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From whe...@apache.org
Subject [2/2] hadoop git commit: HDFS-8238. Move ClientProtocol to the hdfs-client. Contributed by Takanobu Asanuma.
Date Wed, 17 Jun 2015 23:16:58 GMT
HDFS-8238. Move ClientProtocol to the hdfs-client. Contributed by Takanobu Asanuma.


Project: http://git-wip-us.apache.org/repos/asf/hadoop/repo
Commit: http://git-wip-us.apache.org/repos/asf/hadoop/commit/09941e6f
Tree: http://git-wip-us.apache.org/repos/asf/hadoop/tree/09941e6f
Diff: http://git-wip-us.apache.org/repos/asf/hadoop/diff/09941e6f

Branch: refs/heads/branch-2
Commit: 09941e6f8db03140820b24a929c8ae70e8c9506b
Parents: f0901e7
Author: Haohui Mai <wheat9@apache.org>
Authored: Wed Jun 17 16:16:36 2015 -0700
Committer: Haohui Mai <wheat9@apache.org>
Committed: Wed Jun 17 16:16:55 2015 -0700

----------------------------------------------------------------------
 .../hdfs/client/HdfsClientConfigKeys.java       |    1 +
 .../hadoop/hdfs/protocol/ClientProtocol.java    | 1454 ++++++++++++++++++
 .../hdfs/server/namenode/SafeModeException.java |   38 +
 .../org/apache/hadoop/hdfs/DFSConfigKeys.java   |    3 +-
 .../hadoop/hdfs/protocol/ClientProtocol.java    | 1454 ------------------
 .../hdfs/server/namenode/SafeModeException.java |   38 -
 6 files changed, 1495 insertions(+), 1493 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/hadoop/blob/09941e6f/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/HdfsClientConfigKeys.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/HdfsClientConfigKeys.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/HdfsClientConfigKeys.java
index 05955d3..beed4eb 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/HdfsClientConfigKeys.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/HdfsClientConfigKeys.java
@@ -43,6 +43,7 @@ public interface HdfsClientConfigKeys {
   String  DFS_NAMENODE_HTTP_PORT_KEY = "dfs.http.port";
   String  DFS_NAMENODE_HTTPS_PORT_KEY = "dfs.https.port";
   int DFS_NAMENODE_RPC_PORT_DEFAULT = 8020;
+  String DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY = "dfs.namenode.kerberos.principal";
 
   /** dfs.client.retry configuration properties */
   interface Retry {

http://git-wip-us.apache.org/repos/asf/hadoop/blob/09941e6f/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java
new file mode 100644
index 0000000..599eb06
--- /dev/null
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java
@@ -0,0 +1,1454 @@
+/**
+ * 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.protocol;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.EnumSet;
+import java.util.List;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.crypto.CryptoProtocolVersion;
+import org.apache.hadoop.fs.BatchedRemoteIterator.BatchedEntries;
+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.FsServerDefaults;
+import org.apache.hadoop.fs.InvalidPathException;
+import org.apache.hadoop.fs.Options;
+import org.apache.hadoop.fs.Options.Rename;
+import org.apache.hadoop.fs.ParentNotDirectoryException;
+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.inotify.EventBatchList;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
+import org.apache.hadoop.hdfs.security.token.block.DataEncryptionKey;
+import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
+import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSelector;
+import org.apache.hadoop.hdfs.server.namenode.NotReplicatedYetException;
+import org.apache.hadoop.hdfs.server.namenode.SafeModeException;
+import org.apache.hadoop.hdfs.server.protocol.DatanodeStorageReport;
+import org.apache.hadoop.io.EnumSetWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.retry.AtMostOnce;
+import org.apache.hadoop.io.retry.Idempotent;
+import org.apache.hadoop.security.AccessControlException;
+import org.apache.hadoop.security.KerberosInfo;
+import org.apache.hadoop.security.token.Token;
+import org.apache.hadoop.security.token.TokenInfo;
+
+import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY;
+
+/**********************************************************************
+ * ClientProtocol is used by user code via the DistributedFileSystem class to
+ * communicate with the NameNode.  User code can manipulate the directory
+ * namespace, as well as open/close file streams, etc.
+ *
+ **********************************************************************/
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+@KerberosInfo(
+    serverPrincipal = DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY)
+@TokenInfo(DelegationTokenSelector.class)
+public interface ClientProtocol {
+
+  /**
+   * Until version 69, this class ClientProtocol served as both
+   * the client interface to the NN AND the RPC protocol used to 
+   * communicate with the NN.
+   * 
+   * This class is used by both the DFSClient and the 
+   * NN server side to insulate from the protocol serialization.
+   * 
+   * If you are adding/changing this interface then you need to 
+   * change both this class and ALSO related protocol buffer
+   * wire protocol definition in ClientNamenodeProtocol.proto.
+   * 
+   * For more details on protocol buffer wire protocol, please see 
+   * .../org/apache/hadoop/hdfs/protocolPB/overview.html
+   * 
+   * The log of historical changes can be retrieved from the svn).
+   * 69: Eliminate overloaded method names.
+   * 
+   * 69L is the last version id when this class was used for protocols
+   *  serialization. DO not update this version any further. 
+   */
+  public static final long versionID = 69L;
+  
+  ///////////////////////////////////////
+  // File contents
+  ///////////////////////////////////////
+  /**
+   * Get locations of the blocks of the specified file within the specified range.
+   * DataNode locations for each block are sorted by
+   * the proximity to the client.
+   * <p>
+   * Return {@link LocatedBlocks} which contains
+   * file length, blocks and their locations.
+   * DataNode locations for each block are sorted by
+   * the distance to the client's address.
+   * <p>
+   * The client will then have to contact 
+   * one of the indicated DataNodes to obtain the actual data.
+   * 
+   * @param src file name
+   * @param offset range start offset
+   * @param length range length
+   *
+   * @return file length and array of blocks with their locations
+   *
+   * @throws AccessControlException If access is denied
+   * @throws FileNotFoundException If file <code>src</code> does not exist
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public LocatedBlocks getBlockLocations(String src,
+                                         long offset,
+                                         long length) 
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * Get server default values for a number of configuration params.
+   * @return a set of server default configuration values
+   * @throws IOException
+   */
+  @Idempotent
+  public FsServerDefaults getServerDefaults() throws IOException;
+
+  /**
+   * Create a new file entry in the namespace.
+   * <p>
+   * This will create an empty file specified by the source path.
+   * The path should reflect a full path originated at the root.
+   * The name-node does not have a notion of "current" directory for a client.
+   * <p>
+   * Once created, the file is visible and available for read to other clients.
+   * Although, other clients cannot {@link #delete(String, boolean)}, re-create or 
+   * {@link #rename(String, String)} it until the file is completed
+   * or explicitly as a result of lease expiration.
