Package org.apache.lucene.store

Class NativeUnixDirectory

java.lang.Object

org.apache.lucene.store.Directory

org.apache.lucene.store.BaseDirectory

org.apache.lucene.store.FSDirectory

org.apache.lucene.store.NativeUnixDirectory

All Implemented Interfaces:

Closeable, AutoCloseable

public class NativeUnixDirectory
extends FSDirectory

A Directory implementation for all Unixes that uses DIRECT I/O to bypass OS level IO caching during merging. For all other cases (searching, writing) we delegate to the provided Directory instance.

See Overview for more details.

To use this you must compile NativePosixUtil.cpp (exposes Linux-specific APIs through JNI) for your platform, by running ant build-native-unix, and then putting the resulting libNativePosixUtil.so (from lucene/build/native) onto your dynamic linker search path.

WARNING: this code is very new and quite easily could contain horrible bugs. For example, here's one known issue: if you use seek in IndexOutput, and then write more than one buffer's worth of bytes, then the file will be wrong. Lucene does not do this today (only writes small number of bytes after seek), but that may change.

This directory passes Solr and Lucene tests on Linux and OS X; other Unixes should work but have not been tested! Use at your own risk.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static final class	NativeUnixDirectory.NativeUnixIndexInput
private static final class	NativeUnixDirectory.NativeUnixIndexOutput

Nested classes/interfaces inherited from class org.apache.lucene.store.FSDirectory

FSDirectory.FSIndexOutput

Field Summary

Fields

Modifier and Type	Field	Description
private static final long	ALIGN
private static final long	ALIGN_NOT_MASK
static final int	DEFAULT_MERGE_BUFFER_SIZE	Default buffer size before writing to disk (256 KB); larger means less IO load but more RAM and direct buffer storage space consumed during merging.
static final long	DEFAULT_MIN_BYTES_DIRECT	Default min expected merge size before direct IO is used (10 MB):
private final Directory	delegate
private final int	mergeBufferSize
private final long	minBytesDirect

Fields inherited from class org.apache.lucene.store.FSDirectory

directory

Fields inherited from class org.apache.lucene.store.BaseDirectory

isOpen, lockFactory

Constructor Summary

Constructors

Constructor	Description
NativeUnixDirectory(Path path, int mergeBufferSize, long minBytesDirect, LockFactory lockFactory, Directory delegate)	Create a new NIOFSDirectory for the named location.
NativeUnixDirectory(Path path, Directory delegate)	Create a new NIOFSDirectory for the named location with FSLockFactory.getDefault().
NativeUnixDirectory(Path path, LockFactory lockFactory, Directory delegate)	Create a new NIOFSDirectory for the named location.

Method Summary

Modifier and Type	Method	Description
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.
IndexInput	openInput(String name, IOContext context)	Opens a stream for reading an existing file.

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

close, createTempOutput, deleteFile, deletePendingFiles, ensureCanRead, fileLength, fsync, getDirectory, getPendingDeletions, listAll, listAll, open, open, rename, sync, syncMetaData, toString

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

ensureOpen, obtainLock

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 Details

ALIGN

private static final long ALIGN

See Also:

• Constant Field Values

ALIGN_NOT_MASK

private static final long ALIGN_NOT_MASK

See Also:

• Constant Field Values

DEFAULT_MERGE_BUFFER_SIZE

public static final int DEFAULT_MERGE_BUFFER_SIZE

Default buffer size before writing to disk (256 KB); larger means less IO load but more RAM and direct buffer storage space consumed during merging.

See Also:

• Constant Field Values

DEFAULT_MIN_BYTES_DIRECT

public static final long DEFAULT_MIN_BYTES_DIRECT

Default min expected merge size before direct IO is used (10 MB):

See Also:

• Constant Field Values

mergeBufferSize

private final int mergeBufferSize

minBytesDirect

private final long minBytesDirect

delegate

private final Directory delegate

Constructor Details

NativeUnixDirectory

public NativeUnixDirectory(Path path,
 int mergeBufferSize,
 long minBytesDirect,
 LockFactory lockFactory,
 Directory delegate)
                    throws IOException

Create a new NIOFSDirectory for the named location.

Parameters:

path - the path of the directory

mergeBufferSize - Size of buffer to use for merging. See DEFAULT_MERGE_BUFFER_SIZE.

minBytesDirect - Merges, or files to be opened for reading, smaller than this will not use direct IO. See DEFAULT_MIN_BYTES_DIRECT

lockFactory - to use

delegate - fallback Directory for non-merges

Throws:

IOException - If there is a low-level I/O error

NativeUnixDirectory

public NativeUnixDirectory(Path path,
 LockFactory lockFactory,
 Directory delegate)
                    throws IOException

Create a new NIOFSDirectory for the named location.

Parameters:

path - the path of the directory

lockFactory - the lock factory to use

delegate - fallback Directory for non-merges

Throws:

IOException - If there is a low-level I/O error

NativeUnixDirectory

public NativeUnixDirectory(Path path,
 Directory delegate)
                    throws IOException

Create a new NIOFSDirectory for the named location with FSLockFactory.getDefault().

Parameters:

path - the path of the directory

delegate - fallback Directory for non-merges

Throws:

IOException - If there is a low-level I/O error

Method Details

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

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.

Overrides:

createOutput in class FSDirectory

Parameters:

name - the name of the file to create.

Throws:

IOException - in case of I/O error