rev 7555 : [mq]: propagate_scanrs_closure
rev 7556 : [mq]: review-comments

   1 /*
   2  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  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).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
  27 
  28 #include "gc_implementation/g1/g1AllocationContext.hpp"
  29 #include "gc_implementation/g1/g1BlockOffsetTable.hpp"
  30 #include "gc_implementation/g1/g1_specialized_oop_closures.hpp"
  31 #include "gc_implementation/g1/heapRegionType.hpp"
  32 #include "gc_implementation/g1/survRateGroup.hpp"
  33 #include "gc_implementation/shared/ageTable.hpp"
  34 #include "gc_implementation/shared/spaceDecorator.hpp"
  35 #include "memory/space.inline.hpp"
  36 #include "memory/watermark.hpp"
  37 #include "utilities/macros.hpp"
  38 
  39 // A HeapRegion is the smallest piece of a G1CollectedHeap that
  40 // can be collected independently.
  41 
  42 // NOTE: Although a HeapRegion is a Space, its
  43 // Space::initDirtyCardClosure method must not be called.
  44 // The problem is that the existence of this method breaks
  45 // the independence of barrier sets from remembered sets.
  46 // The solution is to remove this method from the definition
  47 // of a Space.
  48 
  49 class HeapRegionRemSet;
  50 class HeapRegionRemSetIterator;
  51 class HeapRegion;
  52 class HeapRegionSetBase;
  53 class nmethod;
  54 
  55 #define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"
  56 #define HR_FORMAT_PARAMS(_hr_) \
  57                 (_hr_)->hrm_index(), \
  58                 (_hr_)->get_short_type_str(), \
  59                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
  60 
  61 // sentinel value for hrm_index
  62 #define G1_NO_HRM_INDEX ((uint) -1)
  63 
  64 // A dirty card to oop closure for heap regions. It
  65 // knows how to get the G1 heap and how to use the bitmap
  66 // in the concurrent marker used by G1 to filter remembered
  67 // sets.
  68 
  69 class HeapRegionDCTOC : public DirtyCardToOopClosure {
  70 private:
  71   HeapRegion* _hr;
  72   G1ParPushHeapRSClosure* _rs_scan;
  73   G1CollectedHeap* _g1;
  74 
  75   // Walk the given memory region from bottom to (actual) top
  76   // looking for objects and applying the oop closure (_cl) to
  77   // them. The base implementation of this treats the area as
  78   // blocks, where a block may or may not be an object. Sub-
  79   // classes should override this to provide more accurate
  80   // or possibly more efficient walking.
  81   void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
  82 
  83 public:
  84   HeapRegionDCTOC(G1CollectedHeap* g1,
  85                   HeapRegion* hr,
  86                   G1ParPushHeapRSClosure* cl,
  87                   CardTableModRefBS::PrecisionStyle precision);
  88 };
  89 
  90 // The complicating factor is that BlockOffsetTable diverged
  91 // significantly, and we need functionality that is only in the G1 version.
  92 // So I copied that code, which led to an alternate G1 version of
  93 // OffsetTableContigSpace.  If the two versions of BlockOffsetTable could
  94 // be reconciled, then G1OffsetTableContigSpace could go away.
  95 
  96 // The idea behind time stamps is the following. We want to keep track of
  97 // the highest address where it's safe to scan objects for each region.
  98 // This is only relevant for current GC alloc regions so we keep a time stamp
  99 // per region to determine if the region has been allocated during the current
 100 // GC or not. If the time stamp is current we report a scan_top value which
 101 // was saved at the end of the previous GC for retained alloc regions and which is
 102 // equal to the bottom for all other regions.
 103 // There is a race between card scanners and allocating gc workers where we must ensure
 104 // that card scanners do not read the memory allocated by the gc workers.
 105 // In order to enforce that, we must not return a value of _top which is more recent than the
 106 // time stamp. This is due to the fact that a region may become a gc alloc region at
 107 // some point after we've read the timestamp value as being < the current time stamp.
 108 // The time stamps are re-initialized to zero at cleanup and at Full GCs.
 109 // The current scheme that uses sequential unsigned ints will fail only if we have 4b
 110 // evacuation pauses between two cleanups, which is _highly_ unlikely.
 111 class G1OffsetTableContigSpace: public CompactibleSpace {
 112   friend class VMStructs;
 113   HeapWord* _top;
 114   HeapWord* volatile _scan_top;
 115  protected:
 116   G1BlockOffsetArrayContigSpace _offsets;
 117   Mutex _par_alloc_lock;
 118   volatile unsigned _gc_time_stamp;
 119   // When we need to retire an allocation region, while other threads
 120   // are also concurrently trying to allocate into it, we typically
 121   // allocate a dummy object at the end of the region to ensure that
 122   // no more allocations can take place in it. However, sometimes we
 123   // want to know where the end of the last "real" object we allocated
 124   // into the region was and this is what this keeps track.
 125   HeapWord* _pre_dummy_top;
 126 
 127  public:
 128   G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
 129                            MemRegion mr);
 130 
 131   void set_top(HeapWord* value) { _top = value; }
 132   HeapWord* top() const { return _top; }
 133 
 134  protected:
 135   // Reset the G1OffsetTableContigSpace.
 136   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
 137 
 138   HeapWord** top_addr() { return &_top; }
 139   // Allocation helpers (return NULL if full).
 140   inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
 141   inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);
 142 
 143  public:
 144   void reset_after_compaction() { set_top(compaction_top()); }
 145 
 146   size_t used() const { return byte_size(bottom(), top()); }
 147   size_t free() const { return byte_size(top(), end()); }
 148   bool is_free_block(const HeapWord* p) const { return p >= top(); }
 149 
 150   MemRegion used_region() const { return MemRegion(bottom(), top()); }
 151 
 152   void object_iterate(ObjectClosure* blk);
 153   void safe_object_iterate(ObjectClosure* blk);
 154 
 155   void set_bottom(HeapWord* value);
 156   void set_end(HeapWord* value);
 157 
 158   HeapWord* scan_top() const;
 159   void record_timestamp();
 160   void reset_gc_time_stamp() { _gc_time_stamp = 0; }
 161   unsigned get_gc_time_stamp() { return _gc_time_stamp; }
 162   void record_retained_region();
 163 
 164   // See the comment above in the declaration of _pre_dummy_top for an
 165   // explanation of what it is.
 166   void set_pre_dummy_top(HeapWord* pre_dummy_top) {
 167     assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
 168     _pre_dummy_top = pre_dummy_top;
 169   }
 170   HeapWord* pre_dummy_top() {
 171     return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
 172   }
 173   void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
 174 
 175   virtual void clear(bool mangle_space);
 176 
 177   HeapWord* block_start(const void* p);
 178   HeapWord* block_start_const(const void* p) const;
 179 
 180   // Add offset table update.
 181   virtual HeapWord* allocate(size_t word_size);
 182   HeapWord* par_allocate(size_t word_size);
 183 
 184   HeapWord* saved_mark_word() const { ShouldNotReachHere(); return NULL; }
 185 
 186   // MarkSweep support phase3
 187   virtual HeapWord* initialize_threshold();
 188   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
 189 
 190   virtual void print() const;
 191 
 192   void reset_bot() {
 193     _offsets.reset_bot();
 194   }
 195 
 196   void print_bot_on(outputStream* out) {
 197     _offsets.print_on(out);
 198   }
 199 };
 200 
 201 class HeapRegion: public G1OffsetTableContigSpace {
 202   friend class VMStructs;
 203   // Allow scan_and_forward to call (private) overrides for auxiliary functions on this class
 204   template <typename SpaceType>
 205   friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
 206  private:
 207 
 208   // The remembered set for this region.
 209   // (Might want to make this "inline" later, to avoid some alloc failure
 210   // issues.)
 211   HeapRegionRemSet* _rem_set;
 212 
 213   G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
 214 
 215   // Auxiliary functions for scan_and_forward support.
 216   // See comments for CompactibleSpace for more information.
 217   inline HeapWord* scan_limit() const {
 218     return top();
 219   }
 220 
 221   inline bool scanned_block_is_obj(const HeapWord* addr) const {
 222     return true; // Always true, since scan_limit is top
 223   }
 224 
 225   inline size_t scanned_block_size(const HeapWord* addr) const {
 226     return HeapRegion::block_size(addr); // Avoid virtual call
 227   }
 228 
 229  protected:
 230   // The index of this region in the heap region sequence.
 231   uint  _hrm_index;
 232 
 233   AllocationContext_t _allocation_context;
 234 
 235   HeapRegionType _type;
 236 
 237   // For a humongous region, region in which it starts.
 238   HeapRegion* _humongous_start_region;
 239   // True iff the region is in current collection_set.
 240   bool _in_collection_set;
 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 
 335   // It sets up the heap region size (GrainBytes / GrainWords), as
 336   // well as other related fields that are based on the heap region
 337   // size (LogOfHRGrainBytes / LogOfHRGrainWords /
 338   // CardsPerRegion). All those fields are considered constant
 339   // throughout the JVM's execution, therefore they should only be set
 340   // up once during initialization time.
 341   static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
 342 
 343   // All allocated blocks are occupied by objects in a HeapRegion
 344   bool block_is_obj(const HeapWord* p) const;
 345 
 346   // Returns the object size for all valid block starts
 347   // and the amount of unallocated words if called on top()
 348   size_t block_size(const HeapWord* p) const;
 349 
 350   // Override for scan_and_forward support.
 351   void prepare_for_compaction(CompactPoint* cp);
 352 
 353   inline HeapWord* par_allocate_no_bot_updates(size_t word_size);
 354   inline HeapWord* allocate_no_bot_updates(size_t word_size);
 355 
 356   // If this region is a member of a HeapRegionManager, the index in that
 357   // sequence, otherwise -1.
 358   uint hrm_index() const { return _hrm_index; }
 359 
 360   // The number of bytes marked live in the region in the last marking phase.
 361   size_t marked_bytes()    { return _prev_marked_bytes; }
 362   size_t live_bytes() {
 363     return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
 364   }
 365 
 366   // The number of bytes counted in the next marking.
 367   size_t next_marked_bytes() { return _next_marked_bytes; }
 368   // The number of bytes live wrt the next marking.
 369   size_t next_live_bytes() {
 370     return
 371       (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
 372   }
 373 
 374   // A lower bound on the amount of garbage bytes in the region.
 375   size_t garbage_bytes() {
 376     size_t used_at_mark_start_bytes =
 377       (prev_top_at_mark_start() - bottom()) * HeapWordSize;
 378     assert(used_at_mark_start_bytes >= marked_bytes(),
 379            "Can't mark more than we have.");
 380     return used_at_mark_start_bytes - marked_bytes();
 381   }
 382 
 383   // Return the amount of bytes we'll reclaim if we collect this
 384   // region. This includes not only the known garbage bytes in the
 385   // region but also any unallocated space in it, i.e., [top, end),
 386   // since it will also be reclaimed if we collect the region.
 387   size_t reclaimable_bytes() {
 388     size_t known_live_bytes = live_bytes();
 389     assert(known_live_bytes <= capacity(), "sanity");
 390     return capacity() - known_live_bytes;
 391   }
 392 
 393   // An upper bound on the number of live bytes in the region.
 394   size_t max_live_bytes() { return used() - garbage_bytes(); }
 395 
 396   void add_to_marked_bytes(size_t incr_bytes) {
 397     _next_marked_bytes = _next_marked_bytes + incr_bytes;
 398     assert(_next_marked_bytes <= used(), "invariant" );
 399   }
 400 
 401   void zero_marked_bytes()      {
 402     _prev_marked_bytes = _next_marked_bytes = 0;
 403   }
 404 
 405   const char* get_type_str() const { return _type.get_str(); }
 406   const char* get_short_type_str() const { return _type.get_short_str(); }
 407 
 408   bool is_free() const { return _type.is_free(); }
 409 
 410   bool is_young()    const { return _type.is_young();    }
 411   bool is_eden()     const { return _type.is_eden();     }
 412   bool is_survivor() const { return _type.is_survivor(); }
 413 
 414   bool is_humongous() const { return _type.is_humongous(); }
 415   bool is_starts_humongous() const { return _type.is_starts_humongous(); }
 416   bool is_continues_humongous() const { return _type.is_continues_humongous();   }
 417 
 418   bool is_old() const { return _type.is_old(); }
 419 
 420   // For a humongous region, region in which it starts.
 421   HeapRegion* humongous_start_region() const {
 422     return _humongous_start_region;
 423   }
 424 
 425   // Return the number of distinct regions that are covered by this region:
 426   // 1 if the region is not humongous, >= 1 if the region is humongous.
 427   uint region_num() const {
 428     if (!is_humongous()) {
 429       return 1U;
 430     } else {
 431       assert(is_starts_humongous(), "doesn't make sense on HC regions");
 432       assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
 433       return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
 434     }
 435   }
 436 
 437   // Return the index + 1 of the last HC regions that's associated
 438   // with this HS region.
 439   uint last_hc_index() const {
 440     assert(is_starts_humongous(), "don't call this otherwise");
 441     return hrm_index() + region_num();
 442   }
 443 
 444   // Same as Space::is_in_reserved, but will use the original size of the region.
 445   // The original size is different only for start humongous regions. They get
 446   // their _end set up to be the end of the last continues region of the
 447   // corresponding humongous object.
 448   bool is_in_reserved_raw(const void* p) const {
 449     return _bottom <= p && p < orig_end();
 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. The two parameters
 455   // are as follows:
 456   //
 457   // new_top : The new value of the top field of this region which
 458   // points to the end of the humongous object that's being
 459   // allocated. If there is more than one region in the series, top
 460   // will lie beyond this region's original end field and on the last
 461   // region in the series.
 462   //
 463   // new_end : The new value of the end field of this region which
 464   // points to the end of the last region in the series. If there is
 465   // one region in the series (namely: this one) end will be the same
 466   // as the original end of this region.
 467   //
 468   // Updating top and end as described above makes this region look as
 469   // if it spans the entire space taken up by all the regions in the
 470   // series and an single allocation moved its top to new_top. This
 471   // ensures that the space (capacity / allocated) taken up by all
 472   // humongous regions can be calculated by just looking at the
 473   // "starts humongous" regions and by ignoring the "continues
 474   // humongous" regions.
 475   void set_starts_humongous(HeapWord* new_top, HeapWord* new_end);
 476 
 477   // Makes the current region be a "continues humongous'
 478   // region. first_hr is the "start humongous" region of the series
 479   // which this region will be part of.
 480   void set_continues_humongous(HeapRegion* first_hr);
 481 
 482   // Unsets the humongous-related fields on the region.
 483   void clear_humongous();
 484 
 485   // If the region has a remembered set, return a pointer to it.
 486   HeapRegionRemSet* rem_set() const {
 487     return _rem_set;
 488   }
 489 
 490   // True iff the region is in current collection_set.
 491   bool in_collection_set() const {
 492     return _in_collection_set;
 493   }
 494   void set_in_collection_set(bool b) {
 495     _in_collection_set = b;
 496   }
 497   HeapRegion* next_in_collection_set() {
 498     assert(in_collection_set(), "should only invoke on member of CS.");
 499     assert(_next_in_special_set == NULL ||
 500            _next_in_special_set->in_collection_set(),
 501            "Malformed CS.");
 502     return _next_in_special_set;
 503   }
 504   void set_next_in_collection_set(HeapRegion* r) {
 505     assert(in_collection_set(), "should only invoke on member of CS.");
 506     assert(r == NULL || r->in_collection_set(), "Malformed CS.");
 507     _next_in_special_set = r;
 508   }
 509 
 510   void set_allocation_context(AllocationContext_t context) {
 511     _allocation_context = context;
 512   }
 513 
 514   AllocationContext_t  allocation_context() const {
 515     return _allocation_context;
 516   }
 517 
 518   // Methods used by the HeapRegionSetBase class and subclasses.
 519 
 520   // Getter and setter for the next and prev fields used to link regions into
 521   // linked lists.
 522   HeapRegion* next()              { return _next; }
 523   HeapRegion* prev()              { return _prev; }
 524 
 525   void set_next(HeapRegion* next) { _next = next; }
 526   void set_prev(HeapRegion* prev) { _prev = prev; }
 527 
 528   // Every region added to a set is tagged with a reference to that
 529   // set. This is used for doing consistency checking to make sure that
 530   // the contents of a set are as they should be and it's only
 531   // available in non-product builds.
 532 #ifdef ASSERT
 533   void set_containing_set(HeapRegionSetBase* containing_set) {
 534     assert((containing_set == NULL && _containing_set != NULL) ||
 535            (containing_set != NULL && _containing_set == NULL),
 536            err_msg("containing_set: "PTR_FORMAT" "
 537                    "_containing_set: "PTR_FORMAT,
 538                    p2i(containing_set), p2i(_containing_set)));
 539 
 540     _containing_set = containing_set;
 541   }
 542 
 543   HeapRegionSetBase* containing_set() { return _containing_set; }
 544 #else // ASSERT
 545   void set_containing_set(HeapRegionSetBase* containing_set) { }
 546 
 547   // containing_set() is only used in asserts so there's no reason
 548   // to provide a dummy version of it.
 549 #endif // ASSERT
 550 
 551   HeapRegion* get_next_young_region() { return _next_young_region; }
 552   void set_next_young_region(HeapRegion* hr) {
 553     _next_young_region = hr;
 554   }
 555 
 556   HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
 557   HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
 558   void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
 559   bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
 560 
 561   // For the start region of a humongous sequence, it's original end().
 562   HeapWord* orig_end() const { return _bottom + GrainWords; }
 563 
 564   // Reset HR stuff to default values.
 565   void hr_clear(bool par, bool clear_space, bool locked = false);
 566   void par_clear();
 567 
 568   // Get the start of the unmarked area in this region.
 569   HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
 570   HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
 571 
 572   // Note the start or end of marking. This tells the heap region
 573   // that the collector is about to start or has finished (concurrently)
 574   // marking the heap.
 575 
 576   // Notify the region that concurrent marking is starting. Initialize
 577   // all fields related to the next marking info.
 578   inline void note_start_of_marking();
 579 
 580   // Notify the region that concurrent marking has finished. Copy the
 581   // (now finalized) next marking info fields into the prev marking
 582   // info fields.
 583   inline void note_end_of_marking();
 584 
 585   // Notify the region that it will be used as to-space during a GC
 586   // and we are about to start copying objects into it.
 587   inline void note_start_of_copying(bool during_initial_mark);
 588 
 589   // Notify the region that it ceases being to-space during a GC and
 590   // we will not copy objects into it any more.
 591   inline void note_end_of_copying(bool during_initial_mark);
 592 
 593   // Notify the region that we are about to start processing
 594   // self-forwarded objects during evac failure handling.
 595   void note_self_forwarding_removal_start(bool during_initial_mark,
 596                                           bool during_conc_mark);
 597 
 598   // Notify the region that we have finished processing self-forwarded
 599   // objects during evac failure handling.
 600   void note_self_forwarding_removal_end(bool during_initial_mark,
 601                                         bool during_conc_mark,
 602                                         size_t marked_bytes);
 603 
 604   // Returns "false" iff no object in the region was allocated when the
 605   // last mark phase ended.
 606   bool is_marked() { return _prev_top_at_mark_start != bottom(); }
 607 
 608   void reset_during_compaction() {
 609     assert(is_starts_humongous(),
 610            "should only be called for starts humongous regions");
 611 
 612     zero_marked_bytes();
 613     init_top_at_mark_start();
 614   }
 615 
 616   void calc_gc_efficiency(void);
 617   double gc_efficiency() { return _gc_efficiency;}
 618 
 619   int  young_index_in_cset() const { return _young_index_in_cset; }
 620   void set_young_index_in_cset(int index) {
 621     assert( (index == -1) || is_young(), "pre-condition" );
 622     _young_index_in_cset = index;
 623   }
 624 
 625   int age_in_surv_rate_group() {
 626     assert( _surv_rate_group != NULL, "pre-condition" );
 627     assert( _age_index > -1, "pre-condition" );
 628     return _surv_rate_group->age_in_group(_age_index);
 629   }
 630 
 631   void record_surv_words_in_group(size_t words_survived) {
 632     assert( _surv_rate_group != NULL, "pre-condition" );
 633     assert( _age_index > -1, "pre-condition" );
 634     int age_in_group = age_in_surv_rate_group();
 635     _surv_rate_group->record_surviving_words(age_in_group, words_survived);
 636   }
 637 
 638   int age_in_surv_rate_group_cond() {
 639     if (_surv_rate_group != NULL)
 640       return age_in_surv_rate_group();
 641     else
 642       return -1;
 643   }
 644 
 645   SurvRateGroup* surv_rate_group() {
 646     return _surv_rate_group;
 647   }
 648 
 649   void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
 650     assert( surv_rate_group != NULL, "pre-condition" );
 651     assert( _surv_rate_group == NULL, "pre-condition" );
 652     assert( is_young(), "pre-condition" );
 653 
 654     _surv_rate_group = surv_rate_group;
 655     _age_index = surv_rate_group->next_age_index();
 656   }
 657 
 658   void uninstall_surv_rate_group() {
 659     if (_surv_rate_group != NULL) {
 660       assert( _age_index > -1, "pre-condition" );
 661       assert( is_young(), "pre-condition" );
 662 
 663       _surv_rate_group = NULL;
 664       _age_index = -1;
 665     } else {
 666       assert( _age_index == -1, "pre-condition" );
 667     }
 668   }
 669 
 670   void set_free() { _type.set_free(); }
 671 
 672   void set_eden()        { _type.set_eden();        }
 673   void set_eden_pre_gc() { _type.set_eden_pre_gc(); }
 674   void set_survivor()    { _type.set_survivor();    }
 675 
 676   void set_old() { _type.set_old(); }
 677 
 678   // Determine if an object has been allocated since the last
 679   // mark performed by the collector. This returns true iff the object
 680   // is within the unmarked area of the region.
 681   bool obj_allocated_since_prev_marking(oop obj) const {
 682     return (HeapWord *) obj >= prev_top_at_mark_start();
 683   }
 684   bool obj_allocated_since_next_marking(oop obj) const {
 685     return (HeapWord *) obj >= next_top_at_mark_start();
 686   }
 687 
 688   // Returns the "evacuation_failed" property of the region.
 689   bool evacuation_failed() { return _evacuation_failed; }
 690 
 691   // Sets the "evacuation_failed" property of the region.
 692   void set_evacuation_failed(bool b) {
 693     _evacuation_failed = b;
 694 
 695     if (b) {
 696       _next_marked_bytes = 0;
 697     }
 698   }
 699 
 700   // Requires that "mr" be entirely within the region.
 701   // Apply "cl->do_object" to all objects that intersect with "mr".
 702   // If the iteration encounters an unparseable portion of the region,
 703   // or if "cl->abort()" is true after a closure application,
 704   // terminate the iteration and return the address of the start of the
 705   // subregion that isn't done.  (The two can be distinguished by querying
 706   // "cl->abort()".)  Return of "NULL" indicates that the iteration
 707   // completed.
 708   HeapWord*
 709   object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
 710 
 711   // filter_young: if true and the region is a young region then we
 712   // skip the iteration.
 713   // card_ptr: if not NULL, and we decide that the card is not young
 714   // and we iterate over it, we'll clean the card before we start the
 715   // iteration.
 716   HeapWord*
 717   oops_on_card_seq_iterate_careful(MemRegion mr,
 718                                    FilterOutOfRegionClosure* cl,
 719                                    bool filter_young,
 720                                    jbyte* card_ptr);
 721 
 722   size_t recorded_rs_length() const        { return _recorded_rs_length; }
 723   double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
 724   size_t predicted_bytes_to_copy() const   { return _predicted_bytes_to_copy; }
 725 
 726   void set_recorded_rs_length(size_t rs_length) {
 727     _recorded_rs_length = rs_length;
 728   }
 729 
 730   void set_predicted_elapsed_time_ms(double ms) {
 731     _predicted_elapsed_time_ms = ms;
 732   }
 733 
 734   void set_predicted_bytes_to_copy(size_t bytes) {
 735     _predicted_bytes_to_copy = bytes;
 736   }
 737 
 738   virtual CompactibleSpace* next_compaction_space() const;
 739 
 740   virtual void reset_after_compaction();
 741 
 742   // Routines for managing a list of code roots (attached to the
 743   // this region's RSet) that point into this heap region.
 744   void add_strong_code_root(nmethod* nm);
 745   void add_strong_code_root_locked(nmethod* nm);
 746   void remove_strong_code_root(nmethod* nm);
 747 
 748   // Applies blk->do_code_blob() to each of the entries in
 749   // the strong code roots list for this region
 750   void strong_code_roots_do(CodeBlobClosure* blk) const;
 751 
 752   // Verify that the entries on the strong code root list for this
 753   // region are live and include at least one pointer into this region.
 754   void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
 755 
 756   void print() const;
 757   void print_on(outputStream* st) const;
 758 
 759   // vo == UsePrevMarking  -> use "prev" marking information,
 760   // vo == UseNextMarking -> use "next" marking information
 761   // vo == UseMarkWord    -> use the mark word in the object header
 762   //
 763   // NOTE: Only the "prev" marking information is guaranteed to be
 764   // consistent most of the time, so most calls to this should use
 765   // vo == UsePrevMarking.
 766   // Currently, there is only one case where this is called with
 767   // vo == UseNextMarking, which is to verify the "next" marking
 768   // information at the end of remark.
 769   // Currently there is only one place where this is called with
 770   // vo == UseMarkWord, which is to verify the marking during a
 771   // full GC.
 772   void verify(VerifyOption vo, bool *failures) const;
 773 
 774   // Override; it uses the "prev" marking information
 775   virtual void verify() const;
 776 };
 777 
 778 // HeapRegionClosure is used for iterating over regions.
 779 // Terminates the iteration when the "doHeapRegion" method returns "true".
 780 class HeapRegionClosure : public StackObj {
 781   friend class HeapRegionManager;
 782   friend class G1CollectedHeap;
 783 
 784   bool _complete;
 785   void incomplete() { _complete = false; }
 786 
 787  public:
 788   HeapRegionClosure(): _complete(true) {}
 789 
 790   // Typically called on each region until it returns true.
 791   virtual bool doHeapRegion(HeapRegion* r) = 0;
 792 
 793   // True after iteration if the closure was applied to all heap regions
 794   // and returned "false" in all cases.
 795   bool complete() { return _complete; }
 796 };
 797 
 798 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
--- EOF ---