--- jsr166/src/jsr166e/ForkJoinTask.java 2013/02/05 17:09:54 1.12
+++ jsr166/src/jsr166e/ForkJoinTask.java 2016/06/30 14:17:04 1.19
@@ -71,7 +71,7 @@ import java.lang.reflect.Constructor;
* encountering the exception; minimally only the latter.
*
*
It is possible to define and use ForkJoinTasks that may block,
- * but doing do requires three further considerations: (1) Completion
+ * but doing so requires three further considerations: (1) Completion
* of few if any other tasks should be dependent on a task
* that blocks on external synchronization or I/O. Event-style async
* tasks that are never joined (for example, those subclassing {@link
@@ -134,10 +134,9 @@ import java.lang.reflect.Constructor;
* (DAG). Otherwise, executions may encounter a form of deadlock as
* tasks cyclically wait for each other. However, this framework
* supports other methods and techniques (for example the use of
- * {@link java.util.concurrent.Phaser}, {@link #helpQuiesce}, and
- * {@link #complete}) that
+ * {@link java.util.concurrent.Phaser Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
* may be of use in constructing custom subclasses for problems that
- * are not statically structured as DAGs. To support such usages a
+ * are not statically structured as DAGs. To support such usages, a
* ForkJoinTask may be atomically tagged with a {@code short}
* value using {@link #setForkJoinTaskTag} or {@link
* #compareAndSetForkJoinTaskTag} and checked using {@link
@@ -286,25 +285,35 @@ public abstract class ForkJoinTask im
*/
private int externalAwaitDone() {
int s;
- ForkJoinPool.externalHelpJoin(this);
- boolean interrupted = false;
- while ((s = status) >= 0) {
- if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
- synchronized (this) {
- if (status >= 0) {
- try {
- wait();
- } catch (InterruptedException ie) {
- interrupted = true;
+ ForkJoinPool cp = ForkJoinPool.common;
+ if ((s = status) >= 0) {
+ if (cp != null) {
+ if (this instanceof CountedCompleter)
+ s = cp.externalHelpComplete((CountedCompleter>)this);
+ else if (cp.tryExternalUnpush(this))
+ s = doExec();
+ }
+ if (s >= 0 && (s = status) >= 0) {
+ boolean interrupted = false;
+ do {
+ if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
+ synchronized (this) {
+ if (status >= 0) {
+ try {
+ wait();
+ } catch (InterruptedException ie) {
+ interrupted = true;
+ }
+ }
+ else
+ notifyAll();
}
}
- else
- notifyAll();
- }
+ } while ((s = status) >= 0);
+ if (interrupted)
+ Thread.currentThread().interrupt();
}
}
- if (interrupted)
- Thread.currentThread().interrupt();
return s;
}
@@ -313,9 +322,15 @@ public abstract class ForkJoinTask im
*/
private int externalInterruptibleAwaitDone() throws InterruptedException {
int s;
+ ForkJoinPool cp = ForkJoinPool.common;
if (Thread.interrupted())
throw new InterruptedException();
- ForkJoinPool.externalHelpJoin(this);
+ if ((s = status) >= 0 && cp != null) {
+ if (this instanceof CountedCompleter)
+ cp.externalHelpComplete((CountedCompleter>)this);
+ else if (cp.tryExternalUnpush(this))
+ doExec();
+ }
while ((s = status) >= 0) {
if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
synchronized (this) {
@@ -396,11 +411,13 @@ public abstract class ForkJoinTask im
final Throwable ex;
ExceptionNode next;
final long thrower; // use id not ref to avoid weak cycles
+ final int hashCode; // store task hashCode before weak ref disappears
ExceptionNode(ForkJoinTask> task, Throwable ex, ExceptionNode next) {
super(task, exceptionTableRefQueue);
this.ex = ex;
this.next = next;
this.thrower = Thread.currentThread().getId();
+ this.hashCode = System.identityHashCode(task);
}
}
@@ -559,12 +576,15 @@ public abstract class ForkJoinTask im
/**
* Poll stale refs and remove them. Call only while holding lock.
*/
+ /**
+ * Poll stale refs and remove them. Call only while holding lock.
+ */
private static void expungeStaleExceptions() {
for (Object x; (x = exceptionTableRefQueue.poll()) != null;) {
if (x instanceof ExceptionNode) {
- ForkJoinTask> key = ((ExceptionNode)x).get();
+ int hashCode = ((ExceptionNode)x).hashCode;
ExceptionNode[] t = exceptionTable;
- int i = System.identityHashCode(key) & (t.length - 1);
+ int i = hashCode & (t.length - 1);
ExceptionNode e = t[i];
ExceptionNode pred = null;
while (e != null) {
@@ -601,14 +621,9 @@ public abstract class ForkJoinTask im
/**
* A version of "sneaky throw" to relay exceptions
*/
- static void rethrow(final Throwable ex) {
- if (ex != null) {
- if (ex instanceof Error)
- throw (Error)ex;
- if (ex instanceof RuntimeException)
- throw (RuntimeException)ex;
+ static void rethrow(Throwable ex) {
+ if (ex != null)
ForkJoinTask.uncheckedThrow(ex);
- }
}
/**
@@ -618,8 +633,7 @@ public abstract class ForkJoinTask im
*/
@SuppressWarnings("unchecked") static
void uncheckedThrow(Throwable t) throws T {
- if (t != null)
- throw (T)t; // rely on vacuous cast
+ throw (T)t; // rely on vacuous cast
}
/**
@@ -773,6 +787,7 @@ public abstract class ForkJoinTask im
* unprocessed.
*
* @param tasks the collection of tasks
+ * @param the type of the values returned from the tasks
* @return the tasks argument, to simplify usage
* @throws NullPointerException if tasks or any element are null
*/
@@ -830,7 +845,7 @@ public abstract class ForkJoinTask im
* This method is designed to be invoked by other
* tasks. To terminate the current task, you can just return or
* throw an unchecked exception from its computation method, or
- * invoke {@link #completeExceptionally}.
+ * invoke {@link #completeExceptionally(Throwable)}.
*
* @param mayInterruptIfRunning this value has no effect in the
* default implementation because interrupts are not used to
@@ -982,6 +997,7 @@ public abstract class ForkJoinTask im
// Messy in part because we measure in nanosecs, but wait in millisecs
int s; long ms;
long ns = unit.toNanos(timeout);
+ ForkJoinPool cp;
if ((s = status) >= 0 && ns > 0L) {
long deadline = System.nanoTime() + ns;
ForkJoinPool p = null;
@@ -993,8 +1009,12 @@ public abstract class ForkJoinTask im
w = wt.workQueue;
p.helpJoinOnce(w, this); // no retries on failure
}
- else
- ForkJoinPool.externalHelpJoin(this);
+ else if ((cp = ForkJoinPool.common) != null) {
+ if (this instanceof CountedCompleter)
+ cp.externalHelpComplete((CountedCompleter>)this);
+ else if (cp.tryExternalUnpush(this))
+ doExec();
+ }
boolean canBlock = false;
boolean interrupted = false;
try {
@@ -1002,7 +1022,7 @@ public abstract class ForkJoinTask im
if (w != null && w.qlock < 0)
cancelIgnoringExceptions(this);
else if (!canBlock) {
- if (p == null || p.tryCompensate())
+ if (p == null || p.tryCompensate(p.ctl))
canBlock = true;
}
else {
@@ -1066,10 +1086,10 @@ public abstract class ForkJoinTask im
/**
* Possibly executes tasks until the pool hosting the current task
- * {@link ForkJoinPool#isQuiescent is quiescent}. This method may
- * be of use in designs in which many tasks are forked, but none
- * are explicitly joined, instead executing them until all are
- * processed.
+ * {@linkplain ForkJoinPool#isQuiescent is quiescent}. This
+ * method may be of use in designs in which many tasks are forked,
+ * but none are explicitly joined, instead executing them until
+ * all are processed.
*/
public static void helpQuiesce() {
Thread t;
@@ -1143,7 +1163,7 @@ public abstract class ForkJoinTask im
Thread t;
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ?
((ForkJoinWorkerThread)t).workQueue.tryUnpush(this) :
- ForkJoinPool.tryExternalUnpush(this));
+ ForkJoinPool.common.tryExternalUnpush(this));
}
/**
@@ -1312,7 +1332,7 @@ public abstract class ForkJoinTask im
*
* @param e the expected tag value
* @param tag the new tag value
- * @return true if successful; i.e., the current value was
+ * @return {@code true} if successful; i.e., the current value was
* equal to e and is now tag.
* @since 1.8
*/
@@ -1327,7 +1347,7 @@ public abstract class ForkJoinTask im
}
/**
- * Adaptor for Runnables. This implements RunnableFuture
+ * Adapter for Runnables. This implements RunnableFuture
* to be compliant with AbstractExecutorService constraints
* when used in ForkJoinPool.
*/
@@ -1348,7 +1368,7 @@ public abstract class ForkJoinTask im
}
/**
- * Adaptor for Runnables without results
+ * Adapter for Runnables without results
*/
static final class AdaptedRunnableAction extends ForkJoinTask
implements RunnableFuture {
@@ -1365,7 +1385,25 @@ public abstract class ForkJoinTask im
}
/**
- * Adaptor for Callables
+ * Adapter for Runnables in which failure forces worker exception
+ */
+ static final class RunnableExecuteAction extends ForkJoinTask {
+ final Runnable runnable;
+ RunnableExecuteAction(Runnable runnable) {
+ if (runnable == null) throw new NullPointerException();
+ this.runnable = runnable;
+ }
+ public final Void getRawResult() { return null; }
+ public final void setRawResult(Void v) { }
+ public final boolean exec() { runnable.run(); return true; }
+ void internalPropagateException(Throwable ex) {
+ rethrow(ex); // rethrow outside exec() catches.
+ }
+ private static final long serialVersionUID = 5232453952276885070L;
+ }
+
+ /**
+ * Adapter for Callables
*/
static final class AdaptedCallable extends ForkJoinTask
implements RunnableFuture {
@@ -1412,6 +1450,7 @@ public abstract class ForkJoinTask im
*
* @param runnable the runnable action
* @param result the result upon completion
+ * @param the type of the result
* @return the task
*/
public static ForkJoinTask adapt(Runnable runnable, T result) {
@@ -1425,6 +1464,7 @@ public abstract class ForkJoinTask im
* encountered into {@code RuntimeException}.
*
* @param callable the callable action
+ * @param the type of the callable's result
* @return the task
*/
public static ForkJoinTask adapt(Callable extends T> callable) {
@@ -1438,6 +1478,8 @@ public abstract class ForkJoinTask im
/**
* Saves this task to a stream (that is, serializes it).
*
+ * @param s the stream
+ * @throws java.io.IOException if an I/O error occurs
* @serialData the current run status and the exception thrown
* during execution, or {@code null} if none
*/
@@ -1449,6 +1491,10 @@ public abstract class ForkJoinTask im
/**
* Reconstitutes this task from a stream (that is, deserializes it).
+ * @param s the stream
+ * @throws ClassNotFoundException if the class of a serialized object
+ * could not be found
+ * @throws java.io.IOException if an I/O error occurs
*/
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {