1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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  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).
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
  27 
  28 #include "gc_implementation/g1/g1BlockOffsetTable.hpp"
  29 #include "gc_implementation/g1/g1_specialized_oop_closures.hpp"
  30 #include "gc_implementation/g1/heapRegionType.hpp"
  31 #include "gc_implementation/g1/survRateGroup.hpp"
  32 #include "gc_implementation/shared/ageTable.hpp"
  33 #include "gc_implementation/shared/spaceDecorator.hpp"
  34 #include "memory/space.inline.hpp"
  35 #include "memory/watermark.hpp"
  36 #include "utilities/macros.hpp"
  37 
  38 // A HeapRegion is the smallest piece of a G1CollectedHeap that
  39 // can be collected independently.
  40 
  41 // NOTE: Although a HeapRegion is a Space, its
  42 // Space::initDirtyCardClosure method must not be called.
  43 // The problem is that the existence of this method breaks
  44 // the independence of barrier sets from remembered sets.
  45 // The solution is to remove this method from the definition
  46 // of a Space.
  47 
  48 class HeapRegionRemSet;
  49 class HeapRegionRemSetIterator;
  50 class HeapRegion;
  51 class HeapRegionSetBase;
  52 class nmethod;
  53 
  54 #define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"
  55 #define HR_FORMAT_PARAMS(_hr_) \
  56                 (_hr_)->hrm_index(), \
  57                 (_hr_)->get_short_type_str(), \
  58                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
  59 
  60 // sentinel value for hrm_index
  61 #define G1_NO_HRM_INDEX ((uint) -1)
  62 
  63 // A dirty card to oop closure for heap regions. It
  64 // knows how to get the G1 heap and how to use the bitmap
  65 // in the concurrent marker used by G1 to filter remembered
  66 // sets.
  67 
  68 class HeapRegionDCTOC : public DirtyCardToOopClosure {
  69 public:
  70   // Specification of possible DirtyCardToOopClosure filtering.
  71   enum FilterKind {
  72     NoFilterKind,
  73     IntoCSFilterKind,
  74     OutOfRegionFilterKind
  75   };
  76 
  77 protected:
  78   HeapRegion* _hr;
  79   FilterKind _fk;
  80   G1CollectedHeap* _g1;
  81 
  82   // Walk the given memory region from bottom to (actual) top
  83   // looking for objects and applying the oop closure (_cl) to
  84   // them. The base implementation of this treats the area as
  85   // blocks, where a block may or may not be an object. Sub-
  86   // classes should override this to provide more accurate
  87   // or possibly more efficient walking.
  88   void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
  89 
  90 public:
  91   HeapRegionDCTOC(G1CollectedHeap* g1,
  92                   HeapRegion* hr, ExtendedOopClosure* cl,
  93                   CardTableModRefBS::PrecisionStyle precision,
  94                   FilterKind fk);
  95 };
  96 
  97 // The complicating factor is that BlockOffsetTable diverged
  98 // significantly, and we need functionality that is only in the G1 version.
  99 // So I copied that code, which led to an alternate G1 version of
 100 // OffsetTableContigSpace.  If the two versions of BlockOffsetTable could
 101 // be reconciled, then G1OffsetTableContigSpace could go away.
 102 
 103 // The idea behind time stamps is the following. Doing a save_marks on
 104 // all regions at every GC pause is time consuming (if I remember
 105 // well, 10ms or so). So, we would like to do that only for regions
 106 // that are GC alloc regions. To achieve this, we use time
 107 // stamps. For every evacuation pause, G1CollectedHeap generates a
 108 // unique time stamp (essentially a counter that gets
 109 // incremented). Every time we want to call save_marks on a region,
 110 // we set the saved_mark_word to top and also copy the current GC
 111 // time stamp to the time stamp field of the space. Reading the
 112 // saved_mark_word involves checking the time stamp of the
 113 // region. If it is the same as the current GC time stamp, then we
 114 // can safely read the saved_mark_word field, as it is valid. If the
 115 // time stamp of the region is not the same as the current GC time
 116 // stamp, then we instead read top, as the saved_mark_word field is
 117 // invalid. Time stamps (on the regions and also on the
 118 // G1CollectedHeap) are reset at every cleanup (we iterate over
 119 // the regions anyway) and at the end of a Full GC. The current scheme
 120 // that uses sequential unsigned ints will fail only if we have 4b
 121 // evacuation pauses between two cleanups, which is _highly_ unlikely.
 122 class G1OffsetTableContigSpace: public CompactibleSpace {
 123   friend class VMStructs;
 124   HeapWord* _top;
 125  protected:
 126   G1BlockOffsetArrayContigSpace _offsets;
 127   Mutex _par_alloc_lock;
 128   volatile unsigned _gc_time_stamp;
 129   // When we need to retire an allocation region, while other threads
 130   // are also concurrently trying to allocate into it, we typically
 131   // allocate a dummy object at the end of the region to ensure that
 132   // no more allocations can take place in it. However, sometimes we
 133   // want to know where the end of the last "real" object we allocated
 134   // into the region was and this is what this keeps track.
 135   HeapWord* _pre_dummy_top;
 136 
 137  public:
 138   G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
 139                            MemRegion mr);
 140 
 141   void set_top(HeapWord* value) { _top = value; }
 142   HeapWord* top() const { return _top; }
 143 
 144  protected:
 145   // Reset the G1OffsetTableContigSpace.
 146   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
 147 
 148   HeapWord** top_addr() { return &_top; }
 149   // Allocation helpers (return NULL if full).
 150   inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
 151   inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);
 152 
 153  public:
 154   void reset_after_compaction() { set_top(compaction_top()); }
 155 
 156   size_t used() const { return byte_size(bottom(), top()); }
 157   size_t free() const { return byte_size(top(), end()); }
 158   bool is_free_block(const HeapWord* p) const { return p >= top(); }
 159 
 160   MemRegion used_region() const { return MemRegion(bottom(), top()); }
 161 
 162   void object_iterate(ObjectClosure* blk);
 163   void safe_object_iterate(ObjectClosure* blk);
 164 
 165   void set_bottom(HeapWord* value);
 166   void set_end(HeapWord* value);
 167 
 168   virtual HeapWord* saved_mark_word() const;
 169   void record_top_and_timestamp();
 170   void reset_gc_time_stamp() { _gc_time_stamp = 0; }
 171   unsigned get_gc_time_stamp() { return _gc_time_stamp; }
 172 
 173   // See the comment above in the declaration of _pre_dummy_top for an
 174   // explanation of what it is.
 175   void set_pre_dummy_top(HeapWord* pre_dummy_top) {
 176     assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
 177     _pre_dummy_top = pre_dummy_top;
 178   }
 179   HeapWord* pre_dummy_top() {
 180     return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
 181   }
 182   void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
 183 
 184   virtual void clear(bool mangle_space);
 185 
 186   HeapWord* block_start(const void* p);
 187   HeapWord* block_start_const(const void* p) const;
 188 
 189   void prepare_for_compaction(CompactPoint* cp);
 190 
 191   // Add offset table update.
 192   virtual HeapWord* allocate(size_t word_size);
 193   HeapWord* par_allocate(size_t word_size);
 194 
 195   // MarkSweep support phase3
 196   virtual HeapWord* initialize_threshold();
 197   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
 198 
 199   virtual void print() const;
 200 
 201   void reset_bot() {
 202     _offsets.reset_bot();
 203   }
 204 
 205   void print_bot_on(outputStream* out) {
 206     _offsets.print_on(out);
 207   }
 208 };
 209 
 210 class HeapRegion: public G1OffsetTableContigSpace {
 211   friend class VMStructs;
 212  private:
 213 
 214   // The remembered set for this region.
 215   // (Might want to make this "inline" later, to avoid some alloc failure
 216   // issues.)
 217   HeapRegionRemSet* _rem_set;
 218 
 219   G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
 220 
 221  protected:
 222   // The index of this region in the heap region sequence.
 223   uint  _hrm_index;
 224 
 225   HeapRegionType _type;
 226 
 227   // For a humongous region, region in which it starts.
 228   HeapRegion* _humongous_start_region;
 229   // For the start region of a humongous sequence, it's original end().
 230   HeapWord* _orig_end;
 231 
 232   // True iff the region is in current collection_set.
 233   bool _in_collection_set;
 234 
 235   // True iff an attempt to evacuate an object in the region failed.
 236   bool _evacuation_failed;
 237 
 238   // A heap region may be a member one of a number of special subsets, each
 239   // represented as linked lists through the field below.  Currently, there
 240   // is only one set:
 241   //   The collection set.
 242   HeapRegion* _next_in_special_set;
 243 
 244   // next region in the young "generation" region set
 245   HeapRegion* _next_young_region;
 246 
 247   // Next region whose cards need cleaning
 248   HeapRegion* _next_dirty_cards_region;
 249 
 250   // Fields used by the HeapRegionSetBase class and subclasses.
 251   HeapRegion* _next;
 252   HeapRegion* _prev;
 253 #ifdef ASSERT
 254   HeapRegionSetBase* _containing_set;
 255 #endif // ASSERT
 256 
 257   // For parallel heapRegion traversal.
 258   jint _claimed;
 259 
 260   // We use concurrent marking to determine the amount of live data
 261   // in each heap region.
 262   size_t _prev_marked_bytes;    // Bytes known to be live via last completed marking.
 263   size_t _next_marked_bytes;    // Bytes known to be live via in-progress marking.
 264 
 265   // The calculated GC efficiency of the region.
 266   double _gc_efficiency;
 267 
 268   int  _young_index_in_cset;
 269   SurvRateGroup* _surv_rate_group;
 270   int  _age_index;
 271 
 272   // The start of the unmarked area. The unmarked area extends from this
 273   // word until the top and/or end of the region, and is the part
 274   // of the region for which no marking was done, i.e. objects may
 275   // have been allocated in this part since the last mark phase.
 276   // "prev" is the top at the start of the last completed marking.
 277   // "next" is the top at the start of the in-progress marking (if any.)
 278   HeapWord* _prev_top_at_mark_start;
 279   HeapWord* _next_top_at_mark_start;
 280   // If a collection pause is in progress, this is the top at the start
 281   // of that pause.
 282 
 283   void init_top_at_mark_start() {
 284     assert(_prev_marked_bytes == 0 &&
 285            _next_marked_bytes == 0,
 286            "Must be called after zero_marked_bytes.");
 287     HeapWord* bot = bottom();
 288     _prev_top_at_mark_start = bot;
 289     _next_top_at_mark_start = bot;
 290   }
 291 
 292   // Cached attributes used in the collection set policy information
 293 
 294   // The RSet length that was added to the total value
 295   // for the collection set.
 296   size_t _recorded_rs_length;
 297 
 298   // The predicted elapsed time that was added to total value
 299   // for the collection set.
 300   double _predicted_elapsed_time_ms;
 301 
 302   // The predicted number of bytes to copy that was added to
 303   // the total value for the collection set.
 304   size_t _predicted_bytes_to_copy;
 305 
 306  public:
 307   HeapRegion(uint hrm_index,
 308              G1BlockOffsetSharedArray* sharedOffsetArray,
 309              MemRegion mr);
 310 
 311   // Initializing the HeapRegion not only resets the data structure, but also
 312   // resets the BOT for that heap region.
 313   // The default values for clear_space means that we will do the clearing if
 314   // there's clearing to be done ourselves. We also always mangle the space.
