code: public static SeekableSource seekableSourceFrom(File file) throws IOException {
          requireNonNull(file);
          if (!"32".equals(System.getProperty("sun.arch.data.model"))
                  && !Boolean.getBoolean(DISABLE_MEMORY_MAPPED_PROPERTY)
                  && file.length() > Long.getLong(MAPPED_SIZE_THRESHOLD_PROPERTY, MB_16)) {
              return new BufferedSeekableSource(new MemoryMappedSeekableSource(file));
          }
          return new BufferedSeekableSource(new FileChannelSeekableSource(file));
      }
docs: Factory method to create a {@link SeekableSource} from a {@link File}. An attempt is made to return the best {@link SeekableSource} implementation based on the size of the
  file and bitness of the JVM.
  
  @param file
  @return a {@link SeekableSource} from the given file.
  @throws IOException