1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
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  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  24 
  25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
  26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
  27 
  28 #include "gc/g1/evacuationInfo.hpp"
  29 #include "gc/g1/g1BarrierSet.hpp"
  30 #include "gc/g1/g1BiasedArray.hpp"
  31 #include "gc/g1/g1CardTable.hpp"
  32 #include "gc/g1/g1CollectionSet.hpp"
  33 #include "gc/g1/g1CollectorState.hpp"
  34 #include "gc/g1/g1ConcurrentMark.hpp"
  35 #include "gc/g1/g1EdenRegions.hpp"
  36 #include "gc/g1/g1EvacFailure.hpp"
  37 #include "gc/g1/g1EvacStats.hpp"
  38 #include "gc/g1/g1HeapTransition.hpp"
  39 #include "gc/g1/g1HeapVerifier.hpp"
  40 #include "gc/g1/g1HRPrinter.hpp"
  41 #include "gc/g1/g1InCSetState.hpp"
  42 #include "gc/g1/g1MonitoringSupport.hpp"
  43 #include "gc/g1/g1SurvivorRegions.hpp"
  44 #include "gc/g1/g1YCTypes.hpp"
  45 #include "gc/g1/heapRegionManager.hpp"
  46 #include "gc/g1/heapRegionSet.hpp"
  47 #include "gc/shared/barrierSet.hpp"
  48 #include "gc/shared/collectedHeap.hpp"
  49 #include "gc/shared/gcHeapSummary.hpp"
  50 #include "gc/shared/plab.hpp"
  51 #include "gc/shared/preservedMarks.hpp"
  52 #include "gc/shared/softRefPolicy.hpp"
  53 #include "memory/memRegion.hpp"
  54 #include "utilities/stack.hpp"
  55 
  56 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  57 // It uses the "Garbage First" heap organization and algorithm, which
  58 // may combine concurrent marking with parallel, incremental compaction of
  59 // heap subsets that will yield large amounts of garbage.
  60 
  61 // Forward declarations
  62 class HeapRegion;
  63 class HRRSCleanupTask;
  64 class GenerationSpec;
  65 class G1ParScanThreadState;
  66 class G1ParScanThreadStateSet;
  67 class G1ParScanThreadState;
  68 class MemoryPool;
  69 class MemoryManager;
  70 class ObjectClosure;
  71 class SpaceClosure;
  72 class CompactibleSpaceClosure;
  73 class Space;
  74 class G1CollectionSet;
  75 class G1CollectorPolicy;
  76 class G1Policy;
  77 class G1HotCardCache;
  78 class G1RemSet;
  79 class G1YoungRemSetSamplingThread;
  80 class HeapRegionRemSetIterator;
  81 class G1ConcurrentMark;
  82 class G1ConcurrentMarkThread;
  83 class G1ConcurrentRefine;
  84 class GenerationCounters;
  85 class STWGCTimer;
  86 class G1NewTracer;
  87 class EvacuationFailedInfo;
  88 class nmethod;
  89 class WorkGang;
  90 class G1Allocator;
  91 class G1ArchiveAllocator;
  92 class G1FullGCScope;
  93 class G1HeapVerifier;
  94 class G1HeapSizingPolicy;
  95 class G1HeapSummary;
  96 class G1EvacSummary;
  97 
  98 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
  99 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
 100 
 101 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
 102 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
 103 
 104 // The G1 STW is alive closure.
 105 // An instance is embedded into the G1CH and used as the
 106 // (optional) _is_alive_non_header closure in the STW
 107 // reference processor. It is also extensively used during
 108 // reference processing during STW evacuation pauses.
 109 class G1STWIsAliveClosure : public BoolObjectClosure {
 110   G1CollectedHeap* _g1h;
 111 public:
 112   G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
 113   bool do_object_b(oop p);
 114 };
 115 
 116 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
 117   G1CollectedHeap* _g1h;
 118 public:
 119   G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
 120   bool do_object_b(oop p);
 121 };
 122 
 123 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 124  private:
 125   void reset_from_card_cache(uint start_idx, size_t num_regions);
 126  public:
 127   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 128 };
 129 
 130 class G1CollectedHeap : public CollectedHeap {
 131   friend class G1FreeCollectionSetTask;
 132   friend class VM_CollectForMetadataAllocation;
 133   friend class VM_G1CollectForAllocation;
 134   friend class VM_G1CollectFull;
 135   friend class VMStructs;
 136   friend class MutatorAllocRegion;
 137   friend class G1FullCollector;
 138   friend class G1GCAllocRegion;
 139   friend class G1HeapVerifier;
 140 
 141   // Closures used in implementation.
 142   friend class G1ParScanThreadState;
 143   friend class G1ParScanThreadStateSet;
 144   friend class G1ParTask;
 145   friend class G1PLABAllocator;
 146   friend class G1PrepareCompactClosure;
 147 
 148   // Other related classes.
 149   friend class HeapRegionClaimer;
 150 
 151   // Testing classes.
 152   friend class G1CheckCSetFastTableClosure;
 153 
 154 private:
 155   G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
 156 
 157   WorkGang* _workers;
 158   G1CollectorPolicy* _collector_policy;
 159   G1CardTable* _card_table;
 160 
 161   SoftRefPolicy      _soft_ref_policy;
 162 
 163   static size_t _humongous_object_threshold_in_words;
 164 
 165   // These sets keep track of old, archive and humongous regions respectively.
 166   HeapRegionSet _old_set;
 167   HeapRegionSet _archive_set;
 168   HeapRegionSet _humongous_set;
 169 
 170   void eagerly_reclaim_humongous_regions();
 171   // Start a new incremental collection set for the next pause.
 172   void start_new_collection_set();
 173 
 174   // The block offset table for the G1 heap.
 175   G1BlockOffsetTable* _bot;
 176 
 177   // Tears down the region sets / lists so that they are empty and the
 178   // regions on the heap do not belong to a region set / list. The
 179   // only exception is the humongous set which we leave unaltered. If
 180   // free_list_only is true, it will only tear down the master free
 181   // list. It is called before a Full GC (free_list_only == false) or
 182   // before heap shrinking (free_list_only == true).
 183   void tear_down_region_sets(bool free_list_only);
 184 
 185   // Rebuilds the region sets / lists so that they are repopulated to
 186   // reflect the contents of the heap. The only exception is the
 187   // humongous set which was not torn down in the first place. If
 188   // free_list_only is true, it will only rebuild the master free
 189   // list. It is called after a Full GC (free_list_only == false) or
 190   // after heap shrinking (free_list_only == true).
 191   void rebuild_region_sets(bool free_list_only);
 192 
 193   // Callback for region mapping changed events.
 194   G1RegionMappingChangedListener _listener;
 195 
 196   // The sequence of all heap regions in the heap.
 197   HeapRegionManager _hrm;
 198 
 199   // Manages all allocations with regions except humongous object allocations.
 200   G1Allocator* _allocator;
 201 
 202   // Manages all heap verification.
 203   G1HeapVerifier* _verifier;
 204 
 205   // Outside of GC pauses, the number of bytes used in all regions other
 206   // than the current allocation region(s).
 207   size_t _summary_bytes_used;
 208 
 209   void increase_used(size_t bytes);
 210   void decrease_used(size_t bytes);
 211 
 212   void set_used(size_t bytes);
 213 
 214   // Class that handles archive allocation ranges.
 215   G1ArchiveAllocator* _archive_allocator;
 216 
 217   // GC allocation statistics policy for survivors.
 218   G1EvacStats _survivor_evac_stats;
 219 
 220   // GC allocation statistics policy for tenured objects.
 221   G1EvacStats _old_evac_stats;
 222 
 223   // It specifies whether we should attempt to expand the heap after a
 224   // region allocation failure. If heap expansion fails we set this to
 225   // false so that we don't re-attempt the heap expansion (it's likely
 226   // that subsequent expansion attempts will also fail if one fails).
 227   // Currently, it is only consulted during GC and it's reset at the
 228   // start of each GC.
 229   bool _expand_heap_after_alloc_failure;
 230 
 231   // Helper for monitoring and management support.
 232   G1MonitoringSupport* _g1mm;
 233 
 234   // Records whether the region at the given index is (still) a
 235   // candidate for eager reclaim.  Only valid for humongous start
 236   // regions; other regions have unspecified values.  Humongous start
 237   // regions are initialized at start of collection pause, with
 238   // candidates removed from the set as they are found reachable from
 239   // roots or the young generation.
 240   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 241    protected:
 242     bool default_value() const { return false; }
 243    public:
 244     void clear() { G1BiasedMappedArray<bool>::clear(); }
 245     void set_candidate(uint region, bool value) {
 246       set_by_index(region, value);
 247     }
 248     bool is_candidate(uint region) {
 249       return get_by_index(region);
 250     }
 251   };
 252 
 253   HumongousReclaimCandidates _humongous_reclaim_candidates;
 254   // Stores whether during humongous object registration we found candidate regions.
 255   // If not, we can skip a few steps.
 256   bool _has_humongous_reclaim_candidates;
 257 
 258   G1HRPrinter _hr_printer;
 259 
 260   // It decides whether an explicit GC should start a concurrent cycle
 261   // instead of doing a STW GC. Currently, a concurrent cycle is
 262   // explicitly started if:
 263   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 264   // (b) cause == _g1_humongous_allocation
 265   // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 266   // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 267   // (e) cause == _wb_conc_mark
 268   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 269 
 270   // indicates whether we are in young or mixed GC mode
 271   G1CollectorState _collector_state;
 272 
 273   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 274   // concurrent cycles) we have started.
 275   volatile uint _old_marking_cycles_started;
 276 
 277   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 278   // concurrent cycles) we have completed.
 279   volatile uint _old_marking_cycles_completed;
 280 
 281   // This is a non-product method that is helpful for testing. It is
 282   // called at the end of a GC and artificially expands the heap by
 283   // allocating a number of dead regions. This way we can induce very
 284   // frequent marking cycles and stress the cleanup / concurrent
 285   // cleanup code more (as all the regions that will be allocated by
 286   // this method will be found dead by the marking cycle).
 287   void allocate_dummy_regions() PRODUCT_RETURN;
 288 
 289   // If the HR printer is active, dump the state of the regions in the
 290   // heap after a compaction.
 291   void print_hrm_post_compaction();
 292 
 293   // Create a memory mapper for auxiliary data structures of the given size and
 294   // translation factor.
 295   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 296                                                          size_t size,
 297                                                          size_t translation_factor);
 298 
 299   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 300 
 301   // These are macros so that, if the assert fires, we get the correct
 302   // line number, file, etc.
 303 
 304 #define heap_locking_asserts_params(_extra_message_)                          \
 305   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 306   (_extra_message_),                                                          \
 307   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 308   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 309   BOOL_TO_STR(Thread::current()->is_VM_thread())
 310 
 311 #define assert_heap_locked()                                                  \
 312   do {                                                                        \
 313     assert(Heap_lock->owned_by_self(),                                        \
 314            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 315   } while (0)
 316 
 317 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 318   do {                                                                        \
 319     assert(Heap_lock->owned_by_self() ||                                      \
 320            (SafepointSynchronize::is_at_safepoint() &&                        \
 321              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 322            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 323                                         "should be at a safepoint"));         \
 324   } while (0)
 325 
 326 #define assert_heap_locked_and_not_at_safepoint()                             \
 327   do {                                                                        \
 328     assert(Heap_lock->owned_by_self() &&                                      \
 329                                     !SafepointSynchronize::is_at_safepoint(), \
 330           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 331                                        "should not be at a safepoint"));      \
 332   } while (0)
 333 
 334 #define assert_heap_not_locked()                                              \
 335   do {                                                                        \
 336     assert(!Heap_lock->owned_by_self(),                                       \
 337         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 338   } while (0)
 339 
 340 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 341   do {                                                                        \
 342     assert(!Heap_lock->owned_by_self() &&                                     \
 343                                     !SafepointSynchronize::is_at_safepoint(), \
 344       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 345                                    "should not be at a safepoint"));          \
 346   } while (0)
 347 
 348 #define assert_at_safepoint_on_vm_thread()                                    \
 349   do {                                                                        \
 350     assert_at_safepoint();                                                    \
 351     assert(Thread::current_or_null() != NULL, "no current thread");           \
 352     assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
 353   } while (0)
 354 
 355   // The young region list.
 356   G1EdenRegions _eden;
 357   G1SurvivorRegions _survivor;
 358 
 359   STWGCTimer* _gc_timer_stw;
 360 
 361   G1NewTracer* _gc_tracer_stw;
 362 
 363   // The current policy object for the collector.
 364   G1Policy* _g1_policy;
 365   G1HeapSizingPolicy* _heap_sizing_policy;
 366 
 367   G1CollectionSet _collection_set;
 368 
 369   // Try to allocate a single non-humongous HeapRegion sufficient for
 370   // an allocation of the given word_size. If do_expand is true,
 371   // attempt to expand the heap if necessary to satisfy the allocation
 372   // request. If the region is to be used as an old region or for a
 373   // humongous object, set is_old to true. If not, to false.
 374   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 375 
 376   // Initialize a contiguous set of free regions of length num_regions
 377   // and starting at index first so that they appear as a single
 378   // humongous region.
 379   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 380                                                       uint num_regions,
 381                                                       size_t word_size);
 382 
 383   // Attempt to allocate a humongous object of the given size. Return
 384   // NULL if unsuccessful.
 385   HeapWord* humongous_obj_allocate(size_t word_size);
 386 
 387   // The following two methods, allocate_new_tlab() and
 388   // mem_allocate(), are the two main entry points from the runtime
 389   // into the G1's allocation routines. They have the following
 390   // assumptions:
 391   //
 392   // * They should both be called outside safepoints.
 393   //
 394   // * They should both be called without holding the Heap_lock.
 395   //
 396   // * All allocation requests for new TLABs should go to
 397   //   allocate_new_tlab().
 398   //
 399   // * All non-TLAB allocation requests should go to mem_allocate().
 400   //
 401   // * If either call cannot satisfy the allocation request using the
 402   //   current allocating region, they will try to get a new one. If
 403   //   this fails, they will attempt to do an evacuation pause and
 404   //   retry the allocation.
 405   //
 406   // * If all allocation attempts fail, even after trying to schedule
 407   //   an evacuation pause, allocate_new_tlab() will return NULL,
 408   //   whereas mem_allocate() will attempt a heap expansion and/or
 409   //   schedule a Full GC.
 410   //
 411   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 412   //   should never be called with word_size being humongous. All
 413   //   humongous allocation requests should go to mem_allocate() which
 414   //   will satisfy them with a special path.
 415 
 416   virtual HeapWord* allocate_new_tlab(size_t min_size,
 417                                       size_t requested_size,
 418                                       size_t* actual_size);
 419 
 420   virtual HeapWord* mem_allocate(size_t word_size,
 421                                  bool*  gc_overhead_limit_was_exceeded);
 422 
 423   // First-level mutator allocation attempt: try to allocate out of
 424   // the mutator alloc region without taking the Heap_lock. This
 425   // should only be used for non-humongous allocations.
 426   inline HeapWord* attempt_allocation(size_t min_word_size,
 427                                       size_t desired_word_size,
 428                                       size_t* actual_word_size);
 429 
 430   // Second-level mutator allocation attempt: take the Heap_lock and
 431   // retry the allocation attempt, potentially scheduling a GC
 432   // pause. This should only be used for non-humongous allocations.
 433   HeapWord* attempt_allocation_slow(size_t word_size);
 434 
 435   // Takes the Heap_lock and attempts a humongous allocation. It can
 436   // potentially schedule a GC pause.
 437   HeapWord* attempt_allocation_humongous(size_t word_size);
 438 
 439   // Allocation attempt that should be called during safepoints (e.g.,
 440   // at the end of a successful GC). expect_null_mutator_alloc_region
 441   // specifies whether the mutator alloc region is expected to be NULL
 442   // or not.
 443   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 444                                             bool expect_null_mutator_alloc_region);
 445 
 446   // These methods are the "callbacks" from the G1AllocRegion class.
 447 
 448   // For mutator alloc regions.
 449   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 450   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 451                                    size_t allocated_bytes);
 452 
 453   // For GC alloc regions.
 454   bool has_more_regions(InCSetState dest);
 455   HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
 456   void retire_gc_alloc_region(HeapRegion* alloc_region,
 457                               size_t allocated_bytes, InCSetState dest);
 458 
 459   // - if explicit_gc is true, the GC is for a System.gc() etc,
 460   //   otherwise it's for a failed allocation.
 461   // - if clear_all_soft_refs is true, all soft references should be
 462   //   cleared during the GC.
 463   // - it returns false if it is unable to do the collection due to the
 464   //   GC locker being active, true otherwise.
 465   bool do_full_collection(bool explicit_gc,
 466                           bool clear_all_soft_refs);
 467 
 468   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 469   virtual void do_full_collection(bool clear_all_soft_refs);
 470 
 471   // Callback from VM_G1CollectForAllocation operation.
 472   // This function does everything necessary/possible to satisfy a
 473   // failed allocation request (including collection, expansion, etc.)
 474   HeapWord* satisfy_failed_allocation(size_t word_size,
 475                                       bool* succeeded);
 476   // Internal helpers used during full GC to split it up to
 477   // increase readability.
 478   void abort_concurrent_cycle();
 479   void verify_before_full_collection(bool explicit_gc);
 480   void prepare_heap_for_full_collection();
 481   void prepare_heap_for_mutators();
 482   void abort_refinement();
 483   void verify_after_full_collection();
 484   void print_heap_after_full_collection(G1HeapTransition* heap_transition);
 485 
 486   // Helper method for satisfy_failed_allocation()
 487   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 488                                              bool do_gc,
 489                                              bool clear_all_soft_refs,
 490                                              bool expect_null_mutator_alloc_region,
 491                                              bool* gc_succeeded);
 492 
 493   // Attempting to expand the heap sufficiently
 494   // to support an allocation of the given "word_size".  If
 495   // successful, perform the allocation and return the address of the
 496   // allocated block, or else "NULL".
 497   HeapWord* expand_and_allocate(size_t word_size);
 498 
 499   // Process any reference objects discovered.
 500   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 501 
 502   // If during an initial mark pause we may install a pending list head which is not
 503   // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
 504   // to discover.
 505   void make_pending_list_reachable();
 506 
 507   // Merges the information gathered on a per-thread basis for all worker threads
 508   // during GC into global variables.
 509   void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
 510 public:
 511   G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
 512 
 513   WorkGang* workers() const { return _workers; }
 514 
 515   G1Allocator* allocator() {
 516     return _allocator;
 517   }
 518 
 519   G1HeapVerifier* verifier() {
 520     return _verifier;
 521   }
 522 
 523   G1MonitoringSupport* g1mm() {
 524     assert(_g1mm != NULL, "should have been initialized");
 525     return _g1mm;
 526   }
 527 
 528   void resize_heap_if_necessary();
 529   
 530   // Expand the garbage-first heap by at least the given size (in bytes!).
 531   // Returns true if the heap was expanded by the requested amount;
 532   // false otherwise.
 533   // (Rounds up to a HeapRegion boundary.)
 534   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 535 
 536   // Returns the PLAB statistics for a given destination.
 537   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 538 
 539   // Determines PLAB size for a given destination.
 540   inline size_t desired_plab_sz(InCSetState dest);
 541 
 542   // Do anything common to GC's.
 543   void gc_prologue(bool full);
 544   void gc_epilogue(bool full);
 545 
 546   // Does the given region fulfill remembered set based eager reclaim candidate requirements?
 547   bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
 548 
 549   // Modify the reclaim candidate set and test for presence.
 550   // These are only valid for starts_humongous regions.
 551   inline void set_humongous_reclaim_candidate(uint region, bool value);
 552   inline bool is_humongous_reclaim_candidate(uint region);
 553 
 554   // Remove from the reclaim candidate set.  Also remove from the
 555   // collection set so that later encounters avoid the slow path.
