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Posted to common-commits@hadoop.apache.org by zh...@apache.org on 2015/09/30 17:41:05 UTC

[05/58] [abbrv] hadoop git commit: HDFS-8053. Move DFSIn/OutputStream and related classes to hadoop-hdfs-client. Contributed by Mingliang Liu.

http://git-wip-us.apache.org/repos/asf/hadoop/blob/bf37d3d8/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSClient.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
deleted file mode 100644
index 5bd48af..0000000
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
+++ /dev/null
@@ -1,3141 +0,0 @@
-/**
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.apache.hadoop.hdfs;
-
-import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.HADOOP_SECURITY_CRYPTO_CODEC_CLASSES_KEY_PREFIX;
-import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_CACHE_DROP_BEHIND_READS;
-import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_CACHE_DROP_BEHIND_WRITES;
-import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_CACHE_READAHEAD;
-import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_CONTEXT;
-import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_CONTEXT_DEFAULT;
-
-import java.io.BufferedOutputStream;
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.net.InetAddress;
-import java.net.InetSocketAddress;
-import java.net.Socket;
-import java.net.SocketAddress;
-import java.net.URI;
-import java.net.UnknownHostException;
-import java.security.GeneralSecurityException;
-import java.util.ArrayList;
-import java.util.EnumSet;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Random;
-import java.util.concurrent.SynchronousQueue;
-import java.util.concurrent.ThreadLocalRandom;
-import java.util.concurrent.ThreadPoolExecutor;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicInteger;
-
-import javax.net.SocketFactory;
-
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-import org.apache.hadoop.HadoopIllegalArgumentException;
-import org.apache.hadoop.classification.InterfaceAudience;
-import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.crypto.CipherSuite;
-import org.apache.hadoop.crypto.CryptoCodec;
-import org.apache.hadoop.crypto.CryptoInputStream;
-import org.apache.hadoop.crypto.CryptoOutputStream;
-import org.apache.hadoop.crypto.CryptoProtocolVersion;
-import org.apache.hadoop.crypto.key.KeyProvider;
-import org.apache.hadoop.crypto.key.KeyProvider.KeyVersion;
-import org.apache.hadoop.crypto.key.KeyProviderCryptoExtension;
-import org.apache.hadoop.crypto.key.KeyProviderCryptoExtension.EncryptedKeyVersion;
-import org.apache.hadoop.fs.BlockLocation;
-import org.apache.hadoop.fs.CacheFlag;
-import org.apache.hadoop.fs.ContentSummary;
-import org.apache.hadoop.fs.CreateFlag;
-import org.apache.hadoop.fs.FileAlreadyExistsException;
-import org.apache.hadoop.fs.FileEncryptionInfo;
-import org.apache.hadoop.fs.FileSystem;
-import org.apache.hadoop.fs.FsServerDefaults;
-import org.apache.hadoop.fs.FsStatus;
-import org.apache.hadoop.fs.HdfsBlockLocation;
-import org.apache.hadoop.fs.InvalidPathException;
-import org.apache.hadoop.fs.MD5MD5CRC32CastagnoliFileChecksum;
-import org.apache.hadoop.fs.MD5MD5CRC32FileChecksum;
-import org.apache.hadoop.fs.MD5MD5CRC32GzipFileChecksum;
-import org.apache.hadoop.fs.Options;
-import org.apache.hadoop.fs.Options.ChecksumOpt;
-import org.apache.hadoop.fs.ParentNotDirectoryException;
-import org.apache.hadoop.fs.Path;
-import org.apache.hadoop.fs.RemoteIterator;
-import org.apache.hadoop.fs.StorageType;
-import org.apache.hadoop.fs.UnresolvedLinkException;
-import org.apache.hadoop.fs.XAttr;
-import org.apache.hadoop.fs.XAttrSetFlag;
-import org.apache.hadoop.fs.permission.AclEntry;
-import org.apache.hadoop.fs.permission.AclStatus;
-import org.apache.hadoop.fs.permission.FsAction;
-import org.apache.hadoop.fs.permission.FsPermission;
-import org.apache.hadoop.hdfs.NameNodeProxiesClient.ProxyAndInfo;
-import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
-import org.apache.hadoop.hdfs.client.HdfsDataInputStream;
-import org.apache.hadoop.hdfs.client.HdfsDataOutputStream;
-import org.apache.hadoop.hdfs.client.impl.DfsClientConf;
-import org.apache.hadoop.hdfs.client.impl.LeaseRenewer;
-import org.apache.hadoop.hdfs.net.Peer;
-import org.apache.hadoop.hdfs.protocol.AclException;
-import org.apache.hadoop.hdfs.protocol.BlockStoragePolicy;
-import org.apache.hadoop.hdfs.protocol.CacheDirectiveEntry;
-import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
-import org.apache.hadoop.hdfs.protocol.CacheDirectiveIterator;
-import org.apache.hadoop.hdfs.protocol.CachePoolEntry;
-import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
-import org.apache.hadoop.hdfs.protocol.CachePoolIterator;
-import org.apache.hadoop.hdfs.protocol.ClientProtocol;
-import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
-import org.apache.hadoop.hdfs.protocol.DSQuotaExceededException;
-import org.apache.hadoop.hdfs.protocol.DatanodeID;
-import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
-import org.apache.hadoop.hdfs.protocol.DirectoryListing;
-import org.apache.hadoop.hdfs.protocol.EncryptionZone;
-import org.apache.hadoop.hdfs.protocol.EncryptionZoneIterator;
-import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
-import org.apache.hadoop.hdfs.protocol.HdfsConstants;
-import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
-import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
-import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
-import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
-import org.apache.hadoop.hdfs.protocol.LastBlockWithStatus;
-import org.apache.hadoop.hdfs.protocol.LocatedBlock;
-import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
-import org.apache.hadoop.hdfs.protocol.NSQuotaExceededException;
-import org.apache.hadoop.hdfs.protocol.QuotaByStorageTypeExceededException;
-import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
-import org.apache.hadoop.hdfs.protocol.SnapshotAccessControlException;
-import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
-import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
-import org.apache.hadoop.hdfs.protocol.UnresolvedPathException;
-import org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtoUtil;
-import org.apache.hadoop.hdfs.protocol.datatransfer.IOStreamPair;
-import org.apache.hadoop.hdfs.protocol.datatransfer.Op;
-import org.apache.hadoop.hdfs.protocol.datatransfer.ReplaceDatanodeOnFailure;
-import org.apache.hadoop.hdfs.protocol.datatransfer.Sender;
-import org.apache.hadoop.hdfs.protocol.datatransfer.TrustedChannelResolver;
-import org.apache.hadoop.hdfs.protocol.datatransfer.sasl.DataEncryptionKeyFactory;
-import org.apache.hadoop.hdfs.protocol.datatransfer.sasl.DataTransferSaslUtil;
-import org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient;
-import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.BlockOpResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.OpBlockChecksumResponseProto;
-import org.apache.hadoop.hdfs.protocolPB.PBHelperClient;
-import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
-import org.apache.hadoop.hdfs.security.token.block.DataEncryptionKey;
-import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
-import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
-import org.apache.hadoop.hdfs.server.datanode.CachingStrategy;
-import org.apache.hadoop.hdfs.server.namenode.SafeModeException;
-import org.apache.hadoop.hdfs.server.protocol.DatanodeStorageReport;
-import org.apache.hadoop.io.DataOutputBuffer;
-import org.apache.hadoop.io.EnumSetWritable;
-import org.apache.hadoop.io.IOUtils;
-import org.apache.hadoop.io.MD5Hash;
-import org.apache.hadoop.io.Text;
-import org.apache.hadoop.io.retry.LossyRetryInvocationHandler;
-import org.apache.hadoop.ipc.RPC;
-import org.apache.hadoop.ipc.RemoteException;
-import org.apache.hadoop.net.DNS;
-import org.apache.hadoop.net.NetUtils;
-import org.apache.hadoop.security.AccessControlException;
-import org.apache.hadoop.security.UserGroupInformation;
-import org.apache.hadoop.security.token.SecretManager.InvalidToken;
-import org.apache.hadoop.security.token.Token;
-import org.apache.hadoop.security.token.TokenRenewer;
-import org.apache.hadoop.tracing.SpanReceiverHost;
-import org.apache.hadoop.tracing.TraceUtils;
-import org.apache.hadoop.util.Daemon;
-import org.apache.hadoop.util.DataChecksum;
-import org.apache.hadoop.util.DataChecksum.Type;
-import org.apache.hadoop.util.Progressable;
-import org.apache.hadoop.util.Time;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.SamplerBuilder;
-import org.apache.htrace.Span;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
-
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Joiner;
-import com.google.common.base.Preconditions;
-import com.google.common.collect.Lists;
-import com.google.common.net.InetAddresses;
-
-/********************************************************
- * DFSClient can connect to a Hadoop Filesystem and 
- * perform basic file tasks.  It uses the ClientProtocol
- * to communicate with a NameNode daemon, and connects 
- * directly to DataNodes to read/write block data.
- *
- * Hadoop DFS users should obtain an instance of 
- * DistributedFileSystem, which uses DFSClient to handle
- * filesystem tasks.
- *
- ********************************************************/
-@InterfaceAudience.Private
-public class DFSClient implements java.io.Closeable, RemotePeerFactory,
-    DataEncryptionKeyFactory {
-  public static final Log LOG = LogFactory.getLog(DFSClient.class);
-  public static final long SERVER_DEFAULTS_VALIDITY_PERIOD = 60 * 60 * 1000L; // 1 hour
-
-  private final Configuration conf;
-  private final DfsClientConf dfsClientConf;
-  final ClientProtocol namenode;
-  /* The service used for delegation tokens */
-  private Text dtService;
-
-  final UserGroupInformation ugi;
-  volatile boolean clientRunning = true;
-  volatile long lastLeaseRenewal;
-  private volatile FsServerDefaults serverDefaults;
-  private volatile long serverDefaultsLastUpdate;
-  final String clientName;
-  final SocketFactory socketFactory;
-  final ReplaceDatanodeOnFailure dtpReplaceDatanodeOnFailure;
-  final FileSystem.Statistics stats;
-  private final String authority;
-  private final Random r = new Random();
-  private SocketAddress[] localInterfaceAddrs;
-  private DataEncryptionKey encryptionKey;
-  final SaslDataTransferClient saslClient;
-  private final CachingStrategy defaultReadCachingStrategy;
-  private final CachingStrategy defaultWriteCachingStrategy;
-  private final ClientContext clientContext;
-
-  private static final DFSHedgedReadMetrics HEDGED_READ_METRIC =
-      new DFSHedgedReadMetrics();
-  private static ThreadPoolExecutor HEDGED_READ_THREAD_POOL;
-  private final Sampler<?> traceSampler;
-  private final int smallBufferSize;
-
-  public DfsClientConf getConf() {
-    return dfsClientConf;
-  }
-
-  Configuration getConfiguration() {
-    return conf;
-  }
-
-  /**
-   * A map from file names to {@link DFSOutputStream} objects
-   * that are currently being written by this client.
-   * Note that a file can only be written by a single client.
-   */
-  private final Map<Long, DFSOutputStream> filesBeingWritten
-      = new HashMap<Long, DFSOutputStream>();
-
-  /**
-   * Same as this(NameNode.getNNAddress(conf), conf);
-   * @see #DFSClient(InetSocketAddress, Configuration)
-   * @deprecated Deprecated at 0.21
-   */
-  @Deprecated
-  public DFSClient(Configuration conf) throws IOException {
-    this(DFSUtilClient.getNNAddress(conf), conf);
-  }
-  
-  public DFSClient(InetSocketAddress address, Configuration conf) throws IOException {
-    this(DFSUtilClient.getNNUri(address), conf);
-  }
-
-  /**
-   * Same as this(nameNodeUri, conf, null);
-   * @see #DFSClient(URI, Configuration, FileSystem.Statistics)
-   */
-  public DFSClient(URI nameNodeUri, Configuration conf
-      ) throws IOException {
-    this(nameNodeUri, conf, null);
-  }
-
-  /**
-   * Same as this(nameNodeUri, null, conf, stats);
-   * @see #DFSClient(URI, ClientProtocol, Configuration, FileSystem.Statistics) 
-   */
-  public DFSClient(URI nameNodeUri, Configuration conf,
-                   FileSystem.Statistics stats)
-    throws IOException {
-    this(nameNodeUri, null, conf, stats);
-  }
-  
-  /** 
-   * Create a new DFSClient connected to the given nameNodeUri or rpcNamenode.
-   * If HA is enabled and a positive value is set for
-   * {@link HdfsClientConfigKeys#DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY}
-   * in the configuration, the DFSClient will use
-   * {@link LossyRetryInvocationHandler} as its RetryInvocationHandler.
-   * Otherwise one of nameNodeUri or rpcNamenode must be null.
-   */
-  @VisibleForTesting
-  public DFSClient(URI nameNodeUri, ClientProtocol rpcNamenode,
-      Configuration conf, FileSystem.Statistics stats)
-    throws IOException {
-    SpanReceiverHost.get(conf, HdfsClientConfigKeys.DFS_CLIENT_HTRACE_PREFIX);
-    traceSampler = new SamplerBuilder(TraceUtils.
-        wrapHadoopConf(HdfsClientConfigKeys.DFS_CLIENT_HTRACE_PREFIX, conf))
-        .build();
-    // Copy only the required DFSClient configuration
-    this.dfsClientConf = new DfsClientConf(conf);
-    this.conf = conf;
-    this.stats = stats;
-    this.socketFactory = NetUtils.getSocketFactory(conf, ClientProtocol.class);
-    this.dtpReplaceDatanodeOnFailure = ReplaceDatanodeOnFailure.get(conf);
-    this.smallBufferSize = DFSUtil.getSmallBufferSize(conf);
-
-    this.ugi = UserGroupInformation.getCurrentUser();
-    
-    this.authority = nameNodeUri == null? "null": nameNodeUri.getAuthority();
-    this.clientName = "DFSClient_" + dfsClientConf.getTaskId() + "_" + 
-        ThreadLocalRandom.current().nextInt()  + "_" +
-        Thread.currentThread().getId();
-    int numResponseToDrop = conf.getInt(
-        HdfsClientConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY,
-        HdfsClientConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_DEFAULT);
-    ProxyAndInfo<ClientProtocol> proxyInfo = null;
-    AtomicBoolean nnFallbackToSimpleAuth = new AtomicBoolean(false);
-    if (numResponseToDrop > 0) {
-      // This case is used for testing.
-      LOG.warn(HdfsClientConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY
-          + " is set to " + numResponseToDrop
-          + ", this hacked client will proactively drop responses");
-      proxyInfo = NameNodeProxiesClient.createProxyWithLossyRetryHandler(conf,
-          nameNodeUri, ClientProtocol.class, numResponseToDrop,
-          nnFallbackToSimpleAuth);
-    }
-    
-    if (proxyInfo != null) {
-      this.dtService = proxyInfo.getDelegationTokenService();
-      this.namenode = proxyInfo.getProxy();
-    } else if (rpcNamenode != null) {
-      // This case is used for testing.
-      Preconditions.checkArgument(nameNodeUri == null);
-      this.namenode = rpcNamenode;
-      dtService = null;
-    } else {
-      Preconditions.checkArgument(nameNodeUri != null,
-          "null URI");
-      proxyInfo = NameNodeProxiesClient.createProxyWithClientProtocol(conf,
-          nameNodeUri, nnFallbackToSimpleAuth);
-      this.dtService = proxyInfo.getDelegationTokenService();
-      this.namenode = proxyInfo.getProxy();
-    }
-
-    String localInterfaces[] =
-      conf.getTrimmedStrings(HdfsClientConfigKeys.DFS_CLIENT_LOCAL_INTERFACES);
-    localInterfaceAddrs = getLocalInterfaceAddrs(localInterfaces);
-    if (LOG.isDebugEnabled() && 0 != localInterfaces.length) {
-      LOG.debug("Using local interfaces [" +
-      Joiner.on(',').join(localInterfaces)+ "] with addresses [" +
-      Joiner.on(',').join(localInterfaceAddrs) + "]");
-    }
-    
-    Boolean readDropBehind = (conf.get(DFS_CLIENT_CACHE_DROP_BEHIND_READS) == null) ?
-        null : conf.getBoolean(DFS_CLIENT_CACHE_DROP_BEHIND_READS, false);
-    Long readahead = (conf.get(DFS_CLIENT_CACHE_READAHEAD) == null) ?
-        null : conf.getLong(DFS_CLIENT_CACHE_READAHEAD, 0);
-    Boolean writeDropBehind = (conf.get(DFS_CLIENT_CACHE_DROP_BEHIND_WRITES) == null) ?
-        null : conf.getBoolean(DFS_CLIENT_CACHE_DROP_BEHIND_WRITES, false);
-    this.defaultReadCachingStrategy =
-        new CachingStrategy(readDropBehind, readahead);
-    this.defaultWriteCachingStrategy =
-        new CachingStrategy(writeDropBehind, readahead);
-    this.clientContext = ClientContext.get(
-        conf.get(DFS_CLIENT_CONTEXT, DFS_CLIENT_CONTEXT_DEFAULT),
-        dfsClientConf);
-
-    if (dfsClientConf.getHedgedReadThreadpoolSize() > 0) {
-      this.initThreadsNumForHedgedReads(dfsClientConf.getHedgedReadThreadpoolSize());
-    }
-    this.saslClient = new SaslDataTransferClient(
-      conf, DataTransferSaslUtil.getSaslPropertiesResolver(conf),
-      TrustedChannelResolver.getInstance(conf), nnFallbackToSimpleAuth);
-  }
-  
-  /**
-   * Return the socket addresses to use with each configured
-   * local interface. Local interfaces may be specified by IP
-   * address, IP address range using CIDR notation, interface
-   * name (e.g. eth0) or sub-interface name (e.g. eth0:0).
-   * The socket addresses consist of the IPs for the interfaces
-   * and the ephemeral port (port 0). If an IP, IP range, or
-   * interface name matches an interface with sub-interfaces
-   * only the IP of the interface is used. Sub-interfaces can
-   * be used by specifying them explicitly (by IP or name).
-   * 
-   * @return SocketAddresses for the configured local interfaces,
-   *    or an empty array if none are configured
-   * @throws UnknownHostException if a given interface name is invalid
-   */
-  private static SocketAddress[] getLocalInterfaceAddrs(
-      String interfaceNames[]) throws UnknownHostException {
-    List<SocketAddress> localAddrs = new ArrayList<SocketAddress>();
-    for (String interfaceName : interfaceNames) {
-      if (InetAddresses.isInetAddress(interfaceName)) {
-        localAddrs.add(new InetSocketAddress(interfaceName, 0));
-      } else if (NetUtils.isValidSubnet(interfaceName)) {
-        for (InetAddress addr : NetUtils.getIPs(interfaceName, false)) {
-          localAddrs.add(new InetSocketAddress(addr, 0));
-        }
-      } else {
-        for (String ip : DNS.getIPs(interfaceName, false)) {
-          localAddrs.add(new InetSocketAddress(ip, 0));
-        }
-      }
-    }
-    return localAddrs.toArray(new SocketAddress[localAddrs.size()]);
-  }
-
-  /**
-   * Select one of the configured local interfaces at random. We use a random
-   * interface because other policies like round-robin are less effective
-   * given that we cache connections to datanodes.
-   *
-   * @return one of the local interface addresses at random, or null if no
-   *    local interfaces are configured
-   */
-  SocketAddress getRandomLocalInterfaceAddr() {
-    if (localInterfaceAddrs.length == 0) {
-      return null;
-    }
-    final int idx = r.nextInt(localInterfaceAddrs.length);
-    final SocketAddress addr = localInterfaceAddrs[idx];
-    if (LOG.isDebugEnabled()) {
-      LOG.debug("Using local interface " + addr);
-    }
-    return addr;
-  }
-
-  /**
-   * Return the timeout that clients should use when writing to datanodes.
-   * @param numNodes the number of nodes in the pipeline.
-   */
-  int getDatanodeWriteTimeout(int numNodes) {
-    final int t = dfsClientConf.getDatanodeSocketWriteTimeout();
-    return t > 0? t + HdfsConstants.WRITE_TIMEOUT_EXTENSION*numNodes: 0;
-  }
-
-  int getDatanodeReadTimeout(int numNodes) {
-    final int t = dfsClientConf.getSocketTimeout();
-    return t > 0? HdfsConstants.READ_TIMEOUT_EXTENSION*numNodes + t: 0;
-  }
-  
-  @VisibleForTesting
-  public String getClientName() {
-    return clientName;
-  }
-
-  void checkOpen() throws IOException {
-    if (!clientRunning) {
-      IOException result = new IOException("Filesystem closed");
-      throw result;
-    }
-  }
-
-  /** Return the lease renewer instance. The renewer thread won't start
-   *  until the first output stream is created. The same instance will
-   *  be returned until all output streams are closed.
-   */
-  public LeaseRenewer getLeaseRenewer() throws IOException {
-      return LeaseRenewer.getInstance(authority, ugi, this);
-  }
-
-  /** Get a lease and start automatic renewal */
-  private void beginFileLease(final long inodeId, final DFSOutputStream out)
-      throws IOException {
-    getLeaseRenewer().put(inodeId, out, this);
-  }
-
-  /** Stop renewal of lease for the file. */
-  void endFileLease(final long inodeId) throws IOException {
-    getLeaseRenewer().closeFile(inodeId, this);
-  }
-    
-
-  /** Put a file. Only called from LeaseRenewer, where proper locking is
-   *  enforced to consistently update its local dfsclients array and 
-   *  client's filesBeingWritten map.
-   */
-  public void putFileBeingWritten(final long inodeId, final DFSOutputStream out) {
-    synchronized(filesBeingWritten) {
-      filesBeingWritten.put(inodeId, out);
-      // update the last lease renewal time only when there was no
-      // writes. once there is one write stream open, the lease renewer
-      // thread keeps it updated well with in anyone's expiration time.
-      if (lastLeaseRenewal == 0) {
-        updateLastLeaseRenewal();
-      }
-    }
-  }
-
-  /** Remove a file. Only called from LeaseRenewer. */
-  public void removeFileBeingWritten(final long inodeId) {
-    synchronized(filesBeingWritten) {
-      filesBeingWritten.remove(inodeId);
-      if (filesBeingWritten.isEmpty()) {
-        lastLeaseRenewal = 0;
-      }
-    }
-  }
-
-  /** Is file-being-written map empty? */
-  public boolean isFilesBeingWrittenEmpty() {
-    synchronized(filesBeingWritten) {
-      return filesBeingWritten.isEmpty();
-    }
-  }
-  
-  /** @return true if the client is running */
-  public boolean isClientRunning() {
-    return clientRunning;
-  }
-
-  long getLastLeaseRenewal() {
-    return lastLeaseRenewal;
-  }
-
-  void updateLastLeaseRenewal() {
-    synchronized(filesBeingWritten) {
-      if (filesBeingWritten.isEmpty()) {
-        return;
-      }
-      lastLeaseRenewal = Time.monotonicNow();
-    }
-  }
-
-  /**
-   * Renew leases.
-   * @return true if lease was renewed. May return false if this
-   * client has been closed or has no files open.
-   **/
-  public boolean renewLease() throws IOException {
-    if (clientRunning && !isFilesBeingWrittenEmpty()) {
-      try {
-        namenode.renewLease(clientName);
-        updateLastLeaseRenewal();
-        return true;
-      } catch (IOException e) {
-        // Abort if the lease has already expired. 
-        final long elapsed = Time.monotonicNow() - getLastLeaseRenewal();
-        if (elapsed > HdfsConstants.LEASE_HARDLIMIT_PERIOD) {
-          LOG.warn("Failed to renew lease for " + clientName + " for "
-              + (elapsed/1000) + " seconds (>= hard-limit ="
-              + (HdfsConstants.LEASE_HARDLIMIT_PERIOD / 1000) + " seconds.) "
-              + "Closing all files being written ...", e);
-          closeAllFilesBeingWritten(true);
-        } else {
-          // Let the lease renewer handle it and retry.
-          throw e;
-        }
-      }
-    }
-    return false;
-  }
-  
-  /**
-   * Close connections the Namenode.
-   */
-  void closeConnectionToNamenode() {
-    RPC.stopProxy(namenode);
-  }
-
-  /** Close/abort all files being written. */
-  public void closeAllFilesBeingWritten(final boolean abort) {
-    for(;;) {
-      final long inodeId;
-      final DFSOutputStream out;
-      synchronized(filesBeingWritten) {
-        if (filesBeingWritten.isEmpty()) {
-          return;
-        }
-        inodeId = filesBeingWritten.keySet().iterator().next();
-        out = filesBeingWritten.remove(inodeId);
-      }
-      if (out != null) {
-        try {
-          if (abort) {
-            out.abort();
-          } else {
-            out.close();
-          }
-        } catch(IOException ie) {
-          LOG.error("Failed to " + (abort ? "abort" : "close") + " file: "
-              + out.getSrc() + " with inode: " + inodeId, ie);
-        }
-      }
-    }
-  }
-
-  /**
-   * Close the file system, abandoning all of the leases and files being
-   * created and close connections to the namenode.
-   */
-  @Override
-  public synchronized void close() throws IOException {
-    if(clientRunning) {
-      closeAllFilesBeingWritten(false);
-      clientRunning = false;
-      getLeaseRenewer().closeClient(this);
-      // close connections to the namenode
-      closeConnectionToNamenode();
-    }
-  }
-
-  /**
-   * Close all open streams, abandoning all of the leases and files being
-   * created.
-   * @param abort whether streams should be gracefully closed
-   */
-  public void closeOutputStreams(boolean abort) {
-    if (clientRunning) {
-      closeAllFilesBeingWritten(abort);
-    }
-  }
-
-  /**
-   * @see ClientProtocol#getPreferredBlockSize(String)
-   */
-  public long getBlockSize(String f) throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("getBlockSize", f);
-    try {
-      return namenode.getPreferredBlockSize(f);
-    } catch (IOException ie) {
-      LOG.warn("Problem getting block size", ie);
-      throw ie;
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Get server default values for a number of configuration params.
-   * @see ClientProtocol#getServerDefaults()
-   */
-  public FsServerDefaults getServerDefaults() throws IOException {
-    checkOpen();
-    long now = Time.monotonicNow();
-    if ((serverDefaults == null) ||
-        (now - serverDefaultsLastUpdate > SERVER_DEFAULTS_VALIDITY_PERIOD)) {
-      serverDefaults = namenode.getServerDefaults();
-      serverDefaultsLastUpdate = now;
-    }
-    assert serverDefaults != null;
-    return serverDefaults;
-  }
-  
-  /**
-   * Get a canonical token service name for this client's tokens.  Null should
-   * be returned if the client is not using tokens.
-   * @return the token service for the client
-   */
-  @InterfaceAudience.LimitedPrivate( { "HDFS" }) 
-  public String getCanonicalServiceName() {
-    return (dtService != null) ? dtService.toString() : null;
-  }
-  
-  /**
-   * @see ClientProtocol#getDelegationToken(Text)
-   */
-  public Token<DelegationTokenIdentifier> getDelegationToken(Text renewer)
-      throws IOException {
-    assert dtService != null;
-    TraceScope scope = Trace.startSpan("getDelegationToken", traceSampler);
-    try {
-      Token<DelegationTokenIdentifier> token =
-        namenode.getDelegationToken(renewer);
-      if (token != null) {
-        token.setService(this.dtService);
-        LOG.info("Created " + DelegationTokenIdentifier.stringifyToken(token));
-      } else {
-        LOG.info("Cannot get delegation token from " + renewer);
-      }
-      return token;
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Renew a delegation token
-   * @param token the token to renew
-   * @return the new expiration time
-   * @throws InvalidToken
-   * @throws IOException
-   * @deprecated Use Token.renew instead.
-   */
-  @Deprecated
-  public long renewDelegationToken(Token<DelegationTokenIdentifier> token)
-      throws InvalidToken, IOException {
-    LOG.info("Renewing " + DelegationTokenIdentifier.stringifyToken(token));
-    try {
-      return token.renew(conf);
-    } catch (InterruptedException ie) {                                       
-      throw new RuntimeException("caught interrupted", ie);
-    } catch (RemoteException re) {
-      throw re.unwrapRemoteException(InvalidToken.class,
-                                     AccessControlException.class);
-    }
-  }
-  
-  /**
-   * Cancel a delegation token
-   * @param token the token to cancel
-   * @throws InvalidToken
-   * @throws IOException
-   * @deprecated Use Token.cancel instead.
-   */
-  @Deprecated
-  public void cancelDelegationToken(Token<DelegationTokenIdentifier> token)
-      throws InvalidToken, IOException {
-    LOG.info("Cancelling " + DelegationTokenIdentifier.stringifyToken(token));
-    try {
-      token.cancel(conf);
-     } catch (InterruptedException ie) {                                       
-      throw new RuntimeException("caught interrupted", ie);
-    } catch (RemoteException re) {
-      throw re.unwrapRemoteException(InvalidToken.class,
-                                     AccessControlException.class);
-    }
-  }
-  
-  @InterfaceAudience.Private
-  public static class Renewer extends TokenRenewer {
-    
-    static {
-      //Ensure that HDFS Configuration files are loaded before trying to use
-      // the renewer.
-      HdfsConfiguration.init();
-    }
-    
-    @Override
-    public boolean handleKind(Text kind) {
-      return DelegationTokenIdentifier.HDFS_DELEGATION_KIND.equals(kind);
-    }
-
-    @SuppressWarnings("unchecked")
-    @Override
-    public long renew(Token<?> token, Configuration conf) throws IOException {
-      Token<DelegationTokenIdentifier> delToken = 
-        (Token<DelegationTokenIdentifier>) token;
-      ClientProtocol nn = getNNProxy(delToken, conf);
-      try {
-        return nn.renewDelegationToken(delToken);
-      } catch (RemoteException re) {
-        throw re.unwrapRemoteException(InvalidToken.class, 
-                                       AccessControlException.class);
-      }
-    }
-
-    @SuppressWarnings("unchecked")
-    @Override
-    public void cancel(Token<?> token, Configuration conf) throws IOException {
-      Token<DelegationTokenIdentifier> delToken = 
-          (Token<DelegationTokenIdentifier>) token;
-      LOG.info("Cancelling " + 
-               DelegationTokenIdentifier.stringifyToken(delToken));
-      ClientProtocol nn = getNNProxy(delToken, conf);
-      try {
-        nn.cancelDelegationToken(delToken);
-      } catch (RemoteException re) {
-        throw re.unwrapRemoteException(InvalidToken.class,
-            AccessControlException.class);
-      }
-    }
-    
-    private static ClientProtocol getNNProxy(
-        Token<DelegationTokenIdentifier> token, Configuration conf)
-        throws IOException {
-      URI uri = HAUtilClient.getServiceUriFromToken(
-          HdfsConstants.HDFS_URI_SCHEME, token);
-      if (HAUtilClient.isTokenForLogicalUri(token) &&
-          !HAUtilClient.isLogicalUri(conf, uri)) {
-        // If the token is for a logical nameservice, but the configuration
-        // we have disagrees about that, we can't actually renew it.
