/**
   * The following test first creates a file. It verifies the block information from a datanode.
   * Then, it updates the block with new information and verifies again.
   */
  @Test
  public void testBlockMetaDataInfo() throws Exception {
    MiniDFSCluster cluster = null;

    try {
      cluster = new MiniDFSCluster.Builder(conf).numDataNodes(3).build();
      cluster.waitActive();

      // create a file
      DistributedFileSystem dfs = (DistributedFileSystem) cluster.getFileSystem();
      String filestr = "/foo";
      Path filepath = new Path(filestr);
      DFSTestUtil.createFile(dfs, filepath, 1024L, (short) 3, 0L);
      assertTrue(dfs.exists(filepath));

      // get block info
      LocatedBlock locatedblock =
          getLastLocatedBlock(DFSClientAdapter.getDFSClient(dfs).getNamenode(), filestr);
      DatanodeInfo[] datanodeinfo = locatedblock.getLocations();
      assertTrue(datanodeinfo.length > 0);

      // connect to a data node
      DataNode datanode = cluster.getDataNode(datanodeinfo[0].getIpcPort());
      InterDatanodeProtocol idp =
          DataNodeTestUtils.createInterDatanodeProtocolProxy(datanode, datanodeinfo[0], conf);

      // stop block scanner, so we could compare lastScanTime
      DataNodeTestUtils.shutdownBlockScanner(datanode);

      // verify BlockMetaDataInfo
      ExtendedBlock b = locatedblock.getBlock();
      InterDatanodeProtocol.LOG.info("b=" + b + ", " + b.getClass());
      checkMetaInfo(b, datanode);
      long recoveryId = b.getGenerationStamp() + 1;
      idp.initReplicaRecovery(new RecoveringBlock(b, locatedblock.getLocations(), recoveryId));

      // verify updateBlock
      ExtendedBlock newblock =
          new ExtendedBlock(
              b.getBlockPoolId(), b.getBlockId(), b.getNumBytes() / 2, b.getGenerationStamp() + 1);
      idp.updateReplicaUnderRecovery(b, recoveryId, newblock.getNumBytes());
      checkMetaInfo(newblock, datanode);

      // Verify correct null response trying to init recovery for a missing block
      ExtendedBlock badBlock = new ExtendedBlock("fake-pool", b.getBlockId(), 0, 0);
      assertNull(
          idp.initReplicaRecovery(
              new RecoveringBlock(badBlock, locatedblock.getLocations(), recoveryId)));
    } finally {
      if (cluster != null) {
        cluster.shutdown();
      }
    }
  }
  /**
   * Test to verify that InterDatanode RPC timesout as expected when the server DN does not respond.
   */
  @Test(expected = SocketTimeoutException.class)
  public void testInterDNProtocolTimeout() throws Throwable {
    final Server server = new TestServer(1, true);
    server.start();

    final InetSocketAddress addr = NetUtils.getConnectAddress(server);
    DatanodeID fakeDnId =
        new DatanodeID("localhost", "localhost", "fake-storage", addr.getPort(), 0, addr.getPort());
    DatanodeInfo dInfo = new DatanodeInfo(fakeDnId);
    InterDatanodeProtocol proxy = null;

    try {
      proxy = DataNode.createInterDataNodeProtocolProxy(dInfo, conf, 500);
      proxy.initReplicaRecovery(new RecoveringBlock(new ExtendedBlock("bpid", 1), null, 100));
      fail("Expected SocketTimeoutException exception, but did not get.");
    } finally {
      if (proxy != null) {
        RPC.stopProxy(proxy);
      }
      server.stop();
    }
  }