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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
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
  27 
  28 #include "gc_implementation/g1/g1AllocationContext.hpp"
  29 #include "gc_implementation/g1/g1Allocator.hpp"
  30 #include "gc_implementation/g1/concurrentMark.hpp"
  31 #include "gc_implementation/g1/evacuationInfo.hpp"
  32 #include "gc_implementation/g1/g1AllocRegion.hpp"
  33 #include "gc_implementation/g1/g1BiasedArray.hpp"
  34 #include "gc_implementation/g1/g1HRPrinter.hpp"
  35 #include "gc_implementation/g1/g1InCSetState.hpp"
  36 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
  37 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
  38 #include "gc_implementation/g1/g1YCTypes.hpp"
  39 #include "gc_implementation/g1/heapRegionManager.hpp"
  40 #include "gc_implementation/g1/heapRegionSet.hpp"
  41 #include "gc_implementation/shared/hSpaceCounters.hpp"
  42 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
  43 #include "memory/barrierSet.hpp"
  44 #include "memory/memRegion.hpp"
  45 #include "memory/sharedHeap.hpp"
  46 #include "utilities/stack.hpp"
  47 
  48 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  49 // It uses the "Garbage First" heap organization and algorithm, which
  50 // may combine concurrent marking with parallel, incremental compaction of
  51 // heap subsets that will yield large amounts of garbage.
  52 
  53 // Forward declarations
  54 class HeapRegion;
  55 class HRRSCleanupTask;
  56 class GenerationSpec;
  57 class OopsInHeapRegionClosure;
  58 class G1KlassScanClosure;
  59 class G1ScanHeapEvacClosure;
  60 class ObjectClosure;
  61 class SpaceClosure;
  62 class CompactibleSpaceClosure;
  63 class Space;
  64 class G1CollectorPolicy;
  65 class GenRemSet;
  66 class G1RemSet;
  67 class HeapRegionRemSetIterator;
  68 class ConcurrentMark;
  69 class ConcurrentMarkThread;
  70 class ConcurrentG1Refine;
  71 class ConcurrentGCTimer;
  72 class GenerationCounters;
  73 class STWGCTimer;
  74 class G1NewTracer;
  75 class G1OldTracer;
  76 class EvacuationFailedInfo;
  77 class nmethod;
  78 class Ticks;
  79 
  80 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
  81 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
  82 
  83 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
  84 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
  85 
  86 class YoungList : public CHeapObj<mtGC> {
  87 private:
  88   G1CollectedHeap* _g1h;
  89 
  90   HeapRegion* _head;
  91 
  92   HeapRegion* _survivor_head;
  93   HeapRegion* _survivor_tail;
  94 
  95   HeapRegion* _curr;
  96 
  97   uint        _length;
  98   uint        _survivor_length;
  99 
 100   size_t      _last_sampled_rs_lengths;
 101   size_t      _sampled_rs_lengths;
 102 
 103   void         empty_list(HeapRegion* list);
 104 
 105 public:
 106   YoungList(G1CollectedHeap* g1h);
 107 
 108   void         push_region(HeapRegion* hr);
 109   void         add_survivor_region(HeapRegion* hr);
 110 
 111   void         empty_list();
 112   bool         is_empty() { return _length == 0; }
 113   uint         length() { return _length; }
 114   uint         survivor_length() { return _survivor_length; }
 115 
 116   // Currently we do not keep track of the used byte sum for the
 117   // young list and the survivors and it'd be quite a lot of work to
 118   // do so. When we'll eventually replace the young list with
 119   // instances of HeapRegionLinkedList we'll get that for free. So,
 120   // we'll report the more accurate information then.
 121   size_t       eden_used_bytes() {
 122     assert(length() >= survivor_length(), "invariant");
 123     return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
 124   }
 125   size_t       survivor_used_bytes() {
 126     return (size_t) survivor_length() * HeapRegion::GrainBytes;
 127   }
 128 
 129   void rs_length_sampling_init();
 130   bool rs_length_sampling_more();
 131   void rs_length_sampling_next();
 132 
 133   void reset_sampled_info() {
 134     _last_sampled_rs_lengths =   0;
 135   }
 136   size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
 137 
 138   // for development purposes
 139   void reset_auxilary_lists();
 140   void clear() { _head = NULL; _length = 0; }
 141 
 142   void clear_survivors() {
 143     _survivor_head    = NULL;
 144     _survivor_tail    = NULL;
 145     _survivor_length  = 0;
 146   }
 147 
 148   HeapRegion* first_region() { return _head; }
 149   HeapRegion* first_survivor_region() { return _survivor_head; }
 150   HeapRegion* last_survivor_region() { return _survivor_tail; }
 151 
 152   // debugging
 153   bool          check_list_well_formed();
 154   bool          check_list_empty(bool check_sample = true);
 155   void          print();
 156 };
 157 
 158 // The G1 STW is alive closure.
 159 // An instance is embedded into the G1CH and used as the
 160 // (optional) _is_alive_non_header closure in the STW
 161 // reference processor. It is also extensively used during
 162 // reference processing during STW evacuation pauses.
 163 class G1STWIsAliveClosure: public BoolObjectClosure {
 164   G1CollectedHeap* _g1;
 165 public:
 166   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 167   bool do_object_b(oop p);
 168 };
 169 
 170 class RefineCardTableEntryClosure;
 171 
 172 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 173  private:
 174   void reset_from_card_cache(uint start_idx, size_t num_regions);
 175  public:
 176   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 177 };
 178 
 179 class G1CollectedHeap : public SharedHeap {
 180   friend class VM_CollectForMetadataAllocation;
 181   friend class VM_G1CollectForAllocation;
 182   friend class VM_G1CollectFull;
 183   friend class VM_G1IncCollectionPause;
 184   friend class VMStructs;
 185   friend class MutatorAllocRegion;
 186   friend class SurvivorGCAllocRegion;
 187   friend class OldGCAllocRegion;
 188   friend class G1Allocator;
 189   friend class G1DefaultAllocator;
 190   friend class G1ResManAllocator;
 191 
 192   // Closures used in implementation.
 193   template <G1Barrier barrier, G1Mark do_mark_object>
 194   friend class G1ParCopyClosure;
 195   friend class G1IsAliveClosure;
 196   friend class G1EvacuateFollowersClosure;
 197   friend class G1ParScanThreadState;
 198   friend class G1ParScanClosureSuper;
 199   friend class G1ParEvacuateFollowersClosure;
 200   friend class G1ParTask;
 201   friend class G1ParGCAllocator;
 202   friend class G1DefaultParGCAllocator;
 203   friend class G1FreeGarbageRegionClosure;
 204   friend class RefineCardTableEntryClosure;
 205   friend class G1PrepareCompactClosure;
 206   friend class RegionSorter;
 207   friend class RegionResetter;
 208   friend class CountRCClosure;
 209   friend class EvacPopObjClosure;
 210   friend class G1ParCleanupCTTask;
 211 
 212   friend class G1FreeHumongousRegionClosure;
 213   // Other related classes.
 214   friend class G1MarkSweep;
 215 
 216   // Testing classes.
 217   friend class G1CheckCSetFastTableClosure;
 218 
 219 private:
 220   // The one and only G1CollectedHeap, so static functions can find it.
 221   static G1CollectedHeap* _g1h;
 222 
 223   static size_t _humongous_object_threshold_in_words;
 224 
 225   // The secondary free list which contains regions that have been
 226   // freed up during the cleanup process. This will be appended to
 227   // the master free list when appropriate.
 228   FreeRegionList _secondary_free_list;
 229 
 230   // It keeps track of the old regions.
 231   HeapRegionSet _old_set;
 232 
 233   // It keeps track of the humongous regions.
 234   HeapRegionSet _humongous_set;
 235 
 236   void clear_humongous_is_live_table();
 237   void eagerly_reclaim_humongous_regions();
 238 
 239   // The number of regions we could create by expansion.
 240   uint _expansion_regions;
 241 
 242   // The block offset table for the G1 heap.
 243   G1BlockOffsetSharedArray* _bot_shared;
 244 
 245   // Tears down the region sets / lists so that they are empty and the
 246   // regions on the heap do not belong to a region set / list. The
 247   // only exception is the humongous set which we leave unaltered. If
 248   // free_list_only is true, it will only tear down the master free
 249   // list. It is called before a Full GC (free_list_only == false) or
 250   // before heap shrinking (free_list_only == true).
 251   void tear_down_region_sets(bool free_list_only);
 252 
 253   // Rebuilds the region sets / lists so that they are repopulated to
 254   // reflect the contents of the heap. The only exception is the
 255   // humongous set which was not torn down in the first place. If
 256   // free_list_only is true, it will only rebuild the master free
 257   // list. It is called after a Full GC (free_list_only == false) or
 258   // after heap shrinking (free_list_only == true).
 259   void rebuild_region_sets(bool free_list_only);
 260 
 261   // Callback for region mapping changed events.
 262   G1RegionMappingChangedListener _listener;
 263 
 264   // The sequence of all heap regions in the heap.
 265   HeapRegionManager _hrm;
 266 
 267   // Class that handles the different kinds of allocations.
 268   G1Allocator* _allocator;
 269 
 270   // Statistics for each allocation context
 271   AllocationContextStats _allocation_context_stats;
 272 
 273   // PLAB sizing policy for survivors.
 274   PLABStats _survivor_plab_stats;
 275 
 276   // PLAB sizing policy for tenured objects.
 277   PLABStats _old_plab_stats;
 278 
 279   // It specifies whether we should attempt to expand the heap after a
 280   // region allocation failure. If heap expansion fails we set this to
 281   // false so that we don't re-attempt the heap expansion (it's likely
 282   // that subsequent expansion attempts will also fail if one fails).
 283   // Currently, it is only consulted during GC and it's reset at the
 284   // start of each GC.
 285   bool _expand_heap_after_alloc_failure;
 286 
 287   // It resets the mutator alloc region before new allocations can take place.
 288   void init_mutator_alloc_region();
 289 
 290   // It releases the mutator alloc region.
 291   void release_mutator_alloc_region();
 292 
 293   // It initializes the GC alloc regions at the start of a GC.
 294   void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
 295 
 296   // It releases the GC alloc regions at the end of a GC.
 297   void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
 298 
 299   // It does any cleanup that needs to be done on the GC alloc regions
 300   // before a Full GC.
 301   void abandon_gc_alloc_regions();
 302 
 303   // Helper for monitoring and management support.
 304   G1MonitoringSupport* _g1mm;
 305 
 306   // Records whether the region at the given index is kept live by roots or
 307   // references from the young generation.
 308   class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> {
 309    protected:
 310     bool default_value() const { return false; }
 311    public:
 312     void clear() { G1BiasedMappedArray<bool>::clear(); }
 313     void set_live(uint region) {
 314       set_by_index(region, true);
 315     }
 316     bool is_live(uint region) {
 317       return get_by_index(region);
 318     }
 319   };
 320 
 321   HumongousIsLiveBiasedMappedArray _humongous_is_live;
 322   // Stores whether during humongous object registration we found candidate regions.
 323   // If not, we can skip a few steps.
 324   bool _has_humongous_reclaim_candidates;
 325 
 326   volatile unsigned _gc_time_stamp;
 327 
 328   size_t* _surviving_young_words;
 329 
 330   G1HRPrinter _hr_printer;
 331 
 332   void setup_surviving_young_words();
 333   void update_surviving_young_words(size_t* surv_young_words);
 334   void cleanup_surviving_young_words();
 335 
 336   // It decides whether an explicit GC should start a concurrent cycle
 337   // instead of doing a STW GC. Currently, a concurrent cycle is
 338   // explicitly started if:
 339   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 340   // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 341   // (c) cause == _g1_humongous_allocation
 342   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 343 
 344   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 345   // concurrent cycles) we have started.
 346   volatile unsigned int _old_marking_cycles_started;
 347 
 348   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 349   // concurrent cycles) we have completed.
 350   volatile unsigned int _old_marking_cycles_completed;
 351 
 352   bool _concurrent_cycle_started;
 353   bool _heap_summary_sent;
 354 
 355   // This is a non-product method that is helpful for testing. It is
 356   // called at the end of a GC and artificially expands the heap by
 357   // allocating a number of dead regions. This way we can induce very
 358   // frequent marking cycles and stress the cleanup / concurrent
 359   // cleanup code more (as all the regions that will be allocated by
 360   // this method will be found dead by the marking cycle).
 361   void allocate_dummy_regions() PRODUCT_RETURN;
 362 
 363   // Clear RSets after a compaction. It also resets the GC time stamps.
 364   void clear_rsets_post_compaction();
 365 
 366   // If the HR printer is active, dump the state of the regions in the
 367   // heap after a compaction.
 368   void print_hrm_post_compaction();
 369 
 370   double verify(bool guard, const char* msg);
 371   void verify_before_gc();
 372   void verify_after_gc();
 373 
 374   void log_gc_header();
 375   void log_gc_footer(double pause_time_sec);
 376 
 377   // These are macros so that, if the assert fires, we get the correct
 378   // line number, file, etc.
 379 
 380 #define heap_locking_asserts_err_msg(_extra_message_)                         \
 381   err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",    \
 382           (_extra_message_),                                                  \
 383           BOOL_TO_STR(Heap_lock->owned_by_self()),                            \
 384           BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),               \
 385           BOOL_TO_STR(Thread::current()->is_VM_thread()))
 386 
 387 #define assert_heap_locked()                                                  \
 388   do {                                                                        \
 389     assert(Heap_lock->owned_by_self(),                                        \
 390            heap_locking_asserts_err_msg("should be holding the Heap_lock"));  \
 391   } while (0)
 392 
 393 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 394   do {                                                                        \
 395     assert(Heap_lock->owned_by_self() ||                                      \
 396            (SafepointSynchronize::is_at_safepoint() &&                        \
 397              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 398            heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
 399                                         "should be at a safepoint"));         \
 400   } while (0)
 401 
 402 #define assert_heap_locked_and_not_at_safepoint()                             \
 403   do {                                                                        \
 404     assert(Heap_lock->owned_by_self() &&                                      \
 405                                     !SafepointSynchronize::is_at_safepoint(), \
 406           heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
 407                                        "should not be at a safepoint"));      \
 408   } while (0)
 409 
 410 #define assert_heap_not_locked()                                              \
 411   do {                                                                        \
 412     assert(!Heap_lock->owned_by_self(),                                       \
 413         heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
 414   } while (0)
 415 
 416 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 417   do {                                                                        \
 418     assert(!Heap_lock->owned_by_self() &&                                     \
 419                                     !SafepointSynchronize::is_at_safepoint(), \
 420       heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
 421                                    "should not be at a safepoint"));          \
 422   } while (0)
 423 
 424 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 425   do {                                                                        \
 426     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 427               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 428            heap_locking_asserts_err_msg("should be at a safepoint"));         \
 429   } while (0)
 430 
 431 #define assert_not_at_safepoint()                                             \
 432   do {                                                                        \
 433     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 434            heap_locking_asserts_err_msg("should not be at a safepoint"));     \
 435   } while (0)
 436 
 437 protected:
 438 
 439   // The young region list.
 440   YoungList*  _young_list;
 441 
 442   // The current policy object for the collector.
 443   G1CollectorPolicy* _g1_policy;
 444 
 445   // This is the second level of trying to allocate a new region. If
 446   // new_region() didn't find a region on the free_list, this call will
 447   // check whether there's anything available on the
 448   // secondary_free_list and/or wait for more regions to appear on
 449   // that list, if _free_regions_coming is set.
