| 7 |
|
package jsr166y; |
| 8 |
|
|
| 9 |
|
/** |
| 10 |
< |
* A resultless {@link ForkJoinTask} with a completion action |
| 11 |
< |
* performed when triggered and there are no remaining pending |
| 12 |
< |
* actions. Uses of CountedCompleter are similar to those of other |
| 13 |
< |
* completion based components (such as {@link |
| 14 |
< |
* java.nio.channels.CompletionHandler}) except that multiple |
| 15 |
< |
* <em>pending</em> completions may be necessary to trigger the {@link |
| 16 |
< |
* #onCompletion} action, not just one. Unless initialized otherwise, |
| 17 |
< |
* the {@link #getPendingCount pending count} starts at zero, but may |
| 18 |
< |
* be (atomically) changed using methods {@link #setPendingCount}, |
| 19 |
< |
* {@link #addToPendingCount}, and {@link |
| 10 |
> |
* A {@link ForkJoinTask} with a completion action performed when |
| 11 |
> |
* triggered and there are no remaining pending |
| 12 |
> |
* actions. CountedCompleters are in general more robust in the |
| 13 |
> |
* presence of subtask stalls and blockage than are other forms for |
| 14 |
> |
* ForkJoinTasks, but are in general less intuitive to program. Uses |
| 15 |
> |
* of CountedCompleter are similar to those of other completion based |
| 16 |
> |
* components (such as {@link java.nio.channels.CompletionHandler}) |
| 17 |
> |
* except that multiple <em>pending</em> completions may be necessary |
| 18 |
> |
* to trigger the {@link #onCompletion} action, not just one. Unless |
| 19 |
> |
* initialized otherwise, the {@link #getPendingCount pending count} |
| 20 |
> |
* starts at zero, but may be (atomically) changed using methods |
| 21 |
> |
* {@link #setPendingCount}, {@link #addToPendingCount}, and {@link |
| 22 |
|
* #compareAndSetPendingCount}. Upon invocation of {@link |
| 23 |
|
* #tryComplete}, if the pending action count is nonzero, it is |
| 24 |
|
* decremented; otherwise, the completion action is performed, and if |
| 25 |
|
* this completer itself has a completer, the process is continued |
| 26 |
< |
* with its completer. As is the case with most basic synchronization |
| 27 |
< |
* constructs, these methods affect only internal counts; they do not |
| 28 |
< |
* establish any further internal bookkeeping. In particular, the |
| 29 |
< |
* identities of pending tasks are not maintained. As illustrated |
| 30 |
< |
* below, you can create subclasses that do record some or all pended |
| 31 |
< |
* tasks or their results when needed. |
| 26 |
> |
* with its completer. As is the case with related synchronization |
| 27 |
> |
* components such as {@link java.util.concurrent.Phaser Phaser} and |
| 28 |
> |
* {@link java.util.concurrent.Semaphore Semaphore}, these methods |
| 29 |
> |
* affect only internal counts; they do not establish any further |
| 30 |
> |
* internal bookkeeping. In particular, the identities of pending |
| 31 |
> |
* tasks are not maintained. As illustrated below, you can create |
| 32 |
> |
* subclasses that do record some or all pending tasks or their |
| 33 |
> |
* results when needed. Because CountedCompleters provide only basic |
| 34 |
> |
* synchronization mechanisms, it may be useful to create further |
| 35 |
> |
* abstract subclasses that maintain linkages and fields and support |
| 36 |
> |
* methods appropriate for a set of related usages. |
| 37 |
|
* |
| 38 |
|
* <p>A concrete CountedCompleter class must define method {@link |
| 39 |
< |
* #compute}, that should, in almost all use cases, invoke {@code |
| 40 |
< |
* tryComplete()} before returning. The class may also optionally |
| 41 |
< |
* override method {@link #onCompletion} to perform an action upon |
