@Override
      public Operation newOp(final MemcachedNode n,
          final CountDownLatch latch) {
        Operation op = opFact.flush(delay, new OperationCallback() {
          @Override
          public void receivedStatus(OperationStatus s) {
            flushResult.set(s.isSuccess());
          }

          @Override
          public void complete() {
            latch.countDown();
          }
        });
        ops.add(op);
        return op;
      }
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