class BlockPoolManager {

  void refreshNamenodes(Configuration conf)
      throws IOException {
    LOG.info("Refresh request received for nameservices: " + conf.get
            (DFSConfigKeys.DFS_NAMESERVICES));

    Map<String, Map<String, InetSocketAddress>> newAddressMap = DFSUtil
            .getNNServiceRpcAddressesForCluster(conf);

    synchronized (refreshNamenodesLock) {
      doRefreshNamenodes(newAddressMap);
    }
  }

    BlockPoolManager(DataNode dn);

}