/**
* 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 org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
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.UnresolvedLinkException;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hdfs.DFSConfigKeys;
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.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;
/**********************************************************************
* ClientProtocol is used by user code via
* {@link org.apache.hadoop.hdfs.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 = DFSConfigKeys.DFS_NAMENODE_USER_NAME_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.
*
* @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)
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.
* @return information about the last partial block 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 LocatedBlock append(String src, String clientName)
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;
/**
* 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
* @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.
*
* @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, 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 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 ExtendedBlock blk,
final DatanodeInfo[] existings, 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;
/**
* 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;
/**
* 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 the total used space of the block pool. </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 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;
/**
* @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 diskspaceQuota Limit on disk space occupied all the files under
* this directory.
* <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 diskspaceQuota)
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 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, 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)
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;
}