 450   HeapRegion* new_region_try_secondary_free_list(bool is_old);
 451 
 452   // Try to allocate a single non-humongous HeapRegion sufficient for
 453   // an allocation of the given word_size. If do_expand is true,
 454   // attempt to expand the heap if necessary to satisfy the allocation
 455   // request. If the region is to be used as an old region or for a
 456   // humongous object, set is_old to true. If not, to false.
 457   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 458 
 459   // Initialize a contiguous set of free regions of length num_regions
 460   // and starting at index first so that they appear as a single
 461   // humongous region.
 462   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 463                                                       uint num_regions,
 464                                                       size_t word_size,
 465                                                       AllocationContext_t context);
 466 
 467   // Attempt to allocate a humongous object of the given size. Return
 468   // NULL if unsuccessful.
 469   HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
 470 
 471   // The following two methods, allocate_new_tlab() and
 472   // mem_allocate(), are the two main entry points from the runtime
 473   // into the G1's allocation routines. They have the following
 474   // assumptions:
 475   //
 476   // * They should both be called outside safepoints.
 477   //
 478   // * They should both be called without holding the Heap_lock.
 479   //
 480   // * All allocation requests for new TLABs should go to
 481   //   allocate_new_tlab().
 482   //
 483   // * All non-TLAB allocation requests should go to mem_allocate().
 484   //
 485   // * If either call cannot satisfy the allocation request using the
 486   //   current allocating region, they will try to get a new one. If
 487   //   this fails, they will attempt to do an evacuation pause and
 488   //   retry the allocation.
 489   //
 490   // * If all allocation attempts fail, even after trying to schedule
 491   //   an evacuation pause, allocate_new_tlab() will return NULL,
 492   //   whereas mem_allocate() will attempt a heap expansion and/or
 493   //   schedule a Full GC.
 494   //
 495   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 496   //   should never be called with word_size being humongous. All
 497   //   humongous allocation requests should go to mem_allocate() which
 498   //   will satisfy them with a special path.
 499 
 500   virtual HeapWord* allocate_new_tlab(size_t word_size);
 501 
 502   virtual HeapWord* mem_allocate(size_t word_size,
 503                                  bool*  gc_overhead_limit_was_exceeded);
 504 
 505   // The following three methods take a gc_count_before_ret
 506   // parameter which is used to return the GC count if the method
 507   // returns NULL. Given that we are required to read the GC count
 508   // while holding the Heap_lock, and these paths will take the
 509   // Heap_lock at some point, it's easier to get them to read the GC
 510   // count while holding the Heap_lock before they return NULL instead
 511   // of the caller (namely: mem_allocate()) having to also take the
 512   // Heap_lock just to read the GC count.
 513 
 514   // First-level mutator allocation attempt: try to allocate out of
 515   // the mutator alloc region without taking the Heap_lock. This
 516   // should only be used for non-humongous allocations.
 517   inline HeapWord* attempt_allocation(size_t word_size,
 518                                       unsigned int* gc_count_before_ret,
 519                                       int* gclocker_retry_count_ret);
 520 
 521   // Second-level mutator allocation attempt: take the Heap_lock and
 522   // retry the allocation attempt, potentially scheduling a GC
 523   // pause. This should only be used for non-humongous allocations.
 524   HeapWord* attempt_allocation_slow(size_t word_size,
 525                                     AllocationContext_t context,
 526                                     unsigned int* gc_count_before_ret,
 527                                     int* gclocker_retry_count_ret);
 528 
 529   // Takes the Heap_lock and attempts a humongous allocation. It can
 530   // potentially schedule a GC pause.
 531   HeapWord* attempt_allocation_humongous(size_t word_size,
 532                                          unsigned int* gc_count_before_ret,
 533                                          int* gclocker_retry_count_ret);
 534 
 535   // Allocation attempt that should be called during safepoints (e.g.,
 536   // at the end of a successful GC). expect_null_mutator_alloc_region
 537   // specifies whether the mutator alloc region is expected to be NULL
 538   // or not.
 539   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 540                                             AllocationContext_t context,
 541                                             bool expect_null_mutator_alloc_region);
 542 
 543   // It dirties the cards that cover the block so that so that the post
 544   // write barrier never queues anything when updating objects on this
 545   // block. It is assumed (and in fact we assert) that the block
 546   // belongs to a young region.
 547   inline void dirty_young_block(HeapWord* start, size_t word_size);
 548 
 549   // Allocate blocks during garbage collection. Will ensure an
 550   // allocation region, either by picking one or expanding the
 551   // heap, and then allocate a block of the given size. The block
 552   // may not be a humongous - it must fit into a single heap region.
 553   inline HeapWord* par_allocate_during_gc(InCSetState dest,
 554                                           size_t word_size,
 555                                           AllocationContext_t context);
 556   // Ensure that no further allocations can happen in "r", bearing in mind
 557   // that parallel threads might be attempting allocations.
 558   void par_allocate_remaining_space(HeapRegion* r);
 559 
 560   // Allocation attempt during GC for a survivor object / PLAB.
 561   inline HeapWord* survivor_attempt_allocation(size_t word_size,
 562                                                AllocationContext_t context);
 563 
 564   // Allocation attempt during GC for an old object / PLAB.
 565   inline HeapWord* old_attempt_allocation(size_t word_size,
 566                                           AllocationContext_t context);
 567 
 568   // These methods are the "callbacks" from the G1AllocRegion class.
 569 
 570   // For mutator alloc regions.
 571   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 572   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 573                                    size_t allocated_bytes);
 574 
 575   // For GC alloc regions.
 576   HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
 577                                   InCSetState dest);
 578   void retire_gc_alloc_region(HeapRegion* alloc_region,
 579                               size_t allocated_bytes, InCSetState dest);
 580 
 581   // - if explicit_gc is true, the GC is for a System.gc() or a heap
 582   //   inspection request and should collect the entire heap
 583   // - if clear_all_soft_refs is true, all soft references should be
 584   //   cleared during the GC
 585   // - if explicit_gc is false, word_size describes the allocation that
 586   //   the GC should attempt (at least) to satisfy
 587   // - it returns false if it is unable to do the collection due to the
 588   //   GC locker being active, true otherwise
 589   bool do_collection(bool explicit_gc,
 590                      bool clear_all_soft_refs,
 591                      size_t word_size);
 592 
 593   // Callback from VM_G1CollectFull operation.
 594   // Perform a full collection.
 595   virtual void do_full_collection(bool clear_all_soft_refs);
 596 
 597   // Resize the heap if necessary after a full collection.  If this is
 598   // after a collect-for allocation, "word_size" is the allocation size,
 599   // and will be considered part of the used portion of the heap.
 600   void resize_if_necessary_after_full_collection(size_t word_size);
 601 
 602   // Callback from VM_G1CollectForAllocation operation.
 603   // This function does everything necessary/possible to satisfy a
 604   // failed allocation request (including collection, expansion, etc.)
 605   HeapWord* satisfy_failed_allocation(size_t word_size,
 606                                       AllocationContext_t context,
 607                                       bool* succeeded);
 608 
 609   // Attempting to expand the heap sufficiently
 610   // to support an allocation of the given "word_size".  If
 611   // successful, perform the allocation and return the address of the
 612   // allocated block, or else "NULL".
 613   HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
 614 
 615   // Process any reference objects discovered during
 616   // an incremental evacuation pause.
 617   void process_discovered_references(uint no_of_gc_workers);
 618 
 619   // Enqueue any remaining discovered references
 620   // after processing.
 621   void enqueue_discovered_references(uint no_of_gc_workers);
 622 
 623 public:
 624 
 625   G1Allocator* allocator() {
 626     return _allocator;
 627   }
 628 
 629   G1MonitoringSupport* g1mm() {
 630     assert(_g1mm != NULL, "should have been initialized");
 631     return _g1mm;
 632   }
 633 
 634   // Expand the garbage-first heap by at least the given size (in bytes!).