| 42 |
< |
* normal completion. |
| 39 |
> |
* #compute}, that should in most cases (as illustrated below), invoke |
| 40 |
> |
* {@code tryComplete()} once before returning. The class may also |
| 41 |
> |
* optionally override method {@link #onCompletion} to perform an |
| 42 |
> |
* action upon normal completion, and method {@link |
| 43 |
> |
* #onExceptionalCompletion} to perform an action upon any exception. |
| 44 |
> |
* |
| 45 |
> |
* <p>CountedCompleters most often do not bear results, in which case |
| 46 |
> |
* they are normally declared as {@code CountedCompleter<Void>}, and |
| 47 |
> |
* will always return {@code null} as a result value. In other cases, |
| 48 |
> |
* you should override method {@link #getRawResult} to provide a |
| 49 |
> |
* result from {@code join(), invoke()}, and related methods. In |
| 50 |
> |
* general, this method should return the value of a field (or a |
| 51 |
> |
* function of one or more fields) of the CountedCompleter object that |
| 52 |
> |
* holds the result upon completion. Method {@link #setRawResult} by |
| 53 |
> |
* default plays no role in CountedCompleters. It is possible, but |
| 54 |
> |
* not usually applicable, to override this method to maintain other |
| 55 |
> |
* objects or fields holding result data. |
| 56 |
|
* |
| 57 |
|
* <p>A CountedCompleter that does not itself have a completer (i.e., |
| 58 |
|
* one for which {@link #getCompleter} returns {@code null}) can be |
| 64 |
|
* {@link #complete}, {@link ForkJoinTask#cancel}, {@link |
| 65 |
|
* ForkJoinTask#completeExceptionally} or upon exceptional completion |
| 66 |
|
* of method {@code compute}. Upon any exceptional completion, the |
| 67 |
< |
* exception is relayed to a task's completer (and its completer, and |
| 68 |
< |
* so on), if one exists and it has not otherwise already completed. |
| 67 |
> |
* exception may be relayed to a task's completer (and its completer, |
| 68 |
> |
* and so on), if one exists and it has not otherwise already |
| 69 |
> |
* completed. Similarly, cancelling an internal CountedCompleter has |
| 70 |
> |
* only a local effect on that completer, so is not often useful. |
| 71 |
|
* |
| 72 |
|
* <p><b>Sample Usages.</b> |
| 73 |
|
* |
| 74 |
|
* <p><b>Parallel recursive decomposition.</b> CountedCompleters may |
| 75 |
|
* be arranged in trees similar to those often used with {@link |
| 76 |
|
* RecursiveAction}s, although the constructions involved in setting |
| 77 |
< |
* them up typically vary. Even though they entail a bit more |
| 77 |
> |
* them up typically vary. Here, the completer of each task is its |
| 78 |
> |
* parent in the computation tree. Even though they entail a bit more |
| 79 |
|
* bookkeeping, CountedCompleters may be better choices when applying |
| 80 |
|
* a possibly time-consuming operation (that cannot be further |
| 81 |
|
* subdivided) to each element of an array or collection; especially |
| 86 |
|
* continuations, other threads need not block waiting to perform |
| 87 |
|
* them. |
| 88 |
|
* |
| 89 |
< |
* <p> For example, here is an initial version of a class that uses |
| 89 |
> |
* <p>For example, here is an initial version of a class that uses |
| 90 |
|
* divide-by-two recursive decomposition to divide work into single |
| 91 |
|
* pieces (leaf tasks). Even when work is split into individual calls, |
| 92 |
|
* tree-based techniques are usually preferable to directly forking |
| 95 |
|
* pair of subtasks to finish triggers completion of its parent |
| 96 |
|
* (because no result combination is performed, the default no-op |
| 97 |
|
* implementation of method {@code onCompletion} is not overridden). A |
| 98 |
< |
* static utility method sets up the base task and invokes it: |
| 98 |
> |
* static utility method sets up the base task and invokes it |
| 99 |
> |
* (here, implicitly using the {@link ForkJoinPool#commonPool()}). |
| 100 |
|
* |
| 101 |
|
* <pre> {@code |
| 102 |
|
* class MyOperation<E> { void apply(E e) { ... } } |
| 103 |
|
* |
| 104 |
< |
* class ForEach<E> extends CountedCompleter { |
| 104 |
> |
* class ForEach<E> extends CountedCompleter<Void> { |
| 105 |
|
* |
| 106 |
< |
* public static <E> void forEach(ForkJoinPool pool, E[] array, MyOperation<E> op) { |
| 107 |
< |
* pool.invoke(new ForEach<E>(null, array, op, 0, array.length)); |
| 106 |
> |
* public static <E> void forEach(E[] array, MyOperation<E> op) { |
| 107 |
> |
* new ForEach<E>(null, array, op, 0, array.length).invoke(); |
| 108 |
|
* } |
| 109 |
|
* |
| 110 |
|
* final E[] array; final MyOperation<E> op; final int lo, hi; |
| 111 |
< |
* ForEach(CountedCompleter p, E[] array, MyOperation<E> op, int lo, int hi) { |
| 111 |
> |
* ForEach(CountedCompleter<?> p, E[] array, MyOperation<E> op, int lo, int hi) { |
| 112 |
|
* super(p); |
| 113 |
|
* this.array = array; this.op = op; this.lo = lo; this.hi = hi; |
| 114 |
|
* } |
| 152 |
|
* |
| 153 |
|
* As a further improvement, notice that the left task need not even |
| 154 |
|
* exist. Instead of creating a new one, we can iterate using the |
| 155 |
< |
* original task, and add a pending count for each fork: |
| 155 |
> |
* original task, and add a pending count for each fork. |
| 156 |
|
* |
| 157 |
|
* <pre> {@code |
| 158 |
|
* class ForEach<E> ... |
| 183 |
|
* and reductions are all of type {@code E}), one way to do this in |
| 184 |
|
* divide and conquer designs is to have each subtask record its |
| 185 |
|
* sibling, so that it can be accessed in method {@code onCompletion}. |
| 186 |
< |
* For clarity, this class uses explicit left and right subtasks, but |
| 187 |
< |
* variants of other streamlinings seen in the above example may also |
| 188 |
< |
* apply. |
| 186 |
> |
* This technique applies to reductions in which the order of |
| 187 |
> |
* combining left and right results does not matter; ordered |
| 188 |
> |
* reductions require explicit left/right designations. Variants of |
| 189 |
> |
* other streamlinings seen in the above examples may also apply. |
| 190 |
|
* |
| 191 |
|
* <pre> {@code |
| 192 |
|
* class MyMapper<E> { E apply(E v) { ... } } |
| 193 |
|
* class MyReducer<E> { E apply(E x, E y) { ... } } |
| 194 |
< |
* class MapReducer<E> extends CountedCompleter { |
| 194 |
> |
* class MapReducer<E> extends CountedCompleter<E> { |
| 195 |
|
* final E[] array; final MyMapper<E> mapper; |
| 196 |
|
* final MyReducer<E> reducer; final int lo, hi; |
| 197 |
< |
* MapReducer sibling; |
| 197 |
> |
* MapReducer<E> sibling; |
| 198 |
|
* E result; |
| 199 |
|
* MapReducer(CountedCompleter p, E[] array, MyMapper<E> mapper, |
| 200 |
|
* MyReducer<E> reducer, int lo, int hi) { |
| 229 |
|
* result = reducer.apply(child.result, sib.result); |
| 230 |
|
* } |
| 231 |
|
* } |
| 232 |
+ |
* public E getRawResult() { return result; } |
| 233 |
|
* |
| 234 |
< |
* public static <E> E mapReduce(ForkJoinPool pool, E[] array, |
| 235 |
< |
* MyMapper<E> mapper, MyReducer<E> reducer) { |
| 236 |
< |
* MapReducer<E> mr = new MapReducer<E>(null, array, mapper, |
| 211 |
< |
* reducer, 0, array.length); |
| 212 |
< |
* pool.invoke(mr); |
| 213 |
< |
* return mr.result; |
| 234 |
> |
* public static <E> E mapReduce(E[] array, MyMapper<E> mapper, MyReducer<E> reducer) { |
| 235 |
> |
* return new MapReducer<E>(null, array, mapper, reducer, |
| 236 |
> |
* 0, array.length).invoke(); |
| 237 |
|
* } |
| 238 |
|
* } }</pre> |
| 239 |
|
* |
| 240 |
+ |
* Here, method {@code onCompletion} takes a form common to many |
| 241 |
+ |
* completion designs that combine results. This callback-style method |
| 242 |
+ |
* is triggered once per task, in either of the two different contexts |
| 243 |
+ |
* in which the pending count is, or becomes, zero: (1) by a task |
| 244 |
+ |
* itself, if its pending count is zero upon invocation of {@code |
| 245 |
+ |
* tryComplete}, or (2) by any of its subtasks when they complete and |
| 246 |
+ |
* decrement the pending count to zero. The {@code caller} argument |
| 247 |
+ |
* distinguishes cases. Most often, when the caller is {@code this}, |
| 248 |
+ |
* no action is necessary. Otherwise the caller argument can be used |
| 249 |
+ |
* (usually via a cast) to supply a value (and/or links to other |
| 250 |
+ |
* values) to be combined. Asuuming proper use of pending counts, the |
| 251 |
+ |
* actions inside {@code onCompletion} occur (once) upon completion of |
| 252 |
+ |
* a task and its subtasks. No additional synchronization is required |
| 253 |
+ |
* within this method to ensure thread safety of accesses to fields of |
| 254 |
+ |
* this task or other completed tasks. |
| 255 |
+ |
* |
| 256 |
+ |
* <p><b>Searching.</b> A tree of CountedCompleters can search for a |
| 257 |
+ |
* value or property in different parts of a data structure, and |
| 258 |
+ |
* report a result in an {@link java.util.concurrent.AtomicReference} |
| 259 |
+ |
* as soon as one is found. The others can poll the result to avoid |
| 260 |
+ |
* unnecessary work. (You could additionally {@link #cancel} other |
| 261 |
+ |
* tasks, but it is usually simpler and more efficient to just let |
| 262 |
+ |
* them notice that the result is set and if so skip further |
| 263 |
+ |
* processing.) Illustrating again with an array using full |
| 264 |
+ |
* partitioning (again, in practice, leaf tasks will almost always |
| 265 |
+ |
* process more than one element): |
| 266 |
+ |
* |
| 267 |
+ |
* <pre> {@code |
| 268 |
+ |
* class Searcher<E> extends CountedCompleter<E> { |
| 269 |
+ |
* final E[] array; final AtomicReference<E> result; final int lo, hi; |
| 270 |
+ |
* Searcher(CountedCompleter<?> p, E[] array, AtomicReference<E> result, int lo, int hi) { |
| 271 |
+ |
* super(p); |
| 272 |
+ |
* this.array = array; this.result = result; this.lo = lo; this.hi = hi; |
| 273 |
+ |
* } |
| 274 |
+ |
* public E getRawResult() { return result.get(); } |
| 275 |
+ |
* public void compute() { // similar to ForEach version 3 |
| 276 |
+ |
* int l = lo, h = hi; |
| 277 |
+ |
* while (h - l >= 2 && result.get() == null) { |
| 278 |
+ |
* int mid = (l + h) >>> 1; |
| 279 |
+ |
* addToPendingCount(1); |
| 280 |
+ |
* new Searcher(this, array, result, mid, h).fork(); |
| 281 |
+ |
* h = mid; |
| 282 |
+ |
* } |
| 283 |
+ |
* if (h > l && result.get() == null && matches(array[l]) && |
| 284 |
+ |
* result.compareAndSet(null, array[l])) |
| 285 |
+ |
* getRoot().quietlyComplete(); // root task is now joinable |
| 286 |
+ |
* |
| 287 |
+ |
* tryComplete(); // normally complete whether or not found |
| 288 |
+ |
* } |
| 289 |
+ |
* boolean matches(E e) { ... } // return true if found |
| 290 |
+ |
* |
| 291 |
+ |
* public static <E> E search(E[] array) { |
| 292 |
+ |
* return new Searcher<E>(null, array, new AtomicReference<E>(), 0, array.length).invoke(); |
| 293 |
+ |
* } |
| 294 |
+ |
*}}</pre> |
| 295 |
+ |
* |
| 296 |
+ |
