/**
* 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.avro.reflect.Nullable;
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.FileStatus;
import org.apache.hadoop.fs.FsServerDefaults;
import org.apache.hadoop.fs.Options;
import org.apache.hadoop.fs.UnresolvedLinkException;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.protocol.FSConstants.UpgradeAction;
import org.apache.hadoop.hdfs.server.common.UpgradeStatusReport;
import org.apache.hadoop.hdfs.server.namenode.SafeModeException;
import org.apache.hadoop.io.EnumSetWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.ipc.VersionedProtocol;
import org.apache.hadoop.security.AccessControlException;
import org.apache.hadoop.security.KerberosInfo;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.security.token.TokenInfo;
import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSelector;
/**********************************************************************
* 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.
*
**********************************************************************/
@KerberosInfo(DFSConfigKeys.DFS_NAMENODE_USER_NAME_KEY)
@TokenInfo(DelegationTokenSelector.class)
@InterfaceAudience.Private
@InterfaceStability.Evolving
public interface ClientProtocol extends VersionedProtocol {
/**
* Compared to the previous version the following changes have been introduced:
* (Only the latest change is reflected.
* The log of historical changes can be retrieved from the svn).
* 60: Replace full getListing with iterative getListinng.
*/
public static final long versionID = 60L;
///////////////////////////////////////
// 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 IOException
* @throws UnresolvedLinkException if the path contains a symlink.
* @throws FileNotFoundException if the path does not exist.
*/
@Nullable
public LocatedBlocks getBlockLocations(String src,
long offset,
long length)
throws IOException, UnresolvedLinkException, FileNotFoundException;
/**
* Get server default values for a number of configuration params.
* @return a set of server default configuration values
* @throws IOException
*/
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(String, String, Block, DatanodeInfo[])}.
*
* @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.
*
* @throws AccessControlException if permission to create file is
* denied by the system. As usually on the client side the exception will
* be wrapped into {@link org.apache.hadoop.ipc.RemoteException}.
* @throws QuotaExceededException if the file creation violates
* any quota restriction
* @throws IOException if other errors occur.
* @throws UnresolvedLinkException if the path contains a symlink.
* @throws AlreadyBeingCreatedException if the path does not exist.
* @throws NSQuotaExceededException if the namespace quota is exceeded.
*/
public void create(String src,
FsPermission masked,
String clientName,
EnumSetWritable<CreateFlag> flag,
boolean createParent,
short replication,
long blockSize)
throws IOException, UnresolvedLinkException,
AlreadyBeingCreatedException, NSQuotaExceededException;
/**
* 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 IOException if other errors occur.
* @throws UnresolvedLinkException if the path contains a symlink.
*/
public LocatedBlock append(String src, String clientName)
throws IOException, UnresolvedLinkException;
/**
* 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
* @throws IOException
* @return true if successful;
* false if file does not exist or is a directory
* @throws UnresolvedLinkException if the path contains a symlink.
*/
public boolean setReplication(String src, short replication)
throws IOException, UnresolvedLinkException;
/**
* Set permissions for an existing file/directory.
* @throws UnresolvedLinkException if the path contains a symlink.
*/
public void setPermission(String src, FsPermission permission)
throws IOException, UnresolvedLinkException, SafeModeException;
/**
* 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 UnresolvedLinkException if the path contains a symlink.
*/
public void setOwner(String src, String username, String groupname)
throws IOException, UnresolvedLinkException;
/**
* 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 UnresolvedLinkException if the path contains a symlink.
*/
public void abandonBlock(Block b, String src, String holder)
throws IOException, UnresolvedLinkException;
/**
* 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 excludedNodes a list of nodes that should not be
* allocated for the current block
* @return LocatedBlock allocated block information.
* @throws UnresolvedLinkException if the path contains a symlink.
* @throws DSQuotaExceededException if the directory's quota is exceeded.
*/
public LocatedBlock addBlock(String src, String clientName,
@Nullable Block previous,
@Nullable DatanodeInfo[] excludedNodes)
throws IOException, UnresolvedLinkException, DSQuotaExceededException;
/**
* 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 the 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.
