public class

NativeFSLockFactory

extends FSLockFactory
java.lang.Object
   ↳ org.apache.lucene.store.LockFactory
     ↳ org.apache.lucene.store.FSLockFactory
       ↳ org.apache.lucene.store.NativeFSLockFactory

Class Overview

Implements LockFactory using native OS file locks. Note that because this LockFactory relies on java.nio.* APIs for locking, any problems with those APIs will cause locking to fail. Specifically, on certain NFS environments the java.nio.* locks will fail (the lock can incorrectly be double acquired) whereas SimpleFSLockFactory worked perfectly in those same environments. For NFS based access to an index, it's recommended that you try SimpleFSLockFactory first and work around the one limitation that a lock file could be left when the JVM exits abnormally.

The primary benefit of NativeFSLockFactory is that lock files will be properly removed (by the OS) if the JVM has an abnormal exit.

Note that, unlike SimpleFSLockFactory, the existence of leftover lock files in the filesystem on exiting the JVM is fine because the OS will free the locks held against these files even though the files still remain.

If you suspect that this or any other LockFactory is not working properly in your environment, you can easily test it by using VerifyingLockFactory, LockVerifyServer and LockStressTest.

See Also

Summary

[Expand]
Inherited Fields
From class org.apache.lucene.store.FSLockFactory
From class org.apache.lucene.store.LockFactory
Public Constructors
NativeFSLockFactory()
Create a NativeFSLockFactory instance, with null (unset) lock directory.
NativeFSLockFactory(String lockDirName)
Create a NativeFSLockFactory instance, storing lock files into the specified lockDirName:
NativeFSLockFactory(File lockDir)
Create a NativeFSLockFactory instance, storing lock files into the specified lockDir:
Public Methods
void clearLock(String lockName)
Attempt to clear (forcefully unlock and remove) the specified lock.
synchronized Lock makeLock(String lockName)
Return a new Lock instance identified by lockName.
[Expand]
Inherited Methods
From class org.apache.lucene.store.FSLockFactory
From class org.apache.lucene.store.LockFactory
From class java.lang.Object

Public Constructors

public NativeFSLockFactory ()

Create a NativeFSLockFactory instance, with null (unset) lock directory. When you pass this factory to a FSDirectory subclass, the lock directory is automatically set to the directory itsself. Be sure to create one instance for each directory your create!

Throws
IOException

public NativeFSLockFactory (String lockDirName)

Create a NativeFSLockFactory instance, storing lock files into the specified lockDirName:

Parameters
lockDirName where lock files are created.
Throws
IOException

public NativeFSLockFactory (File lockDir)

Create a NativeFSLockFactory instance, storing lock files into the specified lockDir:

Parameters
lockDir where lock files are created.
Throws
IOException

Public Methods

public void clearLock (String lockName)

Attempt to clear (forcefully unlock and remove) the specified lock. Only call this at a time when you are certain this lock is no longer in use.

Parameters
lockName name of the lock to be cleared.
Throws
IOException

public synchronized Lock makeLock (String lockName)

Return a new Lock instance identified by lockName.

Parameters
lockName name of the lock to be created.