def KillOldFlows(self):
    """Disable cron flow if it has exceeded CRON_ARGS.lifetime.

    Returns:
      bool: True if the flow is was killed.
    """
    if not self.IsRunning():
      return False

    start_time = self.Get(self.Schema.LAST_RUN_TIME)
    lifetime = self.Get(self.Schema.CRON_ARGS).lifetime

    elapsed = rdfvalue.RDFDatetime.Now() - start_time

    if lifetime and elapsed > lifetime:
      self.StopCurrentRun()
      stats_collector_instance.Get().IncrementCounter(
          "cron_job_timeout", fields=[self.urn.Basename()])
      stats_collector_instance.Get().RecordEvent(
          "cron_job_latency", elapsed.seconds, fields=[self.urn.Basename()])
      return True

    return False
Disable cron flow if it has exceeded CRON_ARGS.lifetime.

    Returns:
      bool: True if the flow is was killed.