* @throws UnresolvedLinkException if the path contains a symlink.
*/
public boolean complete(String src, String clientName, Block last)
throws IOException, UnresolvedLinkException;
/**
* The client wants to report corrupted blocks (blocks with specified
* locations on datanodes).
* @param blocks Array of located blocks to report
*/
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 IOException if the new name is invalid.
* @throws UnresolvedLinkException if the path contains a symlink.
* @throws QuotaExceededException if the rename would violate
* any quota restriction
* @deprecated Use {@link #rename(String, String, Options.Rename...)} instead.
*/
@Deprecated
public boolean rename(String src, String dst)
throws IOException, UnresolvedLinkException;
/**
* 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 the path contains a symlink.
* @throws QuotaExceededException if the rename would violate
* any quota restriction
*/
public void concat(String trg, String[] srcs)
throws IOException, UnresolvedLinkException;
/**
* 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 IOException if rename failed
* @throws UnresolvedLinkException if the path contains a symlink.
*/
public void rename(String src, String dst, Options.Rename... options)
throws IOException, UnresolvedLinkException;
/**
* Delete the given file or directory from the file system.
* <p>
* Any blocks belonging to the deleted files will be garbage-collected.
*
* @param src existing name.
* @return true only if the existing file or directory was actually removed
* from the file system.
* @throws UnresolvedLinkException if the path contains a symlink.
* @deprecated use {@link #delete(String, boolean)} istead.
*/
@Deprecated
public boolean delete(String src)
throws IOException, UnresolvedLinkException;
/**
* 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 UnresolvedLinkException if the path contains a symlink.
*/
public boolean delete(String src, boolean recursive)
throws IOException, UnresolvedLinkException;
/**
* 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 UnresolvedLinkException if the path contains a symlink.
* @throws {@link AccessControlException} if permission to create file is
* denied by the system. As usually on the client side the exception will
* be wraped into {@link org.apache.hadoop.ipc.RemoteException}.
* @throws QuotaExceededException if the operation would violate
* any quota restriction.
*/
public boolean mkdirs(String src, FsPermission masked, boolean createParent)
throws IOException, UnresolvedLinkException, NSQuotaExceededException;
/**
* 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
* @return a partial listing starting after startAfter
* @throws UnresolvedLinkException if the path contains a symlink.
*/
public DirectoryListing getListing(String src, byte[] startAfter)
throws IOException, UnresolvedLinkException;
///////////////////////////////////////
// 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 UnresolvedLinkException if the path contains a symlink.
*/
public void renewLease(String clientName)
throws IOException, UnresolvedLinkException;
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 three 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>
* </ul>
* Use public constants like {@link #GET_STATS_CAPACITY_IDX} in place of
* actual numbers to index into the array.
*/
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.
*/
public DatanodeInfo[] getDatanodeReport(FSConstants.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.
*/
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(FSConstants.SafeModeAction) setSafeMode(SafeModeAction.SAFEMODE_GET)}.
* <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(FSConstants.SafeModeAction) setSafeMode(SafeModeAction.SAFEMODE_ENTER)}
* then the name node stays in safe mode until it is manually turned off
* using {@link #setSafeMode(FSConstants.SafeModeAction) setSafeMode(SafeModeAction.SAFEMODE_LEAVE)}.
* Current state of the name node can be verified using
* {@link #setSafeMode(FSConstants.SafeModeAction) setSafeMode(SafeModeAction.SAFEMODE_GET)}
* <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>
* @return <ul><li>0 if the safe mode is OFF or</li>
* <li>1 if the safe mode is ON.</li></ul>
* @throws IOException
*/
public boolean setSafeMode(FSConstants.SafeModeAction action) 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.
*/
public void saveNamespace() throws IOException;
/**
* Enable/Disable restore failed storage.
* <p>
* sets flag to enable restore of failed storage replicas
*
* @throws AccessControlException if the superuser privilege is violated.
*/
public boolean restoreFailedStorage(String arg) throws AccessControlException;
/**
* Tells the namenode to reread the hosts and exclude files.
* @throws IOException
*/
public void refreshNodes() throws IOException;
/**
* Finalize previous upgrade.
* Remove file system state saved during the upgrade.
* The upgrade will become irreversible.
*
* @throws IOException
*/
public void finalizeUpgrade() throws IOException;
/**
* Report distributed upgrade progress or force current upgrade to proceed.
*
* @param action {@link FSConstants.UpgradeAction} to perform
* @return upgrade status information or null if no upgrades are in progress
* @throws IOException
*/
@Nullable
public UpgradeStatusReport distributedUpgradeProgress(UpgradeAction action)
throws IOException;
/**
* Dumps namenode data structures into specified file. If the file
* already exists, then append.
* @throws IOException
*/
public void metaSave(String filename) throws IOException;
/**
* @return Array of FileStatus objects referring to corrupted files.
* The server could return all or a few of the files that are corrupt.
* @throws AccessControlException
* @throws IOException
*/
FileStatus[] getCorruptFiles()
throws AccessControlException, IOException;
/**
* Get the file info for a specific file or directory.
* @param src The string representation of the path to the file
* @throws UnresolvedLinkException if the path contains symlinks;
* IOException if permission to access file is denied by the system
* @return object containing information regarding the file
* or null if file not found
*/
@Nullable
public HdfsFileStatus getFileInfo(String src)
throws IOException, UnresolvedLinkException;
/**
* 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
* @throws UnresolvedLinkException if the path contains symlinks;
* IOException if permission to access file is denied by the system
* @return object containing information regarding the file
* or null if file not found
*/
public HdfsFileStatus getFileLinkInfo(String src)
throws IOException, UnresolvedLinkException;
/**
* Get {@link ContentSummary} rooted at the specified directory.
* @param path The string representation of the path
* @throws UnresolvedLinkException if the path contains a symlink.
*/
public ContentSummary getContentSummary(String path)
throws IOException, UnresolvedLinkException;
/**
* 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 FSConstants#QUOTA_DONT_SET} implies
* the quota will not be changed, and (3) {@link FSConstants#QUOTA_RESET}
* implies the quota will be reset. Any other value is a runtime error.
* @throws UnresolvedLinkException if the path contains a symlink.
* @throws FileNotFoundException if the path is a file or
* does not exist
* @throws QuotaExceededException if the directory size
* is greater than the given quota
*/
public void setQuota(String path, long namespaceQuota, long diskspaceQuota)
throws IOException, UnresolvedLinkException,
FileNotFoundException, SafeModeException;
/**
* 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
* @throws UnresolvedLinkException if the path contains a symlink.
*/
public void fsync(String src, String client)
throws IOException, UnresolvedLinkException;
/**
* 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 UnresolvedLinkException if the path contains a symlink.
*/
public void setTimes(String src, long mtime, long atime)
throws IOException, UnresolvedLinkException;
/**
* Create a symbolic link to a file or directory.
* @param target The pathname of the destination that the
* link points to.
* @param link The pathname 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 IOException
* @throws UnresolvedLinkException if the path contains a symlink.
*/
public void createSymlink(String target, String link, FsPermission dirPerm,
boolean createParent) throws IOException, UnresolvedLinkException;
/**
* Resolve the first symbolic link on the specified path.
* @param path The pathname that needs to be resolved
* @return The pathname after resolving the first symbolic link if any.
* @throws IOException
*/
public 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
*/
public LocatedBlock updateBlockForPipeline(Block 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
*/
public void updatePipeline(String clientName, Block oldBlock,
Block newBlock, DatanodeID[] newNodes)
throws IOException;
/**
* Get a valid Delegation Token.
*
* @param renewer the designated renewer for the token
* @return Token<DelegationTokenIdentifier>
* @throws IOException
*/
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
*/
public long renewDelegationToken(Token<DelegationTokenIdentifier> token)
throws IOException;
/**
* Cancel an existing delegation token.
*
* @param token delegation token
* @throws IOException
*/
public void cancelDelegationToken(Token<DelegationTokenIdentifier> token)
throws IOException;
}