code: @Override
    public boolean addObserver(ConnectionObserver obs) {
      boolean rv = mconn.addObserver(obs);
      if (rv) {
        for (MemcachedNode node : mconn.getLocator().getAll()) {
          if (node.isActive()) {
            obs.connectionEstablished(node.getSocketAddress(), -1);
          }
        }
      }
      return rv;
    }
docs: Add a connection observer.
  
  If connections are already established, your observer will be called with
  the address and -1.
  
  @param obs the ConnectionObserver you wish to add
  @return true if the observer was added.