alluxio.underfs

Interface UnderFileSystem

All Superinterfaces:

AutoCloseable, Closeable

All Known Subinterfaces:

AtomicFileOutputStreamCallback

All Known Implementing Classes:

AdlUnderFileSystem, BaseUnderFileSystem, ConsistentUnderFileSystem, COSUnderFileSystem, GCSUnderFileSystem, HdfsUnderFileSystem, KodoUnderFileSystem, LocalUnderFileSystem, ManagedBlockingUfsForwarder, ObjectUnderFileSystem, OSSUnderFileSystem, S3AUnderFileSystem, SwiftUnderFileSystem, UnderFileSystemWithLogging, WasbUnderFileSystem, WebUnderFileSystem

@PublicApi
 @ThreadSafe
public interface UnderFileSystem
extends Closeable

Alluxio stores data into an under layer file system. Any file system implementing this interface can be a valid under layer file system. There are two sets of APIs in the under file system: (1) normal operations (e.g. create, renameFile, deleteFile) (2) operations deal with the eventual consistency issue (e.g. createNonexistingFile, renameRenamableFile) When confirmed by Alluxio metadata that an operation should succeed but may fail because of the under filesystem eventual consistency issue, use the second set of APIs.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	UnderFileSystem.Factory The factory for the UnderFileSystem.
static class	UnderFileSystem.SpaceType The different types of space indicate the total space, the free space and the space used in the under file system.

Method Summary

Modifier and Type	Method and Description
void	cleanup() Cleans up the under file system.
void	connectFromMaster(String hostname) Takes any necessary actions required to establish a connection to the under file system from the given master host e.g.
void	connectFromWorker(String hostname) Takes any necessary actions required to establish a connection to the under file system from the given worker host e.g.
OutputStream	create(String path) Creates a file in the under file system with the indicated name.
OutputStream	create(String path, CreateOptions options) Creates a file in the under file system with the specified CreateOptions.
OutputStream	createNonexistingFile(String path) Creates a file in the under file system with the indicated name.
OutputStream	createNonexistingFile(String path, CreateOptions options) Creates a file in the under file system with the specified CreateOptions.
boolean	deleteDirectory(String path) Deletes a directory from the under file system with the indicated name non-recursively.
boolean	deleteDirectory(String path, DeleteOptions options) Deletes a directory from the under file system with the indicated name.
boolean	deleteExistingDirectory(String path) Deletes a directory from the under file system.
boolean	deleteExistingDirectory(String path, DeleteOptions options) Deletes a directory from the under file system with the indicated name.
boolean	deleteExistingFile(String path) Deletes a file from the under file system with the indicated name.
boolean	deleteFile(String path) Deletes a file from the under file system with the indicated name.
boolean	exists(String path) Checks if a file or directory exists in under file system.
Pair<AccessControlList,DefaultAccessControlList>	getAclPair(String path) Gets the ACL and the Default ACL of a file or directory in under file system.
SyncInfo	getActiveSyncInfo() Return the active sync info for the specified syncPoints.
long	getBlockSizeByte(String path) Deprecated. block size should be returned as part of the UfsFileStatus from getFileStatus(String) or getExistingFileStatus(String)
default AlluxioConfiguration	getConfiguration() Gets the under file system configuration.
UfsDirectoryStatus	getDirectoryStatus(String path) Gets the directory status.
UfsDirectoryStatus	getExistingDirectoryStatus(String path) Gets the directory status.
UfsFileStatus	getExistingFileStatus(String path) Gets the file status.
UfsStatus	getExistingStatus(String path) Gets the file or directory status.
List<String>	getFileLocations(String path) Gets the list of locations of the indicated path.
List<String>	getFileLocations(String path, FileLocationOptions options) Gets the list of locations of the indicated path given options.
UfsFileStatus	getFileStatus(String path) Gets the file status.
String	getFingerprint(String path) Computes and returns a fingerprint for the path.
UfsMode	getOperationMode(Map<String,UfsMode> physicalUfsState) An UnderFileSystem may be composed of one or more "physical UFS"s.
List<String>	getPhysicalStores() An UnderFileSystem may be composed of one or more "physical UFS"s.
long	getSpace(String path, UnderFileSystem.SpaceType type) Queries the under file system about the space of the indicated path (e.g., space left, space used and etc).
UfsStatus	getStatus(String path) Gets the file or directory status.
String	getUnderFSType() Returns the name of the under filesystem implementation.
boolean	isDirectory(String path) Checks if a directory exists in under file system.
boolean	isExistingDirectory(String path) Checks if a directory exists in under file system.
boolean	isFile(String path) Checks if a file exists in under file system.
boolean	isObjectStorage()
boolean	isSeekable() Denotes if the under storage supports seeking.
UfsStatus[]	listStatus(String path) Returns an array of statuses of the files and directories in the directory denoted by this abstract pathname.
UfsStatus[]	listStatus(String path, ListOptions options) Returns an array of statuses of the files and directories in the directory denoted by this abstract pathname, with options.
boolean	mkdirs(String path) Creates the directory named by this abstract pathname.
boolean	mkdirs(String path, MkdirsOptions options) Creates the directory named by this abstract pathname, with specified MkdirsOptions.
InputStream	open(String path) Opens an InputStream for a file in under filesystem at the indicated path.
InputStream	open(String path, OpenOptions options) Opens an InputStream for a file in under filesystem at the indicated path.
InputStream	openExistingFile(String path) Opens an InputStream for a file in under filesystem at the indicated path.
InputStream	openExistingFile(String path, OpenOptions options) Opens an InputStream for a file in under filesystem at the indicated path.
boolean	renameDirectory(String src, String dst) Renames a directory from src to dst in under file system.
boolean	renameFile(String src, String dst) Renames a file from src to dst in under file system.
boolean	renameRenamableDirectory(String src, String dst) Renames a directory from src to dst in under file system.
boolean	renameRenamableFile(String src, String dst) Renames a file from src to dst in under file system.
AlluxioURI	resolveUri(AlluxioURI ufsBaseUri, String alluxioPath) Returns an AlluxioURI representation for the UnderFileSystem given a base UFS URI, and the Alluxio path from the base.
void	setAclEntries(String path, List<AclEntry> aclEntries) Sets the access control list of a file or directory in under file system.
void	setMode(String path, short mode) Changes posix file mode.
void	setOwner(String path, String owner, String group) Sets the user and group of the given path.
boolean	startActiveSyncPolling(long txId) Start Active Sync.
void	startSync(AlluxioURI uri) Add Sync Point.
boolean	stopActiveSyncPolling() Stop Active Sync.
void	stopSync(AlluxioURI uri) Stop Sync Point.
boolean	supportsActiveSync() Whether this type of UFS supports active sync.
boolean	supportsFlush() Whether this type of UFS supports flush.

Methods inherited from interface java.io.Closeable

close

Method Detail

cleanup

void cleanup()
      throws IOException

Cleans up the under file system. If any data or files are created and not completed/aborted correctly in normal ways, they should be cleaned in this method.

Throws:

IOException

connectFromMaster

void connectFromMaster(String hostname)
                throws IOException

Takes any necessary actions required to establish a connection to the under file system from the given master host e.g. logging in

Depending on the implementation this may be a no-op

Parameters:

hostname - the host that wants to connect to the under file system

Throws:

IOException

connectFromWorker

void connectFromWorker(String hostname)
                throws IOException

Takes any necessary actions required to establish a connection to the under file system from the given worker host e.g. logging in

Depending on the implementation this may be a no-op

Parameters:

hostname - the host that wants to connect to the under file system

Throws:

IOException

create

OutputStream create(String path)
             throws IOException

Creates a file in the under file system with the indicated name. Parents directories will be created recursively.

Parameters:

path - the file name

Returns:

A OutputStream object

Throws:

IOException

create

OutputStream create(String path,
                    CreateOptions options)
             throws IOException

Creates a file in the under file system with the specified CreateOptions. Implementations should make sure that the path under creation appears in listings only after a successful close and that contents are written in its entirety or not at all.

Parameters:

path - the file name

options - the options for create

Returns:

A OutputStream object

Throws:

IOException

createNonexistingFile

OutputStream createNonexistingFile(String path)
                            throws IOException

Creates a file in the under file system with the indicated name. Similar to create(String) but deals with the delete-then-create eventual consistency issue.

Parameters:

path - the file name

Returns:

A OutputStream object

Throws:

IOException

createNonexistingFile

OutputStream createNonexistingFile(String path,
                                   CreateOptions options)
                            throws IOException

Creates a file in the under file system with the specified CreateOptions. Similar to create(String, CreateOptions) but deals with the delete-then-create eventual consistency issue.

Parameters:

path - the file name

options - the options for create

Returns:

A OutputStream object

Throws:

IOException

deleteDirectory

boolean deleteDirectory(String path)
                 throws IOException

Deletes a directory from the under file system with the indicated name non-recursively. A non-recursive delete is successful only if the directory is empty.

Parameters:

path - of the directory to delete

Returns:

true if directory was found and deleted, false otherwise

Throws:

IOException

deleteDirectory

boolean deleteDirectory(String path,
                        DeleteOptions options)
                 throws IOException

Deletes a directory from the under file system with the indicated name.

Parameters:

path - of the directory to delete

options - for directory delete semantics

Returns:

true if directory was found and deleted, false otherwise

Throws:

IOException

deleteExistingDirectory

boolean deleteExistingDirectory(String path)
                         throws IOException

Deletes a directory from the under file system. Similar to deleteDirectory(String) but deals with the create-delete eventual consistency issue.

Parameters:

path - of the directory to delete

Returns:

true if directory was found and deleted, false otherwise

Throws:

IOException

deleteExistingDirectory

boolean deleteExistingDirectory(String path,
                                DeleteOptions options)
                         throws IOException

Deletes a directory from the under file system with the indicated name. Similar to deleteDirectory(String, DeleteOptions) but deals with the create-then-delete eventual consistency issue.

Parameters:

path - of the directory to delete

options - for directory delete semantics

Returns:

true if directory was found and deleted, false otherwise

Throws:

IOException

deleteFile

boolean deleteFile(String path)
            throws IOException

Deletes a file from the under file system with the indicated name.

Parameters:

path - of the file to delete

Returns:

true if file was found and deleted, false otherwise

Throws:

IOException

deleteExistingFile

boolean deleteExistingFile(String path)
                    throws IOException

Deletes a file from the under file system with the indicated name. Similar to deleteFile(String) but deals with the create-then-delete eventual consistency issue.

Parameters:

path - of the file to delete

Returns:

true if file was found and deleted, false otherwise

Throws:

IOException

exists

boolean exists(String path)
        throws IOException

Checks if a file or directory exists in under file system.

Parameters:

path - the absolute path

Returns:

true if the path exists, false otherwise

Throws:

IOException

getAclPair

@Nullable
Pair<AccessControlList,DefaultAccessControlList> getAclPair(String path)
                                                               throws IOException

Gets the ACL and the Default ACL of a file or directory in under file system.

Parameters:

path - the path to the file or directory

Returns:

the access control list, along with a Default ACL if it is a directory return null if ACL is unsupported or disabled

Throws:

IOException - if ACL is supported and enabled but cannot be retrieved

getBlockSizeByte

@Deprecated
long getBlockSizeByte(String path)
                           throws IOException

Deprecated. block size should be returned as part of the UfsFileStatus from getFileStatus(String) or getExistingFileStatus(String)

Gets the block size of a file in under file system, in bytes.

Parameters:

path - the file name

Returns:

the block size in bytes

Throws:

IOException

getConfiguration

default AlluxioConfiguration getConfiguration()
                                       throws IOException

Gets the under file system configuration.

Returns:

the configuration

Throws:

IOException

getDirectoryStatus

UfsDirectoryStatus getDirectoryStatus(String path)
                               throws IOException

Gets the directory status. The caller must already know the path is a directory. This method will throw an exception if the path exists, but is a file.

Parameters:

path - the path to the directory

Returns:

the directory status

Throws:

FileNotFoundException - when the path does not exist

IOException

getExistingDirectoryStatus

UfsDirectoryStatus getExistingDirectoryStatus(String path)
                                       throws IOException

Gets the directory status. Similar to getDirectoryStatus(String) but deals with the write-then-get-status eventual consistency issue.

Parameters:

path - the path to the directory

Returns:

the directory status

Throws:

IOException

getFileLocations

List<String> getFileLocations(String path)
                       throws IOException

Gets the list of locations of the indicated path.

Parameters:

path - the file name

Returns:

The list of locations

Throws:

IOException

getFileLocations

List<String> getFileLocations(String path,
                              FileLocationOptions options)
                       throws IOException

Gets the list of locations of the indicated path given options.

Parameters:

path - the file name

options - method options

Returns:

The list of locations

Throws:

IOException

getFileStatus

UfsFileStatus getFileStatus(String path)
                     throws IOException

Gets the file status. The caller must already know the path is a file. This method will throw an exception if the path exists, but is a directory.

Parameters:

path - the path to the file

Returns:

the file status

Throws:

FileNotFoundException - when the path does not exist

IOException

getExistingFileStatus

UfsFileStatus getExistingFileStatus(String path)
                             throws IOException

Gets the file status. Similar to getFileStatus(String) but deals with the write-then-get-status eventual consistency issue.

Parameters:

path - the path to the file

Returns:

the file status

Throws:

IOException

getFingerprint

String getFingerprint(String path)

Computes and returns a fingerprint for the path. The fingerprint is used to determine if two UFS files are identical. The fingerprint must be deterministic, and must not change if a file is only renamed (identical content and permissions). Returns Constants.INVALID_UFS_FINGERPRINT if there is any error.

Parameters:

path - the path to compute the fingerprint for

Returns:

the string representing the fingerprint

getOperationMode

UfsMode getOperationMode(Map<String,UfsMode> physicalUfsState)

An UnderFileSystem may be composed of one or more "physical UFS"s. This method is used to determine the operation mode based on the physical UFS operation modes. For example, if this UnderFileSystem is composed of physical UFS hdfs://ns1/ and hdfs://ns2/ with read operations split b/w the two, with physicalUfsState{hdfs://ns1/:NO_ACCESS, hdfs://ns2/:READ_WRITE} this method can return READ_ONLY to allow reads to proceed from hdfs://ns2/.

Parameters:

physicalUfsState - the state of physical UFSs for this UnderFileSystem; keys are expected to be normalized (ending with /)

Returns:

the desired operation mode for this UFS

getPhysicalStores

List<String> getPhysicalStores()

An UnderFileSystem may be composed of one or more "physical UFS"s. This method returns all underlying physical stores; normalized with only scheme and authority.

Returns:

physical UFSs this UnderFileSystem is composed of

getSpace

long getSpace(String path,
              UnderFileSystem.SpaceType type)
       throws IOException

Queries the under file system about the space of the indicated path (e.g., space left, space used and etc).

Parameters:

path - the path to query

type - the type of queries

Returns:

The space in bytes

Throws:

IOException

getStatus

UfsStatus getStatus(String path)
             throws IOException

Gets the file or directory status. The caller does not need to know if the path is a file or directory. This method will determine the path type, and will return the appropriate status.

Parameters:

path - the path to get the status

Returns:

the file or directory status

Throws:

FileNotFoundException - when the path does not exist

IOException

getExistingStatus

UfsStatus getExistingStatus(String path)
                     throws IOException

Gets the file or directory status. Similar to getStatus(String) but deals with the write-then-get-status eventual consistency issue.

Parameters:

path - the path to get the status

Returns:

the file or directory status

Throws:

IOException

getUnderFSType

String getUnderFSType()

Returns the name of the under filesystem implementation. The name should be lowercase and not include any spaces, e.g. "hdfs", "s3".

Returns:

name of the under filesystem implementation

isDirectory

boolean isDirectory(String path)
             throws IOException

Checks if a directory exists in under file system.

Parameters:

path - the absolute directory path

Returns:

true if the path exists and is a directory, false otherwise

Throws:

IOException

isExistingDirectory

boolean isExistingDirectory(String path)
                     throws IOException

Checks if a directory exists in under file system. Similar to isDirectory(String) but deals with the write-then-list eventual consistency issue.

Parameters:

path - the absolute directory path

Returns:

true if the path exists and is a directory, false otherwise

Throws:

IOException

isFile

boolean isFile(String path)
        throws IOException

Checks if a file exists in under file system.

Parameters:

path - the absolute file path

Returns:

true if the path exists and is a file, false otherwise

Throws:

IOException

isObjectStorage

boolean isObjectStorage()

Returns:

true if under storage is an object store, false otherwise

isSeekable

boolean isSeekable()

Denotes if the under storage supports seeking. Note, the under file system subclass that returns true for this method should return the input stream extending SeekableUnderFileInputStream in the open(String, OpenOptions) method.

Returns:

true if under storage is seekable, false otherwise

listStatus

@Nullable
UfsStatus[] listStatus(String path)
                          throws IOException

Returns an array of statuses of the files and directories in the directory denoted by this abstract pathname.

If this abstract pathname does not denote a directory, then this method returns null. Otherwise an array of statuses is returned, one for each file or directory in the directory. Names denoting the directory itself and the directory's parent directory are not included in the result. Each string is a file name rather than a complete path.

There is no guarantee that the name strings in the resulting array will appear in any specific order; they are not, in particular, guaranteed to appear in alphabetical order.

Parameters:

path - the abstract pathname to list

Returns:

An array with the statuses of the files and directories in the directory denoted by this abstract pathname. The array will be empty if the directory is empty. Returns null if this abstract pathname does not denote a directory.

Throws:

IOException

listStatus

@Nullable
UfsStatus[] listStatus(String path,
                                 ListOptions options)
                          throws IOException

Returns an array of statuses of the files and directories in the directory denoted by this abstract pathname, with options.

If this abstract pathname does not denote a directory, then this method returns null. Otherwise an array of statuses is returned, one for each file or directory. Names denoting the directory itself and the directory's parent directory are not included in the result. Each string is a path relative to the given directory.

There is no guarantee that the name strings in the resulting array will appear in any specific order; they are not, in particular, guaranteed to appear in alphabetical order.

Parameters:

path - the abstract pathname to list

options - for list directory

Returns:

An array of statuses naming the files and directories in the directory denoted by this abstract pathname. The array will be empty if the directory is empty. Returns null if this abstract pathname does not denote a directory.

Throws:

IOException

mkdirs

boolean mkdirs(String path)
        throws IOException

Creates the directory named by this abstract pathname. If the folder already exists, the method returns false. The method creates any necessary but nonexistent parent directories.

Parameters:

path - the folder to create

Returns:

true if and only if the directory was created; false otherwise

Throws:

IOException

mkdirs

boolean mkdirs(String path,
               MkdirsOptions options)
        throws IOException

Creates the directory named by this abstract pathname, with specified MkdirsOptions. If the folder already exists, the method returns false.

Parameters:

path - the folder to create

options - the options for mkdirs

Returns:

true if and only if the directory was created; false otherwise

Throws:

IOException

open

InputStream open(String path)
          throws IOException

Opens an InputStream for a file in under filesystem at the indicated path.

Parameters:

path - the file name

Returns:

The InputStream object

Throws:

IOException

open

InputStream open(String path,
                 OpenOptions options)
          throws IOException

Opens an InputStream for a file in under filesystem at the indicated path.

Parameters:

path - the file name

options - to open input stream

Returns:

The InputStream object

Throws:

IOException

openExistingFile

InputStream openExistingFile(String path)
                      throws IOException

Opens an InputStream for a file in under filesystem at the indicated path. Similar to open(String) but deals with the write-then-read eventual consistency issue.

Parameters:

path - the file name

Returns:

The InputStream object

Throws:

IOException

openExistingFile

InputStream openExistingFile(String path,
                             OpenOptions options)
                      throws IOException

Opens an InputStream for a file in under filesystem at the indicated path. Similar to open(String, OpenOptions) but deals with the write-then-read eventual consistency issue.

Parameters:

path - the file name

options - to open input stream

Returns:

The InputStream object

Throws:

IOException

renameDirectory

boolean renameDirectory(String src,
                        String dst)
                 throws IOException

Renames a directory from src to dst in under file system.

Parameters:

src - the source directory path

dst - the destination directory path

Returns:

true if succeed, false otherwise

Throws:

IOException

renameRenamableDirectory

boolean renameRenamableDirectory(String src,
                                 String dst)
                          throws IOException

Renames a directory from src to dst in under file system. Similar to renameDirectory(String, String) but deals with the write-src-then-rename and delete-dst-then-rename eventual consistency issue.

Parameters:

src - the source directory path

dst - the destination directory path

Returns:

true if succeed, false otherwise

Throws:

IOException

renameFile

boolean renameFile(String src,
                   String dst)
            throws IOException

Renames a file from src to dst in under file system.

Parameters:

src - the source file path

dst - the destination file path

Returns:

true if succeed, false otherwise

Throws:

IOException

renameRenamableFile

boolean renameRenamableFile(String src,
                            String dst)
                     throws IOException

Renames a file from src to dst in under file system. Similar to renameFile(String, String) but deals with the write-src-then-rename and delete-dst-then-rename eventual consistency issue.

Parameters:

src - the source file path

dst - the destination file path

Returns:

true if succeed, false otherwise

Throws:

IOException

resolveUri

AlluxioURI resolveUri(AlluxioURI ufsBaseUri,
                      String alluxioPath)

Returns an AlluxioURI representation for the UnderFileSystem given a base UFS URI, and the Alluxio path from the base. The default implementation simply concatenates the path to the base URI. This should be overridden if a subclass needs alternate functionality.

Parameters:

ufsBaseUri - the base AlluxioURI in the ufs

alluxioPath - the path in Alluxio from the given base

Returns:

the UFS AlluxioURI representing the Alluxio path

setAclEntries

void setAclEntries(String path,
                   List<AclEntry> aclEntries)
            throws IOException

Sets the access control list of a file or directory in under file system. if the ufs does not support acls, this is a noop. This will overwrite the ACL and defaultACL in the UFS.

Parameters:

path - the path to the file or directory

aclEntries - the access control list + default acl represented in a list of acl entries

Throws:

IOException

setMode

void setMode(String path,
             short mode)
      throws IOException

Changes posix file mode.

Parameters:

path - the path of the file

mode - the mode to set in short format, e.g. 0777

Throws:

IOException

setOwner

void setOwner(String path,
              String owner,
              String group)
       throws IOException

Sets the user and group of the given path. An empty implementation should be provided if unsupported.

Parameters:

path - the path of the file

owner - the new owner to set, unchanged if null

group - the new group to set, unchanged if null

Throws:

IOException

supportsFlush

boolean supportsFlush()
               throws IOException

Whether this type of UFS supports flush.

Returns:

true if this type of UFS supports flush, false otherwise

Throws:

IOException

supportsActiveSync

boolean supportsActiveSync()

Whether this type of UFS supports active sync.

Returns:

true if this type of UFS supports active sync, false otherwise

getActiveSyncInfo

SyncInfo getActiveSyncInfo()
                    throws IOException

Return the active sync info for the specified syncPoints.

Returns:

active sync info consisting of what changed for these sync points

Throws:

IOException

startSync

void startSync(AlluxioURI uri)
        throws IOException

Add Sync Point.

Parameters:

uri - ufs uri to start

Throws:

IOException

stopSync

void stopSync(AlluxioURI uri)
       throws IOException

Stop Sync Point.

Parameters:

uri - ufs uri to stop

Throws:

IOException

startActiveSyncPolling

boolean startActiveSyncPolling(long txId)
                        throws IOException

Start Active Sync.

Parameters:

txId - the transaction id to start receiving event

Returns:

true if active sync started

Throws:

IOException

stopActiveSyncPolling

boolean stopActiveSyncPolling()
                       throws IOException

Stop Active Sync.

Returns:

true if active sync stopped

Throws:

IOException