-        // This can be the case in MR, for example, if the RM doesn't
-        // have all of the HA clusters configured in its configuration.
-        throw new IOException("Unable to map logical nameservice URI '" +
-            uri + "' to a NameNode. Local configuration does not have " +
-            "a failover proxy provider configured.");
-      }
-      
-      ProxyAndInfo<ClientProtocol> info =
-        NameNodeProxiesClient.createProxyWithClientProtocol(conf, uri, null);
-      assert info.getDelegationTokenService().equals(token.getService()) :
-        "Returned service '" + info.getDelegationTokenService().toString() +
-        "' doesn't match expected service '" +
-        token.getService().toString() + "'";
-        
-      return info.getProxy();
-    }
-
-    @Override
-    public boolean isManaged(Token<?> token) throws IOException {
-      return true;
-    }
-    
-  }
-
-  /**
-   * Report corrupt blocks that were discovered by the client.
-   * @see ClientProtocol#reportBadBlocks(LocatedBlock[])
-   */
-  public void reportBadBlocks(LocatedBlock[] blocks) throws IOException {
-    checkOpen();
-    namenode.reportBadBlocks(blocks);
-  }
-  
-  public LocatedBlocks getLocatedBlocks(String src, long start)
-      throws IOException {
-    return getLocatedBlocks(src, start, dfsClientConf.getPrefetchSize());
-  }
-
-  /*
-   * This is just a wrapper around callGetBlockLocations, but non-static so that
-   * we can stub it out for tests.
-   */
-  @VisibleForTesting
-  public LocatedBlocks getLocatedBlocks(String src, long start, long length)
-      throws IOException {
-    TraceScope scope = getPathTraceScope("getBlockLocations", src);
-    try {
-      return callGetBlockLocations(namenode, src, start, length);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * @see ClientProtocol#getBlockLocations(String, long, long)
-   */
-  static LocatedBlocks callGetBlockLocations(ClientProtocol namenode,
-      String src, long start, long length) 
-      throws IOException {
-    try {
-      return namenode.getBlockLocations(src, start, length);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class,
-                                     UnresolvedPathException.class);
-    }
-  }
-
-  /**
-   * Recover a file's lease
-   * @param src a file's path
-   * @return true if the file is already closed
-   * @throws IOException
-   */
-  boolean recoverLease(String src) throws IOException {
-    checkOpen();
-
-    TraceScope scope = getPathTraceScope("recoverLease", src);
-    try {
-      return namenode.recoverLease(src, clientName);
-    } catch (RemoteException re) {
-      throw re.unwrapRemoteException(FileNotFoundException.class,
-                                     AccessControlException.class,
-                                     UnresolvedPathException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Get block location info about file
-   * 
-   * getBlockLocations() returns a list of hostnames that store 
-   * data for a specific file region.  It returns a set of hostnames
-   * for every block within the indicated region.
-   *
-   * This function is very useful when writing code that considers
-   * data-placement when performing operations.  For example, the
-   * MapReduce system tries to schedule tasks on the same machines
-   * as the data-block the task processes. 
-   */
-  public BlockLocation[] getBlockLocations(String src, long start, 
-        long length) throws IOException, UnresolvedLinkException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("getBlockLocations", src);
-    try {
-      LocatedBlocks blocks = getLocatedBlocks(src, start, length);
-      BlockLocation[] locations =  DFSUtilClient.locatedBlocks2Locations(blocks);
-      HdfsBlockLocation[] hdfsLocations = new HdfsBlockLocation[locations.length];
-      for (int i = 0; i < locations.length; i++) {
-        hdfsLocations[i] = new HdfsBlockLocation(locations[i], blocks.get(i));
-      }
-      return hdfsLocations;
-    } finally {
-      scope.close();
-    }
-  }
-  
-  /**
-   * Decrypts a EDEK by consulting the KeyProvider.
-   */
-  private KeyVersion decryptEncryptedDataEncryptionKey(FileEncryptionInfo
-      feInfo) throws IOException {
-    TraceScope scope = Trace.startSpan("decryptEDEK", traceSampler);
-    try {
-      KeyProvider provider = getKeyProvider();
-      if (provider == null) {
-        throw new IOException("No KeyProvider is configured, cannot access" +
-            " an encrypted file");
-      }
-      EncryptedKeyVersion ekv = EncryptedKeyVersion.createForDecryption(
-          feInfo.getKeyName(), feInfo.getEzKeyVersionName(), feInfo.getIV(),
-          feInfo.getEncryptedDataEncryptionKey());
-      try {
-        KeyProviderCryptoExtension cryptoProvider = KeyProviderCryptoExtension
-            .createKeyProviderCryptoExtension(provider);
-        return cryptoProvider.decryptEncryptedKey(ekv);
-      } catch (GeneralSecurityException e) {
-        throw new IOException(e);
-      }
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Obtain the crypto protocol version from the provided FileEncryptionInfo,
-   * checking to see if this version is supported by.
-   *
-   * @param feInfo FileEncryptionInfo
-   * @return CryptoProtocolVersion from the feInfo
-   * @throws IOException if the protocol version is unsupported.
-   */
-  private static CryptoProtocolVersion getCryptoProtocolVersion
-      (FileEncryptionInfo feInfo) throws IOException {
-    final CryptoProtocolVersion version = feInfo.getCryptoProtocolVersion();
-    if (!CryptoProtocolVersion.supports(version)) {
-      throw new IOException("Client does not support specified " +
-          "CryptoProtocolVersion " + version.getDescription() + " version " +
-          "number" + version.getVersion());
-    }
-    return version;
-  }
-
-  /**
-   * Obtain a CryptoCodec based on the CipherSuite set in a FileEncryptionInfo
-   * and the available CryptoCodecs configured in the Configuration.
-   *
-   * @param conf   Configuration
-   * @param feInfo FileEncryptionInfo
-   * @return CryptoCodec
-   * @throws IOException if no suitable CryptoCodec for the CipherSuite is
-   *                     available.
-   */
-  private static CryptoCodec getCryptoCodec(Configuration conf,
-      FileEncryptionInfo feInfo) throws IOException {
-    final CipherSuite suite = feInfo.getCipherSuite();
-    if (suite.equals(CipherSuite.UNKNOWN)) {
-      throw new IOException("NameNode specified unknown CipherSuite with ID "
-          + suite.getUnknownValue() + ", cannot instantiate CryptoCodec.");
-    }
-    final CryptoCodec codec = CryptoCodec.getInstance(conf, suite);
-    if (codec == null) {
-      throw new UnknownCipherSuiteException(
-          "No configuration found for the cipher suite "
-          + suite.getConfigSuffix() + " prefixed with "
-          + HADOOP_SECURITY_CRYPTO_CODEC_CLASSES_KEY_PREFIX
-          + ". Please see the example configuration "
-          + "hadoop.security.crypto.codec.classes.EXAMPLECIPHERSUITE "
-          + "at core-default.xml for details.");
-    }
-    return codec;
-  }
-
-  /**
-   * Wraps the stream in a CryptoInputStream if the underlying file is
-   * encrypted.
-   */
-  public HdfsDataInputStream createWrappedInputStream(DFSInputStream dfsis)
-      throws IOException {
-    final FileEncryptionInfo feInfo = dfsis.getFileEncryptionInfo();
-    if (feInfo != null) {
-      // File is encrypted, wrap the stream in a crypto stream.
-      // Currently only one version, so no special logic based on the version #
-      getCryptoProtocolVersion(feInfo);
-      final CryptoCodec codec = getCryptoCodec(conf, feInfo);
-      final KeyVersion decrypted = decryptEncryptedDataEncryptionKey(feInfo);
-      final CryptoInputStream cryptoIn =
-          new CryptoInputStream(dfsis, codec, decrypted.getMaterial(),
-              feInfo.getIV());
-      return new HdfsDataInputStream(cryptoIn);
-    } else {
-      // No FileEncryptionInfo so no encryption.
-      return new HdfsDataInputStream(dfsis);
-    }
-  }
-
-  /**
-   * Wraps the stream in a CryptoOutputStream if the underlying file is
-   * encrypted.
-   */
-  public HdfsDataOutputStream createWrappedOutputStream(DFSOutputStream dfsos,
-      FileSystem.Statistics statistics) throws IOException {
-    return createWrappedOutputStream(dfsos, statistics, 0);
-  }
-
-  /**
-   * Wraps the stream in a CryptoOutputStream if the underlying file is
-   * encrypted.
-   */
-  public HdfsDataOutputStream createWrappedOutputStream(DFSOutputStream dfsos,
-      FileSystem.Statistics statistics, long startPos) throws IOException {
-    final FileEncryptionInfo feInfo = dfsos.getFileEncryptionInfo();
-    if (feInfo != null) {
-      // File is encrypted, wrap the stream in a crypto stream.
-      // Currently only one version, so no special logic based on the version #
-      getCryptoProtocolVersion(feInfo);
-      final CryptoCodec codec = getCryptoCodec(conf, feInfo);
-      KeyVersion decrypted = decryptEncryptedDataEncryptionKey(feInfo);
-      final CryptoOutputStream cryptoOut =
-          new CryptoOutputStream(dfsos, codec,
-              decrypted.getMaterial(), feInfo.getIV(), startPos);
-      return new HdfsDataOutputStream(cryptoOut, statistics, startPos);
-    } else {
-      // No FileEncryptionInfo present so no encryption.
-      return new HdfsDataOutputStream(dfsos, statistics, startPos);
-    }
-  }
-
-  public DFSInputStream open(String src) 
-      throws IOException, UnresolvedLinkException {
-    return open(src, dfsClientConf.getIoBufferSize(), true, null);
-  }
-
-  /**
-   * Create an input stream that obtains a nodelist from the
-   * namenode, and then reads from all the right places.  Creates
-   * inner subclass of InputStream that does the right out-of-band
-   * work.
-   * @deprecated Use {@link #open(String, int, boolean)} instead.
-   */
-  @Deprecated
-  public DFSInputStream open(String src, int buffersize, boolean verifyChecksum,
-                             FileSystem.Statistics stats)
-      throws IOException, UnresolvedLinkException {
-    return open(src, buffersize, verifyChecksum);
-  }
-  
-
-  /**
-   * Create an input stream that obtains a nodelist from the
-   * namenode, and then reads from all the right places.  Creates
-   * inner subclass of InputStream that does the right out-of-band
-   * work.
-   */
-  public DFSInputStream open(String src, int buffersize, boolean verifyChecksum)
-      throws IOException, UnresolvedLinkException {
-    checkOpen();
-    //    Get block info from namenode
-    TraceScope scope = getPathTraceScope("newDFSInputStream", src);
-    try {
-      return new DFSInputStream(this, src, verifyChecksum, null);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Get the namenode associated with this DFSClient object
-   * @return the namenode associated with this DFSClient object
-   */
-  public ClientProtocol getNamenode() {
-    return namenode;
-  }
-  
-  /**
-   * Call {@link #create(String, boolean, short, long, Progressable)} with
-   * default <code>replication</code> and <code>blockSize<code> and null <code>
-   * progress</code>.
-   */
-  public OutputStream create(String src, boolean overwrite) 
-      throws IOException {
-    return create(src, overwrite, dfsClientConf.getDefaultReplication(),
-        dfsClientConf.getDefaultBlockSize(), null);
-  }
-    
-  /**
-   * Call {@link #create(String, boolean, short, long, Progressable)} with
-   * default <code>replication</code> and <code>blockSize<code>.
-   */
-  public OutputStream create(String src, 
-                             boolean overwrite,
-                             Progressable progress) throws IOException {
-    return create(src, overwrite, dfsClientConf.getDefaultReplication(),
-        dfsClientConf.getDefaultBlockSize(), progress);
-  }
-    
-  /**
-   * Call {@link #create(String, boolean, short, long, Progressable)} with
-   * null <code>progress</code>.
-   */
-  public OutputStream create(String src, 
-                             boolean overwrite, 
-                             short replication,
-                             long blockSize) throws IOException {
-    return create(src, overwrite, replication, blockSize, null);
-  }
-
-  /**
-   * Call {@link #create(String, boolean, short, long, Progressable, int)}
-   * with default bufferSize.
-   */
-  public OutputStream create(String src, boolean overwrite, short replication,
-      long blockSize, Progressable progress) throws IOException {
-    return create(src, overwrite, replication, blockSize, progress,
-        dfsClientConf.getIoBufferSize());
-  }
-
-  /**
-   * Call {@link #create(String, FsPermission, EnumSet, short, long, 
-   * Progressable, int, ChecksumOpt)} with default <code>permission</code>
-   * {@link FsPermission#getFileDefault()}.
-   * 
-   * @param src File name
-   * @param overwrite overwrite an existing file if true
-   * @param replication replication factor for the file
-   * @param blockSize maximum block size
-   * @param progress interface for reporting client progress
-   * @param buffersize underlying buffersize
-   * 
-   * @return output stream
-   */
-  public OutputStream create(String src,
-                             boolean overwrite,
-                             short replication,
-                             long blockSize,
-                             Progressable progress,
-                             int buffersize)
-      throws IOException {
-    return create(src, FsPermission.getFileDefault(),
-        overwrite ? EnumSet.of(CreateFlag.CREATE, CreateFlag.OVERWRITE)
-            : EnumSet.of(CreateFlag.CREATE), replication, blockSize, progress,
-        buffersize, null);
-  }
-
-  /**
-   * Call {@link #create(String, FsPermission, EnumSet, boolean, short, 
-   * long, Progressable, int, ChecksumOpt)} with <code>createParent</code>
-   *  set to true.
-   */
-  public DFSOutputStream create(String src, 
-                             FsPermission permission,
-                             EnumSet<CreateFlag> flag, 
-                             short replication,
-                             long blockSize,
-                             Progressable progress,
-                             int buffersize,
-                             ChecksumOpt checksumOpt)
-      throws IOException {
-    return create(src, permission, flag, true,
-        replication, blockSize, progress, buffersize, checksumOpt, null);
-  }
-
-  /**
-   * Create a new dfs file with the specified block replication 
-   * with write-progress reporting and return an output stream for writing
-   * into the file.  
-   * 
-   * @param src File name
-   * @param permission The permission of the directory being created.
-   *          If null, use default permission {@link FsPermission#getFileDefault()}
-   * @param flag indicates create a new file or create/overwrite an
-   *          existing file or append to an existing file
-   * @param createParent create missing parent directory if true
-   * @param replication block replication
-   * @param blockSize maximum block size
-   * @param progress interface for reporting client progress
-   * @param buffersize underlying buffer size 
-   * @param checksumOpt checksum options
-   * 
-   * @return output stream
-   *
-   * @see ClientProtocol#create for detailed description of exceptions thrown
-   */
-  public DFSOutputStream create(String src, 
-                             FsPermission permission,
-                             EnumSet<CreateFlag> flag, 
-                             boolean createParent,
-                             short replication,
-                             long blockSize,
-                             Progressable progress,
-                             int buffersize,
-                             ChecksumOpt checksumOpt) throws IOException {
-    return create(src, permission, flag, createParent, replication, blockSize, 
-        progress, buffersize, checksumOpt, null);
-  }
-
-  private FsPermission applyUMask(FsPermission permission) {
-    if (permission == null) {
-      permission = FsPermission.getFileDefault();
-    }
-    return permission.applyUMask(dfsClientConf.getUMask());
-  }
-
-  /**
-   * Same as {@link #create(String, FsPermission, EnumSet, boolean, short, long,
-   * Progressable, int, ChecksumOpt)} with the addition of favoredNodes that is
-   * a hint to where the namenode should place the file blocks.
-   * The favored nodes hint is not persisted in HDFS. Hence it may be honored
-   * at the creation time only. HDFS could move the blocks during balancing or
-   * replication, to move the blocks from favored nodes. A value of null means
-   * no favored nodes for this create
-   */
-  public DFSOutputStream create(String src, 
-                             FsPermission permission,
-                             EnumSet<CreateFlag> flag, 
-                             boolean createParent,
-                             short replication,
-                             long blockSize,
-                             Progressable progress,
-                             int buffersize,
-                             ChecksumOpt checksumOpt,
-                             InetSocketAddress[] favoredNodes) throws IOException {
-    checkOpen();
-    final FsPermission masked = applyUMask(permission);
-    if(LOG.isDebugEnabled()) {
-      LOG.debug(src + ": masked=" + masked);
-    }
-    final DFSOutputStream result = DFSOutputStream.newStreamForCreate(this,
-        src, masked, flag, createParent, replication, blockSize, progress,
-        buffersize, dfsClientConf.createChecksum(checksumOpt),
-        getFavoredNodesStr(favoredNodes));
-    beginFileLease(result.getFileId(), result);
-    return result;
-  }
-
-  private String[] getFavoredNodesStr(InetSocketAddress[] favoredNodes) {
-    String[] favoredNodeStrs = null;
-    if (favoredNodes != null) {
-      favoredNodeStrs = new String[favoredNodes.length];
-      for (int i = 0; i < favoredNodes.length; i++) {
-        favoredNodeStrs[i] = 
-            favoredNodes[i].getHostName() + ":" 
-                         + favoredNodes[i].getPort();
-      }
-    }
-    return favoredNodeStrs;
-  }
-  
-  /**
-   * Append to an existing file if {@link CreateFlag#APPEND} is present
-   */
-  private DFSOutputStream primitiveAppend(String src, EnumSet<CreateFlag> flag,
-      int buffersize, Progressable progress) throws IOException {
-    if (flag.contains(CreateFlag.APPEND)) {
-      HdfsFileStatus stat = getFileInfo(src);
-      if (stat == null) { // No file to append to
-        // New file needs to be created if create option is present
-        if (!flag.contains(CreateFlag.CREATE)) {
-          throw new FileNotFoundException("failed to append to non-existent file "
-              + src + " on client " + clientName);
-        }
-        return null;
-      }
-      return callAppend(src, buffersize, flag, progress, null);
-    }
-    return null;
-  }
-  
-  /**
-   * Same as {{@link #create(String, FsPermission, EnumSet, short, long,
-   *  Progressable, int, ChecksumOpt)} except that the permission
-   *  is absolute (ie has already been masked with umask.
-   */
-  public DFSOutputStream primitiveCreate(String src, 
-                             FsPermission absPermission,
-                             EnumSet<CreateFlag> flag,
-                             boolean createParent,
-                             short replication,
-                             long blockSize,
-                             Progressable progress,
-                             int buffersize,
-                             ChecksumOpt checksumOpt)
-      throws IOException, UnresolvedLinkException {
-    checkOpen();
-    CreateFlag.validate(flag);
-    DFSOutputStream result = primitiveAppend(src, flag, buffersize, progress);
-    if (result == null) {
-      DataChecksum checksum = dfsClientConf.createChecksum(checksumOpt);
-      result = DFSOutputStream.newStreamForCreate(this, src, absPermission,
-          flag, createParent, replication, blockSize, progress, buffersize,
-          checksum, null);
-    }
-    beginFileLease(result.getFileId(), result);
-    return result;
-  }
-  
-  /**
-   * Creates a symbolic link.
-   * 
-   * @see ClientProtocol#createSymlink(String, String,FsPermission, boolean) 
-   */
-  public void createSymlink(String target, String link, boolean createParent)
-      throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("createSymlink", target);
-    try {
-      final FsPermission dirPerm = applyUMask(null);
-      namenode.createSymlink(target, link, dirPerm, createParent);
-    } catch (RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileAlreadyExistsException.class, 
-                                     FileNotFoundException.class,
-                                     ParentNotDirectoryException.class,
-                                     NSQuotaExceededException.class, 
-                                     DSQuotaExceededException.class,
-                                     QuotaByStorageTypeExceededException.class,
-                                     UnresolvedPathException.class,
-                                     SnapshotAccessControlException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Resolve the *first* symlink, if any, in the path.
-   * 
-   * @see ClientProtocol#getLinkTarget(String)
-   */
-  public String getLinkTarget(String path) throws IOException { 
-    checkOpen();
-    TraceScope scope = getPathTraceScope("getLinkTarget", path);
-    try {
-      return namenode.getLinkTarget(path);
-    } catch (RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /** Method to get stream returned by append call */
-  private DFSOutputStream callAppend(String src, int buffersize,
-      EnumSet<CreateFlag> flag, Progressable progress, String[] favoredNodes)
-      throws IOException {
-    CreateFlag.validateForAppend(flag);
-    try {
-      LastBlockWithStatus blkWithStatus = namenode.append(src, clientName,
-          new EnumSetWritable<>(flag, CreateFlag.class));
-      return DFSOutputStream.newStreamForAppend(this, src, flag, buffersize,
-          progress, blkWithStatus.getLastBlock(),
-          blkWithStatus.getFileStatus(), dfsClientConf.createChecksum(null),
-          favoredNodes);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class,
-                                     SafeModeException.class,
-                                     DSQuotaExceededException.class,
-                                     QuotaByStorageTypeExceededException.class,
-                                     UnsupportedOperationException.class,
-                                     UnresolvedPathException.class,
-                                     SnapshotAccessControlException.class);
-    }
-  }
-  
-  /**
-   * Append to an existing HDFS file.  
-   * 
-   * @param src file name
-   * @param buffersize buffer size
-   * @param flag indicates whether to append data to a new block instead of
-   *             the last block
-   * @param progress for reporting write-progress; null is acceptable.
-   * @param statistics file system statistics; null is acceptable.
-   * @return an output stream for writing into the file
-   * 
-   * @see ClientProtocol#append(String, String, EnumSetWritable)
-   */
-  public HdfsDataOutputStream append(final String src, final int buffersize,
-      EnumSet<CreateFlag> flag, final Progressable progress,
-      final FileSystem.Statistics statistics) throws IOException {
-    final DFSOutputStream out = append(src, buffersize, flag, null, progress);
-    return createWrappedOutputStream(out, statistics, out.getInitialLen());
-  }
-
-  /**
-   * Append to an existing HDFS file.
-   * 
-   * @param src file name
-   * @param buffersize buffer size
-   * @param flag indicates whether to append data to a new block instead of the
-   *          last block
-   * @param progress for reporting write-progress; null is acceptable.
-   * @param statistics file system statistics; null is acceptable.
-   * @param favoredNodes FavoredNodes for new blocks
-   * @return an output stream for writing into the file
-   * @see ClientProtocol#append(String, String, EnumSetWritable)
-   */
-  public HdfsDataOutputStream append(final String src, final int buffersize,
-      EnumSet<CreateFlag> flag, final Progressable progress,
-      final FileSystem.Statistics statistics,
-      final InetSocketAddress[] favoredNodes) throws IOException {
-    final DFSOutputStream out = append(src, buffersize, flag,
-        getFavoredNodesStr(favoredNodes), progress);
-    return createWrappedOutputStream(out, statistics, out.getInitialLen());
-  }
-
-  private DFSOutputStream append(String src, int buffersize,
-      EnumSet<CreateFlag> flag, String[] favoredNodes, Progressable progress)
-      throws IOException {
-    checkOpen();
-    final DFSOutputStream result = callAppend(src, buffersize, flag, progress,
-        favoredNodes);
-    beginFileLease(result.getFileId(), result);
-    return result;
-  }
-
-  /**
-   * Set replication for an existing file.
-   * @param src file name
-   * @param replication replication to set the file to
-   * 
-   * @see ClientProtocol#setReplication(String, short)
-   */
-  public boolean setReplication(String src, short replication)
-      throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("setReplication", src);
-    try {
-      return namenode.setReplication(src, replication);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class,
-                                     SafeModeException.class,
-                                     DSQuotaExceededException.class,
-                                     QuotaByStorageTypeExceededException.class,
-                                     UnresolvedPathException.class,
-                                     SnapshotAccessControlException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Set storage policy for an existing file/directory
-   * @param src file/directory name
-   * @param policyName name of the storage policy
-   */
-  public void setStoragePolicy(String src, String policyName)
-      throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("setStoragePolicy", src);
-    try {
-      namenode.setStoragePolicy(src, policyName);
-    } catch (RemoteException e) {
-      throw e.unwrapRemoteException(AccessControlException.class,
-                                    FileNotFoundException.class,
-                                    SafeModeException.class,
-                                    NSQuotaExceededException.class,
-                                    UnresolvedPathException.class,
-                                    SnapshotAccessControlException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * @param path file/directory name
-   * @return Get the storage policy for specified path
-   */
-  public BlockStoragePolicy getStoragePolicy(String path) throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("getStoragePolicy", path);
-    try {
-      return namenode.getStoragePolicy(path);
-    } catch (RemoteException e) {
-      throw e.unwrapRemoteException(AccessControlException.class,
-                                    FileNotFoundException.class,
-                                    SafeModeException.class,
-                                    UnresolvedPathException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * @return All the existing storage policies
-   */
-  public BlockStoragePolicy[] getStoragePolicies() throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("getStoragePolicies", traceSampler);
-    try {
-      return namenode.getStoragePolicies();
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Rename file or directory.
-   * @see ClientProtocol#rename(String, String)
-   * @deprecated Use {@link #rename(String, String, Options.Rename...)} instead.
-   */
-  @Deprecated
-  public boolean rename(String src, String dst) throws IOException {
-    checkOpen();
-    TraceScope scope = getSrcDstTraceScope("rename", src, dst);
-    try {
-      return namenode.rename(src, dst);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     NSQuotaExceededException.class,
-                                     DSQuotaExceededException.class,
-                                     QuotaByStorageTypeExceededException.class,
-                                     UnresolvedPathException.class,
-                                     SnapshotAccessControlException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Move blocks from src to trg and delete src
-   * See {@link ClientProtocol#concat}.
-   */
-  public void concat(String trg, String [] srcs) throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("concat", traceSampler);
-    try {
-      namenode.concat(trg, srcs);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     UnresolvedPathException.class,
-                                     SnapshotAccessControlException.class);
-    } finally {
-      scope.close();
-    }
-  }
-  /**
-   * Rename file or directory.
-   * @see ClientProtocol#rename2(String, String, Options.Rename...)
-   */
-  public void rename(String src, String dst, Options.Rename... options)
-      throws IOException {
-    checkOpen();
-    TraceScope scope = getSrcDstTraceScope("rename2", src, dst);
-    try {
-      namenode.rename2(src, dst, options);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     DSQuotaExceededException.class,
-                                     QuotaByStorageTypeExceededException.class,
-                                     FileAlreadyExistsException.class,
-                                     FileNotFoundException.class,
-                                     ParentNotDirectoryException.class,
-                                     SafeModeException.class,
-                                     NSQuotaExceededException.class,
-                                     UnresolvedPathException.class,
-                                     SnapshotAccessControlException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Truncate a file to an indicated size
-   * See {@link ClientProtocol#truncate}.
-   */
-  public boolean truncate(String src, long newLength) throws IOException {
-    checkOpen();
-    if (newLength < 0) {
-      throw new HadoopIllegalArgumentException(
-          "Cannot truncate to a negative file size: " + newLength + ".");
-    }
-    TraceScope scope = getPathTraceScope("truncate", src);
-    try {
-      return namenode.truncate(src, newLength, clientName);
-    } catch (RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-          UnresolvedPathException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Delete file or directory.
-   * See {@link ClientProtocol#delete(String, boolean)}. 
-   */
-  @Deprecated
-  public boolean delete(String src) throws IOException {
-    checkOpen();
-    return delete(src, true);
-  }
-
-  /**
-   * delete file or directory.
-   * delete contents of the directory if non empty and recursive 
-   * set to true
-   *
-   * @see ClientProtocol#delete(String, boolean)
-   */
-  public boolean delete(String src, boolean recursive) throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("delete", src);
-    try {
-      return namenode.delete(src, recursive);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class,
-                                     SafeModeException.class,
-                                     UnresolvedPathException.class,
-                                     SnapshotAccessControlException.class);
-    } finally {
-      scope.close();
-    }
-  }
-  
-  /** Implemented using getFileInfo(src)
-   */
-  public boolean exists(String src) throws IOException {
-    checkOpen();
-    return getFileInfo(src) != null;
-  }
-
-  /**
-   * Get a partial listing of the indicated directory
-   * No block locations need to be fetched
-   */
-  public DirectoryListing listPaths(String src,  byte[] startAfter)
-    throws IOException {
-    return listPaths(src, startAfter, false);
-  }
-  
-  /**
-   * Get a partial listing of the indicated directory
-   *
-   * Recommend to use HdfsFileStatus.EMPTY_NAME as startAfter
-   * if the application wants to fetch a listing starting from
-   * the first entry in the directory
-   *
-   * @see ClientProtocol#getListing(String, byte[], boolean)
-   */
-  public DirectoryListing listPaths(String src,  byte[] startAfter,
-      boolean needLocation) throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("listPaths", src);
-    try {
-      return namenode.getListing(src, startAfter, needLocation);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class,
-                                     UnresolvedPathException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Get the file info for a specific file or directory.
-   * @param src The string representation of the path to the file
-   * @return object containing information regarding the file
-   *         or null if file not found
-   *         
-   * @see ClientProtocol#getFileInfo(String) for description of exceptions
-   */
-  public HdfsFileStatus getFileInfo(String src) throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("getFileInfo", src);
-    try {
-      return namenode.getFileInfo(src);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class,
-                                     UnresolvedPathException.class);
-    } finally {
-      scope.close();
-    }
-  }
-  
-  /**
-   * Close status of a file
-   * @return true if file is already closed
-   */
-  public boolean isFileClosed(String src) throws IOException{
-    checkOpen();
-    TraceScope scope = getPathTraceScope("isFileClosed", src);
-    try {
-      return namenode.isFileClosed(src);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class,
-                                     UnresolvedPathException.class);
-    } finally {
-      scope.close();
-    }
-  }
-  
-  /**
-   * Get the file info for a specific file or directory. If src
-   * refers to a symlink then the FileStatus of the link is returned.
-   * @param src path to a file or directory.
-   * 
-   * For description of exceptions thrown 
-   * @see ClientProtocol#getFileLinkInfo(String)
-   */
-  public HdfsFileStatus getFileLinkInfo(String src) throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("getFileLinkInfo", src);
-    try {
-      return namenode.getFileLinkInfo(src);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     UnresolvedPathException.class);
-    } finally {
-      scope.close();
-    }
-   }
-  
-  @InterfaceAudience.Private
-  public void clearDataEncryptionKey() {
-    LOG.debug("Clearing encryption key");
-    synchronized (this) {
-      encryptionKey = null;
-    }
-  }
-  
-  /**
-   * @return true if data sent between this client and DNs should be encrypted,
-   *         false otherwise.
-   * @throws IOException in the event of error communicating with the NN
-   */
-  boolean shouldEncryptData() throws IOException {
-    FsServerDefaults d = getServerDefaults();
-    return d == null ? false : d.getEncryptDataTransfer();
-  }
-  
-  @Override
-  public DataEncryptionKey newDataEncryptionKey() throws IOException {
-    if (shouldEncryptData()) {
-      synchronized (this) {
-        if (encryptionKey == null ||
-            encryptionKey.expiryDate < Time.now()) {
-          LOG.debug("Getting new encryption token from NN");
-          encryptionKey = namenode.getDataEncryptionKey();
-        }
-        return encryptionKey;
-      }
-    } else {
-      return null;
-    }
-  }
-
-  /**
-   * Get the checksum of the whole file of a range of the file. Note that the
-   * range always starts from the beginning of the file.
-   * @param src The file path
-   * @param length the length of the range, i.e., the range is [0, length]
-   * @return The checksum 
-   * @see DistributedFileSystem#getFileChecksum(Path)
-   */
-  public MD5MD5CRC32FileChecksum getFileChecksum(String src, long length)
-      throws IOException {
-    checkOpen();
-    Preconditions.checkArgument(length >= 0);
-    //get block locations for the file range
-    LocatedBlocks blockLocations = callGetBlockLocations(namenode, src, 0,
-        length);
-    if (null == blockLocations) {
-      throw new FileNotFoundException("File does not exist: " + src);
-    }
-    if (blockLocations.isUnderConstruction()) {
-      throw new IOException("Fail to get checksum, since file " + src
-          + " is under construction.");
-    }
-    List<LocatedBlock> locatedblocks = blockLocations.getLocatedBlocks();
-    final DataOutputBuffer md5out = new DataOutputBuffer();
-    int bytesPerCRC = -1;
-    DataChecksum.Type crcType = DataChecksum.Type.DEFAULT;
-    long crcPerBlock = 0;
-    boolean refetchBlocks = false;
-    int lastRetriedIndex = -1;
-
-    // get block checksum for each block
-    long remaining = length;
-    if (src.contains(HdfsConstants.SEPARATOR_DOT_SNAPSHOT_DIR_SEPARATOR)) {
-      remaining = Math.min(length, blockLocations.getFileLength());
-    }
-    for(int i = 0; i < locatedblocks.size() && remaining > 0; i++) {
-      if (refetchBlocks) {  // refetch to get fresh tokens
-        blockLocations = callGetBlockLocations(namenode, src, 0, length);
-        if (null == blockLocations) {
-          throw new FileNotFoundException("File does not exist: " + src);
-        }
-        if (blockLocations.isUnderConstruction()) {
-          throw new IOException("Fail to get checksum, since file " + src
-              + " is under construction.");
-        }
-        locatedblocks = blockLocations.getLocatedBlocks();
-        refetchBlocks = false;
-      }
-      LocatedBlock lb = locatedblocks.get(i);
-      final ExtendedBlock block = lb.getBlock();
-      if (remaining < block.getNumBytes()) {
-        block.setNumBytes(remaining);
-      }
-      remaining -= block.getNumBytes();
-      final DatanodeInfo[] datanodes = lb.getLocations();
-      
-      //try each datanode location of the block
-      final int timeout = 3000*datanodes.length + dfsClientConf.getSocketTimeout();
-      boolean done = false;
-      for(int j = 0; !done && j < datanodes.length; j++) {
-        DataOutputStream out = null;
-        DataInputStream in = null;
-        
-        try {
-          //connect to a datanode
-          IOStreamPair pair = connectToDN(datanodes[j], timeout, lb);
-          out = new DataOutputStream(new BufferedOutputStream(pair.out,
-              smallBufferSize));
-          in = new DataInputStream(pair.in);
-
-          if (LOG.isDebugEnabled()) {
-            LOG.debug("write to " + datanodes[j] + ": "
-                + Op.BLOCK_CHECKSUM + ", block=" + block);
-          }
-          // get block MD5
-          new Sender(out).blockChecksum(block, lb.getBlockToken());
-
-          final BlockOpResponseProto reply =
-            BlockOpResponseProto.parseFrom(PBHelperClient.vintPrefixed(in));
-
-          String logInfo = "for block " + block + " from datanode " + datanodes[j];
-          DataTransferProtoUtil.checkBlockOpStatus(reply, logInfo);
-
-          OpBlockChecksumResponseProto checksumData =
-            reply.getChecksumResponse();
-
-          //read byte-per-checksum
-          final int bpc = checksumData.getBytesPerCrc();
-          if (i == 0) { //first block
-            bytesPerCRC = bpc;
-          }
-          else if (bpc != bytesPerCRC) {
-            throw new IOException("Byte-per-checksum not matched: bpc=" + bpc
-                + " but bytesPerCRC=" + bytesPerCRC);
-          }
-          
-          //read crc-per-block
-          final long cpb = checksumData.getCrcPerBlock();
-          if (locatedblocks.size() > 1 && i == 0) {
-            crcPerBlock = cpb;
-          }
-
-          //read md5
-          final MD5Hash md5 = new MD5Hash(
-              checksumData.getMd5().toByteArray());
-          md5.write(md5out);
-          
-          // read crc-type
-          final DataChecksum.Type ct;
-          if (checksumData.hasCrcType()) {
-            ct = PBHelperClient.convert(checksumData
-                .getCrcType());
-          } else {
-            LOG.debug("Retrieving checksum from an earlier-version DataNode: " +
-                      "inferring checksum by reading first byte");
-            ct = inferChecksumTypeByReading(lb, datanodes[j]);
-          }
-
-          if (i == 0) { // first block
-            crcType = ct;
-          } else if (crcType != DataChecksum.Type.MIXED
-              && crcType != ct) {
-            // if crc types are mixed in a file
-            crcType = DataChecksum.Type.MIXED;
-          }
-
-          done = true;
-
-          if (LOG.isDebugEnabled()) {
-            if (i == 0) {
-              LOG.debug("set bytesPerCRC=" + bytesPerCRC
-                  + ", crcPerBlock=" + crcPerBlock);
-            }
-            LOG.debug("got reply from " + datanodes[j] + ": md5=" + md5);
-          }
-        } catch (InvalidBlockTokenException ibte) {
-          if (i > lastRetriedIndex) {
-            if (LOG.isDebugEnabled()) {
-              LOG.debug("Got access token error in response to OP_BLOCK_CHECKSUM "
-                  + "for file " + src + " for block " + block
-                  + " from datanode " + datanodes[j]
-                  + ". Will retry the block once.");
-            }
-            lastRetriedIndex = i;
-            done = true; // actually it's not done; but we'll retry
-            i--; // repeat at i-th block
-            refetchBlocks = true;
-            break;
-          }
-        } catch (IOException ie) {
-          LOG.warn("src=" + src + ", datanodes["+j+"]=" + datanodes[j], ie);
-        } finally {
-          IOUtils.closeStream(in);
-          IOUtils.closeStream(out);
-        }
-      }
-
-      if (!done) {
-        throw new IOException("Fail to get block MD5 for " + block);
-      }
-    }
-
-    //compute file MD5
-    final MD5Hash fileMD5 = MD5Hash.digest(md5out.getData()); 
-    switch (crcType) {
-      case CRC32:
-        return new MD5MD5CRC32GzipFileChecksum(bytesPerCRC,
-            crcPerBlock, fileMD5);
-      case CRC32C:
-        return new MD5MD5CRC32CastagnoliFileChecksum(bytesPerCRC,
-            crcPerBlock, fileMD5);
-      default:
-        // If there is no block allocated for the file,
-        // return one with the magic entry that matches what previous
-        // hdfs versions return.
-        if (locatedblocks.size() == 0) {
-          return new MD5MD5CRC32GzipFileChecksum(0, 0, fileMD5);
-        }
-
-        // we should never get here since the validity was checked
-        // when getCrcType() was called above.
-        return null;
-    }
-  }
-
-  /**
-   * Connect to the given datanode's datantrasfer port, and return
-   * the resulting IOStreamPair. This includes encryption wrapping, etc.
-   */
-  private IOStreamPair connectToDN(DatanodeInfo dn, int timeout,
-      LocatedBlock lb) throws IOException {
-    boolean success = false;
-    Socket sock = null;
-    try {
-      sock = socketFactory.createSocket();
-      String dnAddr = dn.getXferAddr(getConf().isConnectToDnViaHostname());
-      if (LOG.isDebugEnabled()) {
-        LOG.debug("Connecting to datanode " + dnAddr);
-      }
-      NetUtils.connect(sock, NetUtils.createSocketAddr(dnAddr), timeout);
-      sock.setSoTimeout(timeout);
-  
-      OutputStream unbufOut = NetUtils.getOutputStream(sock);
-      InputStream unbufIn = NetUtils.getInputStream(sock);
-      IOStreamPair ret = saslClient.newSocketSend(sock, unbufOut, unbufIn, this,
-        lb.getBlockToken(), dn);
-      success = true;
-      return ret;
-    } finally {
-      if (!success) {
-        IOUtils.closeSocket(sock);
-      }
-    }
-  }
-  
-  /**
-   * Infer the checksum type for a replica by sending an OP_READ_BLOCK
-   * for the first byte of that replica. This is used for compatibility
-   * with older HDFS versions which did not include the checksum type in
-   * OpBlockChecksumResponseProto.
-   *
-   * @param lb the located block
-   * @param dn the connected datanode
-   * @return the inferred checksum type
-   * @throws IOException if an error occurs
-   */
-  private Type inferChecksumTypeByReading(LocatedBlock lb, DatanodeInfo dn)
-      throws IOException {
-    IOStreamPair pair = connectToDN(dn, dfsClientConf.getSocketTimeout(), lb);
-
-    try {
-      DataOutputStream out = new DataOutputStream(new BufferedOutputStream(pair.out,
-          smallBufferSize));
-      DataInputStream in = new DataInputStream(pair.in);
-  
-      new Sender(out).readBlock(lb.getBlock(), lb.getBlockToken(), clientName,
-          0, 1, true, CachingStrategy.newDefaultStrategy());
-      final BlockOpResponseProto reply =
-          BlockOpResponseProto.parseFrom(PBHelperClient.vintPrefixed(in));
-      String logInfo = "trying to read " + lb.getBlock() + " from datanode " + dn;
-      DataTransferProtoUtil.checkBlockOpStatus(reply, logInfo);
-
-      return PBHelperClient.convert(reply.getReadOpChecksumInfo().getChecksum().getType());
-    } finally {
-      IOUtils.cleanup(null, pair.in, pair.out);
-    }
-  }
-
-  /**
-   * Set permissions to a file or directory.
-   * @param src path name.
-   * @param permission permission to set to
-   * 
-   * @see ClientProtocol#setPermission(String, FsPermission)
-   */
-  public void setPermission(String src, FsPermission permission)
-      throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("setPermission", src);
-    try {
-      namenode.setPermission(src, permission);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class,
-                                     SafeModeException.class,
-                                     UnresolvedPathException.class,
-                                     SnapshotAccessControlException.class);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Set file or directory owner.
-   * @param src path name.
-   * @param username user id.
-   * @param groupname user group.
-   * 
-   * @see ClientProtocol#setOwner(String, String, String)
-   */
-  public void setOwner(String src, String username, String groupname)
-      throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("setOwner", src);
-    try {
-      namenode.setOwner(src, username, groupname);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException(AccessControlException.class,
-                                     FileNotFoundException.class,
-                                     SafeModeException.class,
-                                     UnresolvedPathException.class,
-                                     SnapshotAccessControlException.class);                                   
-    } finally {
-      scope.close();
-    }
-  }
-
-  private long[] callGetStats() throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("getStats", traceSampler);
-    try {
-      return namenode.getStats();
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * @see ClientProtocol#getStats()
-   */
-  public FsStatus getDiskStatus() throws IOException {
-    long rawNums[] = callGetStats();
-    return new FsStatus(rawNums[0], rawNums[1], rawNums[2]);
-  }
-
-  /**
-   * Returns count of blocks with no good replicas left. Normally should be 
-   * zero.
-   * @throws IOException
-   */ 
-  public long getMissingBlocksCount() throws IOException {
-    return callGetStats()[ClientProtocol.GET_STATS_MISSING_BLOCKS_IDX];
-  }
-  
-  /**
-   * Returns count of blocks with replication factor 1 and have
-   * lost the only replica.
-   * @throws IOException
-   */
-  public long getMissingReplOneBlocksCount() throws IOException {
-    return callGetStats()[ClientProtocol.
-        GET_STATS_MISSING_REPL_ONE_BLOCKS_IDX];
-  }
-
-  /**
-   * Returns count of blocks with one of more replica missing.
-   * @throws IOException
-   */ 
-  public long getUnderReplicatedBlocksCount() throws IOException {
-    return callGetStats()[ClientProtocol.GET_STATS_UNDER_REPLICATED_IDX];
-  }
-  
-  /**
-   * Returns count of blocks with at least one replica marked corrupt. 
-   * @throws IOException
-   */ 
-  public long getCorruptBlocksCount() throws IOException {
-    return callGetStats()[ClientProtocol.GET_STATS_CORRUPT_BLOCKS_IDX];
-  }
-  
-  /**
-   * @return a list in which each entry describes a corrupt file/block
-   * @throws IOException
-   */
-  public CorruptFileBlocks listCorruptFileBlocks(String path,
-                                                 String cookie)
-        throws IOException {
-    checkOpen();
-    TraceScope scope = getPathTraceScope("listCorruptFileBlocks", path);
-    try {
-      return namenode.listCorruptFileBlocks(path, cookie);
-    } finally {
-      scope.close();
-    }
-  }
-
-  public DatanodeInfo[] datanodeReport(DatanodeReportType type)
-      throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("datanodeReport", traceSampler);
-    try {
-      return namenode.getDatanodeReport(type);
-    } finally {
-      scope.close();
-    }
-  }
-    
-  public DatanodeStorageReport[] getDatanodeStorageReport(
-      DatanodeReportType type) throws IOException {
-    checkOpen();
-    TraceScope scope =
-        Trace.startSpan("datanodeStorageReport", traceSampler);
-    try {
-      return namenode.getDatanodeStorageReport(type);
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Enter, leave or get safe mode.
-   * 
-   * @see ClientProtocol#setSafeMode(HdfsConstants.SafeModeAction,boolean)
-   */
-  public boolean setSafeMode(SafeModeAction action) throws IOException {
-    checkOpen();
-    return setSafeMode(action, false);
-  }
-  
-  /**
-   * Enter, leave or get safe mode.
-   * 
-   * @param action
-   *          One of SafeModeAction.GET, SafeModeAction.ENTER and
-   *          SafeModeActiob.LEAVE
-   * @param isChecked
-   *          If true, then check only active namenode's safemode status, else
-   *          check first namenode's status.
-   * @see ClientProtocol#setSafeMode(HdfsConstants.SafeModeAction, boolean)
-   */
-  public boolean setSafeMode(SafeModeAction action, boolean isChecked) throws IOException{
-    TraceScope scope =
-        Trace.startSpan("setSafeMode", traceSampler);
-    try {
-      return namenode.setSafeMode(action, isChecked);
-    } finally {
-      scope.close();
-    }
-  }
- 
-  /**
-   * Create one snapshot.
-   * 
-   * @param snapshotRoot The directory where the snapshot is to be taken
-   * @param snapshotName Name of the snapshot
-   * @return the snapshot path.
-   * @see ClientProtocol#createSnapshot(String, String)
-   */
-  public String createSnapshot(String snapshotRoot, String snapshotName)
-      throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("createSnapshot", traceSampler);
-    try {
-      return namenode.createSnapshot(snapshotRoot, snapshotName);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException();
-    } finally {
-      scope.close();
-    }
-  }
-  
-  /**
-   * Delete a snapshot of a snapshottable directory.
-   * 
-   * @param snapshotRoot The snapshottable directory that the 
-   *                    to-be-deleted snapshot belongs to
-   * @param snapshotName The name of the to-be-deleted snapshot
-   * @throws IOException
-   * @see ClientProtocol#deleteSnapshot(String, String)
-   */
-  public void deleteSnapshot(String snapshotRoot, String snapshotName)
-      throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("deleteSnapshot", traceSampler);
-    try {
-      namenode.deleteSnapshot(snapshotRoot, snapshotName);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException();
-    } finally {
-      scope.close();
-    }
-  }
-  
-  /**
-   * Rename a snapshot.
-   * @param snapshotDir The directory path where the snapshot was taken
-   * @param snapshotOldName Old name of the snapshot
-   * @param snapshotNewName New name of the snapshot
-   * @throws IOException
-   * @see ClientProtocol#renameSnapshot(String, String, String)
-   */
-  public void renameSnapshot(String snapshotDir, String snapshotOldName,
-      String snapshotNewName) throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("renameSnapshot", traceSampler);
-    try {
-      namenode.renameSnapshot(snapshotDir, snapshotOldName, snapshotNewName);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException();
-    } finally {
-      scope.close();
-    }
-  }
-  
-  /**
-   * Get all the current snapshottable directories.
-   * @return All the current snapshottable directories
-   * @throws IOException
-   * @see ClientProtocol#getSnapshottableDirListing()
-   */
-  public SnapshottableDirectoryStatus[] getSnapshottableDirListing()
-      throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("getSnapshottableDirListing",
-        traceSampler);
-    try {
-      return namenode.getSnapshottableDirListing();
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException();
-    } finally {
-      scope.close();
-    }
-  }
-
-  /**
-   * Allow snapshot on a directory.
-   * 
-   * @see ClientProtocol#allowSnapshot(String snapshotRoot)
-   */
-  public void allowSnapshot(String snapshotRoot) throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("allowSnapshot", traceSampler);
-    try {
-      namenode.allowSnapshot(snapshotRoot);
-    } catch (RemoteException re) {
-      throw re.unwrapRemoteException();
-    } finally {
-      scope.close();
-    }
-  }
-  
-  /**
-   * Disallow snapshot on a directory.
-   * 
-   * @see ClientProtocol#disallowSnapshot(String snapshotRoot)
-   */
-  public void disallowSnapshot(String snapshotRoot) throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("disallowSnapshot", traceSampler);
-    try {
-      namenode.disallowSnapshot(snapshotRoot);
-    } catch (RemoteException re) {
-      throw re.unwrapRemoteException();
-    } finally {
-      scope.close();
-    }
-  }
-  
-  /**
-   * Get the difference between two snapshots, or between a snapshot and the
-   * current tree of a directory.
-   * @see ClientProtocol#getSnapshotDiffReport(String, String, String)
-   */
-  public SnapshotDiffReport getSnapshotDiffReport(String snapshotDir,
-      String fromSnapshot, String toSnapshot) throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("getSnapshotDiffReport", traceSampler);
-    try {
-      return namenode.getSnapshotDiffReport(snapshotDir,
-          fromSnapshot, toSnapshot);
-    } catch(RemoteException re) {
-      throw re.unwrapRemoteException();
-    } finally {
-      scope.close();
-    }
-  }
-
-  public long addCacheDirective(
-      CacheDirectiveInfo info, EnumSet<CacheFlag> flags) throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("addCacheDirective", traceSampler);
-    try {
-      return namenode.addCacheDirective(info, flags);
-    } catch (RemoteException re) {
-      throw re.unwrapRemoteException();
-    } finally {
-      scope.close();
-    }
-  }
-  
-  public void modifyCacheDirective(
-      CacheDirectiveInfo info, EnumSet<CacheFlag> flags) throws IOException {
-    checkOpen();
-    TraceScope scope = Trace.startSpan("modifyCacheDirect

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