content: package org.apache.lucene.index;
  
  /**
   * 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.
   */
  
  import java.io.IOException;
  
  /**
   * 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,
   * irregardless 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(IndexWriter writer) throws CorruptIndexException, IOException {}
  }
  