 635   // Returns true if the heap was expanded by the requested amount;
 636   // false otherwise.
 637   // (Rounds up to a HeapRegion boundary.)
 638   bool expand(size_t expand_bytes);
 639 
 640   // Returns the PLAB statistics for a given destination.
 641   inline PLABStats* alloc_buffer_stats(InCSetState dest);
 642 
 643   // Determines PLAB size for a given destination.
 644   inline size_t desired_plab_sz(InCSetState dest);
 645 
 646   inline AllocationContextStats& allocation_context_stats();
 647 
 648   // Do anything common to GC's.
 649   virtual void gc_prologue(bool full);
 650   virtual void gc_epilogue(bool full);
 651 
 652   inline void set_humongous_is_live(oop obj);
 653 
 654   bool humongous_is_live(uint region) {
 655     return _humongous_is_live.is_live(region);
 656   }
 657 
 658   // Returns whether the given region (which must be a humongous (start) region)
 659   // is to be considered conservatively live regardless of any other conditions.
 660   bool humongous_region_is_always_live(uint index);
 661   // Register the given region to be part of the collection set.
 662   inline void register_humongous_region_with_in_cset_fast_test(uint index);
 663   // Register regions with humongous objects (actually on the start region) in
 664   // the in_cset_fast_test table.
 665   void register_humongous_regions_with_in_cset_fast_test();
 666   // We register a region with the fast "in collection set" test. We
 667   // simply set to true the array slot corresponding to this region.
 668   void register_young_region_with_in_cset_fast_test(HeapRegion* r) {
 669     _in_cset_fast_test.set_in_young(r->hrm_index());
 670   }
 671   void register_old_region_with_in_cset_fast_test(HeapRegion* r) {
 672     _in_cset_fast_test.set_in_old(r->hrm_index());
 673   }
 674 
 675   // This is a fast test on whether a reference points into the
 676   // collection set or not. Assume that the reference
 677   // points into the heap.
 678   inline bool in_cset_fast_test(oop obj);
 679 
 680   void clear_cset_fast_test() {
 681     _in_cset_fast_test.clear();
 682   }
 683 
 684   // This is called at the start of either a concurrent cycle or a Full
 685   // GC to update the number of old marking cycles started.
 686   void increment_old_marking_cycles_started();
 687 
 688   // This is called at the end of either a concurrent cycle or a Full
 689   // GC to update the number of old marking cycles completed. Those two
 690   // can happen in a nested fashion, i.e., we start a concurrent
 691   // cycle, a Full GC happens half-way through it which ends first,
 692   // and then the cycle notices that a Full GC happened and ends
 693   // too. The concurrent parameter is a boolean to help us do a bit
 694   // tighter consistency checking in the method. If concurrent is
 695   // false, the caller is the inner caller in the nesting (i.e., the
 696   // Full GC). If concurrent is true, the caller is the outer caller
 697   // in this nesting (i.e., the concurrent cycle). Further nesting is
 698   // not currently supported. The end of this call also notifies
 699   // the FullGCCount_lock in case a Java thread is waiting for a full
 700   // GC to happen (e.g., it called System.gc() with
 701   // +ExplicitGCInvokesConcurrent).
 702   void increment_old_marking_cycles_completed(bool concurrent);
 703 
 704   unsigned int old_marking_cycles_completed() {
 705     return _old_marking_cycles_completed;
 706   }
 707 
 708   void register_concurrent_cycle_start(const Ticks& start_time);
 709   void register_concurrent_cycle_end();
 710   void trace_heap_after_concurrent_cycle();
 711 
 712   G1YCType yc_type();
 713 
 714   G1HRPrinter* hr_printer() { return &_hr_printer; }
 715 
 716   // Frees a non-humongous region by initializing its contents and
 717   // adding it to the free list that's passed as a parameter (this is
 718   // usually a local list which will be appended to the master free
 719   // list later). The used bytes of freed regions are accumulated in
 720   // pre_used. If par is true, the region's RSet will not be freed
 721   // up. The assumption is that this will be done later.
 722   // The locked parameter indicates if the caller has already taken
 723   // care of proper synchronization. This may allow some optimizations.
 724   void free_region(HeapRegion* hr,
 725                    FreeRegionList* free_list,
 726                    bool par,
 727                    bool locked = false);
 728 
 729   // Frees a humongous region by collapsing it into individual regions
 730   // and calling free_region() for each of them. The freed regions
 731   // will be added to the free list that's passed as a parameter (this
 732   // is usually a local list which will be appended to the master free
 733   // list later). The used bytes of freed regions are accumulated in
 734   // pre_used. If par is true, the region's RSet will not be freed
 735   // up. The assumption is that this will be done later.
 736   void free_humongous_region(HeapRegion* hr,
 737                              FreeRegionList* free_list,
 738                              bool par);
 739 protected:
 740 
 741   // Shrink the garbage-first heap by at most the given size (in bytes!).
 742   // (Rounds down to a HeapRegion boundary.)
 743   virtual void shrink(size_t expand_bytes);
 744   void shrink_helper(size_t expand_bytes);
 745 
 746   #if TASKQUEUE_STATS
 747   static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
 748   void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
 749   void reset_taskqueue_stats();
 750   #endif // TASKQUEUE_STATS
 751 
 752   // Schedule the VM operation that will do an evacuation pause to
 753   // satisfy an allocation request of word_size. *succeeded will
 754   // return whether the VM operation was successful (it did do an
 755   // evacuation pause) or not (another thread beat us to it or the GC
 756   // locker was active). Given that we should not be holding the
 757   // Heap_lock when we enter this method, we will pass the
 758   // gc_count_before (i.e., total_collections()) as a parameter since
 759   // it has to be read while holding the Heap_lock. Currently, both
 760   // methods that call do_collection_pause() release the Heap_lock
 761   // before the call, so it's easy to read gc_count_before just before.
 762   HeapWord* do_collection_pause(size_t         word_size,
 763                                 unsigned int   gc_count_before,
 764                                 bool*          succeeded,
 765                                 GCCause::Cause gc_cause);
 766 
 767   // The guts of the incremental collection pause, executed by the vm
 768   // thread. It returns false if it is unable to do the collection due
 769   // to the GC locker being active, true otherwise
 770   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 771 
 772   // Actually do the work of evacuating the collection set.
 773   void evacuate_collection_set(EvacuationInfo& evacuation_info);
 774 
 775   // The g1 remembered set of the heap.
 776   G1RemSet* _g1_rem_set;
 777 
 778   // A set of cards that cover the objects for which the Rsets should be updated
 779   // concurrently after the collection.
 780   DirtyCardQueueSet _dirty_card_queue_set;
 781 
 782   // The closure used to refine a single card.
 783   RefineCardTableEntryClosure* _refine_cte_cl;
 784 
 785   // A function to check the consistency of dirty card logs.
 786   void check_ct_logs_at_safepoint();
 787 
 788   // A DirtyCardQueueSet that is used to hold cards that contain
 789   // references into the current collection set. This is used to
 790   // update the remembered sets of the regions in the collection
 791   // set in the event of an evacuation failure.
 792   DirtyCardQueueSet _into_cset_dirty_card_queue_set;
 793 
 794   // After a collection pause, make the regions in the CS into free
 795   // regions.
 796   void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
 797 
 798   // Abandon the current collection set without recording policy
 799   // statistics or updating free lists.
 800   void abandon_collection_set(HeapRegion* cs_head);
 801 
 802   // The concurrent marker (and the thread it runs in.)
 803   ConcurrentMark* _cm;
 804   ConcurrentMarkThread* _cmThread;
 805   bool _mark_in_progress;
 806 
 807   // The concurrent refiner.
 808   ConcurrentG1Refine* _cg1r;
 809 
 810   // The parallel task queues
 811   RefToScanQueueSet *_task_queues;
 812 
 813   // True iff a evacuation has failed in the current collection.
