Files
deb-python-taskflow/taskflow/jobs/backends/__init__.py
2014-05-07 22:33:32 +00:00

68 lines
2.3 KiB
Python

# -*- coding: utf-8 -*-
# Copyright (C) 2014 Yahoo! 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 contextlib
import logging
import six
from stevedore import driver
from taskflow import exceptions as exc
from taskflow.utils import misc
# NOTE(harlowja): this is the entrypoint namespace, not the module namespace.
BACKEND_NAMESPACE = 'taskflow.jobboards'
LOG = logging.getLogger(__name__)
def fetch(name, conf, namespace=BACKEND_NAMESPACE, **kwargs):
"""Fetch a jobboard backend with the given configuration (and any board
specific kwargs) in the given entrypoint namespace and create it with the
given name.
"""
if isinstance(conf, six.string_types):
conf = {'board': conf}
board = conf['board']
try:
pieces = misc.parse_uri(board)
except (TypeError, ValueError):
pass
else:
board = pieces['scheme']
conf = misc.merge_uri(pieces, conf.copy())
LOG.debug('Looking for %r jobboard driver in %r', board, namespace)
try:
mgr = driver.DriverManager(namespace, board,
invoke_on_load=True,
invoke_args=(name, conf),
invoke_kwds=kwargs)
return mgr.driver
except RuntimeError as e:
raise exc.NotFound("Could not find jobboard %s" % (board), e)
@contextlib.contextmanager
def backend(name, conf, namespace=BACKEND_NAMESPACE, **kwargs):
"""Fetches a jobboard backend, connects to it and allows it to be used in
a context manager statement with the jobboard being closed upon completion.
"""
jb = fetch(name, conf, namespace=namespace, **kwargs)
jb.connect()
with contextlib.closing(jb):
yield jb