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 final class SimpleFSLockFactory
      extends FSLockFactory

  Implements `LockFactory` using `Files.createFile(java.nio.file.Path, java.nio.file.attribute.FileAttribute<?>...)`.

  The main downside with using this API for locking is that the Lucene write lock may not be released when the JVM exits abnormally.

  When this happens, an `LockObtainFailedException` is hit when trying to create a writer, in which case you may need to explicitly clear the lock file first by manually removing the file. But, first be certain that no writer is in fact writing to the index otherwise you can easily corrupt your index.

  Special care needs to be taken if you change the locking implementation: First be certain that no writer is in fact writing to the index otherwise you can easily corrupt your index. Be sure to do the LockFactory change all Lucene instances and clean up all leftover lock files before starting the new configuration for the first time. Different implementations can not work together!

  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`.

  This is a singleton, you have to use `INSTANCE`.

  See Also:
    `LockFactory`

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static SimpleFSLockFactory` | `INSTANCE` Singleton instance

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected Lock` | `obtainFSLock(FSDirectory dir, String lockName)` Implement this method to obtain a lock for a FSDirectory instance.

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

      `getDefault, obtainLock`

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### INSTANCE

          public static final SimpleFSLockFactory INSTANCE

      Singleton instance

  - ### Method Detail

    - #### obtainFSLock

          protected Lock obtainFSLock(FSDirectory dir,
                                      String lockName)
                               throws IOException

      Description copied from class: `FSLockFactory`
      Implement this method to obtain a lock for a FSDirectory instance.
      Specified by:
        `obtainFSLock` in class `FSLockFactory`
      Throws:
        `IOException` - if the lock could not be obtained.

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