 556   inline void set_humongous_is_live(oop obj);
 557 
 558   // Register the given region to be part of the collection set.
 559   inline void register_humongous_region_with_cset(uint index);
 560   // Register regions with humongous objects (actually on the start region) in
 561   // the in_cset_fast_test table.
 562   void register_humongous_regions_with_cset();
 563   // We register a region with the fast "in collection set" test. We
 564   // simply set to true the array slot corresponding to this region.
 565   void register_young_region_with_cset(HeapRegion* r) {
 566     _in_cset_fast_test.set_in_young(r->hrm_index());
 567   }
 568   void register_old_region_with_cset(HeapRegion* r) {
 569     _in_cset_fast_test.set_in_old(r->hrm_index());
 570   }
 571   void clear_in_cset(const HeapRegion* hr) {
 572     _in_cset_fast_test.clear(hr);
 573   }
 574 
 575   void clear_cset_fast_test() {
 576     _in_cset_fast_test.clear();
 577   }
 578 
 579   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 580 
 581   // This is called at the start of either a concurrent cycle or a Full
 582   // GC to update the number of old marking cycles started.
 583   void increment_old_marking_cycles_started();
 584 
 585   // This is called at the end of either a concurrent cycle or a Full
 586   // GC to update the number of old marking cycles completed. Those two
 587   // can happen in a nested fashion, i.e., we start a concurrent
 588   // cycle, a Full GC happens half-way through it which ends first,
 589   // and then the cycle notices that a Full GC happened and ends
 590   // too. The concurrent parameter is a boolean to help us do a bit
 591   // tighter consistency checking in the method. If concurrent is
 592   // false, the caller is the inner caller in the nesting (i.e., the
 593   // Full GC). If concurrent is true, the caller is the outer caller
 594   // in this nesting (i.e., the concurrent cycle). Further nesting is
 595   // not currently supported. The end of this call also notifies
 596   // the FullGCCount_lock in case a Java thread is waiting for a full
 597   // GC to happen (e.g., it called System.gc() with
 598   // +ExplicitGCInvokesConcurrent).
 599   void increment_old_marking_cycles_completed(bool concurrent);
 600 
 601   uint old_marking_cycles_completed() {
 602     return _old_marking_cycles_completed;
 603   }
 604 
 605   G1HRPrinter* hr_printer() { return &_hr_printer; }
 606 
 607   // Allocates a new heap region instance.
 608   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 609 
 610   // Allocate the highest free region in the reserved heap. This will commit
 611   // regions as necessary.
 612   HeapRegion* alloc_highest_free_region();
 613 
 614   // Frees a non-humongous region by initializing its contents and
 615   // adding it to the free list that's passed as a parameter (this is
 616   // usually a local list which will be appended to the master free
 617   // list later). The used bytes of freed regions are accumulated in
 618   // pre_used. If skip_remset is true, the region's RSet will not be freed
 619   // up. If skip_hot_card_cache is true, the region's hot card cache will not
 620   // be freed up. The assumption is that this will be done later.
 621   // The locked parameter indicates if the caller has already taken
 622   // care of proper synchronization. This may allow some optimizations.
 623   void free_region(HeapRegion* hr,
 624                    FreeRegionList* free_list,
 625                    bool skip_remset,
 626                    bool skip_hot_card_cache = false,
 627                    bool locked = false);
 628 
 629   // It dirties the cards that cover the block so that the post
 630   // write barrier never queues anything when updating objects on this
 631   // block. It is assumed (and in fact we assert) that the block
 632   // belongs to a young region.
 633   inline void dirty_young_block(HeapWord* start, size_t word_size);
 634 
 635   // Frees a humongous region by collapsing it into individual regions
 636   // and calling free_region() for each of them. The freed regions
 637   // will be added to the free list that's passed as a parameter (this
 638   // is usually a local list which will be appended to the master free
 639   // list later).
 640   // The method assumes that only a single thread is ever calling
 641   // this for a particular region at once.
 642   void free_humongous_region(HeapRegion* hr,
 643                              FreeRegionList* free_list);
 644 
 645   // Facility for allocating in 'archive' regions in high heap memory and
 646   // recording the allocated ranges. These should all be called from the
 647   // VM thread at safepoints, without the heap lock held. They can be used
 648   // to create and archive a set of heap regions which can be mapped at the
 649   // same fixed addresses in a subsequent JVM invocation.
 650   void begin_archive_alloc_range(bool open = false);
 651 
 652   // Check if the requested size would be too large for an archive allocation.
 653   bool is_archive_alloc_too_large(size_t word_size);
 654 
 655   // Allocate memory of the requested size from the archive region. This will
 656   // return NULL if the size is too large or if no memory is available. It
 657   // does not trigger a garbage collection.
 658   HeapWord* archive_mem_allocate(size_t word_size);
 659 
 660   // Optionally aligns the end address and returns the allocated ranges in
 661   // an array of MemRegions in order of ascending addresses.
 662   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 663                                size_t end_alignment_in_bytes = 0);
 664 
 665   // Facility for allocating a fixed range within the heap and marking
 666   // the containing regions as 'archive'. For use at JVM init time, when the
 667   // caller may mmap archived heap data at the specified range(s).
 668   // Verify that the MemRegions specified in the argument array are within the
 669   // reserved heap.
 670   bool check_archive_addresses(MemRegion* range, size_t count);
 671 
 672   // Commit the appropriate G1 regions containing the specified MemRegions
 673   // and mark them as 'archive' regions. The regions in the array must be
 674   // non-overlapping and in order of ascending address.
 675   bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
 676 
 677   // Insert any required filler objects in the G1 regions around the specified
 678   // ranges to make the regions parseable. This must be called after
 679   // alloc_archive_regions, and after class loading has occurred.
 680   void fill_archive_regions(MemRegion* range, size_t count);
 681 
 682   // For each of the specified MemRegions, uncommit the containing G1 regions
 683   // which had been allocated by alloc_archive_regions. This should be called
 684   // rather than fill_archive_regions at JVM init time if the archive file
 685   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 686   void dealloc_archive_regions(MemRegion* range, size_t count);
 687 
 688   oop materialize_archived_object(oop obj);
 689 
 690 private:
 691 
 692   // Shrink the garbage-first heap by at most the given size (in bytes!).
 693   // (Rounds down to a HeapRegion boundary.)
 694   void shrink(size_t expand_bytes);
 695   void shrink_helper(size_t expand_bytes);
 696 
 697   #if TASKQUEUE_STATS
 698   static void print_taskqueue_stats_hdr(outputStream* const st);
 699   void print_taskqueue_stats() const;
 700   void reset_taskqueue_stats();
 701   #endif // TASKQUEUE_STATS
 702 
 703   // Schedule the VM operation that will do an evacuation pause to
 704   // satisfy an allocation request of word_size. *succeeded will
 705   // return whether the VM operation was successful (it did do an
 706   // evacuation pause) or not (another thread beat us to it or the GC
 707   // locker was active). Given that we should not be holding the
 708   // Heap_lock when we enter this method, we will pass the
 709   // gc_count_before (i.e., total_collections()) as a parameter since
 710   // it has to be read while holding the Heap_lock. Currently, both
 711   // methods that call do_collection_pause() release the Heap_lock
 712   // before the call, so it's easy to read gc_count_before just before.
 713   HeapWord* do_collection_pause(size_t         word_size,
 714                                 uint           gc_count_before,
 715                                 bool*          succeeded,
 716                                 GCCause::Cause gc_cause);
 717 
 718   void wait_for_root_region_scanning();
 719 
 720   // The guts of the incremental collection pause, executed by the vm
 721   // thread. It returns false if it is unable to do the collection due
 722   // to the GC locker being active, true otherwise
 723   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 724 
 725   // Actually do the work of evacuating the collection set.
 726   void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states);
 727 
 728   void pre_evacuate_collection_set();
 729   void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 730 
 731   // Print the header for the per-thread termination statistics.
 732   static void print_termination_stats_hdr();
 733   // Print actual per-thread termination statistics.
 734   void print_termination_stats(uint worker_id,
 735                                double elapsed_ms,
 736                                double strong_roots_ms,
 737                                double term_ms,
 738                                size_t term_attempts,
 739                                size_t alloc_buffer_waste,
 740                                size_t undo_waste) const;
 741   // Update object copying statistics.
 742   void record_obj_copy_mem_stats();
 743 
 744   // The hot card cache for remembered set insertion optimization.
 745   G1HotCardCache* _hot_card_cache;
 746 
 747   // The g1 remembered set of the heap.
 748   G1RemSet* _g1_rem_set;
 749 
 750   // A set of cards that cover the objects for which the Rsets should be updated
 751   // concurrently after the collection.
 752   DirtyCardQueueSet _dirty_card_queue_set;
 753 
 754   // After a collection pause, convert the regions in the collection set into free
 755   // regions.
 756   void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 757 
 758   // Abandon the current collection set without recording policy
 759   // statistics or updating free lists.
 760   void abandon_collection_set(G1CollectionSet* collection_set);
 761 
 762   // The concurrent marker (and the thread it runs in.)
 763   G1ConcurrentMark* _cm;
 764   G1ConcurrentMarkThread* _cm_thread;
 765 
 766   // The concurrent refiner.
 767   G1ConcurrentRefine* _cr;
 768 
 769   // The parallel task queues
 770   RefToScanQueueSet *_task_queues;
 771 
 772   // True iff a evacuation has failed in the current collection.
 773   bool _evacuation_failed;
 774 
 775   EvacuationFailedInfo* _evacuation_failed_info_array;
 776 
 777   // Failed evacuations cause some logical from-space objects to have
 778   // forwarding pointers to themselves.  Reset them.
 779   void remove_self_forwarding_pointers();
 780 
 781   // Restore the objects in the regions in the collection set after an
 782   // evacuation failure.
 783   void restore_after_evac_failure();
 784 
 785   PreservedMarksSet _preserved_marks_set;
 786 
 787   // Preserve the mark of "obj", if necessary, in preparation for its mark
 788   // word being overwritten with a self-forwarding-pointer.
 789   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 790 
 791 #ifndef PRODUCT
 792   // Support for forcing evacuation failures. Analogous to
 793   // PromotionFailureALot for the other collectors.
 794 
 795   // Records whether G1EvacuationFailureALot should be in effect
 796   // for the current GC
 797   bool _evacuation_failure_alot_for_current_gc;
 798 
 799   // Used to record the GC number for interval checking when
 800   // determining whether G1EvaucationFailureALot is in effect
 801   // for the current GC.
 802   size_t _evacuation_failure_alot_gc_number;
 803 
 804   // Count of the number of evacuations between failures.
 805   volatile size_t _evacuation_failure_alot_count;
 806 
 807   // Set whether G1EvacuationFailureALot should be in effect
 808   // for the current GC (based upon the type of GC and which
 809   // command line flags are set);
 810   inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
 811                                                   bool during_initial_mark,
 812                                                   bool mark_or_rebuild_in_progress);
 813 
 814   inline void set_evacuation_failure_alot_for_current_gc();
 815 
 816   // Return true if it's time to cause an evacuation failure.
 817   inline bool evacuation_should_fail();
 818 
 819   // Reset the G1EvacuationFailureALot counters.  Should be called at
 820   // the end of an evacuation pause in which an evacuation failure occurred.
 821   inline void reset_evacuation_should_fail();
 822 #endif // !PRODUCT
 823 
 824   // ("Weak") Reference processing support.
 825   //
 826   // G1 has 2 instances of the reference processor class. One
 827   // (_ref_processor_cm) handles reference object discovery
 828   // and subsequent processing during concurrent marking cycles.
 829   //
 830   // The other (_ref_processor_stw) handles reference object
 831   // discovery and processing during full GCs and incremental
 832   // evacuation pauses.
 833   //
 834   // During an incremental pause, reference discovery will be
 835   // temporarily disabled for _ref_processor_cm and will be
 836   // enabled for _ref_processor_stw. At the end of the evacuation
 837   // pause references discovered by _ref_processor_stw will be
 838   // processed and discovery will be disabled. The previous
 839   // setting for reference object discovery for _ref_processor_cm
 840   // will be re-instated.
 841   //
 842   // At the start of marking:
 843   //  * Discovery by the CM ref processor is verified to be inactive
 844   //    and it's discovered lists are empty.
 845   //  * Discovery by the CM ref processor is then enabled.
 846   //
 847   // At the end of marking:
 848   //  * Any references on the CM ref processor's discovered
 849   //    lists are processed (possibly MT).
 850   //
 851   // At the start of full GC we:
 852   //  * Disable discovery by the CM ref processor and
 853   //    empty CM ref processor's discovered lists
 854   //    (without processing any entries).
 855   //  * Verify that the STW ref processor is inactive and it's
 856   //    discovered lists are empty.
 857   //  * Temporarily set STW ref processor discovery as single threaded.
 858   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 859   //    field.
 860   //  * Finally enable discovery by the STW ref processor.
 861   //
 862   // The STW ref processor is used to record any discovered
 863   // references during the full GC.
 864   //
 865   // At the end of a full GC we:
 866   //  * Enqueue any reference objects discovered by the STW ref processor
 867   //    that have non-live referents. This has the side-effect of
 868   //    making the STW ref processor inactive by disabling discovery.
 869   //  * Verify that the CM ref processor is still inactive
 870   //    and no references have been placed on it's discovered
 871   //    lists (also checked as a precondition during initial marking).
 872 
 873   // The (stw) reference processor...
 874   ReferenceProcessor* _ref_processor_stw;
 875 
 876   // During reference object discovery, the _is_alive_non_header
 877   // closure (if non-null) is applied to the referent object to
 878   // determine whether the referent is live. If so then the
 879   // reference object does not need to be 'discovered' and can
 880   // be treated as a regular oop. This has the benefit of reducing
 881   // the number of 'discovered' reference objects that need to
 882   // be processed.
 883   //
 884   // Instance of the is_alive closure for embedding into the
 885   // STW reference processor as the _is_alive_non_header field.
 886   // Supplying a value for the _is_alive_non_header field is
 887   // optional but doing so prevents unnecessary additions to
 888   // the discovered lists during reference discovery.
 889   G1STWIsAliveClosure _is_alive_closure_stw;
 890 
 891   G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
 892 
 893   // The (concurrent marking) reference processor...
 894   ReferenceProcessor* _ref_processor_cm;
 895 
 896   // Instance of the concurrent mark is_alive closure for embedding
 897   // into the Concurrent Marking reference processor as the
 898   // _is_alive_non_header field. Supplying a value for the
 899   // _is_alive_non_header field is optional but doing so prevents
 900   // unnecessary additions to the discovered lists during reference
 901   // discovery.
 902   G1CMIsAliveClosure _is_alive_closure_cm;
 903 
 904   G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
 905 public:
 906 
 907   RefToScanQueue *task_queue(uint i) const;
 908 
 909   uint num_task_queues() const;
 910 
 911   // A set of cards where updates happened during the GC
 912   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 913 
 914   // Create a G1CollectedHeap with the specified policy.
 915   // Must call the initialize method afterwards.
 916   // May not return if something goes wrong.
 917   G1CollectedHeap(G1CollectorPolicy* policy);
 918 
 919 private:
 920   jint initialize_concurrent_refinement();
 921   jint initialize_young_gen_sampling_thread();
 922 public:
 923   // Initialize the G1CollectedHeap to have the initial and
 924   // maximum sizes and remembered and barrier sets
 925   // specified by the policy object.
 926   jint initialize();
 927 
 928   virtual void stop();
 929   virtual void safepoint_synchronize_begin();
 930   virtual void safepoint_synchronize_end();
 931 
 932   // Return the (conservative) maximum heap alignment for any G1 heap
 933   static size_t conservative_max_heap_alignment();
 934 
 935   // Does operations required after initialization has been done.
 936   void post_initialize();
 937 
 938   // Initialize weak reference processing.
 939   void ref_processing_init();
 940 
 941   virtual Name kind() const {
 942     return CollectedHeap::G1;
 943   }
 944 
 945   virtual const char* name() const {
 946     return "G1";
 947   }
 948 
 949   const G1CollectorState* collector_state() const { return &_collector_state; }
 950   G1CollectorState* collector_state() { return &_collector_state; }
 951 
 952   // The current policy object for the collector.
 953   G1Policy* g1_policy() const { return _g1_policy; }
 954 
 955   const G1CollectionSet* collection_set() const { return &_collection_set; }
 956   G1CollectionSet* collection_set() { return &_collection_set; }
 957 
 958   virtual CollectorPolicy* collector_policy() const;
 959 
 960   virtual SoftRefPolicy* soft_ref_policy();
 961 
 962   virtual void initialize_serviceability();
 963   virtual MemoryUsage memory_usage();
 964   virtual GrowableArray<GCMemoryManager*> memory_managers();
 965   virtual GrowableArray<MemoryPool*> memory_pools();
 966 
 967   // The rem set and barrier set.
 968   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
 969 
 970   // Try to minimize the remembered set.
 971   void scrub_rem_set();
 972 
 973   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
 974   void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
 975 
 976   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
 977   void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
 978 
 979   // The shared block offset table array.
 980   G1BlockOffsetTable* bot() const { return _bot; }
 981 
 982   // Reference Processing accessors
 983 
 984   // The STW reference processor....
 985   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
 986 
 987   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
 988 
 989   // The Concurrent Marking reference processor...
 990   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
 991 
 992   size_t unused_committed_regions_in_bytes() const;
 993   virtual size_t capacity() const;
 994   virtual size_t used() const;
 995   // This should be called when we're not holding the heap lock. The
 996   // result might be a bit inaccurate.
 997   size_t used_unlocked() const;
 998   size_t recalculate_used() const;
 999 
1000   // These virtual functions do the actual allocation.
1001   // Some heaps may offer a contiguous region for shared non-blocking
1002   // allocation, via inlined code (by exporting the address of the top and
1003   // end fields defining the extent of the contiguous allocation region.)
1004   // But G1CollectedHeap doesn't yet support this.
1005 
1006   virtual bool is_maximal_no_gc() const {
1007     return _hrm.available() == 0;
1008   }
1009 
1010   // Returns whether there are any regions left in the heap for allocation.
1011   bool has_regions_left_for_allocation() const {
1012     return !is_maximal_no_gc() || num_free_regions() != 0;
1013   }
1014 
1015   // The current number of regions in the heap.
1016   uint num_regions() const { return _hrm.length(); }
1017 
1018   // The max number of regions in the heap.
1019   uint max_regions() const { return _hrm.max_length(); }
1020 
1021   // The number of regions that are completely free.
1022   uint num_free_regions() const { return _hrm.num_free_regions(); }
1023 
1024   MemoryUsage get_auxiliary_data_memory_usage() const {
1025     return _hrm.get_auxiliary_data_memory_usage();
1026   }
1027 
1028   // The number of regions that are not completely free.
1029   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1030 
1031 #ifdef ASSERT
1032   bool is_on_master_free_list(HeapRegion* hr) {
1033     return _hrm.is_free(hr);
1034   }
1035 #endif // ASSERT
1036 
1037   inline void old_set_add(HeapRegion* hr);
1038   inline void old_set_remove(HeapRegion* hr);
1039 
1040   inline void archive_set_add(HeapRegion* hr);
1041 
1042   size_t non_young_capacity_bytes() {
1043     return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1044   }
1045 
1046   // Determine whether the given region is one that we are using as an
1047   // old GC alloc region.
1048   bool is_old_gc_alloc_region(HeapRegion* hr);
1049 
1050   // Perform a collection of the heap; intended for use in implementing
1051   // "System.gc".  This probably implies as full a collection as the
1052   // "CollectedHeap" supports.
1053   virtual void collect(GCCause::Cause cause);
1054 
1055   // True iff an evacuation has failed in the most-recent collection.
1056   bool evacuation_failed() { return _evacuation_failed; }
1057 
1058   void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1059   void prepend_to_freelist(FreeRegionList* list);
1060   void decrement_summary_bytes(size_t bytes);
1061 
1062   virtual bool is_in(const void* p) const;
1063 #ifdef ASSERT
1064   // Returns whether p is in one of the available areas of the heap. Slow but
1065   // extensive version.
1066   bool is_in_exact(const void* p) const;
1067 #endif
1068 
1069   // Return "TRUE" iff the given object address is within the collection
1070   // set. Assumes that the reference points into the heap.
1071   inline bool is_in_cset(const HeapRegion *hr);
1072   inline bool is_in_cset(oop obj);
1073   inline bool is_in_cset(HeapWord* addr);
1074 
1075   inline bool is_in_cset_or_humongous(const oop obj);
1076 
1077  private:
1078   // This array is used for a quick test on whether a reference points into
1079   // the collection set or not. Each of the array's elements denotes whether the
1080   // corresponding region is in the collection set or not.
1081   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1082 
1083  public:
1084 
1085   inline InCSetState in_cset_state(const oop obj);
1086 
1087   // Return "TRUE" iff the given object address is in the reserved
1088   // region of g1.
1089   bool is_in_g1_reserved(const void* p) const {
1090     return _hrm.reserved().contains(p);
1091   }
1092 
1093   // Returns a MemRegion that corresponds to the space that has been
1094   // reserved for the heap
1095   MemRegion g1_reserved() const {
1096     return _hrm.reserved();
1097   }
1098 
1099   virtual bool is_in_closed_subset(const void* p) const;
1100 
1101   G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1102 
1103   G1CardTable* card_table() const {
1104     return _card_table;
1105   }
1106 
1107   // Iteration functions.
1108 
1109   // Iterate over all objects, calling "cl.do_object" on each.
1110   virtual void object_iterate(ObjectClosure* cl);
1111 
1112   virtual void safe_object_iterate(ObjectClosure* cl) {
1113     object_iterate(cl);
1114   }
1115 
1116   // Iterate over heap regions, in address order, terminating the
1117   // iteration early if the "do_heap_region" method returns "true".
1118   void heap_region_iterate(HeapRegionClosure* blk) const;
1119 
1120   // Return the region with the given index. It assumes the index is valid.
1121   inline HeapRegion* region_at(uint index) const;
1122   inline HeapRegion* region_at_or_null(uint index) const;
1123 
1124   // Return the next region (by index) that is part of the same
1125   // humongous object that hr is part of.
1126   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1127 
1128   // Calculate the region index of the given address. Given address must be
1129   // within the heap.
1130   inline uint addr_to_region(HeapWord* addr) const;
1131 
1132   inline HeapWord* bottom_addr_for_region(uint index) const;
1133 
1134   // Two functions to iterate over the heap regions in parallel. Threads
1135   // compete using the HeapRegionClaimer to claim the regions before
1136   // applying the closure on them.
1137   // The _from_worker_offset version uses the HeapRegionClaimer and
1138   // the worker id to calculate a start offset to prevent all workers to
1139   // start from the point.
1140   void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1141                                                   HeapRegionClaimer* hrclaimer,
1142                                                   uint worker_id) const;
1143 
1144   void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1145                                           HeapRegionClaimer* hrclaimer) const;
1146 
1147   // Iterate over the regions (if any) in the current collection set.
1148   void collection_set_iterate(HeapRegionClosure* blk);
1149 
1150   // Iterate over the regions (if any) in the current collection set. Starts the
1151   // iteration over the entire collection set so that the start regions of a given
1152   // worker id over the set active_workers are evenly spread across the set of
1153   // collection set regions.
1154   void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1155 
1156   // Returns the HeapRegion that contains addr. addr must not be NULL.
1157   template <class T>
1158   inline HeapRegion* heap_region_containing(const T addr) const;
1159 
1160   // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1161   // region. addr must not be NULL.
1162   template <class T>
1163   inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1164 
1165   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1166   // each address in the (reserved) heap is a member of exactly
1167   // one block.  The defining characteristic of a block is that it is
1168   // possible to find its size, and thus to progress forward to the next
1169   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1170   // represent Java objects, or they might be free blocks in a
1171   // free-list-based heap (or subheap), as long as the two kinds are
1172   // distinguishable and the size of each is determinable.
1173 
1174   // Returns the address of the start of the "block" that contains the
1175   // address "addr".  We say "blocks" instead of "object" since some heaps
1176   // may not pack objects densely; a chunk may either be an object or a
1177   // non-object.
1178   virtual HeapWord* block_start(const void* addr) const;
1179 
1180   // Requires "addr" to be the start of a chunk, and returns its size.
1181   // "addr + size" is required to be the start of a new chunk, or the end
1182   // of the active area of the heap.
1183   virtual size_t block_size(const HeapWord* addr) const;
1184 
1185   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1186   // the block is an object.
1187   virtual bool block_is_obj(const HeapWord* addr) const;
1188 
1189   // Section on thread-local allocation buffers (TLABs)
1190   // See CollectedHeap for semantics.
1191 
1192   bool supports_tlab_allocation() const;
1193   size_t tlab_capacity(Thread* ignored) const;
1194   size_t tlab_used(Thread* ignored) const;
1195   size_t max_tlab_size() const;
1196   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1197 
1198   inline bool is_in_young(const oop obj);
1199 
1200   // Returns "true" iff the given word_size is "very large".
1201   static bool is_humongous(size_t word_size) {
1202     // Note this has to be strictly greater-than as the TLABs
1203     // are capped at the humongous threshold and we want to
1204     // ensure that we don't try to allocate a TLAB as
1205     // humongous and that we don't allocate a humongous
1206     // object in a TLAB.
1207     return word_size > _humongous_object_threshold_in_words;
1208   }
1209 
1210   // Returns the humongous threshold for a specific region size
1211   static size_t humongous_threshold_for(size_t region_size) {
1212     return (region_size / 2);
1213   }
1214 
1215   // Returns the number of regions the humongous object of the given word size
1216   // requires.
1217   static size_t humongous_obj_size_in_regions(size_t word_size);
1218 
1219   // Print the maximum heap capacity.
1220   virtual size_t max_capacity() const;
1221 
1222   virtual jlong millis_since_last_gc();
1223 
1224 
1225   // Convenience function to be used in situations where the heap type can be
1226   // asserted to be this type.
1227   static G1CollectedHeap* heap();
1228 
1229   void set_region_short_lived_locked(HeapRegion* hr);
1230   // add appropriate methods for any other surv rate groups
1231 
1232   const G1SurvivorRegions* survivor() const { return &_survivor; }
1233 
1234   uint eden_regions_count() const { return _eden.length(); }
1235   uint survivor_regions_count() const { return _survivor.length(); }
1236   uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1237   uint old_regions_count() const { return _old_set.length(); }
1238   uint archive_regions_count() const { return _archive_set.length(); }
1239   uint humongous_regions_count() const { return _humongous_set.length(); }
1240 
1241 #ifdef ASSERT
1242   bool check_young_list_empty();
1243 #endif
1244 
1245   // *** Stuff related to concurrent marking.  It's not clear to me that so
1246   // many of these need to be public.
1247 
1248   // The functions below are helper functions that a subclass of
1249   // "CollectedHeap" can use in the implementation of its virtual
1250   // functions.
1251   // This performs a concurrent marking of the live objects in a
1252   // bitmap off to the side.
1253   void do_concurrent_mark();
1254 
1255   bool is_marked_next(oop obj) const;
1256 
1257   // Determine if an object is dead, given the object and also
1258   // the region to which the object belongs. An object is dead
1259   // iff a) it was not allocated since the last mark, b) it
1260   // is not marked, and c) it is not in an archive region.
1261   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1262     return
1263       hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1264       !hr->is_archive();
1265   }
1266 
1267   // This function returns true when an object has been
1268   // around since the previous marking and hasn't yet
1269   // been marked during this marking, and is not in an archive region.
1270   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1271     return
1272       !hr->obj_allocated_since_next_marking(obj) &&
1273       !is_marked_next(obj) &&
1274       !hr->is_archive();
1275   }
1276 
1277   // Determine if an object is dead, given only the object itself.
1278   // This will find the region to which the object belongs and
1279   // then call the region version of the same function.
1280 
1281   // Added if it is NULL it isn't dead.
1282 
1283   inline bool is_obj_dead(const oop obj) const;
1284 
1285   inline bool is_obj_ill(const oop obj) const;
1286 
1287   inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1288   inline bool is_obj_dead_full(const oop obj) const;
1289 
1290   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1291 
1292   // Refinement
1293 
1294   G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1295 
1296   // Optimized nmethod scanning support routines
1297 
1298   // Is an oop scavengeable
1299   virtual bool is_scavengable(oop obj);
1300 
1301   // Register the given nmethod with the G1 heap.
1302   virtual void register_nmethod(nmethod* nm);
1303 
1304   // Unregister the given nmethod from the G1 heap.
1305   virtual void unregister_nmethod(nmethod* nm);
1306 
1307   // Free up superfluous code root memory.
1308   void purge_code_root_memory();
1309 
1310   // Rebuild the strong code root lists for each region
1311   // after a full GC.
1312   void rebuild_strong_code_roots();
1313 
1314   // Partial cleaning used when class unloading is disabled.
1315   // Let the caller choose what structures to clean out:
1316   // - StringTable
1317   // - StringDeduplication structures
1318   void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_string_dedup);
1319 
1320   // Complete cleaning used when class unloading is enabled.
1321   // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1322   void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1323 
1324   // Redirty logged cards in the refinement queue.
1325   void redirty_logged_cards();
1326   // Verification
1327 
1328   // Deduplicate the string
1329   virtual void deduplicate_string(oop str);
1330 
1331   // Perform any cleanup actions necessary before allowing a verification.
1332   virtual void prepare_for_verify();
1333 
1334   // Perform verification.
1335 
1336   // vo == UsePrevMarking -> use "prev" marking information,
1337   // vo == UseNextMarking -> use "next" marking information
1338   // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1339   //
1340   // NOTE: Only the "prev" marking information is guaranteed to be
1341   // consistent most of the time, so most calls to this should use
1342   // vo == UsePrevMarking.
1343   // Currently, there is only one case where this is called with
1344   // vo == UseNextMarking, which is to verify the "next" marking
1345   // information at the end of remark.
1346   // Currently there is only one place where this is called with
1347   // vo == UseFullMarking, which is to verify the marking during a
1348   // full GC.
1349   void verify(VerifyOption vo);
1350 
1351   // WhiteBox testing support.
1352   virtual bool supports_concurrent_phase_control() const;
1353   virtual const char* const* concurrent_phases() const;
1354   virtual bool request_concurrent_phase(const char* phase);
1355 
1356   virtual WorkGang* get_safepoint_workers() { return _workers; }
1357 
1358   // The methods below are here for convenience and dispatch the
1359   // appropriate method depending on value of the given VerifyOption
1360   // parameter. The values for that parameter, and their meanings,
1361   // are the same as those above.
1362 
1363   bool is_obj_dead_cond(const oop obj,
1364                         const HeapRegion* hr,
1365                         const VerifyOption vo) const;
1366 
1367   bool is_obj_dead_cond(const oop obj,
1368                         const VerifyOption vo) const;
1369 
1370   G1HeapSummary create_g1_heap_summary();
1371   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1372 
1373   // Printing
1374 private:
1375   void print_heap_regions() const;
1376   void print_regions_on(outputStream* st) const;
1377 
1378 public:
1379   virtual void print_on(outputStream* st) const;
1380   virtual void print_extended_on(outputStream* st) const;
1381   virtual void print_on_error(outputStream* st) const;
1382 
1383   virtual void print_gc_threads_on(outputStream* st) const;
1384   virtual void gc_threads_do(ThreadClosure* tc) const;
1385 
1386   // Override
1387   void print_tracing_info() const;
1388 
1389   // The following two methods are helpful for debugging RSet issues.
1390   void print_cset_rsets() PRODUCT_RETURN;
1391   void print_all_rsets() PRODUCT_RETURN;
1392 
1393   size_t pending_card_num();
1394 };
1395 
1396 class G1ParEvacuateFollowersClosure : public VoidClosure {
1397 private:
1398   double _start_term;
1399   double _term_time;
1400   size_t _term_attempts;
1401 
1402   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1403   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1404 protected:
1405   G1CollectedHeap*              _g1h;
1406   G1ParScanThreadState*         _par_scan_state;
1407   RefToScanQueueSet*            _queues;
1408   ParallelTaskTerminator*       _terminator;
1409 
1410   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1411   RefToScanQueueSet*      queues()         { return _queues; }
1412   ParallelTaskTerminator* terminator()     { return _terminator; }
1413 
1414 public:
1415   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1416                                 G1ParScanThreadState* par_scan_state,
1417                                 RefToScanQueueSet* queues,
1418                                 ParallelTaskTerminator* terminator)
1419     : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1420       _g1h(g1h), _par_scan_state(par_scan_state),
1421       _queues(queues), _terminator(terminator) {}
1422 
1423   void do_void();
1424 
1425   double term_time() const { return _term_time; }
1426   size_t term_attempts() const { return _term_attempts; }
1427 
1428 private:
1429   inline bool offer_termination();
1430 };
1431 
1432 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP