Thu, 21 Aug 2014 16:44:41 +0200
8055098: WB API should be extended to provide information about size and age of object.
Summary: Extend the WhiteBox API to provide information about the size and age of objects. Further add a mechanism to trigger a young GC.
Reviewed-by: tschatzl, sjohanss
Contributed-by: Leonid Mesnik <leonid.mesnik@oracle.com>
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/g1BlockOffsetTable.hpp"
29 #include "gc_implementation/g1/g1_specialized_oop_closures.hpp"
30 #include "gc_implementation/g1/survRateGroup.hpp"
31 #include "gc_implementation/shared/ageTable.hpp"
32 #include "gc_implementation/shared/spaceDecorator.hpp"
33 #include "memory/space.inline.hpp"
34 #include "memory/watermark.hpp"
35 #include "utilities/macros.hpp"
37 #if INCLUDE_ALL_GCS
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_)->hrs_index(), \
58 (_hr_)->is_survivor() ? "S" : (_hr_)->is_young() ? "E" : \
59 (_hr_)->startsHumongous() ? "HS" : \
60 (_hr_)->continuesHumongous() ? "HC" : \
61 !(_hr_)->is_empty() ? "O" : "F", \
62 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
64 // sentinel value for hrs_index
65 #define G1_NO_HRS_INDEX ((uint) -1)
67 // A dirty card to oop closure for heap regions. It
68 // knows how to get the G1 heap and how to use the bitmap
69 // in the concurrent marker used by G1 to filter remembered
70 // sets.
72 class HeapRegionDCTOC : public DirtyCardToOopClosure {
73 public:
74 // Specification of possible DirtyCardToOopClosure filtering.
75 enum FilterKind {
76 NoFilterKind,
77 IntoCSFilterKind,
78 OutOfRegionFilterKind
79 };
81 protected:
82 HeapRegion* _hr;
83 FilterKind _fk;
84 G1CollectedHeap* _g1;
86 // Walk the given memory region from bottom to (actual) top
87 // looking for objects and applying the oop closure (_cl) to
88 // them. The base implementation of this treats the area as
89 // blocks, where a block may or may not be an object. Sub-
90 // classes should override this to provide more accurate
91 // or possibly more efficient walking.
92 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
94 public:
95 HeapRegionDCTOC(G1CollectedHeap* g1,
96 HeapRegion* hr, ExtendedOopClosure* cl,
97 CardTableModRefBS::PrecisionStyle precision,
98 FilterKind fk);
99 };
101 // The complicating factor is that BlockOffsetTable diverged
102 // significantly, and we need functionality that is only in the G1 version.
103 // So I copied that code, which led to an alternate G1 version of
104 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
105 // be reconciled, then G1OffsetTableContigSpace could go away.
107 // The idea behind time stamps is the following. Doing a save_marks on
108 // all regions at every GC pause is time consuming (if I remember
109 // well, 10ms or so). So, we would like to do that only for regions
110 // that are GC alloc regions. To achieve this, we use time
111 // stamps. For every evacuation pause, G1CollectedHeap generates a
112 // unique time stamp (essentially a counter that gets
113 // incremented). Every time we want to call save_marks on a region,
114 // we set the saved_mark_word to top and also copy the current GC
115 // time stamp to the time stamp field of the space. Reading the
116 // saved_mark_word involves checking the time stamp of the
117 // region. If it is the same as the current GC time stamp, then we
118 // can safely read the saved_mark_word field, as it is valid. If the
119 // time stamp of the region is not the same as the current GC time
120 // stamp, then we instead read top, as the saved_mark_word field is
121 // invalid. Time stamps (on the regions and also on the
122 // G1CollectedHeap) are reset at every cleanup (we iterate over
123 // the regions anyway) and at the end of a Full GC. The current scheme
124 // that uses sequential unsigned ints will fail only if we have 4b
125 // evacuation pauses between two cleanups, which is _highly_ unlikely.
