001// Copyright 2004, 2005 The Apache Software Foundation 002// 003// Licensed under the Apache License, Version 2.0 (the "License"); 004// you may not use this file except in compliance with the License. 005// You may obtain a copy of the License at 006// 007// http://www.apache.org/licenses/LICENSE-2.0 008// 009// Unless required by applicable law or agreed to in writing, software 010// distributed under the License is distributed on an "AS IS" BASIS, 011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012// See the License for the specific language governing permissions and 013// limitations under the License. 014 015package org.apache.hivemind.impl; 016 017import java.util.HashSet; 018import java.util.Iterator; 019import java.util.Set; 020 021import org.apache.commons.logging.Log; 022import org.apache.commons.logging.LogFactory; 023import org.apache.hivemind.ShutdownCoordinator; 024import org.apache.hivemind.events.RegistryShutdownListener; 025import org.apache.hivemind.util.EventListenerList; 026 027/** 028 * Manages a list of objects that implement the 029 * {@link org.apache.hivemind.events.RegistryShutdownListener} interface. 030 * 031 * @author Howard Lewis Ship 032 */ 033public final class ShutdownCoordinatorImpl implements ShutdownCoordinator 034{ 035 private final Log _log; 036 037 private Set alreadyShutdown; 038 039 public ShutdownCoordinatorImpl() 040 { 041 this(LogFactory.getLog(ShutdownCoordinatorImpl.class)); 042 } 043 044 public ShutdownCoordinatorImpl(Log log) 045 { 046 _log = log; 047 } 048 049 private EventListenerList _listenerList; 050 051 public synchronized void addRegistryShutdownListener( 052 RegistryShutdownListener s) 053 { 054 if (_listenerList == null) 055 _listenerList = new EventListenerList(); 056 057 _listenerList.addListener(s); 058 } 059 060 public synchronized void removeRegistryShutdownListener( 061 RegistryShutdownListener s) 062 { 063 if (_listenerList != null) 064 _listenerList.removeListener(s); 065 } 066 067 public void shutdown() 068 { 069 if (_listenerList == null) 070 return; 071 072 Iterator i = _listenerList.getListeners(); 073 074 _listenerList = null; 075 076 while (i.hasNext()) 077 { 078 RegistryShutdownListener s = (RegistryShutdownListener) i.next(); 079 080 shutdown(s); 081 } 082 083 _listenerList = null; 084 } 085 086 private void shutdown(RegistryShutdownListener s) 087 { 088 if (alreadyShutdown == null) 089 { 090 alreadyShutdown = new HashSet(); 091 } 092 final Long id = new Long(System.identityHashCode(s)); 093 if (!alreadyShutdown.contains(id)) 094 { 095 try 096 { 097 s.registryDidShutdown(); 098 } 099 catch (RuntimeException ex) 100 { 101 _log.error(ImplMessages.shutdownCoordinatorFailure(s, ex), ex); 102 } 103 finally 104 { 105 alreadyShutdown.add(id); 106 } 107 } 108 } 109 110}