neutron/neutron/db/common_db_mixin.py

263 lines
11 KiB
Python

# Copyright (c) 2014 OpenStack Foundation.
# All Rights Reserved.
#
# 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.
import weakref
import six
from sqlalchemy import and_
from sqlalchemy import or_
from sqlalchemy import sql
from neutron.common import exceptions as n_exc
from neutron.db import sqlalchemyutils
def model_query_scope(context, model):
# Unless a context has 'admin' or 'advanced-service' rights the
# query will be scoped to a single tenant_id
return ((not context.is_admin and hasattr(model, 'tenant_id')) and
(not context.is_advsvc and hasattr(model, 'tenant_id')))
def model_query(context, model):
query = context.session.query(model)
# define basic filter condition for model query
query_filter = None
if model_query_scope(context, model):
query_filter = (model.tenant_id == context.tenant_id)
if query_filter is not None:
query = query.filter(query_filter)
return query
class CommonDbMixin(object):
"""Common methods used in core and service plugins."""
# Plugins, mixin classes implementing extension will register
# hooks into the dict below for "augmenting" the "core way" of
# building a query for retrieving objects from a model class.
# To this aim, the register_model_query_hook and unregister_query_hook
# from this class should be invoked
_model_query_hooks = {}
# This dictionary will store methods for extending attributes of
# api resources. Mixins can use this dict for adding their own methods
# TODO(salvatore-orlando): Avoid using class-level variables
_dict_extend_functions = {}
@classmethod
def register_model_query_hook(cls, model, name, query_hook, filter_hook,
result_filters=None):
"""Register a hook to be invoked when a query is executed.
Add the hooks to the _model_query_hooks dict. Models are the keys
of this dict, whereas the value is another dict mapping hook names to
callables performing the hook.
Each hook has a "query" component, used to build the query expression
and a "filter" component, which is used to build the filter expression.
Query hooks take as input the query being built and return a
transformed query expression.
Filter hooks take as input the filter expression being built and return
a transformed filter expression
"""
cls._model_query_hooks.setdefault(model, {})[name] = {
'query': query_hook, 'filter': filter_hook,
'result_filters': result_filters}
@classmethod
def register_dict_extend_funcs(cls, resource, funcs):
cls._dict_extend_functions.setdefault(resource, []).extend(funcs)
@property
def safe_reference(self):
"""Return a weakref to the instance.
Minimize the potential for the instance persisting
unnecessarily in memory by returning a weakref proxy that
won't prevent deallocation.
"""
return weakref.proxy(self)
def model_query_scope(self, context, model):
return model_query_scope(context, model)
def _model_query(self, context, model):
query = context.session.query(model)
# define basic filter condition for model query
query_filter = None
if self.model_query_scope(context, model):
if hasattr(model, 'rbac_entries'):
rbac_model, join_params = self._get_rbac_query_params(model)
query = query.outerjoin(*join_params)
query_filter = (
(model.tenant_id == context.tenant_id) |
((rbac_model.action == 'access_as_shared') &
((rbac_model.target_tenant == context.tenant_id) |
(rbac_model.target_tenant == '*'))))
elif hasattr(model, 'shared'):
query_filter = ((model.tenant_id == context.tenant_id) |
(model.shared == sql.true()))
else:
query_filter = (model.tenant_id == context.tenant_id)
# Execute query hooks registered from mixins and plugins
for _name, hooks in six.iteritems(self._model_query_hooks.get(model,
{})):
query_hook = hooks.get('query')
if isinstance(query_hook, six.string_types):
query_hook = getattr(self, query_hook, None)
if query_hook:
query = query_hook(context, model, query)
filter_hook = hooks.get('filter')
if isinstance(filter_hook, six.string_types):
filter_hook = getattr(self, filter_hook, None)
if filter_hook:
query_filter = filter_hook(context, model, query_filter)
# NOTE(salvatore-orlando): 'if query_filter' will try to evaluate the
# condition, raising an exception
if query_filter is not None:
query = query.filter(query_filter)
return query
def _fields(self, resource, fields):
if fields:
return dict(((key, item) for key, item in resource.items()
if key in fields))
return resource
def _get_tenant_id_for_create(self, context, resource):
if context.is_admin and 'tenant_id' in resource:
tenant_id = resource['tenant_id']
elif ('tenant_id' in resource and
resource['tenant_id'] != context.tenant_id):
reason = _('Cannot create resource for another tenant')
raise n_exc.AdminRequired(reason=reason)
else:
tenant_id = context.tenant_id
return tenant_id
def _get_by_id(self, context, model, id):
query = self._model_query(context, model)
return query.filter(model.id == id).one()
@staticmethod
def _get_rbac_query_params(model):
"""Return the class and join params for the rbac relationship."""
