001package org.apache.commons.jcs3.engine.memory.util; 002 003/* 004 * Licensed to the Apache Software Foundation (ASF) under one 005 * or more contributor license agreements. See the NOTICE file 006 * distributed with this work for additional information 007 * regarding copyright ownership. The ASF licenses this file 008 * to you under the Apache License, Version 2.0 (the 009 * "License"); you may not use this file except in compliance 010 * with the License. You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, 015 * software distributed under the License is distributed on an 016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 017 * KIND, either express or implied. See the License for the 018 * specific language governing permissions and limitations 019 * under the License. 020 */ 021 022import java.lang.ref.SoftReference; 023 024import org.apache.commons.jcs3.engine.behavior.ICacheElement; 025 026/** 027 * This wrapper is needed for double linked lists. 028 */ 029public class SoftReferenceElementDescriptor<K, V> 030 extends MemoryElementDescriptor<K, V> 031{ 032 /** Don't change */ 033 private static final long serialVersionUID = -1905161209035522460L; 034 035 /** The CacheElement wrapped by this descriptor */ 036 private transient final SoftReference<ICacheElement<K, V>> srce; 037 038 /** 039 * Constructs a usable MemoryElementDescriptor. 040 * <p> 041 * @param ce 042 */ 043 public SoftReferenceElementDescriptor( final ICacheElement<K, V> ce ) 044 { 045 super( null ); 046 this.srce = new SoftReference<>(ce); 047 } 048 049 /** 050 * @return the ce 051 */ 052 @Override 053 public ICacheElement<K, V> getCacheElement() 054 { 055 if (srce != null) 056 { 057 return srce.get(); 058 } 059 060 return null; 061 } 062}