17 |
|
* subclassable solely for the sake of adding functionality -- there |
18 |
|
* are no overridable methods dealing with scheduling or |
19 |
|
* execution. However, you can override initialization and termination |
20 |
< |
* cleanup methods surrounding the main task processing loop. If you |
21 |
< |
* do create such a subclass, you will also need to supply a custom |
20 |
> |
* methods surrounding the main task processing loop. If you do |
21 |
> |
* create such a subclass, you will also need to supply a custom |
22 |
|
* ForkJoinWorkerThreadFactory to use it in a ForkJoinPool. |
23 |
< |
* |
24 |
< |
* <p>This class also provides methods for generating per-thread |
25 |
< |
* random numbers, with the same properties as {@link |
26 |
< |
* java.util.Random} but with each generator isolated from those of |
27 |
< |
* other threads. |
23 |
> |
* |
24 |
> |
* @since 1.7 |
25 |
> |
* @author Doug Lea |
26 |
|
*/ |
27 |
|
public class ForkJoinWorkerThread extends Thread { |
28 |
|
/* |
46 |
|
* of tasks. To accomplish this, we shift the CAS arbitrating pop |
47 |
|
* vs deq (steal) from being on the indices ("base" and "sp") to |
48 |
|
* the slots themselves (mainly via method "casSlotNull()"). So, |
49 |
< |
* both a successful pop and deq mainly entail CAS'ing a nonnull |
49 |
> |
* both a successful pop and deq mainly entail CAS'ing a non-null |
50 |
|
* slot to null. Because we rely on CASes of references, we do |
51 |
|
* not need tag bits on base or sp. They are simple ints as used |
52 |
|
* in any circular array-based queue (see for example ArrayDeque). |
58 |
|
* considered individually, is not wait-free. One thief cannot |
59 |
|
* successfully continue until another in-progress one (or, if |
60 |
|
* previously empty, a push) completes. However, in the |
61 |
< |
* aggregate, we ensure at least probablistic non-blockingness. If |
61 |
> |
* aggregate, we ensure at least probabilistic non-blockingness. If |
62 |
|
* an attempted steal fails, a thief always chooses a different |
63 |
|
* random victim target to try next. So, in order for one thief to |
64 |
|
* progress, it suffices for any in-progress deq or new push on |
77 |
|
* push) require store order and CASes (in pop and deq) require |
78 |
|
* (volatile) CAS semantics. Since these combinations aren't |
79 |
|
* supported using ordinary volatiles, the only way to accomplish |
80 |
< |
* these effciently is to use direct Unsafe calls. (Using external |
80 |
> |
* these efficiently is to use direct Unsafe calls. (Using external |
81 |
|
* AtomicIntegers and AtomicReferenceArrays for the indices and |
82 |
|
* array is significantly slower because of memory locality and |
83 |
|
* indirection effects.) Further, performance on most platforms is |
132 |
|
|
133 |
|
/** |
134 |
|
* Maximum work-stealing queue array size. Must be less than or |
135 |
< |
* equal to 1 << 30 to ensure lack of index wraparound. |
135 |
> |
* equal to 1 << 28 to ensure lack of index wraparound. (This |
136 |
> |
* is less than usual bounds, because we need leftshift by 3 |
137 |
> |
* to be in int range). |
138 |
|
*/ |
139 |
< |
private static final int MAXIMUM_QUEUE_CAPACITY = 1 << 30; |
139 |
> |
private static final int MAXIMUM_QUEUE_CAPACITY = 1 << 28; |
140 |
|
|
141 |
|
/** |
142 |
< |
* Generator of seeds for per-thread random numbers. |
142 |
> |
* The pool this thread works in. Accessed directly by ForkJoinTask. |
143 |
|
*/ |
144 |
< |
private static final Random randomSeedGenerator = new Random(); |
144 |
> |
final ForkJoinPool pool; |
145 |
|
|
146 |
|
/** |
147 |
|
* The work-stealing queue array. Size must be a power of two. |
148 |
+ |
* Initialized when thread starts, to improve memory locality. |
149 |
|
*/ |
150 |
|
private ForkJoinTask<?>[] queue; |
151 |
|
|
164 |
|
private volatile int base; |
165 |
|
|
166 |
|
/** |
167 |
< |
* The pool this thread works in. |
168 |
< |
*/ |
169 |
< |
final ForkJoinPool pool; |
170 |
< |
|
170 |
< |
/** |
171 |
< |
* Index of this worker in pool array. Set once by pool before |
172 |
< |
* running, and accessed directly by pool during cleanup etc |
167 |
> |
* Activity status. When true, this worker is considered active. |
168 |
> |
* Must be false upon construction. It must be true when executing |
169 |
> |
* tasks, and BEFORE stealing a task. It must be false before |
170 |
> |
* calling pool.sync. |
171 |
|
*/ |
172 |
< |
int poolIndex; |
172 |
> |
private boolean active; |
173 |
|
|
174 |
|
/** |
175 |
|
* Run state of this worker. Supports simple versions of the usual |
177 |
|
*/ |
178 |
|
private volatile int runState; |
179 |
|
|
182 |
– |
// Runstate values. Order matters |
183 |
– |
private static final int RUNNING = 0; |
184 |
– |
private static final int SHUTDOWN = 1; |
185 |
– |
private static final int TERMINATING = 2; |
186 |
– |
private static final int TERMINATED = 3; |
187 |
– |
|
180 |
|
/** |
181 |
< |
* Activity status. When true, this worker is considered active. |
182 |
< |
* Must be false upon construction. It must be true when executing |
191 |
< |
* tasks, and BEFORE stealing a task. It must be false before |
192 |
< |
* blocking on the Pool Barrier. |
181 |
> |
* Seed for random number generator for choosing steal victims. |
182 |
> |
* Uses Marsaglia xorshift. Must be nonzero upon initialization. |
183 |
|
*/ |
184 |
< |
private boolean active; |
184 |
> |
private int seed; |
185 |
|
|
186 |
|
/** |
187 |
|
* Number of steals, transferred to pool when idle |
189 |
|
private int stealCount; |
190 |
|
|
191 |
|
/** |
192 |
< |
* Seed for random number generator for choosing steal victims |
192 |
> |
* Index of this worker in pool array. Set once by pool before |
193 |
> |
* running, and accessed directly by pool during cleanup etc. |
194 |
|
*/ |
195 |
< |
private int randomVictimSeed; |
195 |
> |
int poolIndex; |
196 |
|
|
197 |
|
/** |
198 |
< |
* Seed for embedded Jurandom |
198 |
> |
* The last barrier event waited for. Accessed in pool callback |
199 |
> |
* methods, but only by current thread. |
200 |
|
*/ |
201 |
< |
private long juRandomSeed; |
201 |
> |
long lastEventCount; |
202 |
|
|
203 |
|
/** |
204 |
< |
* The last barrier event waited for |
204 |
> |
* True if use local fifo, not default lifo, for local polling |
205 |
|
*/ |
206 |
< |
private long eventCount; |
206 |
> |
private boolean locallyFifo; |
207 |
|
|
208 |
|
/** |
209 |
|
* Creates a ForkJoinWorkerThread operating in the given pool. |
210 |
+ |
* |
211 |
|
* @param pool the pool this thread works in |
212 |
|
* @throws NullPointerException if pool is null |
213 |
|
*/ |
214 |
|
protected ForkJoinWorkerThread(ForkJoinPool pool) { |
215 |
|
if (pool == null) throw new NullPointerException(); |
216 |
|
this.pool = pool; |
217 |
< |
// remaining initialization deferred to onStart |
217 |
> |
// Note: poolIndex is set by pool during construction |
218 |
> |
// Remaining initialization is deferred to onStart |
219 |
|
} |
220 |
|
|
221 |
< |
// public access methods |
221 |
> |
// Public access methods |
222 |
|
|
223 |
|
/** |
224 |
< |
* Returns the pool hosting this thread |
224 |
> |
* Returns the pool hosting this thread. |
225 |
> |
* |
226 |
|
* @return the pool |
227 |
|
*/ |
228 |
|
public ForkJoinPool getPool() { |
234 |
|
* returned value ranges from zero to the maximum number of |
235 |
|
* threads (minus one) that have ever been created in the pool. |
236 |
|
* This method may be useful for applications that track status or |
237 |
< |
* collect results on a per-worker basis. |
238 |
< |
* @return the index number. |
237 |
> |
* collect results per-worker rather than per-task. |
238 |
> |
* |
239 |
> |
* @return the index number |
240 |
|
*/ |
241 |
|
public int getPoolIndex() { |
242 |
|
return poolIndex; |
243 |
|
} |
244 |
|
|
245 |
< |
// Access methods used by Pool |
245 |
> |
/** |
246 |
> |
* Establishes local first-in-first-out scheduling mode for forked |
247 |
> |
* tasks that are never joined. |
248 |
> |
* |
249 |
> |
* @param async if true, use locally FIFO scheduling |
250 |
> |
*/ |
251 |
> |
void setAsyncMode(boolean async) { |
252 |
> |
locallyFifo = async; |
253 |
> |
} |
254 |
> |
|
255 |
> |
// Runstate management |
256 |
> |
|
257 |
> |
// Runstate values. Order matters |
258 |
> |
private static final int RUNNING = 0; |
259 |
> |
private static final int SHUTDOWN = 1; |
260 |
> |
private static final int TERMINATING = 2; |
261 |
> |
private static final int TERMINATED = 3; |
262 |
> |
|
263 |
> |
final boolean isShutdown() { return runState >= SHUTDOWN; } |
264 |
> |
final boolean isTerminating() { return runState >= TERMINATING; } |
265 |
> |
final boolean isTerminated() { return runState == TERMINATED; } |
266 |
> |
final boolean shutdown() { return transitionRunStateTo(SHUTDOWN); } |
267 |
> |
final boolean shutdownNow() { return transitionRunStateTo(TERMINATING); } |
268 |
|
|
269 |
|
/** |
270 |
< |
* Get and clear steal count for accumulation by pool. Called |
271 |
< |
* only when known to be idle (in pool.sync and termination). |
270 |
> |
* Transitions to at least the given state. Returns true if not |
271 |
> |
* already at least at given state. |
272 |
|
*/ |
273 |
< |
final int getAndClearStealCount() { |
274 |
< |
int sc = stealCount; |
275 |
< |
stealCount = 0; |
276 |
< |
return sc; |
273 |
> |
private boolean transitionRunStateTo(int state) { |
274 |
> |
for (;;) { |
275 |
> |
int s = runState; |
276 |
> |
if (s >= state) |
277 |
> |
return false; |
278 |
> |
if (UNSAFE.compareAndSwapInt(this, runStateOffset, s, state)) |
279 |
> |
return true; |
280 |
> |
} |
281 |
|
} |
282 |
|
|
283 |
|
/** |
284 |
< |
* Returns estimate of the number of tasks in the queue, without |
263 |
< |
* correcting for transient negative values |
284 |
> |
* Tries to set status to active; fails on contention. |
285 |
|
*/ |
286 |
< |
final int getRawQueueSize() { |
287 |
< |
return sp - base; |
286 |
> |
private boolean tryActivate() { |
287 |
> |
if (!active) { |
288 |
> |
if (!pool.tryIncrementActiveCount()) |
289 |
> |
return false; |
290 |
> |
active = true; |
291 |
> |
} |
292 |
> |
return true; |
293 |
|
} |
294 |
|
|
295 |
< |
// Intrinsics-based support for queue operations. |
296 |
< |
// Currently these three (setSp, setSlot, casSlotNull) are |
297 |
< |
// usually manually inlined to improve performance |
295 |
> |
/** |
296 |
> |
* Tries to set status to inactive; fails on contention. |
297 |
> |
*/ |
298 |
> |
private boolean tryInactivate() { |
299 |
> |
if (active) { |
300 |
> |
if (!pool.tryDecrementActiveCount()) |
301 |
> |
return false; |
302 |
> |
active = false; |
303 |
> |
} |
304 |
> |
return true; |
305 |
> |
} |
306 |
|
|
307 |
|
/** |
308 |
< |
* Sets sp in store-order. |
308 |
> |
* Computes next value for random victim probe. Scans don't |
309 |
> |
* require a very high quality generator, but also not a crummy |
310 |
> |
* one. Marsaglia xor-shift is cheap and works well. |
311 |
|
*/ |
312 |
< |
private void setSp(int s) { |
313 |
< |
_unsafe.putOrderedInt(this, spOffset, s); |
312 |
> |
private static int xorShift(int r) { |
313 |
> |
r ^= r << 1; |
314 |
> |
r ^= r >>> 3; |
315 |
> |
r ^= r << 10; |
316 |
> |
return r; |
317 |
|
} |
