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   6  * under the terms of the GNU General Public License version 2 only, as
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  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  24 
  25 #ifndef SHARE_GC_G1_G1COLLECTEDHEAP_HPP
  26 #define SHARE_GC_G1_G1COLLECTEDHEAP_HPP
  27 
  28 #include "gc/g1/g1BarrierSet.hpp"
  29 #include "gc/g1/g1BiasedArray.hpp"
  30 #include "gc/g1/g1CardTable.hpp"
  31 #include "gc/g1/g1CollectionSet.hpp"
  32 #include "gc/g1/g1CollectorState.hpp"
  33 #include "gc/g1/g1ConcurrentMark.hpp"
  34 #include "gc/g1/g1DirtyCardQueue.hpp"
  35 #include "gc/g1/g1EdenRegions.hpp"
  36 #include "gc/g1/g1EvacFailure.hpp"
  37 #include "gc/g1/g1EvacStats.hpp"
  38 #include "gc/g1/g1EvacuationInfo.hpp"
  39 #include "gc/g1/g1GCPhaseTimes.hpp"
  40 #include "gc/g1/g1HeapTransition.hpp"
  41 #include "gc/g1/g1HeapVerifier.hpp"
  42 #include "gc/g1/g1HRPrinter.hpp"
  43 #include "gc/g1/g1InCSetState.hpp"
  44 #include "gc/g1/g1MonitoringSupport.hpp"
  45 #include "gc/g1/g1SurvivorRegions.hpp"
  46 #include "gc/g1/g1YCTypes.hpp"
  47 #include "gc/g1/heapRegionManager.hpp"
  48 #include "gc/g1/heapRegionSet.hpp"
  49 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
  50 #include "gc/shared/barrierSet.hpp"
  51 #include "gc/shared/collectedHeap.hpp"
  52 #include "gc/shared/gcHeapSummary.hpp"
  53 #include "gc/shared/plab.hpp"
  54 #include "gc/shared/preservedMarks.hpp"
  55 #include "gc/shared/softRefPolicy.hpp"
  56 #include "memory/memRegion.hpp"
  57 #include "utilities/stack.hpp"
  58 
  59 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  60 // It uses the "Garbage First" heap organization and algorithm, which
  61 // may combine concurrent marking with parallel, incremental compaction of
  62 // heap subsets that will yield large amounts of garbage.
  63 
  64 // Forward declarations
  65 class HeapRegion;
  66 class GenerationSpec;
  67 class G1ParScanThreadState;
  68 class G1ParScanThreadStateSet;
  69 class G1ParScanThreadState;
  70 class MemoryPool;
  71 class MemoryManager;
  72 class ObjectClosure;
  73 class SpaceClosure;
  74 class CompactibleSpaceClosure;
  75 class Space;
  76 class G1CollectionSet;
  77 class G1CollectorPolicy;
  78 class G1Policy;
  79 class G1HotCardCache;
  80 class G1RemSet;
  81 class G1YoungRemSetSamplingThread;
  82 class HeapRegionRemSetIterator;
  83 class G1ConcurrentMark;
  84 class G1ConcurrentMarkThread;
  85 class G1ConcurrentRefine;
  86 class GenerationCounters;
  87 class STWGCTimer;
  88 class G1NewTracer;
  89 class EvacuationFailedInfo;
  90 class nmethod;
  91 class WorkGang;
  92 class G1Allocator;
  93 class G1ArchiveAllocator;
  94 class G1FullGCScope;
  95 class G1HeapVerifier;
  96 class G1HeapSizingPolicy;
  97 class G1HeapSummary;
  98 class G1EvacSummary;
  99 
 100 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
 101 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
 102 
 103 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
 104 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
 105 
 106 // The G1 STW is alive closure.
 107 // An instance is embedded into the G1CH and used as the
 108 // (optional) _is_alive_non_header closure in the STW
 109 // reference processor. It is also extensively used during
 110 // reference processing during STW evacuation pauses.
 111 class G1STWIsAliveClosure : public BoolObjectClosure {
 112   G1CollectedHeap* _g1h;
 113 public:
 114   G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
 115   bool do_object_b(oop p);
 116 };
 117 
 118 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
 119   G1CollectedHeap* _g1h;
 120 public:
 121   G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
 122   bool do_object_b(oop p);
 123 };
 124 
 125 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 126  private:
 127   void reset_from_card_cache(uint start_idx, size_t num_regions);
 128  public:
 129   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 130 };
 131 
 132 class G1CollectedHeap : public CollectedHeap {
 133   friend class G1FreeCollectionSetTask;
 134   friend class VM_CollectForMetadataAllocation;
 135   friend class VM_G1CollectForAllocation;
 136   friend class VM_G1CollectFull;
 137   friend class VMStructs;
 138   friend class MutatorAllocRegion;
 139   friend class G1FullCollector;
 140   friend class G1GCAllocRegion;
 141   friend class G1HeapVerifier;
 142 
 143   // Closures used in implementation.
 144   friend class G1ParScanThreadState;
 145   friend class G1ParScanThreadStateSet;
 146   friend class G1ParTask;
 147   friend class G1PLABAllocator;
 148   friend class G1PrepareCompactClosure;
 149 
 150   // Other related classes.
 151   friend class HeapRegionClaimer;
 152 
 153   // Testing classes.
 154   friend class G1CheckCSetFastTableClosure;
 155 
 156 private:
 157   G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
 158 
 159   WorkGang* _workers;
 160   G1CollectorPolicy* _collector_policy;
 161   G1CardTable* _card_table;
 162 
 163   SoftRefPolicy      _soft_ref_policy;
 164 
 165   static size_t _humongous_object_threshold_in_words;
 166 
 167   // These sets keep track of old, archive and humongous regions respectively.
 168   HeapRegionSet _old_set;
 169   HeapRegionSet _archive_set;
 170   HeapRegionSet _humongous_set;
 171 
 172   void eagerly_reclaim_humongous_regions();
 173   // Start a new incremental collection set for the next pause.
 174   void start_new_collection_set();
 175 
 176   // The block offset table for the G1 heap.
 177   G1BlockOffsetTable* _bot;
 178 
 179   // Tears down the region sets / lists so that they are empty and the
 180   // regions on the heap do not belong to a region set / list. The
 181   // only exception is the humongous set which we leave unaltered. If
 182   // free_list_only is true, it will only tear down the master free
 183   // list. It is called before a Full GC (free_list_only == false) or
 184   // before heap shrinking (free_list_only == true).
 185   void tear_down_region_sets(bool free_list_only);
 186 
 187   // Rebuilds the region sets / lists so that they are repopulated to
 188   // reflect the contents of the heap. The only exception is the
 189   // humongous set which was not torn down in the first place. If
 190   // free_list_only is true, it will only rebuild the master free
 191   // list. It is called after a Full GC (free_list_only == false) or
 192   // after heap shrinking (free_list_only == true).
 193   void rebuild_region_sets(bool free_list_only);
 194 
 195   // Callback for region mapping changed events.
 196   G1RegionMappingChangedListener _listener;
 197 
 198   // The sequence of all heap regions in the heap.
 199   HeapRegionManager* _hrm;
 200 
 201   // Manages all allocations with regions except humongous object allocations.
 202   G1Allocator* _allocator;
 203 
 204   // Manages all heap verification.
 205   G1HeapVerifier* _verifier;
 206 
 207   // Outside of GC pauses, the number of bytes used in all regions other
 208   // than the current allocation region(s).
 209   size_t _summary_bytes_used;
 210 
 211   void increase_used(size_t bytes);
 212   void decrease_used(size_t bytes);
 213 
 214   void set_used(size_t bytes);
 215 
 216   // Class that handles archive allocation ranges.
 217   G1ArchiveAllocator* _archive_allocator;
 218 
 219   // GC allocation statistics policy for survivors.
 220   G1EvacStats _survivor_evac_stats;
 221 
 222   // GC allocation statistics policy for tenured objects.
 223   G1EvacStats _old_evac_stats;
 224 
 225   // It specifies whether we should attempt to expand the heap after a
 226   // region allocation failure. If heap expansion fails we set this to
 227   // false so that we don't re-attempt the heap expansion (it's likely
 228   // that subsequent expansion attempts will also fail if one fails).
 229   // Currently, it is only consulted during GC and it's reset at the
 230   // start of each GC.
 231   bool _expand_heap_after_alloc_failure;
 232 
 233   // Helper for monitoring and management support.
 234   G1MonitoringSupport* _g1mm;
 235 
 236   // Records whether the region at the given index is (still) a
 237   // candidate for eager reclaim.  Only valid for humongous start
 238   // regions; other regions have unspecified values.  Humongous start
 239   // regions are initialized at start of collection pause, with
 240   // candidates removed from the set as they are found reachable from
 241   // roots or the young generation.
 242   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 243    protected:
 244     bool default_value() const { return false; }
 245    public:
 246     void clear() { G1BiasedMappedArray<bool>::clear(); }
 247     void set_candidate(uint region, bool value) {
 248       set_by_index(region, value);
 249     }
 250     bool is_candidate(uint region) {
 251       return get_by_index(region);
 252     }
 253   };
 254 
 255   HumongousReclaimCandidates _humongous_reclaim_candidates;
 256   // Stores whether during humongous object registration we found candidate regions.
 257   // If not, we can skip a few steps.
 258   bool _has_humongous_reclaim_candidates;
 259 
 260   G1HRPrinter _hr_printer;
 261 
 262   // It decides whether an explicit GC should start a concurrent cycle
 263   // instead of doing a STW GC. Currently, a concurrent cycle is
 264   // explicitly started if:
 265   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 266   // (b) cause == _g1_humongous_allocation
 267   // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 268   // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 269   // (e) cause == _wb_conc_mark
 270   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 271 
 272   // Return true if should upgrade to full gc after an incremental one.
 273   bool should_upgrade_to_full_gc(GCCause::Cause cause);
 274 
 275   // indicates whether we are in young or mixed GC mode
 276   G1CollectorState _collector_state;
 277 
 278   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 279   // concurrent cycles) we have started.
 280   volatile uint _old_marking_cycles_started;
 281 
 282   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 283   // concurrent cycles) we have completed.
 284   volatile uint _old_marking_cycles_completed;
 285 
 286   // This is a non-product method that is helpful for testing. It is
 287   // called at the end of a GC and artificially expands the heap by
 288   // allocating a number of dead regions. This way we can induce very
 289   // frequent marking cycles and stress the cleanup / concurrent
 290   // cleanup code more (as all the regions that will be allocated by
 291   // this method will be found dead by the marking cycle).
 292   void allocate_dummy_regions() PRODUCT_RETURN;
 293 
 294   // If the HR printer is active, dump the state of the regions in the
 295   // heap after a compaction.
 296   void print_hrm_post_compaction();
 297 
 298   // Create a memory mapper for auxiliary data structures of the given size and
 299   // translation factor.
 300   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 301                                                          size_t size,
 302                                                          size_t translation_factor);
 303 
 304   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 305 
 306   // These are macros so that, if the assert fires, we get the correct
 307   // line number, file, etc.
 308 
 309 #define heap_locking_asserts_params(_extra_message_)                          \
 310   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 311   (_extra_message_),                                                          \
 312   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 313   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 314   BOOL_TO_STR(Thread::current()->is_VM_thread())
 315 
 316 #define assert_heap_locked()                                                  \
 317   do {                                                                        \
 318     assert(Heap_lock->owned_by_self(),                                        \
 319            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 320   } while (0)
 321 
 322 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 323   do {                                                                        \
 324     assert(Heap_lock->owned_by_self() ||                                      \
 325            (SafepointSynchronize::is_at_safepoint() &&                        \
 326              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 327            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 328                                         "should be at a safepoint"));         \
 329   } while (0)
 330 
 331 #define assert_heap_locked_and_not_at_safepoint()                             \
 332   do {                                                                        \
 333     assert(Heap_lock->owned_by_self() &&                                      \
 334                                     !SafepointSynchronize::is_at_safepoint(), \
 335           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 336                                        "should not be at a safepoint"));      \
 337   } while (0)
 338 
 339 #define assert_heap_not_locked()                                              \
 340   do {                                                                        \
 341     assert(!Heap_lock->owned_by_self(),                                       \
 342         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 343   } while (0)
 344 
 345 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 346   do {                                                                        \
 347     assert(!Heap_lock->owned_by_self() &&                                     \
 348                                     !SafepointSynchronize::is_at_safepoint(), \
 349       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 350                                    "should not be at a safepoint"));          \
 351   } while (0)
 352 
 353 #define assert_at_safepoint_on_vm_thread()                                    \
 354   do {                                                                        \
 355     assert_at_safepoint();                                                    \
 356     assert(Thread::current_or_null() != NULL, "no current thread");           \
 357     assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
 358   } while (0)
 359 
 360   const char* young_gc_name() const;
 361 
 362   // The young region list.
 363   G1EdenRegions _eden;
 364   G1SurvivorRegions _survivor;
 365 
 366   STWGCTimer* _gc_timer_stw;
 367 
 368   G1NewTracer* _gc_tracer_stw;
 369 
 370   // The current policy object for the collector.
 371   G1Policy* _policy;
 372   G1HeapSizingPolicy* _heap_sizing_policy;
 373 
 374   G1CollectionSet _collection_set;
 375 
 376   // Try to allocate a single non-humongous HeapRegion sufficient for
 377   // an allocation of the given word_size. If do_expand is true,
 378   // attempt to expand the heap if necessary to satisfy the allocation
 379   // request. 'type' takes the type of region to be allocated. (Use constants
 380   // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
 381   HeapRegion* new_region(size_t word_size, HeapRegionType type, bool do_expand);
 382 
 383   // Initialize a contiguous set of free regions of length num_regions
 384   // and starting at index first so that they appear as a single
 385   // humongous region.
