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# Copyright 2011 OpenStack LLC.
# 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.
from nova.openstack.common import cfg
from nova.openstack.common import importutils
from nova.openstack.common import log as logging
list_notifier_drivers_opt = cfg.MultiStrOpt('list_notifier_drivers',
default=['nova.openstack.common.notifier.no_op_notifier'],
help='List of drivers to send notifications')
CONF = cfg.CONF
CONF.register_opt(list_notifier_drivers_opt)
LOG = logging.getLogger(__name__)
drivers = None
class ImportFailureNotifier(object):
"""Noisily re-raises some exception over-and-over when notify is called."""
def __init__(self, exception):
self.exception = exception
def notify(self, context, message):
raise self.exception
def _get_drivers():
"""Instantiates and returns drivers based on the flag values."""
global drivers
if drivers is None:
drivers = []
for notification_driver in CONF.list_notifier_drivers:
try:
drivers.append(importutils.import_module(notification_driver))
except ImportError as e:
drivers.append(ImportFailureNotifier(e))
return drivers
def add_driver(notification_driver):
"""Add a notification driver at runtime."""
# Make sure the driver list is initialized.
_get_drivers()
if isinstance(notification_driver, basestring):
# Load and add
try:
drivers.append(importutils.import_module(notification_driver))
except ImportError as e:
drivers.append(ImportFailureNotifier(e))
else:
# Driver is already loaded; just add the object.
drivers.append(notification_driver)
def _object_name(obj):
name = []
if hasattr(obj, '__module__'):
name.append(obj.__module__)
if hasattr(obj, '__name__'):
name.append(obj.__name__)
else:
name.append(obj.__class__.__name__)
return '.'.join(name)
def remove_driver(notification_driver):
"""Remove a notification driver at runtime."""
# Make sure the driver list is initialized.
_get_drivers()
removed = False
if notification_driver in drivers:
# We're removing an object. Easy.
drivers.remove(notification_driver)
removed = True
else:
# We're removing a driver by name. Search for it.
for driver in drivers:
if _object_name(driver) == notification_driver:
drivers.remove(driver)
removed = True
if not removed:
raise ValueError("Cannot remove; %s is not in list" %
notification_driver)
def notify(context, message):
"""Passes notification to multiple notifiers in a list."""
for driver in _get_drivers():
try:
driver.notify(context, message)
except Exception as e:
LOG.exception(_("Problem '%(e)s' attempting to send to "
"notification driver %(driver)s."), locals())
def _reset_drivers():
"""Used by unit tests to reset the drivers."""
global drivers
drivers = None
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