)
if default == obj_fields.UnspecifiedDefault:
return primitive[key]
else:
return primitive.get(key, default)
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
def conductor(self):
if not hasattr(self, '_conductor'):
from nova import conductor
self._conductor = conductor.API()
return self._conductor
def _process_object(self, context, objprim):
try:
objinst = NovaObject.obj_from_primitive(objprim, context=context)
except exception.IncompatibleObjectVersion as e:
objver = objprim['nova_object.version']
if objver.count('.') == 2:
# NOTE(danms): For our purposes, the .z part of the version
# should be safe to accept without requiring a backport
objprim['nova_object.version'] = \
'.'.join(objver.split('.')[:2])
return self._process_object(context, objprim)
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 issubclass(iterable, dict):
return iterable(**{k: action_fn(context, v)
for k, v in six.iteritems(values)})
else:
# NOTE(danms, gibi) A set can't have an unhashable value inside,
# such as a dict. Convert the set to list, which is fine, since we
# can't send them over RPC anyway. We convert it to list as this
# way there will be no semantic change between the fake rpc driver
# used in functional test and a normal rpc driver.
if iterable == set:
iterable = list
return iterable([action_fn(context, value) for value in values])
def serialize_entity(self, context, entity):
if isinstance(entity, (tuple, list, set, dict)):
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, dict)):
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 in obj.obj_fields:
if obj.obj_attr_is_set(key) or key in obj.obj_extra_fields:
result[key] = obj_to_primitive(getattr(obj, key))
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 context
: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
def serialize_args(fn):
"""Decorator that will do the arguments serialization before remoting."""
def wrapper(obj, *args, **kwargs):
args = [timeutils.strtime(at=arg) if isinstance(arg, datetime.datetime)
else arg for arg in args]
for k, v in six.iteritems(kwargs):
if k == 'exc_val' and v:
kwargs[k] = str(v)
elif k == 'exc_tb' and v and not isinstance(v, six.string_types):
kwargs[k] = ''.join(traceback.format_tb(v))
elif isinstance(v, datetime.datetime):
kwargs[k] = timeutils.strtime(at=v)
if hasattr(fn, '__call__'):
return fn(obj, *args, **kwargs)
# NOTE(danms): We wrap a descriptor, so use that protocol
return fn.__get__(None, obj)(*args, **kwargs)
# NOTE(danms): Make this discoverable
wrapper.remotable = getattr(fn, 'remotable', False)
wrapper.original_fn = fn
return (functools.wraps(fn)(wrapper) if hasattr(fn, '__call__')
else classmethod(wrapper))
def obj_equal_prims(obj_1, obj_2, ignore=None):
"""Compare two primitives for equivalence ignoring some keys.
This operation tests the primitives of two objects for equivalence.
Object primitives may contain a list identifying fields that have been
changed - this is ignored in the comparison. The ignore parameter lists
any other keys to be ignored.
:param:obj1: The first object in the comparison
:param:obj2: The second object in the comparison
:param:ignore: A list of fields to ignore
:returns: True if the primitives are equal ignoring changes
and specified fields, otherwise False.
"""
def _strip(prim, keys):
if isinstance(prim, dict):
for k in keys:
prim.pop(k, None)
for v in prim.values():
_strip(v, keys)
if isinstance(prim, list):
for v in prim:
_strip(v, keys)
return prim
if ignore is not None:
keys = ['nova_object.changes'] + ignore
else:
keys = ['nova_object.changes']
prim_1 = _strip(obj_1.obj_to_primitive(), keys)
prim_2 = _strip(obj_2.obj_to_primitive(), keys)
return prim_1 == prim_2