--- jsr166/src/jsr166y/ForkJoinTask.java 2009/07/22 01:36:51 1.12
+++ jsr166/src/jsr166y/ForkJoinTask.java 2009/08/01 21:17:11 1.26
@@ -5,16 +5,19 @@
*/
package jsr166y;
-import java.io.Serializable;
-import java.util.*;
+
import java.util.concurrent.*;
-import java.util.concurrent.atomic.*;
-import sun.misc.Unsafe;
-import java.lang.reflect.*;
+
+import java.io.Serializable;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.WeakHashMap;
/**
- * Abstract base class for tasks that run within a {@link
- * ForkJoinPool}. A ForkJoinTask is a thread-like entity that is much
+ * Abstract base class for tasks that run within a {@link ForkJoinPool}.
+ * A {@code ForkJoinTask} is a thread-like entity that is much
* lighter weight than a normal thread. Huge numbers of tasks and
* subtasks may be hosted by a small number of actual threads in a
* ForkJoinPool, at the price of some usage limitations.
@@ -22,12 +25,11 @@ import java.lang.reflect.*;
*
A "main" ForkJoinTask begins execution when submitted to a
* {@link ForkJoinPool}. Once started, it will usually in turn start
* other subtasks. As indicated by the name of this class, many
- * programs using ForkJoinTasks employ only methods {@code fork}
- * and {@code join}, or derivatives such as
- * {@code invokeAll}. However, this class also provides a number
- * of other methods that can come into play in advanced usages, as
- * well as extension mechanics that allow support of new forms of
- * fork/join processing.
+ * programs using ForkJoinTasks employ only methods {@code fork} and
+ * {@code join}, or derivatives such as {@code invokeAll}. However,
+ * this class also provides a number of other methods that can come
+ * into play in advanced usages, as well as extension mechanics that
+ * allow support of new forms of fork/join processing.
*
*
A ForkJoinTask is a lightweight form of {@link Future}. The
* efficiency of ForkJoinTasks stems from a set of restrictions (that
@@ -81,16 +83,18 @@ import java.lang.reflect.*;
* class. While these methods have {@code public} access (to allow
* instances of different task subclasses to call each others
* methods), some of them may only be called from within other
- * ForkJoinTasks. Attempts to invoke them in other contexts result in
- * exceptions or errors possibly including ClassCastException.
+ * ForkJoinTasks (as may be determined using method {@link
+ * #inForkJoinPool}). Attempts to invoke them in other contexts
+ * result in exceptions or errors, possibly including
+ * ClassCastException.
*
*
Most base support methods are {@code final} because their
* implementations are intrinsically tied to the underlying
* lightweight task scheduling framework, and so cannot be overridden.
* Developers creating new basic styles of fork/join processing should
* minimally implement {@code protected} methods
- * {@code exec}, {@code setRawResult}, and
- * {@code getRawResult}, while also introducing an abstract
+ * {@link #exec}, {@link #setRawResult}, and
+ * {@link #getRawResult}, while also introducing an abstract
* computational method that can be implemented in its subclasses,
* possibly relying on other {@code protected} methods provided
* by this class.
@@ -160,8 +164,8 @@ public abstract class ForkJoinTask im
*/
static ForkJoinWorkerThread getWorker() {
Thread t = Thread.currentThread();
- return ((t instanceof ForkJoinWorkerThread)?
- (ForkJoinWorkerThread)t : null);
+ return ((t instanceof ForkJoinWorkerThread) ?
+ (ForkJoinWorkerThread) t : null);
}
final boolean casStatus(int cmp, int val) {
@@ -187,12 +191,12 @@ public abstract class ForkJoinTask im
ForkJoinPool pool = getPool();
if (pool != null) {
int s; // Clear signal bits while setting completion status
- do;while ((s = status) >= 0 && !casStatus(s, completion));
+ do {} while ((s = status) >= 0 && !casStatus(s, completion));
if ((s & SIGNAL_MASK) != 0) {
if ((s &= INTERNAL_SIGNAL_MASK) != 0)
pool.updateRunningCount(s);
- synchronized(this) { notifyAll(); }
+ synchronized (this) { notifyAll(); }
}
}
else
@@ -205,13 +209,13 @@ public abstract class ForkJoinTask im
*/
private void externallySetCompletion(int completion) {
int s;
- do;while ((s = status) >= 0 &&
- !casStatus(s, (s & SIGNAL_MASK) | completion));
- synchronized(this) { notifyAll(); }
+ do {} while ((s = status) >= 0 &&
+ !casStatus(s, (s & SIGNAL_MASK) | completion));
+ synchronized (this) { notifyAll(); }
}
/**
- * Sets status to indicate normal completion
+ * Sets status to indicate normal completion.
*/
final void setNormalCompletion() {
// Try typical fast case -- single CAS, no signal, not already done.
@@ -223,30 +227,30 @@ public abstract class ForkJoinTask im
// internal waiting and notification
/**
- * Performs the actual monitor wait for awaitDone
+ * Performs the actual monitor wait for awaitDone.
*/
private void doAwaitDone() {
// Minimize lock bias and in/de-flation effects by maximizing
// chances of waiting inside sync
try {
while (status >= 0)
- synchronized(this) { if (status >= 0) wait(); }
+ synchronized (this) { if (status >= 0) wait(); }
} catch (InterruptedException ie) {
onInterruptedWait();
}
}
/**
- * Performs the actual monitor wait for awaitDone
+ * Performs the actual timed monitor wait for awaitDone.
*/
private void doAwaitDone(long startTime, long nanos) {
- synchronized(this) {
+ synchronized (this) {
try {
while (status >= 0) {
- long nt = nanos - System.nanoTime() - startTime;
+ long nt = nanos - (System.nanoTime() - startTime);
if (nt <= 0)
break;
- wait(nt / 1000000, (int)(nt % 1000000));
+ wait(nt / 1000000, (int) (nt % 1000000));
}
} catch (InterruptedException ie) {
onInterruptedWait();
@@ -262,11 +266,12 @@ public abstract class ForkJoinTask im
*
* @return status upon exit
*/
- private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
- ForkJoinPool pool = w == null? null : w.pool;
+ private int awaitDone(ForkJoinWorkerThread w,
+ boolean maintainParallelism) {
+ ForkJoinPool pool = (w == null) ? null : w.pool;
int s;
while ((s = status) >= 0) {
- if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
+ if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
if (pool == null || !pool.preJoin(this, maintainParallelism))
doAwaitDone();
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
@@ -279,13 +284,14 @@ public abstract class ForkJoinTask im
/**
* Timed version of awaitDone
+ *
* @return status upon exit
*/
private int awaitDone(ForkJoinWorkerThread w, long nanos) {
- ForkJoinPool pool = w == null? null : w.pool;
+ ForkJoinPool pool = (w == null) ? null : w.pool;
int s;
while ((s = status) >= 0) {
- if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
+ if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
long startTime = System.nanoTime();
if (pool == null || !pool.preJoin(this, false))
doAwaitDone(startTime, nanos);
@@ -307,7 +313,7 @@ public abstract class ForkJoinTask im
*/
private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
int s;
- do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
+ do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
pool.updateRunningCount(s);
}
@@ -362,7 +368,7 @@ public abstract class ForkJoinTask im
/**
* Returns result or throws exception using j.u.c.Future conventions.
- * Only call when isDone known to be true.
+ * Only call when {@code isDone} known to be true.
*/
private V reportFutureResult()
throws ExecutionException, InterruptedException {
@@ -428,7 +434,7 @@ public abstract class ForkJoinTask im
try {
if (!exec())
return;
- } catch(Throwable rex) {
+ } catch (Throwable rex) {
setDoneExceptionally(rex);
return;
}
@@ -460,7 +466,7 @@ public abstract class ForkJoinTask im
final void cancelIgnoringExceptions() {
try {
cancel(false);
- } catch(Throwable ignore) {
+ } catch (Throwable ignore) {
}
}
@@ -472,7 +478,7 @@ public abstract class ForkJoinTask im
ForkJoinTask> t;
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
t.quietlyExec();
- return (s >= 0)? awaitDone(w, false) : s; // block if no work
+ return (s >= 0) ? awaitDone(w, false) : s; // block if no work
}
// public methods
@@ -482,11 +488,16 @@ public abstract class ForkJoinTask im
* necessarily enforced, it is a usage error to fork a task more
* than once unless it has completed and been reinitialized. This
* method may be invoked only from within ForkJoinTask
- * computations. Attempts to invoke in other contexts result in
- * exceptions or errors possibly including ClassCastException.
