package org.apache.lucene.search;/** * 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;import java.util.BitSet;import org.apache.lucene.index.IndexReader;/** * Provides caching of {@link Filter}s themselves on the remote end of an RMI connection. * The cache is keyed on Filter's hashCode(), so if it sees the same filter twice * it will reuse the original version. * <p/> * NOTE: This does NOT cache the Filter bits, but rather the Filter itself. * Thus, this works hand-in-hand with {@link CachingWrapperFilter} to keep both * file Filter cache and the Filter bits on the remote end, close to the searcher. * <p/> * Usage: * <p/> * To cache a result you must do something like  * RemoteCachingWrapperFilter f = new RemoteCachingWrapperFilter(new CachingWrapperFilter(myFilter)); * <p/> */public class RemoteCachingWrapperFilter extends Filter {  protected Filter filter;  public RemoteCachingWrapperFilter(Filter filter) {    this.filter = filter;  }  /**   * Uses the {@link FilterManager} to keep the cache for a filter on the    * searcher side of a remote connection.   * @param reader the index reader for the Filter   * @return the bitset   * @deprecated Use {@link #getDocIdSet(IndexReader)} instead.   */  public BitSet bits(IndexReader reader) throws IOException {    Filter cachedFilter = FilterManager.getInstance().getFilter(filter);    return cachedFilter.bits(reader);  }    /**   * Uses the {@link FilterManager} to keep the cache for a filter on the    * searcher side of a remote connection.   * @param reader the index reader for the Filter   * @return the DocIdSet   */  public DocIdSet getDocIdSet(IndexReader reader) throws IOException {    Filter cachedFilter = FilterManager.getInstance().getFilter(filter);    return cachedFilter.getDocIdSet(reader);  }}