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 G1CMBitMap;
60 class G1IsAliveAndApplyClosure;
61 class HeapRegionRemSet;
62 class HeapRegionRemSetIterator;
63 class HeapRegion;
64 class HeapRegionSetBase;
65 class nmethod;
66
67 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
68 #define HR_FORMAT_PARAMS(_hr_) \
69 (_hr_)->hrm_index(), \
70 (_hr_)->get_short_type_str(), \
71 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
72
73 // sentinel value for hrm_index
74 #define G1_NO_HRM_INDEX ((uint) -1)
75
76 // The complicating factor is that BlockOffsetTable diverged
77 // significantly, and we need functionality that is only in the G1 version.
78 // So I copied that code, which led to an alternate G1 version of
79 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
80 // be reconciled, then G1OffsetTableContigSpace could go away.
81
82 // The idea behind time stamps is the following. We want to keep track of
83 // the highest address where it's safe to scan objects for each region.
84 // This is only relevant for current GC alloc regions so we keep a time stamp
85 // per region to determine if the region has been allocated during the current
86 // GC or not. If the time stamp is current we report a scan_top value which
87 // was saved at the end of the previous GC for retained alloc regions and which is
88 // equal to the bottom for all other regions.
89 // There is a race between card scanners and allocating gc workers where we must ensure
90 // that card scanners do not read the memory allocated by the gc workers.
91 // In order to enforce that, we must not return a value of _top which is more recent than the
92 // time stamp. This is due to the fact that a region may become a gc alloc region at
93 // some point after we've read the timestamp value as being < the current time stamp.
94 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
95 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
96 // evacuation pauses between two cleanups, which is _highly_ unlikely.
97 class G1ContiguousSpace: public CompactibleSpace {
98 friend class VMStructs;
99 HeapWord* volatile _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 void record_timestamp();
151 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
152 uint get_gc_time_stamp() { return _gc_time_stamp; }
153
154 // See the comment above in the declaration of _pre_dummy_top for an
155 // explanation of what it is.
156 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
157 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
158 _pre_dummy_top = pre_dummy_top;
159 }
160 HeapWord* pre_dummy_top() {
161 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
162 }
163 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
164
165 virtual void clear(bool mangle_space);
166
167 HeapWord* block_start(const void* p);
168 HeapWord* block_start_const(const void* p) const;
169
170 // Allocation (return NULL if full). Assumes the caller has established
171 // mutually exclusive access to the space.
172 HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
173 // Allocation (return NULL if full). Enforces mutual exclusion internally.
174 HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
175
176 virtual HeapWord* allocate(size_t word_size);
177 virtual HeapWord* par_allocate(size_t word_size);
178
179 HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
180
181 // MarkSweep support phase3
182 virtual HeapWord* initialize_threshold();
183 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
184
185 virtual void print() const;
186
187 void reset_bot() {
188 _bot_part.reset_bot();
189 }
190
191 void print_bot_on(outputStream* out) {
192 _bot_part.print_on(out);
193 }
194 };
195
196 class HeapRegion: public G1ContiguousSpace {
197 friend class VMStructs;
198 // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
199 template <typename SpaceType>
200 friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
201 private:
202
203 // The remembered set for this region.
204 // (Might want to make this "inline" later, to avoid some alloc failure
205 // issues.)
206 HeapRegionRemSet* _rem_set;
207
208 // Auxiliary functions for scan_and_forward support.
209 // See comments for CompactibleSpace for more information.
210 inline HeapWord* scan_limit() const {
211 return top();
212 }
213
214 inline bool scanned_block_is_obj(const HeapWord* addr) const {
215 return true; // Always true, since scan_limit is top
216 }
217
218 inline size_t scanned_block_size(const HeapWord* addr) const {
219 return HeapRegion::block_size(addr); // Avoid virtual call
220 }
221
222 void report_region_type_change(G1HeapRegionTraceType::Type to);
223
224 // Returns whether the given object address refers to a dead object, and either the
225 // size of the object (if live) or the size of the block (if dead) in size.
226 // May
227 // - only called with obj < top()
228 // - not called on humongous objects or archive regions
229 inline bool is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const;
230
231 protected:
232 // The index of this region in the heap region sequence.
233 uint _hrm_index;
234
235 AllocationContext_t _allocation_context;
236
237 HeapRegionType _type;
238
239 // For a humongous region, region in which it starts.
240 HeapRegion* _humongous_start_region;
241
242 // True iff an attempt to evacuate an object in the region failed.
