1 /*
2 * Copyright (c) 2013, 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
26
27 #include "gc_implementation/shared/markBitMap.hpp"
28 #include "gc_implementation/shenandoah/shenandoahAsserts.hpp"
29 #include "gc_implementation/shenandoah/shenandoahAllocRequest.hpp"
30 #include "gc_implementation/shenandoah/shenandoahHeapLock.hpp"
31 #include "gc_implementation/shenandoah/shenandoahEvacOOMHandler.hpp"
32 #include "gc_implementation/shenandoah/shenandoahSharedVariables.hpp"
33
34 class ConcurrentGCTimer;
35
36 class ShenandoahAllocTracker;
37 class ShenandoahCollectionSet;
38 class ShenandoahCollectorPolicy;
39 class ShenandoahConcurrentMark;
40 class ShenandoahControlThread;
41 class ShenandoahGCSession;
42 class ShenandoahFreeSet;
43 class ShenandoahHeapRegion;
44 class ShenandoahHeapRegionClosure;
45 class ShenandoahMarkCompact;
46 class ShenandoahMonitoringSupport;
47 class ShenandoahHeuristics;
48 class ShenandoahMarkingContext;
49 class ShenandoahPhaseTimings;
50 class ShenandoahPacer;
51 class ShenandoahVerifier;
52 class ShenandoahWorkGang;
53 class VMStructs;
54
55 class ShenandoahRegionIterator : public StackObj {
56 private:
57 ShenandoahHeap* _heap;
58
59 char _pad0[DEFAULT_CACHE_LINE_SIZE];
60 volatile jint _index;
61 char _pad1[DEFAULT_CACHE_LINE_SIZE];
62
63 // No implicit copying: iterators should be passed by reference to capture the state
64 ShenandoahRegionIterator(const ShenandoahRegionIterator& that);
65 ShenandoahRegionIterator& operator=(const ShenandoahRegionIterator& o);
66
67 public:
68 ShenandoahRegionIterator();
69 ShenandoahRegionIterator(ShenandoahHeap* heap);
70
71 // Reset iterator to default state
72 void reset();
73
74 // Returns next region, or NULL if there are no more regions.
75 // This is multi-thread-safe.
76 inline ShenandoahHeapRegion* next();
77
78 // This is *not* MT safe. However, in the absence of multithreaded access, it
79 // can be used to determine if there is more work to do.
80 bool has_next() const;
81 };
82
83 class ShenandoahHeapRegionClosure : public StackObj {
84 public:
85 virtual void heap_region_do(ShenandoahHeapRegion* r) = 0;
86 virtual bool is_thread_safe() { return false; }
87 };
88
89 class ShenandoahUpdateRefsClosure: public OopClosure {
90 private:
91 ShenandoahHeap* _heap;
92
93 template <class T>
94 inline void do_oop_work(T* p);
95
96 public:
97 ShenandoahUpdateRefsClosure();
98 inline void do_oop(oop* p);
99 inline void do_oop(narrowOop* p);
100 };
101
102 #ifdef ASSERT
103 class ShenandoahAssertToSpaceClosure : public OopClosure {
104 private:
105 template <class T>
106 void do_oop_nv(T* p);
107 public:
108 void do_oop(narrowOop* p);
109 void do_oop(oop* p);
110 };
111 #endif
112
113 class ShenandoahAlwaysTrueClosure : public BoolObjectClosure {
114 public:
115 bool do_object_b(oop p) { return true; }
116 };
117
118 class ShenandoahForwardedIsAliveClosure: public BoolObjectClosure {
119 private:
120 ShenandoahMarkingContext* const _mark_context;
121 public:
122 ShenandoahForwardedIsAliveClosure();
123 bool do_object_b(oop obj);
124 };
125
126 class ShenandoahIsAliveClosure: public BoolObjectClosure {
127 private:
128 ShenandoahMarkingContext* const _mark_context;
129 public:
130 ShenandoahIsAliveClosure();
131 bool do_object_b(oop obj);
132 };
133
134 class ShenandoahIsAliveSelector : public StackObj {
135 private:
136 ShenandoahIsAliveClosure _alive_cl;
137 ShenandoahForwardedIsAliveClosure _fwd_alive_cl;
138 public:
139 BoolObjectClosure* is_alive_closure();
140 };
141
142 // Shenandoah GC is low-pause concurrent GC that uses Brooks forwarding pointers
143 // to encode forwarding data. See BrooksPointer for details on forwarding data encoding.
