1 /*
2 * Copyright (c) 2002, 2015, 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 sun.awt.util.ThreadGroupUtils;
29 import sun.misc.ManagedLocalsThread;
30
31 import java.lang.ref.Reference;
32 import java.lang.ref.ReferenceQueue;
33 import java.lang.ref.PhantomReference;
34 import java.lang.ref.WeakReference;
35 import java.security.AccessController;
36 import java.security.PrivilegedAction;
37 import java.util.ArrayList;
38 import java.util.Hashtable;
39
40 /**
41 * This class is used for registering and disposing the native
42 * data associated with java objects.
43 *
44 * The object can register itself by calling one of the addRecord
45 * methods and providing either the pointer to the native disposal
46 * method or a descendant of the DisposerRecord class with overridden
47 * dispose() method.
48 *
49 * When the object becomes unreachable, the dispose() method
50 * of the associated DisposerRecord object will be called.
51 *
52 * @see DisposerRecord
53 */
54 public class Disposer implements Runnable {
55 private static final ReferenceQueue<Object> queue = new ReferenceQueue<>();
56 private static final Hashtable<java.lang.ref.Reference<Object>, DisposerRecord> records =
57 new Hashtable<>();
58
59 private static Disposer disposerInstance;
60 public static final int WEAK = 0;
61 public static final int PHANTOM = 1;
62 public static int refType = PHANTOM;
63
64 static {
65 java.security.AccessController.doPrivileged(
66 new java.security.PrivilegedAction<Void>() {
67 public Void run() {
68 System.loadLibrary("awt");
69 return null;
70 }
71 });
72 initIDs();
73 String type = java.security.AccessController.doPrivileged(
74 new sun.security.action.GetPropertyAction("sun.java2d.reftype"));
75 if (type != null) {
76 if (type.equals("weak")) {
77 refType = WEAK;
78 System.err.println("Using WEAK refs");
79 } else {
80 refType = PHANTOM;
81 System.err.println("Using PHANTOM refs");
82 }
83 }
84 disposerInstance = new Disposer();
85 AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
86 String name = "Java2D Disposer";
87 ThreadGroup rootTG = ThreadGroupUtils.getRootThreadGroup();
88 Thread t = new ManagedLocalsThread(rootTG, disposerInstance, name);
89 t.setContextClassLoader(null);
90 t.setDaemon(true);
91 t.setPriority(Thread.MAX_PRIORITY);
92 t.start();
93 return null;
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<Object> 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 = 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.");
154 }
155 }
156 }
157
158 /*
159 * This is a marker interface that, if implemented, means it
160 * doesn't acquire any special locks, and is safe to
161 * be disposed in the poll loop on whatever thread
162 * which happens to be the Toolkit thread, is in use.
163 */
164 public static interface PollDisposable {
165 };
166
167 private static ArrayList<DisposerRecord> deferredRecords = null;
168
169 private static void clearDeferredRecords() {
170 if (deferredRecords == null || deferredRecords.isEmpty()) {
171 return;
172 }
173 for (int i=0;i<deferredRecords.size(); i++) {
174 try {
175 DisposerRecord rec = deferredRecords.get(i);
176 rec.dispose();
177 } catch (Exception e) {
178 System.out.println("Exception while disposing deferred rec.");
179 }
180 }
181 deferredRecords.clear();
182 }
183
184 /*
185 * Set to indicate the queue is presently being polled.
186 */
187 public static volatile boolean pollingQueue = false;
188
189 /*
190 * The pollRemove() method is called back from a dispose method
191 * that is running on the toolkit thread and wants to
192 * dispose any pending refs that are safe to be disposed
193 * on that thread.
194 */
195 public static void pollRemove() {
196
197 /* This should never be called recursively, so this check
198 * is just a safeguard against the unexpected.
199 */
200 if (pollingQueue) {
201 return;
202 }
203 Object obj;
204 pollingQueue = true;
205 int freed = 0;
206 int deferred = 0;
207 try {
208 while ( freed < 10000 && deferred < 100 &&
209 (obj = queue.poll()) != null ) {
210 freed++;
211 ((Reference)obj).clear();
212 DisposerRecord rec = records.remove(obj);
213 if (rec instanceof PollDisposable) {
214 rec.dispose();
215 obj = null;
216 rec = null;
217 } else {
218 if (rec == null) { // shouldn't happen, but just in case.
219 continue;
220 }
221 deferred++;
222 if (deferredRecords == null) {
223 deferredRecords = new ArrayList<DisposerRecord>(5);
224 }
225 deferredRecords.add(rec);
226 }
227 }
228 } catch (Exception e) {
229 System.out.println("Exception while removing reference.");
230 } finally {
231 pollingQueue = false;
232 }
233 }
234
235 private static native void initIDs();
236
237 /*
238 * This was added for use by the 2D font implementation to avoid creation
239 * of an additional disposer thread.
240 * WARNING: this thread class monitors a specific queue, so a reference
241 * added here must have been created with this queue. Failure to do
242 * so will clutter the records hashmap and no one will be cleaning up
243 * the reference queue.
244 */
245 @SuppressWarnings("unchecked")
246 public static void addReference(Reference<Object> ref, DisposerRecord rec) {
247 records.put(ref, rec);
248 }
249
250 public static void addObjectRecord(Object obj, DisposerRecord rec) {
251 records.put(new WeakReference<>(obj, queue) , rec);
252 }
253
254 /* This is intended for use in conjunction with addReference(..)
255 */
256 public static ReferenceQueue<Object> getQueue() {
257 return queue;
258 }
259
260 }