 386   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 387                                                       uint num_regions,
 388                                                       size_t word_size);
 389 
 390   // Attempt to allocate a humongous object of the given size. Return
 391   // NULL if unsuccessful.
 392   HeapWord* humongous_obj_allocate(size_t word_size);
 393 
 394   // The following two methods, allocate_new_tlab() and
 395   // mem_allocate(), are the two main entry points from the runtime
 396   // into the G1's allocation routines. They have the following
 397   // assumptions:
 398   //
 399   // * They should both be called outside safepoints.
 400   //
 401   // * They should both be called without holding the Heap_lock.
 402   //
 403   // * All allocation requests for new TLABs should go to
 404   //   allocate_new_tlab().
 405   //
 406   // * All non-TLAB allocation requests should go to mem_allocate().
 407   //
 408   // * If either call cannot satisfy the allocation request using the
 409   //   current allocating region, they will try to get a new one. If
 410   //   this fails, they will attempt to do an evacuation pause and
 411   //   retry the allocation.
 412   //
 413   // * If all allocation attempts fail, even after trying to schedule
 414   //   an evacuation pause, allocate_new_tlab() will return NULL,
 415   //   whereas mem_allocate() will attempt a heap expansion and/or
 416   //   schedule a Full GC.
 417   //
 418   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 419   //   should never be called with word_size being humongous. All
 420   //   humongous allocation requests should go to mem_allocate() which
 421   //   will satisfy them with a special path.
 422 
 423   virtual HeapWord* allocate_new_tlab(size_t min_size,
 424                                       size_t requested_size,
 425                                       size_t* actual_size);
 426 
 427   virtual HeapWord* mem_allocate(size_t word_size,
 428                                  bool*  gc_overhead_limit_was_exceeded);
 429 
 430   // First-level mutator allocation attempt: try to allocate out of
 431   // the mutator alloc region without taking the Heap_lock. This
 432   // should only be used for non-humongous allocations.
 433   inline HeapWord* attempt_allocation(size_t min_word_size,
 434                                       size_t desired_word_size,
 435                                       size_t* actual_word_size);
 436 
 437   // Second-level mutator allocation attempt: take the Heap_lock and
 438   // retry the allocation attempt, potentially scheduling a GC
 439   // pause. This should only be used for non-humongous allocations.
 440   HeapWord* attempt_allocation_slow(size_t word_size);
 441 
 442   // Takes the Heap_lock and attempts a humongous allocation. It can
 443   // potentially schedule a GC pause.
 444   HeapWord* attempt_allocation_humongous(size_t word_size);
 445 
 446   // Allocation attempt that should be called during safepoints (e.g.,
 447   // at the end of a successful GC). expect_null_mutator_alloc_region
 448   // specifies whether the mutator alloc region is expected to be NULL
 449   // or not.
 450   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 451                                             bool expect_null_mutator_alloc_region);
 452 
 453   // These methods are the "callbacks" from the G1AllocRegion class.
 454 
 455   // For mutator alloc regions.
 456   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 457   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 458                                    size_t allocated_bytes);
 459 
 460   // For GC alloc regions.
 461   bool has_more_regions(InCSetState dest);
 462   HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
 463   void retire_gc_alloc_region(HeapRegion* alloc_region,
 464                               size_t allocated_bytes, InCSetState dest);
 465 
 466   // - if explicit_gc is true, the GC is for a System.gc() etc,
 467   //   otherwise it's for a failed allocation.
 468   // - if clear_all_soft_refs is true, all soft references should be
 469   //   cleared during the GC.
 470   // - it returns false if it is unable to do the collection due to the
 471   //   GC locker being active, true otherwise.
 472   bool do_full_collection(bool explicit_gc,
 473                           bool clear_all_soft_refs);
 474 
 475   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 476   virtual void do_full_collection(bool clear_all_soft_refs);
 477 
 478   // Callback from VM_G1CollectForAllocation operation.
 479   // This function does everything necessary/possible to satisfy a
 480   // failed allocation request (including collection, expansion, etc.)
 481   HeapWord* satisfy_failed_allocation(size_t word_size,
 482                                       bool* succeeded);
 483   // Internal helpers used during full GC to split it up to
 484   // increase readability.
 485   void abort_concurrent_cycle();
 486   void verify_before_full_collection(bool explicit_gc);
 487   void prepare_heap_for_full_collection();
 488   void prepare_heap_for_mutators();
 489   void abort_refinement();
 490   void verify_after_full_collection();
 491   void print_heap_after_full_collection(G1HeapTransition* heap_transition);
 492 
 493   // Helper method for satisfy_failed_allocation()
 494   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 495                                              bool do_gc,
 496                                              bool clear_all_soft_refs,
 497                                              bool expect_null_mutator_alloc_region,
 498                                              bool* gc_succeeded);
 499 
 500   // Attempting to expand the heap sufficiently
 501   // to support an allocation of the given "word_size".  If
 502   // successful, perform the allocation and return the address of the
 503   // allocated block, or else "NULL".
 504   HeapWord* expand_and_allocate(size_t word_size);
 505 
 506   // Process any reference objects discovered.
 507   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 508 
 509   // If during an initial mark pause we may install a pending list head which is not
 510   // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
 511   // to discover.
 512   void make_pending_list_reachable();
 513 
 514   // Merges the information gathered on a per-thread basis for all worker threads
 515   // during GC into global variables.
 516   void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
 517 public:
 518   G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
 519 
 520   WorkGang* workers() const { return _workers; }
 521 
 522   G1Allocator* allocator() {
 523     return _allocator;
 524   }
 525 
 526   G1HeapVerifier* verifier() {
 527     return _verifier;
 528   }
 529 
 530   G1MonitoringSupport* g1mm() {
 531     assert(_g1mm != NULL, "should have been initialized");
 532     return _g1mm;
 533   }
 534 
 535   void resize_heap_if_necessary();
 536 
 537   // Expand the garbage-first heap by at least the given size (in bytes!).
 538   // Returns true if the heap was expanded by the requested amount;
 539   // false otherwise.
 540   // (Rounds up to a HeapRegion boundary.)
 541   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 542 
 543   // Returns the PLAB statistics for a given destination.
 544   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 545 
 546   // Determines PLAB size for a given destination.
 547   inline size_t desired_plab_sz(InCSetState dest);
 548 
 549   // Do anything common to GC's.
 550   void gc_prologue(bool full);
 551   void gc_epilogue(bool full);
 552 
 553   // Does the given region fulfill remembered set based eager reclaim candidate requirements?
 554   bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
 555 
 556   // Modify the reclaim candidate set and test for presence.
 557   // These are only valid for starts_humongous regions.
