Java ReplicaInfo.getGenerationStamp方法代码示例

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
/**
 * Bump a replica's generation stamp to a new one.
 * Its on-disk meta file name is renamed to be the new one too.
 * 
 * @param replicaInfo a replica
 * @param newGS new generation stamp
 * @throws IOException if rename fails
 */
private void bumpReplicaGS(ReplicaInfo replicaInfo, 
    long newGS) throws IOException { 
  long oldGS = replicaInfo.getGenerationStamp();
  File oldmeta = replicaInfo.getMetaFile();
  replicaInfo.setGenerationStamp(newGS);
  File newmeta = replicaInfo.getMetaFile();

  // rename meta file to new GS
  if (LOG.isDebugEnabled()) {
    LOG.debug("Renaming " + oldmeta + " to " + newmeta);
  }
  try {
    NativeIO.renameTo(oldmeta, newmeta);
  } catch (IOException e) {
    replicaInfo.setGenerationStamp(oldGS); // restore old GS
    throw new IOException("Block " + replicaInfo + " reopen failed. " +
                          " Unable to move meta file  " + oldmeta +
                          " to " + newmeta, e);
  }
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
/**
 * Remove the replica's meta information from the map that matches
 * the input block's id and generation stamp
 * @param bpid block pool id
 * @param block block with its id as the key
 * @return the removed replica's meta information
 * @throws IllegalArgumentException if the input block is null
 */
ReplicaInfo remove(String bpid, Block block) {
  checkBlockPool(bpid);
  checkBlock(block);
  synchronized(mutex) {
    Map<Long, ReplicaInfo> m = map.get(bpid);
    if (m != null) {
      Long key = Long.valueOf(block.getBlockId());
      ReplicaInfo replicaInfo = m.get(key);
      if (replicaInfo != null &&
          block.getGenerationStamp() == replicaInfo.getGenerationStamp()) {
        return m.remove(key);
      } 
    }
  }
  
  return null;
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
/**
 * Remove the replica's meta information from the map that matches
 * the input block's id and generation stamp
 * @param bpid block pool id
 * @param block block with its id as the key
 * @return the removed replica's meta information
 * @throws IllegalArgumentException if the input block is null
 */
ReplicaInfo remove(String bpid, Block block) {
  checkBlockPool(bpid);
  checkBlock(block);
  synchronized(mutex) {
    LightWeightResizableGSet<Block, ReplicaInfo> m = map.get(bpid);
    if (m != null) {
      ReplicaInfo replicaInfo = m.get(block);
      if (replicaInfo != null &&
          block.getGenerationStamp() == replicaInfo.getGenerationStamp()) {
        return m.remove(block);
      }
    }
  }
  
  return null;
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
@Override // FsDatasetSpi
public synchronized ReplicaInPipeline createTemporary(StorageType storageType,
    ExtendedBlock b) throws IOException {
  ReplicaInfo replicaInfo = volumeMap.get(b.getBlockPoolId(), b.getBlockId());
  if (replicaInfo != null) {
    if (replicaInfo.getGenerationStamp() < b.getGenerationStamp()
        && replicaInfo instanceof ReplicaInPipeline) {
      // Stop the previous writer
      ((ReplicaInPipeline)replicaInfo)
                    .stopWriter(datanode.getDnConf().getXceiverStopTimeout());
      invalidate(b.getBlockPoolId(), new Block[]{replicaInfo});
    } else {
      throw new ReplicaAlreadyExistsException("Block " + b +
          " already exists in state " + replicaInfo.getState() +
          " and thus cannot be created.");
    }
  }
  
  FsVolumeImpl v = volumes.getNextVolume(storageType, b.getNumBytes());
  // create a temporary file to hold block in the designated volume
  File f = v.createTmpFile(b.getBlockPoolId(), b.getLocalBlock());
  ReplicaInPipeline newReplicaInfo = new ReplicaInPipeline(b.getBlockId(), 
      b.getGenerationStamp(), v, f.getParentFile(), 0);
  volumeMap.add(b.getBlockPoolId(), newReplicaInfo);
  return newReplicaInfo;
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
@VisibleForTesting
static ReplicaInfo selectReplicaToDelete(final ReplicaInfo replica1,
    final ReplicaInfo replica2) {
  ReplicaInfo replicaToKeep;
  ReplicaInfo replicaToDelete;

  // it's the same block so don't ever delete it, even if GS or size
  // differs.  caller should keep the one it just discovered on disk
  if (replica1.getBlockFile().equals(replica2.getBlockFile())) {
    return null;
  }
  if (replica1.getGenerationStamp() != replica2.getGenerationStamp()) {
    replicaToKeep = replica1.getGenerationStamp() > replica2.getGenerationStamp()
        ? replica1 : replica2;
  } else if (replica1.getNumBytes() != replica2.getNumBytes()) {
    replicaToKeep = replica1.getNumBytes() > replica2.getNumBytes() ?
        replica1 : replica2;
  } else if (replica1.getVolume().isTransientStorage() &&
             !replica2.getVolume().isTransientStorage()) {
    replicaToKeep = replica2;
  } else {
    replicaToKeep = replica1;
  }

  replicaToDelete = (replicaToKeep == replica1) ? replica2 : replica1;

  if (LOG.isDebugEnabled()) {
    LOG.debug("resolveDuplicateReplicas decide to keep " + replicaToKeep
        + ".  Will try to delete " + replicaToDelete);
  }
  return replicaToDelete;
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
/**
 * Get the meta information of the replica that matches both block id 
 * and generation stamp
 * @param bpid block pool id
 * @param block block with its id as the key
 * @return the replica's meta information
 * @throws IllegalArgumentException if the input block or block pool is null
 */
ReplicaInfo get(String bpid, Block block) {
  checkBlockPool(bpid);
  checkBlock(block);
  ReplicaInfo replicaInfo = get(bpid, block.getBlockId());
  if (replicaInfo != null && 
      block.getGenerationStamp() == replicaInfo.getGenerationStamp()) {
    return replicaInfo;
  }
  return null;
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
@Override // FsDatasetSpi
public synchronized ReplicaHandler createTemporary(
    StorageType storageType, ExtendedBlock b) throws IOException {
  ReplicaInfo replicaInfo = volumeMap.get(b.getBlockPoolId(), b.getBlockId());
  if (replicaInfo != null) {
    if (replicaInfo.getGenerationStamp() < b.getGenerationStamp()
        && replicaInfo instanceof ReplicaInPipeline) {
      // Stop the previous writer
      ((ReplicaInPipeline)replicaInfo)
                    .stopWriter(datanode.getDnConf().getXceiverStopTimeout());
      invalidate(b.getBlockPoolId(), new Block[]{replicaInfo});
    } else {
      throw new ReplicaAlreadyExistsException("Block " + b +
          " already exists in state " + replicaInfo.getState() +
          " and thus cannot be created.");
    }
  }

  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);
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
static ReplicaInfo selectReplicaToDelete(final ReplicaInfo replica1,
    final ReplicaInfo replica2) {
  ReplicaInfo replicaToKeep;
  ReplicaInfo replicaToDelete;

  // it's the same block so don't ever delete it, even if GS or size
  // differs.  caller should keep the one it just discovered on disk
  if (replica1.getBlockFile().equals(replica2.getBlockFile())) {
    return null;
  }
  if (replica1.getGenerationStamp() != replica2.getGenerationStamp()) {
    replicaToKeep = replica1.getGenerationStamp() > replica2.getGenerationStamp()
        ? replica1 : replica2;
  } else if (replica1.getNumBytes() != replica2.getNumBytes()) {
    replicaToKeep = replica1.getNumBytes() > replica2.getNumBytes() ?
        replica1 : replica2;
  } else if (replica1.getVolume().isTransientStorage() &&
             !replica2.getVolume().isTransientStorage()) {
    replicaToKeep = replica2;
  } else {
    replicaToKeep = replica1;
  }

  replicaToDelete = (replicaToKeep == replica1) ? replica2 : replica1;

  if (LOG.isDebugEnabled()) {
    LOG.debug("resolveDuplicateReplicas decide to keep " + replicaToKeep
        + ".  Will try to delete " + replicaToDelete);
  }
  return replicaToDelete;
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
/**
 * Move block files from one storage to another storage.
 * @return Returns the Old replicaInfo
 * @throws IOException
 */
@Override
public ReplicaInfo moveBlockAcrossStorage(ExtendedBlock block,
    StorageType targetStorageType) throws IOException {
  ReplicaInfo replicaInfo = getReplicaInfo(block);
  if (replicaInfo.getState() != ReplicaState.FINALIZED) {
    throw new ReplicaNotFoundException(
        ReplicaNotFoundException.UNFINALIZED_REPLICA + block);
  }
  if (replicaInfo.getNumBytes() != block.getNumBytes()) {
    throw new IOException("Corrupted replica " + replicaInfo
        + " with a length of " + replicaInfo.getNumBytes()
        + " expected length is " + block.getNumBytes());
  }
  if (replicaInfo.getVolume().getStorageType() == targetStorageType) {
    throw new ReplicaAlreadyExistsException("Replica " + replicaInfo
        + " already exists on storage " + targetStorageType);
  }

  if (replicaInfo.isOnTransientStorage()) {
    // Block movement from RAM_DISK will be done by LazyPersist mechanism
    throw new IOException("Replica " + replicaInfo
        + " cannot be moved from storageType : "
        + replicaInfo.getVolume().getStorageType());
  }

  try (FsVolumeReference volumeRef = volumes.getNextVolume(
      targetStorageType, block.getNumBytes())) {
    File oldBlockFile = replicaInfo.getBlockFile();
    File oldMetaFile = replicaInfo.getMetaFile();
    FsVolumeImpl targetVolume = (FsVolumeImpl) volumeRef.getVolume();
    // Copy files to temp dir first
    File[] blockFiles = copyBlockFiles(block.getBlockId(),
        block.getGenerationStamp(), oldMetaFile, oldBlockFile,
        targetVolume.getTmpDir(block.getBlockPoolId()),
        replicaInfo.isOnTransientStorage());

    ReplicaInfo newReplicaInfo = new ReplicaInPipeline(
        replicaInfo.getBlockId(), replicaInfo.getGenerationStamp(),
        targetVolume, blockFiles[0].getParentFile(), 0);
    newReplicaInfo.setNumBytes(blockFiles[1].length());
    // Finalize the copied files
    newReplicaInfo = finalizeReplica(block.getBlockPoolId(), newReplicaInfo);

    removeOldReplica(replicaInfo, newReplicaInfo, oldBlockFile, oldMetaFile,
        oldBlockFile.length(), oldMetaFile.length(), block.getBlockPoolId());
  }

  // Replace the old block if any to reschedule the scanning.
  return replicaInfo;
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
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;
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
@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);
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
/**
 * Asynchronously attempts to cache a single block via {@link FsDatasetCache}.
 */
private void cacheBlock(String bpid, long blockId) {
  FsVolumeImpl volume;
  String blockFileName;
  long length, genstamp;
  Executor volumeExecutor;

  synchronized (this) {
    ReplicaInfo info = volumeMap.get(bpid, blockId);
    boolean success = false;
    try {
      if (info == null) {
        LOG.warn("Failed to cache block with id " + blockId + ", pool " +
            bpid + ": ReplicaInfo not found.");
        return;
      }
      if (info.getState() != ReplicaState.FINALIZED) {
        LOG.warn("Failed to cache block with id " + blockId + ", pool " +
            bpid + ": replica is not finalized; it is in state " +
            info.getState());
        return;
      }
      try {
        volume = (FsVolumeImpl)info.getVolume();
        if (volume == null) {
          LOG.warn("Failed to cache block with id " + blockId + ", pool " +
              bpid + ": volume not found.");
          return;
        }
      } catch (ClassCastException e) {
        LOG.warn("Failed to cache block with id " + blockId +
            ": volume was not an instance of FsVolumeImpl.");
        return;
      }
      if (volume.isTransientStorage()) {
        LOG.warn("Caching not supported on block with id " + blockId +
            " since the volume is backed by RAM.");
        return;
      }
      success = true;
    } finally {
      if (!success) {
        cacheManager.numBlocksFailedToCache.incrementAndGet();
      }
    }
    blockFileName = info.getBlockFile().getAbsolutePath();
    length = info.getVisibleLength();
    genstamp = info.getGenerationStamp();
    volumeExecutor = volume.getCacheExecutor();
  }
  cacheManager.cacheBlock(blockId, bpid, 
      blockFileName, length, genstamp, volumeExecutor);
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
/**
 * Move block files from one storage to another storage.
 * @return Returns the Old replicaInfo
 * @throws IOException
 */
@Override
public ReplicaInfo moveBlockAcrossStorage(ExtendedBlock block,
    StorageType targetStorageType) throws IOException {
  ReplicaInfo replicaInfo = getReplicaInfo(block);
  if (replicaInfo.getState() != ReplicaState.FINALIZED) {
    throw new ReplicaNotFoundException(
        ReplicaNotFoundException.UNFINALIZED_REPLICA + block);
  }
  if (replicaInfo.getNumBytes() != block.getNumBytes()) {
    throw new IOException("Corrupted replica " + replicaInfo
        + " with a length of " + replicaInfo.getNumBytes()
        + " expected length is " + block.getNumBytes());
  }
  if (replicaInfo.getVolume().getStorageType() == targetStorageType) {
    throw new ReplicaAlreadyExistsException("Replica " + replicaInfo
        + " already exists on storage " + targetStorageType);
  }

  if (replicaInfo.isOnTransientStorage()) {
    // Block movement from RAM_DISK will be done by LazyPersist mechanism
    throw new IOException("Replica " + replicaInfo
        + " cannot be moved from storageType : "
        + replicaInfo.getVolume().getStorageType());
  }

  try (FsVolumeReference volumeRef = volumes.getNextVolume(
      targetStorageType, block.getNumBytes())) {
    File oldBlockFile = replicaInfo.getBlockFile();
    File oldMetaFile = replicaInfo.getMetaFile();
    FsVolumeImpl targetVolume = (FsVolumeImpl) volumeRef.getVolume();
    // Copy files to temp dir first
    File[] blockFiles = copyBlockFiles(block.getBlockId(),
        block.getGenerationStamp(), oldMetaFile, oldBlockFile,
        targetVolume.getTmpDir(block.getBlockPoolId()),
        replicaInfo.isOnTransientStorage(), smallBufferSize, conf);

    ReplicaInfo newReplicaInfo = new ReplicaInPipeline(
        replicaInfo.getBlockId(), replicaInfo.getGenerationStamp(),
        targetVolume, blockFiles[0].getParentFile(), 0);
    newReplicaInfo.setNumBytes(blockFiles[1].length());
    // Finalize the copied files
    newReplicaInfo = finalizeReplica(block.getBlockPoolId(), newReplicaInfo);

    removeOldReplica(replicaInfo, newReplicaInfo, oldBlockFile, oldMetaFile,
        oldBlockFile.length(), oldMetaFile.length(), block.getBlockPoolId());
  }

  // Replace the old block if any to reschedule the scanning.
  return replicaInfo;
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
@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(), b.getLocalBlock().getNumBytes());
        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);
}
 

import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo; //导入方法依赖的package包/类
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();
    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;
}