76 lines
2.6 KiB
Python
76 lines
2.6 KiB
Python
# All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from oslo_service import service
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from neutron_lib.callbacks import events
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from neutron_lib.callbacks import registry
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from neutron_lib.callbacks import resources
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class BaseWorker(service.ServiceBase):
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"""Partial implementation of the ServiceBase ABC.
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Subclasses will still need to add the other abstract methods defined in
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service.ServiceBase. See oslo_service for more details.
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If a plugin needs to handle synchronization with the Neutron database and
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do this only once instead of in every API worker, for instance, it would
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define a BaseWorker class and the plugin would have get_workers return
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an array of BaseWorker instances. For example:
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.. code-block:: python
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class MyPlugin(...):
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def get_workers(self):
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return [MyPluginWorker()]
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class MyPluginWorker(BaseWorker):
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def start(self):
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super(MyPluginWorker, self).start()
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do_sync()
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"""
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# default class value for case when super().__init__ is not called
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_default_process_count = 1
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def __init__(self, worker_process_count=_default_process_count):
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"""Initialize a worker instance.
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:param worker_process_count: Defines how many processes to spawn for
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worker:
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0 - spawn 1 new worker thread,
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1..N - spawn N new worker processes
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"""
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self._worker_process_count = worker_process_count
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@property
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def worker_process_count(self):
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"""The worker's process count.
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:returns: The number of processes to spawn for this worker.
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"""
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return self._worker_process_count
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def start(self):
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"""Start the worker.
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If worker_process_count is greater than 0, a callback notification
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is sent. Subclasses should call this method before doing their
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own start() work.
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:returns: None
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"""
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if self.worker_process_count > 0:
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registry.notify(resources.PROCESS, events.AFTER_INIT, self.start)
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