Event loop.

def Run(self):
    """Event loop."""
    if data_store.RelationalDBEnabled():
      data_store.REL_DB.RegisterMessageHandler(
          self._ProcessMessageHandlerRequests,
          self.well_known_flow_lease_time,
          limit=100)
      data_store.REL_DB.RegisterFlowProcessingHandler(self.ProcessFlow)

    try:
      while 1:
        processed = self.RunOnce()
        if processed == 0:
          if time.time() - self.last_active > self.SHORT_POLL_TIME:
            interval = self.POLLING_INTERVAL
          else:
            interval = self.SHORT_POLLING_INTERVAL

          time.sleep(interval)
        else:
          self.last_active = time.time()
    except KeyboardInterrupt:
      logging.info("Caught interrupt, exiting.")
      self.thread_pool.Join()