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 */ 017 package org.apache.activemq.memory; 018 019 /** 020 * Defines the interface used to cache messages. 021 * 022 * 023 */ 024 public interface Cache { 025 026 /** 027 * Gets an object that was previously <code>put</code> into this object. 028 * 029 * @param msgid 030 * @return null if the object was not previously put or if the object has 031 * expired out of the cache. 032 */ 033 Object get(Object key); 034 035 /** 036 * Puts an object into the cache. 037 * 038 * @param messageID 039 * @param message 040 */ 041 Object put(Object key, Object value); 042 043 /** 044 * Removes an object from the cache. 045 * 046 * @param messageID 047 * @return the object associated with the key if it was still in the cache. 048 */ 049 Object remove(Object key); 050 051 /** 052 * Lets a cache know it will not be used any further and that it can release 053 * acquired resources 054 */ 055 void close(); 056 057 /** 058 * How big is the cache right now? 059 * 060 * @return 061 */ 062 int size(); 063 064 }