Java Code Examples for org.apache.hadoop.hdfs.protocol.ExtendedBlock#getGenerationStamp()

@Override // FsDatasetSpi
public BlockLocalPathInfo getBlockLocalPathInfo(ExtendedBlock block)
    throws IOException {
  synchronized(this) {
    final Replica replica = volumeMap.get(block.getBlockPoolId(),
        block.getBlockId());
    if (replica == null) {
      throw new ReplicaNotFoundException(block);
    }
    if (replica.getGenerationStamp() < block.getGenerationStamp()) {
      throw new IOException(
          "Replica generation stamp < block generation stamp, block="
          + block + ", replica=" + replica);
    } else if (replica.getGenerationStamp() > block.getGenerationStamp()) {
      block.setGenerationStamp(replica.getGenerationStamp());
    }
  }

  File datafile = getBlockFile(block);
  File metafile = FsDatasetUtil.getMetaFile(datafile, block.getGenerationStamp());
  BlockLocalPathInfo info = new BlockLocalPathInfo(block,
      datafile.getAbsolutePath(), metafile.getAbsolutePath());
  return info;
}
 

private static ExtendedBlock[][] generateBlocks(Suite s, long size
    ) throws IOException, InterruptedException, TimeoutException {
  final ExtendedBlock[][] blocks = new ExtendedBlock[s.clients.length][];
  for(int n = 0; n < s.clients.length; n++) {
    final long fileLen = size/s.replication;
    createFile(s, n, fileLen);

    final List<LocatedBlock> locatedBlocks = s.clients[n].getBlockLocations(
        FILE_NAME, 0, fileLen).getLocatedBlocks();

    final int numOfBlocks = locatedBlocks.size();
    blocks[n] = new ExtendedBlock[numOfBlocks];
    for(int i = 0; i < numOfBlocks; i++) {
      final ExtendedBlock b = locatedBlocks.get(i).getBlock();
      blocks[n][i] = new ExtendedBlock(b.getBlockPoolId(), b.getBlockId(),
          b.getNumBytes(), b.getGenerationStamp());
    }
  }
  return blocks;
}
 

/**
 * Transfer a replica to the datanode targets.
 * @param b the block to transfer.
 *          The corresponding replica must be an RBW or a Finalized.
 *          Its GS and numBytes will be set to
 *          the stored GS and the visible length. 
 * @param targets targets to transfer the block to
 * @param client client name
 */
void transferReplicaForPipelineRecovery(final ExtendedBlock b,
    final DatanodeInfo[] targets, final StorageType[] targetStorageTypes,
    final String client) throws IOException {
  final long storedGS;
  final long visible;
  final BlockConstructionStage stage;

  //get replica information
  synchronized(data) {
    Block storedBlock = data.getStoredBlock(b.getBlockPoolId(),
        b.getBlockId());
    if (null == storedBlock) {
      throw new IOException(b + " not found in datanode.");
    }
    storedGS = storedBlock.getGenerationStamp();
    if (storedGS < b.getGenerationStamp()) {
      throw new IOException(storedGS
          + " = storedGS < b.getGenerationStamp(), b=" + b);
    }
    // Update the genstamp with storedGS
    b.setGenerationStamp(storedGS);
    if (data.isValidRbw(b)) {
      stage = BlockConstructionStage.TRANSFER_RBW;
    } else if (data.isValidBlock(b)) {
      stage = BlockConstructionStage.TRANSFER_FINALIZED;
    } else {
      final String r = data.getReplicaString(b.getBlockPoolId(), b.getBlockId());
      throw new IOException(b + " is neither a RBW nor a Finalized, r=" + r);
    }
    visible = data.getReplicaVisibleLength(b);
  }
  //set visible length
  b.setNumBytes(visible);

  if (targets.length > 0) {
    new DataTransfer(targets, targetStorageTypes, b, stage, client).run();
  }
}
 

