1*cf279e26SAndrew Rist /************************************************************** 2cdf0e10cSrcweir * 3*cf279e26SAndrew Rist * Licensed to the Apache Software Foundation (ASF) under one 4*cf279e26SAndrew Rist * or more contributor license agreements. See the NOTICE file 5*cf279e26SAndrew Rist * distributed with this work for additional information 6*cf279e26SAndrew Rist * regarding copyright ownership. The ASF licenses this file 7*cf279e26SAndrew Rist * to you under the Apache License, Version 2.0 (the 8*cf279e26SAndrew Rist * "License"); you may not use this file except in compliance 9*cf279e26SAndrew Rist * with the License. You may obtain a copy of the License at 10*cf279e26SAndrew Rist * 11*cf279e26SAndrew Rist * http://www.apache.org/licenses/LICENSE-2.0 12*cf279e26SAndrew Rist * 13*cf279e26SAndrew Rist * Unless required by applicable law or agreed to in writing, 14*cf279e26SAndrew Rist * software distributed under the License is distributed on an 15*cf279e26SAndrew Rist * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 16*cf279e26SAndrew Rist * KIND, either express or implied. See the License for the 17*cf279e26SAndrew Rist * specific language governing permissions and limitations 18*cf279e26SAndrew Rist * under the License. 19*cf279e26SAndrew Rist * 20*cf279e26SAndrew Rist *************************************************************/ 21*cf279e26SAndrew Rist 22*cf279e26SAndrew Rist 23cdf0e10cSrcweir 24cdf0e10cSrcweir using System; 25cdf0e10cSrcweir using unoidl.com.sun.star.uno; 26cdf0e10cSrcweir using unoidl.com.sun.star.lang; 27cdf0e10cSrcweir 28cdf0e10cSrcweir namespace uno.util 29cdf0e10cSrcweir { 30cdf0e10cSrcweir 31cdf0e10cSrcweir /** An XAdapter implementation that holds a weak reference 32cdf0e10cSrcweir (System.WeakReference) to an object. 33cdf0e10cSrcweir Clients can register listeners (unoidl.com.sun.star.lang.XReference) 34cdf0e10cSrcweir which are notified when the object (the one which is kept weak) is 35cdf0e10cSrcweir being finalized. That is, that object is being destroyed because there 36cdf0e10cSrcweir are not any hard references to it. 37cdf0e10cSrcweir */ 38cdf0e10cSrcweir public class WeakAdapter : XAdapter 39cdf0e10cSrcweir { 40cdf0e10cSrcweir // references the XWeak implementation 41cdf0e10cSrcweir private WeakReference m_weakRef; 42cdf0e10cSrcweir // contains XReference objects registered by addReference XReference_dispose()43cdf0e10cSrcweir private delegate void XReference_dispose(); 44cdf0e10cSrcweir private XReference_dispose m_XReference_dispose; 45cdf0e10cSrcweir 46cdf0e10cSrcweir /** ctor. 47cdf0e10cSrcweir 48cdf0e10cSrcweir @param obj the object that is to be held weakly 49cdf0e10cSrcweir */ WeakAdapter( Object obj )50cdf0e10cSrcweir public WeakAdapter( Object obj ) 51cdf0e10cSrcweir { 52cdf0e10cSrcweir m_weakRef = new WeakReference( obj ); 53cdf0e10cSrcweir m_XReference_dispose = null; 54cdf0e10cSrcweir } 55cdf0e10cSrcweir 56cdf0e10cSrcweir /** Called by the XWeak implementation (WeakBase) when it is being 57cdf0e10cSrcweir finalized. It is only being called once. 58cdf0e10cSrcweir The registererd XReference listeners are notified. On notification 59cdf0e10cSrcweir they are to unregister themselves. The notification is thread-safe. 60cdf0e10cSrcweir However, it is possible to add a listener during the notification 61cdf0e10cSrcweir process, which will never receive a notification. 62cdf0e10cSrcweir To prevent this, one would have to synchronize this method with 63cdf0e10cSrcweir the addReference method. But this can result in deadlocks in a 64cdf0e10cSrcweir multithreaded environment. 65cdf0e10cSrcweir */ referentDying()66cdf0e10cSrcweir internal /* non-virtual */ void referentDying() 67cdf0e10cSrcweir { 68cdf0e10cSrcweir XReference_dispose call; 69cdf0e10cSrcweir lock (this) 70cdf0e10cSrcweir { 71cdf0e10cSrcweir call = m_XReference_dispose; 72cdf0e10cSrcweir m_XReference_dispose = null; 73cdf0e10cSrcweir } 74cdf0e10cSrcweir if (null != call) 75cdf0e10cSrcweir call(); 76cdf0e10cSrcweir } 77cdf0e10cSrcweir 78cdf0e10cSrcweir // XAdapter impl 79cdf0e10cSrcweir 80cdf0e10cSrcweir /** Called to obtain a hard reference o the object which is kept weakly 81cdf0e10cSrcweir by this instance. 82cdf0e10cSrcweir 83cdf0e10cSrcweir @return hard reference to the object 84cdf0e10cSrcweir */ queryAdapted()85cdf0e10cSrcweir public Object queryAdapted() 86cdf0e10cSrcweir { 87cdf0e10cSrcweir return m_weakRef.Target; 88cdf0e10cSrcweir } 89cdf0e10cSrcweir /** Called by clients to register listener which are notified when the 90cdf0e10cSrcweir weak object is dying. 91cdf0e10cSrcweir 92cdf0e10cSrcweir @param xReference a listener 93cdf0e10cSrcweir */ removeReference( XReference xReference )94cdf0e10cSrcweir public void removeReference( XReference xReference ) 95cdf0e10cSrcweir { 96cdf0e10cSrcweir lock (this) 97cdf0e10cSrcweir { 98cdf0e10cSrcweir m_XReference_dispose -= 99cdf0e10cSrcweir new XReference_dispose( xReference.dispose ); 100cdf0e10cSrcweir } 101cdf0e10cSrcweir } 102cdf0e10cSrcweir /** Called by clients to unregister listeners. 103cdf0e10cSrcweir 104cdf0e10cSrcweir @param xReference a listener 105cdf0e10cSrcweir */ addReference( XReference xReference )106cdf0e10cSrcweir public void addReference( XReference xReference ) 107cdf0e10cSrcweir { 108cdf0e10cSrcweir lock (this) 109cdf0e10cSrcweir { 110cdf0e10cSrcweir m_XReference_dispose += 111cdf0e10cSrcweir new XReference_dispose( xReference.dispose ); 112cdf0e10cSrcweir } 113cdf0e10cSrcweir } 114cdf0e10cSrcweir } 115cdf0e10cSrcweir 116cdf0e10cSrcweir } 117