@Override
      public void set(Boolean o, OperationStatus s) {
        super.set(o, s);
        notifyListeners();
      }
Flush all caches from all servers with a delay of application.

@param delay the period of time to delay, in seconds
@return whether or not the operation was accepted
@throws IllegalStateException in the rare circumstance where queue is too
          full to accept any more requests
src/main/java/net/spy/memcached/MemcachedClient.java