/**
 * Transfer a replica to the datanode targets.
 * @param b the block to transfer.
 *          The corresponding replica must be an RBW or a Finalized.
 *          Its GS and numBytes will be set to
 *          the stored GS and the visible length. 
 * @param targets targets to transfer the block to
 * @param client client name
 */
void transferReplicaForPipelineRecovery(final ExtendedBlock b,
    final DatanodeInfo[] targets, final StorageType[] targetStorageTypes,
    final String client) throws IOException {
  final long storedGS;
  final long visible;
  final BlockConstructionStage stage;

  //get replica information
  synchronized(data) {
    Block storedBlock = data.getStoredBlock(b.getBlockPoolId(),
        b.getBlockId());
    if (null == storedBlock) {
      throw new IOException(b + " not found in datanode.");
    }
    storedGS = storedBlock.getGenerationStamp();
    if (storedGS < b.getGenerationStamp()) {
      throw new IOException(storedGS
          + " = storedGS < b.getGenerationStamp(), b=" + b);
    }
    // Update the genstamp with storedGS
    b.setGenerationStamp(storedGS);
    if (data.isValidRbw(b)) {
      stage = BlockConstructionStage.TRANSFER_RBW;
    } else if (data.isValidBlock(b)) {
      stage = BlockConstructionStage.TRANSFER_FINALIZED;
    } else {
      final String r = data.getReplicaString(b.getBlockPoolId(), b.getBlockId());
      throw new IOException(b + " is neither a RBW nor a Finalized, r=" + r);
    }
    visible = data.getReplicaVisibleLength(b);
  }
  //set visible length
  b.setNumBytes(visible);

  if (targets.length > 0) {
    new DataTransfer(targets, targetStorageTypes, b, stage, client).run();
  }
}
 

@Override  // FsDatasetSpi
public synchronized ReplicaHandler append(ExtendedBlock b,
    long newGS, long expectedBlockLen) throws IOException {
  // If the block was successfully finalized because all packets
  // were successfully processed at the Datanode but the ack for
  // some of the packets were not received by the client. The client 
  // re-opens the connection and retries sending those packets.
  // The other reason is that an "append" is occurring to this block.
  
  // check the validity of the parameter
  if (newGS < b.getGenerationStamp()) {
    throw new IOException("The new generation stamp " + newGS + 
        " should be greater than the replica " + b + "'s generation stamp");
  }
  ReplicaInfo replicaInfo = getReplicaInfo(b);
  LOG.info("Appending to " + replicaInfo);
  if (replicaInfo.getState() != ReplicaState.FINALIZED) {
    throw new ReplicaNotFoundException(
        ReplicaNotFoundException.UNFINALIZED_REPLICA + b);
  }
  if (replicaInfo.getNumBytes() != expectedBlockLen) {
    throw new IOException("Corrupted replica " + replicaInfo + 
        " with a length of " + replicaInfo.getNumBytes() + 
        " expected length is " + expectedBlockLen);
  }

  FsVolumeReference ref = replicaInfo.getVolume().obtainReference();
  ReplicaBeingWritten replica = null;
  try {
    replica = append(b.getBlockPoolId(), (FinalizedReplica)replicaInfo, newGS,
        b.getNumBytes());
  } catch (IOException e) {
    IOUtils.cleanup(null, ref);
    throw e;
  }
  return new ReplicaHandler(replica, ref);
}
 

static void checkSuccess(
    BlockOpResponseProto status, Peer peer,
    ExtendedBlock block, String file)
    throws IOException {
  String logInfo = "for OP_READ_BLOCK"
    + ", self=" + peer.getLocalAddressString()
    + ", remote=" + peer.getRemoteAddressString()
    + ", for file " + file
    + ", for pool " + block.getBlockPoolId()
    + " block " + block.getBlockId() + "_" + block.getGenerationStamp();
  DataTransferProtoUtil.checkBlockOpStatus(status, logInfo);
}
 

@Override // FsDatasetSpi
public synchronized long getReplicaVisibleLength(final ExtendedBlock block)
throws IOException {
  final Replica replica = getReplicaInfo(block.getBlockPoolId(), 
      block.getBlockId());
  if (replica.getGenerationStamp() < block.getGenerationStamp()) {
    throw new IOException(
        "replica.getGenerationStamp() < block.getGenerationStamp(), block="
        + block + ", replica=" + replica);
  }
  return replica.getVisibleLength();
}
 

@Override // FsDatasetSpi
public synchronized long getReplicaVisibleLength(final ExtendedBlock block)
throws IOException {
  final Replica replica = getReplicaInfo(block.getBlockPoolId(), 
      block.getBlockId());
  if (replica.getGenerationStamp() < block.getGenerationStamp()) {
    throw new IOException(
        "replica.getGenerationStamp() < block.getGenerationStamp(), block="
        + block + ", replica=" + replica);
  }
  return replica.getVisibleLength();
}
 

@Override // FsDatasetSpi
public ReplicaHandler createTemporary(
    StorageType storageType, ExtendedBlock b) throws IOException {
  long startTimeMs = Time.monotonicNow();
  long writerStopTimeoutMs = datanode.getDnConf().getXceiverStopTimeout();
  ReplicaInfo lastFoundReplicaInfo = null;
  do {
    synchronized (this) {
      ReplicaInfo currentReplicaInfo =
          volumeMap.get(b.getBlockPoolId(), b.getBlockId());
      if (currentReplicaInfo == lastFoundReplicaInfo) {
        if (lastFoundReplicaInfo != null) {
          invalidate(b.getBlockPoolId(), new Block[] { lastFoundReplicaInfo });
        }
        FsVolumeReference ref =
            volumes.getNextVolume(storageType, b.getNumBytes());
        FsVolumeImpl v = (FsVolumeImpl) ref.getVolume();
        // create a temporary file to hold block in the designated volume
        File f;
        try {
          f = v.createTmpFile(b.getBlockPoolId(), b.getLocalBlock());
        } catch (IOException e) {
          IOUtils.cleanup(null, ref);
          throw e;
        }
        ReplicaInPipeline newReplicaInfo =
            new ReplicaInPipeline(b.getBlockId(), b.getGenerationStamp(), v,
                f.getParentFile(), 0);
        volumeMap.add(b.getBlockPoolId(), newReplicaInfo);
        return new ReplicaHandler(newReplicaInfo, ref);
      } else {
        if (!(currentReplicaInfo.getGenerationStamp() < b
            .getGenerationStamp() && currentReplicaInfo instanceof ReplicaInPipeline)) {
          throw new ReplicaAlreadyExistsException("Block " + b
              + " already exists in state " + currentReplicaInfo.getState()
              + " and thus cannot be created.");
        }
        lastFoundReplicaInfo = currentReplicaInfo;
      }
    }

    // Hang too long, just bail out. This is not supposed to happen.
    long writerStopMs = Time.monotonicNow() - startTimeMs;
    if (writerStopMs > writerStopTimeoutMs) {
      LOG.warn("Unable to stop existing writer for block " + b + " after " 
          + writerStopMs + " miniseconds.");
      throw new IOException("Unable to stop existing writer for block " + b
          + " after " + writerStopMs + " miniseconds.");
    }

    // Stop the previous writer
    ((ReplicaInPipeline) lastFoundReplicaInfo)
        .stopWriter(writerStopTimeoutMs);
  } while (true);
}
 

/** Recover a block */
private void recoverBlock(RecoveringBlock rBlock) throws IOException {
  ExtendedBlock block = rBlock.getBlock();
  String blookPoolId = block.getBlockPoolId();
  DatanodeID[] datanodeids = rBlock.getLocations();
  List<BlockRecord> syncList = new ArrayList<BlockRecord>(datanodeids.length);
  int errorCount = 0;

  //check generation stamps
  for(DatanodeID id : datanodeids) {
    try {
      BPOfferService bpos = blockPoolManager.get(blookPoolId);
      DatanodeRegistration bpReg = bpos.bpRegistration;
      InterDatanodeProtocol datanode = bpReg.equals(id)?
          this: DataNode.createInterDataNodeProtocolProxy(id, getConf(),
              dnConf.socketTimeout, dnConf.connectToDnViaHostname);
      ReplicaRecoveryInfo info = callInitReplicaRecovery(datanode, rBlock);
      if (info != null &&
          info.getGenerationStamp() >= block.getGenerationStamp() &&
          info.getNumBytes() > 0) {
        syncList.add(new BlockRecord(id, datanode, info));
      }
    } catch (RecoveryInProgressException ripE) {
      InterDatanodeProtocol.LOG.warn(
          "Recovery for replica " + block + " on data-node " + id
          + " is already in progress. Recovery id = "
          + rBlock.getNewGenerationStamp() + " is aborted.", ripE);
      return;
    } catch (IOException e) {
      ++errorCount;
      InterDatanodeProtocol.LOG.warn(
          "Failed to obtain replica info for block (=" + block 
          + ") from datanode (=" + id + ")", e);
    }
  }

  if (errorCount == datanodeids.length) {
    throw new IOException("All datanodes failed: block=" + block
        + ", datanodeids=" + Arrays.asList(datanodeids));
  }

  syncBlock(rBlock, syncList);
}
 

@Override // FsDatasetSpi
public synchronized ReplicaInPipeline convertTemporaryToRbw(
    final ExtendedBlock b) throws IOException {
  final long blockId = b.getBlockId();
  final long expectedGs = b.getGenerationStamp();
  final long visible = b.getNumBytes();
  LOG.info("Convert " + b + " from Temporary to RBW, visible length="
      + visible);

  final ReplicaInPipeline temp;
  {
    // get replica
    final ReplicaInfo r = volumeMap.get(b.getBlockPoolId(), blockId);
    if (r == null) {
      throw new ReplicaNotFoundException(
          ReplicaNotFoundException.NON_EXISTENT_REPLICA + b);
    }
    // check the replica's state
    if (r.getState() != ReplicaState.TEMPORARY) {
      throw new ReplicaAlreadyExistsException(
          "r.getState() != ReplicaState.TEMPORARY, r=" + r);
    }
    temp = (ReplicaInPipeline)r;
  }
  // check generation stamp
  if (temp.getGenerationStamp() != expectedGs) {
    throw new ReplicaAlreadyExistsException(
        "temp.getGenerationStamp() != expectedGs = " + expectedGs
        + ", temp=" + temp);
  }

  // TODO: check writer?
  // set writer to the current thread
  // temp.setWriter(Thread.currentThread());

  // check length
  final long numBytes = temp.getNumBytes();
  if (numBytes < visible) {
    throw new IOException(numBytes + " = numBytes < visible = "
        + visible + ", temp=" + temp);
  }
  // check volume
  final FsVolumeImpl v = (FsVolumeImpl)temp.getVolume();
  if (v == null) {
    throw new IOException("r.getVolume() = null, temp="  + temp);
  }
  
  // move block files to the rbw directory
  BlockPoolSlice bpslice = v.getBlockPoolSlice(b.getBlockPoolId());
  final File dest = moveBlockFiles(b.getLocalBlock(), temp.getBlockFile(), 
      bpslice.getRbwDir());
  // create RBW
  final ReplicaBeingWritten rbw = new ReplicaBeingWritten(
      blockId, numBytes, expectedGs,
      v, dest.getParentFile(), Thread.currentThread(), 0);
  rbw.setBytesAcked(visible);
  // overwrite the RBW in the volume map
  volumeMap.add(b.getBlockPoolId(), rbw);
  return rbw;
}
 

@Override // FsDatasetSpi
public synchronized ReplicaInPipeline convertTemporaryToRbw(
    final ExtendedBlock b) throws IOException {
  final long blockId = b.getBlockId();
  final long expectedGs = b.getGenerationStamp();
  final long visible = b.getNumBytes();
  LOG.info("Convert " + b + " from Temporary to RBW, visible length="
      + visible);

  final ReplicaInPipeline temp;
  {
    // get replica
    final ReplicaInfo r = volumeMap.get(b.getBlockPoolId(), blockId);
    if (r == null) {
      throw new ReplicaNotFoundException(
          ReplicaNotFoundException.NON_EXISTENT_REPLICA + b);
    }
    // check the replica's state
    if (r.getState() != ReplicaState.TEMPORARY) {
      throw new ReplicaAlreadyExistsException(
          "r.getState() != ReplicaState.TEMPORARY, r=" + r);
    }
    temp = (ReplicaInPipeline)r;
  }
  // check generation stamp
  if (temp.getGenerationStamp() != expectedGs) {
    throw new ReplicaAlreadyExistsException(
        "temp.getGenerationStamp() != expectedGs = " + expectedGs
        + ", temp=" + temp);
  }

