| 5 |
|
*/ |
| 6 |
|
|
| 7 |
|
package jsr166y; |
| 8 |
< |
import java.util.*; |
| 8 |
> |
|
| 9 |
|
import java.util.concurrent.*; |
| 10 |
< |
import java.util.concurrent.locks.*; |
| 11 |
< |
import java.util.concurrent.atomic.*; |
| 12 |
< |
import sun.misc.Unsafe; |
| 13 |
< |
import java.lang.reflect.*; |
| 10 |
> |
|
| 11 |
> |
import java.util.ArrayList; |
| 12 |
> |
import java.util.Arrays; |
| 13 |
> |
import java.util.Collection; |
| 14 |
> |
import java.util.Collections; |
| 15 |
> |
import java.util.List; |
| 16 |
> |
import java.util.concurrent.locks.Condition; |
| 17 |
> |
import java.util.concurrent.locks.LockSupport; |
| 18 |
> |
import java.util.concurrent.locks.ReentrantLock; |
| 19 |
> |
import java.util.concurrent.atomic.AtomicInteger; |
| 20 |
> |
import java.util.concurrent.atomic.AtomicLong; |
| 21 |
|
|
| 22 |
|
/** |
| 23 |
< |
* An {@link ExecutorService} for running {@link ForkJoinTask}s. A |
| 24 |
< |
* ForkJoinPool provides the entry point for submissions from |
| 23 |
> |
* An {@link ExecutorService} for running {@link ForkJoinTask}s. |
| 24 |
> |
* A ForkJoinPool provides the entry point for submissions from |
| 25 |
|
* non-ForkJoinTasks, as well as management and monitoring operations. |
| 26 |
|
* Normally a single ForkJoinPool is used for a large number of |
| 27 |
|
* submitted tasks. Otherwise, use would not usually outweigh the |
| 34 |
|
* (eventually blocking if none exist). This makes them efficient when |
| 35 |
|
* most tasks spawn other subtasks (as do most ForkJoinTasks), as well |
| 36 |
|
* as the mixed execution of some plain Runnable- or Callable- based |
| 37 |
< |
* activities along with ForkJoinTasks. When setting |
| 38 |
< |
* {@code setAsyncMode}, a ForkJoinPools may also be appropriate for |
| 39 |
< |
* use with fine-grained tasks that are never joined. Otherwise, other |
| 40 |
< |
* ExecutorService implementations are typically more appropriate |
| 41 |
< |
* choices. |
| 37 |
> |
* activities along with ForkJoinTasks. When setting {@linkplain |
| 38 |
> |
* #setAsyncMode async mode}, a ForkJoinPool may also be appropriate |
| 39 |
> |
* for use with fine-grained tasks that are never joined. Otherwise, |
| 40 |
> |
* other ExecutorService implementations are typically more |
| 41 |
> |
* appropriate choices. |
| 42 |
|
* |
| 43 |
|
* <p>A ForkJoinPool may be constructed with a given parallelism level |
| 44 |
|
* (target pool size), which it attempts to maintain by dynamically |
| 45 |
|
* adding, suspending, or resuming threads, even if some tasks are |
| 46 |
|
* waiting to join others. However, no such adjustments are performed |
| 47 |
|
* in the face of blocked IO or other unmanaged synchronization. The |
| 48 |
< |
* nested {@code ManagedBlocker} interface enables extension of |
| 48 |
> |
* nested {@link ManagedBlocker} interface enables extension of |
| 49 |
|
* the kinds of synchronization accommodated. The target parallelism |
| 50 |
< |
* level may also be changed dynamically ({@code setParallelism}) |
| 50 |
> |
* level may also be changed dynamically ({@link #setParallelism}) |
| 51 |
|
* and thread construction can be limited using methods |
| 52 |
< |
* {@code setMaximumPoolSize} and/or |
| 53 |
< |
* {@code setMaintainsParallelism}. |
| 52 |
> |
* {@link #setMaximumPoolSize} and/or |
| 53 |
> |
* {@link #setMaintainsParallelism}. |
| 54 |
|
* |
| 55 |
|
* <p>In addition to execution and lifecycle control methods, this |
| 56 |
|
* class provides status check methods (for example |
| 57 |
< |
* {@code getStealCount}) that are intended to aid in developing, |
| 57 |
> |
* {@link #getStealCount}) that are intended to aid in developing, |
| 58 |
|
* tuning, and monitoring fork/join applications. Also, method |
| 59 |
< |
* {@code toString} returns indications of pool state in a |
| 59 |
> |
* {@link #toString} returns indications of pool state in a |
| 60 |
|
* convenient form for informal monitoring. |
| 61 |
|
* |
| 62 |
|
* <p><b>Implementation notes</b>: This implementation restricts the |
| 81 |
|
private static final int MAX_THREADS = 0x7FFF; |
| 82 |
|
|
| 83 |
|
/** |
| 84 |
< |
* Factory for creating new ForkJoinWorkerThreads. A |
| 85 |
< |
* ForkJoinWorkerThreadFactory must be defined and used for |
| 86 |
< |
* ForkJoinWorkerThread subclasses that extend base functionality |
| 87 |
< |
* or initialize threads with different contexts. |
| 84 |
> |
* Factory for creating new {@link ForkJoinWorkerThread}s. |
| 85 |
> |
* A {@code ForkJoinWorkerThreadFactory} must be defined and used |
| 86 |
> |
* for {@code ForkJoinWorkerThread} subclasses that extend base |
| 87 |
> |
* functionality or initialize threads with different contexts. |
| 88 |
|
*/ |
| 89 |
|
public static interface ForkJoinWorkerThreadFactory { |
| 90 |
|
/** |
| 311 |
|
} |
| 312 |
|
|
| 313 |
|
/** |
| 314 |
< |
* Returns true if argument represents zero active count and |
| 315 |
< |
* nonzero runstate, which is the triggering condition for |
| 314 |
> |
* Returns {@code true} if argument represents zero active count |
| 315 |
> |
* and nonzero runstate, which is the triggering condition for |
| 316 |
|
* terminating on shutdown. |
| 317 |
|
*/ |
| 318 |
|
private static boolean canTerminateOnShutdown(int c) { |
| 548 |
|
* Common code for execute, invoke and submit |
| 549 |
|
*/ |
| 550 |
|
private <T> void doSubmit(ForkJoinTask<T> task) { |
| 551 |
+ |
if (task == null) |
| 552 |
+ |
throw new NullPointerException(); |
| 553 |
|
if (isShutdown()) |
| 554 |
|
throw new RejectedExecutionException(); |
| 555 |
|
if (workers == null) |
| 578 |
|
* @throws NullPointerException if task is null |
| 579 |
|
* @throws RejectedExecutionException if pool is shut down |
| 580 |
|
*/ |
| 581 |
< |
public <T> void execute(ForkJoinTask<T> task) { |
| 581 |
> |
public void execute(ForkJoinTask<?> task) { |
| 582 |
|
doSubmit(task); |
| 583 |
|
} |
| 584 |
|
|
| 585 |
|
// AbstractExecutorService methods |
| 586 |
|
|
| 587 |
|
public void execute(Runnable task) { |
| 588 |
< |
doSubmit(new AdaptedRunnable<Void>(task, null)); |
| 588 |
> |
ForkJoinTask<?> job; |
| 589 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
| 590 |
> |
job = (ForkJoinTask<?>) task; |
| 591 |
> |
else |
| 592 |
> |
job = ForkJoinTask.adapt(task, null); |
| 593 |
> |
doSubmit(job); |
| 594 |
|
} |
| 595 |
|
|
| 596 |
|
public <T> ForkJoinTask<T> submit(Callable<T> task) { |
| 597 |
< |
ForkJoinTask<T> job = new AdaptedCallable<T>(task); |
| 597 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task); |
| 598 |
|
doSubmit(job); |
| 599 |
|
return job; |
| 600 |
|
} |
| 601 |
|
|
| 602 |
|
public <T> ForkJoinTask<T> submit(Runnable task, T result) { |
| 603 |
< |
ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result); |
| 603 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task, result); |
| 604 |
|
doSubmit(job); |
| 605 |
|
return job; |
| 606 |
|
} |
| 607 |
|
|
| 608 |
|
public ForkJoinTask<?> submit(Runnable task) { |
| 609 |
< |
ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null); |
| 609 |
> |
ForkJoinTask<?> job; |
| 610 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
| 611 |
> |
job = (ForkJoinTask<?>) task; |
| 612 |
> |
else |
| 613 |
> |
job = ForkJoinTask.adapt(task, null); |
| 614 |
|
doSubmit(job); |
| 615 |
|
return job; |
| 616 |
|
} |
| 617 |
|
|
| 618 |
|
/** |
| 619 |
< |
* Adaptor for Runnables. This implements RunnableFuture |
| 620 |
< |
* to be compliant with AbstractExecutorService constraints. |
| 619 |
> |
* Submits a ForkJoinTask for execution. |
| 620 |
> |
* |
| 621 |
> |
* @param task the task to submit |
| 622 |
> |
* @return the task |
| 623 |
> |
* @throws RejectedExecutionException if the task cannot be |
| 624 |
> |
* scheduled for execution |
| 625 |
> |
* @throws NullPointerException if the task is null |
| 626 |
|
*/ |
| 627 |
< |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
| 628 |
< |
implements RunnableFuture<T> { |
| 629 |
< |
final Runnable runnable; |
| 607 |
< |
final T resultOnCompletion; |
| 608 |
< |
T result; |
| 609 |
< |
AdaptedRunnable(Runnable runnable, T result) { |
| 610 |
< |
if (runnable == null) throw new NullPointerException(); |
| 611 |
< |
this.runnable = runnable; |
| 612 |
< |
this.resultOnCompletion = result; |
| 613 |
< |
} |
| 614 |
< |
public T getRawResult() { return result; } |
| 615 |
< |
public void setRawResult(T v) { result = v; } |
| 616 |
< |
public boolean exec() { |
| 617 |
< |
runnable.run(); |
| 618 |
< |
result = resultOnCompletion; |
| 619 |
< |
return true; |
| 620 |
< |
} |
| 621 |
< |
public void run() { invoke(); } |
| 622 |
< |
private static final long serialVersionUID = 5232453952276885070L; |
| 627 |
> |
public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) { |
| 628 |
> |
doSubmit(task); |
| 629 |
> |
return task; |
| 630 |
|
} |
| 631 |
|
|
| 625 |
– |
/** |
| 626 |
– |
* Adaptor for Callables |
| 627 |
– |
*/ |
| 628 |
– |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
| 629 |
– |
implements RunnableFuture<T> { |
| 630 |
– |
final Callable<T> callable; |
| 631 |
– |
T result; |
| 632 |
– |
AdaptedCallable(Callable<T> callable) { |
| 633 |
– |
if (callable == null) throw new NullPointerException(); |
| 634 |
– |
this.callable = callable; |
| 635 |
– |
} |
| 636 |
– |
public T getRawResult() { return result; } |
| 637 |
– |
public void setRawResult(T v) { result = v; } |
| 638 |
– |
public boolean exec() { |
| 639 |
– |
try { |
| 640 |
– |
result = callable.call(); |
| 641 |
– |
return true; |
| 642 |
– |
} catch (Error err) { |
| 643 |
– |
throw err; |
| 644 |
– |
} catch (RuntimeException rex) { |
| 645 |
– |
throw rex; |
| 646 |
– |
} catch (Exception ex) { |
| 647 |
– |
throw new RuntimeException(ex); |
| 648 |
– |
} |
| 649 |
– |
} |
| 650 |
– |
public void run() { invoke(); } |
| 651 |
– |
private static final long serialVersionUID = 2838392045355241008L; |
| 652 |
– |
} |
| 632 |
|
|
| 633 |
|
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) { |
| 634 |
< |
ArrayList<ForkJoinTask<T>> ts = |
| 634 |
> |
ArrayList<ForkJoinTask<T>> forkJoinTasks = |
| 635 |
|
new ArrayList<ForkJoinTask<T>>(tasks.size()); |
| 636 |
< |
for (Callable<T> c : tasks) |
| 637 |
< |
ts.add(new AdaptedCallable<T>(c)); |
| 638 |
< |
invoke(new InvokeAll<T>(ts)); |
| 639 |
< |
return (List<Future<T>>) (List) ts; |
| 636 |
> |
for (Callable<T> task : tasks) |
| 637 |
> |
forkJoinTasks.add(ForkJoinTask.adapt(task)); |
| 638 |
> |
invoke(new InvokeAll<T>(forkJoinTasks)); |
| 639 |
> |
|
| 640 |
> |
@SuppressWarnings({"unchecked", "rawtypes"}) |
| 641 |
> |
List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks; |
| 642 |
> |
return futures; |
| 643 |
|
} |
| 644 |
|
|
| 645 |
|
static final class InvokeAll<T> extends RecursiveAction { |
| 667 |
|
* Returns the handler for internal worker threads that terminate |
| 668 |
|
* due to unrecoverable errors encountered while executing tasks. |
| 669 |
|
* |
| 670 |
< |
* @return the handler, or null if none |
| 670 |
> |
* @return the handler, or {@code null} if none |
| 671 |
|
*/ |
| 672 |
|
public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() { |
| 673 |
|
Thread.UncaughtExceptionHandler h; |
| 688 |
|
* as handler. |
| 689 |
|
* |
| 690 |
|
* @param h the new handler |
| 691 |
< |
* @return the old handler, or null if none |
| 691 |
> |
* @return the old handler, or {@code null} if none |
| 692 |
|
* @throws SecurityException if a security manager exists and |
| 693 |
|
* the caller is not permitted to modify threads |
| 694 |
|
* because it does not hold {@link |
| 762 |
|
/** |
| 763 |
|
* Returns the number of worker threads that have started but not |
| 764 |
|
* yet terminated. This result returned by this method may differ |
| 765 |
< |
* from {@code getParallelism} when threads are created to |
| 765 |
> |
* from {@link #getParallelism} when threads are created to |
| 766 |
|
* maintain parallelism when others are cooperatively blocked. |
| 767 |
|
* |
| 768 |
|
* @return the number of worker threads |
| 787 |
|
* Setting this value has no effect on current pool size. It |
| 788 |
|
* controls construction of new threads. |
| 789 |
|
* |
| 790 |
< |
* @throws IllegalArgumentException if negative or greater then |
| 790 |
> |
* @throws IllegalArgumentException if negative or greater than |
| 791 |
|
* internal implementation limit |
| 792 |
|
*/ |
| 793 |
|
public void setMaximumPoolSize(int newMax) { |
| 798 |
|
|
| 799 |
|
|
| 800 |
|
/** |
| 801 |
< |
* Returns true if this pool dynamically maintains its target |
| 802 |
< |
* parallelism level. If false, new threads are added only to |
| 803 |
< |
* avoid possible starvation. |
| 822 |
< |
* This setting is by default true. |
| 801 |
> |
* Returns {@code true} if this pool dynamically maintains its |
| 802 |
> |
* target parallelism level. If false, new threads are added only |
| 803 |
> |
* to avoid possible starvation. This setting is by default true. |
| 804 |
|
* |
| 805 |
< |
* @return true if maintains parallelism |
| 805 |
> |
* @return {@code true} if maintains parallelism |
| 806 |
|
*/ |
| 807 |
|
public boolean getMaintainsParallelism() { |
| 808 |
|
return maintainsParallelism; |
| 813 |
|
* parallelism level. If false, new threads are added only to |
| 814 |
|
* avoid possible starvation. |
| 815 |
|
* |
| 816 |
< |
* @param enable true to maintains parallelism |
| 816 |
> |
* @param enable {@code true} to maintain parallelism |
| 817 |
|
*/ |
| 818 |
|
public void setMaintainsParallelism(boolean enable) { |
| 819 |
|
maintainsParallelism = enable; |
| 824 |
|
* tasks that are never joined. This mode may be more appropriate |
| 825 |
|
* than default locally stack-based mode in applications in which |
| 826 |
|
* worker threads only process asynchronous tasks. This method is |
| 827 |
< |
* designed to be invoked only when pool is quiescent, and |
| 827 |
> |
* designed to be invoked only when the pool is quiescent, and |
| 828 |
|
* typically only before any tasks are submitted. The effects of |
| 829 |
|
* invocations at other times may be unpredictable. |
| 830 |
|
* |
| 831 |
< |
* @param async if true, use locally FIFO scheduling |
| 831 |
> |
* @param async if {@code true}, use locally FIFO scheduling |
| 832 |
|
* @return the previous mode |
| 833 |
+ |
* @see #getAsyncMode |
| 834 |
|
*/ |
| 835 |
|
public boolean setAsyncMode(boolean async) { |
| 836 |
|
boolean oldMode = locallyFifo; |
| 847 |
|
} |
| 848 |
|
|
| 849 |
|
/** |
| 850 |
< |
* Returns true if this pool uses local first-in-first-out |
| 850 |
> |
* Returns {@code true} if this pool uses local first-in-first-out |
| 851 |
|
* scheduling mode for forked tasks that are never joined. |
| 852 |
|
* |
| 853 |
< |
* @return true if this pool uses async mode |
| 853 |
> |
* @return {@code true} if this pool uses async mode |
| 854 |
> |
* @see #setAsyncMode |
| 855 |
|
*/ |
| 856 |
|
public boolean getAsyncMode() { |
| 857 |
|
return locallyFifo; |
| 892 |
|
} |
| 893 |
|
|
| 894 |
|
/** |
| 895 |
< |
* Returns true if all worker threads are currently idle. An idle |
| 896 |
< |
* worker is one that cannot obtain a task to execute because none |
| 897 |
< |
* are available to steal from other threads, and there are no |
| 898 |
< |
* pending submissions to the pool. This method is conservative; |
| 899 |
< |
* it might not return true immediately upon idleness of all |
| 900 |
< |
* threads, but will eventually become true if threads remain |
| 901 |
< |
* inactive. |
| 895 |
> |
* Returns {@code true} if all worker threads are currently idle. |
| 896 |
> |
* An idle worker is one that cannot obtain a task to execute |
| 897 |
> |
* because none are available to steal from other threads, and |
| 898 |
> |
* there are no pending submissions to the pool. This method is |
| 899 |
> |
* conservative; it might not return {@code true} immediately upon |
| 900 |
> |
* idleness of all threads, but will eventually become true if |
| 901 |
> |
* threads remain inactive. |
| 902 |
|
* |
| 903 |
< |
* @return true if all threads are currently idle |
| 903 |
> |
* @return {@code true} if all threads are currently idle |
| 904 |
|
*/ |
| 905 |
|
public boolean isQuiescent() { |
| 906 |
|
return activeCountOf(runControl) == 0; |
| 966 |
|
} |
| 967 |
|
|
| 968 |
|
/** |
| 969 |
< |
* Returns true if there are any tasks submitted to this pool |
| 970 |
< |
* that have not yet begun executing. |
| 969 |
> |
* Returns {@code true} if there are any tasks submitted to this |
| 970 |
> |
* pool that have not yet begun executing. |
| 971 |
|
* |
| 972 |
|
* @return {@code true} if there are any queued submissions |
| 973 |
|
*/ |
| 980 |
|
* available. This method may be useful in extensions to this |
| 981 |
|
* class that re-assign work in systems with multiple pools. |
| 982 |
|
* |
| 983 |
< |
* @return the next submission, or null if none |
| 983 |
> |
* @return the next submission, or {@code null} if none |
| 984 |
|
*/ |
| 985 |
|
protected ForkJoinTask<?> pollSubmission() { |
| 986 |
|
return submissionQueue.poll(); |
| 1003 |
|
* @param c the collection to transfer elements into |
| 1004 |
|
* @return the number of elements transferred |
| 1005 |
|
*/ |
| 1006 |
< |
protected int drainTasksTo(Collection<ForkJoinTask<?>> c) { |
| 1006 |
> |
protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) { |
| 1007 |
|
int n = submissionQueue.drainTo(c); |
| 1008 |
|
ForkJoinWorkerThread[] ws = workers; |
| 1009 |
|
if (ws != null) { |
| 1069 |
|
public void shutdown() { |
| 1070 |
|
checkPermission(); |
| 1071 |
|
transitionRunStateTo(SHUTDOWN); |
| 1072 |
< |
if (canTerminateOnShutdown(runControl)) |
| 1072 |
> |
if (canTerminateOnShutdown(runControl)) { |
| 1073 |
> |
if (workers == null) { // shutting down before workers created |
| 1074 |
> |
final ReentrantLock lock = this.workerLock; |
| 1075 |
> |
lock.lock(); |
| 1076 |
> |
try { |
| 1077 |
> |
if (workers == null) { |
| 1078 |
> |
terminate(); |
| 1079 |
> |
transitionRunStateTo(TERMINATED); |
| 1080 |
> |
termination.signalAll(); |
| 1081 |
> |
} |
| 1082 |
> |
} finally { |
| 1083 |
> |
lock.unlock(); |
| 1084 |
> |
} |
| 1085 |
> |
} |
| 1086 |
|
terminateOnShutdown(); |
| 1087 |
+ |
} |
| 1088 |
|
} |
| 1089 |
|
|
| 1090 |
|
/** |
| 1094 |
|
* method may or may not be rejected. Unlike some other executors, |
| 1095 |
|
* this method cancels rather than collects non-executed tasks |
| 1096 |
|
* upon termination, so always returns an empty list. However, you |
| 1097 |
< |
* can use method {@code drainTasksTo} before invoking this |
| 1097 |
> |
* can use method {@link #drainTasksTo} before invoking this |
| 1098 |
|
* method to transfer unexecuted tasks to another collection. |
| 1099 |
|
* |
| 1100 |
|
* @return an empty list |
| 1454 |
|
} |
| 1455 |
|
|
| 1456 |
|
/** |
| 1457 |
< |
* Returns true if worker waiting on sync can proceed: |
| 1457 |
> |
* Returns {@code true} if worker waiting on sync can proceed: |
| 1458 |
|
* - on signal (thread == null) |
| 1459 |
|
* - on event count advance (winning race to notify vs signaller) |
| 1460 |
|
* - on interrupt |
| 1462 |
|
* If node was not signalled and event count not advanced on exit, |
| 1463 |
|
* then we also help advance event count. |
| 1464 |
|
* |
| 1465 |
< |
* @return true if node can be released |
| 1465 |
> |
* @return {@code true} if node can be released |
| 1466 |
|
*/ |
| 1467 |
|
final boolean syncIsReleasable(WaitQueueNode node) { |
| 1468 |
|
long prev = node.count; |
| 1481 |
|
} |
| 1482 |
|
|
| 1483 |
|
/** |
| 1484 |
< |
* Returns true if a new sync event occurred since last call to |
| 1485 |
< |
* sync or this method, if so, updating caller's count. |
| 1484 |
> |
* Returns {@code true} if a new sync event occurred since last |
| 1485 |
> |
* call to sync or this method, if so, updating caller's count. |
| 1486 |
|
*/ |
| 1487 |
|
final boolean hasNewSyncEvent(ForkJoinWorkerThread w) { |
| 1488 |
|
long lc = w.lastEventCount; |
| 1566 |
|
} |
| 1567 |
|
|
| 1568 |
|
/** |
| 1569 |
< |
* Returns true if a spare thread appears to be needed. If |
| 1570 |
< |
* maintaining parallelism, returns true when the deficit in |
| 1569 |
> |
* Returns {@code true} if a spare thread appears to be needed. |
| 1570 |
> |
* If maintaining parallelism, returns true when the deficit in |
| 1571 |
|
* running threads is more than the surplus of total threads, and |
| 1572 |
|
* there is apparently some work to do. This self-limiting rule |
| 1573 |
|
* means that the more threads that have already been added, the |
| 1735 |
|
|
| 1736 |
|
/** |
| 1737 |
|
* Interface for extending managed parallelism for tasks running |
| 1738 |
< |
* in ForkJoinPools. A ManagedBlocker provides two methods. |
| 1739 |
< |
* Method {@code isReleasable} must return true if blocking is not |
| 1740 |
< |
* necessary. Method {@code block} blocks the current thread if |
| 1741 |
< |
* necessary (perhaps internally invoking {@code isReleasable} |
| 1742 |
< |
* before actually blocking.). |
| 1738 |
> |
* in {@link ForkJoinPool}s. |
| 1739 |
> |
* |
| 1740 |
> |
* <p>A {@code ManagedBlocker} provides two methods. |
| 1741 |
> |
* Method {@code isReleasable} must return {@code true} if |
| 1742 |
> |
* blocking is not necessary. Method {@code block} blocks the |
| 1743 |
> |
* current thread if necessary (perhaps internally invoking |
| 1744 |
> |
* {@code isReleasable} before actually blocking.). |
| 1745 |
|
* |
| 1746 |
|
* <p>For example, here is a ManagedBlocker based on a |
| 1747 |
|
* ReentrantLock: |
| 1765 |
|
* Possibly blocks the current thread, for example waiting for |
| 1766 |
|
* a lock or condition. |
| 1767 |
|
* |
| 1768 |
< |
* @return true if no additional blocking is necessary (i.e., |
| 1769 |
< |
* if isReleasable would return true) |
| 1768 |
> |
* @return {@code true} if no additional blocking is necessary |
| 1769 |
> |
* (i.e., if isReleasable would return true) |
| 1770 |
|
* @throws InterruptedException if interrupted while waiting |
| 1771 |
|
* (the method is not required to do so, but is allowed to) |
| 1772 |
|
*/ |
| 1773 |
|
boolean block() throws InterruptedException; |
| 1774 |
|
|
| 1775 |
|
/** |
| 1776 |
< |
* Returns true if blocking is unnecessary. |
| 1776 |
> |
* Returns {@code true} if blocking is unnecessary. |
| 1777 |
|
*/ |
| 1778 |
|
boolean isReleasable(); |
| 1779 |
|
} |
| 1783 |
|
* is a ForkJoinWorkerThread, this method possibly arranges for a |
| 1784 |
|
* spare thread to be activated if necessary to ensure parallelism |
| 1785 |
|
* while the current thread is blocked. If |
| 1786 |
< |
* {@code maintainParallelism} is true and the pool supports |
| 1786 |
> |
* {@code maintainParallelism} is {@code true} and the pool supports |
| 1787 |
|
* it ({@link #getMaintainsParallelism}), this method attempts to |
| 1788 |
|
* maintain the pool's nominal parallelism. Otherwise it activates |
| 1789 |
|
* a thread only if necessary to avoid complete starvation. This |
| 1801 |
|
* be expanded to ensure parallelism, and later adjusted. |
| 1802 |
|
* |
| 1803 |
|
* @param blocker the blocker |
| 1804 |
< |
* @param maintainParallelism if true and supported by this pool, |
| 1805 |
< |
* attempt to maintain the pool's nominal parallelism; otherwise |
| 1806 |
< |
* activate a thread only if necessary to avoid complete |
| 1807 |
< |
* starvation. |
| 1804 |
> |
* @param maintainParallelism if {@code true} and supported by |
| 1805 |
> |
* this pool, attempt to maintain the pool's nominal parallelism; |
| 1806 |
> |
* otherwise activate a thread only if necessary to avoid |
| 1807 |
> |
* complete starvation. |
| 1808 |
|
* @throws InterruptedException if blocker.block did so |
| 1809 |
|
*/ |
| 1810 |
|
public static void managedBlock(ManagedBlocker blocker, |
| 1830 |
|
do {} while (!blocker.isReleasable() && !blocker.block()); |
| 1831 |
|
} |
| 1832 |
|
|
| 1833 |
< |
// AbstractExecutorService overrides |
| 1833 |
> |
// AbstractExecutorService overrides. These rely on undocumented |
| 1834 |
> |
// fact that ForkJoinTask.adapt returns ForkJoinTasks that also |
| 1835 |
> |
// implement RunnableFuture. |
| 1836 |
|
|
| 1837 |
|
protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) { |
| 1838 |
< |
return new AdaptedRunnable(runnable, value); |
| 1838 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(runnable, value); |
| 1839 |
|
} |
| 1840 |
|
|
| 1841 |
|
protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) { |
| 1842 |
< |
return new AdaptedCallable(callable); |
| 1842 |
< |
} |
| 1843 |
< |
|
| 1844 |
< |
|
| 1845 |
< |
// Temporary Unsafe mechanics for preliminary release |
| 1846 |
< |
private static Unsafe getUnsafe() throws Throwable { |
| 1847 |
< |
try { |
| 1848 |
< |
return Unsafe.getUnsafe(); |
| 1849 |
< |
} catch (SecurityException se) { |
| 1850 |
< |
try { |
| 1851 |
< |
return java.security.AccessController.doPrivileged |
| 1852 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
| 1853 |
< |
public Unsafe run() throws Exception { |
| 1854 |
< |
return getUnsafePrivileged(); |
| 1855 |
< |
}}); |
| 1856 |
< |
} catch (java.security.PrivilegedActionException e) { |
| 1857 |
< |
throw e.getCause(); |
| 1858 |
< |
} |
| 1859 |
< |
} |
| 1842 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(callable); |
| 1843 |
|
} |
| 1844 |
|
|
| 1845 |
< |
private static Unsafe getUnsafePrivileged() |
| 1863 |
< |
throws NoSuchFieldException, IllegalAccessException { |
| 1864 |
< |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
| 1865 |
< |
f.setAccessible(true); |
| 1866 |
< |
return (Unsafe) f.get(null); |
| 1867 |
< |
} |
| 1845 |
> |
// Unsafe mechanics |
| 1846 |
|
|
| 1847 |
< |
private static long fieldOffset(String fieldName) |
| 1848 |
< |
throws NoSuchFieldException { |
| 1849 |
< |
return UNSAFE.objectFieldOffset |
| 1850 |
< |
(ForkJoinPool.class.getDeclaredField(fieldName)); |
| 1851 |
< |
} |
| 1852 |
< |
|
| 1853 |
< |
static final Unsafe UNSAFE; |
| 1854 |
< |
static final long eventCountOffset; |
| 1855 |
< |
static final long workerCountsOffset; |
| 1856 |
< |
static final long runControlOffset; |
| 1857 |
< |
static final long syncStackOffset; |
| 1880 |
< |
static final long spareStackOffset; |
| 1881 |
< |
|
| 1882 |
< |
static { |
| 1883 |
< |
try { |
| 1884 |
< |
UNSAFE = getUnsafe(); |
| 1885 |
< |
eventCountOffset = fieldOffset("eventCount"); |
| 1886 |
< |
workerCountsOffset = fieldOffset("workerCounts"); |
| 1887 |
< |
runControlOffset = fieldOffset("runControl"); |
| 1888 |
< |
syncStackOffset = fieldOffset("syncStack"); |
| 1889 |
< |
spareStackOffset = fieldOffset("spareStack"); |
| 1890 |
< |
} catch (Throwable e) { |
| 1891 |
< |
throw new RuntimeException("Could not initialize intrinsics", e); |
| 1892 |
< |
} |
| 1893 |
< |
} |
| 1847 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
| 1848 |
> |
private static final long eventCountOffset = |
| 1849 |
> |
objectFieldOffset("eventCount", ForkJoinPool.class); |
| 1850 |
> |
private static final long workerCountsOffset = |
| 1851 |
> |
objectFieldOffset("workerCounts", ForkJoinPool.class); |
| 1852 |
> |
private static final long runControlOffset = |
| 1853 |
> |
objectFieldOffset("runControl", ForkJoinPool.class); |
| 1854 |
> |
private static final long syncStackOffset = |
| 1855 |
> |
objectFieldOffset("syncStack",ForkJoinPool.class); |
| 1856 |
> |
private static final long spareStackOffset = |
| 1857 |
> |
objectFieldOffset("spareStack", ForkJoinPool.class); |
| 1858 |
|
|
| 1859 |
|
private boolean casEventCount(long cmp, long val) { |
| 1860 |
|
return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val); |
| 1871 |
|
private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) { |
| 1872 |
|
return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val); |
| 1873 |
|
} |
| 1874 |
+ |
|
| 1875 |
+ |
private static long objectFieldOffset(String field, Class<?> klazz) { |
| 1876 |
+ |
try { |
| 1877 |
+ |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
| 1878 |
+ |
} catch (NoSuchFieldException e) { |
| 1879 |
+ |
// Convert Exception to corresponding Error |
| 1880 |
+ |
NoSuchFieldError error = new NoSuchFieldError(field); |
| 1881 |
+ |
error.initCause(e); |
| 1882 |
+ |
throw error; |
| 1883 |
+ |
} |
| 1884 |
+ |
} |
| 1885 |
+ |
|
| 1886 |
+ |
/** |
| 1887 |
+ |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
| 1888 |
+ |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
| 1889 |
+ |
* into a jdk. |
| 1890 |
+ |
* |
| 1891 |
+ |
* @return a sun.misc.Unsafe |
| 1892 |
+ |
*/ |
| 1893 |
+ |
private static sun.misc.Unsafe getUnsafe() { |
| 1894 |
+ |
try { |
| 1895 |
+ |
return sun.misc.Unsafe.getUnsafe(); |
| 1896 |
+ |
} catch (SecurityException se) { |
| 1897 |
+ |
try { |
| 1898 |
+ |
return java.security.AccessController.doPrivileged |
| 1899 |
+ |
(new java.security |
| 1900 |
+ |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
| 1901 |
+ |
public sun.misc.Unsafe run() throws Exception { |
| 1902 |
+ |
java.lang.reflect.Field f = sun.misc |
| 1903 |
+ |
.Unsafe.class.getDeclaredField("theUnsafe"); |
| 1904 |
+ |
f.setAccessible(true); |
| 1905 |
+ |
return (sun.misc.Unsafe) f.get(null); |
| 1906 |
+ |
}}); |
| 1907 |
+ |
} catch (java.security.PrivilegedActionException e) { |
| 1908 |
+ |
throw new RuntimeException("Could not initialize intrinsics", |
| 1909 |
+ |
e.getCause()); |
| 1910 |
+ |
} |
| 1911 |
+ |
} |
| 1912 |
+ |
} |
| 1913 |
|
} |
