deb-cinder/cinder/objects/service.py
John Griffith 106c14a84b Replication v2.1 (Cheesecake)
This focuses the replication work on a specific use case,
and eliminates some of the ambiguity in earlier versions.

Additionally this implementation addresses needs for
devices that do replication based on the whole backend-device
or on Pools.

Use case:
  DR scenario, where a storage device is rendered inoperable.
  This implementation allows the preservation of user data
  for those volumes that are of type replication-enabled.

  The goal is NOT to make failures completely transparent
  but instead to preserve data access while an Admin tries
  to rebuild/recover his/her cloud.

It's very important to note that we're no longer interested in
dealing with replication in Cinder at a Volume level.  The concept
of have "some" volumes failover, and "others" left behind, proved
to not only be overly complex and difficult to implement, but we
never identified a concrete use-case where one would use failover
in a scenario where some volumes would stay and be accessible on
a primary but other may be moved and accessed via a secondary.

In this model, it's host/backend based.  So when you failover,
you're failing over an entire backend.  We heavily leverage
existing resources, specifically services, and capabilities.

Implements: blueprint replication-update

Change-Id: If862bcd18515098639f94a8294a8e44e1358c52a
2016-02-26 13:15:19 -07:00

174 lines
6.6 KiB
Python

# Copyright 2015 Intel 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.
from oslo_log import log as logging
from oslo_utils import versionutils
from oslo_versionedobjects import fields
from cinder import db
from cinder import exception
from cinder.i18n import _
from cinder import objects
from cinder.objects import base
from cinder.objects import fields as c_fields
from cinder import utils
LOG = logging.getLogger(__name__)
@base.CinderObjectRegistry.register
class Service(base.CinderPersistentObject, base.CinderObject,
base.CinderObjectDictCompat,
base.CinderComparableObject):
# Version 1.0: Initial version
# Version 1.1: Add rpc_current_version and object_current_version fields
# Version 1.2: Add get_minimum_rpc_version() and get_minimum_obj_version()
# Version 1.3: Add replication fields
VERSION = '1.3'
fields = {
'id': fields.IntegerField(),
'host': fields.StringField(nullable=True),
'binary': fields.StringField(nullable=True),
'topic': fields.StringField(nullable=True),
'report_count': fields.IntegerField(default=0),
'disabled': fields.BooleanField(default=False),
'availability_zone': fields.StringField(nullable=True,
default='cinder'),
'disabled_reason': fields.StringField(nullable=True),
'modified_at': fields.DateTimeField(nullable=True),
'rpc_current_version': fields.StringField(nullable=True),
'object_current_version': fields.StringField(nullable=True),
# Replication properties
'replication_status': c_fields.ReplicationStatusField(nullable=True),
'frozen': fields.BooleanField(default=False),
'active_backend_id': fields.StringField(nullable=True),
}
def obj_make_compatible(self, primitive, target_version):
"""Make an object representation compatible with a target version."""
target_version = utils.convert_version_to_tuple(target_version)
@staticmethod
def _from_db_object(context, service, db_service):
for name, field in service.fields.items():
value = db_service.get(name)
if isinstance(field, fields.IntegerField):
value = value or 0
elif isinstance(field, fields.DateTimeField):
value = value or None
service[name] = value
service._context = context
service.obj_reset_changes()
return service
@base.remotable_classmethod
def get_by_host_and_topic(cls, context, host, topic):
db_service = db.service_get_by_host_and_topic(context, host, topic)
return cls._from_db_object(context, cls(context), db_service)
@base.remotable_classmethod
def get_by_args(cls, context, host, binary_key):
db_service = db.service_get_by_args(context, host, binary_key)
return cls._from_db_object(context, cls(context), db_service)
@base.remotable
def create(self):
if self.obj_attr_is_set('id'):
raise exception.ObjectActionError(action='create',
reason=_('already created'))
updates = self.cinder_obj_get_changes()
db_service = db.service_create(self._context, updates)
self._from_db_object(self._context, self, db_service)
@base.remotable
def save(self):
updates = self.cinder_obj_get_changes()
if updates:
db.service_update(self._context, self.id, updates)
self.obj_reset_changes()
@base.remotable
def destroy(self):
with self.obj_as_admin():
db.service_destroy(self._context, self.id)
@classmethod
def _get_minimum_version(cls, attribute, context, binary):
services = ServiceList.get_all_by_binary(context, binary)
min_ver = None
min_ver_str = None
for s in services:
ver_str = getattr(s, attribute)
if ver_str is None:
# FIXME(dulek) None in *_current_version means that this
# service is in Liberty version, so we must assume this is the
# lowest one. We use handy and easy to remember token to
# indicate that. This may go away as soon as we drop
# compatibility with Liberty, possibly in early N.
return 'liberty'
ver = versionutils.convert_version_to_int(ver_str)
if min_ver is None or ver < min_ver:
min_ver = ver
min_ver_str = ver_str
return min_ver_str
@base.remotable_classmethod
def get_minimum_rpc_version(cls, context, binary):
return cls._get_minimum_version('rpc_current_version', context, binary)
@base.remotable_classmethod
def get_minimum_obj_version(cls, context, binary):
return cls._get_minimum_version('object_current_version', context,
binary)
@base.CinderObjectRegistry.register
class ServiceList(base.ObjectListBase, base.CinderObject):
# Version 1.0: Initial version
# Version 1.1: Service object 1.2
VERSION = '1.1'
fields = {
'objects': fields.ListOfObjectsField('Service'),
}
child_versions = {
'1.0': '1.0',
'1.1': '1.2',
}
@base.remotable_classmethod
def get_all(cls, context, filters=None):
services = db.service_get_all(context, filters)
return base.obj_make_list(context, cls(context), objects.Service,
services)
@base.remotable_classmethod
def get_all_by_topic(cls, context, topic, disabled=None):
services = db.service_get_all_by_topic(context, topic,
disabled=disabled)
return base.obj_make_list(context, cls(context), objects.Service,
services)
@base.remotable_classmethod
def get_all_by_binary(cls, context, binary, disabled=None):
services = db.service_get_all_by_binary(context, binary,
disabled=disabled)
return base.obj_make_list(context, cls(context), objects.Service,
services)