presto-main/src/main/java/io/prestosql/operator/SpatialJoinOperator.java/SpatialJoinOperator/needsInput
class SpatialJoinOperator:    @Override
    public boolean needsInput()
    {
        return !finished && pagesSpatialIndexFuture.isDone() && !pageBuilder.isFull() && probe == null;
    }