Files
deb-python-taskflow/taskflow/persistence/backends/base.py
Joshua Harlow 58a5a0932d Persistence cleanup part one
- Convert the various functions that take a task detail into
  ones that take atom details (since this is now the generic
  type they should take).
- Don't expose the detail type strings as part of the atom
  detail api, leave those as private hidden strings and provide
  conversion functions from string<->class instead.
- Have the logbook objects contain the following new methods
  to reduce the dependence on persistence_utils to do the same.
  - to_dict() which converts the current object into a dict
  - from_dict() which converts the provided dict into a object
  - merge() which merges a incoming objects data with the current
    objects
- Have the persistence backends + storage + action engine use these
  new methods instead of there current usage.
- Don't compare to logbook.RETRY_DETAIL or logbook.TASK_DETAIL since
  python has the isinstance function just use it (ideally we should
  fix the code so that this isn't even needed, usage of isinstance
  means something is not designed/structured right).
- In storage tests we can't assume that failures will be non-lossy
  since under certain backends when a failure is stored information
  about the internally held exc_info is lost, so take this into
  account when testing by using matches() where applicable.

Change-Id: Ie8a274cfd4cb4e64e87c355dc99d466d74a4e82c
2014-03-26 12:48:40 -07:00

125 lines
3.5 KiB
Python

# -*- coding: utf-8 -*-
# Copyright (C) 2013 Rackspace Hosting Inc. 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 abc
import six
from taskflow.persistence import logbook
@six.add_metaclass(abc.ABCMeta)
class Backend(object):
"""Base class for persistence backends."""
def __init__(self, conf):
if not conf:
conf = {}
if not isinstance(conf, dict):
raise TypeError("Configuration dictionary expected not: %s"
% type(conf))
self._conf = conf
@abc.abstractmethod
def get_connection(self):
"""Return a Connection instance based on the configuration settings."""
pass
@abc.abstractmethod
def close(self):
"""Closes any resources this backend has open."""
pass
@six.add_metaclass(abc.ABCMeta)
class Connection(object):
"""Base class for backend connections."""
@abc.abstractproperty
def backend(self):
"""Returns the backend this connection is associated with."""
pass
@abc.abstractmethod
def close(self):
"""Closes any resources this connection has open."""
pass
@abc.abstractmethod
def upgrade(self):
"""Migrate the persistence backend to the most recent version."""
pass
@abc.abstractmethod
def clear_all(self):
"""Clear all entries from this backend."""
pass
@abc.abstractmethod
def validate(self):
"""Validates that a backend is still ok to be used (the semantics
of this vary depending on the backend). On failure a backend specific
exception is raised that will indicate why the failure occurred.
"""
pass
@abc.abstractmethod
def update_atom_details(self, atom_detail):
"""Updates a given atom details and returns the updated version.
NOTE(harlowja): the details that is to be updated must already have
been created by saving a flow details with the given atom detail inside
of it.
"""
pass
@abc.abstractmethod
def update_flow_details(self, flow_detail):
"""Updates a given flow details and returns the updated version.
NOTE(harlowja): the details that is to be updated must already have
been created by saving a logbook with the given flow detail inside
of it.
"""
pass
@abc.abstractmethod
def save_logbook(self, book):
"""Saves a logbook, and all its contained information."""
pass
@abc.abstractmethod
def destroy_logbook(self, book_uuid):
"""Deletes/destroys a logbook matching the given uuid."""
pass
@abc.abstractmethod
def get_logbook(self, book_uuid):
"""Fetches a logbook object matching the given uuid."""
pass
@abc.abstractmethod
def get_logbooks(self):
"""Return an iterable of logbook objects."""
pass
def _format_atom(atom_detail):
return {
'atom': atom_detail.to_dict(),
'type': logbook.atom_detail_type(atom_detail),
}