Fri, 24 Jun 2016 17:12:13 +0800
[Code Reorganization] Removed GC related modifications made by Loongson, for example, UseOldNUMA.
1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #ifndef SHARE_VM_UTILITIES_TASKQUEUE_HPP
26 #define SHARE_VM_UTILITIES_TASKQUEUE_HPP
28 #include "memory/allocation.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "runtime/mutex.hpp"
31 #include "utilities/stack.hpp"
32 #ifdef TARGET_OS_ARCH_linux_x86
33 # include "orderAccess_linux_x86.inline.hpp"
34 #endif
35 #ifdef TARGET_OS_ARCH_linux_sparc
36 # include "orderAccess_linux_sparc.inline.hpp"
37 #endif
38 #ifdef TARGET_OS_ARCH_linux_zero
39 # include "orderAccess_linux_zero.inline.hpp"
40 #endif
41 #ifdef TARGET_OS_ARCH_solaris_x86
42 # include "orderAccess_solaris_x86.inline.hpp"
43 #endif
44 #ifdef TARGET_OS_ARCH_solaris_sparc
45 # include "orderAccess_solaris_sparc.inline.hpp"
46 #endif
47 #ifdef TARGET_OS_ARCH_windows_x86
48 # include "orderAccess_windows_x86.inline.hpp"
49 #endif
50 #ifdef TARGET_OS_ARCH_linux_arm
51 # include "orderAccess_linux_arm.inline.hpp"
52 #endif
53 #ifdef TARGET_OS_ARCH_linux_ppc
54 # include "orderAccess_linux_ppc.inline.hpp"
55 #endif
56 #ifdef TARGET_OS_ARCH_aix_ppc
57 # include "orderAccess_aix_ppc.inline.hpp"
58 #endif
59 #ifdef TARGET_OS_ARCH_bsd_x86
60 # include "orderAccess_bsd_x86.inline.hpp"
61 #endif
62 #ifdef TARGET_OS_ARCH_bsd_zero
63 # include "orderAccess_bsd_zero.inline.hpp"
64 #endif
66 // Simple TaskQueue stats that are collected by default in debug builds.
68 #if !defined(TASKQUEUE_STATS) && defined(ASSERT)
69 #define TASKQUEUE_STATS 1
70 #elif !defined(TASKQUEUE_STATS)
71 #define TASKQUEUE_STATS 0
72 #endif
74 #if TASKQUEUE_STATS
75 #define TASKQUEUE_STATS_ONLY(code) code
76 #else
77 #define TASKQUEUE_STATS_ONLY(code)
78 #endif // TASKQUEUE_STATS
80 #if TASKQUEUE_STATS
81 class TaskQueueStats {
82 public:
83 enum StatId {
84 push, // number of taskqueue pushes
85 pop, // number of taskqueue pops
86 pop_slow, // subset of taskqueue pops that were done slow-path
87 steal_attempt, // number of taskqueue steal attempts
88 steal, // number of taskqueue steals
89 overflow, // number of overflow pushes
90 overflow_max_len, // max length of overflow stack
91 last_stat_id
92 };
94 public:
95 inline TaskQueueStats() { reset(); }
97 inline void record_push() { ++_stats[push]; }
98 inline void record_pop() { ++_stats[pop]; }
99 inline void record_pop_slow() { record_pop(); ++_stats[pop_slow]; }
100 inline void record_steal(bool success);
101 inline void record_overflow(size_t new_length);
103 TaskQueueStats & operator +=(const TaskQueueStats & addend);
105 inline size_t get(StatId id) const { return _stats[id]; }
106 inline const size_t* get() const { return _stats; }
108 inline void reset();
110 // Print the specified line of the header (does not include a line separator).
111 static void print_header(unsigned int line, outputStream* const stream = tty,
112 unsigned int width = 10);
113 // Print the statistics (does not include a line separator).
114 void print(outputStream* const stream = tty, unsigned int width = 10) const;
116 DEBUG_ONLY(void verify() const;)
118 private:
119 size_t _stats[last_stat_id];
120 static const char * const _names[last_stat_id];
121 };
123 void TaskQueueStats::record_steal(bool success) {
124 ++_stats[steal_attempt];
125 if (success) ++_stats[steal];
126 }
128 void TaskQueueStats::record_overflow(size_t new_len) {
129 ++_stats[overflow];
130 if (new_len > _stats[overflow_max_len]) _stats[overflow_max_len] = new_len;
131 }
133 void TaskQueueStats::reset() {
134 memset(_stats, 0, sizeof(_stats));
135 }
136 #endif // TASKQUEUE_STATS
138 // TaskQueueSuper collects functionality common to all GenericTaskQueue instances.
140 template <unsigned int N, MEMFLAGS F>
141 class TaskQueueSuper: public CHeapObj<F> {
142 protected:
143 // Internal type for indexing the queue; also used for the tag.
144 typedef NOT_LP64(uint16_t) LP64_ONLY(uint32_t) idx_t;
146 // The first free element after the last one pushed (mod N).
147 volatile uint _bottom;
149 enum { MOD_N_MASK = N - 1 };
151 class Age {
152 public:
153 Age(size_t data = 0) { _data = data; }
154 Age(const Age& age) { _data = age._data; }
155 Age(idx_t top, idx_t tag) { _fields._top = top; _fields._tag = tag; }
157 Age get() const volatile { return _data; }
158 void set(Age age) volatile { _data = age._data; }
160 idx_t top() const volatile { return _fields._top; }
161 idx_t tag() const volatile { return _fields._tag; }
163 // Increment top; if it wraps, increment tag also.
164 void increment() {
165 _fields._top = increment_index(_fields._top);
166 if (_fields._top == 0) ++_fields._tag;
167 }
169 Age cmpxchg(const Age new_age, const Age old_age) volatile {
170 return (size_t) Atomic::cmpxchg_ptr((intptr_t)new_age._data,
171 (volatile intptr_t *)&_data,
172 (intptr_t)old_age._data);
173 }
175 bool operator ==(const Age& other) const { return _data == other._data; }
177 private:
178 struct fields {
179 idx_t _top;
180 idx_t _tag;
181 };
182 union {
183 size_t _data;
184 fields _fields;
185 };
186 };
188 volatile Age _age;
190 // These both operate mod N.
191 static uint increment_index(uint ind) {
192 return (ind + 1) & MOD_N_MASK;
193 }
194 static uint decrement_index(uint ind) {
195 return (ind - 1) & MOD_N_MASK;
196 }
198 // Returns a number in the range [0..N). If the result is "N-1", it should be
199 // interpreted as 0.
200 uint dirty_size(uint bot, uint top) const {
201 return (bot - top) & MOD_N_MASK;
202 }
204 // Returns the size corresponding to the given "bot" and "top".
205 uint size(uint bot, uint top) const {
206 uint sz = dirty_size(bot, top);
207 // Has the queue "wrapped", so that bottom is less than top? There's a
208 // complicated special case here. A pair of threads could perform pop_local
209 // and pop_global operations concurrently, starting from a state in which
210 // _bottom == _top+1. The pop_local could succeed in decrementing _bottom,
211 // and the pop_global in incrementing _top (in which case the pop_global
212 // will be awarded the contested queue element.) The resulting state must
213 // be interpreted as an empty queue. (We only need to worry about one such
214 // event: only the queue owner performs pop_local's, and several concurrent
215 // threads attempting to perform the pop_global will all perform the same
216 // CAS, and only one can succeed.) Any stealing thread that reads after
217 // either the increment or decrement will see an empty queue, and will not
218 // join the competitors. The "sz == -1 || sz == N-1" state will not be
219 // modified by concurrent queues, so the owner thread can reset the state to
220 // _bottom == top so subsequent pushes will be performed normally.
221 return (sz == N - 1) ? 0 : sz;
222 }
224 public:
225 TaskQueueSuper() : _bottom(0), _age() {}
227 // Return true if the TaskQueue contains/does not contain any tasks.
228 bool peek() const { return _bottom != _age.top(); }
229 bool is_empty() const { return size() == 0; }
231 // Return an estimate of the number of elements in the queue.
232 // The "careful" version admits the possibility of pop_local/pop_global
233 // races.
234 uint size() const {
235 return size(_bottom, _age.top());
236 }
238 uint dirty_size() const {
239 return dirty_size(_bottom, _age.top());
240 }
242 void set_empty() {
243 _bottom = 0;
244 _age.set(0);
245 }
247 // Maximum number of elements allowed in the queue. This is two less
248 // than the actual queue size, for somewhat complicated reasons.
249 uint max_elems() const { return N - 2; }
251 // Total size of queue.
252 static const uint total_size() { return N; }
254 TASKQUEUE_STATS_ONLY(TaskQueueStats stats;)
255 };
257 //
258 // GenericTaskQueue implements an ABP, Aurora-Blumofe-Plaxton, double-
259 // ended-queue (deque), intended for use in work stealing. Queue operations
260 // are non-blocking.
261 //
262 // A queue owner thread performs push() and pop_local() operations on one end
263 // of the queue, while other threads may steal work using the pop_global()
264 // method.
265 //
266 // The main difference to the original algorithm is that this
267 // implementation allows wrap-around at the end of its allocated
268 // storage, which is an array.
269 //
270 // The original paper is:
271 //
272 // Arora, N. S., Blumofe, R. D., and Plaxton, C. G.
273 // Thread scheduling for multiprogrammed multiprocessors.
274 // Theory of Computing Systems 34, 2 (2001), 115-144.
275 //
276 // The following paper provides an correctness proof and an
277 // implementation for weakly ordered memory models including (pseudo-)
278 // code containing memory barriers for a Chase-Lev deque. Chase-Lev is
279 // similar to ABP, with the main difference that it allows resizing of the
280 // underlying storage:
281 //
282 // Le, N. M., Pop, A., Cohen A., and Nardell, F. Z.
283 // Correct and efficient work-stealing for weak memory models
284 // Proceedings of the 18th ACM SIGPLAN symposium on Principles and
285 // practice of parallel programming (PPoPP 2013), 69-80
286 //
288 template <class E, MEMFLAGS F, unsigned int N = TASKQUEUE_SIZE>
289 class GenericTaskQueue: public TaskQueueSuper<N, F> {
290 ArrayAllocator<E, F> _array_allocator;
291 protected:
292 typedef typename TaskQueueSuper<N, F>::Age Age;
293 typedef typename TaskQueueSuper<N, F>::idx_t idx_t;
295 using TaskQueueSuper<N, F>::_bottom;
296 using TaskQueueSuper<N, F>::_age;
297 using TaskQueueSuper<N, F>::increment_index;
298 using TaskQueueSuper<N, F>::decrement_index;
299 using TaskQueueSuper<N, F>::dirty_size;
301 public:
302 using TaskQueueSuper<N, F>::max_elems;
303 using TaskQueueSuper<N, F>::size;
305 #if TASKQUEUE_STATS
306 using TaskQueueSuper<N, F>::stats;
307 #endif
309 private:
310 // Slow paths for push, pop_local. (pop_global has no fast path.)
311 bool push_slow(E t, uint dirty_n_elems);
312 bool pop_local_slow(uint localBot, Age oldAge);
314 public:
315 typedef E element_type;
317 // Initializes the queue to empty.
318 GenericTaskQueue();
320 void initialize();
322 // Push the task "t" on the queue. Returns "false" iff the queue is full.
323 inline bool push(E t);
325 // Attempts to claim a task from the "local" end of the queue (the most
326 // recently pushed). If successful, returns true and sets t to the task;
327 // otherwise, returns false (the queue is empty).
328 inline bool pop_local(volatile E& t);
330 // Like pop_local(), but uses the "global" end of the queue (the least
331 // recently pushed).
332 bool pop_global(volatile E& t);
334 // Delete any resource associated with the queue.
335 ~GenericTaskQueue();
337 // apply the closure to all elements in the task queue
338 void oops_do(OopClosure* f);
340 private:
341 // Element array.
342 volatile E* _elems;
343 };
345 template<class E, MEMFLAGS F, unsigned int N>
346 GenericTaskQueue<E, F, N>::GenericTaskQueue() {
347 assert(sizeof(Age) == sizeof(size_t), "Depends on this.");
348 }
350 template<class E, MEMFLAGS F, unsigned int N>
351 void GenericTaskQueue<E, F, N>::initialize() {
352 _elems = _array_allocator.allocate(N);
353 }
355 template<class E, MEMFLAGS F, unsigned int N>
356 void GenericTaskQueue<E, F, N>::oops_do(OopClosure* f) {
357 // tty->print_cr("START OopTaskQueue::oops_do");
358 uint iters = size();
359 uint index = _bottom;
360 for (uint i = 0; i < iters; ++i) {
361 index = decrement_index(index);
362 // tty->print_cr(" doing entry %d," INTPTR_T " -> " INTPTR_T,
363 // index, &_elems[index], _elems[index]);
364 E* t = (E*)&_elems[index]; // cast away volatility
365 oop* p = (oop*)t;
366 assert((*t)->is_oop_or_null(), "Not an oop or null");
367 f->do_oop(p);
368 }
369 // tty->print_cr("END OopTaskQueue::oops_do");
370 }
372 template<class E, MEMFLAGS F, unsigned int N>
373 bool GenericTaskQueue<E, F, N>::push_slow(E t, uint dirty_n_elems) {
374 if (dirty_n_elems == N - 1) {
375 // Actually means 0, so do the push.
376 uint localBot = _bottom;
377 // g++ complains if the volatile result of the assignment is
378 // unused, so we cast the volatile away. We cannot cast directly
379 // to void, because gcc treats that as not using the result of the
380 // assignment. However, casting to E& means that we trigger an
381 // unused-value warning. So, we cast the E& to void.
382 (void)const_cast<E&>(_elems[localBot] = t);
383 OrderAccess::release_store(&_bottom, increment_index(localBot));
384 TASKQUEUE_STATS_ONLY(stats.record_push());
385 return true;
386 }
387 return false;
388 }
390 // pop_local_slow() is done by the owning thread and is trying to
391 // get the last task in the queue. It will compete with pop_global()
392 // that will be used by other threads. The tag age is incremented
393 // whenever the queue goes empty which it will do here if this thread
394 // gets the last task or in pop_global() if the queue wraps (top == 0
395 // and pop_global() succeeds, see pop_global()).
396 template<class E, MEMFLAGS F, unsigned int N>
397 bool GenericTaskQueue<E, F, N>::pop_local_slow(uint localBot, Age oldAge) {
398 // This queue was observed to contain exactly one element; either this
399 // thread will claim it, or a competing "pop_global". In either case,
400 // the queue will be logically empty afterwards. Create a new Age value
401 // that represents the empty queue for the given value of "_bottom". (We
402 // must also increment "tag" because of the case where "bottom == 1",
403 // "top == 0". A pop_global could read the queue element in that case,
404 // then have the owner thread do a pop followed by another push. Without
405 // the incrementing of "tag", the pop_global's CAS could succeed,
406 // allowing it to believe it has claimed the stale element.)
407 Age newAge((idx_t)localBot, oldAge.tag() + 1);
408 // Perhaps a competing pop_global has already incremented "top", in which
409 // case it wins the element.
410 if (localBot == oldAge.top()) {
411 // No competing pop_global has yet incremented "top"; we'll try to
412 // install new_age, thus claiming the element.
413 Age tempAge = _age.cmpxchg(newAge, oldAge);
414 if (tempAge == oldAge) {
415 // We win.
416 assert(dirty_size(localBot, _age.top()) != N - 1, "sanity");
417 TASKQUEUE_STATS_ONLY(stats.record_pop_slow());
418 return true;
419 }
420 }
421 // We lose; a completing pop_global gets the element. But the queue is empty
422 // and top is greater than bottom. Fix this representation of the empty queue
423 // to become the canonical one.
424 _age.set(newAge);
425 assert(dirty_size(localBot, _age.top()) != N - 1, "sanity");
426 return false;
427 }
429 template<class E, MEMFLAGS F, unsigned int N>
430 bool GenericTaskQueue<E, F, N>::pop_global(volatile E& t) {
431 Age oldAge = _age.get();
432 // Architectures with weak memory model require a barrier here
433 // to guarantee that bottom is not older than age,
434 // which is crucial for the correctness of the algorithm.
435 #if !(defined SPARC || defined IA32 || defined AMD64)
436 OrderAccess::fence();
437 #endif
438 uint localBot = OrderAccess::load_acquire((volatile juint*)&_bottom);
439 uint n_elems = size(localBot, oldAge.top());
440 if (n_elems == 0) {
441 return false;
442 }
444 // g++ complains if the volatile result of the assignment is
445 // unused, so we cast the volatile away. We cannot cast directly
446 // to void, because gcc treats that as not using the result of the
447 // assignment. However, casting to E& means that we trigger an
448 // unused-value warning. So, we cast the E& to void.
449 (void) const_cast<E&>(t = _elems[oldAge.top()]);
450 Age newAge(oldAge);
451 newAge.increment();
452 Age resAge = _age.cmpxchg(newAge, oldAge);
454 // Note that using "_bottom" here might fail, since a pop_local might
455 // have decremented it.
456 assert(dirty_size(localBot, newAge.top()) != N - 1, "sanity");
457 return resAge == oldAge;
458 }
460 template<class E, MEMFLAGS F, unsigned int N>
461 GenericTaskQueue<E, F, N>::~GenericTaskQueue() {
462 FREE_C_HEAP_ARRAY(E, _elems, F);
463 }
465 // OverflowTaskQueue is a TaskQueue that also includes an overflow stack for
466 // elements that do not fit in the TaskQueue.
467 //
468 // This class hides two methods from super classes:
469 //
470 // push() - push onto the task queue or, if that fails, onto the overflow stack
471 // is_empty() - return true if both the TaskQueue and overflow stack are empty
472 //
473 // Note that size() is not hidden--it returns the number of elements in the
474 // TaskQueue, and does not include the size of the overflow stack. This
475 // simplifies replacement of GenericTaskQueues with OverflowTaskQueues.
476 template<class E, MEMFLAGS F, unsigned int N = TASKQUEUE_SIZE>
477 class OverflowTaskQueue: public GenericTaskQueue<E, F, N>
478 {
479 public:
480 typedef Stack<E, F> overflow_t;
481 typedef GenericTaskQueue<E, F, N> taskqueue_t;
483 TASKQUEUE_STATS_ONLY(using taskqueue_t::stats;)
485 // Push task t onto the queue or onto the overflow stack. Return true.
486 inline bool push(E t);
488 // Attempt to pop from the overflow stack; return true if anything was popped.
489 inline bool pop_overflow(E& t);
491 inline overflow_t* overflow_stack() { return &_overflow_stack; }
493 inline bool taskqueue_empty() const { return taskqueue_t::is_empty(); }
494 inline bool overflow_empty() const { return _overflow_stack.is_empty(); }
495 inline bool is_empty() const {
496 return taskqueue_empty() && overflow_empty();
497 }
499 private:
500 overflow_t _overflow_stack;
501 };
503 template <class E, MEMFLAGS F, unsigned int N>
504 bool OverflowTaskQueue<E, F, N>::push(E t)
505 {
506 if (!taskqueue_t::push(t)) {
507 overflow_stack()->push(t);
508 TASKQUEUE_STATS_ONLY(stats.record_overflow(overflow_stack()->size()));
509 }
510 return true;
511 }
513 template <class E, MEMFLAGS F, unsigned int N>
514 bool OverflowTaskQueue<E, F, N>::pop_overflow(E& t)
515 {
516 if (overflow_empty()) return false;
517 t = overflow_stack()->pop();
518 return true;
519 }
521 class TaskQueueSetSuper {
522 protected:
523 static int randomParkAndMiller(int* seed0);
524 public:
525 // Returns "true" if some TaskQueue in the set contains a task.
526 virtual bool peek() = 0;
527 };
529 template <MEMFLAGS F> class TaskQueueSetSuperImpl: public CHeapObj<F>, public TaskQueueSetSuper {
530 };
532 template<class T, MEMFLAGS F>
533 class GenericTaskQueueSet: public TaskQueueSetSuperImpl<F> {
534 private:
535 uint _n;
536 T** _queues;
538 public:
539 typedef typename T::element_type E;
541 GenericTaskQueueSet(int n) : _n(n) {
542 typedef T* GenericTaskQueuePtr;
543 _queues = NEW_C_HEAP_ARRAY(GenericTaskQueuePtr, n, F);
544 for (int i = 0; i < n; i++) {
545 _queues[i] = NULL;
546 }
547 }
549 bool steal_best_of_2(uint queue_num, int* seed, E& t);
551 void register_queue(uint i, T* q);
553 T* queue(uint n);
555 // The thread with queue number "queue_num" (and whose random number seed is
556 // at "seed") is trying to steal a task from some other queue. (It may try
557 // several queues, according to some configuration parameter.) If some steal
558 // succeeds, returns "true" and sets "t" to the stolen task, otherwise returns
559 // false.
560 bool steal(uint queue_num, int* seed, E& t);
562 bool peek();
563 };
565 template<class T, MEMFLAGS F> void
566 GenericTaskQueueSet<T, F>::register_queue(uint i, T* q) {
567 assert(i < _n, "index out of range.");
568 _queues[i] = q;
569 }
571 template<class T, MEMFLAGS F> T*
572 GenericTaskQueueSet<T, F>::queue(uint i) {
573 return _queues[i];
574 }
576 template<class T, MEMFLAGS F> bool
577 GenericTaskQueueSet<T, F>::steal(uint queue_num, int* seed, E& t) {
578 for (uint i = 0; i < 2 * _n; i++) {
579 if (steal_best_of_2(queue_num, seed, t)) {
580 TASKQUEUE_STATS_ONLY(queue(queue_num)->stats.record_steal(true));
581 return true;
582 }
583 }
584 TASKQUEUE_STATS_ONLY(queue(queue_num)->stats.record_steal(false));
585 return false;
586 }
588 template<class T, MEMFLAGS F> bool
589 GenericTaskQueueSet<T, F>::steal_best_of_2(uint queue_num, int* seed, E& t) {
590 if (_n > 2) {
591 uint k1 = queue_num;
592 while (k1 == queue_num) k1 = TaskQueueSetSuper::randomParkAndMiller(seed) % _n;
593 uint k2 = queue_num;
594 while (k2 == queue_num || k2 == k1) k2 = TaskQueueSetSuper::randomParkAndMiller(seed) % _n;
595 // Sample both and try the larger.
596 uint sz1 = _queues[k1]->size();
597 uint sz2 = _queues[k2]->size();
598 if (sz2 > sz1) return _queues[k2]->pop_global(t);
599 else return _queues[k1]->pop_global(t);
600 } else if (_n == 2) {
601 // Just try the other one.
602 uint k = (queue_num + 1) % 2;
603 return _queues[k]->pop_global(t);
604 } else {
605 assert(_n == 1, "can't be zero.");
606 return false;
607 }
608 }
610 template<class T, MEMFLAGS F>
611 bool GenericTaskQueueSet<T, F>::peek() {
612 // Try all the queues.
613 for (uint j = 0; j < _n; j++) {
614 if (_queues[j]->peek())
615 return true;
616 }
617 return false;
618 }
620 // When to terminate from the termination protocol.
621 class TerminatorTerminator: public CHeapObj<mtInternal> {
622 public:
623 virtual bool should_exit_termination() = 0;
624 };
626 // A class to aid in the termination of a set of parallel tasks using
627 // TaskQueueSet's for work stealing.
629 #undef TRACESPINNING
631 class ParallelTaskTerminator: public StackObj {
632 private:
633 int _n_threads;
634 TaskQueueSetSuper* _queue_set;
635 int _offered_termination;
637 #ifdef TRACESPINNING
638 static uint _total_yields;
639 static uint _total_spins;
640 static uint _total_peeks;
641 #endif
643 bool peek_in_queue_set();
644 protected:
645 virtual void yield();
646 void sleep(uint millis);
648 public:
650 // "n_threads" is the number of threads to be terminated. "queue_set" is a
651 // queue sets of work queues of other threads.
652 ParallelTaskTerminator(int n_threads, TaskQueueSetSuper* queue_set);
654 // The current thread has no work, and is ready to terminate if everyone
655 // else is. If returns "true", all threads are terminated. If returns
656 // "false", available work has been observed in one of the task queues,
657 // so the global task is not complete.
658 bool offer_termination() {
659 return offer_termination(NULL);
660 }
662 // As above, but it also terminates if the should_exit_termination()
663 // method of the terminator parameter returns true. If terminator is
664 // NULL, then it is ignored.
665 bool offer_termination(TerminatorTerminator* terminator);
667 // Reset the terminator, so that it may be reused again.
668 // The caller is responsible for ensuring that this is done
669 // in an MT-safe manner, once the previous round of use of
670 // the terminator is finished.
671 void reset_for_reuse();
672 // Same as above but the number of parallel threads is set to the
673 // given number.
674 void reset_for_reuse(int n_threads);
676 #ifdef TRACESPINNING
677 static uint total_yields() { return _total_yields; }
678 static uint total_spins() { return _total_spins; }
679 static uint total_peeks() { return _total_peeks; }
680 static void print_termination_counts();
681 #endif
682 };
684 template<class E, MEMFLAGS F, unsigned int N> inline bool
685 GenericTaskQueue<E, F, N>::push(E t) {
686 uint localBot = _bottom;
687 assert(localBot < N, "_bottom out of range.");
688 idx_t top = _age.top();
689 uint dirty_n_elems = dirty_size(localBot, top);
690 assert(dirty_n_elems < N, "n_elems out of range.");
691 if (dirty_n_elems < max_elems()) {
692 // g++ complains if the volatile result of the assignment is
693 // unused, so we cast the volatile away. We cannot cast directly
694 // to void, because gcc treats that as not using the result of the
695 // assignment. However, casting to E& means that we trigger an
696 // unused-value warning. So, we cast the E& to void.
697 (void) const_cast<E&>(_elems[localBot] = t);
698 OrderAccess::release_store(&_bottom, increment_index(localBot));
699 TASKQUEUE_STATS_ONLY(stats.record_push());
700 return true;
701 } else {
702 return push_slow(t, dirty_n_elems);
703 }
704 }
706 template<class E, MEMFLAGS F, unsigned int N> inline bool
707 GenericTaskQueue<E, F, N>::pop_local(volatile E& t) {
708 uint localBot = _bottom;
709 // This value cannot be N-1. That can only occur as a result of
710 // the assignment to bottom in this method. If it does, this method
711 // resets the size to 0 before the next call (which is sequential,
712 // since this is pop_local.)
713 uint dirty_n_elems = dirty_size(localBot, _age.top());
714 assert(dirty_n_elems != N - 1, "Shouldn't be possible...");
715 if (dirty_n_elems == 0) return false;
716 localBot = decrement_index(localBot);
717 _bottom = localBot;
718 // This is necessary to prevent any read below from being reordered
719 // before the store just above.
720 OrderAccess::fence();
721 // g++ complains if the volatile result of the assignment is
722 // unused, so we cast the volatile away. We cannot cast directly
723 // to void, because gcc treats that as not using the result of the
724 // assignment. However, casting to E& means that we trigger an
725 // unused-value warning. So, we cast the E& to void.
726 (void) const_cast<E&>(t = _elems[localBot]);
727 // This is a second read of "age"; the "size()" above is the first.
728 // If there's still at least one element in the queue, based on the
729 // "_bottom" and "age" we've read, then there can be no interference with
730 // a "pop_global" operation, and we're done.
731 idx_t tp = _age.top(); // XXX
732 if (size(localBot, tp) > 0) {
733 assert(dirty_size(localBot, tp) != N - 1, "sanity");
734 TASKQUEUE_STATS_ONLY(stats.record_pop());
735 return true;
736 } else {
737 // Otherwise, the queue contained exactly one element; we take the slow
738 // path.
739 return pop_local_slow(localBot, _age.get());
740 }
741 }
743 typedef GenericTaskQueue<oop, mtGC> OopTaskQueue;
744 typedef GenericTaskQueueSet<OopTaskQueue, mtGC> OopTaskQueueSet;
746 #ifdef _MSC_VER
747 #pragma warning(push)
748 // warning C4522: multiple assignment operators specified
749 #pragma warning(disable:4522)
750 #endif
752 // This is a container class for either an oop* or a narrowOop*.
753 // Both are pushed onto a task queue and the consumer will test is_narrow()
754 // to determine which should be processed.
755 class StarTask {
756 void* _holder; // either union oop* or narrowOop*
758 enum { COMPRESSED_OOP_MASK = 1 };
760 public:
761 StarTask(narrowOop* p) {
762 assert(((uintptr_t)p & COMPRESSED_OOP_MASK) == 0, "Information loss!");
763 _holder = (void *)((uintptr_t)p | COMPRESSED_OOP_MASK);
764 }
765 StarTask(oop* p) {
766 assert(((uintptr_t)p & COMPRESSED_OOP_MASK) == 0, "Information loss!");
767 _holder = (void*)p;
768 }
769 StarTask() { _holder = NULL; }
770 operator oop*() { return (oop*)_holder; }
771 operator narrowOop*() {
772 return (narrowOop*)((uintptr_t)_holder & ~COMPRESSED_OOP_MASK);
773 }
775 StarTask& operator=(const StarTask& t) {
776 _holder = t._holder;
777 return *this;
778 }
779 volatile StarTask& operator=(const volatile StarTask& t) volatile {
780 _holder = t._holder;
781 return *this;
782 }
784 bool is_narrow() const {
785 return (((uintptr_t)_holder & COMPRESSED_OOP_MASK) != 0);
786 }
787 };
789 class ObjArrayTask
790 {
791 public:
792 ObjArrayTask(oop o = NULL, int idx = 0): _obj(o), _index(idx) { }
793 ObjArrayTask(oop o, size_t idx): _obj(o), _index(int(idx)) {
794 assert(idx <= size_t(max_jint), "too big");
795 }
796 ObjArrayTask(const ObjArrayTask& t): _obj(t._obj), _index(t._index) { }
798 ObjArrayTask& operator =(const ObjArrayTask& t) {
799 _obj = t._obj;
800 _index = t._index;
801 return *this;
802 }
803 volatile ObjArrayTask&
804 operator =(const volatile ObjArrayTask& t) volatile {
805 (void)const_cast<oop&>(_obj = t._obj);
806 _index = t._index;
807 return *this;
808 }
810 inline oop obj() const { return _obj; }
811 inline int index() const { return _index; }
813 DEBUG_ONLY(bool is_valid() const); // Tasks to be pushed/popped must be valid.
815 private:
816 oop _obj;
817 int _index;
818 };
820 #ifdef _MSC_VER
821 #pragma warning(pop)
822 #endif
824 typedef OverflowTaskQueue<StarTask, mtClass> OopStarTaskQueue;
825 typedef GenericTaskQueueSet<OopStarTaskQueue, mtClass> OopStarTaskQueueSet;
827 typedef OverflowTaskQueue<size_t, mtInternal> RegionTaskQueue;
828 typedef GenericTaskQueueSet<RegionTaskQueue, mtClass> RegionTaskQueueSet;
831 #endif // SHARE_VM_UTILITIES_TASKQUEUE_HPP