Files
deb-python-taskflow/taskflow/persistence/backends/impl_memory.py
Joshua Harlow e417914d49 Make all/most usage of type errors follow a similar pattern
To make it easy to add new type errors and to make the existing
ones have a common string pattern adjust the current type errors
to contain at least the following string format: '%s' (%s) where
these two places will be filled in with the object of the wrong
type and the type of that object. This information is useful when
analyzing the exception (by the user) to know exactly what they
passed in and what type it was.

This convention is not maintained where it would interpolate large
text blobs (such as in binary encoding/decoding and json decoding).

Change-Id: Id84b0e7ce684a543cc407b15016e77804e6f03ed
2015-01-23 18:25:01 -08:00

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 '%s' (%s)"
% (incoming, 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