presto-main/src/main/java/io/prestosql/operator/SpatialJoinOperator.java/SpatialJoinOperatorFactory/noMoreOperators
class SpatialJoinOperatorFactory:        @Override
        public void noMoreOperators()
        {
            if (closed) {
                return;
            }

            referenceCount.release();
            closed = true;
        }