Java tutorial
/* * 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; /** * <p>Base class for Locking implementation. {@link Directory} uses * instances of this class to implement locking.</p> * * <p>Lucene uses {@link NativeFSLockFactory} by default for * {@link FSDirectory}-based index directories.</p> * * <p>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!</p> * * <p>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}.</p> * * @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; }