1*cdf0e10cSrcweir /************************************************************************* 2*cdf0e10cSrcweir * 3*cdf0e10cSrcweir * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4*cdf0e10cSrcweir * 5*cdf0e10cSrcweir * Copyright 2000, 2010 Oracle and/or its affiliates. 6*cdf0e10cSrcweir * 7*cdf0e10cSrcweir * OpenOffice.org - a multi-platform office productivity suite 8*cdf0e10cSrcweir * 9*cdf0e10cSrcweir * This file is part of OpenOffice.org. 10*cdf0e10cSrcweir * 11*cdf0e10cSrcweir * OpenOffice.org is free software: you can redistribute it and/or modify 12*cdf0e10cSrcweir * it under the terms of the GNU Lesser General Public License version 3 13*cdf0e10cSrcweir * only, as published by the Free Software Foundation. 14*cdf0e10cSrcweir * 15*cdf0e10cSrcweir * OpenOffice.org is distributed in the hope that it will be useful, 16*cdf0e10cSrcweir * but WITHOUT ANY WARRANTY; without even the implied warranty of 17*cdf0e10cSrcweir * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18*cdf0e10cSrcweir * GNU Lesser General Public License version 3 for more details 19*cdf0e10cSrcweir * (a copy is included in the LICENSE file that accompanied this code). 20*cdf0e10cSrcweir * 21*cdf0e10cSrcweir * You should have received a copy of the GNU Lesser General Public License 22*cdf0e10cSrcweir * version 3 along with OpenOffice.org. If not, see 23*cdf0e10cSrcweir * <http://www.openoffice.org/license.html> 24*cdf0e10cSrcweir * for a copy of the LGPLv3 License. 25*cdf0e10cSrcweir * 26*cdf0e10cSrcweir ************************************************************************/ 27*cdf0e10cSrcweir 28*cdf0e10cSrcweir using System; 29*cdf0e10cSrcweir using unoidl.com.sun.star.uno; 30*cdf0e10cSrcweir using unoidl.com.sun.star.lang; 31*cdf0e10cSrcweir 32*cdf0e10cSrcweir namespace uno.util 33*cdf0e10cSrcweir { 34*cdf0e10cSrcweir 35*cdf0e10cSrcweir /** An XAdapter implementation that holds a weak reference 36*cdf0e10cSrcweir (System.WeakReference) to an object. 37*cdf0e10cSrcweir Clients can register listeners (unoidl.com.sun.star.lang.XReference) 38*cdf0e10cSrcweir which are notified when the object (the one which is kept weak) is 39*cdf0e10cSrcweir being finalized. That is, that object is being destroyed because there 40*cdf0e10cSrcweir are not any hard references to it. 41*cdf0e10cSrcweir */ 42*cdf0e10cSrcweir public class WeakAdapter : XAdapter 43*cdf0e10cSrcweir { 44*cdf0e10cSrcweir // references the XWeak implementation 45*cdf0e10cSrcweir private WeakReference m_weakRef; 46*cdf0e10cSrcweir // contains XReference objects registered by addReference 47*cdf0e10cSrcweir private delegate void XReference_dispose(); 48*cdf0e10cSrcweir private XReference_dispose m_XReference_dispose; 49*cdf0e10cSrcweir 50*cdf0e10cSrcweir /** ctor. 51*cdf0e10cSrcweir 52*cdf0e10cSrcweir @param obj the object that is to be held weakly 53*cdf0e10cSrcweir */ 54*cdf0e10cSrcweir public WeakAdapter( Object obj ) 55*cdf0e10cSrcweir { 56*cdf0e10cSrcweir m_weakRef = new WeakReference( obj ); 57*cdf0e10cSrcweir m_XReference_dispose = null; 58*cdf0e10cSrcweir } 59*cdf0e10cSrcweir 60*cdf0e10cSrcweir /** Called by the XWeak implementation (WeakBase) when it is being 61*cdf0e10cSrcweir finalized. It is only being called once. 62*cdf0e10cSrcweir The registererd XReference listeners are notified. On notification 63*cdf0e10cSrcweir they are to unregister themselves. The notification is thread-safe. 64*cdf0e10cSrcweir However, it is possible to add a listener during the notification 65*cdf0e10cSrcweir process, which will never receive a notification. 66*cdf0e10cSrcweir To prevent this, one would have to synchronize this method with 67*cdf0e10cSrcweir the addReference method. But this can result in deadlocks in a 68*cdf0e10cSrcweir multithreaded environment. 69*cdf0e10cSrcweir */ 70*cdf0e10cSrcweir internal /* non-virtual */ void referentDying() 71*cdf0e10cSrcweir { 72*cdf0e10cSrcweir XReference_dispose call; 73*cdf0e10cSrcweir lock (this) 74*cdf0e10cSrcweir { 75*cdf0e10cSrcweir call = m_XReference_dispose; 76*cdf0e10cSrcweir m_XReference_dispose = null; 77*cdf0e10cSrcweir } 78*cdf0e10cSrcweir if (null != call) 79*cdf0e10cSrcweir call(); 80*cdf0e10cSrcweir } 81*cdf0e10cSrcweir 82*cdf0e10cSrcweir // XAdapter impl 83*cdf0e10cSrcweir 84*cdf0e10cSrcweir /** Called to obtain a hard reference o the object which is kept weakly 85*cdf0e10cSrcweir by this instance. 86*cdf0e10cSrcweir 87*cdf0e10cSrcweir @return hard reference to the object 88*cdf0e10cSrcweir */ 89*cdf0e10cSrcweir public Object queryAdapted() 90*cdf0e10cSrcweir { 91*cdf0e10cSrcweir return m_weakRef.Target; 92*cdf0e10cSrcweir } 93*cdf0e10cSrcweir /** Called by clients to register listener which are notified when the 94*cdf0e10cSrcweir weak object is dying. 95*cdf0e10cSrcweir 96*cdf0e10cSrcweir @param xReference a listener 97*cdf0e10cSrcweir */ 98*cdf0e10cSrcweir public void removeReference( XReference xReference ) 99*cdf0e10cSrcweir { 100*cdf0e10cSrcweir lock (this) 101*cdf0e10cSrcweir { 102*cdf0e10cSrcweir m_XReference_dispose -= 103*cdf0e10cSrcweir new XReference_dispose( xReference.dispose ); 104*cdf0e10cSrcweir } 105*cdf0e10cSrcweir } 106*cdf0e10cSrcweir /** Called by clients to unregister listeners. 107*cdf0e10cSrcweir 108*cdf0e10cSrcweir @param xReference a listener 109*cdf0e10cSrcweir */ 110*cdf0e10cSrcweir public void addReference( XReference xReference ) 111*cdf0e10cSrcweir { 112*cdf0e10cSrcweir lock (this) 113*cdf0e10cSrcweir { 114*cdf0e10cSrcweir m_XReference_dispose += 115*cdf0e10cSrcweir new XReference_dispose( xReference.dispose ); 116*cdf0e10cSrcweir } 117*cdf0e10cSrcweir } 118*cdf0e10cSrcweir } 119*cdf0e10cSrcweir 120*cdf0e10cSrcweir } 121