/*
 * 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 MergeScheduler which never executes any merges. It is also a singleton and can be accessed through INSTANCE. Use it if you want to prevent an IndexWriter from ever executing merges, regardless of the MergePolicy used. Note that you can achieve the same thing by using NoMergePolicy, however with NoMergeScheduler you also ensure that no unnecessary code of any MergeScheduler implementation is ever executed. Hence it is recommended to use both if you want to disable merges from ever happening. /**
 * 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 NoMergeScheduler /** 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, MergeTrigger trigger, boolean newMergesFound) {}
  
  @Override
  public Directory wrapForMerge(OneMerge merge, Directory in) {
    return in;
  }

  @Override
  public MergeScheduler clone() {
    return this;
  }
}