Java FSDataset类代码示例

import org.apache.hadoop.hdfs.server.datanode.FSDataset; //导入依赖的package包/类
static List<File> getBlockFiles(MiniDFSCluster cluster) throws IOException {
  List<File> files = new ArrayList<File>();
  List<DataNode> datanodes = cluster.getDataNodes();
  int nsId = cluster.getNameNode().getNamespaceID();
  Block[][] blocks = cluster.getAllBlockReports(nsId);
  for(int i = 0; i < blocks.length; i++) {
    FSDataset ds = (FSDataset)datanodes.get(i).getFSDataset();
    for(Block b : blocks[i]) {
      files.add(ds.getBlockFile(nsId,b));
    }        
  }
  return files;
}
 

import org.apache.hadoop.hdfs.server.datanode.FSDataset; //导入依赖的package包/类
static List<File> getBlockFiles(MiniDFSCluster cluster) throws IOException {
  List<File> files = new ArrayList<File>();
  List<DataNode> datanodes = cluster.getDataNodes();
  Block[][] blocks = cluster.getAllBlockReports();
  for(int i = 0; i < blocks.length; i++) {
    FSDataset ds = (FSDataset)datanodes.get(i).getFSDataset();
    for(Block b : blocks[i]) {
      files.add(ds.getBlockFile(b));
    }        
  }
  return files;
}
 

import org.apache.hadoop.hdfs.server.datanode.FSDataset; //导入依赖的package包/类
static List<File> getBlockFiles(MiniDFSCluster cluster) throws IOException {
  List<File> files = new ArrayList<File>();
  List<DataNode> datanodes = cluster.getDataNodes();
  Iterable<Block>[] blocks = cluster.getAllBlockReports();
  for(int i = 0; i < blocks.length; i++) {
    FSDataset ds = (FSDataset)datanodes.get(i).getFSDataset();
    for(Block b : blocks[i]) {
      files.add(ds.getBlockFile(b));
    }        
  }
  return files;
}
 

import org.apache.hadoop.hdfs.server.datanode.FSDataset; //导入依赖的package包/类
public void testParallelCheckDirs() throws Exception {
  final DataNode datanode = cluster.getDataNodes().get(0);
  FSDataset fsDataset = (FSDataset) datanode.data;
  datanode.data = spy(fsDataset);

  final Method checkDiskMethod = DataNode.class.getDeclaredMethod(
      "checkDiskError", Exception.class);
  checkDiskMethod.setAccessible(true);

  doAnswer(new Answer() {
    public Object answer(InvocationOnMock invocation) {
      try {
        Thread.sleep(1000);
      } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
      return null;
    }
  }).when(datanode.data).checkDataDir();
  
  Thread[] threads = new Thread[30];
  for (int i = 0; i < 30; i++) {
    threads[i] = new Thread() {
      public void run() {
        try {
          checkDiskMethod.invoke(datanode, new Exception("Fake Exception"));
        } catch (IllegalArgumentException e) {
          TestCase.fail("IllegalArgumentException");
        } catch (IllegalAccessException e) {
          TestCase.fail("IllegalAccessException");
        } catch (InvocationTargetException e) {
          TestCase.fail("InvocationTargetException");
        }
      }
    };
  }

  // Parallel 10 checks should only have one launched.
  for (int i = 0; i < 10; i++) {
    threads[i].start();
  }
  for (int i = 0; i < 10; i++) {
    threads[i].join();
  }
  verify(datanode.data, times(1)).checkDataDir();

  // Next checks won't be launched as one recently finishes.
  for (int i = 10; i < 20; i++) {
    threads[i].start();
  }
  for (int i = 10; i < 20; i++) {
    threads[i].join();
  }
  verify(datanode.data, times(1)).checkDataDir();

  // After 2 seconds, another check should be able to run
  Thread.sleep(2000);
  for (int i = 20; i < 30; i++) {
    threads[i].start();
  }
  for (int i = 20; i < 30; i++) {
    threads[i].join();
  }
  verify(datanode.data, times(2)).checkDataDir();
}
 

import org.apache.hadoop.hdfs.server.datanode.FSDataset; //导入依赖的package包/类
/**
 * The only way this object can be instantiated.
 */
static BlockReaderLocal newBlockReader(Configuration conf,
  String file, Block blk, Token<BlockTokenIdentifier> token, DatanodeInfo node, 
  int socketTimeout, long startOffset, long length) throws IOException {
  
  LocalDatanodeInfo localDatanodeInfo =  getLocalDatanodeInfo(node.getIpcPort());
  // check the cache first
  BlockLocalPathInfo pathinfo = localDatanodeInfo.getBlockLocalPathInfo(blk);
  if (pathinfo == null) {
    pathinfo = getBlockPathInfo(blk, node, conf, socketTimeout, token);
  }

  // check to see if the file exists. It may so happen that the
  // HDFS file has been deleted and this block-lookup is occurring
  // on behalf of a new HDFS file. This time, the block file could
  // be residing in a different portion of the fs.data.dir directory.
  // In this case, we remove this entry from the cache. The next
  // call to this method will re-populate the cache.
  FileInputStream dataIn = null;
  FileInputStream checksumIn = null;
  BlockReaderLocal localBlockReader = null;
  boolean skipChecksum = shortCircuitChecksum(conf);
  try {
    // get a local file system
    File blkfile = new File(pathinfo.getBlockPath());
    dataIn = new FileInputStream(blkfile);

    if (LOG.isDebugEnabled()) {
      LOG.debug("New BlockReaderLocal for file " + blkfile + " of size "
          + blkfile.length() + " startOffset " + startOffset + " length "
          + length + " short circuit checksum " + skipChecksum);
    }

    if (!skipChecksum) {
      // get the metadata file
      File metafile = new File(pathinfo.getMetaPath());
      checksumIn = new FileInputStream(metafile);

      // read and handle the common header here. For now just a version
      BlockMetadataHeader header = BlockMetadataHeader
          .readHeader(new DataInputStream(checksumIn));
      short version = header.getVersion();
      if (version != FSDataset.METADATA_VERSION) {
        LOG.warn("Wrong version (" + version + ") for metadata file for "
            + blk + " ignoring ...");
      }
      DataChecksum checksum = header.getChecksum();
      localBlockReader = new BlockReaderLocal(conf, file, blk, token, startOffset, length,
          pathinfo, checksum, true, dataIn, checksumIn);
    } else {
      localBlockReader = new BlockReaderLocal(conf, file, blk, token, startOffset, length,
          pathinfo, dataIn);
    }
  } catch (IOException e) {
    // remove from cache
    localDatanodeInfo.removeBlockLocalPathInfo(blk);
    DFSClient.LOG.warn("BlockReaderLocal: Removing " + blk +
        " from cache because local file " + pathinfo.getBlockPath() +
        " could not be opened.");
    throw e;
  } finally {
    if (localBlockReader == null) {
      if (dataIn != null) {
        dataIn.close();
      }
      if (checksumIn != null) {
        checksumIn.close();
      }
    }  
  }
  return localBlockReader;
}
 

import org.apache.hadoop.hdfs.server.datanode.FSDataset; //导入依赖的package包/类
/**
 * The only way this object can be instantiated.
 */
public static BlockReaderLocal newBlockReader(Configuration conf,
  String file, int namespaceid, Block blk, DatanodeInfo node, 
  long startOffset, long length,
  DFSClientMetrics metrics, boolean verifyChecksum,
  boolean clearOsBuffer) throws IOException {
  // check in cache first
  BlockPathInfo pathinfo = cache.get(blk);

  if (pathinfo == null) {
    // cache the connection to the local data for eternity.
    if (datanode == null) {
      datanode = DFSClient.createClientDNProtocolProxy(node, conf, 0);
    }
    // make RPC to local datanode to find local pathnames of blocks
    if (datanode.isMethodSupported("getBlockPathInfo", int.class, Block.class)) {
      pathinfo = datanode.getProxy().getBlockPathInfo(namespaceid, blk);
    } else {
      pathinfo = datanode.getProxy().getBlockPathInfo(blk);
    }
    if (pathinfo != null) {
      cache.put(blk, pathinfo);
    }
  }
  
  // check to see if the file exists. It may so happen that the
  // HDFS file has been deleted and this block-lookup is occuring
  // on behalf of a new HDFS file. This time, the block file could
  // be residing in a different portion of the fs.data.dir directory.
  // In this case, we remove this entry from the cache. The next
  // call to this method will repopulate the cache.
  try {

    // get a local file system
    File blkfile = new File(pathinfo.getBlockPath());
    FileInputStream dataIn = new FileInputStream(blkfile);
    
    if (LOG.isDebugEnabled()) {
      LOG.debug("New BlockReaderLocal for file " +
                blkfile + " of size " + blkfile.length() +
                " startOffset " + startOffset +
                " length " + length);
    }

    if (verifyChecksum) {
    
      // get the metadata file
      File metafile = new File(pathinfo.getMetaPath());
      FileInputStream checksumIn = new FileInputStream(metafile);
  
      // read and handle the common header here. For now just a version
      BlockMetadataHeader header = BlockMetadataHeader.readHeader(new DataInputStream(checksumIn), new PureJavaCrc32());
      short version = header.getVersion();
    
      if (version != FSDataset.METADATA_VERSION) {
        LOG.warn("Wrong version (" + version + ") for metadata file for "
            + blk + " ignoring ...");
      }
      DataChecksum checksum = header.getChecksum();

      return new BlockReaderLocal(conf, file, blk, startOffset, length,
          pathinfo, metrics, checksum, verifyChecksum, dataIn, checksumIn,
          clearOsBuffer);
    }
    else {
      return new BlockReaderLocal(conf, file, blk, startOffset, length,
          pathinfo, metrics, dataIn, clearOsBuffer);
    }
    
  } catch (FileNotFoundException e) {
    cache.remove(blk);    // remove from cache
    DFSClient.LOG.warn("BlockReaderLoca: Removing " + blk +
                       " from cache because local file " +
                       pathinfo.getBlockPath() + 
                       " could not be opened.");
    throw e;
  }
}