+   * <p>
+   * Blocks have a maximum size.  Clients that intend to create
+   * multi-block files must also use 
+   * {@link #addBlock}
+   *
+   * @param src path of the file being created.
+   * @param masked masked permission.
+   * @param clientName name of the current client.
+   * @param flag indicates whether the file should be 
+   * overwritten if it already exists or create if it does not exist or append.
+   * @param createParent create missing parent directory if true
+   * @param replication block replication factor.
+   * @param blockSize maximum block size.
+   * @param supportedVersions CryptoProtocolVersions supported by the client
+   * 
+   * @return the status of the created file, it could be null if the server
+   *           doesn't support returning the file status
+   * @throws AccessControlException If access is denied
+   * @throws AlreadyBeingCreatedException if the path does not exist.
+   * @throws DSQuotaExceededException If file creation violates disk space 
+   *           quota restriction
+   * @throws FileAlreadyExistsException If file <code>src</code> already exists
+   * @throws FileNotFoundException If parent of <code>src</code> does not exist
+   *           and <code>createParent</code> is false
+   * @throws ParentNotDirectoryException If parent of <code>src</code> is not a
+   *           directory.
+   * @throws NSQuotaExceededException If file creation violates name space 
+   *           quota restriction
+   * @throws SafeModeException create not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   *
+   * RuntimeExceptions:
+   * @throws InvalidPathException Path <code>src</code> is invalid
+   * <p>
+   * <em>Note that create with {@link CreateFlag#OVERWRITE} is idempotent.</em>
+   */
+  @AtMostOnce
+  public HdfsFileStatus create(String src, FsPermission masked,
+      String clientName, EnumSetWritable<CreateFlag> flag,
+      boolean createParent, short replication, long blockSize, 
+      CryptoProtocolVersion[] supportedVersions)
+      throws AccessControlException, AlreadyBeingCreatedException,
+      DSQuotaExceededException, FileAlreadyExistsException,
+      FileNotFoundException, NSQuotaExceededException,
+      ParentNotDirectoryException, SafeModeException, UnresolvedLinkException,
+      SnapshotAccessControlException, IOException;
+
+  /**
+   * Append to the end of the file. 
+   * @param src path of the file being created.
+   * @param clientName name of the current client.
+   * @param flag indicates whether the data is appended to a new block.
+   * @return wrapper with information about the last partial block and file
+   *    status if any
+   * @throws AccessControlException if permission to append file is 
+   * denied by the system. As usually on the client side the exception will 
+   * be wrapped into {@link org.apache.hadoop.ipc.RemoteException}.
+   * Allows appending to an existing file if the server is
+   * configured with the parameter dfs.support.append set to true, otherwise
+   * throws an IOException.
+   * 
+   * @throws AccessControlException If permission to append to file is denied
+   * @throws FileNotFoundException If file <code>src</code> is not found
+   * @throws DSQuotaExceededException If append violates disk space quota 
+   *           restriction
+   * @throws SafeModeException append not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred.
+   *
+   * RuntimeExceptions:
+   * @throws UnsupportedOperationException if append is not supported
+   */
+  @AtMostOnce
+  public LastBlockWithStatus append(String src, String clientName,
+      EnumSetWritable<CreateFlag> flag) throws AccessControlException,
+      DSQuotaExceededException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, SnapshotAccessControlException, IOException;
+
+  /**
+   * Set replication for an existing file.
+   * <p>
+   * The NameNode sets replication to the new value and returns.
+   * The actual block replication is not expected to be performed during  
+   * this method call. The blocks will be populated or removed in the 
+   * background as the result of the routine block maintenance procedures.
+   * 
+   * @param src file name
+   * @param replication new replication
+   * 
+   * @return true if successful;
+   *         false if file does not exist or is a directory
+   *
+   * @throws AccessControlException If access is denied
+   * @throws DSQuotaExceededException If replication violates disk space 
+   *           quota restriction
+   * @throws FileNotFoundException If file <code>src</code> is not found
+   * @throws SafeModeException not allowed in safemode
+   * @throws UnresolvedLinkException if <code>src</code> contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public boolean setReplication(String src, short replication)
+      throws AccessControlException, DSQuotaExceededException,
+      FileNotFoundException, SafeModeException, UnresolvedLinkException,
+      SnapshotAccessControlException, IOException;
+
+  /**
+   * Get all the available block storage policies.
+   * @return All the in-use block storage policies currently.
+   */
+  @Idempotent
+  public BlockStoragePolicy[] getStoragePolicies() throws IOException;
+
+  /**
+   * Set the storage policy for a file/directory
+   * @param src Path of an existing file/directory. 
+   * @param policyName The name of the storage policy
+   * @throws SnapshotAccessControlException If access is denied
+   * @throws UnresolvedLinkException if <code>src</code> contains a symlink
+   * @throws FileNotFoundException If file/dir <code>src</code> is not found
+   * @throws QuotaExceededException If changes violate the quota restriction
+   */
+  @Idempotent
+  public void setStoragePolicy(String src, String policyName)
+      throws SnapshotAccessControlException, UnresolvedLinkException,
+      FileNotFoundException, QuotaExceededException, IOException;
+
+  /**
+   * Set permissions for an existing file/directory.
+   * 
+   * @throws AccessControlException If access is denied
+   * @throws FileNotFoundException If file <code>src</code> is not found
+   * @throws SafeModeException not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public void setPermission(String src, FsPermission permission)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, SnapshotAccessControlException, IOException;
+
+  /**
+   * Set Owner of a path (i.e. a file or a directory).
+   * The parameters username and groupname cannot both be null.
+   * @param src file path
+   * @param username If it is null, the original username remains unchanged.
+   * @param groupname If it is null, the original groupname remains unchanged.
+   *
+   * @throws AccessControlException If access is denied
+   * @throws FileNotFoundException If file <code>src</code> is not found
+   * @throws SafeModeException not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public void setOwner(String src, String username, String groupname)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, SnapshotAccessControlException, IOException;
+
+  /**
+   * The client can give up on a block by calling abandonBlock().
+   * The client can then either obtain a new block, or complete or abandon the 
+   * file.
+   * Any partial writes to the block will be discarded.
+   * 
+   * @param b         Block to abandon
+   * @param fileId    The id of the file where the block resides.  Older clients
+   *                    will pass GRANDFATHER_INODE_ID here.
+   * @param src       The path of the file where the block resides.
+   * @param holder    Lease holder.
+   *
+   * @throws AccessControlException If access is denied
+   * @throws FileNotFoundException file <code>src</code> is not found
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public void abandonBlock(ExtendedBlock b, long fileId,
+      String src, String holder)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * A client that wants to write an additional block to the 
+   * indicated filename (which must currently be open for writing)
+   * should call addBlock().  
+   *
+   * addBlock() allocates a new block and datanodes the block data
+   * should be replicated to.
+   * 
+   * addBlock() also commits the previous block by reporting
+   * to the name-node the actual generation stamp and the length
+   * of the block that the client has transmitted to data-nodes.
+   *
+   * @param src the file being created
+   * @param clientName the name of the client that adds the block
+   * @param previous  previous block
+   * @param excludeNodes a list of nodes that should not be
+   * allocated for the current block
+   * @param fileId the id uniquely identifying a file
+   * @param favoredNodes the list of nodes where the client wants the blocks.
+   *          Nodes are identified by either host name or address.
+   *
+   * @return LocatedBlock allocated block information.
+   *
+   * @throws AccessControlException If access is denied
+   * @throws FileNotFoundException If file <code>src</code> is not found
+   * @throws NotReplicatedYetException previous blocks of the file are not
+   *           replicated yet. Blocks cannot be added until replication
+   *           completes.
+   * @throws SafeModeException create not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public LocatedBlock addBlock(String src, String clientName,
+      ExtendedBlock previous, DatanodeInfo[] excludeNodes, long fileId, 
+      String[] favoredNodes)
+      throws AccessControlException, FileNotFoundException,
+      NotReplicatedYetException, SafeModeException, UnresolvedLinkException,
+      IOException;
+
+  /** 
+   * Get a datanode for an existing pipeline.
+   * 
+   * @param src the file being written
+   * @param fileId the ID of the file being written
+   * @param blk the block being written
+   * @param existings the existing nodes in the pipeline
+   * @param excludes the excluded nodes
+   * @param numAdditionalNodes number of additional datanodes
+   * @param clientName the name of the client
+   * 
+   * @return the located block.
+   * 
+   * @throws AccessControlException If access is denied
+   * @throws FileNotFoundException If file <code>src</code> is not found
+   * @throws SafeModeException create not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public LocatedBlock getAdditionalDatanode(final String src,
+      final long fileId, final ExtendedBlock blk,
+      final DatanodeInfo[] existings,
+      final String[] existingStorageIDs,
+      final DatanodeInfo[] excludes,
+      final int numAdditionalNodes, final String clientName
+      ) throws AccessControlException, FileNotFoundException,
+          SafeModeException, UnresolvedLinkException, IOException;
+
+  /**
+   * The client is done writing data to the given filename, and would 
+   * like to complete it.  
+   *
+   * The function returns whether the file has been closed successfully.
+   * If the function returns false, the caller should try again.
+   * 
+   * close() also commits the last block of file by reporting
+   * to the name-node the actual generation stamp and the length
+   * of the block that the client has transmitted to data-nodes.
+   *
+   * A call to complete() will not return true until all the file's
+   * blocks have been replicated the minimum number of times.  Thus,
+   * DataNode failures may cause a client to call complete() several
+   * times before succeeding.
+   *
+   * @param src the file being created
+   * @param clientName the name of the client that adds the block
+   * @param last the last block info
+   * @param fileId the id uniquely identifying a file
+   *
+   * @return true if all file blocks are minimally replicated or false otherwise
+   *
+   * @throws AccessControlException If access is denied
+   * @throws FileNotFoundException If file <code>src</code> is not found
+   * @throws SafeModeException create not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink 
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public boolean complete(String src, String clientName,
+                          ExtendedBlock last, long fileId)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * The client wants to report corrupted blocks (blocks with specified
+   * locations on datanodes).
+   * @param blocks Array of located blocks to report
+   */
+  @Idempotent
+  public void reportBadBlocks(LocatedBlock[] blocks) throws IOException;
+
+  ///////////////////////////////////////
+  // Namespace management
+  ///////////////////////////////////////
+  /**
+   * Rename an item in the file system namespace.
+   * @param src existing file or directory name.
+   * @param dst new name.
+   * @return true if successful, or false if the old name does not exist
+   * or if the new name already belongs to the namespace.
+   * 
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException an I/O error occurred 
+   */
+  @AtMostOnce
+  public boolean rename(String src, String dst) 
+      throws UnresolvedLinkException, SnapshotAccessControlException, IOException;
+
+  /**
+   * Moves blocks from srcs to trg and delete srcs
+   * 
+   * @param trg existing file
+   * @param srcs - list of existing files (same block size, same replication)
+   * @throws IOException if some arguments are invalid
+   * @throws UnresolvedLinkException if <code>trg</code> or <code>srcs</code>
+   *           contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   */
+  @AtMostOnce
+  public void concat(String trg, String[] srcs) 
+      throws IOException, UnresolvedLinkException, SnapshotAccessControlException;
+
+  /**
+   * Rename src to dst.
+   * <ul>
+   * <li>Fails if src is a file and dst is a directory.
+   * <li>Fails if src is a directory and dst is a file.
+   * <li>Fails if the parent of dst does not exist or is a file.
+   * </ul>
+   * <p>
+   * Without OVERWRITE option, rename fails if the dst already exists.
+   * With OVERWRITE option, rename overwrites the dst, if it is a file 
+   * or an empty directory. Rename fails if dst is a non-empty directory.
+   * <p>
+   * This implementation of rename is atomic.
+   * <p>
+   * @param src existing file or directory name.
+   * @param dst new name.
+   * @param options Rename options
+   * 
+   * @throws AccessControlException If access is denied
+   * @throws DSQuotaExceededException If rename violates disk space 
+   *           quota restriction
+   * @throws FileAlreadyExistsException If <code>dst</code> already exists and
+   *           <code>options</options> has {@link Rename#OVERWRITE} option
+   *           false.
+   * @throws FileNotFoundException If <code>src</code> does not exist
+   * @throws NSQuotaExceededException If rename violates namespace 
+   *           quota restriction
+   * @throws ParentNotDirectoryException If parent of <code>dst</code> 
+   *           is not a directory
+   * @throws SafeModeException rename not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> or
+   *           <code>dst</code> contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   */
+  @AtMostOnce
+  public void rename2(String src, String dst, Options.Rename... options)
+      throws AccessControlException, DSQuotaExceededException,
+      FileAlreadyExistsException, FileNotFoundException,
+      NSQuotaExceededException, ParentNotDirectoryException, SafeModeException,
+      UnresolvedLinkException, SnapshotAccessControlException, IOException;
+
+  /**
+   * Truncate file src to new size.
+   * <ul>
+   * <li>Fails if src is a directory.
+   * <li>Fails if src does not exist.
+   * <li>Fails if src is not closed.
+   * <li>Fails if new size is greater than current size.
+   * </ul>
+   * <p>
+   * This implementation of truncate is purely a namespace operation if truncate
+   * occurs at a block boundary. Requires DataNode block recovery otherwise.
+   * <p>
+   * @param src  existing file
+   * @param newLength  the target size
+   *
+   * @return true if client does not need to wait for block recovery,
+   * false if client needs to wait for block recovery.
+   *
+   * @throws AccessControlException If access is denied
+   * @throws FileNotFoundException If file <code>src</code> is not found
+   * @throws SafeModeException truncate not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public boolean truncate(String src, long newLength, String clientName)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, SnapshotAccessControlException, IOException;
+
+  /**
+   * Delete the given file or directory from the file system.
+   * <p>
+   * same as delete but provides a way to avoid accidentally 
+   * deleting non empty directories programmatically. 
+   * @param src existing name
+   * @param recursive if true deletes a non empty directory recursively,
+   * else throws an exception.
+   * @return true only if the existing file or directory was actually removed 
+   * from the file system.
+   * 
+   * @throws AccessControlException If access is denied
+   * @throws FileNotFoundException If file <code>src</code> is not found
+   * @throws SafeModeException create not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   */
+  @AtMostOnce
+  public boolean delete(String src, boolean recursive)
+      throws AccessControlException, FileNotFoundException, SafeModeException,
+      UnresolvedLinkException, SnapshotAccessControlException, IOException;
+  
+  /**
+   * Create a directory (or hierarchy of directories) with the given
+   * name and permission.
+   *
+   * @param src The path of the directory being created
+   * @param masked The masked permission of the directory being created
+   * @param createParent create missing parent directory if true
+   *
+   * @return True if the operation success.
+   *
+   * @throws AccessControlException If access is denied
+   * @throws FileAlreadyExistsException If <code>src</code> already exists
+   * @throws FileNotFoundException If parent of <code>src</code> does not exist
+   *           and <code>createParent</code> is false
+   * @throws NSQuotaExceededException If file creation violates quota restriction
+   * @throws ParentNotDirectoryException If parent of <code>src</code> 
+   *           is not a directory
+   * @throws SafeModeException create not allowed in safemode
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred.
+   *
+   * RunTimeExceptions:
+   * @throws InvalidPathException If <code>src</code> is invalid
+   */
+  @Idempotent
+  public boolean mkdirs(String src, FsPermission masked, boolean createParent)
+      throws AccessControlException, FileAlreadyExistsException,
+      FileNotFoundException, NSQuotaExceededException,
+      ParentNotDirectoryException, SafeModeException, UnresolvedLinkException,
+      SnapshotAccessControlException, IOException;
+
+  /**
+   * Get a partial listing of the indicated directory
+   *
+   * @param src the directory name
+   * @param startAfter the name to start listing after encoded in java UTF8
+   * @param needLocation if the FileStatus should contain block locations
+   *
+   * @return a partial listing starting after startAfter
+   *
+   * @throws AccessControlException permission denied
+   * @throws FileNotFoundException file <code>src</code> is not found
+   * @throws UnresolvedLinkException If <code>src</code> contains a symlink
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public DirectoryListing getListing(String src,
+                                     byte[] startAfter,
+                                     boolean needLocation)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException;
+  
+  /**
+   * Get listing of all the snapshottable directories
+   * 
+   * @return Information about all the current snapshottable directory
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public SnapshottableDirectoryStatus[] getSnapshottableDirListing()
+      throws IOException;
+
+  ///////////////////////////////////////
+  // System issues and management
+  ///////////////////////////////////////
+
+  /**
+   * Client programs can cause stateful changes in the NameNode
+   * that affect other clients.  A client may obtain a file and 
+   * neither abandon nor complete it.  A client might hold a series
+   * of locks that prevent other clients from proceeding.
+   * Clearly, it would be bad if a client held a bunch of locks
+   * that it never gave up.  This can happen easily if the client
+   * dies unexpectedly.
+   * <p>
+   * So, the NameNode will revoke the locks and live file-creates
+   * for clients that it thinks have died.  A client tells the
+   * NameNode that it is still alive by periodically calling
+   * renewLease().  If a certain amount of time passes since
+   * the last call to renewLease(), the NameNode assumes the
+   * client has died.
+   *
+   * @throws AccessControlException permission denied
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public void renewLease(String clientName) throws AccessControlException,
+      IOException;
+
+  /**
+   * Start lease recovery.
+   * Lightweight NameNode operation to trigger lease recovery
+   * 
+   * @param src path of the file to start lease recovery
+   * @param clientName name of the current client
+   * @return true if the file is already closed
+   * @throws IOException
+   */
+  @Idempotent
+  public boolean recoverLease(String src, String clientName) throws IOException;
+
+  public int GET_STATS_CAPACITY_IDX = 0;
+  public int GET_STATS_USED_IDX = 1;
+  public int GET_STATS_REMAINING_IDX = 2;
+  public int GET_STATS_UNDER_REPLICATED_IDX = 3;
+  public int GET_STATS_CORRUPT_BLOCKS_IDX = 4;
+  public int GET_STATS_MISSING_BLOCKS_IDX = 5;
+  public int GET_STATS_MISSING_REPL_ONE_BLOCKS_IDX = 6;
+  
+  /**
+   * Get a set of statistics about the filesystem.
+   * Right now, only seven values are returned.
+   * <ul>
+   * <li> [0] contains the total storage capacity of the system, in bytes.</li>
+   * <li> [1] contains the total used space of the system, in bytes.</li>
+   * <li> [2] contains the available storage of the system, in bytes.</li>
+   * <li> [3] contains number of under replicated blocks in the system.</li>
+   * <li> [4] contains number of blocks with a corrupt replica. </li>
+   * <li> [5] contains number of blocks without any good replicas left. </li>
+   * <li> [6] contains number of blocks which have replication factor
+   *          1 and have lost the only replica. </li>
+   * </ul>
+   * Use public constants like {@link #GET_STATS_CAPACITY_IDX} in place of 
+   * actual numbers to index into the array.
+   */
+  @Idempotent
+  public long[] getStats() throws IOException;
+
+  /**
+   * Get a report on the system's current datanodes.
+   * One DatanodeInfo object is returned for each DataNode.
+   * Return live datanodes if type is LIVE; dead datanodes if type is DEAD;
+   * otherwise all datanodes if type is ALL.
+   */
+  @Idempotent
+  public DatanodeInfo[] getDatanodeReport(HdfsConstants.DatanodeReportType type)
+      throws IOException;
+
+  /**
+   * Get a report on the current datanode storages.
+   */
+  @Idempotent
+  public DatanodeStorageReport[] getDatanodeStorageReport(
+      HdfsConstants.DatanodeReportType type) throws IOException;
+
+  /**
+   * Get the block size for the given file.
+   * @param filename The name of the file
+   * @return The number of bytes in each block
+   * @throws IOException
+   * @throws UnresolvedLinkException if the path contains a symlink. 
+   */
+  @Idempotent
+  public long getPreferredBlockSize(String filename) 
+      throws IOException, UnresolvedLinkException;
+
+  /**
+   * Enter, leave or get safe mode.
+   * <p>
+   * Safe mode is a name node state when it
+   * <ol><li>does not accept changes to name space (read-only), and</li>
+   * <li>does not replicate or delete blocks.</li></ol>
+   * 
+   * <p>
+   * Safe mode is entered automatically at name node startup.
+   * Safe mode can also be entered manually using
+   * {@link #setSafeMode(HdfsConstants.SafeModeAction,boolean) setSafeMode(SafeModeAction.SAFEMODE_ENTER,false)}.
+   * <p>
+   * At startup the name node accepts data node reports collecting
+   * information about block locations.
+   * In order to leave safe mode it needs to collect a configurable
+   * percentage called threshold of blocks, which satisfy the minimal 
+   * replication condition.
+   * The minimal replication condition is that each block must have at least
+   * <tt>dfs.namenode.replication.min</tt> replicas.
+   * When the threshold is reached the name node extends safe mode
+   * for a configurable amount of time
+   * to let the remaining data nodes to check in before it
+   * will start replicating missing blocks.
+   * Then the name node leaves safe mode.
+   * <p>
+   * If safe mode is turned on manually using
+   * {@link #setSafeMode(HdfsConstants.SafeModeAction,boolean) setSafeMode(SafeModeAction.SAFEMODE_ENTER,false)}
+   * then the name node stays in safe mode until it is manually turned off
+   * using {@link #setSafeMode(HdfsConstants.SafeModeAction,boolean) setSafeMode(SafeModeAction.SAFEMODE_LEAVE,false)}.
+   * Current state of the name node can be verified using
+   * {@link #setSafeMode(HdfsConstants.SafeModeAction,boolean) setSafeMode(SafeModeAction.SAFEMODE_GET,false)}
+   * <h4>Configuration parameters:</h4>
+   * <tt>dfs.safemode.threshold.pct</tt> is the threshold parameter.<br>
+   * <tt>dfs.safemode.extension</tt> is the safe mode extension parameter.<br>
+   * <tt>dfs.namenode.replication.min</tt> is the minimal replication parameter.
+   * 
+   * <h4>Special cases:</h4>
+   * The name node does not enter safe mode at startup if the threshold is 
+   * set to 0 or if the name space is empty.<br>
+   * If the threshold is set to 1 then all blocks need to have at least 
+   * minimal replication.<br>
+   * If the threshold value is greater than 1 then the name node will not be 
+   * able to turn off safe mode automatically.<br>
+   * Safe mode can always be turned off manually.
+   * 
+   * @param action  <ul> <li>0 leave safe mode;</li>
+   *                <li>1 enter safe mode;</li>
+   *                <li>2 get safe mode state.</li></ul>
+   * @param isChecked If true then action will be done only in ActiveNN.
+   * 
+   * @return <ul><li>0 if the safe mode is OFF or</li> 
+   *         <li>1 if the safe mode is ON.</li></ul>
+   *                   
+   * @throws IOException
+   */
+  @Idempotent
+  public boolean setSafeMode(HdfsConstants.SafeModeAction action, boolean isChecked) 
+      throws IOException;
+
+  /**
+   * Save namespace image.
+   * <p>
+   * Saves current namespace into storage directories and reset edits log.
+   * Requires superuser privilege and safe mode.
+   * 
+   * @throws AccessControlException if the superuser privilege is violated.
+   * @throws IOException if image creation failed.
+   */
+  @AtMostOnce
+  public void saveNamespace() throws AccessControlException, IOException;
+
+  
+  /**
+   * Roll the edit log.
+   * Requires superuser privileges.
+   * 
+   * @throws AccessControlException if the superuser privilege is violated
+   * @throws IOException if log roll fails
+   * @return the txid of the new segment
+   */
+  @Idempotent
+  public long rollEdits() throws AccessControlException, IOException;
+
+  /**
+   * Enable/Disable restore failed storage.
+   * <p>
+   * sets flag to enable restore of failed storage replicas
+   * 
+   * @throws AccessControlException if the superuser privilege is violated.
+   */
+  @Idempotent
+  public boolean restoreFailedStorage(String arg) 
+      throws AccessControlException, IOException;
+
+  /**
+   * Tells the namenode to reread the hosts and exclude files. 
+   * @throws IOException
+   */
+  @Idempotent
+  public void refreshNodes() throws IOException;
+
+  /**
+   * Finalize previous upgrade.
+   * Remove file system state saved during the upgrade.
+   * The upgrade will become irreversible.
+   * 
+   * @throws IOException
+   */
+  @Idempotent
+  public void finalizeUpgrade() throws IOException;
+
+  /**
+   * Rolling upgrade operations.
+   * @param action either query, prepare or finalize.
+   * @return rolling upgrade information.
+   */
+  @Idempotent
+  public RollingUpgradeInfo rollingUpgrade(RollingUpgradeAction action)
+      throws IOException;
+
+  /**
+   * @return CorruptFileBlocks, containing a list of corrupt files (with
+   *         duplicates if there is more than one corrupt block in a file)
+   *         and a cookie
+   * @throws IOException
+   *
+   * Each call returns a subset of the corrupt files in the system. To obtain
+   * all corrupt files, call this method repeatedly and each time pass in the
+   * cookie returned from the previous call.
+   */
+  @Idempotent
+  public CorruptFileBlocks listCorruptFileBlocks(String path, String cookie)
+      throws IOException;
+  
+  /**
+   * Dumps namenode data structures into specified file. If the file
+   * already exists, then append.
+   *
+   * @throws IOException
+   */
+  @Idempotent
+  public void metaSave(String filename) throws IOException;
+
+  /**
+   * Tell all datanodes to use a new, non-persistent bandwidth value for
+   * dfs.balance.bandwidthPerSec.
+   *
+   * @param bandwidth Blanacer bandwidth in bytes per second for this datanode.
+   * @throws IOException
+   */
+  @Idempotent
+  public void setBalancerBandwidth(long bandwidth) throws IOException;
+  
+  /**
+   * 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
+   * @throws AccessControlException permission denied
+   * @throws FileNotFoundException file <code>src</code> is not found
+   * @throws UnresolvedLinkException if the path contains a symlink. 
+   * @throws IOException If an I/O error occurred        
+   */
+  @Idempotent
+  public HdfsFileStatus getFileInfo(String src) throws AccessControlException,
+      FileNotFoundException, UnresolvedLinkException, IOException;
+  
+  /**
+   * Get the close status of a file
+   * @param src The string representation of the path to the file
+   *
+   * @return return true if file is closed
+   * @throws AccessControlException permission denied
+   * @throws FileNotFoundException file <code>src</code> is not found
+   * @throws UnresolvedLinkException if the path contains a symlink.
+   * @throws IOException If an I/O error occurred     
+   */
+  @Idempotent
+  public boolean isFileClosed(String src) throws AccessControlException,
+      FileNotFoundException, UnresolvedLinkException, IOException;
+  
+  /**
+   * Get the file info for a specific file or directory. If the path 
+   * refers to a symlink then the FileStatus of the symlink is returned.
+   * @param src The string representation of the path to the file
+   *
+   * @return object containing information regarding the file
+   *         or null if file not found
+   *
+   * @throws AccessControlException permission denied
+   * @throws UnresolvedLinkException if <code>src</code> contains a symlink
+   * @throws IOException If an I/O error occurred        
+   */
+  @Idempotent
+  public HdfsFileStatus getFileLinkInfo(String src)
+      throws AccessControlException, UnresolvedLinkException, IOException;
+  
+  /**
+   * Get {@link ContentSummary} rooted at the specified directory.
+   * @param path The string representation of the path
+   *
+   * @throws AccessControlException permission denied
+   * @throws FileNotFoundException file <code>path</code> is not found
+   * @throws UnresolvedLinkException if <code>path</code> contains a symlink. 
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public ContentSummary getContentSummary(String path)
+      throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, IOException;
+
+  /**
+   * Set the quota for a directory.
+   * @param path  The string representation of the path to the directory
+   * @param namespaceQuota Limit on the number of names in the tree rooted 
+   *                       at the directory
+   * @param storagespaceQuota Limit on storage space occupied all the files under
+   *                       this directory.
+   * @param type StorageType that the space quota is intended to be set on.
+   *             It may be null when called by traditional space/namespace quota.
+   *             When type is is not null, the storagespaceQuota parameter is for
+   *             type specified and namespaceQuota must be
+   *             {@link HdfsConstants#QUOTA_DONT_SET}.
+   *
+   * <br><br>
+   *                       
+   * The quota can have three types of values : (1) 0 or more will set 
+   * the quota to that value, (2) {@link HdfsConstants#QUOTA_DONT_SET}  implies
+   * the quota will not be changed, and (3) {@link HdfsConstants#QUOTA_RESET}
+   * implies the quota will be reset. Any other value is a runtime error.
+   * 
+   * @throws AccessControlException permission denied
+   * @throws FileNotFoundException file <code>path</code> is not found
+   * @throws QuotaExceededException if the directory size 
+   *           is greater than the given quota
+   * @throws UnresolvedLinkException if the <code>path</code> contains a symlink. 
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public void setQuota(String path, long namespaceQuota, long storagespaceQuota,
+      StorageType type) throws AccessControlException, FileNotFoundException,
+      UnresolvedLinkException, SnapshotAccessControlException, IOException;
+
+  /**
+   * Write all metadata for this file into persistent storage.
+   * The file must be currently open for writing.
+   * @param src The string representation of the path
+   * @param inodeId The inode ID, or GRANDFATHER_INODE_ID if the client is
+   *                too old to support fsync with inode IDs.
+   * @param client The string representation of the client
+   * @param lastBlockLength The length of the last block (under construction) 
+   *                        to be reported to NameNode 
+   * @throws AccessControlException permission denied
+   * @throws FileNotFoundException file <code>src</code> is not found
+   * @throws UnresolvedLinkException if <code>src</code> contains a symlink. 
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public void fsync(String src, long inodeId, String client,
+                    long lastBlockLength)
+      throws AccessControlException, FileNotFoundException, 
+      UnresolvedLinkException, IOException;
+
+  /**
+   * Sets the modification and access time of the file to the specified time.
+   * @param src The string representation of the path
+   * @param mtime The number of milliseconds since Jan 1, 1970.
+   *              Setting mtime to -1 means that modification time should not be set
+   *              by this call.
+   * @param atime The number of milliseconds since Jan 1, 1970.
+   *              Setting atime to -1 means that access time should not be set
+   *              by this call.
+   *              
+   * @throws AccessControlException permission denied
+   * @throws FileNotFoundException file <code>src</code> is not found
+   * @throws UnresolvedLinkException if <code>src</code> contains a symlink. 
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  public void setTimes(String src, long mtime, long atime)
+      throws AccessControlException, FileNotFoundException, 
+      UnresolvedLinkException, SnapshotAccessControlException, IOException;
+
+  /**
+   * Create symlink to a file or directory.
+   * @param target The path of the destination that the
+   *               link points to.
+   * @param link The path of the link being created.
+   * @param dirPerm permissions to use when creating parent directories
+   * @param createParent - if true then missing parent dirs are created
+   *                       if false then parent must exist
+   *
+   * @throws AccessControlException permission denied
+   * @throws FileAlreadyExistsException If file <code>link</code> already exists
+   * @throws FileNotFoundException If parent of <code>link</code> does not exist
+   *           and <code>createParent</code> is false
+   * @throws ParentNotDirectoryException If parent of <code>link</code> is not a
+   *           directory.
+   * @throws UnresolvedLinkException if <code>link</target> contains a symlink. 
+   * @throws SnapshotAccessControlException if path is in RO snapshot
+   * @throws IOException If an I/O error occurred
+   */
+  @AtMostOnce
+  public void createSymlink(String target, String link, FsPermission dirPerm,
+      boolean createParent) throws AccessControlException,
+      FileAlreadyExistsException, FileNotFoundException,
+      ParentNotDirectoryException, SafeModeException, UnresolvedLinkException,
+      SnapshotAccessControlException, IOException;
+
+  /**
+   * Return the target of the given symlink. If there is an intermediate
+   * symlink in the path (ie a symlink leading up to the final path component)
+   * then the given path is returned with this symlink resolved.
+   *
+   * @param path The path with a link that needs resolution.
+   * @return The path after resolving the first symbolic link in the path.
+   * @throws AccessControlException permission denied
+   * @throws FileNotFoundException If <code>path</code> does not exist
+   * @throws IOException If the given path does not refer to a symlink
+   *           or an I/O error occurred
+   */
+  @Idempotent
+  public String getLinkTarget(String path) throws AccessControlException,
+      FileNotFoundException, IOException; 
+  
+  /**
+   * Get a new generation stamp together with an access token for 
+   * a block under construction
+   * 
+   * This method is called only when a client needs to recover a failed
+   * pipeline or set up a pipeline for appending to a block.
+   * 
+   * @param block a block
+   * @param clientName the name of the client
+   * @return a located block with a new generation stamp and an access token
+   * @throws IOException if any error occurs
+   */
+  @Idempotent
+  public LocatedBlock updateBlockForPipeline(ExtendedBlock block,
+      String clientName) throws IOException;
+
+  /**
+   * Update a pipeline for a block under construction
+   * 
+   * @param clientName the name of the client
+   * @param oldBlock the old block
+   * @param newBlock the new block containing new generation stamp and length
+   * @param newNodes datanodes in the pipeline
+   * @throws IOException if any error occurs
+   */
+  @AtMostOnce
+  public void updatePipeline(String clientName, ExtendedBlock oldBlock, 
+      ExtendedBlock newBlock, DatanodeID[] newNodes, String[] newStorageIDs)
+      throws IOException;
+
+  /**
+   * Get a valid Delegation Token.
+   * 
+   * @param renewer the designated renewer for the token
+   * @return Token<DelegationTokenIdentifier>
+   * @throws IOException
+   */
+  @Idempotent
+  public Token<DelegationTokenIdentifier> getDelegationToken(Text renewer) 
+      throws IOException;
+
+  /**
+   * Renew an existing delegation token.
+   * 
+   * @param token delegation token obtained earlier
+   * @return the new expiration time
+   * @throws IOException
+   */
+  @Idempotent
+  public long renewDelegationToken(Token<DelegationTokenIdentifier> token)
+      throws IOException;
+  
+  /**
+   * Cancel an existing delegation token.
+   * 
+   * @param token delegation token
+   * @throws IOException
+   */
+  @Idempotent
+  public void cancelDelegationToken(Token<DelegationTokenIdentifier> token)
+      throws IOException;
+  
+  /**
+   * @return encryption key so a client can encrypt data sent via the
+   *         DataTransferProtocol to/from DataNodes.
+   * @throws IOException
+   */
+  @Idempotent
+  public DataEncryptionKey getDataEncryptionKey() throws IOException;
+  
+  /**
+   * Create a snapshot
+   * @param snapshotRoot the path that is being snapshotted
+   * @param snapshotName name of the snapshot created
+   * @return the snapshot path.
+   * @throws IOException
+   */
+  @AtMostOnce
+  public String createSnapshot(String snapshotRoot, String snapshotName)
+      throws IOException;
+
+  /**
+   * Delete a specific snapshot of a snapshottable directory
+   * @param snapshotRoot  The snapshottable directory
+   * @param snapshotName Name of the snapshot for the snapshottable directory
+   * @throws IOException
+   */
+  @AtMostOnce
+  public void deleteSnapshot(String snapshotRoot, String snapshotName)
+      throws IOException;
+  
+  /**
+   * Rename a snapshot
+   * @param snapshotRoot the directory path where the snapshot was taken 
+   * @param snapshotOldName old name of the snapshot
+   * @param snapshotNewName new name of the snapshot
+   * @throws IOException
+   */
+  @AtMostOnce
+  public void renameSnapshot(String snapshotRoot, String snapshotOldName,
+      String snapshotNewName) throws IOException;
+  
+  /**
+   * Allow snapshot on a directory.
+   * @param snapshotRoot the directory to be snapped
+   * @throws IOException on error
+   */
+  @Idempotent
+  public void allowSnapshot(String snapshotRoot)
+      throws IOException;
+    
+  /**
+   * Disallow snapshot on a directory.
+   * @param snapshotRoot the directory to disallow snapshot
+   * @throws IOException on error
+   */
+  @Idempotent
+  public void disallowSnapshot(String snapshotRoot)
+      throws IOException;
+  
+  /**
+   * Get the difference between two snapshots, or between a snapshot and the
+   * current tree of a directory.
+   * 
+   * @param snapshotRoot
+   *          full path of the directory where snapshots are taken
+   * @param fromSnapshot
+   *          snapshot name of the from point. Null indicates the current
+   *          tree
+   * @param toSnapshot
+   *          snapshot name of the to point. Null indicates the current
+   *          tree.
+   * @return The difference report represented as a {@link SnapshotDiffReport}.
+   * @throws IOException on error
+   */
+  @Idempotent
+  public SnapshotDiffReport getSnapshotDiffReport(String snapshotRoot,
+      String fromSnapshot, String toSnapshot) throws IOException;
+
+  /**
+   * Add a CacheDirective to the CacheManager.
+   * 
+   * @param directive A CacheDirectiveInfo to be added
+   * @param flags {@link CacheFlag}s to use for this operation.
+   * @return A CacheDirectiveInfo associated with the added directive
+   * @throws IOException if the directive could not be added
+   */
+  @AtMostOnce
+  public long addCacheDirective(CacheDirectiveInfo directive,
+      EnumSet<CacheFlag> flags) throws IOException;
+
+  /**
+   * Modify a CacheDirective in the CacheManager.
+   * 
+   * @param flags {@link CacheFlag}s to use for this operation.
+   * @throws IOException if the directive could not be modified
+   */
+  @AtMostOnce
+  public void modifyCacheDirective(CacheDirectiveInfo directive,
+      EnumSet<CacheFlag> flags) throws IOException;
+
+  /**
+   * Remove a CacheDirectiveInfo from the CacheManager.
+   * 
+   * @param id of a CacheDirectiveInfo
+   * @throws IOException if the cache directive could not be removed
+   */
+  @AtMostOnce
+  public void removeCacheDirective(long id) throws IOException;
+
+  /**
+   * List the set of cached paths of a cache pool. Incrementally fetches results
+   * from the server.
+   * 
+   * @param prevId The last listed entry ID, or -1 if this is the first call to
+   *               listCacheDirectives.
+   * @param filter Parameters to use to filter the list results, 
+   *               or null to display all directives visible to us.
+   * @return A batch of CacheDirectiveEntry objects.
+   */
+  @Idempotent
+  public BatchedEntries<CacheDirectiveEntry> listCacheDirectives(
+      long prevId, CacheDirectiveInfo filter) throws IOException;
+
+  /**
+   * Add a new cache pool.
+   * 
+   * @param info Description of the new cache pool
+   * @throws IOException If the request could not be completed.
+   */
+  @AtMostOnce
+  public void addCachePool(CachePoolInfo info) throws IOException;
+
+  /**
+   * Modify an existing cache pool.
+   *
+   * @param req
+   *          The request to modify a cache pool.
+   * @throws IOException 
+   *          If the request could not be completed.
+   */
+  @AtMostOnce
+  public void modifyCachePool(CachePoolInfo req) throws IOException;
+  
+  /**
+   * Remove a cache pool.
+   * 
+   * @param pool name of the cache pool to remove.
+   * @throws IOException if the cache pool did not exist, or could not be
+   *           removed.
+   */
+  @AtMostOnce
+  public void removeCachePool(String pool) throws IOException;
+
+  /**
+   * List the set of cache pools. Incrementally fetches results from the server.
+   * 
+   * @param prevPool name of the last pool listed, or the empty string if this is
+   *          the first invocation of listCachePools
+   * @return A batch of CachePoolEntry objects.
+   */
+  @Idempotent
+  public BatchedEntries<CachePoolEntry> listCachePools(String prevPool)
+      throws IOException;
+
+  /**
+   * Modifies ACL entries of files and directories.  This method can add new ACL
+   * entries or modify the permissions on existing ACL entries.  All existing
+   * ACL entries that are not specified in this call are retained without
+   * changes.  (Modifications are merged into the current ACL.)
+   */
+  @Idempotent
+  public void modifyAclEntries(String src, List<AclEntry> aclSpec)
+      throws IOException;
+
+  /**
+   * Removes ACL entries from files and directories.  Other ACL entries are
+   * retained.
+   */
+  @Idempotent
+  public void removeAclEntries(String src, List<AclEntry> aclSpec)
+      throws IOException;
+
+  /**
+   * Removes all default ACL entries from files and directories.
+   */
+  @Idempotent
+  public void removeDefaultAcl(String src) throws IOException;
+
+  /**
+   * Removes all but the base ACL entries of files and directories.  The entries
+   * for user, group, and others are retained for compatibility with permission
+   * bits.
+   */
+  @Idempotent
+  public void removeAcl(String src) throws IOException;
+
+  /**
+   * Fully replaces ACL of files and directories, discarding all existing
+   * entries.
+   */
+  @Idempotent
+  public void setAcl(String src, List<AclEntry> aclSpec) throws IOException;
+
+  /**
+   * Gets the ACLs of files and directories.
+   */
+  @Idempotent
+  public AclStatus getAclStatus(String src) throws IOException;
+  
+  /**
+   * Create an encryption zone
+   */
+  @AtMostOnce
+  public void createEncryptionZone(String src, String keyName)
+    throws IOException;
+
+  /**
+   * Get the encryption zone for a path.
+   */
+  @Idempotent
+  public EncryptionZone getEZForPath(String src)
+    throws IOException;
+
+  /**
+   * Used to implement cursor-based batched listing of {@EncryptionZone}s.
+   *
+   * @param prevId ID of the last item in the previous batch. If there is no
+   *               previous batch, a negative value can be used.
+   * @return Batch of encryption zones.
+   */
+  @Idempotent
+  public BatchedEntries<EncryptionZone> listEncryptionZones(
+      long prevId) throws IOException;
+
+  /**
+   * Set xattr of a file or directory.
+   * The name must be prefixed with the namespace followed by ".". For example,
+   * "user.attr".
+   * <p/>
+   * Refer to the HDFS extended attributes user documentation for details.
+   *
+   * @param src file or directory
+   * @param xAttr <code>XAttr</code> to set
+   * @param flag set flag
+   * @throws IOException
+   */
+  @AtMostOnce
+  public void setXAttr(String src, XAttr xAttr, EnumSet<XAttrSetFlag> flag) 
+      throws IOException;
+  
+  /**
+   * Get xattrs of a file or directory. Values in xAttrs parameter are ignored.
+   * If xAttrs is null or empty, this is the same as getting all xattrs of the
+   * file or directory.  Only those xattrs for which the logged-in user has
+   * permissions to view are returned.
+   * <p/>
+   * Refer to the HDFS extended attributes user documentation for details.
+   *
+   * @param src file or directory
+   * @param xAttrs xAttrs to get
+   * @return List<XAttr> <code>XAttr</code> list 
+   * @throws IOException
+   */
+  @Idempotent
+  public List<XAttr> getXAttrs(String src, List<XAttr> xAttrs) 
+      throws IOException;
+
+  /**
+   * List the xattrs names for a file or directory.
+   * Only the xattr names for which the logged in user has the permissions to
+   * access will be returned.
+   * <p/>
+   * Refer to the HDFS extended attributes user documentation for details.
+   *
+   * @param src file or directory
+   * @return List<XAttr> <code>XAttr</code> list
+   * @throws IOException
+   */
+  @Idempotent
+  public List<XAttr> listXAttrs(String src)
+      throws IOException;
+  
+  /**
+   * Remove xattr of a file or directory.Value in xAttr parameter is ignored.
+   * The name must be prefixed with the namespace followed by ".". For example,
+   * "user.attr".
+   * <p/>
+   * Refer to the HDFS extended attributes user documentation for details.
+   *
+   * @param src file or directory
+   * @param xAttr <code>XAttr</code> to remove
+   * @throws IOException
+   */
+  @AtMostOnce
+  public void removeXAttr(String src, XAttr xAttr) throws IOException;
+
+  /**
+   * Checks if the user can access a path.  The mode specifies which access
+   * checks to perform.  If the requested permissions are granted, then the
+   * method returns normally.  If access is denied, then the method throws an
+   * {@link AccessControlException}.
+   * In general, applications should avoid using this method, due to the risk of
+   * time-of-check/time-of-use race conditions.  The permissions on a file may
+   * change immediately after the access call returns.
+   *
+   * @param path Path to check
+   * @param mode type of access to check
+   * @throws AccessControlException if access is denied
+   * @throws FileNotFoundException if the path does not exist
+   * @throws IOException see specific implementation
+   */
+  @Idempotent
+  public void checkAccess(String path, FsAction mode) throws IOException;
+
+  /**
+   * Get the highest txid the NameNode knows has been written to the edit
+   * log, or -1 if the NameNode's edit log is not yet open for write. Used as
+   * the starting point for the inotify event stream.
+   */
+  @Idempotent
+  public long getCurrentEditLogTxid() throws IOException;
+
+  /**
+   * Get an ordered list of batches of events corresponding to the edit log
+   * transactions for txids equal to or greater than txid.
+   */
+  @Idempotent
+  public EventBatchList getEditsFromTxid(long txid) throws IOException;
+}

http://git-wip-us.apache.org/repos/asf/hadoop/blob/09941e6f/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/SafeModeException.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/SafeModeException.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/SafeModeException.java
new file mode 100644
index 0000000..8080bcf
--- /dev/null
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/SafeModeException.java
@@ -0,0 +1,38 @@
+/**
+ * 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.server.namenode;
+
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/**
+ * This exception is thrown when the name node is in safe mode.
+ * Client cannot modified namespace until the safe mode is off. 
+ * 
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public class SafeModeException extends IOException {
+  private static final long serialVersionUID = 1L;
+  public SafeModeException(String msg) {
+    super(msg);
+  }
+}
\ No newline at end of file

http://git-wip-us.apache.org/repos/asf/hadoop/blob/09941e6f/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
index 5295a2f..e396f53 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
@@ -492,7 +492,8 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final String  DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS = "dfs.short.circuit.shared.memory.watcher.interrupt.check.ms";
   public static final int     DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS_DEFAULT = 60000;
   public static final String  DFS_NAMENODE_KEYTAB_FILE_KEY = "dfs.namenode.keytab.file";
-  public static final String  DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY = "dfs.namenode.kerberos.principal";
+  public static final String  DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY =
+      HdfsClientConfigKeys.DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY;
   @Deprecated
   public static final String  DFS_NAMENODE_USER_NAME_KEY = DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY;
   public static final String  DFS_NAMENODE_KERBEROS_INTERNAL_SPNEGO_PRINCIPAL_KEY = "dfs.namenode.kerberos.internal.spnego.principal";


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