95 lines
3.4 KiB
Python
95 lines
3.4 KiB
Python
# Copyright 2014 OpenStack Foundation.
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# 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 neutron.openstack.common import lockutils
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from neutron.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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class AdvancedService(object):
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"""Observer base class for Advanced Services.
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Base class for service types. This should not be instantiated normally.
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Instead, a child class is defined for each service type and instantiated
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by the corresponding service agent. The instances will have a back
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reference to the L3 agent, and will register as an observer of events.
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A singleton is used to create only one service object per service type.
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This base class provides a definition for all of the L3 event handlers
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that a service could "observe". A child class for a service type will
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implement handlers, for events of interest.
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"""
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_instance = None
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def __init__(self, l3_agent):
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"""Base class for an advanced service.
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Do not directly instantiate objects of this class. Should only be
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called indirectly by a child class's instance() invocation.
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"""
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self.l3_agent = l3_agent
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# NOTE: Copying L3 agent attributes, so that they are accessible
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# from device drivers, which are now provided a service instance.
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# TODO(pcm): Address this in future refactorings.
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self.conf = l3_agent.conf
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self.root_helper = l3_agent.root_helper
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@classmethod
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def instance(cls, l3_agent):
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"""Creates instance (singleton) of service.
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Do not directly call this for the base class. Instead, it should be
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called by a child class, that represents a specific service type.
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This ensures that only one instance is created for all agents of a
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specific service type.
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"""
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if not cls._instance:
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with lockutils.lock('instance'):
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if not cls._instance:
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cls._instance = cls(l3_agent)
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return cls._instance
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# NOTE: Handler definitions for events generated by the L3 agent.
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# Subclasses of AdvancedService can override these to perform service
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# specific actions. Unique methods are defined for add/update, as
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# some services may want to take different actions.
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def before_router_added(self, ri):
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"""Actions taken before router_info created."""
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pass
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def after_router_added(self, ri):
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"""Actions taken after router_info created."""
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pass
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def before_router_updated(self, ri):
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"""Actions before processing for an updated router."""
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pass
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def after_router_updated(self, ri):
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"""Actions add processing for an updated router."""
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pass
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def before_router_removed(self, ri):
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"""Actions before removing router."""
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pass
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def after_router_removed(self, ri):
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"""Actions after processing and removing router."""
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pass
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