--- jsr166/src/jsr166y/ForkJoinTask.java 2009/07/22 19:04:11 1.13 +++ jsr166/src/jsr166y/ForkJoinTask.java 2009/07/27 21:41:53 1.24 @@ -5,12 +5,15 @@ */ 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 @@ -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 @@ -83,7 +85,7 @@ import java.lang.reflect.*; * 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 + * result in exceptions or errors, possibly including * ClassCastException. * *

Most base support methods are {@code final} because their @@ -91,8 +93,8 @@ import java.lang.reflect.*; * 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. @@ -162,8 +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) { @@ -189,12 +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 @@ -207,13 +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. @@ -225,30 +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; if (nt <= 0) break; - wait(nt / 1000000, (int)(nt % 1000000)); + wait(nt / 1000000, (int) (nt % 1000000)); } } catch (InterruptedException ie) { onInterruptedWait(); @@ -264,11 +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) @@ -281,13 +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); @@ -309,7 +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); } @@ -364,7 +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 { @@ -430,7 +434,7 @@ public abstract class ForkJoinTask im try { if (!exec()) return; - } catch(Throwable rex) { + } catch (Throwable rex) { setDoneExceptionally(rex); return; } @@ -462,7 +466,7 @@ public abstract class ForkJoinTask im final void cancelIgnoringExceptions() { try { cancel(false); - } catch(Throwable ignore) { + } catch (Throwable ignore) { } } @@ -474,7 +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 @@ -486,10 +490,14 @@ public abstract class ForkJoinTask im * 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. + * in exceptions or errors, possibly including ClassCastException. + * + * @return {@code this}, to simplify usage. */ - public final void fork() { - ((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this); + public final ForkJoinTask fork() { + ((ForkJoinWorkerThread) Thread.currentThread()) + .pushTask(this); + return this; } /** @@ -527,7 +535,7 @@ public abstract class ForkJoinTask im * both of them or an exception is encountered. 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 + * invoke in other contexts result in exceptions or errors, * possibly including ClassCastException. * * @param t1 one task @@ -547,8 +555,9 @@ public abstract class ForkJoinTask im * may be cancelled. 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 + * result in exceptions or errors, possibly including * ClassCastException. + * * @param tasks the array of tasks * @throws NullPointerException if tasks or any element are null * @throws RuntimeException or Error if any task did so @@ -592,20 +601,22 @@ public abstract class ForkJoinTask im * encounters an exception, others may be cancelled. This method * may be invoked only from within ForkJoinTask computations (as * may be determined using method {@link - * #inForkJoinPool}). Attempts to invoke in other contexts resul!t - * in exceptions or errors possibly including ClassCastException. + * #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> 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> ts = - (List>)tasks; + (List>) tasks; Throwable ex = null; int last = ts.size() - 1; for (int i = last; i >= 0; --i) { @@ -636,22 +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; @@ -660,13 +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 @@ -676,13 +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); @@ -690,9 +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; @@ -703,7 +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; @@ -730,7 +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)); } @@ -749,7 +761,7 @@ public abstract class ForkJoinTask im public void complete(V value) { try { setRawResult(value); - } catch(Throwable rex) { + } catch (Throwable rex) { setDoneExceptionally(rex); return; } @@ -781,13 +793,13 @@ public abstract class ForkJoinTask im * tasks). This method may be invoked only from within * ForkJoinTask computations (as may be determined using method * {@link #inForkJoinPool}). Attempts to invoke in other contexts - * resul!t in exceptions or errors possibly including + * 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(); @@ -797,13 +809,13 @@ public abstract class ForkJoinTask im * Possibly executes other tasks until this task is ready. This * method may be invoked only from within ForkJoinTask * computations (as may be determined using method {@link - * #inForkJoinPool}). Attempts to invoke in other contexts resul!t - * in exceptions or errors possibly including ClassCastException. + * #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); } @@ -842,8 +854,8 @@ 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(); } /** @@ -866,18 +878,19 @@ public abstract class ForkJoinTask im * Returns the pool hosting the current task execution, or null * 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 true if the current thread is executing as a + * Returns {@code true} if the current thread is executing as a * ForkJoinPool computation. - * @return true if the current thread is executing as a + * + * @return {@code true} if the current thread is executing as a * ForkJoinPool computation, or false otherwise */ public static boolean inForkJoinPool() { @@ -893,13 +906,14 @@ public abstract class ForkJoinTask im * were not, stolen. 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 + * 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); } /** @@ -911,8 +925,8 @@ public abstract class ForkJoinTask im * @return the number of tasks */ public static int getQueuedTaskCount() { - return ((ForkJoinWorkerThread)(Thread.currentThread())). - getQueueSize(); + return ((ForkJoinWorkerThread) Thread.currentThread()) + .getQueueSize(); } /** @@ -928,20 +942,20 @@ 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(); @@ -960,10 +974,10 @@ 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(); @@ -977,12 +991,13 @@ public abstract class ForkJoinTask im * 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. + * 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(); } /** @@ -992,13 +1007,14 @@ public abstract class ForkJoinTask im * 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 + * 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(); } /** @@ -1012,14 +1028,54 @@ public abstract class ForkJoinTask im * 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 + * 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(); + } + + // adaptors + + /** + * 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 ForkJoinPool.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 ForkJoinPool.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 ForkJoinPool.AdaptedCallable(callable); } // Serialization support @@ -1030,7 +1086,7 @@ 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) @@ -1051,49 +1107,51 @@ 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); + } + + // 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.objectFieldOffset(klazz.getDeclaredField(field)); + } catch (NoSuchFieldException e) { + // Convert Exception to corresponding Error + NoSuchFieldError error = new NoSuchFieldError(field); + error.initCause(e); + throw error; + } } - // Temporary Unsafe mechanics for preliminary release - private static Unsafe getUnsafe() throws Throwable { + /** + * 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 Unsafe.getUnsafe(); + 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); - } - } - }