5 |
|
*/ |
6 |
|
|
7 |
|
package jsr166y; |
8 |
< |
import java.io.Serializable; |
9 |
< |
import java.util.*; |
8 |
> |
|
9 |
|
import java.util.concurrent.*; |
10 |
< |
import java.util.concurrent.atomic.*; |
11 |
< |
import sun.misc.Unsafe; |
12 |
< |
import java.lang.reflect.*; |
10 |
> |
|
11 |
> |
import java.io.Serializable; |
12 |
> |
import java.util.Collection; |
13 |
> |
import java.util.Collections; |
14 |
> |
import java.util.List; |
15 |
> |
import java.util.Map; |
16 |
> |
import java.util.WeakHashMap; |
17 |
|
|
18 |
|
/** |
19 |
< |
* Abstract base class for tasks that run within a {@link |
20 |
< |
* ForkJoinPool}. A ForkJoinTask is a thread-like entity that is much |
19 |
> |
* Abstract base class for tasks that run within a {@link ForkJoinPool}. |
20 |
> |
* A {@code ForkJoinTask} is a thread-like entity that is much |
21 |
|
* lighter weight than a normal thread. Huge numbers of tasks and |
22 |
|
* subtasks may be hosted by a small number of actual threads in a |
23 |
|
* ForkJoinPool, at the price of some usage limitations. |
25 |
|
* <p> A "main" ForkJoinTask begins execution when submitted to a |
26 |
|
* {@link ForkJoinPool}. Once started, it will usually in turn start |
27 |
|
* other subtasks. As indicated by the name of this class, many |
28 |
< |
* programs using ForkJoinTasks employ only methods {@code fork} |
29 |
< |
* and {@code join}, or derivatives such as |
30 |
< |
* {@code invokeAll}. However, this class also provides a number |
31 |
< |
* of other methods that can come into play in advanced usages, as |
32 |
< |
* well as extension mechanics that allow support of new forms of |
30 |
< |
* fork/join processing. |
28 |
> |
* programs using ForkJoinTasks employ only methods {@code fork} and |
29 |
> |
* {@code join}, or derivatives such as {@code invokeAll}. However, |
30 |
> |
* this class also provides a number of other methods that can come |
31 |
> |
* into play in advanced usages, as well as extension mechanics that |
32 |
> |
* allow support of new forms of fork/join processing. |
33 |
|
* |
34 |
|
* <p>A ForkJoinTask is a lightweight form of {@link Future}. The |
35 |
|
* efficiency of ForkJoinTasks stems from a set of restrictions (that |
93 |
|
* lightweight task scheduling framework, and so cannot be overridden. |
94 |
|
* Developers creating new basic styles of fork/join processing should |
95 |
|
* minimally implement {@code protected} methods |
96 |
< |
* {@code exec}, {@code setRawResult}, and |
97 |
< |
* {@code getRawResult}, while also introducing an abstract |
96 |
> |
* {@link #exec}, {@link #setRawResult}, and |
97 |
> |
* {@link #getRawResult}, while also introducing an abstract |
98 |
|
* computational method that can be implemented in its subclasses, |
99 |
|
* possibly relying on other {@code protected} methods provided |
100 |
|
* by this class. |
247 |
|
synchronized (this) { |
248 |
|
try { |
249 |
|
while (status >= 0) { |
250 |
< |
long nt = nanos - System.nanoTime() - startTime; |
250 |
> |
long nt = nanos - (System.nanoTime() - startTime); |
251 |
|
if (nt <= 0) |
252 |
|
break; |
253 |
|
wait(nt / 1000000, (int) (nt % 1000000)); |
491 |
|
* computations (as may be determined using method {@link |
492 |
|
* #inForkJoinPool}). Attempts to invoke in other contexts result |
493 |
|
* in exceptions or errors, possibly including ClassCastException. |
494 |
+ |
* |
495 |
+ |
* @return {@code this}, to simplify usage. |
496 |
|
*/ |
497 |
< |
public final void fork() { |
497 |
> |
