--- jsr166/src/jsr166y/ForkJoinTask.java 2012/03/04 19:47:08 1.88
+++ jsr166/src/jsr166y/ForkJoinTask.java 2012/04/09 13:11:44 1.89
@@ -5,6 +5,7 @@
*/
package jsr166y;
+
import java.io.Serializable;
import java.util.Collection;
import java.util.List;
@@ -115,18 +116,19 @@ import java.lang.reflect.Constructor;
*
The ForkJoinTask class is not usually directly subclassed.
* Instead, you subclass one of the abstract classes that support a
* particular style of fork/join processing, typically {@link
- * RecursiveAction} for computations that do not return results, or
- * {@link RecursiveTask} for those that do. Normally, a concrete
- * ForkJoinTask subclass declares fields comprising its parameters,
- * established in a constructor, and then defines a {@code compute}
- * method that somehow uses the control methods supplied by this base
- * class. While these methods have {@code public} access (to allow
- * instances of different task subclasses to call each other's
- * methods), some of them may only be called from within other
- * ForkJoinTasks (as may be determined using method {@link
- * #inForkJoinPool}). Attempts to invoke them in other contexts
- * result in exceptions or errors, possibly including
- * {@code ClassCastException}.
+ * RecursiveAction} for most computations that do not return results,
+ * {@link RecursiveTask} for those that do, and {@link
+ * CountedCompleter} for those in which completed actions trigger
+ * other actions. Normally, a concrete ForkJoinTask subclass declares
+ * fields comprising its parameters, established in a constructor, and
+ * then defines a {@code compute} method that somehow uses the control
+ * methods supplied by this base class. While these methods have
+ * {@code public} access (to allow instances of different task
+ * subclasses to call each other's methods), some of them may only be
+ * called from within other ForkJoinTasks (as may be determined using
+ * method {@link #inForkJoinPool}). Attempts to invoke them in other
+ * contexts result in exceptions or errors, possibly including {@code
+ * ClassCastException}.
*
*
Method {@link #join} and its variants are appropriate for use
* only when completion dependencies are acyclic; that is, the
@@ -269,14 +271,15 @@ public abstract class ForkJoinTask im
}
/**
- * Tries to set SIGNAL status. Used by ForkJoinPool. Other
- * variants are directly incorporated into externalAwaitDone etc.
+ * Tries to set SIGNAL status unless already completed. Used by
+ * ForkJoinPool. Other variants are directly incorporated into
+ * externalAwaitDone etc.
*
* @return true if successful
*/
final boolean trySetSignal() {
- int s;
- return U.compareAndSwapInt(this, STATUS, s = status, s | SIGNAL);
+ int s = status;
+ return s >= 0 && U.compareAndSwapInt(this, STATUS, s, s | SIGNAL);
}
/**
@@ -414,25 +417,39 @@ public abstract class ForkJoinTask im
* @return status on exit
*/
private int setExceptionalCompletion(Throwable ex) {
- int h = System.identityHashCode(this);
- final ReentrantLock lock = exceptionTableLock;
- lock.lock();
- try {
- expungeStaleExceptions();
- ExceptionNode[] t = exceptionTable;
- int i = h & (t.length - 1);
- for (ExceptionNode e = t[i]; ; e = e.next) {
- if (e == null) {
- t[i] = new ExceptionNode(this, ex, t[i]);
- break;
+ int s;
+ if ((s = status) >= 0) {
+ int h = System.identityHashCode(this);
+ final ReentrantLock lock = exceptionTableLock;
+ lock.lock();
+ try {
+ expungeStaleExceptions();
+ ExceptionNode[] t = exceptionTable;
+ int i = h & (t.length - 1);
+ for (ExceptionNode e = t[i]; ; e = e.next) {
+ if (e == null) {
+ t[i] = new ExceptionNode(this, ex, t[i]);
+ break;
+ }
+ if (e.get() == this) // already present
+ break;
}
- if (e.get() == this) // already present
- break;
+ } finally {
+ lock.unlock();
}
- } finally {
- lock.unlock();
+ s = setCompletion(EXCEPTIONAL);
}
- return setCompletion(EXCEPTIONAL);
+ ForkJoinTask> p = internalGetCompleter(); // propagate
+ if (p != null && p.status >= 0)
+ p.setExceptionalCompletion(ex);
+ return s;
+ }
+
+ /**
+ * Exception propagation support for tasks with completers.
+ */
+ ForkJoinTask> internalGetCompleter() {
+ return null;
}
/**
@@ -514,7 +531,7 @@ public abstract class ForkJoinTask im
Throwable ex;
if (e == null || (ex = e.ex) == null)
return null;
- if (e.thrower != Thread.currentThread().getId()) {
+ if (false && e.thrower != Thread.currentThread().getId()) {
Class extends Throwable> ec = ex.getClass();
try {
Constructor> noArgCtor = null;
@@ -904,12 +921,12 @@ public abstract class ForkJoinTask im
}
/**
- * Completes this task. The most recent value established by
- * {@link #setRawResult} (or {@code null}) will be returned as the
- * result of subsequent invocations of {@code join} and related
- * operations. This method may be useful when processing sets of
- * tasks when some do not otherwise complete normally. Its use in
- * other situations is discouraged.
+ * Completes this task normally without setting a value. The most
+ * recent value established by {@link #setRawResult} (or {@code
+ * null} by default) will be returned as the result of subsequent
+ * invocations of {@code join} and related operations.
+ *
+ * @since 1.8
*/
public final void quietlyComplete() {
setCompletion(NORMAL);
@@ -1234,15 +1251,18 @@ public abstract class ForkJoinTask im
protected abstract void setRawResult(V value);
/**
- * Immediately performs the base action of this task. This method
- * is designed to support extensions, and should not in general be
- * called otherwise. The return value controls whether this task
- * is considered to be done normally. It may return false in
+ * Immediately performs the base action of this task and returns
+ * true if, upon return from this method, this task is guaranteed
+ * to have completed normally. This method may return false
+ * otherwise, to indicate that this task is not necessarily
+ * complete (or is not known to be complete), for example in
* asynchronous actions that require explicit invocations of
- * {@link #complete} to become joinable. It may also throw an
- * (unchecked) exception to indicate abnormal exit.
+ * completion methods. This method may also throw an (unchecked)
+ * exception to indicate abnormal exit. This method is designed to
+ * support extensions, and should not in general be called
+ * otherwise.
*
- * @return {@code true} if completed normally
+ * @return {@code true} if this task is known to have completed normally
*/
protected abstract boolean exec();