ViewFileSystem (Apache Hadoop Main 3.2.1 API)

java.lang.Object
- org.apache.hadoop.conf.Configured
- - org.apache.hadoop.fs.FileSystem
  - - org.apache.hadoop.fs.viewfs.ViewFileSystem

All Implemented Interfaces:

Closeable, AutoCloseable, Configurable, org.apache.hadoop.security.token.DelegationTokenIssuer
```
@InterfaceAudience.Public
 @InterfaceStability.Evolving
public class ViewFileSystem
extends FileSystem
```
ViewFileSystem (extends the FileSystem interface) implements a client-side mount table. Its spec and implementation is identical to ViewFs.

Field Summary
- Fields inherited from class org.apache.hadoop.fs.FileSystem
  DEFAULT_FS, FS_DEFAULT_NAME_KEY, SHUTDOWN_HOOK_PRIORITY, statistics, TRASH_PREFIX, USER_HOME_PREFIX

Constructor Summary

Constructors
Constructor and Description
`ViewFileSystem()` This is the constructor with the signature needed by `FileSystem.createFileSystem(URI, Configuration)` After this constructor is called initialize() is called.
`ViewFileSystem(Configuration conf)` Convenience Constructor for apps to call directly

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`access(Path path, FsAction mode)` Checks if the user can access a path.
`FSDataOutputStream`	`append(Path f, int bufferSize, Progressable progress)` Append to an existing file (optional operation).
`FSDataOutputStream`	`create(Path f, FsPermission permission, boolean overwrite, int bufferSize, short replication, long blockSize, Progressable progress)` Create an FSDataOutputStream at the indicated Path with write-progress reporting.
`FSDataOutputStream`	`createNonRecursive(Path f, FsPermission permission, EnumSet<CreateFlag> flags, int bufferSize, short replication, long blockSize, Progressable progress)` Opens an FSDataOutputStream at the indicated Path with write-progress reporting.
`Path`	`createSnapshot(Path path, String snapshotName)` Create a snapshot.
`boolean`	`delete(Path f)` Delete a file/directory.
`boolean`	`delete(Path f, boolean recursive)` Delete a file.
`void`	`deleteSnapshot(Path path, String snapshotName)` Delete a snapshot of a directory.
`AclStatus`	`getAclStatus(Path path)` Gets the ACL of a file or directory.
`Collection<? extends BlockStoragePolicySpi>`	`getAllStoragePolicies()` Retrieve all the storage policies supported by this file system.
`FileSystem[]`	`getChildFileSystems()` Get all the immediate child FileSystems embedded in this FileSystem.
`ContentSummary`	`getContentSummary(Path f)` Return the `ContentSummary` of a given `Path`.
`long`	`getDefaultBlockSize()` Return the number of bytes that large input files should be optimally be split into to minimize I/O time.
`long`	`getDefaultBlockSize(Path f)` 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.
`short`	`getDefaultReplication(Path f)` Get the default replication for a path.
`BlockLocation[]`	`getFileBlockLocations(FileStatus fs, long start, long len)` Return an array containing hostnames, offset and size of portions of the given file.
`FileChecksum`	`getFileChecksum(Path f)` Get the checksum of a file, if the FS supports checksums.
`FileChecksum`	`getFileChecksum(Path f, long length)` Get the checksum of a file, from the beginning of the file till the specific length.
`FileStatus`	`getFileStatus(Path f)` Return a file status object that represents the path.
`Path`	`getHomeDirectory()` Return the current user's home directory in this FileSystem.
`Path`	`getLinkTarget(Path path)` See `FileContext.getLinkTarget(Path)`.
`org.apache.hadoop.fs.viewfs.ViewFileSystem.MountPoint[]`	`getMountPoints()`
`QuotaUsage`	`getQuotaUsage(Path f)` Return the `QuotaUsage` of a given `Path`.
`String`	`getScheme()` Return the protocol scheme for the FileSystem.
`FsServerDefaults`	`getServerDefaults()` Return a set of server default configuration values.
`FsServerDefaults`	`getServerDefaults(Path f)` Return a set of server default configuration values.
`FsStatus`	`getStatus()` Returns a status object describing the use and capacity of the filesystem.
`FsStatus`	`getStatus(Path p)` Returns a status object describing the use and capacity of the filesystem.
`BlockStoragePolicySpi`	`getStoragePolicy(Path src)` Query the effective storage policy ID for the given file or directory.
`Path`	`getTrashRoot(Path path)` Get the trash root directory for current user when the path specified is deleted.
`Collection<FileStatus>`	`getTrashRoots(boolean allUsers)` Get all the trash roots for current user or all users.
`URI`	`getUri()` Returns a URI which identifies this FileSystem.
`long`	`getUsed()` Return the total size of all files under "/", if `Constants.CONFIG_VIEWFS_LINK_MERGE_SLASH` is supported and is a valid mount point.
`Path`	`getWorkingDirectory()` Get the current working directory for the given FileSystem
`byte[]`	`getXAttr(Path path, String name)` Get an xattr name and value for a file or directory.
`Map<String,byte[]>`	`getXAttrs(Path path)` Get all of the xattr name/value pairs for a file or directory.
`Map<String,byte[]>`	`getXAttrs(Path path, List<String> names)` Get all of the xattrs name/value pairs for a file or directory.
`void`	`initialize(URI theUri, Configuration conf)` Called after a new FileSystem instance is constructed.
`org.apache.hadoop.fs.RemoteIterator<LocatedFileStatus>`	`listLocatedStatus(Path f, PathFilter filter)` List a directory.
`FileStatus[]`	`listStatus(Path f)` List the statuses of the files/directories in the given path if the path is a directory.
`List<String>`	`listXAttrs(Path path)` Get all of the xattr names for a file or directory.
`boolean`	`mkdirs(Path dir, FsPermission permission)` Make the given file and all non-existent parents into directories.
`void`	`modifyAclEntries(Path path, List<AclEntry> aclSpec)` Modifies ACL entries of files and directories.
`FSDataInputStream`	`open(Path f, int bufferSize)` Opens an FSDataInputStream at the indicated Path.
`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.
`boolean`	`rename(Path src, Path dst)` Renames Path src to Path dst.
`void`	`renameSnapshot(Path path, String snapshotOldName, String snapshotNewName)` Rename a snapshot.
`Path`	`resolvePath(Path f)` Return the fully-qualified path of path, resolving the path through any 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)` Set owner of a path (i.e.
`void`	`setPermission(Path f, FsPermission permission)` Set permission of a path.
`boolean`	`setReplication(Path f, short replication)` Set the replication for an existing file.
`void`	`setStoragePolicy(Path src, String policyName)` Set the storage policy for a given file or directory.
`void`	`setTimes(Path f, long mtime, long atime)` Set access time of a file.
`void`	`setVerifyChecksum(boolean verifyChecksum)` Set the verify checksum flag.
`void`	`setWorkingDirectory(Path new_dir)` Set the current working directory for the given FileSystem.
`void`	`setWriteChecksum(boolean writeChecksum)` Set the write checksum flag.
`void`	`setXAttr(Path path, String name, byte[] value, EnumSet<XAttrSetFlag> flag)` Set an xattr of a file or directory.
`boolean`	`truncate(Path f, long newLength)` Truncate the file in the indicated path to the indicated size.
`void`	`unsetStoragePolicy(Path src)` Unset the storage policy set for a given file or directory.