try:
cls = model.rbac_entries.property.mapper.class_
return (cls, (cls, ))
except AttributeError:
# an association proxy is being used (e.g. subnets
# depends on network's rbac entries)
rbac_model = (model.rbac_entries.target_class.
rbac_entries.property.mapper.class_)
return (rbac_model, model.rbac_entries.attr)
def _apply_filters_to_query(self, query, model, filters, context=None):
if filters:
for key, value in six.iteritems(filters):
column = getattr(model, key, None)
# NOTE(kevinbenton): if column is a hybrid property that
# references another expression, attempting to convert to
# a boolean will fail so we must compare to None.
# See "An Important Expression Language Gotcha" in:
# docs.sqlalchemy.org/en/rel_0_9/changelog/migration_06.html
if column is not None:
if not value:
query = query.filter(sql.false())
return query
query = query.filter(column.in_(value))
elif key == 'shared' and hasattr(model, 'rbac_entries'):
# translate a filter on shared into a query against the
# object's rbac entries
rbac, join_params = self._get_rbac_query_params(model)
query = query.outerjoin(*join_params, aliased=True)
matches = [rbac.target_tenant == '*']
if context:
matches.append(rbac.target_tenant == context.tenant_id)
is_shared = and_(
~rbac.object_id.is_(None),
rbac.action == 'access_as_shared',
or_(*matches)
)
query = query.filter(is_shared if value[0] else ~is_shared)
for _nam, hooks in six.iteritems(self._model_query_hooks.get(model,
{})):
result_filter = hooks.get('result_filters', None)
if isinstance(result_filter, six.string_types):
result_filter = getattr(self, result_filter, None)
if result_filter:
query = result_filter(query, filters)
return query
def _apply_dict_extend_functions(self, resource_type,
response, db_object):
for func in self._dict_extend_functions.get(
resource_type, []):
args = (response, db_object)
if isinstance(func, six.string_types):
func = getattr(self, func, None)
else:
# must call unbound method - use self as 1st argument
args = (self,) + args
if func:
func(*args)
def _get_collection_query(self, context, model, filters=None,
sorts=None, limit=None, marker_obj=None,
page_reverse=False):
collection = self._model_query(context, model)
collection = self._apply_filters_to_query(collection, model, filters,
context)
if limit and page_reverse and sorts:
sorts = [(s[0], not s[1]) for s in sorts]
collection = sqlalchemyutils.paginate_query(collection, model, limit,
sorts,
marker_obj=marker_obj)
return collection
def _get_collection(self, context, model, dict_func, filters=None,
fields=None, sorts=None, limit=None, marker_obj=None,
page_reverse=False):
query = self._get_collection_query(context, model, filters=filters,
sorts=sorts,
limit=limit,
marker_obj=marker_obj,
page_reverse=page_reverse)
items = [dict_func(c, fields) for c in query]
if limit and page_reverse:
items.reverse()
return items
def _get_collection_count(self, context, model, filters=None):
return self._get_collection_query(context, model, filters).count()
def _get_marker_obj(self, context, resource, limit, marker):
if limit and marker:
return getattr(self, '_get_%s' % resource)(context, marker)
return None
def _filter_non_model_columns(self, data, model):
"""Remove all the attributes from data which are not columns of
the model passed as second parameter.
"""
columns = [c.name for c in model.__table__.columns]
return dict((k, v) for (k, v) in
six.iteritems(data) if k in columns)