예제 #1
0
 /** Get the list of Blocks for a file. */
 public List<LocatedBlock> getFileBlocks(Path filepath, int sizeKB) throws IOException {
   // Return the blocks we just wrote
   DFSClient dfsclient = getDFSClient();
   return dfsclient
       .getNamenode()
       .getBlockLocations(filepath.toString(), 0, sizeKB * 1024)
       .getLocatedBlocks();
 }
  /**
   * 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();
    }
  }