  // TODO: check writer?
  // set writer to the current thread
  // temp.setWriter(Thread.currentThread());

  // check length
  final long numBytes = temp.getNumBytes();
  if (numBytes < visible) {
    throw new IOException(numBytes + " = numBytes < visible = "
        + visible + ", temp=" + temp);
  }
  // check volume
  final FsVolumeImpl v = (FsVolumeImpl)temp.getVolume();
  if (v == null) {
    throw new IOException("r.getVolume() = null, temp="  + temp);
  }
  
  // move block files to the rbw directory
  BlockPoolSlice bpslice = v.getBlockPoolSlice(b.getBlockPoolId());
  final File dest = moveBlockFiles(b.getLocalBlock(), temp.getBlockFile(), 
      bpslice.getRbwDir());
  // create RBW
  final ReplicaBeingWritten rbw = new ReplicaBeingWritten(
      blockId, numBytes, expectedGs,
      v, dest.getParentFile(), Thread.currentThread(), 0);
  rbw.setBytesAcked(visible);
  // overwrite the RBW in the volume map
  volumeMap.add(b.getBlockPoolId(), rbw);
  return rbw;
}
 

/**
 * 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.
 * @param useDnHostname whether DNs should connect to other DNs by hostname
 */
private void checkBlockMetaDataInfo(boolean useDnHostname) throws Exception {
  MiniDFSCluster cluster = null;

  conf.setBoolean(DFSConfigKeys.DFS_DATANODE_USE_DN_HOSTNAME, useDnHostname);
  if (useDnHostname) {
    // Since the mini cluster only listens on the loopback we have to
    // ensure the hostname used to access DNs maps to the loopback. We
    // do this by telling the DN to advertise localhost as its hostname
    // instead of the default hostname.
    conf.set(DFSConfigKeys.DFS_DATANODE_HOST_NAME_KEY, "localhost");
  }

  try {
    cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(3)
      .checkDataNodeHostConfig(true)
      .build();
    cluster.waitActive();

    //create a file
    DistributedFileSystem dfs = 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, useDnHostname);
    
    // Stop the block scanners.
    datanode.getBlockScanner().removeAllVolumeScanners();

    //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, b.getBlockId(),
        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();}
  }
}
 

/** Recover a block */
private void recoverBlock(RecoveringBlock rBlock) throws IOException {
  ExtendedBlock block = rBlock.getBlock();
  String blookPoolId = block.getBlockPoolId();
  DatanodeID[] datanodeids = rBlock.getLocations();
  List<BlockRecord> syncList = new ArrayList<BlockRecord>(datanodeids.length);
  int errorCount = 0;

  //check generation stamps
  for(DatanodeID id : datanodeids) {
    try {
      BPOfferService bpos = blockPoolManager.get(blookPoolId);
      DatanodeRegistration bpReg = bpos.bpRegistration;
      InterDatanodeProtocol datanode = bpReg.equals(id)?
          this: DataNode.createInterDataNodeProtocolProxy(id, getConf(),
              dnConf.socketTimeout, dnConf.connectToDnViaHostname);
      ReplicaRecoveryInfo info = callInitReplicaRecovery(datanode, rBlock);
      if (info != null &&
          info.getGenerationStamp() >= block.getGenerationStamp() &&
          info.getNumBytes() > 0) {
        syncList.add(new BlockRecord(id, datanode, info));
      }
    } catch (RecoveryInProgressException ripE) {
      InterDatanodeProtocol.LOG.warn(
          "Recovery for replica " + block + " on data-node " + id
          + " is already in progress. Recovery id = "
          + rBlock.getNewGenerationStamp() + " is aborted.", ripE);
      return;
    } catch (IOException e) {
      ++errorCount;
      InterDatanodeProtocol.LOG.warn(
          "Failed to obtain replica info for block (=" + block 
          + ") from datanode (=" + id + ")", e);
    }
  }

  if (errorCount == datanodeids.length) {
    throw new IOException("All datanodes failed: block=" + block
        + ", datanodeids=" + Arrays.asList(datanodeids));
  }

  syncBlock(rBlock, syncList);
}
 

@Override // FsDatasetSpi
public synchronized ReplicaHandler recoverRbw(
    ExtendedBlock b, long newGS, long minBytesRcvd, long maxBytesRcvd)
    throws IOException {
  LOG.info("Recover RBW replica " + b);

  ReplicaInfo replicaInfo = getReplicaInfo(b.getBlockPoolId(), b.getBlockId());
  
  // check the replica's state
  if (replicaInfo.getState() != ReplicaState.RBW) {
    throw new ReplicaNotFoundException(
        ReplicaNotFoundException.NON_RBW_REPLICA + replicaInfo);
  }
  ReplicaBeingWritten rbw = (ReplicaBeingWritten)replicaInfo;
  
  LOG.info("Recovering " + rbw);

  // Stop the previous writer
  rbw.stopWriter(datanode.getDnConf().getXceiverStopTimeout());
  rbw.setWriter(Thread.currentThread());

  // check generation stamp
  long replicaGenerationStamp = rbw.getGenerationStamp();
  if (replicaGenerationStamp < b.getGenerationStamp() ||
      replicaGenerationStamp > newGS) {
    throw new ReplicaNotFoundException(
        ReplicaNotFoundException.UNEXPECTED_GS_REPLICA + b +
        ". Expected GS range is [" + b.getGenerationStamp() + ", " + 
        newGS + "].");
  }
  
  // check replica length
  long bytesAcked = rbw.getBytesAcked();
  long numBytes = rbw.getNumBytes();
  if (bytesAcked < minBytesRcvd || numBytes > maxBytesRcvd){
    throw new ReplicaNotFoundException("Unmatched length replica " + 
        replicaInfo + ": BytesAcked = " + bytesAcked + 
        " BytesRcvd = " + numBytes + " are not in the range of [" + 
        minBytesRcvd + ", " + maxBytesRcvd + "].");
  }

  FsVolumeReference ref = rbw.getVolume().obtainReference();
  try {
    // Truncate the potentially corrupt portion.
    // If the source was client and the last node in the pipeline was lost,
    // any corrupt data written after the acked length can go unnoticed.
    if (numBytes > bytesAcked) {
      final File replicafile = rbw.getBlockFile();
      truncateBlock(replicafile, rbw.getMetaFile(), numBytes, bytesAcked);
      rbw.setNumBytes(bytesAcked);
      rbw.setLastChecksumAndDataLen(bytesAcked, null);
    }

    // bump the replica's generation stamp to newGS
    bumpReplicaGS(rbw, newGS);
  } catch (IOException e) {
    IOUtils.cleanup(null, ref);
    throw e;
  }
  return new ReplicaHandler(rbw, ref);
}
 

private ReplicaInfo recoverCheck(ExtendedBlock b, long newGS, 
    long expectedBlockLen) throws IOException {
  ReplicaInfo replicaInfo = getReplicaInfo(b.getBlockPoolId(), b.getBlockId());
  
  // check state
  if (replicaInfo.getState() != ReplicaState.FINALIZED &&
      replicaInfo.getState() != ReplicaState.RBW) {
    throw new ReplicaNotFoundException(
        ReplicaNotFoundException.UNFINALIZED_AND_NONRBW_REPLICA + replicaInfo);
  }

  // check generation stamp
  long replicaGenerationStamp = replicaInfo.getGenerationStamp();
  if (replicaGenerationStamp < b.getGenerationStamp() ||
      replicaGenerationStamp > newGS) {
    throw new ReplicaNotFoundException(
        ReplicaNotFoundException.UNEXPECTED_GS_REPLICA + replicaGenerationStamp
        + ". Expected GS range is [" + b.getGenerationStamp() + ", " + 
        newGS + "].");
  }
  
  // stop the previous writer before check a replica's length
  long replicaLen = replicaInfo.getNumBytes();
  if (replicaInfo.getState() == ReplicaState.RBW) {
    ReplicaBeingWritten rbw = (ReplicaBeingWritten)replicaInfo;
    // kill the previous writer
    rbw.stopWriter(datanode.getDnConf().getXceiverStopTimeout());
    rbw.setWriter(Thread.currentThread());
    // check length: bytesRcvd, bytesOnDisk, and bytesAcked should be the same
    if (replicaLen != rbw.getBytesOnDisk() 
        || replicaLen != rbw.getBytesAcked()) {
      throw new ReplicaAlreadyExistsException("RBW replica " + replicaInfo + 
          "bytesRcvd(" + rbw.getNumBytes() + "), bytesOnDisk(" + 
          rbw.getBytesOnDisk() + "), and bytesAcked(" + rbw.getBytesAcked() +
          ") are not the same.");
    }
  }
  
  // check block length
  if (replicaLen != expectedBlockLen) {
    throw new IOException("Corrupted replica " + replicaInfo + 
        " with a length of " + replicaLen + 
        " expected length is " + expectedBlockLen);
  }
  
  return replicaInfo;
}
 

@Override // FsDatasetSpi
public synchronized ReplicaHandler createRbw(
    StorageType storageType, ExtendedBlock b, boolean allowLazyPersist)
    throws IOException {
  ReplicaInfo replicaInfo = volumeMap.get(b.getBlockPoolId(),
      b.getBlockId());
  if (replicaInfo != null) {
    throw new ReplicaAlreadyExistsException("Block " + b +
    " already exists in state " + replicaInfo.getState() +
    " and thus cannot be created.");
  }
  // create a new block
  FsVolumeReference ref;
  while (true) {
    try {
      if (allowLazyPersist) {
        // First try to place the block on a transient volume.
        ref = volumes.getNextTransientVolume(b.getNumBytes());
        datanode.getMetrics().incrRamDiskBlocksWrite();
      } else {
        ref = volumes.getNextVolume(storageType, b.getNumBytes());
      }
    } catch (DiskOutOfSpaceException de) {
      if (allowLazyPersist) {
        datanode.getMetrics().incrRamDiskBlocksWriteFallback();
        allowLazyPersist = false;
        continue;
      }
      throw de;
    }
    break;
  }
  FsVolumeImpl v = (FsVolumeImpl) ref.getVolume();
  // create an rbw file to hold block in the designated volume
  File f;
  try {
    f = v.createRbwFile(b.getBlockPoolId(), b.getLocalBlock());
  } catch (IOException e) {
    IOUtils.cleanup(null, ref);
    throw e;
  }

  ReplicaBeingWritten newReplicaInfo = new ReplicaBeingWritten(b.getBlockId(), 
      b.getGenerationStamp(), v, f.getParentFile(), b.getNumBytes());
  volumeMap.add(b.getBlockPoolId(), newReplicaInfo);
  return new ReplicaHandler(newReplicaInfo, ref);
}
 

/** 
 * 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 = 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,
            tmp.getBlockId(), newlength);
        Assert.fail();
      } catch(IOException ioe) {
        System.out.println("GOOD: getting " + ioe);
      }
    }

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

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

/**
 * Get the latest metadata file correpsonding to a block
 * @param storageDir storage directory
 * @param blk the block
 * @return metadata file corresponding to the block
 */
public static File getBlockMetadataFile(File storageDir, ExtendedBlock blk) {
  return new File(DatanodeUtil.idToBlockDir(getFinalizedDir(storageDir,
      blk.getBlockPoolId()), blk.getBlockId()), blk.getBlockName() + "_" +
      blk.getGenerationStamp() + Block.METADATA_EXTENSION);
}
 

/**
 * Get the latest metadata file correpsonding to a block
 * @param storageDir storage directory
 * @param blk the block
 * @return metadata file corresponding to the block
 */
public static File getBlockMetadataFile(File storageDir, ExtendedBlock blk) {
  return new File(DatanodeUtil.idToBlockDir(getFinalizedDir(storageDir,
      blk.getBlockPoolId()), blk.getBlockId()), blk.getBlockName() + "_" +
      blk.getGenerationStamp() + Block.METADATA_EXTENSION);
}