alluxio.util.io

Class PathUtils

java.lang.Object

alluxio.util.io.PathUtils

@ThreadSafe
public final class PathUtils
extends Object

Utilities related to both Alluxio paths like AlluxioURI and local file paths.

Method Summary

Modifier and Type	Method and Description
static String	cleanPath(String path) Checks and normalizes the given path.
static String	concatPath(Object base, Object... paths) Joins each element in paths in order, separated by AlluxioURI.SEPARATOR.
static String	concatPath(Object base, Object path) Joins two path elements, separated by AlluxioURI.SEPARATOR.
static String	concatUfsPath(String base, String path) Join two path elements for ufs, separated by AlluxioURI.SEPARATOR.
static AlluxioURI	convertAlluxioPathToUfsPath(AlluxioURI alluxioPath, AlluxioURI ufsRootPath) Converts the Alluxio based path to UfsBaseFileSystem based path if needed.
static AlluxioURI	convertUfsPathToAlluxioPath(AlluxioURI ufsPath, AlluxioURI ufsRootPath) Converts the UFS path back to Alluxio path.
static AlluxioURI	findLowestCommonAncestor(Collection<AlluxioURI> paths)
static String[]	getCleanedPathComponents(String path) Get the components of a path that has already been cleaned.
static String	getFirstLevelDirectory(String path) Gets the first level directory of the path.
static String	getParent(String path) Gets the parent of the file at a path.
static String	getParentCleaned(String cleanedPath) The same as getParent(java.lang.String) except does not clean the path before getting the parent.
static String[]	getPathComponents(String path) Gets the path components of the given path.
static String	getPermanentFileName(String path)
static String	getPersistentTmpPath(AlluxioConfiguration ufsConfiguration, String path) Get temp path for async persistence job.
static List<String>	getPossibleMountPoints(String path) Returns the list of possible mount points of the given path.
static boolean	hasPrefix(String path, String prefix) Checks whether the given path contains the given prefix.
static boolean	isRoot(String path) Checks if the given path is the root.
static boolean	isTemporaryFileName(String path) Determines whether the given path is a temporary file name generated by Alluxio.
static String	normalizePath(String path, String separator) Adds a trailing separator if it does not exist in path.
static String	subtractPaths(String path, String prefix) Removes the prefix from the path, yielding a relative path from the second path to the first.
static String	temporaryFileName(long nonce, String path) Generates a deterministic temporary file name for the a path and a file id and a nonce.
static String	uniqPath() Creates a unique path based off the caller.
static void	validatePath(String path) Checks if the given path is properly formed.

Methods inherited from class java.lang.Object

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

Method Detail

cleanPath

public static String cleanPath(String path)
                        throws InvalidPathException

Checks and normalizes the given path.

Parameters:

path - The path to clean up

Returns:

a normalized version of the path, with single separators between path components and dot components resolved

Throws:

InvalidPathException - if the path is invalid

concatPath

public static String concatPath(Object base,
                                Object path)

Joins two path elements, separated by AlluxioURI.SEPARATOR.

Note that empty element in base or paths is ignored.

Parameters:

base - base path

path - path element to concatenate

Returns:

joined path

concatPath

public static String concatPath(Object base,
                                Object... paths)
                         throws IllegalArgumentException

Joins each element in paths in order, separated by AlluxioURI.SEPARATOR.

For example,

 
 concatPath("/myroot/", "dir", 1L, "filename").equals("/myroot/dir/1/filename");
 concatPath("alluxio://myroot", "dir", "filename").equals("alluxio://myroot/dir/filename");
 concatPath("myroot/", "/dir/", "filename").equals("myroot/dir/filename");
 concatPath("/", "dir", "filename").equals("/dir/filename");
 
 

Note that empty element in base or paths is ignored.

Parameters:

base - base path

paths - paths to concatenate

Returns:

joined path

Throws:

IllegalArgumentException - if base or paths is null

findLowestCommonAncestor

public static AlluxioURI findLowestCommonAncestor(Collection<AlluxioURI> paths)

Parameters:

paths - the set of paths

Returns:

the lowest common ancestor, or null if paths is null or empty

getParent

public static String getParent(String path)
                        throws InvalidPathException

Gets the parent of the file at a path.

Parameters:

path - The path

Returns:

the parent path of the file; this is "/" if the given path is the root

Throws:

InvalidPathException - if the path is invalid

getParentCleaned

public static String getParentCleaned(String cleanedPath)
                               throws InvalidPathException

The same as getParent(java.lang.String) except does not clean the path before getting the parent.

Parameters:

cleanedPath - the path that has been cleaned

Returns:

the parent path of the file; this is "/" if the given path is the root

Throws:

InvalidPathException - if the path is invalid

getFirstLevelDirectory

public static String getFirstLevelDirectory(String path)
                                     throws InvalidPathException

Gets the first level directory of the path. For example,

 
 getFirstLevelDirectory("/a/xx/").equals("/a");
 getFirstLevelDirectory("/a/").equals("/a");
 
 

Parameters:

path - the path

Returns:

the first level directory of the path;

Throws:

InvalidPathException - if the path is the root or invalid

concatUfsPath

public static String concatUfsPath(String base,
                                   String path)

Join two path elements for ufs, separated by AlluxioURI.SEPARATOR. For example,

 
 concatUfsPath("s3://myroot/", "filename").equals("s3://myroot/filename");
 concatUfsPath("s3://", "filename").equals("s3://filename");
 
 

Parameters:

base - base path

path - path element to concatenate

Returns:

joined path

getPersistentTmpPath

public static String getPersistentTmpPath(AlluxioConfiguration ufsConfiguration,
                                          String path)

Get temp path for async persistence job.

