001 // Copyright 2006, 2007, 2010 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. 014 015 package org.apache.tapestry5.ioc.internal.services; 016 017 import java.lang.ref.WeakReference; 018 import java.util.Iterator; 019 import java.util.List; 020 021 import org.apache.tapestry5.ioc.annotations.PreventServiceDecoration; 022 import org.apache.tapestry5.ioc.internal.util.CollectionFactory; 023 import org.apache.tapestry5.services.UpdateListener; 024 import org.apache.tapestry5.services.UpdateListenerHub; 025 026 @PreventServiceDecoration 027 public class UpdateListenerHubImpl implements UpdateListenerHub 028 { 029 private final List<WeakReference<UpdateListener>> listeners = CollectionFactory.newThreadSafeList(); 030 031 public void addUpdateListener(UpdateListener listener) 032 { 033 assert listener != null; 034 listeners.add(new WeakReference<UpdateListener>(listener)); 035 } 036 037 /** 038 * Notifies all {@link UpdateListener}s. 039 */ 040 public void fireCheckForUpdates() 041 { 042 List<WeakReference<UpdateListener>> deadReferences = CollectionFactory.newList(); 043 044 Iterator<WeakReference<UpdateListener>> i = listeners.iterator(); 045 046 while (i.hasNext()) 047 { 048 WeakReference<UpdateListener> reference = i.next(); 049 050 UpdateListener listener = reference.get(); 051 052 if (listener == null) 053 deadReferences.add(reference); 054 else 055 listener.checkForUpdates(); 056 } 057 058 if (!deadReferences.isEmpty()) 059 listeners.removeAll(deadReferences); 060 } 061 }