1 /*
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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/g1BlockOffsetTable.hpp"
  29 #include "gc/g1/g1HeapRegionTraceType.hpp"
  30 #include "gc/g1/heapRegionTracer.hpp"
  31 #include "gc/g1/heapRegionType.hpp"
  32 #include "gc/g1/survRateGroup.hpp"
  33 #include "gc/shared/ageTable.hpp"
  34 #include "gc/shared/cardTable.hpp"
  35 #include "gc/shared/spaceDecorator.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 // Each heap region is self contained. top() and end() can never
  49 // be set beyond the end of the region. For humongous objects,
  50 // the first region is a StartsHumongous region. If the humongous
  51 // object is larger than a heap region, the following regions will
  52 // be of type ContinuesHumongous. In this case the top() of the
  53 // StartHumongous region and all ContinuesHumongous regions except
  54 // the last will point to their own end. The last ContinuesHumongous
  55 // region may have top() equal the end of object if there isn't
  56 // room for filler objects to pad out to the end of the region.
  57 
  58 class G1CollectedHeap;
  59 class G1CMBitMap;
  60 class G1IsAliveAndApplyClosure;
  61 class HeapRegionRemSet;
  62 class HeapRegionRemSetIterator;
  63 class HeapRegion;
  64 class HeapRegionSetBase;
  65 class nmethod;
  66 
  67 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
  68 #define HR_FORMAT_PARAMS(_hr_) \
  69                 (_hr_)->hrm_index(), \
  70                 (_hr_)->get_short_type_str(), \
  71                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
  72 
  73 // sentinel value for hrm_index
  74 #define G1_NO_HRM_INDEX ((uint) -1)
  75 
  76 // The complicating factor is that BlockOffsetTable diverged
  77 // significantly, and we need functionality that is only in the G1 version.
  78 // So I copied that code, which led to an alternate G1 version of
  79 // OffsetTableContigSpace.  If the two versions of BlockOffsetTable could
  80 // be reconciled, then G1OffsetTableContigSpace could go away.
  81 
  82 // The idea behind time stamps is the following. We want to keep track of
  83 // the highest address where it's safe to scan objects for each region.
  84 // This is only relevant for current GC alloc regions so we keep a time stamp
  85 // per region to determine if the region has been allocated during the current
  86 // GC or not. If the time stamp is current we report a scan_top value which
  87 // was saved at the end of the previous GC for retained alloc regions and which is
  88 // equal to the bottom for all other regions.
  89 // There is a race between card scanners and allocating gc workers where we must ensure
  90 // that card scanners do not read the memory allocated by the gc workers.
  91 // In order to enforce that, we must not return a value of _top which is more recent than the
  92 // time stamp. This is due to the fact that a region may become a gc alloc region at
  93 // some point after we've read the timestamp value as being < the current time stamp.
  94 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
  95 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
  96 // evacuation pauses between two cleanups, which is _highly_ unlikely.
  97 class G1ContiguousSpace: public CompactibleSpace {
  98   friend class VMStructs;
  99   HeapWord* volatile _top;
 100  protected:
 101   G1BlockOffsetTablePart _bot_part;
 102   Mutex _par_alloc_lock;
 103   // When we need to retire an allocation region, while other threads
 104   // are also concurrently trying to allocate into it, we typically
 105   // allocate a dummy object at the end of the region to ensure that
 106   // no more allocations can take place in it. However, sometimes we
 107   // want to know where the end of the last "real" object we allocated
 108   // into the region was and this is what this keeps track.
 109   HeapWord* _pre_dummy_top;
 110 
 111  public:
 112   G1ContiguousSpace(G1BlockOffsetTable* bot);
 113 
 114   void set_top(HeapWord* value) { _top = value; }
 115   HeapWord* top() const { return _top; }
 116 
 117  protected:
 118   // Reset the G1ContiguousSpace.
 119   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
 120 
 121   HeapWord* volatile* top_addr() { return &_top; }
 122   // Try to allocate at least min_word_size and up to desired_size from this Space.
 123   // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
 124   // space allocated.
 125   // This version assumes that all allocation requests to this Space are properly
 126   // synchronized.
 127   inline HeapWord* allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 128   // Try to allocate at least min_word_size and up to desired_size from this Space.
 129   // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
 130   // space allocated.
 131   // This version synchronizes with other calls to par_allocate_impl().
