1 /* 2 * Copyright (c) 2001, 2020, 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_GC_G1_HEAPREGION_HPP 26 #define SHARE_GC_G1_HEAPREGION_HPP 27 28 #include "gc/g1/g1BlockOffsetTable.hpp" 29 #include "gc/g1/g1HeapRegionTraceType.hpp" 30 #include "gc/g1/g1SurvRateGroup.hpp" 31 #include "gc/g1/heapRegionTracer.hpp" 32 #include "gc/g1/heapRegionType.hpp" 33 #include "gc/shared/ageTable.hpp" 34 #include "gc/shared/spaceDecorator.hpp" 35 #include "gc/shared/verifyOption.hpp" 36 #include "runtime/mutex.hpp" 37 #include "utilities/macros.hpp" 38 39 class G1CollectedHeap; 40 class G1CMBitMap; 41 class G1Predictions; 42 class HeapRegionRemSet; 43 class HeapRegion; 44 class HeapRegionSetBase; 45 class nmethod; 46 47 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]" 48 #define HR_FORMAT_PARAMS(_hr_) \ 49 (_hr_)->hrm_index(), \ 50 (_hr_)->get_short_type_str(), \ 51 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end()) 52 53 // sentinel value for hrm_index 54 #define G1_NO_HRM_INDEX ((uint) -1) 55 56 // A HeapRegion is the smallest piece of a G1CollectedHeap that 57 // can be collected independently. 58 59 // Each heap region is self contained. top() and end() can never 60 // be set beyond the end of the region. For humongous objects, 61 // the first region is a StartsHumongous region. If the humongous 62 // object is larger than a heap region, the following regions will 63 // be of type ContinuesHumongous. In this case the top() of the 64 // StartHumongous region and all ContinuesHumongous regions except 65 // the last will point to their own end. The last ContinuesHumongous 66 // region may have top() equal the end of object if there isn't 67 // room for filler objects to pad out to the end of the region. 68 class HeapRegion : public CHeapObj<mtGC> { 69 friend class VMStructs; 70 71 HeapWord* const _bottom; 72 HeapWord* const _end; 73 74 HeapWord* volatile _top; 75 HeapWord* _compaction_top; 76 77 G1BlockOffsetTablePart _bot_part; 78 Mutex _par_alloc_lock; 79 // When we need to retire an allocation region, while other threads 80 // are also concurrently trying to allocate into it, we typically 81 // allocate a dummy object at the end of the region to ensure that 82 // no more allocations can take place in it. However, sometimes we 83 // want to know where the end of the last "real" object we allocated 84 // into the region was and this is what this keeps track. 85 HeapWord* _pre_dummy_top; 86 87 public: 88 HeapWord* bottom() const { return _bottom; } 89 HeapWord* end() const { return _end; } 90 91 void set_compaction_top(HeapWord* compaction_top) { _compaction_top = compaction_top; } 92 HeapWord* compaction_top() const { return _compaction_top; } 93 94 void set_top(HeapWord* value) { _top = value; } 95 HeapWord* top() const { return _top; } 96 97 // See the comment above in the declaration of _pre_dummy_top for an 98 // explanation of what it is. 99 void set_pre_dummy_top(HeapWord* pre_dummy_top) { 100 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition"); 101 _pre_dummy_top = pre_dummy_top; 102 } 103 HeapWord* pre_dummy_top() { return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top; } 104 void reset_pre_dummy_top() { _pre_dummy_top = NULL; } 105 106 // Returns true iff the given the heap region contains the 107 // given address as part of an allocated object. This may 108 // be a potentially, so we restrict its use to assertion checks only. 109 bool is_in(const void* p) const { 110 return is_in_reserved(p); 111 } 112 bool is_in(oop obj) const { 113 return is_in((void*)obj); 114 } 115 // Returns true iff the given reserved memory of the space contains the 116 // given address. 117 bool is_in_reserved(const void* p) const { return _bottom <= p && p < _end; } 118 119 size_t capacity() const { return byte_size(bottom(), end()); } 120 size_t used() const { return byte_size(bottom(), top()); } 121 size_t free() const { return byte_size(top(), end()); } 122 123 bool is_empty() const { return used() == 0; } 124 125 private: 126 void reset_after_compaction() { set_top(compaction_top()); } 127 128 void clear(bool mangle_space); 129 130 HeapWord* block_start_const(const void* p) const; 131 132 void mangle_unused_area() PRODUCT_RETURN; 133 134 // Try to allocate at least min_word_size and up to desired_size from this region. 135 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of 136 // space allocated. 137 // This version assumes that all allocation requests to this HeapRegion are properly 138 // synchronized. 139 inline HeapWord* allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size); 140 // Try to allocate at least min_word_size and up to desired_size from this HeapRegion. 141 // Returns NULL if not possible, otherwise sets actual_word_size to the amount of 142 // space allocated. 143 // This version synchronizes with other calls to par_allocate_impl(). 144 inline HeapWord* par_allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size); 145 146 public: 147 HeapWord* block_start(const void* p); 148 149 void object_iterate(ObjectClosure* blk); 150 151 // Allocation (return NULL if full). Assumes the caller has established 152 // mutually exclusive access to the HeapRegion. 153 HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size); 154 // Allocation (return NULL if full). Enforces mutual exclusion internally. 155 HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size); 156 157 HeapWord* allocate(size_t word_size); 158 HeapWord* par_allocate(size_t word_size); 159 160 inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size); 161 inline HeapWord* allocate_no_bot_updates(size_t word_size); 162 inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size); 163 164 // Full GC support methods. 165 166 HeapWord* initialize_threshold(); 167 HeapWord* cross_threshold(HeapWord* start, HeapWord* end); 168 // Update heap region to be consistent after Full GC compaction. 169 void reset_humongous_during_compaction() { 170 assert(is_humongous(), 171 "should only be called for humongous regions"); 172 173 zero_marked_bytes(); 174 init_top_at_mark_start(); 175 } 176 // Update heap region to be consistent after Full GC compaction. 177 void complete_compaction(); 178 179 // All allocated blocks are occupied by objects in a HeapRegion 180 bool block_is_obj(const HeapWord* p) const; 181 182 // Returns whether the given object is dead based on TAMS and bitmap. 183 bool is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const; 184 185 // Returns the object size for all valid block starts 186 // and the amount of unallocated words if called on top() 187 size_t block_size(const HeapWord* p) const; 188 189 // Scans through the region using the bitmap to determine what 190 // objects to call size_t ApplyToMarkedClosure::apply(oop) for. 191 template<typename ApplyToMarkedClosure> 192 inline void apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure); 193 194 void reset_bot() { 195 _bot_part.reset_bot(); 196 } 197 198 private: 199 // The remembered set for this region. 200 HeapRegionRemSet* _rem_set; 201 202 // Cached index of this region in the heap region sequence. 203 const uint _hrm_index; 204 205 HeapRegionType _type; 206 207 // For a humongous region, region in which it starts. 208 HeapRegion* _humongous_start_region; 209 210 // True iff an attempt to evacuate an object in the region failed. 211 bool _evacuation_failed; 212 213 static const uint InvalidCSetIndex = UINT_MAX; 214 215 // The index in the optional regions array, if this region 216 // is considered optional during a mixed collections. 217 uint _index_in_opt_cset; 218 219 // Fields used by the HeapRegionSetBase class and subclasses. 220 HeapRegion* _next; 221 HeapRegion* _prev; 222 #ifdef ASSERT 223 HeapRegionSetBase* _containing_set; 224 #endif // ASSERT 225 226 // The start of the unmarked area. The unmarked area extends from this 227 // word until the top and/or end of the region, and is the part 228 // of the region for which no marking was done, i.e. objects may 229 // have been allocated in this part since the last mark phase. 230 // "prev" is the top at the start of the last completed marking. 231 // "next" is the top at the start of the in-progress marking (if any.) 232 HeapWord* _prev_top_at_mark_start; 233 HeapWord* _next_top_at_mark_start; 234 235 // We use concurrent marking to determine the amount of live data 236 // in each heap region. 237 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking. 238 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking. 239 240 void init_top_at_mark_start() { 241 assert(_prev_marked_bytes == 0 && 242 _next_marked_bytes == 0, 243 "Must be called after zero_marked_bytes."); 244 _prev_top_at_mark_start = _next_top_at_mark_start = bottom(); 245 } 246 247 // Data for young region survivor prediction. 248 uint _young_index_in_cset; 249 G1SurvRateGroup* _surv_rate_group; 250 int _age_index; 251 252 // Cached attributes used in the collection set policy information 253 254 // The calculated GC efficiency of the region. 255 double _gc_efficiency; 256 257 uint _node_index; 258 259 void report_region_type_change(G1HeapRegionTraceType::Type to); 260 261 // Returns whether the given object address refers to a dead object, and either the 262 // size of the object (if live) or the size of the block (if dead) in size. 263 // May 264 // - only called with obj < top() 265 // - not called on humongous objects or archive regions 266 inline bool is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const; 267 268 // Iterate over the references covered by the given MemRegion in a humongous 269 // object and apply the given closure to them. 270 // Humongous objects are allocated directly in the old-gen. So we need special 271 // handling for concurrent processing encountering an in-progress allocation. 272 // Returns the address after the last actually scanned or NULL if the area could 273 // not be scanned (That should only happen when invoked concurrently with the 274 // mutator). 275 template <class Closure, bool is_gc_active> 276 inline HeapWord* do_oops_on_memregion_in_humongous(MemRegion mr, 277 Closure* cl, 278 G1CollectedHeap* g1h); 279 280 // Returns the block size of the given (dead, potentially having its class unloaded) object 281 // starting at p extending to at most the prev TAMS using the given mark bitmap. 282 inline size_t block_size_using_bitmap(const HeapWord* p, const G1CMBitMap* const prev_bitmap) const; 283 public: 284 HeapRegion(uint hrm_index, G1BlockOffsetTable* bot, MemRegion mr); 285 286 // If this region is a member of a HeapRegionManager, the index in that 287 // sequence, otherwise -1. 288 uint hrm_index() const { return _hrm_index; } 289 290 // Initializing the HeapRegion not only resets the data structure, but also 291 // resets the BOT for that heap region. 292 // The default values for clear_space means that we will do the clearing if 293 // there's clearing to be done ourselves. We also always mangle the space. 294 void initialize(bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle); 295 296 static int LogOfHRGrainBytes; 297 static int LogOfHRGrainWords; 298 static int LogCardsPerRegion; 299 300 static size_t GrainBytes; 301 static size_t GrainWords; 302 static size_t CardsPerRegion; 303 304 static size_t align_up_to_region_byte_size(size_t sz) { 305 return (sz + (size_t) GrainBytes - 1) & 306 ~((1 << (size_t) LogOfHRGrainBytes) - 1); 307 } 308 309 // Returns whether a field is in the same region as the obj it points to. 310 template <typename T> 311 static bool is_in_same_region(T* p, oop obj) { 312 assert(p != NULL, "p can't be NULL"); 313 assert(obj != NULL, "obj can't be NULL"); 314 return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0; 315 } 316 317 static size_t max_region_size(); 318 static size_t min_region_size_in_words(); 319 320 // It sets up the heap region size (GrainBytes / GrainWords), as 321 // well as other related fields that are based on the heap region 322 // size (LogOfHRGrainBytes / LogOfHRGrainWords / 323 // CardsPerRegion). All those fields are considered constant 324 // throughout the JVM's execution, therefore they should only be set 325 // up once during initialization time. 326 static void setup_heap_region_size(size_t max_heap_size); 327 328 // The number of bytes marked live in the region in the last marking phase. 329 size_t marked_bytes() { return _prev_marked_bytes; } 330 size_t live_bytes() { 331 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes(); 332 } 333 334 // The number of bytes counted in the next marking. 335 size_t next_marked_bytes() { return _next_marked_bytes; } 336 // The number of bytes live wrt the next marking. 337 size_t next_live_bytes() { 338 return 339 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes(); 340 } 341 342 // A lower bound on the amount of garbage bytes in the region. 343 size_t garbage_bytes() { 344 size_t used_at_mark_start_bytes = 345 (prev_top_at_mark_start() - bottom()) * HeapWordSize; 346 return used_at_mark_start_bytes - marked_bytes(); 347 } 348 349 // Return the amount of bytes we'll reclaim if we collect this 350 // region. This includes not only the known garbage bytes in the 351 // region but also any unallocated space in it, i.e., [top, end), 352 // since it will also be reclaimed if we collect the region. 353 size_t reclaimable_bytes() { 354 size_t known_live_bytes = live_bytes(); 355 assert(known_live_bytes <= capacity(), "sanity"); 356 return capacity() - known_live_bytes; 357 } 358 359 // An upper bound on the number of live bytes in the region. 360 size_t max_live_bytes() { return used() - garbage_bytes(); } 361 362 void add_to_marked_bytes(size_t incr_bytes) { 363 _next_marked_bytes = _next_marked_bytes + incr_bytes; 364 } 365 366 void zero_marked_bytes() { 367 _prev_marked_bytes = _next_marked_bytes = 0; 368 } 369 // Get the start of the unmarked area in this region. 370 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; } 371 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; } 372 373 // Note the start or end of marking. This tells the heap region 374 // that the collector is about to start or has finished (concurrently) 375 // marking the heap. 376 377 // Notify the region that concurrent marking is starting. Initialize 378 // all fields related to the next marking info. 379 inline void note_start_of_marking(); 380 381 // Notify the region that concurrent marking has finished. Copy the 382 // (now finalized) next marking info fields into the prev marking 383 // info fields. 384 inline void note_end_of_marking(); 385 386 const char* get_type_str() const { return _type.get_str(); } 387 const char* get_short_type_str() const { return _type.get_short_str(); } 388 G1HeapRegionTraceType::Type get_trace_type() { return _type.get_trace_type(); } 389 390 bool is_free() const { return _type.is_free(); } 391 392 bool is_young() const { return _type.is_young(); } 393 bool is_eden() const { return _type.is_eden(); } 394 bool is_survivor() const { return _type.is_survivor(); } 395 396 bool is_humongous() const { return _type.is_humongous(); } 397 bool is_starts_humongous() const { return _type.is_starts_humongous(); } 398 bool is_continues_humongous() const { return _type.is_continues_humongous(); } 399 400 bool is_old() const { return _type.is_old(); } 401 402 bool is_old_or_humongous() const { return _type.is_old_or_humongous(); } 403 404 bool is_old_or_humongous_or_archive() const { return _type.is_old_or_humongous_or_archive(); } 405 406 // A pinned region contains objects which are not moved by garbage collections. 407 // Humongous regions and archive regions are pinned. 408 bool is_pinned() const { return _type.is_pinned(); } 409 410 // An archive region is a pinned region, also tagged as old, which 411 // should not be marked during mark/sweep. This allows the address 412 // space to be shared by JVM instances. 413 bool is_archive() const { return _type.is_archive(); } 414 bool is_open_archive() const { return _type.is_open_archive(); } 415 bool is_closed_archive() const { return _type.is_closed_archive(); } 416 417 void set_free(); 418 419 void set_eden(); 420 void set_eden_pre_gc(); 421 void set_survivor(); 422 423 void move_to_old(); 424 void set_old(); 425 426 void set_open_archive(); 427 void set_closed_archive(); 428 429 // For a humongous region, region in which it starts. 430 HeapRegion* humongous_start_region() const { 431 return _humongous_start_region; 432 } 433 434 // Makes the current region be a "starts humongous" region, i.e., 435 // the first region in a series of one or more contiguous regions 436 // that will contain a single "humongous" object. 437 // 438 // obj_top : points to the top of the humongous object. 439 // fill_size : size of the filler object at the end of the region series. 440 void set_starts_humongous(HeapWord* obj_top, size_t fill_size); 441 442 // Makes the current region be a "continues humongous' 443 // region. first_hr is the "start humongous" region of the series 444 // which this region will be part of. 445 void set_continues_humongous(HeapRegion* first_hr); 446 447 // Unsets the humongous-related fields on the region. 448 void clear_humongous(); 449 450 // If the region has a remembered set, return a pointer to it. 451 HeapRegionRemSet* rem_set() const { 452 return _rem_set; 453 } 454 455 inline bool in_collection_set() const; 456 457 // Methods used by the HeapRegionSetBase class and subclasses. 458 459 // Getter and setter for the next and prev fields used to link regions into 460 // linked lists. 461 void set_next(HeapRegion* next) { _next = next; } 462 HeapRegion* next() { return _next; } 463 464 void set_prev(HeapRegion* prev) { _prev = prev; } 465 HeapRegion* prev() { return _prev; } 466 467 void unlink_from_list(); 468 469 // Every region added to a set is tagged with a reference to that 470 // set. This is used for doing consistency checking to make sure that 471 // the contents of a set are as they should be and it's only 472 // available in non-product builds. 473 #ifdef ASSERT 474 void set_containing_set(HeapRegionSetBase* containing_set) { 475 assert((containing_set != NULL && _containing_set == NULL) || 476 containing_set == NULL, 477 "containing_set: " PTR_FORMAT " " 478 "_containing_set: " PTR_FORMAT, 479 p2i(containing_set), p2i(_containing_set)); 480 481 _containing_set = containing_set; 482 } 483 484 HeapRegionSetBase* containing_set() { return _containing_set; } 485 #else // ASSERT 486 void set_containing_set(HeapRegionSetBase* containing_set) { } 487 488 // containing_set() is only used in asserts so there's no reason 489 // to provide a dummy version of it. 490 #endif // ASSERT 491 492 493 // Reset the HeapRegion to default values and clear its remembered set. 494 // If clear_space is true, clear the HeapRegion's memory. 495 // Callers must ensure this is not called by multiple threads at the same time. 496 void hr_clear(bool clear_space); 497 // Clear the card table corresponding to this region. 498 void clear_cardtable(); 499 500 // Returns the "evacuation_failed" property of the region. 501 bool evacuation_failed() { return _evacuation_failed; } 502 503 // Sets the "evacuation_failed" property of the region. 504 void set_evacuation_failed(bool b) { 505 _evacuation_failed = b; 506 507 if (b) { 508 _next_marked_bytes = 0; 509 } 510 } 511 512 // Notify the region that we are about to start processing 513 // self-forwarded objects during evac failure handling. 514 void note_self_forwarding_removal_start(bool during_initial_mark, 515 bool during_conc_mark); 516 517 // Notify the region that we have finished processing self-forwarded 518 // objects during evac failure handling. 519 void note_self_forwarding_removal_end(size_t marked_bytes); 520 521 uint index_in_opt_cset() const { 522 assert(has_index_in_opt_cset(), "Opt cset index not set."); 523 return _index_in_opt_cset; 524 } 525 bool has_index_in_opt_cset() const { return _index_in_opt_cset != InvalidCSetIndex; } 526 void set_index_in_opt_cset(uint index) { _index_in_opt_cset = index; } 527 void clear_index_in_opt_cset() { _index_in_opt_cset = InvalidCSetIndex; } 528 529 void calc_gc_efficiency(void); 530 double gc_efficiency() const { return _gc_efficiency;} 531 532 uint young_index_in_cset() const { return _young_index_in_cset; } 533 void clear_young_index_in_cset() { _young_index_in_cset = 0; } 534 void set_young_index_in_cset(uint index) { 535 assert(index != UINT_MAX, "just checking"); 536 assert(index != 0, "just checking"); 537 assert(is_young(), "pre-condition"); 538 _young_index_in_cset = index; 539 } 540 541 int age_in_surv_rate_group() const; 542 bool has_valid_age_in_surv_rate() const; 543 544 bool has_surv_rate_group() const; 545 546 double surv_rate_prediction(G1Predictions const& predictor) const; 547 548 void install_surv_rate_group(G1SurvRateGroup* surv_rate_group); 549 void uninstall_surv_rate_group(); 550 551 void record_surv_words_in_group(size_t words_survived); 552 553 // Determine if an object has been allocated since the last 554 // mark performed by the collector. This returns true iff the object 555 // is within the unmarked area of the region. 556 bool obj_allocated_since_prev_marking(oop obj) const { 557 return cast_from_oop<HeapWord*>(obj) >= prev_top_at_mark_start(); 558 } 559 bool obj_allocated_since_next_marking(oop obj) const { 560 return cast_from_oop<HeapWord*>(obj) >= next_top_at_mark_start(); 561 } 562 563 // Update the region state after a failed evacuation. 564 void handle_evacuation_failure(); 565 566 // Iterate over the objects overlapping the given memory region, applying cl 567 // to all references in the region. This is a helper for 568 // G1RemSet::refine_card*, and is tightly coupled with them. 569 // mr must not be empty. Must be trimmed to the allocated/parseable space in this region. 570 // This region must be old or humongous. 571 // Returns the next unscanned address if the designated objects were successfully 572 // processed, NULL if an unparseable part of the heap was encountered (That should 573 // only happen when invoked concurrently with the mutator). 574 template <bool is_gc_active, class Closure> 575 inline HeapWord* oops_on_memregion_seq_iterate_careful(MemRegion mr, Closure* cl); 576 577 // Routines for managing a list of code roots (attached to the 578 // this region's RSet) that point into this heap region. 579 void add_strong_code_root(nmethod* nm); 580 void add_strong_code_root_locked(nmethod* nm); 581 void remove_strong_code_root(nmethod* nm); 582 583 // Applies blk->do_code_blob() to each of the entries in 584 // the strong code roots list for this region 585 void strong_code_roots_do(CodeBlobClosure* blk) const; 586 587 uint node_index() const { return _node_index; } 588 void set_node_index(uint node_index) { _node_index = node_index; } 589 590 // Verify that the entries on the strong code root list for this 591 // region are live and include at least one pointer into this region. 592 void verify_strong_code_roots(VerifyOption vo, bool* failures) const; 593 594 void print() const; 595 void print_on(outputStream* st) const; 596 597 // vo == UsePrevMarking -> use "prev" marking information, 598 // vo == UseNextMarking -> use "next" marking information 599 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 600 // 601 // NOTE: Only the "prev" marking information is guaranteed to be 602 // consistent most of the time, so most calls to this should use 603 // vo == UsePrevMarking. 604 // Currently, there is only one case where this is called with 605 // vo == UseNextMarking, which is to verify the "next" marking 606 // information at the end of remark. 607 // Currently there is only one place where this is called with 608 // vo == UseFullMarking, which is to verify the marking during a 609 // full GC. 610 void verify(VerifyOption vo, bool *failures) const; 611 612 // Verify using the "prev" marking information 613 void verify() const; 614 615 void verify_rem_set(VerifyOption vo, bool *failures) const; 616 void verify_rem_set() const; 617 }; 618 619 // HeapRegionClosure is used for iterating over regions. 620 // Terminates the iteration when the "do_heap_region" method returns "true". 621 class HeapRegionClosure : public StackObj { 622 friend class HeapRegionManager; 623 friend class G1CollectionSet; 624 friend class G1CollectionSetCandidates; 625 626 bool _is_complete; 627 void set_incomplete() { _is_complete = false; } 628 629 public: 630 HeapRegionClosure(): _is_complete(true) {} 631 632 // Typically called on each region until it returns true. 633 virtual bool do_heap_region(HeapRegion* r) = 0; 634 635 // True after iteration if the closure was applied to all heap regions 636 // and returned "false" in all cases. 637 bool is_complete() { return _is_complete; } 638 }; 639 640 #endif // SHARE_GC_G1_HEAPREGION_HPP