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From z..@apache.org
Subject [49/50] [abbrv] hadoop git commit: Merge commit '456e901a4c5c639267ee87b8e5f1319f256d20c2' (HDFS-6407. Add sorting and pagination in the datanode tab of the NN Web UI. Contributed by Haohui Mai.) into HDFS-7285-merge
Date Mon, 24 Aug 2015 21:11:16 GMT
http://git-wip-us.apache.org/repos/asf/hadoop/blob/6b6a63bb/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java
----------------------------------------------------------------------
diff --cc hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java
index 0000000,8528999..7756bb9
mode 000000,100644..100644
--- 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
@@@ -1,0 -1,1486 +1,1511 @@@
+ /**
+  * 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.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.FsServerDefaults;
+ import org.apache.hadoop.fs.Options;
+ import org.apache.hadoop.fs.StorageType;
+ 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.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.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.
+    */
+   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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws java.io.FileNotFoundException If file <code>src</code> does not
+    *           exist
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException If <code>src</code>
+    *           contains a symlink
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   LocatedBlocks getBlockLocations(String src, long offset, long length)
+       throws IOException;
+ 
+   /**
+    * Get server default values for a number of configuration params.
+    * @return a set of server default configuration values
+    * @throws IOException
+    */
+   @Idempotent
+   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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws AlreadyBeingCreatedException if the path does not exist.
+    * @throws DSQuotaExceededException If file creation violates disk space
+    *           quota restriction
+    * @throws org.apache.hadoop.fs.FileAlreadyExistsException If file
+    *           <code>src</code> already exists
+    * @throws java.io.FileNotFoundException If parent of <code>src</code> does
+    *           not exist and <code>createParent</code> is false
+    * @throws org.apache.hadoop.fs.ParentNotDirectoryException If parent of
+    *           <code>src</code> is not a directory.
+    * @throws NSQuotaExceededException If file creation violates name space
+    *           quota restriction
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException create not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.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 org.apache.hadoop.fs.InvalidPathException Path <code>src</code> is
+    *           invalid
+    * <p>
+    * <em>Note that create with {@link CreateFlag#OVERWRITE} is idempotent.</em>
+    */
+   @AtMostOnce
+   HdfsFileStatus create(String src, FsPermission masked,
+       String clientName, EnumSetWritable<CreateFlag> flag,
+       boolean createParent, short replication, long blockSize,
+       CryptoProtocolVersion[] supportedVersions)
+       throws 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 org.apache.hadoop.security.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 org.apache.hadoop.security.AccessControlException If permission to
+    *           append to file is denied
+    * @throws java.io.FileNotFoundException If file <code>src</code> is not found
+    * @throws DSQuotaExceededException If append violates disk space quota
+    *           restriction
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException append not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.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
+   LastBlockWithStatus append(String src, String clientName,
+       EnumSetWritable<CreateFlag> flag) throws 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws DSQuotaExceededException If replication violates disk space
+    *           quota restriction
+    * @throws java.io.FileNotFoundException If file <code>src</code> is not found
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.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
+   boolean setReplication(String src, short replication)
+       throws IOException;
+ 
+   /**
+    * Get all the available block storage policies.
+    * @return All the in-use block storage policies currently.
+    */
+   @Idempotent
+   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 org.apache.hadoop.fs.UnresolvedLinkException if <code>src</code>
+    *           contains a symlink
+    * @throws java.io.FileNotFoundException If file/dir <code>src</code> is not
+    *           found
+    * @throws QuotaExceededException If changes violate the quota restriction
+    */
+   @Idempotent
+   void setStoragePolicy(String src, String policyName)
+       throws IOException;
+ 
+   /**
+    * Get the storage policy for a file/directory.
+    * @param path
+    *          Path of an existing file/directory.
+    * @throws AccessControlException
+    *           If access is denied
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException
+    *           if <code>src</code> contains a symlink
+    * @throws java.io.FileNotFoundException
+    *           If file/dir <code>src</code> is not found
+    */
+   @Idempotent
+   BlockStoragePolicy getStoragePolicy(String path) throws IOException;
+ 
+   /**
+    * Set permissions for an existing file/directory.
+    *
+    * @throws org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws java.io.FileNotFoundException If file <code>src</code> is not found
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.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
+   void setPermission(String src, FsPermission permission)
+       throws 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws java.io.FileNotFoundException If file <code>src</code> is not found
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.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
+   void setOwner(String src, String username, String groupname)
+       throws 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws java.io.FileNotFoundException file <code>src</code> is not found
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException If <code>src</code>
+    *           contains a symlink
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   void abandonBlock(ExtendedBlock b, long fileId,
+       String src, String holder)
+       throws 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws java.io.FileNotFoundException If file <code>src</code> is not found
+    * @throws org.apache.hadoop.hdfs.server.namenode.NotReplicatedYetException
+    *           previous blocks of the file are not replicated yet.
+    *           Blocks cannot be added until replication completes.
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException create not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException If <code>src</code>
+    *           contains a symlink
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   LocatedBlock addBlock(String src, String clientName,
+       ExtendedBlock previous, DatanodeInfo[] excludeNodes, long fileId,
+       String[] favoredNodes)
+       throws 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws java.io.FileNotFoundException If file <code>src</code> is not found
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException create not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException If <code>src</code>
+    *           contains a symlink
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   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 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws java.io.FileNotFoundException If file <code>src</code> is not found
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException create not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException If <code>src</code>
+    *           contains a symlink
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   boolean complete(String src, String clientName,
+                           ExtendedBlock last, long fileId)
+       throws IOException;
+ 
+   /**
+    * The client wants to report corrupted blocks (blocks with specified
+    * locations on datanodes).
+    * @param blocks Array of located blocks to report
+    */
+   @Idempotent
+   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
+   boolean rename(String src, String dst)
+       throws 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 org.apache.hadoop.fs.UnresolvedLinkException if <code>trg</code> or
+    *           <code>srcs</code> contains a symlink
+    * @throws SnapshotAccessControlException if path is in RO snapshot
+    */
+   @AtMostOnce
+   void concat(String trg, String[] srcs)
+       throws IOException;
+ 
+   /**
+    * 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws DSQuotaExceededException If rename violates disk space
+    *           quota restriction
+    * @throws org.apache.hadoop.fs.FileAlreadyExistsException If <code>dst</code>
+    *           already exists and <code>options</code> has
+    *           {@link org.apache.hadoop.fs.Options.Rename#OVERWRITE} option
+    *           false.
+    * @throws java.io.FileNotFoundException If <code>src</code> does not exist
+    * @throws NSQuotaExceededException If rename violates namespace
+    *           quota restriction
+    * @throws org.apache.hadoop.fs.ParentNotDirectoryException If parent of
+    *           <code>dst</code> is not a directory
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException rename not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.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
+   void rename2(String src, String dst, Options.Rename... options)
+       throws 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws java.io.FileNotFoundException If file <code>src</code> is not found
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException truncate
+    *           not allowed in safemode
+    * @throws org.apache.hadoop.fs.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
+   boolean truncate(String src, long newLength, String clientName)
+       throws 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws java.io.FileNotFoundException If file <code>src</code> is not found
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException create not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.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
+   boolean delete(String src, boolean recursive)
+       throws 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 org.apache.hadoop.security.AccessControlException If access is
+    *           denied
+    * @throws org.apache.hadoop.fs.FileAlreadyExistsException If <code>src</code>
+    *           already exists
+    * @throws java.io.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 org.apache.hadoop.fs.ParentNotDirectoryException If parent of
+    *           <code>src</code> is not a directory
+    * @throws org.apache.hadoop.hdfs.server.namenode.SafeModeException create not
+    *           allowed in safemode
+    * @throws org.apache.hadoop.fs.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 org.apache.hadoop.fs.InvalidPathException If <code>src</code> is
+    *           invalid
+    */
+   @Idempotent
+   boolean mkdirs(String src, FsPermission masked, boolean createParent)
+       throws 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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws java.io.FileNotFoundException file <code>src</code> is not found
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException If <code>src</code>
+    *           contains a symlink
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   DirectoryListing getListing(String src, byte[] startAfter,
+       boolean needLocation) throws 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
+   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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   void renewLease(String clientName) throws 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
+   boolean recoverLease(String src, String clientName) throws IOException;
+ 
+   int GET_STATS_CAPACITY_IDX = 0;
+   int GET_STATS_USED_IDX = 1;
+   int GET_STATS_REMAINING_IDX = 2;
+   int GET_STATS_UNDER_REPLICATED_IDX = 3;
+   int GET_STATS_CORRUPT_BLOCKS_IDX = 4;
+   int GET_STATS_MISSING_BLOCKS_IDX = 5;
+   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
+   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
+   DatanodeInfo[] getDatanodeReport(HdfsConstants.DatanodeReportType type)
+       throws IOException;
+ 
+   /**
+    * Get a report on the current datanode storages.
+    */
+   @Idempotent
+   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 org.apache.hadoop.fs.UnresolvedLinkException if the path contains
+    *           a symlink.
+    */
+   @Idempotent
+   long getPreferredBlockSize(String filename)
+       throws IOException;
+ 
+   /**
+    * 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
+   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.
+    *
+    * @param timeWindow NameNode does a checkpoint if the latest checkpoint was
+    *                   done beyond the given time period (in seconds).
+    * @param txGap NameNode does a checkpoint if the gap between the latest
+    *              checkpoint and the latest transaction id is greater this gap.
+    * @return whether an extra checkpoint has been done
+    *
+    * @throws IOException if image creation failed.
+    */
+   @AtMostOnce
+   boolean saveNamespace(long timeWindow, long txGap) throws IOException;
+ 
+   /**
+    * Roll the edit log.
+    * Requires superuser privileges.
+    *
+    * @throws org.apache.hadoop.security.AccessControlException if the superuser
+    *           privilege is violated
+    * @throws IOException if log roll fails
+    * @return the txid of the new segment
+    */
+   @Idempotent
+   long rollEdits() throws IOException;
+ 
+   /**
+    * Enable/Disable restore failed storage.
+    * <p>
+    * sets flag to enable restore of failed storage replicas
+    *
+    * @throws org.apache.hadoop.security.AccessControlException if the superuser
+    *           privilege is violated.
+    */
+   @Idempotent
+   boolean restoreFailedStorage(String arg) throws IOException;
+ 
+   /**
+    * Tells the namenode to reread the hosts and exclude files.
+    * @throws IOException
+    */
+   @Idempotent
+   void refreshNodes() throws IOException;
+ 
+   /**
+    * Finalize previous upgrade.
+    * Remove file system state saved during the upgrade.
+    * The upgrade will become irreversible.
+    *
+    * @throws IOException
+    */
+   @Idempotent
+   void finalizeUpgrade() throws IOException;
+ 
+   /**
+    * Rolling upgrade operations.
+    * @param action either query, prepare or finalize.
+    * @return rolling upgrade information. On query, if no upgrade is in
+    * progress, returns null.
+    */
+   @Idempotent
+   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
+   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
+   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
+   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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws java.io.FileNotFoundException file <code>src</code> is not found
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException if the path contains
+    *           a symlink.
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   HdfsFileStatus getFileInfo(String src) throws 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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws java.io.FileNotFoundException file <code>src</code> is not found
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException if the path contains
+    *           a symlink.
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   boolean isFileClosed(String src) throws 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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException if <code>src</code>
+    *           contains a symlink
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   HdfsFileStatus getFileLinkInfo(String src) throws IOException;
+ 
+   /**
+    * Get {@link ContentSummary} rooted at the specified directory.
+    * @param path The string representation of the path
+    *
+    * @throws org.apache.hadoop.security.AccessControlException permission denied
+    * @throws java.io.FileNotFoundException file <code>path</code> is not found
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException if <code>path</code>
+    *           contains a symlink.
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   ContentSummary getContentSummary(String path) throws 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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws java.io.FileNotFoundException file <code>path</code> is not found
+    * @throws QuotaExceededException if the directory size
+    *           is greater than the given quota
+    * @throws org.apache.hadoop.fs.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
+   void setQuota(String path, long namespaceQuota, long storagespaceQuota,
+       StorageType type) throws 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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws java.io.FileNotFoundException file <code>src</code> is not found
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException if <code>src</code>
+    *           contains a symlink.
+    * @throws IOException If an I/O error occurred
+    */
+   @Idempotent
+   void fsync(String src, long inodeId, String client, long lastBlockLength)
+       throws 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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws java.io.FileNotFoundException file <code>src</code> is not found
+    * @throws org.apache.hadoop.fs.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
+   void setTimes(String src, long mtime, long atime) throws 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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws org.apache.hadoop.fs.FileAlreadyExistsException If file
+    *           <code>link</code> already exists
+    * @throws java.io.FileNotFoundException If parent of <code>link</code> does
+    *           not exist and <code>createParent</code> is false
+    * @throws org.apache.hadoop.fs.ParentNotDirectoryException If parent of
+    *           <code>link</code> is not a directory.
+    * @throws org.apache.hadoop.fs.UnresolvedLinkException if <code>link</code>
+    *           contains a symlink.
+    * @throws SnapshotAccessControlException if path is in RO snapshot
+    * @throws IOException If an I/O error occurred
+    */
+   @AtMostOnce
+   void createSymlink(String target, String link, FsPermission dirPerm,
+       boolean createParent) throws 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 org.apache.hadoop.security.AccessControlException permission denied
+    * @throws java.io.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
+   String getLinkTarget(String path) throws 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
+   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
+   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
+   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
+   long renewDelegationToken(Token<DelegationTokenIdentifier> token)
+       throws IOException;
+ 
+   /**
+    * Cancel an existing delegation token.
+    *
+    * @param token delegation token
+    * @throws IOException
+    */
+   @Idempotent
+   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
+   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
+   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
+   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
+   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
+   void allowSnapshot(String snapshotRoot)
+       throws IOException;
+ 
+   /**
+    * Disallow snapshot on a directory.
+    * @param snapshotRoot the directory to disallow snapshot
+    * @throws IOException on error
+    */
+   @Idempotent
+   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
+   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
+   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
+   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
+   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
+   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
+   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
+   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
+   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
+   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
+   void modifyAclEntries(String src, List<AclEntry> aclSpec)
+       throws IOException;
+ 
+   /**
+    * Removes ACL entries from files and directories.  Other ACL entries are
+    * retained.
+    */
+   @Idempotent
+   void removeAclEntries(String src, List<AclEntry> aclSpec)
+       throws IOException;
+ 
+   /**
+    * Removes all default ACL entries from files and directories.
+    */
+   @Idempotent
+   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
+   void removeAcl(String src) throws IOException;
+ 
+   /**
+    * Fully replaces ACL of files and directories, discarding all existing
+    * entries.
+    */
+   @Idempotent
+   void setAcl(String src, List<AclEntry> aclSpec) throws IOException;
+ 
+   /**
+    * Gets the ACLs of files and directories.
+    */
+   @Idempotent
+   AclStatus getAclStatus(String src) throws IOException;
+ 
+   /**
+    * Create an encryption zone.
+    */
+   @AtMostOnce
+   void createEncryptionZone(String src, String keyName)
+     throws IOException;
+ 
+   /**
+    * Get the encryption zone for a path.
+    */
+   @Idempotent
+   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
+   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
+   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
+   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
+   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
+   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 org.apache.hadoop.security.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 org.apache.hadoop.security.AccessControlException if access is
+    *           denied
+    * @throws java.io.FileNotFoundException if the path does not exist
+    * @throws IOException see specific implementation
+    */
+   @Idempotent
+   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
+   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
+   EventBatchList getEditsFromTxid(long txid) throws IOException;
++
++  /**
++   * Create an erasure coding zone with specified policy, if any, otherwise
++   * default
++   */
++  @AtMostOnce
++  void createErasureCodingZone(String src, ErasureCodingPolicy ecPolicy)
++      throws IOException;
++
++  /**
++   * Get the erasure coding policies loaded in Namenode
++   *
++   * @throws IOException
++   */
++  @Idempotent
++  ErasureCodingPolicy[] getErasureCodingPolicies() throws IOException;
++
++  /**
++   * Get the information about the EC zone for the path
++   * 
++   * @param src path to get the info for
++   * @throws IOException
++   */
++  @Idempotent
++  ErasureCodingZone getErasureCodingZone(String src) throws IOException;
+ }

http://git-wip-us.apache.org/repos/asf/hadoop/blob/6b6a63bb/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ErasureCodingZone.java
----------------------------------------------------------------------
diff --cc hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ErasureCodingZone.java
index 0000000,0000000..533b630
new file mode 100644
--- /dev/null
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ErasureCodingZone.java
@@@ -1,0 -1,0 +1,54 @@@
++/**
++ * 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;
++
++/**
++ * Information about the EC Zone at the specified path.
++ */
++public class ErasureCodingZone {
++
++  private String dir;
++  private ErasureCodingPolicy ecPolicy;
++
++  public ErasureCodingZone(String dir, ErasureCodingPolicy ecPolicy) {
++    this.dir = dir;
++    this.ecPolicy = ecPolicy;
++  }
++
++  /**
++   * Get directory of the EC zone.
++   * 
++   * @return
++   */
++  public String getDir() {
++    return dir;
++  }
++
++  /**
++   * Get the erasure coding policy for the EC Zone
++   * 
++   * @return
++   */
++  public ErasureCodingPolicy getErasureCodingPolicy() {
++    return ecPolicy;
++  }
++
++  @Override
++  public String toString() {
++    return "Dir: " + getDir() + ", Policy: " + ecPolicy;
++  }
++}

http://git-wip-us.apache.org/repos/asf/hadoop/blob/6b6a63bb/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/HdfsConstants.java
----------------------------------------------------------------------

http://git-wip-us.apache.org/repos/asf/hadoop/blob/6b6a63bb/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/web/JsonUtilClient.java
----------------------------------------------------------------------


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