318 |
|
|
319 |
+ |
// Lifecycle methods |
320 |
+ |
|
321 |
|
/** |
322 |
< |
* Add in store-order the given task at given slot of q to |
323 |
< |
* null. Caller must ensure q is nonnull and index is in range. |
322 |
> |
* This method is required to be public, but should never be |
323 |
> |
* called explicitly. It performs the main run loop to execute |
324 |
> |
* ForkJoinTasks. |
325 |
> |
*/ |
326 |
> |
public void run() { |
327 |
> |
Throwable exception = null; |
328 |
> |
try { |
329 |
> |
onStart(); |
330 |
> |
pool.sync(this); // await first pool event |
331 |
> |
mainLoop(); |
332 |
> |
} catch (Throwable ex) { |
333 |
> |
exception = ex; |
334 |
> |
} finally { |
335 |
> |
onTermination(exception); |
336 |
> |
} |
337 |
> |
} |
338 |
> |
|
339 |
> |
/** |
340 |
> |
* Executes tasks until shut down. |
341 |
> |
*/ |
342 |
> |
private void mainLoop() { |
343 |
> |
while (!isShutdown()) { |
344 |
> |
ForkJoinTask<?> t = pollTask(); |
345 |
> |
if (t != null || (t = pollSubmission()) != null) |
346 |
> |
t.quietlyExec(); |
347 |
> |
else if (tryInactivate()) |
348 |
> |
pool.sync(this); |
349 |
> |
} |
350 |
> |
} |
351 |
> |
|
352 |
> |
/** |
353 |
> |
* Initializes internal state after construction but before |
354 |
> |
* processing any tasks. If you override this method, you must |
355 |
> |
* invoke super.onStart() at the beginning of the method. |
356 |
> |
* Initialization requires care: Most fields must have legal |
357 |
> |
* default values, to ensure that attempted accesses from other |
358 |
> |
* threads work correctly even before this thread starts |
359 |
> |
* processing tasks. |
360 |
> |
*/ |
361 |
> |
protected void onStart() { |
362 |
> |
// Allocate while starting to improve chances of thread-local |
363 |
> |
// isolation |
364 |
> |
queue = new ForkJoinTask<?>[INITIAL_QUEUE_CAPACITY]; |
365 |
> |
// Initial value of seed need not be especially random but |
366 |
> |
// should differ across workers and must be nonzero |
367 |
> |
int p = poolIndex + 1; |
368 |
> |
seed = p + (p << 8) + (p << 16) + (p << 24); // spread bits |
369 |
> |
} |
370 |
> |
|
371 |
> |
/** |
372 |
> |
* Performs cleanup associated with termination of this worker |
373 |
> |
* thread. If you override this method, you must invoke |
374 |
> |
* {@code super.onTermination} at the end of the overridden method. |
375 |
> |
* |
376 |
> |
* @param exception the exception causing this thread to abort due |
377 |
> |
* to an unrecoverable error, or null if completed normally |
378 |
> |
*/ |
379 |
> |
protected void onTermination(Throwable exception) { |
380 |
> |
// Execute remaining local tasks unless aborting or terminating |
381 |
> |
while (exception == null && !pool.isTerminating() && base != sp) { |
382 |
> |
try { |
383 |
> |
ForkJoinTask<?> t = popTask(); |
384 |
> |
if (t != null) |
385 |
> |
t.quietlyExec(); |
386 |
> |
} catch (Throwable ex) { |
387 |
> |
exception = ex; |
388 |
> |
} |
389 |
> |
} |
390 |
> |
// Cancel other tasks, transition status, notify pool, and |
391 |
> |
// propagate exception to uncaught exception handler |
392 |
> |
try { |
393 |
> |
do {} while (!tryInactivate()); // ensure inactive |
394 |
> |
cancelTasks(); |
395 |
> |
runState = TERMINATED; |
396 |
> |
pool.workerTerminated(this); |
397 |
> |
} catch (Throwable ex) { // Shouldn't ever happen |
398 |
> |
if (exception == null) // but if so, at least rethrown |
399 |
> |
exception = ex; |
400 |
> |
} finally { |
401 |
> |
if (exception != null) |
402 |
> |
ForkJoinTask.rethrowException(exception); |
403 |
> |
} |
404 |
> |
} |
405 |
> |
|
406 |
> |
// Intrinsics-based support for queue operations. |
407 |
> |
|
408 |
> |
/** |
409 |
> |
* Adds in store-order the given task at given slot of q to null. |
410 |
> |
* Caller must ensure q is non-null and index is in range. |
411 |
|
*/ |
412 |
|
private static void setSlot(ForkJoinTask<?>[] q, int i, |
413 |
< |
ForkJoinTask<?> t){ |
414 |
< |
_unsafe.putOrderedObject(q, (i << qShift) + qBase, t); |
413 |
> |
ForkJoinTask<?> t) { |
414 |
> |
UNSAFE.putOrderedObject(q, (i << qShift) + qBase, t); |
415 |
|
} |
416 |
|
|
417 |
|
/** |
418 |
< |
* CAS given slot of q to null. Caller must ensure q is nonnull |
418 |
> |
* CAS given slot of q to null. Caller must ensure q is non-null |
419 |
|
* and index is in range. |
420 |
|
*/ |
421 |
|
private static boolean casSlotNull(ForkJoinTask<?>[] q, int i, |
422 |
|
ForkJoinTask<?> t) { |
423 |
< |
return _unsafe.compareAndSwapObject(q, (i << qShift) + qBase, t, null); |
423 |
> |
return UNSAFE.compareAndSwapObject(q, (i << qShift) + qBase, t, null); |
424 |
> |
} |
425 |
> |
|
426 |
> |
/** |
427 |
> |
* Sets sp in store-order. |
428 |
> |
*/ |
429 |
> |
private void storeSp(int s) { |
430 |
> |
UNSAFE.putOrderedInt(this, spOffset, s); |
431 |
|
} |
432 |
|
|
433 |
|
// Main queue methods |
434 |
|
|
435 |
|
/** |
436 |
|
* Pushes a task. Called only by current thread. |
437 |
< |
* @param t the task. Caller must ensure nonnull |
437 |
> |
* |
438 |
> |
* @param t the task. Caller must ensure non-null. |
439 |
|
*/ |
440 |
|
final void pushTask(ForkJoinTask<?> t) { |
441 |
|
ForkJoinTask<?>[] q = queue; |
442 |
|
int mask = q.length - 1; |
443 |
|
int s = sp; |
444 |
< |
_unsafe.putOrderedObject(q, ((s & mask) << qShift) + qBase, t); |
445 |
< |
_unsafe.putOrderedInt(this, spOffset, ++s); |
444 |
> |
setSlot(q, s & mask, t); |
445 |
> |
storeSp(++s); |
446 |
|
if ((s -= base) == 1) |
447 |
< |
pool.signalNonEmptyWorkerQueue(); |
447 |
> |
pool.signalWork(); |
448 |
|
else if (s >= mask) |
449 |
|
growQueue(); |
450 |
|
} |
452 |
|
/** |
453 |
|
* Tries to take a task from the base of the queue, failing if |
454 |
|
* either empty or contended. |
455 |
< |
* @return a task, or null if none or contended. |
455 |
> |
* |
456 |
> |
* @return a task, or null if none or contended |
457 |
|
*/ |
458 |
< |
private ForkJoinTask<?> deqTask() { |
322 |
< |
ForkJoinTask<?>[] q; |
458 |
> |
final ForkJoinTask<?> deqTask() { |
459 |
|
ForkJoinTask<?> t; |
460 |
+ |
ForkJoinTask<?>[] q; |
461 |
|
int i; |
462 |
|
int b; |
463 |
|
if (sp != (b = base) && |
464 |
|
(q = queue) != null && // must read q after b |
465 |
|
(t = q[i = (q.length - 1) & b]) != null && |
466 |
< |
_unsafe.compareAndSwapObject(q, (i << qShift) + qBase, t, null)) { |
466 |
> |
casSlotNull(q, i, t)) { |
467 |
|
base = b + 1; |
468 |
|
return t; |
469 |
|
} |
471 |
|
} |
472 |
|
|
473 |
|
/** |
474 |
< |
* Returns a popped task, or null if empty. Called only by |
475 |
< |
* current thread. |
474 |
> |
* Returns a popped task, or null if empty. Ensures active status |
475 |
> |
* if non-null. Called only by current thread. |
476 |
|
*/ |
477 |
|
final ForkJoinTask<?> popTask() { |
341 |
– |
ForkJoinTask<?> t; |
342 |
– |
int i; |
343 |
– |
ForkJoinTask<?>[] q = queue; |
344 |
– |
int mask = q.length - 1; |
478 |
|
int s = sp; |
479 |
< |
if (s != base && |
480 |
< |
(t = q[i = (s - 1) & mask]) != null && |
481 |
< |
_unsafe.compareAndSwapObject(q, (i << qShift) + qBase, t, null)) { |
482 |
< |
_unsafe.putOrderedInt(this, spOffset, s - 1); |
483 |
< |
return t; |
479 |
> |
while (s != base) { |
480 |
> |
if (tryActivate()) { |
481 |
> |
ForkJoinTask<?>[] q = queue; |
482 |
> |
int mask = q.length - 1; |
483 |
> |
int i = (s - 1) & mask; |
484 |
> |
ForkJoinTask<?> t = q[i]; |
485 |
> |
if (t == null || !casSlotNull(q, i, t)) |
486 |
> |
break; |
487 |
> |
storeSp(s - 1); |
488 |
> |
return t; |
489 |
> |
} |
490 |
|
} |
491 |
|
return null; |
492 |
|
} |
494 |
|
/** |
495 |
|
* Specialized version of popTask to pop only if |
496 |
|
* topmost element is the given task. Called only |
497 |
< |
* by current thread. |
498 |
< |
* @param t the task. Caller must ensure nonnull |
497 |
> |
* by current thread while active. |
498 |
> |
* |
499 |
> |
* @param t the task. Caller must ensure non-null. |
500 |
|
*/ |
501 |
|
final boolean unpushTask(ForkJoinTask<?> t) { |
502 |
|
ForkJoinTask<?>[] q = queue; |
503 |
|
int mask = q.length - 1; |
504 |
|
int s = sp - 1; |
505 |
< |
if (_unsafe.compareAndSwapObject(q, ((s & mask) << qShift) + qBase, |
506 |
< |
t, null)) { |
367 |
< |
_unsafe.putOrderedInt(this, spOffset, s); |
505 |
> |
if (casSlotNull(q, s & mask, t)) { |
506 |
> |
storeSp(s); |
507 |
|
return true; |
508 |
|
} |
509 |
|
return false; |
510 |
|
} |
511 |
|
|
512 |
|
/** |
513 |
< |
* Returns next task to pop. |
513 |
> |
* Returns next task. |
514 |
|
*/ |
515 |
|
final ForkJoinTask<?> peekTask() { |
516 |
|
ForkJoinTask<?>[] q = queue; |
517 |
< |
return q == null? null : q[(sp - 1) & (q.length - 1)]; |
517 |
> |
if (q == null) |
518 |
> |
return null; |
519 |
> |
int mask = q.length - 1; |
520 |
> |
int i = locallyFifo ? base : (sp - 1); |
521 |
> |
return q[i & mask]; |
522 |
|
} |
523 |
|
|
524 |
|
/** |
545 |
|
t = null; |
546 |
|
setSlot(newQ, b & newMask, t); |
547 |
|
} while (++b != bf); |
548 |
< |
pool.signalIdleWorkers(false); |
406 |
< |
} |
407 |
< |
|
408 |
< |
// Runstate management |
409 |
< |
|
410 |
< |
final boolean isShutdown() { return runState >= SHUTDOWN; } |
411 |
< |
final boolean isTerminating() { return runState >= TERMINATING; } |
412 |
< |
final boolean isTerminated() { return runState == TERMINATED; } |
413 |
< |
final boolean shutdown() { return transitionRunStateTo(SHUTDOWN); } |
414 |
< |
final boolean shutdownNow() { return transitionRunStateTo(TERMINATING); } |
415 |
< |
|
416 |
< |
/** |
417 |
< |
* Transition to at least the given state. Return true if not |
418 |
< |
* already at least given state. |
419 |
< |
*/ |
420 |
< |
private boolean transitionRunStateTo(int state) { |
421 |
< |
for (;;) { |
422 |
< |
int s = runState; |
423 |
< |
if (s >= state) |
424 |
< |
return false; |
425 |
< |
if (_unsafe.compareAndSwapInt(this, runStateOffset, s, state)) |
426 |
< |
return true; |
427 |
< |
} |
428 |
< |
} |
429 |
< |
|
430 |
< |
/** |
431 |
< |
* Ensure status is active and if necessary adjust pool active count |
432 |
< |
*/ |
433 |
< |
final void activate() { |
434 |
< |
if (!active) { |
435 |
< |
active = true; |
436 |
< |
pool.incrementActiveCount(); |
437 |
< |
} |
548 |
> |
pool.signalWork(); |
549 |
|
} |
550 |
|
|
551 |
|
/** |
552 |
< |
* Ensure status is inactive and if necessary adjust pool active count |
552 |
> |
* Tries to steal a task from another worker. Starts at a random |
553 |
> |
* index of workers array, and probes workers until finding one |
554 |
> |
* with non-empty queue or finding that all are empty. It |
555 |
> |
* randomly selects the first n probes. If these are empty, it |
556 |
> |
* resorts to a full circular traversal, which is necessary to |
557 |
> |
* accurately set active status by caller. Also restarts if pool |
558 |
> |
* events occurred since last scan, which forces refresh of |
559 |
> |
* workers array, in case barrier was associated with resize. |
560 |
> |
* |
561 |
> |
* This method must be both fast and quiet -- usually avoiding |
562 |
> |
* memory accesses that could disrupt cache sharing etc other than |
563 |
> |
* those needed to check for and take tasks. This accounts for, |
564 |
> |
* among other things, updating random seed in place without |
565 |
> |
* storing it until exit. |
566 |
> |
* |
567 |
> |
* @return a task, or null if none found |
568 |
|
*/ |
569 |
< |
final void inactivate() { |
570 |
< |
if (active) { |
571 |
< |
active = false; |
572 |
< |
pool.decrementActiveCount(); |
573 |
< |
} |
569 |
> |
private ForkJoinTask<?> scan() { |
570 |
> |
ForkJoinTask<?> t = null; |
571 |
> |
int r = seed; // extract once to keep scan quiet |
572 |
> |
ForkJoinWorkerThread[] ws; // refreshed on outer loop |
573 |
> |
int mask; // must be power 2 minus 1 and > 0 |
574 |
> |
outer:do { |
575 |
> |
if ((ws = pool.workers) != null && (mask = ws.length - 1) > 0) { |
576 |
> |
int idx = r; |
577 |
> |
int probes = ~mask; // use random index while negative |
578 |
> |
for (;;) { |
579 |
> |
r = xorShift(r); // update random seed |
580 |
> |
ForkJoinWorkerThread v = ws[mask & idx]; |
581 |
> |
if (v == null || v.sp == v.base) { |
582 |
> |
if (probes <= mask) |
583 |
> |
idx = (probes++ < 0) ? r : (idx + 1); |
584 |
> |
else |
585 |
> |
break; |
586 |
> |
} |
587 |
> |
else if (!tryActivate() || (t = v.deqTask()) == null) |
588 |
> |
continue outer; // restart on contention |
589 |
> |
else |
590 |
> |
break outer; |
591 |
> |
} |
592 |
> |
} |
593 |
> |
} while (pool.hasNewSyncEvent(this)); // retry on pool events |
594 |
> |
seed = r; |
595 |
> |
return t; |
596 |
|
} |
597 |
|
|
450 |
– |
// Lifecycle methods |
451 |
– |
|
598 |
|
/** |
599 |
< |
* Initializes internal state after construction but before |
600 |
< |
* processing any tasks. If you override this method, you must |
601 |
< |
* invoke super.onStart() at the beginning of the method. |
456 |
< |
* Initialization requires care: Most fields must have legal |
457 |
< |
* default values, to ensure that attempted accesses from other |
458 |
< |
* threads work correctly even before this thread starts |
459 |
< |
* processing tasks. |
599 |
> |
* Gets and removes a local or stolen task. |
600 |
> |
* |
601 |
> |
* @return a task, if available |
602 |
|
*/ |
603 |
< |
protected void onStart() { |
604 |
< |
juRandomSeed = randomSeedGenerator.nextLong(); |
605 |
< |
do;while((randomVictimSeed = nextRandomInt()) == 0); // must be nonzero |
606 |
< |
if (queue == null) |
607 |
< |
queue = new ForkJoinTask<?>[INITIAL_QUEUE_CAPACITY]; |
466 |
< |
|
467 |
< |
// Heuristically allow one initial thread to warm up; others wait |
468 |
< |
if (poolIndex < pool.getParallelism() - 1) { |
469 |
< |
eventCount = pool.sync(this, 0); |
470 |
< |
activate(); |
471 |
< |
} |
603 |
> |
final ForkJoinTask<?> pollTask() { |
604 |
> |
ForkJoinTask<?> t = locallyFifo ? deqTask() : popTask(); |
605 |
> |
if (t == null && (t = scan()) != null) |
606 |
> |
++stealCount; |
607 |
> |
return t; |
608 |
|
} |
609 |
|
|
610 |
|
/** |
611 |
< |
* Perform cleanup associated with termination of this worker |
476 |
< |
* thread. If you override this method, you must invoke |
477 |
< |
* super.onTermination at the end of the overridden method. |
611 |
> |
* Gets a local task. |
612 |
|
* |
613 |
< |
* @param exception the exception causing this thread to abort due |
480 |
< |
* to an unrecoverable error, or null if completed normally. |
613 |
> |
* @return a task, if available |
614 |
|
*/ |
615 |
< |
protected void onTermination(Throwable exception) { |
616 |
< |
try { |
484 |
< |
clearLocalTasks(); |
485 |
< |
inactivate(); |
486 |
< |
cancelTasks(); |
487 |
< |
} finally { |
488 |
< |
terminate(exception); |
489 |
< |
} |
615 |
> |
final ForkJoinTask<?> pollLocalTask() { |
616 |
> |
return locallyFifo ? deqTask() : popTask(); |
617 |
|
} |
618 |
|
|
619 |
|
/** |
620 |
< |
* Notify pool of termination and, if exception is nonnull, |
621 |
< |
* rethrow it to trigger this thread's uncaughtExceptionHandler |
620 |
> |
* Returns a pool submission, if one exists, activating first. |
621 |
> |
* |
622 |
> |
* @return a submission, if available |
623 |
|
*/ |
624 |
< |
private void terminate(Throwable exception) { |
625 |
< |
transitionRunStateTo(TERMINATED); |
626 |
< |
try { |
627 |
< |
pool.workerTerminated(this); |
628 |
< |
} finally { |
629 |
< |
if (exception != null) |
502 |
< |
ForkJoinTask.rethrowException(exception); |
624 |
> |
private ForkJoinTask<?> pollSubmission() { |
625 |
> |
ForkJoinPool p = pool; |
626 |
> |
while (p.hasQueuedSubmissions()) { |
627 |
> |
ForkJoinTask<?> t; |
628 |
> |
if (tryActivate() && (t = p.pollSubmission()) != null) |
629 |
> |
return t; |
630 |
|
} |
631 |
+ |
return null; |
632 |
|
} |
633 |
|
|
634 |
< |
/** |
507 |
< |
* Run local tasks on exit from main. |
508 |
< |
*/ |
509 |
< |
private void clearLocalTasks() { |
510 |
< |
while (base != sp && !pool.isTerminating()) { |
511 |
< |
ForkJoinTask<?> t = popTask(); |
512 |
< |
if (t != null) { |
513 |
< |
activate(); // ensure active status |
514 |
< |
t.quietlyExec(); |
515 |
< |
} |
516 |
< |
} |
517 |
< |
} |
634 |
> |
// Methods accessed only by Pool |
635 |
|
|
636 |
|
/** |
637 |
|
* Removes and cancels all tasks in queue. Can be called from any |
638 |
|
* thread. |
639 |
|
*/ |
640 |
|
final void cancelTasks() { |
641 |
< |
while (base != sp) { |
642 |
< |
ForkJoinTask<?> t = deqTask(); |
643 |
< |
if (t != null) |
527 |
< |
t.cancelIgnoringExceptions(); |
528 |
< |
} |
641 |
> |
ForkJoinTask<?> t; |
642 |
> |
while (base != sp && (t = deqTask()) != null) |
643 |
> |
t.cancelIgnoringExceptions(); |
644 |
|
} |
645 |
|
|
646 |
|
/** |
647 |
< |
* This method is required to be public, but should never be |
648 |
< |
* called explicitly. It performs the main run loop to execute |
649 |
< |
* ForkJoinTasks. |
647 |
> |
* Drains tasks to given collection c. |
648 |
> |
* |
649 |
> |
* @return the number of tasks drained |
650 |
|
*/ |
651 |
< |
public void run() { |
652 |
< |
Throwable exception = null; |
653 |
< |
try { |
654 |
< |
onStart(); |
655 |
< |
while (!isShutdown()) |
656 |
< |
step(); |
542 |
< |
} catch (Throwable ex) { |
543 |
< |
exception = ex; |
544 |
< |
} finally { |
545 |
< |
onTermination(exception); |
651 |
> |
final int drainTasksTo(Collection<ForkJoinTask<?>> c) { |
652 |
> |
int n = 0; |
653 |
> |
ForkJoinTask<?> t; |
654 |
> |
while (base != sp && (t = deqTask()) != null) { |
655 |
> |
c.add(t); |
656 |
> |
++n; |
657 |
|
} |
658 |
+ |
return n; |
659 |
|
} |
660 |
|
|
661 |
|
/** |
662 |
< |
* Main top-level action. |
662 |
> |
* Gets and clears steal count for accumulation by pool. Called |
663 |
> |
* only when known to be idle (in pool.sync and termination). |
664 |
|
*/ |
665 |
< |
private void step() { |
666 |
< |
ForkJoinTask<?> t = sp != base? popTask() : null; |
667 |
< |
if (t != null || (t = scan(null, true)) != null) { |
668 |
< |
activate(); |
556 |
< |
t.quietlyExec(); |
557 |
< |
} |
558 |
< |
else { |
559 |
< |
inactivate(); |
560 |
< |
eventCount = pool.sync(this, eventCount); |
561 |
< |
} |
665 |
> |
final int getAndClearStealCount() { |
666 |
> |
int sc = stealCount; |
667 |
> |
stealCount = 0; |
668 |
> |
return sc; |
669 |
|
} |
670 |
|
|
564 |
– |
// scanning for and stealing tasks |
565 |
– |
|
671 |
|
/** |
672 |
< |
* Computes next value for random victim probe. Scans don't |
673 |
< |
* require a very high quality generator, but also not a crummy |
569 |
< |
* one. Marsaglia xor-shift is cheap and works well. |
672 |
> |
* Returns true if at least one worker in the given array appears |
673 |
> |
* to have at least one queued task. |
674 |
|
* |
675 |
< |
* This is currently unused, and manually inlined |
675 |
> |
* @param ws array of workers |
676 |
|
*/ |
677 |
< |
private static int xorShift(int r) { |
678 |
< |
r ^= r << 1; |
679 |
< |
r ^= r >>> 3; |
680 |
< |
r ^= r << 10; |
681 |
< |
return r; |
682 |
< |
} |
683 |
< |
|
684 |
< |
/** |
581 |
< |
* Tries to steal a task from another worker and/or, if enabled, |
582 |
< |
* submission queue. Starts at a random index of workers array, |
583 |
< |
* and probes workers until finding one with non-empty queue or |
584 |
< |
* finding that all are empty. It randomly selects the first n-1 |
585 |
< |
* probes. If these are empty, it resorts to full circular |
586 |
< |
* traversal, which is necessary to accurately set active status |
587 |
< |
* by caller. Also restarts if pool barrier has tripped since last |
588 |
< |
* scan, which forces refresh of workers array, in case barrier |
589 |
< |
* was associated with resize. |
590 |
< |
* |
591 |
< |
* This method must be both fast and quiet -- usually avoiding |
592 |
< |
* memory accesses that could disrupt cache sharing etc other than |
593 |
< |
* those needed to check for and take tasks. This accounts for, |
594 |
< |
* among other things, updating random seed in place without |
595 |
< |
* storing it until exit. (Note that we only need to store it if |
596 |
< |
* we found a task; otherwise it doesn't matter if we start at the |
597 |
< |
* same place next time.) |
598 |
< |
* |
599 |
< |
* @param joinMe if non null; exit early if done |
600 |
< |
* @param checkSubmissions true if OK to take submissions |
601 |
< |
* @return a task, or null if none found |
602 |
< |
*/ |
603 |
< |
private ForkJoinTask<?> scan(ForkJoinTask<?> joinMe, |
604 |
< |
boolean checkSubmissions) { |
605 |
< |
ForkJoinPool p = pool; |
606 |
< |
if (p == null) // Never null, but avoids |
607 |
< |
return null; // implicit nullchecks below |
608 |
< |
int r = randomVictimSeed; // extract once to keep scan quiet |
609 |
< |
restart: // outer loop refreshes ws array |
610 |
< |
while (joinMe == null || joinMe.status >= 0) { |
611 |
< |
int mask; |
612 |
< |
ForkJoinWorkerThread[] ws = p.workers; |
613 |
< |
if (ws != null && (mask = ws.length - 1) > 0) { |
614 |
< |
int probes = -mask; // use random index while negative |
615 |
< |
int idx = r; |
616 |
< |
for (;;) { |
617 |
< |
ForkJoinWorkerThread v; |
618 |
< |
// inlined xorshift to update seed |
619 |
< |
r ^= r << 1; r ^= r >>> 3; r ^= r << 10; |
620 |
< |
if ((v = ws[mask & idx]) != null && v.sp != v.base) { |
621 |
< |
ForkJoinTask<?> t; |
622 |
< |
activate(); |
623 |
< |
if ((joinMe == null || joinMe.status >= 0) && |
624 |
< |
(t = v.deqTask()) != null) { |
625 |
< |
randomVictimSeed = r; |
626 |
< |
++stealCount; |
627 |
< |
return t; |
628 |
< |
} |
629 |
< |
continue restart; // restart on contention |
630 |
< |
} |
631 |
< |
if ((probes >> 1) <= mask) // n-1 random then circular |
632 |
< |
idx = (probes++ < 0)? r : (idx + 1); |
633 |
< |
else |
634 |
< |
break; |
677 |
> |
static boolean hasQueuedTasks(ForkJoinWorkerThread[] ws) { |
678 |
> |
if (ws != null) { |
679 |
> |
int len = ws.length; |
680 |
> |
for (int j = 0; j < 2; ++j) { // need two passes for clean sweep |
681 |
> |
for (int i = 0; i < len; ++i) { |
682 |
> |
ForkJoinWorkerThread w = ws[i]; |
683 |
> |
if (w != null && w.sp != w.base) |
684 |
> |
return true; |
685 |
|
} |
686 |
|
} |
637 |
– |
if (checkSubmissions && p.hasQueuedSubmissions()) { |
638 |
– |
activate(); |
639 |
– |
ForkJoinTask<?> t = p.pollSubmission(); |
640 |
– |
if (t != null) |
641 |
– |
return t; |
642 |
– |
} |
643 |
– |
else { |
644 |
– |
long ec = eventCount; // restart on pool event |
645 |
– |
if ((eventCount = p.getEventCount()) == ec) |
646 |
– |
break; |
647 |
– |
} |
648 |
– |
} |
649 |
– |
return null; |
650 |
– |
} |
651 |
– |
|
652 |
– |
/** |
653 |
– |
* Callback from pool.sync to rescan before blocking. If a |
654 |
– |
* task is found, it is pushed so it can be executed upon return. |
655 |
– |
* @return true if found and pushed a task |
656 |
– |
*/ |
657 |
– |
final boolean prescan() { |
658 |
– |
ForkJoinTask<?> t = scan(null, true); |
659 |
– |
if (t != null) { |
660 |
– |
pushTask(t); |
661 |
– |
return true; |
662 |
– |
} |
663 |
– |
else { |
664 |
– |
inactivate(); |
665 |
– |
return false; |
687 |
|
} |
688 |
+ |
return false; |
689 |
|
} |
690 |
|
|
691 |
< |
// Support for ForkJoinTask methods |
670 |
< |
|
671 |
< |
/** |
672 |
< |
* Scan, returning early if joinMe done |
673 |
< |
*/ |
674 |
< |
final ForkJoinTask<?> scanWhileJoining(ForkJoinTask<?> joinMe) { |
675 |
< |
ForkJoinTask<?> t = scan(joinMe, false); |
676 |
< |
if (t != null && joinMe.status < 0 && sp == base) { |
677 |
< |
pushTask(t); // unsteal if done and this task would be stealable |
678 |
< |
t = null; |
679 |
< |
} |
680 |
< |
return t; |
681 |
< |
} |
682 |
< |
|
683 |
< |
/** |
684 |
< |
* Pops or steals a task |
685 |
< |
* @return task, or null if none available |
686 |
< |
*/ |
687 |
< |
final ForkJoinTask<?> pollLocalOrStolenTask() { |
688 |
< |
ForkJoinTask<?> t; |
689 |
< |
return (t = popTask()) == null? scan(null, false) : t; |
690 |
< |
} |
691 |
< |
|
692 |
< |
/** |
693 |
< |
* Runs tasks until pool isQuiescent |
694 |
< |
*/ |
695 |
< |
final void helpQuiescePool() { |
696 |
< |
for (;;) { |
697 |
< |
ForkJoinTask<?> t = pollLocalOrStolenTask(); |
698 |
< |
if (t != null) { |
699 |
< |
activate(); |
700 |
< |
t.quietlyExec(); |
701 |
< |
} |
702 |
< |
else { |
703 |
< |
inactivate(); |
704 |
< |
if (pool.isQuiescent()) { |
705 |
< |
activate(); // re-activate on exit |
706 |
< |
break; |
707 |
< |
} |
708 |
< |
} |
709 |
< |
} |
710 |
< |
} |
691 |
> |
// Support methods for ForkJoinTask |
692 |
|
|
693 |
|
/** |
694 |
|
* Returns an estimate of the number of tasks in the queue. |
695 |
|
*/ |
696 |
|
final int getQueueSize() { |
697 |
< |
int n = sp - base; |
698 |
< |
return n <= 0? 0 : n; // suppress momentarily negative values |
697 |
> |
// suppress momentarily negative values |
698 |
> |
return Math.max(0, sp - base); |
699 |
|
} |
700 |
|
|
701 |
|
/** |
707 |
|
return (sp - base) - (pool.getIdleThreadCount() >>> 1); |
708 |
|
} |
709 |
|
|
729 |
– |
// Per-worker exported random numbers |
730 |
– |
|
731 |
– |
// Same constants as java.util.Random |
732 |
– |
final static long JURandomMultiplier = 0x5DEECE66DL; |
733 |
– |
final static long JURandomAddend = 0xBL; |
734 |
– |
final static long JURandomMask = (1L << 48) - 1; |
735 |
– |
|
736 |
– |
private final int nextJURandom(int bits) { |
737 |
– |
long next = (juRandomSeed * JURandomMultiplier + JURandomAddend) & |
738 |
– |
JURandomMask; |
739 |
– |
juRandomSeed = next; |
740 |
– |
return (int)(next >>> (48 - bits)); |
741 |
– |
} |
742 |
– |
|
743 |
– |
private final int nextJURandomInt(int n) { |
744 |
– |
if (n <= 0) |
745 |
– |
throw new IllegalArgumentException("n must be positive"); |
746 |
– |
int bits = nextJURandom(31); |
747 |
– |
if ((n & -n) == n) |
748 |
– |
return (int)((n * (long)bits) >> 31); |
749 |
– |
|
750 |
– |
for (;;) { |
751 |
– |
int val = bits % n; |
752 |
– |
if (bits - val + (n-1) >= 0) |
753 |
– |
return val; |
754 |
– |
bits = nextJURandom(31); |
755 |
– |
} |
756 |
– |
} |
757 |
– |
|
758 |
– |
private final long nextJURandomLong() { |
759 |
– |
return ((long)(nextJURandom(32)) << 32) + nextJURandom(32); |
760 |
– |
} |
761 |
– |
|
762 |
– |
private final long nextJURandomLong(long n) { |
763 |
– |
if (n <= 0) |
764 |
– |
throw new IllegalArgumentException("n must be positive"); |
765 |
– |
long offset = 0; |
766 |
– |
while (n >= Integer.MAX_VALUE) { // randomly pick half range |
767 |
– |
int bits = nextJURandom(2); // 2nd bit for odd vs even split |
768 |
– |
long half = n >>> 1; |
769 |
– |
long nextn = ((bits & 2) == 0)? half : n - half; |
770 |
– |
if ((bits & 1) == 0) |
771 |
– |
offset += n - nextn; |
772 |
– |
n = nextn; |
773 |
– |
} |
774 |
– |
return offset + nextJURandomInt((int)n); |
775 |
– |
} |
776 |
– |
|
777 |
– |
private final double nextJURandomDouble() { |
778 |
– |
return (((long)(nextJURandom(26)) << 27) + nextJURandom(27)) |
779 |
– |
/ (double)(1L << 53); |
780 |
– |
} |
781 |
– |
|
710 |
|
/** |
711 |
< |
* Returns a random integer using a per-worker random |
784 |
< |
* number generator with the same properties as |
785 |
< |
* {@link java.util.Random#nextInt} |
786 |
< |
* @return the next pseudorandom, uniformly distributed {@code int} |
787 |
< |
* value from this worker's random number generator's sequence |
711 |
> |
* Scans, returning early if joinMe done. |
712 |
|
*/ |
713 |
< |
public static int nextRandomInt() { |
714 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
715 |
< |
nextJURandom(32); |
713 |
> |
final ForkJoinTask<?> scanWhileJoining(ForkJoinTask<?> joinMe) { |
714 |
> |
ForkJoinTask<?> t = pollTask(); |
715 |
> |
if (t != null && joinMe.status < 0 && sp == base) { |
716 |
> |
pushTask(t); // unsteal if done and this task would be stealable |
717 |
> |
t = null; |
718 |
> |
} |
719 |
> |
return t; |
720 |
|
} |
721 |
|
|
722 |
|
/** |
723 |
< |
* Returns a random integer using a per-worker random |
796 |
< |
* number generator with the same properties as |
797 |
< |
* {@link java.util.Random#nextInt(int)} |
798 |
< |
* @param n the bound on the random number to be returned. Must be |
799 |
< |
* positive. |
800 |
< |
* @return the next pseudorandom, uniformly distributed {@code int} |
801 |
< |
* value between {@code 0} (inclusive) and {@code n} (exclusive) |
802 |
< |
* from this worker's random number generator's sequence |
803 |
< |
* @throws IllegalArgumentException if n is not positive |
723 |
> |
* Runs tasks until {@code pool.isQuiescent()}. |
724 |
|
*/ |
725 |
< |
public static int nextRandomInt(int n) { |
726 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
727 |
< |
nextJURandomInt(n); |
725 |
> |
final void helpQuiescePool() { |
726 |
> |
for (;;) { |
727 |
> |
ForkJoinTask<?> t = pollTask(); |
728 |
> |
if (t != null) |
729 |
> |
t.quietlyExec(); |
730 |
> |
else if (tryInactivate() && pool.isQuiescent()) |
731 |
> |
break; |
732 |
> |
} |
733 |
> |
do {} while (!tryActivate()); // re-activate on exit |
734 |
|
} |
735 |
|
|
736 |
< |
/** |
737 |
< |
* Returns a random long using a per-worker random |
738 |
< |
* number generator with the same properties as |
739 |
< |
* {@link java.util.Random#nextLong} |
740 |
< |
* @return the next pseudorandom, uniformly distributed {@code long} |
741 |
< |
* value from this worker's random number generator's sequence |
742 |
< |
*/ |
743 |
< |
public static long nextRandomLong() { |
744 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
745 |
< |
nextJURandomLong(); |
736 |
> |
// Temporary Unsafe mechanics for preliminary release |
737 |
> |
private static Unsafe getUnsafe() throws Throwable { |
738 |
> |
try { |
739 |
> |
return Unsafe.getUnsafe(); |
740 |
> |
} catch (SecurityException se) { |
741 |
> |
try { |
742 |
> |
return java.security.AccessController.doPrivileged |
743 |
> |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
744 |
> |
public Unsafe run() throws Exception { |
745 |
> |
return getUnsafePrivileged(); |
746 |
> |
}}); |
747 |
> |
} catch (java.security.PrivilegedActionException e) { |
748 |
> |
throw e.getCause(); |
749 |
> |
} |
750 |
> |
} |
751 |
|
} |
752 |
|
|
753 |
< |
/** |
754 |
< |
* Returns a random integer using a per-worker random |
755 |
< |
* number generator with the same properties as |
756 |
< |
* {@link java.util.Random#nextInt(int)} |
757 |
< |
* @param n the bound on the random number to be returned. Must be |
827 |
< |
* positive. |
828 |
< |
* @return the next pseudorandom, uniformly distributed {@code int} |
829 |
< |
* value between {@code 0} (inclusive) and {@code n} (exclusive) |
830 |
< |
* from this worker's random number generator's sequence |
831 |
< |
* @throws IllegalArgumentException if n is not positive |
832 |
< |
*/ |
833 |
< |
public static long nextRandomLong(long n) { |
834 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
835 |
< |
nextJURandomLong(n); |
753 |
> |
private static Unsafe getUnsafePrivileged() |
754 |
> |
throws NoSuchFieldException, IllegalAccessException { |
755 |
> |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
756 |
> |
f.setAccessible(true); |
757 |
> |
return (Unsafe) f.get(null); |
758 |
|
} |
759 |
|
|
760 |
< |
/** |
761 |
< |
* Returns a random double using a per-worker random |
762 |
< |
* number generator with the same properties as |
763 |
< |
* {@link java.util.Random#nextDouble} |
842 |
< |
* @return the next pseudorandom, uniformly distributed {@code double} |
843 |
< |
* value between {@code 0.0} and {@code 1.0} from this |
844 |
< |
* worker's random number generator's sequence |
845 |
< |
*/ |
846 |
< |
public static double nextRandomDouble() { |
847 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
848 |
< |
nextJURandomDouble(); |
760 |
> |
private static long fieldOffset(String fieldName) |
761 |
> |
throws NoSuchFieldException { |
762 |
> |
return UNSAFE.objectFieldOffset |
763 |
> |
(ForkJoinWorkerThread.class.getDeclaredField(fieldName)); |
764 |
|
} |
765 |
|
|
766 |
< |
// Temporary Unsafe mechanics for preliminary release |
852 |
< |
|
853 |
< |
static final Unsafe _unsafe; |
766 |
> |
static final Unsafe UNSAFE; |
767 |
|
static final long baseOffset; |
768 |
|
static final long spOffset; |
769 |
+ |
static final long runStateOffset; |
770 |
|
static final long qBase; |
771 |
|
static final int qShift; |
858 |
– |
static final long runStateOffset; |
772 |
|
static { |
773 |
|
try { |
774 |
< |
if (ForkJoinWorkerThread.class.getClassLoader() != null) { |
775 |
< |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
776 |
< |
f.setAccessible(true); |
777 |
< |
_unsafe = (Unsafe)f.get(null); |
778 |
< |
} |
779 |
< |
else |
867 |
< |
_unsafe = Unsafe.getUnsafe(); |
868 |
< |
baseOffset = _unsafe.objectFieldOffset |
869 |
< |
(ForkJoinWorkerThread.class.getDeclaredField("base")); |
870 |
< |
spOffset = _unsafe.objectFieldOffset |
871 |
< |
(ForkJoinWorkerThread.class.getDeclaredField("sp")); |
872 |
< |
runStateOffset = _unsafe.objectFieldOffset |
873 |
< |
(ForkJoinWorkerThread.class.getDeclaredField("runState")); |
874 |
< |
qBase = _unsafe.arrayBaseOffset(ForkJoinTask[].class); |
875 |
< |
int s = _unsafe.arrayIndexScale(ForkJoinTask[].class); |
774 |
> |
UNSAFE = getUnsafe(); |
775 |
> |
baseOffset = fieldOffset("base"); |
776 |
> |
spOffset = fieldOffset("sp"); |
777 |
> |
runStateOffset = fieldOffset("runState"); |
778 |
> |
qBase = UNSAFE.arrayBaseOffset(ForkJoinTask[].class); |
779 |
> |
int s = UNSAFE.arrayIndexScale(ForkJoinTask[].class); |
780 |
|
if ((s & (s-1)) != 0) |
781 |
|
throw new Error("data type scale not a power of two"); |
782 |
|
qShift = 31 - Integer.numberOfLeadingZeros(s); |
783 |
< |
} catch (Exception e) { |
783 |
> |
} catch (Throwable e) { |
784 |
|
throw new RuntimeException("Could not initialize intrinsics", e); |
785 |
|
} |
786 |
|
} |