def OnStartup(self):
    """A handler that is called on client startup."""
    # We read the transaction log and fail any requests that are in it. If there
    # is anything in the transaction log we assume its there because we crashed
    # last time and let the server know.

    last_request = self.transaction_log.Get()
    if last_request:
      status = rdf_flows.GrrStatus(
          status=rdf_flows.GrrStatus.ReturnedStatus.CLIENT_KILLED,
          error_message="Client killed during transaction")
      if self.nanny_controller:
        nanny_status = self.nanny_controller.GetNannyStatus()
        if nanny_status:
          status.nanny_status = nanny_status

      self.SendReply(
          status,
          request_id=last_request.request_id,
          response_id=1,
          session_id=last_request.session_id,
          message_type=rdf_flows.GrrMessage.Type.STATUS)

    self.transaction_log.Clear()

    # Inform the server that we started.
    action = admin.SendStartupInfo(grr_worker=self)
    action.Run(None, ttl=1)
A handler that is called on client startup.