1 /* 2 * Copyright (c) 2001, 2012, 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 // A list of code blobs (nmethods) whose code contains pointers into this region 342 GrowableArray<nmethod*>* _strong_code_root_list; 343 344 public: 345 HeapRegion(uint hrs_index, 346 G1BlockOffsetSharedArray* sharedOffsetArray, 347 MemRegion mr); 348 349 static int LogOfHRGrainBytes; 350 static int LogOfHRGrainWords; 351 352 static size_t GrainBytes; 353 static size_t GrainWords; 354 static size_t CardsPerRegion; 355 356 static size_t align_up_to_region_byte_size(size_t sz) { 357 return (sz + (size_t) GrainBytes - 1) & 358 ~((1 << (size_t) LogOfHRGrainBytes) - 1); 359 } 360 361 // It sets up the heap region size (GrainBytes / GrainWords), as 362 // well as other related fields that are based on the heap region 363 // size (LogOfHRGrainBytes / LogOfHRGrainWords / 364 // CardsPerRegion). All those fields are considered constant 365 // throughout the JVM's execution, therefore they should only be set 366 // up once during initialization time. 367 static void setup_heap_region_size(uintx min_heap_size); 368 369 enum ClaimValues { 370 InitialClaimValue = 0, 371 FinalCountClaimValue = 1, 372 NoteEndClaimValue = 2, 373 ScrubRemSetClaimValue = 3, 374 ParVerifyClaimValue = 4, 375 RebuildRSClaimValue = 5, 376 ParEvacFailureClaimValue = 6, 377 AggregateCountClaimValue = 7, 378 VerifyCountClaimValue = 8, 379 ParMarkRootClaimValue = 9 380 }; 381 382 inline HeapWord* par_allocate_no_bot_updates(size_t word_size) { 383 assert(is_young(), "we can only skip BOT updates on young regions"); 384 return ContiguousSpace::par_allocate(word_size); 385 } 386 inline HeapWord* allocate_no_bot_updates(size_t word_size) { 387 assert(is_young(), "we can only skip BOT updates on young regions"); 388 return ContiguousSpace::allocate(word_size); 389 } 390 391 // If this region is a member of a HeapRegionSeq, the index in that 392 // sequence, otherwise -1. 393 uint hrs_index() const { return _hrs_index; } 394 395 // The number of bytes marked live in the region in the last marking phase. 396 size_t marked_bytes() { return _prev_marked_bytes; } 397 size_t live_bytes() { 398 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes(); 399 } 400 401 // The number of bytes counted in the next marking. 402 size_t next_marked_bytes() { return _next_marked_bytes; } 403 // The number of bytes live wrt the next marking. 404 size_t next_live_bytes() { 405 return 406 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes(); 407 } 408 409 // A lower bound on the amount of garbage bytes in the region. 410 size_t garbage_bytes() { 411 size_t used_at_mark_start_bytes = 412 (prev_top_at_mark_start() - bottom()) * HeapWordSize; 413 assert(used_at_mark_start_bytes >= marked_bytes(), 414 "Can't mark more than we have."); 415 return used_at_mark_start_bytes - marked_bytes(); 416 } 417 418 // Return the amount of bytes we'll reclaim if we collect this 419 // region. This includes not only the known garbage bytes in the 420 // region but also any unallocated space in it, i.e., [top, end), 421 // since it will also be reclaimed if we collect the region. 422 size_t reclaimable_bytes() { 423 size_t known_live_bytes = live_bytes(); 424 assert(known_live_bytes <= capacity(), "sanity"); 425 return capacity() - known_live_bytes; 426 } 427 428 // An upper bound on the number of live bytes in the region. 429 size_t max_live_bytes() { return used() - garbage_bytes(); } 430 431 void add_to_marked_bytes(size_t incr_bytes) { 432 _next_marked_bytes = _next_marked_bytes + incr_bytes; 433 assert(_next_marked_bytes <= used(), "invariant" ); 434 } 435 436 void zero_marked_bytes() { 437 _prev_marked_bytes = _next_marked_bytes = 0; 438 } 439 440 bool isHumongous() const { return _humongous_type != NotHumongous; } 441 bool startsHumongous() const { return _humongous_type == StartsHumongous; } 442 bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; } 443 // For a humongous region, region in which it starts. 444 HeapRegion* humongous_start_region() const { 445 return _humongous_start_region; 446 } 447 448 // Return the number of distinct regions that are covered by this region: 449 // 1 if the region is not humongous, >= 1 if the region is humongous. 450 uint region_num() const { 451 if (!isHumongous()) { 452 return 1U; 453 } else { 454 assert(startsHumongous(), "doesn't make sense on HC regions"); 455 assert(capacity() % HeapRegion::GrainBytes == 0, "sanity"); 456 return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes); 457 } 458 } 459 460 // Return the index + 1 of the last HC regions that's associated 461 // with this HS region. 462 uint last_hc_index() const { 463 assert(startsHumongous(), "don't call this otherwise"); 464 return hrs_index() + region_num(); 465 } 466 467 // Same as Space::is_in_reserved, but will use the original size of the region. 468 // The original size is different only for start humongous regions. They get 469 // their _end set up to be the end of the last continues region of the 470 // corresponding humongous object. 471 bool is_in_reserved_raw(const void* p) const { 472 return _bottom <= p && p < _orig_end; 473 } 474 475 // Makes the current region be a "starts humongous" region, i.e., 476 // the first region in a series of one or more contiguous regions 477 // that will contain a single "humongous" object. The two parameters 478 // are as follows: 479 // 480 // new_top : The new value of the top field of this region which 481 // points to the end of the humongous object that's being 482 // allocated. If there is more than one region in the series, top 483 // will lie beyond this region's original end field and on the last 484 // region in the series. 485 // 486 // new_end : The new value of the end field of this region which 487 // points to the end of the last region in the series. If there is 488 // one region in the series (namely: this one) end will be the same 489 // as the original end of this region. 490 // 491 // Updating top and end as described above makes this region look as 492 // if it spans the entire space taken up by all the regions in the 493 // series and an single allocation moved its top to new_top. This 494 // ensures that the space (capacity / allocated) taken up by all 495 // humongous regions can be calculated by just looking at the 496 // "starts humongous" regions and by ignoring the "continues 497 // humongous" regions. 498 void set_startsHumongous(HeapWord* new_top, HeapWord* new_end); 499 500 // Makes the current region be a "continues humongous' 501 // region. first_hr is the "start humongous" region of the series 502 // which this region will be part of. 503 void set_continuesHumongous(HeapRegion* first_hr); 504 505 // Unsets the humongous-related fields on the region. 506 void set_notHumongous(); 507 508 // If the region has a remembered set, return a pointer to it. 509 HeapRegionRemSet* rem_set() const { 510 return _rem_set; 511 } 512 513 // True iff the region is in current collection_set. 514 bool in_collection_set() const { 515 return _in_collection_set; 516 } 517 void set_in_collection_set(bool b) { 518 _in_collection_set = b; 519 } 520 HeapRegion* next_in_collection_set() { 521 assert(in_collection_set(), "should only invoke on member of CS."); 522 assert(_next_in_special_set == NULL || 523 _next_in_special_set->in_collection_set(), 524 "Malformed CS."); 525 return _next_in_special_set; 526 } 527 void set_next_in_collection_set(HeapRegion* r) { 528 assert(in_collection_set(), "should only invoke on member of CS."); 529 assert(r == NULL || r->in_collection_set(), "Malformed CS."); 530 _next_in_special_set = r; 531 } 532 533 // Methods used by the HeapRegionSetBase class and subclasses. 534 535 // Getter and setter for the next field used to link regions into 536 // linked lists. 537 HeapRegion* next() { return _next; } 538 539 void set_next(HeapRegion* next) { _next = next; } 540 541 // Every region added to a set is tagged with a reference to that 542 // set. This is used for doing consistency checking to make sure that 543 // the contents of a set are as they should be and it's only 544 // available in non-product builds. 545 #ifdef ASSERT 546 void set_containing_set(HeapRegionSetBase* containing_set) { 547 assert((containing_set == NULL && _containing_set != NULL) || 548 (containing_set != NULL && _containing_set == NULL), 549 err_msg("containing_set: "PTR_FORMAT" " 550 "_containing_set: "PTR_FORMAT, 551 containing_set, _containing_set)); 552 553 _containing_set = containing_set; 554 } 555 556 HeapRegionSetBase* containing_set() { return _containing_set; } 557 #else // ASSERT 558 void set_containing_set(HeapRegionSetBase* containing_set) { } 559 560 // containing_set() is only used in asserts so there's no reason 561 // to provide a dummy version of it. 562 #endif // ASSERT 563 564 // If we want to remove regions from a list in bulk we can simply tag 565 // them with the pending_removal tag and call the 566 // remove_all_pending() method on the list. 567 568 bool pending_removal() { return _pending_removal; } 569 570 void set_pending_removal(bool pending_removal) { 571 if (pending_removal) { 572 assert(!_pending_removal && containing_set() != NULL, 573 "can only set pending removal to true if it's false and " 574 "the region belongs to a region set"); 575 } else { 576 assert( _pending_removal && containing_set() == NULL, 577 "can only set pending removal to false if it's true and " 578 "the region does not belong to a region set"); 579 } 580 581 _pending_removal = pending_removal; 582 } 583 584 HeapRegion* get_next_young_region() { return _next_young_region; } 585 void set_next_young_region(HeapRegion* hr) { 586 _next_young_region = hr; 587 } 588 589 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; } 590 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; } 591 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; } 592 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; } 593 594 HeapWord* orig_end() { return _orig_end; } 595 596 // Allows logical separation between objects allocated before and after. 597 void save_marks(); 598 599 // Reset HR stuff to default values. 600 void hr_clear(bool par, bool clear_space); 601 void par_clear(); 602 603 // Get the start of the unmarked area in this region. 604 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; } 605 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; } 606 607 // Apply "cl->do_oop" to (the addresses of) all reference fields in objects 608 // allocated in the current region before the last call to "save_mark". 609 void oop_before_save_marks_iterate(ExtendedOopClosure* cl); 610 611 // Note the start or end of marking. This tells the heap region 612 // that the collector is about to start or has finished (concurrently) 613 // marking the heap. 614 615 // Notify the region that concurrent marking is starting. Initialize 616 // all fields related to the next marking info. 617 inline void note_start_of_marking(); 618 619 // Notify the region that concurrent marking has finished. Copy the 620 // (now finalized) next marking info fields into the prev marking 621 // info fields. 622 inline void note_end_of_marking(); 623 624 // Notify the region that it will be used as to-space during a GC 625 // and we are about to start copying objects into it. 626 inline void note_start_of_copying(bool during_initial_mark); 627 628 // Notify the region that it ceases being to-space during a GC and 629 // we will not copy objects into it any more. 630 inline void note_end_of_copying(bool during_initial_mark); 631 632 // Notify the region that we are about to start processing 633 // self-forwarded objects during evac failure handling. 634 void note_self_forwarding_removal_start(bool during_initial_mark, 635 bool during_conc_mark); 636 637 // Notify the region that we have finished processing self-forwarded 638 // objects during evac failure handling. 639 void note_self_forwarding_removal_end(bool during_initial_mark, 640 bool during_conc_mark, 641 size_t marked_bytes); 642 643 // Returns "false" iff no object in the region was allocated when the 644 // last mark phase ended. 645 bool is_marked() { return _prev_top_at_mark_start != bottom(); } 646 647 void reset_during_compaction() { 648 assert(isHumongous() && startsHumongous(), 649 "should only be called for starts humongous regions"); 650 651 zero_marked_bytes(); 652 init_top_at_mark_start(); 653 } 654 655 void calc_gc_efficiency(void); 656 double gc_efficiency() { return _gc_efficiency;} 657 658 bool is_young() const { return _young_type != NotYoung; } 659 bool is_survivor() const { return _young_type == Survivor; } 660 661 int young_index_in_cset() const { return _young_index_in_cset; } 662 void set_young_index_in_cset(int index) { 663 assert( (index == -1) || is_young(), "pre-condition" ); 664 _young_index_in_cset = index; 665 } 666 667 int age_in_surv_rate_group() { 668 assert( _surv_rate_group != NULL, "pre-condition" ); 669 assert( _age_index > -1, "pre-condition" ); 670 return _surv_rate_group->age_in_group(_age_index); 671 } 672 673 void record_surv_words_in_group(size_t words_survived) { 674 assert( _surv_rate_group != NULL, "pre-condition" ); 675 assert( _age_index > -1, "pre-condition" ); 676 int age_in_group = age_in_surv_rate_group(); 677 _surv_rate_group->record_surviving_words(age_in_group, words_survived); 678 } 679 680 int age_in_surv_rate_group_cond() { 681 if (_surv_rate_group != NULL) 682 return age_in_surv_rate_group(); 683 else 684 return -1; 685 } 686 687 SurvRateGroup* surv_rate_group() { 688 return _surv_rate_group; 689 } 690 691 void install_surv_rate_group(SurvRateGroup* surv_rate_group) { 692 assert( surv_rate_group != NULL, "pre-condition" ); 693 assert( _surv_rate_group == NULL, "pre-condition" ); 694 assert( is_young(), "pre-condition" ); 695 696 _surv_rate_group = surv_rate_group; 697 _age_index = surv_rate_group->next_age_index(); 698 } 699 700 void uninstall_surv_rate_group() { 701 if (_surv_rate_group != NULL) { 702 assert( _age_index > -1, "pre-condition" ); 703 assert( is_young(), "pre-condition" ); 704 705 _surv_rate_group = NULL; 706 _age_index = -1; 707 } else { 708 assert( _age_index == -1, "pre-condition" ); 709 } 710 } 711 712 void set_young() { set_young_type(Young); } 713 714 void set_survivor() { set_young_type(Survivor); } 715 716 void set_not_young() { set_young_type(NotYoung); } 717 718 // Determine if an object has been allocated since the last 719 // mark performed by the collector. This returns true iff the object 720 // is within the unmarked area of the region. 721 bool obj_allocated_since_prev_marking(oop obj) const { 722 return (HeapWord *) obj >= prev_top_at_mark_start(); 723 } 724 bool obj_allocated_since_next_marking(oop obj) const { 725 return (HeapWord *) obj >= next_top_at_mark_start(); 726 } 727 728 // For parallel heapRegion traversal. 729 bool claimHeapRegion(int claimValue); 730 jint claim_value() { return _claimed; } 731 // Use this carefully: only when you're sure no one is claiming... 732 void set_claim_value(int claimValue) { _claimed = claimValue; } 733 734 // Returns the "evacuation_failed" property of the region. 735 bool evacuation_failed() { return _evacuation_failed; } 736 737 // Sets the "evacuation_failed" property of the region. 738 void set_evacuation_failed(bool b) { 739 _evacuation_failed = b; 740 741 if (b) { 742 _next_marked_bytes = 0; 743 } 744 } 745 746 // Requires that "mr" be entirely within the region. 747 // Apply "cl->do_object" to all objects that intersect with "mr". 748 // If the iteration encounters an unparseable portion of the region, 749 // or if "cl->abort()" is true after a closure application, 750 // terminate the iteration and return the address of the start of the 751 // subregion that isn't done. (The two can be distinguished by querying 752 // "cl->abort()".) Return of "NULL" indicates that the iteration 753 // completed. 754 HeapWord* 755 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl); 756 757 // filter_young: if true and the region is a young region then we 758 // skip the iteration. 759 // card_ptr: if not NULL, and we decide that the card is not young 760 // and we iterate over it, we'll clean the card before we start the 761 // iteration. 762 HeapWord* 763 oops_on_card_seq_iterate_careful(MemRegion mr, 764 FilterOutOfRegionClosure* cl, 765 bool filter_young, 766 jbyte* card_ptr); 767 768 // A version of block start that is guaranteed to find *some* block 769 // boundary at or before "p", but does not object iteration, and may 770 // therefore be used safely when the heap is unparseable. 771 HeapWord* block_start_careful(const void* p) const { 772 return _offsets.block_start_careful(p); 773 } 774 775 // Requires that "addr" is within the region. Returns the start of the 776 // first ("careful") block that starts at or after "addr", or else the 777 // "end" of the region if there is no such block. 778 HeapWord* next_block_start_careful(HeapWord* addr); 779 780 size_t recorded_rs_length() const { return _recorded_rs_length; } 781 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; } 782 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; } 783 784 void set_recorded_rs_length(size_t rs_length) { 785 _recorded_rs_length = rs_length; 786 } 787 788 void set_predicted_elapsed_time_ms(double ms) { 789 _predicted_elapsed_time_ms = ms; 790 } 791 792 void set_predicted_bytes_to_copy(size_t bytes) { 793 _predicted_bytes_to_copy = bytes; 794 } 795 796 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ 797 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); 798 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DECL) 799 800 virtual CompactibleSpace* next_compaction_space() const; 801 802 virtual void reset_after_compaction(); 803 804 // Routines for managing the list of code roots that point into 805 // this heap region. 806 void add_strong_code_root(nmethod* nm); 807 void remove_strong_code_root(nmethod* nm); 808 809 GrowableArray<nmethod*>* strong_code_root_list() { 810 return _strong_code_root_list; 811 } 812 813 // During a collection, migrate successfully evacuated strong 814 // code roots attached to this region to the new regions that 815 // they point into. Unsuccessfully evacuated code roots are 816 // not migrated. 817 void migrate_strong_code_roots(); 818 819 // Applies blk->do_code_blob() to each of the entries in 820 // the strong code roots list; 821 void strong_code_roots_do(CodeBlobClosure* blk) const; 822 823 // Returns the amount of memory, in bytes, currently 824 // consumed by the strong code roots. 825 size_t strong_code_root_mem_size(); 826 827 // Verify that the entries on the strong code root list are live and 828 // include at least one pointer into this region. 829 void verify_strong_code_roots(VerifyOption vo, bool* failures) const; 830 831 void print() const; 832 void print_on(outputStream* st) const; 833 834 // vo == UsePrevMarking -> use "prev" marking information, 835 // vo == UseNextMarking -> use "next" marking information 836 // vo == UseMarkWord -> use the mark word in the object header 837 // 838 // NOTE: Only the "prev" marking information is guaranteed to be 839 // consistent most of the time, so most calls to this should use 840 // vo == UsePrevMarking. 841 // Currently, there is only one case where this is called with 842 // vo == UseNextMarking, which is to verify the "next" marking 843 // information at the end of remark. 844 // Currently there is only one place where this is called with 845 // vo == UseMarkWord, which is to verify the marking during a 846 // full GC. 847 void verify(VerifyOption vo, bool *failures) const; 848 849 // Override; it uses the "prev" marking information 850 virtual void verify() const; 851 }; 852 853 // HeapRegionClosure is used for iterating over regions. 854 // Terminates the iteration when the "doHeapRegion" method returns "true". 855 class HeapRegionClosure : public StackObj { 856 friend class HeapRegionSeq; 857 friend class G1CollectedHeap; 858 859 bool _complete; 860 void incomplete() { _complete = false; } 861 862 public: 863 HeapRegionClosure(): _complete(true) {} 864 865 // Typically called on each region until it returns true. 866 virtual bool doHeapRegion(HeapRegion* r) = 0; 867 868 // True after iteration if the closure was applied to all heap regions 869 // and returned "false" in all cases. 870 bool complete() { return _complete; } 871 }; 872 873 #endif // INCLUDE_ALL_GCS 874 875 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP