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annotate org.eclipse.core.databinding/src/org/eclipse/core/databinding/observable/Realm.d @ 125:c43718956f21 default tip
Updated the snippets status.
| author | Jacob Carlborg <doob@me.com> |
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| date | Thu, 11 Aug 2011 19:55:14 +0200 |
| parents | 5d5bd660917f |
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| rev | line source |
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| 78 | 1 /******************************************************************************* |
| 2 * Copyright (c) 2006, 2007 IBM Corporation and others. | |
| 3 * All rights reserved. This program and the accompanying materials | |
| 4 * are made available under the terms of the Eclipse Public License v1.0 | |
| 5 * which accompanies this distribution, and is available at | |
| 6 * http://www.eclipse.org/legal/epl-v10.html | |
| 7 * | |
| 8 * Contributors: | |
| 9 * IBM Corporation - initial API and implementation | |
| 10 * Brad Reynolds - bug 168153 | |
| 11 *******************************************************************************/ | |
| 12 | |
| 13 module org.eclipse.core.databinding.observable.Realm; | |
| 14 | |
| 15 import java.lang.all; | |
| 16 | |
| 17 import org.eclipse.core.databinding.Binding; | |
| 18 import org.eclipse.core.databinding.util.Policy; | |
| 19 import org.eclipse.core.internal.databinding.Queue; | |
| 20 import org.eclipse.core.runtime.ISafeRunnable; | |
| 21 import org.eclipse.core.runtime.IStatus; | |
| 22 import org.eclipse.core.runtime.SafeRunner; | |
| 23 import org.eclipse.core.runtime.Status; | |
| 24 | |
| 25 /** | |
| 26 * A realm defines a context from which objects implementing {@link IObservable} | |
| 27 * must be accessed, and on which these objects will notify their listeners. To | |
| 28 * bridge between observables from different realms, subclasses of | |
| 29 * {@link Binding} can be used. | |
| 30 * <p> | |
| 31 * A block of code is said to be executing within a realm if calling | |
| 32 * {@link #isCurrent()} from that block returns true. Code reached by calling | |
| 33 * methods from that block will execute within the same realm, with the | |
| 34 * exception of methods on this class that can be used to execute code within a | |
| 35 * specific realm. Clients can use {@link #syncExeccast(Runnable)}, | |
| 36 * {@link #asyncExeccast(Runnable)}, or {@link #execcast(Runnable)} to execute a | |
| 37 * runnable within this realm. Note that using {@link #syncExeccast(Runnable)} can | |
| 38 * lead to deadlocks and should be avoided if the current thread holds any | |
| 39 * locks. | |
| 40 * </p> | |
| 41 * <p> | |
| 42 * It is instructive to think about possible implementations of Realm: It can be | |
| 43 * based on executing on a designated thread such as a UI thread, or based on | |
| 44 * holding a lock. In the former case, calling syncExec on a realm that is not | |
| 45 * the current realm will execute the given runnable on a different thread (the | |
| 46 * designated thread). In the latter case, calling syncExec may execute the | |
| 47 * given runnable on the calling thread, but calling | |
| 48 * {@link #asyncExeccast(Runnable)} will execute the given runnable on a different | |
| 49 * thread. Therefore, no assumptions can be made about the thread that will | |
| 50 * execute arguments to {@link #asyncExeccast(Runnable)}, | |
| 51 * {@link #syncExeccast(Runnable)}, or {@link #execcast(Runnable)}. | |
| 52 * </p> | |
| 53 * <p> | |
| 54 * It is possible that a block of code is executing within more than one realm. | |
| 55 * This can happen for implementations of Realm that are based on holding a lock | |
| 56 * but don't use a separate thread to run runnables given to | |
| 57 * {@link #syncExeccast(Runnable)}. Realm implementations of this kind should be | |
| 58 * appropriately documented because it increases the opportunity for deadlock. | |
| 59 * </p> | |
| 60 * <p> | |
| 61 * Some implementations of {@link IObservable} provide constructors which do not | |
| 62 * take a Realm argument and are specified to create the observable instance | |
| 63 * with the current default realm. The default realm can be set for the | |
| 64 * currently executing thread by using {@link #runWithDefault(Realm, Runnable)}. | |
| 65 * Note that the default realm does not have to be the current realm. | |
| 66 * </p> | |
| 67 * <p> | |
| 68 * Subclasses must override at least one of asyncExec()/syncExec(). For realms | |
| 69 * based on a designated thread, it may be easier to implement asyncExec and | |
| 70 * keep the default implementation of syncExec. For realms based on holding a | |
| 71 * lock, it may be easier to implement syncExec and keep the default | |
| 72 * implementation of asyncExec. | |
| 73 * </p> | |
| 74 * | |
| 75 * @since 1.0 | |
| 76 * | |
| 77 * @see IObservable | |
| 78 */ | |
| 79 public abstract class Realm { | |
| 80 | |
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81 private static ThreadLocal defaultRealm_; |
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82 private static ThreadLocal defaultRealm(){ |
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83 if( defaultRealm_ is null ){ |
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84 synchronized{ |
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85 if( defaultRealm_ is null ){ |
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86 defaultRealm_ = new ThreadLocal(); |
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87 } |
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88 } |
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89 } |
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90 return defaultRealm_; |
| 85 | 91 } |
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92 |
| 85 | 93 this(){ |
| 94 workQueue = new Queue(); | |
| 95 } | |
| 78 | 96 |
| 97 /** | |
| 98 * Returns the default realm for the calling thread, or <code>null</code> | |
| 99 * if no default realm has been set. | |
| 100 * | |
| 101 * @return the default realm, or <code>null</code> | |
| 102 */ | |
| 103 public static Realm getDefault() { | |
| 104 return cast(Realm) defaultRealm.get(); | |
| 105 } | |
| 106 | |
| 107 /** | |
| 108 * Sets the default realm for the calling thread, returning the current | |
| 109 * default thread. This method is inherently unsafe, it is recommended to | |
| 110 * use {@link #runWithDefault(Realm, Runnable)} instead. This method is | |
| 111 * exposed to subclasses to facilitate testing. | |
| 112 * | |
| 113 * @param realm | |
| 114 * the new default realm, or <code>null</code> | |
| 115 * @return the previous default realm, or <code>null</code> | |
| 116 */ | |
| 117 protected static Realm setDefault(Realm realm) { | |
| 118 Realm oldValue = getDefault(); | |
| 119 defaultRealm.set(realm); | |
| 120 return oldValue; | |
| 121 } | |
| 122 | |
| 123 /** | |
| 124 * @return true if the caller is executing in this realm. This method must | |
| 125 * not have side-effects (such as, for example, implicitly placing | |
| 126 * the caller in this realm). | |
| 127 */ | |
| 128 abstract public bool isCurrent(); | |
| 129 | |
| 130 private Thread workerThread; | |
| 131 | |
| 85 | 132 Queue workQueue; |
| 78 | 133 |
| 134 /** | |
| 135 * Runs the given runnable. If an exception occurs within the runnable, it | |
| 136 * is logged and not re-thrown. If the runnable implements | |
| 137 * {@link ISafeRunnable}, the exception is passed to its | |
| 138 * <code>handleException<code> method. | |
| 139 * | |
| 140 * @param runnable | |
| 141 */ | |
| 142 protected static void safeRun(Runnable runnable) { | |
| 143 ISafeRunnable safeRunnable; | |
| 144 if ( null !is cast(ISafeRunnable)runnable ) { | |
| 145 safeRunnable = cast(ISafeRunnable) runnable; | |
| 146 } else { | |
| 147 safeRunnable = new class(runnable) ISafeRunnable { | |
| 148 Runnable runnable_; | |
| 149 this(Runnable r){runnable_=r;} | |
| 150 public void handleException(Throwable exception) { | |
| 151 Policy | |
| 152 .getLog() | |
| 153 .log( | |
| 154 new Status( | |
| 155 IStatus.ERROR, | |
| 156 Policy.JFACE_DATABINDING, | |
| 157 IStatus.OK, | |
| 85 | 158 "Unhandled exception: " ~ exception.msg, exception)); //$NON-NLS-1$ |
| 78 | 159 } |
| 160 public void run() { | |
| 161 runnable_.run(); | |
| 162 } | |
| 163 }; | |
| 164 } | |
| 165 SafeRunner.run(safeRunnable); | |
| 166 } | |
| 167 | |
| 168 /** | |
| 169 * Causes the <code>run()</code> method of the runnable to be invoked from | |
| 170 * within this realm. If the caller is executing in this realm, the | |
| 171 * runnable's run method is invoked directly, otherwise it is run at the | |
| 172 * next reasonable opportunity using asyncExec. | |
| 173 * <p> | |
| 174 * If the given runnable is an instance of {@link ISafeRunnable}, its | |
| 175 * exception handler method will be called if any exceptions occur while | |
| 176 * running it. Otherwise, the exception will be logged. | |
| 177 * </p> | |
| 178 * | |
| 179 * @param runnable | |
| 180 */ | |
| 181 public void exec(Runnable runnable) { | |
| 182 if (isCurrent()) { | |
| 183 safeRun(runnable); | |
| 184 } else { | |
| 185 asyncExec(runnable); | |
| 186 } | |
| 187 } | |
| 188 | |
| 189 /** | |
| 190 * Causes the <code>run()</code> method of the runnable to be invoked from | |
| 191 * within this realm at the next reasonable opportunity. The caller of this | |
| 192 * method continues to run in parallel, and is not notified when the | |
| 193 * runnable has completed. | |
| 194 * <p> | |
| 195 * If the given runnable is an instance of {@link ISafeRunnable}, its | |
| 196 * exception handler method will be called if any exceptions occur while | |
| 197 * running it. Otherwise, the exception will be logged. | |
| 198 * </p> | |
| 199 * <p> | |
| 200 * Subclasses should use {@link #safeRuncast(Runnable)} to run the runnable. | |
| 201 * </p> | |
| 202 * | |
| 203 * @param runnable | |
| 204 */ | |
| 205 public void asyncExec(Runnable runnable) { | |
| 206 synchronized (workQueue) { | |
| 207 ensureWorkerThreadIsRunning(); | |
| 85 | 208 workQueue.enqueue(cast(Object)runnable); |
| 78 | 209 workQueue.notifyAll(); |
| 210 } | |
| 211 } | |
| 212 | |
| 213 /** | |
| 214 * | |
| 215 */ | |
| 216 private void ensureWorkerThreadIsRunning() { | |
| 217 if (workerThread is null) { | |
| 218 workerThread = new class() Thread { | |
| 219 public void run() { | |
| 220 try { | |
| 221 while (true) { | |
| 222 Runnable work = null; | |
| 223 synchronized (workQueue) { | |
| 224 while (workQueue.isEmpty()) { | |
| 225 workQueue.wait(); | |
| 226 } | |
| 227 work = cast(Runnable) workQueue.dequeue(); | |
| 228 } | |
| 229 syncExec(work); | |
| 230 } | |
| 231 } catch (InterruptedException e) { | |
| 232 // exit | |
| 233 } | |
| 234 } | |
| 235 }; | |
| 236 workerThread.start(); | |
| 237 } | |
| 238 } | |
| 239 | |
| 240 /** | |
| 241 * Causes the <code>run()</code> method of the runnable to be invoked from | |
| 242 * within this realm at the next reasonable opportunity. This method is | |
| 243 * blocking the caller until the runnable completes. | |
| 244 * <p> | |
| 245 * If the given runnable is an instance of {@link ISafeRunnable}, its | |
| 246 * exception handler method will be called if any exceptions occur while | |
| 247 * running it. Otherwise, the exception will be logged. | |
| 248 * </p> | |
| 249 * <p> | |
| 250 * Subclasses should use {@link #safeRuncast(Runnable)} to run the runnable. | |
| 251 * </p> | |
| 252 * <p> | |
| 253 * Note: This class is not meant to be called by clients and therefore has | |
| 254 * only protected access. | |
| 255 * </p> | |
| 256 * | |
| 257 * @param runnable | |
| 258 */ | |
| 259 protected void syncExec(Runnable runnable) { | |
| 260 SyncRunnable syncRunnable = new SyncRunnable(runnable); | |
| 261 asyncExec(syncRunnable); | |
| 262 synchronized (syncRunnable) { | |
| 263 while (!syncRunnable.hasRun) { | |
| 264 try { | |
| 265 syncRunnable.wait(); | |
| 266 } catch (InterruptedException e) { | |
| 267 Thread.currentThread().interrupt(); | |
| 268 } | |
| 269 } | |
| 270 } | |
| 271 } | |
| 272 | |
| 273 static class SyncRunnable : Runnable { | |
| 274 bool hasRun = false; | |
| 275 | |
| 276 private Runnable runnable; | |
| 277 | |
| 278 this(Runnable runnable) { | |
| 279 this.runnable = runnable; | |
| 280 } | |
| 281 | |
| 282 public void run() { | |
| 283 try { | |
| 284 safeRun(runnable); | |
| 285 } finally { | |
| 286 synchronized (this) { | |
| 287 hasRun = true; | |
| 288 this.notifyAll(); | |
| 289 } | |
| 290 } | |
| 291 } | |
| 85 | 292 void notifyAll(){ |
| 293 implMissing( __FILE__, __LINE__ ); | |
| 294 } | |
| 295 void wait(){ | |
| 296 implMissing( __FILE__, __LINE__ ); | |
| 297 } | |
| 78 | 298 } |
| 299 | |
| 300 /** | |
| 301 * Sets the provided <code>realm</code> as the default for the duration of | |
| 302 * {@link Runnable#run()} and resets the previous realm after completion. | |
| 303 * Note that this will not set the given realm as the current realm. | |
| 304 * | |
| 305 * @param realm | |
| 306 * @param runnable | |
| 307 */ | |
| 308 public static void runWithDefault(Realm realm, Runnable runnable) { | |
| 309 Realm oldRealm = Realm.getDefault(); | |
| 310 try { | |
| 311 defaultRealm.set(realm); | |
| 312 runnable.run(); | |
| 313 } finally { | |
| 314 defaultRealm.set(oldRealm); | |
| 315 } | |
| 316 } | |
| 317 } |