 558   inline void set_humongous_reclaim_candidate(uint region, bool value);
 559   inline bool is_humongous_reclaim_candidate(uint region);
 560 
 561   // Remove from the reclaim candidate set.  Also remove from the
 562   // collection set so that later encounters avoid the slow path.
 563   inline void set_humongous_is_live(oop obj);
 564 
 565   // Register the given region to be part of the collection set.
 566   inline void register_humongous_region_with_cset(uint index);
 567   // Register regions with humongous objects (actually on the start region) in
 568   // the in_cset_fast_test table.
 569   void register_humongous_regions_with_cset();
 570   // We register a region with the fast "in collection set" test. We
 571   // simply set to true the array slot corresponding to this region.
 572   void register_young_region_with_cset(HeapRegion* r) {
 573     _in_cset_fast_test.set_in_young(r->hrm_index());
 574   }
 575   void register_old_region_with_cset(HeapRegion* r) {
 576     _in_cset_fast_test.set_in_old(r->hrm_index());
 577   }
 578   void register_optional_region_with_cset(HeapRegion* r) {
 579     _in_cset_fast_test.set_optional(r->hrm_index());
 580   }
 581   void clear_in_cset(const HeapRegion* hr) {
 582     _in_cset_fast_test.clear(hr);
 583   }
 584 
 585   void clear_cset_fast_test() {
 586     _in_cset_fast_test.clear();
 587   }
 588 
 589   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 590 
 591   // This is called at the start of either a concurrent cycle or a Full
 592   // GC to update the number of old marking cycles started.
 593   void increment_old_marking_cycles_started();
 594 
 595   // This is called at the end of either a concurrent cycle or a Full
 596   // GC to update the number of old marking cycles completed. Those two
 597   // can happen in a nested fashion, i.e., we start a concurrent
 598   // cycle, a Full GC happens half-way through it which ends first,
 599   // and then the cycle notices that a Full GC happened and ends
 600   // too. The concurrent parameter is a boolean to help us do a bit
 601   // tighter consistency checking in the method. If concurrent is
 602   // false, the caller is the inner caller in the nesting (i.e., the
 603   // Full GC). If concurrent is true, the caller is the outer caller
 604   // in this nesting (i.e., the concurrent cycle). Further nesting is
 605   // not currently supported. The end of this call also notifies
 606   // the FullGCCount_lock in case a Java thread is waiting for a full
 607   // GC to happen (e.g., it called System.gc() with
 608   // +ExplicitGCInvokesConcurrent).
 609   void increment_old_marking_cycles_completed(bool concurrent);
 610 
 611   uint old_marking_cycles_completed() {
 612     return _old_marking_cycles_completed;
 613   }
 614 
 615   G1HRPrinter* hr_printer() { return &_hr_printer; }
 616 
 617   // Allocates a new heap region instance.
 618   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 619 
 620   // Allocate the highest free region in the reserved heap. This will commit
 621   // regions as necessary.
 622   HeapRegion* alloc_highest_free_region();
 623 
 624   // Frees a non-humongous region by initializing its contents and
 625   // adding it to the free list that's passed as a parameter (this is
 626   // usually a local list which will be appended to the master free
 627   // list later). The used bytes of freed regions are accumulated in
 628   // pre_used. If skip_remset is true, the region's RSet will not be freed
 629   // up. If skip_hot_card_cache is true, the region's hot card cache will not
 630   // be freed up. The assumption is that this will be done later.
 631   // The locked parameter indicates if the caller has already taken
 632   // care of proper synchronization. This may allow some optimizations.
 633   void free_region(HeapRegion* hr,
 634                    FreeRegionList* free_list,
 635                    bool skip_remset,
 636                    bool skip_hot_card_cache = false,
 637                    bool locked = false);
 638 
 639   // It dirties the cards that cover the block so that the post
 640   // write barrier never queues anything when updating objects on this
 641   // block. It is assumed (and in fact we assert) that the block
 642   // belongs to a young region.
 643   inline void dirty_young_block(HeapWord* start, size_t word_size);
 644 
 645   // Frees a humongous region by collapsing it into individual regions
 646   // and calling free_region() for each of them. The freed regions
 647   // will be added to the free list that's passed as a parameter (this
 648   // is usually a local list which will be appended to the master free
 649   // list later).
 650   // The method assumes that only a single thread is ever calling
 651   // this for a particular region at once.
 652   void free_humongous_region(HeapRegion* hr,
 653                              FreeRegionList* free_list);
 654 
 655   // Facility for allocating in 'archive' regions in high heap memory and
 656   // recording the allocated ranges. These should all be called from the
 657   // VM thread at safepoints, without the heap lock held. They can be used
 658   // to create and archive a set of heap regions which can be mapped at the
 659   // same fixed addresses in a subsequent JVM invocation.
 660   void begin_archive_alloc_range(bool open = false);
 661 
 662   // Check if the requested size would be too large for an archive allocation.
 663   bool is_archive_alloc_too_large(size_t word_size);
 664 
 665   // Allocate memory of the requested size from the archive region. This will
 666   // return NULL if the size is too large or if no memory is available. It
 667   // does not trigger a garbage collection.
 668   HeapWord* archive_mem_allocate(size_t word_size);
 669 
 670   // Optionally aligns the end address and returns the allocated ranges in
 671   // an array of MemRegions in order of ascending addresses.
 672   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 673                                size_t end_alignment_in_bytes = 0);
 674 
 675   // Facility for allocating a fixed range within the heap and marking
 676   // the containing regions as 'archive'. For use at JVM init time, when the
 677   // caller may mmap archived heap data at the specified range(s).
 678   // Verify that the MemRegions specified in the argument array are within the
 679   // reserved heap.
 680   bool check_archive_addresses(MemRegion* range, size_t count);
 681 
 682   // Commit the appropriate G1 regions containing the specified MemRegions
 683   // and mark them as 'archive' regions. The regions in the array must be
 684   // non-overlapping and in order of ascending address.
 685   bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
 686 
 687   // Insert any required filler objects in the G1 regions around the specified
 688   // ranges to make the regions parseable. This must be called after
 689   // alloc_archive_regions, and after class loading has occurred.
 690   void fill_archive_regions(MemRegion* range, size_t count);
 691 
 692   // For each of the specified MemRegions, uncommit the containing G1 regions
 693   // which had been allocated by alloc_archive_regions. This should be called
 694   // rather than fill_archive_regions at JVM init time if the archive file
 695   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 696   void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open);
 697 
 698   oop materialize_archived_object(oop obj);
 699 
 700 private:
 701 
 702   // Shrink the garbage-first heap by at most the given size (in bytes!).
 703   // (Rounds down to a HeapRegion boundary.)
