1 /*
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  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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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/g1HeapRegionTraceType.hpp"
  31 #include "gc/g1/heapRegionTracer.hpp"
  32 #include "gc/g1/heapRegionType.hpp"
  33 #include "gc/g1/survRateGroup.hpp"
  34 #include "gc/shared/ageTable.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. For the last ContinuesHumongous
  55 // region, top() will equal the object's top.
  56 
  57 class G1CollectedHeap;
  58 class HeapRegionRemSet;
  59 class HeapRegionRemSetIterator;
  60 class HeapRegion;
  61 class HeapRegionSetBase;
  62 class nmethod;
  63 
  64 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
  65 #define HR_FORMAT_PARAMS(_hr_) \
  66                 (_hr_)->hrm_index(), \
  67                 (_hr_)->get_short_type_str(), \
  68                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
  69 
  70 // sentinel value for hrm_index
  71 #define G1_NO_HRM_INDEX ((uint) -1)
  72 
  73 // A dirty card to oop closure for heap regions. It
  74 // knows how to get the G1 heap and how to use the bitmap
  75 // in the concurrent marker used by G1 to filter remembered
  76 // sets.
  77 
  78 class HeapRegionDCTOC : public DirtyCardToOopClosure {
  79 private:
  80   HeapRegion* _hr;
  81   G1ParPushHeapRSClosure* _rs_scan;
  82   G1CollectedHeap* _g1;
  83 
  84   // Walk the given memory region from bottom to (actual) top
  85   // looking for objects and applying the oop closure (_cl) to
  86   // them. The base implementation of this treats the area as
  87   // blocks, where a block may or may not be an object. Sub-
  88   // classes should override this to provide more accurate
  89   // or possibly more efficient walking.
  90   void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
  91 
  92 public:
  93   HeapRegionDCTOC(G1CollectedHeap* g1,
  94                   HeapRegion* hr,
  95                   G1ParPushHeapRSClosure* cl,
  96                   CardTableModRefBS::PrecisionStyle precision);
  97 };
  98 
  99 // The complicating factor is that BlockOffsetTable diverged
 100 // significantly, and we need functionality that is only in the G1 version.
 101 // So I copied that code, which led to an alternate G1 version of
 102 // OffsetTableContigSpace.  If the two versions of BlockOffsetTable could
 103 // be reconciled, then G1OffsetTableContigSpace could go away.
 104 
 105 // The idea behind time stamps is the following. We want to keep track of
 106 // the highest address where it's safe to scan objects for each region.
 107 // This is only relevant for current GC alloc regions so we keep a time stamp
 108 // per region to determine if the region has been allocated during the current
 109 // GC or not. If the time stamp is current we report a scan_top value which
 110 // was saved at the end of the previous GC for retained alloc regions and which is
 111 // equal to the bottom for all other regions.
 112 // There is a race between card scanners and allocating gc workers where we must ensure
 113 // that card scanners do not read the memory allocated by the gc workers.
 114 // In order to enforce that, we must not return a value of _top which is more recent than the
 115 // time stamp. This is due to the fact that a region may become a gc alloc region at
 116 // some point after we've read the timestamp value as being < the current time stamp.
 117 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
 118 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
 119 // evacuation pauses between two cleanups, which is _highly_ unlikely.
 120 class G1ContiguousSpace: public CompactibleSpace {
 121   friend class VMStructs;
 122   HeapWord* volatile _top;
 123   HeapWord* volatile _scan_top;
 124  protected:
 125   G1BlockOffsetTablePart _bot_part;
 126   Mutex _par_alloc_lock;
 127   volatile uint _gc_time_stamp;
 128   // When we need to retire an allocation region, while other threads
 129   // are also concurrently trying to allocate into it, we typically
 130   // allocate a dummy object at the end of the region to ensure that
 131   // no more allocations can take place in it. However, sometimes we
 132   // want to know where the end of the last "real" object we allocated
 133   // into the region was and this is what this keeps track.
 134   HeapWord* _pre_dummy_top;
 135 
 136  public:
 137   G1ContiguousSpace(G1BlockOffsetTable* bot);
 138 
 139   void set_top(HeapWord* value) { _top = value; }
 140   HeapWord* top() const { return _top; }
 141 
 142  protected:
 143   // Reset the G1ContiguousSpace.
 144   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
 145 
 146   HeapWord* volatile* top_addr() { return &_top; }
 147   // Try to allocate at least min_word_size and up to desired_size from this Space.
 148   // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
 149   // space allocated.
 150   // This version assumes that all allocation requests to this Space are properly
 151   // synchronized.
 152   inline HeapWord* allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 153   // Try to allocate at least min_word_size and up to desired_size from this Space.
 154   // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
 155   // space allocated.
 156   // This version synchronizes with other calls to par_allocate_impl().
 157   inline HeapWord* par_allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 158 
 159  public:
 160   void reset_after_compaction() { set_top(compaction_top()); }
 161 
 162   size_t used() const { return byte_size(bottom(), top()); }
 163   size_t free() const { return byte_size(top(), end()); }
 164   bool is_free_block(const HeapWord* p) const { return p >= top(); }
 165 
 166   MemRegion used_region() const { return MemRegion(bottom(), top()); }
 167 
 168   void object_iterate(ObjectClosure* blk);
 169   void safe_object_iterate(ObjectClosure* blk);
 170 
 171   void mangle_unused_area() PRODUCT_RETURN;
 172   void mangle_unused_area_complete() PRODUCT_RETURN;
 173 
 174   HeapWord* scan_top() const;
 175   void record_timestamp();
 176   void reset_gc_time_stamp() { _gc_time_stamp = 0; }
 177   uint get_gc_time_stamp() { return _gc_time_stamp; }
 178   void record_retained_region();
 179 
 180   // See the comment above in the declaration of _pre_dummy_top for an
 181   // explanation of what it is.
 182   void set_pre_dummy_top(HeapWord* pre_dummy_top) {
 183     assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
 184     _pre_dummy_top = pre_dummy_top;
 185   }
 186   HeapWord* pre_dummy_top() {
 187     return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
 188   }
 189   void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
 190 
 191   virtual void clear(bool mangle_space);
 192 
 193   HeapWord* block_start(const void* p);
 194   HeapWord* block_start_const(const void* p) const;
 195 
 196   // Allocation (return NULL if full).  Assumes the caller has established
 197   // mutually exclusive access to the space.
 198   HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 199   // Allocation (return NULL if full).  Enforces mutual exclusion internally.
 200   HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 201 
 202   virtual HeapWord* allocate(size_t word_size);
 203   virtual HeapWord* par_allocate(size_t word_size);
 204 
 205   HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
 206 
 207   // MarkSweep support phase3
 208   virtual HeapWord* initialize_threshold();
 209   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
 210 
 211   virtual void print() const;
 212 
 213   void reset_bot() {
 214     _bot_part.reset_bot();
 215   }
 216 
 217   void print_bot_on(outputStream* out) {
 218     _bot_part.print_on(out);
 219   }
 220 };
 221 
 222 class HeapRegion: public G1ContiguousSpace {
 223   friend class VMStructs;
 224   // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
 225   template <typename SpaceType>
 226   friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
 227  private:
 228 
 229   // The remembered set for this region.
 230   // (Might want to make this "inline" later, to avoid some alloc failure
 231   // issues.)
 232   HeapRegionRemSet* _rem_set;
 233 
 234   // Auxiliary functions for scan_and_forward support.
 235   // See comments for CompactibleSpace for more information.
 236   inline HeapWord* scan_limit() const {
 237     return top();
 238   }
 239 
 240   inline bool scanned_block_is_obj(const HeapWord* addr) const {
 241     return true; // Always true, since scan_limit is top
 242   }
 243 
 244   inline size_t scanned_block_size(const HeapWord* addr) const {
 245     return HeapRegion::block_size(addr); // Avoid virtual call
 246   }
 247 
 248   void report_region_type_change(G1HeapRegionTraceType::Type to);
 249 
 250  protected:
 251   // The index of this region in the heap region sequence.
 252   uint  _hrm_index;
 253 
 254   AllocationContext_t _allocation_context;
 255 
 256   HeapRegionType _type;
 257 
 258   // For a humongous region, region in which it starts.
 259   HeapRegion* _humongous_start_region;
 260 
 261   // True iff an attempt to evacuate an object in the region failed.
 262   bool _evacuation_failed;
 263 
 264   // A heap region may be a member one of a number of special subsets, each
 265   // represented as linked lists through the field below.  Currently, there
 266   // is only one set:
 267   //   The collection set.
 268   HeapRegion* _next_in_special_set;
 269 
 270   // Fields used by the HeapRegionSetBase class and subclasses.
 271   HeapRegion* _next;
 272   HeapRegion* _prev;
 273 #ifdef ASSERT
 274   HeapRegionSetBase* _containing_set;
 275 #endif // ASSERT
 276 
 277   // We use concurrent marking to determine the amount of live data
 278   // in each heap region.
 279   size_t _prev_marked_bytes;    // Bytes known to be live via last completed marking.
 280   size_t _next_marked_bytes;    // Bytes known to be live via in-progress marking.
 281 
 282   // The calculated GC efficiency of the region.
 283   double _gc_efficiency;
 284 
 285   int  _young_index_in_cset;
 286   SurvRateGroup* _surv_rate_group;
 287   int  _age_index;
 288 
 289   // The start of the unmarked area. The unmarked area extends from this
 290   // word until the top and/or end of the region, and is the part
 291   // of the region for which no marking was done, i.e. objects may
 292   // have been allocated in this part since the last mark phase.
 293   // "prev" is the top at the start of the last completed marking.
 294   // "next" is the top at the start of the in-progress marking (if any.)
 295   HeapWord* _prev_top_at_mark_start;
 296   HeapWord* _next_top_at_mark_start;
 297   // If a collection pause is in progress, this is the top at the start
 298   // of that pause.
 299 
 300   void init_top_at_mark_start() {
 301     assert(_prev_marked_bytes == 0 &&
 302            _next_marked_bytes == 0,
 303            "Must be called after zero_marked_bytes.");
 304     HeapWord* bot = bottom();
 305     _prev_top_at_mark_start = bot;
 306     _next_top_at_mark_start = bot;
 307   }
 308 
 309   // Cached attributes used in the collection set policy information
 310 
 311   // The RSet length that was added to the total value
 312   // for the collection set.
 313   size_t _recorded_rs_length;
 314 
 315   // The predicted elapsed time that was added to total value
 316   // for the collection set.
 317   double _predicted_elapsed_time_ms;
 318 
 319  public:
 320   HeapRegion(uint hrm_index,
 321              G1BlockOffsetTable* bot,
 322              MemRegion mr);
 323 
 324   // Initializing the HeapRegion not only resets the data structure, but also
 325   // resets the BOT for that heap region.
 326   // The default values for clear_space means that we will do the clearing if
 327   // there's clearing to be done ourselves. We also always mangle the space.
 328   virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
 329 
 330   static int    LogOfHRGrainBytes;
 331   static int    LogOfHRGrainWords;
 332 
 333   static size_t GrainBytes;
 334   static size_t GrainWords;
 335   static size_t CardsPerRegion;
 336 
 337   static size_t align_up_to_region_byte_size(size_t sz) {
 338     return (sz + (size_t) GrainBytes - 1) &
 339                                       ~((1 << (size_t) LogOfHRGrainBytes) - 1);
 340   }
 341 
 342 
 343   // Returns whether a field is in the same region as the obj it points to.
 344   template <typename T>
 345   static bool is_in_same_region(T* p, oop obj) {
 346     assert(p != NULL, "p can't be NULL");
 347     assert(obj != NULL, "obj can't be NULL");
 348     return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
 349   }
 350 
 351   static size_t max_region_size();
 352   static size_t min_region_size_in_words();
 353 
 354   // It sets up the heap region size (GrainBytes / GrainWords), as
 355   // well as other related fields that are based on the heap region
 356   // size (LogOfHRGrainBytes / LogOfHRGrainWords /
 357   // CardsPerRegion). All those fields are considered constant
 358   // throughout the JVM's execution, therefore they should only be set
 359   // up once during initialization time.
 360   static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
 361 
 362   // All allocated blocks are occupied by objects in a HeapRegion
 363   bool block_is_obj(const HeapWord* p) const;
 364 
 365   // Returns the object size for all valid block starts
 366   // and the amount of unallocated words if called on top()
 367   size_t block_size(const HeapWord* p) const;
 368 
 369   // Override for scan_and_forward support.
 370   void prepare_for_compaction(CompactPoint* cp);
 371 
 372   inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
 373   inline HeapWord* allocate_no_bot_updates(size_t word_size);
 374   inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
 375 
 376   // If this region is a member of a HeapRegionManager, the index in that
 377   // sequence, otherwise -1.
 378   uint hrm_index() const { return _hrm_index; }
 379 
 380   // The number of bytes marked live in the region in the last marking phase.
 381   size_t marked_bytes()    { return _prev_marked_bytes; }
 382   size_t live_bytes() {
 383     return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
 384   }
 385 
 386   // The number of bytes counted in the next marking.
 387   size_t next_marked_bytes() { return _next_marked_bytes; }
 388   // The number of bytes live wrt the next marking.
 389   size_t next_live_bytes() {
 390     return
 391       (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
 392   }
 393 
 394   // A lower bound on the amount of garbage bytes in the region.
 395   size_t garbage_bytes() {
 396     size_t used_at_mark_start_bytes =
 397       (prev_top_at_mark_start() - bottom()) * HeapWordSize;
 398     return used_at_mark_start_bytes - marked_bytes();
 399   }
 400 
 401   // Return the amount of bytes we'll reclaim if we collect this
 402   // region. This includes not only the known garbage bytes in the
 403   // region but also any unallocated space in it, i.e., [top, end),
 404   // since it will also be reclaimed if we collect the region.
 405   size_t reclaimable_bytes() {
 406     size_t known_live_bytes = live_bytes();
 407     assert(known_live_bytes <= capacity(), "sanity");
 408     return capacity() - known_live_bytes;
 409   }
 410 
 411   // An upper bound on the number of live bytes in the region.
 412   size_t max_live_bytes() { return used() - garbage_bytes(); }
 413 
 414   void add_to_marked_bytes(size_t incr_bytes) {
 415     _next_marked_bytes = _next_marked_bytes + incr_bytes;
 416   }
 417 
 418   void zero_marked_bytes()      {
 419     _prev_marked_bytes = _next_marked_bytes = 0;
 420   }
 421 
 422   const char* get_type_str() const { return _type.get_str(); }
 423   const char* get_short_type_str() const { return _type.get_short_str(); }
 424   G1HeapRegionTraceType::Type get_trace_type() { return _type.get_trace_type(); }
 425 
 426   bool is_free() const { return _type.is_free(); }
 427 
 428   bool is_young()    const { return _type.is_young();    }
 429   bool is_eden()     const { return _type.is_eden();     }
 430   bool is_survivor() const { return _type.is_survivor(); }
 431 
 432   bool is_humongous() const { return _type.is_humongous(); }
 433   bool is_starts_humongous() const { return _type.is_starts_humongous(); }
 434   bool is_continues_humongous() const { return _type.is_continues_humongous();   }
 435 
 436   bool is_old() const { return _type.is_old(); }
 437 
 438   // A pinned region contains objects which are not moved by garbage collections.
 439   // Humongous regions and archive regions are pinned.
 440   bool is_pinned() const { return _type.is_pinned(); }
 441 
 442   // An archive region is a pinned region, also tagged as old, which
 443   // should not be marked during mark/sweep. This allows the address
 444   // space to be shared by JVM instances.
 445   bool is_archive() const { return _type.is_archive(); }
 446 
 447   // For a humongous region, region in which it starts.
 448   HeapRegion* humongous_start_region() const {
 449     return _humongous_start_region;
 450   }
 451 
 452   // Makes the current region be a "starts humongous" region, i.e.,
 453   // the first region in a series of one or more contiguous regions
 454   // that will contain a single "humongous" object.
 455   //
 456   // obj_top : points to the top of the humongous object.
 457   // fill_size : size of the filler object at the end of the region series.
 458   void set_starts_humongous(HeapWord* obj_top, size_t fill_size);
 459 
 460   // Makes the current region be a "continues humongous'
 461   // region. first_hr is the "start humongous" region of the series
 462   // which this region will be part of.
 463   void set_continues_humongous(HeapRegion* first_hr);
 464 
 465   // Unsets the humongous-related fields on the region.
 466   void clear_humongous();
 467 
 468   // If the region has a remembered set, return a pointer to it.
 469   HeapRegionRemSet* rem_set() const {
 470     return _rem_set;
 471   }
 472 
 473   inline bool in_collection_set() const;
 474 
 475   inline HeapRegion* next_in_collection_set() const;
 476   inline void set_next_in_collection_set(HeapRegion* r);
 477 
 478   void set_allocation_context(AllocationContext_t context) {
 479     _allocation_context = context;
 480   }
 481 
 482   AllocationContext_t  allocation_context() const {
 483     return _allocation_context;
 484   }
 485 
 486   // Methods used by the HeapRegionSetBase class and subclasses.
 487 
 488   // Getter and setter for the next and prev fields used to link regions into
 489   // linked lists.
 490   HeapRegion* next()              { return _next; }
 491   HeapRegion* prev()              { return _prev; }
 492 
 493   void set_next(HeapRegion* next) { _next = next; }
 494   void set_prev(HeapRegion* prev) { _prev = prev; }
 495 
 496   // Every region added to a set is tagged with a reference to that
 497   // set. This is used for doing consistency checking to make sure that
 498   // the contents of a set are as they should be and it's only
 499   // available in non-product builds.
 500 #ifdef ASSERT
 501   void set_containing_set(HeapRegionSetBase* containing_set) {
 502     assert((containing_set == NULL && _containing_set != NULL) ||
 503            (containing_set != NULL && _containing_set == NULL),
 504            "containing_set: " PTR_FORMAT " "
 505            "_containing_set: " PTR_FORMAT,
 506            p2i(containing_set), p2i(_containing_set));
 507 
 508     _containing_set = containing_set;
 509   }
 510 
 511   HeapRegionSetBase* containing_set() { return _containing_set; }
 512 #else // ASSERT
 513   void set_containing_set(HeapRegionSetBase* containing_set) { }
 514 
 515   // containing_set() is only used in asserts so there's no reason
 516   // to provide a dummy version of it.
 517 #endif // ASSERT
 518 
 519 
 520   // Reset HR stuff to default values.
 521   void hr_clear(bool par, bool clear_space, bool locked = false);
 522   void par_clear();
 523 
 524   // Get the start of the unmarked area in this region.
 525   HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
 526   HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
 527 
 528   // Note the start or end of marking. This tells the heap region
 529   // that the collector is about to start or has finished (concurrently)
 530   // marking the heap.
 531 
 532   // Notify the region that concurrent marking is starting. Initialize
 533   // all fields related to the next marking info.
 534   inline void note_start_of_marking();
 535 
 536   // Notify the region that concurrent marking has finished. Copy the
 537   // (now finalized) next marking info fields into the prev marking
 538   // info fields.
 539   inline void note_end_of_marking();
 540 
 541   // Notify the region that it will be used as to-space during a GC
 542   // and we are about to start copying objects into it.
 543   inline void note_start_of_copying(bool during_initial_mark);
 544 
 545   // Notify the region that it ceases being to-space during a GC and
 546   // we will not copy objects into it any more.
 547   inline void note_end_of_copying(bool during_initial_mark);
 548 
 549   // Notify the region that we are about to start processing
 550   // self-forwarded objects during evac failure handling.
 551   void note_self_forwarding_removal_start(bool during_initial_mark,
 552                                           bool during_conc_mark);
 553 
 554   // Notify the region that we have finished processing self-forwarded
 555   // objects during evac failure handling.
 556   void note_self_forwarding_removal_end(size_t marked_bytes);
 557 
 558   // Returns "false" iff no object in the region was allocated when the
 559   // last mark phase ended.
 560   bool is_marked() { return _prev_top_at_mark_start != bottom(); }
 561 
 562   void reset_during_compaction() {
 563     assert(is_humongous(),
 564            "should only be called for humongous regions");
 565 
 566     zero_marked_bytes();
 567     init_top_at_mark_start();
 568   }
 569 
 570   void calc_gc_efficiency(void);
 571   double gc_efficiency() { return _gc_efficiency;}
 572 
 573   int  young_index_in_cset() const { return _young_index_in_cset; }
 574   void set_young_index_in_cset(int index) {
 575     assert( (index == -1) || is_young(), "pre-condition" );
 576     _young_index_in_cset = index;
 577   }
 578 
 579   int age_in_surv_rate_group() {
 580     assert( _surv_rate_group != NULL, "pre-condition" );
 581     assert( _age_index > -1, "pre-condition" );
 582     return _surv_rate_group->age_in_group(_age_index);
 583   }
 584 
 585   void record_surv_words_in_group(size_t words_survived) {
 586     assert( _surv_rate_group != NULL, "pre-condition" );
 587     assert( _age_index > -1, "pre-condition" );
 588     int age_in_group = age_in_surv_rate_group();
 589     _surv_rate_group->record_surviving_words(age_in_group, words_survived);
 590   }
 591 
 592   int age_in_surv_rate_group_cond() {
 593     if (_surv_rate_group != NULL)
 594       return age_in_surv_rate_group();
 595     else
 596       return -1;
 597   }
 598 
 599   SurvRateGroup* surv_rate_group() {
 600     return _surv_rate_group;
 601   }
 602 
 603   void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
 604     assert( surv_rate_group != NULL, "pre-condition" );
 605     assert( _surv_rate_group == NULL, "pre-condition" );
 606     assert( is_young(), "pre-condition" );
 607 
 608     _surv_rate_group = surv_rate_group;
 609     _age_index = surv_rate_group->next_age_index();
 610   }
 611 
 612   void uninstall_surv_rate_group() {
 613     if (_surv_rate_group != NULL) {
 614       assert( _age_index > -1, "pre-condition" );
 615       assert( is_young(), "pre-condition" );
 616 
 617       _surv_rate_group = NULL;
 618       _age_index = -1;
 619     } else {
 620       assert( _age_index == -1, "pre-condition" );
 621     }
 622   }
 623 
 624   void set_free();
 625 
 626   void set_eden();
 627   void set_eden_pre_gc();
 628   void set_survivor();
 629 
 630   void set_old();
 631 
 632   void set_archive();
 633 
 634   // Determine if an object has been allocated since the last
 635   // mark performed by the collector. This returns true iff the object
 636   // is within the unmarked area of the region.
 637   bool obj_allocated_since_prev_marking(oop obj) const {
 638     return (HeapWord *) obj >= prev_top_at_mark_start();
 639   }
 640   bool obj_allocated_since_next_marking(oop obj) const {
 641     return (HeapWord *) obj >= next_top_at_mark_start();
 642   }
 643 
 644   // Returns the "evacuation_failed" property of the region.
 645   bool evacuation_failed() { return _evacuation_failed; }
 646 
 647   // Sets the "evacuation_failed" property of the region.
 648   void set_evacuation_failed(bool b) {
 649     _evacuation_failed = b;
 650 
 651     if (b) {
 652       _next_marked_bytes = 0;
 653     }
 654   }
 655 
 656   // filter_young: if true and the region is a young region then we
 657   // skip the iteration.
 658   // card_ptr: if not NULL, and we decide that the card is not young
 659   // and we iterate over it, we'll clean the card before we start the
 660   // iteration.
 661   HeapWord*
 662   oops_on_card_seq_iterate_careful(MemRegion mr,
 663                                    FilterOutOfRegionClosure* cl,
 664                                    bool filter_young,
 665                                    jbyte* card_ptr);
 666 
 667   size_t recorded_rs_length() const        { return _recorded_rs_length; }
 668   double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
 669 
 670   void set_recorded_rs_length(size_t rs_length) {
 671     _recorded_rs_length = rs_length;
 672   }
 673 
 674   void set_predicted_elapsed_time_ms(double ms) {
 675     _predicted_elapsed_time_ms = ms;
 676   }
 677 
 678   virtual CompactibleSpace* next_compaction_space() const;
 679 
 680   virtual void reset_after_compaction();
 681 
 682   // Routines for managing a list of code roots (attached to the
 683   // this region's RSet) that point into this heap region.
 684   void add_strong_code_root(nmethod* nm);
 685   void add_strong_code_root_locked(nmethod* nm);
 686   void remove_strong_code_root(nmethod* nm);
 687 
 688   // Applies blk->do_code_blob() to each of the entries in
 689   // the strong code roots list for this region
 690   void strong_code_roots_do(CodeBlobClosure* blk) const;
 691 
 692   // Verify that the entries on the strong code root list for this
 693   // region are live and include at least one pointer into this region.
 694   void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
 695 
 696   void print() const;
 697   void print_on(outputStream* st) const;
 698 
 699   // vo == UsePrevMarking  -> use "prev" marking information,
 700   // vo == UseNextMarking -> use "next" marking information
 701   // vo == UseMarkWord    -> use the mark word in the object header
 702   //
 703   // NOTE: Only the "prev" marking information is guaranteed to be
 704   // consistent most of the time, so most calls to this should use
 705   // vo == UsePrevMarking.
 706   // Currently, there is only one case where this is called with
 707   // vo == UseNextMarking, which is to verify the "next" marking
 708   // information at the end of remark.
 709   // Currently there is only one place where this is called with
 710   // vo == UseMarkWord, which is to verify the marking during a
 711   // full GC.
 712   void verify(VerifyOption vo, bool *failures) const;
 713 
 714   // Override; it uses the "prev" marking information
 715   virtual void verify() const;
 716 
 717   void verify_rem_set(VerifyOption vo, bool *failures) const;
 718   void verify_rem_set() const;
 719 };
 720 
 721 // HeapRegionClosure is used for iterating over regions.
 722 // Terminates the iteration when the "doHeapRegion" method returns "true".
 723 class HeapRegionClosure : public StackObj {
 724   friend class HeapRegionManager;
 725   friend class G1CollectedHeap;
 726 
 727   bool _complete;
 728   void incomplete() { _complete = false; }
 729 
 730  public:
 731   HeapRegionClosure(): _complete(true) {}
 732 
 733   // Typically called on each region until it returns true.
 734   virtual bool doHeapRegion(HeapRegion* r) = 0;
 735 
 736   // True after iteration if the closure was applied to all heap regions
 737   // and returned "false" in all cases.
 738   bool complete() { return _complete; }
 739 };
 740 
 741 #endif // SHARE_VM_GC_G1_HEAPREGION_HPP