code: protected ByteBuffer getByteBuffer(int bufferLength) {
          if(_buffer == null) {
              _buffer = ByteBuffer.wrap(new byte[bufferLength]);
              _log.info("ByteBuffer allocated for buffering");
          }
          
          return _buffer;
      }
docs: Gets the buffer for speeding up compaction.
  
  @param bufferLength - the length of buffer.