Parameters:

ufsConfiguration - the ufs configuration

path - ufs path

Returns:

ufs temp path with UUID

getPathComponents

public static String[] getPathComponents(String path)
                                  throws InvalidPathException

Gets the path components of the given path. The first component will be an empty string. "/a/b/c" => {"", "a", "b", "c"} "/" => {""}

Parameters:

path - The path to split

Returns:

the path split into components

Throws:

InvalidPathException - if the path is invalid

getCleanedPathComponents

public static String[] getCleanedPathComponents(String path)
                                         throws InvalidPathException

Get the components of a path that has already been cleaned.

Parameters:

path - the path

Returns:

the components

Throws:

InvalidPathException

subtractPaths

public static String subtractPaths(String path,
                                   String prefix)
                            throws InvalidPathException

Removes the prefix from the path, yielding a relative path from the second path to the first. If the paths are the same, this method returns the empty string.

Parameters:

path - the full path

prefix - the prefix to remove

Returns:

the path with the prefix removed

Throws:

InvalidPathException - if either of the arguments are not valid paths

hasPrefix

public static boolean hasPrefix(String path,
                                String prefix)
                         throws InvalidPathException

Checks whether the given path contains the given prefix. The comparison happens at a component granularity; for example, hasPrefix(/dir/file, /dir) should evaluate to true, while hasPrefix(/dir/file, /d) should evaluate to false.

Parameters:

path - a path

prefix - a prefix

Returns:

whether the given path has the given prefix

Throws:

InvalidPathException - when the path or prefix is invalid

isRoot

public static boolean isRoot(String path)
                      throws InvalidPathException

Checks if the given path is the root.

Parameters:

path - The path to check

Returns:

true if the path is the root

Throws:

InvalidPathException - if the path is invalid

validatePath

public static void validatePath(String path)
                         throws InvalidPathException

Checks if the given path is properly formed.

Parameters:

path - The path to check

Throws:

InvalidPathException - If the path is not properly formed

temporaryFileName

public static String temporaryFileName(long nonce,
                                       String path)

Generates a deterministic temporary file name for the a path and a file id and a nonce.

Parameters:

nonce - a nonce token

path - a file path

Returns:

a deterministic temporary file name

getPermanentFileName

public static String getPermanentFileName(String path)

Parameters:

path - the path of the file, possibly temporary

Returns:

the permanent path of the file if it was temporary, or the original path if it was not

isTemporaryFileName

public static boolean isTemporaryFileName(String path)

Determines whether the given path is a temporary file name generated by Alluxio.

Parameters:

path - the path to check

Returns:

whether the given path is a temporary file name generated by Alluxio

uniqPath

public static String uniqPath()

Creates a unique path based off the caller.

Returns:

unique path based off the caller

normalizePath

public static String normalizePath(String path,
                                   String separator)

Adds a trailing separator if it does not exist in path.

Parameters:

path - the file name

separator - trailing separator to add

Returns:

updated path with trailing separator

getPossibleMountPoints

public static List<String> getPossibleMountPoints(String path)
                                           throws InvalidPathException

Returns the list of possible mount points of the given path. "/a/b/c" => {"/a", "/a/b", "/a/b/c"}

Parameters:

path - the path to get the mount points of

Returns:

a list of paths

Throws:

InvalidPathException

convertAlluxioPathToUfsPath

public static AlluxioURI convertAlluxioPathToUfsPath(AlluxioURI alluxioPath,
                                                     AlluxioURI ufsRootPath)

Converts the Alluxio based path to UfsBaseFileSystem based path if needed. This is a static utility intended for reuse.

UfsBaseFileSystem expects absolute/full file path. The Dora Worker expects absolute/full file path, too. So we need to convert the input path from Alluxio relative path to full UFS path if it is an Alluxio relative path. We do this by checking if the path is leading with the UFS root. If the input path is already considered to be UFS path, it should be leading a UFS path with appropriate scheme. If local file system is used, please add "file://" scheme before the path.

Parameters:

alluxioPath - Alluxio based path

ufsRootPath - the UFS root path to resolve against

Returns:

UfsBaseFileSystem based full path

convertUfsPathToAlluxioPath

public static AlluxioURI convertUfsPathToAlluxioPath(AlluxioURI ufsPath,
                                                     AlluxioURI ufsRootPath)
                                              throws InvalidPathException

Converts the UFS path back to Alluxio path. This is a static utility intended for reuse.

This is the opposite operation to convertAlluxioPathToUfsPath(AlluxioURI, AlluxioURI).

Parameters:

ufsPath - UfsBaseFileSystem based full path

ufsRootPath - the UFS root path to resolve against

Returns:

an Alluxio path

Throws:

InvalidPathException - if ufsPath is not a child of the UFS mounted at Alluxio root