Tue, 09 Sep 2014 00:05:25 +0200
8057658: Enable G1 FullGC extensions
Summary: Refactored the G1 FullGC code to enable it to be extended.
Reviewed-by: mgerdin, brutisso
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/survRateGroup.hpp"
32 #include "gc_implementation/shared/ageTable.hpp"
33 #include "gc_implementation/shared/spaceDecorator.hpp"
34 #include "memory/space.inline.hpp"
35 #include "memory/watermark.hpp"
36 #include "utilities/macros.hpp"
38 #if INCLUDE_ALL_GCS
40 // A HeapRegion is the smallest piece of a G1CollectedHeap that
41 // can be collected independently.
43 // NOTE: Although a HeapRegion is a Space, its
44 // Space::initDirtyCardClosure method must not be called.
45 // The problem is that the existence of this method breaks
46 // the independence of barrier sets from remembered sets.
47 // The solution is to remove this method from the definition
48 // of a Space.
50 class HeapRegionRemSet;
51 class HeapRegionRemSetIterator;
52 class HeapRegion;
53 class HeapRegionSetBase;
54 class nmethod;
56 #define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"
57 #define HR_FORMAT_PARAMS(_hr_) \
58 (_hr_)->hrm_index(), \
59 (_hr_)->is_survivor() ? "S" : (_hr_)->is_young() ? "E" : \
60 (_hr_)->startsHumongous() ? "HS" : \
61 (_hr_)->continuesHumongous() ? "HC" : \
62 !(_hr_)->is_empty() ? "O" : "F", \
63 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
65 // sentinel value for hrm_index
66 #define G1_NO_HRM_INDEX ((uint) -1)
68 // A dirty card to oop closure for heap regions. It
69 // knows how to get the G1 heap and how to use the bitmap
70 // in the concurrent marker used by G1 to filter remembered
71 // sets.
73 class HeapRegionDCTOC : public DirtyCardToOopClosure {
74 public:
75 // Specification of possible DirtyCardToOopClosure filtering.
76 enum FilterKind {
77 NoFilterKind,
78 IntoCSFilterKind,
79 OutOfRegionFilterKind
80 };
82 protected:
83 HeapRegion* _hr;
84 FilterKind _fk;
85 G1CollectedHeap* _g1;
87 // Walk the given memory region from bottom to (actual) top
88 // looking for objects and applying the oop closure (_cl) to
89 // them. The base implementation of this treats the area as
90 // blocks, where a block may or may not be an object. Sub-
91 // classes should override this to provide more accurate
92 // or possibly more efficient walking.
93 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
95 public:
96 HeapRegionDCTOC(G1CollectedHeap* g1,
97 HeapRegion* hr, ExtendedOopClosure* cl,
98 CardTableModRefBS::PrecisionStyle precision,
99 FilterKind fk);
100 };
102 // The complicating factor is that BlockOffsetTable diverged
103 // significantly, and we need functionality that is only in the G1 version.
104 // So I copied that code, which led to an alternate G1 version of
105 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
106 // be reconciled, then G1OffsetTableContigSpace could go away.
108 // The idea behind time stamps is the following. Doing a save_marks on
109 // all regions at every GC pause is time consuming (if I remember
110 // well, 10ms or so). So, we would like to do that only for regions
111 // that are GC alloc regions. To achieve this, we use time
112 // stamps. For every evacuation pause, G1CollectedHeap generates a
113 // unique time stamp (essentially a counter that gets
114 // incremented). Every time we want to call save_marks on a region,
115 // we set the saved_mark_word to top and also copy the current GC
116 // time stamp to the time stamp field of the space. Reading the
117 // saved_mark_word involves checking the time stamp of the
118 // region. If it is the same as the current GC time stamp, then we
119 // can safely read the saved_mark_word field, as it is valid. If the
120 // time stamp of the region is not the same as the current GC time
121 // stamp, then we instead read top, as the saved_mark_word field is
122 // invalid. Time stamps (on the regions and also on the
123 // G1CollectedHeap) are reset at every cleanup (we iterate over
124 // the regions anyway) and at the end of a Full GC. The current scheme
125 // that uses sequential unsigned ints will fail only if we have 4b
126 // evacuation pauses between two cleanups, which is _highly_ unlikely.
127 class G1OffsetTableContigSpace: public CompactibleSpace {
128 friend class VMStructs;
129 HeapWord* _top;
130 protected:
131 G1BlockOffsetArrayContigSpace _offsets;
132 Mutex _par_alloc_lock;
133 volatile unsigned _gc_time_stamp;
134 // When we need to retire an allocation region, while other threads
135 // are also concurrently trying to allocate into it, we typically
136 // allocate a dummy object at the end of the region to ensure that
137 // no more allocations can take place in it. However, sometimes we
138 // want to know where the end of the last "real" object we allocated
139 // into the region was and this is what this keeps track.
140 HeapWord* _pre_dummy_top;
142 public:
143 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
144 MemRegion mr);
146 void set_top(HeapWord* value) { _top = value; }
147 HeapWord* top() const { return _top; }
149 protected:
150 // Reset the G1OffsetTableContigSpace.
151 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
153 HeapWord** top_addr() { return &_top; }
154 // Allocation helpers (return NULL if full).
155 inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
156 inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);
158 public:
159 void reset_after_compaction() { set_top(compaction_top()); }
161 size_t used() const { return byte_size(bottom(), top()); }
162 size_t free() const { return byte_size(top(), end()); }
163 bool is_free_block(const HeapWord* p) const { return p >= top(); }
165 MemRegion used_region() const { return MemRegion(bottom(), top()); }
167 void object_iterate(ObjectClosure* blk);
168 void safe_object_iterate(ObjectClosure* blk);
170 void set_bottom(HeapWord* value);
171 void set_end(HeapWord* value);
173 virtual HeapWord* saved_mark_word() const;
174 void record_top_and_timestamp();
175 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
176 unsigned get_gc_time_stamp() { return _gc_time_stamp; }
178 // See the comment above in the declaration of _pre_dummy_top for an
179 // explanation of what it is.
180 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
181 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
182 _pre_dummy_top = pre_dummy_top;
183 }
184 HeapWord* pre_dummy_top() {
185 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
186 }
187 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
189 virtual void clear(bool mangle_space);
191 HeapWord* block_start(const void* p);
192 HeapWord* block_start_const(const void* p) const;
194 void prepare_for_compaction(CompactPoint* cp);
196 // Add offset table update.
197 virtual HeapWord* allocate(size_t word_size);
198 HeapWord* par_allocate(size_t word_size);
200 // MarkSweep support phase3
201 virtual HeapWord* initialize_threshold();
202 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
204 virtual void print() const;
206 void reset_bot() {
207 _offsets.reset_bot();
208 }
210 void update_bot_for_object(HeapWord* start, size_t word_size) {
211 _offsets.alloc_block(start, word_size);
212 }
214 void print_bot_on(outputStream* out) {
215 _offsets.print_on(out);
216 }
217 };
219 class HeapRegion: public G1OffsetTableContigSpace {
220 friend class VMStructs;
221 private:
223 enum HumongousType {
224 NotHumongous = 0,
225 StartsHumongous,
226 ContinuesHumongous
227 };
229 // The remembered set for this region.
230 // (Might want to make this "inline" later, to avoid some alloc failure
231 // issues.)
232 HeapRegionRemSet* _rem_set;
234 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
236 protected:
237 // The index of this region in the heap region sequence.
238 uint _hrm_index;
240 AllocationContext_t _allocation_context;
242 HumongousType _humongous_type;
243 // For a humongous region, region in which it starts.
244 HeapRegion* _humongous_start_region;
245 // For the start region of a humongous sequence, it's original end().
246 HeapWord* _orig_end;
248 // True iff the region is in current collection_set.
249 bool _in_collection_set;
251 // True iff an attempt to evacuate an object in the region failed.
252 bool _evacuation_failed;
254 // A heap region may be a member one of a number of special subsets, each
255 // represented as linked lists through the field below. Currently, there
256 // is only one set:
257 // The collection set.
258 HeapRegion* _next_in_special_set;
260 // next region in the young "generation" region set
261 HeapRegion* _next_young_region;
263 // Next region whose cards need cleaning
264 HeapRegion* _next_dirty_cards_region;
266 // Fields used by the HeapRegionSetBase class and subclasses.
267 HeapRegion* _next;
268 HeapRegion* _prev;
269 #ifdef ASSERT
270 HeapRegionSetBase* _containing_set;
271 #endif // ASSERT
273 // For parallel heapRegion traversal.
274 jint _claimed;
276 // We use concurrent marking to determine the amount of live data
277 // in each heap region.
278 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
279 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
281 // The calculated GC efficiency of the region.
282 double _gc_efficiency;
284 enum YoungType {
285 NotYoung, // a region is not young
286 Young, // a region is young
287 Survivor // a region is young and it contains survivors
288 };
290 volatile YoungType _young_type;
291 int _young_index_in_cset;
292 SurvRateGroup* _surv_rate_group;
293 int _age_index;
295 // The start of the unmarked area. The unmarked area extends from this
296 // word until the top and/or end of the region, and is the part
297 // of the region for which no marking was done, i.e. objects may
298 // have been allocated in this part since the last mark phase.
299 // "prev" is the top at the start of the last completed marking.
300 // "next" is the top at the start of the in-progress marking (if any.)
301 HeapWord* _prev_top_at_mark_start;
302 HeapWord* _next_top_at_mark_start;
303 // If a collection pause is in progress, this is the top at the start
304 // of that pause.
306 void init_top_at_mark_start() {
307 assert(_prev_marked_bytes == 0 &&
308 _next_marked_bytes == 0,
309 "Must be called after zero_marked_bytes.");
310 HeapWord* bot = bottom();
311 _prev_top_at_mark_start = bot;
312 _next_top_at_mark_start = bot;
313 }
315 void set_young_type(YoungType new_type) {
316 //assert(_young_type != new_type, "setting the same type" );
317 // TODO: add more assertions here
318 _young_type = new_type;
319 }
321 // Cached attributes used in the collection set policy information
323 // The RSet length that was added to the total value
324 // for the collection set.
325 size_t _recorded_rs_length;
327 // The predicted elapsed time that was added to total value
328 // for the collection set.
329 double _predicted_elapsed_time_ms;
331 // The predicted number of bytes to copy that was added to
332 // the total value for the collection set.
333 size_t _predicted_bytes_to_copy;
335 public:
336 HeapRegion(uint hrm_index,
337 G1BlockOffsetSharedArray* sharedOffsetArray,
338 MemRegion mr);
340 // Initializing the HeapRegion not only resets the data structure, but also
341 // resets the BOT for that heap region.
342 // The default values for clear_space means that we will do the clearing if
343 // there's clearing to be done ourselves. We also always mangle the space.
344 virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
346 static int LogOfHRGrainBytes;
347 static int LogOfHRGrainWords;
349 static size_t GrainBytes;
350 static size_t GrainWords;
351 static size_t CardsPerRegion;
353 static size_t align_up_to_region_byte_size(size_t sz) {
354 return (sz + (size_t) GrainBytes - 1) &
355 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
356 }
358 static size_t max_region_size();
360 // It sets up the heap region size (GrainBytes / GrainWords), as
361 // well as other related fields that are based on the heap region
362 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
363 // CardsPerRegion). All those fields are considered constant
364 // throughout the JVM's execution, therefore they should only be set
365 // up once during initialization time.
366 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
368 enum ClaimValues {
369 InitialClaimValue = 0,
370 FinalCountClaimValue = 1,
371 NoteEndClaimValue = 2,
372 ScrubRemSetClaimValue = 3,
373 ParVerifyClaimValue = 4,
374 RebuildRSClaimValue = 5,
375 ParEvacFailureClaimValue = 6,
376 AggregateCountClaimValue = 7,
377 VerifyCountClaimValue = 8,
378 ParMarkRootClaimValue = 9
379 };
381 // All allocated blocks are occupied by objects in a HeapRegion
382 bool block_is_obj(const HeapWord* p) const;
384 // Returns the object size for all valid block starts
385 // and the amount of unallocated words if called on top()
386 size_t block_size(const HeapWord* p) const;
388 inline HeapWord* par_allocate_no_bot_updates(size_t word_size);
389 inline HeapWord* allocate_no_bot_updates(size_t word_size);
391 // If this region is a member of a HeapRegionManager, the index in that
392 // sequence, otherwise -1.
393 uint hrm_index() const { return _hrm_index; }
395 // The number of bytes marked live in the region in the last marking phase.
396 size_t marked_bytes() { return _prev_marked_bytes; }
397 size_t live_bytes() {
398 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
399 }
401 // The number of bytes counted in the next marking.
402 size_t next_marked_bytes() { return _next_marked_bytes; }
403 // The number of bytes live wrt the next marking.
404 size_t next_live_bytes() {
405 return
406 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
407 }
409 // A lower bound on the amount of garbage bytes in the region.
410 size_t garbage_bytes() {
411 size_t used_at_mark_start_bytes =
412 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
413 assert(used_at_mark_start_bytes >= marked_bytes(),
414 "Can't mark more than we have.");
415 return used_at_mark_start_bytes - marked_bytes();
416 }
418 // Return the amount of bytes we'll reclaim if we collect this
419 // region. This includes not only the known garbage bytes in the
420 // region but also any unallocated space in it, i.e., [top, end),
421 // since it will also be reclaimed if we collect the region.
422 size_t reclaimable_bytes() {
423 size_t known_live_bytes = live_bytes();
424 assert(known_live_bytes <= capacity(), "sanity");
425 return capacity() - known_live_bytes;
426 }
428 // An upper bound on the number of live bytes in the region.
429 size_t max_live_bytes() { return used() - garbage_bytes(); }
431 void add_to_marked_bytes(size_t incr_bytes) {
432 _next_marked_bytes = _next_marked_bytes + incr_bytes;
433 assert(_next_marked_bytes <= used(), "invariant" );
434 }
436 void zero_marked_bytes() {
437 _prev_marked_bytes = _next_marked_bytes = 0;
438 }
440 bool isHumongous() const { return _humongous_type != NotHumongous; }
441 bool startsHumongous() const { return _humongous_type == StartsHumongous; }
442 bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; }
443 // For a humongous region, region in which it starts.
444 HeapRegion* humongous_start_region() const {
445 return _humongous_start_region;
446 }
448 // Return the number of distinct regions that are covered by this region:
449 // 1 if the region is not humongous, >= 1 if the region is humongous.
450 uint region_num() const {
451 if (!isHumongous()) {
452 return 1U;
453 } else {
454 assert(startsHumongous(), "doesn't make sense on HC regions");
455 assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
456 return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
457 }
458 }
460 // Return the index + 1 of the last HC regions that's associated
461 // with this HS region.
462 uint last_hc_index() const {
463 assert(startsHumongous(), "don't call this otherwise");
464 return hrm_index() + region_num();
465 }
467 // Same as Space::is_in_reserved, but will use the original size of the region.
468 // The original size is different only for start humongous regions. They get
469 // their _end set up to be the end of the last continues region of the
470 // corresponding humongous object.
471 bool is_in_reserved_raw(const void* p) const {
472 return _bottom <= p && p < _orig_end;
473 }
475 // Makes the current region be a "starts humongous" region, i.e.,
476 // the first region in a series of one or more contiguous regions
477 // that will contain a single "humongous" object. The two parameters
478 // are as follows:
479 //
480 // new_top : The new value of the top field of this region which
481 // points to the end of the humongous object that's being
482 // allocated. If there is more than one region in the series, top
483 // will lie beyond this region's original end field and on the last
484 // region in the series.
485 //
486 // new_end : The new value of the end field of this region which
487 // points to the end of the last region in the series. If there is
488 // one region in the series (namely: this one) end will be the same
489 // as the original end of this region.
490 //
491 // Updating top and end as described above makes this region look as
492 // if it spans the entire space taken up by all the regions in the
493 // series and an single allocation moved its top to new_top. This
494 // ensures that the space (capacity / allocated) taken up by all
495 // humongous regions can be calculated by just looking at the
496 // "starts humongous" regions and by ignoring the "continues
497 // humongous" regions.
498 void set_startsHumongous(HeapWord* new_top, HeapWord* new_end);
500 // Makes the current region be a "continues humongous'
501 // region. first_hr is the "start humongous" region of the series
502 // which this region will be part of.
503 void set_continuesHumongous(HeapRegion* first_hr);
505 // Unsets the humongous-related fields on the region.
506 void set_notHumongous();
508 // If the region has a remembered set, return a pointer to it.
509 HeapRegionRemSet* rem_set() const {
510 return _rem_set;
511 }
513 // True iff the region is in current collection_set.
514 bool in_collection_set() const {
515 return _in_collection_set;
516 }
517 void set_in_collection_set(bool b) {
518 _in_collection_set = b;
519 }
520 HeapRegion* next_in_collection_set() {
521 assert(in_collection_set(), "should only invoke on member of CS.");
522 assert(_next_in_special_set == NULL ||
523 _next_in_special_set->in_collection_set(),
524 "Malformed CS.");
525 return _next_in_special_set;
526 }
527 void set_next_in_collection_set(HeapRegion* r) {
528 assert(in_collection_set(), "should only invoke on member of CS.");
529 assert(r == NULL || r->in_collection_set(), "Malformed CS.");
530 _next_in_special_set = r;
531 }
533 void set_allocation_context(AllocationContext_t context) {
534 _allocation_context = context;
535 }
537 AllocationContext_t allocation_context() const {
538 return _allocation_context;
539 }
541 // Methods used by the HeapRegionSetBase class and subclasses.
543 // Getter and setter for the next and prev fields used to link regions into
544 // linked lists.
545 HeapRegion* next() { return _next; }
546 HeapRegion* prev() { return _prev; }
548 void set_next(HeapRegion* next) { _next = next; }
549 void set_prev(HeapRegion* prev) { _prev = prev; }
551 // Every region added to a set is tagged with a reference to that
552 // set. This is used for doing consistency checking to make sure that
553 // the contents of a set are as they should be and it's only
554 // available in non-product builds.
555 #ifdef ASSERT
556 void set_containing_set(HeapRegionSetBase* containing_set) {
557 assert((containing_set == NULL && _containing_set != NULL) ||
558 (containing_set != NULL && _containing_set == NULL),
559 err_msg("containing_set: "PTR_FORMAT" "
560 "_containing_set: "PTR_FORMAT,
561 p2i(containing_set), p2i(_containing_set)));
563 _containing_set = containing_set;
564 }
566 HeapRegionSetBase* containing_set() { return _containing_set; }
567 #else // ASSERT
568 void set_containing_set(HeapRegionSetBase* containing_set) { }
570 // containing_set() is only used in asserts so there's no reason
571 // to provide a dummy version of it.
572 #endif // ASSERT
574 HeapRegion* get_next_young_region() { return _next_young_region; }
575 void set_next_young_region(HeapRegion* hr) {
576 _next_young_region = hr;
577 }
579 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
580 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
581 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
582 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
584 HeapWord* orig_end() const { return _orig_end; }
586 // Reset HR stuff to default values.
587 void hr_clear(bool par, bool clear_space, bool locked = false);
588 void par_clear();
590 // Get the start of the unmarked area in this region.
591 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
592 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
594 // Note the start or end of marking. This tells the heap region
595 // that the collector is about to start or has finished (concurrently)
596 // marking the heap.
598 // Notify the region that concurrent marking is starting. Initialize
599 // all fields related to the next marking info.
600 inline void note_start_of_marking();
602 // Notify the region that concurrent marking has finished. Copy the
603 // (now finalized) next marking info fields into the prev marking
604 // info fields.
605 inline void note_end_of_marking();
607 // Notify the region that it will be used as to-space during a GC
608 // and we are about to start copying objects into it.
609 inline void note_start_of_copying(bool during_initial_mark);
611 // Notify the region that it ceases being to-space during a GC and
612 // we will not copy objects into it any more.
613 inline void note_end_of_copying(bool during_initial_mark);
615 // Notify the region that we are about to start processing
616 // self-forwarded objects during evac failure handling.
617 void note_self_forwarding_removal_start(bool during_initial_mark,
618 bool during_conc_mark);
620 // Notify the region that we have finished processing self-forwarded
621 // objects during evac failure handling.
622 void note_self_forwarding_removal_end(bool during_initial_mark,
623 bool during_conc_mark,
624 size_t marked_bytes);
626 // Returns "false" iff no object in the region was allocated when the
627 // last mark phase ended.
628 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
630 void reset_during_compaction() {
631 assert(isHumongous() && startsHumongous(),
632 "should only be called for starts humongous regions");
634 zero_marked_bytes();
635 init_top_at_mark_start();
636 }
638 void calc_gc_efficiency(void);
639 double gc_efficiency() { return _gc_efficiency;}
641 bool is_young() const { return _young_type != NotYoung; }
642 bool is_survivor() const { return _young_type == Survivor; }
644 int young_index_in_cset() const { return _young_index_in_cset; }
645 void set_young_index_in_cset(int index) {
646 assert( (index == -1) || is_young(), "pre-condition" );
647 _young_index_in_cset = index;
648 }
650 int age_in_surv_rate_group() {
651 assert( _surv_rate_group != NULL, "pre-condition" );
652 assert( _age_index > -1, "pre-condition" );
653 return _surv_rate_group->age_in_group(_age_index);
654 }
656 void record_surv_words_in_group(size_t words_survived) {
657 assert( _surv_rate_group != NULL, "pre-condition" );
658 assert( _age_index > -1, "pre-condition" );
659 int age_in_group = age_in_surv_rate_group();
660 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
661 }
663 int age_in_surv_rate_group_cond() {
664 if (_surv_rate_group != NULL)
665 return age_in_surv_rate_group();
666 else
667 return -1;
668 }
670 SurvRateGroup* surv_rate_group() {
671 return _surv_rate_group;
672 }
674 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
675 assert( surv_rate_group != NULL, "pre-condition" );
676 assert( _surv_rate_group == NULL, "pre-condition" );
677 assert( is_young(), "pre-condition" );
679 _surv_rate_group = surv_rate_group;
680 _age_index = surv_rate_group->next_age_index();
681 }
683 void uninstall_surv_rate_group() {
684 if (_surv_rate_group != NULL) {
685 assert( _age_index > -1, "pre-condition" );
686 assert( is_young(), "pre-condition" );
688 _surv_rate_group = NULL;
689 _age_index = -1;
690 } else {
691 assert( _age_index == -1, "pre-condition" );
692 }
693 }
695 void set_young() { set_young_type(Young); }
697 void set_survivor() { set_young_type(Survivor); }
699 void set_not_young() { set_young_type(NotYoung); }
701 // Determine if an object has been allocated since the last
702 // mark performed by the collector. This returns true iff the object
703 // is within the unmarked area of the region.
704 bool obj_allocated_since_prev_marking(oop obj) const {
705 return (HeapWord *) obj >= prev_top_at_mark_start();
706 }
707 bool obj_allocated_since_next_marking(oop obj) const {
708 return (HeapWord *) obj >= next_top_at_mark_start();
709 }
711 // For parallel heapRegion traversal.
712 bool claimHeapRegion(int claimValue);
713 jint claim_value() { return _claimed; }
714 // Use this carefully: only when you're sure no one is claiming...
715 void set_claim_value(int claimValue) { _claimed = claimValue; }
717 // Returns the "evacuation_failed" property of the region.
718 bool evacuation_failed() { return _evacuation_failed; }
720 // Sets the "evacuation_failed" property of the region.
721 void set_evacuation_failed(bool b) {
722 _evacuation_failed = b;
724 if (b) {
725 _next_marked_bytes = 0;
726 }
727 }
729 // Requires that "mr" be entirely within the region.
730 // Apply "cl->do_object" to all objects that intersect with "mr".
731 // If the iteration encounters an unparseable portion of the region,
732 // or if "cl->abort()" is true after a closure application,
733 // terminate the iteration and return the address of the start of the
734 // subregion that isn't done. (The two can be distinguished by querying
735 // "cl->abort()".) Return of "NULL" indicates that the iteration
736 // completed.
737 HeapWord*
738 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
740 // filter_young: if true and the region is a young region then we
741 // skip the iteration.
742 // card_ptr: if not NULL, and we decide that the card is not young
743 // and we iterate over it, we'll clean the card before we start the
744 // iteration.
745 HeapWord*
746 oops_on_card_seq_iterate_careful(MemRegion mr,
747 FilterOutOfRegionClosure* cl,
748 bool filter_young,
749 jbyte* card_ptr);
751 // A version of block start that is guaranteed to find *some* block
752 // boundary at or before "p", but does not object iteration, and may
753 // therefore be used safely when the heap is unparseable.
754 HeapWord* block_start_careful(const void* p) const {
755 return _offsets.block_start_careful(p);
756 }
758 // Requires that "addr" is within the region. Returns the start of the
759 // first ("careful") block that starts at or after "addr", or else the
760 // "end" of the region if there is no such block.
761 HeapWord* next_block_start_careful(HeapWord* addr);
763 size_t recorded_rs_length() const { return _recorded_rs_length; }
764 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
765 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }
767 void set_recorded_rs_length(size_t rs_length) {
768 _recorded_rs_length = rs_length;
769 }
771 void set_predicted_elapsed_time_ms(double ms) {
772 _predicted_elapsed_time_ms = ms;
773 }
775 void set_predicted_bytes_to_copy(size_t bytes) {
776 _predicted_bytes_to_copy = bytes;
777 }
779 virtual CompactibleSpace* next_compaction_space() const;
781 virtual void reset_after_compaction();
783 // Routines for managing a list of code roots (attached to the
784 // this region's RSet) that point into this heap region.
785 void add_strong_code_root(nmethod* nm);
786 void remove_strong_code_root(nmethod* nm);
788 // During a collection, migrate the successfully evacuated
789 // strong code roots that referenced into this region to the
790 // new regions that they now point into. Unsuccessfully
791 // evacuated code roots are not migrated.
792 void migrate_strong_code_roots();
794 // Applies blk->do_code_blob() to each of the entries in
795 // the strong code roots list for this region
796 void strong_code_roots_do(CodeBlobClosure* blk) const;
798 // Verify that the entries on the strong code root list for this
799 // region are live and include at least one pointer into this region.
800 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
802 void print() const;
803 void print_on(outputStream* st) const;
805 // vo == UsePrevMarking -> use "prev" marking information,
806 // vo == UseNextMarking -> use "next" marking information
807 // vo == UseMarkWord -> use the mark word in the object header
808 //
809 // NOTE: Only the "prev" marking information is guaranteed to be
810 // consistent most of the time, so most calls to this should use
811 // vo == UsePrevMarking.
812 // Currently, there is only one case where this is called with
813 // vo == UseNextMarking, which is to verify the "next" marking
814 // information at the end of remark.
815 // Currently there is only one place where this is called with
816 // vo == UseMarkWord, which is to verify the marking during a
817 // full GC.
818 void verify(VerifyOption vo, bool *failures) const;
820 // Override; it uses the "prev" marking information
821 virtual void verify() const;
822 };
824 // HeapRegionClosure is used for iterating over regions.
825 // Terminates the iteration when the "doHeapRegion" method returns "true".
826 class HeapRegionClosure : public StackObj {
827 friend class HeapRegionManager;
828 friend class G1CollectedHeap;
830 bool _complete;
831 void incomplete() { _complete = false; }
833 public:
834 HeapRegionClosure(): _complete(true) {}
836 // Typically called on each region until it returns true.
837 virtual bool doHeapRegion(HeapRegion* r) = 0;
839 // True after iteration if the closure was applied to all heap regions
840 // and returned "false" in all cases.
841 bool complete() { return _complete; }
842 };
844 #endif // INCLUDE_ALL_GCS
846 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP