text: # Copyright 2015 Hewlett-Packard Development Company, L.P.
  #
  # 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 time
  
  from concurrent import futures
  from oslo_config import cfg
  from oslo_log import log as logging
  
  from octavia.controller.worker import controller_worker as cw
  from octavia.db import api as db_api
  from octavia.db import repositories as repo
  from octavia.i18n import _LI
  
  CONF = cfg.CONF
  LOG = logging.getLogger(__name__)
  
  
  class HealthManager(object):
      def __init__(self):
          self.cw = cw.ControllerWorker()
          self.threads = CONF.health_manager.failover_threads
  
      def health_check(self):
          amp_health_repo = repo.AmphoraHealthRepository()
  
          with futures.ThreadPoolExecutor(max_workers=self.threads) as executor:
              try:
                  # Don't start checking immediately, as the health manager may
                  # have been down for a while and amphorae not able to check in.
                  LOG.debug("Pausing before starting health check")
                  time.sleep(CONF.health_manager.heartbeat_timeout)
                  while True:
                      session = db_api.get_session()
                      LOG.debug("Starting amphora health check")
                      failover_count = 0
                      while True:
                          amp = amp_health_repo.get_stale_amphora(session)
                          if amp is None:
                              break
                          failover_count += 1
                          LOG.info(_LI("Stale amphora's id is: %s"),
                                   amp.amphora_id)
                          executor.submit(self.cw.failover_amphora,
                                          amp.amphora_id)
                      if failover_count > 0:
                          LOG.info(_LI("Failed over %s amphora"),
                                   failover_count)
                      time.sleep(CONF.health_manager.health_check_interval)
              finally:
                  executor.shutdown(wait=True)
  