code: public synchronized void write(final boolean forceSync) throws IOException {
  		if (!validState) {
  			throw new InvalidStateException();
  		}
  		buf.clear();
  		buf.putLong(value);
  		buf.flip();
  		fc.position(fc.size()).write(buf); // go end and write
  		if (forceSync) {
  			fc.force(false);
  		}
  	}
docs: Write value to file
  
  @param forceSync if true data must be synced to disk
  @throws IOException