public final ForkJoinTask<V> fork() { |
498 |
|
((ForkJoinWorkerThread) Thread.currentThread()) |
499 |
|
.pushTask(this); |
500 |
+ |
return this; |
501 |
|
} |
502 |
|
|
503 |
|
/** |
605 |
|
* in exceptions or errors, possibly including ClassCastException. |
606 |
|
* |
607 |
|
* @param tasks the collection of tasks |
608 |
+ |
* @return the tasks argument, to simplify usage |
609 |
|
* @throws NullPointerException if tasks or any element are null |
610 |
|
* @throws RuntimeException or Error if any task did so |
611 |
|
*/ |
612 |
< |
public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) { |
613 |
< |
if (!(tasks instanceof List)) { |
612 |
> |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
613 |
> |
if (!(tasks instanceof List<?>)) { |
614 |
|
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
615 |
< |
return; |
615 |
> |
return tasks; |
616 |
|
} |
617 |
+ |
@SuppressWarnings("unchecked") |
618 |
|
List<? extends ForkJoinTask<?>> ts = |
619 |
|
(List<? extends ForkJoinTask<?>>) tasks; |
620 |
|
Throwable ex = null; |
647 |
|
} |
648 |
|
if (ex != null) |
649 |
|
rethrowException(ex); |
650 |
+ |
return tasks; |
651 |
|
} |
652 |
|
|
653 |
|
/** |
654 |
< |
* Returns true if the computation performed by this task has |
655 |
< |
* completed (or has been cancelled). |
654 |
> |
* Returns {@code true} if the computation performed by this task |
655 |
> |
* has completed (or has been cancelled). |
656 |
|
* |
657 |
< |
* @return true if this computation has completed |
657 |
> |
* @return {@code true} if this computation has completed |
658 |
|
*/ |
659 |
|
public final boolean isDone() { |
660 |
|
return status < 0; |
661 |
|
} |
662 |
|
|
663 |
|
/** |
664 |
< |
* Returns true if this task was cancelled. |
664 |
> |
* Returns {@code true} if this task was cancelled. |
665 |
|
* |
666 |
< |
* @return true if this task was cancelled |
666 |
> |
* @return {@code true} if this task was cancelled |
667 |
|
*/ |
668 |
|
public final boolean isCancelled() { |
669 |
|
return (status & COMPLETION_MASK) == CANCELLED; |
672 |
|
/** |
673 |
|
* Asserts that the results of this task's computation will not be |
674 |
|
* used. If a cancellation occurs before attempting to execute this |
675 |
< |
* task, then execution will be suppressed, {@code isCancelled} |
676 |
< |
* will report true, and {@code join} will result in a |
675 |
> |
* task, execution will be suppressed, {@link #isCancelled} |
676 |
> |
* will report true, and {@link #join} will result in a |
677 |
|
* {@code CancellationException} being thrown. Otherwise, when |
678 |
|
* cancellation races with completion, there are no guarantees |
679 |
< |
* about whether {@code isCancelled} will report true, whether |
680 |
< |
* {@code join} will return normally or via an exception, or |
681 |
< |
* whether these behaviors will remain consistent upon repeated |
679 |
> |
* about whether {@code isCancelled} will report {@code true}, |
680 |
> |
* whether {@code join} will return normally or via an exception, |
681 |
> |
* or whether these behaviors will remain consistent upon repeated |
682 |
|
* invocation. |
683 |
|
* |
684 |
|
* <p>This method may be overridden in subclasses, but if so, must |
688 |
|
* <p> This method is designed to be invoked by <em>other</em> |
689 |
|
* tasks. To terminate the current task, you can just return or |
690 |
|
* throw an unchecked exception from its computation method, or |
691 |
< |
* invoke {@code completeExceptionally}. |
691 |
> |
* invoke {@link #completeExceptionally}. |
692 |
|
* |
693 |
|
* @param mayInterruptIfRunning this value is ignored in the |
694 |
|
* default implementation because tasks are not in general |
695 |
|
* cancelled via interruption |
696 |
|
* |
697 |
< |
* @return true if this task is now cancelled |
697 |
> |
* @return {@code true} if this task is now cancelled |
698 |
|
*/ |
699 |
|
public boolean cancel(boolean mayInterruptIfRunning) { |
700 |
|
setCompletion(CANCELLED); |
702 |
|
} |
703 |
|
|
704 |
|
/** |
705 |
< |
* Returns true if this task threw an exception or was cancelled. |
705 |
> |
* Returns {@code true} if this task threw an exception or was cancelled. |
706 |
|
* |
707 |
< |
* @return true if this task threw an exception or was cancelled |
707 |
> |
* @return {@code true} if this task threw an exception or was cancelled |
708 |
|
*/ |
709 |
|
public final boolean isCompletedAbnormally() { |
710 |
|
return (status & COMPLETION_MASK) < NORMAL; |
715 |
|
* CancellationException if cancelled, or null if none or if the |
716 |
|
* method has not yet completed. |
717 |
|
* |
718 |
< |
* @return the exception, or null if none |
718 |
> |
* @return the exception, or {@code null} if none |
719 |
|
*/ |
720 |
|
public final Throwable getException() { |
721 |
|
int s = status & COMPLETION_MASK; |
777 |
|
|
778 |
|
public final V get(long timeout, TimeUnit unit) |
779 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
780 |
+ |
long nanos = unit.toNanos(timeout); |
781 |
|
ForkJoinWorkerThread w = getWorker(); |
782 |
|
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
783 |
< |
awaitDone(w, unit.toNanos(timeout)); |
783 |
> |
awaitDone(w, nanos); |
784 |
|
return reportTimedFutureResult(); |
785 |
|
} |
786 |
|
|
879 |
|
* Returns the pool hosting the current task execution, or null |
880 |
|
* if this task is executing outside of any ForkJoinPool. |
881 |
|
* |
882 |
< |
* @return the pool, or null if none |
882 |
> |
* @return the pool, or {@code null} if none |
883 |
|
*/ |
884 |
|
public static ForkJoinPool getPool() { |
885 |
|
Thread t = Thread.currentThread(); |
886 |
< |
return ((t instanceof ForkJoinWorkerThread) ? |
887 |
< |
((ForkJoinWorkerThread) t).pool : null); |
886 |
> |
return (t instanceof ForkJoinWorkerThread) ? |
887 |
> |
((ForkJoinWorkerThread) t).pool : null; |
888 |
|
} |
889 |
|
|
890 |
|
/** |
910 |
|
* result in exceptions or errors, possibly including |
911 |
|
* ClassCastException. |
912 |
|
* |
913 |
< |
* @return true if unforked |
913 |
> |
* @return {@code true} if unforked |
914 |
|
*/ |
915 |
|
public boolean tryUnfork() { |
916 |
|
return ((ForkJoinWorkerThread) Thread.currentThread()) |
950 |
|
// Extension methods |
951 |
|
|
952 |
|
/** |
953 |
< |
* Returns the result that would be returned by {@code join}, |
954 |
< |
* even if this task completed abnormally, or null if this task is |
955 |
< |
* not known to have been completed. This method is designed to |
956 |
< |
* aid debugging, as well as to support extensions. Its use in any |
957 |
< |
* other context is discouraged. |
953 |
> |
* Returns the result that would be returned by {@link #join}, even |
954 |
> |
* if this task completed abnormally, or {@code null} if this task |
955 |
> |
* is not known to have been completed. This method is designed |
956 |
> |
* to aid debugging, as well as to support extensions. Its use in |
957 |
> |
* any other context is discouraged. |
958 |
|
* |
959 |
< |
* @return the result, or null if not completed |
959 |
> |
* @return the result, or {@code null} if not completed |
960 |
|
*/ |
961 |
|
public abstract V getRawResult(); |
962 |
|
|
975 |
|
* called otherwise. The return value controls whether this task |
976 |
|
* is considered to be done normally. It may return false in |
977 |
|
* asynchronous actions that require explicit invocations of |
978 |
< |
* {@code complete} to become joinable. It may throw exceptions |
978 |
> |
* {@link #complete} to become joinable. It may throw exceptions |
979 |
|
* to indicate abnormal exit. |
980 |
|
* |
981 |
< |
* @return true if completed normally |
981 |
> |
* @return {@code true} if completed normally |
982 |
|
* @throws Error or RuntimeException if encountered during computation |
983 |
|
*/ |
984 |
|
protected abstract boolean exec(); |
985 |
|
|
986 |
|
/** |
987 |
< |
* Returns, but does not unschedule or execute, the task queued by |
988 |
< |
* the current thread but not yet executed, if one is |
987 |
> |
* Returns, but does not unschedule or execute, a task queued by |
988 |
> |
* the current thread but not yet executed, if one is immediately |
989 |
|
* available. There is no guarantee that this task will actually |
990 |
< |
* be polled or executed next. This method is designed primarily |
991 |
< |
* to support extensions, and is unlikely to be useful otherwise. |
992 |
< |
* This method may be invoked only from within ForkJoinTask |
993 |
< |
* computations (as may be determined using method {@link |
994 |
< |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
995 |
< |
* in exceptions or errors, possibly including ClassCastException. |
990 |
> |
* be polled or executed next. Conversely, this method may return |
991 |
> |
* null even if a task exists but cannot be accessed without |
992 |
> |
* contention with other threads. This method is designed |
993 |
> |
* primarily to support extensions, and is unlikely to be useful |
994 |
> |
* otherwise. This method may be invoked only from within |
995 |
> |
* ForkJoinTask computations (as may be determined using method |
996 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
997 |
> |
* result in exceptions or errors, possibly including |
998 |
> |
* ClassCastException. |
999 |
|
* |
1000 |
< |
* @return the next task, or null if none are available |
1000 |
> |
* @return the next task, or {@code null} if none are available |
1001 |
|
*/ |
1002 |
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1003 |
|
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1014 |
|
* contexts result in exceptions or errors, possibly including |
1015 |
|
* ClassCastException. |
1016 |
|
* |
1017 |
< |
* @return the next task, or null if none are available |
1017 |
> |
* @return the next task, or {@code null} if none are available |
1018 |
|
*/ |
1019 |
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1020 |
|
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1035 |
|
* result in exceptions or errors, possibly including |
1036 |
|
* ClassCastException. |
1037 |
|
* |
1038 |
< |
* @return a task, or null if none are available |
1038 |
> |
* @return a task, or {@code null} if none are available |
1039 |
|
*/ |
1040 |
|
protected static ForkJoinTask<?> pollTask() { |
1041 |
|
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1042 |
|
.pollTask(); |
1043 |
|
} |
1044 |
|
|
1045 |
+ |
/** |
1046 |
+ |
* Adaptor for Runnables. This implements RunnableFuture |
1047 |
+ |
* to be compliant with AbstractExecutorService constraints |
1048 |
+ |
* when used in ForkJoinPool. |
1049 |
+ |
*/ |
1050 |
+ |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1051 |
+ |
implements RunnableFuture<T> { |
1052 |
+ |
final Runnable runnable; |
1053 |
+ |
final T resultOnCompletion; |
1054 |
+ |
T result; |
1055 |
+ |
AdaptedRunnable(Runnable runnable, T result) { |
1056 |
+ |
if (runnable == null) throw new NullPointerException(); |
1057 |
+ |
this.runnable = runnable; |
1058 |
+ |
this.resultOnCompletion = result; |
1059 |
+ |
} |
1060 |
+ |
public T getRawResult() { return result; } |
1061 |
+ |
public void setRawResult(T v) { result = v; } |
1062 |
+ |
public boolean exec() { |
1063 |
+ |
runnable.run(); |
1064 |
+ |
result = resultOnCompletion; |
1065 |
+ |
return true; |
1066 |
+ |
} |
1067 |
+ |
public void run() { invoke(); } |
1068 |
+ |
private static final long serialVersionUID = 5232453952276885070L; |
1069 |
+ |
} |
1070 |
+ |
|
1071 |
+ |
/** |
1072 |
+ |
* Adaptor for Callables |
1073 |
+ |
*/ |
1074 |
+ |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1075 |
+ |
implements RunnableFuture<T> { |
1076 |
+ |
final Callable<T> callable; |
1077 |
+ |
T result; |
1078 |
+ |
AdaptedCallable(Callable<T> callable) { |
1079 |
+ |
if (callable == null) throw new NullPointerException(); |
1080 |
+ |
this.callable = callable; |
1081 |
+ |
} |
1082 |
+ |
public T getRawResult() { return result; } |
1083 |
+ |
public void setRawResult(T v) { result = v; } |
1084 |
+ |
public boolean exec() { |
1085 |
+ |
try { |
1086 |
+ |
result = callable.call(); |
1087 |
+ |
return true; |
1088 |
+ |
} catch (Error err) { |
1089 |
+ |
throw err; |
1090 |
+ |
} catch (RuntimeException rex) { |
1091 |
+ |
throw rex; |
1092 |
+ |
} catch (Exception ex) { |
1093 |
+ |
throw new RuntimeException(ex); |
1094 |
+ |
} |
1095 |
+ |
} |
1096 |
+ |
public void run() { invoke(); } |
1097 |
+ |
private static final long serialVersionUID = 2838392045355241008L; |
1098 |
+ |
} |
1099 |
+ |
|
1100 |
+ |
/** |
1101 |
+ |
* Returns a new ForkJoinTask that performs the {@code run} |
1102 |
+ |
* method of the given Runnable as its action, and returns a null |
1103 |
+ |
* result upon {@code join}. |
1104 |
+ |
* |
1105 |
+ |
* @param runnable the runnable action |
1106 |
+ |
* @return the task |
1107 |
+ |
*/ |
1108 |
+ |
public static ForkJoinTask<Void> adapt(Runnable runnable) { |
1109 |
+ |
return new AdaptedRunnable<Void>(runnable, null); |
1110 |
+ |
} |
1111 |
+ |
|
1112 |
+ |
/** |
1113 |
+ |
* Returns a new ForkJoinTask that performs the {@code run} |
1114 |
+ |
* method of the given Runnable as its action, and returns the |
1115 |
+ |
* given result upon {@code join}. |
1116 |
+ |
* |
1117 |
+ |
* @param runnable the runnable action |
1118 |
+ |
* @param result the result upon completion |
1119 |
+ |
* @return the task |
1120 |
+ |
*/ |
1121 |
+ |
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1122 |
+ |
return new AdaptedRunnable<T>(runnable, result); |
1123 |
+ |
} |
1124 |
+ |
|
1125 |
+ |
/** |
1126 |
+ |
* Returns a new ForkJoinTask that performs the {@code call} |
1127 |
+ |
* method of the given Callable as its action, and returns its |
1128 |
+ |
* result upon {@code join}, translating any checked |
1129 |
+ |
* exceptions encountered into {@code RuntimeException}. |
1130 |
+ |
* |
1131 |
+ |
* @param callable the callable action |
1132 |
+ |
* @return the task |
1133 |
+ |
*/ |
1134 |
+ |
public static <T> ForkJoinTask<T> adapt(Callable<T> callable) { |
1135 |
+ |
return new AdaptedCallable<T>(callable); |
1136 |
+ |
} |
1137 |
+ |
|
1138 |
|
// Serialization support |
1139 |
|
|
1140 |
|
private static final long serialVersionUID = -7721805057305804111L; |
1143 |
|
* Save the state to a stream. |
1144 |
|
* |
1145 |
|
* @serialData the current run status and the exception thrown |
1146 |
< |
* during execution, or null if none |
1146 |
> |
* during execution, or {@code null} if none |
1147 |
|
* @param s the stream |
1148 |
|
*/ |
1149 |
|
private void writeObject(java.io.ObjectOutputStream s) |
1167 |
|
setDoneExceptionally((Throwable) ex); |
1168 |
|
} |
1169 |
|
|
1170 |
< |
// Temporary Unsafe mechanics for preliminary release |
1171 |
< |
private static Unsafe getUnsafe() throws Throwable { |
1170 |
> |
// Unsafe mechanics |
1171 |
> |
|
1172 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1173 |
> |
private static final long statusOffset = |
1174 |
> |
objectFieldOffset("status", ForkJoinTask.class); |
1175 |
> |
|
1176 |
> |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1177 |
> |
try { |
1178 |
> |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1179 |
> |
} catch (NoSuchFieldException e) { |
1180 |
> |
// Convert Exception to corresponding Error |
1181 |
> |
NoSuchFieldError error = new NoSuchFieldError(field); |
1182 |
> |
error.initCause(e); |
1183 |
> |
throw error; |
1184 |
> |
} |
1185 |
> |
} |
1186 |
> |
|
1187 |
> |
/** |
1188 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1189 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1190 |
> |
* into a jdk. |
1191 |
> |
* |
1192 |
> |
* @return a sun.misc.Unsafe |
1193 |
> |
*/ |
1194 |
> |
private static sun.misc.Unsafe getUnsafe() { |
1195 |
|
try { |
1196 |
< |
return Unsafe.getUnsafe(); |
1196 |
> |
return sun.misc.Unsafe.getUnsafe(); |
1197 |
|
} catch (SecurityException se) { |
1198 |
|
try { |
1199 |
|
return java.security.AccessController.doPrivileged |
1200 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
1201 |
< |
public Unsafe run() throws Exception { |
1202 |
< |
return getUnsafePrivileged(); |
1200 |
> |
(new java.security |
1201 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1202 |
> |
public sun.misc.Unsafe run() throws Exception { |
1203 |
> |
java.lang.reflect.Field f = sun.misc |
1204 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1205 |
> |
f.setAccessible(true); |
1206 |
> |
return (sun.misc.Unsafe) f.get(null); |
1207 |
|
}}); |
1208 |
|
} catch (java.security.PrivilegedActionException e) { |
1209 |
< |
throw e.getCause(); |
1209 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
1210 |
> |
e.getCause()); |
1211 |
|
} |
1212 |
|
} |
1213 |
|
} |
1081 |
– |
|
1082 |
– |
private static Unsafe getUnsafePrivileged() |
1083 |
– |
throws NoSuchFieldException, IllegalAccessException { |
1084 |
– |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
1085 |
– |
f.setAccessible(true); |
1086 |
– |
return (Unsafe) f.get(null); |
1087 |
– |
} |
1088 |
– |
|
1089 |
– |
private static long fieldOffset(String fieldName) |
1090 |
– |
throws NoSuchFieldException { |
1091 |
– |
return UNSAFE.objectFieldOffset |
1092 |
– |
(ForkJoinTask.class.getDeclaredField(fieldName)); |
1093 |
– |
} |
1094 |
– |
|
1095 |
– |
static final Unsafe UNSAFE; |
1096 |
– |
static final long statusOffset; |
1097 |
– |
|
1098 |
– |
static { |
1099 |
– |
try { |
1100 |
– |
UNSAFE = getUnsafe(); |
1101 |
– |
statusOffset = fieldOffset("status"); |
1102 |
– |
} catch (Throwable e) { |
1103 |
– |
throw new RuntimeException("Could not initialize intrinsics", e); |
1104 |
– |
} |
1105 |
– |
} |
1106 |
– |
|
1214 |
|
} |