1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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_G1_HEAPREGION_HPP
  26 #define SHARE_VM_GC_G1_HEAPREGION_HPP
  27 
  28 #include "gc/g1/g1AllocationContext.hpp"
  29 #include "gc/g1/g1BlockOffsetTable.hpp"
  30 #include "gc/g1/heapRegionType.hpp"
  31 #include "gc/g1/survRateGroup.hpp"
  32 #include "gc/shared/ageTable.hpp"
  33 #include "gc/shared/spaceDecorator.hpp"
  34 #include "utilities/macros.hpp"
  35 
  36 // A HeapRegion is the smallest piece of a G1CollectedHeap that
  37 // can be collected independently.
  38 
  39 // NOTE: Although a HeapRegion is a Space, its
  40 // Space::initDirtyCardClosure method must not be called.
  41 // The problem is that the existence of this method breaks
  42 // the independence of barrier sets from remembered sets.
  43 // The solution is to remove this method from the definition
  44 // of a Space.
  45 
  46 // Each heap region is self contained. top() and end() can never
  47 // be set beyond the end of the region. For humongous objects,
  48 // the first region is a StartsHumongous region. If the humongous
  49 // object is larger than a heap region, the following regions will
  50 // be of type ContinuesHumongous. In this case the top() of the
  51 // StartHumongous region and all ContinuesHumongous regions except
  52 // the last will point to their own end. For the last ContinuesHumongous
  53 // region, top() will equal the object's top.
  54 
  55 class G1CollectedHeap;
  56 class HeapRegionRemSet;
  57 class HeapRegionRemSetIterator;
  58 class HeapRegion;
  59 class HeapRegionSetBase;
  60 class nmethod;
  61 
  62 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
  63 #define HR_FORMAT_PARAMS(_hr_) \
  64                 (_hr_)->hrm_index(), \
  65                 (_hr_)->get_short_type_str(), \
  66                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
  67 
  68 // sentinel value for hrm_index
  69 #define G1_NO_HRM_INDEX ((uint) -1)
  70 
  71 // A dirty card to oop closure for heap regions. It
  72 // knows how to get the G1 heap and how to use the bitmap
  73 // in the concurrent marker used by G1 to filter remembered
  74 // sets.
  75 
  76 class HeapRegionDCTOC : public DirtyCardToOopClosure {
  77 private:
  78   HeapRegion* _hr;
  79   G1ParPushHeapRSClosure* _rs_scan;
  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,
  93                   G1ParPushHeapRSClosure* cl,
  94                   CardTableModRefBS::PrecisionStyle precision);
  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. We want to keep track of
 104 // the highest address where it's safe to scan objects for each region.
 105 // This is only relevant for current GC alloc regions so we keep a time stamp
 106 // per region to determine if the region has been allocated during the current
 107 // GC or not. If the time stamp is current we report a scan_top value which
 108 // was saved at the end of the previous GC for retained alloc regions and which is
 109 // equal to the bottom for all other regions.
 110 // There is a race between card scanners and allocating gc workers where we must ensure
 111 // that card scanners do not read the memory allocated by the gc workers.
 112 // In order to enforce that, we must not return a value of _top which is more recent than the
 113 // time stamp. This is due to the fact that a region may become a gc alloc region at
 114 // some point after we've read the timestamp value as being < the current time stamp.
 115 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
 116 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
 117 // evacuation pauses between two cleanups, which is _highly_ unlikely.
 118 class G1ContiguousSpace: public CompactibleSpace {
 119   friend class VMStructs;
 120   HeapWord* volatile _top;
 121   HeapWord* volatile _scan_top;
 122  protected:
 123   G1BlockOffsetTablePart _bot_part;
 124   Mutex _par_alloc_lock;
 125   volatile unsigned _gc_time_stamp;
 126   // When we need to retire an allocation region, while other threads
 127   // are also concurrently trying to allocate into it, we typically
 128   // allocate a dummy object at the end of the region to ensure that
 129   // no more allocations can take place in it. However, sometimes we
 130   // want to know where the end of the last "real" object we allocated
 131   // into the region was and this is what this keeps track.
 132   HeapWord* _pre_dummy_top;
 133 
 134  public:
 135   G1ContiguousSpace(G1BlockOffsetTable* bot);
 136 
 137   void set_top(HeapWord* value) { _top = value; }
 138   HeapWord* top() const { return _top; }
 139 
 140  protected:
 141   // Reset the G1ContiguousSpace.
 142   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
 143 
 144   HeapWord* volatile* top_addr() { return &_top; }
 145   // Try to allocate at least min_word_size and up to desired_size from this Space.
 146   // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
 147   // space allocated.
 148   // This version assumes that all allocation requests to this Space are properly
 149   // synchronized.
 150   inline HeapWord* allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 151   // Try to allocate at least min_word_size and up to desired_size from this Space.
 152   // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
 153   // space allocated.
 154   // This version synchronizes with other calls to par_allocate_impl().
 155   inline HeapWord* par_allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 156 
 157  public:
 158   void reset_after_compaction() { set_top(compaction_top()); }
 159 
 160   size_t used() const { return byte_size(bottom(), top()); }
 161   size_t free() const { return byte_size(top(), end()); }
 162   bool is_free_block(const HeapWord* p) const { return p >= top(); }
 163 
 164   MemRegion used_region() const { return MemRegion(bottom(), top()); }
 165 
 166   void object_iterate(ObjectClosure* blk);
 167   void safe_object_iterate(ObjectClosure* blk);
 168 
 169   void mangle_unused_area() PRODUCT_RETURN;
 170   void mangle_unused_area_complete() PRODUCT_RETURN;
 171 
 172   HeapWord* scan_top() const;
 173   void record_timestamp();
 174   void reset_gc_time_stamp() { _gc_time_stamp = 0; }
 175   unsigned get_gc_time_stamp() { return _gc_time_stamp; }
 176   void record_retained_region();
 177 
 178   // See the comment above in the declaration of _pre_dummy_top for an
 179   // explanation of what it is.
 180   void set_pre_dummy_top(HeapWord* pre_dummy_top) {
 181     assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
 182     _pre_dummy_top = pre_dummy_top;
 183   }
 184   HeapWord* pre_dummy_top() {
 185     return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
 186   }
 187   void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
 188 
 189   virtual void clear(bool mangle_space);
 190 
 191   HeapWord* block_start(const void* p);
 192   HeapWord* block_start_const(const void* p) const;
 193 
 194   // Allocation (return NULL if full).  Assumes the caller has established
 195   // mutually exclusive access to the space.
 196   HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 197   // Allocation (return NULL if full).  Enforces mutual exclusion internally.
 198   HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 199 
 200   virtual HeapWord* allocate(size_t word_size);
 201   virtual HeapWord* par_allocate(size_t word_size);
 202 
 203   HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
 204 
 205   // MarkSweep support phase3
 206   virtual HeapWord* initialize_threshold();
 207   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
 208 
 209   virtual void print() const;
 210 
 211   void reset_bot() {
 212     _bot_part.reset_bot();
 213   }
 214 
 215   void print_bot_on(outputStream* out) {
 216     _bot_part.print_on(out);
 217   }
 218 };
 219 
 220 class HeapRegion: public G1ContiguousSpace {
 221   friend class VMStructs;
 222   // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
 223   template <typename SpaceType>
 224   friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
 225  private:
 226 
 227   // The remembered set for this region.
 228   // (Might want to make this "inline" later, to avoid some alloc failure
 229   // issues.)
 230   HeapRegionRemSet* _rem_set;
 231 
 232   // Auxiliary functions for scan_and_forward support.
 233   // See comments for CompactibleSpace for more information.
 234   inline HeapWord* scan_limit() const {
 235     return top();
 236   }
 237 
 238   inline bool scanned_block_is_obj(const HeapWord* addr) const {
 239     return true; // Always true, since scan_limit is top
 240   }
 241 
 242   inline size_t scanned_block_size(const HeapWord* addr) const {
 243     return HeapRegion::block_size(addr); // Avoid virtual call
 244   }
 245 
 246  protected:
 247   // The index of this region in the heap region sequence.
 248   uint  _hrm_index;
 249 
 250   AllocationContext_t _allocation_context;
 251 
 252   HeapRegionType _type;
 253 
 254   // For a humongous region, region in which it starts.
 255   HeapRegion* _humongous_start_region;
 256 
 257   // True iff an attempt to evacuate an object in the region failed.
 258   bool _evacuation_failed;
 259 
 260   // A heap region may be a member one of a number of special subsets, each
 261   // represented as linked lists through the field below.  Currently, there
 262   // is only one set:
 263   //   The collection set.
 264   HeapRegion* _next_in_special_set;
 265 
 266   // next region in the young "generation" region set
 267   HeapRegion* _next_young_region;
 268 
 269   // Next region whose cards need cleaning
 270   HeapRegion* _next_dirty_cards_region;
 271 
 272   // Fields used by the HeapRegionSetBase class and subclasses.
 273   HeapRegion* _next;
 274   HeapRegion* _prev;
 275 #ifdef ASSERT
 276   HeapRegionSetBase* _containing_set;
 277 #endif // ASSERT
 278 
 279   // We use concurrent marking to determine the amount of live data
 280   // in each heap region.
 281   size_t _prev_marked_bytes;    // Bytes known to be live via last completed marking.
 282   size_t _next_marked_bytes;    // Bytes known to be live via in-progress marking.
 283 
 284   // The calculated GC efficiency of the region.
 285   double _gc_efficiency;
 286 
 287   int  _young_index_in_cset;
 288   SurvRateGroup* _surv_rate_group;
 289   int  _age_index;
 290 
 291   // The start of the unmarked area. The unmarked area extends from this
 292   // word until the top and/or end of the region, and is the part
 293   // of the region for which no marking was done, i.e. objects may
 294   // have been allocated in this part since the last mark phase.
 295   // "prev" is the top at the start of the last completed marking.
 296   // "next" is the top at the start of the in-progress marking (if any.)
 297   HeapWord* _prev_top_at_mark_start;
 298   HeapWord* _next_top_at_mark_start;
 299   // If a collection pause is in progress, this is the top at the start
 300   // of that pause.
 301 
 302   void init_top_at_mark_start() {
 303     assert(_prev_marked_bytes == 0 &&
 304            _next_marked_bytes == 0,
 305            "Must be called after zero_marked_bytes.");
 306     HeapWord* bot = bottom();
 307     _prev_top_at_mark_start = bot;
 308     _next_top_at_mark_start = bot;
 309   }
 310 
 311   // Cached attributes used in the collection set policy information
 312 
 313   // The RSet length that was added to the total value
 314   // for the collection set.
 315   size_t _recorded_rs_length;
 316 
 317   // The predicted elapsed time that was added to total value
 318   // for the collection set.
 319   double _predicted_elapsed_time_ms;
 320 
 321   // The predicted number of bytes to copy that was added to
 322   // the total value for the collection set.
 323   size_t _predicted_bytes_to_copy;
 324 
 325  public:
 326   HeapRegion(uint hrm_index,
 327              G1BlockOffsetTable* bot,
 328              MemRegion mr);
 329 
 330   // Initializing the HeapRegion not only resets the data structure, but also
 331   // resets the BOT for that heap region.
 332   // The default values for clear_space means that we will do the clearing if
 333   // there's clearing to be done ourselves. We also always mangle the space.
 334   virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
 335 
 336   static int    LogOfHRGrainBytes;
 337   static int    LogOfHRGrainWords;
 338 
 339   static size_t GrainBytes;
 340   static size_t GrainWords;
 341   static size_t CardsPerRegion;
 342 
 343   static size_t align_up_to_region_byte_size(size_t sz) {
 344     return (sz + (size_t) GrainBytes - 1) &
 345                                       ~((1 << (size_t) LogOfHRGrainBytes) - 1);
 346   }
 347 
 348 
 349   // Returns whether a field is in the same region as the obj it points to.
 350   template <typename T>
 351   static bool is_in_same_region(T* p, oop obj) {
 352     assert(p != NULL, "p can't be NULL");
 353     assert(obj != NULL, "obj can't be NULL");
 354     return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
 355   }
 356 
 357   static size_t max_region_size();
 358   static size_t min_region_size_in_words();
 359 
 360   // It sets up the heap region size (GrainBytes / GrainWords), as
 361   // well as other related fields that are based on the heap region
 362   // size (LogOfHRGrainBytes / LogOfHRGrainWords /
 363   // CardsPerRegion). All those fields are considered constant
 364   // throughout the JVM's execution, therefore they should only be set
 365   // up once during initialization time.
 366   static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
 367 
 368   // All allocated blocks are occupied by objects in a HeapRegion
 369   bool block_is_obj(const HeapWord* p) const;
 370 
 371   // Returns the object size for all valid block starts
 372   // and the amount of unallocated words if called on top()
 373   size_t block_size(const HeapWord* p) const;
 374 
 375   // Override for scan_and_forward support.
 376   void prepare_for_compaction(CompactPoint* cp);
 377 
 378   inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
 379   inline HeapWord* allocate_no_bot_updates(size_t word_size);
 380   inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
 381 
 382   // If this region is a member of a HeapRegionManager, the index in that
 383   // sequence, otherwise -1.
 384   uint hrm_index() const { return _hrm_index; }
 385 
 386   // The number of bytes marked live in the region in the last marking phase.
 387   size_t marked_bytes()    { return _prev_marked_bytes; }
 388   size_t live_bytes() {
 389     return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
 390   }
 391 
 392   // The number of bytes counted in the next marking.
 393   size_t next_marked_bytes() { return _next_marked_bytes; }
 394   // The number of bytes live wrt the next marking.
 395   size_t next_live_bytes() {
 396     return
 397       (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
 398   }
 399 
 400   // A lower bound on the amount of garbage bytes in the region.
 401   size_t garbage_bytes() {
 402     size_t used_at_mark_start_bytes =
 403       (prev_top_at_mark_start() - bottom()) * HeapWordSize;
 404     return used_at_mark_start_bytes - marked_bytes();
 405   }
 406 
 407   // Return the amount of bytes we'll reclaim if we collect this
 408   // region. This includes not only the known garbage bytes in the
 409   // region but also any unallocated space in it, i.e., [top, end),
 410   // since it will also be reclaimed if we collect the region.
 411   size_t reclaimable_bytes() {
 412     size_t known_live_bytes = live_bytes();
 413     assert(known_live_bytes <= capacity(), "sanity");
 414     return capacity() - known_live_bytes;
 415   }
 416 
 417   // An upper bound on the number of live bytes in the region.
 418   size_t max_live_bytes() { return used() - garbage_bytes(); }
 419 
 420   void add_to_marked_bytes(size_t incr_bytes) {
 421     _next_marked_bytes = _next_marked_bytes + incr_bytes;
 422   }
 423 
 424   void zero_marked_bytes()      {
 425     _prev_marked_bytes = _next_marked_bytes = 0;
 426   }
 427 
 428   const char* get_type_str() const { return _type.get_str(); }
 429   const char* get_short_type_str() const { return _type.get_short_str(); }
 430 
 431   bool is_free() const { return _type.is_free(); }
 432 
 433   bool is_young()    const { return _type.is_young();    }
 434   bool is_eden()     const { return _type.is_eden();     }
 435   bool is_survivor() const { return _type.is_survivor(); }
 436 
 437   bool is_humongous() const { return _type.is_humongous(); }
 438   bool is_starts_humongous() const { return _type.is_starts_humongous(); }
 439   bool is_continues_humongous() const { return _type.is_continues_humongous();   }
 440 
 441   bool is_old() const { return _type.is_old(); }
 442 
 443   // A pinned region contains objects which are not moved by garbage collections.
 444   // Humongous regions and archive regions are pinned.
 445   bool is_pinned() const { return _type.is_pinned(); }
 446 
 447   // An archive region is a pinned region, also tagged as old, which
 448   // should not be marked during mark/sweep. This allows the address
 449   // space to be shared by JVM instances.
 450   bool is_archive() const { return _type.is_archive(); }
 451 
 452   // For a humongous region, region in which it starts.
 453   HeapRegion* humongous_start_region() const {
 454     return _humongous_start_region;
 455   }
 456 
 457   // Makes the current region be a "starts humongous" region, i.e.,
 458   // the first region in a series of one or more contiguous regions
 459   // that will contain a single "humongous" object.
 460   //
 461   // obj_top : points to the top of the humongous object.
 462   // fill_size : size of the filler object at the end of the region series.
 463   void set_starts_humongous(HeapWord* obj_top, size_t fill_size);
 464 
 465   // Makes the current region be a "continues humongous'
 466   // region. first_hr is the "start humongous" region of the series
 467   // which this region will be part of.
 468   void set_continues_humongous(HeapRegion* first_hr);
 469 
 470   // Unsets the humongous-related fields on the region.
 471   void clear_humongous();
 472 
 473   // If the region has a remembered set, return a pointer to it.
 474   HeapRegionRemSet* rem_set() const {
 475     return _rem_set;
 476   }
 477 
 478   inline bool in_collection_set() const;
 479 
 480   inline HeapRegion* next_in_collection_set() const;
 481   inline void set_next_in_collection_set(HeapRegion* r);
 482 
 483   void set_allocation_context(AllocationContext_t context) {
 484     _allocation_context = context;
 485   }
 486 
 487   AllocationContext_t  allocation_context() const {
 488     return _allocation_context;
 489   }
 490 
 491   // Methods used by the HeapRegionSetBase class and subclasses.
 492 
 493   // Getter and setter for the next and prev fields used to link regions into
 494   // linked lists.
 495   HeapRegion* next()              { return _next; }
 496   HeapRegion* prev()              { return _prev; }
 497 
 498   void set_next(HeapRegion* next) { _next = next; }
 499   void set_prev(HeapRegion* prev) { _prev = prev; }
 500 
 501   // Every region added to a set is tagged with a reference to that
 502   // set. This is used for doing consistency checking to make sure that
 503   // the contents of a set are as they should be and it's only
 504   // available in non-product builds.
 505 #ifdef ASSERT
 506   void set_containing_set(HeapRegionSetBase* containing_set) {
 507     assert((containing_set == NULL && _containing_set != NULL) ||
 508            (containing_set != NULL && _containing_set == NULL),
 509            "containing_set: " PTR_FORMAT " "
 510            "_containing_set: " PTR_FORMAT,
 511            p2i(containing_set), p2i(_containing_set));
 512 
 513     _containing_set = containing_set;
 514   }
 515 
 516   HeapRegionSetBase* containing_set() { return _containing_set; }
 517 #else // ASSERT
 518   void set_containing_set(HeapRegionSetBase* containing_set) { }
 519 
 520   // containing_set() is only used in asserts so there's no reason
 521   // to provide a dummy version of it.
 522 #endif // ASSERT
 523 
 524   HeapRegion* get_next_young_region() { return _next_young_region; }
 525   void set_next_young_region(HeapRegion* hr) {
 526     _next_young_region = hr;
 527   }
 528 
 529   HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
 530   HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
 531   void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
 532   bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
 533 
 534   // Reset HR stuff to default values.
 535   void hr_clear(bool par, bool clear_space, bool locked = false);
 536   void par_clear();
 537 
 538   // Get the start of the unmarked area in this region.
 539   HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
 540   HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
 541 
 542   // Note the start or end of marking. This tells the heap region
 543   // that the collector is about to start or has finished (concurrently)
 544   // marking the heap.
 545 
 546   // Notify the region that concurrent marking is starting. Initialize
 547   // all fields related to the next marking info.
 548   inline void note_start_of_marking();
 549 
 550   // Notify the region that concurrent marking has finished. Copy the
 551   // (now finalized) next marking info fields into the prev marking
 552   // info fields.
 553   inline void note_end_of_marking();
 554 
 555   // Notify the region that it will be used as to-space during a GC
 556   // and we are about to start copying objects into it.
 557   inline void note_start_of_copying(bool during_initial_mark);
 558 
 559   // Notify the region that it ceases being to-space during a GC and
 560   // we will not copy objects into it any more.
 561   inline void note_end_of_copying(bool during_initial_mark);
 562 
 563   // Notify the region that we are about to start processing
 564   // self-forwarded objects during evac failure handling.
 565   void note_self_forwarding_removal_start(bool during_initial_mark,
 566                                           bool during_conc_mark);
 567 
 568   // Notify the region that we have finished processing self-forwarded
 569   // objects during evac failure handling.
 570   void note_self_forwarding_removal_end(bool during_initial_mark,
 571                                         bool during_conc_mark,
 572                                         size_t marked_bytes);
 573 
 574   // Returns "false" iff no object in the region was allocated when the
 575   // last mark phase ended.
 576   bool is_marked() { return _prev_top_at_mark_start != bottom(); }
 577 
 578   void reset_during_compaction() {
 579     assert(is_humongous(),
 580            "should only be called for humongous regions");
 581 
 582     zero_marked_bytes();
 583     init_top_at_mark_start();
 584   }
 585 
 586   void calc_gc_efficiency(void);
 587   double gc_efficiency() { return _gc_efficiency;}
 588 
 589   int  young_index_in_cset() const { return _young_index_in_cset; }
 590   void set_young_index_in_cset(int index) {
 591     assert( (index == -1) || is_young(), "pre-condition" );
 592     _young_index_in_cset = index;
 593   }
 594 
 595   int age_in_surv_rate_group() {
 596     assert( _surv_rate_group != NULL, "pre-condition" );
 597     assert( _age_index > -1, "pre-condition" );
 598     return _surv_rate_group->age_in_group(_age_index);
 599   }
 600 
 601   void record_surv_words_in_group(size_t words_survived) {
 602     assert( _surv_rate_group != NULL, "pre-condition" );
 603     assert( _age_index > -1, "pre-condition" );
 604     int age_in_group = age_in_surv_rate_group();
 605     _surv_rate_group->record_surviving_words(age_in_group, words_survived);
 606   }
 607 
 608   int age_in_surv_rate_group_cond() {
 609     if (_surv_rate_group != NULL)
 610       return age_in_surv_rate_group();
 611     else
 612       return -1;
 613   }
 614 
 615   SurvRateGroup* surv_rate_group() {
 616     return _surv_rate_group;
 617   }
 618 
 619   void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
 620     assert( surv_rate_group != NULL, "pre-condition" );
 621     assert( _surv_rate_group == NULL, "pre-condition" );
 622     assert( is_young(), "pre-condition" );
 623 
 624     _surv_rate_group = surv_rate_group;
 625     _age_index = surv_rate_group->next_age_index();
 626   }
 627 
 628   void uninstall_surv_rate_group() {
 629     if (_surv_rate_group != NULL) {
 630       assert( _age_index > -1, "pre-condition" );
 631       assert( is_young(), "pre-condition" );
 632 
 633       _surv_rate_group = NULL;
 634       _age_index = -1;
 635     } else {
 636       assert( _age_index == -1, "pre-condition" );
 637     }
 638   }
 639 
 640   void set_free() { _type.set_free(); }
 641 
 642   void set_eden()        { _type.set_eden();        }
 643   void set_eden_pre_gc() { _type.set_eden_pre_gc(); }
 644   void set_survivor()    { _type.set_survivor();    }
 645 
 646   void set_old() { _type.set_old(); }
 647 
 648   void set_archive() { _type.set_archive(); }
 649 
 650   // Determine if an object has been allocated since the last
 651   // mark performed by the collector. This returns true iff the object
 652   // is within the unmarked area of the region.
 653   bool obj_allocated_since_prev_marking(oop obj) const {
 654     return (HeapWord *) obj >= prev_top_at_mark_start();
 655   }
 656   bool obj_allocated_since_next_marking(oop obj) const {
 657     return (HeapWord *) obj >= next_top_at_mark_start();
 658   }
 659 
 660   // Returns the "evacuation_failed" property of the region.
 661   bool evacuation_failed() { return _evacuation_failed; }
 662 
 663   // Sets the "evacuation_failed" property of the region.
 664   void set_evacuation_failed(bool b) {
 665     _evacuation_failed = b;
 666 
 667     if (b) {
 668       _next_marked_bytes = 0;
 669     }
 670   }
 671 
 672   // Requires that "mr" be entirely within the region.
 673   // Apply "cl->do_object" to all objects that intersect with "mr".
 674   // If the iteration encounters an unparseable portion of the region,
 675   // or if "cl->abort()" is true after a closure application,
 676   // terminate the iteration and return the address of the start of the
 677   // subregion that isn't done.  (The two can be distinguished by querying
 678   // "cl->abort()".)  Return of "NULL" indicates that the iteration
 679   // completed.
 680   HeapWord*
 681   object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
 682 
 683   // filter_young: if true and the region is a young region then we
 684   // skip the iteration.
 685   // card_ptr: if not NULL, and we decide that the card is not young
 686   // and we iterate over it, we'll clean the card before we start the
 687   // iteration.
 688   HeapWord*
 689   oops_on_card_seq_iterate_careful(MemRegion mr,
 690                                    FilterOutOfRegionClosure* cl,
 691                                    bool filter_young,
 692                                    jbyte* card_ptr);
 693 
 694   size_t recorded_rs_length() const        { return _recorded_rs_length; }
 695   double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
 696   size_t predicted_bytes_to_copy() const   { return _predicted_bytes_to_copy; }
 697 
 698   void set_recorded_rs_length(size_t rs_length) {
 699     _recorded_rs_length = rs_length;
 700   }
 701 
 702   void set_predicted_elapsed_time_ms(double ms) {
 703     _predicted_elapsed_time_ms = ms;
 704   }
 705 
 706   void set_predicted_bytes_to_copy(size_t bytes) {
 707     _predicted_bytes_to_copy = bytes;
 708   }
 709 
 710   virtual CompactibleSpace* next_compaction_space() const;
 711 
 712   virtual void reset_after_compaction();
 713 
 714   // Routines for managing a list of code roots (attached to the
 715   // this region's RSet) that point into this heap region.
 716   void add_strong_code_root(nmethod* nm);
 717   void add_strong_code_root_locked(nmethod* nm);
 718   void remove_strong_code_root(nmethod* nm);
 719 
 720   // Applies blk->do_code_blob() to each of the entries in
 721   // the strong code roots list for this region
 722   void strong_code_roots_do(CodeBlobClosure* blk) const;
 723 
 724   // Verify that the entries on the strong code root list for this
 725   // region are live and include at least one pointer into this region.
 726   void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
 727 
 728   void print() const;
 729   void print_on(outputStream* st) const;
 730 
 731   // vo == UsePrevMarking  -> use "prev" marking information,
 732   // vo == UseNextMarking -> use "next" marking information
 733   // vo == UseMarkWord    -> use the mark word in the object header
 734   //
 735   // NOTE: Only the "prev" marking information is guaranteed to be
 736   // consistent most of the time, so most calls to this should use
 737   // vo == UsePrevMarking.
 738   // Currently, there is only one case where this is called with
 739   // vo == UseNextMarking, which is to verify the "next" marking
 740   // information at the end of remark.
 741   // Currently there is only one place where this is called with
 742   // vo == UseMarkWord, which is to verify the marking during a
 743   // full GC.
 744   void verify(VerifyOption vo, bool *failures) const;
 745 
 746   // Override; it uses the "prev" marking information
 747   virtual void verify() const;
 748 
 749   void verify_rem_set(VerifyOption vo, bool *failures) const;
 750   void verify_rem_set() const;
 751 };
 752 
 753 // HeapRegionClosure is used for iterating over regions.
 754 // Terminates the iteration when the "doHeapRegion" method returns "true".
 755 class HeapRegionClosure : public StackObj {
 756   friend class HeapRegionManager;
 757   friend class G1CollectedHeap;
 758 
 759   bool _complete;
 760   void incomplete() { _complete = false; }
 761 
 762  public:
 763   HeapRegionClosure(): _complete(true) {}
 764 
 765   // Typically called on each region until it returns true.
 766   virtual bool doHeapRegion(HeapRegion* r) = 0;
 767 
 768   // True after iteration if the closure was applied to all heap regions
 769   // and returned "false" in all cases.
 770   bool complete() { return _complete; }
 771 };
 772 
 773 #endif // SHARE_VM_GC_G1_HEAPREGION_HPP