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
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
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.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 HeapRegionRemSet;
50 class HeapRegionRemSetIterator;
51 class HeapRegion;
52 class HeapRegionSetBase;
53 class nmethod;
54
55 #define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"
56 #define HR_FORMAT_PARAMS(_hr_) \
57 (_hr_)->hrs_index(), \
58 (_hr_)->is_survivor() ? "S" : (_hr_)->is_young() ? "E" : \
59 (_hr_)->startsHumongous() ? "HS" : \
60 (_hr_)->continuesHumongous() ? "HC" : \
61 !(_hr_)->is_empty() ? "O" : "F", \
62 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
63
64 // sentinel value for hrs_index
65 #define G1_NULL_HRS_INDEX ((uint) -1)
66
67 // A dirty card to oop closure for heap regions. It
68 // knows how to get the G1 heap and how to use the bitmap
69 // in the concurrent marker used by G1 to filter remembered
70 // sets.
71
72 class HeapRegionDCTOC : public DirtyCardToOopClosure {
73 public:
74 // Specification of possible DirtyCardToOopClosure filtering.
75 enum FilterKind {
76 NoFilterKind,
77 IntoCSFilterKind,
78 OutOfRegionFilterKind
79 };
80
81 protected:
82 HeapRegion* _hr;
83 FilterKind _fk;
84 G1CollectedHeap* _g1;
85
86 // Walk the given memory region from bottom to (actual) top
87 // looking for objects and applying the oop closure (_cl) to
88 // them. The base implementation of this treats the area as
89 // blocks, where a block may or may not be an object. Sub-
90 // classes should override this to provide more accurate
91 // or possibly more efficient walking.
92 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
93
94 public:
95 HeapRegionDCTOC(G1CollectedHeap* g1,
96 HeapRegion* hr, ExtendedOopClosure* cl,
97 CardTableModRefBS::PrecisionStyle precision,
98 FilterKind fk);
99 };
100
101 // The complicating factor is that BlockOffsetTable diverged
102 // significantly, and we need functionality that is only in the G1 version.
103 // So I copied that code, which led to an alternate G1 version of
104 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
105 // be reconciled, then G1OffsetTableContigSpace could go away.
106
107 // The idea behind time stamps is the following. Doing a save_marks on
108 // all regions at every GC pause is time consuming (if I remember
109 // well, 10ms or so). So, we would like to do that only for regions
110 // that are GC alloc regions. To achieve this, we use time
111 // stamps. For every evacuation pause, G1CollectedHeap generates a
112 // unique time stamp (essentially a counter that gets
113 // incremented). Every time we want to call save_marks on a region,
114 // we set the saved_mark_word to top and also copy the current GC
115 // time stamp to the time stamp field of the space. Reading the
116 // saved_mark_word involves checking the time stamp of the
117 // region. If it is the same as the current GC time stamp, then we
118 // can safely read the saved_mark_word field, as it is valid. If the
119 // time stamp of the region is not the same as the current GC time
120 // stamp, then we instead read top, as the saved_mark_word field is
121 // invalid. Time stamps (on the regions and also on the
122 // G1CollectedHeap) are reset at every cleanup (we iterate over
123 // the regions anyway) and at the end of a Full GC. The current scheme
124 // that uses sequential unsigned ints will fail only if we have 4b
125 // evacuation pauses between two cleanups, which is _highly_ unlikely.
126 class G1OffsetTableContigSpace: public CompactibleSpace {
127 friend class VMStructs;
128 HeapWord* _top;
129 protected:
130 G1BlockOffsetArrayContigSpace _offsets;
131 Mutex _par_alloc_lock;
132 volatile unsigned _gc_time_stamp;
133 // When we need to retire an allocation region, while other threads
134 // are also concurrently trying to allocate into it, we typically
135 // allocate a dummy object at the end of the region to ensure that
136 // no more allocations can take place in it. However, sometimes we
137 // want to know where the end of the last "real" object we allocated
138 // into the region was and this is what this keeps track.
139 HeapWord* _pre_dummy_top;
140
141 public:
142 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
143 MemRegion mr);
144
145 void set_top(HeapWord* value) { _top = value; }
146 HeapWord* top() const { return _top; }
147
148 protected:
149 HeapWord** top_addr() { return &_top; }
150 // Allocation helpers (return NULL if full).
151 inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
152 inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);
153
154 public:
155 void reset_after_compaction() { set_top(compaction_top()); }
156
157 size_t used() const { return byte_size(bottom(), top()); }
158 size_t free() const { return byte_size(top(), end()); }
159 bool is_free_block(const HeapWord* p) const { return p >= top(); }
160
161 MemRegion used_region() const { return MemRegion(bottom(), top()); }
162
163 void object_iterate(ObjectClosure* blk);
164 void safe_object_iterate(ObjectClosure* blk);
165
166 void set_bottom(HeapWord* value);
167 void set_end(HeapWord* value);
168
169 virtual HeapWord* saved_mark_word() const;
170 void record_top_and_timestamp();
171 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
172 unsigned get_gc_time_stamp() { return _gc_time_stamp; }
173
174 // See the comment above in the declaration of _pre_dummy_top for an
175 // explanation of what it is.
176 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
177 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
178 _pre_dummy_top = pre_dummy_top;
179 }
180 HeapWord* pre_dummy_top() {
181 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
182 }
183 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
184
185 virtual void clear(bool mangle_space);
186
187 HeapWord* block_start(const void* p);
188 HeapWord* block_start_const(const void* p) const;
189
190 void prepare_for_compaction(CompactPoint* cp);
191
192 // Add offset table update.
193 virtual HeapWord* allocate(size_t word_size);
194 HeapWord* par_allocate(size_t word_size);
195
196 // MarkSweep support phase3
197 virtual HeapWord* initialize_threshold();
198 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
199
200 virtual void print() const;
201
202 void reset_bot() {
203 _offsets.zero_bottom_entry();
204 _offsets.initialize_threshold();
205 }
206
207 void update_bot_for_object(HeapWord* start, size_t word_size) {
208 _offsets.alloc_block(start, word_size);
209 }
210
211 void print_bot_on(outputStream* out) {
212 _offsets.print_on(out);
213 }
214 };
215
216 class HeapRegion: public G1OffsetTableContigSpace {
217 friend class VMStructs;
218 private:
219
220 enum HumongousType {
221 NotHumongous = 0,
222 StartsHumongous,
223 ContinuesHumongous
224 };
225
226 // The remembered set for this region.
227 // (Might want to make this "inline" later, to avoid some alloc failure
228 // issues.)
229 HeapRegionRemSet* _rem_set;
230
231 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
232
233 protected:
234 // The index of this region in the heap region sequence.
235 uint _hrs_index;
236
237 HumongousType _humongous_type;
238 // For a humongous region, region in which it starts.
239 HeapRegion* _humongous_start_region;
240 // For the start region of a humongous sequence, it's original end().
241 HeapWord* _orig_end;
242
243 // True iff the region is in current collection_set.
244 bool _in_collection_set;
245
246 // True iff an attempt to evacuate an object in the region failed.
247 bool _evacuation_failed;
248
249 // A heap region may be a member one of a number of special subsets, each
250 // represented as linked lists through the field below. Currently, there
251 // is only one set:
252 // The collection set.
253 HeapRegion* _next_in_special_set;
254
255 // next region in the young "generation" region set
256 HeapRegion* _next_young_region;
257
258 // Next region whose cards need cleaning
259 HeapRegion* _next_dirty_cards_region;
260
261 // Fields used by the HeapRegionSetBase class and subclasses.
262 HeapRegion* _next;
263 HeapRegion* _prev;
264 #ifdef ASSERT
265 HeapRegionSetBase* _containing_set;
266 #endif // ASSERT
267 bool _pending_removal;
268
269 // For parallel heapRegion traversal.
270 jint _claimed;
271
272 // We use concurrent marking to determine the amount of live data
273 // in each heap region.
274 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
275 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
276
277 // The calculated GC efficiency of the region.
278 double _gc_efficiency;
279
280 enum YoungType {
281 NotYoung, // a region is not young
282 Young, // a region is young
283 Survivor // a region is young and it contains survivors
284 };
285
286 volatile YoungType _young_type;
287 int _young_index_in_cset;
288 SurvRateGroup* _surv_rate_group;
289 int _age_index;
290
291 // The start of the unmarked area. The unmarked area extends from this
292 // word until the top and/or end of the region, and is the part
293 // of the region for which no marking was done, i.e. objects may
294 // have been allocated in this part since the last mark phase.
295 // "prev" is the top at the start of the last completed marking.
296 // "next" is the top at the start of the in-progress marking (if any.)
297 HeapWord* _prev_top_at_mark_start;
298 HeapWord* _next_top_at_mark_start;
299 // If a collection pause is in progress, this is the top at the start
300 // of that pause.
301
302 void init_top_at_mark_start() {
303 assert(_prev_marked_bytes == 0 &&
304 _next_marked_bytes == 0,
305 "Must be called after zero_marked_bytes.");
306 HeapWord* bot = bottom();
307 _prev_top_at_mark_start = bot;
308 _next_top_at_mark_start = bot;
309 }
310
311 void set_young_type(YoungType new_type) {
312 //assert(_young_type != new_type, "setting the same type" );
313 // TODO: add more assertions here
314 _young_type = new_type;
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 hrs_index,
333 G1BlockOffsetSharedArray* sharedOffsetArray,
334 MemRegion mr);
335
336 static int LogOfHRGrainBytes;
337 static int LogOfHRGrainWords;
338
339 static size_t GrainBytes;
340 static size_t GrainWords;
341 static size_t CardsPerRegion;
342
343 static size_t align_up_to_region_byte_size(size_t sz) {
344 return (sz + (size_t) GrainBytes - 1) &
345 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
346 }
347
348 static size_t max_region_size();
349
350 // It sets up the heap region size (GrainBytes / GrainWords), as
351 // well as other related fields that are based on the heap region
352 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
353 // CardsPerRegion). All those fields are considered constant
354 // throughout the JVM's execution, therefore they should only be set
355 // up once during initialization time.
356 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
357
358 enum ClaimValues {
359 InitialClaimValue = 0,
360 FinalCountClaimValue = 1,
361 NoteEndClaimValue = 2,
362 ScrubRemSetClaimValue = 3,
363 ParVerifyClaimValue = 4,
364 RebuildRSClaimValue = 5,
365 ParEvacFailureClaimValue = 6,
366 AggregateCountClaimValue = 7,
367 VerifyCountClaimValue = 8,
368 ParMarkRootClaimValue = 9
369 };
370
371 // All allocated blocks are occupied by objects in a HeapRegion
372 bool block_is_obj(const HeapWord* p) const;
373
374 // Returns the object size for all valid block starts
375 // and the amount of unallocated words if called on top()
376 size_t block_size(const HeapWord* p) const;
377
378 inline HeapWord* par_allocate_no_bot_updates(size_t word_size);
379 inline HeapWord* allocate_no_bot_updates(size_t word_size);
380
381 // If this region is a member of a HeapRegionSeq, the index in that
382 // sequence, otherwise -1.
383 uint hrs_index() const { return _hrs_index; }
384
385 // The number of bytes marked live in the region in the last marking phase.
386 size_t marked_bytes() { return _prev_marked_bytes; }
387 size_t live_bytes() {
388 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
389 }
390
391 // The number of bytes counted in the next marking.
392 size_t next_marked_bytes() { return _next_marked_bytes; }
393 // The number of bytes live wrt the next marking.
394 size_t next_live_bytes() {
395 return
396 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
397 }
398
399 // A lower bound on the amount of garbage bytes in the region.
400 size_t garbage_bytes() {
401 size_t used_at_mark_start_bytes =
402 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
403 assert(used_at_mark_start_bytes >= marked_bytes(),
404 "Can't mark more than we have.");
405 return used_at_mark_start_bytes - marked_bytes();
406 }
407
408 // Return the amount of bytes we'll reclaim if we collect this
409 // region. This includes not only the known garbage bytes in the
410 // region but also any unallocated space in it, i.e., [top, end),
411 // since it will also be reclaimed if we collect the region.
412 size_t reclaimable_bytes() {
413 size_t known_live_bytes = live_bytes();
414 assert(known_live_bytes <= capacity(), "sanity");
415 return capacity() - known_live_bytes;
416 }
417
418 // An upper bound on the number of live bytes in the region.
419 size_t max_live_bytes() { return used() - garbage_bytes(); }
420
421 void add_to_marked_bytes(size_t incr_bytes) {
422 _next_marked_bytes = _next_marked_bytes + incr_bytes;
423 assert(_next_marked_bytes <= used(), "invariant" );
424 }
425
426 void zero_marked_bytes() {
427 _prev_marked_bytes = _next_marked_bytes = 0;
428 }
429
430 bool isHumongous() const { return _humongous_type != NotHumongous; }
431 bool startsHumongous() const { return _humongous_type == StartsHumongous; }
432 bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; }
433 // For a humongous region, region in which it starts.
434 HeapRegion* humongous_start_region() const {
435 return _humongous_start_region;
436 }
437
438 // Return the number of distinct regions that are covered by this region:
439 // 1 if the region is not humongous, >= 1 if the region is humongous.
440 uint region_num() const {
441 if (!isHumongous()) {
442 return 1U;
443 } else {
444 assert(startsHumongous(), "doesn't make sense on HC regions");
445 assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
446 return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
447 }
448 }
449
450 // Return the index + 1 of the last HC regions that's associated
451 // with this HS region.
452 uint last_hc_index() const {
453 assert(startsHumongous(), "don't call this otherwise");
454 return hrs_index() + region_num();
455 }
456
457 // Same as Space::is_in_reserved, but will use the original size of the region.
458 // The original size is different only for start humongous regions. They get
459 // their _end set up to be the end of the last continues region of the
460 // corresponding humongous object.
461 bool is_in_reserved_raw(const void* p) const {
462 return _bottom <= p && p < _orig_end;
463 }
464
465 // Makes the current region be a "starts humongous" region, i.e.,
466 // the first region in a series of one or more contiguous regions
467 // that will contain a single "humongous" object. The two parameters
468 // are as follows:
469 //
470 // new_top : The new value of the top field of this region which
471 // points to the end of the humongous object that's being
472 // allocated. If there is more than one region in the series, top
473 // will lie beyond this region's original end field and on the last
474 // region in the series.
475 //
476 // new_end : The new value of the end field of this region which
477 // points to the end of the last region in the series. If there is
478 // one region in the series (namely: this one) end will be the same
479 // as the original end of this region.
480 //
481 // Updating top and end as described above makes this region look as
482 // if it spans the entire space taken up by all the regions in the
483 // series and an single allocation moved its top to new_top. This
484 // ensures that the space (capacity / allocated) taken up by all
485 // humongous regions can be calculated by just looking at the
486 // "starts humongous" regions and by ignoring the "continues
487 // humongous" regions.
488 void set_startsHumongous(HeapWord* new_top, HeapWord* new_end);
489
490 // Makes the current region be a "continues humongous'
491 // region. first_hr is the "start humongous" region of the series
492 // which this region will be part of.
493 void set_continuesHumongous(HeapRegion* first_hr);
494
495 // Unsets the humongous-related fields on the region.
496 void set_notHumongous();
497
498 // If the region has a remembered set, return a pointer to it.
499 HeapRegionRemSet* rem_set() const {
500 return _rem_set;
501 }
502
503 // True iff the region is in current collection_set.
504 bool in_collection_set() const {
505 return _in_collection_set;
506 }
507 void set_in_collection_set(bool b) {
508 _in_collection_set = b;
509 }
510 HeapRegion* next_in_collection_set() {
511 assert(in_collection_set(), "should only invoke on member of CS.");
512 assert(_next_in_special_set == NULL ||
513 _next_in_special_set->in_collection_set(),
514 "Malformed CS.");
515 return _next_in_special_set;
516 }
517 void set_next_in_collection_set(HeapRegion* r) {
518 assert(in_collection_set(), "should only invoke on member of CS.");
519 assert(r == NULL || r->in_collection_set(), "Malformed CS.");
520 _next_in_special_set = r;
521 }
522
523 // Methods used by the HeapRegionSetBase class and subclasses.
524
525 // Getter and setter for the next and prev fields used to link regions into
526 // linked lists.
527 HeapRegion* next() { return _next; }
528 HeapRegion* prev() { return _prev; }
529
530 void set_next(HeapRegion* next) { _next = next; }
531 void set_prev(HeapRegion* prev) { _prev = prev; }
532
533 // Every region added to a set is tagged with a reference to that
534 // set. This is used for doing consistency checking to make sure that
535 // the contents of a set are as they should be and it's only
536 // available in non-product builds.
537 #ifdef ASSERT
538 void set_containing_set(HeapRegionSetBase* containing_set) {
539 assert((containing_set == NULL && _containing_set != NULL) ||
540 (containing_set != NULL && _containing_set == NULL),
541 err_msg("containing_set: "PTR_FORMAT" "
542 "_containing_set: "PTR_FORMAT,
543 p2i(containing_set), p2i(_containing_set)));
544
545 _containing_set = containing_set;
546 }
547
548 HeapRegionSetBase* containing_set() { return _containing_set; }
549 #else // ASSERT
550 void set_containing_set(HeapRegionSetBase* containing_set) { }
551
552 // containing_set() is only used in asserts so there's no reason
553 // to provide a dummy version of it.
554 #endif // ASSERT
555
556 // If we want to remove regions from a list in bulk we can simply tag
557 // them with the pending_removal tag and call the
558 // remove_all_pending() method on the list.
559
560 bool pending_removal() { return _pending_removal; }
561
562 void set_pending_removal(bool pending_removal) {
563 if (pending_removal) {
564 assert(!_pending_removal && containing_set() != NULL,
565 "can only set pending removal to true if it's false and "
566 "the region belongs to a region set");
567 } else {
568 assert( _pending_removal && containing_set() == NULL,
569 "can only set pending removal to false if it's true and "
570 "the region does not belong to a region set");
571 }
572
573 _pending_removal = pending_removal;
574 }
575
576 HeapRegion* get_next_young_region() { return _next_young_region; }
577 void set_next_young_region(HeapRegion* hr) {
578 _next_young_region = hr;
579 }
580
581 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
582 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
583 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
584 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
585
586 HeapWord* orig_end() { return _orig_end; }
587
588 // Reset HR stuff to default values.
589 void hr_clear(bool par, bool clear_space, bool locked = false);
590 void par_clear();
591
592 // Get the start of the unmarked area in this region.
593 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
594 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
595
596 // Note the start or end of marking. This tells the heap region
597 // that the collector is about to start or has finished (concurrently)
598 // marking the heap.
599
600 // Notify the region that concurrent marking is starting. Initialize
601 // all fields related to the next marking info.
602 inline void note_start_of_marking();
603
604 // Notify the region that concurrent marking has finished. Copy the
605 // (now finalized) next marking info fields into the prev marking
606 // info fields.
607 inline void note_end_of_marking();
608
609 // Notify the region that it will be used as to-space during a GC
610 // and we are about to start copying objects into it.
611 inline void note_start_of_copying(bool during_initial_mark);
612
613 // Notify the region that it ceases being to-space during a GC and
614 // we will not copy objects into it any more.
615 inline void note_end_of_copying(bool during_initial_mark);
616
617 // Notify the region that we are about to start processing
618 // self-forwarded objects during evac failure handling.
619 void note_self_forwarding_removal_start(bool during_initial_mark,
620 bool during_conc_mark);
621
622 // Notify the region that we have finished processing self-forwarded
623 // objects during evac failure handling.
624 void note_self_forwarding_removal_end(bool during_initial_mark,
625 bool during_conc_mark,
626 size_t marked_bytes);
627
628 // Returns "false" iff no object in the region was allocated when the
629 // last mark phase ended.
630 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
631
632 void reset_during_compaction() {
633 assert(isHumongous() && startsHumongous(),
634 "should only be called for starts humongous regions");
635
636 zero_marked_bytes();
637 init_top_at_mark_start();
638 }
639
640 void calc_gc_efficiency(void);
641 double gc_efficiency() { return _gc_efficiency;}
642
643 bool is_young() const { return _young_type != NotYoung; }
644 bool is_survivor() const { return _young_type == Survivor; }
645
646 int young_index_in_cset() const { return _young_index_in_cset; }
647 void set_young_index_in_cset(int index) {
648 assert( (index == -1) || is_young(), "pre-condition" );
649 _young_index_in_cset = index;
650 }
651
652 int age_in_surv_rate_group() {
653 assert( _surv_rate_group != NULL, "pre-condition" );
654 assert( _age_index > -1, "pre-condition" );
655 return _surv_rate_group->age_in_group(_age_index);
656 }
657
658 void record_surv_words_in_group(size_t words_survived) {
659 assert( _surv_rate_group != NULL, "pre-condition" );
660 assert( _age_index > -1, "pre-condition" );
661 int age_in_group = age_in_surv_rate_group();
662 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
663 }
664
665 int age_in_surv_rate_group_cond() {
666 if (_surv_rate_group != NULL)
667 return age_in_surv_rate_group();
668 else
669 return -1;
670 }
671
672 SurvRateGroup* surv_rate_group() {
673 return _surv_rate_group;
674 }
675
676 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
677 assert( surv_rate_group != NULL, "pre-condition" );
678 assert( _surv_rate_group == NULL, "pre-condition" );
679 assert( is_young(), "pre-condition" );
680
681 _surv_rate_group = surv_rate_group;
682 _age_index = surv_rate_group->next_age_index();
683 }
684
685 void uninstall_surv_rate_group() {
686 if (_surv_rate_group != NULL) {
687 assert( _age_index > -1, "pre-condition" );
688 assert( is_young(), "pre-condition" );
689
690 _surv_rate_group = NULL;
691 _age_index = -1;
692 } else {
693 assert( _age_index == -1, "pre-condition" );
694 }
695 }
696
697 void set_young() { set_young_type(Young); }
698
699 void set_survivor() { set_young_type(Survivor); }
700
701 void set_not_young() { set_young_type(NotYoung); }
702
703 // Determine if an object has been allocated since the last
704 // mark performed by the collector. This returns true iff the object
705 // is within the unmarked area of the region.
706 bool obj_allocated_since_prev_marking(oop obj) const {
707 return (HeapWord *) obj >= prev_top_at_mark_start();
708 }
709 bool obj_allocated_since_next_marking(oop obj) const {
710 return (HeapWord *) obj >= next_top_at_mark_start();
711 }
712
713 // For parallel heapRegion traversal.
714 bool claimHeapRegion(int claimValue);
715 jint claim_value() { return _claimed; }
716 // Use this carefully: only when you're sure no one is claiming...
717 void set_claim_value(int claimValue) { _claimed = claimValue; }
718
719 // Returns the "evacuation_failed" property of the region.
720 bool evacuation_failed() { return _evacuation_failed; }
721
722 // Sets the "evacuation_failed" property of the region.
723 void set_evacuation_failed(bool b) {
724 _evacuation_failed = b;
725
726 if (b) {
727 _next_marked_bytes = 0;
728 }
729 }
730
731 // Requires that "mr" be entirely within the region.
732 // Apply "cl->do_object" to all objects that intersect with "mr".
733 // If the iteration encounters an unparseable portion of the region,
734 // or if "cl->abort()" is true after a closure application,
735 // terminate the iteration and return the address of the start of the
736 // subregion that isn't done. (The two can be distinguished by querying
737 // "cl->abort()".) Return of "NULL" indicates that the iteration
738 // completed.
739 HeapWord*
740 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
741
742 // filter_young: if true and the region is a young region then we
743 // skip the iteration.
744 // card_ptr: if not NULL, and we decide that the card is not young
745 // and we iterate over it, we'll clean the card before we start the
746 // iteration.
747 HeapWord*
748 oops_on_card_seq_iterate_careful(MemRegion mr,
749 FilterOutOfRegionClosure* cl,
750 bool filter_young,
751 jbyte* card_ptr);
752
753 // A version of block start that is guaranteed to find *some* block
754 // boundary at or before "p", but does not object iteration, and may
755 // therefore be used safely when the heap is unparseable.
756 HeapWord* block_start_careful(const void* p) const {
757 return _offsets.block_start_careful(p);
758 }
759
760 // Requires that "addr" is within the region. Returns the start of the
761 // first ("careful") block that starts at or after "addr", or else the
762 // "end" of the region if there is no such block.
763 HeapWord* next_block_start_careful(HeapWord* addr);
764
765 size_t recorded_rs_length() const { return _recorded_rs_length; }
766 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
767 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }
768
769 void set_recorded_rs_length(size_t rs_length) {
770 _recorded_rs_length = rs_length;
771 }
772
773 void set_predicted_elapsed_time_ms(double ms) {
774 _predicted_elapsed_time_ms = ms;
775 }
776
777 void set_predicted_bytes_to_copy(size_t bytes) {
778 _predicted_bytes_to_copy = bytes;
779 }
780
781 virtual CompactibleSpace* next_compaction_space() const;
782
783 virtual void reset_after_compaction();
784
785 // Routines for managing a list of code roots (attached to the
786 // this region's RSet) that point into this heap region.
787 void add_strong_code_root(nmethod* nm);
788 void remove_strong_code_root(nmethod* nm);
789
790 // During a collection, migrate the successfully evacuated
791 // strong code roots that referenced into this region to the
792 // new regions that they now point into. Unsuccessfully
793 // evacuated code roots are not migrated.
794 void migrate_strong_code_roots();
795
796 // Applies blk->do_code_blob() to each of the entries in
797 // the strong code roots list for this region
798 void strong_code_roots_do(CodeBlobClosure* blk) const;
799
800 // Verify that the entries on the strong code root list for this
801 // region are live and include at least one pointer into this region.
802 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
803
804 void print() const;
805 void print_on(outputStream* st) const;
806
807 // vo == UsePrevMarking -> use "prev" marking information,
808 // vo == UseNextMarking -> use "next" marking information
809 // vo == UseMarkWord -> use the mark word in the object header
810 //
811 // NOTE: Only the "prev" marking information is guaranteed to be
812 // consistent most of the time, so most calls to this should use
813 // vo == UsePrevMarking.
814 // Currently, there is only one case where this is called with
815 // vo == UseNextMarking, which is to verify the "next" marking
816 // information at the end of remark.
817 // Currently there is only one place where this is called with
818 // vo == UseMarkWord, which is to verify the marking during a
819 // full GC.
820 void verify(VerifyOption vo, bool *failures) const;
821
822 // Override; it uses the "prev" marking information
823 virtual void verify() const;
824 };
825
826 // HeapRegionClosure is used for iterating over regions.
827 // Terminates the iteration when the "doHeapRegion" method returns "true".
828 class HeapRegionClosure : public StackObj {
829 friend class HeapRegionSeq;
830 friend class G1CollectedHeap;
831
832 bool _complete;
833 void incomplete() { _complete = false; }
834
835 public:
836 HeapRegionClosure(): _complete(true) {}
837
838 // Typically called on each region until it returns true.
839 virtual bool doHeapRegion(HeapRegion* r) = 0;
840
841 // True after iteration if the closure was applied to all heap regions
842 // and returned "false" in all cases.
843 bool complete() { return _complete; }
844 };
845
846 #endif // INCLUDE_ALL_GCS
847
848 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP