presto-spi/src/main/java/io/prestosql/spi/block/AbstractVariableWidthBlock.java/AbstractVariableWidthBlock/hash
class AbstractVariableWidthBlock:    @Override
    public long hash(int position, int offset, int length)
    {
        checkReadablePosition(position);
        return XxHash64.hash(getRawSlice(position), getPositionOffset(position) + offset, length);
    }