Methods inherited from class org.apache.hadoop.fs.FileSystem
append, append, appendFile, areSymlinksEnabled, cancelDeleteOnExit, canonicalizeUri, checkPath, clearStatistics, close, closeAll, closeAllForUGI, completeLocalOutput, concat, copyFromLocalFile, copyFromLocalFile, copyFromLocalFile, copyFromLocalFile, copyToLocalFile, copyToLocalFile, copyToLocalFile, create, create, create, create, create, create, create, create, create, create, create, create, createFile, createNewFile, createNonRecursive, createNonRecursive, createPathHandle, createSnapshot, createSymlink, deleteOnExit, enableSymlinks, exists, fixRelativePart, get, get, get, getAllStatistics, getBlockSize, getCanonicalServiceName, getCanonicalUri, getDefaultPort, getDefaultUri, getFileBlockLocations, getFileLinkStatus, getFileSystemClass, getFSofPath, getGlobalStorageStatistics, getInitialWorkingDirectory, getLength, getLocal, getName, getNamed, getPathHandle, getReplication, getStatistics, getStatistics, getStorageStatistics, getUsed, globStatus, globStatus, isDirectory, isFile, listCorruptFileBlocks, listFiles, listLocatedStatus, listStatus, listStatus, listStatus, listStatusIterator, makeQualified, mkdirs, mkdirs, moveFromLocalFile, moveFromLocalFile, moveToLocalFile, newInstance, newInstance, newInstance, newInstanceLocal, open, open, open, primitiveCreate, primitiveMkdir, primitiveMkdir, printStatistics, processDeleteOnExit, rename, resolveLink, setDefaultUri, setDefaultUri, setXAttr, startLocalOutput, supportsSymlinks

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, toString, wait, wait, wait

Methods inherited from interface org.apache.hadoop.security.token.DelegationTokenIssuer
addDelegationTokens, getAdditionalTokenIssuers, getDelegationToken

- Constructor Detail
  - ViewFileSystem
```
public ViewFileSystem()
               throws IOException
```
    This is the constructor with the signature needed by FileSystem.createFileSystem(URI, Configuration) After this constructor is called initialize() is called.
    
