Wed, 25 Mar 2015 11:03:16 +0100
8065358: Refactor G1s usage of save_marks and reduce related races
Summary: Stop using save_marks in G1 related code and make setting the replacement field less racy.
Reviewed-by: brutisso, tschatzl
1 /*
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
28 #include "gc_implementation/g1/g1AllocationContext.hpp"
29 #include "gc_implementation/g1/g1BlockOffsetTable.hpp"
30 #include "gc_implementation/g1/g1_specialized_oop_closures.hpp"
31 #include "gc_implementation/g1/heapRegionType.hpp"
32 #include "gc_implementation/g1/survRateGroup.hpp"
33 #include "gc_implementation/shared/ageTable.hpp"
34 #include "gc_implementation/shared/spaceDecorator.hpp"
35 #include "memory/space.inline.hpp"
36 #include "memory/watermark.hpp"
37 #include "utilities/macros.hpp"
39 // A HeapRegion is the smallest piece of a G1CollectedHeap that
40 // can be collected independently.
42 // NOTE: Although a HeapRegion is a Space, its
43 // Space::initDirtyCardClosure method must not be called.
44 // The problem is that the existence of this method breaks
45 // the independence of barrier sets from remembered sets.
46 // The solution is to remove this method from the definition
47 // of a Space.
49 class HeapRegionRemSet;
50 class HeapRegionRemSetIterator;
51 class HeapRegion;
52 class HeapRegionSetBase;
53 class nmethod;
55 #define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"
56 #define HR_FORMAT_PARAMS(_hr_) \
57 (_hr_)->hrm_index(), \
58 (_hr_)->get_short_type_str(), \
59 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
61 // sentinel value for hrm_index
62 #define G1_NO_HRM_INDEX ((uint) -1)
64 // A dirty card to oop closure for heap regions. It
65 // knows how to get the G1 heap and how to use the bitmap
66 // in the concurrent marker used by G1 to filter remembered
67 // sets.
69 class HeapRegionDCTOC : public DirtyCardToOopClosure {
70 public:
71 // Specification of possible DirtyCardToOopClosure filtering.
72 enum FilterKind {
73 NoFilterKind,
74 IntoCSFilterKind,
75 OutOfRegionFilterKind
76 };
78 protected:
79 HeapRegion* _hr;
80 FilterKind _fk;
81 G1CollectedHeap* _g1;
83 // Walk the given memory region from bottom to (actual) top
84 // looking for objects and applying the oop closure (_cl) to
85 // them. The base implementation of this treats the area as
86 // blocks, where a block may or may not be an object. Sub-
87 // classes should override this to provide more accurate
88 // or possibly more efficient walking.
89 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
91 public:
92 HeapRegionDCTOC(G1CollectedHeap* g1,
93 HeapRegion* hr, ExtendedOopClosure* cl,
94 CardTableModRefBS::PrecisionStyle precision,
95 FilterKind fk);
96 };
98 // The complicating factor is that BlockOffsetTable diverged
99 // significantly, and we need functionality that is only in the G1 version.
100 // So I copied that code, which led to an alternate G1 version of
101 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
102 // be reconciled, then G1OffsetTableContigSpace could go away.
104 // The idea behind time stamps is the following. We want to keep track of
105 // the highest address where it's safe to scan objects for each region.
106 // This is only relevant for current GC alloc regions so we keep a time stamp
107 // per region to determine if the region has been allocated during the current
108 // GC or not. If the time stamp is current we report a scan_top value which
109 // was saved at the end of the previous GC for retained alloc regions and which is
110 // equal to the bottom for all other regions.
111 // There is a race between card scanners and allocating gc workers where we must ensure
112 // that card scanners do not read the memory allocated by the gc workers.
113 // In order to enforce that, we must not return a value of _top which is more recent than the
114 // time stamp. This is due to the fact that a region may become a gc alloc region at
115 // some point after we've read the timestamp value as being < the current time stamp.