 132   inline HeapWord* par_allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 133 
 134  public:
 135   void reset_after_compaction() { set_top(compaction_top()); }
 136 
 137   size_t used() const { return byte_size(bottom(), top()); }
 138   size_t free() const { return byte_size(top(), end()); }
 139   bool is_free_block(const HeapWord* p) const { return p >= top(); }
 140 
 141   MemRegion used_region() const { return MemRegion(bottom(), top()); }
 142 
 143   void object_iterate(ObjectClosure* blk);
 144   void safe_object_iterate(ObjectClosure* blk);
 145 
 146   void mangle_unused_area() PRODUCT_RETURN;
 147   void mangle_unused_area_complete() PRODUCT_RETURN;
 148 
 149   // See the comment above in the declaration of _pre_dummy_top for an
 150   // explanation of what it is.
 151   void set_pre_dummy_top(HeapWord* pre_dummy_top) {
 152     assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
 153     _pre_dummy_top = pre_dummy_top;
 154   }
 155   HeapWord* pre_dummy_top() {
 156     return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
 157   }
 158   void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
 159 
 160   virtual void clear(bool mangle_space);
 161 
 162   HeapWord* block_start(const void* p);
 163   HeapWord* block_start_const(const void* p) const;
 164 
 165   // Allocation (return NULL if full).  Assumes the caller has established
 166   // mutually exclusive access to the space.
 167   HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 168   // Allocation (return NULL if full).  Enforces mutual exclusion internally.
 169   HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 170 
 171   virtual HeapWord* allocate(size_t word_size);
 172   virtual HeapWord* par_allocate(size_t word_size);
 173 
 174   HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
 175 
 176   // MarkSweep support phase3
 177   virtual HeapWord* initialize_threshold();
 178   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
 179 
 180   virtual void print() const;
 181 
 182   void reset_bot() {
 183     _bot_part.reset_bot();
 184   }
 185 
 186   void print_bot_on(outputStream* out) {
 187     _bot_part.print_on(out);
 188   }
 189 };
 190 
 191 class HeapRegion: public G1ContiguousSpace {
 192   friend class VMStructs;
 193   // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
 194   template <typename SpaceType>
 195   friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
 196  private:
 197 
 198   // The remembered set for this region.
 199   // (Might want to make this "inline" later, to avoid some alloc failure
 200   // issues.)
 201   HeapRegionRemSet* _rem_set;
 202 
 203   // Auxiliary functions for scan_and_forward support.
 204   // See comments for CompactibleSpace for more information.
 205   inline HeapWord* scan_limit() const {
 206     return top();
 207   }
 208 
 209   inline bool scanned_block_is_obj(const HeapWord* addr) const {
 210     return true; // Always true, since scan_limit is top
 211   }
 212 
 213   inline size_t scanned_block_size(const HeapWord* addr) const {
 214     return HeapRegion::block_size(addr); // Avoid virtual call
 215   }
 216 
 217   void report_region_type_change(G1HeapRegionTraceType::Type to);
 218 
 219   // Returns whether the given object address refers to a dead object, and either the
 220   // size of the object (if live) or the size of the block (if dead) in size.
 221   // May
 222   // - only called with obj < top()
 223   // - not called on humongous objects or archive regions
 224   inline bool is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const;
 225 
 226  protected:
 227   // The index of this region in the heap region sequence.
 228   uint  _hrm_index;
 229 
 230   HeapRegionType _type;
 231 
 232   // For a humongous region, region in which it starts.
 233   HeapRegion* _humongous_start_region;
 234 
 235   // True iff an attempt to evacuate an object in the region failed.
 236   bool _evacuation_failed;
 237 
 238   // Fields used by the HeapRegionSetBase class and subclasses.
 239   HeapRegion* _next;
 240   HeapRegion* _prev;
 241 #ifdef ASSERT
 242   HeapRegionSetBase* _containing_set;
 243 #endif // ASSERT
 244 
 245   // We use concurrent marking to determine the amount of live data
 246   // in each heap region.
 247   size_t _prev_marked_bytes;    // Bytes known to be live via last completed marking.
 248   size_t _next_marked_bytes;    // Bytes known to be live via in-progress marking.
 249 
 250   // The calculated GC efficiency of the region.
 251   double _gc_efficiency;
 252 
 253   int  _young_index_in_cset;
 254   SurvRateGroup* _surv_rate_group;
 255   int  _age_index;
 256 
 257   // The start of the unmarked area. The unmarked area extends from this
 258   // word until the top and/or end of the region, and is the part
 259   // of the region for which no marking was done, i.e. objects may
 260   // have been allocated in this part since the last mark phase.
 261   // "prev" is the top at the start of the last completed marking.
 262   // "next" is the top at the start of the in-progress marking (if any.)
 263   HeapWord* _prev_top_at_mark_start;
 264   HeapWord* _next_top_at_mark_start;
 265   // If a collection pause is in progress, this is the top at the start
 266   // of that pause.
 267 
 268   void init_top_at_mark_start() {
 269     assert(_prev_marked_bytes == 0 &&
 270            _next_marked_bytes == 0,
 271            "Must be called after zero_marked_bytes.");
 272     HeapWord* bot = bottom();
 273     _prev_top_at_mark_start = bot;
 274     _next_top_at_mark_start = bot;
 275   }
 276 
 277   // Cached attributes used in the collection set policy information
 278 
 279   // The RSet length that was added to the total value
 280   // for the collection set.
 281   size_t _recorded_rs_length;
 282 
 283   // The predicted elapsed time that was added to total value
 284   // for the collection set.
 285   double _predicted_elapsed_time_ms;
 286 
 287   // Iterate over the references in a humongous objects and apply the given closure
 288   // to them.
 289   // Humongous objects are allocated directly in the old-gen. So we need special
 290   // handling for concurrent processing encountering an in-progress allocation.
 291   template <class Closure, bool is_gc_active>
 292   inline bool do_oops_on_card_in_humongous(MemRegion mr,
 293                                            Closure* cl,
 294                                            G1CollectedHeap* g1h);
 295 
 296   // Returns the block size of the given (dead, potentially having its class unloaded) object
 297   // starting at p extending to at most the prev TAMS using the given mark bitmap.
 298   inline size_t block_size_using_bitmap(const HeapWord* p, const G1CMBitMap* const prev_bitmap) const;
 299  public:
 300   HeapRegion(uint hrm_index,
 301              G1BlockOffsetTable* bot,
 302              MemRegion mr);
 303 
 304   // Initializing the HeapRegion not only resets the data structure, but also
 305   // resets the BOT for that heap region.
 306   // The default values for clear_space means that we will do the clearing if
 307   // there's clearing to be done ourselves. We also always mangle the space.
 308   virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
 309 
 310   static int    LogOfHRGrainBytes;
 311   static int    LogOfHRGrainWords;
 312 
 313   static size_t GrainBytes;
 314   static size_t GrainWords;
 315   static size_t CardsPerRegion;
 316 
 317   static size_t align_up_to_region_byte_size(size_t sz) {
 318     return (sz + (size_t) GrainBytes - 1) &
 319                                       ~((1 << (size_t) LogOfHRGrainBytes) - 1);
 320   }
 321 
 322 
 323   // Returns whether a field is in the same region as the obj it points to.
 324   template <typename T>
 325   static bool is_in_same_region(T* p, oop obj) {
 326     assert(p != NULL, "p can't be NULL");
 327     assert(obj != NULL, "obj can't be NULL");
 328     return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
 329   }
 330 
 331   static size_t max_region_size();
 332   static size_t min_region_size_in_words();
 333 
 334   // It sets up the heap region size (GrainBytes / GrainWords), as
 335   // well as other related fields that are based on the heap region
 336   // size (LogOfHRGrainBytes / LogOfHRGrainWords /
 337   // CardsPerRegion). All those fields are considered constant
 338   // throughout the JVM's execution, therefore they should only be set
 339   // up once during initialization time.
 340   static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
 341 
 342   // All allocated blocks are occupied by objects in a HeapRegion
 343   bool block_is_obj(const HeapWord* p) const;
 344 
 345   // Returns whether the given object is dead based on TAMS and bitmap.
 346   bool is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const;
 347 
 348   // Returns the object size for all valid block starts
 349   // and the amount of unallocated words if called on top()
 350   size_t block_size(const HeapWord* p) const;
 351 
 352   // Scans through the region using the bitmap to determine what
 353   // objects to call size_t ApplyToMarkedClosure::apply(oop) for.
 354   template<typename ApplyToMarkedClosure>
 355   inline void apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure);
 356   // Override for scan_and_forward support.
 357   void prepare_for_compaction(CompactPoint* cp);
 358   // Update heap region to be consistent after compaction.
 359   void complete_compaction();
 360 
 361   inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
 362   inline HeapWord* allocate_no_bot_updates(size_t word_size);
 363   inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
 364 
 365   // If this region is a member of a HeapRegionManager, the index in that
 366   // sequence, otherwise -1.
 367   uint hrm_index() const { return _hrm_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     return used_at_mark_start_bytes - marked_bytes();
 388   }
 389 
 390   // Return the amount of bytes we'll reclaim if we collect this
 391   // region. This includes not only the known garbage bytes in the
 392   // region but also any unallocated space in it, i.e., [top, end),
 393   // since it will also be reclaimed if we collect the region.
 394   size_t reclaimable_bytes() {
 395     size_t known_live_bytes = live_bytes();
 396     assert(known_live_bytes <= capacity(), "sanity");
 397     return capacity() - known_live_bytes;
 398   }
 399 
 400   // An upper bound on the number of live bytes in the region.
 401   size_t max_live_bytes() { return used() - garbage_bytes(); }
 402 
 403   void add_to_marked_bytes(size_t incr_bytes) {
 404     _next_marked_bytes = _next_marked_bytes + incr_bytes;
 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   G1HeapRegionTraceType::Type get_trace_type() { return _type.get_trace_type(); }
 414 
 415   bool is_free() const { return _type.is_free(); }
 416 
 417   bool is_young()    const { return _type.is_young();    }
 418   bool is_eden()     const { return _type.is_eden();     }
 419   bool is_survivor() const { return _type.is_survivor(); }
 420 
 421   bool is_humongous() const { return _type.is_humongous(); }
 422   bool is_starts_humongous() const { return _type.is_starts_humongous(); }
 423   bool is_continues_humongous() const { return _type.is_continues_humongous();   }
 424 
 425   bool is_old() const { return _type.is_old(); }
 426 
 427   bool is_old_or_humongous() const { return _type.is_old_or_humongous(); }
 428 
 429   bool is_old_or_humongous_or_archive() const { return _type.is_old_or_humongous_or_archive(); }
 430 
 431   // A pinned region contains objects which are not moved by garbage collections.
 432   // Humongous regions and archive regions are pinned.
 433   bool is_pinned() const { return _type.is_pinned(); }
 434 
 435   // An archive region is a pinned region, also tagged as old, which
 436   // should not be marked during mark/sweep. This allows the address
 437   // space to be shared by JVM instances.
 438   bool is_archive()        const { return _type.is_archive(); }
 439   bool is_open_archive()   const { return _type.is_open_archive(); }
 440   bool is_closed_archive() const { return _type.is_closed_archive(); }
 441 
 442   // For a humongous region, region in which it starts.
 443   HeapRegion* humongous_start_region() const {
 444     return _humongous_start_region;
 445   }
 446 
 447   // Makes the current region be a "starts humongous" region, i.e.,
 448   // the first region in a series of one or more contiguous regions
 449   // that will contain a single "humongous" object.
 450   //
 451   // obj_top : points to the top of the humongous object.
 452   // fill_size : size of the filler object at the end of the region series.
 453   void set_starts_humongous(HeapWord* obj_top, size_t fill_size);
 454 
 455   // Makes the current region be a "continues humongous'
 456   // region. first_hr is the "start humongous" region of the series
 457   // which this region will be part of.
 458   void set_continues_humongous(HeapRegion* first_hr);
 459 
 460   // Unsets the humongous-related fields on the region.
 461   void clear_humongous();
 462 
 463   // If the region has a remembered set, return a pointer to it.
 464   HeapRegionRemSet* rem_set() const {
 465     return _rem_set;
 466   }
 467 
 468   inline bool in_collection_set() const;
 469 
 470   // Methods used by the HeapRegionSetBase class and subclasses.
 471 
 472   // Getter and setter for the next and prev fields used to link regions into
 473   // linked lists.
 474   HeapRegion* next()              { return _next; }
 475   HeapRegion* prev()              { return _prev; }
 476 
 477   void set_next(HeapRegion* next) { _next = next; }
 478   void set_prev(HeapRegion* prev) { _prev = prev; }
 479 
 480   // Every region added to a set is tagged with a reference to that
 481   // set. This is used for doing consistency checking to make sure that
 482   // the contents of a set are as they should be and it's only
 483   // available in non-product builds.
 484 #ifdef ASSERT
 485   void set_containing_set(HeapRegionSetBase* containing_set) {
 486     assert((containing_set == NULL && _containing_set != NULL) ||
 487            (containing_set != NULL && _containing_set == NULL),
 488            "containing_set: " PTR_FORMAT " "
 489            "_containing_set: " PTR_FORMAT,
 490            p2i(containing_set), p2i(_containing_set));
 491 
 492     _containing_set = containing_set;
 493   }
 494 
 495   HeapRegionSetBase* containing_set() { return _containing_set; }
 496 #else // ASSERT
 497   void set_containing_set(HeapRegionSetBase* containing_set) { }
 498 
 499   // containing_set() is only used in asserts so there's no reason
 500   // to provide a dummy version of it.
 501 #endif // ASSERT
 502 
 503 
 504   // Reset the HeapRegion to default values.
 505   // If skip_remset is true, do not clear the remembered set.
 506   // If clear_space is true, clear the HeapRegion's memory.
 507   // If locked is true, assume we are the only thread doing this operation.
 508   void hr_clear(bool skip_remset, bool clear_space, bool locked = false);
 509   // Clear the card table corresponding to this region.
 510   void clear_cardtable();
 511 
 512   // Get the start of the unmarked area in this region.
 513   HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
 514   HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
 515 
 516   // Note the start or end of marking. This tells the heap region
 517   // that the collector is about to start or has finished (concurrently)
 518   // marking the heap.
 519 
 520   // Notify the region that concurrent marking is starting. Initialize
 521   // all fields related to the next marking info.
 522   inline void note_start_of_marking();
 523 
 524   // Notify the region that concurrent marking has finished. Copy the
 525   // (now finalized) next marking info fields into the prev marking
 526   // info fields.
 527   inline void note_end_of_marking();
 528 
 529   // Notify the region that we are about to start processing
 530   // self-forwarded objects during evac failure handling.
 531   void note_self_forwarding_removal_start(bool during_initial_mark,
 532                                           bool during_conc_mark);
 533 
 534   // Notify the region that we have finished processing self-forwarded
 535   // objects during evac failure handling.
 536   void note_self_forwarding_removal_end(size_t marked_bytes);
 537 
 538   void reset_during_compaction() {
 539     assert(is_humongous(),
 540            "should only be called for humongous regions");
 541 
 542     zero_marked_bytes();
 543     init_top_at_mark_start();
 544   }
 545 
 546   void calc_gc_efficiency(void);
 547   double gc_efficiency() { return _gc_efficiency;}
 548 
 549   int  young_index_in_cset() const { return _young_index_in_cset; }
 550   void set_young_index_in_cset(int index) {
 551     assert( (index == -1) || is_young(), "pre-condition" );
 552     _young_index_in_cset = index;
 553   }
 554 
 555   int age_in_surv_rate_group() {
 556     assert( _surv_rate_group != NULL, "pre-condition" );
 557     assert( _age_index > -1, "pre-condition" );
 558     return _surv_rate_group->age_in_group(_age_index);
 559   }
 560 
 561   void record_surv_words_in_group(size_t words_survived) {
 562     assert( _surv_rate_group != NULL, "pre-condition" );
 563     assert( _age_index > -1, "pre-condition" );
 564     int age_in_group = age_in_surv_rate_group();
 565     _surv_rate_group->record_surviving_words(age_in_group, words_survived);
 566   }
 567 
 568   int age_in_surv_rate_group_cond() {
 569     if (_surv_rate_group != NULL)
 570       return age_in_surv_rate_group();
 571     else
 572       return -1;
 573   }
 574 
 575   SurvRateGroup* surv_rate_group() {
 576     return _surv_rate_group;
 577   }
 578 
 579   void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
 580     assert( surv_rate_group != NULL, "pre-condition" );
 581     assert( _surv_rate_group == NULL, "pre-condition" );
 582     assert( is_young(), "pre-condition" );
 583 
 584     _surv_rate_group = surv_rate_group;
 585     _age_index = surv_rate_group->next_age_index();
 586   }
 587 
 588   void uninstall_surv_rate_group() {
 589     if (_surv_rate_group != NULL) {
 590       assert( _age_index > -1, "pre-condition" );
 591       assert( is_young(), "pre-condition" );
 592 
 593       _surv_rate_group = NULL;
 594       _age_index = -1;
 595     } else {
 596       assert( _age_index == -1, "pre-condition" );
 597     }
 598   }
 599 
 600   void set_free();
 601 
 602   void set_eden();
 603   void set_eden_pre_gc();
 604   void set_survivor();
 605 
 606   void move_to_old();
 607   void set_old();
 608 
 609   void set_open_archive();
 610   void set_closed_archive();
 611 
 612   // Determine if an object has been allocated since the last
 613   // mark performed by the collector. This returns true iff the object
 614   // is within the unmarked area of the region.
 615   bool obj_allocated_since_prev_marking(oop obj) const {
 616     return (HeapWord *) obj >= prev_top_at_mark_start();
 617   }
 618   bool obj_allocated_since_next_marking(oop obj) const {
 619     return (HeapWord *) obj >= next_top_at_mark_start();
 620   }
 621 
 622   // Returns the "evacuation_failed" property of the region.
 623   bool evacuation_failed() { return _evacuation_failed; }
 624 
 625   // Sets the "evacuation_failed" property of the region.
 626   void set_evacuation_failed(bool b) {
 627     _evacuation_failed = b;
 628 
 629     if (b) {
 630       _next_marked_bytes = 0;
 631     }
 632   }
 633 
 634   // Iterate over the objects overlapping part of a card, applying cl
 635   // to all references in the region.  This is a helper for
 636   // G1RemSet::refine_card*, and is tightly coupled with them.
 637   // mr is the memory region covered by the card, trimmed to the
 638   // allocated space for this region.  Must not be empty.
 639   // This region must be old or humongous.
 640   // Returns true if the designated objects were successfully
 641   // processed, false if an unparsable part of the heap was
 642   // encountered; that only happens when invoked concurrently with the
 643   // mutator.
 644   template <bool is_gc_active, class Closure>
 645   inline bool oops_on_card_seq_iterate_careful(MemRegion mr, Closure* cl);
 646 
 647   size_t recorded_rs_length() const        { return _recorded_rs_length; }
 648   double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
 649 
 650   void set_recorded_rs_length(size_t rs_length) {
 651     _recorded_rs_length = rs_length;
 652   }
 653 
 654   void set_predicted_elapsed_time_ms(double ms) {
 655     _predicted_elapsed_time_ms = ms;
 656   }
 657 
 658   // Routines for managing a list of code roots (attached to the
 659   // this region's RSet) that point into this heap region.
 660   void add_strong_code_root(nmethod* nm);
 661   void add_strong_code_root_locked(nmethod* nm);
 662   void remove_strong_code_root(nmethod* nm);
 663 
 664   // Applies blk->do_code_blob() to each of the entries in
 665   // the strong code roots list for this region
 666   void strong_code_roots_do(CodeBlobClosure* blk) const;
 667 
 668   // Verify that the entries on the strong code root list for this
 669   // region are live and include at least one pointer into this region.
 670   void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
 671 
 672   void print() const;
 673   void print_on(outputStream* st) const;
 674 
 675   // vo == UsePrevMarking -> use "prev" marking information,
 676   // vo == UseNextMarking -> use "next" marking information
 677   // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
 678   //
 679   // NOTE: Only the "prev" marking information is guaranteed to be
 680   // consistent most of the time, so most calls to this should use
 681   // vo == UsePrevMarking.
 682   // Currently, there is only one case where this is called with
 683   // vo == UseNextMarking, which is to verify the "next" marking
 684   // information at the end of remark.
 685   // Currently there is only one place where this is called with
 686   // vo == UseFullMarking, which is to verify the marking during a
 687   // full GC.
 688   void verify(VerifyOption vo, bool *failures) const;
 689 
 690   // Override; it uses the "prev" marking information
 691   virtual void verify() const;
 692 
 693   void verify_rem_set(VerifyOption vo, bool *failures) const;
 694   void verify_rem_set() const;
 695 };
 696 
 697 // HeapRegionClosure is used for iterating over regions.
 698 // Terminates the iteration when the "do_heap_region" method returns "true".
 699 class HeapRegionClosure : public StackObj {
 700   friend class HeapRegionManager;
 701   friend class G1CollectionSet;
 702   friend class CollectionSetChooser;
 703 
 704   bool _is_complete;
 705   void set_incomplete() { _is_complete = false; }
 706 
 707  public:
 708   HeapRegionClosure(): _is_complete(true) {}
 709 
 710   // Typically called on each region until it returns true.
 711   virtual bool do_heap_region(HeapRegion* r) = 0;
 712 
 713   // True after iteration if the closure was applied to all heap regions
 714   // and returned "false" in all cases.
 715   bool is_complete() { return _is_complete; }
 716 };
 717 
 718 #endif // SHARE_VM_GC_G1_HEAPREGION_HPP