old_contents: #    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.
  
  from neutron._i18n import _LW
  from neutron.notifiers import nova as n_nova
  from novaclient import exceptions as nova_exceptions
  from oslo_log import log as logging
  
  
  LOG = logging.getLogger(__name__)
  
  
  client = None
  
  
  def _get_client():
      global client
      if client is None:
          client = n_nova.Notifier().nclient
      return client
  
  
  class NovaClient(object):
  
      def __init__(self):
          self.client = n_nova.Notifier().nclient
  
      def get_server(self, server_id):
          try:
              return self.client.servers.get(server_id)
          except nova_exceptions.NotFound:
              LOG.warning(_LW("Nova returned NotFound for server: %s"),
                          server_id)
          except Exception as e:
              LOG.exception(e)
  
new_contents: #    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.
  
  from neutron._i18n import _LW
  from neutron.notifiers import nova as n_nova
  from novaclient import exceptions as nova_exceptions
  from oslo_log import log as logging
  
  
  LOG = logging.getLogger(__name__)
  
  
  client = None
  
  
  def _get_client():
      global client
      if client is None:
          client = n_nova.Notifier().nclient
      return client
  
  
  class NovaClient(object):
  
      def __init__(self):
          self.client = _get_client()
  
      def get_server(self, server_id):
          try:
              return self.client.servers.get(server_id)
          except nova_exceptions.NotFound:
              LOG.warning(_LW("Nova returned NotFound for server: %s"),
                          server_id)
          except Exception as e:
              LOG.exception(e)
  
subject: Fix NovaClient singleton pattern