116 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
117 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
118 // evacuation pauses between two cleanups, which is _highly_ unlikely.
119 class G1OffsetTableContigSpace: public CompactibleSpace {
120 friend class VMStructs;
121 HeapWord* _top;
122 HeapWord* volatile _scan_top;
123 protected:
124 G1BlockOffsetArrayContigSpace _offsets;
125 Mutex _par_alloc_lock;
126 volatile unsigned _gc_time_stamp;
127 // When we need to retire an allocation region, while other threads
128 // are also concurrently trying to allocate into it, we typically
129 // allocate a dummy object at the end of the region to ensure that
130 // no more allocations can take place in it. However, sometimes we
131 // want to know where the end of the last "real" object we allocated
132 // into the region was and this is what this keeps track.
133 HeapWord* _pre_dummy_top;
135 public:
136 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
137 MemRegion mr);
139 void set_top(HeapWord* value) { _top = value; }
140 HeapWord* top() const { return _top; }
142 protected:
143 // Reset the G1OffsetTableContigSpace.
144 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
146 HeapWord** top_addr() { return &_top; }
147 // Allocation helpers (return NULL if full).
148 inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
149 inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);
151 public:
152 void reset_after_compaction() { set_top(compaction_top()); }
154 size_t used() const { return byte_size(bottom(), top()); }
155 size_t free() const { return byte_size(top(), end()); }
156 bool is_free_block(const HeapWord* p) const { return p >= top(); }
158 MemRegion used_region() const { return MemRegion(bottom(), top()); }
160 void object_iterate(ObjectClosure* blk);
161 void safe_object_iterate(ObjectClosure* blk);
163 void set_bottom(HeapWord* value);
164 void set_end(HeapWord* value);
166 HeapWord* scan_top() const;
167 void record_timestamp();
168 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
169 unsigned get_gc_time_stamp() { return _gc_time_stamp; }
170 void record_retained_region();
172 // See the comment above in the declaration of _pre_dummy_top for an
173 // explanation of what it is.
174 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
175 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
176 _pre_dummy_top = pre_dummy_top;
177 }
178 HeapWord* pre_dummy_top() {
179 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
180 }
181 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
183 virtual void clear(bool mangle_space);
185 HeapWord* block_start(const void* p);
186 HeapWord* block_start_const(const void* p) const;
188 void prepare_for_compaction(CompactPoint* cp);
190 // Add offset table update.
191 virtual HeapWord* allocate(size_t word_size);
192 HeapWord* par_allocate(size_t word_size);
194 HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
196 // MarkSweep support phase3
197 virtual HeapWord* initialize_threshold();
198 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
200 virtual void print() const;
202 void reset_bot() {
203 _offsets.reset_bot();
204 }
206 void print_bot_on(outputStream* out) {
207 _offsets.print_on(out);
208 }
209 };
211 class HeapRegion: public G1OffsetTableContigSpace {
212 friend class VMStructs;
213 private:
215 // The remembered set for this region.
216 // (Might want to make this "inline" later, to avoid some alloc failure
217 // issues.)
218 HeapRegionRemSet* _rem_set;
220 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
222 protected:
223 // The index of this region in the heap region sequence.
224 uint _hrm_index;
226 AllocationContext_t _allocation_context;
228 HeapRegionType _type;
230 // For a humongous region, region in which it starts.
231 HeapRegion* _humongous_start_region;
232 // For the start region of a humongous sequence, it's original end().
233 HeapWord* _orig_end;
235 // True iff the region is in current collection_set.
236 bool _in_collection_set;
238 // True iff an attempt to evacuate an object in the region failed.
239 bool _evacuation_failed;
241 // A heap region may be a member one of a number of special subsets, each
242 // represented as linked lists through the field below. Currently, there
243 // is only one set:
244 // The collection set.
245 HeapRegion* _next_in_special_set;
247 // next region in the young "generation" region set
248 HeapRegion* _next_young_region;
250 // Next region whose cards need cleaning
251 HeapRegion* _next_dirty_cards_region;
253 // Fields used by the HeapRegionSetBase class and subclasses.
254 HeapRegion* _next;
255 HeapRegion* _prev;
256 #ifdef ASSERT
257 HeapRegionSetBase* _containing_set;
258 #endif // ASSERT
260 // For parallel heapRegion traversal.
261 jint _claimed;
263 // We use concurrent marking to determine the amount of live data
264 // in each heap region.
265 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
266 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
268 // The calculated GC efficiency of the region.
269 double _gc_efficiency;
271 int _young_index_in_cset;
272 SurvRateGroup* _surv_rate_group;
273 int _age_index;
275 // The start of the unmarked area. The unmarked area extends from this
276 // word until the top and/or end of the region, and is the part
277 // of the region for which no marking was done, i.e. objects may
278 // have been allocated in this part since the last mark phase.
279 // "prev" is the top at the start of the last completed marking.
280 // "next" is the top at the start of the in-progress marking (if any.)
281 HeapWord* _prev_top_at_mark_start;
282 HeapWord* _next_top_at_mark_start;
283 // If a collection pause is in progress, this is the top at the start
284 // of that pause.
286 void init_top_at_mark_start() {
287 assert(_prev_marked_bytes == 0 &&
288 _next_marked_bytes == 0,
289 "Must be called after zero_marked_bytes.");
290 HeapWord* bot = bottom();
291 _prev_top_at_mark_start = bot;
292 _next_top_at_mark_start = bot;
293 }
295 // Cached attributes used in the collection set policy information
297 // The RSet length that was added to the total value
298 // for the collection set.
299 size_t _recorded_rs_length;
301 // The predicted elapsed time that was added to total value
302 // for the collection set.
303 double _predicted_elapsed_time_ms;
305 // The predicted number of bytes to copy that was added to
306 // the total value for the collection set.
307 size_t _predicted_bytes_to_copy;
309 public:
310 HeapRegion(uint hrm_index,
311 G1BlockOffsetSharedArray* sharedOffsetArray,
312 MemRegion mr);
314 // Initializing the HeapRegion not only resets the data structure, but also
315 // resets the BOT for that heap region.
316 // The default values for clear_space means that we will do the clearing if
317 // there's clearing to be done ourselves. We also always mangle the space.
318 virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
320 static int LogOfHRGrainBytes;
321 static int LogOfHRGrainWords;
323 static size_t GrainBytes;
324 static size_t GrainWords;
325 static size_t CardsPerRegion;
327 static size_t align_up_to_region_byte_size(size_t sz) {
328 return (sz + (size_t) GrainBytes - 1) &
329 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
330 }
332 static size_t max_region_size();
334 // It sets up the heap region size (GrainBytes / GrainWords), as
335 // well as other related fields that are based on the heap region
336 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
337 // CardsPerRegion). All those fields are considered constant
338 // throughout the JVM's execution, therefore they should only be set
339 // up once during initialization time.
340 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
342 enum ClaimValues {
343 InitialClaimValue = 0,
344 FinalCountClaimValue = 1,
345 NoteEndClaimValue = 2,
346 ScrubRemSetClaimValue = 3,
347 ParVerifyClaimValue = 4,
348 RebuildRSClaimValue = 5,
349 ParEvacFailureClaimValue = 6,
350 AggregateCountClaimValue = 7,
351 VerifyCountClaimValue = 8,
352 ParMarkRootClaimValue = 9
353 };
355 // All allocated blocks are occupied by objects in a HeapRegion
356 bool block_is_obj(const HeapWord* p) const;
358 // Returns the object size for all valid block starts
359 // and the amount of unallocated words if called on top()
360 size_t block_size(const HeapWord* p) const;
362 inline HeapWord* par_allocate_no_bot_updates(size_t word_size);
363 inline HeapWord* allocate_no_bot_updates(size_t word_size);
365 // If this region is a member of a HeapRegionManager, the index in that
366 // sequence, otherwise -1.
367 uint hrm_index() const { return _hrm_index; }
369 // The number of bytes marked live in the region in the last marking phase.
370 size_t marked_bytes() { return _prev_marked_bytes; }
371 size_t live_bytes() {
372 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
373 }
375 // The number of bytes counted in the next marking.
376 size_t next_marked_bytes() { return _next_marked_bytes; }
377 // The number of bytes live wrt the next marking.
378 size_t next_live_bytes() {
379 return
380 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
381 }
383 // A lower bound on the amount of garbage bytes in the region.
384 size_t garbage_bytes() {
385 size_t used_at_mark_start_bytes =
386 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
387 assert(used_at_mark_start_bytes >= marked_bytes(),
388 "Can't mark more than we have.");
389 return used_at_mark_start_bytes - marked_bytes();
390 }
392 // Return the amount of bytes we'll reclaim if we collect this
393 // region. This includes not only the known garbage bytes in the
394 // region but also any unallocated space in it, i.e., [top, end),
395 // since it will also be reclaimed if we collect the region.
396 size_t reclaimable_bytes() {
397 size_t known_live_bytes = live_bytes();
398 assert(known_live_bytes <= capacity(), "sanity");
399 return capacity() - known_live_bytes;
400 }
402 // An upper bound on the number of live bytes in the region.
403 size_t max_live_bytes() { return used() - garbage_bytes(); }
405 void add_to_marked_bytes(size_t incr_bytes) {
406 _next_marked_bytes = _next_marked_bytes + incr_bytes;
407 assert(_next_marked_bytes <= used(), "invariant" );
408 }
410 void zero_marked_bytes() {
411 _prev_marked_bytes = _next_marked_bytes = 0;
412 }
414 const char* get_type_str() const { return _type.get_str(); }
415 const char* get_short_type_str() const { return _type.get_short_str(); }
417 bool is_free() const { return _type.is_free(); }
419 bool is_young() const { return _type.is_young(); }
420 bool is_eden() const { return _type.is_eden(); }
421 bool is_survivor() const { return _type.is_survivor(); }
423 bool isHumongous() const { return _type.is_humongous(); }
424 bool startsHumongous() const { return _type.is_starts_humongous(); }
425 bool continuesHumongous() const { return _type.is_continues_humongous(); }
427 bool is_old() const { return _type.is_old(); }
429 // For a humongous region, region in which it starts.
430 HeapRegion* humongous_start_region() const {
431 return _humongous_start_region;
432 }
434 // Return the number of distinct regions that are covered by this region:
435 // 1 if the region is not humongous, >= 1 if the region is humongous.
436 uint region_num() const {
437 if (!isHumongous()) {
438 return 1U;
439 } else {
440 assert(startsHumongous(), "doesn't make sense on HC regions");
441 assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
442 return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
443 }
444 }
446 // Return the index + 1 of the last HC regions that's associated
447 // with this HS region.
448 uint last_hc_index() const {
449 assert(startsHumongous(), "don't call this otherwise");
450 return hrm_index() + region_num();
451 }
453 // Same as Space::is_in_reserved, but will use the original size of the region.
454 // The original size is different only for start humongous regions. They get
455 // their _end set up to be the end of the last continues region of the
456 // corresponding humongous object.
457 bool is_in_reserved_raw(const void* p) const {
458 return _bottom <= p && p < _orig_end;
459 }
461 // Makes the current region be a "starts humongous" region, i.e.,
462 // the first region in a series of one or more contiguous regions
463 // that will contain a single "humongous" object. The two parameters
464 // are as follows:
465 //
466 // new_top : The new value of the top field of this region which
467 // points to the end of the humongous object that's being
468 // allocated. If there is more than one region in the series, top
469 // will lie beyond this region's original end field and on the last
470 // region in the series.
471 //
472 // new_end : The new value of the end field of this region which
473 // points to the end of the last region in the series. If there is
474 // one region in the series (namely: this one) end will be the same
475 // as the original end of this region.
476 //
477 // Updating top and end as described above makes this region look as
478 // if it spans the entire space taken up by all the regions in the
479 // series and an single allocation moved its top to new_top. This
480 // ensures that the space (capacity / allocated) taken up by all
481 // humongous regions can be calculated by just looking at the
482 // "starts humongous" regions and by ignoring the "continues
483 // humongous" regions.
484 void set_startsHumongous(HeapWord* new_top, HeapWord* new_end);
486 // Makes the current region be a "continues humongous'
487 // region. first_hr is the "start humongous" region of the series
488 // which this region will be part of.
489 void set_continuesHumongous(HeapRegion* first_hr);
491 // Unsets the humongous-related fields on the region.
492 void clear_humongous();
494 // If the region has a remembered set, return a pointer to it.
495 HeapRegionRemSet* rem_set() const {
496 return _rem_set;
497 }
499 // True iff the region is in current collection_set.
500 bool in_collection_set() const {
501 return _in_collection_set;
502 }
503 void set_in_collection_set(bool b) {
504 _in_collection_set = b;
505 }
506 HeapRegion* next_in_collection_set() {
507 assert(in_collection_set(), "should only invoke on member of CS.");
508 assert(_next_in_special_set == NULL ||
509 _next_in_special_set->in_collection_set(),
510 "Malformed CS.");
511 return _next_in_special_set;
512 }
513 void set_next_in_collection_set(HeapRegion* r) {
514 assert(in_collection_set(), "should only invoke on member of CS.");
515 assert(r == NULL || r->in_collection_set(), "Malformed CS.");
516 _next_in_special_set = r;
517 }
519 void set_allocation_context(AllocationContext_t context) {
520 _allocation_context = context;
521 }
523 AllocationContext_t allocation_context() const {
524 return _allocation_context;
525 }
527 // Methods used by the HeapRegionSetBase class and subclasses.
529 // Getter and setter for the next and prev fields used to link regions into
530 // linked lists.
531 HeapRegion* next() { return _next; }
532 HeapRegion* prev() { return _prev; }
534 void set_next(HeapRegion* next) { _next = next; }
535 void set_prev(HeapRegion* prev) { _prev = prev; }
537 // Every region added to a set is tagged with a reference to that
538 // set. This is used for doing consistency checking to make sure that
539 // the contents of a set are as they should be and it's only
540 // available in non-product builds.
541 #ifdef ASSERT
542 void set_containing_set(HeapRegionSetBase* containing_set) {
543 assert((containing_set == NULL && _containing_set != NULL) ||
544 (containing_set != NULL && _containing_set == NULL),
545 err_msg("containing_set: "PTR_FORMAT" "
546 "_containing_set: "PTR_FORMAT,
547 p2i(containing_set), p2i(_containing_set)));
549 _containing_set = containing_set;
550 }
552 HeapRegionSetBase* containing_set() { return _containing_set; }
553 #else // ASSERT
554 void set_containing_set(HeapRegionSetBase* containing_set) { }
556 // containing_set() is only used in asserts so there's no reason
557 // to provide a dummy version of it.
558 #endif // ASSERT
560 HeapRegion* get_next_young_region() { return _next_young_region; }
561 void set_next_young_region(HeapRegion* hr) {
562 _next_young_region = hr;
563 }
565 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
566 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
567 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
568 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
570 HeapWord* orig_end() const { return _orig_end; }
572 // Reset HR stuff to default values.
573 void hr_clear(bool par, bool clear_space, bool locked = false);
574 void par_clear();
576 // Get the start of the unmarked area in this region.
577 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
578 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
580 // Note the start or end of marking. This tells the heap region
581 // that the collector is about to start or has finished (concurrently)
582 // marking the heap.
584 // Notify the region that concurrent marking is starting. Initialize
585 // all fields related to the next marking info.
586 inline void note_start_of_marking();
588 // Notify the region that concurrent marking has finished. Copy the
589 // (now finalized) next marking info fields into the prev marking
590 // info fields.
591 inline void note_end_of_marking();
593 // Notify the region that it will be used as to-space during a GC
594 // and we are about to start copying objects into it.
595 inline void note_start_of_copying(bool during_initial_mark);
597 // Notify the region that it ceases being to-space during a GC and
598 // we will not copy objects into it any more.
599 inline void note_end_of_copying(bool during_initial_mark);
601 // Notify the region that we are about to start processing
602 // self-forwarded objects during evac failure handling.
603 void note_self_forwarding_removal_start(bool during_initial_mark,
604 bool during_conc_mark);
606 // Notify the region that we have finished processing self-forwarded
607 // objects during evac failure handling.
608 void note_self_forwarding_removal_end(bool during_initial_mark,
609 bool during_conc_mark,
610 size_t marked_bytes);
612 // Returns "false" iff no object in the region was allocated when the
613 // last mark phase ended.
614 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
616 void reset_during_compaction() {
617 assert(isHumongous() && startsHumongous(),
618 "should only be called for starts humongous regions");
620 zero_marked_bytes();
621 init_top_at_mark_start();
622 }
624 void calc_gc_efficiency(void);
625 double gc_efficiency() { return _gc_efficiency;}
627 int young_index_in_cset() const { return _young_index_in_cset; }
628 void set_young_index_in_cset(int index) {
629 assert( (index == -1) || is_young(), "pre-condition" );
630 _young_index_in_cset = index;
631 }
633 int age_in_surv_rate_group() {
634 assert( _surv_rate_group != NULL, "pre-condition" );
635 assert( _age_index > -1, "pre-condition" );
636 return _surv_rate_group->age_in_group(_age_index);
637 }
639 void record_surv_words_in_group(size_t words_survived) {
640 assert( _surv_rate_group != NULL, "pre-condition" );
641 assert( _age_index > -1, "pre-condition" );
642 int age_in_group = age_in_surv_rate_group();
643 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
644 }
646 int age_in_surv_rate_group_cond() {
647 if (_surv_rate_group != NULL)
648 return age_in_surv_rate_group();
649 else
650 return -1;
651 }
653 SurvRateGroup* surv_rate_group() {
654 return _surv_rate_group;
655 }
657 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
658 assert( surv_rate_group != NULL, "pre-condition" );
659 assert( _surv_rate_group == NULL, "pre-condition" );
660 assert( is_young(), "pre-condition" );
662 _surv_rate_group = surv_rate_group;
663 _age_index = surv_rate_group->next_age_index();
664 }
666 void uninstall_surv_rate_group() {
667 if (_surv_rate_group != NULL) {
668 assert( _age_index > -1, "pre-condition" );
669 assert( is_young(), "pre-condition" );
671 _surv_rate_group = NULL;
672 _age_index = -1;
673 } else {
674 assert( _age_index == -1, "pre-condition" );
675 }
676 }
678 void set_free() { _type.set_free(); }
680 void set_eden() { _type.set_eden(); }
681 void set_eden_pre_gc() { _type.set_eden_pre_gc(); }
682 void set_survivor() { _type.set_survivor(); }
684 void set_old() { _type.set_old(); }
686 // Determine if an object has been allocated since the last
687 // mark performed by the collector. This returns true iff the object
688 // is within the unmarked area of the region.
689 bool obj_allocated_since_prev_marking(oop obj) const {
690 return (HeapWord *) obj >= prev_top_at_mark_start();
691 }
692 bool obj_allocated_since_next_marking(oop obj) const {
693 return (HeapWord *) obj >= next_top_at_mark_start();
694 }
696 // For parallel heapRegion traversal.
697 bool claimHeapRegion(int claimValue);
698 jint claim_value() { return _claimed; }
699 // Use this carefully: only when you're sure no one is claiming...
700 void set_claim_value(int claimValue) { _claimed = claimValue; }
702 // Returns the "evacuation_failed" property of the region.
703 bool evacuation_failed() { return _evacuation_failed; }
705 // Sets the "evacuation_failed" property of the region.
706 void set_evacuation_failed(bool b) {
707 _evacuation_failed = b;
709 if (b) {
710 _next_marked_bytes = 0;
711 }
712 }
714 // Requires that "mr" be entirely within the region.
715 // Apply "cl->do_object" to all objects that intersect with "mr".
716 // If the iteration encounters an unparseable portion of the region,
717 // or if "cl->abort()" is true after a closure application,
718 // terminate the iteration and return the address of the start of the
719 // subregion that isn't done. (The two can be distinguished by querying
720 // "cl->abort()".) Return of "NULL" indicates that the iteration
721 // completed.
722 HeapWord*
723 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
725 // filter_young: if true and the region is a young region then we
726 // skip the iteration.
727 // card_ptr: if not NULL, and we decide that the card is not young
728 // and we iterate over it, we'll clean the card before we start the
729 // iteration.
730 HeapWord*
731 oops_on_card_seq_iterate_careful(MemRegion mr,
732 FilterOutOfRegionClosure* cl,
733 bool filter_young,
734 jbyte* card_ptr);
736 size_t recorded_rs_length() const { return _recorded_rs_length; }
737 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
738 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }
740 void set_recorded_rs_length(size_t rs_length) {
741 _recorded_rs_length = rs_length;
742 }
744 void set_predicted_elapsed_time_ms(double ms) {
745 _predicted_elapsed_time_ms = ms;
746 }
748 void set_predicted_bytes_to_copy(size_t bytes) {
749 _predicted_bytes_to_copy = bytes;
750 }
752 virtual CompactibleSpace* next_compaction_space() const;
754 virtual void reset_after_compaction();
756 // Routines for managing a list of code roots (attached to the
757 // this region's RSet) that point into this heap region.
758 void add_strong_code_root(nmethod* nm);
759 void add_strong_code_root_locked(nmethod* nm);
760 void remove_strong_code_root(nmethod* nm);
762 // Applies blk->do_code_blob() to each of the entries in
763 // the strong code roots list for this region
764 void strong_code_roots_do(CodeBlobClosure* blk) const;
766 // Verify that the entries on the strong code root list for this
767 // region are live and include at least one pointer into this region.
768 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
770 void print() const;
771 void print_on(outputStream* st) const;
773 // vo == UsePrevMarking -> use "prev" marking information,
774 // vo == UseNextMarking -> use "next" marking information
775 // vo == UseMarkWord -> use the mark word in the object header
776 //
777 // NOTE: Only the "prev" marking information is guaranteed to be
778 // consistent most of the time, so most calls to this should use
779 // vo == UsePrevMarking.
780 // Currently, there is only one case where this is called with
781 // vo == UseNextMarking, which is to verify the "next" marking
782 // information at the end of remark.
783 // Currently there is only one place where this is called with
784 // vo == UseMarkWord, which is to verify the marking during a
785 // full GC.
786 void verify(VerifyOption vo, bool *failures) const;
788 // Override; it uses the "prev" marking information
789 virtual void verify() const;
790 };
792 // HeapRegionClosure is used for iterating over regions.
793 // Terminates the iteration when the "doHeapRegion" method returns "true".
794 class HeapRegionClosure : public StackObj {
795 friend class HeapRegionManager;
796 friend class G1CollectedHeap;
798 bool _complete;
799 void incomplete() { _complete = false; }
801 public:
802 HeapRegionClosure(): _complete(true) {}
804 // Typically called on each region until it returns true.
805 virtual bool doHeapRegion(HeapRegion* r) = 0;
807 // True after iteration if the closure was applied to all heap regions
808 // and returned "false" in all cases.
809 bool complete() { return _complete; }
810 };
812 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP