1 /*
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  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/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. 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 G1CMBitMapRO;
  60 class HeapRegionRemSet;
  61 class HeapRegionRemSetIterator;
  62 class HeapRegion;
  63 class HeapRegionSetBase;
  64 class nmethod;
  65 
  66 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
  67 #define HR_FORMAT_PARAMS(_hr_) \
  68                 (_hr_)->hrm_index(), \
  69                 (_hr_)->get_short_type_str(), \
  70                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
  71 
  72 // sentinel value for hrm_index
  73 #define G1_NO_HRM_INDEX ((uint) -1)
  74 
  75 // A dirty card to oop closure for heap regions. It
  76 // knows how to get the G1 heap and how to use the bitmap
  77 // in the concurrent marker used by G1 to filter remembered
  78 // sets.
  79 
  80 class HeapRegionDCTOC : public DirtyCardToOopClosure {
  81 private:
  82   HeapRegion* _hr;
  83   G1ParPushHeapRSClosure* _rs_scan;
  84   G1CollectedHeap* _g1;
  85 
  86   // Walk the given memory region from bottom to (actual) top
  87   // looking for objects and applying the oop closure (_cl) to
  88   // them. The base implementation of this treats the area as
  89   // blocks, where a block may or may not be an object. Sub-
  90   // classes should override this to provide more accurate
  91   // or possibly more efficient walking.
  92   void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
  93 
  94 public:
  95   HeapRegionDCTOC(G1CollectedHeap* g1,
  96                   HeapRegion* hr,
  97                   G1ParPushHeapRSClosure* cl,
  98                   CardTableModRefBS::PrecisionStyle precision);
  99 };
 100 
 101 // The complicating factor is that BlockOffsetTable diverged
 102 // significantly, and we need functionality that is only in the G1 version.
 103 // So I copied that code, which led to an alternate G1 version of
 104 // OffsetTableContigSpace.  If the two versions of BlockOffsetTable could
 105 // be reconciled, then G1OffsetTableContigSpace could go away.
 106 
 107 // The idea behind time stamps is the following. We want to keep track of
 108 // the highest address where it's safe to scan objects for each region.
 109 // This is only relevant for current GC alloc regions so we keep a time stamp
 110 // per region to determine if the region has been allocated during the current
 111 // GC or not. If the time stamp is current we report a scan_top value which
 112 // was saved at the end of the previous GC for retained alloc regions and which is
 113 // equal to the bottom for all other regions.
 114 // There is a race between card scanners and allocating gc workers where we must ensure
 115 // that card scanners do not read the memory allocated by the gc workers.
 116 // In order to enforce that, we must not return a value of _top which is more recent than the
 117 // time stamp. This is due to the fact that a region may become a gc alloc region at
 118 // some point after we've read the timestamp value as being < the current time stamp.
 119 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
 120 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
 121 // evacuation pauses between two cleanups, which is _highly_ unlikely.
 122 class G1ContiguousSpace: public CompactibleSpace {
 123   friend class VMStructs;
 124   HeapWord* volatile _top;
 125   HeapWord* volatile _scan_top;
 126  protected:
 127   G1BlockOffsetTablePart _bot_part;
 128   Mutex _par_alloc_lock;
 129   volatile uint _gc_time_stamp;
 130   // When we need to retire an allocation region, while other threads
 131   // are also concurrently trying to allocate into it, we typically
 132   // allocate a dummy object at the end of the region to ensure that
 133   // no more allocations can take place in it. However, sometimes we
 134   // want to know where the end of the last "real" object we allocated
 135   // into the region was and this is what this keeps track.
 136   HeapWord* _pre_dummy_top;
 137 
 138  public:
 139   G1ContiguousSpace(G1BlockOffsetTable* bot);
 140 
 141   void set_top(HeapWord* value) { _top = value; }
 142   HeapWord* top() const { return _top; }
 143 
 144  protected:
 145   // Reset the G1ContiguousSpace.
 146   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
 147 
 148   HeapWord* volatile* top_addr() { return &_top; }
 149   // Try to allocate at least min_word_size and up to desired_size from this Space.
 150   // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
 151   // space allocated.
 152   // This version assumes that all allocation requests to this Space are properly
 153   // synchronized.
 154   inline HeapWord* allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 155   // Try to allocate at least min_word_size and up to desired_size from this Space.
 156   // Returns NULL if not possible, otherwise sets actual_word_size to the amount of
 157   // space allocated.
 158   // This version synchronizes with other calls to par_allocate_impl().
 159   inline HeapWord* par_allocate_impl(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 160 
 161  public:
 162   void reset_after_compaction() { set_top(compaction_top()); }
 163 
 164   size_t used() const { return byte_size(bottom(), top()); }
 165   size_t free() const { return byte_size(top(), end()); }
 166   bool is_free_block(const HeapWord* p) const { return p >= top(); }
 167 
 168   MemRegion used_region() const { return MemRegion(bottom(), top()); }
 169 
 170   void object_iterate(ObjectClosure* blk);
 171   void safe_object_iterate(ObjectClosure* blk);
 172 
 173   void mangle_unused_area() PRODUCT_RETURN;
 174   void mangle_unused_area_complete() PRODUCT_RETURN;
 175 
 176   HeapWord* scan_top() const;
 177   void record_timestamp();
 178   void reset_gc_time_stamp() { _gc_time_stamp = 0; }
 179   uint get_gc_time_stamp() { return _gc_time_stamp; }
 180   void record_retained_region();
 181 
 182   // See the comment above in the declaration of _pre_dummy_top for an
 183   // explanation of what it is.
 184   void set_pre_dummy_top(HeapWord* pre_dummy_top) {
 185     assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
 186     _pre_dummy_top = pre_dummy_top;
 187   }
 188   HeapWord* pre_dummy_top() {
 189     return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
 190   }
 191   void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
 192 
 193   virtual void clear(bool mangle_space);
 194 
 195   HeapWord* block_start(const void* p);
 196   HeapWord* block_start_const(const void* p) const;
 197 
 198   // Allocation (return NULL if full).  Assumes the caller has established
 199   // mutually exclusive access to the space.
 200   HeapWord* allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 201   // Allocation (return NULL if full).  Enforces mutual exclusion internally.
 202   HeapWord* par_allocate(size_t min_word_size, size_t desired_word_size, size_t* actual_word_size);
 203 
 204   virtual HeapWord* allocate(size_t word_size);
 205   virtual HeapWord* par_allocate(size_t word_size);
 206 
 207   HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
 208 
 209   // MarkSweep support phase3
 210   virtual HeapWord* initialize_threshold();
 211   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
 212 
 213   virtual void print() const;
 214 
 215   void reset_bot() {
 216     _bot_part.reset_bot();
 217   }
 218 
 219   void print_bot_on(outputStream* out) {
 220     _bot_part.print_on(out);
 221   }
 222 };
 223 
 224 class HeapRegion: public G1ContiguousSpace {
 225   friend class VMStructs;
 226   // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
 227   template <typename SpaceType>
 228   friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
 229  private:
 230 
 231   // The remembered set for this region.
 232   // (Might want to make this "inline" later, to avoid some alloc failure
 233   // issues.)
 234   HeapRegionRemSet* _rem_set;
 235 
 236   // Auxiliary functions for scan_and_forward support.
 237   // See comments for CompactibleSpace for more information.
 238   inline HeapWord* scan_limit() const {
 239     return top();
 240   }
 241 
 242   inline bool scanned_block_is_obj(const HeapWord* addr) const {
 243     return true; // Always true, since scan_limit is top
 244   }
 245 
 246   inline size_t scanned_block_size(const HeapWord* addr) const {
 247     return HeapRegion::block_size(addr); // Avoid virtual call
 248   }
 249 
 250   void report_region_type_change(G1HeapRegionTraceType::Type to);
 251 
 252   // Returns whether the given object address refers to a dead address, and either the
 253   // size of the object (if live) or the size of the block (if dead) in size.
 254   // Performs some optimizations if is_gc_active is set.
 255   template <bool is_gc_active>
 256   inline bool is_obj_dead_with_size(const oop obj, G1CMBitMapRO* bitmap, size_t* size) const;
 257 
 258  protected:
 259   // The index of this region in the heap region sequence.
 260   uint  _hrm_index;
 261 
 262   AllocationContext_t _allocation_context;
 263 
 264   HeapRegionType _type;
 265 
 266   // For a humongous region, region in which it starts.
 267   HeapRegion* _humongous_start_region;
 268 
 269   // True iff an attempt to evacuate an object in the region failed.
 270   bool _evacuation_failed;
 271 
 272   // Fields used by the HeapRegionSetBase class and subclasses.
 273   HeapRegion* _next;
 274   HeapRegion* _prev;
 275 #ifdef ASSERT
 276   HeapRegionSetBase* _containing_set;
 277 #endif // ASSERT
 278 
 279   // We use concurrent marking to determine the amount of live data
 280   // in each heap region.
 281   size_t _prev_marked_bytes;    // Bytes known to be live via last completed marking.
 282   size_t _next_marked_bytes;    // Bytes known to be live via in-progress marking.
 283 
 284   // The calculated GC efficiency of the region.
 285   double _gc_efficiency;
 286 
 287   int  _young_index_in_cset;
 288   SurvRateGroup* _surv_rate_group;
 289   int  _age_index;
 290 
 291   // The start of the unmarked area. The unmarked area extends from this
 292   // word until the top and/or end of the region, and is the part
 293   // of the region for which no marking was done, i.e. objects may
 294   // have been allocated in this part since the last mark phase.
 295   // "prev" is the top at the start of the last completed marking.
 296   // "next" is the top at the start of the in-progress marking (if any.)
 297   HeapWord* _prev_top_at_mark_start;
 298   HeapWord* _next_top_at_mark_start;
 299   // If a collection pause is in progress, this is the top at the start
 300   // of that pause.
 301 
 302   void init_top_at_mark_start() {
 303     assert(_prev_marked_bytes == 0 &&
 304            _next_marked_bytes == 0,
 305            "Must be called after zero_marked_bytes.");
 306     HeapWord* bot = bottom();
 307     _prev_top_at_mark_start = bot;
 308     _next_top_at_mark_start = bot;
 309   }
 310 
 311   // Cached attributes used in the collection set policy information
 312 
 313   // The RSet length that was added to the total value
 314   // for the collection set.
 315   size_t _recorded_rs_length;
 316 
 317   // The predicted elapsed time that was added to total value
 318   // for the collection set.
 319   double _predicted_elapsed_time_ms;
 320 
 321   // Returns the object size for all valid block starts. Must only be called for
 322   // blocks with an address < top().
 323   size_t block_size_during_gc(const HeapWord* p, const G1CMBitMapRO* bitmap) const;
 324 
 325   // Iterate over the references in a humongous objects and apply the given closure
 326   // to them.
 327   // Humongous objects are allocated directly in the old-gen. So we need special
 328   // handling for concurrent processing encountering an in-progress allocation.
 329   template <class Closure, bool is_gc_active>
 330   inline bool do_oops_on_card_in_humongous(MemRegion mr,
 331                                            Closure* cl,
 332                                            G1CollectedHeap* g1h);
 333  public:
 334   HeapRegion(uint hrm_index,
 335              G1BlockOffsetTable* bot,
 336              MemRegion mr);
 337 
 338   // Initializing the HeapRegion not only resets the data structure, but also
 339   // resets the BOT for that heap region.
 340   // The default values for clear_space means that we will do the clearing if
 341   // there's clearing to be done ourselves. We also always mangle the space.
 342   virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
 343 
 344   static int    LogOfHRGrainBytes;
 345   static int    LogOfHRGrainWords;
 346 
 347   static size_t GrainBytes;
 348   static size_t GrainWords;
 349   static size_t CardsPerRegion;
 350 
 351   static size_t align_up_to_region_byte_size(size_t sz) {
 352     return (sz + (size_t) GrainBytes - 1) &
 353                                       ~((1 << (size_t) LogOfHRGrainBytes) - 1);
 354   }
 355 
 356 
 357   // Returns whether a field is in the same region as the obj it points to.
 358   template <typename T>
 359   static bool is_in_same_region(T* p, oop obj) {
 360     assert(p != NULL, "p can't be NULL");
 361     assert(obj != NULL, "obj can't be NULL");
 362     return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
 363   }
 364 
 365   static size_t max_region_size();
 366   static size_t min_region_size_in_words();
 367 
 368   // It sets up the heap region size (GrainBytes / GrainWords), as
 369   // well as other related fields that are based on the heap region
 370   // size (LogOfHRGrainBytes / LogOfHRGrainWords /
 371   // CardsPerRegion). All those fields are considered constant
 372   // throughout the JVM's execution, therefore they should only be set
 373   // up once during initialization time.
 374   static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
 375 
 376   // All allocated blocks are occupied by objects in a HeapRegion
 377   bool block_is_obj(const HeapWord* p) const;
 378 
 379   // Returns the object size for all valid block starts
 380   // and the amount of unallocated words if called on top()
 381   size_t block_size(const HeapWord* p) const;
 382 
 383   // Override for scan_and_forward support.
 384   void prepare_for_compaction(CompactPoint* cp);
 385 
 386   inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
 387   inline HeapWord* allocate_no_bot_updates(size_t word_size);
 388   inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
 389 
 390   // If this region is a member of a HeapRegionManager, the index in that
 391   // sequence, otherwise -1.
 392   uint hrm_index() const { return _hrm_index; }
 393 
 394   // The number of bytes marked live in the region in the last marking phase.
 395   size_t marked_bytes()    { return _prev_marked_bytes; }
 396   size_t live_bytes() {
 397     return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
 398   }
 399 
 400   // The number of bytes counted in the next marking.
 401   size_t next_marked_bytes() { return _next_marked_bytes; }
 402   // The number of bytes live wrt the next marking.
 403   size_t next_live_bytes() {
 404     return
 405       (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
 406   }
 407 
 408   // A lower bound on the amount of garbage bytes in the region.
 409   size_t garbage_bytes() {
 410     size_t used_at_mark_start_bytes =
 411       (prev_top_at_mark_start() - bottom()) * HeapWordSize;
 412     return used_at_mark_start_bytes - marked_bytes();
 413   }
 414 
 415   // Return the amount of bytes we'll reclaim if we collect this
 416   // region. This includes not only the known garbage bytes in the
 417   // region but also any unallocated space in it, i.e., [top, end),
 418   // since it will also be reclaimed if we collect the region.
 419   size_t reclaimable_bytes() {
 420     size_t known_live_bytes = live_bytes();
 421     assert(known_live_bytes <= capacity(), "sanity");
 422     return capacity() - known_live_bytes;
 423   }
 424 
 425   // An upper bound on the number of live bytes in the region.
 426   size_t max_live_bytes() { return used() - garbage_bytes(); }
 427 
 428   void add_to_marked_bytes(size_t incr_bytes) {
 429     _next_marked_bytes = _next_marked_bytes + incr_bytes;
 430   }
 431 
 432   void zero_marked_bytes()      {
 433     _prev_marked_bytes = _next_marked_bytes = 0;
 434   }
 435 
 436   const char* get_type_str() const { return _type.get_str(); }
 437   const char* get_short_type_str() const { return _type.get_short_str(); }
 438   G1HeapRegionTraceType::Type get_trace_type() { return _type.get_trace_type(); }
 439 
 440   bool is_free() const { return _type.is_free(); }
 441 
 442   bool is_young()    const { return _type.is_young();    }
 443   bool is_eden()     const { return _type.is_eden();     }
 444   bool is_survivor() const { return _type.is_survivor(); }
 445 
 446   bool is_humongous() const { return _type.is_humongous(); }
 447   bool is_starts_humongous() const { return _type.is_starts_humongous(); }
 448   bool is_continues_humongous() const { return _type.is_continues_humongous();   }
 449 
 450   bool is_old() const { return _type.is_old(); }
 451 
 452   bool is_old_or_humongous() const { return _type.is_old_or_humongous(); }
 453 
 454   // A pinned region contains objects which are not moved by garbage collections.
 455   // Humongous regions and archive regions are pinned.
 456   bool is_pinned() const { return _type.is_pinned(); }
 457 
 458   // An archive region is a pinned region, also tagged as old, which
 459   // should not be marked during mark/sweep. This allows the address
 460   // space to be shared by JVM instances.
 461   bool is_archive() const { return _type.is_archive(); }
 462 
 463   // For a humongous region, region in which it starts.
 464   HeapRegion* humongous_start_region() const {
 465     return _humongous_start_region;
 466   }
 467 
 468   // Makes the current region be a "starts humongous" region, i.e.,
 469   // the first region in a series of one or more contiguous regions
 470   // that will contain a single "humongous" object.
 471   //
 472   // obj_top : points to the top of the humongous object.
 473   // fill_size : size of the filler object at the end of the region series.
 474   void set_starts_humongous(HeapWord* obj_top, size_t fill_size);
 475 
 476   // Makes the current region be a "continues humongous'
 477   // region. first_hr is the "start humongous" region of the series
 478   // which this region will be part of.
 479   void set_continues_humongous(HeapRegion* first_hr);
 480 
 481   // Unsets the humongous-related fields on the region.
 482   void clear_humongous();
 483 
 484   // If the region has a remembered set, return a pointer to it.
 485   HeapRegionRemSet* rem_set() const {
 486     return _rem_set;
 487   }
 488 
 489   inline bool in_collection_set() const;
 490 
 491   void set_allocation_context(AllocationContext_t context) {
 492     _allocation_context = context;
 493   }
 494 
 495   AllocationContext_t  allocation_context() const {
 496     return _allocation_context;
 497   }
 498 
 499   // Methods used by the HeapRegionSetBase class and subclasses.
 500 
 501   // Getter and setter for the next and prev fields used to link regions into
 502   // linked lists.
 503   HeapRegion* next()              { return _next; }
 504   HeapRegion* prev()              { return _prev; }
 505 
 506   void set_next(HeapRegion* next) { _next = next; }
 507   void set_prev(HeapRegion* prev) { _prev = prev; }
 508 
 509   // Every region added to a set is tagged with a reference to that
 510   // set. This is used for doing consistency checking to make sure that
 511   // the contents of a set are as they should be and it's only
 512   // available in non-product builds.
 513 #ifdef ASSERT
 514   void set_containing_set(HeapRegionSetBase* containing_set) {
 515     assert((containing_set == NULL && _containing_set != NULL) ||
 516            (containing_set != NULL && _containing_set == NULL),
 517            "containing_set: " PTR_FORMAT " "
 518            "_containing_set: " PTR_FORMAT,
 519            p2i(containing_set), p2i(_containing_set));
 520 
 521     _containing_set = containing_set;
 522   }
 523 
 524   HeapRegionSetBase* containing_set() { return _containing_set; }
 525 #else // ASSERT
 526   void set_containing_set(HeapRegionSetBase* containing_set) { }
 527 
 528   // containing_set() is only used in asserts so there's no reason
 529   // to provide a dummy version of it.
 530 #endif // ASSERT
 531 
 532 
 533   // Reset the HeapRegion to default values.
 534   // If skip_remset is true, do not clear the remembered set.
 535   void hr_clear(bool skip_remset, bool clear_space, bool locked = false);
 536   // Clear the parts skipped by skip_remset in hr_clear() in the HeapRegion during
 537   // a concurrent phase.
 538   void par_clear();
 539 
 540   // Get the start of the unmarked area in this region.
 541   HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
 542   HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
 543 
 544   // Note the start or end of marking. This tells the heap region
 545   // that the collector is about to start or has finished (concurrently)
 546   // marking the heap.
 547 
 548   // Notify the region that concurrent marking is starting. Initialize
 549   // all fields related to the next marking info.
 550   inline void note_start_of_marking();
 551 
 552   // Notify the region that concurrent marking has finished. Copy the
 553   // (now finalized) next marking info fields into the prev marking
 554   // info fields.
 555   inline void note_end_of_marking();
 556 
 557   // Notify the region that it will be used as to-space during a GC
 558   // and we are about to start copying objects into it.
 559   inline void note_start_of_copying(bool during_initial_mark);
 560 
 561   // Notify the region that it ceases being to-space during a GC and
 562   // we will not copy objects into it any more.
 563   inline void note_end_of_copying(bool during_initial_mark);
 564 
 565   // Notify the region that we are about to start processing
 566   // self-forwarded objects during evac failure handling.
 567   void note_self_forwarding_removal_start(bool during_initial_mark,
 568                                           bool during_conc_mark);
 569 
 570   // Notify the region that we have finished processing self-forwarded
 571   // objects during evac failure handling.
 572   void note_self_forwarding_removal_end(size_t marked_bytes);
 573 
 574   // Returns "false" iff no object in the region was allocated when the
 575   // last mark phase ended.
 576   bool is_marked() { return _prev_top_at_mark_start != bottom(); }
 577 
 578   void reset_during_compaction() {
 579     assert(is_humongous(),
 580            "should only be called for humongous regions");
 581 
 582     zero_marked_bytes();
 583     init_top_at_mark_start();
 584   }
 585 
 586   void calc_gc_efficiency(void);
 587   double gc_efficiency() { return _gc_efficiency;}
 588 
 589   int  young_index_in_cset() const { return _young_index_in_cset; }
 590   void set_young_index_in_cset(int index) {
 591     assert( (index == -1) || is_young(), "pre-condition" );
 592     _young_index_in_cset = index;
 593   }
 594 
 595   int age_in_surv_rate_group() {
 596     assert( _surv_rate_group != NULL, "pre-condition" );
 597     assert( _age_index > -1, "pre-condition" );
 598     return _surv_rate_group->age_in_group(_age_index);
 599   }
 600 
 601   void record_surv_words_in_group(size_t words_survived) {
 602     assert( _surv_rate_group != NULL, "pre-condition" );
 603     assert( _age_index > -1, "pre-condition" );
 604     int age_in_group = age_in_surv_rate_group();
 605     _surv_rate_group->record_surviving_words(age_in_group, words_survived);
 606   }
 607 
 608   int age_in_surv_rate_group_cond() {
 609     if (_surv_rate_group != NULL)
 610       return age_in_surv_rate_group();
 611     else
 612       return -1;
 613   }
 614 
 615   SurvRateGroup* surv_rate_group() {
 616     return _surv_rate_group;
 617   }
 618 
 619   void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
 620     assert( surv_rate_group != NULL, "pre-condition" );
 621     assert( _surv_rate_group == NULL, "pre-condition" );
 622     assert( is_young(), "pre-condition" );
 623 
 624     _surv_rate_group = surv_rate_group;
 625     _age_index = surv_rate_group->next_age_index();
 626   }
 627 
 628   void uninstall_surv_rate_group() {
 629     if (_surv_rate_group != NULL) {
 630       assert( _age_index > -1, "pre-condition" );
 631       assert( is_young(), "pre-condition" );
 632 
 633       _surv_rate_group = NULL;
 634       _age_index = -1;
 635     } else {
 636       assert( _age_index == -1, "pre-condition" );
 637     }
 638   }
 639 
 640   void set_free();
 641 
 642   void set_eden();
 643   void set_eden_pre_gc();
 644   void set_survivor();
 645 
 646   void set_old();
 647 
 648   void set_archive();
 649 
 650   // Determine if an object has been allocated since the last
 651   // mark performed by the collector. This returns true iff the object
 652   // is within the unmarked area of the region.
 653   bool obj_allocated_since_prev_marking(oop obj) const {
 654     return (HeapWord *) obj >= prev_top_at_mark_start();
 655   }
 656   bool obj_allocated_since_next_marking(oop obj) const {
 657     return (HeapWord *) obj >= next_top_at_mark_start();
 658   }
 659 
 660   // Returns the "evacuation_failed" property of the region.
 661   bool evacuation_failed() { return _evacuation_failed; }
 662 
 663   // Sets the "evacuation_failed" property of the region.
 664   void set_evacuation_failed(bool b) {
 665     _evacuation_failed = b;
 666 
 667     if (b) {
 668       _next_marked_bytes = 0;
 669     }
 670   }
 671 
 672   // Iterate over the objects overlapping part of a card, applying cl
 673   // to all references in the region.  This is a helper for
 674   // G1RemSet::refine_card, and is tightly coupled with it.
 675   // mr: the memory region covered by the card, trimmed to the
 676   // allocated space for this region.  Must not be empty.
 677   // This region must be old or humongous.
 678   // Returns true if the designated objects were successfully
 679   // processed, false if an unparsable part of the heap was
 680   // encountered; that only happens when invoked concurrently with the
 681   // mutator.
 682   template <class Closure, bool is_gc_active>
 683   inline bool oops_on_card_seq_iterate_careful(MemRegion mr, Closure* cl);
 684 
 685   size_t recorded_rs_length() const        { return _recorded_rs_length; }
 686   double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
 687 
 688   void set_recorded_rs_length(size_t rs_length) {
 689     _recorded_rs_length = rs_length;
 690   }
 691 
 692   void set_predicted_elapsed_time_ms(double ms) {
 693     _predicted_elapsed_time_ms = ms;
 694   }
 695 
 696   virtual CompactibleSpace* next_compaction_space() const;
 697 
 698   virtual void reset_after_compaction();
 699 
 700   // Routines for managing a list of code roots (attached to the
 701   // this region's RSet) that point into this heap region.
 702   void add_strong_code_root(nmethod* nm);
 703   void add_strong_code_root_locked(nmethod* nm);
 704   void remove_strong_code_root(nmethod* nm);
 705 
 706   // Applies blk->do_code_blob() to each of the entries in
 707   // the strong code roots list for this region
 708   void strong_code_roots_do(CodeBlobClosure* blk) const;
 709 
 710   // Verify that the entries on the strong code root list for this
 711   // region are live and include at least one pointer into this region.
 712   void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
 713 
 714   void print() const;
 715   void print_on(outputStream* st) const;
 716 
 717   // vo == UsePrevMarking  -> use "prev" marking information,
 718   // vo == UseNextMarking -> use "next" marking information
 719   // vo == UseMarkWord    -> use the mark word in the object header
 720   //
 721   // NOTE: Only the "prev" marking information is guaranteed to be
 722   // consistent most of the time, so most calls to this should use
 723   // vo == UsePrevMarking.
 724   // Currently, there is only one case where this is called with
 725   // vo == UseNextMarking, which is to verify the "next" marking
 726   // information at the end of remark.
 727   // Currently there is only one place where this is called with
 728   // vo == UseMarkWord, which is to verify the marking during a
 729   // full GC.
 730   void verify(VerifyOption vo, bool *failures) const;
 731 
 732   // Override; it uses the "prev" marking information
 733   virtual void verify() const;
 734 
 735   void verify_rem_set(VerifyOption vo, bool *failures) const;
 736   void verify_rem_set() const;
 737 };
 738 
 739 // HeapRegionClosure is used for iterating over regions.
 740 // Terminates the iteration when the "doHeapRegion" method returns "true".
 741 class HeapRegionClosure : public StackObj {
 742   friend class HeapRegionManager;
 743   friend class G1CollectionSet;
 744 
 745   bool _complete;
 746   void incomplete() { _complete = false; }
 747 
 748  public:
 749   HeapRegionClosure(): _complete(true) {}
 750 
 751   // Typically called on each region until it returns true.
 752   virtual bool doHeapRegion(HeapRegion* r) = 0;
 753 
 754   // True after iteration if the closure was applied to all heap regions
 755   // and returned "false" in all cases.
 756   bool complete() { return _complete; }
 757 };
 758 
 759 #endif // SHARE_VM_GC_G1_HEAPREGION_HPP