deb-murano/murano/dsl/meta.py
Stan Lagun 584571c3d8 On-demand garbage collection
Garbage collection is triggered by io.murano.system.GC.collect()
static method. Garbage collector destroys all object that are not
reachable anymore. GC can handle objects with cross-references and
isolated object graphs. When portion of object model becomes not
reachable it destroyed in predictable order such that child objects get
destroyed before their parents and, when possible, before objects
that are subscribed to their destruction notifications.

Internally, both pre-deployment garbage collection (that was done by
comparision of ``Objects`` and ``ObjectsCopy``) and post-deployment
orphan object collection are now done through the new GC.

MuranoPL GC utilizes Python GC to track and collect objects.
The main idea is to make ObjectStore have weak links only and
prevent hard links in other dsl places so that only links between objects
remain. Then prevent Python GC to automatically delete objects that
are not used anymore and use gc.collect() to obtain a list of
objects that are both not reachable and cannot be destroyed and then
destroy them in the correct order.

Targets-blueprint: dependency-driven-resource-deallocation
Closes-Bug: #1619635
Closes-Bug: #1597747
Change-Id: I653d8f71f003afa0a1ea588c9d14198571f5ad14
2016-09-14 03:43:09 +00:00

128 lines
4.6 KiB
Python

# Copyright (c) 2016 Mirantis, Inc.
#
# 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 abc
import operator
import weakref
import six
from murano.dsl import dsl_types
from murano.dsl import helpers
class MetaProvider(object):
@abc.abstractmethod
def get_meta(self, context):
raise NotImplementedError()
class MetaData(MetaProvider):
def __init__(self, definition, target, declaring_type):
declaring_type = weakref.proxy(declaring_type)
definition = helpers.list_value(definition)
factories = []
used_types = set()
for d in definition:
if isinstance(d, dict):
if len(d) != 1:
raise ValueError('Invalid Meta format')
name = next(iter(d.keys()))
props = d[name] or {}
else:
name = d
props = {}
type_obj = helpers.resolve_type(name, declaring_type)
if type_obj.usage != dsl_types.ClassUsages.Meta:
raise ValueError('Only Meta classes can be attached')
if target not in type_obj.targets:
raise ValueError(
u'Meta class {} is not applicable here'.format(
type_obj.name))
if type_obj in used_types and (
type_obj.cardinality != dsl_types.MetaCardinality.Many):
raise ValueError('Cannot attach several Meta instances '
'with cardinality One')
used_types.add(type_obj)
def factory_maker(template):
def instantiate(context):
obj = helpers.get_object_store().load(
template, owner=None,
context=context, scope_type=declaring_type,
bypass_store=True)
obj.declaring_type = declaring_type
return obj
return instantiate
factories.append(factory_maker({type_obj: props}))
self._meta_factories = factories
self._meta = None
def get_meta(self, context):
if self._meta is None:
self._meta = list(map(lambda x: x(context), self._meta_factories))
return self._meta
def merge_providers(initial_class, producer, context):
def merger(cls_list, skip_list):
result = set()
all_meta = []
for cls in cls_list:
cls_skip_list = skip_list.copy()
provider = producer(cls)
meta = [] if provider is None else provider.get_meta(context)
for item in meta:
cardinality = item.type.cardinality
inherited = item.type.inherited
if cls != initial_class and (
not inherited or item.type in skip_list):
continue
if cardinality == dsl_types.MetaCardinality.One:
cls_skip_list.add(item.type)
all_meta.append((cls, item))
all_meta.extend(merger(cls.parents, cls_skip_list))
meta_types = {}
for cls, item in all_meta:
entry = meta_types.get(item.type)
if entry is not None:
if entry != cls:
raise ValueError(
u'Found more than one instance of Meta {} '
u'with Cardinality One'.format(item.type.name))
else:
continue
if item.type.cardinality == dsl_types.MetaCardinality.One:
meta_types[item.type] = cls
result.add((cls, item))
return result
meta = merger([initial_class], set())
return list(six.moves.map(operator.itemgetter(1), meta))
def aggregate_meta(provider, context, group_by_name=True):
key_func = lambda m: m.type.name if group_by_name else m.type
meta = provider.get_meta(context)
result = {}
for item in meta:
if item.type.cardinality == dsl_types.MetaCardinality.One:
result[key_func(item)] = item
else:
result.setdefault(key_func(item), []).append(item)
return result