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

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the directory.
IndexOutput	createOutput(String name, IOContext context)	Creates a new, empty file in the directory and returns an IndexOutput instance for appending data to this file.
IndexOutput	createTempOutput(String prefix, String suffix, IOContext context)	Creates a new, empty, temporary file in the directory and returns an IndexOutput instance for appending data to this file.
void	deleteFile(String name)	Removes an existing file in the directory.
long	fileLength(String name)	Returns the byte length of a file in the directory.
static String	getExtension(String name)	Utility method to return a file's extension.
Set<String>	getPendingDeletions()	Returns a set of files currently pending deletion in this directory.
Directory	getPrimaryDir()	Return the primary directory
Directory	getSecondaryDir()	Return the secondary directory
String[]	listAll()	Returns names of all files stored in this directory.
Lock	obtainLock(String name)	Acquires and returns a Lock for a file with the given name.
IndexInput	openInput(String name, IOContext context)	Opens a stream for reading an existing file.
void	rename(String source, String dest)	Renames source file to dest file where dest must not already exist in the directory.
void	sync(Collection<String> names)	Ensures that any writes to these files are moved to stable storage (made durable).
void	syncMetaData()	Ensures that directory metadata, such as recent file renames, are moved to stable storage.

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

copyFrom, ensureOpen, getTempFileName, openChecksumInput, toString

Methods inherited from class java.lang.Object

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

Constructor Details

FileSwitchDirectory

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

Method Details

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

Acquires and returns a Lock for a file with the given name.

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 directory.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in class Directory

Throws:

IOException

listAll

public String[] listAll()
                 throws IOException

Description copied from class: Directory

Returns names of all files stored in this directory. The output must be in sorted (UTF-16, java's String.compareTo(java.lang.String)) order.

Specified by:

listAll in class Directory

Throws:

IOException - in case of I/O 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.

This method must throw either NoSuchFileException or FileNotFoundException if name points to a non-existing file.

Specified by:

deleteFile in class Directory

Parameters:

name - the name of an existing file.

Throws:

IOException - in case of I/O error

fileLength

public long fileLength(String name)
                throws IOException

Description copied from class: Directory

Returns the byte length of a file in the directory.

This method must throw either NoSuchFileException or FileNotFoundException if name points to a non-existing file.

Specified by:

fileLength in class Directory

Parameters:

name - the name of an existing file.

Throws:

IOException - in case of I/O error

createOutput

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

Description copied from class: Directory

Creates a new, empty file in the directory and returns an IndexOutput instance for appending data to this file.

This method must throw FileAlreadyExistsException if the file already exists.

Specified by:

createOutput in class Directory

Parameters:

name - the name of the file to create.

Throws:

IOException - in case of I/O error

createTempOutput

public IndexOutput createTempOutput(String prefix,
 String suffix,
 IOContext context)
                             throws IOException

Description copied from class: Directory

Creates a new, empty, temporary file in the directory and returns an IndexOutput instance for appending data to this file.

The temporary file name (accessible via IndexOutput.getName()) will start with prefix, end with suffix and have a reserved file extension .tmp.

Specified by:

createTempOutput in class Directory

Throws:

IOException

sync

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

Description copied from class: Directory

Ensures that any writes to these files are moved to stable storage (made durable).

Lucene uses this to properly commit changes to the index, to prevent a machine/OS crash from corrupting the index.

Specified by:

sync in class Directory

Throws:

IOException

See Also:

• Directory.syncMetaData()

rename

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

Description copied from class: Directory

Renames source file to dest file where dest must not already exist in the directory.

It is permitted for this operation to not be truly atomic, for example both source and dest can be visible temporarily in Directory.listAll(). However, the implementation of this method must ensure the content of dest appears as the entire source atomically. So once dest is visible for readers, the entire content of previous source is visible.

This method is used by IndexWriter to publish commits.

Specified by:

rename in class Directory

Throws:

IOException

syncMetaData

public void syncMetaData()
                  throws IOException

Description copied from class: Directory

Ensures that directory metadata, such as recent file renames, are moved to stable storage.

Specified by:

syncMetaData in class Directory

Throws:

IOException

See Also:

• Directory.sync(Collection)

openInput

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

Description copied from class: Directory

Opens a stream for reading an existing file.

This method must throw either NoSuchFileException or FileNotFoundException if name points to a non-existing file.

Specified by:

openInput in class Directory

Parameters:

name - the name of an existing file.

Throws:

IOException - in case of I/O error

getPendingDeletions

public Set<String> getPendingDeletions()
                                throws IOException

Description copied from class: Directory

Returns a set of files currently pending deletion in this directory.

Specified by:

getPendingDeletions in class Directory

Throws:

IOException