presto-main/src/main/java/io/prestosql/operator/TableScanWorkProcessorOperator.java/TableScanWorkProcessorOperator/getPhysicalInputDataSize
class TableScanWorkProcessorOperator:        DataSize getPhysicalInputDataSize()
        {
            if (source == null) {
                return new DataSize(0, BYTE);
            }

            return new DataSize(source.getCompletedBytes(), BYTE);
        }