1 /* 2 * Copyright (c) 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 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 50 private final static PlatformLogger log = 51 PlatformLogger.getLogger("java.awt.event.WaitDispatchSupport"); 52 53 private EventDispatchThread dispatchThread; 54 private EventFilter filter; 55 56 private volatile Conditional extCondition; 57 private volatile Conditional condition; 58 59 private long interval; 60 // Use a shared daemon timer to serve all the WaitDispatchSupports 61 private static Timer timer; 62 // When this WDS expires, we cancel the timer task leaving the 63 // shared timer up and running 64 private TimerTask timerTask; 65 66 private AtomicBoolean keepBlockingEDT = new AtomicBoolean(false); 67 private AtomicBoolean keepBlockingCT = 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 extCondition 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.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) { 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 log.fine("enter(): blockingEDT=" + keepBlockingEDT.get() + 169 ", blockingCT=" + keepBlockingCT.get()); 170 171 if (!keepBlockingEDT.compareAndSet(false, true)) { 172 log.fine("The secondary loop is already running, aborting"); 173 return false; 174 } 175 176 final Runnable run = new Runnable() { 177 public void run() { 178 log.fine("Starting a new event pump"); 179 if (filter == null) { 180 dispatchThread.pumpEvents(condition); 181 } else { 182 dispatchThread.pumpEventsForFilter(condition, filter); 183 } 184 } 185 }; 186 187 // We have two mechanisms for blocking: if we're on the 188 // dispatch thread, start a new event pump; if we're 189 // on any other thread, call wait() on the treelock 190 191 Thread currentThread = Thread.currentThread(); 192 if (currentThread == dispatchThread) { 193 log.finest("On dispatch thread: " + dispatchThread); 194 if (interval != 0) { 195 log.finest("scheduling the timer for " + interval + " ms"); 196 timer.schedule(timerTask = new TimerTask() { 197 @Override 198 public void run() { 199 if (keepBlockingEDT.compareAndSet(true, false)) { 200 wakeupEDT(); 201 } 202 } 203 }, interval); 204 } 205 // Dispose SequencedEvent we are dispatching on the the current 206 // AppContext, to prevent us from hang - see 4531693 for details 207 SequencedEvent currentSE = KeyboardFocusManager. 208 getCurrentKeyboardFocusManager().getCurrentSequencedEvent(); 209 if (currentSE != null) { 210 log.fine("Dispose current SequencedEvent: " + currentSE); 211 currentSE.dispose(); 212 } 213 // In case the exit() method is called before starting 214 // new event pump it will post the waking event to EDT. 215 // The event will be handled after the the new event pump 216 // starts. Thus, the enter() method will not hang. 217 // 218 // Event pump should be privileged. See 6300270. 219 AccessController.doPrivileged(new PrivilegedAction() { 220 public Object run() { 221 run.run(); 222 return null; 223 } 224 }); 225 } else { 226 log.finest("On non-dispatch thread: " + currentThread); 227 synchronized (getTreeLock()) { 228 if (filter != null) { 229 dispatchThread.addEventFilter(filter); 230 } 231 try { 232 EventQueue eq = dispatchThread.getEventQueue(); 233 eq.postEvent(new PeerEvent(this, run, PeerEvent.PRIORITY_EVENT)); 234 keepBlockingCT.set(true); 235 if (interval > 0) { 236 long currTime = System.currentTimeMillis(); 237 while (keepBlockingCT.get() && 238 ((extCondition != null) ? extCondition.evaluate() : true) && 239 (currTime + interval > System.currentTimeMillis())) 240 { 241 getTreeLock().wait(interval); 242 } 243 } else { 244 while (keepBlockingCT.get() && 245 ((extCondition != null) ? extCondition.evaluate() : true)) 246 { 247 getTreeLock().wait(); 248 } 249 } 250 log.fine("waitDone " + keepBlockingEDT.get() + " " + keepBlockingCT.get()); 251 } catch (InterruptedException e) { 252 log.fine("Exception caught while waiting: " + e); 253 } finally { 254 if (filter != null) { 255 dispatchThread.removeEventFilter(filter); 256 } 257 } 258 // If the waiting process has been stopped because of the 259 // time interval passed or an exception occurred, the state 260 // should be changed 261 keepBlockingEDT.set(false); 262 keepBlockingCT.set(false); 263 } 264 } 265 266 return true; 267 } 268 269 /** 270 * @inheritDoc 271 */ 272 public boolean exit() { 273 log.fine("exit(): blockingEDT=" + keepBlockingEDT.get() + 274 ", blockingCT=" + keepBlockingCT.get()); 275 if (keepBlockingEDT.compareAndSet(true, false)) { 276 wakeupEDT(); 277 return true; 278 } 279 return false; 280 } 281 282 private final static Object getTreeLock() { 283 return Component.LOCK; 284 } 285 286 private final Runnable wakingRunnable = new Runnable() { 287 public void run() { 288 log.fine("Wake up EDT"); 289 synchronized (getTreeLock()) { 290 keepBlockingCT.set(false); 291 getTreeLock().notifyAll(); 292 } 293 log.fine("Wake up EDT done"); 294 } 295 }; 296 297 private void wakeupEDT() { 298 log.finest("wakeupEDT(): EDT == " + dispatchThread); 299 EventQueue eq = dispatchThread.getEventQueue(); 300 eq.postEvent(new PeerEvent(this, wakingRunnable, PeerEvent.PRIORITY_EVENT)); 301 } 302 }