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*/ |
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package jsr166y; |
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+ |
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import java.io.Serializable; |
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import java.util.Collection; |
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import java.util.List; |
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* <p>The ForkJoinTask class is not usually directly subclassed. |
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* Instead, you subclass one of the abstract classes that support a |
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* particular style of fork/join processing, typically {@link |
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* RecursiveAction} for computations that do not return results, or |
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* {@link RecursiveTask} for those that do. Normally, a concrete |
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* ForkJoinTask subclass declares fields comprising its parameters, |
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* established in a constructor, and then defines a {@code compute} |
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* method that somehow uses the control methods supplied by this base |
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* class. While these methods have {@code public} access (to allow |
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* instances of different task subclasses to call each other's |
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* methods), some of them may only be called from within other |
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* ForkJoinTasks (as may be determined using method {@link |
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* #inForkJoinPool}). Attempts to invoke them in other contexts |
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* result in exceptions or errors, possibly including |
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* {@code ClassCastException}. |
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* RecursiveAction} for most computations that do not return results, |
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* {@link RecursiveTask} for those that do, and {@link |
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* CountedCompleter} for those in which completed actions trigger |
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* other actions. Normally, a concrete ForkJoinTask subclass declares |
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* fields comprising its parameters, established in a constructor, and |
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* then defines a {@code compute} method that somehow uses the control |
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* methods supplied by this base class. While these methods have |
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* {@code public} access (to allow instances of different task |
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* subclasses to call each other's methods), some of them may only be |
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* called from within other ForkJoinTasks (as may be determined using |
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* method {@link #inForkJoinPool}). Attempts to invoke them in other |
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* contexts result in exceptions or errors, possibly including {@code |
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* ClassCastException}. |
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* |
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* <p>Method {@link #join} and its variants are appropriate for use |
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* only when completion dependencies are acyclic; that is, the |
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} |
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|
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/** |
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* Tries to set SIGNAL status. Used by ForkJoinPool. Other |
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* variants are directly incorporated into externalAwaitDone etc. |
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* Tries to set SIGNAL status unless already completed. Used by |
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* ForkJoinPool. Other variants are directly incorporated into |
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* externalAwaitDone etc. |
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* |
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* @return true if successful |
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*/ |
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final boolean trySetSignal() { |
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< |
int s; |
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< |
return U.compareAndSwapInt(this, STATUS, s = status, s | SIGNAL); |
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> |
int s = status; |
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> |
return s >= 0 && U.compareAndSwapInt(this, STATUS, s, s | SIGNAL); |
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} |
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|
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/** |
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* @return status on exit |
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*/ |
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private int setExceptionalCompletion(Throwable ex) { |
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int h = System.identityHashCode(this); |
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final ReentrantLock lock = exceptionTableLock; |
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lock.lock(); |
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try { |
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expungeStaleExceptions(); |
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ExceptionNode[] t = exceptionTable; |
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int i = h & (t.length - 1); |
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< |
for (ExceptionNode e = t[i]; ; e = e.next) { |
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if (e == null) { |
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t[i] = new ExceptionNode(this, ex, t[i]); |
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< |
break; |
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> |
int s; |
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> |
if ((s = status) >= 0) { |
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> |
int h = System.identityHashCode(this); |
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> |
final ReentrantLock lock = exceptionTableLock; |
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> |
lock.lock(); |
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> |
try { |
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> |
expungeStaleExceptions(); |
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> |
ExceptionNode[] t = exceptionTable; |
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> |
int i = h & (t.length - 1); |
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> |
for (ExceptionNode e = t[i]; ; e = e.next) { |
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> |
if (e == null) { |
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t[i] = new ExceptionNode(this, ex, t[i]); |
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> |
break; |
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> |
} |
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> |
if (e.get() == this) // already present |
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break; |
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} |
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< |
if (e.get() == this) // already present |
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< |
break; |
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> |
} finally { |
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> |
lock.unlock(); |
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} |
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< |
} finally { |
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< |
lock.unlock(); |
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> |
s = setCompletion(EXCEPTIONAL); |
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} |
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< |
return setCompletion(EXCEPTIONAL); |
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> |
ForkJoinTask<?> p = internalGetCompleter(); // propagate |
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> |
if (p != null && p.status >= 0) |
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p.setExceptionalCompletion(ex); |
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return s; |
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} |
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> |
|
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> |
/** |
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* Exception propagation support for tasks with completers. |
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*/ |
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> |
ForkJoinTask<?> internalGetCompleter() { |
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> |
return null; |
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} |
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|
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/** |
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Throwable ex; |
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if (e == null || (ex = e.ex) == null) |
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return null; |
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< |
if (e.thrower != Thread.currentThread().getId()) { |
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> |
if (false && e.thrower != Thread.currentThread().getId()) { |
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Class<? extends Throwable> ec = ex.getClass(); |
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try { |
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Constructor<?> noArgCtor = null; |
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} |
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|
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/** |
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< |
* Completes this task. The most recent value established by |
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* {@link #setRawResult} (or {@code null}) will be returned as the |
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* result of subsequent invocations of {@code join} and related |
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* operations. This method may be useful when processing sets of |
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* tasks when some do not otherwise complete normally. Its use in |
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* other situations is discouraged. |
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* Completes this task normally without setting a value. The most |
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* recent value established by {@link #setRawResult} (or {@code |
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* null} by default) will be returned as the result of subsequent |
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* invocations of {@code join} and related operations. |
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* |
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* @since 1.8 |
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*/ |
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public final void quietlyComplete() { |
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setCompletion(NORMAL); |
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protected abstract void setRawResult(V value); |
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/** |
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* Immediately performs the base action of this task. This method |
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* is designed to support extensions, and should not in general be |
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* called otherwise. The return value controls whether this task |
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* is considered to be done normally. It may return false in |
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* Immediately performs the base action of this task and returns |
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> |
* true if, upon return from this method, this task is guaranteed |
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* to have completed normally. This method may return false |
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* otherwise, to indicate that this task is not necessarily |
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* complete (or is not known to be complete), for example in |
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* asynchronous actions that require explicit invocations of |
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< |
* {@link #complete} to become joinable. It may also throw an |
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< |
* (unchecked) exception to indicate abnormal exit. |
| 1260 |
> |
* completion methods. This method may also throw an (unchecked) |
| 1261 |
> |
* exception to indicate abnormal exit. This method is designed to |
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> |
* support extensions, and should not in general be called |
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> |
* otherwise. |
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* |
| 1265 |
< |
* @return {@code true} if completed normally |
| 1265 |
> |
* @return {@code true} if this task is known to have completed normally |
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*/ |
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protected abstract boolean exec(); |
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|
