| /* |
| * 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.index; |
| |
| import org.apache.lucene.index.MergePolicy.OneMerge; |
| import org.apache.lucene.store.Directory; |
| |
| /** |
| * A {@link MergeScheduler} which never executes any merges. It is also a |
| * singleton and can be accessed through {@link NoMergeScheduler#INSTANCE}. Use |
| * it if you want to prevent an {@link IndexWriter} from ever executing merges, |
| * regardless of the {@link MergePolicy} used. Note that you can achieve the |
| * same thing by using {@link NoMergePolicy}, however with |
| * {@link NoMergeScheduler} you also ensure that no unnecessary code of any |
| * {@link MergeScheduler} implementation is ever executed. Hence it is |
| * recommended to use both if you want to disable merges from ever happening. |
| */ |
| public final class NoMergeScheduler extends MergeScheduler { |
| |
| /** The single instance of {@link NoMergeScheduler} */ |
| public static final MergeScheduler INSTANCE = new NoMergeScheduler(); |
| |
| private NoMergeScheduler() { |
| // prevent instantiation |
| } |
| |
| @Override |
| public void close() {} |
| |
| @Override |
| public void merge(MergeSource mergeSource, MergeTrigger trigger) {} |
| |
| @Override |
| public Directory wrapForMerge(OneMerge merge, Directory in) { |
| return in; |
| } |
| |
| @Override |
| public MergeScheduler clone() { |
| return this; |
| } |
| } |