presto-main/src/main/java/io/prestosql/operator/NestedLoopBuildOperator.java/NestedLoopBuildOperator/addInput
class NestedLoopBuildOperator:    @Override
    public void addInput(Page page)
    {
        requireNonNull(page, "page is null");
        checkState(!isFinished(), "Operator is already finished");

        if (page.getPositionCount() == 0) {
            return;
        }

        nestedLoopJoinPagesBuilder.addPage(page);
        if (!localUserMemoryContext.trySetBytes(nestedLoopJoinPagesBuilder.getEstimatedSize().toBytes())) {
            nestedLoopJoinPagesBuilder.compact();
            localUserMemoryContext.setBytes(nestedLoopJoinPagesBuilder.getEstimatedSize().toBytes());
        }
        operatorContext.recordOutput(page.getSizeInBytes(), page.getPositionCount());
    }