001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 * 019 */ 020package org.apache.mina.filter.util; 021 022import org.apache.mina.core.filterchain.IoFilter; 023import org.apache.mina.core.filterchain.IoFilterAdapter; 024import org.apache.mina.core.filterchain.IoFilterChain; 025import org.apache.mina.core.session.IdleStatus; 026import org.apache.mina.core.session.IoSession; 027import org.apache.mina.core.write.WriteRequest; 028 029/** 030 * An {@link IoFilter}s wrapper that keeps track of the number of usages of this filter and will call init/destroy 031 * when the filter is not in use. 032 * 033 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 034 * @org.apache.xbean.XBean 035 */ 036public class ReferenceCountingFilter extends IoFilterAdapter { 037 private final IoFilter filter; 038 039 private int count = 0; 040 041 public ReferenceCountingFilter(IoFilter filter) { 042 this.filter = filter; 043 } 044 045 public void init() throws Exception { 046 // no-op, will init on-demand in pre-add if count == 0 047 } 048 049 public void destroy() throws Exception { 050 //no-op, will destroy on-demand in post-remove if count == 0 051 } 052 053 public synchronized void onPreAdd(IoFilterChain parent, String name, NextFilter nextFilter) throws Exception { 054 if (0 == count) { 055 filter.init(); 056 } 057 058 ++count; 059 060 filter.onPreAdd(parent, name, nextFilter); 061 } 062 063 public synchronized void onPostRemove(IoFilterChain parent, String name, NextFilter nextFilter) throws Exception { 064 filter.onPostRemove(parent, name, nextFilter); 065 066 --count; 067 068 if (0 == count) { 069 filter.destroy(); 070 } 071 } 072 073 public void exceptionCaught(NextFilter nextFilter, IoSession session, Throwable cause) throws Exception { 074 filter.exceptionCaught(nextFilter, session, cause); 075 } 076 077 public void filterClose(NextFilter nextFilter, IoSession session) throws Exception { 078 filter.filterClose(nextFilter, session); 079 } 080 081 public void filterWrite(NextFilter nextFilter, IoSession session, WriteRequest writeRequest) throws Exception { 082 filter.filterWrite(nextFilter, session, writeRequest); 083 } 084 085 public void messageReceived(NextFilter nextFilter, IoSession session, Object message) throws Exception { 086 filter.messageReceived(nextFilter, session, message); 087 } 088 089 public void messageSent(NextFilter nextFilter, IoSession session, WriteRequest writeRequest) throws Exception { 090 filter.messageSent(nextFilter, session, writeRequest); 091 } 092 093 public void onPostAdd(IoFilterChain parent, String name, NextFilter nextFilter) throws Exception { 094 filter.onPostAdd(parent, name, nextFilter); 095 } 096 097 public void onPreRemove(IoFilterChain parent, String name, NextFilter nextFilter) throws Exception { 098 filter.onPreRemove(parent, name, nextFilter); 099 } 100 101 public void sessionClosed(NextFilter nextFilter, IoSession session) throws Exception { 102 filter.sessionClosed(nextFilter, session); 103 } 104 105 public void sessionCreated(NextFilter nextFilter, IoSession session) throws Exception { 106 filter.sessionCreated(nextFilter, session); 107 } 108 109 public void sessionIdle(NextFilter nextFilter, IoSession session, IdleStatus status) throws Exception { 110 filter.sessionIdle(nextFilter, session, status); 111 } 112 113 public void sessionOpened(NextFilter nextFilter, IoSession session) throws Exception { 114 filter.sessionOpened(nextFilter, session); 115 } 116}