/**
 * This method retrieve all the datanodes of a hdfs cluster
 */
private List<String> getDataNodes() throws IOException {

  Configuration conf = new Configuration(false);
  conf.addResource(new org.apache.hadoop.fs.Path(HdfsDataContext.getHdfsConfigDirectory(config)));

  List<String> datanodesList = new ArrayList<>();
  InetSocketAddress namenodeAddress = new InetSocketAddress(
      HdfsDataContext.getHdfsNamenodeDefault(config),
      HdfsDataContext.getHdfsNamenodePortDefault(config));
  DFSClient dfsClient = new DFSClient(namenodeAddress, conf);
  ClientProtocol nameNode = dfsClient.getNamenode();
  DatanodeInfo[] datanodeReport =
      nameNode.getDatanodeReport(HdfsConstants.DatanodeReportType.ALL);
  for (DatanodeInfo di : datanodeReport) {
    datanodesList.add(di.getHostName());
  }
  return datanodesList;
}
 

private static ClientProtocol getNNProxy(
    Token<DelegationTokenIdentifier> token, Configuration conf)
    throws IOException {
  URI uri = HAUtil.getServiceUriFromToken(HdfsConstants.HDFS_URI_SCHEME,
          token);
  if (HAUtil.isTokenForLogicalUri(token) &&
      !HAUtil.isLogicalUri(conf, uri)) {
    // If the token is for a logical nameservice, but the configuration
    // we have disagrees about that, we can't actually renew it.
    // This can be the case in MR, for example, if the RM doesn't
    // have all of the HA clusters configured in its configuration.
    throw new IOException("Unable to map logical nameservice URI '" +
        uri + "' to a NameNode. Local configuration does not have " +
        "a failover proxy provider configured.");
  }
  
  NameNodeProxies.ProxyAndInfo<ClientProtocol> info =
    NameNodeProxies.createProxy(conf, uri, ClientProtocol.class);
  assert info.getDelegationTokenService().equals(token.getService()) :
    "Returned service '" + info.getDelegationTokenService().toString() +
    "' doesn't match expected service '" +
    token.getService().toString() + "'";
    
  return info.getProxy();
}
 

public void testSinglePortStartup() throws IOException {
  Configuration conf = new Configuration();
  MiniDFSCluster cluster = new MiniDFSCluster(conf, 2, true, null);
  NameNode nn = cluster.getNameNode();
  InetSocketAddress dnAddress = nn.getNameNodeDNAddress();
  InetSocketAddress clientAddress = nn.getNameNodeAddress();

  assertEquals(clientAddress, dnAddress);

  DatanodeProtocol dnProtocol = (DatanodeProtocol) RPC.waitForProxy(
      DatanodeProtocol.class, DatanodeProtocol.versionID, dnAddress, conf);
  // perform a dummy call
  dnProtocol.getProtocolVersion(DatanodeProtocol.class.getName(),
      DatanodeProtocol.versionID);
  ClientProtocol client = (ClientProtocol) RPC.waitForProxy(
      ClientProtocol.class, ClientProtocol.versionID, dnAddress, conf);
  client.getProtocolVersion(ClientProtocol.class.getName(),
      ClientProtocol.versionID);

  cluster.shutdown();
}
 

/**
 * Create a {@link NameNode} proxy from the current {@link ServletContext}. 
 */
protected ClientProtocol createNameNodeProxy() throws IOException {
  ServletContext context = getServletContext();
  // if we are running in the Name Node, use it directly rather than via 
  // rpc
  NameNode nn = NameNodeHttpServer.getNameNodeFromContext(context);
  if (nn != null) {
    return nn.getRpcServer();
  }
  InetSocketAddress nnAddr =
    NameNodeHttpServer.getNameNodeAddressFromContext(context);
  Configuration conf = new HdfsConfiguration(
      NameNodeHttpServer.getConfFromContext(context));
  return NameNodeProxies.createProxy(conf, NameNode.getUri(nnAddr),
      ClientProtocol.class).getProxy();
}
 

/**
 * Dumps DFS data structures into specified file.
 * Usage: hdfs dfsadmin -metasave filename
 * @param argv List of of command line parameters.
 * @param idx The index of the command that is being processed.
 * @exception IOException if an error occurred while accessing
 *            the file or path.
 */
public int metaSave(String[] argv, int idx) throws IOException {
  String pathname = argv[idx];
  DistributedFileSystem dfs = getDFS();
  Configuration dfsConf = dfs.getConf();
  URI dfsUri = dfs.getUri();
  boolean isHaEnabled = HAUtil.isLogicalUri(dfsConf, dfsUri);

  if (isHaEnabled) {
    String nsId = dfsUri.getHost();
    List<ProxyAndInfo<ClientProtocol>> proxies =
        HAUtil.getProxiesForAllNameNodesInNameservice(dfsConf,
        nsId, ClientProtocol.class);
    for (ProxyAndInfo<ClientProtocol> proxy : proxies) {
      proxy.getProxy().metaSave(pathname);
      System.out.println("Created metasave file " + pathname + " in the log "
          + "directory of namenode " + proxy.getAddress());
    }
  } else {
    dfs.metaSave(pathname);
    System.out.println("Created metasave file " + pathname + " in the log " +
        "directory of namenode " + dfs.getUri());
  }
  return 0;
}
 

private DFSClient genClientWithDummyHandler() throws IOException {
  URI nnUri = dfs.getUri();
  FailoverProxyProvider<ClientProtocol> failoverProxyProvider = 
      NameNodeProxies.createFailoverProxyProvider(conf, 
          nnUri, ClientProtocol.class, true, null);
  InvocationHandler dummyHandler = new DummyRetryInvocationHandler(
      failoverProxyProvider, RetryPolicies
      .failoverOnNetworkException(RetryPolicies.TRY_ONCE_THEN_FAIL,
          Integer.MAX_VALUE,
          DFSConfigKeys.DFS_CLIENT_FAILOVER_SLEEPTIME_BASE_DEFAULT,
          DFSConfigKeys.DFS_CLIENT_FAILOVER_SLEEPTIME_MAX_DEFAULT));
  ClientProtocol proxy = (ClientProtocol) Proxy.newProxyInstance(
      failoverProxyProvider.getInterface().getClassLoader(),
      new Class[] { ClientProtocol.class }, dummyHandler);
  
  DFSClient client = new DFSClient(null, proxy, conf, null);
  return client;
}
 

FanOutOneBlockAsyncDFSOutput(Configuration conf,DistributedFileSystem dfs,
    DFSClient client, ClientProtocol namenode, String clientName, String src, long fileId,
    LocatedBlock locatedBlock, Encryptor encryptor, List<Channel> datanodeList,
    DataChecksum summer, ByteBufAllocator alloc) {
  this.conf = conf;
  this.dfs = dfs;
  this.client = client;
  this.namenode = namenode;
  this.fileId = fileId;
  this.clientName = clientName;
  this.src = src;
  this.block = locatedBlock.getBlock();
  this.locations = locatedBlock.getLocations();
  this.encryptor = encryptor;
  this.datanodeList = datanodeList;
  this.summer = summer;
  this.maxDataLen = MAX_DATA_LEN - (MAX_DATA_LEN % summer.getBytesPerChecksum());
  this.alloc = alloc;
  this.buf = alloc.directBuffer(sendBufSizePRedictor.initialSize());
  this.state = State.STREAMING;
  setupReceiver(conf.getInt(DFS_CLIENT_SOCKET_TIMEOUT_KEY, READ_TIMEOUT));
}
 

@SuppressWarnings("unchecked")
private static void mockCreate(ClientProtocol mcp,
    CipherSuite suite, CryptoProtocolVersion version) throws Exception {
  Mockito.doReturn(
      new HdfsFileStatus(0, false, 1, 1024, 0, 0, new FsPermission(
          (short) 777), "owner", "group", new byte[0], new byte[0],
          1010, 0, new FileEncryptionInfo(suite,
          version, new byte[suite.getAlgorithmBlockSize()],
          new byte[suite.getAlgorithmBlockSize()],
          "fakeKey", "fakeVersion"),
          (byte) 0))
      .when(mcp)
      .create(anyString(), (FsPermission) anyObject(), anyString(),
          (EnumSetWritable<CreateFlag>) anyObject(), anyBoolean(),
          anyShort(), anyLong(), (CryptoProtocolVersion[]) anyObject());
}
 

private FileStatus[] versionBasedListPath(String src) throws IOException {
  if (namenodeVersion >= ClientProtocol.ITERATIVE_LISTING_VERSION) {
    return iterativeListing(src);
  } else if (namenodeVersion >= ClientProtocol.OPTIMIZE_FILE_STATUS_VERSION) {
    HdfsFileStatus[] hdfsStats = namenode.getHdfsListing(src);
    if (hdfsStats == null) {
      return null;
    }
    FileStatus[] stats = new FileStatus[hdfsStats.length];
    for (int i=0; i<stats.length; i++) {
      stats[i] = toFileStatus(hdfsStats[i], src);
    }
    return stats;
  } else {
    return namenode.getListing(src);
  }
}
 

/** {@inheritDoc} */
public void doGet(HttpServletRequest request, HttpServletResponse response
    ) throws ServletException, IOException {
  final UnixUserGroupInformation ugi = getUGI(request);
  final PrintWriter out = response.getWriter();
  final String filename = getFilename(request, response);
  final XMLOutputter xml = new XMLOutputter(out, "UTF-8");
  xml.declaration();

  final Configuration conf = new Configuration(DataNode.getDataNode().getConf());
  final int socketTimeout = conf.getInt("dfs.socket.timeout", HdfsConstants.READ_TIMEOUT);
  final SocketFactory socketFactory = NetUtils.getSocketFactory(conf, ClientProtocol.class);
  UnixUserGroupInformation.saveToConf(conf,
      UnixUserGroupInformation.UGI_PROPERTY_NAME, ugi);
  final ClientProtocol nnproxy = DFSClient.createNamenode(conf);

  try {
    final MD5MD5CRC32FileChecksum checksum = DFSClient.getFileChecksum(
        filename, nnproxy, socketFactory, socketTimeout);
    MD5MD5CRC32FileChecksum.write(xml, checksum);
  } catch(IOException ioe) {
    new RemoteException(ioe.getClass().getName(), ioe.getMessage()
        ).writeXml(filename, xml);
  }
  xml.endDocument();
}
 

private DFSClient genClientWithDummyHandler() throws IOException {
  URI nnUri = dfs.getUri();
  FailoverProxyProvider<ClientProtocol> failoverProxyProvider = 
      NameNodeProxies.createFailoverProxyProvider(conf, 
          nnUri, ClientProtocol.class, true, null);
  InvocationHandler dummyHandler = new DummyRetryInvocationHandler(
      failoverProxyProvider, RetryPolicies
      .failoverOnNetworkException(RetryPolicies.TRY_ONCE_THEN_FAIL,
          Integer.MAX_VALUE,
          DFSConfigKeys.DFS_CLIENT_FAILOVER_SLEEPTIME_BASE_DEFAULT,
          DFSConfigKeys.DFS_CLIENT_FAILOVER_SLEEPTIME_MAX_DEFAULT));
  ClientProtocol proxy = (ClientProtocol) Proxy.newProxyInstance(
      failoverProxyProvider.getInterface().getClassLoader(),
      new Class[] { ClientProtocol.class }, dummyHandler);
  
  DFSClient client = new DFSClient(null, proxy, conf, null);
  return client;
}
 

/** Select a datanode to service this request, which is the first one
 * in the returned array. The rest of the elements in the datanode
 * are possible candidates if the first one fails.
 * Currently, this looks at no more than the first five blocks of a file,
 * selecting a datanode randomly from the most represented.
 */
private static DatanodeInfo[] pickSrcDatanode(FileStatus i,
    ClientProtocol nnproxy) throws IOException {
  // a race condition can happen by initializing a static member this way.
  // A proper fix should make JspHelper a singleton. Since it doesn't affect 
  // correctness, we leave it as is for now.
  if (jspHelper == null)
    jspHelper = new JspHelper();
  final LocatedBlocks blks = nnproxy.getBlockLocations(
      i.getPath().toUri().getPath(), 0, 1);
  if (i.getLen() == 0 || blks.getLocatedBlocks().size() <= 0) {
    // pick a random datanode
    return new DatanodeInfo[] { jspHelper.randomNode() };
  }
  return jspHelper.bestNode(blks);
}
 

/**
 * Create a NameNode proxy for the client if the client and NameNode
 * are compatible
 *
 * @param nameNodeAddr NameNode address
 * @param conf configuration
 * @param ugi ticket
 * @return a NameNode proxy that's compatible with the client
 */
private void createRPCNamenodeIfCompatible(
    InetSocketAddress nameNodeAddr,
    Configuration conf,
    UnixUserGroupInformation ugi) throws IOException {
  try {
    this.namenodeProtocolProxy = createRPCNamenode(nameNodeAddr, conf, ugi);
    this.rpcNamenode = namenodeProtocolProxy.getProxy();
  } catch (RPC.VersionMismatch e) {
    long clientVersion = e.getClientVersion();
    namenodeVersion = e.getServerVersion();
    if (clientVersion > namenodeVersion &&
        !ProtocolCompatible.isCompatibleClientProtocol(
            clientVersion, namenodeVersion)) {
      throw new RPC.VersionIncompatible(
          ClientProtocol.class.getName(), clientVersion, namenodeVersion);
    }
    this.rpcNamenode = (ClientProtocol)e.getProxy();
  }
}
 

public long getProtocolVersion(String protocol, 
                               long clientVersion) throws IOException {
  if (protocol.equals(ClientProtocol.class.getName())) {
    return ClientProtocol.versionID; 
  } else if (protocol.equals(DatanodeProtocol.class.getName())){
    return DatanodeProtocol.versionID;
  } else if (protocol.equals(NamenodeProtocol.class.getName())){
    return NamenodeProtocol.versionID;
  } else if (protocol.equals(RefreshAuthorizationPolicyProtocol.class.getName())){
    return RefreshAuthorizationPolicyProtocol.versionID;
  } else if (protocol.equals(RefreshUserMappingsProtocol.class.getName())){
    return RefreshUserMappingsProtocol.versionID;
  } else if (protocol.equals(RefreshCallQueueProtocol.class.getName())) {
    return RefreshCallQueueProtocol.versionID;
  } else if (protocol.equals(GetUserMappingsProtocol.class.getName())){
    return GetUserMappingsProtocol.versionID;
  } else if (protocol.equals(TraceAdminProtocol.class.getName())){
    return TraceAdminProtocol.versionID;
  } else {
    throw new IOException("Unknown protocol to name node: " + protocol);
  }
}
 

/**
 * Creates an explicitly non-HA-enabled proxy object. Most of the time you
 * don't want to use this, and should instead use {@link NameNodeProxies#createProxy}.
 *
 * @param conf the configuration object
 * @param nnAddr address of the remote NN to connect to
 * @param xface the IPC interface which should be created
 * @param ugi the user who is making the calls on the proxy object
 * @param withRetries certain interfaces have a non-standard retry policy
 * @param fallbackToSimpleAuth - set to true or false during this method to
 *   indicate if a secure client falls back to simple auth
 * @return an object containing both the proxy and the associated
 *         delegation token service it corresponds to
 * @throws IOException
 */
@SuppressWarnings("unchecked")
public static <T> ProxyAndInfo<T> createNonHAProxy(
    Configuration conf, InetSocketAddress nnAddr, Class<T> xface,
    UserGroupInformation ugi, boolean withRetries,
    AtomicBoolean fallbackToSimpleAuth) throws IOException {
  Text dtService = SecurityUtil.buildTokenService(nnAddr);

  T proxy;
  if (xface == ClientProtocol.class) {
    proxy = (T) createNNProxyWithClientProtocol(nnAddr, conf, ugi,
        withRetries, fallbackToSimpleAuth);
  } else if (xface == JournalProtocol.class) {
    proxy = (T) createNNProxyWithJournalProtocol(nnAddr, conf, ugi);
  } else if (xface == NamenodeProtocol.class) {
    proxy = (T) createNNProxyWithNamenodeProtocol(nnAddr, conf, ugi,
        withRetries);
  } else if (xface == GetUserMappingsProtocol.class) {
    proxy = (T) createNNProxyWithGetUserMappingsProtocol(nnAddr, conf, ugi);
  } else if (xface == RefreshUserMappingsProtocol.class) {
    proxy = (T) createNNProxyWithRefreshUserMappingsProtocol(nnAddr, conf, ugi);
  } else if (xface == RefreshAuthorizationPolicyProtocol.class) {
    proxy = (T) createNNProxyWithRefreshAuthorizationPolicyProtocol(nnAddr,
        conf, ugi);
  } else if (xface == RefreshCallQueueProtocol.class) {
    proxy = (T) createNNProxyWithRefreshCallQueueProtocol(nnAddr, conf, ugi);
  } else {
    String message = "Unsupported protocol found when creating the proxy " +
        "connection to NameNode: " +
        ((xface != null) ? xface.getClass().getName() : "null");
    LOG.error(message);
    throw new IllegalStateException(message);
  }

  return new ProxyAndInfo<T>(proxy, dtService, nnAddr);
}
 

@SuppressWarnings("unchecked")
@Override
public long renew(Token<?> token, Configuration conf) throws IOException {
  Token<DelegationTokenIdentifier> delToken = 
    (Token<DelegationTokenIdentifier>) token;
  ClientProtocol nn = getNNProxy(delToken, conf);
  try {
    return nn.renewDelegationToken(delToken);
  } catch (RemoteException re) {
    throw re.unwrapRemoteException(InvalidToken.class, 
                                   AccessControlException.class);
  }
}
 

@SuppressWarnings("unchecked")
@Override
public void cancel(Token<?> token, Configuration conf) throws IOException {
  Token<DelegationTokenIdentifier> delToken = 
      (Token<DelegationTokenIdentifier>) token;
  LOG.info("Cancelling " + 
           DelegationTokenIdentifier.stringifyToken(delToken));
  ClientProtocol nn = getNNProxy(delToken, conf);
  try {
    nn.cancelDelegationToken(delToken);
  } catch (RemoteException re) {
    throw re.unwrapRemoteException(InvalidToken.class,
        AccessControlException.class);
  }
}
 

/**
 * @see ClientProtocol#getBlockLocations(String, long, long)
 */
static LocatedBlocks callGetBlockLocations(ClientProtocol namenode,
    String src, long start, long length) 
    throws IOException {
  try {
    return namenode.getBlockLocations(src, start, length);
  } catch(RemoteException re) {
    throw re.unwrapRemoteException(AccessControlException.class,
                                   FileNotFoundException.class,
                                   UnresolvedPathException.class);
  }
}
 

private static FileCreator createFileCreator3() throws NoSuchMethodException {
  Method createMethod = ClientProtocol.class.getMethod("create", String.class, FsPermission.class,
    String.class, EnumSetWritable.class, boolean.class, short.class, long.class,
    CryptoProtocolVersion[].class, String.class);

  return (instance, src, masked, clientName, flag, createParent, replication, blockSize,
      supportedVersions) -> {
    return (HdfsFileStatus) createMethod.invoke(instance, src, masked, clientName, flag,
      createParent, replication, blockSize, supportedVersions, null);
  };
}
 

/**
 * Test addBlock() name-node RPC is idempotent
 */
public void testIdepotentCallsAddBlock() throws IOException {
  ClientProtocol nn = cluster.getNameNode();
  FileSystem fs = cluster.getFileSystem();
  DFSClient dfsclient = ((DistributedFileSystem) fs).dfs;

  String src = "/testNameNodeFingerprintSent1.txt";
  // Path f = new Path(src);

  DFSOutputStream dos = (DFSOutputStream) dfsclient.create(src, true,
      (short) 1, 512L);

  FSDataOutputStream a_out = new FSDataOutputStream(dos); // fs.create(f);

  for (int i = 0; i < 512; i++) {
    a_out.writeBytes("bc");
  }
  a_out.flush();

  LocatedBlocks lb = nn.getBlockLocations(src, 256, 257);
  LocatedBlock lb1 = nn.addBlockAndFetchMetaInfo(src, dfsclient.clientName,
      null, null, 512L, lb.getLocatedBlocks().get(lb.locatedBlockCount() - 1)
          .getBlock());
  LocatedBlock lb2 = nn.addBlockAndFetchMetaInfo(src, dfsclient.clientName,
      null, null, 512L, lb.getLocatedBlocks().get(lb.locatedBlockCount() - 1)
          .getBlock());
  TestCase.assertTrue("blocks: " + lb1.getBlock() + " and " + lb2.getBlock(),
      lb1.getBlock().equals(lb2.getBlock()));
}
 

DFSInotifyEventInputStream(Sampler traceSampler, ClientProtocol namenode,
      long lastReadTxid) throws IOException {
  this.traceSampler = traceSampler;
  this.namenode = namenode;
  this.it = Iterators.emptyIterator();
  this.lastReadTxid = lastReadTxid;
}
 

public static ProtocolProxy<ClientProtocol> createRPCNamenode(
    Configuration conf) throws IOException {
  try {
    return createRPCNamenode(NameNode.getAddress(conf), conf,
        UnixUserGroupInformation.login(conf, true));
  } catch (LoginException e) {
    throw new IOException(e);
  }   
}
 

public static LocatedBlock getLastLocatedBlock(
    ClientProtocol namenode, String src
) throws IOException {
  //get block info for the last block
  LocatedBlocks locations = namenode.getBlockLocations(src, 0, Long.MAX_VALUE);
  List<LocatedBlock> blocks = locations.getLocatedBlocks();
  DataNode.LOG.info("blocks.size()=" + blocks.size());
  assertTrue(blocks.size() > 0);

  return blocks.get(blocks.size() - 1);
}
 

/** Create a redirection URL */
private URL createRedirectURL(String path, String encodedPath, HdfsFileStatus status, 
    UserGroupInformation ugi, ClientProtocol nnproxy, HttpServletRequest request, String dt)
    throws IOException {
  String scheme = request.getScheme();
  final LocatedBlocks blks = nnproxy.getBlockLocations(
      status.getFullPath(new Path(path)).toUri().getPath(), 0, 1);
  final Configuration conf = NameNodeHttpServer.getConfFromContext(
      getServletContext());
  final DatanodeID host = pickSrcDatanode(blks, status, conf);
  final String hostname;
  if (host instanceof DatanodeInfo) {
    hostname = host.getHostName();
  } else {
    hostname = host.getIpAddr();
  }

  int port = "https".equals(scheme) ? host.getInfoSecurePort() : host
      .getInfoPort();

  String dtParam = "";
  if (dt != null) {
    dtParam = JspHelper.getDelegationTokenUrlParam(dt);
  }

  // Add namenode address to the url params
  NameNode nn = NameNodeHttpServer.getNameNodeFromContext(
      getServletContext());
  String addr = nn.getNameNodeAddressHostPortString();
  String addrParam = JspHelper.getUrlParam(JspHelper.NAMENODE_ADDRESS, addr);
  
  return new URL(scheme, hostname, port,
      "/streamFile" + encodedPath + '?' +
      "ugi=" + ServletUtil.encodeQueryValue(ugi.getShortUserName()) +
      dtParam + addrParam);
}
 

/** {@inheritDoc} */
@Override
protected URI createUri(FileStatus i, UnixUserGroupInformation ugi,
    ClientProtocol nnproxy, HttpServletRequest request) throws IOException,
    URISyntaxException {
  return new URI(request.getScheme(), null, request.getServerName(), request
      .getServerPort(), "/streamFile", "filename=" + i.getPath() + "&ugi="
      + ugi, null);
}
 

public static LocatedBlock getLastLocatedBlock(
    ClientProtocol namenode, String src) throws IOException {
  //get block info for the last block
  LocatedBlocks locations = namenode.getBlockLocations(src, 0, Long.MAX_VALUE);
  List<LocatedBlock> blocks = locations.getLocatedBlocks();
  DataNode.LOG.info("blocks.size()=" + blocks.size());
  assertTrue(blocks.size() > 0);

  return blocks.get(blocks.size() - 1);
}
 

/**
 * Get an RPC proxy for each NN in an HA nameservice. Used when a given RPC
 * call should be made on every NN in an HA nameservice, not just the active.
 * 
 * @param conf configuration
 * @param nsId the nameservice to get all of the proxies for.
 * @return a list of RPC proxies for each NN in the nameservice.
 * @throws IOException in the event of error.
 */
public static List<ClientProtocol> getProxiesForAllNameNodesInNameservice(
    Configuration conf, String nsId) throws IOException {
  List<ProxyAndInfo<ClientProtocol>> proxies =
      getProxiesForAllNameNodesInNameservice(conf, nsId, ClientProtocol.class);

  List<ClientProtocol> namenodes = new ArrayList<ClientProtocol>(
      proxies.size());
  for (ProxyAndInfo<ClientProtocol> proxy : proxies) {
    namenodes.add(proxy.getProxy());
  }
  return namenodes;
}
 

private void doTestConnection(URI host, Configuration hadoopConfiguration) throws IOException {
	SocketFactory socketFactory = NetUtils.getSocketFactory(hadoopConfiguration, ClientProtocol.class);
	Socket socket = socketFactory.createSocket();
       socket.setTcpNoDelay(false);
       SocketAddress address = new InetSocketAddress(host.getHost(), host.getPort());
       try {
       	NetUtils.connect(socket, address, CONNECTION_TEST_TIMEOUT);
	} finally {
		try {
			socket.close();
		} catch (IOException e) {}
	}
}
 

/**
 * Command to ask the namenode to reread the hosts and excluded hosts 
 * file.
 * Usage: hdfs dfsadmin -refreshNodes
 * @exception IOException 
 */
public int refreshNodes() throws IOException {
  int exitCode = -1;

  DistributedFileSystem dfs = getDFS();
  Configuration dfsConf = dfs.getConf();
  URI dfsUri = dfs.getUri();
  boolean isHaEnabled = HAUtil.isLogicalUri(dfsConf, dfsUri);

  if (isHaEnabled) {
    String nsId = dfsUri.getHost();
    List<ProxyAndInfo<ClientProtocol>> proxies =
        HAUtil.getProxiesForAllNameNodesInNameservice(dfsConf,
        nsId, ClientProtocol.class);
    for (ProxyAndInfo<ClientProtocol> proxy: proxies) {
      proxy.getProxy().refreshNodes();
      System.out.println("Refresh nodes successful for " +
          proxy.getAddress());
    }
  } else {
    dfs.refreshNodes();
    System.out.println("Refresh nodes successful");
  }
  exitCode = 0;
 
  return exitCode;
}
 

/**
 * Command to ask the namenode to finalize previously performed upgrade.
 * Usage: hdfs dfsadmin -finalizeUpgrade
 * @exception IOException 
 */
public int finalizeUpgrade() throws IOException {
  DistributedFileSystem dfs = getDFS();
  
  Configuration dfsConf = dfs.getConf();
  URI dfsUri = dfs.getUri();
  boolean isHaAndLogicalUri = HAUtil.isLogicalUri(dfsConf, dfsUri);
  if (isHaAndLogicalUri) {
    // In the case of HA and logical URI, run finalizeUpgrade for all
    // NNs in this nameservice.
    String nsId = dfsUri.getHost();
    List<ClientProtocol> namenodes =
        HAUtil.getProxiesForAllNameNodesInNameservice(dfsConf, nsId);
    if (!HAUtil.isAtLeastOneActive(namenodes)) {
      throw new IOException("Cannot finalize with no NameNode active");
    }

    List<ProxyAndInfo<ClientProtocol>> proxies =
        HAUtil.getProxiesForAllNameNodesInNameservice(dfsConf,
        nsId, ClientProtocol.class);
    for (ProxyAndInfo<ClientProtocol> proxy : proxies) {
      proxy.getProxy().finalizeUpgrade();
      System.out.println("Finalize upgrade successful for " +
          proxy.getAddress());
    }
  } else {
    dfs.finalizeUpgrade();
    System.out.println("Finalize upgrade successful");
  }
  
  return 0;
}