tests/util/cancel_util.py

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import threading
from time import sleep
from tests.beeswax.impala_beeswax import ImpalaBeeswaxException
from tests.common.impala_test_suite import ImpalaTestSuite


def cancel_query_and_validate_state(client, query, exec_option, table_format,
    cancel_delay, join_before_close=False):
  """Runs the given query asynchronously and then cancels it after the specified delay.
  The query is run with the given 'exec_options' against the specified 'table_format'. A
  separate async thread is launched to fetch the results of the query. The method
  validates that the query was successfully cancelled and that the error messages for the
  calls to ImpalaConnection#fetch and #close are consistent. If 'join_before_close' is
  True the method will join against the fetch results thread before closing the query.
  """
  if exec_option: client.set_configuration(exec_option)
  if table_format: ImpalaTestSuite.change_database(client, table_format)
  handle = client.execute_async(query)

  thread = threading.Thread(target=__fetch_results, args=(query, handle))
  thread.start()

  sleep(cancel_delay)
  assert client.get_state(handle) != client.QUERY_STATES['EXCEPTION']
  cancel_result = client.cancel(handle)
  assert cancel_result.status_code == 0,\
      'Unexpected status code from cancel request: %s' % cancel_result

  if join_before_close:
    thread.join()

  close_error = None
  try:
    client.close_query(handle)
  except ImpalaBeeswaxException as e:
    close_error = e

  # Before accessing fetch_results_error we need to join the fetch thread
  thread.join()

  if thread.fetch_results_error is None:
    # If the fetch rpc didn't result in CANCELLED (and auto-close the query) then
    # the close rpc should have succeeded.
    assert close_error is None
  elif close_error is None:
    # If the close rpc succeeded, then the fetch rpc should have either succeeded,
    # failed with 'Cancelled' or failed with 'Invalid query handle' (if the close
    # rpc occured before the fetch rpc).
    if thread.fetch_results_error is not None:
      assert 'Cancelled' in str(thread.fetch_results_error) or \
        ('Invalid query handle' in str(thread.fetch_results_error)
         and not join_before_close)
  else:
    # If the close rpc encountered an exception, then it must be due to fetch
    # noticing the cancellation and doing the auto-close.
    assert 'Invalid or unknown query handle' in str(close_error)
    assert 'Cancelled' in str(thread.fetch_results_error)

  # TODO: Add some additional verification to check to make sure the query was
  # actually canceled


def __fetch_results(query, handle):
  threading.current_thread().fetch_results_error = None
  threading.current_thread().query_profile = None
  try:
    new_client = ImpalaTestSuite.create_impala_client()
    new_client.fetch(query, handle)
  except ImpalaBeeswaxException as e:
    threading.current_thread().fetch_results_error = e