presto-main/src/main/java/io/prestosql/operator/LookupJoinOperator.java/JoinProcessor/finish
class JoinProcessor:        private void finish()
        {
            if (finishing) {
                return;
            }

            if (!spillInProgress.isDone()) {
                return;
            }

            checkSuccess(spillInProgress, "spilling failed");
            finishing = true;
        }