1 /* 2 * Copyright (c) 2001, 2014, 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_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP 27 28 #include "gc_implementation/g1/g1BlockOffsetTable.hpp" 29 #include "gc_implementation/g1/g1_specialized_oop_closures.hpp" 30 #include "gc_implementation/g1/survRateGroup.hpp" 31 #include "gc_implementation/shared/ageTable.hpp" 32 #include "gc_implementation/shared/spaceDecorator.hpp" 33 #include "memory/space.inline.hpp" 34 #include "memory/watermark.hpp" 35 #include "utilities/macros.hpp" 36 37 #if INCLUDE_ALL_GCS 38 39 // A HeapRegion is the smallest piece of a G1CollectedHeap that 40 // can be collected independently. 41 42 // NOTE: Although a HeapRegion is a Space, its 43 // Space::initDirtyCardClosure method must not be called. 44 // The problem is that the existence of this method breaks 45 // the independence of barrier sets from remembered sets. 46 // The solution is to remove this method from the definition 47 // of a Space. 48 49 class HeapRegionRemSet; 50 class HeapRegionRemSetIterator; 51 class HeapRegion; 52 class HeapRegionSetBase; 53 class nmethod; 54 55 #define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]" 56 #define HR_FORMAT_PARAMS(_hr_) \ 57 (_hr_)->hrs_index(), \ 58 (_hr_)->is_survivor() ? "S" : (_hr_)->is_young() ? "E" : \ 59 (_hr_)->startsHumongous() ? "HS" : \ 60 (_hr_)->continuesHumongous() ? "HC" : \ 61 !(_hr_)->is_empty() ? "O" : "F", \ 62 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end()) 63 64 // sentinel value for hrs_index 65 #define G1_NULL_HRS_INDEX ((uint) -1) 66 67 // A dirty card to oop closure for heap regions. It 68 // knows how to get the G1 heap and how to use the bitmap 69 // in the concurrent marker used by G1 to filter remembered 70 // sets. 71 72 class HeapRegionDCTOC : public DirtyCardToOopClosure { 73 public: 74 // Specification of possible DirtyCardToOopClosure filtering. 75 enum FilterKind { 76 NoFilterKind, 77 IntoCSFilterKind, 78 OutOfRegionFilterKind 79 }; 80 81 protected: 82 HeapRegion* _hr; 83 FilterKind _fk; 84 G1CollectedHeap* _g1; 85 86 // Walk the given memory region from bottom to (actual) top 87 // looking for objects and applying the oop closure (_cl) to 88 // them. The base implementation of this treats the area as 89 // blocks, where a block may or may not be an object. Sub- 90 // classes should override this to provide more accurate 91 // or possibly more efficient walking. 92 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top); 93 94 public: 95 HeapRegionDCTOC(G1CollectedHeap* g1, 96 HeapRegion* hr, ExtendedOopClosure* cl, 97 CardTableModRefBS::PrecisionStyle precision, 98 FilterKind fk); 99 }; 100 101 // The complicating factor is that BlockOffsetTable diverged 102 // significantly, and we need functionality that is only in the G1 version. 103 // So I copied that code, which led to an alternate G1 version of 104 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could 105 // be reconciled, then G1OffsetTableContigSpace could go away. 106 107 // The idea behind time stamps is the following. Doing a save_marks on 108 // all regions at every GC pause is time consuming (if I remember 109 // well, 10ms or so). So, we would like to do that only for regions 110 // that are GC alloc regions. To achieve this, we use time 111 // stamps. For every evacuation pause, G1CollectedHeap generates a 112 // unique time stamp (essentially a counter that gets 113 // incremented). Every time we want to call save_marks on a region, 114 // we set the saved_mark_word to top and also copy the current GC 115 // time stamp to the time stamp field of the space. Reading the 116 // saved_mark_word involves checking the time stamp of the 117 // region. If it is the same as the current GC time stamp, then we 118 // can safely read the saved_mark_word field, as it is valid. If the 119 // time stamp of the region is not the same as the current GC time 120 // stamp, then we instead read top, as the saved_mark_word field is 121 // invalid. Time stamps (on the regions and also on the 122 // G1CollectedHeap) are reset at every cleanup (we iterate over 123 // the regions anyway) and at the end of a Full GC. The current scheme 124 // that uses sequential unsigned ints will fail only if we have 4b 125 // evacuation pauses between two cleanups, which is _highly_ unlikely. 