* In this example, as well as others in which tasks have no other |
| 297 |
+ |
* effects except to compareAndSet a common result, the trailing |
| 298 |
+ |
* unconditional invocation of {@code tryComplete} could be made |
| 299 |
+ |
* conditional ({@code if (result.get() == null) tryComplete();}) |
| 300 |
+ |
* because no further bookkeeping is required to manage completions |
| 301 |
+ |
* once the root task completes. |
| 302 |
+ |
* |
| 303 |
|
* <p><b>Triggers.</b> Some CountedCompleters are themselves never |
| 304 |
|
* forked, but instead serve as bits of plumbing in other designs; |
| 305 |
|
* including those in which the completion of one of more async tasks |
| 306 |
|
* triggers another async task. For example: |
| 307 |
|
* |
| 308 |
|
* <pre> {@code |
| 309 |
< |
* class HeaderBuilder extends CountedCompleter { ... } |
| 310 |
< |
* class BodyBuilder extends CountedCompleter { ... } |
| 311 |
< |
* class PacketSender extends CountedCompleter { |
| 309 |
> |
* class HeaderBuilder extends CountedCompleter<...> { ... } |
| 310 |
> |
* class BodyBuilder extends CountedCompleter<...> { ... } |
| 311 |
> |
* class PacketSender extends CountedCompleter<...> { |
| 312 |
|
* PacketSender(...) { super(null, 1); ... } // trigger on second completion |
| 313 |
|
* public void compute() { } // never called |
| 314 |
< |
* public void onCompletion(CountedCompleter caller) { sendPacket(); } |
| 314 |
> |
* public void onCompletion(CountedCompleter<?> caller) { sendPacket(); } |
| 315 |
|
* } |
| 316 |
|
* // sample use: |
| 317 |
|
* PacketSender p = new PacketSender(); |
| 322 |
|
* @since 1.8 |
| 323 |
|
* @author Doug Lea |
| 324 |
|
*/ |
| 325 |
< |
public abstract class CountedCompleter extends ForkJoinTask<Void> { |
| 325 |
> |
public abstract class CountedCompleter<T> extends ForkJoinTask<T> { |
| 326 |
> |
private static final long serialVersionUID = 5232453752276485070L; |
| 327 |
> |
|
| 328 |
|
/** This task's completer, or null if none */ |
| 329 |
< |
final CountedCompleter completer; |
| 329 |
> |
final CountedCompleter<?> completer; |
| 330 |
|
/** The number of pending tasks until completion */ |
| 331 |
|
volatile int pending; |
| 332 |
|
|
| 337 |
|
* @param completer this tasks completer, or {@code null} if none |
| 338 |
|
* @param initialPendingCount the initial pending count |
| 339 |
|
*/ |
| 340 |
< |
protected CountedCompleter(CountedCompleter completer, |
| 340 |
> |
protected CountedCompleter(CountedCompleter<?> completer, |
| 341 |
|
int initialPendingCount) { |
| 342 |
|
this.completer = completer; |
| 343 |
|
this.pending = initialPendingCount; |
| 349 |
|
* |
| 350 |
|
* @param completer this tasks completer, or {@code null} if none |
| 351 |
|
*/ |
| 352 |
< |
protected CountedCompleter(CountedCompleter completer) { |
| 352 |
> |
protected CountedCompleter(CountedCompleter<?> completer) { |
| 353 |
|
this.completer = completer; |
| 354 |
|
} |
| 355 |
|
|
| 367 |
|
public abstract void compute(); |
| 368 |
|
|
| 369 |
|
/** |
| 370 |
< |
* Executes the completion action when method {@link #tryComplete} |
| 371 |
< |
* is invoked and there are no pending counts, or when the |
| 372 |
< |
* unconditional method {@link #complete} is invoked. By default, |
| 373 |
< |
* this method does nothing. |
| 370 |
> |
* Performs an action when method {@link #tryComplete} is invoked |
| 371 |
> |
* and there are no pending counts, or when the unconditional |
| 372 |
> |
* method {@link #complete} is invoked. By default, this method |
| 373 |
> |
* does nothing. You can distinguish cases by checking the |
| 374 |
> |
* identity of the given caller argument. If not equal to {@code |
| 375 |
> |
* this}, then it is typically a subtask that may contain results |
| 376 |
> |
* (and/or links to other results) to combine. |
| 377 |
|
* |
| 378 |
|
* @param caller the task invoking this method (which may |
| 379 |
|
* be this task itself). |
| 380 |
|
*/ |
| 381 |
< |
public void onCompletion(CountedCompleter caller) { |
| 381 |
> |
public void onCompletion(CountedCompleter<?> caller) { |
| 382 |
> |
} |
| 383 |
> |
|
| 384 |
> |
/** |
| 385 |
> |
* Performs an action when method {@link #completeExceptionally} |
| 386 |
> |
* is invoked or method {@link #compute} throws an exception, and |
| 387 |
> |
* this task has not otherwise already completed normally. On |
| 388 |
> |
* entry to this method, this task {@link |
| 389 |
> |
* ForkJoinTask#isCompletedAbnormally}. The return value of this |
| 390 |
> |
* method controls further propagation: If {@code true} and this |
| 391 |
> |
* task has a completer, then this completer is also completed |
| 392 |
> |
* exceptionally. The default implementation of this method does |
| 393 |
> |
* nothing except return {@code true}. |
| 394 |
> |
* |
| 395 |
> |
* @param ex the exception |
| 396 |
> |
* @param caller the task invoking this method (which may |
| 397 |
> |
* be this task itself). |
| 398 |
> |
* @return true if this exception should be propagated to this |
| 399 |
> |
* tasks completer, if one exists. |
| 400 |
> |
*/ |
| 401 |
> |
public boolean onExceptionalCompletion(Throwable ex, CountedCompleter<?> caller) { |
| 402 |
> |
return true; |
| 403 |
|
} |
| 404 |
|
|
| 405 |
|
/** |
| 408 |
|
* |
| 409 |
|
* @return the completer |
| 410 |
|
*/ |
| 411 |
< |
public final CountedCompleter getCompleter() { |
| 411 |
> |
public final CountedCompleter<?> getCompleter() { |
| 412 |
|
return completer; |
| 413 |
|
} |
| 414 |
|
|
| 453 |
|
} |
| 454 |
|
|
| 455 |
|
/** |
| 456 |
+ |
* Returns the root of the current computation; i.e., this |
| 457 |
+ |
* task if it has no completer, else its completer's root. |
| 458 |
+ |
* |
| 459 |
+ |
* @return the root of the current computation |
| 460 |
+ |
*/ |
| 461 |
+ |
public final CountedCompleter<?> getRoot() { |
| 462 |
+ |
CountedCompleter<?> a = this, p; |
| 463 |
+ |
while ((p = a.completer) != null) |
| 464 |
+ |
a = p; |
| 465 |
+ |
return a; |
| 466 |
+ |
} |
| 467 |
+ |
|
| 468 |
+ |
/** |
| 469 |
|
* If the pending count is nonzero, decrements the count; |
| 470 |
|
* otherwise invokes {@link #onCompletion} and then similarly |
| 471 |
|
* tries to complete this task's completer, if one exists, |
| 472 |
|
* else marks this task as complete. |
| 473 |
|
*/ |
| 474 |
|
public final void tryComplete() { |
| 475 |
< |
for (CountedCompleter a = this, s = a;;) { |
| 476 |
< |
int c; |
| 475 |
> |
CountedCompleter<?> a = this, s = a; |
| 476 |
> |
for (int c;;) { |
| 477 |
|
if ((c = a.pending) == 0) { |
| 478 |
|
a.onCompletion(s); |
| 479 |
|
if ((a = (s = a).completer) == null) { |
| 488 |
|
|
| 489 |
|
/** |
| 490 |
|
* Regardless of pending count, invokes {@link #onCompletion}, |
| 491 |
< |
* marks this task as complete with a {@code null} return value, |
| 492 |
< |
* and further triggers {@link #tryComplete} on this task's |
| 493 |
< |
* completer, if one exists. This method may be useful when |
| 494 |
< |
* forcing completion as soon as any one (versus all) of several |
| 495 |
< |
* subtask results are obtained. |
| 496 |
< |
* |
| 497 |
< |
* @param mustBeNull the {@code null} completion value |
| 498 |
< |
*/ |
| 499 |
< |
public void complete(Void mustBeNull) { |
| 500 |
< |
CountedCompleter p; |
| 491 |
> |
* marks this task as complete and further triggers {@link |
| 492 |
> |
* #tryComplete} on this task's completer, if one exists. The |
| 493 |
> |
* given rawResult is used as an argument to {@link #setRawResult} |
| 494 |
> |
* before invoking {@link #onCompletion} or marking this task as |
| 495 |
> |
* complete; its value is meaningful only for classes overriding |
| 496 |
> |
* {@code setRawResult}. |
| 497 |
> |
* |
| 498 |
> |
* <p>This method may be useful when forcing completion as soon as |
| 499 |
> |
* any one (versus all) of several subtask results are obtained. |
| 500 |
> |
* However, in the common (and recommended) case in which {@code |
| 501 |
> |
* setRawResult} is not overridden, this effect can be obtained |
| 502 |
> |
* more simply using {@code getRoot().quietlyComplete();}. |
| 503 |
> |
* |
| 504 |
> |
* @param rawResult the raw result |
| 505 |
> |
*/ |
| 506 |
> |
public void complete(T rawResult) { |
| 507 |
> |
CountedCompleter<?> p; |
| 508 |
> |
setRawResult(rawResult); |
| 509 |
|
onCompletion(this); |
| 510 |
|
quietlyComplete(); |
| 511 |
|
if ((p = completer) != null) |
| 513 |
|
} |
| 514 |
|
|
| 515 |
|
/** |
| 516 |
+ |
* Support for FJT exception propagation |
| 517 |
+ |
*/ |
| 518 |
+ |
void internalPropagateException(Throwable ex) { |
| 519 |
+ |
CountedCompleter<?> a = this, s = a; |
| 520 |
+ |
while (a.onExceptionalCompletion(ex, s) && |
| 521 |
+ |
(a = (s = a).completer) != null && a.status >= 0) |
| 522 |
+ |
a.recordExceptionalCompletion(ex); |
| 523 |
+ |
} |
| 524 |
+ |
|
| 525 |
+ |
/** |
| 526 |
|
* Implements execution conventions for CountedCompleters |
| 527 |
|
*/ |
| 528 |
|
protected final boolean exec() { |
| 531 |
|
} |
| 532 |
|
|
| 533 |
|
/** |
| 534 |
< |
* Always returns {@code null}. |
| 534 |
> |
* Returns the result of the computation. By default |
| 535 |
> |
* returns {@code null}, which is appropriate for {@code Void} |
| 536 |
> |
* actions, but in other cases should be overridden. |
| 537 |
|
* |
| 538 |
< |
* @return {@code null} always |
| 394 |
< |
*/ |
| 395 |
< |
public final Void getRawResult() { return null; } |
| 396 |
< |
|
| 397 |
< |
/** |
| 398 |
< |
* Requires null completion value. |
| 538 |
> |
* @return the result of the computation |
| 539 |
|
*/ |
| 540 |
< |
protected final void setRawResult(Void mustBeNull) { } |
| 540 |
> |
public T getRawResult() { return null; } |
| 541 |
|
|
| 542 |
|
/** |
| 543 |
< |
* Support for FJT exception propagation |
| 543 |
> |
* A method that result-bearing CountedCompleters may optionally |
| 544 |
> |
* use to help maintain result data. By default, does nothing. |
| 545 |
> |
* If this method is overridden to update existing objects or |
| 546 |
> |
* fields, then it must in general be defined to be thread-safe. |
| 547 |
|
*/ |
| 548 |
< |
final ForkJoinTask<?> internalGetCompleter() { return completer; } |
| 548 |
> |
protected void setRawResult(T t) { } |
| 549 |
|
|
| 550 |
|
// Unsafe mechanics |
| 551 |
|
private static final sun.misc.Unsafe U; |
| 552 |
|
private static final long PENDING; |
| 553 |
|
static { |
| 554 |
|
try { |
| 555 |
< |
U = getUnsafe(); |
| 555 |
> |
U = sun.misc.Unsafe.getUnsafe(); |
| 556 |
|
PENDING = U.objectFieldOffset |
| 557 |
|
(CountedCompleter.class.getDeclaredField("pending")); |
| 558 |
|
} catch (Exception e) { |
| 560 |
|
} |
| 561 |
|
} |
| 562 |
|
|
| 420 |
– |
|
| 563 |
|
/** |
| 564 |
|
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
| 565 |
|
* Replace with a simple call to Unsafe.getUnsafe when integrating |
| 587 |
|
} |
| 588 |
|
} |
| 589 |
|
} |
| 448 |
– |
|
| 590 |
|
} |
