1 /* 2 * Copyright (c) 1997, 2012, 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 27 28 package javax.swing; 29 30 31 32 import java.util.*; 33 import java.util.concurrent.*; 34 import java.util.concurrent.locks.*; 35 import java.util.concurrent.atomic.AtomicLong; 36 import sun.awt.AppContext; 37 38 39 40 /** 41 * Internal class to manage all Timers using one thread. 42 * TimerQueue manages a queue of Timers. The Timers are chained 43 * together in a linked list sorted by the order in which they will expire. 44 * 45 * @author Dave Moore 46 * @author Igor Kushnirskiy 47 */ 48 class TimerQueue implements Runnable 49 { 50 private static final Object sharedInstanceKey = 51 new StringBuffer("TimerQueue.sharedInstanceKey"); 52 private static final Object expiredTimersKey = 53 new StringBuffer("TimerQueue.expiredTimersKey"); 54 55 private final DelayQueue<DelayedTimer> queue; 56 private volatile boolean running; 57 private final Lock runningLock; 58 59 /* Lock object used in place of class object for synchronization. 60 * (4187686) 61 */ 62 private static final Object classLock = new Object(); 63 64 /** Base of nanosecond timings, to avoid wrapping */ 65 private static final long NANO_ORIGIN = System.nanoTime(); 66 67 /** 68 * Constructor for TimerQueue. 69 */ 70 public TimerQueue() { 71 super(); 72 queue = new DelayQueue<DelayedTimer>(); 73 // Now start the TimerQueue thread. 74 runningLock = new ReentrantLock(); 75 startIfNeeded(); 76 } 77 78 79 public static TimerQueue sharedInstance() { 80 synchronized (classLock) { 81 TimerQueue sharedInst = (TimerQueue) 82 SwingUtilities.appContextGet( 83 sharedInstanceKey); 84 if (sharedInst == null) { 85 sharedInst = new TimerQueue(); 86 SwingUtilities.appContextPut(sharedInstanceKey, sharedInst); 87 } 88 return sharedInst; 89 } 90 } 91 92 93 void startIfNeeded() { 94 if (! running) { 95 runningLock.lock(); 96 try { 97 final ThreadGroup threadGroup = 98 AppContext.getAppContext().getThreadGroup(); 99 java.security.AccessController.doPrivileged( 100 new java.security.PrivilegedAction<Object>() { 101 public Object run() { 102 Thread timerThread = new Thread(threadGroup, TimerQueue.this, 103 "TimerQueue"); 104 timerThread.setDaemon(true); 105 timerThread.setPriority(Thread.NORM_PRIORITY); 106 timerThread.start(); 107 return null; 108 } 109 }); 110 running = true; 111 } finally { 112 runningLock.unlock(); 113 } 114 } 115 } 116 117 void addTimer(Timer timer, long delayMillis) { 118 timer.getLock().lock(); 119 try { 120 // If the Timer is already in the queue, then ignore the add. 121 if (! containsTimer(timer)) { 122 addTimer(new DelayedTimer(timer, 123 TimeUnit.MILLISECONDS.toNanos(delayMillis) 124 + now())); 125 } 126 } finally { 127 timer.getLock().unlock(); 128 } 129 } 130 131 private void addTimer(DelayedTimer delayedTimer) { 132 assert delayedTimer != null && ! containsTimer(delayedTimer.getTimer()); 133 134 Timer timer = delayedTimer.getTimer(); 135 timer.getLock().lock(); 136 try { 137 timer.delayedTimer = delayedTimer; 138 queue.add(delayedTimer); 139 } finally { 140 timer.getLock().unlock(); 141 } 142 } 143 144 void removeTimer(Timer timer) { 145 timer.getLock().lock(); 146 try { 147 if (timer.delayedTimer != null) { 148 queue.remove(timer.delayedTimer); 149 timer.delayedTimer = null; 150 } 151 } finally { 152 timer.getLock().unlock(); 153 } 154 } 155 156 boolean containsTimer(Timer timer) { 157 timer.getLock().lock(); 158 try { 159 return timer.delayedTimer != null; 