126 class G1OffsetTableContigSpace: public CompactibleSpace {
127 friend class VMStructs;
128 HeapWord* _top;
129 protected:
130 G1BlockOffsetArrayContigSpace _offsets;
131 Mutex _par_alloc_lock;
132 volatile unsigned _gc_time_stamp;
133 // When we need to retire an allocation region, while other threads
134 // are also concurrently trying to allocate into it, we typically
135 // allocate a dummy object at the end of the region to ensure that
136 // no more allocations can take place in it. However, sometimes we
137 // want to know where the end of the last "real" object we allocated
138 // into the region was and this is what this keeps track.
139 HeapWord* _pre_dummy_top;
141 public:
142 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
143 MemRegion mr);
145 void set_top(HeapWord* value) { _top = value; }
146 HeapWord* top() const { return _top; }
148 protected:
149 // Reset the G1OffsetTableContigSpace.
150 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
152 HeapWord** top_addr() { return &_top; }
153 // Allocation helpers (return NULL if full).
154 inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
155 inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);
157 public:
158 void reset_after_compaction() { set_top(compaction_top()); }
160 size_t used() const { return byte_size(bottom(), top()); }
161 size_t free() const { return byte_size(top(), end()); }
162 bool is_free_block(const HeapWord* p) const { return p >= top(); }
164 MemRegion used_region() const { return MemRegion(bottom(), top()); }
166 void object_iterate(ObjectClosure* blk);
167 void safe_object_iterate(ObjectClosure* blk);
169 void set_bottom(HeapWord* value);
170 void set_end(HeapWord* value);
172 virtual HeapWord* saved_mark_word() const;
173 void record_top_and_timestamp();
174 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
175 unsigned get_gc_time_stamp() { return _gc_time_stamp; }
177 // See the comment above in the declaration of _pre_dummy_top for an
178 // explanation of what it is.
179 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
180 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
181 _pre_dummy_top = pre_dummy_top;
182 }
183 HeapWord* pre_dummy_top() {
184 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
185 }
186 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
188 virtual void clear(bool mangle_space);
190 HeapWord* block_start(const void* p);
191 HeapWord* block_start_const(const void* p) const;
193 void prepare_for_compaction(CompactPoint* cp);
195 // Add offset table update.
196 virtual HeapWord* allocate(size_t word_size);
197 HeapWord* par_allocate(size_t word_size);
199 // MarkSweep support phase3
200 virtual HeapWord* initialize_threshold();
201 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
203 virtual void print() const;
205 void reset_bot() {
206 _offsets.reset_bot();
207 }
209 void update_bot_for_object(HeapWord* start, size_t word_size) {
210 _offsets.alloc_block(start, word_size);
211 }
213 void print_bot_on(outputStream* out) {
214 _offsets.print_on(out);
215 }
216 };
218 class HeapRegion: public G1OffsetTableContigSpace {
219 friend class VMStructs;
220 private:
222 enum HumongousType {
223 NotHumongous = 0,
224 StartsHumongous,
225 ContinuesHumongous
226 };
228 // The remembered set for this region.
229 // (Might want to make this "inline" later, to avoid some alloc failure
230 // issues.)
231 HeapRegionRemSet* _rem_set;
233 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
235 protected:
236 // The index of this region in the heap region sequence.
237 uint _hrs_index;
239 HumongousType _humongous_type;
240 // For a humongous region, region in which it starts.
241 HeapRegion* _humongous_start_region;
242 // For the start region of a humongous sequence, it's original end().
243 HeapWord* _orig_end;
245 // True iff the region is in current collection_set.
246 bool _in_collection_set;
248 // True iff an attempt to evacuate an object in the region failed.
249 bool _evacuation_failed;
251 // A heap region may be a member one of a number of special subsets, each
252 // represented as linked lists through the field below. Currently, there
253 // is only one set:
254 // The collection set.
255 HeapRegion* _next_in_special_set;
257 // next region in the young "generation" region set
258 HeapRegion* _next_young_region;
260 // Next region whose cards need cleaning
261 HeapRegion* _next_dirty_cards_region;
263 // Fields used by the HeapRegionSetBase class and subclasses.
264 HeapRegion* _next;
265 HeapRegion* _prev;
266 #ifdef ASSERT
267 HeapRegionSetBase* _containing_set;
268 #endif // ASSERT
270 // For parallel heapRegion traversal.
271 jint _claimed;
273 // We use concurrent marking to determine the amount of live data
274 // in each heap region.
275 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
276 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
278 // The calculated GC efficiency of the region.
279 double _gc_efficiency;
281 enum YoungType {
282 NotYoung, // a region is not young
283 Young, // a region is young
284 Survivor // a region is young and it contains survivors
285 };
287 volatile YoungType _young_type;
288 int _young_index_in_cset;
289 SurvRateGroup* _surv_rate_group;
290 int _age_index;
292 // The start of the unmarked area. The unmarked area extends from this
293 // word until the top and/or end of the region, and is the part
294 // of the region for which no marking was done, i.e. objects may
295 // have been allocated in this part since the last mark phase.
296 // "prev" is the top at the start of the last completed marking.
297 // "next" is the top at the start of the in-progress marking (if any.)
298 HeapWord* _prev_top_at_mark_start;
299 HeapWord* _next_top_at_mark_start;
300 // If a collection pause is in progress, this is the top at the start
301 // of that pause.
303 void init_top_at_mark_start() {
304 assert(_prev_marked_bytes == 0 &&
305 _next_marked_bytes == 0,
306 "Must be called after zero_marked_bytes.");
307 HeapWord* bot = bottom();
308 _prev_top_at_mark_start = bot;
309 _next_top_at_mark_start = bot;
310 }
312 void set_young_type(YoungType new_type) {
313 //assert(_young_type != new_type, "setting the same type" );
314 // TODO: add more assertions here
315 _young_type = new_type;
316 }
318 // Cached attributes used in the collection set policy information
320 // The RSet length that was added to the total value
321 // for the collection set.
322 size_t _recorded_rs_length;
324 // The predicted elapsed time that was added to total value
325 // for the collection set.
326 double _predicted_elapsed_time_ms;
328 // The predicted number of bytes to copy that was added to
329 // the total value for the collection set.
330 size_t _predicted_bytes_to_copy;
332 public:
333 HeapRegion(uint hrs_index,
334 G1BlockOffsetSharedArray* sharedOffsetArray,
335 MemRegion mr);
337 // Initializing the HeapRegion not only resets the data structure, but also
338 // resets the BOT for that heap region.
339 // The default values for clear_space means that we will do the clearing if
340 // there's clearing to be done ourselves. We also always mangle the space.
341 virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
343 static int LogOfHRGrainBytes;
344 static int LogOfHRGrainWords;
346 static size_t GrainBytes;
347 static size_t GrainWords;
348 static size_t CardsPerRegion;
350 static size_t align_up_to_region_byte_size(size_t sz) {
351 return (sz + (size_t) GrainBytes - 1) &
352 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
353 }
355 static size_t max_region_size();
357 // It sets up the heap region size (GrainBytes / GrainWords), as
358 // well as other related fields that are based on the heap region
359 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
360 // CardsPerRegion). All those fields are considered constant
361 // throughout the JVM's execution, therefore they should only be set
362 // up once during initialization time.
363 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
365 enum ClaimValues {
366 InitialClaimValue = 0,
367 FinalCountClaimValue = 1,
368 NoteEndClaimValue = 2,
369 ScrubRemSetClaimValue = 3,
370 ParVerifyClaimValue = 4,
371 RebuildRSClaimValue = 5,
372 ParEvacFailureClaimValue = 6,
373 AggregateCountClaimValue = 7,
374 VerifyCountClaimValue = 8,
375 ParMarkRootClaimValue = 9
376 };
378 // All allocated blocks are occupied by objects in a HeapRegion
379 bool block_is_obj(const HeapWord* p) const;
381 // Returns the object size for all valid block starts
382 // and the amount of unallocated words if called on top()
383 size_t block_size(const HeapWord* p) const;
385 inline HeapWord* par_allocate_no_bot_updates(size_t word_size);
386 inline HeapWord* allocate_no_bot_updates(size_t word_size);
388 // If this region is a member of a HeapRegionSeq, the index in that
389 // sequence, otherwise -1.
390 uint hrs_index() const { return _hrs_index; }
392 // The number of bytes marked live in the region in the last marking phase.
393 size_t marked_bytes() { return _prev_marked_bytes; }
394 size_t live_bytes() {
395 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
396 }
398 // The number of bytes counted in the next marking.
399 size_t next_marked_bytes() { return _next_marked_bytes; }
400 // The number of bytes live wrt the next marking.
401 size_t next_live_bytes() {
402 return
403 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
404 }
406 // A lower bound on the amount of garbage bytes in the region.
407 size_t garbage_bytes() {
408 size_t used_at_mark_start_bytes =
409 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
410 assert(used_at_mark_start_bytes >= marked_bytes(),
411 "Can't mark more than we have.");
412 return used_at_mark_start_bytes - marked_bytes();
413 }
415 // Return the amount of bytes we'll reclaim if we collect this
416 // region. This includes not only the known garbage bytes in the
417 // region but also any unallocated space in it, i.e., [top, end),
418 // since it will also be reclaimed if we collect the region.
419 size_t reclaimable_bytes() {
420 size_t known_live_bytes = live_bytes();
421 assert(known_live_bytes <= capacity(), "sanity");
422 return capacity() - known_live_bytes;
423 }
425 // An upper bound on the number of live bytes in the region.
426 size_t max_live_bytes() { return used() - garbage_bytes(); }
428 void add_to_marked_bytes(size_t incr_bytes) {
429 _next_marked_bytes = _next_marked_bytes + incr_bytes;
430 assert(_next_marked_bytes <= used(), "invariant" );
431 }
433 void zero_marked_bytes() {
434 _prev_marked_bytes = _next_marked_bytes = 0;
435 }
437 bool isHumongous() const { return _humongous_type != NotHumongous; }
438 bool startsHumongous() const { return _humongous_type == StartsHumongous; }
439 bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; }
440 // For a humongous region, region in which it starts.
441 HeapRegion* humongous_start_region() const {
442 return _humongous_start_region;
443 }
445 // Return the number of distinct regions that are covered by this region:
446 // 1 if the region is not humongous, >= 1 if the region is humongous.
447 uint region_num() const {
448 if (!isHumongous()) {
449 return 1U;
450 } else {
451 assert(startsHumongous(), "doesn't make sense on HC regions");
452 assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
453 return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
454 }
455 }
457 // Return the index + 1 of the last HC regions that's associated
458 // with this HS region.
459 uint last_hc_index() const {
460 assert(startsHumongous(), "don't call this otherwise");
461 return hrs_index() + region_num();
462 }
464 // Same as Space::is_in_reserved, but will use the original size of the region.
465 // The original size is different only for start humongous regions. They get
466 // their _end set up to be the end of the last continues region of the
467 // corresponding humongous object.
468 bool is_in_reserved_raw(const void* p) const {
469 return _bottom <= p && p < _orig_end;
470 }
472 // Makes the current region be a "starts humongous" region, i.e.,
473 // the first region in a series of one or more contiguous regions
474 // that will contain a single "humongous" object. The two parameters
475 // are as follows:
476 //
477 // new_top : The new value of the top field of this region which
478 // points to the end of the humongous object that's being
479 // allocated. If there is more than one region in the series, top
480 // will lie beyond this region's original end field and on the last
481 // region in the series.
482 //
483 // new_end : The new value of the end field of this region which
484 // points to the end of the last region in the series. If there is
485 // one region in the series (namely: this one) end will be the same
486 // as the original end of this region.
487 //
488 // Updating top and end as described above makes this region look as
489 // if it spans the entire space taken up by all the regions in the
490 // series and an single allocation moved its top to new_top. This
491 // ensures that the space (capacity / allocated) taken up by all
492 // humongous regions can be calculated by just looking at the
493 // "starts humongous" regions and by ignoring the "continues
494 // humongous" regions.