126 class G1OffsetTableContigSpace: public CompactibleSpace { 127 friend class VMStructs; 128 HeapWord* _top; 129 protected: 130 G1BlockOffsetArrayContigSpace _offsets; 131 Mutex _par_alloc_lock; 132 volatile unsigned _gc_time_stamp; 133 // When we need to retire an allocation region, while other threads 134 // are also concurrently trying to allocate into it, we typically 135 // allocate a dummy object at the end of the region to ensure that 136 // no more allocations can take place in it. However, sometimes we 137 // want to know where the end of the last "real" object we allocated 138 // into the region was and this is what this keeps track. 139 HeapWord* _pre_dummy_top; 140 141 public: 142 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray, 143 MemRegion mr); 144 145 void set_top(HeapWord* value) { _top = value; } 146 HeapWord* top() const { return _top; } 147 148 protected: 149 HeapWord** top_addr() { return &_top; } 150 // Allocation helpers (return NULL if full). 151 inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value); 152 inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value); 153 154 public: 155 void reset_after_compaction() { set_top(compaction_top()); } 156 157 size_t used() const { return byte_size(bottom(), top()); } 158 size_t free() const { return byte_size(top(), end()); } 159 bool is_free_block(const HeapWord* p) const { return p >= top(); } 160 161 MemRegion used_region() const { return MemRegion(bottom(), top()); } 162 163 void object_iterate(ObjectClosure* blk); 164 void safe_object_iterate(ObjectClosure* blk); 165 166 void set_bottom(HeapWord* value); 167 void set_end(HeapWord* value); 168 169 virtual HeapWord* saved_mark_word() const; 170 void record_top_and_timestamp(); 171 void reset_gc_time_stamp() { _gc_time_stamp = 0; } 172 unsigned get_gc_time_stamp() { return _gc_time_stamp; } 173 174 // See the comment above in the declaration of _pre_dummy_top for an 175 // explanation of what it is. 176 void set_pre_dummy_top(HeapWord* pre_dummy_top) { 177 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition"); 178 _pre_dummy_top = pre_dummy_top; 179 } 180 HeapWord* pre_dummy_top() { 181 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top; 182 } 183 void reset_pre_dummy_top() { _pre_dummy_top = NULL; } 184 185 virtual void clear(bool mangle_space); 186 187 HeapWord* block_start(const void* p); 188 HeapWord* block_start_const(const void* p) const; 189 190 void prepare_for_compaction(CompactPoint* cp); 191 192 // Add offset table update. 193 virtual HeapWord* allocate(size_t word_size); 194 HeapWord* par_allocate(size_t word_size); 195 196 // MarkSweep support phase3 197 virtual HeapWord* initialize_threshold(); 198 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end); 199 200 virtual void print() const; 201 202 void reset_bot() { 203 _offsets.zero_bottom_entry(); 204 _offsets.initialize_threshold(); 205 } 206 207 void update_bot_for_object(HeapWord* start, size_t word_size) { 208 _offsets.alloc_block(start, word_size); 209 } 210 211 void print_bot_on(outputStream* out) { 212 _offsets.print_on(out); 213 } 214 }; 215 216 class HeapRegion: public G1OffsetTableContigSpace { 217 friend class VMStructs; 218 private: 219 220 enum HumongousType { 221 NotHumongous = 0, 222 StartsHumongous, 223 ContinuesHumongous 224 }; 225 226 // The remembered set for this region. 227 // (Might want to make this "inline" later, to avoid some alloc failure 228 // issues.) 229 HeapRegionRemSet* _rem_set; 230 231 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; } 232 233 protected: 234 // The index of this region in the heap region sequence. 235 uint _hrs_index; 236 237 HumongousType _humongous_type; 238 // For a humongous region, region in which it starts. 239 HeapRegion* _humongous_start_region; 240 // For the start region of a humongous sequence, it's original end(). 241 HeapWord* _orig_end; 242 243 // True iff the region is in current collection_set. 244 bool _in_collection_set; 245 246 // True iff an attempt to evacuate an object in the region failed. 247 bool _evacuation_failed; 248 249 // A heap region may be a member one of a number of special subsets, each 250 // represented as linked lists through the field below. Currently, these 251 // sets include: 252 // The collection set. 253 // The set of allocation regions used in a collection pause. 254 // Spaces that may contain gray objects. 255 HeapRegion* _next_in_special_set; 256 257 // next region in the young "generation" region set 258 HeapRegion* _next_young_region; 259 260 // Next region whose cards need cleaning 261 HeapRegion* _next_dirty_cards_region; 262 263 // Fields used by the HeapRegionSetBase class and subclasses. 264 HeapRegion* _next; 265 HeapRegion* _prev; 266 #ifdef ASSERT 267 HeapRegionSetBase* _containing_set; 268 #endif // ASSERT 269 bool _pending_removal; 270 271 // For parallel heapRegion traversal. 272 jint _claimed; 273 274 // We use concurrent marking to determine the amount of live data 275 // in each heap region. 276 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking. 277 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking. 278 279 // The calculated GC efficiency of the region. 280 double _gc_efficiency; 281 282 enum YoungType { 283 NotYoung, // a region is not young 284 Young, // a region is young 285 Survivor // a region is young and it contains survivors 286 }; 287 288 volatile YoungType _young_type; 289 int _young_index_in_cset; 290 SurvRateGroup* _surv_rate_group; 291 int _age_index; 292 293 // The start of the unmarked area. The unmarked area extends from this 294 // word until the top and/or end of the region, and is the part 295 // of the region for which no marking was done, i.e. objects may 296 // have been allocated in this part since the last mark phase. 297 // "prev" is the top at the start of the last completed marking. 298 // "next" is the top at the start of the in-progress marking (if any.) 299 HeapWord* _prev_top_at_mark_start; 300 HeapWord* _next_top_at_mark_start; 301 // If a collection pause is in progress, this is the top at the start 302 // of that pause. 303 304 void init_top_at_mark_start() { 305 assert(_prev_marked_bytes == 0 && 306 _next_marked_bytes == 0, 307 "Must be called after zero_marked_bytes."); 308 HeapWord* bot = bottom(); 309 _prev_top_at_mark_start = bot; 310 _next_top_at_mark_start = bot; 311 } 312 313 void set_young_type(YoungType new_type) { 314 //assert(_young_type != new_type, "setting the same type" ); 315 // TODO: add more assertions here 316 _young_type = new_type; 317 } 318 319 // Cached attributes used in the collection set policy information 320 321 // The RSet length that was added to the total value 322 // for the collection set. 323 size_t _recorded_rs_length; 324 325 // The predicted elapsed time that was added to total value 326 // for the collection set. 327 double _predicted_elapsed_time_ms; 328 329 // The predicted number of bytes to copy that was added to 330 // the total value for the collection set. 331 size_t _predicted_bytes_to_copy; 332 333 public: 334 HeapRegion(uint hrs_index, 335 G1BlockOffsetSharedArray* sharedOffsetArray, 336 MemRegion mr); 337 338 static int LogOfHRGrainBytes; 339 static int LogOfHRGrainWords; 340 341 static size_t GrainBytes; 342 static size_t GrainWords; 343 static size_t CardsPerRegion; 344 345 static size_t align_up_to_region_byte_size(size_t sz) { 346 return (sz + (size_t) GrainBytes - 1) & 347 ~((1 << (size_t) LogOfHRGrainBytes) - 1); 348 } 349 350 static size_t max_region_size(); 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 enum ClaimValues { 361 InitialClaimValue = 0, 362 FinalCountClaimValue = 1, 363 NoteEndClaimValue = 2, 364 ScrubRemSetClaimValue = 3, 365 ParVerifyClaimValue = 4, 366 RebuildRSClaimValue = 5, 367 ParEvacFailureClaimValue = 6, 368 AggregateCountClaimValue = 7, 369 VerifyCountClaimValue = 8, 370 ParMarkRootClaimValue = 9 371 }; 372 373 // All allocated blocks are occupied by objects in a HeapRegion 374 bool block_is_obj(const HeapWord* p) const; 375 376 // Returns the object size for all valid block starts 377 // and the amount of unallocated words if called on top() 378 size_t block_size(const HeapWord* p) const; 379 380 inline HeapWord* par_allocate_no_bot_updates(size_t word_size); 381 inline HeapWord* allocate_no_bot_updates(size_t word_size); 382 383 // If this region is a member of a HeapRegionSeq, the index in that 384 // sequence, otherwise -1. 385 uint hrs_index() const { return _hrs_index; } 386 387 // The number of bytes marked live in the region in the last marking phase. 388 size_t marked_bytes() { return _prev_marked_bytes; } 389 size_t live_bytes() { 390 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes(); 391 } 392 393 // The number of bytes counted in the next marking. 394 size_t next_marked_bytes() { return _next_marked_bytes; } 395 // The number of bytes live wrt the next marking. 396 size_t next_live_bytes() { 397 return 398 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes(); 399 } 400 401 // A lower bound on the amount of garbage bytes in the region. 402 size_t garbage_bytes() { 403 size_t used_at_mark_start_bytes = 404 (prev_top_at_mark_start() - bottom()) * HeapWordSize; 405 assert(used_at_mark_start_bytes >= marked_bytes(), 406 "Can't mark more than we have."); 407 return used_at_mark_start_bytes - marked_bytes(); 408 } 409 410 // Return the amount of bytes we'll reclaim if we collect this 411 // region. This includes not only the known garbage bytes in the 412 // region but also any unallocated space in it, i.e., [top, end), 413 // since it will also be reclaimed if we collect the region. 414 size_t reclaimable_bytes() { 415 size_t known_live_bytes = live_bytes(); 416 assert(known_live_bytes <= capacity(), "sanity"); 417 return capacity() - known_live_bytes; 418 } 419 420 // An upper bound on the number of live bytes in the region. 421 size_t max_live_bytes() { return used() - garbage_bytes(); } 422 423 void add_to_marked_bytes(size_t incr_bytes) { 424 _next_marked_bytes = _next_marked_bytes + incr_bytes; 425 assert(_next_marked_bytes <= used(), "invariant" ); 426 } 427 428 void zero_marked_bytes() { 429 _prev_marked_bytes = _next_marked_bytes = 0; 430 } 431 432 bool isHumongous() const { return _humongous_type != NotHumongous; } 433 bool startsHumongous() const { return _humongous_type == StartsHumongous; } 434 bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; } 435 // For a humongous region, region in which it starts. 436 HeapRegion* humongous_start_region() const { 437 return _humongous_start_region; 438 } 439 440 // Return the number of distinct regions that are covered by this region: 441 // 1 if the region is not humongous, >= 1 if the region is humongous. 442 uint region_num() const { 443 if (!isHumongous()) { 444 return 1U; 445 } else { 446 assert(startsHumongous(), "doesn't make sense on HC regions"); 447 assert(capacity() % HeapRegion::GrainBytes == 0, "sanity"); 448 return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes); 449 } 450 } 451 452 // Return the index + 1 of the last HC regions that's associated 453 // with this HS region. 454 uint last_hc_index() const { 455 assert(startsHumongous(), "don't call this otherwise"); 456 return hrs_index() + region_num(); 457 } 458 459 // Same as Space::is_in_reserved, but will use the original size of the region. 460 // The original size is different only for start humongous regions. They get 461 // their _end set up to be the end of the last continues region of the 462 // corresponding humongous object. 463 bool is_in_reserved_raw(const void* p) const { 464 return _bottom <= p && p < _orig_end; 465 } 466 467 // Makes the current region be a "starts humongous" region, i.e., 468 // the first region in a series of one or more contiguous regions 469 // that will contain a single "humongous" object. The two parameters 470 // are as follows: 471 // 472 // new_top : The new value of the top field of this region which 473 // points to the end of the humongous object that's being 474 // allocated. If there is more than one region in the series, top 475 // will lie beyond this region's original end field and on the last 476 // region in the series. 477 // 478 // new_end : The new value of the end field of this region which 479 // points to the end of the last region in the series. If there is 480 // one region in the series (namely: this one) end will be the same 481 // as the original end of this region. 482 // 483 // Updating top and end as described above makes this region look as 484 // if it spans the entire space taken up by all the regions in the 485 // series and an single allocation moved its top to new_top. This 486 // ensures that the space (capacity / allocated) taken up by all 487 // humongous regions can be calculated by just looking at the 488 // "starts humongous" regions and by ignoring the "continues 489 // humongous" regions. 490 void set_startsHumongous(HeapWord* new_top, HeapWord* new_end); 491 492 // Makes the current region be a "continues humongous' 493 // region. first_hr is the "start humongous" region of the series 494 // which this region will be part of. 495 void set_continuesHumongous(HeapRegion* first_hr); 496 497 // Unsets the humongous-related fields on the region. 498 void set_notHumongous(); 499 500 // If the region has a remembered set, return a pointer to it. 501 HeapRegionRemSet* rem_set() const { 502 return _rem_set; 503 } 504 505 // True iff the region is in current collection_set. 506 bool in_collection_set() const { 507 return _in_collection_set; 508 } 509 void set_in_collection_set(bool b) { 510 _in_collection_set = b; 511 } 512 HeapRegion* next_in_collection_set() { 513 assert(in_collection_set(), "should only invoke on member of CS."); 514 assert(_next_in_special_set == NULL || 515 _next_in_special_set->in_collection_set(), 516 "Malformed CS."); 517 return _next_in_special_set; 518 } 519 void set_next_in_collection_set(HeapRegion* r) { 520 assert(in_collection_set(), "should only invoke on member of CS."); 521 assert(r == NULL || r->in_collection_set(), "Malformed CS."); 522 _next_in_special_set = r; 523 } 524 525 // Methods used by the HeapRegionSetBase class and subclasses. 526 527 // Getter and setter for the next and prev fields used to link regions into 528 // linked lists. 529 HeapRegion* next() { return _next; } 530 HeapRegion* prev() { return _prev; } 531 532 void set_next(HeapRegion* next) { _next = next; } 533 void set_prev(HeapRegion* prev) { _prev = prev; } 534 535 // Every region added to a set is tagged with a reference to that 536 // set. This is used for doing consistency checking to make sure that 537 // the contents of a set are as they should be and it's only 538 // available in non-product builds. 539 #ifdef ASSERT 540 void set_containing_set(HeapRegionSetBase* containing_set) { 541 assert((containing_set == NULL && _containing_set != NULL) || 542 (containing_set != NULL && _containing_set == NULL), 543 err_msg("containing_set: "PTR_FORMAT" " 544 "_containing_set: "PTR_FORMAT, 545 p2i(containing_set), p2i(_containing_set))); 546 547 _containing_set = containing_set; 548 } 549 550 HeapRegionSetBase* containing_set() { return _containing_set; } 551 #else // ASSERT 552 void set_containing_set(HeapRegionSetBase* containing_set) { } 553 554 // containing_set() is only used in asserts so there's no reason 555 // to provide a dummy version of it. 556 #endif // ASSERT 557 558 // If we want to remove regions from a list in bulk we can simply tag 559 // them with the pending_removal tag and call the 560 // remove_all_pending() method on the list. 561 562 bool pending_removal() { return _pending_removal; } 563 564 void set_pending_removal(bool pending_removal) { 565 if (pending_removal) { 566 assert(!_pending_removal && containing_set() != NULL, 567 "can only set pending removal to true if it's false and " 568 "the region belongs to a region set"); 569 } else { 570 assert( _pending_removal && containing_set() == NULL, 571 "can only set pending removal to false if it's true and " 572 "the region does not belong to a region set"); 573 } 574 575 _pending_removal = pending_removal; 576 } 577 578 HeapRegion* get_next_young_region() { return _next_young_region; } 579 void set_next_young_region(HeapRegion* hr) { 580 _next_young_region = hr; 581 } 582 583 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; } 584 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; } 585 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; } 586 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; } 587 588 HeapWord* orig_end() { return _orig_end; } 589 590 // Reset HR stuff to default values. 591 void hr_clear(bool par, bool clear_space, bool locked = false); 592 void par_clear(); 593 594 // Get the start of the unmarked area in this region. 595 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; } 596 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; } 597 598 // Note the start or end of marking. This tells the heap region 599 // that the collector is about to start or has finished (concurrently) 600 // marking the heap. 601 602 // Notify the region that concurrent marking is starting. Initialize 603 // all fields related to the next marking info. 604 inline void note_start_of_marking(); 605 606 // Notify the region that concurrent marking has finished. Copy the 607 // (now finalized) next marking info fields into the prev marking 608 // info fields. 609 inline void note_end_of_marking(); 610 611 // Notify the region that it will be used as to-space during a GC 612 // and we are about to start copying objects into it. 613 inline void note_start_of_copying(bool during_initial_mark); 614 615 // Notify the region that it ceases being to-space during a GC and 616 // we will not copy objects into it any more. 617 inline void note_end_of_copying(bool during_initial_mark); 618 619 // Notify the region that we are about to start processing 620 // self-forwarded objects during evac failure handling. 621 void note_self_forwarding_removal_start(bool during_initial_mark, 622 bool during_conc_mark); 623 624 // Notify the region that we have finished processing self-forwarded 625 // objects during evac failure handling. 626 void note_self_forwarding_removal_end(bool during_initial_mark, 627 bool during_conc_mark, 628 size_t marked_bytes); 629 630 // Returns "false" iff no object in the region was allocated when the 631 // last mark phase ended. 632 bool is_marked() { return _prev_top_at_mark_start != bottom(); } 633 634 void reset_during_compaction() { 635 assert(isHumongous() && startsHumongous(), 636 "should only be called for starts humongous regions"); 637 638 zero_marked_bytes(); 639 init_top_at_mark_start(); 640 } 641 642 void calc_gc_efficiency(void); 643 double gc_efficiency() { return _gc_efficiency;} 644 645 bool is_young() const { return _young_type != NotYoung; } 646 bool is_survivor() const { return _young_type == Survivor; } 647 648 int young_index_in_cset() const { return _young_index_in_cset; } 649 void set_young_index_in_cset(int index) { 650 assert( (index == -1) || is_young(), "pre-condition" ); 651 _young_index_in_cset = index; 652 } 653 654 int age_in_surv_rate_group() { 655 assert( _surv_rate_group != NULL, "pre-condition" ); 656 assert( _age_index > -1, "pre-condition" ); 657 return _surv_rate_group->age_in_group(_age_index); 658 } 659 660 void record_surv_words_in_group(size_t words_survived) { 661 assert( _surv_rate_group != NULL, "pre-condition" ); 662 assert( _age_index > -1, "pre-condition" ); 663 int age_in_group = age_in_surv_rate_group(); 664 _surv_rate_group->record_surviving_words(age_in_group, words_survived); 665 } 666 667 int age_in_surv_rate_group_cond() { 668 if (_surv_rate_group != NULL) 669 return age_in_surv_rate_group(); 670 else 671 return -1; 672 } 673 674 SurvRateGroup* surv_rate_group() { 675 return _surv_rate_group; 676 } 677 678 void install_surv_rate_group(SurvRateGroup* surv_rate_group) { 679 assert( surv_rate_group != NULL, "pre-condition" ); 680 assert( _surv_rate_group == NULL, "pre-condition" ); 681 assert( is_young(), "pre-condition" ); 682 683 _surv_rate_group = surv_rate_group; 684 _age_index = surv_rate_group->next_age_index(); 685 } 686 687 void uninstall_surv_rate_group() { 688 if (_surv_rate_group != NULL) { 689 assert( _age_index > -1, "pre-condition" ); 690 assert( is_young(), "pre-condition" ); 691 692 _surv_rate_group = NULL; 693 _age_index = -1; 694 } else { 695 assert( _age_index == -1, "pre-condition" ); 696 } 697 } 698 699 void set_young() { set_young_type(Young); } 700 701 void set_survivor() { set_young_type(Survivor); } 702 703 void set_not_young() { set_young_type(NotYoung); } 704 705 // Determine if an object has been allocated since the last 706 // mark performed by the collector. This returns true iff the object 707 // is within the unmarked area of the region. 708 bool obj_allocated_since_prev_marking(oop obj) const { 709 return (HeapWord *) obj >= prev_top_at_mark_start(); 710 } 711 bool obj_allocated_since_next_marking(oop obj) const { 712 return (HeapWord *) obj >= next_top_at_mark_start(); 713 } 714 715 // For parallel heapRegion traversal. 716 bool claimHeapRegion(int claimValue); 717 jint claim_value() { return _claimed; } 718 // Use this carefully: only when you're sure no one is claiming... 719 void set_claim_value(int claimValue) { _claimed = claimValue; } 720 721 // Returns the "evacuation_failed" property of the region. 722 bool evacuation_failed() { return _evacuation_failed; } 723 724 // Sets the "evacuation_failed" property of the region. 725 void set_evacuation_failed(bool b) { 726 _evacuation_failed = b; 727 728 if (b) { 729 _next_marked_bytes = 0; 730 } 731 } 732 733 // Requires that "mr" be entirely within the region. 734 // Apply "cl->do_object" to all objects that intersect with "mr". 735 // If the iteration encounters an unparseable portion of the region, 736 // or if "cl->abort()" is true after a closure application, 737 // terminate the iteration and return the address of the start of the 738 // subregion that isn't done. (The two can be distinguished by querying 739 // "cl->abort()".) Return of "NULL" indicates that the iteration 740 // completed. 741 HeapWord* 742 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl); 743 744 // filter_young: if true and the region is a young region then we 745 // skip the iteration. 746 // card_ptr: if not NULL, and we decide that the card is not young 747 // and we iterate over it, we'll clean the card before we start the 748 // iteration. 749 HeapWord* 750 oops_on_card_seq_iterate_careful(MemRegion mr, 751 FilterOutOfRegionClosure* cl, 752 bool filter_young, 753 jbyte* card_ptr); 754 755 // A version of block start that is guaranteed to find *some* block 756 // boundary at or before "p", but does not object iteration, and may 757 // therefore be used safely when the heap is unparseable. 758 HeapWord* block_start_careful(const void* p) const { 759 return _offsets.block_start_careful(p); 760 } 761 762 // Requires that "addr" is within the region. Returns the start of the 763 // first ("careful") block that starts at or after "addr", or else the 764 // "end" of the region if there is no such block. 765 HeapWord* next_block_start_careful(HeapWord* addr); 766 767 size_t recorded_rs_length() const { return _recorded_rs_length; } 768 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; } 769 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; } 770 771 void set_recorded_rs_length(size_t rs_length) { 772 _recorded_rs_length = rs_length; 773 } 774 775 void set_predicted_elapsed_time_ms(double ms) { 776 _predicted_elapsed_time_ms = ms; 777 } 778 779 void set_predicted_bytes_to_copy(size_t bytes) { 780 _predicted_bytes_to_copy = bytes; 781 } 782 783 virtual CompactibleSpace* next_compaction_space() const; 784 785 virtual void reset_after_compaction(); 786 787 // Routines for managing a list of code roots (attached to the 788 // this region's RSet) that point into this heap region. 789 void add_strong_code_root(nmethod* nm); 790 void remove_strong_code_root(nmethod* nm); 791 792 // During a collection, migrate the successfully evacuated 793 // strong code roots that referenced into this region to the 794 // new regions that they now point into. Unsuccessfully 795 // evacuated code roots are not migrated. 796 void migrate_strong_code_roots(); 797 798 // Applies blk->do_code_blob() to each of the entries in 799 // the strong code roots list for this region 800 void strong_code_roots_do(CodeBlobClosure* blk) const; 801 802 // Verify that the entries on the strong code root list for this 803 // region are live and include at least one pointer into this region. 804 void verify_strong_code_roots(VerifyOption vo, bool* failures) const; 805 806 void print() const; 807 void print_on(outputStream* st) const; 808 809 // vo == UsePrevMarking -> use "prev" marking information, 810 // vo == UseNextMarking -> use "next" marking information 811 // vo == UseMarkWord -> use the mark word in the object header 812 // 813 // NOTE: Only the "prev" marking information is guaranteed to be 814 // consistent most of the time, so most calls to this should use 815 // vo == UsePrevMarking. 816 // Currently, there is only one case where this is called with 817 // vo == UseNextMarking, which is to verify the "next" marking 818 // information at the end of remark. 819 // Currently there is only one place where this is called with 820 // vo == UseMarkWord, which is to verify the marking during a 821 // full GC. 822 void verify(VerifyOption vo, bool *failures) const; 823 824 // Override; it uses the "prev" marking information 825 virtual void verify() const; 826 }; 827 828 // HeapRegionClosure is used for iterating over regions. 829 // Terminates the iteration when the "doHeapRegion" method returns "true". 830 class HeapRegionClosure : public StackObj { 831 friend class HeapRegionSeq; 832 friend class G1CollectedHeap; 833 834 bool _complete; 835 void incomplete() { _complete = false; } 836 837 public: 838 HeapRegionClosure(): _complete(true) {} 839 840 // Typically called on each region until it returns true. 841 virtual bool doHeapRegion(HeapRegion* r) = 0; 842 843 // True after iteration if the closure was applied to all heap regions 844 // and returned "false" in all cases. 845 bool complete() { return _complete; } 846 }; 847 848 #endif // INCLUDE_ALL_GCS 849 850 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP