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/g1HeapRegionTraceType.hpp"
31 #include "gc/g1/heapRegionTracer.hpp"
32 #include "gc/g1/heapRegionType.hpp"
33 #include "gc/g1/survRateGroup.hpp"
34 #include "gc/shared/ageTable.hpp"
35 #include "gc/shared/spaceDecorator.hpp"
36 #include "utilities/macros.hpp"
37
38 // A HeapRegion is the smallest piece of a G1CollectedHeap that
39 // can be collected independently.
40
41 // NOTE: Although a HeapRegion is a Space, its
42 // Space::initDirtyCardClosure method must not be called.
43 // The problem is that the existence of this method breaks
44 // the independence of barrier sets from remembered sets.
45 // The solution is to remove this method from the definition
46 // of a Space.
47
48 // Each heap region is self contained. top() and end() can never
49 // be set beyond the end of the region. For humongous objects,
50 // the first region is a StartsHumongous region. If the humongous
51 // object is larger than a heap region, the following regions will
52 // be of type ContinuesHumongous. In this case the top() of the
53 // StartHumongous region and all ContinuesHumongous regions except
54 // the last will point to their own end. The last ContinuesHumongous
55 // region may have top() equal the end of object if there isn't
56 // room for filler objects to pad out to the end of the region.
57
58 class G1CollectedHeap;
59 class G1CMBitMapRO;
60 class HeapRegionRemSet;
61 class HeapRegionRemSetIterator;
62 class HeapRegion;
63 class HeapRegionSetBase;
64 class nmethod;
65
66 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
67 #define HR_FORMAT_PARAMS(_hr_) \
68 (_hr_)->hrm_index(), \
69 (_hr_)->get_short_type_str(), \
70 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
71
72 // sentinel value for hrm_index
73 #define G1_NO_HRM_INDEX ((uint) -1)
74
75 // The complicating factor is that BlockOffsetTable diverged
76 // significantly, and we need functionality that is only in the G1 version.
77 // So I copied that code, which led to an alternate G1 version of
78 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
79 // be reconciled, then G1OffsetTableContigSpace could go away.
80
81 // The idea behind time stamps is the following. We want to keep track of
82 // the highest address where it's safe to scan objects for each region.
83 // This is only relevant for current GC alloc regions so we keep a time stamp
84 // per region to determine if the region has been allocated during the current
85 // GC or not. If the time stamp is current we report a scan_top value which
86 // was saved at the end of the previous GC for retained alloc regions and which is
87 // equal to the bottom for all other regions.
88 // There is a race between card scanners and allocating gc workers where we must ensure
89 // that card scanners do not read the memory allocated by the gc workers.
90 // In order to enforce that, we must not return a value of _top which is more recent than the
91 // time stamp. This is due to the fact that a region may become a gc alloc region at
92 // some point after we've read the timestamp value as being < the current time stamp.
93 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
94 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
95 // evacuation pauses between two cleanups, which is _highly_ unlikely.
96 class G1ContiguousSpace: public CompactibleSpace {
97 friend class VMStructs;
98 HeapWord* volatile _top;
99 HeapWord* volatile _scan_top;
100 protected:
101 G1BlockOffsetTablePart _bot_part;
102 Mutex _par_alloc_lock;
103 volatile uint _gc_time_stamp;
104 // When we need to retire an allocation region, while other threads
105 // are also concurrently trying to allocate into it, we typically
106 // allocate a dummy object at the end of the region to ensure that
107 // no more allocations can take place in it. However, sometimes we
108 // want to know where the end of the last "real" object we allocated
109 // into the region was and this is what this keeps track.
110 HeapWord* _pre_dummy_top;
111
112 public:
113 G1ContiguousSpace(G1BlockOffsetTable* bot);
114
115 void set_top(HeapWord* value) { _top = value; }
116 HeapWord* top() const { return _top; }
117
118 protected:
119 // Reset the G1ContiguousSpace.
120 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
121
122 HeapWord* volatile* top_addr() { return &_top; }
123 // Try to allocate at least min_word_size and up to desired_size from this Space.
124 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
125 // space allocated.
126 // This version assumes that all allocation requests to this Space are properly
127 // synchronized.
128 inline HeapWord* allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
129 // Try to allocate at least min_word_size and up to desired_size from this Space.
130 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
131 // space allocated.
132 // This version synchronizes with other calls to par_allocate_impl().
133 inline HeapWord* par_allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
134
135 public:
136 void reset_after_compaction() { set_top(compaction_top()); }
137
138 size_t used() const { return byte_size(bottom(), top()); }
139 size_t free() const { return byte_size(top(), end()); }
140 bool is_free_block(const HeapWord* p) const { return p >= top(); }
141
142 MemRegion used_region() const { return MemRegion(bottom(), top()); }
143
144 void object_iterate(ObjectClosure* blk);
145 void safe_object_iterate(ObjectClosure* blk);
146
147 void mangle_unused_area() PRODUCT_RETURN;
148 void mangle_unused_area_complete() PRODUCT_RETURN;
149
150 HeapWord* scan_top() const;
151 void record_timestamp();
152 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
153 uint get_gc_time_stamp() { return _gc_time_stamp; }
154 void record_retained_region();
155
156 // See the comment above in the declaration of _pre_dummy_top for an
157 // explanation of what it is.
158 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
159 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
160 _pre_dummy_top = pre_dummy_top;
161 }
162 HeapWord* pre_dummy_top() {
163 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
164 }
165 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
166
167 virtual void clear(bool mangle_space);
168
169 HeapWord* block_start(const void* p);
170 HeapWord* block_start_const(const void* p) const;
171
172 // Allocation (return NULL if full). Assumes the caller has established
173 // mutually exclusive access to the space.
174 HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
175 // Allocation (return NULL if full). Enforces mutual exclusion internally.
176 HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
177
178 virtual HeapWord* allocate(size_t word_size);
179 virtual HeapWord* par_allocate(size_t word_size);
180
181 HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
182
183 // MarkSweep support phase3
184 virtual HeapWord* initialize_threshold();
185 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
186
187 virtual void print() const;
188
189 void reset_bot() {
190 _bot_part.reset_bot();
191 }
192
193 void print_bot_on(outputStream* out) {
194 _bot_part.print_on(out);
195 }
196 };
197
198 class HeapRegion: public G1ContiguousSpace {
199 friend class VMStructs;
200 // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
201 template <typename SpaceType>
202 friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
203 private:
204
205 // The remembered set for this region.
206 // (Might want to make this "inline" later, to avoid some alloc failure
207 // issues.)
208 HeapRegionRemSet* _rem_set;
209
210 // Auxiliary functions for scan_and_forward support.
211 // See comments for CompactibleSpace for more information.
212 inline HeapWord* scan_limit() const {
213 return top();
214 }
215
216 inline bool scanned_block_is_obj(const HeapWord* addr) const {
217 return true; // Always true, since scan_limit is top
218 }
219
220 inline size_t scanned_block_size(const HeapWord* addr) const {
221 return HeapRegion::block_size(addr); // Avoid virtual call
222 }
223
224 void report_region_type_change(G1HeapRegionTraceType::Type to);
225
226 // Returns whether the given object address refers to a dead object, and either the
227 // size of the object (if live) or the size of the block (if dead) in size.
228 // Performs some optimizations if is_gc_active is set.
229 template <bool is_gc_active>
230 inline bool is_obj_dead_with_size(const oop obj, G1CMBitMapRO* bitmap, size_t* size) const;
231
232 protected:
233 // The index of this region in the heap region sequence.
234 uint _hrm_index;
235
236 AllocationContext_t _allocation_context;
237
238 HeapRegionType _type;
239
240 // For a humongous region, region in which it starts.
241 HeapRegion* _humongous_start_region;
242
243 // True iff an attempt to evacuate an object in the region failed.
244 bool _evacuation_failed;
245
246 // Fields used by the HeapRegionSetBase class and subclasses.
247 HeapRegion* _next;
248 HeapRegion* _prev;
249 #ifdef ASSERT
250 HeapRegionSetBase* _containing_set;
251 #endif // ASSERT
252
253 // We use concurrent marking to determine the amount of live data
254 // in each heap region.
255 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
256 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
257
258 // The calculated GC efficiency of the region.
259 double _gc_efficiency;
260
261 int _young_index_in_cset;
262 SurvRateGroup* _surv_rate_group;
263 int _age_index;
264
265 // The start of the unmarked area. The unmarked area extends from this
266 // word until the top and/or end of the region, and is the part
267 // of the region for which no marking was done, i.e. objects may
268 // have been allocated in this part since the last mark phase.
269 // "prev" is the top at the start of the last completed marking.
270 // "next" is the top at the start of the in-progress marking (if any.)
271 HeapWord* _prev_top_at_mark_start;
272 HeapWord* _next_top_at_mark_start;
273 // If a collection pause is in progress, this is the top at the start
274 // of that pause.
275
276 void init_top_at_mark_start() {
277 assert(_prev_marked_bytes == 0 &&
278 _next_marked_bytes == 0,
279 "Must be called after zero_marked_bytes.");
280 HeapWord* bot = bottom();
281 _prev_top_at_mark_start = bot;
282 _next_top_at_mark_start = bot;
283 }
284
285 // Cached attributes used in the collection set policy information
286
287 // The RSet length that was added to the total value
288 // for the collection set.
289 size_t _recorded_rs_length;
290
291 // The predicted elapsed time that was added to total value
292 // for the collection set.
293 double _predicted_elapsed_time_ms;
294
295 // Iterate over the references in a humongous objects and apply the given closure
296 // to them.
297 // Humongous objects are allocated directly in the old-gen. So we need special
298 // handling for concurrent processing encountering an in-progress allocation.
299 template <class Closure, bool is_gc_active>
300 inline bool do_oops_on_card_in_humongous(MemRegion mr,
301 Closure* cl,
302 G1CollectedHeap* g1h);
303
304 // Returns the block size of the given (dead, potentially having its class unloaded) object
305 // starting at p extending to at most the prev TAMS using the given mark bitmap.
306 inline size_t block_size_using_bitmap(const HeapWord* p, const G1CMBitMapRO* bitmap) const;
307 public:
308 HeapRegion(uint hrm_index,
309 G1BlockOffsetTable* bot,
310 MemRegion mr);
311
312 // Initializing the HeapRegion not only resets the data structure, but also
313 // resets the BOT for that heap region.
314 // The default values for clear_space means that we will do the clearing if
315 // there's clearing to be done ourselves. We also always mangle the space.
316 virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
317
318 static int LogOfHRGrainBytes;
319 static int LogOfHRGrainWords;
320
321 static size_t GrainBytes;
322 static size_t GrainWords;
323 static size_t CardsPerRegion;
324
325 static size_t align_up_to_region_byte_size(size_t sz) {
326 return (sz + (size_t) GrainBytes - 1) &
327 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
328 }
329
330
331 // Returns whether a field is in the same region as the obj it points to.
332 template <typename T>
333 static bool is_in_same_region(T* p, oop obj) {
334 assert(p != NULL, "p can't be NULL");
335 assert(obj != NULL, "obj can't be NULL");
336 return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
337 }
338
339 static size_t max_region_size();
340 static size_t min_region_size_in_words();
341
342 // It sets up the heap region size (GrainBytes / GrainWords), as
343 // well as other related fields that are based on the heap region
344 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
345 // CardsPerRegion). All those fields are considered constant
346 // throughout the JVM's execution, therefore they should only be set
347 // up once during initialization time.
348 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
349
350 // All allocated blocks are occupied by objects in a HeapRegion
351 bool block_is_obj(const HeapWord* p) const;
352
353 // Returns the object size for valid block starts for potentially unloaded dead
354 // objects. Must only be called during scanning cards during GC. Expects the
355 // following preconditions:
356 // - only called on p < top()
357 // - not called on humongous objects or archive regions
358 size_t block_size_during_gc(const HeapWord* p, const G1CMBitMapRO* bitmap) const;
359
360 // Returns the object size for all valid block starts
361 // and the amount of unallocated words if called on top()
362 size_t block_size(const HeapWord* p) const;
363
364 // Override for scan_and_forward support.
365 void prepare_for_compaction(CompactPoint* cp);
366
367 inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
368 inline HeapWord* allocate_no_bot_updates(size_t word_size);
369 inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
370
371 // If this region is a member of a HeapRegionManager, the index in that
372 // sequence, otherwise -1.
373 uint hrm_index() const { return _hrm_index; }
374
375 // The number of bytes marked live in the region in the last marking phase.
376 size_t marked_bytes() { return _prev_marked_bytes; }
377 size_t live_bytes() {
378 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
379 }
380
381 // The number of bytes counted in the next marking.
382 size_t next_marked_bytes() { return _next_marked_bytes; }
383 // The number of bytes live wrt the next marking.
384 size_t next_live_bytes() {
385 return
386 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
387 }
388
389 // A lower bound on the amount of garbage bytes in the region.
390 size_t garbage_bytes() {
391 size_t used_at_mark_start_bytes =
392 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
393 return used_at_mark_start_bytes - marked_bytes();
394 }
395
396 // Return the amount of bytes we'll reclaim if we collect this
397 // region. This includes not only the known garbage bytes in the
398 // region but also any unallocated space in it, i.e., [top, end),
399 // since it will also be reclaimed if we collect the region.
400 size_t reclaimable_bytes() {
401 size_t known_live_bytes = live_bytes();
402 assert(known_live_bytes <= capacity(), "sanity");
403 return capacity() - known_live_bytes;
404 }
405
406 // An upper bound on the number of live bytes in the region.
407 size_t max_live_bytes() { return used() - garbage_bytes(); }
408
409 void add_to_marked_bytes(size_t incr_bytes) {
410 _next_marked_bytes = _next_marked_bytes + incr_bytes;
411 }
412
413 void zero_marked_bytes() {
414 _prev_marked_bytes = _next_marked_bytes = 0;
415 }
416
417 const char* get_type_str() const { return _type.get_str(); }
418 const char* get_short_type_str() const { return _type.get_short_str(); }
419 G1HeapRegionTraceType::Type get_trace_type() { return _type.get_trace_type(); }
420
421 bool is_free() const { return _type.is_free(); }
422
423 bool is_young() const { return _type.is_young(); }
424 bool is_eden() const { return _type.is_eden(); }
425 bool is_survivor() const { return _type.is_survivor(); }
426
427 bool is_humongous() const { return _type.is_humongous(); }
428 bool is_starts_humongous() const { return _type.is_starts_humongous(); }
429 bool is_continues_humongous() const { return _type.is_continues_humongous(); }
430
431 bool is_old() const { return _type.is_old(); }
432
433 bool is_old_or_humongous() const { return _type.is_old_or_humongous(); }
434
435 // A pinned region contains objects which are not moved by garbage collections.
436 // Humongous regions and archive regions are pinned.
437 bool is_pinned() const { return _type.is_pinned(); }
438
439 // An archive region is a pinned region, also tagged as old, which
440 // should not be marked during mark/sweep. This allows the address
441 // space to be shared by JVM instances.
442 bool is_archive() const { return _type.is_archive(); }
443
444 // For a humongous region, region in which it starts.
445 HeapRegion* humongous_start_region() const {
446 return _humongous_start_region;
447 }
448
449 // Makes the current region be a "starts humongous" region, i.e.,
450 // the first region in a series of one or more contiguous regions
451 // that will contain a single "humongous" object.
452 //
453 // obj_top : points to the top of the humongous object.
454 // fill_size : size of the filler object at the end of the region series.
455 void set_starts_humongous(HeapWord* obj_top, size_t fill_size);
456
457 // Makes the current region be a "continues humongous'
458 // region. first_hr is the "start humongous" region of the series
459 // which this region will be part of.
460 void set_continues_humongous(HeapRegion* first_hr);
461
462 // Unsets the humongous-related fields on the region.
463 void clear_humongous();
464
465 // If the region has a remembered set, return a pointer to it.
466 HeapRegionRemSet* rem_set() const {
467 return _rem_set;
468 }
469
470 inline bool in_collection_set() const;
471
472 void set_allocation_context(AllocationContext_t context) {
473 _allocation_context = context;
474 }
475
476 AllocationContext_t allocation_context() const {
477 return _allocation_context;
478 }
479
480 // Methods used by the HeapRegionSetBase class and subclasses.
481
482 // Getter and setter for the next and prev fields used to link regions into
483 // linked lists.
484 HeapRegion* next() { return _next; }
485 HeapRegion* prev() { return _prev; }
486
487 void set_next(HeapRegion* next) { _next = next; }
488 void set_prev(HeapRegion* prev) { _prev = prev; }
489
490 // Every region added to a set is tagged with a reference to that
491 // set. This is used for doing consistency checking to make sure that
492 // the contents of a set are as they should be and it's only
493 // available in non-product builds.
494 #ifdef ASSERT
495 void set_containing_set(HeapRegionSetBase* containing_set) {
496 assert((containing_set == NULL && _containing_set != NULL) ||
497 (containing_set != NULL && _containing_set == NULL),
498 "containing_set: " PTR_FORMAT " "
499 "_containing_set: " PTR_FORMAT,
500 p2i(containing_set), p2i(_containing_set));
501
502 _containing_set = containing_set;
503 }
504
505 HeapRegionSetBase* containing_set() { return _containing_set; }
506 #else // ASSERT
507 void set_containing_set(HeapRegionSetBase* containing_set) { }
508
509 // containing_set() is only used in asserts so there's no reason
510 // to provide a dummy version of it.
511 #endif // ASSERT
512
513
514 // Reset the HeapRegion to default values.
515 // If skip_remset is true, do not clear the remembered set.
516 void hr_clear(bool skip_remset, bool clear_space, bool locked = false);
517 // Clear the parts skipped by skip_remset in hr_clear() in the HeapRegion during
518 // a concurrent phase.
519 void par_clear();
520
521 // Get the start of the unmarked area in this region.
522 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
523 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
524
525 // Note the start or end of marking. This tells the heap region
526 // that the collector is about to start or has finished (concurrently)
527 // marking the heap.
528
529 // Notify the region that concurrent marking is starting. Initialize
530 // all fields related to the next marking info.
531 inline void note_start_of_marking();
532
533 // Notify the region that concurrent marking has finished. Copy the
534 // (now finalized) next marking info fields into the prev marking
535 // info fields.
536 inline void note_end_of_marking();
537
538 // Notify the region that it will be used as to-space during a GC
539 // and we are about to start copying objects into it.
540 inline void note_start_of_copying(bool during_initial_mark);
541
542 // Notify the region that it ceases being to-space during a GC and
543 // we will not copy objects into it any more.
544 inline void note_end_of_copying(bool during_initial_mark);
545
546 // Notify the region that we are about to start processing
547 // self-forwarded objects during evac failure handling.
548 void note_self_forwarding_removal_start(bool during_initial_mark,
549 bool during_conc_mark);
550
551 // Notify the region that we have finished processing self-forwarded
552 // objects during evac failure handling.
553 void note_self_forwarding_removal_end(size_t marked_bytes);
554
555 // Returns "false" iff no object in the region was allocated when the
556 // last mark phase ended.
557 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
558
559 void reset_during_compaction() {
560 assert(is_humongous(),
561 "should only be called for humongous regions");
562
563 zero_marked_bytes();
564 init_top_at_mark_start();
565 }
566
567 void calc_gc_efficiency(void);
568 double gc_efficiency() { return _gc_efficiency;}
569
570 int young_index_in_cset() const { return _young_index_in_cset; }
571 void set_young_index_in_cset(int index) {
572 assert( (index == -1) || is_young(), "pre-condition" );
573 _young_index_in_cset = index;
574 }
575
576 int age_in_surv_rate_group() {
577 assert( _surv_rate_group != NULL, "pre-condition" );
578 assert( _age_index > -1, "pre-condition" );
579 return _surv_rate_group->age_in_group(_age_index);
580 }
581
582 void record_surv_words_in_group(size_t words_survived) {
583 assert( _surv_rate_group != NULL, "pre-condition" );
584 assert( _age_index > -1, "pre-condition" );
585 int age_in_group = age_in_surv_rate_group();
586 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
587 }
588
589 int age_in_surv_rate_group_cond() {
590 if (_surv_rate_group != NULL)
591 return age_in_surv_rate_group();
592 else
593 return -1;
594 }
595
596 SurvRateGroup* surv_rate_group() {
597 return _surv_rate_group;
598 }
599
600 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
601 assert( surv_rate_group != NULL, "pre-condition" );
602 assert( _surv_rate_group == NULL, "pre-condition" );
603 assert( is_young(), "pre-condition" );
604
605 _surv_rate_group = surv_rate_group;
606 _age_index = surv_rate_group->next_age_index();
607 }
608
609 void uninstall_surv_rate_group() {
610 if (_surv_rate_group != NULL) {
611 assert( _age_index > -1, "pre-condition" );
612 assert( is_young(), "pre-condition" );
613
614 _surv_rate_group = NULL;
615 _age_index = -1;
616 } else {
617 assert( _age_index == -1, "pre-condition" );
618 }
619 }
620
621 void set_free();
622
623 void set_eden();
624 void set_eden_pre_gc();
625 void set_survivor();
626
627 void set_old();
628
629 void set_archive();
630
631 // Determine if an object has been allocated since the last
632 // mark performed by the collector. This returns true iff the object
633 // is within the unmarked area of the region.
634 bool obj_allocated_since_prev_marking(oop obj) const {
635 return (HeapWord *) obj >= prev_top_at_mark_start();
636 }
637 bool obj_allocated_since_next_marking(oop obj) const {
638 return (HeapWord *) obj >= next_top_at_mark_start();
639 }
640
641 // Returns the "evacuation_failed" property of the region.
642 bool evacuation_failed() { return _evacuation_failed; }
643
644 // Sets the "evacuation_failed" property of the region.
645 void set_evacuation_failed(bool b) {
646 _evacuation_failed = b;
647
648 if (b) {
649 _next_marked_bytes = 0;
650 }
651 }
652
653 // Iterate over the objects overlapping part of a card, applying cl
654 // to all references in the region. This is a helper for
655 // G1RemSet::refine_card, and is tightly coupled with it.
656 // mr: the memory region covered by the card, trimmed to the
657 // allocated space for this region. Must not be empty.
658 // This region must be old or humongous.
659 // Returns true if the designated objects were successfully
660 // processed, false if an unparsable part of the heap was
661 // encountered; that only happens when invoked concurrently with the
662 // mutator.
663 template <bool is_gc_active, class Closure>
664 inline bool oops_on_card_seq_iterate_careful(MemRegion mr, Closure* cl);
665
666 size_t recorded_rs_length() const { return _recorded_rs_length; }
667 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
668
669 void set_recorded_rs_length(size_t rs_length) {
670 _recorded_rs_length = rs_length;
671 }
672
673 void set_predicted_elapsed_time_ms(double ms) {
674 _predicted_elapsed_time_ms = ms;
675 }
676
677 virtual CompactibleSpace* next_compaction_space() const;
678
679 virtual void reset_after_compaction();
680
681 // Routines for managing a list of code roots (attached to the
682 // this region's RSet) that point into this heap region.
683 void add_strong_code_root(nmethod* nm);
684 void add_strong_code_root_locked(nmethod* nm);
685 void remove_strong_code_root(nmethod* nm);
686
687 // Applies blk->do_code_blob() to each of the entries in
688 // the strong code roots list for this region
689 void strong_code_roots_do(CodeBlobClosure* blk) const;
690
691 // Verify that the entries on the strong code root list for this
692 // region are live and include at least one pointer into this region.
693 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
694
695 void print() const;
696 void print_on(outputStream* st) const;
697
698 // vo == UsePrevMarking -> use "prev" marking information,
699 // vo == UseNextMarking -> use "next" marking information
700 // vo == UseMarkWord -> use the mark word in the object header
701 //
702 // NOTE: Only the "prev" marking information is guaranteed to be
703 // consistent most of the time, so most calls to this should use
704 // vo == UsePrevMarking.
705 // Currently, there is only one case where this is called with
706 // vo == UseNextMarking, which is to verify the "next" marking
707 // information at the end of remark.
708 // Currently there is only one place where this is called with
709 // vo == UseMarkWord, which is to verify the marking during a
710 // full GC.
711 void verify(VerifyOption vo, bool *failures) const;
712
713 // Override; it uses the "prev" marking information
714 virtual void verify() const;
715
716 void verify_rem_set(VerifyOption vo, bool *failures) const;
717 void verify_rem_set() const;
718 };
719
720 // HeapRegionClosure is used for iterating over regions.
721 // Terminates the iteration when the "doHeapRegion" method returns "true".
722 class HeapRegionClosure : public StackObj {
723 friend class HeapRegionManager;
724 friend class G1CollectionSet;
725
726 bool _complete;
727 void incomplete() { _complete = false; }
728
729 public:
730 HeapRegionClosure(): _complete(true) {}
731
732 // Typically called on each region until it returns true.
733 virtual bool doHeapRegion(HeapRegion* r) = 0;
734
735 // True after iteration if the closure was applied to all heap regions
736 // and returned "false" in all cases.
737 bool complete() { return _complete; }
738 };
739
740 #endif // SHARE_VM_GC_G1_HEAPREGION_HPP