 704   void shrink(size_t expand_bytes);
 705   void shrink_helper(size_t expand_bytes);
 706 
 707   #if TASKQUEUE_STATS
 708   static void print_taskqueue_stats_hdr(outputStream* const st);
 709   void print_taskqueue_stats() const;
 710   void reset_taskqueue_stats();
 711   #endif // TASKQUEUE_STATS
 712 
 713   // Schedule the VM operation that will do an evacuation pause to
 714   // satisfy an allocation request of word_size. *succeeded will
 715   // return whether the VM operation was successful (it did do an
 716   // evacuation pause) or not (another thread beat us to it or the GC
 717   // locker was active). Given that we should not be holding the
 718   // Heap_lock when we enter this method, we will pass the
 719   // gc_count_before (i.e., total_collections()) as a parameter since
 720   // it has to be read while holding the Heap_lock. Currently, both
 721   // methods that call do_collection_pause() release the Heap_lock
 722   // before the call, so it's easy to read gc_count_before just before.
 723   HeapWord* do_collection_pause(size_t         word_size,
 724                                 uint           gc_count_before,
 725                                 bool*          succeeded,
 726                                 GCCause::Cause gc_cause);
 727 
 728   void wait_for_root_region_scanning();
 729 
 730   // The guts of the incremental collection pause, executed by the vm
 731   // thread. It returns false if it is unable to do the collection due
 732   // to the GC locker being active, true otherwise
 733   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 734 
 735   G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
 736   void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
 737   void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
 738 
 739   void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
 740 
 741   // Actually do the work of evacuating the collection set.
 742   void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states);
 743   void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
 744   void evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset);
 745 
 746   void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info);
 747   void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 748 
 749   void expand_heap_after_young_collection();
 750   // Update object copying statistics.
 751   void record_obj_copy_mem_stats();
 752 
 753   // The hot card cache for remembered set insertion optimization.
 754   G1HotCardCache* _hot_card_cache;
 755 
 756   // The g1 remembered set of the heap.
 757   G1RemSet* _rem_set;
 758 
 759   // A set of cards that cover the objects for which the Rsets should be updated
 760   // concurrently after the collection.
 761   G1DirtyCardQueueSet _dirty_card_queue_set;
 762 
 763   // After a collection pause, convert the regions in the collection set into free
 764   // regions.
 765   void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 766 
 767   // Abandon the current collection set without recording policy
 768   // statistics or updating free lists.
 769   void abandon_collection_set(G1CollectionSet* collection_set);
 770 
 771   // The concurrent marker (and the thread it runs in.)
 772   G1ConcurrentMark* _cm;
 773   G1ConcurrentMarkThread* _cm_thread;
 774 
 775   // The concurrent refiner.
 776   G1ConcurrentRefine* _cr;
 777 
 778   // The parallel task queues
 779   RefToScanQueueSet *_task_queues;
 780 
 781   // True iff a evacuation has failed in the current collection.
 782   bool _evacuation_failed;
 783 
 784   EvacuationFailedInfo* _evacuation_failed_info_array;
 785 
 786   // Failed evacuations cause some logical from-space objects to have
 787   // forwarding pointers to themselves.  Reset them.
 788   void remove_self_forwarding_pointers();
 789 
 790   // Restore the objects in the regions in the collection set after an
 791   // evacuation failure.
 792   void restore_after_evac_failure();
 793 
 794   PreservedMarksSet _preserved_marks_set;
 795 
 796   // Preserve the mark of "obj", if necessary, in preparation for its mark
 797   // word being overwritten with a self-forwarding-pointer.
 798   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 799 
 800 #ifndef PRODUCT
 801   // Support for forcing evacuation failures. Analogous to
 802   // PromotionFailureALot for the other collectors.
 803 
 804   // Records whether G1EvacuationFailureALot should be in effect
 805   // for the current GC
 806   bool _evacuation_failure_alot_for_current_gc;
 807 
 808   // Used to record the GC number for interval checking when
 809   // determining whether G1EvaucationFailureALot is in effect
 810   // for the current GC.
 811   size_t _evacuation_failure_alot_gc_number;
 812 
 813   // Count of the number of evacuations between failures.
 814   volatile size_t _evacuation_failure_alot_count;
 815 
 816   // Set whether G1EvacuationFailureALot should be in effect
 817   // for the current GC (based upon the type of GC and which
 818   // command line flags are set);
 819   inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
 820                                                   bool during_initial_mark,
 821                                                   bool mark_or_rebuild_in_progress);
 822 
 823   inline void set_evacuation_failure_alot_for_current_gc();
 824 
 825   // Return true if it's time to cause an evacuation failure.
 826   inline bool evacuation_should_fail();
 827 
 828   // Reset the G1EvacuationFailureALot counters.  Should be called at
 829   // the end of an evacuation pause in which an evacuation failure occurred.
 830   inline void reset_evacuation_should_fail();
 831 #endif // !PRODUCT
 832 
 833   // ("Weak") Reference processing support.
 834   //
 835   // G1 has 2 instances of the reference processor class. One
 836   // (_ref_processor_cm) handles reference object discovery
 837   // and subsequent processing during concurrent marking cycles.
 838   //
 839   // The other (_ref_processor_stw) handles reference object
 840   // discovery and processing during full GCs and incremental
 841   // evacuation pauses.
 842   //
 843   // During an incremental pause, reference discovery will be
 844   // temporarily disabled for _ref_processor_cm and will be
 845   // enabled for _ref_processor_stw. At the end of the evacuation
 846   // pause references discovered by _ref_processor_stw will be
 847   // processed and discovery will be disabled. The previous
 848   // setting for reference object discovery for _ref_processor_cm
 849   // will be re-instated.
 850   //
 851   // At the start of marking:
 852   //  * Discovery by the CM ref processor is verified to be inactive
 853   //    and it's discovered lists are empty.
 854   //  * Discovery by the CM ref processor is then enabled.
 855   //
 856   // At the end of marking:
 857   //  * Any references on the CM ref processor's discovered
 858   //    lists are processed (possibly MT).
 859   //
 860   // At the start of full GC we:
 861   //  * Disable discovery by the CM ref processor and
 862   //    empty CM ref processor's discovered lists
 863   //    (without processing any entries).
 864   //  * Verify that the STW ref processor is inactive and it's
 865   //    discovered lists are empty.
 866   //  * Temporarily set STW ref processor discovery as single threaded.
 867   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 868   //    field.
 869   //  * Finally enable discovery by the STW ref processor.
 870   //
 871   // The STW ref processor is used to record any discovered
 872   // references during the full GC.
 873   //
 874   // At the end of a full GC we:
 875   //  * Enqueue any reference objects discovered by the STW ref processor
 876   //    that have non-live referents. This has the side-effect of
 877   //    making the STW ref processor inactive by disabling discovery.
 878   //  * Verify that the CM ref processor is still inactive
 879   //    and no references have been placed on it's discovered
 880   //    lists (also checked as a precondition during initial marking).
 881 
 882   // The (stw) reference processor...
 883   ReferenceProcessor* _ref_processor_stw;
 884 
 885   // During reference object discovery, the _is_alive_non_header
 886   // closure (if non-null) is applied to the referent object to
 887   // determine whether the referent is live. If so then the
 888   // reference object does not need to be 'discovered' and can
 889   // be treated as a regular oop. This has the benefit of reducing
 890   // the number of 'discovered' reference objects that need to
 891   // be processed.
 892   //
 893   // Instance of the is_alive closure for embedding into the
 894   // STW reference processor as the _is_alive_non_header field.
 895   // Supplying a value for the _is_alive_non_header field is
 896   // optional but doing so prevents unnecessary additions to
 897   // the discovered lists during reference discovery.
 898   G1STWIsAliveClosure _is_alive_closure_stw;
 899 
 900   G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
 901 
 902   // The (concurrent marking) reference processor...
 903   ReferenceProcessor* _ref_processor_cm;
 904 
 905   // Instance of the concurrent mark is_alive closure for embedding
 906   // into the Concurrent Marking reference processor as the
 907   // _is_alive_non_header field. Supplying a value for the
 908   // _is_alive_non_header field is optional but doing so prevents
 909   // unnecessary additions to the discovered lists during reference
 910   // discovery.
 911   G1CMIsAliveClosure _is_alive_closure_cm;
 912 
 913   G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
 914 public:
 915 
 916   RefToScanQueue *task_queue(uint i) const;
 917 
 918   uint num_task_queues() const;
 919 
 920   // A set of cards where updates happened during the GC
 921   G1DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 922 
 923   // Create a G1CollectedHeap with the specified policy.
 924   // Must call the initialize method afterwards.
 925   // May not return if something goes wrong.
 926   G1CollectedHeap(G1CollectorPolicy* policy);
 927 
 928 private:
 929   jint initialize_concurrent_refinement();
 930   jint initialize_young_gen_sampling_thread();
 931 public:
 932   // Initialize the G1CollectedHeap to have the initial and
 933   // maximum sizes and remembered and barrier sets
 934   // specified by the policy object.
 935   jint initialize();
 936 
 937   virtual void stop();
 938   virtual void safepoint_synchronize_begin();
 939   virtual void safepoint_synchronize_end();
 940 
 941   // Return the (conservative) maximum heap alignment for any G1 heap
 942   static size_t conservative_max_heap_alignment();
 943 
 944   // Does operations required after initialization has been done.
 945   void post_initialize();
 946 
 947   // Initialize weak reference processing.
 948   void ref_processing_init();
 949 
 950   virtual Name kind() const {
 951     return CollectedHeap::G1;
 952   }
 953 
 954   virtual const char* name() const {
 955     return "G1";
 956   }
 957 
 958   const G1CollectorState* collector_state() const { return &_collector_state; }
 959   G1CollectorState* collector_state() { return &_collector_state; }
 960 
 961   // The current policy object for the collector.
 962   G1Policy* policy() const { return _policy; }
 963   // The remembered set.
 964   G1RemSet* rem_set() const { return _rem_set; }
 965 
 966   inline G1GCPhaseTimes* phase_times() const;
 967 
 968   HeapRegionManager* hrm() const { return _hrm; }
 969 
 970   const G1CollectionSet* collection_set() const { return &_collection_set; }
 971   G1CollectionSet* collection_set() { return &_collection_set; }
 972 
 973   virtual CollectorPolicy* collector_policy() const;
 974 
 975   virtual SoftRefPolicy* soft_ref_policy();
 976 
 977   virtual void initialize_serviceability();
 978   virtual MemoryUsage memory_usage();
 979   virtual GrowableArray<GCMemoryManager*> memory_managers();
 980   virtual GrowableArray<MemoryPool*> memory_pools();
 981 
 982   // Try to minimize the remembered set.
 983   void scrub_rem_set();
 984 
 985   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
 986   void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i);
 987 
 988   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
 989   void iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i);
 990 
 991   // The shared block offset table array.
 992   G1BlockOffsetTable* bot() const { return _bot; }
 993 
 994   // Reference Processing accessors
 995 
 996   // The STW reference processor....
 997   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
 998 
 999   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1000 
1001   // The Concurrent Marking reference processor...
1002   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1003 
1004   size_t unused_committed_regions_in_bytes() const;
1005   virtual size_t capacity() const;
1006   virtual size_t used() const;
1007   // This should be called when we're not holding the heap lock. The
1008   // result might be a bit inaccurate.
1009   size_t used_unlocked() const;
1010   size_t recalculate_used() const;
1011 
1012   // These virtual functions do the actual allocation.
1013   // Some heaps may offer a contiguous region for shared non-blocking
1014   // allocation, via inlined code (by exporting the address of the top and
1015   // end fields defining the extent of the contiguous allocation region.)
1016   // But G1CollectedHeap doesn't yet support this.
1017 
1018   virtual bool is_maximal_no_gc() const {
1019     return _hrm->available() == 0;
1020   }
1021 
1022   // Returns whether there are any regions left in the heap for allocation.
1023   bool has_regions_left_for_allocation() const {
1024     return !is_maximal_no_gc() || num_free_regions() != 0;
1025   }
1026 
1027   // The current number of regions in the heap.
1028   uint num_regions() const { return _hrm->length(); }
1029 
1030   // The max number of regions in the heap.
1031   uint max_regions() const { return _hrm->max_length(); }
1032 
1033   // Max number of regions that can be comitted.
1034   uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1035 
1036   // The number of regions that are completely free.
1037   uint num_free_regions() const { return _hrm->num_free_regions(); }
1038 
1039   // The number of regions that can be allocated into.
1040   uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1041 
1042   MemoryUsage get_auxiliary_data_memory_usage() const {
1043     return _hrm->get_auxiliary_data_memory_usage();
1044   }
1045 
1046   // The number of regions that are not completely free.
1047   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1048 
1049 #ifdef ASSERT
1050   bool is_on_master_free_list(HeapRegion* hr) {
1051     return _hrm->is_free(hr);
1052   }
1053 #endif // ASSERT
1054 
1055   inline void old_set_add(HeapRegion* hr);
1056   inline void old_set_remove(HeapRegion* hr);
1057 
1058   inline void archive_set_add(HeapRegion* hr);
1059 
1060   size_t non_young_capacity_bytes() {
1061     return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1062   }
1063 
1064   // Determine whether the given region is one that we are using as an
1065   // old GC alloc region.
1066   bool is_old_gc_alloc_region(HeapRegion* hr);
1067 
1068   // Perform a collection of the heap; intended for use in implementing
1069   // "System.gc".  This probably implies as full a collection as the
1070   // "CollectedHeap" supports.
1071   virtual void collect(GCCause::Cause cause);
1072 
1073   // Perform a collection of the heap with the given cause; if the VM operation
1074   // fails to execute for any reason, retry only if retry_on_gc_failure is set.
1075   // Returns whether this collection actually executed.
1076   bool try_collect(GCCause::Cause cause, bool retry_on_gc_failure);
1077 
1078   // True iff an evacuation has failed in the most-recent collection.
1079   bool evacuation_failed() { return _evacuation_failed; }
1080 
1081   void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1082   void prepend_to_freelist(FreeRegionList* list);
1083   void decrement_summary_bytes(size_t bytes);
1084 
1085   virtual bool is_in(const void* p) const;
1086 #ifdef ASSERT
1087   // Returns whether p is in one of the available areas of the heap. Slow but
1088   // extensive version.
1089   bool is_in_exact(const void* p) const;
1090 #endif
1091 
1092   // Return "TRUE" iff the given object address is within the collection
1093   // set. Assumes that the reference points into the heap.
1094   inline bool is_in_cset(const HeapRegion *hr);
1095   inline bool is_in_cset(oop obj);
1096   inline bool is_in_cset(HeapWord* addr);
1097 
1098   inline bool is_in_cset_or_humongous(const oop obj);
1099 
1100  private:
1101   // This array is used for a quick test on whether a reference points into
1102   // the collection set or not. Each of the array's elements denotes whether the
1103   // corresponding region is in the collection set or not.
1104   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1105 
1106  public:
1107 
1108   inline InCSetState in_cset_state(const oop obj);
1109 
1110   // Return "TRUE" iff the given object address is in the reserved
1111   // region of g1.
1112   bool is_in_g1_reserved(const void* p) const {
1113     return _hrm->reserved().contains(p);
1114   }
1115 
1116   // Returns a MemRegion that corresponds to the space that has been
1117   // reserved for the heap
1118   MemRegion g1_reserved() const {
1119     return _hrm->reserved();
1120   }
1121 
1122   G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1123 
1124   G1CardTable* card_table() const {
1125     return _card_table;
1126   }
1127 
1128   // Iteration functions.
1129 
1130   // Iterate over all objects, calling "cl.do_object" on each.
1131   virtual void object_iterate(ObjectClosure* cl);
1132 
1133   virtual void safe_object_iterate(ObjectClosure* cl) {
1134     object_iterate(cl);
1135   }
1136 
1137   // Iterate over heap regions, in address order, terminating the
1138   // iteration early if the "do_heap_region" method returns "true".
1139   void heap_region_iterate(HeapRegionClosure* blk) const;
1140 
1141   // Return the region with the given index. It assumes the index is valid.
1142   inline HeapRegion* region_at(uint index) const;
1143   inline HeapRegion* region_at_or_null(uint index) const;
1144 
1145   // Return the next region (by index) that is part of the same
1146   // humongous object that hr is part of.
1147   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1148 
1149   // Calculate the region index of the given address. Given address must be
1150   // within the heap.
1151   inline uint addr_to_region(HeapWord* addr) const;
1152 
1153   inline HeapWord* bottom_addr_for_region(uint index) const;
1154 
1155   // Two functions to iterate over the heap regions in parallel. Threads
1156   // compete using the HeapRegionClaimer to claim the regions before
1157   // applying the closure on them.
1158   // The _from_worker_offset version uses the HeapRegionClaimer and
1159   // the worker id to calculate a start offset to prevent all workers to
1160   // start from the point.
1161   void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1162                                                   HeapRegionClaimer* hrclaimer,
1163                                                   uint worker_id) const;
1164 
1165   void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1166                                           HeapRegionClaimer* hrclaimer) const;
1167 
1168   // Iterate over the regions (if any) in the current collection set.
1169   void collection_set_iterate(HeapRegionClosure* blk);
1170 
1171   // Iterate over the regions (if any) in the current collection set. Starts the
1172   // iteration over the entire collection set so that the start regions of a given
1173   // worker id over the set active_workers are evenly spread across the set of
1174   // collection set regions.
1175   void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1176 
1177   // Returns the HeapRegion that contains addr. addr must not be NULL.
1178   template <class T>
1179   inline HeapRegion* heap_region_containing(const T addr) const;
1180 
1181   // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1182   // region. addr must not be NULL.
1183   template <class T>
1184   inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1185 
1186   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1187   // each address in the (reserved) heap is a member of exactly
1188   // one block.  The defining characteristic of a block is that it is
1189   // possible to find its size, and thus to progress forward to the next
1190   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1191   // represent Java objects, or they might be free blocks in a
1192   // free-list-based heap (or subheap), as long as the two kinds are
1193   // distinguishable and the size of each is determinable.
1194 
1195   // Returns the address of the start of the "block" that contains the
1196   // address "addr".  We say "blocks" instead of "object" since some heaps
1197   // may not pack objects densely; a chunk may either be an object or a
1198   // non-object.
1199   virtual HeapWord* block_start(const void* addr) const;
1200 
1201   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1202   // the block is an object.
1203   virtual bool block_is_obj(const HeapWord* addr) const;
1204 
1205   // Section on thread-local allocation buffers (TLABs)
1206   // See CollectedHeap for semantics.
1207 
1208   bool supports_tlab_allocation() const;
1209   size_t tlab_capacity(Thread* ignored) const;
1210   size_t tlab_used(Thread* ignored) const;
1211   size_t max_tlab_size() const;
1212   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1213 
1214   inline bool is_in_young(const oop obj);
1215 
1216   // Returns "true" iff the given word_size is "very large".
1217   static bool is_humongous(size_t word_size) {
1218     // Note this has to be strictly greater-than as the TLABs
1219     // are capped at the humongous threshold and we want to
1220     // ensure that we don't try to allocate a TLAB as
1221     // humongous and that we don't allocate a humongous
1222     // object in a TLAB.
1223     return word_size > _humongous_object_threshold_in_words;
1224   }
1225 
1226   // Returns the humongous threshold for a specific region size
1227   static size_t humongous_threshold_for(size_t region_size) {
1228     return (region_size / 2);
1229   }
1230 
1231   // Returns the number of regions the humongous object of the given word size
1232   // requires.
1233   static size_t humongous_obj_size_in_regions(size_t word_size);
1234 
1235   // Print the maximum heap capacity.
1236   virtual size_t max_capacity() const;
1237 
1238   // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1239   virtual size_t max_reserved_capacity() const;
1240 
1241   virtual jlong millis_since_last_gc();
1242 
1243 
1244   // Convenience function to be used in situations where the heap type can be
1245   // asserted to be this type.
1246   static G1CollectedHeap* heap();
1247 
1248   void set_region_short_lived_locked(HeapRegion* hr);
1249   // add appropriate methods for any other surv rate groups
1250 
1251   const G1SurvivorRegions* survivor() const { return &_survivor; }
1252 
1253   uint eden_regions_count() const { return _eden.length(); }
1254   uint survivor_regions_count() const { return _survivor.length(); }
1255   uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1256   uint old_regions_count() const { return _old_set.length(); }
1257   uint archive_regions_count() const { return _archive_set.length(); }
1258   uint humongous_regions_count() const { return _humongous_set.length(); }
1259 
1260 #ifdef ASSERT
1261   bool check_young_list_empty();
1262 #endif
1263 
1264   // *** Stuff related to concurrent marking.  It's not clear to me that so
1265   // many of these need to be public.
1266 
1267   // The functions below are helper functions that a subclass of
1268   // "CollectedHeap" can use in the implementation of its virtual
1269   // functions.
1270   // This performs a concurrent marking of the live objects in a
1271   // bitmap off to the side.
1272   void do_concurrent_mark();
1273 
1274   bool is_marked_next(oop obj) const;
1275 
1276   // Determine if an object is dead, given the object and also
1277   // the region to which the object belongs. An object is dead
1278   // iff a) it was not allocated since the last mark, b) it
1279   // is not marked, and c) it is not in an archive region.
1280   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1281     return
1282       hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1283       !hr->is_archive();
1284   }
1285 
1286   // This function returns true when an object has been
1287   // around since the previous marking and hasn't yet
1288   // been marked during this marking, and is not in an archive region.
1289   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1290     return
1291       !hr->obj_allocated_since_next_marking(obj) &&
1292       !is_marked_next(obj) &&
1293       !hr->is_archive();
1294   }
1295 
1296   // Determine if an object is dead, given only the object itself.
1297   // This will find the region to which the object belongs and
1298   // then call the region version of the same function.
1299 
1300   // Added if it is NULL it isn't dead.
1301 
1302   inline bool is_obj_dead(const oop obj) const;
1303 
1304   inline bool is_obj_ill(const oop obj) const;
1305 
1306   inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1307   inline bool is_obj_dead_full(const oop obj) const;
1308 
1309   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1310 
1311   // Refinement
1312 
1313   G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1314 
1315   // Optimized nmethod scanning support routines
1316 
1317   // Register the given nmethod with the G1 heap.
1318   virtual void register_nmethod(nmethod* nm);
1319 
1320   // Unregister the given nmethod from the G1 heap.
1321   virtual void unregister_nmethod(nmethod* nm);
1322 
1323   // No nmethod flushing needed.
1324   virtual void flush_nmethod(nmethod* nm) {}
1325 
1326   // No nmethod verification implemented.
1327   virtual void verify_nmethod(nmethod* nm) {}
1328 
1329   // Free up superfluous code root memory.
1330   void purge_code_root_memory();
1331 
1332   // Rebuild the strong code root lists for each region
1333   // after a full GC.
1334   void rebuild_strong_code_roots();
1335 
1336   // Partial cleaning of VM internal data structures.
1337   void string_dedup_cleaning(BoolObjectClosure* is_alive,
1338                              OopClosure* keep_alive,
1339                              G1GCPhaseTimes* phase_times = NULL);
1340 
1341   // Performs cleaning of data structures after class unloading.
1342   void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1343 
1344   // Redirty logged cards in the refinement queue.
1345   void redirty_logged_cards();
1346   // Verification
1347 
1348   // Deduplicate the string
1349   virtual void deduplicate_string(oop str);
1350 
1351   // Perform any cleanup actions necessary before allowing a verification.
1352   virtual void prepare_for_verify();
1353 
1354   // Perform verification.
1355 
1356   // vo == UsePrevMarking -> use "prev" marking information,
1357   // vo == UseNextMarking -> use "next" marking information
1358   // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1359   //
1360   // NOTE: Only the "prev" marking information is guaranteed to be
1361   // consistent most of the time, so most calls to this should use
1362   // vo == UsePrevMarking.
1363   // Currently, there is only one case where this is called with
1364   // vo == UseNextMarking, which is to verify the "next" marking
1365   // information at the end of remark.
1366   // Currently there is only one place where this is called with
1367   // vo == UseFullMarking, which is to verify the marking during a
1368   // full GC.
1369   void verify(VerifyOption vo);
1370 
1371   // WhiteBox testing support.
1372   virtual bool supports_concurrent_phase_control() const;
1373   virtual bool request_concurrent_phase(const char* phase);
1374   bool is_heterogeneous_heap() const;
1375 
1376   virtual WorkGang* get_safepoint_workers() { return _workers; }
1377 
1378   // The methods below are here for convenience and dispatch the
1379   // appropriate method depending on value of the given VerifyOption
1380   // parameter. The values for that parameter, and their meanings,
1381   // are the same as those above.
1382 
1383   bool is_obj_dead_cond(const oop obj,
1384                         const HeapRegion* hr,
1385                         const VerifyOption vo) const;
1386 
1387   bool is_obj_dead_cond(const oop obj,
1388                         const VerifyOption vo) const;
1389 
1390   G1HeapSummary create_g1_heap_summary();
1391   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1392 
1393   // Printing
1394 private:
1395   void print_heap_regions() const;
1396   void print_regions_on(outputStream* st) const;
1397 
1398 public:
1399   virtual void print_on(outputStream* st) const;
1400   virtual void print_extended_on(outputStream* st) const;
1401   virtual void print_on_error(outputStream* st) const;
1402 
1403   virtual void print_gc_threads_on(outputStream* st) const;
1404   virtual void gc_threads_do(ThreadClosure* tc) const;
1405 
1406   // Override
1407   void print_tracing_info() const;
1408 
1409   // The following two methods are helpful for debugging RSet issues.
1410   void print_cset_rsets() PRODUCT_RETURN;
1411   void print_all_rsets() PRODUCT_RETURN;
1412 
1413   size_t pending_card_num();
1414 };
1415 
1416 class G1ParEvacuateFollowersClosure : public VoidClosure {
1417 private:
1418   double _start_term;
1419   double _term_time;
1420   size_t _term_attempts;
1421 
1422   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1423   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1424 protected:
1425   G1CollectedHeap*              _g1h;
1426   G1ParScanThreadState*         _par_scan_state;
1427   RefToScanQueueSet*            _queues;
1428   ParallelTaskTerminator*       _terminator;
1429   G1GCPhaseTimes::GCParPhases   _phase;
1430 
1431   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1432   RefToScanQueueSet*      queues()         { return _queues; }
1433   ParallelTaskTerminator* terminator()     { return _terminator; }
1434 
1435 public:
1436   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1437                                 G1ParScanThreadState* par_scan_state,
1438                                 RefToScanQueueSet* queues,
1439                                 ParallelTaskTerminator* terminator,
1440                                 G1GCPhaseTimes::GCParPhases phase)
1441     : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1442       _g1h(g1h), _par_scan_state(par_scan_state),
1443       _queues(queues), _terminator(terminator), _phase(phase) {}
1444 
1445   void do_void();
1446 
1447   double term_time() const { return _term_time; }
1448   size_t term_attempts() const { return _term_attempts; }
1449 
1450 private:
1451   inline bool offer_termination();
1452 };
1453 
1454 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP