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.util.List;
  
  /**
   * This {@link IndexDeletionPolicy} implementation that
   * keeps only the most recent commit and immediately removes
   * all prior commits after a new commit is done.  This is
   * the default deletion policy.
   */
  
  public final class KeepOnlyLastCommitDeletionPolicy implements IndexDeletionPolicy {
  
    /**
     * Deletes all commits except the most recent one.
     */
    public void onInit(List<? extends IndexCommit> commits) {
      // Note that commits.size() should normally be 1:
      onCommit(commits);
    }
  
    /**
     * Deletes all commits except the most recent one.
     */
    public void onCommit(List<? extends IndexCommit> commits) {
      // Note that commits.size() should normally be 2 (if not
      // called by onInit above):
      int size = commits.size();
      for(int i=0;i<size-1;i++) {
        commits.get(i).delete();
      }
    }
  }
  