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.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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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 ContiguousSpaceDCTOC {
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 void walk_mem_region_with_cl(MemRegion mr,
89 HeapWord* bottom, HeapWord* top,
90 ExtendedOopClosure* cl);
91
92 // We don't specialize this for FilteringClosure; filtering is handled by
93 // the "FilterKind" mechanism. But we provide this to avoid a compiler
94 // warning.
95 void walk_mem_region_with_cl(MemRegion mr,
96 HeapWord* bottom, HeapWord* top,
97 FilteringClosure* cl) {
98 HeapRegionDCTOC::walk_mem_region_with_cl(mr, bottom, top,
99 (ExtendedOopClosure*)cl);
100 }
101
102 // Get the actual top of the area on which the closure will
103 // operate, given where the top is assumed to be (the end of the
104 // memory region passed to do_MemRegion) and where the object
105 // at the top is assumed to start. For example, an object may
106 // start at the top but actually extend past the assumed top,
107 // in which case the top becomes the end of the object.
108 HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj) {
109 return ContiguousSpaceDCTOC::get_actual_top(top, top_obj);
110 }
111
112 // Walk the given memory region from bottom to (actual) top
113 // looking for objects and applying the oop closure (_cl) to
114 // them. The base implementation of this treats the area as
115 // blocks, where a block may or may not be an object. Sub-
116 // classes should override this to provide more accurate
117 // or possibly more efficient walking.
118 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top) {
119 Filtering_DCTOC::walk_mem_region(mr, bottom, top);
120 }
121
122 public:
123 HeapRegionDCTOC(G1CollectedHeap* g1,
124 HeapRegion* hr, ExtendedOopClosure* cl,
125 CardTableModRefBS::PrecisionStyle precision,
126 FilterKind fk);
127 };
128
129 // The complicating factor is that BlockOffsetTable diverged
130 // significantly, and we need functionality that is only in the G1 version.
131 // So I copied that code, which led to an alternate G1 version of
132 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
133 // be reconciled, then G1OffsetTableContigSpace could go away.
134
135 // The idea behind time stamps is the following. Doing a save_marks on
136 // all regions at every GC pause is time consuming (if I remember
137 // well, 10ms or so). So, we would like to do that only for regions
138 // that are GC alloc regions. To achieve this, we use time
139 // stamps. For every evacuation pause, G1CollectedHeap generates a
140 // unique time stamp (essentially a counter that gets
141 // incremented). Every time we want to call save_marks on a region,
142 // we set the saved_mark_word to top and also copy the current GC
143 // time stamp to the time stamp field of the space. Reading the
144 // saved_mark_word involves checking the time stamp of the
145 // region. If it is the same as the current GC time stamp, then we
146 // can safely read the saved_mark_word field, as it is valid. If the
147 // time stamp of the region is not the same as the current GC time
148 // stamp, then we instead read top, as the saved_mark_word field is
149 // invalid. Time stamps (on the regions and also on the
150 // G1CollectedHeap) are reset at every cleanup (we iterate over
151 // the regions anyway) and at the end of a Full GC. The current scheme
152 // that uses sequential unsigned ints will fail only if we have 4b
153 // evacuation pauses between two cleanups, which is _highly_ unlikely.
154
155 class G1OffsetTableContigSpace: public ContiguousSpace {
156 friend class VMStructs;
157 protected:
158 G1BlockOffsetArrayContigSpace _offsets;
159 Mutex _par_alloc_lock;
160 volatile unsigned _gc_time_stamp;
161 // When we need to retire an allocation region, while other threads
162 // are also concurrently trying to allocate into it, we typically
163 // allocate a dummy object at the end of the region to ensure that
164 // no more allocations can take place in it. However, sometimes we
165 // want to know where the end of the last "real" object we allocated
166 // into the region was and this is what this keeps track.
