5 |
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*/ |
6 |
|
|
7 |
|
package jsr166y; |
8 |
< |
import java.util.*; |
8 |
> |
|
9 |
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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 |
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|
22 |
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/** |
23 |
< |
* An {@link ExecutorService} for running {@link ForkJoinTask}s. A |
24 |
< |
* 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 |
28 |
< |
* construction and bookkeeping overhead of creating a large set of |
29 |
< |
* threads. |
23 |
> |
* An {@link ExecutorService} for running {@link ForkJoinTask}s. |
24 |
> |
* A {@code ForkJoinPool} provides the entry point for submissions |
25 |
> |
* from non-{@code ForkJoinTask}s, as well as management and |
26 |
> |
* monitoring operations. Normally a single {@code ForkJoinPool} is |
27 |
> |
* used for a large number of submitted tasks. Otherwise, use would |
28 |
> |
* not usually outweigh the construction and bookkeeping overhead of |
29 |
> |
* creating a large set of threads. |
30 |
|
* |
31 |
< |
* <p>ForkJoinPools differ from other kinds of Executors mainly in |
32 |
< |
* that they provide <em>work-stealing</em>: all threads in the pool |
33 |
< |
* attempt to find and execute subtasks created by other active tasks |
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. |
31 |
> |
* <p>{@code ForkJoinPool}s differ from other kinds of {@link |
32 |
> |
* Executor}s mainly in that they provide <em>work-stealing</em>: all |
33 |
> |
* threads in the pool attempt to find and execute subtasks created by |
34 |
> |
* other active tasks (eventually blocking if none exist). This makes |
35 |
> |
* them efficient when most tasks spawn other subtasks (as do most |
36 |
> |
* {@code ForkJoinTask}s), as well as the mixed execution of some |
37 |
> |
* plain {@code Runnable}- or {@code Callable}- based activities along |
38 |
> |
* with {@code ForkJoinTask}s. When setting {@linkplain #setAsyncMode |
39 |
> |
* async mode}, a {@code ForkJoinPool} may also be appropriate for use |
40 |
> |
* with fine-grained tasks that are never joined. Otherwise, other |
41 |
> |
* {@code ExecutorService} implementations are typically more |
42 |
> |
* appropriate choices. |
43 |
|
* |
44 |
< |
* <p>A ForkJoinPool may be constructed with a given parallelism level |
45 |
< |
* (target pool size), which it attempts to maintain by dynamically |
46 |
< |
* adding, suspending, or resuming threads, even if some tasks are |
47 |
< |
* waiting to join others. However, no such adjustments are performed |
48 |
< |
* in the face of blocked IO or other unmanaged synchronization. The |
49 |
< |
* nested {@code ManagedBlocker} interface enables extension of |
50 |
< |
* the kinds of synchronization accommodated. The target parallelism |
51 |
< |
* level may also be changed dynamically ({@code setParallelism}) |
52 |
< |
* and thread construction can be limited using methods |
53 |
< |
* {@code setMaximumPoolSize} and/or |
54 |
< |
* {@code setMaintainsParallelism}. |
44 |
> |
* <p>A {@code ForkJoinPool} may be constructed with a given |
45 |
> |
* parallelism level (target pool size), which it attempts to maintain |
46 |
> |
* by dynamically adding, suspending, or resuming threads, even if |
47 |
> |
* some tasks are waiting to join others. However, no such adjustments |
48 |
> |
* are performed in the face of blocked IO or other unmanaged |
49 |
> |
* synchronization. The nested {@link ManagedBlocker} interface |
50 |
> |
* enables extension of the kinds of synchronization accommodated. |
51 |
> |
* The target parallelism level may also be changed dynamically |
52 |
> |
* ({@link #setParallelism}) and thread construction can be limited |
53 |
> |
* using methods {@link #setMaximumPoolSize} and/or {@link |
54 |
> |
* #setMaintainsParallelism}. |
55 |
|
* |
56 |
|
* <p>In addition to execution and lifecycle control methods, this |
57 |
|
* class provides status check methods (for example |
58 |
< |
* {@code getStealCount}) that are intended to aid in developing, |
58 |
> |
* {@link #getStealCount}) that are intended to aid in developing, |
59 |
|
* tuning, and monitoring fork/join applications. Also, method |
60 |
< |
* {@code toString} returns indications of pool state in a |
60 |
> |
* {@link #toString} returns indications of pool state in a |
61 |
|
* convenient form for informal monitoring. |
62 |
|
* |
63 |
|
* <p><b>Implementation notes</b>: This implementation restricts the |
64 |
|
* maximum number of running threads to 32767. Attempts to create |
65 |
|
* pools with greater than the maximum result in |
66 |
< |
* IllegalArgumentExceptions. |
66 |
> |
* {@code IllegalArgumentException}. |
67 |
|
* |
68 |
|
* @since 1.7 |
69 |
|
* @author Doug Lea |
82 |
|
private static final int MAX_THREADS = 0x7FFF; |
83 |
|
|
84 |
|
/** |
85 |
< |
* Factory for creating new ForkJoinWorkerThreads. A |
86 |
< |
* ForkJoinWorkerThreadFactory must be defined and used for |
87 |
< |
* ForkJoinWorkerThread subclasses that extend base functionality |
88 |
< |
* or initialize threads with different contexts. |
85 |
> |
* Factory for creating new {@link ForkJoinWorkerThread}s. |
86 |
> |
* A {@code ForkJoinWorkerThreadFactory} must be defined and used |
87 |
> |
* for {@code ForkJoinWorkerThread} subclasses that extend base |
88 |
> |
* functionality or initialize threads with different contexts. |
89 |
|
*/ |
90 |
|
public static interface ForkJoinWorkerThreadFactory { |
91 |
|
/** |
312 |
|
} |
313 |
|
|
314 |
|
/** |
315 |
< |
* Returns true if argument represents zero active count and |
316 |
< |
* nonzero runstate, which is the triggering condition for |
315 |
> |
* Returns {@code true} if argument represents zero active count |
316 |
> |
* and nonzero runstate, which is the triggering condition for |
317 |
|
* terminating on shutdown. |
318 |
|
*/ |
319 |
|
private static boolean canTerminateOnShutdown(int c) { |
549 |
|
* Common code for execute, invoke and submit |
550 |
|
*/ |
551 |
|
private <T> void doSubmit(ForkJoinTask<T> task) { |
552 |
+ |
if (task == null) |
553 |
+ |
throw new NullPointerException(); |
554 |
|
if (isShutdown()) |
555 |
|
throw new RejectedExecutionException(); |
556 |
|
if (workers == null) |
579 |
|
* @throws NullPointerException if task is null |
580 |
|
* @throws RejectedExecutionException if pool is shut down |
581 |
|
*/ |
582 |
< |
public <T> void execute(ForkJoinTask<T> task) { |
582 |
> |
public void execute(ForkJoinTask<?> task) { |
583 |
|
doSubmit(task); |
584 |
|
} |
585 |
|
|
586 |
|
// AbstractExecutorService methods |
587 |
|
|
588 |
|
public void execute(Runnable task) { |
589 |
< |
doSubmit(new AdaptedRunnable<Void>(task, null)); |
589 |
> |
ForkJoinTask<?> job; |
590 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
591 |
> |
job = (ForkJoinTask<?>) task; |
592 |
> |
else |
593 |
> |
job = ForkJoinTask.adapt(task, null); |
594 |
> |
doSubmit(job); |
595 |
|
} |
596 |
|
|
597 |
|
public <T> ForkJoinTask<T> submit(Callable<T> task) { |
598 |
< |
ForkJoinTask<T> job = new AdaptedCallable<T>(task); |
598 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task); |
599 |
|
doSubmit(job); |
600 |
|
return job; |
601 |
|
} |
602 |
|
|
603 |
|
public <T> ForkJoinTask<T> submit(Runnable task, T result) { |
604 |
< |
ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result); |
604 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task, result); |
605 |
|
doSubmit(job); |
606 |
|
return job; |
607 |
|
} |
608 |
|
|
609 |
|
public ForkJoinTask<?> submit(Runnable task) { |
610 |
< |
ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null); |
610 |
> |
ForkJoinTask<?> job; |
611 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
612 |
> |
job = (ForkJoinTask<?>) task; |
613 |
> |
else |
614 |
> |
job = ForkJoinTask.adapt(task, null); |
615 |
|
doSubmit(job); |
616 |
|
return job; |
617 |
|
} |
618 |
|
|
619 |
|
/** |
620 |
< |
* Adaptor for Runnables. This implements RunnableFuture |
621 |
< |
* to be compliant with AbstractExecutorService constraints. |
620 |
> |
* Submits a ForkJoinTask for execution. |
621 |
> |
* |
622 |
> |
* @param task the task to submit |
623 |
> |
* @return the task |
624 |
> |
* @throws RejectedExecutionException if the task cannot be |
625 |
> |
* scheduled for execution |
626 |
> |
* @throws NullPointerException if the task is null |
627 |
|
*/ |
628 |
< |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
629 |
< |
implements RunnableFuture<T> { |
630 |
< |
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; |
628 |
> |
public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) { |
629 |
> |
doSubmit(task); |
630 |
> |
return task; |
631 |
|
} |
632 |
|
|
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 |
– |
} |
633 |
|
|
634 |
|
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) { |
635 |
|
ArrayList<ForkJoinTask<T>> forkJoinTasks = |
636 |
|
new ArrayList<ForkJoinTask<T>>(tasks.size()); |
637 |
|
for (Callable<T> task : tasks) |
638 |
< |
forkJoinTasks.add(new AdaptedCallable<T>(task)); |
638 |
> |
forkJoinTasks.add(ForkJoinTask.adapt(task)); |
639 |
|
invoke(new InvokeAll<T>(forkJoinTasks)); |
640 |
|
|
641 |
|
@SuppressWarnings({"unchecked", "rawtypes"}) |
668 |
|
* Returns the handler for internal worker threads that terminate |
669 |
|
* due to unrecoverable errors encountered while executing tasks. |
670 |
|
* |
671 |
< |
* @return the handler, or null if none |
671 |
> |
* @return the handler, or {@code null} if none |
672 |
|
*/ |
673 |
|
public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() { |
674 |
|
Thread.UncaughtExceptionHandler h; |
689 |
|
* as handler. |
690 |
|
* |
691 |
|
* @param h the new handler |
692 |
< |
* @return the old handler, or null if none |
692 |
> |
* @return the old handler, or {@code null} if none |
693 |
|
* @throws SecurityException if a security manager exists and |
694 |
|
* the caller is not permitted to modify threads |
695 |
|
* because it does not hold {@link |
763 |
|
/** |
764 |
|
* Returns the number of worker threads that have started but not |
765 |
|
* yet terminated. This result returned by this method may differ |
766 |
< |
* from {@code getParallelism} when threads are created to |
766 |
> |
* from {@link #getParallelism} when threads are created to |
767 |
|
* maintain parallelism when others are cooperatively blocked. |
768 |
|
* |
769 |
|
* @return the number of worker threads |
788 |
|
* Setting this value has no effect on current pool size. It |
789 |
|
* controls construction of new threads. |
790 |
|
* |
791 |
< |
* @throws IllegalArgumentException if negative or greater then |
791 |
> |
* @throws IllegalArgumentException if negative or greater than |
792 |
|
* internal implementation limit |
793 |
|
*/ |
794 |
|
public void setMaximumPoolSize(int newMax) { |
799 |
|
|
800 |
|
|
801 |
|
/** |
802 |
< |
* Returns true if this pool dynamically maintains its target |
803 |
< |
* parallelism level. If false, new threads are added only to |
804 |
< |
* avoid possible starvation. |
825 |
< |
* This setting is by default true. |
802 |
> |
* Returns {@code true} if this pool dynamically maintains its |
803 |
> |
* target parallelism level. If false, new threads are added only |
804 |
> |
* to avoid possible starvation. This setting is by default true. |
805 |
|
* |
806 |
< |
* @return true if maintains parallelism |
806 |
> |
* @return {@code true} if maintains parallelism |
807 |
|
*/ |
808 |
|
public boolean getMaintainsParallelism() { |
809 |
|
return maintainsParallelism; |
814 |
|
* parallelism level. If false, new threads are added only to |
815 |
|
* avoid possible starvation. |
816 |
|
* |
817 |
< |
* @param enable true to maintains parallelism |
817 |
> |
* @param enable {@code true} to maintain parallelism |
818 |
|
*/ |
819 |
|
public void setMaintainsParallelism(boolean enable) { |
820 |
|
maintainsParallelism = enable; |
825 |
|
* tasks that are never joined. This mode may be more appropriate |
826 |
|
* than default locally stack-based mode in applications in which |
827 |
|
* worker threads only process asynchronous tasks. This method is |
828 |
< |
* designed to be invoked only when pool is quiescent, and |
828 |
> |
* designed to be invoked only when the pool is quiescent, and |
829 |
|
* typically only before any tasks are submitted. The effects of |
830 |
|
* invocations at other times may be unpredictable. |
831 |
|
* |
832 |
< |
* @param async if true, use locally FIFO scheduling |
832 |
> |
* @param async if {@code true}, use locally FIFO scheduling |
833 |
|
* @return the previous mode |
834 |
+ |
* @see #getAsyncMode |
835 |
|
*/ |
836 |
|
public boolean setAsyncMode(boolean async) { |
837 |
|
boolean oldMode = locallyFifo; |
848 |
|
} |
849 |
|
|
850 |
|
/** |
851 |
< |
* Returns true if this pool uses local first-in-first-out |
851 |
> |
* Returns {@code true} if this pool uses local first-in-first-out |
852 |
|
* scheduling mode for forked tasks that are never joined. |
853 |
|
* |
854 |
< |
* @return true if this pool uses async mode |
854 |
> |
* @return {@code true} if this pool uses async mode |
855 |
> |
* @see #setAsyncMode |
856 |
|
*/ |
857 |
|
public boolean getAsyncMode() { |
858 |
|
return locallyFifo; |
893 |
|
} |
894 |
|
|
895 |
|
/** |
896 |
< |
* Returns true if all worker threads are currently idle. An idle |
897 |
< |
* worker is one that cannot obtain a task to execute because none |
898 |
< |
* are available to steal from other threads, and there are no |
899 |
< |
* pending submissions to the pool. This method is conservative; |
900 |
< |
* it might not return true immediately upon idleness of all |
901 |
< |
* threads, but will eventually become true if threads remain |
902 |
< |
* inactive. |
896 |
> |
* Returns {@code true} if all worker threads are currently idle. |
897 |
> |
* An idle worker is one that cannot obtain a task to execute |
898 |
> |
* because none are available to steal from other threads, and |
899 |
> |
* there are no pending submissions to the pool. This method is |
900 |
> |
* conservative; it might not return {@code true} immediately upon |
901 |
> |
* idleness of all threads, but will eventually become true if |
902 |
> |
* threads remain inactive. |
903 |
|
* |
904 |
< |
* @return true if all threads are currently idle |
904 |
> |
* @return {@code true} if all threads are currently idle |
905 |
|
*/ |
906 |
|
public boolean isQuiescent() { |
907 |
|
