presto-main/src/main/java/io/prestosql/operator/HashBuilderOperator.java/HashBuilderOperator/spillInput
class HashBuilderOperator:    private void spillInput(Page page)
    {
        checkState(spillInProgress.isDone(), "Previous spill still in progress");
        checkSuccess(spillInProgress, "spilling failed");
        spillInProgress = getSpiller().spill(page);
    }