Package org.apache.lucene.store

Class SimpleFSLockFactory

java.lang.Object

org.apache.lucene.store.LockFactory

org.apache.lucene.store.FSLockFactory

org.apache.lucene.store.SimpleFSLockFactory

public class SimpleFSLockFactory
extends FSLockFactory

Implements LockFactory using File.createNewFile().

NOTE: the javadocs for File.createNewFile() contain a vague yet spooky warning about not using the API for file locking. This warning was added due to this bug, and in fact the only known problem with using this API for locking is that the Lucene write lock may not be released when the JVM exits abnormally.

When this happens, a LockObtainFailedException is hit when trying to create a writer, in which case you need to explicitly clear the lock file first. You can either manually remove the file, or use the IndexWriter.unlock(Directory) API. But, first be certain that no writer is in fact writing to the index otherwise you can easily corrupt your index.

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:

LockFactory

Field Summary

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

lockDir

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

lockPrefix

Constructor Summary

Constructors

Constructor	Description
SimpleFSLockFactory()	Create a SimpleFSLockFactory instance, with null (unset) lock directory.
SimpleFSLockFactory(File lockDir)	Instantiate using the provided directory (as a File instance).
SimpleFSLockFactory(String lockDirName)	Instantiate using the provided directory name (String).

Method Summary

Modifier and Type	Method	Description
void	clearLock(String lockName)	Attempt to clear (forcefully unlock and remove) the specified lock.
Lock	makeLock(String lockName)	Return a new Lock instance identified by lockName.

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

getLockDir, setLockDir, toString

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

getLockPrefix, setLockPrefix

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleFSLockFactory

public SimpleFSLockFactory()

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

SimpleFSLockFactory

public SimpleFSLockFactory(File lockDir)

Instantiate using the provided directory (as a File instance).

Parameters:

lockDir - where lock files should be created.

SimpleFSLockFactory

public SimpleFSLockFactory(String lockDirName)

Instantiate using the provided directory name (String).

Parameters:

lockDirName - where lock files should be created.

Method Detail

makeLock

public Lock makeLock(String lockName)

Description copied from class: LockFactory

Return a new Lock instance identified by lockName.

Specified by:

makeLock in class LockFactory

Parameters:

lockName - name of the lock to be created.

clearLock

public void clearLock(String lockName)
               throws IOException

Description copied from class: LockFactory

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.

Specified by:

clearLock in class LockFactory

Parameters:

lockName - name of the lock to be cleared.

Throws:

IOException