144 // See ShenandoahControlThread for GC cycle structure.
145 //
146 class ShenandoahHeap : public SharedHeap {
147 friend class ShenandoahAsserts;
148 friend class VMStructs;
149 friend class ShenandoahGCSession;
150
151 // ---------- Locks that guard important data structures in Heap
152 //
153 private:
154 ShenandoahHeapLock _lock;
155
156 public:
157 ShenandoahHeapLock* lock() {
158 return &_lock;
159 }
160
161 void assert_heaplock_owned_by_current_thread() NOT_DEBUG_RETURN;
162 void assert_heaplock_not_owned_by_current_thread() NOT_DEBUG_RETURN;
163 void assert_heaplock_or_safepoint() NOT_DEBUG_RETURN;
164
165 // ---------- Initialization, termination, identification, printing routines
166 //
167 public:
168 static ShenandoahHeap* heap();
169 static ShenandoahHeap* heap_no_check();
170 static size_t conservative_max_heap_alignment();
171
172 const char* name() const { return "Shenandoah"; }
173 ShenandoahHeap::Name kind() const { return CollectedHeap::ShenandoahHeap; }
174
175 ShenandoahHeap(ShenandoahCollectorPolicy* policy);
176 jint initialize();
177 void post_initialize();
178 void initialize_heuristics();
179
180 void print_on(outputStream* st) const;
181 void print_extended_on(outputStream *st) const;
182 void print_tracing_info() const;
183 void print_gc_threads_on(outputStream* st) const;
184 void print_heap_regions_on(outputStream* st) const;
185
186 void stop();
187
188 void prepare_for_verify();
189 void verify(bool silent, VerifyOption vo);
190
191 // ---------- Heap counters and metrics
192 //
193 private:
194 size_t _initial_size;
195 char _pad0[DEFAULT_CACHE_LINE_SIZE];
196 volatile jlong _used;
197 volatile size_t _committed;
198 volatile jlong _bytes_allocated_since_gc_start;
199 char _pad1[DEFAULT_CACHE_LINE_SIZE];
200
201 public:
202 void increase_used(size_t bytes);
203 void decrease_used(size_t bytes);
204 void set_used(size_t bytes);
205
206 void increase_committed(size_t bytes);
207 void decrease_committed(size_t bytes);
208 void increase_allocated(size_t bytes);
209
210 size_t bytes_allocated_since_gc_start();
211 void reset_bytes_allocated_since_gc_start();
212
213 size_t max_capacity() const;
214 size_t initial_capacity() const;
215 size_t capacity() const;
216 size_t used() const;
217 size_t committed() const;
218
219 // ---------- Workers handling
220 //
221 private:
222 uint _max_workers;
223 ShenandoahWorkGang* _workers;
224
225 public:
226 uint max_workers();
227 void assert_gc_workers(uint nworker) NOT_DEBUG_RETURN;
228
229 ShenandoahWorkGang* workers() const;
230
231 void gc_threads_do(ThreadClosure* tcl) const;
232
233 // ---------- Heap regions handling machinery
234 //
235 private:
236 MemRegion _heap_region;
237 size_t _num_regions;
238 ShenandoahHeapRegion** _regions;
239 ShenandoahRegionIterator _update_refs_iterator;
240
241 public:
242 inline size_t num_regions() const { return _num_regions; }
243
244 inline ShenandoahHeapRegion* const heap_region_containing(const void* addr) const;
245 inline size_t heap_region_index_containing(const void* addr) const;
246
247 inline ShenandoahHeapRegion* const get_region(size_t region_idx) const;
248
249 void heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
250 void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
251
252 // ---------- GC state machinery
253 //
254 // GC state describes the important parts of collector state, that may be
255 // used to make barrier selection decisions in the native and generated code.
256 // Multiple bits can be set at once.
257 //
258 // Important invariant: when GC state is zero, the heap is stable, and no barriers
259 // are required.
260 //
261 public:
262 enum GCStateBitPos {
263 // Heap has forwarded objects: need RB, ACMP, CAS barriers.
264 HAS_FORWARDED_BITPOS = 0,
265
266 // Heap is under marking: needs SATB barriers.
267 MARKING_BITPOS = 1,
268
269 // Heap is under evacuation: needs WB barriers. (Set together with UNSTABLE)
270 EVACUATION_BITPOS = 2,
271
272 // Heap is under updating: needs SVRB/SVWB barriers.
273 UPDATEREFS_BITPOS = 3,
274 };
275
276 enum GCState {
277 STABLE = 0,
278 HAS_FORWARDED = 1 << HAS_FORWARDED_BITPOS,
279 MARKING = 1 << MARKING_BITPOS,
280 EVACUATION = 1 << EVACUATION_BITPOS,
281 UPDATEREFS = 1 << UPDATEREFS_BITPOS,
282 };
283
284 private:
285 ShenandoahSharedBitmap _gc_state;
286 ShenandoahSharedFlag _degenerated_gc_in_progress;
287 ShenandoahSharedFlag _full_gc_in_progress;
288 ShenandoahSharedFlag _full_gc_move_in_progress;
289 ShenandoahSharedFlag _progress_last_gc;
290
291 void set_gc_state_mask(uint mask, bool value);
292
293 public:
294 char gc_state();
295 static address gc_state_addr();
296
297 void set_concurrent_mark_in_progress(bool in_progress);
298 void set_evacuation_in_progress(bool in_progress);
299 void set_update_refs_in_progress(bool in_progress);
300 void set_degenerated_gc_in_progress(bool in_progress);
301 void set_full_gc_in_progress(bool in_progress);
302 void set_full_gc_move_in_progress(bool in_progress);
303 void set_has_forwarded_objects(bool cond);
304
305 inline bool is_stable() const;
306 inline bool is_idle() const;
307 inline bool is_concurrent_mark_in_progress() const;
308 inline bool is_update_refs_in_progress() const;
309 inline bool is_evacuation_in_progress() const;
310 inline bool is_degenerated_gc_in_progress() const;
311 inline bool is_full_gc_in_progress() const;
312 inline bool is_full_gc_move_in_progress() const;
313 inline bool has_forwarded_objects() const;
314 inline bool is_gc_in_progress_mask(uint mask) const;
315
316 // ---------- GC cancellation and degeneration machinery
317 //
318 // Cancelled GC flag is used to notify concurrent phases that they should terminate.
319 //
320 public:
321 enum ShenandoahDegenPoint {
322 _degenerated_unset,
323 _degenerated_outside_cycle,
324 _degenerated_mark,
325 _degenerated_evac,
326 _degenerated_updaterefs,
327 _DEGENERATED_LIMIT,
328 };
329
330 static const char* degen_point_to_string(ShenandoahDegenPoint point) {
331 switch (point) {
332 case _degenerated_unset:
333 return "<UNSET>";
334 case _degenerated_outside_cycle:
335 return "Outside of Cycle";
336 case _degenerated_mark:
337 return "Mark";
338 case _degenerated_evac:
339 return "Evacuation";
340 case _degenerated_updaterefs:
341 return "Update Refs";
342 default:
343 ShouldNotReachHere();
344 return "ERROR";
345 }
346 };
347
348 private:
349 ShenandoahSharedFlag _cancelled_gc;
350 inline bool try_cancel_gc();
351
352 public:
353 static address cancelled_gc_addr();
354
355 inline bool cancelled_gc() const;
356
357 inline void clear_cancelled_gc();
358
359 void cancel_gc(GCCause::Cause cause);
360
361 // ---------- GC operations entry points
362 //
363 public:
364 // Entry points to STW GC operations, these cause a related safepoint, that then
365 // call the entry method below
366 void vmop_entry_init_mark();
367 void vmop_entry_final_mark();
368 void vmop_entry_final_evac();
369 void vmop_entry_init_updaterefs();
370 void vmop_entry_final_updaterefs();
371 void vmop_entry_full(GCCause::Cause cause);
372 void vmop_degenerated(ShenandoahDegenPoint point);
373
374 // Entry methods to normally STW GC operations. These set up logging, monitoring
375 // and workers for net VM operation
376 void entry_init_mark();
377 void entry_final_mark();
378 void entry_final_evac();
379 void entry_init_updaterefs();
380 void entry_final_updaterefs();
381 void entry_full(GCCause::Cause cause);
382 void entry_degenerated(int point);
383
384 // Entry methods to normally concurrent GC operations. These set up logging, monitoring
385 // for concurrent operation.
386 void entry_reset();
387 void entry_mark();
388 void entry_preclean();
389 void entry_cleanup();
390 void entry_evac();
391 void entry_updaterefs();
392 void entry_uncommit(double shrink_before);
393
394 private:
395 // Actual work for the phases
396 void op_init_mark();
397 void op_final_mark();
398 void op_final_evac();
399 void op_init_updaterefs();
400 void op_final_updaterefs();
401 void op_full(GCCause::Cause cause);
402 void op_degenerated(ShenandoahDegenPoint point);
403 void op_degenerated_fail();
404 void op_degenerated_futile();
405
406 void op_reset();
407 void op_mark();
408 void op_preclean();
409 void op_cleanup();
410 void op_conc_evac();
411 void op_stw_evac();
412 void op_updaterefs();
413 void op_uncommit(double shrink_before);
414
415 // Messages for GC trace event, they have to be immortal for
416 // passing around the logging/tracing systems
417 const char* init_mark_event_message() const;
418 const char* final_mark_event_message() const;
419 const char* conc_mark_event_message() const;
420 const char* degen_event_message(ShenandoahDegenPoint point) const;
421
422 // ---------- GC subsystems
423 //
424 private:
425 ShenandoahControlThread* _control_thread;
426 ShenandoahCollectorPolicy* _shenandoah_policy;
427 ShenandoahHeuristics* _heuristics;
428 ShenandoahFreeSet* _free_set;
429 ShenandoahConcurrentMark* _scm;
430 ShenandoahMarkCompact* _full_gc;
431 ShenandoahPacer* _pacer;
432 ShenandoahVerifier* _verifier;
433
434 ShenandoahAllocTracker* _alloc_tracker;
435 ShenandoahPhaseTimings* _phase_timings;
436
437 ShenandoahControlThread* control_thread() { return _control_thread; }
438 ShenandoahMarkCompact* full_gc() { return _full_gc; }
439
440 public:
441 ShenandoahCollectorPolicy* shenandoah_policy() const { return _shenandoah_policy; }
442 ShenandoahHeuristics* heuristics() const { return _heuristics; }
443 ShenandoahFreeSet* free_set() const { return _free_set; }
444 ShenandoahConcurrentMark* concurrent_mark() { return _scm; }
445 ShenandoahPacer* pacer() const { return _pacer; }
446
447 ShenandoahPhaseTimings* phase_timings() const { return _phase_timings; }
448 ShenandoahAllocTracker* alloc_tracker() const { return _alloc_tracker; }
449
450 ShenandoahVerifier* verifier();
451
452 // ---------- VM subsystem bindings
453 //
454 private:
455 ShenandoahMonitoringSupport* _monitoring_support;
456 ConcurrentGCTimer* _gc_timer;
457
458 public:
459 ShenandoahMonitoringSupport* monitoring_support() { return _monitoring_support; }
460
461 GCTracer* tracer();
462 GCTimer* gc_timer() const;
463 CollectorPolicy* collector_policy() const;
464
465 // ---------- Reference processing
466 //
467 private:
468 ReferenceProcessor* _ref_processor;
469 ShenandoahSharedFlag _process_references;
470
471 void ref_processing_init();
472
473 public:
474 ReferenceProcessor* ref_processor() { return _ref_processor;}
475 void set_process_references(bool pr);
476 bool process_references() const;
477
478 // ---------- Class Unloading
479 //
480 private:
481 ShenandoahSharedFlag _unload_classes;
482
483 public:
484 void set_unload_classes(bool uc);
485 bool unload_classes() const;
486
487 // Delete entries for dead interned string and clean up unreferenced symbols
488 // in symbol table, possibly in parallel.
489 void unload_classes_and_cleanup_tables(bool full_gc);
490
491 // ---------- Generic interface hooks
492 // Minor things that super-interface expects us to implement to play nice with
493 // the rest of runtime. Some of the things here are not required to be implemented,
494 // and can be stubbed out.
495 //
496 public:
497 AdaptiveSizePolicy* size_policy() shenandoah_not_implemented_return(NULL);
498 bool is_maximal_no_gc() const shenandoah_not_implemented_return(false);
499
500 bool is_in(const void* p) const;
501
502 // All objects can potentially move
503 bool is_scavengable(const void* addr) { return true; }
504
505 void collect(GCCause::Cause cause);
506 void do_full_collection(bool clear_all_soft_refs);
507
508 // Used for parsing heap during error printing
509 HeapWord* block_start(const void* addr) const;
510 size_t block_size(const HeapWord* addr) const;
511 bool block_is_obj(const HeapWord* addr) const;
512
513 // Used for native heap walkers: heap dumpers, mostly
514 void object_iterate(ObjectClosure* cl);
515 void safe_object_iterate(ObjectClosure* cl);
516 void space_iterate(SpaceClosure* scl);
517 void oop_iterate(ExtendedOopClosure* cl);
518 Space* space_containing(const void* oop) const;
519
520 // Used by RMI
521 jlong millis_since_last_gc();
522
523 bool can_elide_tlab_store_barriers() const { return true; }
524 oop new_store_pre_barrier(JavaThread* thread, oop new_obj) { return new_obj; }
525 bool can_elide_initializing_store_barrier(oop new_obj) { return true; }
526 bool card_mark_must_follow_store() const { return false; }
527
528 bool is_in_partial_collection(const void* p) shenandoah_not_implemented_return(false);
529 bool supports_heap_inspection() const { return true; }
530
531 void gc_prologue(bool b);
532 void gc_epilogue(bool b);
533
534 void acquire_pending_refs_lock();
535 void release_pending_refs_lock();
536
537 // ---------- Code roots handling hooks
538 //
539 public:
540 void register_nmethod(nmethod* nm);
541 void unregister_nmethod(nmethod* nm);
542
543 // ---------- Pinning hooks
544 //
545 public:
546 // Shenandoah supports per-object (per-region) pinning
547 bool supports_object_pinning() const { return true; }
548
549 oop pin_object(JavaThread* thread, oop obj);
550 void unpin_object(JavaThread* thread, oop obj);
551
552 // ---------- Allocation support
553 //
554 private:
555 HeapWord* allocate_memory_under_lock(ShenandoahAllocRequest& request, bool& in_new_region);
556 inline HeapWord* allocate_from_gclab(Thread* thread, size_t size);
557 HeapWord* allocate_from_gclab_slow(Thread* thread, size_t size);
558 HeapWord* allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size);
559
560 public:
561 #ifndef CC_INTERP
562 void compile_prepare_oop(MacroAssembler* masm, Register obj);
563 #endif
564
565 HeapWord* allocate_memory(ShenandoahAllocRequest& request);
566 HeapWord* mem_allocate(size_t size, bool* what);
567
568 uint oop_extra_words();
569
570 void notify_mutator_alloc_words(size_t words, bool waste);
571
572 // Shenandoah supports TLAB allocation
573 bool supports_tlab_allocation() const { return true; }
574
575 HeapWord* allocate_new_tlab(size_t word_size);
576 size_t tlab_capacity(Thread *thr) const;
577 size_t unsafe_max_tlab_alloc(Thread *thread) const;
578 size_t max_tlab_size() const;
579 size_t tlab_used(Thread* ignored) const;
580
581 HeapWord* tlab_post_allocation_setup(HeapWord* obj);
582
583 void resize_tlabs();
584 void resize_all_tlabs();
585
586 void accumulate_statistics_tlabs();
587 void accumulate_statistics_all_gclabs();
588
589 void make_parsable(bool retire_tlabs);
590 void ensure_parsability(bool retire_tlabs);
591
592 // ---------- Marking support
593 //
594 private:
595 ShenandoahMarkingContext* _marking_context;
596 MemRegion _bitmap_region;
597 MemRegion _aux_bitmap_region;
598 MarkBitMap _verification_bit_map;
599 MarkBitMap _aux_bit_map;
600
601 size_t _bitmap_size;
602 size_t _bitmap_regions_per_slice;
603 size_t _bitmap_bytes_per_slice;
604
605 // Used for buffering per-region liveness data.
606 // Needed since ShenandoahHeapRegion uses atomics to update liveness.
607 //
608 // The array has max-workers elements, each of which is an array of
609 // jushort * max_regions. The choice of jushort is not accidental:
610 // there is a tradeoff between static/dynamic footprint that translates
611 // into cache pressure (which is already high during marking), and
612 // too many atomic updates. size_t/jint is too large, jbyte is too small.
613 jushort** _liveness_cache;
614
615 public:
616 inline ShenandoahMarkingContext* complete_marking_context() const;
617 inline ShenandoahMarkingContext* marking_context() const;
618 inline void mark_complete_marking_context();
619 inline void mark_incomplete_marking_context();
620
621 template<class T>
622 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl);
623
624 template<class T>
625 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
626
627 template<class T>
628 inline void marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
629
630 void reset_mark_bitmap();
631
632 // SATB barriers hooks
633 inline bool requires_marking(const void* entry) const;
634 void force_satb_flush_all_threads();
635
636 // Support for bitmap uncommits
637 bool commit_bitmap_slice(ShenandoahHeapRegion *r);
638 bool uncommit_bitmap_slice(ShenandoahHeapRegion *r);
639 bool is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self = false);
640
641 // Liveness caching support
642 jushort* get_liveness_cache(uint worker_id);
643 void flush_liveness_cache(uint worker_id);
644
645 // ---------- Evacuation support
646 //
647 private:
648 ShenandoahCollectionSet* _collection_set;
649 ShenandoahEvacOOMHandler _oom_evac_handler;
650
651 void evacuate_and_update_roots();
652
653 public:
654 static address in_cset_fast_test_addr();
655
656 ShenandoahCollectionSet* collection_set() const { return _collection_set; }
657
658 template <class T>
659 inline bool in_collection_set(T obj) const;
660
661 // Avoid accidentally calling the method above with ShenandoahHeapRegion*, which would be *wrong*.
662 inline bool in_collection_set(ShenandoahHeapRegion* r) shenandoah_not_implemented_return(false);
663
664 // Evacuates object src. Returns the evacuated object, either evacuated
665 // by this thread, or by some other thread.
666 inline oop evacuate_object(oop src, Thread* thread, bool& evacuated);
667
668 // Call before/after evacuation.
669 void enter_evacuation();
670 void leave_evacuation();
671
672 // ---------- Helper functions
673 //
674 public:
675 template <class T>
676 inline oop maybe_update_with_forwarded(T* p);
677
678 template <class T>
679 inline oop maybe_update_with_forwarded_not_null(T* p, oop obj);
680
681 template <class T>
682 inline oop update_with_forwarded_not_null(T* p, oop obj);
683
684 inline oop atomic_compare_exchange_oop(oop n, narrowOop* addr, oop c);
685 inline oop atomic_compare_exchange_oop(oop n, oop* addr, oop c);
686
687 void trash_humongous_region_at(ShenandoahHeapRegion *r);
688
689 void stop_concurrent_marking();
690
691 void roots_iterate(OopClosure* cl);
692
693 private:
694 void trash_cset_regions();
695 void update_heap_references(bool concurrent);
696
697 // ---------- Testing helpers functions
698 //
699 private:
700 ShenandoahSharedFlag _inject_alloc_failure;
701
702 void try_inject_alloc_failure();
703 bool should_inject_alloc_failure();
704 };
705
706 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP