org.apache.hadoop.dfs
Class DistributedFileSystem

java.lang.Object
  org.apache.hadoop.conf.Configured
      org.apache.hadoop.fs.FileSystem
          org.apache.hadoop.dfs.DistributedFileSystem

All Implemented Interfaces:

Closeable, Configurable

public class DistributedFileSystem
extends FileSystem

Implementation of the abstract FileSystem for the DFS system. This object is the way end-user code interacts with a Hadoop DistributedFileSystem.

Nested Class Summary

static class

DistributedFileSystem.DiskStatus

Nested classes/interfaces inherited from class org.apache.hadoop.fs.FileSystem

FileSystem.Statistics

Field Summary

Fields inherited from class org.apache.hadoop.fs.FileSystem

LOG, statistics

Constructor Summary

DistributedFileSystem()

DistributedFileSystem(InetSocketAddress namenode, Configuration conf)
Deprecated.

Method Summary

FSDataOutputStream	append(Path f, int bufferSize, Progressable progress) This optional operation is not yet supported.
protected void	checkPath(Path path) Permit paths which explicitly specify the default port.
void	close() No more filesystem operations are needed.
FSDataOutputStream	create(Path f, FsPermission permission, boolean overwrite, int bufferSize, short replication, long blockSize, Progressable progress) Opens an FSDataOutputStream at the indicated Path with write-progress reporting.
boolean	delete(Path f) Deprecated.
boolean	delete(Path f, boolean recursive) requires a boolean check to delete a non empty directory recursively.
UpgradeStatusReport	distributedUpgradeProgress(FSConstants.UpgradeAction action)
void	finalizeUpgrade() Finalize previously upgraded files system state.
ContentSummary	getContentSummary(Path f) Return the ContentSummary of a given Path.
DatanodeInfo[]	getDataNodeStats() Return statistics for each datanode.
long	getDefaultBlockSize() Return the number of bytes that large input files should be optimally be split into to minimize i/o time.
short	getDefaultReplication() Get the default replication.
DistributedFileSystem.DiskStatus	getDiskStatus() Return the disk usage of the filesystem, including total capacity, used space, and remaining space
BlockLocation[]	getFileBlockLocations(FileStatus file, long start, long len) Return an array containing hostnames, offset and size of portions of the given file.
FileStatus	getFileStatus(Path f) Returns the stat information about the file.
Path	getHomeDirectory() Return the current user's home directory in this filesystem.
String	getName() Deprecated.
long	getRawCapacity() Return the total raw capacity of the filesystem, disregarding replication .
long	getRawUsed() Return the total raw used space in the filesystem, disregarding replication .
URI	getUri() Returns a URI whose scheme and authority identify this FileSystem.
Path	getWorkingDirectory() Get the current working directory for the given file system
void	initialize(URI uri, Configuration conf) Called after a new FileSystem instance is constructed.
FileStatus[]	listStatus(Path p) List the statuses of the files/directories in the given path if the path is a directory.
void	metaSave(String pathname)
boolean	mkdirs(Path f, FsPermission permission) Make the given file and all non-existent parents into directories.
FSDataInputStream	open(Path f, int bufferSize) Opens an FSDataInputStream at the indicated Path.
void	refreshNodes()
boolean	rename(Path src, Path dst) Rename files/dirs
boolean	reportChecksumFailure(Path f, FSDataInputStream in, long inPos, FSDataInputStream sums, long sumsPos) We need to find the blocks that didn't match.
void	setOwner(Path p, String username, String groupname) Set owner of a path (i.e.
void	setPermission(Path p, FsPermission permission) Set permission of a path.
boolean	setReplication(Path src, short replication) Set replication for an existing file.
boolean	setSafeMode(FSConstants.SafeModeAction action) Enter, leave or get safe mode.
void	setVerifyChecksum(boolean verifyChecksum)
void	setWorkingDirectory(Path dir) Set the current working directory for the given file system.
String	toString()

Methods inherited from class org.apache.hadoop.fs.FileSystem

append, append, closeAll, completeLocalOutput, copyFromLocalFile, copyFromLocalFile, copyFromLocalFile, copyFromLocalFile, copyToLocalFile, copyToLocalFile, create, create, create, create, create, create, create, create, create, create, createNewFile, deleteOnExit, exists, get, get, getBlockSize, getDefaultUri, getFileBlockLocations, getLength, getLocal, getNamed, getReplication, getStatistics, getUsed, globStatus, globStatus, isDirectory, isFile, listStatus, listStatus, listStatus, makeQualified, mkdirs, mkdirs, moveFromLocalFile, moveFromLocalFile, moveToLocalFile, open, parseArgs, printStatistics, processDeleteOnExit, setDefaultUri, setDefaultUri, startLocalOutput

Methods inherited from class org.apache.hadoop.conf.Configured

getConf, setConf

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

DistributedFileSystem

public DistributedFileSystem()

DistributedFileSystem

public DistributedFileSystem(InetSocketAddress namenode,
                             Configuration conf)
                      throws IOException

Deprecated.

Throws:

IOException

Method Detail

getName

public String getName()

Deprecated.

Overrides:

getName in class FileSystem

getUri

public URI getUri()

Description copied from class: FileSystem

Returns a URI whose scheme and authority identify this FileSystem.

Specified by:

getUri in class FileSystem

initialize

public void initialize(URI uri,
                       Configuration conf)
                throws IOException

Description copied from class: FileSystem

Called after a new FileSystem instance is constructed.

Specified by:

initialize in class FileSystem

Parameters:

uri - a uri whose authority section names the host, port, etc. for this FileSystem

conf - the configuration

Throws:

IOException

checkPath

protected void checkPath(Path path)

Permit paths which explicitly specify the default port.

Overrides:

checkPath in class FileSystem

getWorkingDirectory

public Path getWorkingDirectory()

Description copied from class: FileSystem

Get the current working directory for the given file system

Specified by:

getWorkingDirectory in class FileSystem

Returns:

the directory pathname

getDefaultBlockSize

public long getDefaultBlockSize()

Description copied from class: FileSystem

Return the number of bytes that large input files should be optimally be split into to minimize i/o time.

Overrides:

getDefaultBlockSize in class FileSystem

getDefaultReplication

public short getDefaultReplication()

Description copied from class: FileSystem

Get the default replication.

Overrides:

getDefaultReplication in class FileSystem

setWorkingDirectory

public void setWorkingDirectory(Path dir)

Description copied from class: FileSystem

Set the current working directory for the given file system. All relative paths will be resolved relative to it.

Specified by:

setWorkingDirectory in class FileSystem

getHomeDirectory

public Path getHomeDirectory()

Return the current user's home directory in this filesystem. The default implementation returns "/user/$USER/".

Overrides:

getHomeDirectory in class FileSystem

getFileBlockLocations

public BlockLocation[] getFileBlockLocations(FileStatus file,
                                             long start,
                                             long len)
                                      throws IOException

Description copied from class: FileSystem

Return an array containing hostnames, offset and size of portions of the given file. For a nonexistent file or regions, null will be returned. This call is most helpful with DFS, where it returns hostnames of machines that contain the given file. The FileSystem will simply return an elt containing 'localhost'.

Overrides:

getFileBlockLocations in class FileSystem

Throws:

IOException

setVerifyChecksum

public void setVerifyChecksum(boolean verifyChecksum)

open

public FSDataInputStream open(Path f,
                              int bufferSize)
                       throws IOException

Description copied from class: FileSystem

Opens an FSDataInputStream at the indicated Path.

Specified by:

open in class FileSystem

Parameters:

f - the file name to open

bufferSize - the size of the buffer to be used.

Throws:

IOException

append

public FSDataOutputStream append(Path f,
                                 int bufferSize,
                                 Progressable progress)
                          throws IOException

This optional operation is not yet supported.

Specified by:

append in class FileSystem

Parameters:

f - the existing file to be appended.

bufferSize - the size of the buffer to be used.

progress - for reporting progress if it is not null.

Throws:

IOException

create

public FSDataOutputStream create(Path f,
                                 FsPermission permission,
                                 boolean overwrite,
                                 int bufferSize,
                                 short replication,
                                 long blockSize,
                                 Progressable progress)
                          throws IOException

Description copied from class: FileSystem

Opens an FSDataOutputStream at the indicated Path with write-progress reporting.

Specified by:

create in class FileSystem

Parameters:

f - the file name to open

overwrite - if a file with this name already exists, then if true, the file will be overwritten, and if false an error will be thrown.

bufferSize - the size of the buffer to be used.

replication - required block replication for the file.

Throws:

IOException

See Also:

FileSystem.setPermission(Path, FsPermission)

setReplication

public boolean setReplication(Path src,
                              short replication)
                       throws IOException

Description copied from class: FileSystem

Set replication for an existing file.

Overrides:

setReplication in class FileSystem

Parameters:

src - file name

replication - new replication

Returns:

true if successful; false if file does not exist or is a directory

Throws:

IOException

rename

public boolean rename(Path src,
                      Path dst)
               throws IOException

Rename files/dirs

Specified by:

rename in class FileSystem

Throws:

IOException

delete

@Deprecated
public boolean delete(Path f)
               throws IOException

Deprecated.

Get rid of Path f, whether a true file or dir.

Specified by:

delete in class FileSystem

Throws:

IOException

delete

public boolean delete(Path f,
                      boolean recursive)
               throws IOException

requires a boolean check to delete a non empty directory recursively.

Specified by:

delete in class FileSystem

Parameters:

f - the path to delete.

recursive - if path is a directory and set to true, the directory is deleted else throws an exception. In case of a file the recursive can be set to either true or false.

Returns:

true if delete is successful else false.

Throws:

IOException

getContentSummary

public ContentSummary getContentSummary(Path f)
                                 throws IOException

Return the ContentSummary of a given Path.

Overrides:

getContentSummary in class FileSystem

Throws:

IOException

listStatus

public FileStatus[] listStatus(Path p)
                        throws IOException

Description copied from class: FileSystem

List the statuses of the files/directories in the given path if the path is a directory.

Specified by:

listStatus in class FileSystem

Parameters:

p - given path

Returns:

the statuses of the files/directories in the given patch

Throws:

IOException

mkdirs

public boolean mkdirs(Path f,
                      FsPermission permission)
               throws IOException

Description copied from class: FileSystem

Make the given file and all non-existent parents into directories. Has the semantics of Unix 'mkdir -p'. Existence of the directory hierarchy is not an error.

Specified by:

mkdirs in class FileSystem

Throws:

IOException

close

public void close()
           throws IOException

No more filesystem operations are needed. Will release any held locks.

Specified by:

close in interface Closeable

Overrides:

close in class FileSystem

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object

getDiskStatus

public DistributedFileSystem.DiskStatus getDiskStatus()
                                               throws IOException

Return the disk usage of the filesystem, including total capacity, used space, and remaining space

Throws:

IOException

getRawCapacity

public long getRawCapacity()
                    throws IOException

Return the total raw capacity of the filesystem, disregarding replication .

Throws:

IOException

getRawUsed

public long getRawUsed()
                throws IOException

Return the total raw used space in the filesystem, disregarding replication .

Throws:

IOException

getDataNodeStats

public DatanodeInfo[] getDataNodeStats()
                                throws IOException

Return statistics for each datanode.

Throws:

IOException

setSafeMode

public boolean setSafeMode(FSConstants.SafeModeAction action)
                    throws IOException

Enter, leave or get safe mode.

Throws:

IOException

See Also:

ClientProtocol.setSafeMode( FSConstants.SafeModeAction)

refreshNodes

public void refreshNodes()
                  throws IOException

Throws:

IOException

finalizeUpgrade

public void finalizeUpgrade()
                     throws IOException

Finalize previously upgraded files system state.

Throws:

IOException

distributedUpgradeProgress

public UpgradeStatusReport distributedUpgradeProgress(FSConstants.UpgradeAction action)
                                               throws IOException

Throws:

IOException

metaSave

public void metaSave(String pathname)
              throws IOException

Throws:

IOException

reportChecksumFailure

public boolean reportChecksumFailure(Path f,
                                     FSDataInputStream in,
                                     long inPos,
                                     FSDataInputStream sums,
                                     long sumsPos)

We need to find the blocks that didn't match. Likely only one is corrupt but we will report both to the namenode. In the future, we can consider figuring out exactly which block is corrupt.

getFileStatus

public FileStatus getFileStatus(Path f)
                         throws IOException

Returns the stat information about the file.

Specified by:

getFileStatus in class FileSystem

Parameters:

f - The path we want information from

Returns:

a FileStatus object

Throws:

FileNotFoundException - if the file does not exist.

IOException

setPermission

public void setPermission(Path p,
                          FsPermission permission)
                   throws IOException

Set permission of a path.

Overrides:

setPermission in class FileSystem

Throws:

IOException

setOwner

public void setOwner(Path p,
                     String username,
                     String groupname)
              throws IOException

Set owner of a path (i.e. a file or a directory). The parameters username and groupname cannot both be null.

Overrides:

setOwner in class FileSystem

Parameters:

p - The path

username - If it is null, the original username remains unchanged.

groupname - If it is null, the original groupname remains unchanged.

Throws:

IOException