vmware-nsx/neutron/scheduler/dhcp_agent_scheduler.py
Eugene Nikanorov 17e13319e8 Fix race condition in network scheduling to dhcp agent
Rarely dhcp agent rpc call get_active_networks_info() can interleave
with network scheduling initiated by create.port.end notification.
In this case scheduling raises and port creation returns 500.
Need to synchronize on DhcpNetworkBindings table.

Closes-Bug: #1276552
Change-Id: I52d94a40772a99c7032dba15b200bf0f21362f93
2014-02-06 15:40:54 +04:00

130 lines
5.4 KiB
Python

# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright (c) 2013 OpenStack Foundation.
# All Rights Reserved.
#
# 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 random
from oslo.config import cfg
from neutron.common import constants
from neutron.db import agents_db
from neutron.db import agentschedulers_db
from neutron.openstack.common.db import exception as db_exc
from neutron.openstack.common import log as logging
LOG = logging.getLogger(__name__)
class ChanceScheduler(object):
"""Allocate a DHCP agent for a network in a random way.
More sophisticated scheduler (similar to filter scheduler in nova?)
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(self, plugin, context, network):
"""Schedule the network to active DHCP agent(s).
A list of scheduled agents is returned.
"""
agents_per_network = cfg.CONF.dhcp_agents_per_network
#TODO(gongysh) don't schedule the networks with only
# subnets whose enable_dhcp is false
with context.session.begin(subtransactions=True):
dhcp_agents = plugin.get_dhcp_agents_hosting_networks(
context, [network['id']], active=True)
if len(dhcp_agents) >= agents_per_network:
LOG.debug(_('Network %s is hosted already'),
network['id'])
return
n_agents = agents_per_network - len(dhcp_agents)
enabled_dhcp_agents = plugin.get_agents_db(
context, filters={
'agent_type': [constants.AGENT_TYPE_DHCP],
'admin_state_up': [True]})
if not enabled_dhcp_agents:
LOG.warn(_('No more DHCP agents'))
return
active_dhcp_agents = [
agent for agent in set(enabled_dhcp_agents)
if not agents_db.AgentDbMixin.is_agent_down(
agent['heartbeat_timestamp'])
and agent not in dhcp_agents
]
if not active_dhcp_agents:
LOG.warn(_('No more DHCP agents'))
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'])
return chosen_agents
def auto_schedule_networks(self, plugin, context, host):
"""Schedule non-hosted networks to the DHCP agent on
the specified host.
"""
agents_per_network = cfg.CONF.dhcp_agents_per_network
with context.session.begin(subtransactions=True):
query = context.session.query(agents_db.Agent)
query = query.filter(agents_db.Agent.agent_type ==
constants.AGENT_TYPE_DHCP,
agents_db.Agent.host == host,
agents_db.Agent.admin_state_up == True)
dhcp_agents = query.all()
for dhcp_agent in dhcp_agents:
if agents_db.AgentDbMixin.is_agent_down(
dhcp_agent.heartbeat_timestamp):
LOG.warn(_('DHCP agent %s is not active'), dhcp_agent.id)
continue
fields = ['network_id', 'enable_dhcp']
subnets = plugin.get_subnets(context, fields=fields)
net_ids = set(s['network_id'] for s in subnets
if s['enable_dhcp'])
if not net_ids:
LOG.debug(_('No non-hosted networks'))
return False
for net_id in net_ids:
agents = plugin.get_dhcp_agents_hosting_networks(
context, [net_id], active=True)
if len(agents) >= agents_per_network:
continue
if any(dhcp_agent.id == agent.id for agent in agents):
continue
binding = agentschedulers_db.NetworkDhcpAgentBinding()
binding.dhcp_agent = dhcp_agent
binding.network_id = net_id
context.session.add(binding)
return True