docs: public boolean truncate(long zxid) throws IOException {
          FileTxnIterator itr = new FileTxnIterator(this.logDir, zxid);
          PositionInputStream input = itr.inputStream;
          long pos = input.getPosition();
          // now, truncate at the current position
          RandomAccessFile raf=new RandomAccessFile(itr.logFile,"rw");
          raf.setLength(pos);
          raf.close();
          while(itr.goToNextLog()) {
              if (!itr.logFile.delete()) {
                  LOG.warn("Unable to truncate " + itr.logFile);
              }
          }
          return true;
      }