commit 61dcc805e536af0f160225cc928aa188aa861225
author stiga-huang <huangquanlong@gmail.com> Tue Aug 11 16:35:15 2020 +0800
committer Impala Public Jenkins <impala-public-jenkins@cloudera.com> Thu Aug 27 04:09:58 2020 +0000
tree df9e3fe11df578ba90d0ec85c636e4dc8587115c
parent 0fcf846592072e35a1d693ee432b8a0216e229ee

IMPALA-9225: Query option for retryable queries to spool all results before returning any to the client

If we have returned any results to the client in the original query,
query retry will be skipped to avoid incorrect results. This patch adds
a query option, spool_all_results_for_retries, for retryable queries to
spool all results before returning any to the client. It defaults to
true. If all query results cannot be contained in the allocated result
spooling space, we'll return results and thus disabled query retry on
the query.

Setting spool_all_results_for_retries to false will fallback to the
original behavior - client can fetch results when any of them are ready.
So we explicitly set it to false in the retried query since it won't be
retried. For non retryable queries or queries that don't enable results
spooling, the spool_all_results_for_retries option takes no effect.

To implement this, this patch defers the time when results are ready to
be fetched. By default, the “rows available” event happens when any
results are ready. For a retryable query, when spool_query_results and
spool_all_results_for_retries are both true, the “rows available” event
happens after all results are spooled or any errors stopping us to do
so, e.g. batch queue is full, cancellation or failures. After waiting
for the root fragment instance’s Open() finishes, the coordinator will
wait until results of BufferedPlanRootSink are ready.
BufferedPlanRootSink sets the results ready signal in its Send(),
Close(), Cancel(), FlushFinal() methods.

Tests:
- Add a test to verify that a retryable query will spool all its results
  when results spooling and spool_all_results_for_retries are enabled.
- Add a test to verify that query retry succeeds when a retryable query
  is still spooling its results (spool_all_results_for_retries=true).
- Add a test to verify that the retried query won't spool all results
  even when results spooling and spool_all_results_for_retries are
  enabled in the original query.
- Add a test to verify that the original query can be canceled
  correctly. We need this because the added logics for
  spool_all_results_for_retries are related to the cancellation code
  path.
- Add a test to verify results will be returned when all of them can't
  fit into the result spooling space, and query retry will be skipped.

Change-Id: I462dbfef9ddab9060b30a6937fca9122484a24a5
Reviewed-on: http://gerrit.cloudera.org:8080/16323
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>