- */
- public final void fork() {
- ((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
+ * computations (as may be determined using method {@link
+ * #inForkJoinPool}). Attempts to invoke in other contexts result
+ * in exceptions or errors, possibly including ClassCastException.
+ *
+ * @return {@code this}, to simplify usage.
+ */
+ public final ForkJoinTask fork() {
+ ((ForkJoinWorkerThread) Thread.currentThread())
+ .pushTask(this);
+ return this;
}
/**
@@ -522,8 +533,9 @@ public abstract class ForkJoinTask im
/**
* Forks both tasks, returning when {@code isDone} holds for
* both of them or an exception is encountered. This method may be
- * invoked only from within ForkJoinTask computations. Attempts to
- * invoke in other contexts result in exceptions or errors
+ * invoked only from within ForkJoinTask computations (as may be
+ * determined using method {@link #inForkJoinPool}). Attempts to
+ * invoke in other contexts result in exceptions or errors,
* possibly including ClassCastException.
*
* @param t1 one task
@@ -541,8 +553,10 @@ public abstract class ForkJoinTask im
* Forks the given tasks, returning when {@code isDone} holds
* for all of them. If any task encounters an exception, others
* may be cancelled. This method may be invoked only from within
- * ForkJoinTask computations. Attempts to invoke in other contexts
- * result in exceptions or errors possibly including ClassCastException.
+ * ForkJoinTask computations (as may be determined using method
+ * {@link #inForkJoinPool}). Attempts to invoke in other contexts
+ * result in exceptions or errors, possibly including
+ * ClassCastException.
*
* @param tasks the array of tasks
* @throws NullPointerException if tasks or any element are null
@@ -585,21 +599,24 @@ public abstract class ForkJoinTask im
* Forks all tasks in the collection, returning when
* {@code isDone} holds for all of them. If any task
* encounters an exception, others may be cancelled. This method
- * may be invoked only from within ForkJoinTask
- * computations. Attempts to invoke in other contexts result in
- * exceptions or errors possibly including ClassCastException.
+ * may be invoked only from within ForkJoinTask computations (as
+ * may be determined using method {@link
+ * #inForkJoinPool}). Attempts to invoke in other contexts result
+ * in exceptions or errors, possibly including ClassCastException.
*
* @param tasks the collection of tasks
+ * @return the tasks argument, to simplify usage
* @throws NullPointerException if tasks or any element are null
* @throws RuntimeException or Error if any task did so
*/
- public static void invokeAll(Collection extends ForkJoinTask>> tasks) {
- if (!(tasks instanceof List)) {
- invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()]));
- return;
+ public static > Collection invokeAll(Collection tasks) {
+ if (!(tasks instanceof List>)) {
+ invokeAll(tasks.toArray(new ForkJoinTask>[tasks.size()]));
+ return tasks;
}
+ @SuppressWarnings("unchecked")
List extends ForkJoinTask>> ts =
- (List extends ForkJoinTask>>)tasks;
+ (List extends ForkJoinTask>>) tasks;
Throwable ex = null;
int last = ts.size() - 1;
for (int i = last; i >= 0; --i) {
@@ -630,22 +647,23 @@ public abstract class ForkJoinTask im
}
if (ex != null)
rethrowException(ex);
+ return tasks;
}
/**
- * Returns true if the computation performed by this task has
- * completed (or has been cancelled).
+ * Returns {@code true} if the computation performed by this task
+ * has completed (or has been cancelled).
*
- * @return true if this computation has completed
+ * @return {@code true} if this computation has completed
*/
public final boolean isDone() {
return status < 0;
}
/**
- * Returns true if this task was cancelled.
+ * Returns {@code true} if this task was cancelled.
*
- * @return true if this task was cancelled
+ * @return {@code true} if this task was cancelled
*/
public final boolean isCancelled() {
return (status & COMPLETION_MASK) == CANCELLED;
@@ -654,13 +672,13 @@ public abstract class ForkJoinTask im
/**
* Asserts that the results of this task's computation will not be
* used. If a cancellation occurs before attempting to execute this
- * task, then execution will be suppressed, {@code isCancelled}
- * will report true, and {@code join} will result in a
+ * task, execution will be suppressed, {@link #isCancelled}
+ * will report true, and {@link #join} will result in a
* {@code CancellationException} being thrown. Otherwise, when
* cancellation races with completion, there are no guarantees
- * about whether {@code isCancelled} will report true, whether
- * {@code join} will return normally or via an exception, or
- * whether these behaviors will remain consistent upon repeated
+ * about whether {@code isCancelled} will report {@code true},
+ * whether {@code join} will return normally or via an exception,
+ * or whether these behaviors will remain consistent upon repeated
* invocation.
