NativeFSLockFactory (Lucene 2.2.0 API)

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org.apache.lucene.store

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Class NativeFSLockFactory

java.lang.Object
  org.apache.lucene.store.LockFactory
      org.apache.lucene.store.NativeFSLockFactory
 
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public class NativeFSLockFactory
extends LockFactory

Implements LockFactory using native OS file locks (available through java.nio.*). Note that for certain filesystems native locks are possible but must be explicity configured and enabled (and may be disabled by default). For example, for NFS servers there sometimes must be a separate lockd process running, and other configuration may be required such as running the server in kernel mode. Other filesystems may not even support native OS locks in which case you must use a different LockFactory implementation.

The advantage of this lock factory over SimpleFSLockFactory is that the locks should be "correct", whereas SimpleFSLockFactory uses java.io.File.createNewFile which has warnings about not using it for locking. Furthermore, if the JVM crashes, the OS will free any held locks, whereas SimpleFSLockFactory will keep the locks held, requiring manual removal before re-running Lucene. 数据挖掘实验室

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. 数据挖掘交友

See Also:

LockFactory

NativeFSLockFactory

public NativeFSLockFactory(String lockDirName)
                    throws IOException 数据挖掘论坛 

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

Parameters:

lockDirName - where lock files are created.

Throws:

IOException

NativeFSLockFactory

public NativeFSLockFactory(File lockDir)
                    throws IOException 数据挖掘工具 

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

Parameters:

lockDir - where lock files are created.

Throws:

IOException

makeLock

public Lock makeLock(String lockName) 
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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 
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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