Package org.apache.lucene.store

Class FilterDirectory

java.lang.Object

org.apache.lucene.store.Directory

org.apache.lucene.store.FilterDirectory

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

LockValidatingDirectoryWrapper, NRTCachingDirectory, SleepingLockWrapper, TrackingDirectoryWrapper

public abstract class FilterDirectory
extends Directory

Directory implementation that delegates calls to another directory. This class can be used to add limitations on top of an existing Directory implementation such as NRTCachingDirectory or to add additional sanity checks for tests. However, if you plan to write your own Directory implementation, you should consider extending directly Directory or BaseDirectory rather than try to reuse functionality of existing Directorys by extending this class.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Field Summary

Fields

Modifier and Type	Field	Description
protected Directory	in

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	FilterDirectory(Directory in)	Sole constructor, typically called from sub-classes.

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.
protected void	ensureOpen()	Ensures this directory is still open.
long	fileLength(String name)	Returns the byte length of a file in the directory.
Directory	getDelegate()	Return the wrapped Directory.
Set<String>	getPendingDeletions()	Returns a set of files currently pending deletion in this 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.
String	toString()
static Directory	unwrap(Directory dir)	Get the wrapped instance by dir as long as this reader is an instance of FilterDirectory.

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

copyFrom, getTempFileName, openChecksumInput

Methods inherited from class java.lang.Object

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

Field Detail

in

protected final Directory in

Constructor Detail

FilterDirectory

protected FilterDirectory(Directory in)

Sole constructor, typically called from sub-classes.

Method Detail

unwrap

public static Directory unwrap(Directory dir)

Get the wrapped instance by dir as long as this reader is an instance of FilterDirectory.

getDelegate

public final Directory getDelegate()

Return the wrapped Directory.

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

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

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

toString

public String toString()

Overrides:

toString in class Directory

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

ensureOpen

protected void ensureOpen()
                   throws AlreadyClosedException

Description copied from class: Directory

Ensures this directory is still open.

Overrides:

ensureOpen in class Directory

Throws:

AlreadyClosedException - if this directory is closed.