 814   bool _evacuation_failed;
 815 
 816   EvacuationFailedInfo* _evacuation_failed_info_array;
 817 
 818   // Failed evacuations cause some logical from-space objects to have
 819   // forwarding pointers to themselves.  Reset them.
 820   void remove_self_forwarding_pointers();
 821 
 822   // Together, these store an object with a preserved mark, and its mark value.
 823   Stack<oop, mtGC>     _objs_with_preserved_marks;
 824   Stack<markOop, mtGC> _preserved_marks_of_objs;
 825 
 826   // Preserve the mark of "obj", if necessary, in preparation for its mark
 827   // word being overwritten with a self-forwarding-pointer.
 828   void preserve_mark_if_necessary(oop obj, markOop m);
 829 
 830   // The stack of evac-failure objects left to be scanned.
 831   GrowableArray<oop>*    _evac_failure_scan_stack;
 832   // The closure to apply to evac-failure objects.
 833 
 834   OopsInHeapRegionClosure* _evac_failure_closure;
 835   // Set the field above.
 836   void
 837   set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
 838     _evac_failure_closure = evac_failure_closure;
 839   }
 840 
 841   // Push "obj" on the scan stack.
 842   void push_on_evac_failure_scan_stack(oop obj);
 843   // Process scan stack entries until the stack is empty.
 844   void drain_evac_failure_scan_stack();
 845   // True iff an invocation of "drain_scan_stack" is in progress; to
 846   // prevent unnecessary recursion.
 847   bool _drain_in_progress;
 848 
 849   // Do any necessary initialization for evacuation-failure handling.
 850   // "cl" is the closure that will be used to process evac-failure
 851   // objects.
 852   void init_for_evac_failure(OopsInHeapRegionClosure* cl);
 853   // Do any necessary cleanup for evacuation-failure handling data
 854   // structures.
 855   void finalize_for_evac_failure();
 856 
 857   // An attempt to evacuate "obj" has failed; take necessary steps.
 858   oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
 859   void handle_evacuation_failure_common(oop obj, markOop m);
 860 
 861 #ifndef PRODUCT
 862   // Support for forcing evacuation failures. Analogous to
 863   // PromotionFailureALot for the other collectors.
 864 
 865   // Records whether G1EvacuationFailureALot should be in effect
 866   // for the current GC
 867   bool _evacuation_failure_alot_for_current_gc;
 868 
 869   // Used to record the GC number for interval checking when
 870   // determining whether G1EvaucationFailureALot is in effect
 871   // for the current GC.
 872   size_t _evacuation_failure_alot_gc_number;
 873 
 874   // Count of the number of evacuations between failures.
 875   volatile size_t _evacuation_failure_alot_count;
 876 
 877   // Set whether G1EvacuationFailureALot should be in effect
 878   // for the current GC (based upon the type of GC and which
 879   // command line flags are set);
 880   inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
 881                                                   bool during_initial_mark,
 882                                                   bool during_marking);
 883 
 884   inline void set_evacuation_failure_alot_for_current_gc();
 885 
 886   // Return true if it's time to cause an evacuation failure.
 887   inline bool evacuation_should_fail();
 888 
 889   // Reset the G1EvacuationFailureALot counters.  Should be called at
 890   // the end of an evacuation pause in which an evacuation failure occurred.
 891   inline void reset_evacuation_should_fail();
 892 #endif // !PRODUCT
 893 
 894   // ("Weak") Reference processing support.
 895   //
 896   // G1 has 2 instances of the reference processor class. One
 897   // (_ref_processor_cm) handles reference object discovery
 898   // and subsequent processing during concurrent marking cycles.
 899   //
 900   // The other (_ref_processor_stw) handles reference object
 901   // discovery and processing during full GCs and incremental
 902   // evacuation pauses.
 903   //
 904   // During an incremental pause, reference discovery will be
 905   // temporarily disabled for _ref_processor_cm and will be
 906   // enabled for _ref_processor_stw. At the end of the evacuation
 907   // pause references discovered by _ref_processor_stw will be
 908   // processed and discovery will be disabled. The previous
 909   // setting for reference object discovery for _ref_processor_cm
 910   // will be re-instated.
 911   //
 912   // At the start of marking:
 913   //  * Discovery by the CM ref processor is verified to be inactive
 914   //    and it's discovered lists are empty.
 915   //  * Discovery by the CM ref processor is then enabled.
 916   //
 917   // At the end of marking:
 918   //  * Any references on the CM ref processor's discovered
 919   //    lists are processed (possibly MT).
 920   //
 921   // At the start of full GC we:
 922   //  * Disable discovery by the CM ref processor and
 923   //    empty CM ref processor's discovered lists
 924   //    (without processing any entries).
 925   //  * Verify that the STW ref processor is inactive and it's
 926   //    discovered lists are empty.
 927   //  * Temporarily set STW ref processor discovery as single threaded.
 928   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 929   //    field.
 930   //  * Finally enable discovery by the STW ref processor.
 931   //
 932   // The STW ref processor is used to record any discovered
 933   // references during the full GC.
 934   //
 935   // At the end of a full GC we:
 936   //  * Enqueue any reference objects discovered by the STW ref processor
 937   //    that have non-live referents. This has the side-effect of
 938   //    making the STW ref processor inactive by disabling discovery.
 939   //  * Verify that the CM ref processor is still inactive
 940   //    and no references have been placed on it's discovered
 941   //    lists (also checked as a precondition during initial marking).
 942 
 943   // The (stw) reference processor...
 944   ReferenceProcessor* _ref_processor_stw;
 945 
 946   STWGCTimer* _gc_timer_stw;
 947   ConcurrentGCTimer* _gc_timer_cm;
 948 
 949   G1OldTracer* _gc_tracer_cm;
 950   G1NewTracer* _gc_tracer_stw;
 951 
 952   // During reference object discovery, the _is_alive_non_header
 953   // closure (if non-null) is applied to the referent object to
 954   // determine whether the referent is live. If so then the
 955   // reference object does not need to be 'discovered' and can
 956   // be treated as a regular oop. This has the benefit of reducing
 957   // the number of 'discovered' reference objects that need to
 958   // be processed.
 959   //
 960   // Instance of the is_alive closure for embedding into the
 961   // STW reference processor as the _is_alive_non_header field.
 962   // Supplying a value for the _is_alive_non_header field is
 963   // optional but doing so prevents unnecessary additions to
 964   // the discovered lists during reference discovery.
 965   G1STWIsAliveClosure _is_alive_closure_stw;
 966 
 967   // The (concurrent marking) reference processor...
 968   ReferenceProcessor* _ref_processor_cm;
 969 
 970   // Instance of the concurrent mark is_alive closure for embedding
 971   // into the Concurrent Marking reference processor as the
 972   // _is_alive_non_header field. Supplying a value for the
 973   // _is_alive_non_header field is optional but doing so prevents
 974   // unnecessary additions to the discovered lists during reference
 975   // discovery.
 976   G1CMIsAliveClosure _is_alive_closure_cm;
 977 
 978   // Cache used by G1CollectedHeap::start_cset_region_for_worker().
 979   HeapRegion** _worker_cset_start_region;
 980 
 981   // Time stamp to validate the regions recorded in the cache
 982   // used by G1CollectedHeap::start_cset_region_for_worker().
 983   // The heap region entry for a given worker is valid iff
 984   // the associated time stamp value matches the current value
 985   // of G1CollectedHeap::_gc_time_stamp.
 986   unsigned int* _worker_cset_start_region_time_stamp;
 987 
 988   volatile bool _free_regions_coming;
 989 
 990 public:
 991 
 992   void set_refine_cte_cl_concurrency(bool concurrent);
 993 
 994   RefToScanQueue *task_queue(int i) const;
 995 
 996   // A set of cards where updates happened during the GC
 997   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 998 
 999   // A DirtyCardQueueSet that is used to hold cards that contain
1000   // references into the current collection set. This is used to
1001   // update the remembered sets of the regions in the collection
1002   // set in the event of an evacuation failure.
1003   DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1004         { return _into_cset_dirty_card_queue_set; }
1005 
1006   // Create a G1CollectedHeap with the specified policy.
1007   // Must call the initialize method afterwards.
1008   // May not return if something goes wrong.
1009   G1CollectedHeap(G1CollectorPolicy* policy);
1010 
1011   // Initialize the G1CollectedHeap to have the initial and
1012   // maximum sizes and remembered and barrier sets
1013   // specified by the policy object.
1014   jint initialize();
1015 
1016   virtual void stop();
1017 
1018   // Return the (conservative) maximum heap alignment for any G1 heap
1019   static size_t conservative_max_heap_alignment();
1020 
1021   // Initialize weak reference processing.
1022   virtual void ref_processing_init();
1023 
1024   // Explicitly import set_par_threads into this scope
1025   using SharedHeap::set_par_threads;
1026   // Set _n_par_threads according to a policy TBD.
1027   void set_par_threads();
1028 
1029   virtual CollectedHeap::Name kind() const {
1030     return CollectedHeap::G1CollectedHeap;
1031   }
1032 
1033   // The current policy object for the collector.
1034   G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1035 
1036   virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1037 
1038   // Adaptive size policy.  No such thing for g1.
1039   virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1040 
1041   // The rem set and barrier set.
1042   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1043 
1044   unsigned get_gc_time_stamp() {
1045     return _gc_time_stamp;
1046   }
1047 
1048   inline void reset_gc_time_stamp();
1049 
1050   void check_gc_time_stamps() PRODUCT_RETURN;
1051 
1052   inline void increment_gc_time_stamp();
1053 
1054   // Reset the given region's GC timestamp. If it's starts humongous,
1055   // also reset the GC timestamp of its corresponding
1056   // continues humongous regions too.
1057   void reset_gc_time_stamps(HeapRegion* hr);
1058 
1059   void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1060                                   DirtyCardQueue* into_cset_dcq,
1061                                   bool concurrent, uint worker_i);
1062 
1063   // The shared block offset table array.
1064   G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1065 
1066   // Reference Processing accessors
1067 
1068   // The STW reference processor....
1069   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1070 
1071   // The Concurrent Marking reference processor...
1072   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1073 
1074   ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1075   G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1076 
1077   virtual size_t capacity() const;
1078   virtual size_t used() const;
1079   // This should be called when we're not holding the heap lock. The
1080   // result might be a bit inaccurate.
1081   size_t used_unlocked() const;
1082   size_t recalculate_used() const;
1083 
1084   // These virtual functions do the actual allocation.
1085   // Some heaps may offer a contiguous region for shared non-blocking
1086   // allocation, via inlined code (by exporting the address of the top and
1087   // end fields defining the extent of the contiguous allocation region.)
1088   // But G1CollectedHeap doesn't yet support this.
1089 
1090   virtual bool is_maximal_no_gc() const {
1091     return _hrm.available() == 0;
1092   }
1093 
1094   // The current number of regions in the heap.
1095   uint num_regions() const { return _hrm.length(); }
1096 
1097   // The max number of regions in the heap.
1098   uint max_regions() const { return _hrm.max_length(); }
1099 
1100   // The number of regions that are completely free.
1101   uint num_free_regions() const { return _hrm.num_free_regions(); }
1102 
1103   // The number of regions that are not completely free.
1104   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1105 
1106   void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1107   void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1108   void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1109   void verify_dirty_young_regions() PRODUCT_RETURN;
1110 
1111 #ifndef PRODUCT
1112   // Make sure that the given bitmap has no marked objects in the
1113   // range [from,limit). If it does, print an error message and return
1114   // false. Otherwise, just return true. bitmap_name should be "prev"
1115   // or "next".
1116   bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1117                                 HeapWord* from, HeapWord* limit);
1118 
1119   // Verify that the prev / next bitmap range [tams,end) for the given
1120   // region has no marks. Return true if all is well, false if errors
1121   // are detected.
1122   bool verify_bitmaps(const char* caller, HeapRegion* hr);
1123 #endif // PRODUCT
1124 
1125   // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1126   // the given region do not have any spurious marks. If errors are
1127   // detected, print appropriate error messages and crash.
1128   void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1129 
1130   // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1131   // have any spurious marks. If errors are detected, print
1132   // appropriate error messages and crash.
1133   void check_bitmaps(const char* caller) PRODUCT_RETURN;
1134 
1135   // Do sanity check on the contents of the in-cset fast test table.
1136   bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1137 
1138   // verify_region_sets() performs verification over the region
1139   // lists. It will be compiled in the product code to be used when
1140   // necessary (i.e., during heap verification).
1141   void verify_region_sets();
1142 
1143   // verify_region_sets_optional() is planted in the code for
1144   // list verification in non-product builds (and it can be enabled in
1145   // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1146 #if HEAP_REGION_SET_FORCE_VERIFY
1147   void verify_region_sets_optional() {
1148     verify_region_sets();
1149   }
1150 #else // HEAP_REGION_SET_FORCE_VERIFY
1151   void verify_region_sets_optional() { }
1152 #endif // HEAP_REGION_SET_FORCE_VERIFY
1153 
1154 #ifdef ASSERT
1155   bool is_on_master_free_list(HeapRegion* hr) {
1156     return _hrm.is_free(hr);
1157   }
1158 #endif // ASSERT
1159 
1160   // Wrapper for the region list operations that can be called from
1161   // methods outside this class.
1162 
1163   void secondary_free_list_add(FreeRegionList* list) {
1164     _secondary_free_list.add_ordered(list);
1165   }
1166 
1167   void append_secondary_free_list() {
1168     _hrm.insert_list_into_free_list(&_secondary_free_list);
1169   }
1170 
1171   void append_secondary_free_list_if_not_empty_with_lock() {
1172     // If the secondary free list looks empty there's no reason to
1173     // take the lock and then try to append it.
1174     if (!_secondary_free_list.is_empty()) {
1175       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1176       append_secondary_free_list();
1177     }
1178   }
1179 
1180   inline void old_set_remove(HeapRegion* hr);
1181 
1182   size_t non_young_capacity_bytes() {
1183     return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1184   }
1185 
1186   void set_free_regions_coming();
1187   void reset_free_regions_coming();
1188   bool free_regions_coming() { return _free_regions_coming; }
1189   void wait_while_free_regions_coming();
1190 
1191   // Determine whether the given region is one that we are using as an
1192   // old GC alloc region.
1193   bool is_old_gc_alloc_region(HeapRegion* hr) {
1194     return _allocator->is_retained_old_region(hr);
1195   }
1196 
1197   // Perform a collection of the heap; intended for use in implementing
1198   // "System.gc".  This probably implies as full a collection as the
1199   // "CollectedHeap" supports.
1200   virtual void collect(GCCause::Cause cause);
1201 
1202   // The same as above but assume that the caller holds the Heap_lock.
1203   void collect_locked(GCCause::Cause cause);
1204 
1205   virtual bool copy_allocation_context_stats(const jint* contexts,
1206                                              jlong* totals,
1207                                              jbyte* accuracy,
1208                                              jint len);
1209 
1210   // True iff an evacuation has failed in the most-recent collection.
1211   bool evacuation_failed() { return _evacuation_failed; }
1212 
1213   void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1214   void prepend_to_freelist(FreeRegionList* list);
1215   void decrement_summary_bytes(size_t bytes);
1216 
1217   // Returns "TRUE" iff "p" points into the committed areas of the heap.
1218   virtual bool is_in(const void* p) const;
1219 #ifdef ASSERT
1220   // Returns whether p is in one of the available areas of the heap. Slow but
1221   // extensive version.
1222   bool is_in_exact(const void* p) const;
1223 #endif
1224 
1225   // Return "TRUE" iff the given object address is within the collection
1226   // set. Slow implementation.
1227   inline bool obj_in_cs(oop obj);
1228 
1229   inline bool is_in_cset(oop obj);
1230 
1231   inline bool is_in_cset_or_humongous(const oop obj);
1232 
1233  private:
1234   // This array is used for a quick test on whether a reference points into
1235   // the collection set or not. Each of the array's elements denotes whether the
1236   // corresponding region is in the collection set or not.
1237   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1238 
1239  public:
1240 
1241   inline InCSetState in_cset_state(const oop obj);
1242 
1243   // Return "TRUE" iff the given object address is in the reserved
1244   // region of g1.
1245   bool is_in_g1_reserved(const void* p) const {
1246     return _hrm.reserved().contains(p);
1247   }
1248 
1249   // Returns a MemRegion that corresponds to the space that has been
1250   // reserved for the heap
1251   MemRegion g1_reserved() const {
1252     return _hrm.reserved();
1253   }
1254 
1255   virtual bool is_in_closed_subset(const void* p) const;
1256 
1257   G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1258     return (G1SATBCardTableLoggingModRefBS*) barrier_set();
1259   }
1260 
1261   // This resets the card table to all zeros.  It is used after
1262   // a collection pause which used the card table to claim cards.
1263   void cleanUpCardTable();
1264 
1265   // Iteration functions.
1266 
1267   // Iterate over all the ref-containing fields of all objects, calling
1268   // "cl.do_oop" on each.
1269   virtual void oop_iterate(ExtendedOopClosure* cl);
1270 
1271   // Iterate over all objects, calling "cl.do_object" on each.
1272   virtual void object_iterate(ObjectClosure* cl);
1273 
1274   virtual void safe_object_iterate(ObjectClosure* cl) {
1275     object_iterate(cl);
1276   }
1277 
1278   // Iterate over all spaces in use in the heap, in ascending address order.
1279   virtual void space_iterate(SpaceClosure* cl);
1280 
1281   // Iterate over heap regions, in address order, terminating the
1282   // iteration early if the "doHeapRegion" method returns "true".
1283   void heap_region_iterate(HeapRegionClosure* blk) const;
1284 
1285   // Return the region with the given index. It assumes the index is valid.
1286   inline HeapRegion* region_at(uint index) const;
1287 
1288   // Calculate the region index of the given address. Given address must be
1289   // within the heap.
1290   inline uint addr_to_region(HeapWord* addr) const;
1291 
1292   inline HeapWord* bottom_addr_for_region(uint index) const;
1293 
1294   // Divide the heap region sequence into "chunks" of some size (the number
1295   // of regions divided by the number of parallel threads times some
1296   // overpartition factor, currently 4).  Assumes that this will be called
1297   // in parallel by ParallelGCThreads worker threads with discinct worker
1298   // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1299   // calls will use the same "claim_value", and that that claim value is
1300   // different from the claim_value of any heap region before the start of
1301   // the iteration.  Applies "blk->doHeapRegion" to each of the regions, by
1302   // attempting to claim the first region in each chunk, and, if
1303   // successful, applying the closure to each region in the chunk (and
1304   // setting the claim value of the second and subsequent regions of the
1305   // chunk.)  For now requires that "doHeapRegion" always returns "false",
1306   // i.e., that a closure never attempt to abort a traversal.
1307   void heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1308                                        uint worker_id,
1309                                        uint num_workers,
1310                                        jint claim_value) const;
1311 
1312   // It resets all the region claim values to the default.
1313   void reset_heap_region_claim_values();
1314 
1315   // Resets the claim values of regions in the current
1316   // collection set to the default.
1317   void reset_cset_heap_region_claim_values();
1318 
1319 #ifdef ASSERT
1320   bool check_heap_region_claim_values(jint claim_value);
1321 
1322   // Same as the routine above but only checks regions in the
1323   // current collection set.
1324   bool check_cset_heap_region_claim_values(jint claim_value);
1325 #endif // ASSERT
1326 
1327   // Clear the cached cset start regions and (more importantly)
1328   // the time stamps. Called when we reset the GC time stamp.
1329   void clear_cset_start_regions();
1330 
1331   // Given the id of a worker, obtain or calculate a suitable
1332   // starting region for iterating over the current collection set.
1333   HeapRegion* start_cset_region_for_worker(uint worker_i);
1334 
1335   // Iterate over the regions (if any) in the current collection set.
1336   void collection_set_iterate(HeapRegionClosure* blk);
1337 
1338   // As above but starting from region r
1339   void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1340 
1341   HeapRegion* next_compaction_region(const HeapRegion* from) const;
1342 
1343   // A CollectedHeap will contain some number of spaces.  This finds the
1344   // space containing a given address, or else returns NULL.
1345   virtual Space* space_containing(const void* addr) const;
1346 
1347   // Returns the HeapRegion that contains addr. addr must not be NULL.
1348   template <class T>
1349   inline HeapRegion* heap_region_containing_raw(const T addr) const;
1350 
1351   // Returns the HeapRegion that contains addr. addr must not be NULL.
1352   // If addr is within a humongous continues region, it returns its humongous start region.
1353   template <class T>
1354   inline HeapRegion* heap_region_containing(const T addr) const;
1355 
1356   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1357   // each address in the (reserved) heap is a member of exactly
1358   // one block.  The defining characteristic of a block is that it is
1359   // possible to find its size, and thus to progress forward to the next
1360   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1361   // represent Java objects, or they might be free blocks in a
1362   // free-list-based heap (or subheap), as long as the two kinds are
1363   // distinguishable and the size of each is determinable.
1364 
1365   // Returns the address of the start of the "block" that contains the
1366   // address "addr".  We say "blocks" instead of "object" since some heaps
1367   // may not pack objects densely; a chunk may either be an object or a
1368   // non-object.
1369   virtual HeapWord* block_start(const void* addr) const;
1370 
1371   // Requires "addr" to be the start of a chunk, and returns its size.
1372   // "addr + size" is required to be the start of a new chunk, or the end
1373   // of the active area of the heap.
1374   virtual size_t block_size(const HeapWord* addr) const;
1375 
1376   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1377   // the block is an object.
1378   virtual bool block_is_obj(const HeapWord* addr) const;
1379 
1380   // Does this heap support heap inspection? (+PrintClassHistogram)
1381   virtual bool supports_heap_inspection() const { return true; }
1382 
1383   // Section on thread-local allocation buffers (TLABs)
1384   // See CollectedHeap for semantics.
1385 
1386   bool supports_tlab_allocation() const;
1387   size_t tlab_capacity(Thread* ignored) const;
1388   size_t tlab_used(Thread* ignored) const;
1389   size_t max_tlab_size() const;
1390   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1391 
1392   // Can a compiler initialize a new object without store barriers?
1393   // This permission only extends from the creation of a new object
1394   // via a TLAB up to the first subsequent safepoint. If such permission
1395   // is granted for this heap type, the compiler promises to call
1396   // defer_store_barrier() below on any slow path allocation of
1397   // a new object for which such initializing store barriers will
1398   // have been elided. G1, like CMS, allows this, but should be
1399   // ready to provide a compensating write barrier as necessary
1400   // if that storage came out of a non-young region. The efficiency
1401   // of this implementation depends crucially on being able to
1402   // answer very efficiently in constant time whether a piece of
1403   // storage in the heap comes from a young region or not.
1404   // See ReduceInitialCardMarks.
1405   virtual bool can_elide_tlab_store_barriers() const {
1406     return true;
1407   }
1408 
1409   virtual bool card_mark_must_follow_store() const {
1410     return true;
1411   }
1412 
1413   inline bool is_in_young(const oop obj);
1414 
1415 #ifdef ASSERT
1416   virtual bool is_in_partial_collection(const void* p);
1417 #endif
1418 
1419   virtual bool is_scavengable(const void* addr);
1420 
1421   // We don't need barriers for initializing stores to objects
1422   // in the young gen: for the SATB pre-barrier, there is no
1423   // pre-value that needs to be remembered; for the remembered-set
1424   // update logging post-barrier, we don't maintain remembered set
1425   // information for young gen objects.
1426   virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1427 
1428   // Returns "true" iff the given word_size is "very large".
1429   static bool isHumongous(size_t word_size) {
1430     // Note this has to be strictly greater-than as the TLABs
1431     // are capped at the humongous thresold and we want to
1432     // ensure that we don't try to allocate a TLAB as
1433     // humongous and that we don't allocate a humongous
1434     // object in a TLAB.
1435     return word_size > _humongous_object_threshold_in_words;
1436   }
1437 
1438   // Update mod union table with the set of dirty cards.
1439   void updateModUnion();
1440 
1441   // Set the mod union bits corresponding to the given memRegion.  Note
1442   // that this is always a safe operation, since it doesn't clear any
1443   // bits.
1444   void markModUnionRange(MemRegion mr);
1445 
1446   // Records the fact that a marking phase is no longer in progress.
1447   void set_marking_complete() {
1448     _mark_in_progress = false;
1449   }
1450   void set_marking_started() {
1451     _mark_in_progress = true;
1452   }
1453   bool mark_in_progress() {
1454     return _mark_in_progress;
1455   }
1456 
1457   // Print the maximum heap capacity.
1458   virtual size_t max_capacity() const;
1459 
1460   virtual jlong millis_since_last_gc();
1461 
1462 
1463   // Convenience function to be used in situations where the heap type can be
1464   // asserted to be this type.
1465   static G1CollectedHeap* heap();
1466 
1467   void set_region_short_lived_locked(HeapRegion* hr);
1468   // add appropriate methods for any other surv rate groups
1469 
1470   YoungList* young_list() const { return _young_list; }
1471 
1472   // debugging
1473   bool check_young_list_well_formed() {
1474     return _young_list->check_list_well_formed();
1475   }
1476 
1477   bool check_young_list_empty(bool check_heap,
1478                               bool check_sample = true);
1479 
1480   // *** Stuff related to concurrent marking.  It's not clear to me that so
1481   // many of these need to be public.
1482 
1483   // The functions below are helper functions that a subclass of
1484   // "CollectedHeap" can use in the implementation of its virtual
1485   // functions.
1486   // This performs a concurrent marking of the live objects in a
1487   // bitmap off to the side.
1488   void doConcurrentMark();
1489 
1490   bool isMarkedPrev(oop obj) const;
1491   bool isMarkedNext(oop obj) const;
1492 
1493   // Determine if an object is dead, given the object and also
1494   // the region to which the object belongs. An object is dead
1495   // iff a) it was not allocated since the last mark and b) it
1496   // is not marked.
1497   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1498     return
1499       !hr->obj_allocated_since_prev_marking(obj) &&
1500       !isMarkedPrev(obj);
1501   }
1502 
1503   // This function returns true when an object has been
1504   // around since the previous marking and hasn't yet
1505   // been marked during this marking.
1506   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1507     return
1508       !hr->obj_allocated_since_next_marking(obj) &&
1509       !isMarkedNext(obj);
1510   }
1511 
1512   // Determine if an object is dead, given only the object itself.
1513   // This will find the region to which the object belongs and
1514   // then call the region version of the same function.
1515 
1516   // Added if it is NULL it isn't dead.
1517 
1518   inline bool is_obj_dead(const oop obj) const;
1519 
1520   inline bool is_obj_ill(const oop obj) const;
1521 
1522   bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1523   HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1524   bool is_marked(oop obj, VerifyOption vo);
1525   const char* top_at_mark_start_str(VerifyOption vo);
1526 
1527   ConcurrentMark* concurrent_mark() const { return _cm; }
1528 
1529   // Refinement
1530 
1531   ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1532 
1533   // The dirty cards region list is used to record a subset of regions
1534   // whose cards need clearing. The list if populated during the
1535   // remembered set scanning and drained during the card table
1536   // cleanup. Although the methods are reentrant, population/draining
1537   // phases must not overlap. For synchronization purposes the last
1538   // element on the list points to itself.
1539   HeapRegion* _dirty_cards_region_list;
1540   void push_dirty_cards_region(HeapRegion* hr);
1541   HeapRegion* pop_dirty_cards_region();
1542 
1543   // Optimized nmethod scanning support routines
1544 
1545   // Register the given nmethod with the G1 heap
1546   virtual void register_nmethod(nmethod* nm);
1547 
1548   // Unregister the given nmethod from the G1 heap
1549   virtual void unregister_nmethod(nmethod* nm);
1550 
1551   // Free up superfluous code root memory.
1552   void purge_code_root_memory();
1553 
1554   // Rebuild the stong code root lists for each region
1555   // after a full GC
1556   void rebuild_strong_code_roots();
1557 
1558   // Delete entries for dead interned string and clean up unreferenced symbols
1559   // in symbol table, possibly in parallel.
1560   void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1561 
1562   // Parallel phase of unloading/cleaning after G1 concurrent mark.
1563   void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1564 
1565   // Redirty logged cards in the refinement queue.
1566   void redirty_logged_cards();
1567   // Verification
1568 
1569   // The following is just to alert the verification code
1570   // that a full collection has occurred and that the
1571   // remembered sets are no longer up to date.
1572   bool _full_collection;
1573   void set_full_collection() { _full_collection = true;}
1574   void clear_full_collection() {_full_collection = false;}
1575   bool full_collection() {return _full_collection;}
1576 
1577   // Perform any cleanup actions necessary before allowing a verification.
1578   virtual void prepare_for_verify();
1579 
1580   // Perform verification.
1581 
1582   // vo == UsePrevMarking  -> use "prev" marking information,
1583   // vo == UseNextMarking -> use "next" marking information
1584   // vo == UseMarkWord    -> use the mark word in the object header
1585   //
1586   // NOTE: Only the "prev" marking information is guaranteed to be
1587   // consistent most of the time, so most calls to this should use
1588   // vo == UsePrevMarking.
1589   // Currently, there is only one case where this is called with
1590   // vo == UseNextMarking, which is to verify the "next" marking
1591   // information at the end of remark.
1592   // Currently there is only one place where this is called with
1593   // vo == UseMarkWord, which is to verify the marking during a
1594   // full GC.
1595   void verify(bool silent, VerifyOption vo);
1596 
1597   // Override; it uses the "prev" marking information
1598   virtual void verify(bool silent);
1599 
1600   // The methods below are here for convenience and dispatch the
1601   // appropriate method depending on value of the given VerifyOption
1602   // parameter. The values for that parameter, and their meanings,
1603   // are the same as those above.
1604 
1605   bool is_obj_dead_cond(const oop obj,
1606                         const HeapRegion* hr,
1607                         const VerifyOption vo) const;
1608 
1609   bool is_obj_dead_cond(const oop obj,
1610                         const VerifyOption vo) const;
1611 
1612   // Printing
1613 
1614   virtual void print_on(outputStream* st) const;
1615   virtual void print_extended_on(outputStream* st) const;
1616   virtual void print_on_error(outputStream* st) const;
1617 
1618   virtual void print_gc_threads_on(outputStream* st) const;
1619   virtual void gc_threads_do(ThreadClosure* tc) const;
1620 
1621   // Override
1622   void print_tracing_info() const;
1623 
1624   // The following two methods are helpful for debugging RSet issues.
1625   void print_cset_rsets() PRODUCT_RETURN;
1626   void print_all_rsets() PRODUCT_RETURN;
1627 
1628 public:
1629   size_t pending_card_num();
1630   size_t cards_scanned();
1631 
1632 protected:
1633   size_t _max_heap_capacity;
1634 };
1635 
1636 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP