1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25 #ifndef SHARE_VM_GC_G1_HEAPREGION_HPP
26 #define SHARE_VM_GC_G1_HEAPREGION_HPP
27
28 #include "gc/g1/g1AllocationContext.hpp"
29 #include "gc/g1/g1BlockOffsetTable.hpp"
30 #include "gc/g1/heapRegionType.hpp"
31 #include "gc/g1/survRateGroup.hpp"
32 #include "gc/shared/ageTable.hpp"
33 #include "gc/shared/spaceDecorator.hpp"
34 #include "utilities/macros.hpp"
35
36 // A HeapRegion is the smallest piece of a G1CollectedHeap that
37 // can be collected independently.
38
39 // NOTE: Although a HeapRegion is a Space, its
40 // Space::initDirtyCardClosure method must not be called.
41 // The problem is that the existence of this method breaks
42 // the independence of barrier sets from remembered sets.
43 // The solution is to remove this method from the definition
44 // of a Space.
45
46 // Each heap region is self contained. top() and end() can never
47 // be set beyond the end of the region. For humongous objects,
48 // the first region is a StartsHumongous region. If the humongous
49 // object is larger than a heap region, the following regions will
50 // be of type ContinuesHumongous. In this case the top() and end()
51 // of the StartHumongous region will point to the end of that region.
52 // The same will be true for all ContinuesHumongous regions except
53 // the last, which will have its' top() at the objects' top.
54
55 class G1CollectedHeap;
56 class HeapRegionRemSet;
57 class HeapRegionRemSetIterator;
58 class HeapRegion;
59 class HeapRegionSetBase;
60 class nmethod;
61
62 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
63 #define HR_FORMAT_PARAMS(_hr_) \
64 (_hr_)->hrm_index(), \
65 (_hr_)->get_short_type_str(), \
66 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
67
68 // sentinel value for hrm_index
69 #define G1_NO_HRM_INDEX ((uint) -1)
70
71 // A dirty card to oop closure for heap regions. It
72 // knows how to get the G1 heap and how to use the bitmap
73 // in the concurrent marker used by G1 to filter remembered
74 // sets.
75
76 class HeapRegionDCTOC : public DirtyCardToOopClosure {
77 private:
78 HeapRegion* _hr;
79 G1ParPushHeapRSClosure* _rs_scan;
80 G1CollectedHeap* _g1;
81
82 // Walk the given memory region from bottom to (actual) top
83 // looking for objects and applying the oop closure (_cl) to
84 // them. The base implementation of this treats the area as
85 // blocks, where a block may or may not be an object. Sub-
86 // classes should override this to provide more accurate
87 // or possibly more efficient walking.
88 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
89
90 public:
91 HeapRegionDCTOC(G1CollectedHeap* g1,
92 HeapRegion* hr,
93 G1ParPushHeapRSClosure* cl,
94 CardTableModRefBS::PrecisionStyle precision);
95 };
96
97 // The complicating factor is that BlockOffsetTable diverged
98 // significantly, and we need functionality that is only in the G1 version.
99 // So I copied that code, which led to an alternate G1 version of
100 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
101 // be reconciled, then G1OffsetTableContigSpace could go away.
102
103 // The idea behind time stamps is the following. We want to keep track of
104 // the highest address where it's safe to scan objects for each region.
105 // This is only relevant for current GC alloc regions so we keep a time stamp
106 // per region to determine if the region has been allocated during the current
107 // GC or not. If the time stamp is current we report a scan_top value which
108 // was saved at the end of the previous GC for retained alloc regions and which is
109 // equal to the bottom for all other regions.
110 // There is a race between card scanners and allocating gc workers where we must ensure
111 // that card scanners do not read the memory allocated by the gc workers.
112 // In order to enforce that, we must not return a value of _top which is more recent than the
113 // time stamp. This is due to the fact that a region may become a gc alloc region at
114 // some point after we've read the timestamp value as being < the current time stamp.
115 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
116 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
117 // evacuation pauses between two cleanups, which is _highly_ unlikely.
118 class G1OffsetTableContigSpace: public CompactibleSpace {
119 friend class VMStructs;
120 HeapWord* volatile _top;
121 HeapWord* volatile _scan_top;
122 protected:
123 G1BlockOffsetArrayContigSpace _offsets;
124 Mutex _par_alloc_lock;
125 volatile unsigned _gc_time_stamp;
126 // When we need to retire an allocation region, while other threads
127 // are also concurrently trying to allocate into it, we typically
128 // allocate a dummy object at the end of the region to ensure that
129 // no more allocations can take place in it. However, sometimes we
130 // want to know where the end of the last "real" object we allocated
131 // into the region was and this is what this keeps track.
