code: public SegmentIndexBuffer loadSegmentIndexBuffer(int segId) {
          File sibFile = getSegmentIndexBufferFile(segId);
          if(sibFile.exists()) {
              SegmentIndexBuffer sib = new SegmentIndexBuffer();
              try {
                  _sibManager.getSegmentIndexBufferIO().read(sib, sibFile);
                  return sib;
              } catch (Exception e) {
                  _log.warn(sibFile.getAbsolutePath() + " corrupted");
                  sibFile.delete();
              }
          }
          
          return null;
      }
docs: Loads the {@link SegmentIndexBuffer} file at the specified <code>segId</code>.
  
  @return the {@link SegmentIndexBuffer} loaded successfully or <code>null</code> if the loading failed.