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/interfaces inherited from class org.apache.lucene.store.Directory

Directory.IndexInputSlicer

Field Summary

Fields

Modifier and Type	Field	Description
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):

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

DEFAULT_READ_CHUNK_SIZE

Constructor Summary

Constructors

Constructor	Description
NativeUnixDirectory(File path, int mergeBufferSize, long minBytesDirect, Directory delegate)	Create a new NIOFSDirectory for the named location.
NativeUnixDirectory(File path, Directory delegate)	Create a new NIOFSDirectory for the named location.

Method Summary

Modifier and Type	Method	Description
IndexOutput	createOutput(String name, IOContext context)	Creates an IndexOutput for the file with the given name.
IndexInput	openInput(String name, IOContext context)	Returns a stream reading an existing file, with the specified read buffer size.

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

close, deleteFile, fileExists, fileLength, getDirectory, getLockID, getReadChunkSize, listAll, listAll, open, open, setLockFactory, setReadChunkSize, sync, toString

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

clearLock, getLockFactory, makeLock

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

copy, createSlicer

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

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

Constructor Details

NativeUnixDirectory

public NativeUnixDirectory(File path,
 int mergeBufferSize,
 long minBytesDirect,
 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

delegate - fallback Directory for non-merges

Throws:

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

NativeUnixDirectory

public NativeUnixDirectory(File path,
 Directory delegate)
                    throws IOException

Create a new NIOFSDirectory for the named location.

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

Returns a stream reading an existing file, with the specified read buffer size. The particular Directory implementation may ignore the buffer size. Currently the only Directory implementations that respect this parameter are FSDirectory and CompoundFileDirectory.

Must throw FileNotFoundException if the file does not exist (not java.nio.file.NoSuchFileException of Java 7).

Specified by:

openInput in class Directory

Throws:

IOException

createOutput

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

Description copied from class: FSDirectory

Creates an IndexOutput for the file with the given name.

Overrides:

createOutput in class FSDirectory

Throws:

IOException