/**
   * 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 for {@link FsDatasetImpl#updateReplicaUnderRecovery(ExtendedBlock, long, long)} */
  @Test
  public void testUpdateReplicaUnderRecovery() throws IOException {
    MiniDFSCluster cluster = null;

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

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

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

      // get DataNode and FSDataset objects
      final DataNode datanode = cluster.getDataNode(datanodeinfo[0].getIpcPort());
      Assert.assertTrue(datanode != null);

      // initReplicaRecovery
      final ExtendedBlock b = locatedblock.getBlock();
      final long recoveryid = b.getGenerationStamp() + 1;
      final long newlength = b.getNumBytes() - 1;
      final FsDatasetSpi<?> fsdataset = DataNodeTestUtils.getFSDataset(datanode);
      final ReplicaRecoveryInfo rri =
          fsdataset.initReplicaRecovery(new RecoveringBlock(b, null, recoveryid));

      // check replica
      final ReplicaInfo replica =
          FsDatasetTestUtil.fetchReplicaInfo(fsdataset, bpid, b.getBlockId());
      Assert.assertEquals(ReplicaState.RUR, replica.getState());

      // check meta data before update
      FsDatasetImpl.checkReplicaFiles(replica);

      // case "THIS IS NOT SUPPOSED TO HAPPEN"
      // with (block length) != (stored replica's on disk length).
      {
        // create a block with same id and gs but different length.
        final ExtendedBlock tmp =
            new ExtendedBlock(
                b.getBlockPoolId(),
                rri.getBlockId(),
                rri.getNumBytes() - 1,
                rri.getGenerationStamp());
        try {
          // update should fail
          fsdataset.updateReplicaUnderRecovery(tmp, recoveryid, newlength);
          Assert.fail();
        } catch (IOException ioe) {
          System.out.println("GOOD: getting " + ioe);
        }
      }

      // update
      final String storageID =
          fsdataset.updateReplicaUnderRecovery(
              new ExtendedBlock(b.getBlockPoolId(), rri), recoveryid, newlength);
      assertTrue(storageID != null);

    } finally {
      if (cluster != null) cluster.shutdown();
    }
  }