neutron-lib/neutron_lib/worker.py
Akihiro Motoki f9b06e8937 Enable module reference
Also fixes sphinx warnings in existing docstrings.

Change-Id: Iccccd782ff8b80a3fd2764e7ef9cc3dde46e32ee
2017-07-05 12:09:10 +09:00

76 lines
2.6 KiB
Python

# 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 oslo_service import service
from neutron_lib.callbacks import events
from neutron_lib.callbacks import registry
from neutron_lib.callbacks import resources
class BaseWorker(service.ServiceBase):
"""Partial implementation of the ServiceBase ABC.
Subclasses will still need to add the other abstract methods defined in
service.ServiceBase. See oslo_service for more details.
If a plugin needs to handle synchronization with the Neutron database and
do this only once instead of in every API worker, for instance, it would
define a BaseWorker class and the plugin would have get_workers return
an array of BaseWorker instances. For example:
.. code-block:: python
class MyPlugin(...):
def get_workers(self):
return [MyPluginWorker()]
class MyPluginWorker(BaseWorker):
def start(self):
super(MyPluginWorker, self).start()
do_sync()
"""
# default class value for case when super().__init__ is not called
_default_process_count = 1
def __init__(self, worker_process_count=_default_process_count):
"""Initialize a worker instance.
:param worker_process_count: Defines how many processes to spawn for
worker:
0 - spawn 1 new worker thread,
1..N - spawn N new worker processes
"""
self._worker_process_count = worker_process_count
@property
def worker_process_count(self):
"""The worker's process count.
:returns: The number of processes to spawn for this worker.
"""
return self._worker_process_count
def start(self):
"""Start the worker.
If worker_process_count is greater than 0, a callback notification
is sent. Subclasses should call this method before doing their
own start() work.
:returns: None
"""
if self.worker_process_count > 0:
registry.notify(resources.PROCESS, events.AFTER_INIT, self.start)