Tue, 19 May 2009 04:05:31 -0700
6819065: G1: eliminate high serial card table clearing time
Reviewed-by: iveresov, tonyp
1 /*
2 * Copyright 2001-2009 Sun Microsystems, Inc. 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.
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
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23 */
25 #ifndef SERIALGC
27 // A HeapRegion is the smallest piece of a G1CollectedHeap that
28 // can be collected independently.
30 // NOTE: Although a HeapRegion is a Space, its
31 // Space::initDirtyCardClosure method must not be called.
32 // The problem is that the existence of this method breaks
33 // the independence of barrier sets from remembered sets.
34 // The solution is to remove this method from the definition
35 // of a Space.
37 class CompactibleSpace;
38 class ContiguousSpace;
39 class HeapRegionRemSet;
40 class HeapRegionRemSetIterator;
41 class HeapRegion;
43 // A dirty card to oop closure for heap regions. It
44 // knows how to get the G1 heap and how to use the bitmap
45 // in the concurrent marker used by G1 to filter remembered
46 // sets.
48 class HeapRegionDCTOC : public ContiguousSpaceDCTOC {
49 public:
50 // Specification of possible DirtyCardToOopClosure filtering.
51 enum FilterKind {
52 NoFilterKind,
53 IntoCSFilterKind,
54 OutOfRegionFilterKind
55 };
57 protected:
58 HeapRegion* _hr;
59 FilterKind _fk;
60 G1CollectedHeap* _g1;
62 void walk_mem_region_with_cl(MemRegion mr,
63 HeapWord* bottom, HeapWord* top,
64 OopClosure* cl);
66 // We don't specialize this for FilteringClosure; filtering is handled by
67 // the "FilterKind" mechanism. But we provide this to avoid a compiler
68 // warning.
69 void walk_mem_region_with_cl(MemRegion mr,
70 HeapWord* bottom, HeapWord* top,
71 FilteringClosure* cl) {
72 HeapRegionDCTOC::walk_mem_region_with_cl(mr, bottom, top,
73 (OopClosure*)cl);
74 }
76 // Get the actual top of the area on which the closure will
77 // operate, given where the top is assumed to be (the end of the
78 // memory region passed to do_MemRegion) and where the object
79 // at the top is assumed to start. For example, an object may
80 // start at the top but actually extend past the assumed top,
81 // in which case the top becomes the end of the object.
82 HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj) {
83 return ContiguousSpaceDCTOC::get_actual_top(top, top_obj);
84 }
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 Filtering_DCTOC::walk_mem_region(mr, bottom, top);
94 }
96 public:
97 HeapRegionDCTOC(G1CollectedHeap* g1,
98 HeapRegion* hr, OopClosure* cl,
99 CardTableModRefBS::PrecisionStyle precision,
100 FilterKind fk);
101 };
104 // The complicating factor is that BlockOffsetTable diverged
105 // significantly, and we need functionality that is only in the G1 version.
106 // So I copied that code, which led to an alternate G1 version of
107 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
108 // be reconciled, then G1OffsetTableContigSpace could go away.
110 // The idea behind time stamps is the following. Doing a save_marks on
111 // all regions at every GC pause is time consuming (if I remember
112 // well, 10ms or so). So, we would like to do that only for regions
113 // that are GC alloc regions. To achieve this, we use time
114 // stamps. For every evacuation pause, G1CollectedHeap generates a
115 // unique time stamp (essentially a counter that gets
116 // incremented). Every time we want to call save_marks on a region,
117 // we set the saved_mark_word to top and also copy the current GC
118 // time stamp to the time stamp field of the space. Reading the
119 // saved_mark_word involves checking the time stamp of the
120 // region. If it is the same as the current GC time stamp, then we
121 // can safely read the saved_mark_word field, as it is valid. If the
122 // time stamp of the region is not the same as the current GC time
123 // stamp, then we instead read top, as the saved_mark_word field is
124 // invalid. Time stamps (on the regions and also on the
125 // G1CollectedHeap) are reset at every cleanup (we iterate over
126 // the regions anyway) and at the end of a Full GC. The current scheme
127 // that uses sequential unsigned ints will fail only if we have 4b
128 // evacuation pauses between two cleanups, which is _highly_ unlikely.
130 class G1OffsetTableContigSpace: public ContiguousSpace {
131 friend class VMStructs;
132 protected:
133 G1BlockOffsetArrayContigSpace _offsets;
134 Mutex _par_alloc_lock;
135 volatile unsigned _gc_time_stamp;
137 public:
138 // Constructor. If "is_zeroed" is true, the MemRegion "mr" may be
139 // assumed to contain zeros.
140 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
141 MemRegion mr, bool is_zeroed = false);
143 void set_bottom(HeapWord* value);
144 void set_end(HeapWord* value);
146 virtual HeapWord* saved_mark_word() const;
147 virtual void set_saved_mark();
148 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
150 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
151 virtual void clear(bool mangle_space);
153 HeapWord* block_start(const void* p);
154 HeapWord* block_start_const(const void* p) const;
156 // Add offset table update.
157 virtual HeapWord* allocate(size_t word_size);
158 HeapWord* par_allocate(size_t word_size);
160 // MarkSweep support phase3
161 virtual HeapWord* initialize_threshold();
162 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
164 virtual void print() const;
165 };
167 class HeapRegion: public G1OffsetTableContigSpace {
168 friend class VMStructs;
169 private:
171 enum HumongousType {
172 NotHumongous = 0,
173 StartsHumongous,
174 ContinuesHumongous
175 };
177 // The next filter kind that should be used for a "new_dcto_cl" call with
178 // the "traditional" signature.
179 HeapRegionDCTOC::FilterKind _next_fk;
181 // Requires that the region "mr" be dense with objects, and begin and end
182 // with an object.
183 void oops_in_mr_iterate(MemRegion mr, OopClosure* cl);
185 // The remembered set for this region.
186 // (Might want to make this "inline" later, to avoid some alloc failure
187 // issues.)
188 HeapRegionRemSet* _rem_set;
190 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
192 protected:
193 // If this region is a member of a HeapRegionSeq, the index in that
194 // sequence, otherwise -1.
195 int _hrs_index;
197 HumongousType _humongous_type;
198 // For a humongous region, region in which it starts.
199 HeapRegion* _humongous_start_region;
200 // For the start region of a humongous sequence, it's original end().
201 HeapWord* _orig_end;
203 // True iff the region is in current collection_set.
204 bool _in_collection_set;
206 // True iff the region is on the unclean list, waiting to be zero filled.
207 bool _is_on_unclean_list;
209 // True iff the region is on the free list, ready for allocation.
210 bool _is_on_free_list;
212 // Is this or has it been an allocation region in the current collection
213 // pause.
214 bool _is_gc_alloc_region;
216 // True iff an attempt to evacuate an object in the region failed.
217 bool _evacuation_failed;
219 // A heap region may be a member one of a number of special subsets, each
220 // represented as linked lists through the field below. Currently, these
221 // sets include:
222 // The collection set.
223 // The set of allocation regions used in a collection pause.
224 // Spaces that may contain gray objects.
225 HeapRegion* _next_in_special_set;
227 // next region in the young "generation" region set
228 HeapRegion* _next_young_region;
230 // Next region whose cards need cleaning
231 HeapRegion* _next_dirty_cards_region;
233 // For parallel heapRegion traversal.
234 jint _claimed;
236 // We use concurrent marking to determine the amount of live data
237 // in each heap region.
238 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
239 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
241 // See "sort_index" method. -1 means is not in the array.
242 int _sort_index;
244 // <PREDICTION>
245 double _gc_efficiency;
246 // </PREDICTION>
248 enum YoungType {
249 NotYoung, // a region is not young
250 ScanOnly, // a region is young and scan-only
251 Young, // a region is young
252 Survivor // a region is young and it contains
253 // survivor
254 };
256 YoungType _young_type;
257 int _young_index_in_cset;
258 SurvRateGroup* _surv_rate_group;
259 int _age_index;
261 // The start of the unmarked area. The unmarked area extends from this
262 // word until the top and/or end of the region, and is the part
263 // of the region for which no marking was done, i.e. objects may
264 // have been allocated in this part since the last mark phase.
265 // "prev" is the top at the start of the last completed marking.
266 // "next" is the top at the start of the in-progress marking (if any.)
267 HeapWord* _prev_top_at_mark_start;
268 HeapWord* _next_top_at_mark_start;
269 // If a collection pause is in progress, this is the top at the start
270 // of that pause.
272 // We've counted the marked bytes of objects below here.
273 HeapWord* _top_at_conc_mark_count;
275 void init_top_at_mark_start() {
276 assert(_prev_marked_bytes == 0 &&
277 _next_marked_bytes == 0,
278 "Must be called after zero_marked_bytes.");
279 HeapWord* bot = bottom();
280 _prev_top_at_mark_start = bot;
281 _next_top_at_mark_start = bot;
282 _top_at_conc_mark_count = bot;
283 }
285 jint _zfs; // A member of ZeroFillState. Protected by ZF_lock.
286 Thread* _zero_filler; // If _zfs is ZeroFilling, the thread that (last)
287 // made it so.
289 void set_young_type(YoungType new_type) {
290 //assert(_young_type != new_type, "setting the same type" );
291 // TODO: add more assertions here
292 _young_type = new_type;
293 }
295 public:
296 // If "is_zeroed" is "true", the region "mr" can be assumed to contain zeros.
297 HeapRegion(G1BlockOffsetSharedArray* sharedOffsetArray,
298 MemRegion mr, bool is_zeroed);
300 enum SomePublicConstants {
301 // HeapRegions are GrainBytes-aligned
302 // and have sizes that are multiples of GrainBytes.
303 LogOfHRGrainBytes = 20,
304 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize,
305 GrainBytes = 1 << LogOfHRGrainBytes,
306 GrainWords = 1 <<LogOfHRGrainWords,
307 MaxAge = 2, NoOfAges = MaxAge+1
308 };
310 enum ClaimValues {
311 InitialClaimValue = 0,
312 FinalCountClaimValue = 1,
313 NoteEndClaimValue = 2,
314 ScrubRemSetClaimValue = 3,
315 ParVerifyClaimValue = 4,
316 RebuildRSClaimValue = 5
317 };
319 // Concurrent refinement requires contiguous heap regions (in which TLABs
320 // might be allocated) to be zero-filled. Each region therefore has a
321 // zero-fill-state.
322 enum ZeroFillState {
323 NotZeroFilled,
324 ZeroFilling,
325 ZeroFilled,
326 Allocated
327 };
329 // If this region is a member of a HeapRegionSeq, the index in that
330 // sequence, otherwise -1.
331 int hrs_index() const { return _hrs_index; }
332 void set_hrs_index(int index) { _hrs_index = index; }
334 // The number of bytes marked live in the region in the last marking phase.
335 size_t marked_bytes() { return _prev_marked_bytes; }
336 // The number of bytes counted in the next marking.
337 size_t next_marked_bytes() { return _next_marked_bytes; }
338 // The number of bytes live wrt the next marking.
339 size_t next_live_bytes() {
340 return (top() - next_top_at_mark_start())
341 * HeapWordSize
342 + next_marked_bytes();
343 }
345 // A lower bound on the amount of garbage bytes in the region.
346 size_t garbage_bytes() {
347 size_t used_at_mark_start_bytes =
348 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
349 assert(used_at_mark_start_bytes >= marked_bytes(),
350 "Can't mark more than we have.");
351 return used_at_mark_start_bytes - marked_bytes();
352 }
354 // An upper bound on the number of live bytes in the region.
355 size_t max_live_bytes() { return used() - garbage_bytes(); }
357 void add_to_marked_bytes(size_t incr_bytes) {
358 _next_marked_bytes = _next_marked_bytes + incr_bytes;
359 guarantee( _next_marked_bytes <= used(), "invariant" );
360 }
362 void zero_marked_bytes() {
363 _prev_marked_bytes = _next_marked_bytes = 0;
364 }
366 bool isHumongous() const { return _humongous_type != NotHumongous; }
367 bool startsHumongous() const { return _humongous_type == StartsHumongous; }
368 bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; }
369 // For a humongous region, region in which it starts.
370 HeapRegion* humongous_start_region() const {
371 return _humongous_start_region;
372 }
374 // Causes the current region to represent a humongous object spanning "n"
375 // regions.
376 virtual void set_startsHumongous();
378 // The regions that continue a humongous sequence should be added using
379 // this method, in increasing address order.
380 void set_continuesHumongous(HeapRegion* start);
382 void add_continuingHumongousRegion(HeapRegion* cont);
384 // If the region has a remembered set, return a pointer to it.
385 HeapRegionRemSet* rem_set() const {
386 return _rem_set;
387 }
389 // True iff the region is in current collection_set.
390 bool in_collection_set() const {
391 return _in_collection_set;
392 }
393 void set_in_collection_set(bool b) {
394 _in_collection_set = b;
395 }
396 HeapRegion* next_in_collection_set() {
397 assert(in_collection_set(), "should only invoke on member of CS.");
398 assert(_next_in_special_set == NULL ||
399 _next_in_special_set->in_collection_set(),
400 "Malformed CS.");
401 return _next_in_special_set;
402 }
403 void set_next_in_collection_set(HeapRegion* r) {
404 assert(in_collection_set(), "should only invoke on member of CS.");
405 assert(r == NULL || r->in_collection_set(), "Malformed CS.");
406 _next_in_special_set = r;
407 }
409 // True iff it is or has been an allocation region in the current
410 // collection pause.
411 bool is_gc_alloc_region() const {
412 return _is_gc_alloc_region;
413 }
414 void set_is_gc_alloc_region(bool b) {
415 _is_gc_alloc_region = b;
416 }
417 HeapRegion* next_gc_alloc_region() {
418 assert(is_gc_alloc_region(), "should only invoke on member of CS.");
419 assert(_next_in_special_set == NULL ||
420 _next_in_special_set->is_gc_alloc_region(),
421 "Malformed CS.");
422 return _next_in_special_set;
423 }
424 void set_next_gc_alloc_region(HeapRegion* r) {
425 assert(is_gc_alloc_region(), "should only invoke on member of CS.");
426 assert(r == NULL || r->is_gc_alloc_region(), "Malformed CS.");
427 _next_in_special_set = r;
428 }
430 bool is_on_free_list() {
431 return _is_on_free_list;
432 }
434 void set_on_free_list(bool b) {
435 _is_on_free_list = b;
436 }
438 HeapRegion* next_from_free_list() {
439 assert(is_on_free_list(),
440 "Should only invoke on free space.");
441 assert(_next_in_special_set == NULL ||
442 _next_in_special_set->is_on_free_list(),
443 "Malformed Free List.");
444 return _next_in_special_set;
445 }
447 void set_next_on_free_list(HeapRegion* r) {
448 assert(r == NULL || r->is_on_free_list(), "Malformed free list.");
449 _next_in_special_set = r;
450 }
452 bool is_on_unclean_list() {
453 return _is_on_unclean_list;
454 }
456 void set_on_unclean_list(bool b);
458 HeapRegion* next_from_unclean_list() {
459 assert(is_on_unclean_list(),
460 "Should only invoke on unclean space.");
461 assert(_next_in_special_set == NULL ||
462 _next_in_special_set->is_on_unclean_list(),
463 "Malformed unclean List.");
464 return _next_in_special_set;
465 }
467 void set_next_on_unclean_list(HeapRegion* r);
469 HeapRegion* get_next_young_region() { return _next_young_region; }
470 void set_next_young_region(HeapRegion* hr) {
471 _next_young_region = hr;
472 }
474 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
475 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
476 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
477 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
479 // Allows logical separation between objects allocated before and after.
480 void save_marks();
482 // Reset HR stuff to default values.
483 void hr_clear(bool par, bool clear_space);
485 void initialize(MemRegion mr, bool clear_space, bool mangle_space);
487 // Ensure that "this" is zero-filled.
488 void ensure_zero_filled();
489 // This one requires that the calling thread holds ZF_mon.
490 void ensure_zero_filled_locked();
492 // Get the start of the unmarked area in this region.
493 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
494 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
496 // Apply "cl->do_oop" to (the addresses of) all reference fields in objects
497 // allocated in the current region before the last call to "save_mark".
498 void oop_before_save_marks_iterate(OopClosure* cl);
500 // This call determines the "filter kind" argument that will be used for
501 // the next call to "new_dcto_cl" on this region with the "traditional"
502 // signature (i.e., the call below.) The default, in the absence of a
503 // preceding call to this method, is "NoFilterKind", and a call to this
504 // method is necessary for each such call, or else it reverts to the
505 // default.
506 // (This is really ugly, but all other methods I could think of changed a
507 // lot of main-line code for G1.)
508 void set_next_filter_kind(HeapRegionDCTOC::FilterKind nfk) {
509 _next_fk = nfk;
510 }
512 DirtyCardToOopClosure*
513 new_dcto_closure(OopClosure* cl,
514 CardTableModRefBS::PrecisionStyle precision,
515 HeapRegionDCTOC::FilterKind fk);
517 #if WHASSUP
518 DirtyCardToOopClosure*
519 new_dcto_closure(OopClosure* cl,
520 CardTableModRefBS::PrecisionStyle precision,
521 HeapWord* boundary) {
522 assert(boundary == NULL, "This arg doesn't make sense here.");
523 DirtyCardToOopClosure* res = new_dcto_closure(cl, precision, _next_fk);
524 _next_fk = HeapRegionDCTOC::NoFilterKind;
525 return res;
526 }
527 #endif
529 //
530 // Note the start or end of marking. This tells the heap region
531 // that the collector is about to start or has finished (concurrently)
532 // marking the heap.
533 //
535 // Note the start of a marking phase. Record the
536 // start of the unmarked area of the region here.
537 void note_start_of_marking(bool during_initial_mark) {
538 init_top_at_conc_mark_count();
539 _next_marked_bytes = 0;
540 if (during_initial_mark && is_young() && !is_survivor())
541 _next_top_at_mark_start = bottom();
542 else
543 _next_top_at_mark_start = top();
544 }
546 // Note the end of a marking phase. Install the start of
547 // the unmarked area that was captured at start of marking.
548 void note_end_of_marking() {
549 _prev_top_at_mark_start = _next_top_at_mark_start;
550 _prev_marked_bytes = _next_marked_bytes;
551 _next_marked_bytes = 0;
553 guarantee(_prev_marked_bytes <=
554 (size_t) (prev_top_at_mark_start() - bottom()) * HeapWordSize,
555 "invariant");
556 }
558 // After an evacuation, we need to update _next_top_at_mark_start
559 // to be the current top. Note this is only valid if we have only
560 // ever evacuated into this region. If we evacuate, allocate, and
561 // then evacuate we are in deep doodoo.
562 void note_end_of_copying() {
563 assert(top() >= _next_top_at_mark_start,
564 "Increase only");
565 // Survivor regions will be scanned on the start of concurrent
566 // marking.
567 if (!is_survivor()) {
568 _next_top_at_mark_start = top();
569 }
570 }
572 // Returns "false" iff no object in the region was allocated when the
573 // last mark phase ended.
574 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
576 // If "is_marked()" is true, then this is the index of the region in
577 // an array constructed at the end of marking of the regions in a
578 // "desirability" order.
579 int sort_index() {
580 return _sort_index;
581 }
582 void set_sort_index(int i) {
583 _sort_index = i;
584 }
586 void init_top_at_conc_mark_count() {
587 _top_at_conc_mark_count = bottom();
588 }
590 void set_top_at_conc_mark_count(HeapWord *cur) {
591 assert(bottom() <= cur && cur <= end(), "Sanity.");
592 _top_at_conc_mark_count = cur;
593 }
595 HeapWord* top_at_conc_mark_count() {
596 return _top_at_conc_mark_count;
597 }
599 void reset_during_compaction() {
600 guarantee( isHumongous() && startsHumongous(),
601 "should only be called for humongous regions");
603 zero_marked_bytes();
604 init_top_at_mark_start();
605 }
607 // <PREDICTION>
608 void calc_gc_efficiency(void);
609 double gc_efficiency() { return _gc_efficiency;}
610 // </PREDICTION>
612 bool is_young() const { return _young_type != NotYoung; }
613 bool is_scan_only() const { return _young_type == ScanOnly; }
614 bool is_survivor() const { return _young_type == Survivor; }
616 int young_index_in_cset() const { return _young_index_in_cset; }
617 void set_young_index_in_cset(int index) {
618 assert( (index == -1) || is_young(), "pre-condition" );
619 _young_index_in_cset = index;
620 }
622 int age_in_surv_rate_group() {
623 assert( _surv_rate_group != NULL, "pre-condition" );
624 assert( _age_index > -1, "pre-condition" );
625 return _surv_rate_group->age_in_group(_age_index);
626 }
628 void recalculate_age_in_surv_rate_group() {
629 assert( _surv_rate_group != NULL, "pre-condition" );
630 assert( _age_index > -1, "pre-condition" );
631 _age_index = _surv_rate_group->recalculate_age_index(_age_index);
632 }
634 void record_surv_words_in_group(size_t words_survived) {
635 assert( _surv_rate_group != NULL, "pre-condition" );
636 assert( _age_index > -1, "pre-condition" );
637 int age_in_group = age_in_surv_rate_group();
638 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
639 }
641 int age_in_surv_rate_group_cond() {
642 if (_surv_rate_group != NULL)
643 return age_in_surv_rate_group();
644 else
645 return -1;
646 }
648 SurvRateGroup* surv_rate_group() {
649 return _surv_rate_group;
650 }
652 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
653 assert( surv_rate_group != NULL, "pre-condition" );
654 assert( _surv_rate_group == NULL, "pre-condition" );
655 assert( is_young(), "pre-condition" );
657 _surv_rate_group = surv_rate_group;
658 _age_index = surv_rate_group->next_age_index();
659 }
661 void uninstall_surv_rate_group() {
662 if (_surv_rate_group != NULL) {
663 assert( _age_index > -1, "pre-condition" );
664 assert( is_young(), "pre-condition" );
666 _surv_rate_group = NULL;
667 _age_index = -1;
668 } else {
669 assert( _age_index == -1, "pre-condition" );
670 }
671 }
673 void set_young() { set_young_type(Young); }
675 void set_scan_only() { set_young_type(ScanOnly); }
677 void set_survivor() { set_young_type(Survivor); }
679 void set_not_young() { set_young_type(NotYoung); }
681 // Determine if an object has been allocated since the last
682 // mark performed by the collector. This returns true iff the object
683 // is within the unmarked area of the region.
684 bool obj_allocated_since_prev_marking(oop obj) const {
685 return (HeapWord *) obj >= prev_top_at_mark_start();
686 }
687 bool obj_allocated_since_next_marking(oop obj) const {
688 return (HeapWord *) obj >= next_top_at_mark_start();
689 }
691 // For parallel heapRegion traversal.
692 bool claimHeapRegion(int claimValue);
693 jint claim_value() { return _claimed; }
694 // Use this carefully: only when you're sure no one is claiming...
695 void set_claim_value(int claimValue) { _claimed = claimValue; }
697 // Returns the "evacuation_failed" property of the region.
698 bool evacuation_failed() { return _evacuation_failed; }
700 // Sets the "evacuation_failed" property of the region.
701 void set_evacuation_failed(bool b) {
702 _evacuation_failed = b;
704 if (b) {
705 init_top_at_conc_mark_count();
706 _next_marked_bytes = 0;
707 }
708 }
710 // Requires that "mr" be entirely within the region.
711 // Apply "cl->do_object" to all objects that intersect with "mr".
712 // If the iteration encounters an unparseable portion of the region,
713 // or if "cl->abort()" is true after a closure application,
714 // terminate the iteration and return the address of the start of the
715 // subregion that isn't done. (The two can be distinguished by querying
716 // "cl->abort()".) Return of "NULL" indicates that the iteration
717 // completed.
718 HeapWord*
719 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
721 HeapWord*
722 oops_on_card_seq_iterate_careful(MemRegion mr,
723 FilterOutOfRegionClosure* cl);
725 // The region "mr" is entirely in "this", and starts and ends at block
726 // boundaries. The caller declares that all the contained blocks are
727 // coalesced into one.
728 void declare_filled_region_to_BOT(MemRegion mr) {
729 _offsets.single_block(mr.start(), mr.end());
730 }
732 // A version of block start that is guaranteed to find *some* block
733 // boundary at or before "p", but does not object iteration, and may
734 // therefore be used safely when the heap is unparseable.
735 HeapWord* block_start_careful(const void* p) const {
736 return _offsets.block_start_careful(p);
737 }
739 // Requires that "addr" is within the region. Returns the start of the
740 // first ("careful") block that starts at or after "addr", or else the
741 // "end" of the region if there is no such block.
742 HeapWord* next_block_start_careful(HeapWord* addr);
744 // Returns the zero-fill-state of the current region.
745 ZeroFillState zero_fill_state() { return (ZeroFillState)_zfs; }
746 bool zero_fill_is_allocated() { return _zfs == Allocated; }
747 Thread* zero_filler() { return _zero_filler; }
749 // Indicate that the contents of the region are unknown, and therefore
750 // might require zero-filling.
751 void set_zero_fill_needed() {
752 set_zero_fill_state_work(NotZeroFilled);
753 }
754 void set_zero_fill_in_progress(Thread* t) {
755 set_zero_fill_state_work(ZeroFilling);
756 _zero_filler = t;
757 }
758 void set_zero_fill_complete();
759 void set_zero_fill_allocated() {
760 set_zero_fill_state_work(Allocated);
761 }
763 void set_zero_fill_state_work(ZeroFillState zfs);
765 // This is called when a full collection shrinks the heap.
766 // We want to set the heap region to a value which says
767 // it is no longer part of the heap. For now, we'll let "NotZF" fill
768 // that role.
769 void reset_zero_fill() {
770 set_zero_fill_state_work(NotZeroFilled);
771 _zero_filler = NULL;
772 }
774 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
775 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
776 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DECL)
778 CompactibleSpace* next_compaction_space() const;
780 virtual void reset_after_compaction();
782 void print() const;
783 void print_on(outputStream* st) const;
785 // Override
786 virtual void verify(bool allow_dirty) const;
788 #ifdef DEBUG
789 HeapWord* allocate(size_t size);
790 #endif
791 };
793 // HeapRegionClosure is used for iterating over regions.
794 // Terminates the iteration when the "doHeapRegion" method returns "true".
795 class HeapRegionClosure : public StackObj {
796 friend class HeapRegionSeq;
797 friend class G1CollectedHeap;
799 bool _complete;
800 void incomplete() { _complete = false; }
802 public:
803 HeapRegionClosure(): _complete(true) {}
805 // Typically called on each region until it returns true.
806 virtual bool doHeapRegion(HeapRegion* r) = 0;
808 // True after iteration if the closure was applied to all heap regions
809 // and returned "false" in all cases.
810 bool complete() { return _complete; }
811 };
813 // A linked lists of heap regions. It leaves the "next" field
814 // unspecified; that's up to subtypes.
815 class RegionList VALUE_OBJ_CLASS_SPEC {
816 protected:
817 virtual HeapRegion* get_next(HeapRegion* chr) = 0;
818 virtual void set_next(HeapRegion* chr,
819 HeapRegion* new_next) = 0;
821 HeapRegion* _hd;
822 HeapRegion* _tl;
823 size_t _sz;
825 // Protected constructor because this type is only meaningful
826 // when the _get/_set next functions are defined.
827 RegionList() : _hd(NULL), _tl(NULL), _sz(0) {}
828 public:
829 void reset() {
830 _hd = NULL;
831 _tl = NULL;
832 _sz = 0;
833 }
834 HeapRegion* hd() { return _hd; }
835 HeapRegion* tl() { return _tl; }
836 size_t sz() { return _sz; }
837 size_t length();
839 bool well_formed() {
840 return
841 ((hd() == NULL && tl() == NULL && sz() == 0)
842 || (hd() != NULL && tl() != NULL && sz() > 0))
843 && (sz() == length());
844 }
845 virtual void insert_before_head(HeapRegion* r);
846 void prepend_list(RegionList* new_list);
847 virtual HeapRegion* pop();
848 void dec_sz() { _sz--; }
849 // Requires that "r" is an element of the list, and is not the tail.
850 void delete_after(HeapRegion* r);
851 };
853 class EmptyNonHRegionList: public RegionList {
854 protected:
855 // Protected constructor because this type is only meaningful
856 // when the _get/_set next functions are defined.
857 EmptyNonHRegionList() : RegionList() {}
859 public:
860 void insert_before_head(HeapRegion* r) {
861 // assert(r->is_empty(), "Better be empty");
862 assert(!r->isHumongous(), "Better not be humongous.");
863 RegionList::insert_before_head(r);
864 }
865 void prepend_list(EmptyNonHRegionList* new_list) {
866 // assert(new_list->hd() == NULL || new_list->hd()->is_empty(),
867 // "Better be empty");
868 assert(new_list->hd() == NULL || !new_list->hd()->isHumongous(),
869 "Better not be humongous.");
870 // assert(new_list->tl() == NULL || new_list->tl()->is_empty(),
871 // "Better be empty");
872 assert(new_list->tl() == NULL || !new_list->tl()->isHumongous(),
873 "Better not be humongous.");
874 RegionList::prepend_list(new_list);
875 }
876 };
878 class UncleanRegionList: public EmptyNonHRegionList {
879 public:
880 HeapRegion* get_next(HeapRegion* hr) {
881 return hr->next_from_unclean_list();
882 }
883 void set_next(HeapRegion* hr, HeapRegion* new_next) {
884 hr->set_next_on_unclean_list(new_next);
885 }
887 UncleanRegionList() : EmptyNonHRegionList() {}
889 void insert_before_head(HeapRegion* r) {
890 assert(!r->is_on_free_list(),
891 "Better not already be on free list");
892 assert(!r->is_on_unclean_list(),
893 "Better not already be on unclean list");
894 r->set_zero_fill_needed();
895 r->set_on_unclean_list(true);
896 EmptyNonHRegionList::insert_before_head(r);
897 }
898 void prepend_list(UncleanRegionList* new_list) {
899 assert(new_list->tl() == NULL || !new_list->tl()->is_on_free_list(),
900 "Better not already be on free list");
901 assert(new_list->tl() == NULL || new_list->tl()->is_on_unclean_list(),
902 "Better already be marked as on unclean list");
903 assert(new_list->hd() == NULL || !new_list->hd()->is_on_free_list(),
904 "Better not already be on free list");
905 assert(new_list->hd() == NULL || new_list->hd()->is_on_unclean_list(),
906 "Better already be marked as on unclean list");
907 EmptyNonHRegionList::prepend_list(new_list);
908 }
909 HeapRegion* pop() {
910 HeapRegion* res = RegionList::pop();
911 if (res != NULL) res->set_on_unclean_list(false);
912 return res;
913 }
914 };
916 // Local Variables: ***
917 // c-indentation-style: gnu ***
918 // End: ***
920 #endif // SERIALGC