237746a6d6
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
132 lines
5.6 KiB
Python
132 lines
5.6 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (c) 2013 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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import random
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from oslo.config import cfg
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from neutron.common import constants
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from neutron.db import agents_db
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from neutron.db import agentschedulers_db
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from neutron.openstack.common.db import exception as db_exc
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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 ChanceScheduler(object):
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"""Allocate a DHCP agent for a network in a random way.
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More sophisticated scheduler (similar to filter scheduler in nova?)
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can be introduced later.
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"""
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def _schedule_bind_network(self, context, agents, network_id):
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for agent in agents:
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context.session.begin(subtransactions=True)
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try:
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binding = agentschedulers_db.NetworkDhcpAgentBinding()
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binding.dhcp_agent = agent
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binding.network_id = network_id
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context.session.add(binding)
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# try to actually write the changes and catch integrity
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# DBDuplicateEntry
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context.session.commit()
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except db_exc.DBDuplicateEntry:
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# it's totally ok, someone just did our job!
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context.session.rollback()
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LOG.info(_('Agent %s already present'), agent)
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LOG.debug(_('Network %(network_id)s is scheduled to be '
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'hosted by DHCP agent %(agent_id)s'),
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{'network_id': network_id,
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'agent_id': agent})
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def schedule(self, plugin, context, network):
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"""Schedule the network to active DHCP agent(s).
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A list of scheduled agents is returned.
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"""
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agents_per_network = cfg.CONF.dhcp_agents_per_network
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#TODO(gongysh) don't schedule the networks with only
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# subnets whose enable_dhcp is false
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with context.session.begin(subtransactions=True):
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dhcp_agents = plugin.get_dhcp_agents_hosting_networks(
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context, [network['id']], active=True)
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if len(dhcp_agents) >= agents_per_network:
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LOG.debug(_('Network %s is hosted already'),
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network['id'])
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return
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n_agents = agents_per_network - len(dhcp_agents)
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enabled_dhcp_agents = plugin.get_agents_db(
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context, filters={
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'agent_type': [constants.AGENT_TYPE_DHCP],
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'admin_state_up': [True]})
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if not enabled_dhcp_agents:
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LOG.warn(_('No more DHCP agents'))
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return
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active_dhcp_agents = [
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agent for agent in set(enabled_dhcp_agents)
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if not agents_db.AgentDbMixin.is_agent_down(
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agent['heartbeat_timestamp'])
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and agent not in dhcp_agents
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]
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if not active_dhcp_agents:
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LOG.warn(_('No more DHCP agents'))
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return
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n_agents = min(len(active_dhcp_agents), n_agents)
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chosen_agents = random.sample(active_dhcp_agents, n_agents)
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self._schedule_bind_network(context, chosen_agents, network['id'])
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return chosen_agents
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def auto_schedule_networks(self, plugin, context, host):
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"""Schedule non-hosted networks to the DHCP agent on
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the specified host.
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"""
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agents_per_network = cfg.CONF.dhcp_agents_per_network
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with context.session.begin(subtransactions=True):
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query = context.session.query(agents_db.Agent)
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query = query.filter(agents_db.Agent.agent_type ==
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constants.AGENT_TYPE_DHCP,
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agents_db.Agent.host == host,
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agents_db.Agent.admin_state_up == True)
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dhcp_agents = query.all()
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for dhcp_agent in dhcp_agents:
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if agents_db.AgentDbMixin.is_agent_down(
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dhcp_agent.heartbeat_timestamp):
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LOG.warn(_('DHCP agent %s is not active'), dhcp_agent.id)
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continue
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fields = ['network_id', 'enable_dhcp']
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subnets = plugin.get_subnets(context, fields=fields)
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net_ids = set(s['network_id'] for s in subnets
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if s['enable_dhcp'])
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if not net_ids:
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LOG.debug(_('No non-hosted networks'))
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return False
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for net_id in net_ids:
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agents = plugin.get_dhcp_agents_hosting_networks(
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context, [net_id], active=True)
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if len(agents) >= agents_per_network:
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continue
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if any(dhcp_agent.id == agent.id for agent in agents):
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continue
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binding = agentschedulers_db.NetworkDhcpAgentBinding()
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binding.dhcp_agent = dhcp_agent
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binding.network_id = net_id
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context.session.add(binding)
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return True
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