1 /* 2 * Copyright (c) 2001, 2013, 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.inline.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 CompactibleSpace; 50 class ContiguousSpace; 51 class HeapRegionRemSet; 52 class HeapRegionRemSetIterator; 53 class HeapRegion; 54 class HeapRegionSetBase; 55 class nmethod; 56 57 #define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]" 58 #define HR_FORMAT_PARAMS(_hr_) \ 59 (_hr_)->hrs_index(), \ 60 (_hr_)->is_survivor() ? "S" : (_hr_)->is_young() ? "E" : \ 61 (_hr_)->startsHumongous() ? "HS" : \ 62 (_hr_)->continuesHumongous() ? "HC" : \ 63 !(_hr_)->is_empty() ? "O" : "F", \ 64 (_hr_)->bottom(), (_hr_)->top(), (_hr_)->end() 65 66 // sentinel value for hrs_index 67 #define G1_NULL_HRS_INDEX ((uint) -1) 68 69 // A dirty card to oop closure for heap regions. It 70 // knows how to get the G1 heap and how to use the bitmap 71 // in the concurrent marker used by G1 to filter remembered 72 // sets. 73 74 class HeapRegionDCTOC : public ContiguousSpaceDCTOC { 75 public: 76 // Specification of possible DirtyCardToOopClosure filtering. 77 enum FilterKind { 78 NoFilterKind, 79 IntoCSFilterKind, 80 OutOfRegionFilterKind 81 }; 82 83 protected: 84 HeapRegion* _hr; 85 FilterKind _fk; 86 G1CollectedHeap* _g1; 87 88 void walk_mem_region_with_cl(MemRegion mr, 89 HeapWord* bottom, HeapWord* top, 90 ExtendedOopClosure* cl); 91 92 // We don't specialize this for FilteringClosure; filtering is handled by 93 // the "FilterKind" mechanism. But we provide this to avoid a compiler 94 // warning. 95 void walk_mem_region_with_cl(MemRegion mr, 96 HeapWord* bottom, HeapWord* top, 97 FilteringClosure* cl) { 98 HeapRegionDCTOC::walk_mem_region_with_cl(mr, bottom, top, 99 (ExtendedOopClosure*)cl); 100 } 101 102 // Get the actual top of the area on which the closure will 103 // operate, given where the top is assumed to be (the end of the 104 // memory region passed to do_MemRegion) and where the object 105 // at the top is assumed to start. For example, an object may 106 // start at the top but actually extend past the assumed top, 107 // in which case the top becomes the end of the object. 108 HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj) { 109 return ContiguousSpaceDCTOC::get_actual_top(top, top_obj); 110 } 111 112 // Walk the given memory region from bottom to (actual) top 113 // looking for objects and applying the oop closure (_cl) to 114 // them. The base implementation of this treats the area as 115 // blocks, where a block may or may not be an object. Sub- 116 // classes should override this to provide more accurate 117 // or possibly more efficient walking. 118 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top) { 119 Filtering_DCTOC::walk_mem_region(mr, bottom, top); 120 } 121 122 public: 123 HeapRegionDCTOC(G1CollectedHeap* g1, 124 HeapRegion* hr, ExtendedOopClosure* cl, 125 CardTableModRefBS::PrecisionStyle precision, 126 FilterKind fk); 127 }; 128 129 // The complicating factor is that BlockOffsetTable diverged 130 // significantly, and we need functionality that is only in the G1 version. 131 // So I copied that code, which led to an alternate G1 version of 132 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could 133 // be reconciled, then G1OffsetTableContigSpace could go away. 134 135 // The idea behind time stamps is the following. Doing a save_marks on 136 // all regions at every GC pause is time consuming (if I remember 137 // well, 10ms or so). So, we would like to do that only for regions 138 // that are GC alloc regions. To achieve this, we use time 139 // stamps. For every evacuation pause, G1CollectedHeap generates a 140 // unique time stamp (essentially a counter that gets 141 // incremented). Every time we want to call save_marks on a region, 142 // we set the saved_mark_word to top and also copy the current GC 143 // time stamp to the time stamp field of the space. Reading the 144 // saved_mark_word involves checking the time stamp of the 145 // region. If it is the same as the current GC time stamp, then we 146 // can safely read the saved_mark_word field, as it is valid. If the 147 // time stamp of the region is not the same as the current GC time 148 // stamp, then we instead read top, as the saved_mark_word field is 149 // invalid. Time stamps (on the regions and also on the 150 // G1CollectedHeap) are reset at every cleanup (we iterate over 151 // the regions anyway) and at the end of a Full GC. The current scheme 152 // that uses sequential unsigned ints will fail only if we have 4b 153 // evacuation pauses between two cleanups, which is _highly_ unlikely. 154 155 class G1OffsetTableContigSpace: public ContiguousSpace { 156 friend class VMStructs; 157 protected: 158 G1BlockOffsetArrayContigSpace _offsets; 159 Mutex _par_alloc_lock; 160 volatile unsigned _gc_time_stamp; 161 // When we need to retire an allocation region, while other threads 162 // are also concurrently trying to allocate into it, we typically 163 // allocate a dummy object at the end of the region to ensure that 164 // no more allocations can take place in it. However, sometimes we 165 // want to know where the end of the last "real" object we allocated 166 // into the region was and this is what this keeps track. 167 HeapWord* _pre_dummy_top; 168 169 public: 170 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray, 171 MemRegion mr); 172 173 void set_bottom(HeapWord* value); 174 void set_end(HeapWord* value); 175 176 virtual HeapWord* saved_mark_word() const; 177 virtual void set_saved_mark(); 178 void reset_gc_time_stamp() { _gc_time_stamp = 0; } 179 unsigned get_gc_time_stamp() { return _gc_time_stamp; } 180 181 // See the comment above in the declaration of _pre_dummy_top for an 182 // explanation of what it is. 183 void set_pre_dummy_top(HeapWord* pre_dummy_top) { 184 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition"); 185 _pre_dummy_top = pre_dummy_top; 186 } 187 HeapWord* pre_dummy_top() { 188 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top; 189 } 190 void reset_pre_dummy_top() { _pre_dummy_top = NULL; } 191 192 virtual void clear(bool mangle_space); 193 194 HeapWord* block_start(const void* p); 195 HeapWord* block_start_const(const void* p) const; 196 197 // Add offset table update. 198 virtual HeapWord* allocate(size_t word_size); 199 HeapWord* par_allocate(size_t word_size); 200 201 // MarkSweep support phase3 202 virtual HeapWord* initialize_threshold(); 203 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end); 204 205 virtual void print() const; 206 207 void reset_bot() { 208 _offsets.zero_bottom_entry(); 209 _offsets.initialize_threshold(); 210 } 211 212 void update_bot_for_object(HeapWord* start, size_t word_size) { 213 _offsets.alloc_block(start, word_size); 214 } 215 216 void print_bot_on(outputStream* out) { 217 _offsets.print_on(out); 218 } 219 }; 220 221 class HeapRegion: public G1OffsetTableContigSpace { 222 friend class VMStructs; 223 private: 224 225 enum HumongousType { 226 NotHumongous = 0, 227 StartsHumongous, 228 ContinuesHumongous 229 }; 230 231 // Requires that the region "mr" be dense with objects, and begin and end 232 // with an object. 233 void oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl); 234 235 // The remembered set for this region. 236 // (Might want to make this "inline" later, to avoid some alloc failure 237 // issues.) 238 HeapRegionRemSet* _rem_set; 239 240 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; } 241 242 protected: 243 // The index of this region in the heap region sequence. 244 uint _hrs_index; 245 246 HumongousType _humongous_type; 247 // For a humongous region, region in which it starts. 248 HeapRegion* _humongous_start_region; 249 // For the start region of a humongous sequence, it's original end(). 250 HeapWord* _orig_end; 251 252 // True iff the region is in current collection_set. 253 bool _in_collection_set; 254 255 // True iff an attempt to evacuate an object in the region failed. 256 bool _evacuation_failed; 257 258 // A heap region may be a member one of a number of special subsets, each 259 // represented as linked lists through the field below. Currently, these 260 // sets include: 261 // The collection set. 262 // The set of allocation regions used in a collection pause. 263 // Spaces that may contain gray objects. 264 HeapRegion* _next_in_special_set; 265 266 // next region in the young "generation" region set 267 HeapRegion* _next_young_region; 268 269 // Next region whose cards need cleaning 270 HeapRegion* _next_dirty_cards_region; 271 272 // Fields used by the HeapRegionSetBase class and subclasses. 273 HeapRegion* _next; 274 #ifdef ASSERT 275 HeapRegionSetBase* _containing_set; 276 #endif // ASSERT 277 bool _pending_removal; 278 279 // For parallel heapRegion traversal. 280 jint _claimed; 281 282 // We use concurrent marking to determine the amount of live data 283 // in each heap region. 284 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking. 285 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking. 286 287 // The calculated GC efficiency of the region. 288 double _gc_efficiency; 289 290 enum YoungType { 291 NotYoung, // a region is not young 292 Young, // a region is young 293 Survivor // a region is young and it contains survivors 294 }; 295 296 volatile YoungType _young_type; 297 int _young_index_in_cset; 298 SurvRateGroup* _surv_rate_group; 299 int _age_index; 300 301 // The start of the unmarked area. The unmarked area extends from this 302 // word until the top and/or end of the region, and is the part 303 // of the region for which no marking was done, i.e. objects may 304 // have been allocated in this part since the last mark phase. 305 // "prev" is the top at the start of the last completed marking. 306 // "next" is the top at the start of the in-progress marking (if any.) 307 HeapWord* _prev_top_at_mark_start; 308 HeapWord* _next_top_at_mark_start; 309 // If a collection pause is in progress, this is the top at the start 310 // of that pause. 311 312 void init_top_at_mark_start() { 313 assert(_prev_marked_bytes == 0 && 314 _next_marked_bytes == 0, 315 "Must be called after zero_marked_bytes."); 316 HeapWord* bot = bottom(); 317 _prev_top_at_mark_start = bot; 318 _next_top_at_mark_start = bot; 319 } 320 321 void set_young_type(YoungType new_type) { 322 //assert(_young_type != new_type, "setting the same type" ); 323 // TODO: add more assertions here 324 _young_type = new_type; 325 } 326 327 // Cached attributes used in the collection set policy information 328 329 // The RSet length that was added to the total value 330 // for the collection set. 331 size_t _recorded_rs_length; 332 333 // The predicted elapsed time that was added to total value 334 // for the collection set. 335 double _predicted_elapsed_time_ms; 336 337 // The predicted number of bytes to copy that was added to 338 // the total value for the collection set. 339 size_t _predicted_bytes_to_copy; 340 341 public: 342 HeapRegion(uint hrs_index, 343 G1BlockOffsetSharedArray* sharedOffsetArray, 344 MemRegion mr); 345 346 static int LogOfHRGrainBytes; 347 static int LogOfHRGrainWords; 348 349 static size_t GrainBytes; 350 static size_t GrainWords; 351 static size_t CardsPerRegion; 352 353 static size_t align_up_to_region_byte_size(size_t sz) { 354 return (sz + (size_t) GrainBytes - 1) & 355 ~((1 << (size_t) LogOfHRGrainBytes) - 1); 356 } 357 358 static size_t max_region_size(); 359 360 // It sets up the heap region size (GrainBytes / GrainWords), as 361 // well as other related fields that are based on the heap region 362 // size (LogOfHRGrainBytes / LogOfHRGrainWords / 363 // CardsPerRegion). All those fields are considered constant 364 // throughout the JVM's execution, therefore they should only be set 365 // up once during initialization time. 366 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size); 367 368 enum ClaimValues { 369 InitialClaimValue = 0, 370 FinalCountClaimValue = 1, 371 NoteEndClaimValue = 2, 372 ScrubRemSetClaimValue = 3, 373 ParVerifyClaimValue = 4, 374 RebuildRSClaimValue = 5, 375 ParEvacFailureClaimValue = 6, 376 AggregateCountClaimValue = 7, 377 VerifyCountClaimValue = 8, 378 ParMarkRootClaimValue = 9 379 }; 380 381 inline HeapWord* par_allocate_no_bot_updates(size_t word_size) { 382 assert(is_young(), "we can only skip BOT updates on young regions"); 383 return ContiguousSpace::par_allocate(word_size); 384 } 385 inline HeapWord* allocate_no_bot_updates(size_t word_size) { 386 assert(is_young(), "we can only skip BOT updates on young regions"); 387 return ContiguousSpace::allocate(word_size); 388 } 389 390 // If this region is a member of a HeapRegionSeq, the index in that 391 // sequence, otherwise -1. 392 uint hrs_index() const { return _hrs_index; } 393 394 // The number of bytes marked live in the region in the last marking phase. 395 size_t marked_bytes() { return _prev_marked_bytes; } 396 size_t live_bytes() { 397 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes(); 398 } 399 400 // The number of bytes counted in the next marking. 401 size_t next_marked_bytes() { return _next_marked_bytes; } 402 // The number of bytes live wrt the next marking. 403 size_t next_live_bytes() { 404 return 405 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes(); 406 } 407 408 // A lower bound on the amount of garbage bytes in the region. 409 size_t garbage_bytes() { 410 size_t used_at_mark_start_bytes = 411 (prev_top_at_mark_start() - bottom()) * HeapWordSize; 412 assert(used_at_mark_start_bytes >= marked_bytes(), 413 "Can't mark more than we have."); 414 return used_at_mark_start_bytes - marked_bytes(); 415 } 416 417 // Return the amount of bytes we'll reclaim if we collect this 418 // region. This includes not only the known garbage bytes in the 419 // region but also any unallocated space in it, i.e., [top, end), 420 // since it will also be reclaimed if we collect the region. 421 size_t reclaimable_bytes() { 422 size_t known_live_bytes = live_bytes(); 423 assert(known_live_bytes <= capacity(), "sanity"); 424 return capacity() - known_live_bytes; 425 } 426 427 // An upper bound on the number of live bytes in the region. 428 size_t max_live_bytes() { return used() - garbage_bytes(); } 429 430 void add_to_marked_bytes(size_t incr_bytes) { 431 _next_marked_bytes = _next_marked_bytes + incr_bytes; 432 assert(_next_marked_bytes <= used(), "invariant" ); 433 } 434 435 void zero_marked_bytes() { 436 _prev_marked_bytes = _next_marked_bytes = 0; 437 } 438 439 bool isHumongous() const { return _humongous_type != NotHumongous; } 440 bool startsHumongous() const { return _humongous_type == StartsHumongous; } 441 bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; } 442 // For a humongous region, region in which it starts. 443 HeapRegion* humongous_start_region() const { 444 return _humongous_start_region; 445 } 446 447 // Return the number of distinct regions that are covered by this region: 448 // 1 if the region is not humongous, >= 1 if the region is humongous. 449 uint region_num() const { 450 if (!isHumongous()) { 451 return 1U; 452 } else { 453 assert(startsHumongous(), "doesn't make sense on HC regions"); 454 assert(capacity() % HeapRegion::GrainBytes == 0, "sanity"); 455 return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes); 456 } 457 } 458 459 // Return the index + 1 of the last HC regions that's associated 460 // with this HS region. 461 uint last_hc_index() const { 462 assert(startsHumongous(), "don't call this otherwise"); 463 return hrs_index() + region_num(); 464 } 465 466 // Same as Space::is_in_reserved, but will use the original size of the region. 467 // The original size is different only for start humongous regions. They get 468 // their _end set up to be the end of the last continues region of the 469 // corresponding humongous object. 470 bool is_in_reserved_raw(const void* p) const { 471 return _bottom <= p && p < _orig_end; 472 } 473 474 // Makes the current region be a "starts humongous" region, i.e., 475 // the first region in a series of one or more contiguous regions 476 // that will contain a single "humongous" object. The two parameters 477 // are as follows: 478 // 479 // new_top : The new value of the top field of this region which 480 // points to the end of the humongous object that's being 481 // allocated. If there is more than one region in the series, top 482 // will lie beyond this region's original end field and on the last 483 // region in the series. 484 // 485 // new_end : The new value of the end field of this region which 486 // points to the end of the last region in the series. If there is 487 // one region in the series (namely: this one) end will be the same 488 // as the original end of this region. 489 // 490 // Updating top and end as described above makes this region look as 491 // if it spans the entire space taken up by all the regions in the 492 // series and an single allocation moved its top to new_top. This 493 // ensures that the space (capacity / allocated) taken up by all 494 // humongous regions can be calculated by just looking at the 495 // "starts humongous" regions and by ignoring the "continues 496 // humongous" regions. 497 void set_startsHumongous(HeapWord* new_top, HeapWord* new_end); 498 499 // Makes the current region be a "continues humongous' 500 // region. first_hr is the "start humongous" region of the series 501 // which this region will be part of. 502 void set_continuesHumongous(HeapRegion* first_hr); 503 504 // Unsets the humongous-related fields on the region. 505 void set_notHumongous(); 506 507 // If the region has a remembered set, return a pointer to it. 508 HeapRegionRemSet* rem_set() const { 509 return _rem_set; 510 } 511 512 // True iff the region is in current collection_set. 513 bool in_collection_set() const { 514 return _in_collection_set; 515 } 516 void set_in_collection_set(bool b) { 517 _in_collection_set = b; 518 } 519 HeapRegion* next_in_collection_set() { 520 assert(in_collection_set(), "should only invoke on member of CS."); 521 assert(_next_in_special_set == NULL || 522 _next_in_special_set->in_collection_set(), 523 "Malformed CS."); 524 return _next_in_special_set; 525 } 526 void set_next_in_collection_set(HeapRegion* r) { 527 assert(in_collection_set(), "should only invoke on member of CS."); 528 assert(r == NULL || r->in_collection_set(), "Malformed CS."); 529 _next_in_special_set = r; 530 } 531 532 // Methods used by the HeapRegionSetBase class and subclasses. 533 534 // Getter and setter for the next field used to link regions into 535 // linked lists. 536 HeapRegion* next() { return _next; } 537 538 void set_next(HeapRegion* next) { _next = next; } 539 540 // Every region added to a set is tagged with a reference to that 541 // set. This is used for doing consistency checking to make sure that 542 // the contents of a set are as they should be and it's only 543 // available in non-product builds. 544 #ifdef ASSERT 545 void set_containing_set(HeapRegionSetBase* containing_set) { 546 assert((containing_set == NULL && _containing_set != NULL) || 547 (containing_set != NULL && _containing_set == NULL), 548 err_msg("containing_set: "PTR_FORMAT" " 549 "_containing_set: "PTR_FORMAT, 550 containing_set, _containing_set)); 551 552 _containing_set = containing_set; 553 } 554 555 HeapRegionSetBase* containing_set() { return _containing_set; } 556 #else // ASSERT 557 void set_containing_set(HeapRegionSetBase* containing_set) { } 558 559 // containing_set() is only used in asserts so there's no reason 560 // to provide a dummy version of it. 561 #endif // ASSERT 562 563 // If we want to remove regions from a list in bulk we can simply tag 564 // them with the pending_removal tag and call the 565 // remove_all_pending() method on the list. 566 567 bool pending_removal() { return _pending_removal; } 568 569 void set_pending_removal(bool pending_removal) { 570 if (pending_removal) { 571 assert(!_pending_removal && containing_set() != NULL, 572 "can only set pending removal to true if it's false and " 573 "the region belongs to a region set"); 574 } else { 575 assert( _pending_removal && containing_set() == NULL, 576 "can only set pending removal to false if it's true and " 577 "the region does not belong to a region set"); 578 } 579 580 _pending_removal = pending_removal; 581 } 582 583 HeapRegion* get_next_young_region() { return _next_young_region; } 584 void set_next_young_region(HeapRegion* hr) { 585 _next_young_region = hr; 586 } 587 588 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; } 589 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; } 590 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; } 591 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; } 592 593 HeapWord* orig_end() { return _orig_end; } 594 595 // Allows logical separation between objects allocated before and after. 596 void save_marks(); 597 598 // Reset HR stuff to default values. 599 void hr_clear(bool par, bool clear_space, bool locked = false); 600 void par_clear(); 601 602 // Get the start of the unmarked area in this region. 603 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; } 604 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; } 605 606 // Apply "cl->do_oop" to (the addresses of) all reference fields in objects 607 // allocated in the current region before the last call to "save_mark". 608 void oop_before_save_marks_iterate(ExtendedOopClosure* cl); 609 610 // Note the start or end of marking. This tells the heap region 611 // that the collector is about to start or has finished (concurrently) 612 // marking the heap. 613 614 // Notify the region that concurrent marking is starting. Initialize 615 // all fields related to the next marking info. 616 inline void note_start_of_marking(); 617 618 // Notify the region that concurrent marking has finished. Copy the 619 // (now finalized) next marking info fields into the prev marking 620 // info fields. 621 inline void note_end_of_marking(); 622 623 // Notify the region that it will be used as to-space during a GC 624 // and we are about to start copying objects into it. 625 inline void note_start_of_copying(bool during_initial_mark); 626 627 // Notify the region that it ceases being to-space during a GC and 628 // we will not copy objects into it any more. 629 inline void note_end_of_copying(bool during_initial_mark); 630 631 // Notify the region that we are about to start processing 632 // self-forwarded objects during evac failure handling. 633 void note_self_forwarding_removal_start(bool during_initial_mark, 634 bool during_conc_mark); 635 636 // Notify the region that we have finished processing self-forwarded 637 // objects during evac failure handling. 638 void note_self_forwarding_removal_end(bool during_initial_mark, 639 bool during_conc_mark, 640 size_t marked_bytes); 641 642 // Returns "false" iff no object in the region was allocated when the 643 // last mark phase ended. 644 bool is_marked() { return _prev_top_at_mark_start != bottom(); } 645 646 void reset_during_compaction() { 647 assert(isHumongous() && startsHumongous(), 648 "should only be called for starts humongous regions"); 649 650 zero_marked_bytes(); 651 init_top_at_mark_start(); 652 } 653 654 void calc_gc_efficiency(void); 655 double gc_efficiency() { return _gc_efficiency;} 656 657 bool is_young() const { return _young_type != NotYoung; } 658 bool is_survivor() const { return _young_type == Survivor; } 659 660 int young_index_in_cset() const { return _young_index_in_cset; } 661 void set_young_index_in_cset(int index) { 662 assert( (index == -1) || is_young(), "pre-condition" ); 663 _young_index_in_cset = index; 664 } 665 666 int age_in_surv_rate_group() { 667 assert( _surv_rate_group != NULL, "pre-condition" ); 668 assert( _age_index > -1, "pre-condition" ); 669 return _surv_rate_group->age_in_group(_age_index); 670 } 671 672 void record_surv_words_in_group(size_t words_survived) { 673 assert( _surv_rate_group != NULL, "pre-condition" ); 674 assert( _age_index > -1, "pre-condition" ); 675 int age_in_group = age_in_surv_rate_group(); 676 _surv_rate_group->record_surviving_words(age_in_group, words_survived); 677 } 678 679 int age_in_surv_rate_group_cond() { 680 if (_surv_rate_group != NULL) 681 return age_in_surv_rate_group(); 682 else 683 return -1; 684 } 685 686 SurvRateGroup* surv_rate_group() { 687 return _surv_rate_group; 688 } 689 690 void install_surv_rate_group(SurvRateGroup* surv_rate_group) { 691 assert( surv_rate_group != NULL, "pre-condition" ); 692 assert( _surv_rate_group == NULL, "pre-condition" ); 693 assert( is_young(), "pre-condition" ); 694 695 _surv_rate_group = surv_rate_group; 696 _age_index = surv_rate_group->next_age_index(); 697 } 698 699 void uninstall_surv_rate_group() { 700 if (_surv_rate_group != NULL) { 701 assert( _age_index > -1, "pre-condition" ); 702 assert( is_young(), "pre-condition" ); 703 704 _surv_rate_group = NULL; 705 _age_index = -1; 706 } else { 707 assert( _age_index == -1, "pre-condition" ); 708 } 709 } 710 711 void set_young() { set_young_type(Young); } 712 713 void set_survivor() { set_young_type(Survivor); } 714 715 void set_not_young() { set_young_type(NotYoung); } 716 717 // Determine if an object has been allocated since the last 718 // mark performed by the collector. This returns true iff the object 719 // is within the unmarked area of the region. 720 bool obj_allocated_since_prev_marking(oop obj) const { 721 return (HeapWord *) obj >= prev_top_at_mark_start(); 722 } 723 bool obj_allocated_since_next_marking(oop obj) const { 724 return (HeapWord *) obj >= next_top_at_mark_start(); 725 } 726 727 // For parallel heapRegion traversal. 728 bool claimHeapRegion(int claimValue); 729 jint claim_value() { return _claimed; } 730 // Use this carefully: only when you're sure no one is claiming... 731 void set_claim_value(int claimValue) { _claimed = claimValue; } 732 733 // Returns the "evacuation_failed" property of the region. 734 bool evacuation_failed() { return _evacuation_failed; } 735 736 // Sets the "evacuation_failed" property of the region. 737 void set_evacuation_failed(bool b) { 738 _evacuation_failed = b; 739 740 if (b) { 741 _next_marked_bytes = 0; 742 } 743 } 744 745 // Requires that "mr" be entirely within the region. 746 // Apply "cl->do_object" to all objects that intersect with "mr". 747 // If the iteration encounters an unparseable portion of the region, 748 // or if "cl->abort()" is true after a closure application, 749 // terminate the iteration and return the address of the start of the 750 // subregion that isn't done. (The two can be distinguished by querying 751 // "cl->abort()".) Return of "NULL" indicates that the iteration 752 // completed. 753 HeapWord* 754 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl); 755 756 // filter_young: if true and the region is a young region then we 757 // skip the iteration. 758 // card_ptr: if not NULL, and we decide that the card is not young 759 // and we iterate over it, we'll clean the card before we start the 760 // iteration. 761 HeapWord* 762 oops_on_card_seq_iterate_careful(MemRegion mr, 763 FilterOutOfRegionClosure* cl, 764 bool filter_young, 765 jbyte* card_ptr); 766 767 // A version of block start that is guaranteed to find *some* block 768 // boundary at or before "p", but does not object iteration, and may 769 // therefore be used safely when the heap is unparseable. 770 HeapWord* block_start_careful(const void* p) const { 771 return _offsets.block_start_careful(p); 772 } 773 774 // Requires that "addr" is within the region. Returns the start of the 775 // first ("careful") block that starts at or after "addr", or else the 776 // "end" of the region if there is no such block. 777 HeapWord* next_block_start_careful(HeapWord* addr); 778 779 size_t recorded_rs_length() const { return _recorded_rs_length; } 780 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; } 781 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; } 782 783 void set_recorded_rs_length(size_t rs_length) { 784 _recorded_rs_length = rs_length; 785 } 786 787 void set_predicted_elapsed_time_ms(double ms) { 788 _predicted_elapsed_time_ms = ms; 789 } 790 791 void set_predicted_bytes_to_copy(size_t bytes) { 792 _predicted_bytes_to_copy = bytes; 793 } 794 795 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ 796 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); 797 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DECL) 798 799 virtual CompactibleSpace* next_compaction_space() const; 800 801 virtual void reset_after_compaction(); 802 803 // Routines for managing a list of code roots (attached to the 804 // this region's RSet) that point into this heap region. 805 void add_strong_code_root(nmethod* nm); 806 void remove_strong_code_root(nmethod* nm); 807 808 // During a collection, migrate the successfully evacuated 809 // strong code roots that referenced into this region to the 810 // new regions that they now point into. Unsuccessfully 811 // evacuated code roots are not migrated. 812 void migrate_strong_code_roots(); 813 814 // Applies blk->do_code_blob() to each of the entries in 815 // the strong code roots list for this region 816 void strong_code_roots_do(CodeBlobClosure* blk) const; 817 818 // Verify that the entries on the strong code root list for this 819 // region are live and include at least one pointer into this region. 820 void verify_strong_code_roots(VerifyOption vo, bool* failures) const; 821 822 void print() const; 823 void print_on(outputStream* st) const; 824 825 // vo == UsePrevMarking -> use "prev" marking information, 826 // vo == UseNextMarking -> use "next" marking information 827 // vo == UseMarkWord -> use the mark word in the object header 828 // 829 // NOTE: Only the "prev" marking information is guaranteed to be 830 // consistent most of the time, so most calls to this should use 831 // vo == UsePrevMarking. 832 // Currently, there is only one case where this is called with 833 // vo == UseNextMarking, which is to verify the "next" marking 834 // information at the end of remark. 835 // Currently there is only one place where this is called with 836 // vo == UseMarkWord, which is to verify the marking during a 837 // full GC. 838 void verify(VerifyOption vo, bool *failures) const; 839 840 // Override; it uses the "prev" marking information 841 virtual void verify() const; 842 }; 843 844 // HeapRegionClosure is used for iterating over regions. 845 // Terminates the iteration when the "doHeapRegion" method returns "true". 846 class HeapRegionClosure : public StackObj { 847 friend class HeapRegionSeq; 848 friend class G1CollectedHeap; 849 850 bool _complete; 851 void incomplete() { _complete = false; } 852 853 public: 854 HeapRegionClosure(): _complete(true) {} 855 856 // Typically called on each region until it returns true. 857 virtual bool doHeapRegion(HeapRegion* r) = 0; 858 859 // True after iteration if the closure was applied to all heap regions 860 // and returned "false" in all cases. 861 bool complete() { return _complete; } 862 }; 863 864 #endif // INCLUDE_ALL_GCS 865 866 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP