1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
27
28 #include "gc_implementation/g1/g1BlockOffsetTable.inline.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"
36
37 #if INCLUDE_ALL_GCS
38
39 // A HeapRegion is the smallest piece of a G1CollectedHeap that
40 // can be collected independently.
41
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.
48
49 class CompactibleSpace;
50 class ContiguousSpace;
51 class HeapRegionRemSet;
52 class HeapRegionRemSetIterator;
53 class HeapRegion;
54 class HeapRegionSetBase;
55 class nmethod;
56
57 #define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"
58 #define HR_FORMAT_PARAMS(_hr_) \
59 (_hr_)->hrs_index(), \
60 (_hr_)->is_survivor() ? "S" : (_hr_)->is_young() ? "E" : \
61 (_hr_)->startsHumongous() ? "HS" : \
62 (_hr_)->continuesHumongous() ? "HC" : \
63 !(_hr_)->is_empty() ? "O" : "F", \
64 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
65
66 // sentinel value for hrs_index
67 #define G1_NULL_HRS_INDEX ((uint) -1)
68
69 // A dirty card to oop closure for heap regions. It
70 // knows how to get the G1 heap and how to use the bitmap
71 // in the concurrent marker used by G1 to filter remembered
72 // sets.
73
74 class HeapRegionDCTOC : public DirtyCardToOopClosure {
75 public:
76 // Specification of possible DirtyCardToOopClosure filtering.
77 enum FilterKind {
78 NoFilterKind,
79 IntoCSFilterKind,
80 OutOfRegionFilterKind
81 };
82
83 protected:
84 HeapRegion* _hr;
85 FilterKind _fk;
86 G1CollectedHeap* _g1;
87
88 // Walk the given memory region from bottom to (actual) top
89 // looking for objects and applying the oop closure (_cl) to
90 // them. The base implementation of this treats the area as
91 // blocks, where a block may or may not be an object. Sub-
92 // classes should override this to provide more accurate
93 // or possibly more efficient walking.
94 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
95
96 public:
97 HeapRegionDCTOC(G1CollectedHeap* g1,
98 HeapRegion* hr, ExtendedOopClosure* cl,
99 CardTableModRefBS::PrecisionStyle precision,
100 FilterKind fk);
101 };
102
103 // The complicating factor is that BlockOffsetTable diverged
104 // significantly, and we need functionality that is only in the G1 version.
105 // So I copied that code, which led to an alternate G1 version of
106 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
107 // be reconciled, then G1OffsetTableContigSpace could go away.
108
109 // The idea behind time stamps is the following. Doing a save_marks on
110 // all regions at every GC pause is time consuming (if I remember
111 // well, 10ms or so). So, we would like to do that only for regions
112 // that are GC alloc regions. To achieve this, we use time
113 // stamps. For every evacuation pause, G1CollectedHeap generates a
114 // unique time stamp (essentially a counter that gets
115 // incremented). Every time we want to call save_marks on a region,
116 // we set the saved_mark_word to top and also copy the current GC
117 // time stamp to the time stamp field of the space. Reading the
118 // saved_mark_word involves checking the time stamp of the
119 // region. If it is the same as the current GC time stamp, then we
120 // can safely read the saved_mark_word field, as it is valid. If the
121 // time stamp of the region is not the same as the current GC time
122 // stamp, then we instead read top, as the saved_mark_word field is
123 // invalid. Time stamps (on the regions and also on the
124 // G1CollectedHeap) are reset at every cleanup (we iterate over
125 // the regions anyway) and at the end of a Full GC. The current scheme
126 // that uses sequential unsigned ints will fail only if we have 4b
127 // evacuation pauses between two cleanups, which is _highly_ unlikely.
128
129 class G1OffsetTableContigSpace: public ContiguousSpace {
130 friend class VMStructs;
131 protected:
132 G1BlockOffsetArrayContigSpace _offsets;
133 Mutex _par_alloc_lock;
134 volatile unsigned _gc_time_stamp;
135 // When we need to retire an allocation region, while other threads
136 // are also concurrently trying to allocate into it, we typically
137 // allocate a dummy object at the end of the region to ensure that
138 // no more allocations can take place in it. However, sometimes we
139 // want to know where the end of the last "real" object we allocated
140 // into the region was and this is what this keeps track.
141 HeapWord* _pre_dummy_top;
142
143 public:
144 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
145 MemRegion mr);
146
147 void set_bottom(HeapWord* value);
148 void set_end(HeapWord* value);
149
150 virtual HeapWord* saved_mark_word() const;
151 void record_top_and_timestamp();
152 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
153 unsigned get_gc_time_stamp() { return _gc_time_stamp; }
154
155 // See the comment above in the declaration of _pre_dummy_top for an
156 // explanation of what it is.
157 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
158 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
159 _pre_dummy_top = pre_dummy_top;
160 }
161 HeapWord* pre_dummy_top() {
162 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
163 }
164 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
165
166 virtual void clear(bool mangle_space);
167
168 HeapWord* block_start(const void* p);
169 HeapWord* block_start_const(const void* p) const;
170
171 // Add offset table update.
172 virtual HeapWord* allocate(size_t word_size);
173 HeapWord* par_allocate(size_t word_size);
174
175 // MarkSweep support phase3
176 virtual HeapWord* initialize_threshold();
177 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
178
179 virtual void print() const;
180
181 void reset_bot() {
182 _offsets.zero_bottom_entry();
183 _offsets.initialize_threshold();
184 }
185
186 void update_bot_for_object(HeapWord* start, size_t word_size) {
187 _offsets.alloc_block(start, word_size);
188 }
189
190 void print_bot_on(outputStream* out) {
191 _offsets.print_on(out);
192 }
193 };
194
195 class HeapRegion: public G1OffsetTableContigSpace {
196 friend class VMStructs;
197 private:
198
199 enum HumongousType {
200 NotHumongous = 0,
201 StartsHumongous,
202 ContinuesHumongous
203 };
204
205 // The remembered set for this region.
206 // (Might want to make this "inline" later, to avoid some alloc failure
207 // issues.)
208 HeapRegionRemSet* _rem_set;
209
210 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
211
212 protected:
213 // The index of this region in the heap region sequence.
214 uint _hrs_index;
215
216 HumongousType _humongous_type;
217 // For a humongous region, region in which it starts.
218 HeapRegion* _humongous_start_region;
219 // For the start region of a humongous sequence, it's original end().
220 HeapWord* _orig_end;
221
222 // True iff the region is in current collection_set.
223 bool _in_collection_set;
224
225 // True iff an attempt to evacuate an object in the region failed.
226 bool _evacuation_failed;
227
228 // A heap region may be a member one of a number of special subsets, each
229 // represented as linked lists through the field below. Currently, these
230 // sets include:
231 // The collection set.
232 // The set of allocation regions used in a collection pause.
233 // Spaces that may contain gray objects.
234 HeapRegion* _next_in_special_set;
235
236 // next region in the young "generation" region set
237 HeapRegion* _next_young_region;
238
239 // Next region whose cards need cleaning
240 HeapRegion* _next_dirty_cards_region;
241
242 // Fields used by the HeapRegionSetBase class and subclasses.
243 HeapRegion* _next;
244 HeapRegion* _prev;
245 #ifdef ASSERT
246 HeapRegionSetBase* _containing_set;
247 #endif // ASSERT
248 bool _pending_removal;
249
250 // For parallel heapRegion traversal.
251 jint _claimed;
252
253 // We use concurrent marking to determine the amount of live data
254 // in each heap region.
255 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
256 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
257
258 // The calculated GC efficiency of the region.
259 double _gc_efficiency;
260
261 enum YoungType {
262 NotYoung, // a region is not young
263 Young, // a region is young
264 Survivor // a region is young and it contains survivors
265 };
266
267 volatile YoungType _young_type;
268 int _young_index_in_cset;
269 SurvRateGroup* _surv_rate_group;
270 int _age_index;
271
272 // The start of the unmarked area. The unmarked area extends from this
273 // word until the top and/or end of the region, and is the part
274 // of the region for which no marking was done, i.e. objects may
275 // have been allocated in this part since the last mark phase.
276 // "prev" is the top at the start of the last completed marking.
277 // "next" is the top at the start of the in-progress marking (if any.)
278 HeapWord* _prev_top_at_mark_start;
279 HeapWord* _next_top_at_mark_start;
280 // If a collection pause is in progress, this is the top at the start
281 // of that pause.
282
283 void init_top_at_mark_start() {
284 assert(_prev_marked_bytes == 0 &&
285 _next_marked_bytes == 0,
286 "Must be called after zero_marked_bytes.");
287 HeapWord* bot = bottom();
288 _prev_top_at_mark_start = bot;
289 _next_top_at_mark_start = bot;
290 }
291
292 void set_young_type(YoungType new_type) {
293 //assert(_young_type != new_type, "setting the same type" );
294 // TODO: add more assertions here
295 _young_type = new_type;
296 }
297
298 // Cached attributes used in the collection set policy information
299
300 // The RSet length that was added to the total value
301 // for the collection set.
302 size_t _recorded_rs_length;
303
304 // The predicted elapsed time that was added to total value
305 // for the collection set.
306 double _predicted_elapsed_time_ms;
307
308 // The predicted number of bytes to copy that was added to
309 // the total value for the collection set.
310 size_t _predicted_bytes_to_copy;
311
312 public:
313 HeapRegion(uint hrs_index,
314 G1BlockOffsetSharedArray* sharedOffsetArray,
315 MemRegion mr);
316
317 static int LogOfHRGrainBytes;
318 static int LogOfHRGrainWords;
319
320 static size_t GrainBytes;
321 static size_t GrainWords;
322 static size_t CardsPerRegion;
323
324 static size_t align_up_to_region_byte_size(size_t sz) {
325 return (sz + (size_t) GrainBytes - 1) &
326 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
327 }
328
329 static size_t max_region_size();
330
331 // It sets up the heap region size (GrainBytes / GrainWords), as
332 // well as other related fields that are based on the heap region
333 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
334 // CardsPerRegion). All those fields are considered constant
335 // throughout the JVM's execution, therefore they should only be set
336 // up once during initialization time.
337 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
338
339 enum ClaimValues {
340 InitialClaimValue = 0,
341 FinalCountClaimValue = 1,
342 NoteEndClaimValue = 2,
343 ScrubRemSetClaimValue = 3,
344 ParVerifyClaimValue = 4,
345 RebuildRSClaimValue = 5,
346 ParEvacFailureClaimValue = 6,
347 AggregateCountClaimValue = 7,
348 VerifyCountClaimValue = 8,
349 ParMarkRootClaimValue = 9
350 };
351
352 inline HeapWord* par_allocate_no_bot_updates(size_t word_size) {
353 assert(is_young(), "we can only skip BOT updates on young regions");
354 return ContiguousSpace::par_allocate(word_size);
355 }
356 inline HeapWord* allocate_no_bot_updates(size_t word_size) {
357 assert(is_young(), "we can only skip BOT updates on young regions");
358 return ContiguousSpace::allocate(word_size);
359 }
360
361 // If this region is a member of a HeapRegionSeq, the index in that
362 // sequence, otherwise -1.
363 uint hrs_index() const { return _hrs_index; }
364
365 // The number of bytes marked live in the region in the last marking phase.
366 size_t marked_bytes() { return _prev_marked_bytes; }
367 size_t live_bytes() {
368 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
369 }
370
371 // The number of bytes counted in the next marking.
372 size_t next_marked_bytes() { return _next_marked_bytes; }
373 // The number of bytes live wrt the next marking.
374 size_t next_live_bytes() {
375 return
376 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
377 }
378
379 // A lower bound on the amount of garbage bytes in the region.
380 size_t garbage_bytes() {
381 size_t used_at_mark_start_bytes =
382 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
383 assert(used_at_mark_start_bytes >= marked_bytes(),
384 "Can't mark more than we have.");
385 return used_at_mark_start_bytes - marked_bytes();
386 }
387
388 // Return the amount of bytes we'll reclaim if we collect this
389 // region. This includes not only the known garbage bytes in the
390 // region but also any unallocated space in it, i.e., [top, end),
391 // since it will also be reclaimed if we collect the region.
392 size_t reclaimable_bytes() {
393 size_t known_live_bytes = live_bytes();
394 assert(known_live_bytes <= capacity(), "sanity");
395 return capacity() - known_live_bytes;
396 }
397
398 // An upper bound on the number of live bytes in the region.
399 size_t max_live_bytes() { return used() - garbage_bytes(); }
400
401 void add_to_marked_bytes(size_t incr_bytes) {
402 _next_marked_bytes = _next_marked_bytes + incr_bytes;
403 assert(_next_marked_bytes <= used(), "invariant" );
404 }
405
406 void zero_marked_bytes() {
407 _prev_marked_bytes = _next_marked_bytes = 0;
408 }
409
410 bool isHumongous() const { return _humongous_type != NotHumongous; }
411 bool startsHumongous() const { return _humongous_type == StartsHumongous; }
412 bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; }
413 // For a humongous region, region in which it starts.
414 HeapRegion* humongous_start_region() const {
415 return _humongous_start_region;
416 }
417
418 // Return the number of distinct regions that are covered by this region:
419 // 1 if the region is not humongous, >= 1 if the region is humongous.
420 uint region_num() const {
421 if (!isHumongous()) {
422 return 1U;
423 } else {
424 assert(startsHumongous(), "doesn't make sense on HC regions");
425 assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
426 return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
427 }
428 }
429
430 // Return the index + 1 of the last HC regions that's associated
431 // with this HS region.
432 uint last_hc_index() const {
433 assert(startsHumongous(), "don't call this otherwise");
434 return hrs_index() + region_num();
435 }
436
437 // Same as Space::is_in_reserved, but will use the original size of the region.
438 // The original size is different only for start humongous regions. They get
439 // their _end set up to be the end of the last continues region of the
440 // corresponding humongous object.
441 bool is_in_reserved_raw(const void* p) const {
442 return _bottom <= p && p < _orig_end;
443 }
444
445 // Makes the current region be a "starts humongous" region, i.e.,
446 // the first region in a series of one or more contiguous regions
447 // that will contain a single "humongous" object. The two parameters
448 // are as follows:
449 //
450 // new_top : The new value of the top field of this region which
451 // points to the end of the humongous object that's being
452 // allocated. If there is more than one region in the series, top
453 // will lie beyond this region's original end field and on the last
454 // region in the series.
455 //
456 // new_end : The new value of the end field of this region which
457 // points to the end of the last region in the series. If there is
458 // one region in the series (namely: this one) end will be the same
459 // as the original end of this region.
460 //
461 // Updating top and end as described above makes this region look as
462 // if it spans the entire space taken up by all the regions in the
463 // series and an single allocation moved its top to new_top. This
464 // ensures that the space (capacity / allocated) taken up by all
465 // humongous regions can be calculated by just looking at the
466 // "starts humongous" regions and by ignoring the "continues
467 // humongous" regions.
468 void set_startsHumongous(HeapWord* new_top, HeapWord* new_end);
469
470 // Makes the current region be a "continues humongous'
471 // region. first_hr is the "start humongous" region of the series
472 // which this region will be part of.
473 void set_continuesHumongous(HeapRegion* first_hr);
474
475 // Unsets the humongous-related fields on the region.
476 void set_notHumongous();
477
478 // If the region has a remembered set, return a pointer to it.
479 HeapRegionRemSet* rem_set() const {
480 return _rem_set;
481 }
482
483 // True iff the region is in current collection_set.
484 bool in_collection_set() const {
485 return _in_collection_set;
486 }
487 void set_in_collection_set(bool b) {
488 _in_collection_set = b;
489 }
490 HeapRegion* next_in_collection_set() {
491 assert(in_collection_set(), "should only invoke on member of CS.");
492 assert(_next_in_special_set == NULL ||
493 _next_in_special_set->in_collection_set(),
494 "Malformed CS.");
495 return _next_in_special_set;
496 }
497 void set_next_in_collection_set(HeapRegion* r) {
498 assert(in_collection_set(), "should only invoke on member of CS.");
499 assert(r == NULL || r->in_collection_set(), "Malformed CS.");
500 _next_in_special_set = r;
501 }
502
503 // Methods used by the HeapRegionSetBase class and subclasses.
504
505 // Getter and setter for the next and prev fields used to link regions into
506 // linked lists.
507 HeapRegion* next() { return _next; }
508 HeapRegion* prev() { return _prev; }
509
510 void set_next(HeapRegion* next) { _next = next; }
511 void set_prev(HeapRegion* prev) { _prev = prev; }
512
513 // Every region added to a set is tagged with a reference to that
514 // set. This is used for doing consistency checking to make sure that
515 // the contents of a set are as they should be and it's only
516 // available in non-product builds.
517 #ifdef ASSERT
518 void set_containing_set(HeapRegionSetBase* containing_set) {
519 assert((containing_set == NULL && _containing_set != NULL) ||
520 (containing_set != NULL && _containing_set == NULL),
521 err_msg("containing_set: "PTR_FORMAT" "
522 "_containing_set: "PTR_FORMAT,
523 p2i(containing_set), p2i(_containing_set)));
524
525 _containing_set = containing_set;
526 }
527
528 HeapRegionSetBase* containing_set() { return _containing_set; }
529 #else // ASSERT
530 void set_containing_set(HeapRegionSetBase* containing_set) { }
531
532 // containing_set() is only used in asserts so there's no reason
533 // to provide a dummy version of it.
534 #endif // ASSERT
535
536 // If we want to remove regions from a list in bulk we can simply tag
537 // them with the pending_removal tag and call the
538 // remove_all_pending() method on the list.
539
540 bool pending_removal() { return _pending_removal; }
541
542 void set_pending_removal(bool pending_removal) {
543 if (pending_removal) {
544 assert(!_pending_removal && containing_set() != NULL,
545 "can only set pending removal to true if it's false and "
546 "the region belongs to a region set");
547 } else {
548 assert( _pending_removal && containing_set() == NULL,
549 "can only set pending removal to false if it's true and "
550 "the region does not belong to a region set");
551 }
552
553 _pending_removal = pending_removal;
554 }
555
556 HeapRegion* get_next_young_region() { return _next_young_region; }
557 void set_next_young_region(HeapRegion* hr) {
558 _next_young_region = hr;
559 }
560
561 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
562 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
563 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
564 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
565
566 HeapWord* orig_end() { return _orig_end; }
567
568 // Reset HR stuff to default values.
569 void hr_clear(bool par, bool clear_space, bool locked = false);
570 void par_clear();
571
572 // Get the start of the unmarked area in this region.
573 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
574 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
575
576 // Note the start or end of marking. This tells the heap region
577 // that the collector is about to start or has finished (concurrently)
578 // marking the heap.
579
580 // Notify the region that concurrent marking is starting. Initialize
581 // all fields related to the next marking info.
582 inline void note_start_of_marking();
583
584 // Notify the region that concurrent marking has finished. Copy the
585 // (now finalized) next marking info fields into the prev marking
586 // info fields.
587 inline void note_end_of_marking();
588
589 // Notify the region that it will be used as to-space during a GC
590 // and we are about to start copying objects into it.
591 inline void note_start_of_copying(bool during_initial_mark);
592
593 // Notify the region that it ceases being to-space during a GC and
594 // we will not copy objects into it any more.
595 inline void note_end_of_copying(bool during_initial_mark);
596
597 // Notify the region that we are about to start processing
598 // self-forwarded objects during evac failure handling.
599 void note_self_forwarding_removal_start(bool during_initial_mark,
600 bool during_conc_mark);
601
602 // Notify the region that we have finished processing self-forwarded
603 // objects during evac failure handling.
604 void note_self_forwarding_removal_end(bool during_initial_mark,
605 bool during_conc_mark,
606 size_t marked_bytes);
607
608 // Returns "false" iff no object in the region was allocated when the
609 // last mark phase ended.
610 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
611
612 void reset_during_compaction() {
613 assert(isHumongous() && startsHumongous(),
614 "should only be called for starts humongous regions");
615
616 zero_marked_bytes();
617 init_top_at_mark_start();
618 }
619
620 void calc_gc_efficiency(void);
621 double gc_efficiency() { return _gc_efficiency;}
622
623 bool is_young() const { return _young_type != NotYoung; }
624 bool is_survivor() const { return _young_type == Survivor; }
625
626 int young_index_in_cset() const { return _young_index_in_cset; }
627 void set_young_index_in_cset(int index) {
628 assert( (index == -1) || is_young(), "pre-condition" );
629 _young_index_in_cset = index;
630 }
631
632 int age_in_surv_rate_group() {
633 assert( _surv_rate_group != NULL, "pre-condition" );
634 assert( _age_index > -1, "pre-condition" );
635 return _surv_rate_group->age_in_group(_age_index);
636 }
637
638 void record_surv_words_in_group(size_t words_survived) {
639 assert( _surv_rate_group != NULL, "pre-condition" );
640 assert( _age_index > -1, "pre-condition" );
641 int age_in_group = age_in_surv_rate_group();
642 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
643 }
644
645 int age_in_surv_rate_group_cond() {
646 if (_surv_rate_group != NULL)
647 return age_in_surv_rate_group();
648 else
649 return -1;
650 }
651
652 SurvRateGroup* surv_rate_group() {
653 return _surv_rate_group;
654 }
655
656 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
657 assert( surv_rate_group != NULL, "pre-condition" );
658 assert( _surv_rate_group == NULL, "pre-condition" );
659 assert( is_young(), "pre-condition" );
660
661 _surv_rate_group = surv_rate_group;
662 _age_index = surv_rate_group->next_age_index();
663 }
664
665 void uninstall_surv_rate_group() {
666 if (_surv_rate_group != NULL) {
667 assert( _age_index > -1, "pre-condition" );
668 assert( is_young(), "pre-condition" );
669
670 _surv_rate_group = NULL;
671 _age_index = -1;
672 } else {
673 assert( _age_index == -1, "pre-condition" );
674 }
675 }
676
677 void set_young() { set_young_type(Young); }
678
679 void set_survivor() { set_young_type(Survivor); }
680
681 void set_not_young() { set_young_type(NotYoung); }
682
683 // Determine if an object has been allocated since the last
684 // mark performed by the collector. This returns true iff the object
685 // is within the unmarked area of the region.
686 bool obj_allocated_since_prev_marking(oop obj) const {
687 return (HeapWord *) obj >= prev_top_at_mark_start();
688 }
689 bool obj_allocated_since_next_marking(oop obj) const {
690 return (HeapWord *) obj >= next_top_at_mark_start();
691 }
692
693 // For parallel heapRegion traversal.
694 bool claimHeapRegion(int claimValue);
695 jint claim_value() { return _claimed; }
696 // Use this carefully: only when you're sure no one is claiming...
697 void set_claim_value(int claimValue) { _claimed = claimValue; }
698
699 // Returns the "evacuation_failed" property of the region.
700 bool evacuation_failed() { return _evacuation_failed; }
701
702 // Sets the "evacuation_failed" property of the region.
703 void set_evacuation_failed(bool b) {
704 _evacuation_failed = b;
705
706 if (b) {
707 _next_marked_bytes = 0;
708 }
709 }
710
711 // Requires that "mr" be entirely within the region.
712 // Apply "cl->do_object" to all objects that intersect with "mr".
713 // If the iteration encounters an unparseable portion of the region,
714 // or if "cl->abort()" is true after a closure application,
715 // terminate the iteration and return the address of the start of the
716 // subregion that isn't done. (The two can be distinguished by querying
717 // "cl->abort()".) Return of "NULL" indicates that the iteration
718 // completed.
719 HeapWord*
720 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
721
722 // filter_young: if true and the region is a young region then we
723 // skip the iteration.
724 // card_ptr: if not NULL, and we decide that the card is not young
725 // and we iterate over it, we'll clean the card before we start the
726 // iteration.
727 HeapWord*
728 oops_on_card_seq_iterate_careful(MemRegion mr,
729 FilterOutOfRegionClosure* cl,
730 bool filter_young,
731 jbyte* card_ptr);
732
733 // A version of block start that is guaranteed to find *some* block
734 // boundary at or before "p", but does not object iteration, and may
735 // therefore be used safely when the heap is unparseable.
736 HeapWord* block_start_careful(const void* p) const {
737 return _offsets.block_start_careful(p);
738 }
739
740 // Requires that "addr" is within the region. Returns the start of the
741 // first ("careful") block that starts at or after "addr", or else the
742 // "end" of the region if there is no such block.
743 HeapWord* next_block_start_careful(HeapWord* addr);
744
745 size_t recorded_rs_length() const { return _recorded_rs_length; }
746 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
747 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }
748
749 void set_recorded_rs_length(size_t rs_length) {
750 _recorded_rs_length = rs_length;
751 }
752
753 void set_predicted_elapsed_time_ms(double ms) {
754 _predicted_elapsed_time_ms = ms;
755 }
756
757 void set_predicted_bytes_to_copy(size_t bytes) {
758 _predicted_bytes_to_copy = bytes;
759 }
760
761 virtual CompactibleSpace* next_compaction_space() const;
762
763 virtual void reset_after_compaction();
764
765 // Routines for managing a list of code roots (attached to the
766 // this region's RSet) that point into this heap region.
767 void add_strong_code_root(nmethod* nm);
768 void remove_strong_code_root(nmethod* nm);
769
770 // During a collection, migrate the successfully evacuated
771 // strong code roots that referenced into this region to the
772 // new regions that they now point into. Unsuccessfully
773 // evacuated code roots are not migrated.
774 void migrate_strong_code_roots();
775
776 // Applies blk->do_code_blob() to each of the entries in
777 // the strong code roots list for this region
778 void strong_code_roots_do(CodeBlobClosure* blk) const;
779
780 // Verify that the entries on the strong code root list for this
781 // region are live and include at least one pointer into this region.
782 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
783
784 void print() const;
785 void print_on(outputStream* st) const;
786
787 // vo == UsePrevMarking -> use "prev" marking information,
788 // vo == UseNextMarking -> use "next" marking information
789 // vo == UseMarkWord -> use the mark word in the object header
790 //
791 // NOTE: Only the "prev" marking information is guaranteed to be
792 // consistent most of the time, so most calls to this should use
793 // vo == UsePrevMarking.
794 // Currently, there is only one case where this is called with
795 // vo == UseNextMarking, which is to verify the "next" marking
796 // information at the end of remark.
797 // Currently there is only one place where this is called with
798 // vo == UseMarkWord, which is to verify the marking during a
799 // full GC.
800 void verify(VerifyOption vo, bool *failures) const;
801
802 // Override; it uses the "prev" marking information
803 virtual void verify() const;
804 };
805
806 // HeapRegionClosure is used for iterating over regions.
807 // Terminates the iteration when the "doHeapRegion" method returns "true".
808 class HeapRegionClosure : public StackObj {
809 friend class HeapRegionSeq;
810 friend class G1CollectedHeap;
811
812 bool _complete;
813 void incomplete() { _complete = false; }
814
815 public:
816 HeapRegionClosure(): _complete(true) {}
817
818 // Typically called on each region until it returns true.
819 virtual bool doHeapRegion(HeapRegion* r) = 0;
820
821 // True after iteration if the closure was applied to all heap regions
822 // and returned "false" in all cases.
823 bool complete() { return _complete; }
824 };
825
826 #endif // INCLUDE_ALL_GCS
827
828 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP