1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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. For the last ContinuesHumongous
55 // region, top() will equal the object's top.
56
57 class G1CollectedHeap;
58 class HeapRegionRemSet;
59 class HeapRegionRemSetIterator;
60 class HeapRegion;
61 class HeapRegionSetBase;
62 class nmethod;
63
64 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
65 #define HR_FORMAT_PARAMS(_hr_) \
66 (_hr_)->hrm_index(), \
67 (_hr_)->get_short_type_str(), \
68 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
69
70 // sentinel value for hrm_index
71 #define G1_NO_HRM_INDEX ((uint) -1)
72
73 // A dirty card to oop closure for heap regions. It
74 // knows how to get the G1 heap and how to use the bitmap
75 // in the concurrent marker used by G1 to filter remembered
76 // sets.
77
78 class HeapRegionDCTOC : public DirtyCardToOopClosure {
79 private:
80 HeapRegion* _hr;
81 G1ParPushHeapRSClosure* _rs_scan;
82 G1CollectedHeap* _g1;
83
84 // Walk the given memory region from bottom to (actual) top
85 // looking for objects and applying the oop closure (_cl) to
86 // them. The base implementation of this treats the area as
87 // blocks, where a block may or may not be an object. Sub-
88 // classes should override this to provide more accurate
89 // or possibly more efficient walking.
90 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
91
92 public:
93 HeapRegionDCTOC(G1CollectedHeap* g1,
94 HeapRegion* hr,
95 G1ParPushHeapRSClosure* cl,
96 CardTableModRefBS::PrecisionStyle precision);
97 };
98
99 // The complicating factor is that BlockOffsetTable diverged
100 // significantly, and we need functionality that is only in the G1 version.
101 // So I copied that code, which led to an alternate G1 version of
102 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
103 // be reconciled, then G1OffsetTableContigSpace could go away.
104
105 // The idea behind time stamps is the following. We want to keep track of
106 // the highest address where it's safe to scan objects for each region.
107 // This is only relevant for current GC alloc regions so we keep a time stamp
108 // per region to determine if the region has been allocated during the current
109 // GC or not. If the time stamp is current we report a scan_top value which
110 // was saved at the end of the previous GC for retained alloc regions and which is
111 // equal to the bottom for all other regions.
112 // There is a race between card scanners and allocating gc workers where we must ensure
113 // that card scanners do not read the memory allocated by the gc workers.
114 // In order to enforce that, we must not return a value of _top which is more recent than the
115 // time stamp. This is due to the fact that a region may become a gc alloc region at
116 // some point after we've read the timestamp value as being < the current time stamp.
117 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
118 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
119 // evacuation pauses between two cleanups, which is _highly_ unlikely.
120 class G1ContiguousSpace: public CompactibleSpace {
121 friend class VMStructs;
122 HeapWord* volatile _top;
123 HeapWord* volatile _scan_top;
124 protected:
125 G1BlockOffsetTablePart _bot_part;
126 Mutex _par_alloc_lock;
127 volatile uint _gc_time_stamp;
128 // When we need to retire an allocation region, while other threads
129 // are also concurrently trying to allocate into it, we typically
130 // allocate a dummy object at the end of the region to ensure that
131 // no more allocations can take place in it. However, sometimes we
132 // want to know where the end of the last "real" object we allocated
133 // into the region was and this is what this keeps track.
134 HeapWord* _pre_dummy_top;
135
136 public:
137 G1ContiguousSpace(G1BlockOffsetTable* bot);
138
139 void set_top(HeapWord* value) { _top = value; }
140 HeapWord* top() const { return _top; }
141
142 protected:
143 // Reset the G1ContiguousSpace.
144 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
145
146 HeapWord* volatile* top_addr() { return &_top; }
147 // Try to allocate at least min_word_size and up to desired_size from this Space.
148 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
149 // space allocated.
150 // This version assumes that all allocation requests to this Space are properly
151 // synchronized.
152 inline HeapWord* allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
153 // Try to allocate at least min_word_size and up to desired_size from this Space.
154 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
155 // space allocated.
156 // This version synchronizes with other calls to par_allocate_impl().
157 inline HeapWord* par_allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
158
159 public:
160 void reset_after_compaction() { set_top(compaction_top()); }
161
162 size_t used() const { return byte_size(bottom(), top()); }
163 size_t free() const { return byte_size(top(), end()); }
164 bool is_free_block(const HeapWord* p) const { return p >= top(); }
165
166 MemRegion used_region() const { return MemRegion(bottom(), top()); }
167
168 void object_iterate(ObjectClosure* blk);
169 void safe_object_iterate(ObjectClosure* blk);
170
171 void mangle_unused_area() PRODUCT_RETURN;
172 void mangle_unused_area_complete() PRODUCT_RETURN;
173
174 HeapWord* scan_top() const;
175 void record_timestamp();
176 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
177 uint get_gc_time_stamp() { return _gc_time_stamp; }
178 void record_retained_region();
179
180 // See the comment above in the declaration of _pre_dummy_top for an
181 // explanation of what it is.
182 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
183 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
184 _pre_dummy_top = pre_dummy_top;
185 }
186 HeapWord* pre_dummy_top() {
187 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
188 }
189 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
190
191 virtual void clear(bool mangle_space);
192
193 HeapWord* block_start(const void* p);
194 HeapWord* block_start_const(const void* p) const;
195
196 // Allocation (return NULL if full). Assumes the caller has established
197 // mutually exclusive access to the space.
198 HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
199 // Allocation (return NULL if full). Enforces mutual exclusion internally.
200 HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
201
202 virtual HeapWord* allocate(size_t word_size);
203 virtual HeapWord* par_allocate(size_t word_size);
204
205 HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
206
207 // MarkSweep support phase3
208 virtual HeapWord* initialize_threshold();
209 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
210
211 virtual void print() const;
212
213 void reset_bot() {
214 _bot_part.reset_bot();
215 }
216
217 void print_bot_on(outputStream* out) {
218 _bot_part.print_on(out);
219 }
220 };
221
222 class HeapRegion: public G1ContiguousSpace {
223 friend class VMStructs;
224 // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
225 template <typename SpaceType>
226 friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
227 private:
228
229 // The remembered set for this region.
230 // (Might want to make this "inline" later, to avoid some alloc failure
231 // issues.)
232 HeapRegionRemSet* _rem_set;
233
234 // Auxiliary functions for scan_and_forward support.
235 // See comments for CompactibleSpace for more information.
236 inline HeapWord* scan_limit() const {
237 return top();
238 }
239
240 inline bool scanned_block_is_obj(const HeapWord* addr) const {
241 return true; // Always true, since scan_limit is top
242 }
243
244 inline size_t scanned_block_size(const HeapWord* addr) const {
245 return HeapRegion::block_size(addr); // Avoid virtual call
246 }
247
248 void report_region_type_change(G1HeapRegionTraceType::Type to);
249
250 protected:
251 // The index of this region in the heap region sequence.
252 uint _hrm_index;
253
254 AllocationContext_t _allocation_context;
255
256 HeapRegionType _type;
257
258 // For a humongous region, region in which it starts.
259 HeapRegion* _humongous_start_region;
260
261 // True iff an attempt to evacuate an object in the region failed.
262 bool _evacuation_failed;
263
264 // Fields used by the HeapRegionSetBase class and subclasses.
265 HeapRegion* _next;
266 HeapRegion* _prev;
267 #ifdef ASSERT
268 HeapRegionSetBase* _containing_set;
269 #endif // ASSERT
270
271 // We use concurrent marking to determine the amount of live data
272 // in each heap region.
273 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
274 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
275
276 // The calculated GC efficiency of the region.
277 double _gc_efficiency;
278
279 int _young_index_in_cset;
280 SurvRateGroup* _surv_rate_group;
281 int _age_index;
282
283 // The start of the unmarked area. The unmarked area extends from this
284 // word until the top and/or end of the region, and is the part
285 // of the region for which no marking was done, i.e. objects may
286 // have been allocated in this part since the last mark phase.
287 // "prev" is the top at the start of the last completed marking.
288 // "next" is the top at the start of the in-progress marking (if any.)
289 HeapWord* _prev_top_at_mark_start;
290 HeapWord* _next_top_at_mark_start;
291 // If a collection pause is in progress, this is the top at the start
292 // of that pause.
293
294 void init_top_at_mark_start() {
295 assert(_prev_marked_bytes == 0 &&
296 _next_marked_bytes == 0,
297 "Must be called after zero_marked_bytes.");
298 HeapWord* bot = bottom();
299 _prev_top_at_mark_start = bot;
300 _next_top_at_mark_start = bot;
301 }
302
303 // Cached attributes used in the collection set policy information
304
305 // The RSet length that was added to the total value
306 // for the collection set.
307 size_t _recorded_rs_length;
308
309 // The predicted elapsed time that was added to total value
310 // for the collection set.
311 double _predicted_elapsed_time_ms;
312
313 // The predicted number of bytes to copy that was added to
314 // the total value for the collection set.
315 size_t _predicted_bytes_to_copy;
316
317 public:
318 HeapRegion(uint hrm_index,
319 G1BlockOffsetTable* bot,
320 MemRegion mr);
321
322 // Initializing the HeapRegion not only resets the data structure, but also
323 // resets the BOT for that heap region.
324 // The default values for clear_space means that we will do the clearing if
325 // there's clearing to be done ourselves. We also always mangle the space.
326 virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
327
328 static int LogOfHRGrainBytes;
329 static int LogOfHRGrainWords;
330
331 static size_t GrainBytes;
332 static size_t GrainWords;
333 static size_t CardsPerRegion;
334
335 static size_t align_up_to_region_byte_size(size_t sz) {
336 return (sz + (size_t) GrainBytes - 1) &
337 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
338 }
339
340
341 // Returns whether a field is in the same region as the obj it points to.
342 template <typename T>
343 static bool is_in_same_region(T* p, oop obj) {
344 assert(p != NULL, "p can't be NULL");
345 assert(obj != NULL, "obj can't be NULL");
346 return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
347 }
348
349 static size_t max_region_size();
350 static size_t min_region_size_in_words();
351
352 // It sets up the heap region size (GrainBytes / GrainWords), as
353 // well as other related fields that are based on the heap region
354 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
355 // CardsPerRegion). All those fields are considered constant
356 // throughout the JVM's execution, therefore they should only be set
357 // up once during initialization time.
358 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
359
360 // All allocated blocks are occupied by objects in a HeapRegion
361 bool block_is_obj(const HeapWord* p) const;
362
363 // Returns the object size for all valid block starts
364 // and the amount of unallocated words if called on top()
365 size_t block_size(const HeapWord* p) const;
366
367 // Override for scan_and_forward support.
368 void prepare_for_compaction(CompactPoint* cp);
369
370 inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
371 inline HeapWord* allocate_no_bot_updates(size_t word_size);
372 inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
373
374 // If this region is a member of a HeapRegionManager, the index in that
375 // sequence, otherwise -1.
376 uint hrm_index() const { return _hrm_index; }
377
378 // The number of bytes marked live in the region in the last marking phase.
379 size_t marked_bytes() { return _prev_marked_bytes; }
380 size_t live_bytes() {
381 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
382 }
383
384 // The number of bytes counted in the next marking.
385 size_t next_marked_bytes() { return _next_marked_bytes; }
386 // The number of bytes live wrt the next marking.
387 size_t next_live_bytes() {
388 return
389 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
390 }
391
392 // A lower bound on the amount of garbage bytes in the region.
393 size_t garbage_bytes() {
394 size_t used_at_mark_start_bytes =
395 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
396 return used_at_mark_start_bytes - marked_bytes();
397 }
398
399 // Return the amount of bytes we'll reclaim if we collect this
400 // region. This includes not only the known garbage bytes in the
401 // region but also any unallocated space in it, i.e., [top, end),
402 // since it will also be reclaimed if we collect the region.
403 size_t reclaimable_bytes() {
404 size_t known_live_bytes = live_bytes();
405 assert(known_live_bytes <= capacity(), "sanity");
406 return capacity() - known_live_bytes;
407 }
408
409 // An upper bound on the number of live bytes in the region.
410 size_t max_live_bytes() { return used() - garbage_bytes(); }
411
412 void add_to_marked_bytes(size_t incr_bytes) {
413 _next_marked_bytes = _next_marked_bytes + incr_bytes;
414 }
415
416 void zero_marked_bytes() {
417 _prev_marked_bytes = _next_marked_bytes = 0;
418 }
419
420 const char* get_type_str() const { return _type.get_str(); }
421 const char* get_short_type_str() const { return _type.get_short_str(); }
422 G1HeapRegionTraceType::Type get_trace_type() { return _type.get_trace_type(); }
423
424 bool is_free() const { return _type.is_free(); }
425
426 bool is_young() const { return _type.is_young(); }
427 bool is_eden() const { return _type.is_eden(); }
428 bool is_survivor() const { return _type.is_survivor(); }
429
430 bool is_humongous() const { return _type.is_humongous(); }
431 bool is_starts_humongous() const { return _type.is_starts_humongous(); }
432 bool is_continues_humongous() const { return _type.is_continues_humongous(); }
433
434 bool is_old() const { return _type.is_old(); }
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
445 // For a humongous region, region in which it starts.
446 HeapRegion* humongous_start_region() const {
447 return _humongous_start_region;
448 }
449
450 // Makes the current region be a "starts humongous" region, i.e.,
451 // the first region in a series of one or more contiguous regions
452 // that will contain a single "humongous" object.
453 //
454 // obj_top : points to the top of the humongous object.
455 // fill_size : size of the filler object at the end of the region series.
456 void set_starts_humongous(HeapWord* obj_top, size_t fill_size);
457
458 // Makes the current region be a "continues humongous'
459 // region. first_hr is the "start humongous" region of the series
460 // which this region will be part of.
461 void set_continues_humongous(HeapRegion* first_hr);
462
463 // Unsets the humongous-related fields on the region.
464 void clear_humongous();
465
466 // If the region has a remembered set, return a pointer to it.
467 HeapRegionRemSet* rem_set() const {
468 return _rem_set;
469 }
470
471 inline bool in_collection_set() const;
472
473 void set_allocation_context(AllocationContext_t context) {
474 _allocation_context = context;
475 }
476
477 AllocationContext_t allocation_context() const {
478 return _allocation_context;
479 }
480
481 // Methods used by the HeapRegionSetBase class and subclasses.
482
483 // Getter and setter for the next and prev fields used to link regions into
484 // linked lists.
485 HeapRegion* next() { return _next; }
486 HeapRegion* prev() { return _prev; }
487
488 void set_next(HeapRegion* next) { _next = next; }
489 void set_prev(HeapRegion* prev) { _prev = prev; }
490
491 // Every region added to a set is tagged with a reference to that
492 // set. This is used for doing consistency checking to make sure that
493 // the contents of a set are as they should be and it's only
494 // available in non-product builds.
495 #ifdef ASSERT
496 void set_containing_set(HeapRegionSetBase* containing_set) {
497 assert((containing_set == NULL && _containing_set != NULL) ||
498 (containing_set != NULL && _containing_set == NULL),
499 "containing_set: " PTR_FORMAT " "
500 "_containing_set: " PTR_FORMAT,
501 p2i(containing_set), p2i(_containing_set));
502
503 _containing_set = containing_set;
504 }
505
506 HeapRegionSetBase* containing_set() { return _containing_set; }
507 #else // ASSERT
508 void set_containing_set(HeapRegionSetBase* containing_set) { }
509
510 // containing_set() is only used in asserts so there's no reason
511 // to provide a dummy version of it.
512 #endif // ASSERT
513
514
515 // Reset HR stuff to default values.
516 void hr_clear(bool par, bool clear_space, bool locked = false);
517 void par_clear();
518
519 // Get the start of the unmarked area in this region.
520 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
521 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
522
523 // Note the start or end of marking. This tells the heap region
524 // that the collector is about to start or has finished (concurrently)
525 // marking the heap.
526
527 // Notify the region that concurrent marking is starting. Initialize
528 // all fields related to the next marking info.
529 inline void note_start_of_marking();
530
531 // Notify the region that concurrent marking has finished. Copy the
532 // (now finalized) next marking info fields into the prev marking
533 // info fields.
534 inline void note_end_of_marking();
535
536 // Notify the region that it will be used as to-space during a GC
537 // and we are about to start copying objects into it.
538 inline void note_start_of_copying(bool during_initial_mark);
539
540 // Notify the region that it ceases being to-space during a GC and
541 // we will not copy objects into it any more.
542 inline void note_end_of_copying(bool during_initial_mark);
543
544 // Notify the region that we are about to start processing
545 // self-forwarded objects during evac failure handling.
546 void note_self_forwarding_removal_start(bool during_initial_mark,
547 bool during_conc_mark);
548
549 // Notify the region that we have finished processing self-forwarded
550 // objects during evac failure handling.
551 void note_self_forwarding_removal_end(bool during_initial_mark,
552 bool during_conc_mark,
553 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 // Requires that "mr" be entirely within the region.
654 // Apply "cl->do_object" to all objects that intersect with "mr".
655 // If the iteration encounters an unparseable portion of the region,
656 // or if "cl->abort()" is true after a closure application,
657 // terminate the iteration and return the address of the start of the
658 // subregion that isn't done. (The two can be distinguished by querying
659 // "cl->abort()".) Return of "NULL" indicates that the iteration
660 // completed.
661 HeapWord*
662 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
663
664 // filter_young: if true and the region is a young region then we
665 // skip the iteration.
666 // card_ptr: if not NULL, and we decide that the card is not young
667 // and we iterate over it, we'll clean the card before we start the
668 // iteration.
669 HeapWord*
670 oops_on_card_seq_iterate_careful(MemRegion mr,
671 FilterOutOfRegionClosure* cl,
672 bool filter_young,
673 jbyte* card_ptr);
674
675 size_t recorded_rs_length() const { return _recorded_rs_length; }
676 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
677 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }
678
679 void set_recorded_rs_length(size_t rs_length) {
680 _recorded_rs_length = rs_length;
681 }
682
683 void set_predicted_elapsed_time_ms(double ms) {
684 _predicted_elapsed_time_ms = ms;
685 }
686
687 void set_predicted_bytes_to_copy(size_t bytes) {
688 _predicted_bytes_to_copy = bytes;
689 }
690
691 virtual CompactibleSpace* next_compaction_space() const;
692
693 virtual void reset_after_compaction();
694
695 // Routines for managing a list of code roots (attached to the
696 // this region's RSet) that point into this heap region.
697 void add_strong_code_root(nmethod* nm);
698 void add_strong_code_root_locked(nmethod* nm);
699 void remove_strong_code_root(nmethod* nm);
700
701 // Applies blk->do_code_blob() to each of the entries in
702 // the strong code roots list for this region
703 void strong_code_roots_do(CodeBlobClosure* blk) const;
704
705 // Verify that the entries on the strong code root list for this
706 // region are live and include at least one pointer into this region.
707 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
708
709 void print() const;
710 void print_on(outputStream* st) const;
711
712 // vo == UsePrevMarking -> use "prev" marking information,
713 // vo == UseNextMarking -> use "next" marking information
714 // vo == UseMarkWord -> use the mark word in the object header
715 //
716 // NOTE: Only the "prev" marking information is guaranteed to be
717 // consistent most of the time, so most calls to this should use
718 // vo == UsePrevMarking.
719 // Currently, there is only one case where this is called with
720 // vo == UseNextMarking, which is to verify the "next" marking
721 // information at the end of remark.
722 // Currently there is only one place where this is called with
723 // vo == UseMarkWord, which is to verify the marking during a
724 // full GC.
725 void verify(VerifyOption vo, bool *failures) const;
726
727 // Override; it uses the "prev" marking information
728 virtual void verify() const;
729
730 void verify_rem_set(VerifyOption vo, bool *failures) const;
731 void verify_rem_set() const;
732 };
733
734 // HeapRegionClosure is used for iterating over regions.
735 // Terminates the iteration when the "doHeapRegion" method returns "true".
736 class HeapRegionClosure : public StackObj {
737 friend class HeapRegionManager;
738 friend class G1CollectionSet;
739
740 bool _complete;
741 void incomplete() { _complete = false; }
742
743 public:
744 HeapRegionClosure(): _complete(true) {}
745
746 // Typically called on each region until it returns true.
747 virtual bool doHeapRegion(HeapRegion* r) = 0;
748
749 // True after iteration if the closure was applied to all heap regions
750 // and returned "false" in all cases.
751 bool complete() { return _complete; }
752 };
753
754 #endif // SHARE_VM_GC_G1_HEAPREGION_HPP