88fe8afe50
Code handling agents status updates coming via RPC checks, if a corresponding entry for the given (agent_type, host) pair already exists in DB and updates it. And if it doesn't exist, a new entry is created. Without a unique constraint this can cause a race condition resulting in adding of two agent entries having the same value of (agent_type, host) pair. Note, that it's already not allowed to have multiple agents of the same type having the same host value, but currently it's enforced only at code level, not at DB schema level, which effectively makes race conditions possible. Closes-Bug: #1254246 Change-Id: I1ebaa111154b3d6b34074705b579097ab730594c
87 lines
3.1 KiB
Python
87 lines
3.1 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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#
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# Copyright (c) 2013 OpenStack Foundation.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import mock
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from neutron import context
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from neutron.db import agents_db
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from neutron.db import api as db
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from neutron.db import db_base_plugin_v2 as base_plugin
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from neutron.openstack.common.db import exception as exc
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from neutron.tests import base
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class FakePlugin(base_plugin.NeutronDbPluginV2, agents_db.AgentDbMixin):
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"""A fake plugin class containing all DB methods."""
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class TestAgentsDbMixin(base.BaseTestCase):
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def setUp(self):
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super(TestAgentsDbMixin, self).setUp()
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self.context = context.get_admin_context()
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self.plugin = FakePlugin()
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self.addCleanup(db.clear_db)
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self.agent_status = {
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'agent_type': 'Open vSwitch agent',
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'binary': 'neutron-openvswitch-agent',
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'host': 'overcloud-notcompute',
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'topic': 'N/A'
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}
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def _assert_ref_fields_are_equal(self, reference, result):
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"""Compare (key, value) pairs of a reference dict with the result
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Note: the result MAY have additional keys
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"""
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for field, value in reference.items():
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self.assertEqual(value, result[field], field)
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def test_create_or_update_agent_new_entry(self):
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self.plugin.create_or_update_agent(self.context, self.agent_status)
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agent = self.plugin.get_agents(self.context)[0]
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self._assert_ref_fields_are_equal(self.agent_status, agent)
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def test_create_or_update_agent_existing_entry(self):
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self.plugin.create_or_update_agent(self.context, self.agent_status)
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self.plugin.create_or_update_agent(self.context, self.agent_status)
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self.plugin.create_or_update_agent(self.context, self.agent_status)
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agents = self.plugin.get_agents(self.context)
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self.assertEqual(len(agents), 1)
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agent = agents[0]
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self._assert_ref_fields_are_equal(self.agent_status, agent)
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def test_create_or_update_agent_concurrent_insert(self):
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# NOTE(rpodolyaka): emulate violation of the unique constraint caused
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# by a concurrent insert. Ensure we make another
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# attempt on fail
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with mock.patch('sqlalchemy.orm.Session.add') as add_mock:
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add_mock.side_effect = [
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exc.DBDuplicateEntry(columns=['agent_type', 'host']),
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None
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]
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self.plugin.create_or_update_agent(self.context, self.agent_status)
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self.assertEqual(add_mock.call_count, 2,
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"Agent entry creation hasn't been retried")
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