    Throws:
    
    IOException
  - ViewFileSystem
```
public ViewFileSystem(Configuration conf)
               throws IOException
```
    Convenience Constructor for apps to call directly
    
    Parameters:
    
    conf -
    
    Throws:
    
    IOException
- Method Detail
  - getScheme
```
public String getScheme()
```
    Return the protocol scheme for the FileSystem.
    
    Overrides:
    
    getScheme in class FileSystem
    
    Returns:
    
    viewfs
  - initialize
```
public void initialize(URI theUri,
                       Configuration conf)
                throws IOException
```
    Called after a new FileSystem instance is constructed.
    
    Overrides:
    
    initialize in class FileSystem
    
    Parameters:
    
    theUri - a uri whose authority section names the host, port, etc. for this FileSystem
    
    conf - the configuration
    
    Throws:
    
    IOException - on any failure to initialize this instance.
  - getUri
```
public URI getUri()
```
    Description copied from class: FileSystem
    
    Returns a URI which identifies this FileSystem.
    
    Specified by:
    
    getUri in class FileSystem
    
    Returns:
    
    the URI of this filesystem.
  - resolvePath
```
public Path resolvePath(Path f)
                 throws IOException
```
    Description copied from class: FileSystem
    
    Return the fully-qualified path of path, resolving the path through any symlinks or mount point.
    
    Overrides:
    
    resolvePath in class FileSystem
    
    Parameters:
    
    f - path to be resolved
    
    Returns:
    
    fully qualified path
    
    Throws:
    
    FileNotFoundException - if the path is not present
    
    IOException - for any other error
  - getHomeDirectory
```
public Path getHomeDirectory()
```
    Description copied from class: FileSystem
    
    Return the current user's home directory in this FileSystem. The default implementation returns "/user/$USER/".
    
    Overrides:
    
    getHomeDirectory in class FileSystem
  - getWorkingDirectory
```
public Path getWorkingDirectory()
```
    Description copied from class: FileSystem
    
    Get the current working directory for the given FileSystem
    
    Specified by:
    
    getWorkingDirectory in class FileSystem
    
    Returns:
    
    the directory pathname
  - setWorkingDirectory
```
public void setWorkingDirectory(Path new_dir)
```
    Description copied from class: FileSystem
    
    Set the current working directory for the given FileSystem. All relative paths will be resolved relative to it.
    
    Specified by:
    
    setWorkingDirectory in class FileSystem
    
    Parameters:
    
    new_dir - Path of new working directory
  - append
```
public FSDataOutputStream append(Path f,
                                 int bufferSize,
                                 Progressable progress)
                          throws IOException
```
    Description copied from class: FileSystem
    
    Append to an existing file (optional operation).
    
    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 - IO failure
  - createNonRecursive
```
public FSDataOutputStream createNonRecursive(Path f,
                                             FsPermission permission,
                                             EnumSet<CreateFlag> flags,
                                             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. Same as create(), except fails if parent directory doesn't already exist.
    
    Overrides:
    
    createNonRecursive in class FileSystem
    
    Parameters:
    
    f - the file name to open
    
    permission - file permission
    
    flags - CreateFlags to use for this stream.
    
    bufferSize - the size of the buffer to be used.
    
    replication - required block replication for the file.
    
    blockSize - block size
    
    progress - the progress reporter
    
    Throws:
    
    IOException - IO failure
    
    See Also:
    
    FileSystem.setPermission(Path, FsPermission)
  - 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
    
    Create an FSDataOutputStream at the indicated Path with write-progress reporting.
    
    Specified by:
    
    create in class FileSystem
    
    Parameters:
    
    f - the file name to open
    
    permission - file permission
    
    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.
    
    blockSize - block size
    
    progress - the progress reporter
    
    Throws:
    
    IOException - IO failure
    
    See Also:
    
    FileSystem.setPermission(Path, FsPermission)
  - delete
```
public boolean delete(Path f,
                      boolean recursive)
               throws AccessControlException,
                      FileNotFoundException,
                      IOException
```
    Description copied from class: FileSystem
    
    Delete a file.
    
    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 - IO failure
    
    AccessControlException
    
    FileNotFoundException
  - delete
```
public boolean delete(Path f)
               throws AccessControlException,
                      FileNotFoundException,
                      IOException
```
    Description copied from class: FileSystem
    
    Delete a file/directory.
    
    Overrides:
    
    delete in class FileSystem
    
    Throws:
    
    AccessControlException
    
    FileNotFoundException
    
    IOException
  - getFileBlockLocations
```
public BlockLocation[] getFileBlockLocations(FileStatus fs,
                                             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 nonexistent file or regions, null is returned.
```
   if f == null :
     result = null
   elif f.getLen() <= start:
     result = []
   else result = [ locations(FS, b) for b in blocks(FS, p, s, s+l)]
 
```
    This call is most helpful with and distributed filesystem where the hostnames of machines that contain blocks of the given file can be determined. The default implementation returns an array containing one element:
```
 BlockLocation( { "localhost:9866" },  { "localhost" }, 0, file.getLen())
 
```
    In HDFS, if file is three-replicated, the returned array contains elements like:
```
 BlockLocation(offset: 0, length: BLOCK_SIZE,
   hosts: {"host1:9866", "host2:9866, host3:9866"})
 BlockLocation(offset: BLOCK_SIZE, length: BLOCK_SIZE,
   hosts: {"host2:9866", "host3:9866, host4:9866"})
 
```
    And if a file is erasure-coded, the returned BlockLocation are logical block groups. Suppose we have a RS_3_2 coded file (3 data units and 2 parity units). 1. If the file size is less than one stripe size, say 2 * CELL_SIZE, then there will be one BlockLocation returned, with 0 offset, actual file size and 4 hosts (2 data blocks and 2 parity blocks) hosting the actual blocks. 3. If the file size is less than one group size but greater than one stripe size, then there will be one BlockLocation returned, with 0 offset, actual file size with 5 hosts (3 data blocks and 2 parity blocks) hosting the actual blocks. 4. If the file size is greater than one group size, 3 * BLOCK_SIZE + 123 for example, then the result will be like:
```
 BlockLocation(offset: 0, length: 3 * BLOCK_SIZE, hosts: {"host1:9866",
   "host2:9866","host3:9866","host4:9866","host5:9866"})
 BlockLocation(offset: 3 * BLOCK_SIZE, length: 123, hosts: {"host1:9866",
   "host4:9866", "host5:9866"})
 
```
    Overrides:
    
    getFileBlockLocations in class FileSystem
    
    Parameters:
    
    fs - FilesStatus to get data from
    
    start - offset into the given file
    
    len - length for which to get locations for
    
    Throws:
    
    IOException - IO failure
  - getFileChecksum
```
public FileChecksum getFileChecksum(Path f)
                             throws AccessControlException,
                                    FileNotFoundException,
                                    IOException
```
    Description copied from class: FileSystem
    
    Get the checksum of a file, if the FS supports checksums.
    
    Overrides:
    
    getFileChecksum in class FileSystem
    
    Parameters:
    
    f - The file path
    
    Returns:
    
    The file checksum. The default return value is null, which indicates that no checksum algorithm is implemented in the corresponding FileSystem.
    
    Throws:
    
    IOException - IO failure
    
    AccessControlException
    
    FileNotFoundException
  - getFileChecksum
```
public FileChecksum getFileChecksum(Path f,
                                    long length)
                             throws AccessControlException,
                                    FileNotFoundException,
                                    IOException
```
    Description copied from class: FileSystem
    
    Get the checksum of a file, from the beginning of the file till the specific length.
    
    Overrides:
    
    getFileChecksum in class FileSystem
    
    Parameters:
    
    f - The file path
    
    length - The length of the file range for checksum calculation
    
    Returns:
    
    The file checksum or null if checksums are not supported.
    
    Throws:
    
    IOException - IO failure
    
    AccessControlException
    
    FileNotFoundException
  - getFileStatus
```
public FileStatus getFileStatus(Path f)
                         throws AccessControlException,
                                FileNotFoundException,
                                IOException
```
    Description copied from class: FileSystem
    
    Return a file status object that represents the path.
    
    Specified by:
    
    getFileStatus in class FileSystem
    
    Parameters:
    
    f - The path we want information from
    
    Returns:
    
    a FileStatus object
    
    Throws:
    
    FileNotFoundException - when the path does not exist
    
    IOException - see specific implementation
    
    AccessControlException
  - access
```
public void access(Path path,
                   FsAction mode)
            throws AccessControlException,
                   FileNotFoundException,
                   IOException
```
    Description copied from class: FileSystem
    
    Checks if the user can access a path. The mode specifies which access checks to perform. If the requested permissions are granted, then the method returns normally. If access is denied, then the method throws an AccessControlException.
    The default implementation calls FileSystem.getFileStatus(Path) and checks the returned permissions against the requested permissions. Note that the FileSystem.getFileStatus(Path) call will be subject to authorization checks. Typically, this requires search (execute) permissions on each directory in the path's prefix, but this is implementation-defined. Any file system that provides a richer authorization model (such as ACLs) may override the default implementation so that it checks against that model instead.
    In general, applications should avoid using this method, due to the risk of time-of-check/time-of-use race conditions. The permissions on a file may change immediately after the access call returns. Most applications should prefer running specific file system actions as the desired user represented by a UserGroupInformation.
    
    Parameters:
    
    path - Path to check
    
    mode - type of access to check
    
    Throws:
    
    AccessControlException - if access is denied
    
    FileNotFoundException - if the path does not exist
    
    IOException - see specific implementation
  - listStatus
```
public FileStatus[] listStatus(Path f)
                        throws AccessControlException,
                               FileNotFoundException,
                               IOException
```
    Description copied from class: FileSystem
    
    List the statuses of the files/directories in the given path if the path is a directory.
    Does not guarantee to return the List of files/directories status in a sorted order.
    Will not return null. Expect IOException upon access error.
    
    Specified by:
    
    listStatus in class FileSystem
    
    Parameters:
    
    f - given path
    
    Returns:
    
    the statuses of the files/directories in the given patch
    
    Throws:
    
    FileNotFoundException - when the path does not exist
    
    IOException - see specific implementation
    
    AccessControlException
  - listLocatedStatus
```
public org.apache.hadoop.fs.RemoteIterator<LocatedFileStatus> listLocatedStatus(Path f,
                                                                                PathFilter filter)
                                                                         throws FileNotFoundException,
                                                                                IOException
```
    Description copied from class: FileSystem
    
    List a directory. The returned results include its block location if it is a file The results are filtered by the given path filter
    
    Overrides:
    
    listLocatedStatus in class FileSystem
    
    Parameters:
    
    f - a path
    
    filter - a path filter
    
    Returns:
    
    an iterator that traverses statuses of the files/directories in the given path
    
    Throws:
    
    FileNotFoundException - if f does not exist
    
    IOException - if any I/O error occurred
  - mkdirs
```
public boolean mkdirs(Path dir,
                      FsPermission permission)
               throws IOException
```
    Description copied from class: FileSystem
    
    Make the given file and all non-existent parents into directories. Has roughly the semantics of Unix @{code mkdir -p}. Existence of the directory hierarchy is not an error.
    
    Specified by:
    
    mkdirs in class FileSystem
    
    Parameters:
    
    dir - path to create
    
    permission - to apply to f
    
    Throws:
    