*
* This method may be overridden in subclasses, but if so, must
@@ -670,13 +688,13 @@ 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 {@code completeExceptionally}.
+ * invoke {@link #completeExceptionally}.
*
* @param mayInterruptIfRunning this value is ignored in the
* default implementation because tasks are not in general
- * cancelled via interruption.
+ * cancelled via interruption
*
- * @return true if this task is now cancelled
+ * @return {@code true} if this task is now cancelled
*/
public boolean cancel(boolean mayInterruptIfRunning) {
setCompletion(CANCELLED);
@@ -684,9 +702,9 @@ public abstract class ForkJoinTask im
}
/**
- * Returns true if this task threw an exception or was cancelled.
+ * Returns {@code true} if this task threw an exception or was cancelled.
*
- * @return true if this task threw an exception or was cancelled
+ * @return {@code true} if this task threw an exception or was cancelled
*/
public final boolean isCompletedAbnormally() {
return (status & COMPLETION_MASK) < NORMAL;
@@ -697,7 +715,7 @@ public abstract class ForkJoinTask im
* CancellationException if cancelled, or null if none or if the
* method has not yet completed.
*
- * @return the exception, or null if none
+ * @return the exception, or {@code null} if none
*/
public final Throwable getException() {
int s = status & COMPLETION_MASK;
@@ -724,7 +742,7 @@ public abstract class ForkJoinTask im
*/
public void completeExceptionally(Throwable ex) {
setDoneExceptionally((ex instanceof RuntimeException) ||
- (ex instanceof Error)? ex :
+ (ex instanceof Error) ? ex :
new RuntimeException(ex));
}
@@ -743,7 +761,7 @@ public abstract class ForkJoinTask im
public void complete(V value) {
try {
setRawResult(value);
- } catch(Throwable rex) {
+ } catch (Throwable rex) {
setDoneExceptionally(rex);
return;
}
@@ -759,9 +777,10 @@ public abstract class ForkJoinTask im
public final V get(long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException {
+ long nanos = unit.toNanos(timeout);
ForkJoinWorkerThread w = getWorker();
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
- awaitDone(w, unit.toNanos(timeout));
+ awaitDone(w, nanos);
return reportTimedFutureResult();
}
@@ -773,13 +792,15 @@ public abstract class ForkJoinTask im
* current task and that of any other task that might be executed
* while helping. (This usually holds for pure divide-and-conquer
* tasks). This method may be invoked only from within
- * ForkJoinTask computations. Attempts to invoke in other contexts
- * result in exceptions or errors possibly including ClassCastException.
+ * ForkJoinTask computations (as may be determined using method
+ * {@link #inForkJoinPool}). Attempts to invoke in other contexts
+ * result in exceptions or errors, possibly including
+ * ClassCastException.
*
* @return the computed result
*/
public final V helpJoin() {
- ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
+ ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
if (status < 0 || !w.unpushTask(this) || !tryExec())
reportException(busyJoin(w));
return getRawResult();
@@ -788,13 +809,14 @@ public abstract class ForkJoinTask im
/**
* Possibly executes other tasks until this task is ready. This
* method may be invoked only from within ForkJoinTask
- * computations. Attempts to invoke in other contexts result in
- * exceptions or errors possibly including ClassCastException.
+ * computations (as may be determined using method {@link
+ * #inForkJoinPool}). Attempts to invoke in other contexts result
+ * in exceptions or errors, possibly including ClassCastException.
*/
public final void quietlyHelpJoin() {
if (status >= 0) {
ForkJoinWorkerThread w =
- (ForkJoinWorkerThread)(Thread.currentThread());
+ (ForkJoinWorkerThread) Thread.currentThread();
if (!w.unpushTask(this) || !tryQuietlyInvoke())
busyJoin(w);
}
@@ -833,8 +855,8 @@ public abstract class ForkJoinTask im
* joined, instead executing them until all are processed.
*/
public static void helpQuiesce() {
- ((ForkJoinWorkerThread)(Thread.currentThread())).
- helpQuiescePool();
+ ((ForkJoinWorkerThread) Thread.currentThread())
+ .helpQuiescePool();
}
/**
@@ -855,14 +877,25 @@ public abstract class ForkJoinTask im
/**
* Returns the pool hosting the current task execution, or null
- * if this task is executing outside of any pool.
+ * if this task is executing outside of any ForkJoinPool.
*
- * @return the pool, or null if none
+ * @return the pool, or {@code null} if none
*/
public static ForkJoinPool getPool() {
Thread t = Thread.currentThread();
- return ((t instanceof ForkJoinWorkerThread)?
- ((ForkJoinWorkerThread)t).pool : null);
+ return (t instanceof ForkJoinWorkerThread) ?
+ ((ForkJoinWorkerThread) t).pool : null;
+ }
+
+ /**
+ * Returns {@code true} if the current thread is executing as a
+ * ForkJoinPool computation.
+ *
+ * @return {@code true} if the current thread is executing as a
+ * ForkJoinPool computation, or false otherwise
+ */
+ public static boolean inForkJoinPool() {
+ return Thread.currentThread() instanceof ForkJoinWorkerThread;
}
/**
@@ -872,13 +905,16 @@ public abstract class ForkJoinTask im
* another thread. This method may be useful when arranging
* alternative local processing of tasks that could have been, but
* were not, stolen. This method may be invoked only from within
- * ForkJoinTask computations. Attempts to invoke in other contexts
- * result in exceptions or errors possibly including ClassCastException.
+ * ForkJoinTask computations (as may be determined using method
+ * {@link #inForkJoinPool}). Attempts to invoke in other contexts
+ * result in exceptions or errors, possibly including
+ * ClassCastException.
*
- * @return true if unforked
+ * @return {@code true} if unforked
*/
public boolean tryUnfork() {
- return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
+ return ((ForkJoinWorkerThread) Thread.currentThread())
+ .unpushTask(this);
}
/**
@@ -890,8 +926,8 @@ public abstract class ForkJoinTask im
* @return the number of tasks
*/
public static int getQueuedTaskCount() {
- return ((ForkJoinWorkerThread)(Thread.currentThread())).
- getQueueSize();
+ return ((ForkJoinWorkerThread) Thread.currentThread())
+ .getQueueSize();
}
/**
@@ -907,20 +943,20 @@ public abstract class ForkJoinTask im
* @return the surplus number of tasks, which may be negative
*/
public static int getSurplusQueuedTaskCount() {
- return ((ForkJoinWorkerThread)(Thread.currentThread()))
+ return ((ForkJoinWorkerThread) Thread.currentThread())
.getEstimatedSurplusTaskCount();
}
// Extension methods
/**
- * Returns the result that would be returned by {@code join},
- * even if this task completed abnormally, or null if this task is
- * not known to have been completed. This method is designed to
- * aid debugging, as well as to support extensions. Its use in any
- * other context is discouraged.
+ * Returns the result that would be returned by {@link #join}, even
+ * if this task completed abnormally, or {@code null} if this task
+ * is not known to have been completed. This method is designed
+ * to aid debugging, as well as to support extensions. Its use in
+ * any other context is discouraged.
*
- * @return the result, or null if not completed
+ * @return the result, or {@code null} if not completed
*/
public abstract V getRawResult();
@@ -939,28 +975,33 @@ public abstract class ForkJoinTask im
* called otherwise. The return value controls whether this task
* is considered to be done normally. It may return false in
* asynchronous actions that require explicit invocations of
- * {@code complete} to become joinable. It may throw exceptions
+ * {@link #complete} to become joinable. It may throw exceptions
* to indicate abnormal exit.
*
- * @return true if completed normally
+ * @return {@code true} if completed normally
* @throws Error or RuntimeException if encountered during computation
*/
protected abstract boolean exec();
/**
- * Returns, but does not unschedule or execute, the task queued by
- * the current thread but not yet executed, if one is
+ * Returns, but does not unschedule or execute, a task queued by
+ * the current thread but not yet executed, if one is immediately
* available. There is no guarantee that this task will actually
- * be polled or executed next. This method is designed primarily
- * to support extensions, and is unlikely to be useful otherwise.
- * This method may be invoked only from within ForkJoinTask
- * computations. Attempts to invoke in other contexts result in
- * exceptions or errors possibly including ClassCastException.
+ * be polled or executed next. Conversely, this method may return
+ * null even if a task exists but cannot be accessed without
+ * contention with other threads. This method is designed
+ * primarily to support extensions, and is unlikely to be useful
+ * otherwise. This method may be invoked only from within
+ * ForkJoinTask computations (as may be determined using method
+ * {@link #inForkJoinPool}). Attempts to invoke in other contexts
+ * result in exceptions or errors, possibly including
+ * ClassCastException.
*
- * @return the next task, or null if none are available
+ * @return the next task, or {@code null} if none are available
*/
protected static ForkJoinTask> peekNextLocalTask() {
- return ((ForkJoinWorkerThread)(Thread.currentThread())).peekTask();
+ return ((ForkJoinWorkerThread) Thread.currentThread())
+ .peekTask();
}
/**
@@ -968,14 +1009,16 @@ public abstract class ForkJoinTask im
* queued by the current thread but not yet executed. This method
* is designed primarily to support extensions, and is unlikely to
* be useful otherwise. This method may be invoked only from
- * within ForkJoinTask computations. Attempts to invoke in other
- * contexts result in exceptions or errors possibly including
+ * within ForkJoinTask computations (as may be determined using
+ * method {@link #inForkJoinPool}). Attempts to invoke in other
+ * contexts result in exceptions or errors, possibly including
* ClassCastException.
*
- * @return the next task, or null if none are available
+ * @return the next task, or {@code null} if none are available
*/
protected static ForkJoinTask> pollNextLocalTask() {
- return ((ForkJoinWorkerThread)(Thread.currentThread())).pollLocalTask();
+ return ((ForkJoinWorkerThread) Thread.currentThread())
+ .pollLocalTask();
}
/**
@@ -987,15 +1030,109 @@ public abstract class ForkJoinTask im
* of the pool this task is operating in. This method is designed
* primarily to support extensions, and is unlikely to be useful
* otherwise. This method may be invoked only from within
- * ForkJoinTask computations. Attempts to invoke in other contexts
- * result in exceptions or errors possibly including
+ * ForkJoinTask computations (as may be determined using method
+ * {@link #inForkJoinPool}). Attempts to invoke in other contexts
+ * result in exceptions or errors, possibly including
* ClassCastException.
*
- * @return a task, or null if none are available
+ * @return a task, or {@code null} if none are available
*/
protected static ForkJoinTask> pollTask() {
- return ((ForkJoinWorkerThread)(Thread.currentThread())).
- pollTask();
+ return ((ForkJoinWorkerThread) Thread.currentThread())
+ .pollTask();
+ }
+
+ /**
+ * Adaptor for Runnables. This implements RunnableFuture
+ * to be compliant with AbstractExecutorService constraints
+ * when used in ForkJoinPool.
+ */
+ static final class AdaptedRunnable extends ForkJoinTask
+ implements RunnableFuture {
+ final Runnable runnable;
+ final T resultOnCompletion;
+ T result;
+ AdaptedRunnable(Runnable runnable, T result) {
+ if (runnable == null) throw new NullPointerException();
+ this.runnable = runnable;
+ this.resultOnCompletion = result;
+ }
+ public T getRawResult() { return result; }
+ public void setRawResult(T v) { result = v; }
+ public boolean exec() {
+ runnable.run();
+ result = resultOnCompletion;
+ return true;
+ }
+ public void run() { invoke(); }
+ private static final long serialVersionUID = 5232453952276885070L;
+ }
+
+ /**
+ * Adaptor for Callables
+ */
+ static final class AdaptedCallable extends ForkJoinTask
+ implements RunnableFuture {
+ final Callable callable;
+ T result;
+ AdaptedCallable(Callable callable) {
+ if (callable == null) throw new NullPointerException();
+ this.callable = callable;
+ }
+ public T getRawResult() { return result; }
+ public void setRawResult(T v) { result = v; }
+ public boolean exec() {
+ try {
+ result = callable.call();
+ return true;
+ } catch (Error err) {
+ throw err;
+ } catch (RuntimeException rex) {
+ throw rex;
+ } catch (Exception ex) {
+ throw new RuntimeException(ex);
+ }
+ }
+ public void run() { invoke(); }
+ private static final long serialVersionUID = 2838392045355241008L;
+ }
+
+ /**
+ * Returns a new ForkJoinTask that performs the {@code run}
+ * method of the given Runnable as its action, and returns a null
+ * result upon {@code join}.
+ *
+ * @param runnable the runnable action
+ * @return the task
+ */
+ public static ForkJoinTask adapt(Runnable runnable) {
+ return new AdaptedRunnable(runnable, null);
+ }
+
+ /**
+ * Returns a new ForkJoinTask that performs the {@code run}
+ * method of the given Runnable as its action, and returns the
+ * given result upon {@code join}.
+ *
+ * @param runnable the runnable action
+ * @param result the result upon completion
+ * @return the task
+ */
+ public static ForkJoinTask adapt(Runnable runnable, T result) {
+ return new AdaptedRunnable(runnable, result);
+ }
+
+ /**
+ * Returns a new ForkJoinTask that performs the {@code call}
+ * method of the given Callable as its action, and returns its
+ * result upon {@code join}, translating any checked
+ * exceptions encountered into {@code RuntimeException}.
+ *
+ * @param callable the callable action
+ * @return the task
+ */
+ public static ForkJoinTask adapt(Callable callable) {
+ return new AdaptedCallable(callable);
}
// Serialization support
@@ -1006,7 +1143,7 @@ public abstract class ForkJoinTask im
* Save the state to a stream.
*
* @serialData the current run status and the exception thrown
- * during execution, or null if none
+ * during execution, or {@code null} if none
* @param s the stream
*/
private void writeObject(java.io.ObjectOutputStream s)
@@ -1027,49 +1164,51 @@ public abstract class ForkJoinTask im
status |= EXTERNAL_SIGNAL; // conservatively set external signal
Object ex = s.readObject();
if (ex != null)
- setDoneExceptionally((Throwable)ex);
+ setDoneExceptionally((Throwable) ex);
}
- // Temporary Unsafe mechanics for preliminary release
- private static Unsafe getUnsafe() throws Throwable {
+ // Unsafe mechanics
+
+ private static final sun.misc.Unsafe UNSAFE = getUnsafe();
+ private static final long statusOffset =
+ objectFieldOffset("status", ForkJoinTask.class);
+
+ private static long objectFieldOffset(String field, Class> klazz) {
try {
- return Unsafe.getUnsafe();
+ return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
+ } catch (NoSuchFieldException e) {
+ // Convert Exception to corresponding Error
+ NoSuchFieldError error = new NoSuchFieldError(field);
+ error.initCause(e);
+ throw error;
+ }
+ }
+
+ /**
+ * Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package.
+ * Replace with a simple call to Unsafe.getUnsafe when integrating
+ * into a jdk.
+ *
+ * @return a sun.misc.Unsafe
+ */
+ private static sun.misc.Unsafe getUnsafe() {
+ try {
+ return sun.misc.Unsafe.getUnsafe();
} catch (SecurityException se) {
try {
return java.security.AccessController.doPrivileged
- (new java.security.PrivilegedExceptionAction() {
- public Unsafe run() throws Exception {
- return getUnsafePrivileged();
+ (new java.security
+ .PrivilegedExceptionAction() {
+ public sun.misc.Unsafe run() throws Exception {
+ java.lang.reflect.Field f = sun.misc
+ .Unsafe.class.getDeclaredField("theUnsafe");
+ f.setAccessible(true);
+ return (sun.misc.Unsafe) f.get(null);
}});
} catch (java.security.PrivilegedActionException e) {
- throw e.getCause();
+ throw new RuntimeException("Could not initialize intrinsics",
+ e.getCause());
}
}
}
-
- private static Unsafe getUnsafePrivileged()
- throws NoSuchFieldException, IllegalAccessException {
- Field f = Unsafe.class.getDeclaredField("theUnsafe");
- f.setAccessible(true);
- return (Unsafe) f.get(null);
- }
-
- private static long fieldOffset(String fieldName)
- throws NoSuchFieldException {
- return UNSAFE.objectFieldOffset
- (ForkJoinTask.class.getDeclaredField(fieldName));
- }
-
- static final Unsafe UNSAFE;
- static final long statusOffset;
-
- static {
- try {
- UNSAFE = getUnsafe();
- statusOffset = fieldOffset("status");
- } catch (Throwable e) {
- throw new RuntimeException("Could not initialize intrinsics", e);
- }
- }
-
}