001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.activemq.memory;
018
019public class CacheEntry {
020
021    public final Object key;
022    public final Object value;
023
024    public CacheEntry next;
025    public CacheEntry previous;
026    public CacheEntryList owner;
027
028    public CacheEntry(Object key, Object value) {
029        this.key = key;
030        this.value = value;
031    }
032
033    /**
034     * @return false if you are trying to remove the tail pointer.
035     */
036    public boolean remove() {
037
038        // Cannot remove if this is a tail pointer.
039        // Or not linked.
040        if (owner == null || this.key == null || this.next == null) {
041            return false;
042        }
043
044        synchronized (owner.tail) {
045            this.next.previous = this.previous;
046            this.previous.next = this.next;
047            this.owner = null;
048            this.next = null;
049            this.previous = null;
050        }
051
052        return true;
053    }
054}