243 bool _evacuation_failed;
244
245 // Fields used by the HeapRegionSetBase class and subclasses.
246 HeapRegion* _next;
247 HeapRegion* _prev;
248 #ifdef ASSERT
249 HeapRegionSetBase* _containing_set;
250 #endif // ASSERT
251
252 // We use concurrent marking to determine the amount of live data
253 // in each heap region.
254 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
255 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
256
257 // The calculated GC efficiency of the region.
258 double _gc_efficiency;
259
260 int _young_index_in_cset;
261 SurvRateGroup* _surv_rate_group;
262 int _age_index;
263
264 // The start of the unmarked area. The unmarked area extends from this
265 // word until the top and/or end of the region, and is the part
266 // of the region for which no marking was done, i.e. objects may
267 // have been allocated in this part since the last mark phase.
268 // "prev" is the top at the start of the last completed marking.
269 // "next" is the top at the start of the in-progress marking (if any.)
270 HeapWord* _prev_top_at_mark_start;
271 HeapWord* _next_top_at_mark_start;
272 // If a collection pause is in progress, this is the top at the start
273 // of that pause.
274
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 }
283
284 // Cached attributes used in the collection set policy information
285
286 // The RSet length that was added to the total value
287 // for the collection set.
288 size_t _recorded_rs_length;
289
290 // The predicted elapsed time that was added to total value
291 // for the collection set.
292 double _predicted_elapsed_time_ms;
293
294 // Iterate over the references in a humongous objects and apply the given closure
295 // to them.
296 // Humongous objects are allocated directly in the old-gen. So we need special
297 // handling for concurrent processing encountering an in-progress allocation.
298 template <class Closure, bool is_gc_active>
299 inline bool do_oops_on_card_in_humongous(MemRegion mr,
300 Closure* cl,
301 G1CollectedHeap* g1h);
302
303 // Returns the block size of the given (dead, potentially having its class unloaded) object
304 // starting at p extending to at most the prev TAMS using the given mark bitmap.
305 inline size_t block_size_using_bitmap(const HeapWord* p, const G1CMBitMap* const prev_bitmap) const;
306 public:
307 HeapRegion(uint hrm_index,
308 G1BlockOffsetTable* bot,
309 MemRegion mr);
310
311 // Initializing the HeapRegion not only resets the data structure, but also
312 // resets the BOT for that heap region.
313 // The default values for clear_space means that we will do the clearing if
314 // there's clearing to be done ourselves. We also always mangle the space.
315 virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
316
317 static int LogOfHRGrainBytes;
318 static int LogOfHRGrainWords;
319
320 static size_t GrainBytes;
321 static size_t GrainWords;
322 static size_t CardsPerRegion;
323
324 static size_t align_up_to_region_byte_size(size_t sz) {
325 return (sz + (size_t) GrainBytes - 1) &
326 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
327 }
328
329
330 // Returns whether a field is in the same region as the obj it points to.
331 template <typename T>
332 static bool is_in_same_region(T* p, oop obj) {
333 assert(p != NULL, "p can't be NULL");
334 assert(obj != NULL, "obj can't be NULL");
335 return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
336 }
337
338 static size_t max_region_size();
339 static size_t min_region_size_in_words();
340
341 // It sets up the heap region size (GrainBytes / GrainWords), as
342 // well as other related fields that are based on the heap region
343 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
344 // CardsPerRegion). All those fields are considered constant
345 // throughout the JVM's execution, therefore they should only be set
346 // up once during initialization time.
347 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
348
349 // All allocated blocks are occupied by objects in a HeapRegion
350 bool block_is_obj(const HeapWord* p) const;
351
352 // Returns whether the given object is dead based on TAMS and bitmap.
353 bool is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const;
354
355 // Returns the object size for all valid block starts
356 // and the amount of unallocated words if called on top()
357 size_t block_size(const HeapWord* p) const;
358
359 // Scans through the region using the bitmap to determine what
360 // objects to call size_t ApplyToMarkedClosure::apply(oop) for.
361 template<typename ApplyToMarkedClosure>
362 inline void apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure);
363 // Override for scan_and_forward support.
364 void prepare_for_compaction(CompactPoint* cp);
365 // Update heap region to be consistent after compaction.
366 void complete_compaction();
367
368 inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
369 inline HeapWord* allocate_no_bot_updates(size_t word_size);
370 inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
371
372 // If this region is a member of a HeapRegionManager, the index in that
373 // sequence, otherwise -1.