    IOException - IO failure
  - open
```
public FSDataInputStream open(Path f,
                              int bufferSize)
                       throws AccessControlException,
                              FileNotFoundException,
                              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 - IO failure
    
    AccessControlException
    
    FileNotFoundException
  - rename
```
public boolean rename(Path src,
                      Path dst)
               throws IOException
```
    Description copied from class: FileSystem
    
    Renames Path src to Path dst.
    
    Specified by:
    
    rename in class FileSystem
    
    Parameters:
    
    src - path to be renamed
    
    dst - new path after rename
    
    Returns:
    
    true if rename is successful
    
    Throws:
    
    IOException - on failure
  - truncate
```
public boolean truncate(Path f,
                        long newLength)
                 throws IOException
```
    Description copied from class: FileSystem
    Truncate the file in the indicated path to the indicated size.
    - Fails if path is a directory.
    - Fails if path does not exist.
    - Fails if path is not closed.
    - Fails if new size is greater than current size.
    Overrides:
    
    truncate in class FileSystem
    
    Parameters:
    
    f - The path to the file to be truncated
    
    newLength - The size the file is to be truncated to
    
    Returns:
    
    true if the file has been truncated to the desired newLength and is immediately available to be reused for write operations such as append, or false if a background process of adjusting the length of the last block has been started, and clients should wait for it to complete before proceeding with further file updates.
    
    Throws:
    
    IOException - IO failure
  - setOwner
```
public void setOwner(Path f,
                     String username,
                     String groupname)
              throws AccessControlException,
                     FileNotFoundException,
                     IOException
```
    Description copied from class: FileSystem
    
    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:
    
    f - The path
    
    username - If it is null, the original username remains unchanged.
    
    groupname - If it is null, the original groupname remains unchanged.
    
    Throws:
    
    IOException - IO failure
    
    AccessControlException
    
    FileNotFoundException
  - setPermission
```
public void setPermission(Path f,
                          FsPermission permission)
                   throws AccessControlException,
                          FileNotFoundException,
                          IOException
```
    Description copied from class: FileSystem
    
    Set permission of a path.
    
    Overrides:
    
    setPermission in class FileSystem
    
    Parameters:
    
    f - The path
    
    permission - permission
    
    Throws:
    
    IOException - IO failure
    
    AccessControlException
    
    FileNotFoundException
  - setReplication
```
public boolean setReplication(Path f,
                              short replication)
                       throws AccessControlException,
                              FileNotFoundException,
                              IOException
```
    Description copied from class: FileSystem
    
    Set the replication for an existing file. If a filesystem does not support replication, it will always return true: the check for a file existing may be bypassed. This is the default behavior.
    
    Overrides:
    
    setReplication in class FileSystem
    
    Parameters:
    
    f - file name
    
    replication - new replication
    
    Returns:
    
    true if successful, or the feature in unsupported; false if replication is supported but the file does not exist, or is a directory
    
    Throws:
    
    IOException
    
    AccessControlException
    
    FileNotFoundException
  - setTimes
```
public void setTimes(Path f,
                     long mtime,
                     long atime)
              throws AccessControlException,
                     FileNotFoundException,
                     IOException
```
    Description copied from class: FileSystem
    
    Set access time of a file.
    
    Overrides:
    
    setTimes in class FileSystem
    
    Parameters:
    
    f - The path
    
    mtime - Set the modification time of this file. The number of milliseconds since Jan 1, 1970. A value of -1 means that this call should not set modification time.
    
    atime - Set the access time of this file. The number of milliseconds since Jan 1, 1970. A value of -1 means that this call should not set access time.
    
    Throws:
    
    IOException - IO failure
    
    AccessControlException
    
    FileNotFoundException
  - modifyAclEntries
```
public void modifyAclEntries(Path path,
                             List<AclEntry> aclSpec)
                      throws IOException
```
    Description copied from class: FileSystem
    
    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 FileSystem
    
    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: FileSystem
    
    Removes ACL entries from files and directories. Other ACL entries are retained.
    
    Overrides:
    
    removeAclEntries in class FileSystem
    
    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: FileSystem
    
    Removes all default ACL entries from files and directories.
    
    Overrides:
    
    removeDefaultAcl in class FileSystem
    
    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: FileSystem
    
    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 FileSystem
    
    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: FileSystem
    
    Fully replaces ACL of files and directories, discarding all existing entries.
    
    Overrides:
    
    setAcl in class FileSystem
    
    Parameters:
    
    path - Path to modify
    
    aclSpec - List describing modifications, which 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: FileSystem
    
    Gets the ACL of a file or directory.
    
    Overrides:
    
    getAclStatus in class FileSystem
    
    Parameters:
    
    path - Path to get
    
    Returns:
    
    AclStatus describing the ACL of the file or directory
    
    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: FileSystem
    
    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 FileSystem
    
    Parameters:
    
    path - Path to modify
    
    name - xattr name.
    
    value - xattr value.
    
    flag - xattr set flag
    
    Throws:
    
    IOException - IO failure
  - getXAttr
```
public byte[] getXAttr(Path path,
                       String name)
                throws IOException
```
    Description copied from class: FileSystem
    
    Get an xattr name and value 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 FileSystem
    
    Parameters:
    
    path - Path to get extended attribute
    
    name - xattr name.
    
    Returns:
    
    byte[] xattr value.
    
    Throws:
    
    IOException - IO failure
  - getXAttrs
```
public Map<String,byte[]> getXAttrs(Path path)
                             throws IOException
```
    Description copied from class: FileSystem
    
    Get all of the xattr name/value pairs for a file or directory. Only those xattrs 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 FileSystem
    
    Parameters:
    
    path - Path to get extended attributes
    
    Returns:
    
    Map describing the XAttrs of the file or directory
    
    Throws:
    
    IOException - IO failure
  - getXAttrs
```
public Map<String,byte[]> getXAttrs(Path path,
                                    List<String> names)
                             throws IOException
```
    Description copied from class: FileSystem
    
    Get all of the xattrs name/value pairs for a file or directory. Only those xattrs 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 FileSystem
    
    Parameters:
    
    path - Path to get extended attributes
    
    names - XAttr names.
    
    Returns:
    
    Map describing the XAttrs of the file or directory
    
    Throws:
    
    IOException - IO failure
  - listXAttrs
```
public List<String> listXAttrs(Path path)
                        throws IOException
```
    Description copied from class: FileSystem
    
    Get all of the xattr names for a file or directory. Only those xattr names 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 FileSystem
    
    Parameters:
    
    path - Path to get extended attributes
    
    Returns:
    
    List of the XAttr names of the file or directory
    
    Throws:
    
    IOException - IO failure
  - removeXAttr
```
public void removeXAttr(Path path,
                        String name)
                 throws IOException
```
    Description copied from class: FileSystem
    
    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 FileSystem
    
    Parameters:
    
    path - Path to remove extended attribute
    
    name - xattr name
    
    Throws:
    
    IOException - IO failure
  - setVerifyChecksum
```
public void setVerifyChecksum(boolean verifyChecksum)
```
    Description copied from class: FileSystem
    
    Set the verify checksum flag. This is only applicable if the corresponding filesystem supports checksums. By default doesn't do anything.
    
    Overrides:
    
    setVerifyChecksum in class FileSystem
    
    Parameters:
    
    verifyChecksum - Verify checksum flag
  - 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
    
    Returns:
    
    the replication; the default value is "1".
  - getServerDefaults
```
public FsServerDefaults getServerDefaults()
                                   throws IOException
```
    Description copied from class: FileSystem
    
    Return a set of server default configuration values.
    
    Overrides:
    
    getServerDefaults in class FileSystem
    
    Returns:
    
    server default configuration values
    
    Throws:
    
    IOException - IO failure
  - getDefaultBlockSize
```
public long getDefaultBlockSize(Path f)
```
    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. The given path will be used to locate the actual filesystem. The full path does not have to exist.
    
    Overrides:
    
    getDefaultBlockSize in class FileSystem
    
    Parameters:
    
    f - path of file
    
    Returns:
    
    the default block size for the path's filesystem
  - getDefaultReplication
```
public short getDefaultReplication(Path f)
```
    Description copied from class: FileSystem
    
    Get the default replication for a path. The given path will be used to locate the actual FileSystem to query. The full path does not have to exist.
    
    Overrides:
    
    getDefaultReplication in class FileSystem
    
    Parameters:
    
    f - of the file
    
    Returns:
    
    default replication for the path's filesystem
  - getServerDefaults
```
public FsServerDefaults getServerDefaults(Path f)
                                   throws IOException
```
    Description copied from class: FileSystem
    
    Return a set of server default configuration values.
    
    Overrides:
    
    getServerDefaults in class FileSystem
    
    Parameters:
    
    f - path is used to identify an FS since an FS could have another FS that it could be delegating the call to
    
    Returns:
    
    server default configuration values
    
    Throws:
    
    IOException - IO failure
  - getContentSummary
```
public ContentSummary getContentSummary(Path f)
                                 throws IOException
```
    Description copied from class: FileSystem
    
    Return the ContentSummary of a given Path.
    
    Overrides:
    
    getContentSummary in class FileSystem
    
    Parameters:
    
    f - path to use
    
    Throws:
    
    FileNotFoundException - if the path does not resolve
    
    IOException - IO failure
  - getQuotaUsage
```
public QuotaUsage getQuotaUsage(Path f)
                         throws IOException
```
    Description copied from class: FileSystem
    
    Return the QuotaUsage of a given Path.
    
    Overrides:
    
    getQuotaUsage in class FileSystem
    
    Parameters:
    
    f - path to use
    
    Returns:
    
    the quota usage
    
    Throws:
    
    IOException - IO failure
  - setWriteChecksum
```
public void setWriteChecksum(boolean writeChecksum)
```
    Description copied from class: FileSystem
    
    Set the write checksum flag. This is only applicable if the corresponding filesystem supports checksums. By default doesn't do anything.
    
    Overrides:
    
    setWriteChecksum in class FileSystem
    
    Parameters:
    
    writeChecksum - Write checksum flag
  - getChildFileSystems
```
public FileSystem[] getChildFileSystems()
```
    Description copied from class: FileSystem
    
    Get all the immediate child FileSystems embedded in this FileSystem. It does not recurse and get grand children. If a FileSystem has multiple child FileSystems, then it must return a unique list of those FileSystems. Default is to return null to signify no children.
    
    Returns:
    
    FileSystems that are direct children of this FileSystem, or null for "no children"
  - getMountPoints
```
public org.apache.hadoop.fs.viewfs.ViewFileSystem.MountPoint[] getMountPoints()
```
  - createSnapshot
```
public Path createSnapshot(Path path,
                           String snapshotName)
                    throws IOException
```
    Description copied from class: FileSystem
    
    Create a snapshot.
    
    Overrides:
    
    createSnapshot in class FileSystem
    
    Parameters:
    
    path - The directory where snapshots will be taken.
    
    snapshotName - The name of the snapshot
    
    Returns:
    
    the snapshot path.
    
    Throws:
    
    IOException - IO failure
  - renameSnapshot
```
public void renameSnapshot(Path path,
                           String snapshotOldName,
                           String snapshotNewName)
                    throws IOException
```
    Description copied from class: FileSystem
    
    Rename a snapshot.
    
    Overrides:
    
    renameSnapshot in class FileSystem
    
    Parameters:
    
    path - The directory path where the snapshot was taken
    
    snapshotOldName - Old name of the snapshot
    
    snapshotNewName - New name of the snapshot
    
    Throws:
    
    IOException - IO failure
  - deleteSnapshot
```
public void deleteSnapshot(Path path,
                           String snapshotName)
                    throws IOException
```
    Description copied from class: FileSystem
    
    Delete a snapshot of a directory.
    
    Overrides:
    
    deleteSnapshot in class FileSystem
    
    Parameters:
    
    path - The directory that the to-be-deleted snapshot belongs to
    
    snapshotName - The name of the snapshot
    
    Throws:
    
    IOException - IO failure
  - setStoragePolicy
```
public void setStoragePolicy(Path src,
                             String policyName)
                      throws IOException
```
    Description copied from class: FileSystem
    
    Set the storage policy for a given file or directory.
    
    Overrides:
    
    setStoragePolicy in class FileSystem
    
    Parameters:
    
    src - file or directory path.
    
    policyName - the name of the target storage policy. The list of supported Storage policies can be retrieved via FileSystem.getAllStoragePolicies().
    
    Throws:
    
    IOException - IO failure
  - unsetStoragePolicy
```
public void unsetStoragePolicy(Path src)
                        throws IOException
```
    Description copied from class: FileSystem
    
    Unset the storage policy set for a given file or directory.
    
    Overrides:
    
    unsetStoragePolicy in class FileSystem
    
    Parameters:
    
    src - file or directory path.
    
    Throws:
    
    IOException - IO failure
  - getStoragePolicy
```
public BlockStoragePolicySpi getStoragePolicy(Path src)
                                       throws IOException
```
    Description copied from class: FileSystem
    
    Query the effective storage policy ID for the given file or directory.
    
    Overrides:
    
    getStoragePolicy in class FileSystem
    
    Parameters:
    
    src - file or directory path.
    
    Returns:
    
    storage policy for give file.
    
    Throws:
    
    IOException - IO failure
  - getAllStoragePolicies
```
public Collection<? extends BlockStoragePolicySpi> getAllStoragePolicies()
                                                                  throws IOException
```
    Description copied from class: FileSystem
    
    Retrieve all the storage policies supported by this file system.
    
    Overrides:
    
    getAllStoragePolicies in class FileSystem
    
    Returns:
    
    all storage policies supported by this filesystem.
    
    Throws:
    
    IOException - IO failure
  - getTrashRoot
```
public Path getTrashRoot(Path path)
```
    Get the trash root directory for current user when the path specified is deleted.
    
    Overrides:
    
    getTrashRoot in class FileSystem
    
    Parameters:
    
    path - the trash root of the path to be determined.
    
    Returns:
    
    the trash root path.
  - getTrashRoots
```
public Collection<FileStatus> getTrashRoots(boolean allUsers)
```
    Get all the trash roots for current user or all users.
    
    Overrides:
    
    getTrashRoots in class FileSystem
    
    Parameters:
    
    allUsers - return trash roots for all users if true.
    
    Returns:
    
    all Trash root directories.
  - getStatus
```
public FsStatus getStatus()
                   throws IOException
```
    Description copied from class: FileSystem
    
    Returns a status object describing the use and capacity of the filesystem. If the filesystem has multiple partitions, the use and capacity of the root partition is reflected.
    
    Overrides:
    
    getStatus in class FileSystem
    
    Returns:
    
    a FsStatus object
    
    Throws:
    
    IOException - see specific implementation
  - getStatus
```
public FsStatus getStatus(Path p)
                   throws IOException
```
    Description copied from class: FileSystem
    
    Returns a status object describing the use and capacity of the filesystem. If the filesystem has multiple partitions, the use and capacity of the partition pointed to by the specified path is reflected.
    
    Overrides:
    
    getStatus in class FileSystem
    
    Parameters:
    
    p - Path for which status should be obtained. null means the default partition.
    
    Returns:
    
    a FsStatus object
    
    Throws:
    
    IOException - see specific implementation
  - getUsed
```
public long getUsed()
             throws IOException
```
    Return the total size of all files under "/", if Constants.CONFIG_VIEWFS_LINK_MERGE_SLASH is supported and is a valid mount point. Else, throw NotInMountpointException.
    
    Overrides:
    
    getUsed in class FileSystem
    
    Throws:
    
    IOException
  - getLinkTarget
```
public Path getLinkTarget(Path path)
                   throws IOException
```
    Description copied from class: FileSystem
    
    See FileContext.getLinkTarget(Path).
    
    Overrides:
    
    getLinkTarget in class FileSystem
    
    Throws:
    
    IOException

Class ViewFileSystem

Field Summary

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

Constructor Summary

Method Summary

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

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

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.hadoop.security.token.DelegationTokenIssuer

Constructor Detail

ViewFileSystem

ViewFileSystem

Method Detail

getScheme

initialize

getUri

resolvePath

getHomeDirectory

getWorkingDirectory

setWorkingDirectory

append

createNonRecursive

create

delete

delete

getFileBlockLocations

getFileChecksum

getFileChecksum

getFileStatus

access

listStatus

listLocatedStatus

mkdirs

open

rename

truncate

setOwner

setPermission

setReplication

setTimes

modifyAclEntries

removeAclEntries

removeDefaultAcl

removeAcl

setAcl

getAclStatus

setXAttr

getXAttr

getXAttrs

getXAttrs

listXAttrs

removeXAttr

setVerifyChecksum

getDefaultBlockSize

getDefaultReplication

getServerDefaults

getDefaultBlockSize

getDefaultReplication

getServerDefaults

getContentSummary

getQuotaUsage

setWriteChecksum

getChildFileSystems

getMountPoints

createSnapshot

renameSnapshot

deleteSnapshot

setStoragePolicy

unsetStoragePolicy

getStoragePolicy

getAllStoragePolicies

getTrashRoot

getTrashRoots

getStatus

getStatus

getUsed

getLinkTarget