1 /*
2 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package sun.java2d;
27
28 import java.lang.ref.Reference;
29 import java.lang.ref.ReferenceQueue;
30 import java.lang.ref.PhantomReference;
31 import java.lang.ref.WeakReference;
32 import java.util.ArrayList;
33 import java.util.Hashtable;
34
35 /**
36 * This class is used for registering and disposing the native
37 * data associated with java objects.
38 *
39 * The object can register itself by calling one of the addRecord
40 * methods and providing either the pointer to the native disposal
41 * method or a descendant of the DisposerRecord class with overridden
42 * dispose() method.
43 *
44 * When the object becomes unreachable, the dispose() method
45 * of the associated DisposerRecord object will be called.
46 *
47 * @see DisposerRecord
48 */
49 public class Disposer implements Runnable {
50 private static final ReferenceQueue queue = new ReferenceQueue();
51 private static final Hashtable records = new Hashtable();
52
53 private static Disposer disposerInstance;
54 public static final int WEAK = 0;
55 public static final int PHANTOM = 1;
56 public static int refType = PHANTOM;
57
58 static {
59 java.security.AccessController.doPrivileged(
60 new sun.security.action.LoadLibraryAction("awt"));
61 initIDs();
62 String type = (String) java.security.AccessController.doPrivileged(
63 new sun.security.action.GetPropertyAction("sun.java2d.reftype"));
64 if (type != null) {
65 if (type.equals("weak")) {
66 refType = WEAK;
67 System.err.println("Using WEAK refs");
68 } else {
69 refType = PHANTOM;
70 System.err.println("Using PHANTOM refs");
71 }
72 }
73 disposerInstance = new Disposer();
74 java.security.AccessController.doPrivileged(
75 new java.security.PrivilegedAction() {
76 public Object run() {
77 /* The thread must be a member of a thread group
78 * which will not get GCed before VM exit.
79 * Make its parent the top-level thread group.
80 */
81 ThreadGroup tg = Thread.currentThread().getThreadGroup();
82 for (ThreadGroup tgn = tg;
83 tgn != null;
84 tg = tgn, tgn = tg.getParent());
85 Thread t =
86 new Thread(tg, disposerInstance, "Java2D Disposer");
87 t.setContextClassLoader(null);
88 t.setDaemon(true);
89 t.setPriority(Thread.MAX_PRIORITY);
90 t.start();
91 return null;
92 }
93 }
94 );
95 }
96
97 /**
98 * Registers the object and the native data for later disposal.
99 * @param target Object to be registered
100 * @param disposeMethod pointer to the native disposal method
101 * @param pData pointer to the data to be passed to the
102 * native disposal method
103 */
104 public static void addRecord(Object target,
105 long disposeMethod, long pData)
106 {
107 disposerInstance.add(target,
108 new DefaultDisposerRecord(disposeMethod, pData));
109 }
110
111 /**
112 * Registers the object and the native data for later disposal.
113 * @param target Object to be registered
114 * @param rec the associated DisposerRecord object
115 * @see DisposerRecord
116 */
117 public static void addRecord(Object target, DisposerRecord rec) {
118 disposerInstance.add(target, rec);
119 }
120
121 /**
122 * Performs the actual registration of the target object to be disposed.
123 * @param target Object to be registered, or if target is an instance
124 * of DisposerTarget, its associated disposer referent
125 * will be the Object that is registered
126 * @param rec the associated DisposerRecord object
127 * @see DisposerRecord
128 */
129 synchronized void add(Object target, DisposerRecord rec) {
130 if (target instanceof DisposerTarget) {
131 target = ((DisposerTarget)target).getDisposerReferent();
132 }
133 java.lang.ref.Reference ref;
134 if (refType == PHANTOM) {
135 ref = new PhantomReference(target, queue);
136 } else {
137 ref = new WeakReference(target, queue);
138 }
139 records.put(ref, rec);
140 }
141
142 public void run() {
143 while (true) {
144 try {
145 Object obj = queue.remove();
146 ((Reference)obj).clear();
147 DisposerRecord rec = (DisposerRecord)records.remove(obj);
148 rec.dispose();
149 obj = null;
150 rec = null;
151 clearDeferredRecords();
152 } catch (Exception e) {
153 System.out.println("Exception while removing reference: " + e);
154 e.printStackTrace();
155 }
156 }
157 }
158
159 /*
160 * This is a marker interface that, if implemented, means it
161 * doesn't acquire any special locks, and is safe to
162 * be disposed in the poll loop on whatever thread
163 * which happens to be the Toolkit thread, is in use.
164 */
165 public static interface PollDisposable {
166 };
167
168 private static ArrayList<DisposerRecord> deferredRecords = null;
169
170 private static void clearDeferredRecords() {
171 if (deferredRecords == null || deferredRecords.isEmpty()) {
172 return;
173 }
174 for (int i=0;i<deferredRecords.size(); i++) {
175 try {
176 DisposerRecord rec = deferredRecords.get(i);
177 rec.dispose();
178 } catch (Exception e) {
179 System.out.println("Exception while disposing deferred rec.");
180 e.printStackTrace();
181 }
182 }
183 deferredRecords.clear();
184 }
185
186 /*
187 * Set to indicate the queue is presently being polled.
188 */
189 public static volatile boolean pollingQueue = false;
190
191 /*
192 * The pollRemove() method is called back from a dispose method
193 * that is running on the toolkit thread and wants to
194 * dispose any pending refs that are safe to be disposed
195 * on that thread.
196 */
197 public static void pollRemove() {
198
199 /* This should never be called recursively, so this check
200 * is just a safeguard against the unexpected.
201 */
202 if (pollingQueue) {
203 return;
204 }
205 Object obj;
206 pollingQueue = true;
207 int freed = 0;
208 int deferred = 0;
209 try {
210 while ((obj = queue.poll()) != null
211 && freed < 10000 && deferred < 100) {
212 freed++;
213 ((Reference)obj).clear();
214 DisposerRecord rec = (DisposerRecord)records.remove(obj);
215 if (rec instanceof PollDisposable) {
216 rec.dispose();
217 obj = null;
218 rec = null;
219 } else {
220 if (rec == null) { // shouldn't happen, but just in case.
221 continue;
222 }
223 deferred++;
224 if (deferredRecords == null) {
225 deferredRecords = new ArrayList<DisposerRecord>(5);
226 }
227 deferredRecords.add(rec);
228 }
229 }
230 } catch (Exception e) {
231 System.out.println("Exception while removing reference: " + e);
232 e.printStackTrace();
233 } finally {
234 pollingQueue = false;
235 }
236 }
237
238 private static native void initIDs();
239
240 /*
241 * This was added for use by the 2D font implementation to avoid creation
242 * of an additional disposer thread.
243 * WARNING: this thread class monitors a specific queue, so a reference
244 * added here must have been created with this queue. Failure to do
245 * so will clutter the records hashmap and no one will be cleaning up
246 * the reference queue.
247 */
248 public static void addReference(Reference ref, DisposerRecord rec) {
249 records.put(ref, rec);
250 }
251
252 public static void addObjectRecord(Object obj, DisposerRecord rec) {
253 records.put(new WeakReference(obj, queue) , rec);
254 }
255
256 /* This is intended for use in conjunction with addReference(..)
257 */
258 public static ReferenceQueue getQueue() {
259 return queue;
260 }
261
262 }