1 /*
2 * Copyright (c) 2010, 2013, 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 java.awt;
27
28 import java.util.Timer;
29 import java.util.TimerTask;
30 import java.util.concurrent.atomic.AtomicBoolean;
31
32 import java.security.PrivilegedAction;
33 import java.security.AccessController;
34
35 import sun.awt.PeerEvent;
36
37 import sun.util.logging.PlatformLogger;
38
39 /**
40 * This utility class is used to suspend execution on a thread
41 * while still allowing {@code EventDispatchThread} to dispatch events.
42 * The API methods of the class are thread-safe.
43 *
44 * @author Anton Tarasov, Artem Ananiev
45 *
46 * @since 1.7
47 */
48 class WaitDispatchSupport implements SecondaryLoop {
49 private final static PlatformLogger log =
50 PlatformLogger.getLogger("java.awt.event.WaitDispatchSupport");
51
52 private EventDispatchThread dispatchThread;
53 private EventFilter filter;
54
55 private volatile Conditional extCondition;
56 private volatile Conditional condition;
57
58 private long interval;
59 // Use a shared daemon timer to serve all the WaitDispatchSupports
60 private static Timer timer;
61 // When this WDS expires, we cancel the timer task leaving the
62 // shared timer up and running
63 private TimerTask timerTask;
64
65 private AtomicBoolean keepBlockingEDT = new AtomicBoolean(false);
66 private AtomicBoolean keepBlockingCT = new AtomicBoolean(false);
67 private AtomicBoolean afterExit = new AtomicBoolean(false);
68
69 private static synchronized void initializeTimer() {
70 if (timer == null) {
71 timer = new Timer("AWT-WaitDispatchSupport-Timer", true);
72 }
73 }
74
75 /**
76 * Creates a {@code WaitDispatchSupport} instance to
77 * serve the given event dispatch thread.
78 *
79 * @param dispatchThread An event dispatch thread that
80 * should not stop dispatching events while waiting
81 *
82 * @since 1.7
83 */
84 public WaitDispatchSupport(EventDispatchThread dispatchThread) {
85 this(dispatchThread, null);
86 }
87
88 /**
89 * Creates a {@code WaitDispatchSupport} instance to
90 * serve the given event dispatch thread.
91 *
92 * @param dispatchThread An event dispatch thread that
93 * should not stop dispatching events while waiting
94 * @param extCond A conditional object used to determine
95 * if the loop should be terminated
96 *
97 * @since 1.7
98 */
99 public WaitDispatchSupport(EventDispatchThread dispatchThread,
100 Conditional extCond)
101 {
102 if (dispatchThread == null) {
103 throw new IllegalArgumentException("The dispatchThread can not be null");
104 }
105
106 this.dispatchThread = dispatchThread;
107 this.extCondition = extCond;
108 this.condition = new Conditional() {
109 @Override
110 public boolean evaluate() {
111 if (log.isLoggable(PlatformLogger.Level.FINEST)) {
112 log.finest("evaluate(): blockingEDT=" + keepBlockingEDT.get() +
113 ", blockingCT=" + keepBlockingCT.get());
114 }
115 boolean extEvaluate =
116 (extCondition != null) ? extCondition.evaluate() : true;
117 if (!keepBlockingEDT.get() || !extEvaluate || afterExit.get()) {
118 if (timerTask != null) {
119 timerTask.cancel();
120 timerTask = null;
121 }
122 return false;
123 }
124 return true;
125 }
126 };
127 }
128
129 /**
130 * Creates a {@code WaitDispatchSupport} instance to
131 * serve the given event dispatch thread.
132 * <p>
133 * The {@link EventFilter} is set on the {@code dispatchThread}
134 * while waiting. The filter is removed on completion of the
135 * waiting process.
136 * <p>
137 *
138 *
139 * @param dispatchThread An event dispatch thread that
140 * should not stop dispatching events while waiting
141 * @param filter {@code EventFilter} to be set
142 * @param interval A time interval to wait for. Note that
143 * when the waiting process takes place on EDT
144 * there is no guarantee to stop it in the given time
145 *
146 * @since 1.7
147 */
148 public WaitDispatchSupport(EventDispatchThread dispatchThread,
149 Conditional extCondition,
150 EventFilter filter, long interval)
151 {
152 this(dispatchThread, extCondition);
153 this.filter = filter;
154 if (interval < 0) {
155 throw new IllegalArgumentException("The interval value must be >= 0");
156 }
157 this.interval = interval;
158 if (interval != 0) {
159 initializeTimer();
160 }
161 }
162
163 /**
164 * {@inheritDoc}
165 */
166 @Override
167 public boolean enter() {
168 if (log.isLoggable(PlatformLogger.Level.FINE)) {
169 log.fine("enter(): blockingEDT=" + keepBlockingEDT.get() +
170 ", blockingCT=" + keepBlockingCT.get());
171 }
172
173 if (!keepBlockingEDT.compareAndSet(false, true)) {
174 log.fine("The secondary loop is already running, aborting");
175 return false;
176 }
177 try {
178 if (afterExit.get()) {
179 log.fine("Exit was called already, aborting");
180 return false;
181 }
182
183 final Runnable run = new Runnable() {
184 public void run() {
185 log.fine("Starting a new event pump");
186 if (filter == null) {
187 dispatchThread.pumpEvents(condition);
188 } else {
189 dispatchThread.pumpEventsForFilter(condition, filter);
190 }
191 }
192 };
193
194 // We have two mechanisms for blocking: if we're on the
195 // dispatch thread, start a new event pump; if we're
196 // on any other thread, call wait() on the treelock
197
198 Thread currentThread = Thread.currentThread();
199 if (currentThread == dispatchThread) {
200 if (log.isLoggable(PlatformLogger.Level.FINEST)) {
201 log.finest("On dispatch thread: " + dispatchThread);
202 }
203 if (interval != 0) {
204 if (log.isLoggable(PlatformLogger.Level.FINEST)) {
205 log.finest("scheduling the timer for " + interval + " ms");
206 }
207 timer.schedule(timerTask = new TimerTask() {
208 @Override
209 public void run() {
210 if (keepBlockingEDT.compareAndSet(true, false)) {
211 wakeupEDT();
212 }
213 }
214 }, interval);
215 }
216 // Dispose SequencedEvent we are dispatching on the current
217 // AppContext, to prevent us from hang - see 4531693 for details
218 SequencedEvent currentSE = KeyboardFocusManager.
219 getCurrentKeyboardFocusManager().getCurrentSequencedEvent();
220 if (currentSE != null) {
221 if (log.isLoggable(PlatformLogger.Level.FINE)) {
222 log.fine("Dispose current SequencedEvent: " + currentSE);
223 }
224 currentSE.dispose();
225 }
226 // In case the exit() method is called before starting
227 // new event pump it will post the waking event to EDT.
228 // The event will be handled after the new event pump
229 // starts. Thus, the enter() method will not hang.
230 //
231 // Event pump should be privileged. See 6300270.
232 AccessController.doPrivileged(new PrivilegedAction<Void>() {
233 public Void run() {
234 run.run();
235 return null;
236 }
237 });
238 } else {
239 if (log.isLoggable(PlatformLogger.Level.FINEST)) {
240 log.finest("On non-dispatch thread: " + currentThread);
241 }
242 keepBlockingCT.set(true);
243 synchronized (getTreeLock()) {
244 if (afterExit.get()) return false;
245 if (filter != null) {
246 dispatchThread.addEventFilter(filter);
247 }
248 try {
249 EventQueue eq = dispatchThread.getEventQueue();
250 eq.postEvent(new PeerEvent(this, run, PeerEvent.PRIORITY_EVENT));
251 if (interval > 0) {
252 long currTime = System.currentTimeMillis();
253 while (keepBlockingCT.get() &&
254 ((extCondition != null) ? extCondition.evaluate() : true) &&
255 (currTime + interval > System.currentTimeMillis()))
256 {
257 getTreeLock().wait(interval);
258 }
259 } else {
260 while (keepBlockingCT.get() &&
261 ((extCondition != null) ? extCondition.evaluate() : true))
262 {
263 getTreeLock().wait();
264 }
265 }
266 if (log.isLoggable(PlatformLogger.Level.FINE)) {
267 log.fine("waitDone " + keepBlockingEDT.get() + " " + keepBlockingCT.get());
268 }
269 } catch (InterruptedException e) {
270 if (log.isLoggable(PlatformLogger.Level.FINE)) {
271 log.fine("Exception caught while waiting: " + e);
272 }
273 } finally {
274 if (filter != null) {
275 dispatchThread.removeEventFilter(filter);
276 }
277 }
278 }
279 }
280 return true;
281 }
282 finally {
283 keepBlockingEDT.set(false);
284 keepBlockingCT.set(false);
285 afterExit.set(false);
286 }
287 }
288
289 /**
290 * {@inheritDoc}
291 */
292 public boolean exit() {
293 if (log.isLoggable(PlatformLogger.Level.FINE)) {
294 log.fine("exit(): blockingEDT=" + keepBlockingEDT.get() +
295 ", blockingCT=" + keepBlockingCT.get());
296 }
297 afterExit.set(true);
298 if (keepBlockingEDT.getAndSet(false)) {
299 wakeupEDT();
300 return true;
301 }
302 return false;
303 }
304
305 private final static Object getTreeLock() {
306 return Component.LOCK;
307 }
308
309 private final Runnable wakingRunnable = new Runnable() {
310 public void run() {
311 log.fine("Wake up EDT");
312 synchronized (getTreeLock()) {
313 keepBlockingCT.set(false);
314 getTreeLock().notifyAll();
315 }
316 log.fine("Wake up EDT done");
317 }
318 };
319
320 private void wakeupEDT() {
321 if (log.isLoggable(PlatformLogger.Level.FINEST)) {
322 log.finest("wakeupEDT(): EDT == " + dispatchThread);
323 }
324 EventQueue eq = dispatchThread.getEventQueue();
325 eq.postEvent(new PeerEvent(this, wakingRunnable, PeerEvent.PRIORITY_EVENT));
326 }
327 }