Fix DetachedInstanceError for Agent instance

The stacktrace observed seems to hint to a
situation where a session is not properly
rolled back when duplicate agent entries are
found.

Since it is ok to deal with duplicates, the
addition of agents to the DB must be done
one by one, otherwise we go against the
ATOMICITY property of a transaction of all
or none. It's either that or I am barking at
the wrong tree.

This patch also added UT to cover affected
code.

Closes-bug: 1282421
Related-bug: 1282253

Change-Id: Ic5f77808cc10f885d67f5a9cf3b3836283692850
changes/62/74962/6
armando-migliaccio 9 years ago committed by Gerrit Code Review
parent 055bae5c08
commit 237746a6d6

@ -35,22 +35,25 @@ class ChanceScheduler(object):
can be introduced later.
"""
def _schedule_bind_network(self, context, agent, network_id):
try:
binding = agentschedulers_db.NetworkDhcpAgentBinding()
binding.dhcp_agent = agent
binding.network_id = network_id
context.session.add(binding)
# try to actually write the changes and catch integrity
# DBDuplicateEntry
context.session.flush()
except db_exc.DBDuplicateEntry:
# it's totally ok, someone just did our job!
pass
LOG.debug(_('Network %(network_id)s is scheduled to be hosted by '
'DHCP agent %(agent_id)s'),
{'network_id': network_id,
'agent_id': agent})
def _schedule_bind_network(self, context, agents, network_id):
for agent in agents:
context.session.begin(subtransactions=True)
try:
binding = agentschedulers_db.NetworkDhcpAgentBinding()
binding.dhcp_agent = agent
binding.network_id = network_id
context.session.add(binding)
# try to actually write the changes and catch integrity
# DBDuplicateEntry
context.session.commit()
except db_exc.DBDuplicateEntry:
# it's totally ok, someone just did our job!
context.session.rollback()
LOG.info(_('Agent %s already present'), agent)
LOG.debug(_('Network %(network_id)s is scheduled to be '
'hosted by DHCP agent %(agent_id)s'),
{'network_id': network_id,
'agent_id': agent})
def schedule(self, plugin, context, network):
"""Schedule the network to active DHCP agent(s).
@ -87,8 +90,7 @@ class ChanceScheduler(object):
return
n_agents = min(len(active_dhcp_agents), n_agents)
chosen_agents = random.sample(active_dhcp_agents, n_agents)
for agent in chosen_agents:
self._schedule_bind_network(context, agent, network['id'])
self._schedule_bind_network(context, chosen_agents, network['id'])
return chosen_agents
def auto_schedule_networks(self, plugin, context, host):

@ -0,0 +1,90 @@
# Copyright 2014 OpenStack Foundation
#
# 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.
import mock
from neutron.common import constants
from neutron.common import topics
from neutron import context
from neutron.db import agents_db
from neutron.db import agentschedulers_db
from neutron.db import api as db
from neutron.db import models_v2
from neutron.openstack.common import timeutils
from neutron.scheduler import dhcp_agent_scheduler
from neutron.tests import base
class DhcpSchedulerTestCase(base.BaseTestCase):
def setUp(self):
super(DhcpSchedulerTestCase, self).setUp()
db.configure_db()
self.ctx = context.get_admin_context()
self.network_id = 'foo_network_id'
self._save_networks([self.network_id])
self.addCleanup(db.clear_db)
def _get_agents(self, hosts):
return [
agents_db.Agent(
binary='neutron-dhcp-agent',
host=host,
topic=topics.DHCP_AGENT,
configurations="",
agent_type=constants.AGENT_TYPE_DHCP,
created_at=timeutils.utcnow(),
started_at=timeutils.utcnow(),
heartbeat_timestamp=timeutils.utcnow())
for host in hosts
]
def _save_agents(self, agents):
for agent in agents:
with self.ctx.session.begin(subtransactions=True):
self.ctx.session.add(agent)
def _save_networks(self, networks):
for network_id in networks:
with self.ctx.session.begin(subtransactions=True):
self.ctx.session.add(models_v2.Network(id=network_id))
def _test__schedule_bind_network(self, agents, network_id):
scheduler = dhcp_agent_scheduler.ChanceScheduler()
scheduler._schedule_bind_network(self.ctx, agents, network_id)
results = (
self.ctx.session.query(agentschedulers_db.NetworkDhcpAgentBinding).
filter_by(network_id=network_id).all())
self.assertEqual(len(agents), len(results))
for result in results:
self.assertEqual(network_id, result.network_id)
def test__schedule_bind_network_single_agent(self):
agents = self._get_agents(['host-a'])
self._save_agents(agents)
self._test__schedule_bind_network(agents, self.network_id)
def test__schedule_bind_network_multi_agents(self):
agents = self._get_agents(['host-a', 'host-b'])
self._save_agents(agents)
self._test__schedule_bind_network(agents, self.network_id)
def test__schedule_bind_network_multi_agent_fail_one(self):
agents = self._get_agents(['host-a'])
self._save_agents(agents)
self._test__schedule_bind_network(agents, self.network_id)
with mock.patch.object(dhcp_agent_scheduler.LOG, 'info') as fake_log:
self._test__schedule_bind_network(agents, self.network_id)
self.assertEqual(1, fake_log.call_count)
Loading…
Cancel
Save