presto-orc/src/main/java/io/prestosql/orc/reader/SliceDictionaryColumnReader.java/SliceDictionaryColumnReader/readNonNullBlock
class SliceDictionaryColumnReader:    private Block readNonNullBlock()
            throws IOException
    {
        verifyNotNull(dataStream);
        int[] values = new int[nextBatchSize];
        dataStream.next(values, nextBatchSize);
        return new DictionaryBlock(nextBatchSize, dictionaryBlock, values);
    }