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 "gc/shared/watermark.hpp"
  35 #include "utilities/macros.hpp"
  36 
  37 // A HeapRegion is the smallest piece of a G1CollectedHeap that
  38 // can be collected independently.
  39 
  40 // NOTE: Although a HeapRegion is a Space, its
  41 // Space::initDirtyCardClosure method must not be called.
  42 // The problem is that the existence of this method breaks
  43 // the independence of barrier sets from remembered sets.
  44 // The solution is to remove this method from the definition
  45 // of a Space.
  46 
  47 class G1CollectedHeap;
  48 class HeapRegionRemSet;
  49 class HeapRegionRemSetIterator;
  50 class HeapRegion;
  51 class HeapRegionSetBase;
  52 class nmethod;
  53 
  54 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
  55 #define HR_FORMAT_PARAMS(_hr_) \
  56                 (_hr_)->hrm_index(), \
  57                 (_hr_)->get_short_type_str(), \
  58                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
  59 
  60 // sentinel value for hrm_index
  61 #define G1_NO_HRM_INDEX ((uint) -1)
  62 
  63 // A dirty card to oop closure for heap regions. It
  64 // knows how to get the G1 heap and how to use the bitmap
  65 // in the concurrent marker used by G1 to filter remembered
  66 // sets.
  67 
  68 class HeapRegionDCTOC : public DirtyCardToOopClosure {
  69 private:
  70   HeapRegion* _hr;
  71   G1ParPushHeapRSClosure* _rs_scan;
  72   G1CollectedHeap* _g1;
  73 
  74   // Walk the given memory region from bottom to (actual) top
  75   // looking for objects and applying the oop closure (_cl) to
  76   // them. The base implementation of this treats the area as
  77   // blocks, where a block may or may not be an object. Sub-
  78   // classes should override this to provide more accurate
  79   // or possibly more efficient walking.
  80   void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
  81 
  82 public:
  83   HeapRegionDCTOC(G1CollectedHeap* g1,
  84                   HeapRegion* hr,
  85                   G1ParPushHeapRSClosure* cl,
  86                   CardTableModRefBS::PrecisionStyle precision);
  87 };
  88 
  89 // The complicating factor is that BlockOffsetTable diverged
  90 // significantly, and we need functionality that is only in the G1 version.
  91 // So I copied that code, which led to an alternate G1 version of
  92 // OffsetTableContigSpace.  If the two versions of BlockOffsetTable could
  93 // be reconciled, then G1OffsetTableContigSpace could go away.
  94 
  95 // The idea behind time stamps is the following. We want to keep track of
  96 // the highest address where it's safe to scan objects for each region.
  97 // This is only relevant for current GC alloc regions so we keep a time stamp
  98 // per region to determine if the region has been allocated during the current
  99 // GC or not. If the time stamp is current we report a scan_top value which
 100 // was saved at the end of the previous GC for retained alloc regions and which is
 101 // equal to the bottom for all other regions.
 102 // There is a race between card scanners and allocating gc workers where we must ensure
 103 // that card scanners do not read the memory allocated by the gc workers.
 104 // In order to enforce that, we must not return a value of _top which is more recent than the
 105 // time stamp. This is due to the fact that a region may become a gc alloc region at
 106 // some point after we've read the timestamp value as being < the current time stamp.
 107 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
 108 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
 109 // evacuation pauses between two cleanups, which is _highly_ unlikely.
 110 class G1OffsetTableContigSpace: public CompactibleSpace {
 111   friend class VMStructs;
 112   HeapWord* _top;
 113   HeapWord* volatile _scan_top;
 114  protected:
 115   G1BlockOffsetArrayContigSpace _offsets;
 116   Mutex _par_alloc_lock;
 117   volatile unsigned _gc_time_stamp;
 118   // When we need to retire an allocation region, while other threads
 119   // are also concurrently trying to allocate into it, we typically
 120   // allocate a dummy object at the end of the region to ensure that
 121   // no more allocations can take place in it. However, sometimes we
 122   // want to know where the end of the last "real" object we allocated
 123   // into the region was and this is what this keeps track.
 124   HeapWord* _pre_dummy_top;
 125 
 126  public:
 127   G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
 128                            MemRegion mr);
 129 
 130   void set_top(HeapWord* value) { _top = value; }
 131   HeapWord* top() const { return _top; }
 132 
 133  protected:
 134   // Reset the G1OffsetTableContigSpace.
 135   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
 136 
 137   HeapWord** top_addr() { return &_top; }
 138   // Allocation helpers (return NULL if full).
 139   inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
 140   inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);
 141 
 142  public:
 143   void reset_after_compaction() { set_top(compaction_top()); }
 144 
 145   size_t used() const { return byte_size(bottom(), top()); }
 146   size_t free() const { return byte_size(top(), end()); }
 147   bool is_free_block(const HeapWord* p) const { return p >= top(); }
 148 
 149   MemRegion used_region() const { return MemRegion(bottom(), top()); }
 150 
 151   void object_iterate(ObjectClosure* blk);
 152   void safe_object_iterate(ObjectClosure* blk);
 153 
 154   void set_bottom(HeapWord* value);
 155   void set_end(HeapWord* value);
 156 
 157   void mangle_unused_area() PRODUCT_RETURN;
 158   void mangle_unused_area_complete() PRODUCT_RETURN;
 159 
 160   HeapWord* scan_top() const;
 161   void record_timestamp();
 162   void reset_gc_time_stamp() { _gc_time_stamp = 0; }
 163   unsigned get_gc_time_stamp() { return _gc_time_stamp; }
 164   void record_retained_region();
 165 
 166   // See the comment above in the declaration of _pre_dummy_top for an
 167   // explanation of what it is.
 168   void set_pre_dummy_top(HeapWord* pre_dummy_top) {
 169     assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
 170     _pre_dummy_top = pre_dummy_top;
 171   }
 172   HeapWord* pre_dummy_top() {
 173     return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
 174   }
 175   void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
 176 
 177   virtual void clear(bool mangle_space);
 178 
 179   HeapWord* block_start(const void* p);
 180   HeapWord* block_start_const(const void* p) const;
 181 
 182   // Add offset table update.
 183   virtual HeapWord* allocate(size_t word_size);
 184   HeapWord* par_allocate(size_t word_size);
 185 
 186   HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
 187 
 188   // MarkSweep support phase3
 189   virtual HeapWord* initialize_threshold();
 190   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
 191 
 192   virtual void print() const;
 193 
 194   void reset_bot() {
 195     _offsets.reset_bot();
 196   }
 197 
 198   void print_bot_on(outputStream* out) {
 199     _offsets.print_on(out);
 200   }
 201 };
 202 
 203 class HeapRegion: public G1OffsetTableContigSpace {
 204   friend class VMStructs;
 205   // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
 206   template <typename SpaceType>
 207   friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
 208  private:
 209 
 210   // The remembered set for this region.
 211   // (Might want to make this "inline" later, to avoid some alloc failure
 212   // issues.)
 213   HeapRegionRemSet* _rem_set;
 214 
 215   G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
 216 
 217   // Auxiliary functions for scan_and_forward support.
 218   // See comments for CompactibleSpace for more information.
 219   inline HeapWord* scan_limit() const {
 220     return top();
 221   }
 222 
 223   inline bool scanned_block_is_obj(const HeapWord* addr) const {
 224     return true; // Always true, since scan_limit is top
 225   }
 226 
 227   inline size_t scanned_block_size(const HeapWord* addr) const {
 228     return HeapRegion::block_size(addr); // Avoid virtual call
 229   }
 230 
 231  protected:
 232   // The index of this region in the heap region sequence.
 233   uint  _hrm_index;
 234 
 235   AllocationContext_t _allocation_context;
 236 
 237   HeapRegionType _type;
 238 
 239   // For a humongous region, region in which it starts.
 240   HeapRegion* _humongous_start_region;
 241 
 242   // True iff an attempt to evacuate an object in the region failed.
 243   bool _evacuation_failed;
 244 
 245   // A heap region may be a member one of a number of special subsets, each
 246   // represented as linked lists through the field below.  Currently, there
 247   // is only one set:
 248   //   The collection set.
 249   HeapRegion* _next_in_special_set;
 250 
 251   // next region in the young "generation" region set
 252   HeapRegion* _next_young_region;
 253 
 254   // Next region whose cards need cleaning
 255   HeapRegion* _next_dirty_cards_region;
 256 
 257   // Fields used by the HeapRegionSetBase class and subclasses.
 258   HeapRegion* _next;
 259   HeapRegion* _prev;
 260 #ifdef ASSERT
 261   HeapRegionSetBase* _containing_set;
 262 #endif // ASSERT
 263 
 264   // We use concurrent marking to determine the amount of live data
 265   // in each heap region.
 266   size_t _prev_marked_bytes;    // Bytes known to be live via last completed marking.
 267   size_t _next_marked_bytes;    // Bytes known to be live via in-progress marking.
 268 
 269   // The calculated GC efficiency of the region.
 270   double _gc_efficiency;
 271 
 272   int  _young_index_in_cset;
 273   SurvRateGroup* _surv_rate_group;
 274   int  _age_index;
 275 
 276   // The start of the unmarked area. The unmarked area extends from this
 277   // word until the top and/or end of the region, and is the part
 278   // of the region for which no marking was done, i.e. objects may
 279   // have been allocated in this part since the last mark phase.
 280   // "prev" is the top at the start of the last completed marking.
 281   // "next" is the top at the start of the in-progress marking (if any.)
 282   HeapWord* _prev_top_at_mark_start;
 283   HeapWord* _next_top_at_mark_start;
 284   // If a collection pause is in progress, this is the top at the start
 285   // of that pause.
 286 
 287   void init_top_at_mark_start() {
 288     assert(_prev_marked_bytes == 0 &&
 289            _next_marked_bytes == 0,
 290            "Must be called after zero_marked_bytes.");
 291     HeapWord* bot = bottom();
 292     _prev_top_at_mark_start = bot;
 293     _next_top_at_mark_start = bot;
 294   }
 295 
 296   // Cached attributes used in the collection set policy information
 297 
 298   // The RSet length that was added to the total value
 299   // for the collection set.
 300   size_t _recorded_rs_length;
 301 
 302   // The predicted elapsed time that was added to total value
 303   // for the collection set.
 304   double _predicted_elapsed_time_ms;
 305 
 306   // The predicted number of bytes to copy that was added to
 307   // the total value for the collection set.
 308   size_t _predicted_bytes_to_copy;
 309 
 310  public:
 311   HeapRegion(uint hrm_index,
 312              G1BlockOffsetSharedArray* sharedOffsetArray,
 313              MemRegion mr);
 314 
 315   // Initializing the HeapRegion not only resets the data structure, but also
 316   // resets the BOT for that heap region.
 317   // The default values for clear_space means that we will do the clearing if
 318   // there's clearing to be done ourselves. We also always mangle the space.
 319   virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
 320 
 321   static int    LogOfHRGrainBytes;
 322   static int    LogOfHRGrainWords;
 323 
 324   static size_t GrainBytes;
 325   static size_t GrainWords;
 326   static size_t CardsPerRegion;
 327 
 328   static size_t align_up_to_region_byte_size(size_t sz) {
 329     return (sz + (size_t) GrainBytes - 1) &
 330                                       ~((1 << (size_t) LogOfHRGrainBytes) - 1);
 331   }
 332 
 333   static size_t max_region_size();
 334   static size_t min_region_size_in_words();
 335 
 336   // It sets up the heap region size (GrainBytes / GrainWords), as
 337   // well as other related fields that are based on the heap region
 338   // size (LogOfHRGrainBytes / LogOfHRGrainWords /
 339   // CardsPerRegion). All those fields are considered constant
 340   // throughout the JVM's execution, therefore they should only be set
 341   // up once during initialization time.
 342   static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
 343 
 344   // All allocated blocks are occupied by objects in a HeapRegion
 345   bool block_is_obj(const HeapWord* p) const;
 346 
 347   // Returns the object size for all valid block starts
 348   // and the amount of unallocated words if called on top()
 349   size_t block_size(const HeapWord* p) const;
 350 
 351   // Override for scan_and_forward support.
 352   void prepare_for_compaction(CompactPoint* cp);
 353 
 354   inline HeapWord* par_allocate_no_bot_updates(size_t word_size);
 355   inline HeapWord* allocate_no_bot_updates(size_t word_size);
 356 
 357   // If this region is a member of a HeapRegionManager, the index in that
 358   // sequence, otherwise -1.
 359   uint hrm_index() const { return _hrm_index; }
 360 
 361   // The number of bytes marked live in the region in the last marking phase.
 362   size_t marked_bytes()    { return _prev_marked_bytes; }
 363   size_t live_bytes() {
 364     return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
 365   }
 366 
 367   // The number of bytes counted in the next marking.
 368   size_t next_marked_bytes() { return _next_marked_bytes; }
 369   // The number of bytes live wrt the next marking.
 370   size_t next_live_bytes() {
 371     return
 372       (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
 373   }
 374 
 375   // A lower bound on the amount of garbage bytes in the region.
 376   size_t garbage_bytes() {
 377     size_t used_at_mark_start_bytes =
 378       (prev_top_at_mark_start() - bottom()) * HeapWordSize;
 379     assert(used_at_mark_start_bytes >= marked_bytes(),
 380            "Can't mark more than we have.");
 381     return used_at_mark_start_bytes - marked_bytes();
 382   }
 383 
 384   // Return the amount of bytes we'll reclaim if we collect this
 385   // region. This includes not only the known garbage bytes in the
 386   // region but also any unallocated space in it, i.e., [top, end),
 387   // since it will also be reclaimed if we collect the region.
 388   size_t reclaimable_bytes() {
 389     size_t known_live_bytes = live_bytes();
 390     assert(known_live_bytes <= capacity(), "sanity");
 391     return capacity() - known_live_bytes;
 392   }
 393 
 394   // An upper bound on the number of live bytes in the region.
 395   size_t max_live_bytes() { return used() - garbage_bytes(); }
 396 
 397   void add_to_marked_bytes(size_t incr_bytes) {
 398     _next_marked_bytes = _next_marked_bytes + incr_bytes;
 399     assert(_next_marked_bytes <= used(), "invariant" );
 400   }
 401 
 402   void zero_marked_bytes()      {
 403     _prev_marked_bytes = _next_marked_bytes = 0;
 404   }
 405 
 406   const char* get_type_str() const { return _type.get_str(); }
 407   const char* get_short_type_str() const { return _type.get_short_str(); }
 408 
 409   bool is_free() const { return _type.is_free(); }
 410 
 411   bool is_young()    const { return _type.is_young();    }
 412   bool is_eden()     const { return _type.is_eden();     }
 413   bool is_survivor() const { return _type.is_survivor(); }
 414 
 415   bool is_humongous() const { return _type.is_humongous(); }
 416   bool is_starts_humongous() const { return _type.is_starts_humongous(); }
 417   bool is_continues_humongous() const { return _type.is_continues_humongous();   }
 418 
 419   bool is_old() const { return _type.is_old(); }
 420 
 421   // A pinned region contains objects which are not moved by garbage collections.
 422   // Humongous regions and archive regions are pinned.
 423   bool is_pinned() const { return _type.is_pinned(); }
 424 
 425   // An archive region is a pinned region, also tagged as old, which
 426   // should not be marked during mark/sweep. This allows the address
 427   // space to be shared by JVM instances.
 428   bool is_archive() const { return _type.is_archive(); }
 429 
 430   // For a humongous region, region in which it starts.
 431   HeapRegion* humongous_start_region() const {
 432     return _humongous_start_region;
 433   }
 434 
 435   // Return the number of distinct regions that are covered by this region:
 436   // 1 if the region is not humongous, >= 1 if the region is humongous.
 437   uint region_num() const {
 438     if (!is_humongous()) {
 439       return 1U;
 440     } else {
 441       assert(is_starts_humongous(), "doesn't make sense on HC regions");
 442       assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
 443       return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
 444     }
 445   }
 446 
 447   // Return the index + 1 of the last HC regions that's associated
 448   // with this HS region.
 449   uint last_hc_index() const {
 450     assert(is_starts_humongous(), "don't call this otherwise");
 451     return hrm_index() + region_num();
 452   }
 453 
 454   // Same as Space::is_in_reserved, but will use the original size of the region.
 455   // The original size is different only for start humongous regions. They get
 456   // their _end set up to be the end of the last continues region of the
 457   // corresponding humongous object.
 458   bool is_in_reserved_raw(const void* p) const {
 459     return _bottom <= p && p < orig_end();
 460   }
 461 
 462   // Makes the current region be a "starts humongous" region, i.e.,
 463   // the first region in a series of one or more contiguous regions
 464   // that will contain a single "humongous" object. The two parameters
 465   // are as follows:
 466   //
 467   // new_top : The new value of the top field of this region which
 468   // points to the end of the humongous object that's being
 469   // allocated. If there is more than one region in the series, top
 470   // will lie beyond this region's original end field and on the last
 471   // region in the series.
 472   //
 473   // new_end : The new value of the end field of this region which
 474   // points to the end of the last region in the series. If there is
 475   // one region in the series (namely: this one) end will be the same
 476   // as the original end of this region.
 477   //
 478   // Updating top and end as described above makes this region look as
 479   // if it spans the entire space taken up by all the regions in the
 480   // series and an single allocation moved its top to new_top. This
 481   // ensures that the space (capacity / allocated) taken up by all
 482   // humongous regions can be calculated by just looking at the
 483   // "starts humongous" regions and by ignoring the "continues
 484   // humongous" regions.
 485   void set_starts_humongous(HeapWord* new_top, HeapWord* new_end);
 486 
 487   // Makes the current region be a "continues humongous'
 488   // region. first_hr is the "start humongous" region of the series
 489   // which this region will be part of.
 490   void set_continues_humongous(HeapRegion* first_hr);
 491 
 492   // Unsets the humongous-related fields on the region.
 493   void clear_humongous();
 494 
 495   // If the region has a remembered set, return a pointer to it.
 496   HeapRegionRemSet* rem_set() const {
 497     return _rem_set;
 498   }
 499 
 500   bool in_collection_set() const;
 501 
 502   HeapRegion* next_in_collection_set() {
 503     assert(in_collection_set(), "should only invoke on member of CS.");
 504     assert(_next_in_special_set == NULL ||
 505            _next_in_special_set->in_collection_set(),
 506            "Malformed CS.");
 507     return _next_in_special_set;
 508   }
 509   void set_next_in_collection_set(HeapRegion* r) {
 510     assert(in_collection_set(), "should only invoke on member of CS.");
 511     assert(r == NULL || r->in_collection_set(), "Malformed CS.");
 512     _next_in_special_set = r;
 513   }
 514 
 515   void set_allocation_context(AllocationContext_t context) {
 516     _allocation_context = context;
 517   }
 518 
 519   AllocationContext_t  allocation_context() const {
 520     return _allocation_context;
 521   }
 522 
 523   // Methods used by the HeapRegionSetBase class and subclasses.
 524 
 525   // Getter and setter for the next and prev fields used to link regions into
 526   // linked lists.
 527   HeapRegion* next()              { return _next; }
 528   HeapRegion* prev()              { return _prev; }
 529 
 530   void set_next(HeapRegion* next) { _next = next; }
 531   void set_prev(HeapRegion* prev) { _prev = prev; }
 532 
 533   // Every region added to a set is tagged with a reference to that
 534   // set. This is used for doing consistency checking to make sure that
 535   // the contents of a set are as they should be and it's only
 536   // available in non-product builds.
 537 #ifdef ASSERT
 538   void set_containing_set(HeapRegionSetBase* containing_set) {
 539     assert((containing_set == NULL && _containing_set != NULL) ||
 540            (containing_set != NULL && _containing_set == NULL),
 541            err_msg("containing_set: " PTR_FORMAT " "
 542                    "_containing_set: " PTR_FORMAT,
 543                    p2i(containing_set), p2i(_containing_set)));
 544 
 545     _containing_set = containing_set;
 546   }
 547 
 548   HeapRegionSetBase* containing_set() { return _containing_set; }
 549 #else // ASSERT
 550   void set_containing_set(HeapRegionSetBase* containing_set) { }
 551 
 552   // containing_set() is only used in asserts so there's no reason
 553   // to provide a dummy version of it.
 554 #endif // ASSERT
 555 
 556   HeapRegion* get_next_young_region() { return _next_young_region; }
 557   void set_next_young_region(HeapRegion* hr) {
 558     _next_young_region = hr;
 559   }
 560 
 561   HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
 562   HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
 563   void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
 564   bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
 565 
 566   // For the start region of a humongous sequence, it's original end().
 567   HeapWord* orig_end() const { return _bottom + GrainWords; }
 568 
 569   // Reset HR stuff to default values.
 570   void hr_clear(bool par, bool clear_space, bool locked = false);
 571   void par_clear();
 572 
 573   // Get the start of the unmarked area in this region.
 574   HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
 575   HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
 576 
 577   // Note the start or end of marking. This tells the heap region
 578   // that the collector is about to start or has finished (concurrently)
 579   // marking the heap.
 580 
 581   // Notify the region that concurrent marking is starting. Initialize
 582   // all fields related to the next marking info.
 583   inline void note_start_of_marking();
 584 
 585   // Notify the region that concurrent marking has finished. Copy the
 586   // (now finalized) next marking info fields into the prev marking
 587   // info fields.
 588   inline void note_end_of_marking();
 589 
 590   // Notify the region that it will be used as to-space during a GC
 591   // and we are about to start copying objects into it.
 592   inline void note_start_of_copying(bool during_initial_mark);
 593 
 594   // Notify the region that it ceases being to-space during a GC and
 595   // we will not copy objects into it any more.
 596   inline void note_end_of_copying(bool during_initial_mark);
 597 
 598   // Notify the region that we are about to start processing
 599   // self-forwarded objects during evac failure handling.
 600   void note_self_forwarding_removal_start(bool during_initial_mark,
 601                                           bool during_conc_mark);
 602 
 603   // Notify the region that we have finished processing self-forwarded
 604   // objects during evac failure handling.
 605   void note_self_forwarding_removal_end(bool during_initial_mark,
 606                                         bool during_conc_mark,
 607                                         size_t marked_bytes);
 608 
 609   // Returns "false" iff no object in the region was allocated when the
 610   // last mark phase ended.
 611   bool is_marked() { return _prev_top_at_mark_start != bottom(); }
 612 
 613   void reset_during_compaction() {
 614     assert(is_starts_humongous(),
 615            "should only be called for starts humongous regions");
 616 
 617     zero_marked_bytes();
 618     init_top_at_mark_start();
 619   }
 620 
 621   void calc_gc_efficiency(void);
 622   double gc_efficiency() { return _gc_efficiency;}
 623 
 624   int  young_index_in_cset() const { return _young_index_in_cset; }
 625   void set_young_index_in_cset(int index) {
 626     assert( (index == -1) || is_young(), "pre-condition" );
 627     _young_index_in_cset = index;
 628   }
 629 
 630   int age_in_surv_rate_group() {
 631     assert( _surv_rate_group != NULL, "pre-condition" );
 632     assert( _age_index > -1, "pre-condition" );
 633     return _surv_rate_group->age_in_group(_age_index);
 634   }
 635 
 636   void record_surv_words_in_group(size_t words_survived) {
 637     assert( _surv_rate_group != NULL, "pre-condition" );
 638     assert( _age_index > -1, "pre-condition" );
 639     int age_in_group = age_in_surv_rate_group();
 640     _surv_rate_group->record_surviving_words(age_in_group, words_survived);
 641   }
 642 
 643   int age_in_surv_rate_group_cond() {
 644     if (_surv_rate_group != NULL)
 645       return age_in_surv_rate_group();
 646     else
 647       return -1;
 648   }
 649 
 650   SurvRateGroup* surv_rate_group() {
 651     return _surv_rate_group;
 652   }
 653 
 654   void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
 655     assert( surv_rate_group != NULL, "pre-condition" );
 656     assert( _surv_rate_group == NULL, "pre-condition" );
 657     assert( is_young(), "pre-condition" );
 658 
 659     _surv_rate_group = surv_rate_group;
 660     _age_index = surv_rate_group->next_age_index();
 661   }
 662 
 663   void uninstall_surv_rate_group() {
 664     if (_surv_rate_group != NULL) {
 665       assert( _age_index > -1, "pre-condition" );
 666       assert( is_young(), "pre-condition" );
 667 
 668       _surv_rate_group = NULL;
 669       _age_index = -1;
 670     } else {
 671       assert( _age_index == -1, "pre-condition" );
 672     }
 673   }
 674 
 675   void set_free() { _type.set_free(); }
 676 
 677   void set_eden()        { _type.set_eden();        }
 678   void set_eden_pre_gc() { _type.set_eden_pre_gc(); }
 679   void set_survivor()    { _type.set_survivor();    }
 680 
 681   void set_old() { _type.set_old(); }
 682 
 683   void set_archive() { _type.set_archive(); }
 684 
 685   // Determine if an object has been allocated since the last
 686   // mark performed by the collector. This returns true iff the object
 687   // is within the unmarked area of the region.
 688   bool obj_allocated_since_prev_marking(oop obj) const {
 689     return (HeapWord *) obj >= prev_top_at_mark_start();
 690   }
 691   bool obj_allocated_since_next_marking(oop obj) const {
 692     return (HeapWord *) obj >= next_top_at_mark_start();
 693   }
 694 
 695   // Returns the "evacuation_failed" property of the region.
 696   bool evacuation_failed() { return _evacuation_failed; }
 697 
 698   // Sets the "evacuation_failed" property of the region.
 699   void set_evacuation_failed(bool b) {
 700     _evacuation_failed = b;
 701 
 702     if (b) {
 703       _next_marked_bytes = 0;
 704     }
 705   }
 706 
 707   // Requires that "mr" be entirely within the region.
 708   // Apply "cl->do_object" to all objects that intersect with "mr".
 709   // If the iteration encounters an unparseable portion of the region,
 710   // or if "cl->abort()" is true after a closure application,
 711   // terminate the iteration and return the address of the start of the
 712   // subregion that isn't done.  (The two can be distinguished by querying
 713   // "cl->abort()".)  Return of "NULL" indicates that the iteration
 714   // completed.
 715   HeapWord*
 716   object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
 717 
 718   // filter_young: if true and the region is a young region then we
 719   // skip the iteration.
 720   // card_ptr: if not NULL, and we decide that the card is not young
 721   // and we iterate over it, we'll clean the card before we start the
 722   // iteration.
 723   HeapWord*
 724   oops_on_card_seq_iterate_careful(MemRegion mr,
 725                                    FilterOutOfRegionClosure* cl,
 726                                    bool filter_young,
 727                                    jbyte* card_ptr);
 728 
 729   size_t recorded_rs_length() const        { return _recorded_rs_length; }
 730   double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
 731   size_t predicted_bytes_to_copy() const   { return _predicted_bytes_to_copy; }
 732 
 733   void set_recorded_rs_length(size_t rs_length) {
 734     _recorded_rs_length = rs_length;
 735   }
 736 
 737   void set_predicted_elapsed_time_ms(double ms) {
 738     _predicted_elapsed_time_ms = ms;
 739   }
 740 
 741   void set_predicted_bytes_to_copy(size_t bytes) {
 742     _predicted_bytes_to_copy = bytes;
 743   }
 744 
 745   virtual CompactibleSpace* next_compaction_space() const;
 746 
 747   virtual void reset_after_compaction();
 748 
 749   // Routines for managing a list of code roots (attached to the
 750   // this region's RSet) that point into this heap region.
 751   void add_strong_code_root(nmethod* nm);
 752   void add_strong_code_root_locked(nmethod* nm);
 753   void remove_strong_code_root(nmethod* nm);
 754 
 755   // Applies blk->do_code_blob() to each of the entries in
 756   // the strong code roots list for this region
 757   void strong_code_roots_do(CodeBlobClosure* blk) const;
 758 
 759   // Verify that the entries on the strong code root list for this
 760   // region are live and include at least one pointer into this region.
 761   void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
 762 
 763   void print() const;
 764   void print_on(outputStream* st) const;
 765 
 766   // vo == UsePrevMarking  -> use "prev" marking information,
 767   // vo == UseNextMarking -> use "next" marking information
 768   // vo == UseMarkWord    -> use the mark word in the object header
 769   //
 770   // NOTE: Only the "prev" marking information is guaranteed to be
 771   // consistent most of the time, so most calls to this should use
 772   // vo == UsePrevMarking.
 773   // Currently, there is only one case where this is called with
 774   // vo == UseNextMarking, which is to verify the "next" marking
 775   // information at the end of remark.
 776   // Currently there is only one place where this is called with
 777   // vo == UseMarkWord, which is to verify the marking during a
 778   // full GC.
 779   void verify(VerifyOption vo, bool *failures) const;
 780 
 781   // Override; it uses the "prev" marking information
 782   virtual void verify() const;
 783 };
 784 
 785 // HeapRegionClosure is used for iterating over regions.
 786 // Terminates the iteration when the "doHeapRegion" method returns "true".
 787 class HeapRegionClosure : public StackObj {
 788   friend class HeapRegionManager;
 789   friend class G1CollectedHeap;
 790 
 791   bool _complete;
 792   void incomplete() { _complete = false; }
 793 
 794  public:
 795   HeapRegionClosure(): _complete(true) {}
 796 
 797   // Typically called on each region until it returns true.
 798   virtual bool doHeapRegion(HeapRegion* r) = 0;
 799 
 800   // True after iteration if the closure was applied to all heap regions
 801   // and returned "false" in all cases.
 802   bool complete() { return _complete; }
 803 };
 804 
 805 #endif // SHARE_VM_GC_G1_HEAPREGION_HPP