rev 6586 : 8047819: G1 HeapRegionDCTOC does not need to inherit ContiguousSpaceDCTOC
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   1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
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  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.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                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_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 DirtyCardToOopClosure {
  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   // Walk the given memory region from bottom to (actual) top
  89   // looking for objects and applying the oop closure (_cl) to
  90   // them. The base implementation of this treats the area as
  91   // blocks, where a block may or may not be an object. Sub-
  92   // classes should override this to provide more accurate
  93   // or possibly more efficient walking.
  94   void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);


  95 
  96 public:
  97   HeapRegionDCTOC(G1CollectedHeap* g1,
  98                   HeapRegion* hr, ExtendedOopClosure* cl,
  99                   CardTableModRefBS::PrecisionStyle precision,
 100                   FilterKind fk);
 101 };
 102 
 103 // The complicating factor is that BlockOffsetTable diverged
 104 // significantly, and we need functionality that is only in the G1 version.
 105 // So I copied that code, which led to an alternate G1 version of
 106 // OffsetTableContigSpace.  If the two versions of BlockOffsetTable could
 107 // be reconciled, then G1OffsetTableContigSpace could go away.
 108 
 109 // The idea behind time stamps is the following. Doing a save_marks on
 110 // all regions at every GC pause is time consuming (if I remember
 111 // well, 10ms or so). So, we would like to do that only for regions
 112 // that are GC alloc regions. To achieve this, we use time
 113 // stamps. For every evacuation pause, G1CollectedHeap generates a
 114 // unique time stamp (essentially a counter that gets
 115 // incremented). Every time we want to call save_marks on a region,
 116 // we set the saved_mark_word to top and also copy the current GC
 117 // time stamp to the time stamp field of the space. Reading the
 118 // saved_mark_word involves checking the time stamp of the
 119 // region. If it is the same as the current GC time stamp, then we
 120 // can safely read the saved_mark_word field, as it is valid. If the
 121 // time stamp of the region is not the same as the current GC time
 122 // stamp, then we instead read top, as the saved_mark_word field is
 123 // invalid. Time stamps (on the regions and also on the
 124 // G1CollectedHeap) are reset at every cleanup (we iterate over
 125 // the regions anyway) and at the end of a Full GC. The current scheme
 126 // that uses sequential unsigned ints will fail only if we have 4b
 127 // evacuation pauses between two cleanups, which is _highly_ unlikely.
 128 
 129 class G1OffsetTableContigSpace: public ContiguousSpace {
 130   friend class VMStructs;
 131  protected:
 132   G1BlockOffsetArrayContigSpace _offsets;
 133   Mutex _par_alloc_lock;
 134   volatile unsigned _gc_time_stamp;
 135   // When we need to retire an allocation region, while other threads
 136   // are also concurrently trying to allocate into it, we typically
 137   // allocate a dummy object at the end of the region to ensure that
 138   // no more allocations can take place in it. However, sometimes we
 139   // want to know where the end of the last "real" object we allocated
 140   // into the region was and this is what this keeps track.
 141   HeapWord* _pre_dummy_top;
 142 
 143  public:
 144   G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
 145                            MemRegion mr);
 146 
 147   void set_bottom(HeapWord* value);
 148   void set_end(HeapWord* value);
 149 
 150   virtual HeapWord* saved_mark_word() const;
 151   virtual void set_saved_mark();
 152   void reset_gc_time_stamp() { _gc_time_stamp = 0; }
 153   unsigned get_gc_time_stamp() { return _gc_time_stamp; }
 154 
 155   // See the comment above in the declaration of _pre_dummy_top for an
 156   // explanation of what it is.
 157   void set_pre_dummy_top(HeapWord* pre_dummy_top) {
 158     assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
 159     _pre_dummy_top = pre_dummy_top;
 160   }
 161   HeapWord* pre_dummy_top() {
 162     return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
 163   }
 164   void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
 165 
 166   virtual void clear(bool mangle_space);
 167 
 168   HeapWord* block_start(const void* p);
 169   HeapWord* block_start_const(const void* p) const;
 170 
 171   // Add offset table update.
 172   virtual HeapWord* allocate(size_t word_size);
 173   HeapWord* par_allocate(size_t word_size);
 174 
 175   // MarkSweep support phase3
 176   virtual HeapWord* initialize_threshold();
 177   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
 178 
 179   virtual void print() const;
 180 
 181   void reset_bot() {
 182     _offsets.zero_bottom_entry();
 183     _offsets.initialize_threshold();
 184   }
 185 
 186   void update_bot_for_object(HeapWord* start, size_t word_size) {
 187     _offsets.alloc_block(start, word_size);
 188   }
 189 
 190   void print_bot_on(outputStream* out) {
 191     _offsets.print_on(out);
 192   }
 193 };
 194 
 195 class HeapRegion: public G1OffsetTableContigSpace {
 196   friend class VMStructs;
 197  private:
 198 
 199   enum HumongousType {
 200     NotHumongous = 0,
 201     StartsHumongous,
 202     ContinuesHumongous
 203   };
 204 
 205   // Requires that the region "mr" be dense with objects, and begin and end
 206   // with an object.
 207   void oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl);
 208 
 209   // The remembered set for this region.
 210   // (Might want to make this "inline" later, to avoid some alloc failure
 211   // issues.)
 212   HeapRegionRemSet* _rem_set;
 213 
 214   G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
 215 
 216  protected:
 217   // The index of this region in the heap region sequence.
 218   uint  _hrs_index;
 219 
 220   HumongousType _humongous_type;
 221   // For a humongous region, region in which it starts.
 222   HeapRegion* _humongous_start_region;
 223   // For the start region of a humongous sequence, it's original end().
 224   HeapWord* _orig_end;
 225 
 226   // True iff the region is in current collection_set.
 227   bool _in_collection_set;
 228 
 229   // True iff an attempt to evacuate an object in the region failed.
 230   bool _evacuation_failed;
 231 
 232   // A heap region may be a member one of a number of special subsets, each
 233   // represented as linked lists through the field below.  Currently, these
 234   // sets include:
 235   //   The collection set.
 236   //   The set of allocation regions used in a collection pause.
 237   //   Spaces that may contain gray objects.
 238   HeapRegion* _next_in_special_set;
 239 
 240   // next region in the young "generation" region set
 241   HeapRegion* _next_young_region;
 242 
 243   // Next region whose cards need cleaning
 244   HeapRegion* _next_dirty_cards_region;
 245 
 246   // Fields used by the HeapRegionSetBase class and subclasses.
 247   HeapRegion* _next;
 248   HeapRegion* _prev;
 249 #ifdef ASSERT
 250   HeapRegionSetBase* _containing_set;
 251 #endif // ASSERT
 252   bool _pending_removal;
 253 
 254   // For parallel heapRegion traversal.
 255   jint _claimed;
 256 
 257   // We use concurrent marking to determine the amount of live data
 258   // in each heap region.
 259   size_t _prev_marked_bytes;    // Bytes known to be live via last completed marking.
 260   size_t _next_marked_bytes;    // Bytes known to be live via in-progress marking.
 261 
 262   // The calculated GC efficiency of the region.
 263   double _gc_efficiency;
 264 
 265   enum YoungType {
 266     NotYoung,                   // a region is not young
 267     Young,                      // a region is young
 268     Survivor                    // a region is young and it contains survivors
 269   };
 270 
 271   volatile YoungType _young_type;
 272   int  _young_index_in_cset;
 273   SurvRateGroup* _surv_rate_group;
 274   int  _age_index;
 275 
 276   // The start of the unmarked area. The unmarked area extends from this
 277   // word until the top and/or end of the region, and is the part
 278   // of the region for which no marking was done, i.e. objects may
 279   // have been allocated in this part since the last mark phase.
 280   // "prev" is the top at the start of the last completed marking.
 281   // "next" is the top at the start of the in-progress marking (if any.)
 282   HeapWord* _prev_top_at_mark_start;
 283   HeapWord* _next_top_at_mark_start;
 284   // If a collection pause is in progress, this is the top at the start
 285   // of that pause.
 286 
 287   void init_top_at_mark_start() {
 288     assert(_prev_marked_bytes == 0 &&
 289            _next_marked_bytes == 0,
 290            "Must be called after zero_marked_bytes.");
 291     HeapWord* bot = bottom();
 292     _prev_top_at_mark_start = bot;
 293     _next_top_at_mark_start = bot;
 294   }
 295 
 296   void set_young_type(YoungType new_type) {
 297     //assert(_young_type != new_type, "setting the same type" );
 298     // TODO: add more assertions here
 299     _young_type = new_type;
 300   }
 301 
 302   // Cached attributes used in the collection set policy information
 303 
 304   // The RSet length that was added to the total value
 305   // for the collection set.
 306   size_t _recorded_rs_length;
 307 
 308   // The predicted elapsed time that was added to total value
 309   // for the collection set.
 310   double _predicted_elapsed_time_ms;
 311 
 312   // The predicted number of bytes to copy that was added to
 313   // the total value for the collection set.
 314   size_t _predicted_bytes_to_copy;
 315 
 316  public:
 317   HeapRegion(uint hrs_index,
 318              G1BlockOffsetSharedArray* sharedOffsetArray,
 319              MemRegion mr);
 320 
 321   static int    LogOfHRGrainBytes;
 322   static int    LogOfHRGrainWords;
 323 
 324   static size_t GrainBytes;
 325   static size_t GrainWords;
 326   static size_t CardsPerRegion;
 327 
 328   static size_t align_up_to_region_byte_size(size_t sz) {
 329     return (sz + (size_t) GrainBytes - 1) &
 330                                       ~((1 << (size_t) LogOfHRGrainBytes) - 1);
 331   }
 332 
 333   static size_t max_region_size();
 334 
 335   // It sets up the heap region size (GrainBytes / GrainWords), as
 336   // well as other related fields that are based on the heap region
 337   // size (LogOfHRGrainBytes / LogOfHRGrainWords /
 338   // CardsPerRegion). All those fields are considered constant
 339   // throughout the JVM's execution, therefore they should only be set
 340   // up once during initialization time.
 341   static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
 342 
 343   enum ClaimValues {
 344     InitialClaimValue          = 0,
 345     FinalCountClaimValue       = 1,
 346     NoteEndClaimValue          = 2,
 347     ScrubRemSetClaimValue      = 3,
 348     ParVerifyClaimValue        = 4,
 349     RebuildRSClaimValue        = 5,
 350     ParEvacFailureClaimValue   = 6,
 351     AggregateCountClaimValue   = 7,
 352     VerifyCountClaimValue      = 8,
 353     ParMarkRootClaimValue      = 9
 354   };
 355 
 356   inline HeapWord* par_allocate_no_bot_updates(size_t word_size) {
 357     assert(is_young(), "we can only skip BOT updates on young regions");
 358     return ContiguousSpace::par_allocate(word_size);
 359   }
 360   inline HeapWord* allocate_no_bot_updates(size_t word_size) {
 361     assert(is_young(), "we can only skip BOT updates on young regions");
 362     return ContiguousSpace::allocate(word_size);
 363   }
 364 
 365   // If this region is a member of a HeapRegionSeq, the index in that
 366   // sequence, otherwise -1.
 367   uint hrs_index() const { return _hrs_index; }
 368 
 369   // The number of bytes marked live in the region in the last marking phase.
 370   size_t marked_bytes()    { return _prev_marked_bytes; }
 371   size_t live_bytes() {
 372     return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
 373   }
 374 
 375   // The number of bytes counted in the next marking.
 376   size_t next_marked_bytes() { return _next_marked_bytes; }
 377   // The number of bytes live wrt the next marking.
 378   size_t next_live_bytes() {
 379     return
 380       (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
 381   }
 382 
 383   // A lower bound on the amount of garbage bytes in the region.
 384   size_t garbage_bytes() {
 385     size_t used_at_mark_start_bytes =
 386       (prev_top_at_mark_start() - bottom()) * HeapWordSize;
 387     assert(used_at_mark_start_bytes >= marked_bytes(),
 388            "Can't mark more than we have.");
 389     return used_at_mark_start_bytes - marked_bytes();
 390   }
 391 
 392   // Return the amount of bytes we'll reclaim if we collect this
 393   // region. This includes not only the known garbage bytes in the
 394   // region but also any unallocated space in it, i.e., [top, end),
 395   // since it will also be reclaimed if we collect the region.
 396   size_t reclaimable_bytes() {
 397     size_t known_live_bytes = live_bytes();
 398     assert(known_live_bytes <= capacity(), "sanity");
 399     return capacity() - known_live_bytes;
 400   }
 401 
 402   // An upper bound on the number of live bytes in the region.
 403   size_t max_live_bytes() { return used() - garbage_bytes(); }
 404 
 405   void add_to_marked_bytes(size_t incr_bytes) {
 406     _next_marked_bytes = _next_marked_bytes + incr_bytes;
 407     assert(_next_marked_bytes <= used(), "invariant" );
 408   }
 409 
 410   void zero_marked_bytes()      {
 411     _prev_marked_bytes = _next_marked_bytes = 0;
 412   }
 413 
 414   bool isHumongous() const { return _humongous_type != NotHumongous; }
 415   bool startsHumongous() const { return _humongous_type == StartsHumongous; }
 416   bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; }
 417   // For a humongous region, region in which it starts.
 418   HeapRegion* humongous_start_region() const {
 419     return _humongous_start_region;
 420   }
 421 
 422   // Return the number of distinct regions that are covered by this region:
 423   // 1 if the region is not humongous, >= 1 if the region is humongous.
 424   uint region_num() const {
 425     if (!isHumongous()) {
 426       return 1U;
 427     } else {
 428       assert(startsHumongous(), "doesn't make sense on HC regions");
 429       assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
 430       return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
 431     }
 432   }
 433 
 434   // Return the index + 1 of the last HC regions that's associated
 435   // with this HS region.
 436   uint last_hc_index() const {
 437     assert(startsHumongous(), "don't call this otherwise");
 438     return hrs_index() + region_num();
 439   }
 440 
 441   // Same as Space::is_in_reserved, but will use the original size of the region.
 442   // The original size is different only for start humongous regions. They get
 443   // their _end set up to be the end of the last continues region of the
 444   // corresponding humongous object.
 445   bool is_in_reserved_raw(const void* p) const {
 446     return _bottom <= p && p < _orig_end;
 447   }
 448 
 449   // Makes the current region be a "starts humongous" region, i.e.,
 450   // the first region in a series of one or more contiguous regions
 451   // that will contain a single "humongous" object. The two parameters
 452   // are as follows:
 453   //
 454   // new_top : The new value of the top field of this region which
 455   // points to the end of the humongous object that's being
 456   // allocated. If there is more than one region in the series, top
 457   // will lie beyond this region's original end field and on the last
 458   // region in the series.
 459   //
 460   // new_end : The new value of the end field of this region which
 461   // points to the end of the last region in the series. If there is
 462   // one region in the series (namely: this one) end will be the same
 463   // as the original end of this region.
 464   //
 465   // Updating top and end as described above makes this region look as
 466   // if it spans the entire space taken up by all the regions in the
 467   // series and an single allocation moved its top to new_top. This
 468   // ensures that the space (capacity / allocated) taken up by all
 469   // humongous regions can be calculated by just looking at the
 470   // "starts humongous" regions and by ignoring the "continues
 471   // humongous" regions.
 472   void set_startsHumongous(HeapWord* new_top, HeapWord* new_end);
 473 
 474   // Makes the current region be a "continues humongous'
 475   // region. first_hr is the "start humongous" region of the series
 476   // which this region will be part of.
 477   void set_continuesHumongous(HeapRegion* first_hr);
 478 
 479   // Unsets the humongous-related fields on the region.
 480   void set_notHumongous();
 481 
 482   // If the region has a remembered set, return a pointer to it.
 483   HeapRegionRemSet* rem_set() const {
 484     return _rem_set;
 485   }
 486 
 487   // True iff the region is in current collection_set.
 488   bool in_collection_set() const {
 489     return _in_collection_set;
 490   }
 491   void set_in_collection_set(bool b) {
 492     _in_collection_set = b;
 493   }
 494   HeapRegion* next_in_collection_set() {
 495     assert(in_collection_set(), "should only invoke on member of CS.");
 496     assert(_next_in_special_set == NULL ||
 497            _next_in_special_set->in_collection_set(),
 498            "Malformed CS.");
 499     return _next_in_special_set;
 500   }
 501   void set_next_in_collection_set(HeapRegion* r) {
 502     assert(in_collection_set(), "should only invoke on member of CS.");
 503     assert(r == NULL || r->in_collection_set(), "Malformed CS.");
 504     _next_in_special_set = r;
 505   }
 506 
 507   // Methods used by the HeapRegionSetBase class and subclasses.
 508 
 509   // Getter and setter for the next and prev fields used to link regions into
 510   // linked lists.
 511   HeapRegion* next()              { return _next; }
 512   HeapRegion* prev()              { return _prev; }
 513 
 514   void set_next(HeapRegion* next) { _next = next; }
 515   void set_prev(HeapRegion* prev) { _prev = prev; }
 516 
 517   // Every region added to a set is tagged with a reference to that
 518   // set. This is used for doing consistency checking to make sure that
 519   // the contents of a set are as they should be and it's only
 520   // available in non-product builds.
 521 #ifdef ASSERT
 522   void set_containing_set(HeapRegionSetBase* containing_set) {
 523     assert((containing_set == NULL && _containing_set != NULL) ||
 524            (containing_set != NULL && _containing_set == NULL),
 525            err_msg("containing_set: "PTR_FORMAT" "
 526                    "_containing_set: "PTR_FORMAT,
 527                    p2i(containing_set), p2i(_containing_set)));
 528 
 529     _containing_set = containing_set;
 530   }
 531 
 532   HeapRegionSetBase* containing_set() { return _containing_set; }
 533 #else // ASSERT
 534   void set_containing_set(HeapRegionSetBase* containing_set) { }
 535 
 536   // containing_set() is only used in asserts so there's no reason
 537   // to provide a dummy version of it.
 538 #endif // ASSERT
 539 
 540   // If we want to remove regions from a list in bulk we can simply tag
 541   // them with the pending_removal tag and call the
 542   // remove_all_pending() method on the list.
 543 
 544   bool pending_removal() { return _pending_removal; }
 545 
 546   void set_pending_removal(bool pending_removal) {
 547     if (pending_removal) {
 548       assert(!_pending_removal && containing_set() != NULL,
 549              "can only set pending removal to true if it's false and "
 550              "the region belongs to a region set");
 551     } else {
 552       assert( _pending_removal && containing_set() == NULL,
 553               "can only set pending removal to false if it's true and "
 554               "the region does not belong to a region set");
 555     }
 556 
 557     _pending_removal = pending_removal;
 558   }
 559 
 560   HeapRegion* get_next_young_region() { return _next_young_region; }
 561   void set_next_young_region(HeapRegion* hr) {
 562     _next_young_region = hr;
 563   }
 564 
 565   HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
 566   HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
 567   void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
 568   bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
 569 
 570   HeapWord* orig_end() { return _orig_end; }
 571 
 572   // Allows logical separation between objects allocated before and after.
 573   void save_marks();
 574 
 575   // Reset HR stuff to default values.
 576   void hr_clear(bool par, bool clear_space, bool locked = false);
 577   void par_clear();
 578 
 579   // Get the start of the unmarked area in this region.
 580   HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
 581   HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
 582 
 583   // Apply "cl->do_oop" to (the addresses of) all reference fields in objects
 584   // allocated in the current region before the last call to "save_mark".
 585   void oop_before_save_marks_iterate(ExtendedOopClosure* cl);
 586 
 587   // Note the start or end of marking. This tells the heap region
 588   // that the collector is about to start or has finished (concurrently)
 589   // marking the heap.
 590 
 591   // Notify the region that concurrent marking is starting. Initialize
 592   // all fields related to the next marking info.
 593   inline void note_start_of_marking();
 594 
 595   // Notify the region that concurrent marking has finished. Copy the
 596   // (now finalized) next marking info fields into the prev marking
 597   // info fields.
 598   inline void note_end_of_marking();
 599 
 600   // Notify the region that it will be used as to-space during a GC
 601   // and we are about to start copying objects into it.
 602   inline void note_start_of_copying(bool during_initial_mark);
 603 
 604   // Notify the region that it ceases being to-space during a GC and
 605   // we will not copy objects into it any more.
 606   inline void note_end_of_copying(bool during_initial_mark);
 607 
 608   // Notify the region that we are about to start processing
 609   // self-forwarded objects during evac failure handling.
 610   void note_self_forwarding_removal_start(bool during_initial_mark,
 611                                           bool during_conc_mark);
 612 
 613   // Notify the region that we have finished processing self-forwarded
 614   // objects during evac failure handling.
 615   void note_self_forwarding_removal_end(bool during_initial_mark,
 616                                         bool during_conc_mark,
 617                                         size_t marked_bytes);
 618 
 619   // Returns "false" iff no object in the region was allocated when the
 620   // last mark phase ended.
 621   bool is_marked() { return _prev_top_at_mark_start != bottom(); }
 622 
 623   void reset_during_compaction() {
 624     assert(isHumongous() && startsHumongous(),
 625            "should only be called for starts humongous regions");
 626 
 627     zero_marked_bytes();
 628     init_top_at_mark_start();
 629   }
 630 
 631   void calc_gc_efficiency(void);
 632   double gc_efficiency() { return _gc_efficiency;}
 633 
 634   bool is_young() const     { return _young_type != NotYoung; }
 635   bool is_survivor() const  { return _young_type == Survivor; }
 636 
 637   int  young_index_in_cset() const { return _young_index_in_cset; }
 638   void set_young_index_in_cset(int index) {
 639     assert( (index == -1) || is_young(), "pre-condition" );
 640     _young_index_in_cset = index;
 641   }
 642 
 643   int age_in_surv_rate_group() {
 644     assert( _surv_rate_group != NULL, "pre-condition" );
 645     assert( _age_index > -1, "pre-condition" );
 646     return _surv_rate_group->age_in_group(_age_index);
 647   }
 648 
 649   void record_surv_words_in_group(size_t words_survived) {
 650     assert( _surv_rate_group != NULL, "pre-condition" );
 651     assert( _age_index > -1, "pre-condition" );
 652     int age_in_group = age_in_surv_rate_group();
 653     _surv_rate_group->record_surviving_words(age_in_group, words_survived);
 654   }
 655 
 656   int age_in_surv_rate_group_cond() {
 657     if (_surv_rate_group != NULL)
 658       return age_in_surv_rate_group();
 659     else
 660       return -1;
 661   }
 662 
 663   SurvRateGroup* surv_rate_group() {
 664     return _surv_rate_group;
 665   }
 666 
 667   void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
 668     assert( surv_rate_group != NULL, "pre-condition" );
 669     assert( _surv_rate_group == NULL, "pre-condition" );
 670     assert( is_young(), "pre-condition" );
 671 
 672     _surv_rate_group = surv_rate_group;
 673     _age_index = surv_rate_group->next_age_index();
 674   }
 675 
 676   void uninstall_surv_rate_group() {
 677     if (_surv_rate_group != NULL) {
 678       assert( _age_index > -1, "pre-condition" );
 679       assert( is_young(), "pre-condition" );
 680 
 681       _surv_rate_group = NULL;
 682       _age_index = -1;
 683     } else {
 684       assert( _age_index == -1, "pre-condition" );
 685     }
 686   }
 687 
 688   void set_young() { set_young_type(Young); }
 689 
 690   void set_survivor() { set_young_type(Survivor); }
 691 
 692   void set_not_young() { set_young_type(NotYoung); }
 693 
 694   // Determine if an object has been allocated since the last
 695   // mark performed by the collector. This returns true iff the object
 696   // is within the unmarked area of the region.
 697   bool obj_allocated_since_prev_marking(oop obj) const {
 698     return (HeapWord *) obj >= prev_top_at_mark_start();
 699   }
 700   bool obj_allocated_since_next_marking(oop obj) const {
 701     return (HeapWord *) obj >= next_top_at_mark_start();
 702   }
 703 
 704   // For parallel heapRegion traversal.
 705   bool claimHeapRegion(int claimValue);
 706   jint claim_value() { return _claimed; }
 707   // Use this carefully: only when you're sure no one is claiming...
 708   void set_claim_value(int claimValue) { _claimed = claimValue; }
 709 
 710   // Returns the "evacuation_failed" property of the region.
 711   bool evacuation_failed() { return _evacuation_failed; }
 712 
 713   // Sets the "evacuation_failed" property of the region.
 714   void set_evacuation_failed(bool b) {
 715     _evacuation_failed = b;
 716 
 717     if (b) {
 718       _next_marked_bytes = 0;
 719     }
 720   }
 721 
 722   // Requires that "mr" be entirely within the region.
 723   // Apply "cl->do_object" to all objects that intersect with "mr".
 724   // If the iteration encounters an unparseable portion of the region,
 725   // or if "cl->abort()" is true after a closure application,
 726   // terminate the iteration and return the address of the start of the
 727   // subregion that isn't done.  (The two can be distinguished by querying
 728   // "cl->abort()".)  Return of "NULL" indicates that the iteration
 729   // completed.
 730   HeapWord*
 731   object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
 732 
 733   // filter_young: if true and the region is a young region then we
 734   // skip the iteration.
 735   // card_ptr: if not NULL, and we decide that the card is not young
 736   // and we iterate over it, we'll clean the card before we start the
 737   // iteration.
 738   HeapWord*
 739   oops_on_card_seq_iterate_careful(MemRegion mr,
 740                                    FilterOutOfRegionClosure* cl,
 741                                    bool filter_young,
 742                                    jbyte* card_ptr);
 743 
 744   // A version of block start that is guaranteed to find *some* block
 745   // boundary at or before "p", but does not object iteration, and may
 746   // therefore be used safely when the heap is unparseable.
 747   HeapWord* block_start_careful(const void* p) const {
 748     return _offsets.block_start_careful(p);
 749   }
 750 
 751   // Requires that "addr" is within the region.  Returns the start of the
 752   // first ("careful") block that starts at or after "addr", or else the
 753   // "end" of the region if there is no such block.
 754   HeapWord* next_block_start_careful(HeapWord* addr);
 755 
 756   size_t recorded_rs_length() const        { return _recorded_rs_length; }
 757   double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
 758   size_t predicted_bytes_to_copy() const   { return _predicted_bytes_to_copy; }
 759 
 760   void set_recorded_rs_length(size_t rs_length) {
 761     _recorded_rs_length = rs_length;
 762   }
 763 
 764   void set_predicted_elapsed_time_ms(double ms) {
 765     _predicted_elapsed_time_ms = ms;
 766   }
 767 
 768   void set_predicted_bytes_to_copy(size_t bytes) {
 769     _predicted_bytes_to_copy = bytes;
 770   }
 771 
 772 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)  \
 773   virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
 774   SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DECL)
 775 
 776   virtual CompactibleSpace* next_compaction_space() const;
 777 
 778   virtual void reset_after_compaction();
 779 
 780   // Routines for managing a list of code roots (attached to the
 781   // this region's RSet) that point into this heap region.
 782   void add_strong_code_root(nmethod* nm);
 783   void remove_strong_code_root(nmethod* nm);
 784 
 785   // During a collection, migrate the successfully evacuated
 786   // strong code roots that referenced into this region to the
 787   // new regions that they now point into. Unsuccessfully
 788   // evacuated code roots are not migrated.
 789   void migrate_strong_code_roots();
 790 
 791   // Applies blk->do_code_blob() to each of the entries in
 792   // the strong code roots list for this region
 793   void strong_code_roots_do(CodeBlobClosure* blk) const;
 794 
 795   // Verify that the entries on the strong code root list for this
 796   // region are live and include at least one pointer into this region.
 797   void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
 798 
 799   void print() const;
 800   void print_on(outputStream* st) const;
 801 
 802   // vo == UsePrevMarking  -> use "prev" marking information,
 803   // vo == UseNextMarking -> use "next" marking information
 804   // vo == UseMarkWord    -> use the mark word in the object header
 805   //
 806   // NOTE: Only the "prev" marking information is guaranteed to be
 807   // consistent most of the time, so most calls to this should use
 808   // vo == UsePrevMarking.
 809   // Currently, there is only one case where this is called with
 810   // vo == UseNextMarking, which is to verify the "next" marking
 811   // information at the end of remark.
 812   // Currently there is only one place where this is called with
 813   // vo == UseMarkWord, which is to verify the marking during a
 814   // full GC.
 815   void verify(VerifyOption vo, bool *failures) const;
 816 
 817   // Override; it uses the "prev" marking information
 818   virtual void verify() const;
 819 };
 820 
 821 // HeapRegionClosure is used for iterating over regions.
 822 // Terminates the iteration when the "doHeapRegion" method returns "true".
 823 class HeapRegionClosure : public StackObj {
 824   friend class HeapRegionSeq;
 825   friend class G1CollectedHeap;
 826 
 827   bool _complete;
 828   void incomplete() { _complete = false; }
 829 
 830  public:
 831   HeapRegionClosure(): _complete(true) {}
 832 
 833   // Typically called on each region until it returns true.
 834   virtual bool doHeapRegion(HeapRegion* r) = 0;
 835 
 836   // True after iteration if the closure was applied to all heap regions
 837   // and returned "false" in all cases.
 838   bool complete() { return _complete; }
 839 };
 840 
 841 #endif // INCLUDE_ALL_GCS
 842 
 843 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
--- EOF ---