ViewFs (Apache Hadoop Main 3.1.4 API)

java.lang.Object
- org.apache.hadoop.fs.AbstractFileSystem
- - org.apache.hadoop.fs.viewfs.ViewFs

```
@InterfaceAudience.Public
 @InterfaceStability.Evolving
public class ViewFs
extends AbstractFileSystem
```
ViewFs (extends the AbstractFileSystem interface) implements a client-side mount table. The viewFs file system is implemented completely in memory on the client side. The client-side mount table allows a client to provide a customized view of a file system namespace that is composed from one or more individual file systems (a localFs or Hdfs, S3fs, etc). For example one could have a mount table that provides links such as
- /user -> hdfs://nnContainingUserDir/user
- /project/foo -> hdfs://nnProject1/projects/foo
- /project/bar -> hdfs://nnProject2/projects/bar
- /tmp -> hdfs://nnTmp/privateTmpForUserXXX
ViewFs is specified with the following URI: viewfs:///
To use viewfs one would typically set the default file system in the config (i.e. fs.defaultFS < = viewfs:///) along with the mount table config variables as described below.
** Config variables to specify the mount table entries **
The file system is initialized from the standard Hadoop config through config variables. See FsConstants for URI and Scheme constants; See Constants for config var constants; see ConfigUtil for convenient lib.
All the mount table config entries for view fs are prefixed by fs.viewfs.mounttable. For example the above example can be specified with the following config variables:
- fs.viewfs.mounttable.default.link./user= hdfs://nnContainingUserDir/user
- fs.viewfs.mounttable.default.link./project/foo= hdfs://nnProject1/projects/foo
- fs.viewfs.mounttable.default.link./project/bar= hdfs://nnProject2/projects/bar
- fs.viewfs.mounttable.default.link./tmp= hdfs://nnTmp/privateTmpForUserXXX
The default mount table (when no authority is specified) is from config variables prefixed by fs.viewFs.mounttable.default The authority component of a URI can be used to specify a different mount table. For example,
- viewfs://sanjayMountable/
is initialized from fs.viewFs.mounttable.sanjayMountable.* config variables.
**** Merge Mounts **** (NOTE: merge mounts are not implemented yet.)
One can also use "MergeMounts" to merge several directories (this is sometimes called union-mounts or junction-mounts in the literature. For example of the home directories are stored on say two file systems (because they do not fit on one) then one could specify a mount entry such as following merges two dirs:
- /user -> hdfs://nnUser1/user,hdfs://nnUser2/user
Such a mergeLink can be specified with the following config var where "," is used as the separator for each of links to be merged:
- fs.viewfs.mounttable.default.linkMerge./user= hdfs://nnUser1/user,hdfs://nnUser1/user
A special case of the merge mount is where mount table's root is merged with the root (slash) of another file system:
- fs.viewfs.mounttable.default.linkMergeSlash=hdfs://nn99/
In this cases the root of the mount table is merged with the root of hdfs://nn99/

Field Summary
- Fields inherited from class org.apache.hadoop.fs.AbstractFileSystem
  statistics

Constructor Summary

Constructors
Constructor and Description

ViewFs(Configuration conf)

Constructors
Constructor and Description
`ViewFs(Configuration conf)`

Method Summary

All Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`void`	`access(Path path, FsAction mode)` The specification of this method matches that of `FileContext.access(Path, FsAction)` except that an UnresolvedLinkException may be thrown if a symlink is encountered in the path.
`FSDataOutputStream`	`createInternal(Path f, EnumSet<CreateFlag> flag, FsPermission absolutePermission, int bufferSize, short replication, long blockSize, Progressable progress, org.apache.hadoop.fs.Options.ChecksumOpt checksumOpt, boolean createParent)` The specification of this method matches that of `AbstractFileSystem.create(Path, EnumSet, Options.CreateOpts...)` except that the opts have been declared explicitly.
`Path`	`createSnapshot(Path path, String snapshotName)` The specification of this method matches that of `FileContext.createSnapshot(Path, String)`.
`void`	`createSymlink(Path target, Path link, boolean createParent)` The specification of this method matches that of `FileContext.createSymlink(Path, Path, boolean)`;
`boolean`	`delete(Path f, boolean recursive)` The specification of this method matches that of `FileContext.delete(Path, boolean)` except that Path f must be for this file system.
`void`	`deleteSnapshot(Path path, String snapshotName)` The specification of this method matches that of `FileContext.deleteSnapshot(Path, String)`.
`AclStatus`	`getAclStatus(Path path)` Gets the ACLs of files and directories.
`List<Token<?>>`	`getDelegationTokens(String renewer)` Get one or more delegation tokens associated with the filesystem.
`BlockLocation[]`	`getFileBlockLocations(Path f, long start, long len)` The specification of this method matches that of `FileContext.getFileBlockLocations(Path, long, long)` except that Path f must be for this file system.
`FileChecksum`	`getFileChecksum(Path f)` The specification of this method matches that of `FileContext.getFileChecksum(Path)` except that Path f must be for this file system.
`FileStatus`	`getFileLinkStatus(Path f)` The specification of this method matches that of `FileContext.getFileLinkStatus(Path)` except that an UnresolvedLinkException may be thrown if a symlink is encountered in the path leading up to the final path component.
`FileStatus`	`getFileStatus(Path f)` The specification of this method matches that of `FileContext.getFileStatus(Path)` except that an UnresolvedLinkException may be thrown if a symlink is encountered in the path.
`FsStatus`	`getFsStatus()` The specification of this method matches that of `FileContext.getFsStatus(Path)`.
`Path`	`getHomeDirectory()` Return the current user's home directory in this file system.
`Path`	`getLinkTarget(Path f)` Partially resolves the path.
`org.apache.hadoop.fs.viewfs.ViewFs.MountPoint[]`	`getMountPoints()`
`FsServerDefaults`	`getServerDefaults()` Deprecated.
`FsServerDefaults`	`getServerDefaults(Path f)` Return a set of server default configuration values based on path.
`BlockStoragePolicySpi`	`getStoragePolicy(Path src)` Retrieve the storage policy for a given file or directory.
`int`	`getUriDefaultPort()` The default port of this file system.
`byte[]`	`getXAttr(Path path, String name)` Get an xattr for a file or directory.
`Map<String,byte[]>`	`getXAttrs(Path path)` Get all of the xattrs for a file or directory.
`Map<String,byte[]>`	`getXAttrs(Path path, List<String> names)` Get all of the xattrs for a file or directory.
`boolean`	`isValidName(String src)` Returns true if the specified string is considered valid in the path part of a URI by this file system.
`org.apache.hadoop.fs.RemoteIterator<LocatedFileStatus>`	`listLocatedStatus(Path f)` The specification of this method matches that of `FileContext.listLocatedStatus(Path)` except that Path f must be for this file system.
`FileStatus[]`	`listStatus(Path f)` The specification of this method matches that of `FileContext.Util.listStatus(Path)` except that Path f must be for this file system.
`org.apache.hadoop.fs.RemoteIterator<FileStatus>`	`listStatusIterator(Path f)` The specification of this method matches that of `FileContext.listStatus(Path)` except that Path f must be for this file system.
`List<String>`	`listXAttrs(Path path)` Get all of the xattr names for a file or directory.
`void`	`mkdir(Path dir, FsPermission permission, boolean createParent)` The specification of this method matches that of `FileContext.mkdir(Path, FsPermission, boolean)` except that the Path f must be fully qualified and the permission is absolute (i.e.
`void`	`modifyAclEntries(Path path, List<AclEntry> aclSpec)` Modifies ACL entries of files and directories.
`FSDataInputStream`	`open(Path f, int bufferSize)` The specification of this method matches that of `FileContext.open(Path, int)` except that Path f must be for this file system.
`void`	`removeAcl(Path path)` Removes all but the base ACL entries of files and directories.
`void`	`removeAclEntries(Path path, List<AclEntry> aclSpec)` Removes ACL entries from files and directories.
`void`	`removeDefaultAcl(Path path)` Removes all default ACL entries from files and directories.
`void`	`removeXAttr(Path path, String name)` Remove an xattr of a file or directory.
`void`	`renameInternal(Path src, Path dst)` The specification of this method matches that of `FileContext.rename(Path, Path, Options.Rename...)` except that Path f must be for this file system and NO OVERWRITE is performed.
`void`	`renameInternal(Path src, Path dst, boolean overwrite)` The specification of this method matches that of `FileContext.rename(Path, Path, Options.Rename...)` except that Path f must be for this file system.
`void`	`renameSnapshot(Path path, String snapshotOldName, String snapshotNewName)` The specification of this method matches that of `FileContext.renameSnapshot(Path, String, String)`.
`Path`	`resolvePath(Path f)` Return the fully-qualified path of path f resolving the path through any internal symlinks or mount point
`void`	`setAcl(Path path, List<AclEntry> aclSpec)` Fully replaces ACL of files and directories, discarding all existing entries.
`void`	`setOwner(Path f, String username, String groupname)` The specification of this method matches that of `FileContext.setOwner(Path, String, String)` except that Path f must be for this file system.
`void`	`setPermission(Path f, FsPermission permission)` The specification of this method matches that of `FileContext.setPermission(Path, FsPermission)` except that Path f must be for this file system.
`boolean`	`setReplication(Path f, short replication)` The specification of this method matches that of `FileContext.setReplication(Path, short)` except that Path f must be for this file system.
`void`	`setStoragePolicy(Path path, String policyName)` Set the storage policy for a given file or directory.
`void`	`setTimes(Path f, long mtime, long atime)` The specification of this method matches that of `FileContext.setTimes(Path, long, long)` except that Path f must be for this file system.
`void`	`setVerifyChecksum(boolean verifyChecksum)` The specification of this method matches that of `FileContext.setVerifyChecksum(boolean, Path)` except that Path f must be for this file system.
`void`	`setXAttr(Path path, String name, byte[] value, EnumSet<XAttrSetFlag> flag)` Set an xattr of a file or directory.
`boolean`	`supportsSymlinks()` Returns true if the file system supports symlinks, false otherwise.
`boolean`	`truncate(Path f, long newLength)` The specification of this method matches that of `FileContext.truncate(Path, long)` except that Path f must be for this file system.
`void`	`unsetStoragePolicy(Path src)` Unset the storage policy set for a given file or directory.

Methods inherited from class org.apache.hadoop.fs.AbstractFileSystem
checkPath, checkScheme, clearStatistics, create, createFileSystem, equals, get, getAllStatistics, getAllStoragePolicies, getCanonicalServiceName, getFsStatus, getInitialWorkingDirectory, getStatistics, getStatistics, getUri, getUriPath, hashCode, listCorruptFileBlocks, makeQualified, open, printStatistics, rename, setXAttr

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - ViewFs
```
public ViewFs(Configuration conf)
       throws IOException,
              URISyntaxException
```
    Throws:
    
    IOException
    
    URISyntaxException
- Method Detail
  - getServerDefaults
```
@Deprecated
public FsServerDefaults getServerDefaults()
                                               throws IOException
```
    Deprecated.
    
    Description copied from class: AbstractFileSystem
    
    Return a set of server default configuration values.
    
    Specified by:
    
    getServerDefaults in class AbstractFileSystem
    
    Returns:
    
    server default configuration values
    
    Throws:
    
    IOException - an I/O error occurred
  - getServerDefaults
```
public FsServerDefaults getServerDefaults(Path f)
                                   throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Return a set of server default configuration values based on path.
    
    Overrides:
    
    getServerDefaults in class AbstractFileSystem
    
    Parameters:
    
    f - path to fetch server defaults
    
    Returns:
    
    server default configuration values for path
    
    Throws:
    
    IOException - an I/O error occurred
  - getUriDefaultPort
```
public int getUriDefaultPort()
```
    Description copied from class: AbstractFileSystem
    
    The default port of this file system.
    
    Specified by:
    
    getUriDefaultPort in class AbstractFileSystem
    
    Returns:
    
    default port of this file system's Uri scheme A uri with a port of -1 => default port;
  - getHomeDirectory
```
public Path getHomeDirectory()
```
    Description copied from class: AbstractFileSystem
    
    Return the current user's home directory in this file system. The default implementation returns "/user/$USER/".
    
    Overrides:
    
    getHomeDirectory in class AbstractFileSystem
    
    Returns:
    
    current user's home directory.
  - resolvePath
```
public Path resolvePath(Path f)
                 throws FileNotFoundException,
                        AccessControlException,
                        org.apache.hadoop.fs.UnresolvedLinkException,
                        IOException
```
    Description copied from class: AbstractFileSystem
    
    Return the fully-qualified path of path f resolving the path through any internal symlinks or mount point
    
    Overrides:
    
    resolvePath in class AbstractFileSystem
    
    Parameters:
    
    f - path to be resolved
    
    Returns:
    
    fully qualified path
    
    Throws:
    
    FileNotFoundException
    
    AccessControlException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - createInternal
```
public FSDataOutputStream createInternal(Path f,
                                         EnumSet<CreateFlag> flag,
                                         FsPermission absolutePermission,
                                         int bufferSize,
                                         short replication,
                                         long blockSize,
                                         Progressable progress,
                                         org.apache.hadoop.fs.Options.ChecksumOpt checksumOpt,
                                         boolean createParent)
                                  throws AccessControlException,
                                         FileAlreadyExistsException,
                                         FileNotFoundException,
                                         ParentNotDirectoryException,
                                         UnsupportedFileSystemException,
                                         org.apache.hadoop.fs.UnresolvedLinkException,
                                         IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of AbstractFileSystem.create(Path, EnumSet, Options.CreateOpts...) except that the opts have been declared explicitly.
    
    Specified by:
    
    createInternal in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileAlreadyExistsException
    
    FileNotFoundException
    
    ParentNotDirectoryException
    
    UnsupportedFileSystemException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - delete
```
public boolean delete(Path f,
                      boolean recursive)
               throws AccessControlException,
                      FileNotFoundException,
                      org.apache.hadoop.fs.UnresolvedLinkException,
                      IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.delete(Path, boolean) except that Path f must be for this file system.
    
    Specified by:
    
    delete in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - getFileBlockLocations
```
public BlockLocation[] getFileBlockLocations(Path f,
                                             long start,
                                             long len)
                                      throws AccessControlException,
                                             FileNotFoundException,
                                             org.apache.hadoop.fs.UnresolvedLinkException,
                                             IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.getFileBlockLocations(Path, long, long) except that Path f must be for this file system.
    
    Specified by:
    
    getFileBlockLocations in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - getFileChecksum
```
public FileChecksum getFileChecksum(Path f)
                             throws AccessControlException,
                                    FileNotFoundException,
                                    org.apache.hadoop.fs.UnresolvedLinkException,
                                    IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.getFileChecksum(Path) except that Path f must be for this file system.
    
    Specified by:
    
    getFileChecksum in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - getFileStatus
```
public FileStatus getFileStatus(Path f)
                         throws AccessControlException,
                                FileNotFoundException,
                                org.apache.hadoop.fs.UnresolvedLinkException,
                                IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.getFileStatus(Path) except that an UnresolvedLinkException may be thrown if a symlink is encountered in the path.
    
    Specified by:
    
    getFileStatus in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - access
```
public void access(Path path,
                   FsAction mode)
            throws AccessControlException,
                   FileNotFoundException,
                   org.apache.hadoop.fs.UnresolvedLinkException,
                   IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.access(Path, FsAction) except that an UnresolvedLinkException may be thrown if a symlink is encountered in the path.
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - getFileLinkStatus
```
public FileStatus getFileLinkStatus(Path f)
                             throws AccessControlException,
                                    FileNotFoundException,
                                    UnsupportedFileSystemException,
                                    IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.getFileLinkStatus(Path) except that an UnresolvedLinkException may be thrown if a symlink is encountered in the path leading up to the final path component. If the file system does not support symlinks then the behavior is equivalent to AbstractFileSystem.getFileStatus(Path).
    
    Overrides:
    
    getFileLinkStatus in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    UnsupportedFileSystemException
    
    IOException
  - getFsStatus
```
public FsStatus getFsStatus()
                     throws AccessControlException,
                            FileNotFoundException,
                            IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.getFsStatus(Path).
    
    Specified by:
    
    getFsStatus in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    IOException
  - listStatusIterator
```
public org.apache.hadoop.fs.RemoteIterator<FileStatus> listStatusIterator(Path f)
                                                                   throws AccessControlException,
                                                                          FileNotFoundException,
                                                                          org.apache.hadoop.fs.UnresolvedLinkException,
                                                                          IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.listStatus(Path) except that Path f must be for this file system.
    
    Overrides:
    
    listStatusIterator in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - listLocatedStatus
```
public org.apache.hadoop.fs.RemoteIterator<LocatedFileStatus> listLocatedStatus(Path f)
                                                                         throws AccessControlException,
                                                                                FileNotFoundException,
                                                                                org.apache.hadoop.fs.UnresolvedLinkException,
                                                                                IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.listLocatedStatus(Path) except that Path f must be for this file system. In HDFS implementation, the BlockLocation of returned LocatedFileStatus will have different formats for replicated and erasure coded file. Please refer to FileSystem.getFileBlockLocations(FileStatus, long, long) for more details.
    
    Overrides:
    
    listLocatedStatus in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - listStatus
```
public FileStatus[] listStatus(Path f)
                        throws AccessControlException,
                               FileNotFoundException,
                               org.apache.hadoop.fs.UnresolvedLinkException,
                               IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.Util.listStatus(Path) except that Path f must be for this file system.
    
    Specified by:
    
    listStatus in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - mkdir
```
public void mkdir(Path dir,
                  FsPermission permission,
                  boolean createParent)
           throws AccessControlException,
                  FileAlreadyExistsException,
                  FileNotFoundException,
                  org.apache.hadoop.fs.UnresolvedLinkException,
                  IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.mkdir(Path, FsPermission, boolean) except that the Path f must be fully qualified and the permission is absolute (i.e. umask has been applied).
    
    Specified by:
    
    mkdir in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileAlreadyExistsException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - open
```
public FSDataInputStream open(Path f,
                              int bufferSize)
                       throws AccessControlException,
                              FileNotFoundException,
                              org.apache.hadoop.fs.UnresolvedLinkException,
                              IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.open(Path, int) except that Path f must be for this file system.
    
    Specified by:
    
    open in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - truncate
```
public boolean truncate(Path f,
                        long newLength)
                 throws AccessControlException,
                        FileNotFoundException,
                        org.apache.hadoop.fs.UnresolvedLinkException,
                        IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.truncate(Path, long) except that Path f must be for this file system.
    
    Overrides:
    
    truncate in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - renameInternal
```
public void renameInternal(Path src,
                           Path dst,
                           boolean overwrite)
                    throws IOException,
                           org.apache.hadoop.fs.UnresolvedLinkException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.rename(Path, Path, Options.Rename...) except that Path f must be for this file system.
    
    Overrides:
    
    renameInternal in class AbstractFileSystem
    
    Throws:
    
    IOException
    
    org.apache.hadoop.fs.UnresolvedLinkException
  - renameInternal
```
public void renameInternal(Path src,
                           Path dst)
                    throws AccessControlException,
                           FileAlreadyExistsException,
                           FileNotFoundException,
                           ParentNotDirectoryException,
                           org.apache.hadoop.fs.UnresolvedLinkException,
                           IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.rename(Path, Path, Options.Rename...) except that Path f must be for this file system and NO OVERWRITE is performed. File systems that do not have a built in overwrite need implement only this method and can take advantage of the default impl of the other AbstractFileSystem.renameInternal(Path, Path, boolean)
    
    Specified by:
    
    renameInternal in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileAlreadyExistsException
    
    FileNotFoundException
    
    ParentNotDirectoryException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - supportsSymlinks
```
public boolean supportsSymlinks()
```
    Description copied from class: AbstractFileSystem
    
    Returns true if the file system supports symlinks, false otherwise.
    
    Overrides:
    
    supportsSymlinks in class AbstractFileSystem
    
    Returns:
    
    true if filesystem supports symlinks
  - createSymlink
```
public void createSymlink(Path target,
                          Path link,
                          boolean createParent)
                   throws IOException,
                          org.apache.hadoop.fs.UnresolvedLinkException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.createSymlink(Path, Path, boolean);
    
    Overrides:
    
    createSymlink in class AbstractFileSystem
    
    Throws:
    
    IOException
    
    org.apache.hadoop.fs.UnresolvedLinkException
  - getLinkTarget
```
public Path getLinkTarget(Path f)
                   throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Partially resolves the path. This is used during symlink resolution in FSLinkResolver, and differs from the similarly named method FileContext.getLinkTarget(Path).
    
    Overrides:
    
    getLinkTarget in class AbstractFileSystem
    
    Throws:
    
    IOException - subclass implementations may throw IOException
  - setOwner
```
public void setOwner(Path f,
                     String username,
                     String groupname)
              throws AccessControlException,
                     FileNotFoundException,
                     org.apache.hadoop.fs.UnresolvedLinkException,
                     IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.setOwner(Path, String, String) except that Path f must be for this file system.
    
    Specified by:
    
    setOwner in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - setPermission
```
public void setPermission(Path f,
                          FsPermission permission)
                   throws AccessControlException,
                          FileNotFoundException,
                          org.apache.hadoop.fs.UnresolvedLinkException,
                          IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.setPermission(Path, FsPermission) except that Path f must be for this file system.
    
    Specified by:
    
    setPermission in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - setReplication
```
public boolean setReplication(Path f,
                              short replication)
                       throws AccessControlException,
                              FileNotFoundException,
                              org.apache.hadoop.fs.UnresolvedLinkException,
                              IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.setReplication(Path, short) except that Path f must be for this file system.
    
    Specified by:
    
    setReplication in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - setTimes
```
public void setTimes(Path f,
                     long mtime,
                     long atime)
              throws AccessControlException,
                     FileNotFoundException,
                     org.apache.hadoop.fs.UnresolvedLinkException,
                     IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.setTimes(Path, long, long) except that Path f must be for this file system.
    
    Specified by:
    
    setTimes in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    org.apache.hadoop.fs.UnresolvedLinkException
    
    IOException
  - setVerifyChecksum
```
public void setVerifyChecksum(boolean verifyChecksum)
                       throws AccessControlException,
                              IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.setVerifyChecksum(boolean, Path) except that Path f must be for this file system.
    
    Specified by:
    
    setVerifyChecksum in class AbstractFileSystem
    
    Throws:
    
    AccessControlException
    
    IOException
  - getMountPoints
```
public org.apache.hadoop.fs.viewfs.ViewFs.MountPoint[] getMountPoints()
```
  - getDelegationTokens
```
public List<Token<?>> getDelegationTokens(String renewer)
                                   throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Get one or more delegation tokens associated with the filesystem. Normally a file system returns a single delegation token. A file system that manages multiple file systems underneath, could return set of delegation tokens for all the file systems it manages
    
    Parameters:
    
    renewer - the account name that is allowed to renew the token.
    
    Returns:
    
    List of delegation tokens. If delegation tokens not supported then return a list of size zero.
    
    Throws:
    
    IOException
  - isValidName
```
public boolean isValidName(String src)
```
    Description copied from class: AbstractFileSystem
    
    Returns true if the specified string is considered valid in the path part of a URI by this file system. The default implementation enforces the rules of HDFS, but subclasses may override this method to implement specific validation rules for specific file systems.
    
    Overrides:
    
    isValidName in class AbstractFileSystem
    
    Parameters:
    
    src - String source filename to check, path part of the URI
    
    Returns:
    
    boolean true if the specified string is considered valid
  - modifyAclEntries
```
public void modifyAclEntries(Path path,
                             List<AclEntry> aclSpec)
                      throws IOException
```
    Description copied from class: AbstractFileSystem
    
    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.)
    
    Overrides:
    
    modifyAclEntries in class AbstractFileSystem
    
    Parameters:
    
    path - Path to modify
    
    aclSpec - List describing modifications
    
    Throws:
    
    IOException - if an ACL could not be modified
  - removeAclEntries
```
public void removeAclEntries(Path path,
                             List<AclEntry> aclSpec)
                      throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Removes ACL entries from files and directories. Other ACL entries are retained.
    
    Overrides:
    
    removeAclEntries in class AbstractFileSystem
    
    Parameters:
    
    path - Path to modify
    
    aclSpec - List describing entries to remove
    
    Throws:
    
    IOException - if an ACL could not be modified
  - removeDefaultAcl
```
public void removeDefaultAcl(Path path)
                      throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Removes all default ACL entries from files and directories.
    
    Overrides:
    
    removeDefaultAcl in class AbstractFileSystem
    
    Parameters:
    
    path - Path to modify
    
    Throws:
    
    IOException - if an ACL could not be modified
  - removeAcl
```
public void removeAcl(Path path)
               throws IOException
```
    Description copied from class: AbstractFileSystem
    
    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.
    
    Overrides:
    
    removeAcl in class AbstractFileSystem
    
    Parameters:
    
    path - Path to modify
    
    Throws:
    
    IOException - if an ACL could not be removed
  - setAcl
```
public void setAcl(Path path,
                   List<AclEntry> aclSpec)
            throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Fully replaces ACL of files and directories, discarding all existing entries.
    
    Overrides:
    
    setAcl in class AbstractFileSystem
    
    Parameters:
    
    path - Path to modify
    
    aclSpec - List describing modifications, must include entries for user, group, and others for compatibility with permission bits.
    
    Throws:
    
    IOException - if an ACL could not be modified
  - getAclStatus
```
public AclStatus getAclStatus(Path path)
                       throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Gets the ACLs of files and directories.
    
    Overrides:
    
    getAclStatus in class AbstractFileSystem
    
    Parameters:
    
    path - Path to get
    
    Returns:
    
    RemoteIterator which returns each AclStatus
    
    Throws:
    
    IOException - if an ACL could not be read
  - setXAttr
```
public void setXAttr(Path path,
                     String name,
                     byte[] value,
                     EnumSet<XAttrSetFlag> flag)
              throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Set an xattr of a file or directory. The name must be prefixed with the namespace followed by ".". For example, "user.attr".
    Refer to the HDFS extended attributes user documentation for details.
    
    Overrides:
    
    setXAttr in class AbstractFileSystem
    
    Parameters:
    
    path - Path to modify
    
    name - xattr name.
    
    value - xattr value.
    
    flag - xattr set flag
    
    Throws:
    
    IOException
  - getXAttr
```
public byte[] getXAttr(Path path,
                       String name)
                throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Get an xattr for a file or directory. The name must be prefixed with the namespace followed by ".". For example, "user.attr".
    Refer to the HDFS extended attributes user documentation for details.
    
    Overrides:
    
    getXAttr in class AbstractFileSystem
    
    Parameters:
    
    path - Path to get extended attribute
    
    name - xattr name.
    
    Returns:
    
    byte[] xattr value.
    
    Throws:
    
    IOException
  - getXAttrs
```
public Map<String,byte[]> getXAttrs(Path path)
                             throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Get all of the xattrs for a file or directory. Only those xattrs for which the logged-in user has permissions to view are returned.
    Refer to the HDFS extended attributes user documentation for details.
    
    Overrides:
    
    getXAttrs in class AbstractFileSystem
    
    Parameters:
    
    path - Path to get extended attributes
    
    Returns:
    
    Map describing the XAttrs of the file or directory
    
    Throws:
    
    IOException
  - getXAttrs
```
public Map<String,byte[]> getXAttrs(Path path,
                                    List<String> names)
                             throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Get all of the xattrs for a file or directory. Only those xattrs for which the logged-in user has permissions to view are returned.
    Refer to the HDFS extended attributes user documentation for details.
    
    Overrides:
    
    getXAttrs in class AbstractFileSystem
    
    Parameters:
    
    path - Path to get extended attributes
    
    names - XAttr names.
    
    Returns:
    
    Map describing the XAttrs of the file or directory
    
    Throws:
    
    IOException
  - listXAttrs
```
public List<String> listXAttrs(Path path)
                        throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Get all of the xattr names for a file or directory. Only the xattr names for which the logged-in user has permissions to view are returned.
    Refer to the HDFS extended attributes user documentation for details.
    
    Overrides:
    
    listXAttrs in class AbstractFileSystem
    
    Parameters:
    
    path - Path to get extended attributes
    
    Returns:
    
    Map describing the XAttrs of the file or directory
    
    Throws:
    
    IOException
  - removeXAttr
```
public void removeXAttr(Path path,
                        String name)
                 throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Remove an xattr of a file or directory. The name must be prefixed with the namespace followed by ".". For example, "user.attr".
    Refer to the HDFS extended attributes user documentation for details.
    
    Overrides:
    
    removeXAttr in class AbstractFileSystem
    
    Parameters:
    
    path - Path to remove extended attribute
    
    name - xattr name
    
    Throws:
    
    IOException
  - createSnapshot
```
public Path createSnapshot(Path path,
                           String snapshotName)
                    throws IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.createSnapshot(Path, String).
    
    Overrides:
    
    createSnapshot in class AbstractFileSystem
    
    Throws:
    
    IOException
  - renameSnapshot
```
public void renameSnapshot(Path path,
                           String snapshotOldName,
                           String snapshotNewName)
                    throws IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.renameSnapshot(Path, String, String).
    
    Overrides:
    
    renameSnapshot in class AbstractFileSystem
    
    Throws:
    
    IOException
  - deleteSnapshot
```
public void deleteSnapshot(Path path,
                           String snapshotName)
                    throws IOException
```
    Description copied from class: AbstractFileSystem
    
    The specification of this method matches that of FileContext.deleteSnapshot(Path, String).
    
    Overrides:
    
    deleteSnapshot in class AbstractFileSystem
    
    Throws:
    
    IOException
  - setStoragePolicy
```
public void setStoragePolicy(Path path,
                             String policyName)
                      throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Set the storage policy for a given file or directory.
    
    Overrides:
    
    setStoragePolicy in class AbstractFileSystem
    
    Parameters:
    
    path - file or directory path.
    
    policyName - the name of the target storage policy. The list of supported Storage policies can be retrieved via AbstractFileSystem.getAllStoragePolicies().
    
    Throws:
    
    IOException
  - unsetStoragePolicy
```
public void unsetStoragePolicy(Path src)
                        throws IOException
```
    Description copied from class: AbstractFileSystem
    
    Unset the storage policy set for a given file or directory.
    
    Overrides:
    
    unsetStoragePolicy in class AbstractFileSystem
    
    Parameters:
    
    src - file or directory path.
    
    Throws:
    
    IOException
  - getStoragePolicy
```
public BlockStoragePolicySpi getStoragePolicy(Path src)
                                       throws IOException
```
    Retrieve the storage policy for a given file or directory.
    
    Overrides:
    
    getStoragePolicy in class AbstractFileSystem
    
    Parameters:
    
    src - file or directory path.
    
    Returns:
    
    storage policy for give file.
    
    Throws:
    
    IOException

Class ViewFs

Field Summary

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

Constructor Summary

Method Summary

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

Methods inherited from class java.lang.Object

Constructor Detail

ViewFs

Method Detail

getServerDefaults

getServerDefaults

getUriDefaultPort

getHomeDirectory

resolvePath

createInternal

delete

getFileBlockLocations

getFileChecksum

getFileStatus

access

getFileLinkStatus

getFsStatus

listStatusIterator

listLocatedStatus

listStatus

mkdir

open

truncate

renameInternal

renameInternal

supportsSymlinks

createSymlink

getLinkTarget

setOwner

setPermission

setReplication

setTimes

setVerifyChecksum

getMountPoints

getDelegationTokens

isValidName

modifyAclEntries

removeAclEntries

removeDefaultAcl

removeAcl

setAcl

getAclStatus

setXAttr

getXAttr

getXAttrs

getXAttrs

listXAttrs

removeXAttr

createSnapshot

renameSnapshot

deleteSnapshot

setStoragePolicy

unsetStoragePolicy

getStoragePolicy