org.apache.lucene.store

Class FileSwitchDirectory

java.lang.Object

org.apache.lucene.store.Directory

org.apache.lucene.store.FileSwitchDirectory

All Implemented Interfaces:

Closeable, AutoCloseable

public class FileSwitchDirectory
extends Directory

Expert: A Directory instance that switches files between two other Directory instances.

Files with the specified extensions are placed in the primary directory; others are placed in the secondary directory. The provided Set must not change once passed to this class, and must allow multiple threads to call contains at once.

Locks with a name having the specified extensions are delegated to the primary directory; others are delegated to the secondary directory. Ideally, both Directory instances should use the same lock factory.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Constructor and Description
FileSwitchDirectory(Set<String> primaryExtensions, Directory primaryDir, Directory secondaryDir, boolean doClose)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes the store.
IndexOutput	createOutput(String name, IOContext context) Creates a new, empty file in the directory with the given name.
void	deleteFile(String name) Removes an existing file in the directory.
long	fileLength(String name) Returns the length of a file in the directory.
static String	getExtension(String name) Utility method to return a file's extension.
Directory	getPrimaryDir() Return the primary directory
Directory	getSecondaryDir() Return the secondary directory
String[]	listAll() Returns an array of strings, one for each entry in the directory.
Lock	obtainLock(String name) Returns an obtained Lock.
IndexInput	openInput(String name, IOContext context) Returns a stream reading an existing file.
void	renameFile(String source, String dest) Renames source to dest as an atomic operation, where dest does not yet exist in the directory.
void	sync(Collection<String> names) Ensure that any writes to these files are moved to stable storage.

Methods inherited from class org.apache.lucene.store.Directory

copyFrom, ensureOpen, openChecksumInput, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

FileSwitchDirectory

public FileSwitchDirectory(Set<String> primaryExtensions,
                   Directory primaryDir,
                   Directory secondaryDir,
                   boolean doClose)

Method Detail

getPrimaryDir

public Directory getPrimaryDir()

Return the primary directory

getSecondaryDir

public Directory getSecondaryDir()

Return the secondary directory

obtainLock

public Lock obtainLock(String name)
                throws IOException

Description copied from class: Directory

Returns an obtained Lock.

Specified by:

obtainLock in class Directory

Parameters:

name - the name of the lock file

Throws:

LockObtainFailedException - (optional specific exception) if the lock could not be obtained because it is currently held elsewhere.

IOException - if any i/o error occurs attempting to gain the lock

close

public void close()
           throws IOException

Description copied from class: Directory

Closes the store.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in class Directory

Throws:

IOException

listAll

public String[] listAll()
                 throws IOException

Description copied from class: Directory

Returns an array of strings, one for each entry in the directory.

Specified by:

listAll in class Directory

Throws:

IOException - in case of IO error

getExtension

public static String getExtension(String name)

Utility method to return a file's extension.

deleteFile

public void deleteFile(String name)
                throws IOException

Description copied from class: Directory

Removes an existing file in the directory.

Specified by:

deleteFile in class Directory

Throws:

IOException

fileLength

public long fileLength(String name)
                throws IOException

Description copied from class: Directory

Returns the length of a file in the directory. This method follows the following contract:

• Throws FileNotFoundException or NoSuchFileException if the file does not exist.
• Returns a value ≥0 if the file exists, which specifies its length.

Specified by:

fileLength in class Directory

Parameters:

name - the name of the file for which to return the length.

Throws:

IOException - if there was an IO error while retrieving the file's length.

createOutput

public IndexOutput createOutput(String name,
                       IOContext context)
                         throws IOException

Description copied from class: Directory

Creates a new, empty file in the directory with the given name. Returns a stream writing this file.

Specified by:

createOutput in class Directory

Throws:

IOException

sync

public void sync(Collection<String> names)
          throws IOException

Description copied from class: Directory

Ensure that any writes to these files are moved to stable storage. Lucene uses this to properly commit changes to the index, to prevent a machine/OS crash from corrupting the index.
NOTE: Clients may call this method for same files over and over again, so some impls might optimize for that. For other impls the operation can be a noop, for various reasons.

Specified by:

sync in class Directory

Throws:

IOException

renameFile

public void renameFile(String source,
              String dest)
                throws IOException

Description copied from class: Directory

Renames source to dest as an atomic operation, where dest does not yet exist in the directory.

Notes: This method is used by IndexWriter to publish commits. It is ok if this operation is not truly atomic, for example both source and dest can be visible temporarily. It is just important that the contents of dest appear atomically, or an exception is thrown.

Specified by:

renameFile in class Directory

Throws:

IOException

openInput

public IndexInput openInput(String name,
                   IOContext context)
                     throws IOException

Description copied from class: Directory

Returns a stream reading an existing file.

Throws FileNotFoundException or NoSuchFileException if the file does not exist.

Specified by:

openInput in class Directory

Throws:

IOException