132 HeapWord* _pre_dummy_top;
133
134 public:
135 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
136 MemRegion mr);
137
138 void set_top(HeapWord* value) { _top = value; }
139 HeapWord* top() const { return _top; }
140
141 protected:
142 // Reset the G1OffsetTableContigSpace.
143 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
144
145 HeapWord* volatile* top_addr() { return &_top; }
146 // Try to allocate at least min_word_size and up to desired_size from this Space.
147 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
148 // space allocated.
149 // This version assumes that all allocation requests to this Space are properly
150 // synchronized.
151 inline HeapWord* allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
152 // Try to allocate at least min_word_size and up to desired_size from this Space.
153 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
154 // space allocated.
155 // This version synchronizes with other calls to par_allocate_impl().
156 inline HeapWord* par_allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
157
158 public:
159 void reset_after_compaction() { set_top(compaction_top()); }
160
161 size_t used() const { return byte_size(bottom(), top()); }
162 size_t free() const { return byte_size(top(), end()); }
163 bool is_free_block(const HeapWord* p) const { return p >= top(); }
164
165 MemRegion used_region() const { return MemRegion(bottom(), top()); }
166
167 void object_iterate(ObjectClosure* blk);
168 void safe_object_iterate(ObjectClosure* blk);
169
170 void set_bottom(HeapWord* value);
171 void set_end(HeapWord* value);
172
173 void mangle_unused_area() PRODUCT_RETURN;
174 void mangle_unused_area_complete() PRODUCT_RETURN;
175
176 HeapWord* scan_top() const;
177 void record_timestamp();
178 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
179 unsigned get_gc_time_stamp() { return _gc_time_stamp; }
180 void record_retained_region();
181
182 // See the comment above in the declaration of _pre_dummy_top for an
183 // explanation of what it is.
184 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
185 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
186 _pre_dummy_top = pre_dummy_top;
187 }
188 HeapWord* pre_dummy_top() {
189 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
190 }
191 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
192
193 virtual void clear(bool mangle_space);
194
195 HeapWord* block_start(const void* p);
196 HeapWord* block_start_const(const void* p) const;
197
198 // Allocation (return NULL if full). Assumes the caller has established
199 // mutually exclusive access to the space.
200 HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
201 // Allocation (return NULL if full). Enforces mutual exclusion internally.
202 HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
203
204 virtual HeapWord* allocate(size_t word_size);
205 virtual HeapWord* par_allocate(size_t word_size);
206
207 HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
208
209 // MarkSweep support phase3
210 virtual HeapWord* initialize_threshold();
211 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
212
213 virtual void print() const;
214
215 void reset_bot() {
216 _offsets.reset_bot();
217 }
218
219 void print_bot_on(outputStream* out) {
220 _offsets.print_on(out);
221 }
222 };
223
224 class HeapRegion: public G1OffsetTableContigSpace {
225 friend class VMStructs;
226 // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
227 template <typename SpaceType>
228 friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
229 private:
230
231 // The remembered set for this region.
232 // (Might want to make this "inline" later, to avoid some alloc failure
233 // issues.)
234 HeapRegionRemSet* _rem_set;
235
236 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
237
238 // Auxiliary functions for scan_and_forward support.
239 // See comments for CompactibleSpace for more information.
240 inline HeapWord* scan_limit() const {
241 return top();
242 }
243
244 inline bool scanned_block_is_obj(const HeapWord* addr) const {
245 return true; // Always true, since scan_limit is top
246 }
247
248 inline size_t scanned_block_size(const HeapWord* addr) const {
249 return HeapRegion::block_size(addr); // Avoid virtual call
250 }
251
252 protected:
253 // The index of this region in the heap region sequence.
254 uint _hrm_index;
255
256 AllocationContext_t _allocation_context;
257
258 HeapRegionType _type;
259
260 // For a humongous region, region in which it starts.
261 HeapRegion* _humongous_start_region;
262
263 // True iff an attempt to evacuate an object in the region failed.
264 bool _evacuation_failed;
265
266 // A heap region may be a member one of a number of special subsets, each
267 // represented as linked lists through the field below. Currently, there
268 // is only one set:
269 // The collection set.
270 HeapRegion* _next_in_special_set;
271
272 // next region in the young "generation" region set
273 HeapRegion* _next_young_region;
274
275 // Next region whose cards need cleaning
276 HeapRegion* _next_dirty_cards_region;
277
278 // Fields used by the HeapRegionSetBase class and subclasses.
279 HeapRegion* _next;
280 HeapRegion* _prev;
281 #ifdef ASSERT
282 HeapRegionSetBase* _containing_set;
283 #endif // ASSERT
284
285 // We use concurrent marking to determine the amount of live data
286 // in each heap region.
287 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
288 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
289
290 // The calculated GC efficiency of the region.
291 double _gc_efficiency;
292
293 int _young_index_in_cset;
294 SurvRateGroup* _surv_rate_group;
295 int _age_index;
296
297 // The start of the unmarked area. The unmarked area extends from this
298 // word until the top and/or end of the region, and is the part
299 // of the region for which no marking was done, i.e. objects may
300 // have been allocated in this part since the last mark phase.
301 // "prev" is the top at the start of the last completed marking.
302 // "next" is the top at the start of the in-progress marking (if any.)
303 HeapWord* _prev_top_at_mark_start;
304 HeapWord* _next_top_at_mark_start;
305 // If a collection pause is in progress, this is the top at the start
306 // of that pause.
307
308 void init_top_at_mark_start() {
309 assert(_prev_marked_bytes == 0 &&
310 _next_marked_bytes == 0,
311 "Must be called after zero_marked_bytes.");
312 HeapWord* bot = bottom();
313 _prev_top_at_mark_start = bot;
314 _next_top_at_mark_start = bot;
315 }
316
317 // Cached attributes used in the collection set policy information
318
319 // The RSet length that was added to the total value
320 // for the collection set.
321 size_t _recorded_rs_length;
322
323 // The predicted elapsed time that was added to total value
324 // for the collection set.
325 double _predicted_elapsed_time_ms;
326
327 // The predicted number of bytes to copy that was added to
328 // the total value for the collection set.
329 size_t _predicted_bytes_to_copy;
330
331 public:
332 HeapRegion(uint hrm_index,
333 G1BlockOffsetSharedArray* sharedOffsetArray,
334 MemRegion mr);
335
336 // Initializing the HeapRegion not only resets the data structure, but also
337 // resets the BOT for that heap region.
338 // The default values for clear_space means that we will do the clearing if
339 // there's clearing to be done ourselves. We also always mangle the space.
340 virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
341
342 static int LogOfHRGrainBytes;
343 static int LogOfHRGrainWords;
344
345 static size_t GrainBytes;
346 static size_t GrainWords;
347 static size_t CardsPerRegion;
348
349 static size_t align_up_to_region_byte_size(size_t sz) {
350 return (sz + (size_t) GrainBytes - 1) &
351 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
352 }
353
354 static size_t max_region_size();
355 static size_t min_region_size_in_words();
356
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);
364
365 // All allocated blocks are occupied by objects in a HeapRegion
366 bool block_is_obj(const HeapWord* p) const;
367
368 // Returns the object size for all valid block starts
369 // and the amount of unallocated words if called on top()
370 size_t block_size(const HeapWord* p) const;
371
372 // Override for scan_and_forward support.
373 void prepare_for_compaction(CompactPoint* cp);
374
375 inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
376 inline HeapWord* allocate_no_bot_updates(size_t word_size);
377 inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
378
379 // If this region is a member of a HeapRegionManager, the index in that
380 // sequence, otherwise -1.
381 uint hrm_index() const { return _hrm_index; }
382
383 // The number of bytes marked live in the region in the last marking phase.
384 size_t marked_bytes() { return _prev_marked_bytes; }
385 size_t live_bytes() {
386 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
387 }
388
389 // The number of bytes counted in the next marking.
390 size_t next_marked_bytes() { return _next_marked_bytes; }
391 // The number of bytes live wrt the next marking.
392 size_t next_live_bytes() {
393 return
394 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
395 }
396
397 // A lower bound on the amount of garbage bytes in the region.
398 size_t garbage_bytes() {
399 size_t used_at_mark_start_bytes =
400 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
401 return used_at_mark_start_bytes - marked_bytes();
402 }
403
404 // Return the amount of bytes we'll reclaim if we collect this
405 // region. This includes not only the known garbage bytes in the
406 // region but also any unallocated space in it, i.e., [top, end),
407 // since it will also be reclaimed if we collect the region.
408 size_t reclaimable_bytes() {
409 size_t known_live_bytes = live_bytes();
410 assert(known_live_bytes <= capacity(), "sanity");
411 return capacity() - known_live_bytes;
412 }
413
414 // An upper bound on the number of live bytes in the region.
415 size_t max_live_bytes() { return used() - garbage_bytes(); }
416
417 void add_to_marked_bytes(size_t incr_bytes) {
418 _next_marked_bytes = _next_marked_bytes + incr_bytes;
419 }
420
421 void zero_marked_bytes() {
422 _prev_marked_bytes = _next_marked_bytes = 0;
423 }
424
425 const char* get_type_str() const { return _type.get_str(); }
426 const char* get_short_type_str() const { return _type.get_short_str(); }
427
428 bool is_free() const { return _type.is_free(); }
429
430 bool is_young() const { return _type.is_young(); }
431 bool is_eden() const { return _type.is_eden(); }
432 bool is_survivor() const { return _type.is_survivor(); }
433
434 bool is_humongous() const { return _type.is_humongous(); }
435 bool is_starts_humongous() const { return _type.is_starts_humongous(); }
436 bool is_continues_humongous() const { return _type.is_continues_humongous(); }
437
438 bool is_old() const { return _type.is_old(); }
439
440 // A pinned region contains objects which are not moved by garbage collections.
441 // Humongous regions and archive regions are pinned.
442 bool is_pinned() const { return _type.is_pinned(); }
443
444 // An archive region is a pinned region, also tagged as old, which
445 // should not be marked during mark/sweep. This allows the address
446 // space to be shared by JVM instances.
447 bool is_archive() const { return _type.is_archive(); }
448
449 // For a humongous region, region in which it starts.
450 HeapRegion* humongous_start_region() const {
451 return _humongous_start_region;
452 }
453
454 // Makes the current region be a "starts humongous" region, i.e.,
455 // the first region in a series of one or more contiguous regions
456 // that will contain a single "humongous" object.
457 //
458 // obj_top : points to the end of the humongous object that's being
459 // allocated.
460 void set_starts_humongous(HeapWord* obj_top);
461
462 // Makes the current region be a "continues humongous'
463 // region. first_hr is the "start humongous" region of the series
464 // which this region will be part of.
465 void set_continues_humongous(HeapRegion* first_hr);
466
467 // Unsets the humongous-related fields on the region.
468 void clear_humongous();
469
470 // If the region has a remembered set, return a pointer to it.
471 HeapRegionRemSet* rem_set() const {
472 return _rem_set;
473 }
474
475 inline bool in_collection_set() const;
476
477 inline HeapRegion* next_in_collection_set() const;
478 inline void set_next_in_collection_set(HeapRegion* r);
479
480 void set_allocation_context(AllocationContext_t context) {
481 _allocation_context = context;
482 }
483
484 AllocationContext_t allocation_context() const {
485 return _allocation_context;
486 }
487
488 // Methods used by the HeapRegionSetBase class and subclasses.
489
490 // Getter and setter for the next and prev fields used to link regions into
491 // linked lists.
492 HeapRegion* next() { return _next; }
493 HeapRegion* prev() { return _prev; }
494
495 void set_next(HeapRegion* next) { _next = next; }
496 void set_prev(HeapRegion* prev) { _prev = prev; }
497
498 // Every region added to a set is tagged with a reference to that
499 // set. This is used for doing consistency checking to make sure that
500 // the contents of a set are as they should be and it's only
501 // available in non-product builds.
502 #ifdef ASSERT
503 void set_containing_set(HeapRegionSetBase* containing_set) {
504 assert((containing_set == NULL && _containing_set != NULL) ||
505 (containing_set != NULL && _containing_set == NULL),
506 "containing_set: " PTR_FORMAT " "
507 "_containing_set: " PTR_FORMAT,
508 p2i(containing_set), p2i(_containing_set));
509
510 _containing_set = containing_set;
511 }
512
513 HeapRegionSetBase* containing_set() { return _containing_set; }
514 #else // ASSERT
515 void set_containing_set(HeapRegionSetBase* containing_set) { }
516
517 // containing_set() is only used in asserts so there's no reason
518 // to provide a dummy version of it.
519 #endif // ASSERT
520
521 HeapRegion* get_next_young_region() { return _next_young_region; }
522 void set_next_young_region(HeapRegion* hr) {
523 _next_young_region = hr;
524 }
525
526 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
527 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
528 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
529 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
530
531 // Reset HR stuff to default values.
532 void hr_clear(bool par, bool clear_space, bool locked = false);
533 void par_clear();
534
535 // Get the start of the unmarked area in this region.
536 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
537 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
538
539 // Note the start or end of marking. This tells the heap region
540 // that the collector is about to start or has finished (concurrently)
541 // marking the heap.
542
543 // Notify the region that concurrent marking is starting. Initialize
544 // all fields related to the next marking info.
545 inline void note_start_of_marking();
546
547 // Notify the region that concurrent marking has finished. Copy the
548 // (now finalized) next marking info fields into the prev marking
549 // info fields.
550 inline void note_end_of_marking();
551
552 // Notify the region that it will be used as to-space during a GC
553 // and we are about to start copying objects into it.
554 inline void note_start_of_copying(bool during_initial_mark);
555
556 // Notify the region that it ceases being to-space during a GC and
557 // we will not copy objects into it any more.
558 inline void note_end_of_copying(bool during_initial_mark);
559
560 // Notify the region that we are about to start processing
561 // self-forwarded objects during evac failure handling.
562 void note_self_forwarding_removal_start(bool during_initial_mark,
563 bool during_conc_mark);
564
565 // Notify the region that we have finished processing self-forwarded
566 // objects during evac failure handling.
567 void note_self_forwarding_removal_end(bool during_initial_mark,
568 bool during_conc_mark,
569 size_t marked_bytes);
570
571 // Returns "false" iff no object in the region was allocated when the
572 // last mark phase ended.
573 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
574
575 void reset_during_compaction() {
576 assert(is_humongous(),
577 "should only be called for humongous regions");
578
579 zero_marked_bytes();
580 init_top_at_mark_start();
581 }
582
583 void calc_gc_efficiency(void);
584 double gc_efficiency() { return _gc_efficiency;}
585
586 int young_index_in_cset() const { return _young_index_in_cset; }
587 void set_young_index_in_cset(int index) {
588 assert( (index == -1) || is_young(), "pre-condition" );
589 _young_index_in_cset = index;
590 }
591
592 int age_in_surv_rate_group() {
593 assert( _surv_rate_group != NULL, "pre-condition" );
594 assert( _age_index > -1, "pre-condition" );
595 return _surv_rate_group->age_in_group(_age_index);
596 }
597
598 void record_surv_words_in_group(size_t words_survived) {
599 assert( _surv_rate_group != NULL, "pre-condition" );
600 assert( _age_index > -1, "pre-condition" );
601 int age_in_group = age_in_surv_rate_group();
602 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
603 }
604
605 int age_in_surv_rate_group_cond() {
606 if (_surv_rate_group != NULL)
607 return age_in_surv_rate_group();
608 else
609 return -1;
610 }
611
612 SurvRateGroup* surv_rate_group() {
613 return _surv_rate_group;
614 }
615
616 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
617 assert( surv_rate_group != NULL, "pre-condition" );
618 assert( _surv_rate_group == NULL, "pre-condition" );
619 assert( is_young(), "pre-condition" );
620
621 _surv_rate_group = surv_rate_group;
622 _age_index = surv_rate_group->next_age_index();
623 }
624
625 void uninstall_surv_rate_group() {
626 if (_surv_rate_group != NULL) {
627 assert( _age_index > -1, "pre-condition" );
628 assert( is_young(), "pre-condition" );
629
630 _surv_rate_group = NULL;
631 _age_index = -1;
632 } else {
633 assert( _age_index == -1, "pre-condition" );
634 }
635 }
636
637 void set_free() { _type.set_free(); }
638
639 void set_eden() { _type.set_eden(); }
640 void set_eden_pre_gc() { _type.set_eden_pre_gc(); }
641 void set_survivor() { _type.set_survivor(); }
642
643 void set_old() { _type.set_old(); }
644
645 void set_archive() { _type.set_archive(); }
646
647 // Determine if an object has been allocated since the last
648 // mark performed by the collector. This returns true iff the object
649 // is within the unmarked area of the region.
650 bool obj_allocated_since_prev_marking(oop obj) const {
651 return (HeapWord *) obj >= prev_top_at_mark_start();
652 }
653 bool obj_allocated_since_next_marking(oop obj) const {
654 return (HeapWord *) obj >= next_top_at_mark_start();
655 }
656
657 // Returns the "evacuation_failed" property of the region.
658 bool evacuation_failed() { return _evacuation_failed; }
659
660 // Sets the "evacuation_failed" property of the region.
661 void set_evacuation_failed(bool b) {
662 _evacuation_failed = b;
663
664 if (b) {
665 _next_marked_bytes = 0;
666 }
667 }
668
669 // Requires that "mr" be entirely within the region.
670 // Apply "cl->do_object" to all objects that intersect with "mr".
671 // If the iteration encounters an unparseable portion of the region,
672 // or if "cl->abort()" is true after a closure application,
673 // terminate the iteration and return the address of the start of the
674 // subregion that isn't done. (The two can be distinguished by querying
675 // "cl->abort()".) Return of "NULL" indicates that the iteration
676 // completed.
677 HeapWord*
678 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
679
680 // filter_young: if true and the region is a young region then we
681 // skip the iteration.
682 // card_ptr: if not NULL, and we decide that the card is not young
683 // and we iterate over it, we'll clean the card before we start the
684 // iteration.
685 HeapWord*
686 oops_on_card_seq_iterate_careful(MemRegion mr,
687 FilterOutOfRegionClosure* cl,
688 bool filter_young,
689 jbyte* card_ptr);
690
691 size_t recorded_rs_length() const { return _recorded_rs_length; }
692 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
693 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }
694
695 void set_recorded_rs_length(size_t rs_length) {
696 _recorded_rs_length = rs_length;
697 }
698
699 void set_predicted_elapsed_time_ms(double ms) {
700 _predicted_elapsed_time_ms = ms;
701 }
702
703 void set_predicted_bytes_to_copy(size_t bytes) {
704 _predicted_bytes_to_copy = bytes;
705 }
706
707 virtual CompactibleSpace* next_compaction_space() const;
708
709 virtual void reset_after_compaction();
710
711 // Routines for managing a list of code roots (attached to the
712 // this region's RSet) that point into this heap region.
713 void add_strong_code_root(nmethod* nm);
714 void add_strong_code_root_locked(nmethod* nm);
715 void remove_strong_code_root(nmethod* nm);
716
717 // Applies blk->do_code_blob() to each of the entries in
718 // the strong code roots list for this region
719 void strong_code_roots_do(CodeBlobClosure* blk) const;
720
721 // Verify that the entries on the strong code root list for this
722 // region are live and include at least one pointer into this region.
723 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
724
725 void print() const;
726 void print_on(outputStream* st) const;
727
728 // vo == UsePrevMarking -> use "prev" marking information,
729 // vo == UseNextMarking -> use "next" marking information
730 // vo == UseMarkWord -> use the mark word in the object header
731 //
732 // NOTE: Only the "prev" marking information is guaranteed to be
733 // consistent most of the time, so most calls to this should use
734 // vo == UsePrevMarking.
735 // Currently, there is only one case where this is called with
736 // vo == UseNextMarking, which is to verify the "next" marking
737 // information at the end of remark.
738 // Currently there is only one place where this is called with
739 // vo == UseMarkWord, which is to verify the marking during a
740 // full GC.
741 void verify(VerifyOption vo, bool *failures) const;
742
743 // Override; it uses the "prev" marking information
744 virtual void verify() const;
745 };
746
747 // HeapRegionClosure is used for iterating over regions.
748 // Terminates the iteration when the "doHeapRegion" method returns "true".
749 class HeapRegionClosure : public StackObj {
750 friend class HeapRegionManager;
751 friend class G1CollectedHeap;
752
753 bool _complete;
754 void incomplete() { _complete = false; }
755
756 public:
757 HeapRegionClosure(): _complete(true) {}
758
759 // Typically called on each region until it returns true.
760 virtual bool doHeapRegion(HeapRegion* r) = 0;
761
762 // True after iteration if the closure was applied to all heap regions
763 // and returned "false" in all cases.
764 bool complete() { return _complete; }
765 };
766
767 #endif // SHARE_VM_GC_G1_HEAPREGION_HPP