presto-thrift/src/main/java/io/prestosql/plugin/thrift/ThriftPageSource.java/ThriftPageSource/processBatch
class ThriftPageSource:    private Page processBatch(PrestoThriftPageResult rowsBatch)
    {
        firstCall = false;
        nextToken = rowsBatch.getNextToken();
        Page page = rowsBatch.toPage(columnTypes);
        if (page != null) {
            long pageSize = page.getSizeInBytes();
            completedBytes += pageSize;
            stats.addScanPageSize(pageSize);
        }
        else {
            stats.addScanPageSize(0);
        }
        return page;
    }