/* * Copyright 2004 The Apache Software Foundation * * Licensed 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. */ using System; using System.Runtime.InteropServices; using IndexReader = Lucene.Net.Index.IndexReader; namespace Lucene.Net.Search { /// Wraps another filters result and caches it. The caching /// behavior is like {@link QueryFilter}. The purpose is to allow /// filters to simply filter, and then wrap with this class to add /// caching, keeping the two concerns decoupled yet composable. /// [Serializable] public class CachingWrapperFilter:Filter { private Filter filter; /// What about serialization in RemoteSearchable? Caching won't work. /// Should transient be removed? /// [NonSerialized] private System.Collections.IDictionary cache; /// Filter to cache results of /// public CachingWrapperFilter(Filter filter) { this.filter = filter; } public override System.Collections.BitArray Bits(IndexReader reader) { if (cache == null) { cache = new System.Collections.Hashtable(); } lock (cache.SyncRoot) { // check cache System.Collections.BitArray cached = (System.Collections.BitArray) cache[reader]; if (cached != null) { return cached; } } System.Collections.BitArray bits = filter.Bits(reader); lock (cache.SyncRoot) { // update cache cache[reader] = bits; } return bits; } public override System.String ToString() { return "CachingWrapperFilter(" + filter + ")"; } } }