return activeCountOf(runControl) == 0; |
956 |
|
} |
957 |
|
|
958 |
|
/** |
959 |
< |
* Returns an estimate of the number tasks submitted to this pool |
960 |
< |
* that have not yet begun executing. This method takes time |
959 |
> |
* Returns an estimate of the number of tasks submitted to this |
960 |
> |
* pool that have not yet begun executing. This method takes time |
961 |
|
* proportional to the number of submissions. |
962 |
|
* |
963 |
|
* @return the number of queued submissions |
967 |
|
} |
968 |
|
|
969 |
|
/** |
970 |
< |
* Returns true if there are any tasks submitted to this pool |
971 |
< |
* that have not yet begun executing. |
970 |
> |
* Returns {@code true} if there are any tasks submitted to this |
971 |
> |
* pool that have not yet begun executing. |
972 |
|
* |
973 |
|
* @return {@code true} if there are any queued submissions |
974 |
|
*/ |
981 |
|
* available. This method may be useful in extensions to this |
982 |
|
* class that re-assign work in systems with multiple pools. |
983 |
|
* |
984 |
< |
* @return the next submission, or null if none |
984 |
> |
* @return the next submission, or {@code null} if none |
985 |
|
*/ |
986 |
|
protected ForkJoinTask<?> pollSubmission() { |
987 |
|
return submissionQueue.poll(); |
1004 |
|
* @param c the collection to transfer elements into |
1005 |
|
* @return the number of elements transferred |
1006 |
|
*/ |
1007 |
< |
protected int drainTasksTo(Collection<ForkJoinTask<?>> c) { |
1007 |
> |
protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) { |
1008 |
|
int n = submissionQueue.drainTo(c); |
1009 |
|
ForkJoinWorkerThread[] ws = workers; |
1010 |
|
if (ws != null) { |
1070 |
|
public void shutdown() { |
1071 |
|
checkPermission(); |
1072 |
|
transitionRunStateTo(SHUTDOWN); |
1073 |
< |
if (canTerminateOnShutdown(runControl)) |
1073 |
> |
if (canTerminateOnShutdown(runControl)) { |
1074 |
> |
if (workers == null) { // shutting down before workers created |
1075 |
> |
final ReentrantLock lock = this.workerLock; |
1076 |
> |
lock.lock(); |
1077 |
> |
try { |
1078 |
> |
if (workers == null) { |
1079 |
> |
terminate(); |
1080 |
> |
transitionRunStateTo(TERMINATED); |
1081 |
> |
termination.signalAll(); |
1082 |
> |
} |
1083 |
> |
} finally { |
1084 |
> |
lock.unlock(); |
1085 |
> |
} |
1086 |
> |
} |
1087 |
|
terminateOnShutdown(); |
1088 |
+ |
} |
1089 |
|
} |
1090 |
|
|
1091 |
|
/** |
1095 |
|
* method may or may not be rejected. Unlike some other executors, |
1096 |
|
* this method cancels rather than collects non-executed tasks |
1097 |
|
* upon termination, so always returns an empty list. However, you |
1098 |
< |
* can use method {@code drainTasksTo} before invoking this |
1098 |
> |
* can use method {@link #drainTasksTo} before invoking this |
1099 |
|
* method to transfer unexecuted tasks to another collection. |
1100 |
|
* |
1101 |
|
* @return an empty list |
1455 |
|
} |
1456 |
|
|
1457 |
|
/** |
1458 |
< |
* Returns true if worker waiting on sync can proceed: |
1458 |
> |
* Returns {@code true} if worker waiting on sync can proceed: |
1459 |
|
* - on signal (thread == null) |
1460 |
|
* - on event count advance (winning race to notify vs signaller) |
1461 |
|
* - on interrupt |
1463 |
|
* If node was not signalled and event count not advanced on exit, |
1464 |
|
* then we also help advance event count. |
1465 |
|
* |
1466 |
< |
* @return true if node can be released |
1466 |
> |
* @return {@code true} if node can be released |
1467 |
|
*/ |
1468 |
|
final boolean syncIsReleasable(WaitQueueNode node) { |
1469 |
|
long prev = node.count; |
1482 |
|
} |
1483 |
|
|
1484 |
|
/** |
1485 |
< |
* Returns true if a new sync event occurred since last call to |
1486 |
< |
* sync or this method, if so, updating caller's count. |
1485 |
> |
* Returns {@code true} if a new sync event occurred since last |
1486 |
> |
* call to sync or this method, if so, updating caller's count. |
1487 |
|
*/ |
1488 |
|
final boolean hasNewSyncEvent(ForkJoinWorkerThread w) { |
1489 |
|
long lc = w.lastEventCount; |
1567 |
|
} |
1568 |
|
|
1569 |
|
/** |
1570 |
< |
* Returns true if a spare thread appears to be needed. If |
1571 |
< |
* maintaining parallelism, returns true when the deficit in |
1570 |
> |
* Returns {@code true} if a spare thread appears to be needed. |
1571 |
> |
* If maintaining parallelism, returns true when the deficit in |
1572 |
|
* running threads is more than the surplus of total threads, and |
1573 |
|
* there is apparently some work to do. This self-limiting rule |
1574 |
|
* means that the more threads that have already been added, the |
1736 |
|
|
1737 |
|
/** |
1738 |
|
* Interface for extending managed parallelism for tasks running |
1739 |
< |
* in ForkJoinPools. A ManagedBlocker provides two methods. |
1740 |
< |
* Method {@code isReleasable} must return true if blocking is not |
1741 |
< |
* necessary. Method {@code block} blocks the current thread if |
1742 |
< |
* necessary (perhaps internally invoking {@code isReleasable} |
1743 |
< |
* before actually blocking.). |
1739 |
> |
* in {@link ForkJoinPool}s. |
1740 |
> |
* |
1741 |
> |
* <p>A {@code ManagedBlocker} provides two methods. |
1742 |
> |
* Method {@code isReleasable} must return {@code true} if |
1743 |
> |
* blocking is not necessary. Method {@code block} blocks the |
1744 |
> |
* current thread if necessary (perhaps internally invoking |
1745 |
> |
* {@code isReleasable} before actually blocking). |
1746 |
|
* |
1747 |
|
* <p>For example, here is a ManagedBlocker based on a |
1748 |
|
* ReentrantLock: |
1766 |
|
* Possibly blocks the current thread, for example waiting for |
1767 |
|
* a lock or condition. |
1768 |
|
* |
1769 |
< |
* @return true if no additional blocking is necessary (i.e., |
1770 |
< |
* if isReleasable would return true) |
1769 |
> |
* @return {@code true} if no additional blocking is necessary |
1770 |
> |
* (i.e., if isReleasable would return true) |
1771 |
|
* @throws InterruptedException if interrupted while waiting |
1772 |
|
* (the method is not required to do so, but is allowed to) |
1773 |
|
*/ |
1774 |
|
boolean block() throws InterruptedException; |
1775 |
|
|
1776 |
|
/** |
1777 |
< |
* Returns true if blocking is unnecessary. |
1777 |
> |
* Returns {@code true} if blocking is unnecessary. |
1778 |
|
*/ |
1779 |
|
boolean isReleasable(); |
1780 |
|
} |
1781 |
|
|
1782 |
|
/** |
1783 |
|
* Blocks in accord with the given blocker. If the current thread |
1784 |
< |
* is a ForkJoinWorkerThread, this method possibly arranges for a |
1785 |
< |
* spare thread to be activated if necessary to ensure parallelism |
1786 |
< |
* while the current thread is blocked. If |
1787 |
< |
* {@code maintainParallelism} is true and the pool supports |
1788 |
< |
* it ({@link #getMaintainsParallelism}), this method attempts to |
1789 |
< |
* maintain the pool's nominal parallelism. Otherwise it activates |
1790 |
< |
* a thread only if necessary to avoid complete starvation. This |
1791 |
< |
* option may be preferable when blockages use timeouts, or are |
1792 |
< |
* almost always brief. |
1784 |
> |
* is a {@link ForkJoinWorkerThread}, this method possibly |
1785 |
> |
* arranges for a spare thread to be activated if necessary to |
1786 |
> |
* ensure parallelism while the current thread is blocked. |
1787 |
> |
* |
1788 |
> |
* <p>If {@code maintainParallelism} is {@code true} and the pool |
1789 |
> |
* supports it ({@link #getMaintainsParallelism}), this method |
1790 |
> |
* attempts to maintain the pool's nominal parallelism. Otherwise |
1791 |
> |
* it activates a thread only if necessary to avoid complete |
1792 |
> |
* starvation. This option may be preferable when blockages use |
1793 |
> |
* timeouts, or are almost always brief. |
1794 |
|
* |
1795 |
< |
* <p> If the caller is not a ForkJoinTask, this method is behaviorally |
1796 |
< |
* equivalent to |
1795 |
> |
* <p>If the caller is not a {@link ForkJoinTask}, this method is |
1796 |
> |
* behaviorally equivalent to |
1797 |
|
* <pre> {@code |
1798 |
|
* while (!blocker.isReleasable()) |
1799 |
|
* if (blocker.block()) |
1800 |
|
* return; |
1801 |
|
* }</pre> |
1802 |
< |
* If the caller is a ForkJoinTask, then the pool may first |
1803 |
< |
* be expanded to ensure parallelism, and later adjusted. |
1802 |
> |
* |
1803 |
> |
* If the caller is a {@code ForkJoinTask}, then the pool may |
1804 |
> |
* first be expanded to ensure parallelism, and later adjusted. |
1805 |
|
* |
1806 |
|
* @param blocker the blocker |
1807 |
< |
* @param maintainParallelism if true and supported by this pool, |
1808 |
< |
* attempt to maintain the pool's nominal parallelism; otherwise |
1809 |
< |
* activate a thread only if necessary to avoid complete |
1810 |
< |
* starvation. |
1807 |
> |
* @param maintainParallelism if {@code true} and supported by |
1808 |
> |
* this pool, attempt to maintain the pool's nominal parallelism; |
1809 |
> |
* otherwise activate a thread only if necessary to avoid |
1810 |
> |
* complete starvation. |
1811 |
|
* @throws InterruptedException if blocker.block did so |
1812 |
|
*/ |
1813 |
|
public static void managedBlock(ManagedBlocker blocker, |
1833 |
|
do {} while (!blocker.isReleasable() && !blocker.block()); |
1834 |
|
} |
1835 |
|
|
1836 |
< |
// AbstractExecutorService overrides |
1836 |
> |
// AbstractExecutorService overrides. These rely on undocumented |
1837 |
> |
// fact that ForkJoinTask.adapt returns ForkJoinTasks that also |
1838 |
> |
// implement RunnableFuture. |
1839 |
|
|
1840 |
|
protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) { |
1841 |
< |
return new AdaptedRunnable<T>(runnable, value); |
1841 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(runnable, value); |
1842 |
|
} |
1843 |
|
|
1844 |
|
protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) { |
1845 |
< |
return new AdaptedCallable<T>(callable); |
1845 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(callable); |
1846 |
|
} |
1847 |
|
|
1848 |
+ |
// Unsafe mechanics |
1849 |
|
|
1850 |
< |
// Temporary Unsafe mechanics for preliminary release |
1851 |
< |
private static Unsafe getUnsafe() throws Throwable { |
1852 |
< |
try { |
1853 |
< |
return Unsafe.getUnsafe(); |
1854 |
< |
} catch (SecurityException se) { |
1855 |
< |
try { |
1856 |
< |
return java.security.AccessController.doPrivileged |
1857 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
1858 |
< |
public Unsafe run() throws Exception { |
1859 |
< |
return getUnsafePrivileged(); |
1860 |
< |
}}); |
1859 |
< |
} catch (java.security.PrivilegedActionException e) { |
1860 |
< |
throw e.getCause(); |
1861 |
< |
} |
1862 |
< |
} |
1863 |
< |
} |
1864 |
< |
|
1865 |
< |
private static Unsafe getUnsafePrivileged() |
1866 |
< |
throws NoSuchFieldException, IllegalAccessException { |
1867 |
< |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
1868 |
< |
f.setAccessible(true); |
1869 |
< |
return (Unsafe) f.get(null); |
1870 |
< |
} |
1871 |
< |
|
1872 |
< |
private static long fieldOffset(String fieldName) |
1873 |
< |
throws NoSuchFieldException { |
1874 |
< |
return UNSAFE.objectFieldOffset |
1875 |
< |
(ForkJoinPool.class.getDeclaredField(fieldName)); |
1876 |
< |
} |
1877 |
< |
|
1878 |
< |
static final Unsafe UNSAFE; |
1879 |
< |
static final long eventCountOffset; |
1880 |
< |
static final long workerCountsOffset; |
1881 |
< |
static final long runControlOffset; |
1882 |
< |
static final long syncStackOffset; |
1883 |
< |
static final long spareStackOffset; |
1884 |
< |
|
1885 |
< |
static { |
1886 |
< |
try { |
1887 |
< |
UNSAFE = getUnsafe(); |
1888 |
< |
eventCountOffset = fieldOffset("eventCount"); |
1889 |
< |
workerCountsOffset = fieldOffset("workerCounts"); |
1890 |
< |
runControlOffset = fieldOffset("runControl"); |
1891 |
< |
syncStackOffset = fieldOffset("syncStack"); |
1892 |
< |
spareStackOffset = fieldOffset("spareStack"); |
1893 |
< |
} catch (Throwable e) { |
1894 |
< |
throw new RuntimeException("Could not initialize intrinsics", e); |
1895 |
< |
} |
1896 |
< |
} |
1850 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1851 |
> |
private static final long eventCountOffset = |
1852 |
> |
objectFieldOffset("eventCount", ForkJoinPool.class); |
1853 |
> |
private static final long workerCountsOffset = |
1854 |
> |
objectFieldOffset("workerCounts", ForkJoinPool.class); |
1855 |
> |
private static final long runControlOffset = |
1856 |
> |
objectFieldOffset("runControl", ForkJoinPool.class); |
1857 |
> |
private static final long syncStackOffset = |
1858 |
> |
objectFieldOffset("syncStack",ForkJoinPool.class); |
1859 |
> |
private static final long spareStackOffset = |
1860 |
> |
objectFieldOffset("spareStack", ForkJoinPool.class); |
1861 |
|
|
1862 |
|
private boolean casEventCount(long cmp, long val) { |
1863 |
|
return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val); |
1874 |
|
private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) { |
1875 |
|
return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val); |
1876 |
|
} |
1877 |
+ |
|
1878 |
+ |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1879 |
+ |
try { |
1880 |
+ |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1881 |
+ |
} catch (NoSuchFieldException e) { |
1882 |
+ |
// Convert Exception to corresponding Error |
1883 |
+ |
NoSuchFieldError error = new NoSuchFieldError(field); |
1884 |
+ |
error.initCause(e); |
1885 |
+ |
throw error; |
1886 |
+ |
} |
1887 |
+ |
} |
1888 |
+ |
|
1889 |
+ |
/** |
1890 |
+ |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1891 |
+ |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1892 |
+ |
* into a jdk. |
1893 |
+ |
* |
1894 |
+ |
* @return a sun.misc.Unsafe |
1895 |
+ |
*/ |
1896 |
+ |
private static sun.misc.Unsafe getUnsafe() { |
1897 |
+ |
try { |
1898 |
+ |
return sun.misc.Unsafe.getUnsafe(); |
1899 |
+ |
} catch (SecurityException se) { |
1900 |
+ |
try { |
1901 |
+ |
return java.security.AccessController.doPrivileged |
1902 |
+ |
(new java.security |
1903 |
+ |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1904 |
+ |
public sun.misc.Unsafe run() throws Exception { |
1905 |
+ |
java.lang.reflect.Field f = sun.misc |
1906 |
+ |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1907 |
+ |
f.setAccessible(true); |
1908 |
+ |
return (sun.misc.Unsafe) f.get(null); |
1909 |
+ |
}}); |
1910 |
+ |
} catch (java.security.PrivilegedActionException e) { |
1911 |
+ |
throw new RuntimeException("Could not initialize intrinsics", |
1912 |
+ |
e.getCause()); |
1913 |
+ |
} |
1914 |
+ |
} |
1915 |
+ |
} |
1916 |
|
} |