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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   // The young region list.
 361   G1EdenRegions _eden;
 362   G1SurvivorRegions _survivor;
 363 
 364   STWGCTimer* _gc_timer_stw;
 365 
 366   G1NewTracer* _gc_tracer_stw;
 367 
 368   // The current policy object for the collector.
 369   G1Policy* _policy;
 370   G1HeapSizingPolicy* _heap_sizing_policy;
 371 
 372   G1CollectionSet _collection_set;
 373 
 374   // Try to allocate a single non-humongous HeapRegion sufficient for
 375   // an allocation of the given word_size. If do_expand is true,
 376   // attempt to expand the heap if necessary to satisfy the allocation
 377   // request. 'type' takes the type of region to be allocated. (Use constants
 378   // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
 379   HeapRegion* new_region(size_t word_size, HeapRegionType type, bool do_expand);
 380 
 381   // Initialize a contiguous set of free regions of length num_regions
 382   // and starting at index first so that they appear as a single
 383   // humongous region.
 384   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 385                                                       uint num_regions,
 386                                                       size_t word_size);
 387 
 388   // Attempt to allocate a humongous object of the given size. Return
 389   // NULL if unsuccessful.
 390   HeapWord* humongous_obj_allocate(size_t word_size);
 391 
 392   // The following two methods, allocate_new_tlab() and
 393   // mem_allocate(), are the two main entry points from the runtime
 394   // into the G1's allocation routines. They have the following
 395   // assumptions:
 396   //
 397   // * They should both be called outside safepoints.
 398   //
 399   // * They should both be called without holding the Heap_lock.
 400   //
 401   // * All allocation requests for new TLABs should go to
 402   //   allocate_new_tlab().
 403   //
 404   // * All non-TLAB allocation requests should go to mem_allocate().
 405   //
 406   // * If either call cannot satisfy the allocation request using the
 407   //   current allocating region, they will try to get a new one. If
 408   //   this fails, they will attempt to do an evacuation pause and
 409   //   retry the allocation.
 410   //
 411   // * If all allocation attempts fail, even after trying to schedule
 412   //   an evacuation pause, allocate_new_tlab() will return NULL,
 413   //   whereas mem_allocate() will attempt a heap expansion and/or
 414   //   schedule a Full GC.
 415   //
 416   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 417   //   should never be called with word_size being humongous. All
 418   //   humongous allocation requests should go to mem_allocate() which
 419   //   will satisfy them with a special path.
 420 
 421   virtual HeapWord* allocate_new_tlab(size_t min_size,
 422                                       size_t requested_size,
 423                                       size_t* actual_size);
 424 
 425   virtual HeapWord* mem_allocate(size_t word_size,
 426                                  bool*  gc_overhead_limit_was_exceeded);
 427 
 428   // First-level mutator allocation attempt: try to allocate out of
 429   // the mutator alloc region without taking the Heap_lock. This
 430   // should only be used for non-humongous allocations.
 431   inline HeapWord* attempt_allocation(size_t min_word_size,
 432                                       size_t desired_word_size,
 433                                       size_t* actual_word_size);
 434 
 435   // Second-level mutator allocation attempt: take the Heap_lock and
 436   // retry the allocation attempt, potentially scheduling a GC
 437   // pause. This should only be used for non-humongous allocations.
 438   HeapWord* attempt_allocation_slow(size_t word_size);
 439 
 440   // Takes the Heap_lock and attempts a humongous allocation. It can
 441   // potentially schedule a GC pause.
 442   HeapWord* attempt_allocation_humongous(size_t word_size);
 443 
 444   // Allocation attempt that should be called during safepoints (e.g.,
 445   // at the end of a successful GC). expect_null_mutator_alloc_region
 446   // specifies whether the mutator alloc region is expected to be NULL
 447   // or not.
 448   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 449                                             bool expect_null_mutator_alloc_region);
 450 
 451   // These methods are the "callbacks" from the G1AllocRegion class.
 452 
 453   // For mutator alloc regions.
 454   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 455   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 456                                    size_t allocated_bytes);
 457 
 458   // For GC alloc regions.
 459   bool has_more_regions(InCSetState dest);
 460   HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
 461   void retire_gc_alloc_region(HeapRegion* alloc_region,
 462                               size_t allocated_bytes, InCSetState dest);
 463 
 464   // - if explicit_gc is true, the GC is for a System.gc() etc,
 465   //   otherwise it's for a failed allocation.
 466   // - if clear_all_soft_refs is true, all soft references should be
 467   //   cleared during the GC.
 468   // - it returns false if it is unable to do the collection due to the
 469   //   GC locker being active, true otherwise.
 470   bool do_full_collection(bool explicit_gc,
 471                           bool clear_all_soft_refs);
 472 
 473   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 474   virtual void do_full_collection(bool clear_all_soft_refs);
 475 
 476   // Callback from VM_G1CollectForAllocation operation.
 477   // This function does everything necessary/possible to satisfy a
 478   // failed allocation request (including collection, expansion, etc.)
 479   HeapWord* satisfy_failed_allocation(size_t word_size,
 480                                       bool* succeeded);
 481   // Internal helpers used during full GC to split it up to
 482   // increase readability.
 483   void abort_concurrent_cycle();
 484   void verify_before_full_collection(bool explicit_gc);
 485   void prepare_heap_for_full_collection();
 486   void prepare_heap_for_mutators();
 487   void abort_refinement();
 488   void verify_after_full_collection();
 489   void print_heap_after_full_collection(G1HeapTransition* heap_transition);
 490 
 491   // Helper method for satisfy_failed_allocation()
 492   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 493                                              bool do_gc,
 494                                              bool clear_all_soft_refs,
 495                                              bool expect_null_mutator_alloc_region,
 496                                              bool* gc_succeeded);
 497 
 498   // Attempting to expand the heap sufficiently
 499   // to support an allocation of the given "word_size".  If
 500   // successful, perform the allocation and return the address of the
 501   // allocated block, or else "NULL".
 502   HeapWord* expand_and_allocate(size_t word_size);
 503 
 504   // Process any reference objects discovered.
 505   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 506 
 507   // If during an initial mark pause we may install a pending list head which is not
 508   // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
 509   // to discover.
 510   void make_pending_list_reachable();
 511 
 512   // Merges the information gathered on a per-thread basis for all worker threads
 513   // during GC into global variables.
 514   void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
 515 public:
 516   G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
 517 
 518   WorkGang* workers() const { return _workers; }
 519 
 520   G1Allocator* allocator() {
 521     return _allocator;
 522   }
 523 
 524   G1HeapVerifier* verifier() {
 525     return _verifier;
 526   }
 527 
 528   G1MonitoringSupport* g1mm() {
 529     assert(_g1mm != NULL, "should have been initialized");
 530     return _g1mm;
 531   }
 532 
 533   void resize_heap_if_necessary();
 534 
 535   // Expand the garbage-first heap by at least the given size (in bytes!).
 536   // Returns true if the heap was expanded by the requested amount;
 537   // false otherwise.
 538   // (Rounds up to a HeapRegion boundary.)
 539   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 540 
 541   // Returns the PLAB statistics for a given destination.
 542   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 543 
 544   // Determines PLAB size for a given destination.
 545   inline size_t desired_plab_sz(InCSetState dest);
 546 
 547   // Do anything common to GC's.
 548   void gc_prologue(bool full);
 549   void gc_epilogue(bool full);
 550 
 551   // Does the given region fulfill remembered set based eager reclaim candidate requirements?
 552   bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
 553 
 554   // Modify the reclaim candidate set and test for presence.
 555   // These are only valid for starts_humongous regions.
 556   inline void set_humongous_reclaim_candidate(uint region, bool value);
 557   inline bool is_humongous_reclaim_candidate(uint region);
 558 
 559   // Remove from the reclaim candidate set.  Also remove from the
 560   // collection set so that later encounters avoid the slow path.
 561   inline void set_humongous_is_live(oop obj);
 562 
 563   // Register the given region to be part of the collection set.
 564   inline void register_humongous_region_with_cset(uint index);
 565   // Register regions with humongous objects (actually on the start region) in
 566   // the in_cset_fast_test table.
 567   void register_humongous_regions_with_cset();
 568   // We register a region with the fast "in collection set" test. We
 569   // simply set to true the array slot corresponding to this region.
 570   void register_young_region_with_cset(HeapRegion* r) {
 571     _in_cset_fast_test.set_in_young(r->hrm_index());
 572   }
 573   void register_old_region_with_cset(HeapRegion* r) {
 574     _in_cset_fast_test.set_in_old(r->hrm_index());
 575   }
 576   void register_optional_region_with_cset(HeapRegion* r) {
 577     _in_cset_fast_test.set_optional(r->hrm_index());
 578   }
 579   void clear_in_cset(const HeapRegion* hr) {
 580     _in_cset_fast_test.clear(hr);
 581   }
 582 
 583   void clear_cset_fast_test() {
 584     _in_cset_fast_test.clear();
 585   }
 586 
 587   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 588 
 589   // This is called at the start of either a concurrent cycle or a Full
 590   // GC to update the number of old marking cycles started.
 591   void increment_old_marking_cycles_started();
 592 
 593   // This is called at the end of either a concurrent cycle or a Full
 594   // GC to update the number of old marking cycles completed. Those two
 595   // can happen in a nested fashion, i.e., we start a concurrent
 596   // cycle, a Full GC happens half-way through it which ends first,
 597   // and then the cycle notices that a Full GC happened and ends
 598   // too. The concurrent parameter is a boolean to help us do a bit
 599   // tighter consistency checking in the method. If concurrent is
 600   // false, the caller is the inner caller in the nesting (i.e., the
 601   // Full GC). If concurrent is true, the caller is the outer caller
 602   // in this nesting (i.e., the concurrent cycle). Further nesting is
 603   // not currently supported. The end of this call also notifies
 604   // the FullGCCount_lock in case a Java thread is waiting for a full
 605   // GC to happen (e.g., it called System.gc() with
 606   // +ExplicitGCInvokesConcurrent).
 607   void increment_old_marking_cycles_completed(bool concurrent);
 608 
 609   uint old_marking_cycles_completed() {
 610     return _old_marking_cycles_completed;
 611   }
 612 
 613   G1HRPrinter* hr_printer() { return &_hr_printer; }
 614 
 615   // Allocates a new heap region instance.
 616   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 617 
 618   // Allocate the highest free region in the reserved heap. This will commit
 619   // regions as necessary.
 620   HeapRegion* alloc_highest_free_region();
 621 
 622   // Frees a non-humongous region by initializing its contents and
 623   // adding it to the free list that's passed as a parameter (this is
 624   // usually a local list which will be appended to the master free
 625   // list later). The used bytes of freed regions are accumulated in
 626   // pre_used. If skip_remset is true, the region's RSet will not be freed
 627   // up. If skip_hot_card_cache is true, the region's hot card cache will not
 628   // be freed up. The assumption is that this will be done later.
 629   // The locked parameter indicates if the caller has already taken
 630   // care of proper synchronization. This may allow some optimizations.
 631   void free_region(HeapRegion* hr,
 632                    FreeRegionList* free_list,
 633                    bool skip_remset,
 634                    bool skip_hot_card_cache = false,
 635                    bool locked = false);
 636 
 637   // It dirties the cards that cover the block so that the post
 638   // write barrier never queues anything when updating objects on this
 639   // block. It is assumed (and in fact we assert) that the block
 640   // belongs to a young region.
 641   inline void dirty_young_block(HeapWord* start, size_t word_size);
 642 
 643   // Frees a humongous region by collapsing it into individual regions
 644   // and calling free_region() for each of them. The freed regions
 645   // will be added to the free list that's passed as a parameter (this
 646   // is usually a local list which will be appended to the master free
 647   // list later).
 648   // The method assumes that only a single thread is ever calling
 649   // this for a particular region at once.
 650   void free_humongous_region(HeapRegion* hr,
 651                              FreeRegionList* free_list);
 652 
 653   // Facility for allocating in 'archive' regions in high heap memory and
 654   // recording the allocated ranges. These should all be called from the
 655   // VM thread at safepoints, without the heap lock held. They can be used
 656   // to create and archive a set of heap regions which can be mapped at the
 657   // same fixed addresses in a subsequent JVM invocation.
 658   void begin_archive_alloc_range(bool open = false);
 659 
 660   // Check if the requested size would be too large for an archive allocation.
 661   bool is_archive_alloc_too_large(size_t word_size);
 662 
 663   // Allocate memory of the requested size from the archive region. This will
 664   // return NULL if the size is too large or if no memory is available. It
 665   // does not trigger a garbage collection.
 666   HeapWord* archive_mem_allocate(size_t word_size);
 667 
 668   // Optionally aligns the end address and returns the allocated ranges in
 669   // an array of MemRegions in order of ascending addresses.
 670   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 671                                size_t end_alignment_in_bytes = 0);
 672 
 673   // Facility for allocating a fixed range within the heap and marking
 674   // the containing regions as 'archive'. For use at JVM init time, when the
 675   // caller may mmap archived heap data at the specified range(s).
 676   // Verify that the MemRegions specified in the argument array are within the
 677   // reserved heap.
 678   bool check_archive_addresses(MemRegion* range, size_t count);
 679 
 680   // Commit the appropriate G1 regions containing the specified MemRegions
 681   // and mark them as 'archive' regions. The regions in the array must be
 682   // non-overlapping and in order of ascending address.
 683   bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
 684 
 685   // Insert any required filler objects in the G1 regions around the specified
 686   // ranges to make the regions parseable. This must be called after
 687   // alloc_archive_regions, and after class loading has occurred.
 688   void fill_archive_regions(MemRegion* range, size_t count);
 689 
 690   // For each of the specified MemRegions, uncommit the containing G1 regions
 691   // which had been allocated by alloc_archive_regions. This should be called
 692   // rather than fill_archive_regions at JVM init time if the archive file
 693   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 694   void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open);
 695 
 696   oop materialize_archived_object(oop obj);
 697 
 698 private:
 699 
 700   // Shrink the garbage-first heap by at most the given size (in bytes!).
 701   // (Rounds down to a HeapRegion boundary.)
 702   void shrink(size_t expand_bytes);
 703   void shrink_helper(size_t expand_bytes);
 704 
 705   #if TASKQUEUE_STATS
 706   static void print_taskqueue_stats_hdr(outputStream* const st);
 707   void print_taskqueue_stats() const;
 708   void reset_taskqueue_stats();
 709   #endif // TASKQUEUE_STATS
 710 
 711   // Schedule the VM operation that will do an evacuation pause to
 712   // satisfy an allocation request of word_size. *succeeded will
 713   // return whether the VM operation was successful (it did do an
 714   // evacuation pause) or not (another thread beat us to it or the GC
 715   // locker was active). Given that we should not be holding the
 716   // Heap_lock when we enter this method, we will pass the
 717   // gc_count_before (i.e., total_collections()) as a parameter since
 718   // it has to be read while holding the Heap_lock. Currently, both
 719   // methods that call do_collection_pause() release the Heap_lock
 720   // before the call, so it's easy to read gc_count_before just before.
 721   HeapWord* do_collection_pause(size_t         word_size,
 722                                 uint           gc_count_before,
 723                                 bool*          succeeded,
 724                                 GCCause::Cause gc_cause);
 725 
 726   void wait_for_root_region_scanning();
 727 
 728   // The guts of the incremental collection pause, executed by the vm
 729   // thread. It returns false if it is unable to do the collection due
 730   // to the GC locker being active, true otherwise
 731   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 732 
 733   // Actually do the work of evacuating the collection set.
 734   void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states);
 735   void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
 736   void evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset);
 737 
 738   void pre_evacuate_collection_set();
 739   void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 740 
 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* _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   G1DirtyCardQueueSet _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, G1EvacuationInfo& 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   G1DirtyCardQueueSet& 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* policy() const { return _policy; }
 954   // The remembered set.
 955   G1RemSet* rem_set() const { return _rem_set; }
 956 
 957   inline G1GCPhaseTimes* phase_times() const;
 958 
 959   HeapRegionManager* hrm() const { return _hrm; }
 960 
 961   const G1CollectionSet* collection_set() const { return &_collection_set; }
 962   G1CollectionSet* collection_set() { return &_collection_set; }
 963 
 964   virtual CollectorPolicy* collector_policy() const;
 965 
 966   virtual SoftRefPolicy* soft_ref_policy();
 967 
 968   virtual void initialize_serviceability();
 969   virtual MemoryUsage memory_usage();
 970   virtual GrowableArray<GCMemoryManager*> memory_managers();
 971   virtual GrowableArray<MemoryPool*> memory_pools();
 972 
 973   // Try to minimize the remembered set.
 974   void scrub_rem_set();
 975 
 976   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
 977   void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i);
 978 
 979   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
 980   void iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i);
 981 
 982   // The shared block offset table array.
 983   G1BlockOffsetTable* bot() const { return _bot; }
 984 
 985   // Reference Processing accessors
 986 
 987   // The STW reference processor....
 988   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
 989 
 990   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
 991 
 992   // The Concurrent Marking reference processor...
 993   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
 994 
 995   size_t unused_committed_regions_in_bytes() const;
 996   virtual size_t capacity() const;
 997   virtual size_t used() const;
 998   // This should be called when we're not holding the heap lock. The
 999   // result might be a bit inaccurate.
1000   size_t used_unlocked() const;
1001   size_t recalculate_used() const;
1002 
1003   // These virtual functions do the actual allocation.
1004   // Some heaps may offer a contiguous region for shared non-blocking
1005   // allocation, via inlined code (by exporting the address of the top and
1006   // end fields defining the extent of the contiguous allocation region.)
1007   // But G1CollectedHeap doesn't yet support this.
1008 
1009   virtual bool is_maximal_no_gc() const {
1010     return _hrm->available() == 0;
1011   }
1012 
1013   // Returns whether there are any regions left in the heap for allocation.
1014   bool has_regions_left_for_allocation() const {
1015     return !is_maximal_no_gc() || num_free_regions() != 0;
1016   }
1017 
1018   // The current number of regions in the heap.
1019   uint num_regions() const { return _hrm->length(); }
1020 
1021   // The max number of regions in the heap.
1022   uint max_regions() const { return _hrm->max_length(); }
1023 
1024   // Max number of regions that can be comitted.
1025   uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1026 
1027   // The number of regions that are completely free.
1028   uint num_free_regions() const { return _hrm->num_free_regions(); }
1029 
1030   // The number of regions that can be allocated into.
1031   uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1032 
1033   MemoryUsage get_auxiliary_data_memory_usage() const {
1034     return _hrm->get_auxiliary_data_memory_usage();
1035   }
1036 
1037   // The number of regions that are not completely free.
1038   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1039 
1040 #ifdef ASSERT
1041   bool is_on_master_free_list(HeapRegion* hr) {
1042     return _hrm->is_free(hr);
1043   }
1044 #endif // ASSERT
1045 
1046   inline void old_set_add(HeapRegion* hr);
1047   inline void old_set_remove(HeapRegion* hr);
1048 
1049   inline void archive_set_add(HeapRegion* hr);
1050 
1051   size_t non_young_capacity_bytes() {
1052     return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1053   }
1054 
1055   // Determine whether the given region is one that we are using as an
1056   // old GC alloc region.
1057   bool is_old_gc_alloc_region(HeapRegion* hr);
1058 
1059   // Perform a collection of the heap; intended for use in implementing
1060   // "System.gc".  This probably implies as full a collection as the
1061   // "CollectedHeap" supports.
1062   virtual void collect(GCCause::Cause cause);
1063 
1064   // Perform a collection of the heap with the given cause; if the VM operation
1065   // fails to execute for any reason, retry only if retry_on_gc_failure is set.
1066   // Returns whether this collection attempt actually executed.
1067   bool attempt_collect(GCCause::Cause cause, bool retry_on_gc_failure);
1068 
1069   // True iff an evacuation has failed in the most-recent collection.
1070   bool evacuation_failed() { return _evacuation_failed; }
1071 
1072   void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1073   void prepend_to_freelist(FreeRegionList* list);
1074   void decrement_summary_bytes(size_t bytes);
1075 
1076   virtual bool is_in(const void* p) const;
1077 #ifdef ASSERT
1078   // Returns whether p is in one of the available areas of the heap. Slow but
1079   // extensive version.
1080   bool is_in_exact(const void* p) const;
1081 #endif
1082 
1083   // Return "TRUE" iff the given object address is within the collection
1084   // set. Assumes that the reference points into the heap.
1085   inline bool is_in_cset(const HeapRegion *hr);
1086   inline bool is_in_cset(oop obj);
1087   inline bool is_in_cset(HeapWord* addr);
1088 
1089   inline bool is_in_cset_or_humongous(const oop obj);
1090 
1091  private:
1092   // This array is used for a quick test on whether a reference points into
1093   // the collection set or not. Each of the array's elements denotes whether the
1094   // corresponding region is in the collection set or not.
1095   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1096 
1097  public:
1098 
1099   inline InCSetState in_cset_state(const oop obj);
1100 
1101   // Return "TRUE" iff the given object address is in the reserved
1102   // region of g1.
1103   bool is_in_g1_reserved(const void* p) const {
1104     return _hrm->reserved().contains(p);
1105   }
1106 
1107   // Returns a MemRegion that corresponds to the space that has been
1108   // reserved for the heap
1109   MemRegion g1_reserved() const {
1110     return _hrm->reserved();
1111   }
1112 
1113   virtual bool is_in_closed_subset(const void* p) const;
1114 
1115   G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1116 
1117   G1CardTable* card_table() const {
1118     return _card_table;
1119   }
1120 
1121   // Iteration functions.
1122 
1123   // Iterate over all objects, calling "cl.do_object" on each.
1124   virtual void object_iterate(ObjectClosure* cl);
1125 
1126   virtual void safe_object_iterate(ObjectClosure* cl) {
1127     object_iterate(cl);
1128   }
1129 
1130   // Iterate over heap regions, in address order, terminating the
1131   // iteration early if the "do_heap_region" method returns "true".
1132   void heap_region_iterate(HeapRegionClosure* blk) const;
1133 
1134   // Return the region with the given index. It assumes the index is valid.
1135   inline HeapRegion* region_at(uint index) const;
1136   inline HeapRegion* region_at_or_null(uint index) const;
1137 
1138   // Return the next region (by index) that is part of the same
1139   // humongous object that hr is part of.
1140   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1141 
1142   // Calculate the region index of the given address. Given address must be
1143   // within the heap.
1144   inline uint addr_to_region(HeapWord* addr) const;
1145 
1146   inline HeapWord* bottom_addr_for_region(uint index) const;
1147 
1148   // Two functions to iterate over the heap regions in parallel. Threads
1149   // compete using the HeapRegionClaimer to claim the regions before
1150   // applying the closure on them.
1151   // The _from_worker_offset version uses the HeapRegionClaimer and
1152   // the worker id to calculate a start offset to prevent all workers to
1153   // start from the point.
1154   void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1155                                                   HeapRegionClaimer* hrclaimer,
1156                                                   uint worker_id) const;
1157 
1158   void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1159                                           HeapRegionClaimer* hrclaimer) const;
1160 
1161   // Iterate over the regions (if any) in the current collection set.
1162   void collection_set_iterate(HeapRegionClosure* blk);
1163 
1164   // Iterate over the regions (if any) in the current collection set. Starts the
1165   // iteration over the entire collection set so that the start regions of a given
1166   // worker id over the set active_workers are evenly spread across the set of
1167   // collection set regions.
1168   void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1169 
1170   // Returns the HeapRegion that contains addr. addr must not be NULL.
1171   template <class T>
1172   inline HeapRegion* heap_region_containing(const T addr) const;
1173 
1174   // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1175   // region. addr must not be NULL.
1176   template <class T>
1177   inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1178 
1179   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1180   // each address in the (reserved) heap is a member of exactly
1181   // one block.  The defining characteristic of a block is that it is
1182   // possible to find its size, and thus to progress forward to the next
1183   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1184   // represent Java objects, or they might be free blocks in a
1185   // free-list-based heap (or subheap), as long as the two kinds are
1186   // distinguishable and the size of each is determinable.
1187 
1188   // Returns the address of the start of the "block" that contains the
1189   // address "addr".  We say "blocks" instead of "object" since some heaps
1190   // may not pack objects densely; a chunk may either be an object or a
1191   // non-object.
1192   virtual HeapWord* block_start(const void* addr) const;
1193 
1194   // Requires "addr" to be the start of a chunk, and returns its size.
1195   // "addr + size" is required to be the start of a new chunk, or the end
1196   // of the active area of the heap.
1197   virtual size_t block_size(const HeapWord* addr) const;
1198 
1199   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1200   // the block is an object.
1201   virtual bool block_is_obj(const HeapWord* addr) const;
1202 
1203   // Section on thread-local allocation buffers (TLABs)
1204   // See CollectedHeap for semantics.
1205 
1206   bool supports_tlab_allocation() const;
1207   size_t tlab_capacity(Thread* ignored) const;
1208   size_t tlab_used(Thread* ignored) const;
1209   size_t max_tlab_size() const;
1210   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1211 
1212   inline bool is_in_young(const oop obj);
1213 
1214   // Returns "true" iff the given word_size is "very large".
1215   static bool is_humongous(size_t word_size) {
1216     // Note this has to be strictly greater-than as the TLABs
1217     // are capped at the humongous threshold and we want to
1218     // ensure that we don't try to allocate a TLAB as
1219     // humongous and that we don't allocate a humongous
1220     // object in a TLAB.
1221     return word_size > _humongous_object_threshold_in_words;
1222   }
1223 
1224   // Returns the humongous threshold for a specific region size
1225   static size_t humongous_threshold_for(size_t region_size) {
1226     return (region_size / 2);
1227   }
1228 
1229   // Returns the number of regions the humongous object of the given word size
1230   // requires.
1231   static size_t humongous_obj_size_in_regions(size_t word_size);
1232 
1233   // Print the maximum heap capacity.
1234   virtual size_t max_capacity() const;
1235 
1236   // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1237   virtual size_t max_reserved_capacity() const;
1238 
1239   virtual jlong millis_since_last_gc();
1240 
1241 
1242   // Convenience function to be used in situations where the heap type can be
1243   // asserted to be this type.
1244   static G1CollectedHeap* heap();
1245 
1246   void set_region_short_lived_locked(HeapRegion* hr);
1247   // add appropriate methods for any other surv rate groups
1248 
1249   const G1SurvivorRegions* survivor() const { return &_survivor; }
1250 
1251   uint eden_regions_count() const { return _eden.length(); }
1252   uint survivor_regions_count() const { return _survivor.length(); }
1253   uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1254   uint old_regions_count() const { return _old_set.length(); }
1255   uint archive_regions_count() const { return _archive_set.length(); }
1256   uint humongous_regions_count() const { return _humongous_set.length(); }
1257 
1258 #ifdef ASSERT
1259   bool check_young_list_empty();
1260 #endif
1261 
1262   // *** Stuff related to concurrent marking.  It's not clear to me that so
1263   // many of these need to be public.
1264 
1265   // The functions below are helper functions that a subclass of
1266   // "CollectedHeap" can use in the implementation of its virtual
1267   // functions.
1268   // This performs a concurrent marking of the live objects in a
1269   // bitmap off to the side.
1270   void do_concurrent_mark();
1271 
1272   bool is_marked_next(oop obj) const;
1273 
1274   // Determine if an object is dead, given the object and also
1275   // the region to which the object belongs. An object is dead
1276   // iff a) it was not allocated since the last mark, b) it
1277   // is not marked, and c) it is not in an archive region.
1278   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1279     return
1280       hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1281       !hr->is_archive();
1282   }
1283 
1284   // This function returns true when an object has been
1285   // around since the previous marking and hasn't yet
1286   // been marked during this marking, and is not in an archive region.
1287   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1288     return
1289       !hr->obj_allocated_since_next_marking(obj) &&
1290       !is_marked_next(obj) &&
1291       !hr->is_archive();
1292   }
1293 
1294   // Determine if an object is dead, given only the object itself.
1295   // This will find the region to which the object belongs and
1296   // then call the region version of the same function.
1297 
1298   // Added if it is NULL it isn't dead.
1299 
1300   inline bool is_obj_dead(const oop obj) const;
1301 
1302   inline bool is_obj_ill(const oop obj) const;
1303 
1304   inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1305   inline bool is_obj_dead_full(const oop obj) const;
1306 
1307   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1308 
1309   // Refinement
1310 
1311   G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1312 
1313   // Optimized nmethod scanning support routines
1314 
1315   // Is an oop scavengeable
1316   virtual bool is_scavengable(oop obj);
1317 
1318   // Register the given nmethod with the G1 heap.
1319   virtual void register_nmethod(nmethod* nm);
1320 
1321   // Unregister the given nmethod from the G1 heap.
1322   virtual void unregister_nmethod(nmethod* nm);
1323 
1324   // Free up superfluous code root memory.
1325   void purge_code_root_memory();
1326 
1327   // Rebuild the strong code root lists for each region
1328   // after a full GC.
1329   void rebuild_strong_code_roots();
1330 
1331   // Partial cleaning of VM internal data structures.
1332   void string_dedup_cleaning(BoolObjectClosure* is_alive,
1333                              OopClosure* keep_alive,
1334                              G1GCPhaseTimes* phase_times = NULL);
1335 
1336   // Performs cleaning of data structures after class unloading.
1337   void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1338 
1339   // Redirty logged cards in the refinement queue.
1340   void redirty_logged_cards();
1341   // Verification
1342 
1343   // Deduplicate the string
1344   virtual void deduplicate_string(oop str);
1345 
1346   // Perform any cleanup actions necessary before allowing a verification.
1347   virtual void prepare_for_verify();
1348 
1349   // Perform verification.
1350 
1351   // vo == UsePrevMarking -> use "prev" marking information,
1352   // vo == UseNextMarking -> use "next" marking information
1353   // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1354   //
1355   // NOTE: Only the "prev" marking information is guaranteed to be
1356   // consistent most of the time, so most calls to this should use
1357   // vo == UsePrevMarking.
1358   // Currently, there is only one case where this is called with
1359   // vo == UseNextMarking, which is to verify the "next" marking
1360   // information at the end of remark.
1361   // Currently there is only one place where this is called with
1362   // vo == UseFullMarking, which is to verify the marking during a
1363   // full GC.
1364   void verify(VerifyOption vo);
1365 
1366   // WhiteBox testing support.
1367   virtual bool supports_concurrent_phase_control() const;
1368   virtual bool request_concurrent_phase(const char* phase);
1369   bool is_heterogeneous_heap() const;
1370 
1371   virtual WorkGang* get_safepoint_workers() { return _workers; }
1372 
1373   // The methods below are here for convenience and dispatch the
1374   // appropriate method depending on value of the given VerifyOption
1375   // parameter. The values for that parameter, and their meanings,
1376   // are the same as those above.
1377 
1378   bool is_obj_dead_cond(const oop obj,
1379                         const HeapRegion* hr,
1380                         const VerifyOption vo) const;
1381 
1382   bool is_obj_dead_cond(const oop obj,
1383                         const VerifyOption vo) const;
1384 
1385   G1HeapSummary create_g1_heap_summary();
1386   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1387 
1388   // Printing
1389 private:
1390   void print_heap_regions() const;
1391   void print_regions_on(outputStream* st) const;
1392 
1393 public:
1394   virtual void print_on(outputStream* st) const;
1395   virtual void print_extended_on(outputStream* st) const;
1396   virtual void print_on_error(outputStream* st) const;
1397 
1398   virtual void print_gc_threads_on(outputStream* st) const;
1399   virtual void gc_threads_do(ThreadClosure* tc) const;
1400 
1401   // Override
1402   void print_tracing_info() const;
1403 
1404   // The following two methods are helpful for debugging RSet issues.
1405   void print_cset_rsets() PRODUCT_RETURN;
1406   void print_all_rsets() PRODUCT_RETURN;
1407 
1408   size_t pending_card_num();
1409 };
1410 
1411 class G1ParEvacuateFollowersClosure : public VoidClosure {
1412 private:
1413   double _start_term;
1414   double _term_time;
1415   size_t _term_attempts;
1416 
1417   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1418   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1419 protected:
1420   G1CollectedHeap*              _g1h;
1421   G1ParScanThreadState*         _par_scan_state;
1422   RefToScanQueueSet*            _queues;
1423   ParallelTaskTerminator*       _terminator;
1424   G1GCPhaseTimes::GCParPhases   _phase;
1425 
1426   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1427   RefToScanQueueSet*      queues()         { return _queues; }
1428   ParallelTaskTerminator* terminator()     { return _terminator; }
1429 
1430 public:
1431   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1432                                 G1ParScanThreadState* par_scan_state,
1433                                 RefToScanQueueSet* queues,
1434                                 ParallelTaskTerminator* terminator,
1435                                 G1GCPhaseTimes::GCParPhases phase)
1436     : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1437       _g1h(g1h), _par_scan_state(par_scan_state),
1438       _queues(queues), _terminator(terminator), _phase(phase) {}
1439 
1440   void do_void();
1441 
1442   double term_time() const { return _term_time; }
1443   size_t term_attempts() const { return _term_attempts; }
1444 
1445 private:
1446   inline bool offer_termination();
1447 };
1448 
1449 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP