1*b1cdbd2cSJim Jagielski /************************************************************** 2*b1cdbd2cSJim Jagielski * 3*b1cdbd2cSJim Jagielski * Licensed to the Apache Software Foundation (ASF) under one 4*b1cdbd2cSJim Jagielski * or more contributor license agreements. See the NOTICE file 5*b1cdbd2cSJim Jagielski * distributed with this work for additional information 6*b1cdbd2cSJim Jagielski * regarding copyright ownership. The ASF licenses this file 7*b1cdbd2cSJim Jagielski * to you under the Apache License, Version 2.0 (the 8*b1cdbd2cSJim Jagielski * "License"); you may not use this file except in compliance 9*b1cdbd2cSJim Jagielski * with the License. You may obtain a copy of the License at 10*b1cdbd2cSJim Jagielski * 11*b1cdbd2cSJim Jagielski * http://www.apache.org/licenses/LICENSE-2.0 12*b1cdbd2cSJim Jagielski * 13*b1cdbd2cSJim Jagielski * Unless required by applicable law or agreed to in writing, 14*b1cdbd2cSJim Jagielski * software distributed under the License is distributed on an 15*b1cdbd2cSJim Jagielski * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 16*b1cdbd2cSJim Jagielski * KIND, either express or implied. See the License for the 17*b1cdbd2cSJim Jagielski * specific language governing permissions and limitations 18*b1cdbd2cSJim Jagielski * under the License. 19*b1cdbd2cSJim Jagielski * 20*b1cdbd2cSJim Jagielski *************************************************************/ 21*b1cdbd2cSJim Jagielski 22*b1cdbd2cSJim Jagielski 23*b1cdbd2cSJim Jagielski 24*b1cdbd2cSJim Jagielski using System; 25*b1cdbd2cSJim Jagielski using unoidl.com.sun.star.uno; 26*b1cdbd2cSJim Jagielski using unoidl.com.sun.star.lang; 27*b1cdbd2cSJim Jagielski 28*b1cdbd2cSJim Jagielski namespace uno.util 29*b1cdbd2cSJim Jagielski { 30*b1cdbd2cSJim Jagielski 31*b1cdbd2cSJim Jagielski /** An XAdapter implementation that holds a weak reference 32*b1cdbd2cSJim Jagielski (System.WeakReference) to an object. 33*b1cdbd2cSJim Jagielski Clients can register listeners (unoidl.com.sun.star.lang.XReference) 34*b1cdbd2cSJim Jagielski which are notified when the object (the one which is kept weak) is 35*b1cdbd2cSJim Jagielski being finalized. That is, that object is being destroyed because there 36*b1cdbd2cSJim Jagielski are not any hard references to it. 37*b1cdbd2cSJim Jagielski */ 38*b1cdbd2cSJim Jagielski public class WeakAdapter : XAdapter 39*b1cdbd2cSJim Jagielski { 40*b1cdbd2cSJim Jagielski // references the XWeak implementation 41*b1cdbd2cSJim Jagielski private WeakReference m_weakRef; 42*b1cdbd2cSJim Jagielski // contains XReference objects registered by addReference XReference_dispose()43*b1cdbd2cSJim Jagielski private delegate void XReference_dispose(); 44*b1cdbd2cSJim Jagielski private XReference_dispose m_XReference_dispose; 45*b1cdbd2cSJim Jagielski 46*b1cdbd2cSJim Jagielski /** ctor. 47*b1cdbd2cSJim Jagielski 48*b1cdbd2cSJim Jagielski @param obj the object that is to be held weakly 49*b1cdbd2cSJim Jagielski */ WeakAdapter( Object obj )50*b1cdbd2cSJim Jagielski public WeakAdapter( Object obj ) 51*b1cdbd2cSJim Jagielski { 52*b1cdbd2cSJim Jagielski m_weakRef = new WeakReference( obj ); 53*b1cdbd2cSJim Jagielski m_XReference_dispose = null; 54*b1cdbd2cSJim Jagielski } 55*b1cdbd2cSJim Jagielski 56*b1cdbd2cSJim Jagielski /** Called by the XWeak implementation (WeakBase) when it is being 57*b1cdbd2cSJim Jagielski finalized. It is only being called once. 58*b1cdbd2cSJim Jagielski The registererd XReference listeners are notified. On notification 59*b1cdbd2cSJim Jagielski they are to unregister themselves. The notification is thread-safe. 60*b1cdbd2cSJim Jagielski However, it is possible to add a listener during the notification 61*b1cdbd2cSJim Jagielski process, which will never receive a notification. 62*b1cdbd2cSJim Jagielski To prevent this, one would have to synchronize this method with 63*b1cdbd2cSJim Jagielski the addReference method. But this can result in deadlocks in a 64*b1cdbd2cSJim Jagielski multithreaded environment. 65*b1cdbd2cSJim Jagielski */ referentDying()66*b1cdbd2cSJim Jagielski internal /* non-virtual */ void referentDying() 67*b1cdbd2cSJim Jagielski { 68*b1cdbd2cSJim Jagielski XReference_dispose call; 69*b1cdbd2cSJim Jagielski lock (this) 70*b1cdbd2cSJim Jagielski { 71*b1cdbd2cSJim Jagielski call = m_XReference_dispose; 72*b1cdbd2cSJim Jagielski m_XReference_dispose = null; 73*b1cdbd2cSJim Jagielski } 74*b1cdbd2cSJim Jagielski if (null != call) 75*b1cdbd2cSJim Jagielski call(); 76*b1cdbd2cSJim Jagielski } 77*b1cdbd2cSJim Jagielski 78*b1cdbd2cSJim Jagielski // XAdapter impl 79*b1cdbd2cSJim Jagielski 80*b1cdbd2cSJim Jagielski /** Called to obtain a hard reference o the object which is kept weakly 81*b1cdbd2cSJim Jagielski by this instance. 82*b1cdbd2cSJim Jagielski 83*b1cdbd2cSJim Jagielski @return hard reference to the object 84*b1cdbd2cSJim Jagielski */ queryAdapted()85*b1cdbd2cSJim Jagielski public Object queryAdapted() 86*b1cdbd2cSJim Jagielski { 87*b1cdbd2cSJim Jagielski return m_weakRef.Target; 88*b1cdbd2cSJim Jagielski } 89*b1cdbd2cSJim Jagielski /** Called by clients to register listener which are notified when the 90*b1cdbd2cSJim Jagielski weak object is dying. 91*b1cdbd2cSJim Jagielski 92*b1cdbd2cSJim Jagielski @param xReference a listener 93*b1cdbd2cSJim Jagielski */ removeReference( XReference xReference )94*b1cdbd2cSJim Jagielski public void removeReference( XReference xReference ) 95*b1cdbd2cSJim Jagielski { 96*b1cdbd2cSJim Jagielski lock (this) 97*b1cdbd2cSJim Jagielski { 98*b1cdbd2cSJim Jagielski m_XReference_dispose -= 99*b1cdbd2cSJim Jagielski new XReference_dispose( xReference.dispose ); 100*b1cdbd2cSJim Jagielski } 101*b1cdbd2cSJim Jagielski } 102*b1cdbd2cSJim Jagielski /** Called by clients to unregister listeners. 103*b1cdbd2cSJim Jagielski 104*b1cdbd2cSJim Jagielski @param xReference a listener 105*b1cdbd2cSJim Jagielski */ addReference( XReference xReference )106*b1cdbd2cSJim Jagielski public void addReference( XReference xReference ) 107*b1cdbd2cSJim Jagielski { 108*b1cdbd2cSJim Jagielski lock (this) 109*b1cdbd2cSJim Jagielski { 110*b1cdbd2cSJim Jagielski m_XReference_dispose += 111*b1cdbd2cSJim Jagielski new XReference_dispose( xReference.dispose ); 112*b1cdbd2cSJim Jagielski } 113*b1cdbd2cSJim Jagielski } 114*b1cdbd2cSJim Jagielski } 115*b1cdbd2cSJim Jagielski 116*b1cdbd2cSJim Jagielski } 117