| 6 |
|
|
| 7 |
|
package jsr166y; |
| 8 |
|
|
| 9 |
– |
import java.util.concurrent.*; |
| 10 |
– |
|
| 9 |
|
import java.util.Random; |
| 10 |
|
import java.util.Collection; |
| 11 |
|
import java.util.concurrent.locks.LockSupport; |
| 12 |
+ |
import java.util.concurrent.RejectedExecutionException; |
| 13 |
|
|
| 14 |
|
/** |
| 15 |
|
* A thread managed by a {@link ForkJoinPool}. This class is |
| 171 |
|
|
| 172 |
|
/** |
| 173 |
|
* Maximum work-stealing queue array size. Must be less than or |
| 174 |
< |
* equal to 1 << 28 to ensure lack of index wraparound. (This |
| 175 |
< |
* is less than usual bounds, because we need leftshift by 3 |
| 176 |
< |
* to be in int range). |
| 174 |
> |
* equal to 1 << (31 - width of array entry) to ensure lack of |
| 175 |
> |
* index wraparound. The value is set in the static block |
| 176 |
> |
* at the end of this file after obtaining width. |
| 177 |
|
*/ |
| 178 |
< |
private static final int MAXIMUM_QUEUE_CAPACITY = 1 << 28; |
| 178 |
> |
private static final int MAXIMUM_QUEUE_CAPACITY; |
| 179 |
|
|
| 180 |
|
/** |
| 181 |
|
* The pool this thread works in. Accessed directly by ForkJoinTask. |
| 229 |
|
private static final int TRIMMED = 0x08; // killed while suspended |
| 230 |
|
|
| 231 |
|
/** |
| 232 |
< |
* Number of steals, transferred and reset in pool callbacks pool |
| 233 |
< |
* when idle Accessed directly by pool. |
| 232 |
> |
* Number of steals. Directly accessed (and reset) by |
| 233 |
> |
* pool.tryAccumulateStealCount when idle. |
| 234 |
|
*/ |
| 235 |
|
int stealCount; |
| 236 |
|
|
| 285 |
|
|
| 286 |
|
/** |
| 287 |
|
* The task currently being joined, set only when actively trying |
| 288 |
< |
* to helpStealer. Written only by current thread, but read by |
| 289 |
< |
* others. |
| 288 |
> |
* to help other stealers in helpJoinTask. Written only by this |
| 289 |
> |
* thread, but read by others. |
| 290 |
|
*/ |
| 291 |
|
private volatile ForkJoinTask<?> currentJoin; |
| 292 |
|
|
| 293 |
|
/** |
| 294 |
|
* The task most recently stolen from another worker (or |
| 295 |
< |
* submission queue). Written only by current thread, but read by |
| 295 |
> |
* submission queue). Written only by this thread, but read by |
| 296 |
|
* others. |
| 297 |
|
*/ |
| 298 |
|
private volatile ForkJoinTask<?> currentSteal; |
| 312 |
|
} |
| 313 |
|
|
| 314 |
|
/** |
| 315 |
< |
* Performs additional initialization and starts this thread |
| 315 |
> |
* Performs additional initialization and starts this thread. |
| 316 |
|
*/ |
| 317 |
|
final void start(int poolIndex, UncaughtExceptionHandler ueh) { |
| 318 |
|
this.poolIndex = poolIndex; |
| 348 |
|
/** |
| 349 |
|
* Initializes internal state after construction but before |
| 350 |
|
* processing any tasks. If you override this method, you must |
| 351 |
< |
* invoke super.onStart() at the beginning of the method. |
| 351 |
> |
* invoke @code{super.onStart()} at the beginning of the method. |
| 352 |
|
* Initialization requires care: Most fields must have legal |
| 353 |
|
* default values, to ensure that attempted accesses from other |
| 354 |
|
* threads work correctly even before this thread starts |
| 380 |
|
if (active) { |
| 381 |
|
int a; // inline p.tryDecrementActiveCount |
| 382 |
|
active = false; |
| 383 |
< |
do {} while(!UNSAFE.compareAndSwapInt |
| 384 |
< |
(p, poolRunStateOffset, a = p.runState, a - 1)); |
| 383 |
> |
do {} while (!UNSAFE.compareAndSwapInt |
| 384 |
> |
(p, poolRunStateOffset, a = p.runState, a - 1)); |
| 385 |
|
} |
| 386 |
|
cancelTasks(); |
| 387 |
|
setTerminated(); |
| 415 |
|
// helpers for run() |
| 416 |
|
|
| 417 |
|
/** |
| 418 |
< |
* Find and execute tasks and check status while running |
| 418 |
> |
* Finds and executes tasks, and checks status while running. |
| 419 |
|
*/ |
| 420 |
|
private void mainLoop() { |
| 421 |
|
boolean ran = false; // true if ran a task on last step |
| 429 |
|
} |
| 430 |
|
|
| 431 |
|
/** |
| 432 |
< |
* Try to steal a task and execute it |
| 432 |
> |
* Tries to steal a task and execute it. |
| 433 |
|
* |
| 434 |
|
* @return true if ran a task |
| 435 |
|
*/ |
| 446 |
|
} |
| 447 |
|
|
| 448 |
|
/** |
| 449 |
< |
* If a submission exists, try to activate and run it; |
| 449 |
> |
* If a submission exists, try to activate and run it. |
| 450 |
|
* |
| 451 |
|
* @return true if ran a task |
| 452 |
|
*/ |
| 453 |
|
private boolean tryExecSubmission() { |
| 454 |
|
ForkJoinPool p = pool; |
| 455 |
+ |
// This loop is needed in case attempt to activate fails, in |
| 456 |
+ |
// which case we only retry if there still appears to be a |
| 457 |
+ |
// submission. |
| 458 |
|
while (p.hasQueuedSubmissions()) { |
| 459 |
|
ForkJoinTask<?> t; int a; |
| 460 |
|
if (active || // inline p.tryIncrementActiveCount |
| 479 |
|
*/ |
| 480 |
|
private void execLocalTasks() { |
| 481 |
|
while (runState == 0) { |
| 482 |
< |
ForkJoinTask<?> t = locallyFifo? locallyDeqTask() : popTask(); |
| 482 |
> |
ForkJoinTask<?> t = locallyFifo ? locallyDeqTask() : popTask(); |
| 483 |
|
if (t != null) |
| 484 |
|
t.quietlyExec(); |
| 485 |
|
else if (sp == base) |
| 489 |
|
|
| 490 |
|
/* |
| 491 |
|
* Intrinsics-based atomic writes for queue slots. These are |
| 492 |
< |
* basically the same as methods in AtomicObjectArray, but |
| 492 |
> |
* basically the same as methods in AtomicReferenceArray, but |
| 493 |
|
* specialized for (1) ForkJoinTask elements (2) requirement that |
| 494 |
|
* nullness and bounds checks have already been performed by |
| 495 |
|
* callers and (3) effective offsets are known not to overflow |
| 496 |
|
* from int to long (because of MAXIMUM_QUEUE_CAPACITY). We don't |
| 497 |
|
* need corresponding version for reads: plain array reads are OK |
| 498 |
< |
* because they protected by other volatile reads and are |
| 498 |
> |
* because they are protected by other volatile reads and are |
| 499 |
|
* confirmed by CASes. |
| 500 |
|
* |
| 501 |
|
* Most uses don't actually call these methods, but instead contain |
| 519 |
|
* range. This method is used only during resets and backouts. |
| 520 |
|
*/ |
| 521 |
|
private static final void writeSlot(ForkJoinTask<?>[] q, int i, |
| 522 |
< |
ForkJoinTask<?> t) { |
| 522 |
> |
ForkJoinTask<?> t) { |
| 523 |
|
UNSAFE.putObjectVolatile(q, (i << qShift) + qBase, t); |
| 524 |
|
} |
| 525 |
|
|
| 564 |
|
|
| 565 |
|
/** |
| 566 |
|
* Tries to take a task from the base of own queue. Assumes active |
| 567 |
< |
* status. Called only by current thread. |
| 567 |
> |
* status. Called only by this thread. |
| 568 |
|
* |
| 569 |
|
* @return a task, or null if none |
| 570 |
|
*/ |
| 587 |
|
|
| 588 |
|
/** |
| 589 |
|
* Returns a popped task, or null if empty. Assumes active status. |
| 590 |
< |
* Called only by current thread. |
| 590 |
> |
* Called only by this thread. |
| 591 |
|
*/ |
| 592 |
|
private ForkJoinTask<?> popTask() { |
| 593 |
|
ForkJoinTask<?>[] q = queue; |
| 611 |
|
|
| 612 |
|
/** |
| 613 |
|
* Specialized version of popTask to pop only if topmost element |
| 614 |
< |
* is the given task. Called only by current thread while |
| 613 |
< |
* active. |
| 614 |
> |
* is the given task. Called only by this thread while active. |
| 615 |
|
* |
| 616 |
|
* @param t the task. Caller must ensure non-null. |
| 617 |
|
*/ |
| 629 |
|
} |
| 630 |
|
|
| 631 |
|
/** |
| 632 |
< |
* Returns next task or null if empty or contended |
| 632 |
> |
* Returns next task, or null if empty or contended. |
| 633 |
|
*/ |
| 634 |
|
final ForkJoinTask<?> peekTask() { |
| 635 |
|
ForkJoinTask<?>[] q = queue; |
| 671 |
|
* Computes next value for random victim probe in scan(). Scans |
| 672 |
|
* don't require a very high quality generator, but also not a |
| 673 |
|
* crummy one. Marsaglia xor-shift is cheap and works well enough. |
| 674 |
< |
* Note: This is manually inlined in scan() |
| 674 |
> |
* Note: This is manually inlined in scan(). |
| 675 |
|
*/ |
| 676 |
|
private static final int xorShift(int r) { |
| 677 |
|
r ^= r << 13; |
| 749 |
|
// Run State management |
| 750 |
|
|
| 751 |
|
// status check methods used mainly by ForkJoinPool |
| 752 |
< |
final boolean isRunning() { return runState == 0; } |
| 753 |
< |
final boolean isTerminating() { return (runState & TERMINATING) != 0; } |
| 754 |
< |
final boolean isTerminated() { return (runState & TERMINATED) != 0; } |
| 755 |
< |
final boolean isSuspended() { return (runState & SUSPENDED) != 0; } |
| 756 |
< |
final boolean isTrimmed() { return (runState & TRIMMED) != 0; } |
| 752 |
> |
final boolean isRunning() { return runState == 0; } |
| 753 |
> |
final boolean isTerminated() { return (runState & TERMINATED) != 0; } |
| 754 |
> |
final boolean isSuspended() { return (runState & SUSPENDED) != 0; } |
| 755 |
> |
final boolean isTrimmed() { return (runState & TRIMMED) != 0; } |
| 756 |
> |
|
| 757 |
> |
final boolean isTerminating() { |
| 758 |
> |
if ((runState & TERMINATING) != 0) |
| 759 |
> |
return true; |
| 760 |
> |
if (pool.isAtLeastTerminating()) { // propagate pool state |
| 761 |
> |
shutdown(); |
| 762 |
> |
return true; |
| 763 |
> |
} |
| 764 |
> |
return false; |
| 765 |
> |
} |
| 766 |
|
|
| 767 |
|
/** |
| 768 |
|
* Sets state to TERMINATING. Does NOT unpark or interrupt |
| 786 |
|
} |
| 787 |
|
|
| 788 |
|
/** |
| 789 |
< |
* Sets state to TERMINATED. Called only by onTermination() |
| 789 |
> |
* Sets state to TERMINATED. Called only by onTermination(). |
| 790 |
|
*/ |
| 791 |
|
private void setTerminated() { |
| 792 |
|
int s; |
| 907 |
|
if (active || |
| 908 |
|
(active = UNSAFE.compareAndSwapInt(p, poolRunStateOffset, |
| 909 |
|
a = p.runState, a + 1))) |
| 910 |
< |
return locallyFifo? locallyDeqTask() : popTask(); |
| 910 |
> |
return locallyFifo ? locallyDeqTask() : popTask(); |
| 911 |
|
} |
| 912 |
|
return null; |
| 913 |
|
} |
| 931 |
|
* Possibly runs some tasks and/or blocks, until task is done. |
| 932 |
|
* |
| 933 |
|
* @param joinMe the task to join |
| 934 |
+ |
* @param timed true if use timed wait |
| 935 |
+ |
* @param nanos wait time if timed |
| 936 |
|
*/ |
| 937 |
< |
final void joinTask(ForkJoinTask<?> joinMe) { |
| 937 |
> |
final void joinTask(ForkJoinTask<?> joinMe, boolean timed, long nanos) { |
| 938 |
|
// currentJoin only written by this thread; only need ordered store |
| 939 |
|
ForkJoinTask<?> prevJoin = currentJoin; |
| 940 |
|
UNSAFE.putOrderedObject(this, currentJoinOffset, joinMe); |
| 941 |
< |
if (sp != base) |
| 942 |
< |
localHelpJoinTask(joinMe); |
| 943 |
< |
if (joinMe.status >= 0) |
| 944 |
< |
pool.awaitJoin(joinMe, this); |
| 941 |
> |
if (isTerminating()) // cancel if shutting down |
| 942 |
> |
joinMe.cancelIgnoringExceptions(); |
| 943 |
> |
else |
| 944 |
> |
pool.awaitJoin(joinMe, this, timed, nanos); |
| 945 |
|
UNSAFE.putOrderedObject(this, currentJoinOffset, prevJoin); |
| 946 |
|
} |
| 947 |
|
|
| 948 |
|
/** |
| 949 |
|
* Run tasks in local queue until given task is done. |
| 950 |
+ |
* Not currently used because it complicates semantics. |
| 951 |
|
* |
| 952 |
|
* @param joinMe the task to join |
| 953 |
|
*/ |
| 980 |
|
} |
| 981 |
|
|
| 982 |
|
/** |
| 983 |
< |
* Unless terminating, tries to locate and help perform tasks for |
| 984 |
< |
* a stealer of the given task, or in turn one of its stealers. |
| 985 |
< |
* Traces currentSteal->currentJoin links looking for a thread |
| 986 |
< |
* working on a descendant of the given task and with a non-empty |
| 987 |
< |
* queue to steal back and execute tasks from. |
| 983 |
> |
* Tries to locate and help perform tasks for a stealer of the |
| 984 |
> |
* given task, or in turn one of its stealers. Traces |
| 985 |
> |
* currentSteal->currentJoin links looking for a thread working on |
| 986 |
> |
* a descendant of the given task and with a non-empty queue to |
| 987 |
> |
* steal back and execute tasks from. |
| 988 |
|
* |
| 989 |
|
* The implementation is very branchy to cope with potential |
| 990 |
|
* inconsistencies or loops encountering chains that are stale, |
| 1000 |
|
int n; |
| 1001 |
|
if (joinMe.status < 0) // already done |
| 1002 |
|
return; |
| 990 |
– |
if ((runState & TERMINATING) != 0) { // cancel if shutting down |
| 991 |
– |
joinMe.cancelIgnoringExceptions(); |
| 992 |
– |
return; |
| 993 |
– |
} |
| 1003 |
|
if ((ws = pool.workers) == null || (n = ws.length) <= 1) |
| 1004 |
|
return; // need at least 2 workers |
| 1005 |
|
|
| 1012 |
|
for (int j = 0; ; ++j) { // search array |
| 1013 |
|
if (j < n) { |
| 1014 |
|
ForkJoinTask<?> vs; |
| 1015 |
< |
if ((v = ws[j]) != null && |
| 1015 |
> |
if ((v = ws[j]) != null && v != this && |
| 1016 |
|
(vs = v.currentSteal) != null) { |
| 1017 |
|
if (joinMe.status < 0 || task.status < 0) |
| 1018 |
|
return; // stale or done |
| 1064 |
|
} |
| 1065 |
|
|
| 1066 |
|
/** |
| 1067 |
+ |
* Implements ForkJoinTask.getSurplusQueuedTaskCount(). |
| 1068 |
|
* Returns an estimate of the number of tasks, offset by a |
| 1069 |
|
* function of number of idle workers. |
| 1070 |
|
* |
| 1136 |
|
} |
| 1137 |
|
if (p.isQuiescent()) { |
| 1138 |
|
active = true; // re-activate |
| 1139 |
< |
do {} while(!UNSAFE.compareAndSwapInt |
| 1140 |
< |
(p, poolRunStateOffset, a = p.runState, a+1)); |
| 1139 |
> |
do {} while (!UNSAFE.compareAndSwapInt |
| 1140 |
> |
(p, poolRunStateOffset, a = p.runState, a+1)); |
| 1141 |
|
return; |
| 1142 |
|
} |
| 1143 |
|
} |
| 1167 |
|
if ((s & (s-1)) != 0) |
| 1168 |
|
throw new Error("data type scale not a power of two"); |
| 1169 |
|
qShift = 31 - Integer.numberOfLeadingZeros(s); |
| 1170 |
+ |
MAXIMUM_QUEUE_CAPACITY = 1 << (31 - qShift); |
| 1171 |
|
} |
| 1172 |
|
|
| 1173 |
|
private static long objectFieldOffset(String field, Class<?> klazz) { |
