Java 类org.apache.hadoop.hdfs.RemotePeerFactory 实例源码

项目：hadoop 文件：TestBlockTokenWithDFS.java

private static void tryRead(final Configuration conf, LocatedBlock lblock,
    boolean shouldSucceed) {
  InetSocketAddress targetAddr = null;
  IOException ioe = null;
  BlockReader blockReader = null;
  ExtendedBlock block = lblock.getBlock();
  try {
    DatanodeInfo[] nodes = lblock.getLocations();
    targetAddr = NetUtils.createSocketAddr(nodes[0].getXferAddr());

    blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
        setFileName(BlockReaderFactory.getFileName(targetAddr, 
                      "test-blockpoolid", block.getBlockId())).
        setBlock(block).
        setBlockToken(lblock.getBlockToken()).
        setInetSocketAddress(targetAddr).
        setStartOffset(0).
        setLength(-1).
        setVerifyChecksum(true).
        setClientName("TestBlockTokenWithDFS").
        setDatanodeInfo(nodes[0]).
        setCachingStrategy(CachingStrategy.newDefaultStrategy()).
        setClientCacheContext(ClientContext.getFromConf(conf)).
        setConfiguration(conf).
        setRemotePeerFactory(new RemotePeerFactory() {
          @Override
          public Peer newConnectedPeer(InetSocketAddress addr,
              Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
              throws IOException {
            Peer peer = null;
            Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
            try {
              sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
              sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
              peer = TcpPeerServer.peerFromSocket(sock);
            } finally {
              if (peer == null) {
                IOUtils.closeSocket(sock);
              }
            }
            return peer;
          }
        }).
        build();
  } catch (IOException ex) {
    ioe = ex;
  } finally {
    if (blockReader != null) {
      try {
        blockReader.close();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  }
  if (shouldSucceed) {
    Assert.assertNotNull("OP_READ_BLOCK: access token is invalid, "
          + "when it is expected to be valid", blockReader);
  } else {
    Assert.assertNotNull("OP_READ_BLOCK: access token is valid, "
        + "when it is expected to be invalid", ioe);
    Assert.assertTrue(
        "OP_READ_BLOCK failed due to reasons other than access token: ",
        ioe instanceof InvalidBlockTokenException);
  }
}

项目：hadoop 文件：TestDataNodeVolumeFailure.java

/**
 * try to access a block on a data node. If fails - throws exception
 * @param datanode
 * @param lblock
 * @throws IOException
 */
private void accessBlock(DatanodeInfo datanode, LocatedBlock lblock)
  throws IOException {
  InetSocketAddress targetAddr = null;
  ExtendedBlock block = lblock.getBlock(); 

  targetAddr = NetUtils.createSocketAddr(datanode.getXferAddr());

  BlockReader blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
    setInetSocketAddress(targetAddr).
    setBlock(block).
    setFileName(BlockReaderFactory.getFileName(targetAddr,
                  "test-blockpoolid", block.getBlockId())).
    setBlockToken(lblock.getBlockToken()).
    setStartOffset(0).
    setLength(-1).
    setVerifyChecksum(true).
    setClientName("TestDataNodeVolumeFailure").
    setDatanodeInfo(datanode).
    setCachingStrategy(CachingStrategy.newDefaultStrategy()).
    setClientCacheContext(ClientContext.getFromConf(conf)).
    setConfiguration(conf).
    setRemotePeerFactory(new RemotePeerFactory() {
      @Override
      public Peer newConnectedPeer(InetSocketAddress addr,
          Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
          throws IOException {
        Peer peer = null;
        Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
        try {
          sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
          sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
          peer = TcpPeerServer.peerFromSocket(sock);
        } finally {
          if (peer == null) {
            IOUtils.closeSocket(sock);
          }
        }
        return peer;
      }
    }).
    build();
  blockReader.close();
}

项目：aliyun-oss-hadoop-fs 文件：TestBlockTokenWithDFS.java

protected void tryRead(final Configuration conf, LocatedBlock lblock,
    boolean shouldSucceed) {
  InetSocketAddress targetAddr = null;
  IOException ioe = null;
  BlockReader blockReader = null;
  ExtendedBlock block = lblock.getBlock();
  try {
    DatanodeInfo[] nodes = lblock.getLocations();
    targetAddr = NetUtils.createSocketAddr(nodes[0].getXferAddr());

    blockReader = new BlockReaderFactory(new DfsClientConf(conf)).
        setFileName(BlockReaderFactory.getFileName(targetAddr,
                      "test-blockpoolid", block.getBlockId())).
        setBlock(block).
        setBlockToken(lblock.getBlockToken()).
        setInetSocketAddress(targetAddr).
        setStartOffset(0).
        setLength(-1).
        setVerifyChecksum(true).
        setClientName("TestBlockTokenWithDFS").
        setDatanodeInfo(nodes[0]).
        setCachingStrategy(CachingStrategy.newDefaultStrategy()).
        setClientCacheContext(ClientContext.getFromConf(conf)).
        setConfiguration(conf).
        setTracer(FsTracer.get(conf)).
        setRemotePeerFactory(new RemotePeerFactory() {
          @Override
          public Peer newConnectedPeer(InetSocketAddress addr,
              Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
              throws IOException {
            Peer peer = null;
            Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
            try {
              sock.connect(addr, HdfsConstants.READ_TIMEOUT);
              sock.setSoTimeout(HdfsConstants.READ_TIMEOUT);
              peer = DFSUtilClient.peerFromSocket(sock);
            } finally {
              if (peer == null) {
                IOUtils.closeSocket(sock);
              }
            }
            return peer;
          }
        }).
        build();
  } catch (IOException ex) {
    ioe = ex;
  } finally {
    if (blockReader != null) {
      try {
        blockReader.close();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  }
  if (shouldSucceed) {
    Assert.assertNotNull("OP_READ_BLOCK: access token is invalid, "
          + "when it is expected to be valid", blockReader);
  } else {
    Assert.assertNotNull("OP_READ_BLOCK: access token is valid, "
        + "when it is expected to be invalid", ioe);
    Assert.assertTrue(
        "OP_READ_BLOCK failed due to reasons other than access token: ",
        ioe instanceof InvalidBlockTokenException);
  }
}

项目：aliyun-oss-hadoop-fs 文件：TestDataNodeVolumeFailure.java

/**
 * try to access a block on a data node. If fails - throws exception
 * @param datanode
 * @param lblock
 * @throws IOException
 */
private void accessBlock(DatanodeInfo datanode, LocatedBlock lblock)
  throws IOException {
  InetSocketAddress targetAddr = null;
  ExtendedBlock block = lblock.getBlock(); 

  targetAddr = NetUtils.createSocketAddr(datanode.getXferAddr());

  BlockReader blockReader = new BlockReaderFactory(new DfsClientConf(conf)).
    setInetSocketAddress(targetAddr).
    setBlock(block).
    setFileName(BlockReaderFactory.getFileName(targetAddr,
                  "test-blockpoolid", block.getBlockId())).
    setBlockToken(lblock.getBlockToken()).
    setStartOffset(0).
    setLength(-1).
    setVerifyChecksum(true).
    setClientName("TestDataNodeVolumeFailure").
    setDatanodeInfo(datanode).
    setCachingStrategy(CachingStrategy.newDefaultStrategy()).
    setClientCacheContext(ClientContext.getFromConf(conf)).
    setConfiguration(conf).
    setTracer(FsTracer.get(conf)).
    setRemotePeerFactory(new RemotePeerFactory() {
      @Override
      public Peer newConnectedPeer(InetSocketAddress addr,
          Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
          throws IOException {
        Peer peer = null;
        Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
        try {
          sock.connect(addr, HdfsConstants.READ_TIMEOUT);
          sock.setSoTimeout(HdfsConstants.READ_TIMEOUT);
          peer = DFSUtilClient.peerFromSocket(sock);
        } finally {
          if (peer == null) {
            IOUtils.closeSocket(sock);
          }
        }
        return peer;
      }
    }).
    build();
  blockReader.close();
}

项目：big-c 文件：TestBlockTokenWithDFS.java

private static void tryRead(final Configuration conf, LocatedBlock lblock,
    boolean shouldSucceed) {
  InetSocketAddress targetAddr = null;
  IOException ioe = null;
  BlockReader blockReader = null;
  ExtendedBlock block = lblock.getBlock();
  try {
    DatanodeInfo[] nodes = lblock.getLocations();
    targetAddr = NetUtils.createSocketAddr(nodes[0].getXferAddr());

    blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
        setFileName(BlockReaderFactory.getFileName(targetAddr, 
                      "test-blockpoolid", block.getBlockId())).
        setBlock(block).
        setBlockToken(lblock.getBlockToken()).
        setInetSocketAddress(targetAddr).
        setStartOffset(0).
        setLength(-1).
        setVerifyChecksum(true).
        setClientName("TestBlockTokenWithDFS").
        setDatanodeInfo(nodes[0]).
        setCachingStrategy(CachingStrategy.newDefaultStrategy()).
        setClientCacheContext(ClientContext.getFromConf(conf)).
        setConfiguration(conf).
        setRemotePeerFactory(new RemotePeerFactory() {
          @Override
          public Peer newConnectedPeer(InetSocketAddress addr,
              Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
              throws IOException {
            Peer peer = null;
            Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
            try {
              sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
              sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
              peer = TcpPeerServer.peerFromSocket(sock);
            } finally {
              if (peer == null) {
                IOUtils.closeSocket(sock);
              }
            }
            return peer;
          }
        }).
        build();
  } catch (IOException ex) {
    ioe = ex;
  } finally {
    if (blockReader != null) {
      try {
        blockReader.close();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  }
  if (shouldSucceed) {
    Assert.assertNotNull("OP_READ_BLOCK: access token is invalid, "
          + "when it is expected to be valid", blockReader);
  } else {
    Assert.assertNotNull("OP_READ_BLOCK: access token is valid, "
        + "when it is expected to be invalid", ioe);
    Assert.assertTrue(
        "OP_READ_BLOCK failed due to reasons other than access token: ",
        ioe instanceof InvalidBlockTokenException);
  }
}

项目：big-c 文件：TestDataNodeVolumeFailure.java

/**
 * try to access a block on a data node. If fails - throws exception
 * @param datanode
 * @param lblock
 * @throws IOException
 */
private void accessBlock(DatanodeInfo datanode, LocatedBlock lblock)
  throws IOException {
  InetSocketAddress targetAddr = null;
  ExtendedBlock block = lblock.getBlock(); 

  targetAddr = NetUtils.createSocketAddr(datanode.getXferAddr());

  BlockReader blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
    setInetSocketAddress(targetAddr).
    setBlock(block).
    setFileName(BlockReaderFactory.getFileName(targetAddr,
                  "test-blockpoolid", block.getBlockId())).
    setBlockToken(lblock.getBlockToken()).
    setStartOffset(0).
    setLength(-1).
    setVerifyChecksum(true).
    setClientName("TestDataNodeVolumeFailure").
    setDatanodeInfo(datanode).
    setCachingStrategy(CachingStrategy.newDefaultStrategy()).
    setClientCacheContext(ClientContext.getFromConf(conf)).
    setConfiguration(conf).
    setRemotePeerFactory(new RemotePeerFactory() {
      @Override
      public Peer newConnectedPeer(InetSocketAddress addr,
          Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
          throws IOException {
        Peer peer = null;
        Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
        try {
          sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
          sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
          peer = TcpPeerServer.peerFromSocket(sock);
        } finally {
          if (peer == null) {
            IOUtils.closeSocket(sock);
          }
        }
        return peer;
      }
    }).
    build();
  blockReader.close();
}

项目：hadoop-2.6.0-cdh5.4.3 文件：TestBlockTokenWithDFS.java

private static void tryRead(final Configuration conf, LocatedBlock lblock,
    boolean shouldSucceed) {
  InetSocketAddress targetAddr = null;
  IOException ioe = null;
  BlockReader blockReader = null;
  ExtendedBlock block = lblock.getBlock();
  try {
    DatanodeInfo[] nodes = lblock.getLocations();
    targetAddr = NetUtils.createSocketAddr(nodes[0].getXferAddr());

    blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
        setFileName(BlockReaderFactory.getFileName(targetAddr, 
                      "test-blockpoolid", block.getBlockId())).
        setBlock(block).
        setBlockToken(lblock.getBlockToken()).
        setInetSocketAddress(targetAddr).
        setStartOffset(0).
        setLength(-1).
        setVerifyChecksum(true).
        setClientName("TestBlockTokenWithDFS").
        setDatanodeInfo(nodes[0]).
        setCachingStrategy(CachingStrategy.newDefaultStrategy()).
        setClientCacheContext(ClientContext.getFromConf(conf)).
        setConfiguration(conf).
        setRemotePeerFactory(new RemotePeerFactory() {
          @Override
          public Peer newConnectedPeer(InetSocketAddress addr,
              Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
              throws IOException {
            Peer peer = null;
            Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
            try {
              sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
              sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
              peer = TcpPeerServer.peerFromSocket(sock);
            } finally {
              if (peer == null) {
                IOUtils.closeSocket(sock);
              }
            }
            return peer;
          }
        }).
        build();
  } catch (IOException ex) {
    ioe = ex;
  } finally {
    if (blockReader != null) {
      try {
        blockReader.close();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  }
  if (shouldSucceed) {
    Assert.assertNotNull("OP_READ_BLOCK: access token is invalid, "
          + "when it is expected to be valid", blockReader);
  } else {
    Assert.assertNotNull("OP_READ_BLOCK: access token is valid, "
        + "when it is expected to be invalid", ioe);
    Assert.assertTrue(
        "OP_READ_BLOCK failed due to reasons other than access token: ",
        ioe instanceof InvalidBlockTokenException);
  }
}

项目：hadoop-2.6.0-cdh5.4.3 文件：TestDataNodeVolumeFailure.java

/**
 * try to access a block on a data node. If fails - throws exception
 * @param datanode
 * @param lblock
 * @throws IOException
 */
private void accessBlock(DatanodeInfo datanode, LocatedBlock lblock)
  throws IOException {
  InetSocketAddress targetAddr = null;
  ExtendedBlock block = lblock.getBlock(); 

  targetAddr = NetUtils.createSocketAddr(datanode.getXferAddr());

  BlockReader blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
    setInetSocketAddress(targetAddr).
    setBlock(block).
    setFileName(BlockReaderFactory.getFileName(targetAddr,
                  "test-blockpoolid", block.getBlockId())).
    setBlockToken(lblock.getBlockToken()).
    setStartOffset(0).
    setLength(-1).
    setVerifyChecksum(true).
    setClientName("TestDataNodeVolumeFailure").
    setDatanodeInfo(datanode).
    setCachingStrategy(CachingStrategy.newDefaultStrategy()).
    setClientCacheContext(ClientContext.getFromConf(conf)).
    setConfiguration(conf).
    setRemotePeerFactory(new RemotePeerFactory() {
      @Override
      public Peer newConnectedPeer(InetSocketAddress addr,
          Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
          throws IOException {
        Peer peer = null;
        Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
        try {
          sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
          sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
          peer = TcpPeerServer.peerFromSocket(sock);
        } finally {
          if (peer == null) {
            IOUtils.closeSocket(sock);
          }
        }
        return peer;
      }
    }).
    build();
  blockReader.close();
}

项目：FlexMap 文件：TestBlockTokenWithDFS.java

private static void tryRead(final Configuration conf, LocatedBlock lblock,
    boolean shouldSucceed) {
  InetSocketAddress targetAddr = null;
  IOException ioe = null;
  BlockReader blockReader = null;
  ExtendedBlock block = lblock.getBlock();
  try {
    DatanodeInfo[] nodes = lblock.getLocations();
    targetAddr = NetUtils.createSocketAddr(nodes[0].getXferAddr());

    blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
        setFileName(BlockReaderFactory.getFileName(targetAddr, 
                      "test-blockpoolid", block.getBlockId())).
        setBlock(block).
        setBlockToken(lblock.getBlockToken()).
        setInetSocketAddress(targetAddr).
        setStartOffset(0).
        setLength(-1).
        setVerifyChecksum(true).
        setClientName("TestBlockTokenWithDFS").
        setDatanodeInfo(nodes[0]).
        setCachingStrategy(CachingStrategy.newDefaultStrategy()).
        setClientCacheContext(ClientContext.getFromConf(conf)).
        setConfiguration(conf).
        setRemotePeerFactory(new RemotePeerFactory() {
          @Override
          public Peer newConnectedPeer(InetSocketAddress addr,
              Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
              throws IOException {
            Peer peer = null;
            Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
            try {
              sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
              sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
              peer = TcpPeerServer.peerFromSocket(sock);
            } finally {
              if (peer == null) {
                IOUtils.closeSocket(sock);
              }
            }
            return peer;
          }
        }).
        build();
  } catch (IOException ex) {
    ioe = ex;
  } finally {
    if (blockReader != null) {
      try {
        blockReader.close();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  }
  if (shouldSucceed) {
    Assert.assertNotNull("OP_READ_BLOCK: access token is invalid, "
          + "when it is expected to be valid", blockReader);
  } else {
    Assert.assertNotNull("OP_READ_BLOCK: access token is valid, "
        + "when it is expected to be invalid", ioe);
    Assert.assertTrue(
        "OP_READ_BLOCK failed due to reasons other than access token: ",
        ioe instanceof InvalidBlockTokenException);
  }
}

项目：FlexMap 文件：TestDataNodeVolumeFailure.java

/**
 * try to access a block on a data node. If fails - throws exception
 * @param datanode
 * @param lblock
 * @throws IOException
 */
private void accessBlock(DatanodeInfo datanode, LocatedBlock lblock)
  throws IOException {
  InetSocketAddress targetAddr = null;
  ExtendedBlock block = lblock.getBlock(); 

  targetAddr = NetUtils.createSocketAddr(datanode.getXferAddr());

  BlockReader blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
    setInetSocketAddress(targetAddr).
    setBlock(block).
    setFileName(BlockReaderFactory.getFileName(targetAddr,
                  "test-blockpoolid", block.getBlockId())).
    setBlockToken(lblock.getBlockToken()).
    setStartOffset(0).
    setLength(-1).
    setVerifyChecksum(true).
    setClientName("TestDataNodeVolumeFailure").
    setDatanodeInfo(datanode).
    setCachingStrategy(CachingStrategy.newDefaultStrategy()).
    setClientCacheContext(ClientContext.getFromConf(conf)).
    setConfiguration(conf).
    setRemotePeerFactory(new RemotePeerFactory() {
      @Override
      public Peer newConnectedPeer(InetSocketAddress addr,
          Token<BlockTokenIdentifier> blockToken, DatanodeID datanodeId)
          throws IOException {
        Peer peer = null;
        Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
        try {
          sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
          sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
          peer = TcpPeerServer.peerFromSocket(sock);
        } finally {
          if (peer == null) {
            IOUtils.closeSocket(sock);
          }
        }
        return peer;
      }
    }).
    build();
  blockReader.close();
}

项目：hadoop-on-lustre2 文件：TestBlockTokenWithDFS.java

private static void tryRead(final Configuration conf, LocatedBlock lblock,
    boolean shouldSucceed) {
  InetSocketAddress targetAddr = null;
  IOException ioe = null;
  BlockReader blockReader = null;
  ExtendedBlock block = lblock.getBlock();
  try {
    DatanodeInfo[] nodes = lblock.getLocations();
    targetAddr = NetUtils.createSocketAddr(nodes[0].getXferAddr());

    blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
        setFileName(BlockReaderFactory.getFileName(targetAddr, 
                      "test-blockpoolid", block.getBlockId())).
        setBlock(block).
        setBlockToken(lblock.getBlockToken()).
        setInetSocketAddress(targetAddr).
        setStartOffset(0).
        setLength(-1).
        setVerifyChecksum(true).
        setClientName("TestBlockTokenWithDFS").
        setDatanodeInfo(nodes[0]).
        setCachingStrategy(CachingStrategy.newDefaultStrategy()).
        setClientCacheContext(ClientContext.getFromConf(conf)).
        setConfiguration(conf).
        setRemotePeerFactory(new RemotePeerFactory() {
          @Override
          public Peer newConnectedPeer(InetSocketAddress addr)
              throws IOException {
            Peer peer = null;
            Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
            try {
              sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
              sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
              peer = TcpPeerServer.peerFromSocket(sock);
            } finally {
              if (peer == null) {
                IOUtils.closeSocket(sock);
              }
            }
            return peer;
          }
        }).
        build();
  } catch (IOException ex) {
    ioe = ex;
  } finally {
    if (blockReader != null) {
      try {
        blockReader.close();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  }
  if (shouldSucceed) {
    Assert.assertNotNull("OP_READ_BLOCK: access token is invalid, "
          + "when it is expected to be valid", blockReader);
  } else {
    Assert.assertNotNull("OP_READ_BLOCK: access token is valid, "
        + "when it is expected to be invalid", ioe);
    Assert.assertTrue(
        "OP_READ_BLOCK failed due to reasons other than access token: ",
        ioe instanceof InvalidBlockTokenException);
  }
}

项目：hadoop-on-lustre2 文件：TestDataNodeVolumeFailure.java

/**
 * try to access a block on a data node. If fails - throws exception
 * @param datanode
 * @param lblock
 * @throws IOException
 */
private void accessBlock(DatanodeInfo datanode, LocatedBlock lblock)
  throws IOException {
  InetSocketAddress targetAddr = null;
  ExtendedBlock block = lblock.getBlock(); 

  targetAddr = NetUtils.createSocketAddr(datanode.getXferAddr());

  BlockReader blockReader = new BlockReaderFactory(new DFSClient.Conf(conf)).
    setInetSocketAddress(targetAddr).
    setBlock(block).
    setFileName(BlockReaderFactory.getFileName(targetAddr,
                  "test-blockpoolid", block.getBlockId())).
    setBlockToken(lblock.getBlockToken()).
    setStartOffset(0).
    setLength(-1).
    setVerifyChecksum(true).
    setClientName("TestDataNodeVolumeFailure").
    setDatanodeInfo(datanode).
    setCachingStrategy(CachingStrategy.newDefaultStrategy()).
    setClientCacheContext(ClientContext.getFromConf(conf)).
    setConfiguration(conf).
    setRemotePeerFactory(new RemotePeerFactory() {
      @Override
      public Peer newConnectedPeer(InetSocketAddress addr)
          throws IOException {
        Peer peer = null;
        Socket sock = NetUtils.getDefaultSocketFactory(conf).createSocket();
        try {
          sock.connect(addr, HdfsServerConstants.READ_TIMEOUT);
          sock.setSoTimeout(HdfsServerConstants.READ_TIMEOUT);
          peer = TcpPeerServer.peerFromSocket(sock);
        } finally {
          if (peer == null) {
            IOUtils.closeSocket(sock);
          }
        }
        return peer;
      }
    }).
    build();
  blockReader.close();
}