374 uint hrm_index() const { return _hrm_index; }
375
376 // The number of bytes marked live in the region in the last marking phase.
377 size_t marked_bytes() { return _prev_marked_bytes; }
378 size_t live_bytes() {
379 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
380 }
381
382 // The number of bytes counted in the next marking.
383 size_t next_marked_bytes() { return _next_marked_bytes; }
384 // The number of bytes live wrt the next marking.
385 size_t next_live_bytes() {
386 return
387 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
388 }
389
390 // A lower bound on the amount of garbage bytes in the region.
391 size_t garbage_bytes() {
392 size_t used_at_mark_start_bytes =
393 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
394 return used_at_mark_start_bytes - marked_bytes();
395 }
396
397 // Return the amount of bytes we'll reclaim if we collect this
398 // region. This includes not only the known garbage bytes in the
399 // region but also any unallocated space in it, i.e., [top, end),
400 // since it will also be reclaimed if we collect the region.
401 size_t reclaimable_bytes() {
402 size_t known_live_bytes = live_bytes();
403 assert(known_live_bytes <= capacity(), "sanity");
404 return capacity() - known_live_bytes;
405 }
406
407 // An upper bound on the number of live bytes in the region.
408 size_t max_live_bytes() { return used() - garbage_bytes(); }
409
410 void add_to_marked_bytes(size_t incr_bytes) {
411 _next_marked_bytes = _next_marked_bytes + incr_bytes;
412 }
413
414 void zero_marked_bytes() {
415 _prev_marked_bytes = _next_marked_bytes = 0;
416 }
417
418 const char* get_type_str() const { return _type.get_str(); }
419 const char* get_short_type_str() const { return _type.get_short_str(); }
420 G1HeapRegionTraceType::Type get_trace_type() { return _type.get_trace_type(); }
421
422 bool is_free() const { return _type.is_free(); }
423
424 bool is_young() const { return _type.is_young(); }
425 bool is_eden() const { return _type.is_eden(); }
426 bool is_survivor() const { return _type.is_survivor(); }
427
428 bool is_humongous() const { return _type.is_humongous(); }
429 bool is_starts_humongous() const { return _type.is_starts_humongous(); }
430 bool is_continues_humongous() const { return _type.is_continues_humongous(); }
431
432 bool is_old() const { return _type.is_old(); }
433
434 bool is_old_or_humongous() const { return _type.is_old_or_humongous(); }
435
436 // A pinned region contains objects which are not moved by garbage collections.
437 // Humongous regions and archive regions are pinned.
438 bool is_pinned() const { return _type.is_pinned(); }
439
440 // An archive region is a pinned region, also tagged as old, which
441 // should not be marked during mark/sweep. This allows the address
442 // space to be shared by JVM instances.
443 bool is_archive() const { return _type.is_archive(); }
444 bool is_open_archive() const { return _type.is_open_archive(); }
445 bool is_closed_archive() const { return _type.is_closed_archive(); }
446
447 // For a humongous region, region in which it starts.
448 HeapRegion* humongous_start_region() const {
449 return _humongous_start_region;
450 }
451
452 // Makes the current region be a "starts humongous" region, i.e.,
453 // the first region in a series of one or more contiguous regions
454 // that will contain a single "humongous" object.
455 //
456 // obj_top : points to the top of the humongous object.
457 // fill_size : size of the filler object at the end of the region series.
458 void set_starts_humongous(HeapWord* obj_top, size_t fill_size);
459
460 // Makes the current region be a "continues humongous'
461 // region. first_hr is the "start humongous" region of the series
462 // which this region will be part of.
463 void set_continues_humongous(HeapRegion* first_hr);
464
465 // Unsets the humongous-related fields on the region.
466 void clear_humongous();
467
468 // If the region has a remembered set, return a pointer to it.
469 HeapRegionRemSet* rem_set() const {
470 return _rem_set;
471 }
472
473 inline bool in_collection_set() const;
474
475 void set_allocation_context(AllocationContext_t context) {
476 _allocation_context = context;
477 }
478
479 AllocationContext_t allocation_context() const {
480 return _allocation_context;
481 }
482
483 // Methods used by the HeapRegionSetBase class and subclasses.
484
485 // Getter and setter for the next and prev fields used to link regions into
486 // linked lists.
487 HeapRegion* next() { return _next; }
488 HeapRegion* prev() { return _prev; }
489
490 void set_next(HeapRegion* next) { _next = next; }
491 void set_prev(HeapRegion* prev) { _prev = prev; }
492
493 // Every region added to a set is tagged with a reference to that
494 // set. This is used for doing consistency checking to make sure that
495 // the contents of a set are as they should be and it's only
496 // available in non-product builds.
497 #ifdef ASSERT
498 void set_containing_set(HeapRegionSetBase* containing_set) {
499 assert((containing_set == NULL && _containing_set != NULL) ||
500 (containing_set != NULL && _containing_set == NULL),
501 "containing_set: " PTR_FORMAT " "
502 "_containing_set: " PTR_FORMAT,
503 p2i(containing_set), p2i(_containing_set));
504
505 _containing_set = containing_set;
506 }
507
508 HeapRegionSetBase* containing_set() { return _containing_set; }
509 #else // ASSERT
510 void set_containing_set(HeapRegionSetBase* containing_set) { }
511
512 // containing_set() is only used in asserts so there's no reason
513 // to provide a dummy version of it.
514 #endif // ASSERT
515
516
517 // Reset the HeapRegion to default values.
518 // If skip_remset is true, do not clear the remembered set.
519 void hr_clear(bool skip_remset, bool clear_space, bool locked = false);
520 // Clear the parts skipped by skip_remset in hr_clear() in the HeapRegion during
521 // a concurrent phase.
522 void par_clear();
523
524 // Get the start of the unmarked area in this region.
525 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
526 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
527
528 // Note the start or end of marking. This tells the heap region
529 // that the collector is about to start or has finished (concurrently)
530 // marking the heap.
531
532 // Notify the region that concurrent marking is starting. Initialize
533 // all fields related to the next marking info.
534 inline void note_start_of_marking();
535
536 // Notify the region that concurrent marking has finished. Copy the
537 // (now finalized) next marking info fields into the prev marking
538 // info fields.
539 inline void note_end_of_marking();
540
541 // Notify the region that it will be used as to-space during a GC
542 // and we are about to start copying objects into it.
543 inline void note_start_of_copying(bool during_initial_mark);
544
545 // Notify the region that it ceases being to-space during a GC and
546 // we will not copy objects into it any more.
547 inline void note_end_of_copying(bool during_initial_mark);
548
549 // Notify the region that we are about to start processing
550 // self-forwarded objects during evac failure handling.
551 void note_self_forwarding_removal_start(bool during_initial_mark,
552 bool during_conc_mark);
553
554 // Notify the region that we have finished processing self-forwarded
555 // objects during evac failure handling.
556 void note_self_forwarding_removal_end(size_t marked_bytes);
557
558 // Returns "false" iff no object in the region was allocated when the
559 // last mark phase ended.
560 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
561
562 void reset_during_compaction() {
563 assert(is_humongous(),
564 "should only be called for humongous regions");
565
566 zero_marked_bytes();
567 init_top_at_mark_start();
568 }
569
570 void calc_gc_efficiency(void);
571 double gc_efficiency() { return _gc_efficiency;}
572
573 int young_index_in_cset() const { return _young_index_in_cset; }
574 void set_young_index_in_cset(int index) {
575 assert( (index == -1) || is_young(), "pre-condition" );
576 _young_index_in_cset = index;
577 }
578
579 int age_in_surv_rate_group() {
580 assert( _surv_rate_group != NULL, "pre-condition" );
581 assert( _age_index > -1, "pre-condition" );
582 return _surv_rate_group->age_in_group(_age_index);
583 }
584
585 void record_surv_words_in_group(size_t words_survived) {
586 assert( _surv_rate_group != NULL, "pre-condition" );
587 assert( _age_index > -1, "pre-condition" );
588 int age_in_group = age_in_surv_rate_group();
589 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
590 }
591
592 int age_in_surv_rate_group_cond() {
593 if (_surv_rate_group != NULL)
594 return age_in_surv_rate_group();
595 else
596 return -1;
597 }
598
599 SurvRateGroup* surv_rate_group() {
600 return _surv_rate_group;
601 }
602
603 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
604 assert( surv_rate_group != NULL, "pre-condition" );
605 assert( _surv_rate_group == NULL, "pre-condition" );
606 assert( is_young(), "pre-condition" );
607
608 _surv_rate_group = surv_rate_group;
609 _age_index = surv_rate_group->next_age_index();
610 }
611
612 void uninstall_surv_rate_group() {
613 if (_surv_rate_group != NULL) {
614 assert( _age_index > -1, "pre-condition" );
615 assert( is_young(), "pre-condition" );
616
617 _surv_rate_group = NULL;
618 _age_index = -1;
619 } else {
620 assert( _age_index == -1, "pre-condition" );
621 }
622 }
623
624 void set_free();
625
626 void set_eden();
627 void set_eden_pre_gc();
628 void set_survivor();
629
630 void move_to_old();
631 void set_old();
632
633 void set_open_archive();
634 void set_closed_archive();
635
636 // Determine if an object has been allocated since the last
637 // mark performed by the collector. This returns true iff the object
638 // is within the unmarked area of the region.
639 bool obj_allocated_since_prev_marking(oop obj) const {
640 return (HeapWord *) obj >= prev_top_at_mark_start();
641 }
642 bool obj_allocated_since_next_marking(oop obj) const {
643 return (HeapWord *) obj >= next_top_at_mark_start();
644 }
645
646 // Returns the "evacuation_failed" property of the region.
647 bool evacuation_failed() { return _evacuation_failed; }
648
649 // Sets the "evacuation_failed" property of the region.
650 void set_evacuation_failed(bool b) {
651 _evacuation_failed = b;
652
653 if (b) {
654 _next_marked_bytes = 0;
655 }
656 }
657
658 // Iterate over the objects overlapping part of a card, applying cl
659 // to all references in the region. This is a helper for
660 // G1RemSet::refine_card*, and is tightly coupled with them.
661 // mr is the memory region covered by the card, trimmed to the
662 // allocated space for this region. Must not be empty.
663 // This region must be old or humongous.
664 // Returns true if the designated objects were successfully
665 // processed, false if an unparsable part of the heap was
666 // encountered; that only happens when invoked concurrently with the
667 // mutator.
668 template <bool is_gc_active, class Closure>
669 inline bool oops_on_card_seq_iterate_careful(MemRegion mr, Closure* cl);
670
671 size_t recorded_rs_length() const { return _recorded_rs_length; }
672 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
673
674 void set_recorded_rs_length(size_t rs_length) {
675 _recorded_rs_length = rs_length;
676 }
677
678 void set_predicted_elapsed_time_ms(double ms) {
679 _predicted_elapsed_time_ms = ms;
680 }
681
682 // Routines for managing a list of code roots (attached to the
683 // this region's RSet) that point into this heap region.
684 void add_strong_code_root(nmethod* nm);
685 void add_strong_code_root_locked(nmethod* nm);
686 void remove_strong_code_root(nmethod* nm);
687
688 // Applies blk->do_code_blob() to each of the entries in
689 // the strong code roots list for this region
690 void strong_code_roots_do(CodeBlobClosure* blk) const;
691
692 // Verify that the entries on the strong code root list for this
693 // region are live and include at least one pointer into this region.
694 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
695
696 void print() const;
697 void print_on(outputStream* st) const;
698
699 // vo == UsePrevMarking -> use "prev" marking information,
700 // vo == UseNextMarking -> use "next" marking information
701 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
702 //
703 // NOTE: Only the "prev" marking information is guaranteed to be
704 // consistent most of the time, so most calls to this should use
705 // vo == UsePrevMarking.
706 // Currently, there is only one case where this is called with
707 // vo == UseNextMarking, which is to verify the "next" marking
708 // information at the end of remark.
709 // Currently there is only one place where this is called with
710 // vo == UseFullMarking, which is to verify the marking during a
711 // full GC.
712 void verify(VerifyOption vo, bool *failures) const;
713
714 // Override; it uses the "prev" marking information
715 virtual void verify() const;
716
717 void verify_rem_set(VerifyOption vo, bool *failures) const;
718 void verify_rem_set() const;
719 };
720
721 // HeapRegionClosure is used for iterating over regions.
722 // Terminates the iteration when the "do_heap_region" method returns "true".
723 class HeapRegionClosure : public StackObj {
724 friend class HeapRegionManager;
725 friend class G1CollectionSet;
726
727 bool _is_complete;
728 void set_incomplete() { _is_complete = false; }
729
730 public:
731 HeapRegionClosure(): _is_complete(true) {}
732
733 // Typically called on each region until it returns true.
734 virtual bool do_heap_region(HeapRegion* r) = 0;
735
736 // True after iteration if the closure was applied to all heap regions
737 // and returned "false" in all cases.
738 bool is_complete() { return _is_complete; }
739 };
740
741 #endif // SHARE_VM_GC_G1_HEAPREGION_HPP