Files
deb-python-taskflow/taskflow/persistence/backends/impl_memory.py

237 lines
8.4 KiB
Python

# -*- coding: utf-8 -*-
# Copyright (C) 2012 Yahoo! Inc. All Rights Reserved.
# Copyright (C) 2013 Rackspace Hosting 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 functools
import six
from taskflow import exceptions as exc
from taskflow import logging
from taskflow.persistence import base
from taskflow.persistence import logbook
from taskflow.utils import lock_utils
LOG = logging.getLogger(__name__)
class _Memory(object):
"""Where the data is really stored."""
def __init__(self):
self.log_books = {}
self.flow_details = {}
self.atom_details = {}
def clear_all(self):
self.log_books.clear()
self.flow_details.clear()
self.atom_details.clear()
class _MemoryHelper(object):
"""Helper functionality for the memory backends & connections."""
def __init__(self, memory):
self._memory = memory
@staticmethod
def _fetch_clone_args(incoming):
if isinstance(incoming, (logbook.LogBook, logbook.FlowDetail)):
# We keep our own copy of the added contents of the following
# types so we don't need the clone to retain them directly...
return {
'retain_contents': False,
}
return {}
def construct(self, uuid, container):
"""Reconstructs a object from the given uuid and storage container."""
source = container[uuid]
clone_kwargs = self._fetch_clone_args(source)
clone = source['object'].copy(**clone_kwargs)
rebuilder = source.get('rebuilder')
if rebuilder:
for component in map(rebuilder, source['components']):
clone.add(component)
return clone
def merge(self, incoming, saved_info=None):
"""Merges the incoming object into the local memories copy."""
if saved_info is None:
if isinstance(incoming, logbook.LogBook):
saved_info = self._memory.log_books.setdefault(
incoming.uuid, {})
elif isinstance(incoming, logbook.FlowDetail):
saved_info = self._memory.flow_details.setdefault(
incoming.uuid, {})
elif isinstance(incoming, logbook.AtomDetail):
saved_info = self._memory.atom_details.setdefault(
incoming.uuid, {})
else:
raise TypeError("Unknown how to merge type '%s'"
% type(incoming))
try:
saved_info['object'].merge(incoming)
except KeyError:
clone_kwargs = self._fetch_clone_args(incoming)
saved_info['object'] = incoming.copy(**clone_kwargs)
if isinstance(incoming, logbook.LogBook):
flow_details = saved_info.setdefault('components', set())
if 'rebuilder' not in saved_info:
saved_info['rebuilder'] = functools.partial(
self.construct, container=self._memory.flow_details)
for flow_detail in incoming:
flow_details.add(self.merge(flow_detail))
elif isinstance(incoming, logbook.FlowDetail):
atom_details = saved_info.setdefault('components', set())
if 'rebuilder' not in saved_info:
saved_info['rebuilder'] = functools.partial(
self.construct, container=self._memory.atom_details)
for atom_detail in incoming:
atom_details.add(self.merge(atom_detail))
return incoming.uuid
class MemoryBackend(base.Backend):
"""A in-memory (non-persistent) backend.
This backend writes logbooks, flow details, and atom details to in-memory
dictionaries and retrieves from those dictionaries as needed.
"""
def __init__(self, conf=None):
super(MemoryBackend, self).__init__(conf)
self._memory = _Memory()
self._helper = _MemoryHelper(self._memory)
self._lock = lock_utils.ReaderWriterLock()
def _construct_from(self, container):
return dict((uuid, self._helper.construct(uuid, container))
for uuid in six.iterkeys(container))
@property
def log_books(self):
with self._lock.read_lock():
return self._construct_from(self._memory.log_books)
@property
def flow_details(self):
with self._lock.read_lock():
return self._construct_from(self._memory.flow_details)
@property
def atom_details(self):
with self._lock.read_lock():
return self._construct_from(self._memory.atom_details)
def get_connection(self):
return Connection(self)
def close(self):
pass
class Connection(base.Connection):
"""A connection to an in-memory backend."""
def __init__(self, backend):
self._backend = backend
self._helper = backend._helper
self._memory = backend._memory
self._lock = backend._lock
def upgrade(self):
pass
def validate(self):
pass
@property
def backend(self):
return self._backend
def close(self):
pass
def clear_all(self):
with self._lock.write_lock():
self._memory.clear_all()
def destroy_logbook(self, book_uuid):
with self._lock.write_lock():
try:
# Do the same cascading delete that the sql layer does.
book_info = self._memory.log_books.pop(book_uuid)
except KeyError:
raise exc.NotFound("No logbook found with uuid '%s'"
% book_uuid)
else:
while book_info['components']:
flow_uuid = book_info['components'].pop()
flow_info = self._memory.flow_details.pop(flow_uuid)
while flow_info['components']:
atom_uuid = flow_info['components'].pop()
self._memory.atom_details.pop(atom_uuid)
def update_atom_details(self, atom_detail):
with self._lock.write_lock():
try:
atom_info = self._memory.atom_details[atom_detail.uuid]
return self._helper.construct(
self._helper.merge(atom_detail, saved_info=atom_info),
self._memory.atom_details)
except KeyError:
raise exc.NotFound("No atom details found with uuid '%s'"
% atom_detail.uuid)
def update_flow_details(self, flow_detail):
with self._lock.write_lock():
try:
flow_info = self._memory.flow_details[flow_detail.uuid]
return self._helper.construct(
self._helper.merge(flow_detail, saved_info=flow_info),
self._memory.flow_details)
except KeyError:
raise exc.NotFound("No flow details found with uuid '%s'"
% flow_detail.uuid)
def save_logbook(self, book):
with self._lock.write_lock():
return self._helper.construct(self._helper.merge(book),
self._memory.log_books)
def get_logbook(self, book_uuid):
with self._lock.read_lock():
try:
return self._helper.construct(book_uuid,
self._memory.log_books)
except KeyError:
raise exc.NotFound("No logbook found with uuid '%s'"
% book_uuid)
def get_logbooks(self):
# Don't hold locks while iterating...
with self._lock.read_lock():
book_uuids = set(six.iterkeys(self._memory.log_books))
for book_uuid in book_uuids:
try:
with self._lock.read_lock():
book = self._helper.construct(book_uuid,
self._memory.log_books)
yield book
except KeyError:
pass