/**
   * TC7: Corrupted replicas are present.
   *
   * @throws IOException an exception might be thrown
   */
  public void testTC7() throws Exception {
    final short repl = 2;
    final Path p = new Path("/TC7/foo");
    System.out.println("p=" + p);

    // a. Create file with replication factor of 2. Write half block of data. Close file.
    final int len1 = (int) (BLOCK_SIZE / 2);
    {
      FSDataOutputStream out = fs.create(p, false, buffersize, repl, BLOCK_SIZE);
      AppendTestUtil.write(out, 0, len1);
      out.close();
    }
    DFSTestUtil.waitReplication(fs, p, repl);

    // b. Log into one datanode that has one replica of this block.
    //   Find the block file on this datanode and truncate it to zero size.
    final LocatedBlocks locatedblocks =
        fs.dfs.getNamenode().getBlockLocations(p.toString(), 0L, len1);
    assertEquals(1, locatedblocks.locatedBlockCount());
    final LocatedBlock lb = locatedblocks.get(0);
    final Block blk = lb.getBlock();
    assertEquals(len1, lb.getBlockSize());

    DatanodeInfo[] datanodeinfos = lb.getLocations();
    assertEquals(repl, datanodeinfos.length);
    final DataNode dn = cluster.getDataNode(datanodeinfos[0].getIpcPort());
    final FSDataset data = (FSDataset) dn.getFSDataset();
    final RandomAccessFile raf = new RandomAccessFile(data.getBlockFile(blk), "rw");
    AppendTestUtil.LOG.info("dn=" + dn + ", blk=" + blk + " (length=" + blk.getNumBytes() + ")");
    assertEquals(len1, raf.length());
    raf.setLength(0);
    raf.close();

    // c. Open file in "append mode".  Append a new block worth of data. Close file.
    final int len2 = (int) BLOCK_SIZE;
    {
      FSDataOutputStream out = fs.append(p);
      AppendTestUtil.write(out, len1, len2);
      out.close();
    }

    // d. Reopen file and read two blocks worth of data.
    AppendTestUtil.check(fs, p, len1 + len2);
  }
  /**
   * Create a file, write something, fsync but not close. Then change lease period and wait for
   * lease recovery. Finally, read the block directly from each Datanode and verify the content.
   */
  public void testLeaseExpireHardLimit() throws Exception {
    System.out.println("testLeaseExpireHardLimit start");
    final long leasePeriod = 1000;
    final int DATANODE_NUM = 3;

    Configuration conf = new Configuration();
    conf.setInt("heartbeat.recheck.interval", 1000);
    conf.setInt("dfs.heartbeat.interval", 1);

    // create cluster
    MiniDFSCluster cluster = new MiniDFSCluster(conf, DATANODE_NUM, true, null);
    DistributedFileSystem dfs = null;
    try {
      cluster.waitActive();
      dfs = (DistributedFileSystem) cluster.getFileSystem();

      // create a new file.
      final String f = DIR + "foo";
      final Path fpath = new Path(f);
      FSDataOutputStream out = TestFileCreation.createFile(dfs, fpath, DATANODE_NUM);
      out.write("something".getBytes());
      out.sync();
      int actualRepl =
          ((DFSClient.DFSOutputStream) (out.getWrappedStream())).getNumCurrentReplicas();
      assertTrue(
          f + " should be replicated to " + DATANODE_NUM + " datanodes.",
          actualRepl == DATANODE_NUM);

      // set the soft and hard limit to be 1 second so that the
      // namenode triggers lease recovery
      cluster.setLeasePeriod(leasePeriod, leasePeriod);
      // wait for the lease to expire
      try {
        Thread.sleep(5 * leasePeriod);
      } catch (InterruptedException e) {
      }

      LocatedBlocks locations = dfs.dfs.namenode.getBlockLocations(f, 0, Long.MAX_VALUE);
      assertEquals(1, locations.locatedBlockCount());
      LocatedBlock locatedblock = locations.getLocatedBlocks().get(0);
      int successcount = 0;
      for (DatanodeInfo datanodeinfo : locatedblock.getLocations()) {
        DataNode datanode = cluster.getDataNode(datanodeinfo.ipcPort);
        FSDataset dataset = (FSDataset) datanode.data;
        Block b = dataset.getStoredBlock(locatedblock.getBlock().getBlockId());
        File blockfile = dataset.findBlockFile(b.getBlockId());
        System.out.println("blockfile=" + blockfile);
        if (blockfile != null) {
          BufferedReader in = new BufferedReader(new FileReader(blockfile));
          assertEquals("something", in.readLine());
          in.close();
          successcount++;
        }
      }
      System.out.println("successcount=" + successcount);
      assertTrue(successcount > 0);
    } finally {
      IOUtils.closeStream(dfs);
      cluster.shutdown();
    }

    System.out.println("testLeaseExpireHardLimit successful");
  }
  /**
   * Test that copy on write for blocks works correctly
   *
   * @throws IOException an exception might be thrown
   */
  @Test
  public void testCopyOnWrite() throws IOException {
    Configuration conf = new HdfsConfiguration();
    if (simulatedStorage) {
      conf.setBoolean(SimulatedFSDataset.CONFIG_PROPERTY_SIMULATED, true);
    }
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).build();
    FileSystem fs = cluster.getFileSystem();
    InetSocketAddress addr = new InetSocketAddress("localhost", cluster.getNameNodePort());
    DFSClient client = new DFSClient(addr, conf);
    try {

      // create a new file, write to it and close it.
      //
      Path file1 = new Path("/filestatus.dat");
      FSDataOutputStream stm = AppendTestUtil.createFile(fs, file1, 1);
      writeFile(stm);
      stm.close();

      // Get a handle to the datanode
      DataNode[] dn = cluster.listDataNodes();
      assertTrue("There should be only one datanode but found " + dn.length, dn.length == 1);

      LocatedBlocks locations =
          client.getNamenode().getBlockLocations(file1.toString(), 0, Long.MAX_VALUE);
      List<LocatedBlock> blocks = locations.getLocatedBlocks();
      FSDataset dataset = (FSDataset) dn[0].data;

      //
      // Create hard links for a few of the blocks
      //
      for (int i = 0; i < blocks.size(); i = i + 2) {
        ExtendedBlock b = blocks.get(i).getBlock();
        File f = dataset.getFile(b.getBlockPoolId(), b.getLocalBlock());
        File link = new File(f.toString() + ".link");
        System.out.println("Creating hardlink for File " + f + " to " + link);
        HardLink.createHardLink(f, link);
      }

      //
      // Detach all blocks. This should remove hardlinks (if any)
      //
      for (int i = 0; i < blocks.size(); i++) {
        ExtendedBlock b = blocks.get(i).getBlock();
        System.out.println("testCopyOnWrite detaching block " + b);
        assertTrue(
            "Detaching block " + b + " should have returned true", dataset.unlinkBlock(b, 1));
      }

      // Since the blocks were already detached earlier, these calls should
      // return false
      //
      for (int i = 0; i < blocks.size(); i++) {
        ExtendedBlock b = blocks.get(i).getBlock();
        System.out.println("testCopyOnWrite detaching block " + b);
        assertTrue(
            "Detaching block " + b + " should have returned false", !dataset.unlinkBlock(b, 1));
      }

    } finally {
      fs.close();
      cluster.shutdown();
    }
  }