org.apache.lucene.store.LockFactory Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.store;
import java.io.IOException;
/**
* Base class for Locking implementation. {@link Directory} uses
* instances of this class to implement locking.
*
* Lucene uses {@link NativeFSLockFactory} by default for
* {@link FSDirectory}-based index directories.
*
* 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 on 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 some LockFactory implementation is
* not working properly in your environment, you can easily
* test it by using {@link VerifyingLockFactory}, {@link
* LockVerifyServer} and {@link LockStressTest}.
*
* @see LockVerifyServer
* @see LockStressTest
* @see VerifyingLockFactory
*/
public abstract class LockFactory {
/**
* Return a new obtained Lock instance identified by lockName.
* @param lockName name of the lock to be created.
* @throws LockObtainFailedException (optional specific exception) if the lock could
* not be obtained because it is currently held elsewhere.
* @throws IOException if any i/o error occurs attempting to gain the lock
*/
public abstract Lock obtainLock(Directory dir, String lockName) throws IOException;
}