 315   virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
 316 
 317   static int    LogOfHRGrainBytes;
 318   static int    LogOfHRGrainWords;
 319 
 320   static size_t GrainBytes;
 321   static size_t GrainWords;
 322   static size_t CardsPerRegion;
 323 
 324   static size_t align_up_to_region_byte_size(size_t sz) {
 325     return (sz + (size_t) GrainBytes - 1) &
 326                                       ~((1 << (size_t) LogOfHRGrainBytes) - 1);
 327   }
 328 
 329   static size_t max_region_size();
 330 
 331   // It sets up the heap region size (GrainBytes / GrainWords), as
 332   // well as other related fields that are based on the heap region
 333   // size (LogOfHRGrainBytes / LogOfHRGrainWords /
 334   // CardsPerRegion). All those fields are considered constant
 335   // throughout the JVM's execution, therefore they should only be set
 336   // up once during initialization time.
 337   static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
 338 
 339   enum ClaimValues {
 340     InitialClaimValue          = 0,
 341     FinalCountClaimValue       = 1,
 342     NoteEndClaimValue          = 2,
 343     ScrubRemSetClaimValue      = 3,
 344     ParVerifyClaimValue        = 4,
 345     RebuildRSClaimValue        = 5,
 346     ParEvacFailureClaimValue   = 6,
 347     AggregateCountClaimValue   = 7,
 348     VerifyCountClaimValue      = 8,
 349     ParMarkRootClaimValue      = 9
 350   };
 351 
 352   // All allocated blocks are occupied by objects in a HeapRegion
 353   bool block_is_obj(const HeapWord* p) const;
 354 
 355   // Returns the object size for all valid block starts
 356   // and the amount of unallocated words if called on top()
 357   size_t block_size(const HeapWord* p) const;
 358 
 359   inline HeapWord* par_allocate_no_bot_updates(size_t word_size);
 360   inline HeapWord* allocate_no_bot_updates(size_t word_size);
 361 
 362   // If this region is a member of a HeapRegionManager, the index in that
 363   // sequence, otherwise -1.
 364   uint hrm_index() const { return _hrm_index; }
 365 
 366   // The number of bytes marked live in the region in the last marking phase.
 367   size_t marked_bytes()    { return _prev_marked_bytes; }
 368   size_t live_bytes() {
 369     return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
 370   }
 371 
 372   // The number of bytes counted in the next marking.
 373   size_t next_marked_bytes() { return _next_marked_bytes; }
 374   // The number of bytes live wrt the next marking.
 375   size_t next_live_bytes() {
 376     return
 377       (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
 378   }
 379 
 380   // A lower bound on the amount of garbage bytes in the region.
 381   size_t garbage_bytes() {
 382     size_t used_at_mark_start_bytes =
 383       (prev_top_at_mark_start() - bottom()) * HeapWordSize;
 384     assert(used_at_mark_start_bytes >= marked_bytes(),
 385            "Can't mark more than we have.");
 386     return used_at_mark_start_bytes - marked_bytes();
 387   }
 388 
 389   // Return the amount of bytes we'll reclaim if we collect this
 390   // region. This includes not only the known garbage bytes in the
 391   // region but also any unallocated space in it, i.e., [top, end),
 392   // since it will also be reclaimed if we collect the region.
 393   size_t reclaimable_bytes() {
 394     size_t known_live_bytes = live_bytes();
 395     assert(known_live_bytes <= capacity(), "sanity");
 396     return capacity() - known_live_bytes;
 397   }
 398 
 399   // An upper bound on the number of live bytes in the region.
 400   size_t max_live_bytes() { return used() - garbage_bytes(); }
 401 
 402   void add_to_marked_bytes(size_t incr_bytes) {
 403     _next_marked_bytes = _next_marked_bytes + incr_bytes;
 404     assert(_next_marked_bytes <= used(), "invariant" );
 405   }
 406 
 407   void zero_marked_bytes()      {
 408     _prev_marked_bytes = _next_marked_bytes = 0;
 409   }
 410 
 411   const char* get_type_str() const { return _type.get_str(); }
 412   const char* get_short_type_str() const { return _type.get_short_str(); }
 413 
 414   bool is_free() const { return _type.is_free(); }
 415 
 416   bool is_young()    const { return _type.is_young();    }
 417   bool is_eden()     const { return _type.is_eden();     }
 418   bool is_survivor() const { return _type.is_survivor(); }
 419 
 420   bool isHumongous() const { return _type.is_humongous(); }
 421   bool startsHumongous() const { return _type.is_starts_humongous(); }
 422   bool continuesHumongous() const { return _type.is_continues_humongous();   }
 423 
 424   bool is_old() const { return _type.is_old(); }
 425 
 426   // For a humongous region, region in which it starts.
 427   HeapRegion* humongous_start_region() const {
 428     return _humongous_start_region;
 429   }
 430 
 431   // Return the number of distinct regions that are covered by this region:
 432   // 1 if the region is not humongous, >= 1 if the region is humongous.
 433   uint region_num() const {
 434     if (!isHumongous()) {
 435       return 1U;
 436     } else {
 437       assert(startsHumongous(), "doesn't make sense on HC regions");
 438       assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
 439       return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
 440     }
 441   }
 442 
 443   // Return the index + 1 of the last HC regions that's associated
 444   // with this HS region.
 445   uint last_hc_index() const {
 446     assert(startsHumongous(), "don't call this otherwise");
 447     return hrm_index() + region_num();
 448   }
 449 
 450   // Same as Space::is_in_reserved, but will use the original size of the region.
 451   // The original size is different only for start humongous regions. They get
 452   // their _end set up to be the end of the last continues region of the
 453   // corresponding humongous object.
 454   bool is_in_reserved_raw(const void* p) const {
 455     return _bottom <= p && p < _orig_end;
 456   }
 457 
 458   // Makes the current region be a "starts humongous" region, i.e.,
 459   // the first region in a series of one or more contiguous regions
 460   // that will contain a single "humongous" object. The two parameters
 461   // are as follows:
 462   //
 463   // new_top : The new value of the top field of this region which
 464   // points to the end of the humongous object that's being
 465   // allocated. If there is more than one region in the series, top
 466   // will lie beyond this region's original end field and on the last
 467   // region in the series.
 468   //
 469   // new_end : The new value of the end field of this region which
 470   // points to the end of the last region in the series. If there is
 471   // one region in the series (namely: this one) end will be the same
 472   // as the original end of this region.
 473   //
 474   // Updating top and end as described above makes this region look as
 475   // if it spans the entire space taken up by all the regions in the
 476   // series and an single allocation moved its top to new_top. This
 477   // ensures that the space (capacity / allocated) taken up by all
 478   // humongous regions can be calculated by just looking at the
 479   // "starts humongous" regions and by ignoring the "continues
 480   // humongous" regions.
 481   void set_startsHumongous(HeapWord* new_top, HeapWord* new_end);
 482 
 483   // Makes the current region be a "continues humongous'
 484   // region. first_hr is the "start humongous" region of the series
 485   // which this region will be part of.
 486   void set_continuesHumongous(HeapRegion* first_hr);
 487 
 488   // Unsets the humongous-related fields on the region.
 489   void clear_humongous();
 490 
 491   // If the region has a remembered set, return a pointer to it.
 492   HeapRegionRemSet* rem_set() const {
 493     return _rem_set;
 494   }
 495 
 496   // True iff the region is in current collection_set.
 497   bool in_collection_set() const {
 498     return _in_collection_set;
 499   }
 500   void set_in_collection_set(bool b) {
 501     _in_collection_set = b;
 502   }
 503   HeapRegion* next_in_collection_set() {
 504     assert(in_collection_set(), "should only invoke on member of CS.");
 505     assert(_next_in_special_set == NULL ||
 506            _next_in_special_set->in_collection_set(),
 507            "Malformed CS.");
 508     return _next_in_special_set;
 509   }
 510   void set_next_in_collection_set(HeapRegion* r) {
 511     assert(in_collection_set(), "should only invoke on member of CS.");
 512     assert(r == NULL || r->in_collection_set(), "Malformed CS.");
 513     _next_in_special_set = r;
 514   }
 515 
 516   // Methods used by the HeapRegionSetBase class and subclasses.
 517 
 518   // Getter and setter for the next and prev fields used to link regions into
 519   // linked lists.
 520   HeapRegion* next()              { return _next; }
 521   HeapRegion* prev()              { return _prev; }
 522 
 523   void set_next(HeapRegion* next) { _next = next; }
 524   void set_prev(HeapRegion* prev) { _prev = prev; }
 525 
 526   // Every region added to a set is tagged with a reference to that
 527   // set. This is used for doing consistency checking to make sure that
 528   // the contents of a set are as they should be and it's only
 529   // available in non-product builds.
 530 #ifdef ASSERT
 531   void set_containing_set(HeapRegionSetBase* containing_set) {
 532     assert((containing_set == NULL && _containing_set != NULL) ||
 533            (containing_set != NULL && _containing_set == NULL),
 534            err_msg("containing_set: "PTR_FORMAT" "
 535                    "_containing_set: "PTR_FORMAT,
 536                    p2i(containing_set), p2i(_containing_set)));
 537 
 538     _containing_set = containing_set;
 539   }
 540 
 541   HeapRegionSetBase* containing_set() { return _containing_set; }
 542 #else // ASSERT
 543   void set_containing_set(HeapRegionSetBase* containing_set) { }
 544 
 545   // containing_set() is only used in asserts so there's no reason
 546   // to provide a dummy version of it.
 547 #endif // ASSERT
 548 
 549   HeapRegion* get_next_young_region() { return _next_young_region; }
 550   void set_next_young_region(HeapRegion* hr) {
 551     _next_young_region = hr;
 552   }
 553 
 554   HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
 555   HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
 556   void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
 557   bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
 558 
 559   HeapWord* orig_end() const { return _orig_end; }
 560 
 561   // Reset HR stuff to default values.
 562   void hr_clear(bool par, bool clear_space, bool locked = false);
 563   void par_clear();
 564 
 565   // Get the start of the unmarked area in this region.
 566   HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
 567   HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
 568 
 569   // Note the start or end of marking. This tells the heap region
 570   // that the collector is about to start or has finished (concurrently)
 571   // marking the heap.
 572 
 573   // Notify the region that concurrent marking is starting. Initialize
 574   // all fields related to the next marking info.
 575   inline void note_start_of_marking();
 576 
 577   // Notify the region that concurrent marking has finished. Copy the
 578   // (now finalized) next marking info fields into the prev marking
 579   // info fields.
 580   inline void note_end_of_marking();
 581 
 582   // Notify the region that it will be used as to-space during a GC
 583   // and we are about to start copying objects into it.
 584   inline void note_start_of_copying(bool during_initial_mark);
 585 
 586   // Notify the region that it ceases being to-space during a GC and
 587   // we will not copy objects into it any more.
 588   inline void note_end_of_copying(bool during_initial_mark);
 589 
 590   // Notify the region that we are about to start processing
 591   // self-forwarded objects during evac failure handling.
 592   void note_self_forwarding_removal_start(bool during_initial_mark,
 593                                           bool during_conc_mark);
 594 
 595   // Notify the region that we have finished processing self-forwarded
 596   // objects during evac failure handling.
 597   void note_self_forwarding_removal_end(bool during_initial_mark,
 598                                         bool during_conc_mark,
 599                                         size_t marked_bytes);
 600 
 601   // Returns "false" iff no object in the region was allocated when the
 602   // last mark phase ended.
 603   bool is_marked() { return _prev_top_at_mark_start != bottom(); }
 604 
 605   void reset_during_compaction() {
 606     assert(isHumongous() && startsHumongous(),
 607            "should only be called for starts humongous regions");
 608 
 609     zero_marked_bytes();
 610     init_top_at_mark_start();
 611   }
 612 
 613   void calc_gc_efficiency(void);
 614   double gc_efficiency() { return _gc_efficiency;}
 615 
 616   int  young_index_in_cset() const { return _young_index_in_cset; }
 617   void set_young_index_in_cset(int index) {
 618     assert( (index == -1) || is_young(), "pre-condition" );
 619     _young_index_in_cset = index;
 620   }
 621 
 622   int age_in_surv_rate_group() {
 623     assert( _surv_rate_group != NULL, "pre-condition" );
 624     assert( _age_index > -1, "pre-condition" );
 625     return _surv_rate_group->age_in_group(_age_index);
 626   }
 627 
 628   void record_surv_words_in_group(size_t words_survived) {
 629     assert( _surv_rate_group != NULL, "pre-condition" );
 630     assert( _age_index > -1, "pre-condition" );
 631     int age_in_group = age_in_surv_rate_group();
 632     _surv_rate_group->record_surviving_words(age_in_group, words_survived);
 633   }
 634 
 635   int age_in_surv_rate_group_cond() {
 636     if (_surv_rate_group != NULL)
 637       return age_in_surv_rate_group();
 638     else
 639       return -1;
 640   }
 641 
 642   SurvRateGroup* surv_rate_group() {
 643     return _surv_rate_group;
 644   }
 645 
 646   void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
 647     assert( surv_rate_group != NULL, "pre-condition" );
 648     assert( _surv_rate_group == NULL, "pre-condition" );
 649     assert( is_young(), "pre-condition" );
 650 
 651     _surv_rate_group = surv_rate_group;
 652     _age_index = surv_rate_group->next_age_index();
 653   }
 654 
 655   void uninstall_surv_rate_group() {
 656     if (_surv_rate_group != NULL) {
 657       assert( _age_index > -1, "pre-condition" );
 658       assert( is_young(), "pre-condition" );
 659 
 660       _surv_rate_group = NULL;
 661       _age_index = -1;
 662     } else {
 663       assert( _age_index == -1, "pre-condition" );
 664     }
 665   }
 666 
 667   void set_free() { _type.set_free(); }
 668 
 669   void set_eden()        { _type.set_eden();        }
 670   void set_eden_pre_gc() { _type.set_eden_pre_gc(); }
 671   void set_survivor()    { _type.set_survivor();    }
 672 
 673   void set_old() { _type.set_old(); }
 674 
 675   // Determine if an object has been allocated since the last
 676   // mark performed by the collector. This returns true iff the object
 677   // is within the unmarked area of the region.
 678   bool obj_allocated_since_prev_marking(oop obj) const {
 679     return (HeapWord *) obj >= prev_top_at_mark_start();
 680   }
 681   bool obj_allocated_since_next_marking(oop obj) const {
 682     return (HeapWord *) obj >= next_top_at_mark_start();
 683   }
 684 
 685   // For parallel heapRegion traversal.
 686   bool claimHeapRegion(int claimValue);
 687   jint claim_value() { return _claimed; }
 688   // Use this carefully: only when you're sure no one is claiming...
 689   void set_claim_value(int claimValue) { _claimed = claimValue; }
 690 
 691   // Returns the "evacuation_failed" property of the region.
 692   bool evacuation_failed() { return _evacuation_failed; }
 693 
 694   // Sets the "evacuation_failed" property of the region.
 695   void set_evacuation_failed(bool b) {
 696     _evacuation_failed = b;
 697 
 698     if (b) {
 699       _next_marked_bytes = 0;
 700     }
 701   }
 702 
 703   // Requires that "mr" be entirely within the region.
 704   // Apply "cl->do_object" to all objects that intersect with "mr".
 705   // If the iteration encounters an unparseable portion of the region,
 706   // or if "cl->abort()" is true after a closure application,
 707   // terminate the iteration and return the address of the start of the
 708   // subregion that isn't done.  (The two can be distinguished by querying
 709   // "cl->abort()".)  Return of "NULL" indicates that the iteration
 710   // completed.
 711   HeapWord*
 712   object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
 713 
 714   // filter_young: if true and the region is a young region then we
 715   // skip the iteration.
 716   // card_ptr: if not NULL, and we decide that the card is not young
 717   // and we iterate over it, we'll clean the card before we start the
 718   // iteration.
 719   HeapWord*
 720   oops_on_card_seq_iterate_careful(MemRegion mr,
 721                                    FilterOutOfRegionClosure* cl,
 722                                    bool filter_young,
 723                                    jbyte* card_ptr);
 724 
 725   size_t recorded_rs_length() const        { return _recorded_rs_length; }
 726   double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
 727   size_t predicted_bytes_to_copy() const   { return _predicted_bytes_to_copy; }
 728 
 729   void set_recorded_rs_length(size_t rs_length) {
 730     _recorded_rs_length = rs_length;
 731   }
 732 
 733   void set_predicted_elapsed_time_ms(double ms) {
 734     _predicted_elapsed_time_ms = ms;
 735   }
 736 
 737   void set_predicted_bytes_to_copy(size_t bytes) {
 738     _predicted_bytes_to_copy = bytes;
 739   }
 740 
 741   virtual CompactibleSpace* next_compaction_space() const;
 742 
 743   virtual void reset_after_compaction();
 744 
 745   // Routines for managing a list of code roots (attached to the
 746   // this region's RSet) that point into this heap region.
 747   void add_strong_code_root(nmethod* nm);
 748   void add_strong_code_root_locked(nmethod* nm);
 749   void remove_strong_code_root(nmethod* nm);
 750 
 751   // Applies blk->do_code_blob() to each of the entries in
 752   // the strong code roots list for this region
 753   void strong_code_roots_do(CodeBlobClosure* blk) const;
 754 
 755   // Verify that the entries on the strong code root list for this
 756   // region are live and include at least one pointer into this region.
 757   void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
 758 
 759   void print() const;
 760   void print_on(outputStream* st) const;
 761 
 762   // vo == UsePrevMarking  -> use "prev" marking information,
 763   // vo == UseNextMarking -> use "next" marking information
 764   // vo == UseMarkWord    -> use the mark word in the object header
 765   //
 766   // NOTE: Only the "prev" marking information is guaranteed to be
 767   // consistent most of the time, so most calls to this should use
 768   // vo == UsePrevMarking.
 769   // Currently, there is only one case where this is called with
 770   // vo == UseNextMarking, which is to verify the "next" marking
 771   // information at the end of remark.
 772   // Currently there is only one place where this is called with
 773   // vo == UseMarkWord, which is to verify the marking during a
 774   // full GC.
 775   void verify(VerifyOption vo, bool *failures) const;
 776 
 777   // Override; it uses the "prev" marking information
 778   virtual void verify() const;
 779 };
 780 
 781 // HeapRegionClosure is used for iterating over regions.
 782 // Terminates the iteration when the "doHeapRegion" method returns "true".
 783 class HeapRegionClosure : public StackObj {
 784   friend class HeapRegionManager;
 785   friend class G1CollectedHeap;
 786 
 787   bool _complete;
 788   void incomplete() { _complete = false; }
 789 
 790  public:
 791   HeapRegionClosure(): _complete(true) {}
 792 
 793   // Typically called on each region until it returns true.
 794   virtual bool doHeapRegion(HeapRegion* r) = 0;
 795 
 796   // True after iteration if the closure was applied to all heap regions
 797   // and returned "false" in all cases.
 798   bool complete() { return _complete; }
 799 };
 800 
 801 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP