Method _signal_handler

shell/impala_shell/impala_shell.py:736–770

Handles query cancellation on a Ctrl+C event

(self, signal, frame)

      self.imp_client.close_connection()

  def _signal_handler(self, signal, frame):
    """Handles query cancellation on a Ctrl+C event"""
    if self.last_query_handle is None or self.last_query_handle.is_closed:
      if self.partial_cmd:
        # Revert the prompt to its earlier state
        self.prompt = self.cached_prompt
        # Reset the already given commands
        self.partial_cmd = str()
      raise KeyboardInterrupt()
    # Create a new connection to the impalad and cancel the query.
    # TODO: this isn't thread-safe with respect to the main thread executing the
    # query. This probably contributes to glitchiness when cancelling query in
    # the shell.
    for cancel_try in xrange(ImpalaShell.CANCELLATION_TRIES):
      try:
        self.imp_client.is_query_cancelled = True
        os.write(sys.stderr.fileno(), ImpalaShell.CANCELLATION_MESSAGE.encode('utf-8'))
        new_imp_client = self._new_impala_client()
        new_imp_client.connect()
        try:
          new_imp_client.cancel_query(self.last_query_handle)
          new_imp_client.close_query(self.last_query_handle)
        finally:
          new_imp_client.close_connection()
        break
      except Exception as e:
        # Suppress harmless errors.
        err_msg = str(e).strip()
        # Check twice so that it can work with both the old and the new error formats.
        if err_msg in ['ERROR: Cancelled', 'ERROR: Invalid or unknown query handle'] or \
          ('\nCancelled' in err_msg or '\nInvalid or unknown query handle' in err_msg):
          break
        err_details = "Failed to reconnect and close (try {}/{}): {}".format(
            cancel_try + 1, ImpalaShell.CANCELLATION_TRIES, err_msg)
        os.write(sys.stderr.fileno(), err_details.encode('utf-8'))

  def _is_quit_command(self, command):
    # Do a case insensitive check