private CountDownLatch broadcastOp(BroadcastOpFactory of,
      Collection<MemcachedNode> nodes, boolean checkShuttingDown) {
    if (checkShuttingDown && shuttingDown) {
      throw new IllegalStateException("Shutting down");
    }
    return conn.broadcastOperation(of, nodes);
  }
Wait for the queues to die down.

@param timeout the amount of time time for shutdown
@param unit the TimeUnit for the timeout
@return result of the request for the wait
@throws IllegalStateException in the rare circumstance where queue is too
          full to accept any more requests
src/main/java/net/spy/memcached/TapConnectionProvider.java