Wed, 01 May 2013 14:11:01 +0100
Merge
1 /*
2 * Copyright (c) 2001, 2012, 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
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7 * published by the Free Software Foundation.
8 *
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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 *
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23 */
25 #ifndef SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP
26 #define SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP
28 #include "memory/referencePolicy.hpp"
29 #include "oops/instanceRefKlass.hpp"
31 // ReferenceProcessor class encapsulates the per-"collector" processing
32 // of java.lang.Reference objects for GC. The interface is useful for supporting
33 // a generational abstraction, in particular when there are multiple
34 // generations that are being independently collected -- possibly
35 // concurrently and/or incrementally. Note, however, that the
36 // ReferenceProcessor class abstracts away from a generational setting
37 // by using only a heap interval (called "span" below), thus allowing
38 // its use in a straightforward manner in a general, non-generational
39 // setting.
40 //
41 // The basic idea is that each ReferenceProcessor object concerns
42 // itself with ("weak") reference processing in a specific "span"
43 // of the heap of interest to a specific collector. Currently,
44 // the span is a convex interval of the heap, but, efficiency
45 // apart, there seems to be no reason it couldn't be extended
46 // (with appropriate modifications) to any "non-convex interval".
48 // forward references
49 class ReferencePolicy;
50 class AbstractRefProcTaskExecutor;
52 // List of discovered references.
53 class DiscoveredList {
54 public:
55 DiscoveredList() : _len(0), _compressed_head(0), _oop_head(NULL) { }
56 oop head() const {
57 return UseCompressedOops ? oopDesc::decode_heap_oop(_compressed_head) :
58 _oop_head;
59 }
60 HeapWord* adr_head() {
61 return UseCompressedOops ? (HeapWord*)&_compressed_head :
62 (HeapWord*)&_oop_head;
63 }
64 void set_head(oop o) {
65 if (UseCompressedOops) {
66 // Must compress the head ptr.
67 _compressed_head = oopDesc::encode_heap_oop(o);
68 } else {
69 _oop_head = o;
70 }
71 }
72 bool is_empty() const { return head() == NULL; }
73 size_t length() { return _len; }
74 void set_length(size_t len) { _len = len; }
75 void inc_length(size_t inc) { _len += inc; assert(_len > 0, "Error"); }
76 void dec_length(size_t dec) { _len -= dec; }
77 private:
78 // Set value depending on UseCompressedOops. This could be a template class
79 // but then we have to fix all the instantiations and declarations that use this class.
80 oop _oop_head;
81 narrowOop _compressed_head;
82 size_t _len;
83 };
85 // Iterator for the list of discovered references.
86 class DiscoveredListIterator {
87 private:
88 DiscoveredList& _refs_list;
89 HeapWord* _prev_next;
90 oop _prev;
91 oop _ref;
92 HeapWord* _discovered_addr;
93 oop _next;
94 HeapWord* _referent_addr;
95 oop _referent;
96 OopClosure* _keep_alive;
97 BoolObjectClosure* _is_alive;
99 DEBUG_ONLY(
100 oop _first_seen; // cyclic linked list check
101 )
103 NOT_PRODUCT(
104 size_t _processed;
105 size_t _removed;
106 )
108 public:
109 inline DiscoveredListIterator(DiscoveredList& refs_list,
110 OopClosure* keep_alive,
111 BoolObjectClosure* is_alive):
112 _refs_list(refs_list),
113 _prev_next(refs_list.adr_head()),
114 _prev(NULL),
115 _ref(refs_list.head()),
116 #ifdef ASSERT
117 _first_seen(refs_list.head()),
118 #endif
119 #ifndef PRODUCT
120 _processed(0),
121 _removed(0),
122 #endif
123 _next(NULL),
124 _keep_alive(keep_alive),
125 _is_alive(is_alive)
126 { }
128 // End Of List.
129 inline bool has_next() const { return _ref != NULL; }
131 // Get oop to the Reference object.
132 inline oop obj() const { return _ref; }
134 // Get oop to the referent object.
135 inline oop referent() const { return _referent; }
137 // Returns true if referent is alive.
138 inline bool is_referent_alive() const {
139 return _is_alive->do_object_b(_referent);
140 }
142 // Loads data for the current reference.
143 // The "allow_null_referent" argument tells us to allow for the possibility
144 // of a NULL referent in the discovered Reference object. This typically
145 // happens in the case of concurrent collectors that may have done the
146 // discovery concurrently, or interleaved, with mutator execution.
147 void load_ptrs(DEBUG_ONLY(bool allow_null_referent));
149 // Move to the next discovered reference.
150 inline void next() {
151 _prev_next = _discovered_addr;
152 _prev = _ref;
153 move_to_next();
154 }
156 // Remove the current reference from the list
157 void remove();
159 // Make the Reference object active again.
160 void make_active();
162 // Make the referent alive.
163 inline void make_referent_alive() {
164 if (UseCompressedOops) {
165 _keep_alive->do_oop((narrowOop*)_referent_addr);
166 } else {
167 _keep_alive->do_oop((oop*)_referent_addr);
168 }
169 }
171 // Update the discovered field.
172 inline void update_discovered() {
173 // First _prev_next ref actually points into DiscoveredList (gross).
174 if (UseCompressedOops) {
175 if (!oopDesc::is_null(*(narrowOop*)_prev_next)) {
176 _keep_alive->do_oop((narrowOop*)_prev_next);
177 }
178 } else {
179 if (!oopDesc::is_null(*(oop*)_prev_next)) {
180 _keep_alive->do_oop((oop*)_prev_next);
181 }
182 }
183 }
185 // NULL out referent pointer.
186 void clear_referent();
188 // Statistics
189 NOT_PRODUCT(
190 inline size_t processed() const { return _processed; }
191 inline size_t removed() const { return _removed; }
192 )
194 inline void move_to_next() {
195 if (_ref == _next) {
196 // End of the list.
197 _ref = NULL;
198 } else {
199 _ref = _next;
200 }
201 assert(_ref != _first_seen, "cyclic ref_list found");
202 NOT_PRODUCT(_processed++);
203 }
204 };
206 class ReferenceProcessor : public CHeapObj<mtGC> {
207 protected:
208 // Compatibility with pre-4965777 JDK's
209 static bool _pending_list_uses_discovered_field;
211 // The SoftReference master timestamp clock
212 static jlong _soft_ref_timestamp_clock;
214 MemRegion _span; // (right-open) interval of heap
215 // subject to wkref discovery
217 bool _discovering_refs; // true when discovery enabled
218 bool _discovery_is_atomic; // if discovery is atomic wrt
219 // other collectors in configuration
220 bool _discovery_is_mt; // true if reference discovery is MT.
222 // If true, setting "next" field of a discovered refs list requires
223 // write barrier(s). (Must be true if used in a collector in which
224 // elements of a discovered list may be moved during discovery: for
225 // example, a collector like Garbage-First that moves objects during a
226 // long-term concurrent marking phase that does weak reference
227 // discovery.)
228 bool _discovered_list_needs_barrier;
230 BarrierSet* _bs; // Cached copy of BarrierSet.
231 bool _enqueuing_is_done; // true if all weak references enqueued
232 bool _processing_is_mt; // true during phases when
233 // reference processing is MT.
234 uint _next_id; // round-robin mod _num_q counter in
235 // support of work distribution
237 // For collectors that do not keep GC liveness information
238 // in the object header, this field holds a closure that
239 // helps the reference processor determine the reachability
240 // of an oop. It is currently initialized to NULL for all
241 // collectors except for CMS and G1.
242 BoolObjectClosure* _is_alive_non_header;
244 // Soft ref clearing policies
245 // . the default policy
246 static ReferencePolicy* _default_soft_ref_policy;
247 // . the "clear all" policy
248 static ReferencePolicy* _always_clear_soft_ref_policy;
249 // . the current policy below is either one of the above
250 ReferencePolicy* _current_soft_ref_policy;
252 // The discovered ref lists themselves
254 // The active MT'ness degree of the queues below
255 uint _num_q;
256 // The maximum MT'ness degree of the queues below
257 uint _max_num_q;
259 // Master array of discovered oops
260 DiscoveredList* _discovered_refs;
262 // Arrays of lists of oops, one per thread (pointers into master array above)
263 DiscoveredList* _discoveredSoftRefs;
264 DiscoveredList* _discoveredWeakRefs;
265 DiscoveredList* _discoveredFinalRefs;
266 DiscoveredList* _discoveredPhantomRefs;
268 public:
269 static int number_of_subclasses_of_ref() { return (REF_PHANTOM - REF_OTHER); }
271 uint num_q() { return _num_q; }
272 uint max_num_q() { return _max_num_q; }
273 void set_active_mt_degree(uint v) { _num_q = v; }
275 DiscoveredList* discovered_refs() { return _discovered_refs; }
277 ReferencePolicy* setup_policy(bool always_clear) {
278 _current_soft_ref_policy = always_clear ?
279 _always_clear_soft_ref_policy : _default_soft_ref_policy;
280 _current_soft_ref_policy->setup(); // snapshot the policy threshold
281 return _current_soft_ref_policy;
282 }
284 // Process references with a certain reachability level.
285 void process_discovered_reflist(DiscoveredList refs_lists[],
286 ReferencePolicy* policy,
287 bool clear_referent,
288 BoolObjectClosure* is_alive,
289 OopClosure* keep_alive,
290 VoidClosure* complete_gc,
291 AbstractRefProcTaskExecutor* task_executor);
293 void process_phaseJNI(BoolObjectClosure* is_alive,
294 OopClosure* keep_alive,
295 VoidClosure* complete_gc);
297 // Work methods used by the method process_discovered_reflist
298 // Phase1: keep alive all those referents that are otherwise
299 // dead but which must be kept alive by policy (and their closure).
300 void process_phase1(DiscoveredList& refs_list,
301 ReferencePolicy* policy,
302 BoolObjectClosure* is_alive,
303 OopClosure* keep_alive,
304 VoidClosure* complete_gc);
305 // Phase2: remove all those references whose referents are
306 // reachable.
307 inline void process_phase2(DiscoveredList& refs_list,
308 BoolObjectClosure* is_alive,
309 OopClosure* keep_alive,
310 VoidClosure* complete_gc) {
311 if (discovery_is_atomic()) {
312 // complete_gc is ignored in this case for this phase
313 pp2_work(refs_list, is_alive, keep_alive);
314 } else {
315 assert(complete_gc != NULL, "Error");
316 pp2_work_concurrent_discovery(refs_list, is_alive,
317 keep_alive, complete_gc);
318 }
319 }
320 // Work methods in support of process_phase2
321 void pp2_work(DiscoveredList& refs_list,
322 BoolObjectClosure* is_alive,
323 OopClosure* keep_alive);
324 void pp2_work_concurrent_discovery(
325 DiscoveredList& refs_list,
326 BoolObjectClosure* is_alive,
327 OopClosure* keep_alive,
328 VoidClosure* complete_gc);
329 // Phase3: process the referents by either clearing them
330 // or keeping them alive (and their closure)
331 void process_phase3(DiscoveredList& refs_list,
332 bool clear_referent,
333 BoolObjectClosure* is_alive,
334 OopClosure* keep_alive,
335 VoidClosure* complete_gc);
337 // Enqueue references with a certain reachability level
338 void enqueue_discovered_reflist(DiscoveredList& refs_list, HeapWord* pending_list_addr);
340 // "Preclean" all the discovered reference lists
341 // by removing references with strongly reachable referents.
342 // The first argument is a predicate on an oop that indicates
343 // its (strong) reachability and the second is a closure that
344 // may be used to incrementalize or abort the precleaning process.
345 // The caller is responsible for taking care of potential
346 // interference with concurrent operations on these lists
347 // (or predicates involved) by other threads. Currently
348 // only used by the CMS collector.
349 void preclean_discovered_references(BoolObjectClosure* is_alive,
350 OopClosure* keep_alive,
351 VoidClosure* complete_gc,
352 YieldClosure* yield);
354 // Delete entries in the discovered lists that have
355 // either a null referent or are not active. Such
356 // Reference objects can result from the clearing
357 // or enqueueing of Reference objects concurrent
358 // with their discovery by a (concurrent) collector.
359 // For a definition of "active" see java.lang.ref.Reference;
360 // Refs are born active, become inactive when enqueued,
361 // and never become active again. The state of being
362 // active is encoded as follows: A Ref is active
363 // if and only if its "next" field is NULL.
364 void clean_up_discovered_references();
365 void clean_up_discovered_reflist(DiscoveredList& refs_list);
367 // Returns the name of the discovered reference list
368 // occupying the i / _num_q slot.
369 const char* list_name(uint i);
371 void enqueue_discovered_reflists(HeapWord* pending_list_addr, AbstractRefProcTaskExecutor* task_executor);
373 protected:
374 // Set the 'discovered' field of the given reference to
375 // the given value - emitting barriers depending upon
376 // the value of _discovered_list_needs_barrier.
377 void set_discovered(oop ref, oop value);
379 // "Preclean" the given discovered reference list
380 // by removing references with strongly reachable referents.
381 // Currently used in support of CMS only.
382 void preclean_discovered_reflist(DiscoveredList& refs_list,
383 BoolObjectClosure* is_alive,
384 OopClosure* keep_alive,
385 VoidClosure* complete_gc,
386 YieldClosure* yield);
388 // round-robin mod _num_q (not: _not_ mode _max_num_q)
389 uint next_id() {
390 uint id = _next_id;
391 if (++_next_id == _num_q) {
392 _next_id = 0;
393 }
394 return id;
395 }
396 DiscoveredList* get_discovered_list(ReferenceType rt);
397 inline void add_to_discovered_list_mt(DiscoveredList& refs_list, oop obj,
398 HeapWord* discovered_addr);
399 void verify_ok_to_handle_reflists() PRODUCT_RETURN;
401 void clear_discovered_references(DiscoveredList& refs_list);
402 void abandon_partial_discovered_list(DiscoveredList& refs_list);
404 // Calculate the number of jni handles.
405 unsigned int count_jni_refs();
407 // Balances reference queues.
408 void balance_queues(DiscoveredList ref_lists[]);
410 // Update (advance) the soft ref master clock field.
411 void update_soft_ref_master_clock();
413 public:
414 // constructor
415 ReferenceProcessor():
416 _span((HeapWord*)NULL, (HeapWord*)NULL),
417 _discovered_refs(NULL),
418 _discoveredSoftRefs(NULL), _discoveredWeakRefs(NULL),
419 _discoveredFinalRefs(NULL), _discoveredPhantomRefs(NULL),
420 _discovering_refs(false),
421 _discovery_is_atomic(true),
422 _enqueuing_is_done(false),
423 _discovery_is_mt(false),
424 _discovered_list_needs_barrier(false),
425 _bs(NULL),
426 _is_alive_non_header(NULL),
427 _num_q(0),
428 _max_num_q(0),
429 _processing_is_mt(false),
430 _next_id(0)
431 { }
433 // Default parameters give you a vanilla reference processor.
434 ReferenceProcessor(MemRegion span,
435 bool mt_processing = false, uint mt_processing_degree = 1,
436 bool mt_discovery = false, uint mt_discovery_degree = 1,
437 bool atomic_discovery = true,
438 BoolObjectClosure* is_alive_non_header = NULL,
439 bool discovered_list_needs_barrier = false);
441 // RefDiscoveryPolicy values
442 enum DiscoveryPolicy {
443 ReferenceBasedDiscovery = 0,
444 ReferentBasedDiscovery = 1,
445 DiscoveryPolicyMin = ReferenceBasedDiscovery,
446 DiscoveryPolicyMax = ReferentBasedDiscovery
447 };
449 static void init_statics();
451 public:
452 // get and set "is_alive_non_header" field
453 BoolObjectClosure* is_alive_non_header() {
454 return _is_alive_non_header;
455 }
456 void set_is_alive_non_header(BoolObjectClosure* is_alive_non_header) {
457 _is_alive_non_header = is_alive_non_header;
458 }
460 // get and set span
461 MemRegion span() { return _span; }
462 void set_span(MemRegion span) { _span = span; }
464 // start and stop weak ref discovery
465 void enable_discovery(bool verify_disabled, bool check_no_refs);
466 void disable_discovery() { _discovering_refs = false; }
467 bool discovery_enabled() { return _discovering_refs; }
469 // whether discovery is atomic wrt other collectors
470 bool discovery_is_atomic() const { return _discovery_is_atomic; }
471 void set_atomic_discovery(bool atomic) { _discovery_is_atomic = atomic; }
473 // whether the JDK in which we are embedded is a pre-4965777 JDK,
474 // and thus whether or not it uses the discovered field to chain
475 // the entries in the pending list.
476 static bool pending_list_uses_discovered_field() {
477 return _pending_list_uses_discovered_field;
478 }
480 // whether discovery is done by multiple threads same-old-timeously
481 bool discovery_is_mt() const { return _discovery_is_mt; }
482 void set_mt_discovery(bool mt) { _discovery_is_mt = mt; }
484 // Whether we are in a phase when _processing_ is MT.
485 bool processing_is_mt() const { return _processing_is_mt; }
486 void set_mt_processing(bool mt) { _processing_is_mt = mt; }
488 // whether all enqueuing of weak references is complete
489 bool enqueuing_is_done() { return _enqueuing_is_done; }
490 void set_enqueuing_is_done(bool v) { _enqueuing_is_done = v; }
492 // iterate over oops
493 void weak_oops_do(OopClosure* f); // weak roots
495 // Balance each of the discovered lists.
496 void balance_all_queues();
497 void verify_list(DiscoveredList& ref_list);
499 // Discover a Reference object, using appropriate discovery criteria
500 bool discover_reference(oop obj, ReferenceType rt);
502 // Process references found during GC (called by the garbage collector)
503 void process_discovered_references(BoolObjectClosure* is_alive,
504 OopClosure* keep_alive,
505 VoidClosure* complete_gc,
506 AbstractRefProcTaskExecutor* task_executor);
508 public:
509 // Enqueue references at end of GC (called by the garbage collector)
510 bool enqueue_discovered_references(AbstractRefProcTaskExecutor* task_executor = NULL);
512 // If a discovery is in process that is being superceded, abandon it: all
513 // the discovered lists will be empty, and all the objects on them will
514 // have NULL discovered fields. Must be called only at a safepoint.
515 void abandon_partial_discovery();
517 // debugging
518 void verify_no_references_recorded() PRODUCT_RETURN;
519 void verify_referent(oop obj) PRODUCT_RETURN;
521 // clear the discovered lists (unlinking each entry).
522 void clear_discovered_references() PRODUCT_RETURN;
523 };
525 // A utility class to disable reference discovery in
526 // the scope which contains it, for given ReferenceProcessor.
527 class NoRefDiscovery: StackObj {
528 private:
529 ReferenceProcessor* _rp;
530 bool _was_discovering_refs;
531 public:
532 NoRefDiscovery(ReferenceProcessor* rp) : _rp(rp) {
533 _was_discovering_refs = _rp->discovery_enabled();
534 if (_was_discovering_refs) {
535 _rp->disable_discovery();
536 }
537 }
539 ~NoRefDiscovery() {
540 if (_was_discovering_refs) {
541 _rp->enable_discovery(true /*verify_disabled*/, false /*check_no_refs*/);
542 }
543 }
544 };
547 // A utility class to temporarily mutate the span of the
548 // given ReferenceProcessor in the scope that contains it.
549 class ReferenceProcessorSpanMutator: StackObj {
550 private:
551 ReferenceProcessor* _rp;
552 MemRegion _saved_span;
554 public:
555 ReferenceProcessorSpanMutator(ReferenceProcessor* rp,
556 MemRegion span):
557 _rp(rp) {
558 _saved_span = _rp->span();
559 _rp->set_span(span);
560 }
562 ~ReferenceProcessorSpanMutator() {
563 _rp->set_span(_saved_span);
564 }
565 };
567 // A utility class to temporarily change the MT'ness of
568 // reference discovery for the given ReferenceProcessor
569 // in the scope that contains it.
570 class ReferenceProcessorMTDiscoveryMutator: StackObj {
571 private:
572 ReferenceProcessor* _rp;
573 bool _saved_mt;
575 public:
576 ReferenceProcessorMTDiscoveryMutator(ReferenceProcessor* rp,
577 bool mt):
578 _rp(rp) {
579 _saved_mt = _rp->discovery_is_mt();
580 _rp->set_mt_discovery(mt);
581 }
583 ~ReferenceProcessorMTDiscoveryMutator() {
584 _rp->set_mt_discovery(_saved_mt);
585 }
586 };
589 // A utility class to temporarily change the disposition
590 // of the "is_alive_non_header" closure field of the
591 // given ReferenceProcessor in the scope that contains it.
592 class ReferenceProcessorIsAliveMutator: StackObj {
593 private:
594 ReferenceProcessor* _rp;
595 BoolObjectClosure* _saved_cl;
597 public:
598 ReferenceProcessorIsAliveMutator(ReferenceProcessor* rp,
599 BoolObjectClosure* cl):
600 _rp(rp) {
601 _saved_cl = _rp->is_alive_non_header();
602 _rp->set_is_alive_non_header(cl);
603 }
605 ~ReferenceProcessorIsAliveMutator() {
606 _rp->set_is_alive_non_header(_saved_cl);
607 }
608 };
610 // A utility class to temporarily change the disposition
611 // of the "discovery_is_atomic" field of the
612 // given ReferenceProcessor in the scope that contains it.
613 class ReferenceProcessorAtomicMutator: StackObj {
614 private:
615 ReferenceProcessor* _rp;
616 bool _saved_atomic_discovery;
618 public:
619 ReferenceProcessorAtomicMutator(ReferenceProcessor* rp,
620 bool atomic):
621 _rp(rp) {
622 _saved_atomic_discovery = _rp->discovery_is_atomic();
623 _rp->set_atomic_discovery(atomic);
624 }
626 ~ReferenceProcessorAtomicMutator() {
627 _rp->set_atomic_discovery(_saved_atomic_discovery);
628 }
629 };
632 // A utility class to temporarily change the MT processing
633 // disposition of the given ReferenceProcessor instance
634 // in the scope that contains it.
635 class ReferenceProcessorMTProcMutator: StackObj {
636 private:
637 ReferenceProcessor* _rp;
638 bool _saved_mt;
640 public:
641 ReferenceProcessorMTProcMutator(ReferenceProcessor* rp,
642 bool mt):
643 _rp(rp) {
644 _saved_mt = _rp->processing_is_mt();
645 _rp->set_mt_processing(mt);
646 }
648 ~ReferenceProcessorMTProcMutator() {
649 _rp->set_mt_processing(_saved_mt);
650 }
651 };
654 // This class is an interface used to implement task execution for the
655 // reference processing.
656 class AbstractRefProcTaskExecutor {
657 public:
659 // Abstract tasks to execute.
660 class ProcessTask;
661 class EnqueueTask;
663 // Executes a task using worker threads.
664 virtual void execute(ProcessTask& task) = 0;
665 virtual void execute(EnqueueTask& task) = 0;
667 // Switch to single threaded mode.
668 virtual void set_single_threaded_mode() { };
669 };
671 // Abstract reference processing task to execute.
672 class AbstractRefProcTaskExecutor::ProcessTask {
673 protected:
674 ProcessTask(ReferenceProcessor& ref_processor,
675 DiscoveredList refs_lists[],
676 bool marks_oops_alive)
677 : _ref_processor(ref_processor),
678 _refs_lists(refs_lists),
679 _marks_oops_alive(marks_oops_alive)
680 { }
682 public:
683 virtual void work(unsigned int work_id, BoolObjectClosure& is_alive,
684 OopClosure& keep_alive,
685 VoidClosure& complete_gc) = 0;
687 // Returns true if a task marks some oops as alive.
688 bool marks_oops_alive() const
689 { return _marks_oops_alive; }
691 protected:
692 ReferenceProcessor& _ref_processor;
693 DiscoveredList* _refs_lists;
694 const bool _marks_oops_alive;
695 };
697 // Abstract reference processing task to execute.
698 class AbstractRefProcTaskExecutor::EnqueueTask {
699 protected:
700 EnqueueTask(ReferenceProcessor& ref_processor,
701 DiscoveredList refs_lists[],
702 HeapWord* pending_list_addr,
703 int n_queues)
704 : _ref_processor(ref_processor),
705 _refs_lists(refs_lists),
706 _pending_list_addr(pending_list_addr),
707 _n_queues(n_queues)
708 { }
710 public:
711 virtual void work(unsigned int work_id) = 0;
713 protected:
714 ReferenceProcessor& _ref_processor;
715 DiscoveredList* _refs_lists;
716 HeapWord* _pending_list_addr;
717 int _n_queues;
718 };
720 #endif // SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP