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.

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

Field Summary

Fields

Modifier and Type	Field and Description
static 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 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

directory

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

isOpen, lockFactory

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
IndexOutput	createOutput(String name, IOContext context)
IndexInput	openInput(String name, IOContext context)

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 Detail

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 Detail

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

lockFactory - to use

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(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 Detail

openInput

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

Specified by:

openInput in class Directory

Throws:

IOException

createOutput

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

Overrides:

createOutput in class FSDirectory

Throws:

IOException