70 lines
2.3 KiB
Python
70 lines
2.3 KiB
Python
# 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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import collections
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from oslo_log import log as logging
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from neutron.api.rpc.callbacks import resources
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from neutron.callbacks import exceptions
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LOG = logging.getLogger(__name__)
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class ResourcesCallbacksManager(object):
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"""A callback system that allows information providers in a loose manner.
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"""
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def __init__(self):
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self.clear()
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def register(self, callback, resource):
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"""register callback for a resource .
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One callback can be register to a resource
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:param callback: the callback. It must raise or return a dict.
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:param resource: the resource. It must be a valid resource.
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"""
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LOG.debug("register: %(callback)s %(resource)s",
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{'callback': callback, 'resource': resource})
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if resource not in resources.VALID:
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raise exceptions.Invalid(element='resource', value=resource)
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self._callbacks[resource] = callback
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def unregister(self, resource):
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"""Unregister callback from the registry.
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:param callback: the callback.
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:param resource: the resource.
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"""
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LOG.debug("Unregister: %(resource)s",
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{'resource': resource})
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if resource not in resources.VALID:
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raise exceptions.Invalid(element='resource', value=resource)
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self._callbacks[resource] = None
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def clear(self):
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"""Brings the manager to a clean slate."""
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self._callbacks = collections.defaultdict(dict)
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def get_callback(self, resource):
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"""Return the callback if found, None otherwise.
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:param resource: the resource. It must be a valid resource.
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"""
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if resource not in resources.VALID:
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raise exceptions.Invalid(element='resource', value=resource)
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return self._callbacks[resource]
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