66 lines
2.2 KiB
Python
66 lines
2.2 KiB
Python
"""
|
|
(c) Copyright 2014,2015 Hewlett-Packard Development Company, L.P.
|
|
(C) Copyright 2016-2018 Hewlett Packard Enterprise Development Company LP
|
|
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 sys
|
|
|
|
from oslo_log import log
|
|
from oslo_utils import importutils
|
|
from stevedore import driver
|
|
|
|
LOG = log.getLogger(__name__)
|
|
|
|
|
|
_DB_DRIVER_NAMESPACE = "freezer.db.backends"
|
|
|
|
|
|
def _load_class_by_alias_or_classname(namespace, name):
|
|
"""Load class using stevedore alias or the class name
|
|
:param namespace: namespace where the alias is defined
|
|
:param name: alias or class name of the class to be loaded
|
|
:returns: class if calls can be loaded
|
|
:raises ImportError if class cannot be loaded
|
|
"""
|
|
|
|
if not name:
|
|
LOG.error("Alias or class name is not set")
|
|
raise ImportError("Class not found.")
|
|
try:
|
|
# Try to resolve class by alias
|
|
mgr = driver.DriverManager(
|
|
namespace, name, warn_on_missing_entrypoint=False)
|
|
class_to_load = mgr.driver
|
|
except RuntimeError:
|
|
e1_info = sys.exc_info()
|
|
# Fallback to class name
|
|
try:
|
|
class_to_load = importutils.import_class(name)
|
|
except (ImportError, ValueError):
|
|
LOG.error("Error loading class by alias",
|
|
exc_info=e1_info)
|
|
LOG.error("Error loading class by class name",
|
|
exc_info=True)
|
|
raise ImportError("Class not found.")
|
|
return class_to_load
|
|
|
|
|
|
def get_db_driver(name, backend):
|
|
"""
|
|
Loads database driver
|
|
:param name: name of the database driver.
|
|
:return: Instance of the driver class
|
|
"""
|
|
driver_class = _load_class_by_alias_or_classname(_DB_DRIVER_NAMESPACE,
|
|
name)
|
|
return driver_class(backend=backend)
|