160 } finally { 161 timer.getLock().unlock(); 162 } 163 } 164 165 166 public void run() { 167 runningLock.lock(); 168 try { 169 while (running) { 170 try { 171 Timer timer = queue.take().getTimer(); 172 timer.getLock().lock(); 173 try { 174 DelayedTimer delayedTimer = timer.delayedTimer; 175 if (delayedTimer != null) { 176 /* 177 * Timer is not removed after we get it from 178 * the queue and before the lock on the timer is 179 * acquired 180 */ 181 timer.post(); // have timer post an event 182 timer.delayedTimer = null; 183 if (timer.isRepeats()) { 184 delayedTimer.setTime(now() 185 + TimeUnit.MILLISECONDS.toNanos( 186 timer.getDelay())); 187 addTimer(delayedTimer); 188 } 189 } 190 191 // Allow run other threads on systems without kernel threads 192 timer.getLock().newCondition().awaitNanos(1); 193 } catch (SecurityException ignore) { 194 } finally { 195 timer.getLock().unlock(); 196 } 197 } catch (InterruptedException ie) { 198 // Shouldn't ignore InterruptedExceptions here, so AppContext 199 // is disposed gracefully, see 6799345 for details 200 if (AppContext.getAppContext().isDisposed()) { 201 break; 202 } 203 } 204 } 205 } 206 catch (ThreadDeath td) { 207 // Mark all the timers we contain as not being queued. 208 for (DelayedTimer delayedTimer : queue) { 209 delayedTimer.getTimer().cancelEvent(); 210 } 211 throw td; 212 } finally { 213 running = false; 214 runningLock.unlock(); 215 } 216 } 217 218 219 public String toString() { 220 StringBuilder buf = new StringBuilder(); 221 buf.append("TimerQueue ("); 222 boolean isFirst = true; 223 for (DelayedTimer delayedTimer : queue) { 224 if (! isFirst) { 225 buf.append(", "); 226 } 227 buf.append(delayedTimer.getTimer().toString()); 228 isFirst = false; 229 } 230 buf.append(")"); 231 return buf.toString(); 232 } 233 234 /** 235 * Returns nanosecond time offset by origin 236 */ 237 private static long now() { 238 return System.nanoTime() - NANO_ORIGIN; 239 } 240 241 static class DelayedTimer implements Delayed { 242 // most of it copied from 243 // java.util.concurrent.ScheduledThreadPoolExecutor 244 245 /** 246 * Sequence number to break scheduling ties, and in turn to 247 * guarantee FIFO order among tied entries. 248 */ 249 private static final AtomicLong sequencer = new AtomicLong(0); 250 251 /** Sequence number to break ties FIFO */ 252 private final long sequenceNumber; 253 254 255 /** The time the task is enabled to execute in nanoTime units */ 256 private volatile long time; 257 258 private final Timer timer; 259 260 DelayedTimer(Timer timer, long nanos) { 261 this.timer = timer; 262 time = nanos; 263 sequenceNumber = sequencer.getAndIncrement(); 264 } 265 266 267 final public long getDelay(TimeUnit unit) { 268 return unit.convert(time - now(), TimeUnit.NANOSECONDS); 269 } 270 271 final void setTime(long nanos) { 272 time = nanos; 273 } 274 275 final Timer getTimer() { 276 return timer; 277 } 278 279 public int compareTo(Delayed other) { 280 if (other == this) { // compare zero ONLY if same object 281 return 0; 282 } 283 if (other instanceof DelayedTimer) { 284 DelayedTimer x = (DelayedTimer)other; 285 long diff = time - x.time; 286 if (diff < 0) { 287 return -1; 288 } else if (diff > 0) { 289 return 1; 290 } else if (sequenceNumber < x.sequenceNumber) { 291 return -1; 292 } else { 293 return 1; 294 } 295 } 296 long d = (getDelay(TimeUnit.NANOSECONDS) - 297 other.getDelay(TimeUnit.NANOSECONDS)); 298 return (d == 0) ? 0 : ((d < 0) ? -1 : 1); 299 } 300 } 301 }