495 void set_startsHumongous(HeapWord* new_top, HeapWord* new_end);
497 // Makes the current region be a "continues humongous'
498 // region. first_hr is the "start humongous" region of the series
499 // which this region will be part of.
500 void set_continuesHumongous(HeapRegion* first_hr);
502 // Unsets the humongous-related fields on the region.
503 void set_notHumongous();
505 // If the region has a remembered set, return a pointer to it.
506 HeapRegionRemSet* rem_set() const {
507 return _rem_set;
508 }
510 // True iff the region is in current collection_set.
511 bool in_collection_set() const {
512 return _in_collection_set;
513 }
514 void set_in_collection_set(bool b) {
515 _in_collection_set = b;
516 }
517 HeapRegion* next_in_collection_set() {
518 assert(in_collection_set(), "should only invoke on member of CS.");
519 assert(_next_in_special_set == NULL ||
520 _next_in_special_set->in_collection_set(),
521 "Malformed CS.");
522 return _next_in_special_set;
523 }
524 void set_next_in_collection_set(HeapRegion* r) {
525 assert(in_collection_set(), "should only invoke on member of CS.");
526 assert(r == NULL || r->in_collection_set(), "Malformed CS.");
527 _next_in_special_set = r;
528 }
530 // Methods used by the HeapRegionSetBase class and subclasses.
532 // Getter and setter for the next and prev fields used to link regions into
533 // linked lists.
534 HeapRegion* next() { return _next; }
535 HeapRegion* prev() { return _prev; }
537 void set_next(HeapRegion* next) { _next = next; }
538 void set_prev(HeapRegion* prev) { _prev = prev; }
540 // Every region added to a set is tagged with a reference to that
541 // set. This is used for doing consistency checking to make sure that
542 // the contents of a set are as they should be and it's only
543 // available in non-product builds.
544 #ifdef ASSERT
545 void set_containing_set(HeapRegionSetBase* containing_set) {
546 assert((containing_set == NULL && _containing_set != NULL) ||
547 (containing_set != NULL && _containing_set == NULL),
548 err_msg("containing_set: "PTR_FORMAT" "
549 "_containing_set: "PTR_FORMAT,
550 p2i(containing_set), p2i(_containing_set)));
552 _containing_set = containing_set;
553 }
555 HeapRegionSetBase* containing_set() { return _containing_set; }
556 #else // ASSERT
557 void set_containing_set(HeapRegionSetBase* containing_set) { }
559 // containing_set() is only used in asserts so there's no reason
560 // to provide a dummy version of it.
561 #endif // ASSERT
563 HeapRegion* get_next_young_region() { return _next_young_region; }
564 void set_next_young_region(HeapRegion* hr) {
565 _next_young_region = hr;
566 }
568 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
569 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
570 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
571 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
573 HeapWord* orig_end() { return _orig_end; }
575 // Reset HR stuff to default values.
576 void hr_clear(bool par, bool clear_space, bool locked = false);
577 void par_clear();
579 // Get the start of the unmarked area in this region.
580 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
581 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
583 // Note the start or end of marking. This tells the heap region
584 // that the collector is about to start or has finished (concurrently)
585 // marking the heap.
587 // Notify the region that concurrent marking is starting. Initialize
588 // all fields related to the next marking info.
589 inline void note_start_of_marking();
591 // Notify the region that concurrent marking has finished. Copy the
592 // (now finalized) next marking info fields into the prev marking
593 // info fields.
594 inline void note_end_of_marking();
596 // Notify the region that it will be used as to-space during a GC
597 // and we are about to start copying objects into it.
598 inline void note_start_of_copying(bool during_initial_mark);
600 // Notify the region that it ceases being to-space during a GC and
601 // we will not copy objects into it any more.
602 inline void note_end_of_copying(bool during_initial_mark);
604 // Notify the region that we are about to start processing
605 // self-forwarded objects during evac failure handling.
606 void note_self_forwarding_removal_start(bool during_initial_mark,
607 bool during_conc_mark);
609 // Notify the region that we have finished processing self-forwarded
610 // objects during evac failure handling.
611 void note_self_forwarding_removal_end(bool during_initial_mark,
612 bool during_conc_mark,
613 size_t marked_bytes);
615 // Returns "false" iff no object in the region was allocated when the
616 // last mark phase ended.
617 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
619 void reset_during_compaction() {
620 assert(isHumongous() && startsHumongous(),
621 "should only be called for starts humongous regions");
623 zero_marked_bytes();
624 init_top_at_mark_start();
625 }
627 void calc_gc_efficiency(void);
628 double gc_efficiency() { return _gc_efficiency;}
630 bool is_young() const { return _young_type != NotYoung; }
631 bool is_survivor() const { return _young_type == Survivor; }
633 int young_index_in_cset() const { return _young_index_in_cset; }
634 void set_young_index_in_cset(int index) {
635 assert( (index == -1) || is_young(), "pre-condition" );
636 _young_index_in_cset = index;
637 }
639 int age_in_surv_rate_group() {
640 assert( _surv_rate_group != NULL, "pre-condition" );
641 assert( _age_index > -1, "pre-condition" );
642 return _surv_rate_group->age_in_group(_age_index);
643 }
645 void record_surv_words_in_group(size_t words_survived) {
646 assert( _surv_rate_group != NULL, "pre-condition" );
647 assert( _age_index > -1, "pre-condition" );
648 int age_in_group = age_in_surv_rate_group();
649 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
650 }
652 int age_in_surv_rate_group_cond() {
653 if (_surv_rate_group != NULL)
654 return age_in_surv_rate_group();
655 else
656 return -1;
657 }
659 SurvRateGroup* surv_rate_group() {
660 return _surv_rate_group;
661 }
663 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
664 assert( surv_rate_group != NULL, "pre-condition" );
665 assert( _surv_rate_group == NULL, "pre-condition" );
666 assert( is_young(), "pre-condition" );
668 _surv_rate_group = surv_rate_group;
669 _age_index = surv_rate_group->next_age_index();
670 }
672 void uninstall_surv_rate_group() {
673 if (_surv_rate_group != NULL) {
674 assert( _age_index > -1, "pre-condition" );
675 assert( is_young(), "pre-condition" );
677 _surv_rate_group = NULL;
678 _age_index = -1;
679 } else {
680 assert( _age_index == -1, "pre-condition" );
681 }
682 }
684 void set_young() { set_young_type(Young); }
686 void set_survivor() { set_young_type(Survivor); }
688 void set_not_young() { set_young_type(NotYoung); }
690 // Determine if an object has been allocated since the last
691 // mark performed by the collector. This returns true iff the object
692 // is within the unmarked area of the region.
693 bool obj_allocated_since_prev_marking(oop obj) const {
694 return (HeapWord *) obj >= prev_top_at_mark_start();
695 }
696 bool obj_allocated_since_next_marking(oop obj) const {
697 return (HeapWord *) obj >= next_top_at_mark_start();
698 }
700 // For parallel heapRegion traversal.
701 bool claimHeapRegion(int claimValue);
702 jint claim_value() { return _claimed; }
703 // Use this carefully: only when you're sure no one is claiming...
704 void set_claim_value(int claimValue) { _claimed = claimValue; }
706 // Returns the "evacuation_failed" property of the region.
707 bool evacuation_failed() { return _evacuation_failed; }
709 // Sets the "evacuation_failed" property of the region.
710 void set_evacuation_failed(bool b) {
711 _evacuation_failed = b;
713 if (b) {
714 _next_marked_bytes = 0;
715 }
716 }
718 // Requires that "mr" be entirely within the region.
719 // Apply "cl->do_object" to all objects that intersect with "mr".
720 // If the iteration encounters an unparseable portion of the region,
721 // or if "cl->abort()" is true after a closure application,
722 // terminate the iteration and return the address of the start of the
723 // subregion that isn't done. (The two can be distinguished by querying
724 // "cl->abort()".) Return of "NULL" indicates that the iteration
725 // completed.
726 HeapWord*
727 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
729 // filter_young: if true and the region is a young region then we
730 // skip the iteration.
731 // card_ptr: if not NULL, and we decide that the card is not young
732 // and we iterate over it, we'll clean the card before we start the
733 // iteration.
734 HeapWord*
735 oops_on_card_seq_iterate_careful(MemRegion mr,
736 FilterOutOfRegionClosure* cl,
737 bool filter_young,
738 jbyte* card_ptr);
740 // A version of block start that is guaranteed to find *some* block
741 // boundary at or before "p", but does not object iteration, and may
742 // therefore be used safely when the heap is unparseable.
743 HeapWord* block_start_careful(const void* p) const {
744 return _offsets.block_start_careful(p);
745 }
747 // Requires that "addr" is within the region. Returns the start of the
748 // first ("careful") block that starts at or after "addr", or else the
749 // "end" of the region if there is no such block.
750 HeapWord* next_block_start_careful(HeapWord* addr);
752 size_t recorded_rs_length() const { return _recorded_rs_length; }
753 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
754 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }
756 void set_recorded_rs_length(size_t rs_length) {
757 _recorded_rs_length = rs_length;
758 }
760 void set_predicted_elapsed_time_ms(double ms) {
761 _predicted_elapsed_time_ms = ms;
762 }
764 void set_predicted_bytes_to_copy(size_t bytes) {
765 _predicted_bytes_to_copy = bytes;
766 }
768 virtual CompactibleSpace* next_compaction_space() const;
770 virtual void reset_after_compaction();
772 // Routines for managing a list of code roots (attached to the
773 // this region's RSet) that point into this heap region.
774 void add_strong_code_root(nmethod* nm);
775 void remove_strong_code_root(nmethod* nm);
777 // During a collection, migrate the successfully evacuated
778 // strong code roots that referenced into this region to the
779 // new regions that they now point into. Unsuccessfully
780 // evacuated code roots are not migrated.
781 void migrate_strong_code_roots();
783 // Applies blk->do_code_blob() to each of the entries in
784 // the strong code roots list for this region
785 void strong_code_roots_do(CodeBlobClosure* blk) const;
787 // Verify that the entries on the strong code root list for this
788 // region are live and include at least one pointer into this region.
789 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
791 void print() const;
792 void print_on(outputStream* st) const;
794 // vo == UsePrevMarking -> use "prev" marking information,
795 // vo == UseNextMarking -> use "next" marking information
796 // vo == UseMarkWord -> use the mark word in the object header
797 //
798 // NOTE: Only the "prev" marking information is guaranteed to be
799 // consistent most of the time, so most calls to this should use
800 // vo == UsePrevMarking.
801 // Currently, there is only one case where this is called with
802 // vo == UseNextMarking, which is to verify the "next" marking
803 // information at the end of remark.
804 // Currently there is only one place where this is called with
805 // vo == UseMarkWord, which is to verify the marking during a
806 // full GC.
807 void verify(VerifyOption vo, bool *failures) const;
809 // Override; it uses the "prev" marking information
810 virtual void verify() const;
811 };
813 // HeapRegionClosure is used for iterating over regions.
814 // Terminates the iteration when the "doHeapRegion" method returns "true".
815 class HeapRegionClosure : public StackObj {
816 friend class HeapRegionSeq;
817 friend class G1CollectedHeap;
819 bool _complete;
820 void incomplete() { _complete = false; }
822 public:
823 HeapRegionClosure(): _complete(true) {}
825 // Typically called on each region until it returns true.
826 virtual bool doHeapRegion(HeapRegion* r) = 0;
828 // True after iteration if the closure was applied to all heap regions
829 // and returned "false" in all cases.
830 bool complete() { return _complete; }
831 };
833 #endif // INCLUDE_ALL_GCS
835 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP