1 /*
2 * Copyright (c) 2001, 2021, 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_GC_G1_HEAPREGION_HPP
26 #define SHARE_GC_G1_HEAPREGION_HPP
27
28 #include "gc/g1/g1BlockOffsetTable.hpp"
29 #include "gc/g1/g1HeapRegionTraceType.hpp"
30 #include "gc/g1/g1SurvRateGroup.hpp"
31 #include "gc/g1/heapRegionTracer.hpp"
32 #include "gc/g1/heapRegionType.hpp"
33 #include "gc/shared/ageTable.hpp"
34 #include "gc/shared/spaceDecorator.hpp"
35 #include "gc/shared/verifyOption.hpp"
36 #include "runtime/mutex.hpp"
37 #include "utilities/macros.hpp"
38
39 class G1CollectedHeap;
40 class G1CMBitMap;
41 class G1Predictions;
42 class HeapRegionRemSet;
43 class HeapRegion;
44 class HeapRegionSetBase;
45 class nmethod;
46
47 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
48 #define HR_FORMAT_PARAMS(_hr_) \
49 (_hr_)->hrm_index(), \
50 (_hr_)->get_short_type_str(), \
51 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
52
53 // sentinel value for hrm_index
54 #define G1_NO_HRM_INDEX ((uint) -1)
55
56 // A HeapRegion is the smallest piece of a G1CollectedHeap that
57 // can be collected independently.
58
59 // Each heap region is self contained. top() and end() can never
60 // be set beyond the end of the region. For humongous objects,
61 // the first region is a StartsHumongous region. If the humongous
62 // object is larger than a heap region, the following regions will
63 // be of type ContinuesHumongous. In this case the top() of the
64 // StartHumongous region and all ContinuesHumongous regions except
65 // the last will point to their own end. The last ContinuesHumongous
66 // region may have top() equal the end of object if there isn't
67 // room for filler objects to pad out to the end of the region.
68 class HeapRegion : public CHeapObj<mtGC> {
69 friend class VMStructs;
70
71 HeapWord* const _bottom;
72 HeapWord* const _end;
73
74 HeapWord* volatile _top;
75 HeapWord* _compaction_top;
76
77 G1BlockOffsetTablePart _bot_part;
78 Mutex _par_alloc_lock;
79 // When we need to retire an allocation region, while other threads
80 // are also concurrently trying to allocate into it, we typically
81 // allocate a dummy object at the end of the region to ensure that
82 // no more allocations can take place in it. However, sometimes we
83 // want to know where the end of the last "real" object we allocated
84 // into the region was and this is what this keeps track.
85 HeapWord* _pre_dummy_top;
86
87 public:
88 HeapWord* bottom() const { return _bottom; }
89 HeapWord* end() const { return _end; }
90
91 void set_compaction_top(HeapWord* compaction_top) { _compaction_top = compaction_top; }
92 HeapWord* compaction_top() const { return _compaction_top; }
93
94 void set_top(HeapWord* value) { _top = value; }
95 HeapWord* top() const { return _top; }
96
97 // See the comment above in the declaration of _pre_dummy_top for an
98 // explanation of what it is.
99 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
100 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
101 _pre_dummy_top = pre_dummy_top;
102 }
103 HeapWord* pre_dummy_top() { return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top; }
104 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
105
106 // Returns true iff the given the heap region contains the
107 // given address as part of an allocated object. This may
108 // be a potentially, so we restrict its use to assertion checks only.
109 bool is_in(const void* p) const {
110 return is_in_reserved(p);
111 }
112 bool is_in(oop obj) const {
113 return is_in((void*)obj);
114 }
115 // Returns true iff the given reserved memory of the space contains the
116 // given address.
117 bool is_in_reserved(const void* p) const { return _bottom <= p && p < _end; }
118
119 size_t capacity() const { return byte_size(bottom(), end()); }
120 size_t used() const { return byte_size(bottom(), top()); }
121 size_t free() const { return byte_size(top(), end()); }
122
123 bool is_empty() const { return used() == 0; }
124
125 private:
126 void reset_compaction_top_after_compaction();
127
128 void reset_after_full_gc_common();
129
130 void clear(bool mangle_space);
131
132 HeapWord* block_start_const(const void* p) const;
133
134 void mangle_unused_area() PRODUCT_RETURN;
135
136 // Try to allocate at least min_word_size and up to desired_size from this region.
137 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
138 // space allocated.
139 // This version assumes that all allocation requests to this HeapRegion are properly
140 // synchronized.
141 inline HeapWord* allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
142 // Try to allocate at least min_word_size and up to desired_size from this HeapRegion.
143 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
144 // space allocated.
145 // This version synchronizes with other calls to par_allocate_impl().
146 inline HeapWord* par_allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
147
148 public:
149 HeapWord* block_start(const void* p);
150
151 void object_iterate(ObjectClosure* blk);
152
153 // Allocation (return NULL if full). Assumes the caller has established
154 // mutually exclusive access to the HeapRegion.
155 HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
156 // Allocation (return NULL if full). Enforces mutual exclusion internally.
157 HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
158
159 HeapWord* allocate(size_t word_size);
160 HeapWord* par_allocate(size_t word_size);
161
162 inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
163 inline HeapWord* allocate_no_bot_updates(size_t word_size);
164 inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
165
166 // Full GC support methods.
167
168 HeapWord* initialize_threshold();
169 HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
170
171 // Update heap region that has been compacted to be consistent after Full GC.
172 void reset_compacted_after_full_gc();
173 // Update skip-compacting heap region to be consistent after Full GC.
174 void reset_skip_compacting_after_full_gc();
175
176 // All allocated blocks are occupied by objects in a HeapRegion
177 bool block_is_obj(const HeapWord* p) const;
178
179 // Returns whether the given object is dead based on TAMS and bitmap.
180 // An object is dead iff a) it was not allocated since the last mark (>TAMS), b) it
181 // is not marked (bitmap).
182 bool is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const;
183
184 // Returns the object size for all valid block starts
185 // and the amount of unallocated words if called on top()
186 size_t block_size(const HeapWord* p) const;
187
188 // Scans through the region using the bitmap to determine what
189 // objects to call size_t ApplyToMarkedClosure::apply(oop) for.
190 template<typename ApplyToMarkedClosure>
191 inline void apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure);
192
193 void reset_bot() {
194 _bot_part.reset_bot();
195 }
196
197 void update_bot() {
198 _bot_part.update();
199 }
200
201 private:
202 // The remembered set for this region.
203 HeapRegionRemSet* _rem_set;
204
205 // Cached index of this region in the heap region sequence.
206 const uint _hrm_index;
207
208 HeapRegionType _type;
209
210 // For a humongous region, region in which it starts.
211 HeapRegion* _humongous_start_region;
212
213 static const uint InvalidCSetIndex = UINT_MAX;
214
215 // The index in the optional regions array, if this region
216 // is considered optional during a mixed collections.
217 uint _index_in_opt_cset;
218
219 // Fields used by the HeapRegionSetBase class and subclasses.
220 HeapRegion* _next;
221 HeapRegion* _prev;
222 #ifdef ASSERT
223 HeapRegionSetBase* _containing_set;
224 #endif // ASSERT
225
226 // The start of the unmarked area. The unmarked area extends from this
227 // word until the top and/or end of the region, and is the part
228 // of the region for which no marking was done, i.e. objects may
229 // have been allocated in this part since the last mark phase.
230 // "prev" is the top at the start of the last completed marking.
231 // "next" is the top at the start of the in-progress marking (if any.)
232 HeapWord* _prev_top_at_mark_start;
233 HeapWord* _next_top_at_mark_start;
234
235 // We use concurrent marking to determine the amount of live data
236 // in each heap region.
237 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
238 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
239
240 void init_top_at_mark_start() {
241 assert(_prev_marked_bytes == 0 &&
242 _next_marked_bytes == 0,
243 "Must be called after zero_marked_bytes.");
244 _prev_top_at_mark_start = _next_top_at_mark_start = bottom();
245 }
246
247 // Data for young region survivor prediction.
248 uint _young_index_in_cset;
249 G1SurvRateGroup* _surv_rate_group;
250 int _age_index;
251
252 // Cached attributes used in the collection set policy information
253
254 // The calculated GC efficiency of the region.
255 double _gc_efficiency;
256
257 uint _node_index;
258
259 void report_region_type_change(G1HeapRegionTraceType::Type to);
260
261 // Returns whether the given object address refers to a dead object, and either the
262 // size of the object (if live) or the size of the block (if dead) in size.
263 // May
264 // - only called with obj < top()
265 // - not called on humongous objects or archive regions
266 inline bool is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const;
267
268 // Iterate over the references covered by the given MemRegion in a humongous
269 // object and apply the given closure to them.
270 // Humongous objects are allocated directly in the old-gen. So we need special
271 // handling for concurrent processing encountering an in-progress allocation.
272 // Returns the address after the last actually scanned or NULL if the area could
273 // not be scanned (That should only happen when invoked concurrently with the
274 // mutator).
275 template <class Closure, bool is_gc_active>
276 inline HeapWord* do_oops_on_memregion_in_humongous(MemRegion mr,
277 Closure* cl,
278 G1CollectedHeap* g1h);
279
280 // Returns the block size of the given (dead, potentially having its class unloaded) object
281 // starting at p extending to at most the prev TAMS using the given mark bitmap.
282 inline size_t block_size_using_bitmap(const HeapWord* p, const G1CMBitMap* const prev_bitmap) const;
283 public:
284 HeapRegion(uint hrm_index, G1BlockOffsetTable* bot, MemRegion mr);
285
286 // If this region is a member of a HeapRegionManager, the index in that
287 // sequence, otherwise -1.
288 uint hrm_index() const { return _hrm_index; }
289
290 // Initializing the HeapRegion not only resets the data structure, but also
291 // resets the BOT for that heap region.
292 // The default values for clear_space means that we will do the clearing if
293 // there's clearing to be done ourselves. We also always mangle the space.
294 void initialize(bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
295
296 static int LogOfHRGrainBytes;
297 static int LogCardsPerRegion;
298
299 static size_t GrainBytes;
300 static size_t GrainWords;
301 static size_t CardsPerRegion;
302
303 static size_t align_up_to_region_byte_size(size_t sz) {
304 return (sz + (size_t) GrainBytes - 1) &
305 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
306 }
307
308 // Returns whether a field is in the same region as the obj it points to.
309 template <typename T>
310 static bool is_in_same_region(T* p, oop obj) {
311 assert(p != NULL, "p can't be NULL");
312 assert(obj != NULL, "obj can't be NULL");
313 return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
314 }
315
316 static size_t max_region_size();
317 static size_t min_region_size_in_words();
318
319 // It sets up the heap region size (GrainBytes / GrainWords), as well as
320 // other related fields that are based on the heap region size
321 // (LogOfHRGrainBytes / CardsPerRegion). All those fields are considered
322 // constant throughout the JVM's execution, therefore they should only be set
323 // up once during initialization time.
324 static void setup_heap_region_size(size_t max_heap_size);
325
326 // The number of bytes marked live in the region in the last marking phase.
327 size_t marked_bytes() { return _prev_marked_bytes; }
328 size_t live_bytes() {
329 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
330 }
331
332 // The number of bytes counted in the next marking.
333 size_t next_marked_bytes() { return _next_marked_bytes; }
334 // The number of bytes live wrt the next marking.
335 size_t next_live_bytes() {
336 return
337 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
338 }
339
340 // A lower bound on the amount of garbage bytes in the region.
341 size_t garbage_bytes() {
342 size_t used_at_mark_start_bytes =
343 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
344 return used_at_mark_start_bytes - marked_bytes();
345 }
346
347 // Return the amount of bytes we'll reclaim if we collect this
348 // region. This includes not only the known garbage bytes in the
349 // region but also any unallocated space in it, i.e., [top, end),
350 // since it will also be reclaimed if we collect the region.
351 size_t reclaimable_bytes() {
352 size_t known_live_bytes = live_bytes();
353 assert(known_live_bytes <= capacity(), "sanity");
354 return capacity() - known_live_bytes;
355 }
356
357 // An upper bound on the number of live bytes in the region.
358 size_t max_live_bytes() { return used() - garbage_bytes(); }
359
360 void add_to_marked_bytes(size_t incr_bytes) {
361 _next_marked_bytes = _next_marked_bytes + incr_bytes;
362 }
363
364 void zero_marked_bytes() {
365 _prev_marked_bytes = _next_marked_bytes = 0;
366 }
367 // Get the start of the unmarked area in this region.
368 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
369 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
370
371 // Note the start or end of marking. This tells the heap region
372 // that the collector is about to start or has finished (concurrently)
373 // marking the heap.
374
375 // Notify the region that concurrent marking is starting. Initialize
376 // all fields related to the next marking info.
377 inline void note_start_of_marking();
378
379 // Notify the region that concurrent marking has finished. Copy the
380 // (now finalized) next marking info fields into the prev marking
381 // info fields.
382 inline void note_end_of_marking();
383
384 const char* get_type_str() const { return _type.get_str(); }
385 const char* get_short_type_str() const { return _type.get_short_str(); }
386 G1HeapRegionTraceType::Type get_trace_type() { return _type.get_trace_type(); }
387
388 bool is_free() const { return _type.is_free(); }
389
390 bool is_young() const { return _type.is_young(); }
391 bool is_eden() const { return _type.is_eden(); }
392 bool is_survivor() const { return _type.is_survivor(); }
393
394 bool is_humongous() const { return _type.is_humongous(); }
395 bool is_starts_humongous() const { return _type.is_starts_humongous(); }
396 bool is_continues_humongous() const { return _type.is_continues_humongous(); }
397
398 bool is_old() const { return _type.is_old(); }
399
400 bool is_old_or_humongous() const { return _type.is_old_or_humongous(); }
401
402 bool is_old_or_humongous_or_archive() const { return _type.is_old_or_humongous_or_archive(); }
403
404 // A pinned region contains objects which are not moved by garbage collections.
405 // Humongous regions and archive regions are pinned.
406 bool is_pinned() const { return _type.is_pinned(); }
407
408 // An archive region is a pinned region, also tagged as old, which
409 // should not be marked during mark/sweep. This allows the address
410 // space to be shared by JVM instances.
411 bool is_archive() const { return _type.is_archive(); }
412 bool is_open_archive() const { return _type.is_open_archive(); }
413 bool is_closed_archive() const { return _type.is_closed_archive(); }
414
415 void set_free();
416
417 void set_eden();
418 void set_eden_pre_gc();
419 void set_survivor();
420
421 void move_to_old();
422 void set_old();
423
424 void set_open_archive();
425 void set_closed_archive();
426
427 // For a humongous region, region in which it starts.
428 HeapRegion* humongous_start_region() const {
429 return _humongous_start_region;
430 }
431
432 // Makes the current region be a "starts humongous" region, i.e.,
433 // the first region in a series of one or more contiguous regions
434 // that will contain a single "humongous" object.
435 //
436 // obj_top : points to the top of the humongous object.
437 // fill_size : size of the filler object at the end of the region series.
438 void set_starts_humongous(HeapWord* obj_top, size_t fill_size);
439
440 // Makes the current region be a "continues humongous'
441 // region. first_hr is the "start humongous" region of the series
442 // which this region will be part of.
443 void set_continues_humongous(HeapRegion* first_hr);
444
445 // Unsets the humongous-related fields on the region.
446 void clear_humongous();
447
448 // If the region has a remembered set, return a pointer to it.
449 HeapRegionRemSet* rem_set() const {
450 return _rem_set;
451 }
452
453 inline bool in_collection_set() const;
454
455 // Methods used by the HeapRegionSetBase class and subclasses.
456
457 // Getter and setter for the next and prev fields used to link regions into
458 // linked lists.
459 void set_next(HeapRegion* next) { _next = next; }
460 HeapRegion* next() { return _next; }
461
462 void set_prev(HeapRegion* prev) { _prev = prev; }
463 HeapRegion* prev() { return _prev; }
464
465 void unlink_from_list();
466
467 // Every region added to a set is tagged with a reference to that
468 // set. This is used for doing consistency checking to make sure that
469 // the contents of a set are as they should be and it's only
470 // available in non-product builds.
471 #ifdef ASSERT
472 void set_containing_set(HeapRegionSetBase* containing_set) {
473 assert((containing_set != NULL && _containing_set == NULL) ||
474 containing_set == NULL,
475 "containing_set: " PTR_FORMAT " "
476 "_containing_set: " PTR_FORMAT,
477 p2i(containing_set), p2i(_containing_set));
478
479 _containing_set = containing_set;
480 }
481
482 HeapRegionSetBase* containing_set() { return _containing_set; }
483 #else // ASSERT
484 void set_containing_set(HeapRegionSetBase* containing_set) { }
485
486 // containing_set() is only used in asserts so there's no reason
487 // to provide a dummy version of it.
488 #endif // ASSERT
489
490
491 // Reset the HeapRegion to default values and clear its remembered set.
492 // If clear_space is true, clear the HeapRegion's memory.
493 // Callers must ensure this is not called by multiple threads at the same time.
494 void hr_clear(bool clear_space);
495 // Clear the card table corresponding to this region.
496 void clear_cardtable();
497
498 // Notify the region that we are about to start processing
499 // self-forwarded objects during evac failure handling.
500 void note_self_forwarding_removal_start(bool during_concurrent_start,
501 bool during_conc_mark);
502
503 // Notify the region that we have finished processing self-forwarded
504 // objects during evac failure handling.
505 void note_self_forwarding_removal_end(size_t marked_bytes);
506
507 uint index_in_opt_cset() const {
508 assert(has_index_in_opt_cset(), "Opt cset index not set.");
509 return _index_in_opt_cset;
510 }
511 bool has_index_in_opt_cset() const { return _index_in_opt_cset != InvalidCSetIndex; }
512 void set_index_in_opt_cset(uint index) { _index_in_opt_cset = index; }
513 void clear_index_in_opt_cset() { _index_in_opt_cset = InvalidCSetIndex; }
514
515 void calc_gc_efficiency(void);
516 double gc_efficiency() const { return _gc_efficiency;}
517
518 uint young_index_in_cset() const { return _young_index_in_cset; }
519 void clear_young_index_in_cset() { _young_index_in_cset = 0; }
520 void set_young_index_in_cset(uint index) {
521 assert(index != UINT_MAX, "just checking");
522 assert(index != 0, "just checking");
523 assert(is_young(), "pre-condition");
524 _young_index_in_cset = index;
525 }
526
527 int age_in_surv_rate_group() const;
528 bool has_valid_age_in_surv_rate() const;
529
530 bool has_surv_rate_group() const;
531
532 double surv_rate_prediction(G1Predictions const& predictor) const;
533
534 void install_surv_rate_group(G1SurvRateGroup* surv_rate_group);
535 void uninstall_surv_rate_group();
536
537 void record_surv_words_in_group(size_t words_survived);
538
539 // Determine if an object has been allocated since the last
540 // mark performed by the collector. This returns true iff the object
541 // is within the unmarked area of the region.
542 bool obj_allocated_since_prev_marking(oop obj) const {
543 return cast_from_oop<HeapWord*>(obj) >= prev_top_at_mark_start();
544 }
545 bool obj_allocated_since_next_marking(oop obj) const {
546 return cast_from_oop<HeapWord*>(obj) >= next_top_at_mark_start();
547 }
548
549 // Update the region state after a failed evacuation.
550 void handle_evacuation_failure();
551
552 // Iterate over the objects overlapping the given memory region, applying cl
553 // to all references in the region. This is a helper for
554 // G1RemSet::refine_card*, and is tightly coupled with them.
555 // mr must not be empty. Must be trimmed to the allocated/parseable space in this region.
556 // This region must be old or humongous.
557 // Returns the next unscanned address if the designated objects were successfully
558 // processed, NULL if an unparseable part of the heap was encountered (That should
559 // only happen when invoked concurrently with the mutator).
560 template <bool is_gc_active, class Closure>
561 inline HeapWord* oops_on_memregion_seq_iterate_careful(MemRegion mr, Closure* cl);
562
563 // Routines for managing a list of code roots (attached to the
564 // this region's RSet) that point into this heap region.
565 void add_strong_code_root(nmethod* nm);
566 void add_strong_code_root_locked(nmethod* nm);
567 void remove_strong_code_root(nmethod* nm);
568
569 // Applies blk->do_code_blob() to each of the entries in
570 // the strong code roots list for this region
571 void strong_code_roots_do(CodeBlobClosure* blk) const;
572
573 uint node_index() const { return _node_index; }
574 void set_node_index(uint node_index) { _node_index = node_index; }
575
576 // Verify that the entries on the strong code root list for this
577 // region are live and include at least one pointer into this region.
578 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
579
580 void print() const;
581 void print_on(outputStream* st) const;
582
583 // vo == UsePrevMarking -> use "prev" marking information,
584 // vo == UseNextMarking -> use "next" marking information
585 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
586 //
587 // NOTE: Only the "prev" marking information is guaranteed to be
588 // consistent most of the time, so most calls to this should use
589 // vo == UsePrevMarking.
590 // Currently, there is only one case where this is called with
591 // vo == UseNextMarking, which is to verify the "next" marking
592 // information at the end of remark.
593 // Currently there is only one place where this is called with
594 // vo == UseFullMarking, which is to verify the marking during a
595 // full GC.
596 void verify(VerifyOption vo, bool *failures) const;
597
598 // Verify using the "prev" marking information
599 void verify() const;
600
601 void verify_rem_set(VerifyOption vo, bool *failures) const;
602 void verify_rem_set() const;
603 };
604
605 // HeapRegionClosure is used for iterating over regions.
606 // Terminates the iteration when the "do_heap_region" method returns "true".
607 class HeapRegionClosure : public StackObj {
608 friend class HeapRegionManager;
609 friend class G1CollectionSet;
610 friend class G1CollectionSetCandidates;
611
612 bool _is_complete;
613 void set_incomplete() { _is_complete = false; }
614
615 public:
616 HeapRegionClosure(): _is_complete(true) {}
617
618 // Typically called on each region until it returns true.
619 virtual bool do_heap_region(HeapRegion* r) = 0;
620
621 // True after iteration if the closure was applied to all heap regions
622 // and returned "false" in all cases.
623 bool is_complete() { return _is_complete; }
624 };
625
626 #endif // SHARE_GC_G1_HEAPREGION_HPP
--- EOF ---