167 HeapWord* _pre_dummy_top;
168
169 public:
170 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
171 MemRegion mr);
172
173 void set_bottom(HeapWord* value);
174 void set_end(HeapWord* value);
175
176 virtual HeapWord* saved_mark_word() const;
177 virtual void set_saved_mark();
178 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
179 unsigned get_gc_time_stamp() { return _gc_time_stamp; }
180
181 // See the comment above in the declaration of _pre_dummy_top for an
182 // explanation of what it is.
183 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
184 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
185 _pre_dummy_top = pre_dummy_top;
186 }
187 HeapWord* pre_dummy_top() {
188 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
189 }
190 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
191
192 virtual void clear(bool mangle_space);
193
194 HeapWord* block_start(const void* p);
195 HeapWord* block_start_const(const void* p) const;
196
197 // Add offset table update.
198 virtual HeapWord* allocate(size_t word_size);
199 HeapWord* par_allocate(size_t word_size);
200
201 // MarkSweep support phase3
202 virtual HeapWord* initialize_threshold();
203 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
204
205 virtual void print() const;
206
207 void reset_bot() {
208 _offsets.zero_bottom_entry();
209 _offsets.initialize_threshold();
210 }
211
212 void update_bot_for_object(HeapWord* start, size_t word_size) {
213 _offsets.alloc_block(start, word_size);
214 }
215
216 void print_bot_on(outputStream* out) {
217 _offsets.print_on(out);
218 }
219 };
220
221 class HeapRegion: public G1OffsetTableContigSpace {
222 friend class VMStructs;
223 private:
224
225 enum HumongousType {
226 NotHumongous = 0,
227 StartsHumongous,
228 ContinuesHumongous
229 };
230
231 // Requires that the region "mr" be dense with objects, and begin and end
232 // with an object.
233 void oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl);
234
235 // The remembered set for this region.
236 // (Might want to make this "inline" later, to avoid some alloc failure
237 // issues.)
238 HeapRegionRemSet* _rem_set;
239
240 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
241
242 protected:
243 // The index of this region in the heap region sequence.
244 uint _hrs_index;
245
246 HumongousType _humongous_type;
247 // For a humongous region, region in which it starts.
248 HeapRegion* _humongous_start_region;
249 // For the start region of a humongous sequence, it's original end().
250 HeapWord* _orig_end;
251
252 // True iff the region is in current collection_set.
253 bool _in_collection_set;
254
255 // True iff an attempt to evacuate an object in the region failed.
256 bool _evacuation_failed;
257
258 // A heap region may be a member one of a number of special subsets, each
259 // represented as linked lists through the field below. Currently, these
260 // sets include:
261 // The collection set.
262 // The set of allocation regions used in a collection pause.
263 // Spaces that may contain gray objects.
264 HeapRegion* _next_in_special_set;
265
266 // next region in the young "generation" region set
267 HeapRegion* _next_young_region;
268
269 // Next region whose cards need cleaning
270 HeapRegion* _next_dirty_cards_region;
271
272 // Fields used by the HeapRegionSetBase class and subclasses.
273 HeapRegion* _next;
274 HeapRegion* _prev;
275 #ifdef ASSERT
276 HeapRegionSetBase* _containing_set;
277 #endif // ASSERT
278 bool _pending_removal;
279
280 // For parallel heapRegion traversal.
281 jint _claimed;
282
283 // We use concurrent marking to determine the amount of live data
284 // in each heap region.
285 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
286 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
287
288 // The calculated GC efficiency of the region.
289 double _gc_efficiency;
290
291 enum YoungType {
292 NotYoung, // a region is not young
293 Young, // a region is young
294 Survivor // a region is young and it contains survivors
295 };
296
297 volatile YoungType _young_type;
298 int _young_index_in_cset;
299 SurvRateGroup* _surv_rate_group;
300 int _age_index;
301
302 // The start of the unmarked area. The unmarked area extends from this
303 // word until the top and/or end of the region, and is the part
304 // of the region for which no marking was done, i.e. objects may
305 // have been allocated in this part since the last mark phase.
306 // "prev" is the top at the start of the last completed marking.
307 // "next" is the top at the start of the in-progress marking (if any.)
308 HeapWord* _prev_top_at_mark_start;
309 HeapWord* _next_top_at_mark_start;
310 // If a collection pause is in progress, this is the top at the start
311 // of that pause.
312
313 void init_top_at_mark_start() {
314 assert(_prev_marked_bytes == 0 &&
315 _next_marked_bytes == 0,
316 "Must be called after zero_marked_bytes.");
317 HeapWord* bot = bottom();
318 _prev_top_at_mark_start = bot;
319 _next_top_at_mark_start = bot;
320 }
321
322 void set_young_type(YoungType new_type) {
323 //assert(_young_type != new_type, "setting the same type" );
324 // TODO: add more assertions here
325 _young_type = new_type;
326 }
327
328 // Cached attributes used in the collection set policy information
329
330 // The RSet length that was added to the total value
331 // for the collection set.
332 size_t _recorded_rs_length;
333
334 // The predicted elapsed time that was added to total value
335 // for the collection set.
336 double _predicted_elapsed_time_ms;
337
338 // The predicted number of bytes to copy that was added to
339 // the total value for the collection set.
340 size_t _predicted_bytes_to_copy;
341
342 public:
343 HeapRegion(uint hrs_index,
344 G1BlockOffsetSharedArray* sharedOffsetArray,
345 MemRegion mr);
346
347 static int LogOfHRGrainBytes;
348 static int LogOfHRGrainWords;
349
350 static size_t GrainBytes;
351 static size_t GrainWords;
352 static size_t CardsPerRegion;
353
354 static size_t align_up_to_region_byte_size(size_t sz) {
355 return (sz + (size_t) GrainBytes - 1) &
356 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
357 }
358
359 static size_t max_region_size();
360
361 // It sets up the heap region size (GrainBytes / GrainWords), as
362 // well as other related fields that are based on the heap region
363 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
364 // CardsPerRegion). All those fields are considered constant
365 // throughout the JVM's execution, therefore they should only be set
366 // up once during initialization time.
367 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
368
369 enum ClaimValues {
370 InitialClaimValue = 0,
371 FinalCountClaimValue = 1,
372 NoteEndClaimValue = 2,
373 ScrubRemSetClaimValue = 3,
374 ParVerifyClaimValue = 4,
375 RebuildRSClaimValue = 5,
376 ParEvacFailureClaimValue = 6,
377 AggregateCountClaimValue = 7,
378 VerifyCountClaimValue = 8,
379 ParMarkRootClaimValue = 9
380 };
381
382 inline HeapWord* par_allocate_no_bot_updates(size_t word_size) {
383 assert(is_young(), "we can only skip BOT updates on young regions");
384 return ContiguousSpace::par_allocate(word_size);
385 }
386 inline HeapWord* allocate_no_bot_updates(size_t word_size) {
387 assert(is_young(), "we can only skip BOT updates on young regions");
388 return ContiguousSpace::allocate(word_size);
389 }
390
391 // If this region is a member of a HeapRegionSeq, the index in that
392 // sequence, otherwise -1.
393 uint hrs_index() const { return _hrs_index; }
394
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 }
400
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 }
408
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 }
417
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 }
427
428 // An upper bound on the number of live bytes in the region.
429 size_t max_live_bytes() { return used() - garbage_bytes(); }
430
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 }
435
436 void zero_marked_bytes() {
437 _prev_marked_bytes = _next_marked_bytes = 0;
438 }
439
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 }
447
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 }
459
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 hrs_index() + region_num();
465 }
466
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 }
474
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);
499
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);
504
505 // Unsets the humongous-related fields on the region.
506 void set_notHumongous();
507
508 // If the region has a remembered set, return a pointer to it.
509 HeapRegionRemSet* rem_set() const {
510 return _rem_set;
511 }
512
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 }
532
533 // Methods used by the HeapRegionSetBase class and subclasses.
534
535 // Getter and setter for the next and prev fields used to link regions into
536 // linked lists.
537 HeapRegion* next() { return _next; }
538 HeapRegion* prev() { return _prev; }
539
540 void set_next(HeapRegion* next) { _next = next; }
541 void set_prev(HeapRegion* prev) { _prev = prev; }
542
543 // Every region added to a set is tagged with a reference to that
544 // set. This is used for doing consistency checking to make sure that
545 // the contents of a set are as they should be and it's only
546 // available in non-product builds.
547 #ifdef ASSERT
548 void set_containing_set(HeapRegionSetBase* containing_set) {
549 assert((containing_set == NULL && _containing_set != NULL) ||
550 (containing_set != NULL && _containing_set == NULL),
551 err_msg("containing_set: "PTR_FORMAT" "
552 "_containing_set: "PTR_FORMAT,
553 p2i(containing_set), p2i(_containing_set)));
554
555 _containing_set = containing_set;
556 }
557
558 HeapRegionSetBase* containing_set() { return _containing_set; }
559 #else // ASSERT
560 void set_containing_set(HeapRegionSetBase* containing_set) { }
561
562 // containing_set() is only used in asserts so there's no reason
563 // to provide a dummy version of it.
564 #endif // ASSERT
565
566 // If we want to remove regions from a list in bulk we can simply tag
567 // them with the pending_removal tag and call the
568 // remove_all_pending() method on the list.
569
570 bool pending_removal() { return _pending_removal; }
571
572 void set_pending_removal(bool pending_removal) {
573 if (pending_removal) {
574 assert(!_pending_removal && containing_set() != NULL,
575 "can only set pending removal to true if it's false and "
576 "the region belongs to a region set");
577 } else {
578 assert( _pending_removal && containing_set() == NULL,
579 "can only set pending removal to false if it's true and "
580 "the region does not belong to a region set");
581 }
582
583 _pending_removal = pending_removal;
584 }
585
586 HeapRegion* get_next_young_region() { return _next_young_region; }
587 void set_next_young_region(HeapRegion* hr) {
588 _next_young_region = hr;
589 }
590
591 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
592 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
593 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
594 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
595
596 HeapWord* orig_end() { return _orig_end; }
597
598 // Allows logical separation between objects allocated before and after.
599 void save_marks();
600
601 // Reset HR stuff to default values.
602 void hr_clear(bool par, bool clear_space, bool locked = false);
603 void par_clear();
604
605 // Get the start of the unmarked area in this region.
606 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
607 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
608
609 // Apply "cl->do_oop" to (the addresses of) all reference fields in objects
610 // allocated in the current region before the last call to "save_mark".
611 void oop_before_save_marks_iterate(ExtendedOopClosure* cl);
612
613 // Note the start or end of marking. This tells the heap region
614 // that the collector is about to start or has finished (concurrently)
615 // marking the heap.
616
617 // Notify the region that concurrent marking is starting. Initialize
618 // all fields related to the next marking info.
619 inline void note_start_of_marking();
620
621 // Notify the region that concurrent marking has finished. Copy the
622 // (now finalized) next marking info fields into the prev marking
623 // info fields.
624 inline void note_end_of_marking();
625
626 // Notify the region that it will be used as to-space during a GC
627 // and we are about to start copying objects into it.
628 inline void note_start_of_copying(bool during_initial_mark);
629
630 // Notify the region that it ceases being to-space during a GC and
631 // we will not copy objects into it any more.
632 inline void note_end_of_copying(bool during_initial_mark);
633
634 // Notify the region that we are about to start processing
635 // self-forwarded objects during evac failure handling.
636 void note_self_forwarding_removal_start(bool during_initial_mark,
637 bool during_conc_mark);
638
639 // Notify the region that we have finished processing self-forwarded
640 // objects during evac failure handling.
641 void note_self_forwarding_removal_end(bool during_initial_mark,
642 bool during_conc_mark,
643 size_t marked_bytes);
644
645 // Returns "false" iff no object in the region was allocated when the
646 // last mark phase ended.
647 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
648
649 void reset_during_compaction() {
650 assert(isHumongous() && startsHumongous(),
651 "should only be called for starts humongous regions");
652
653 zero_marked_bytes();
654 init_top_at_mark_start();
655 }
656
657 void calc_gc_efficiency(void);
658 double gc_efficiency() { return _gc_efficiency;}
659
660 bool is_young() const { return _young_type != NotYoung; }
661 bool is_survivor() const { return _young_type == Survivor; }
662
663 int young_index_in_cset() const { return _young_index_in_cset; }
664 void set_young_index_in_cset(int index) {
665 assert( (index == -1) || is_young(), "pre-condition" );
666 _young_index_in_cset = index;
667 }
668
669 int age_in_surv_rate_group() {
670 assert( _surv_rate_group != NULL, "pre-condition" );
671 assert( _age_index > -1, "pre-condition" );
672 return _surv_rate_group->age_in_group(_age_index);
673 }
674
675 void record_surv_words_in_group(size_t words_survived) {
676 assert( _surv_rate_group != NULL, "pre-condition" );
677 assert( _age_index > -1, "pre-condition" );
678 int age_in_group = age_in_surv_rate_group();
679 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
680 }
681
682 int age_in_surv_rate_group_cond() {
683 if (_surv_rate_group != NULL)
684 return age_in_surv_rate_group();
685 else
686 return -1;
687 }
688
689 SurvRateGroup* surv_rate_group() {
690 return _surv_rate_group;
691 }
692
693 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
694 assert( surv_rate_group != NULL, "pre-condition" );
695 assert( _surv_rate_group == NULL, "pre-condition" );
696 assert( is_young(), "pre-condition" );
697
698 _surv_rate_group = surv_rate_group;
699 _age_index = surv_rate_group->next_age_index();
700 }
701
702 void uninstall_surv_rate_group() {
703 if (_surv_rate_group != NULL) {
704 assert( _age_index > -1, "pre-condition" );
705 assert( is_young(), "pre-condition" );
706
707 _surv_rate_group = NULL;
708 _age_index = -1;
709 } else {
710 assert( _age_index == -1, "pre-condition" );
711 }
712 }
713
714 void set_young() { set_young_type(Young); }
715
716 void set_survivor() { set_young_type(Survivor); }
717
718 void set_not_young() { set_young_type(NotYoung); }
719
720 // Determine if an object has been allocated since the last
721 // mark performed by the collector. This returns true iff the object
722 // is within the unmarked area of the region.
723 bool obj_allocated_since_prev_marking(oop obj) const {
724 return (HeapWord *) obj >= prev_top_at_mark_start();
725 }
726 bool obj_allocated_since_next_marking(oop obj) const {
727 return (HeapWord *) obj >= next_top_at_mark_start();
728 }
729
730 // For parallel heapRegion traversal.
731 bool claimHeapRegion(int claimValue);
732 jint claim_value() { return _claimed; }
733 // Use this carefully: only when you're sure no one is claiming...
734 void set_claim_value(int claimValue) { _claimed = claimValue; }
735
736 // Returns the "evacuation_failed" property of the region.
737 bool evacuation_failed() { return _evacuation_failed; }
738
739 // Sets the "evacuation_failed" property of the region.
740 void set_evacuation_failed(bool b) {
741 _evacuation_failed = b;
742
743 if (b) {
744 _next_marked_bytes = 0;
745 }
746 }
747
748 // Requires that "mr" be entirely within the region.
749 // Apply "cl->do_object" to all objects that intersect with "mr".
750 // If the iteration encounters an unparseable portion of the region,
751 // or if "cl->abort()" is true after a closure application,
752 // terminate the iteration and return the address of the start of the
753 // subregion that isn't done. (The two can be distinguished by querying
754 // "cl->abort()".) Return of "NULL" indicates that the iteration
755 // completed.
756 HeapWord*
757 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
758
759 // filter_young: if true and the region is a young region then we
760 // skip the iteration.
761 // card_ptr: if not NULL, and we decide that the card is not young
762 // and we iterate over it, we'll clean the card before we start the
763 // iteration.
764 HeapWord*
765 oops_on_card_seq_iterate_careful(MemRegion mr,
766 FilterOutOfRegionClosure* cl,
767 bool filter_young,
768 jbyte* card_ptr);
769
770 // A version of block start that is guaranteed to find *some* block
771 // boundary at or before "p", but does not object iteration, and may
772 // therefore be used safely when the heap is unparseable.
773 HeapWord* block_start_careful(const void* p) const {
774 return _offsets.block_start_careful(p);
775 }
776
777 // Requires that "addr" is within the region. Returns the start of the
778 // first ("careful") block that starts at or after "addr", or else the
779 // "end" of the region if there is no such block.
780 HeapWord* next_block_start_careful(HeapWord* addr);
781
782 size_t recorded_rs_length() const { return _recorded_rs_length; }
783 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
784 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }
785
786 void set_recorded_rs_length(size_t rs_length) {
787 _recorded_rs_length = rs_length;
788 }
789
790 void set_predicted_elapsed_time_ms(double ms) {
791 _predicted_elapsed_time_ms = ms;
792 }
793
794 void set_predicted_bytes_to_copy(size_t bytes) {
795 _predicted_bytes_to_copy = bytes;
796 }
797
798 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
799 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
800 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DECL)
801
802 virtual CompactibleSpace* next_compaction_space() const;
803
804 virtual void reset_after_compaction();
805
806 // Routines for managing a list of code roots (attached to the
807 // this region's RSet) that point into this heap region.
808 void add_strong_code_root(nmethod* nm);
809 void remove_strong_code_root(nmethod* nm);
810
811 // During a collection, migrate the successfully evacuated
812 // strong code roots that referenced into this region to the
813 // new regions that they now point into. Unsuccessfully
814 // evacuated code roots are not migrated.
815 void migrate_strong_code_roots();
816
817 // Applies blk->do_code_blob() to each of the entries in
818 // the strong code roots list for this region
819 void strong_code_roots_do(CodeBlobClosure* blk) const;
820
821 // Verify that the entries on the strong code root list for this
822 // region are live and include at least one pointer into this region.
823 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
824
825 void print() const;
826 void print_on(outputStream* st) const;
827
828 // vo == UsePrevMarking -> use "prev" marking information,
829 // vo == UseNextMarking -> use "next" marking information
830 // vo == UseMarkWord -> use the mark word in the object header
831 //
832 // NOTE: Only the "prev" marking information is guaranteed to be
833 // consistent most of the time, so most calls to this should use
834 // vo == UsePrevMarking.
835 // Currently, there is only one case where this is called with
836 // vo == UseNextMarking, which is to verify the "next" marking
837 // information at the end of remark.
838 // Currently there is only one place where this is called with
839 // vo == UseMarkWord, which is to verify the marking during a
840 // full GC.
841 void verify(VerifyOption vo, bool *failures) const;
842
843 // Override; it uses the "prev" marking information
844 virtual void verify() const;
845 };
846
847 // HeapRegionClosure is used for iterating over regions.
848 // Terminates the iteration when the "doHeapRegion" method returns "true".
849 class HeapRegionClosure : public StackObj {
850 friend class HeapRegionSeq;
851 friend class G1CollectedHeap;
852
853 bool _complete;
854 void incomplete() { _complete = false; }
855
856 public:
857 HeapRegionClosure(): _complete(true) {}
858
859 // Typically called on each region until it returns true.
860 virtual bool doHeapRegion(HeapRegion* r) = 0;
861
862 // True after iteration if the closure was applied to all heap regions
863 // and returned "false" in all cases.
864 bool complete() { return _complete; }
865 };
866
867 #endif // INCLUDE_ALL_GCS
868
869 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP