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 "services/memoryManager.hpp"
  55 #include "utilities/stack.hpp"
  56 
  57 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  58 // It uses the "Garbage First" heap organization and algorithm, which
  59 // may combine concurrent marking with parallel, incremental compaction of
  60 // heap subsets that will yield large amounts of garbage.
  61 
  62 // Forward declarations
  63 class HeapRegion;
  64 class HRRSCleanupTask;
  65 class GenerationSpec;
  66 class G1ParScanThreadState;
  67 class G1ParScanThreadStateSet;
  68 class G1ParScanThreadState;
  69 class MemoryPool;
  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 Ticks;
  90 class WorkGang;
  91 class G1Allocator;
  92 class G1ArchiveAllocator;
  93 class G1FullGCScope;
  94 class G1HeapVerifier;
  95 class G1HeapSizingPolicy;
  96 class G1HeapSummary;
  97 class G1EvacSummary;
  98 
  99 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
 100 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
 101 
 102 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
 103 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
 104 
 105 // The G1 STW is alive closure.
 106 // An instance is embedded into the G1CH and used as the
 107 // (optional) _is_alive_non_header closure in the STW
 108 // reference processor. It is also extensively used during
 109 // reference processing during STW evacuation pauses.
 110 class G1STWIsAliveClosure: public BoolObjectClosure {
 111   G1CollectedHeap* _g1h;
 112 public:
 113   G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
 114   bool do_object_b(oop p);
 115 };
 116 
 117 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 118  private:
 119   void reset_from_card_cache(uint start_idx, size_t num_regions);
 120  public:
 121   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 122 };
 123 
 124 class G1CollectedHeap : public CollectedHeap {
 125   friend class G1FreeCollectionSetTask;
 126   friend class VM_CollectForMetadataAllocation;
 127   friend class VM_G1CollectForAllocation;
 128   friend class VM_G1CollectFull;
 129   friend class VMStructs;
 130   friend class MutatorAllocRegion;
 131   friend class G1FullCollector;
 132   friend class G1GCAllocRegion;
 133   friend class G1HeapVerifier;
 134 
 135   // Closures used in implementation.
 136   friend class G1ParScanThreadState;
 137   friend class G1ParScanThreadStateSet;
 138   friend class G1ParTask;
 139   friend class G1PLABAllocator;
 140   friend class G1PrepareCompactClosure;
 141 
 142   // Other related classes.
 143   friend class HeapRegionClaimer;
 144 
 145   // Testing classes.
 146   friend class G1CheckCSetFastTableClosure;
 147 
 148 private:
 149   G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
 150 
 151   WorkGang* _workers;
 152   G1CollectorPolicy* _collector_policy;
 153   G1CardTable* _card_table;
 154 
 155   SoftRefPolicy      _soft_ref_policy;
 156 
 157   GCMemoryManager _memory_manager;
 158   GCMemoryManager _full_gc_memory_manager;
 159 
 160   MemoryPool* _eden_pool;
 161   MemoryPool* _survivor_pool;
 162   MemoryPool* _old_pool;
 163 
 164   static size_t _humongous_object_threshold_in_words;
 165 
 166   // It keeps track of the old regions.
 167   HeapRegionSet _old_set;
 168 
 169   // It keeps track of the humongous regions.
 170   HeapRegionSet _humongous_set;
 171 
 172   virtual void initialize_serviceability();
 173 
 174   void eagerly_reclaim_humongous_regions();
 175   // Start a new incremental collection set for the next pause.
 176   void start_new_collection_set();
 177 
 178   // The number of regions we could create by expansion.
 179   uint _expansion_regions;
 180 
 181   // The block offset table for the G1 heap.
 182   G1BlockOffsetTable* _bot;
 183 
 184   // Tears down the region sets / lists so that they are empty and the
 185   // regions on the heap do not belong to a region set / list. The
 186   // only exception is the humongous set which we leave unaltered. If
 187   // free_list_only is true, it will only tear down the master free
 188   // list. It is called before a Full GC (free_list_only == false) or
 189   // before heap shrinking (free_list_only == true).
 190   void tear_down_region_sets(bool free_list_only);
 191 
 192   // Rebuilds the region sets / lists so that they are repopulated to
 193   // reflect the contents of the heap. The only exception is the
 194   // humongous set which was not torn down in the first place. If
 195   // free_list_only is true, it will only rebuild the master free
 196   // list. It is called after a Full GC (free_list_only == false) or
 197   // after heap shrinking (free_list_only == true).
 198   void rebuild_region_sets(bool free_list_only);
 199 
 200   // Callback for region mapping changed events.
 201   G1RegionMappingChangedListener _listener;
 202 
 203   // The sequence of all heap regions in the heap.
 204   HeapRegionManager _hrm;
 205 
 206   // Manages all allocations with regions except humongous object allocations.
 207   G1Allocator* _allocator;
 208 
 209   // Manages all heap verification.
 210   G1HeapVerifier* _verifier;
 211 
 212   // Outside of GC pauses, the number of bytes used in all regions other
 213   // than the current allocation region(s).
 214   size_t _summary_bytes_used;
 215 
 216   void increase_used(size_t bytes);
 217   void decrease_used(size_t bytes);
 218 
 219   void set_used(size_t bytes);
 220 
 221   // Class that handles archive allocation ranges.
 222   G1ArchiveAllocator* _archive_allocator;
 223 
 224   // GC allocation statistics policy for survivors.
 225   G1EvacStats _survivor_evac_stats;
 226 
 227   // GC allocation statistics policy for tenured objects.
 228   G1EvacStats _old_evac_stats;
 229 
 230   // It specifies whether we should attempt to expand the heap after a
 231   // region allocation failure. If heap expansion fails we set this to
 232   // false so that we don't re-attempt the heap expansion (it's likely
 233   // that subsequent expansion attempts will also fail if one fails).
 234   // Currently, it is only consulted during GC and it's reset at the
 235   // start of each GC.
 236   bool _expand_heap_after_alloc_failure;
 237 
 238   // Helper for monitoring and management support.
 239   G1MonitoringSupport* _g1mm;
 240 
 241   // Records whether the region at the given index is (still) a
 242   // candidate for eager reclaim.  Only valid for humongous start
 243   // regions; other regions have unspecified values.  Humongous start
 244   // regions are initialized at start of collection pause, with
 245   // candidates removed from the set as they are found reachable from
 246   // roots or the young generation.
 247   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 248    protected:
 249     bool default_value() const { return false; }
 250    public:
 251     void clear() { G1BiasedMappedArray<bool>::clear(); }
 252     void set_candidate(uint region, bool value) {
 253       set_by_index(region, value);
 254     }
 255     bool is_candidate(uint region) {
 256       return get_by_index(region);
 257     }
 258   };
 259 
 260   HumongousReclaimCandidates _humongous_reclaim_candidates;
 261   // Stores whether during humongous object registration we found candidate regions.
 262   // If not, we can skip a few steps.
 263   bool _has_humongous_reclaim_candidates;
 264 
 265   G1HRPrinter _hr_printer;
 266 
 267   // It decides whether an explicit GC should start a concurrent cycle
 268   // instead of doing a STW GC. Currently, a concurrent cycle is
 269   // explicitly started if:
 270   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 271   // (b) cause == _g1_humongous_allocation
 272   // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 273   // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 274   // (e) cause == _wb_conc_mark
 275   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 276 
 277   // indicates whether we are in young or mixed GC mode
 278   G1CollectorState _collector_state;
 279 
 280   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 281   // concurrent cycles) we have started.
 282   volatile uint _old_marking_cycles_started;
 283 
 284   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 285   // concurrent cycles) we have completed.
 286   volatile uint _old_marking_cycles_completed;
 287 
 288   // This is a non-product method that is helpful for testing. It is
 289   // called at the end of a GC and artificially expands the heap by
 290   // allocating a number of dead regions. This way we can induce very
 291   // frequent marking cycles and stress the cleanup / concurrent
 292   // cleanup code more (as all the regions that will be allocated by
 293   // this method will be found dead by the marking cycle).
 294   void allocate_dummy_regions() PRODUCT_RETURN;
 295 
 296   // If the HR printer is active, dump the state of the regions in the
 297   // heap after a compaction.
 298   void print_hrm_post_compaction();
 299 
 300   // Create a memory mapper for auxiliary data structures of the given size and
 301   // translation factor.
 302   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 303                                                          size_t size,
 304                                                          size_t translation_factor);
 305 
 306   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 307 
 308   // These are macros so that, if the assert fires, we get the correct
 309   // line number, file, etc.
 310 
 311 #define heap_locking_asserts_params(_extra_message_)                          \
 312   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 313   (_extra_message_),                                                          \
 314   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 315   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 316   BOOL_TO_STR(Thread::current()->is_VM_thread())
 317 
 318 #define assert_heap_locked()                                                  \
 319   do {                                                                        \
 320     assert(Heap_lock->owned_by_self(),                                        \
 321            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 322   } while (0)
 323 
 324 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 325   do {                                                                        \
 326     assert(Heap_lock->owned_by_self() ||                                      \
 327            (SafepointSynchronize::is_at_safepoint() &&                        \
 328              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 329            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 330                                         "should be at a safepoint"));         \
 331   } while (0)
 332 
 333 #define assert_heap_locked_and_not_at_safepoint()                             \
 334   do {                                                                        \
 335     assert(Heap_lock->owned_by_self() &&                                      \
 336                                     !SafepointSynchronize::is_at_safepoint(), \
 337           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 338                                        "should not be at a safepoint"));      \
 339   } while (0)
 340 
 341 #define assert_heap_not_locked()                                              \
 342   do {                                                                        \
 343     assert(!Heap_lock->owned_by_self(),                                       \
 344         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 345   } while (0)
 346 
 347 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 348   do {                                                                        \
 349     assert(!Heap_lock->owned_by_self() &&                                     \
 350                                     !SafepointSynchronize::is_at_safepoint(), \
 351       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 352                                    "should not be at a safepoint"));          \
 353   } while (0)
 354 
 355 #define assert_at_safepoint_on_vm_thread()                                    \
 356   do {                                                                        \
 357     assert_at_safepoint();                                                    \
 358     assert(Thread::current_or_null() != NULL, "no current thread");           \
 359     assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
 360   } while (0)
 361 
 362   // The young region list.
 363   G1EdenRegions _eden;
 364   G1SurvivorRegions _survivor;
 365 
 366   STWGCTimer* _gc_timer_stw;
 367 
 368   G1NewTracer* _gc_tracer_stw;
 369 
 370   // The current policy object for the collector.
 371   G1Policy* _g1_policy;
 372   G1HeapSizingPolicy* _heap_sizing_policy;
 373 
 374   G1CollectionSet _collection_set;
 375 
 376   // Try to allocate a single non-humongous HeapRegion sufficient for
 377   // an allocation of the given word_size. If do_expand is true,
 378   // attempt to expand the heap if necessary to satisfy the allocation
 379   // request. If the region is to be used as an old region or for a
 380   // humongous object, set is_old to true. If not, to false.
 381   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 382 
 383   // Initialize a contiguous set of free regions of length num_regions
 384   // and starting at index first so that they appear as a single
 385   // humongous region.
 386   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 387                                                       uint num_regions,
 388                                                       size_t word_size);
 389 
 390   // Attempt to allocate a humongous object of the given size. Return
 391   // NULL if unsuccessful.
 392   HeapWord* humongous_obj_allocate(size_t word_size);
 393 
 394   // The following two methods, allocate_new_tlab() and
 395   // mem_allocate(), are the two main entry points from the runtime
 396   // into the G1's allocation routines. They have the following
 397   // assumptions:
 398   //
 399   // * They should both be called outside safepoints.
 400   //
 401   // * They should both be called without holding the Heap_lock.
 402   //
 403   // * All allocation requests for new TLABs should go to
 404   //   allocate_new_tlab().
 405   //
 406   // * All non-TLAB allocation requests should go to mem_allocate().
 407   //
 408   // * If either call cannot satisfy the allocation request using the
 409   //   current allocating region, they will try to get a new one. If
 410   //   this fails, they will attempt to do an evacuation pause and
 411   //   retry the allocation.
 412   //
 413   // * If all allocation attempts fail, even after trying to schedule
 414   //   an evacuation pause, allocate_new_tlab() will return NULL,
 415   //   whereas mem_allocate() will attempt a heap expansion and/or
 416   //   schedule a Full GC.
 417   //
 418   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 419   //   should never be called with word_size being humongous. All
 420   //   humongous allocation requests should go to mem_allocate() which
 421   //   will satisfy them with a special path.
 422 
 423   virtual HeapWord* allocate_new_tlab(size_t min_word_size,
 424                                       size_t desired_word_size,
 425                                       size_t* actual_word_size);
 426 
 427   virtual HeapWord* mem_allocate(size_t word_size,
 428                                  bool*  gc_overhead_limit_was_exceeded);
 429 
 430   // First-level mutator allocation attempt: try to allocate out of
 431   // the mutator alloc region without taking the Heap_lock. This
 432   // should only be used for non-humongous allocations.
 433   inline HeapWord* attempt_allocation(size_t min_word_size,
 434                                       size_t desired_word_size,
 435                                       size_t* actual_word_size);
 436 
 437   // Second-level mutator allocation attempt: take the Heap_lock and
 438   // retry the allocation attempt, potentially scheduling a GC
 439   // pause. This should only be used for non-humongous allocations.
 440   HeapWord* attempt_allocation_slow(size_t word_size);
 441 
 442   // Takes the Heap_lock and attempts a humongous allocation. It can
 443   // potentially schedule a GC pause.
 444   HeapWord* attempt_allocation_humongous(size_t word_size);
 445 
 446   // Allocation attempt that should be called during safepoints (e.g.,
 447   // at the end of a successful GC). expect_null_mutator_alloc_region
 448   // specifies whether the mutator alloc region is expected to be NULL
 449   // or not.
 450   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 451                                             bool expect_null_mutator_alloc_region);
 452 
 453   // These methods are the "callbacks" from the G1AllocRegion class.
 454 
 455   // For mutator alloc regions.
 456   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 457   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 458                                    size_t allocated_bytes);
 459 
 460   // For GC alloc regions.
 461   bool has_more_regions(InCSetState dest);
 462   HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
 463   void retire_gc_alloc_region(HeapRegion* alloc_region,
 464                               size_t allocated_bytes, InCSetState dest);
 465 
 466   // - if explicit_gc is true, the GC is for a System.gc() etc,
 467   //   otherwise it's for a failed allocation.
 468   // - if clear_all_soft_refs is true, all soft references should be
 469   //   cleared during the GC.
 470   // - it returns false if it is unable to do the collection due to the
 471   //   GC locker being active, true otherwise.
 472   bool do_full_collection(bool explicit_gc,
 473                           bool clear_all_soft_refs);
 474 
 475   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 476   virtual void do_full_collection(bool clear_all_soft_refs);
 477 
 478   // Resize the heap if necessary after a full collection.
 479   void resize_if_necessary_after_full_collection();
 480 
 481   // Callback from VM_G1CollectForAllocation operation.
 482   // This function does everything necessary/possible to satisfy a
 483   // failed allocation request (including collection, expansion, etc.)
 484   HeapWord* satisfy_failed_allocation(size_t word_size,
 485                                       bool* succeeded);
 486   // Internal helpers used during full GC to split it up to
 487   // increase readability.
 488   void abort_concurrent_cycle();
 489   void verify_before_full_collection(bool explicit_gc);
 490   void prepare_heap_for_full_collection();
 491   void prepare_heap_for_mutators();
 492   void abort_refinement();
 493   void verify_after_full_collection();
 494   void print_heap_after_full_collection(G1HeapTransition* heap_transition);
 495 
 496   // Helper method for satisfy_failed_allocation()
 497   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 498                                              bool do_gc,
 499                                              bool clear_all_soft_refs,
 500                                              bool expect_null_mutator_alloc_region,
 501                                              bool* gc_succeeded);
 502 
 503   // Attempting to expand the heap sufficiently
 504   // to support an allocation of the given "word_size".  If
 505   // successful, perform the allocation and return the address of the
 506   // allocated block, or else "NULL".
 507   HeapWord* expand_and_allocate(size_t word_size);
 508 
 509   // Preserve any referents discovered by concurrent marking that have not yet been
 510   // copied by the STW pause.
 511   void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
 512   // Process any reference objects discovered during
 513   // an incremental evacuation pause.
 514   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 515 
 516   // Enqueue any remaining discovered references
 517   // after processing.
 518   void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 519 
 520   // Merges the information gathered on a per-thread basis for all worker threads
 521   // during GC into global variables.
 522   void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
 523 public:
 524   G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
 525 
 526   WorkGang* workers() const { return _workers; }
 527 
 528   G1Allocator* allocator() {
 529     return _allocator;
 530   }
 531 
 532   G1HeapVerifier* verifier() {
 533     return _verifier;
 534   }
 535 
 536   G1MonitoringSupport* g1mm() {
 537     assert(_g1mm != NULL, "should have been initialized");
 538     return _g1mm;
 539   }
 540 
 541   // Expand the garbage-first heap by at least the given size (in bytes!).
 542   // Returns true if the heap was expanded by the requested amount;
 543   // false otherwise.
 544   // (Rounds up to a HeapRegion boundary.)
 545   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 546 
 547   // Returns the PLAB statistics for a given destination.
 548   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 549 
 550   // Determines PLAB size for a given destination.
 551   inline size_t desired_plab_sz(InCSetState dest);
 552 
 553   // Do anything common to GC's.
 554   void gc_prologue(bool full);
 555   void gc_epilogue(bool full);
 556 
 557   // Does the given region fulfill remembered set based eager reclaim candidate requirements?
 558   bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
 559 
 560   // Modify the reclaim candidate set and test for presence.
 561   // These are only valid for starts_humongous regions.
 562   inline void set_humongous_reclaim_candidate(uint region, bool value);
 563   inline bool is_humongous_reclaim_candidate(uint region);
 564 
 565   // Remove from the reclaim candidate set.  Also remove from the
 566   // collection set so that later encounters avoid the slow path.
 567   inline void set_humongous_is_live(oop obj);
 568 
 569   // Register the given region to be part of the collection set.
 570   inline void register_humongous_region_with_cset(uint index);
 571   // Register regions with humongous objects (actually on the start region) in
 572   // the in_cset_fast_test table.
 573   void register_humongous_regions_with_cset();
 574   // We register a region with the fast "in collection set" test. We
 575   // simply set to true the array slot corresponding to this region.
 576   void register_young_region_with_cset(HeapRegion* r) {
 577     _in_cset_fast_test.set_in_young(r->hrm_index());
 578   }
 579   void register_old_region_with_cset(HeapRegion* r) {
 580     _in_cset_fast_test.set_in_old(r->hrm_index());
 581   }
 582   void clear_in_cset(const HeapRegion* hr) {
 583     _in_cset_fast_test.clear(hr);
 584   }
 585 
 586   void clear_cset_fast_test() {
 587     _in_cset_fast_test.clear();
 588   }
 589 
 590   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 591 
 592   // This is called at the start of either a concurrent cycle or a Full
 593   // GC to update the number of old marking cycles started.
 594   void increment_old_marking_cycles_started();
 595 
 596   // This is called at the end of either a concurrent cycle or a Full
 597   // GC to update the number of old marking cycles completed. Those two
 598   // can happen in a nested fashion, i.e., we start a concurrent
 599   // cycle, a Full GC happens half-way through it which ends first,
 600   // and then the cycle notices that a Full GC happened and ends
 601   // too. The concurrent parameter is a boolean to help us do a bit
 602   // tighter consistency checking in the method. If concurrent is
 603   // false, the caller is the inner caller in the nesting (i.e., the
 604   // Full GC). If concurrent is true, the caller is the outer caller
 605   // in this nesting (i.e., the concurrent cycle). Further nesting is
 606   // not currently supported. The end of this call also notifies
 607   // the FullGCCount_lock in case a Java thread is waiting for a full
 608   // GC to happen (e.g., it called System.gc() with
 609   // +ExplicitGCInvokesConcurrent).
 610   void increment_old_marking_cycles_completed(bool concurrent);
 611 
 612   uint old_marking_cycles_completed() {
 613     return _old_marking_cycles_completed;
 614   }
 615 
 616   G1HRPrinter* hr_printer() { return &_hr_printer; }
 617 
 618   // Allocates a new heap region instance.
 619   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 620 
 621   // Allocate the highest free region in the reserved heap. This will commit
 622   // regions as necessary.
 623   HeapRegion* alloc_highest_free_region();
 624 
 625   // Frees a non-humongous region by initializing its contents and
 626   // adding it to the free list that's passed as a parameter (this is
 627   // usually a local list which will be appended to the master free
 628   // list later). The used bytes of freed regions are accumulated in
 629   // pre_used. If skip_remset is true, the region's RSet will not be freed
 630   // up. If skip_hot_card_cache is true, the region's hot card cache will not
 631   // be freed up. The assumption is that this will be done later.
 632   // The locked parameter indicates if the caller has already taken
 633   // care of proper synchronization. This may allow some optimizations.
 634   void free_region(HeapRegion* hr,
 635                    FreeRegionList* free_list,
 636                    bool skip_remset,
 637                    bool skip_hot_card_cache = false,
 638                    bool locked = false);
 639 
 640   // It dirties the cards that cover the block so that the post
 641   // write barrier never queues anything when updating objects on this
 642   // block. It is assumed (and in fact we assert) that the block
 643   // belongs to a young region.
 644   inline void dirty_young_block(HeapWord* start, size_t word_size);
 645 
 646   // Frees a humongous region by collapsing it into individual regions
 647   // and calling free_region() for each of them. The freed regions
 648   // will be added to the free list that's passed as a parameter (this
 649   // is usually a local list which will be appended to the master free
 650   // list later).
 651   // The method assumes that only a single thread is ever calling
 652   // this for a particular region at once.
 653   void free_humongous_region(HeapRegion* hr,
 654                              FreeRegionList* free_list);
 655 
 656   // Facility for allocating in 'archive' regions in high heap memory and
 657   // recording the allocated ranges. These should all be called from the
 658   // VM thread at safepoints, without the heap lock held. They can be used
 659   // to create and archive a set of heap regions which can be mapped at the
 660   // same fixed addresses in a subsequent JVM invocation.
 661   void begin_archive_alloc_range(bool open = false);
 662 
 663   // Check if the requested size would be too large for an archive allocation.
 664   bool is_archive_alloc_too_large(size_t word_size);
 665 
 666   // Allocate memory of the requested size from the archive region. This will
 667   // return NULL if the size is too large or if no memory is available. It
 668   // does not trigger a garbage collection.
 669   HeapWord* archive_mem_allocate(size_t word_size);
 670 
 671   // Optionally aligns the end address and returns the allocated ranges in
 672   // an array of MemRegions in order of ascending addresses.
 673   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 674                                size_t end_alignment_in_bytes = 0);
 675 
 676   // Facility for allocating a fixed range within the heap and marking
 677   // the containing regions as 'archive'. For use at JVM init time, when the
 678   // caller may mmap archived heap data at the specified range(s).
 679   // Verify that the MemRegions specified in the argument array are within the
 680   // reserved heap.
 681   bool check_archive_addresses(MemRegion* range, size_t count);
 682 
 683   // Commit the appropriate G1 regions containing the specified MemRegions
 684   // and mark them as 'archive' regions. The regions in the array must be
 685   // non-overlapping and in order of ascending address.
 686   bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
 687 
 688   // Insert any required filler objects in the G1 regions around the specified
 689   // ranges to make the regions parseable. This must be called after
 690   // alloc_archive_regions, and after class loading has occurred.
 691   void fill_archive_regions(MemRegion* range, size_t count);
 692 
 693   // For each of the specified MemRegions, uncommit the containing G1 regions
 694   // which had been allocated by alloc_archive_regions. This should be called
 695   // rather than fill_archive_regions at JVM init time if the archive file
 696   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 697   void dealloc_archive_regions(MemRegion* range, size_t count);
 698 
 699 private:
 700 
 701   // Shrink the garbage-first heap by at most the given size (in bytes!).
 702   // (Rounds down to a HeapRegion boundary.)
 703   void shrink(size_t expand_bytes);
 704   void shrink_helper(size_t expand_bytes);
 705 
 706   #if TASKQUEUE_STATS
 707   static void print_taskqueue_stats_hdr(outputStream* const st);
 708   void print_taskqueue_stats() const;
 709   void reset_taskqueue_stats();
 710   #endif // TASKQUEUE_STATS
 711 
 712   // Schedule the VM operation that will do an evacuation pause to
 713   // satisfy an allocation request of word_size. *succeeded will
 714   // return whether the VM operation was successful (it did do an
 715   // evacuation pause) or not (another thread beat us to it or the GC
 716   // locker was active). Given that we should not be holding the
 717   // Heap_lock when we enter this method, we will pass the
 718   // gc_count_before (i.e., total_collections()) as a parameter since
 719   // it has to be read while holding the Heap_lock. Currently, both
 720   // methods that call do_collection_pause() release the Heap_lock
 721   // before the call, so it's easy to read gc_count_before just before.
 722   HeapWord* do_collection_pause(size_t         word_size,
 723                                 uint           gc_count_before,
 724                                 bool*          succeeded,
 725                                 GCCause::Cause gc_cause);
 726 
 727   void wait_for_root_region_scanning();
 728 
 729   // The guts of the incremental collection pause, executed by the vm
 730   // thread. It returns false if it is unable to do the collection due
 731   // to the GC locker being active, true otherwise
 732   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 733 
 734   // Actually do the work of evacuating the collection set.
 735   void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states);
 736 
 737   void pre_evacuate_collection_set();
 738   void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 739 
 740   // Print the header for the per-thread termination statistics.
 741   static void print_termination_stats_hdr();
 742   // Print actual per-thread termination statistics.
 743   void print_termination_stats(uint worker_id,
 744                                double elapsed_ms,
 745                                double strong_roots_ms,
 746                                double term_ms,
 747                                size_t term_attempts,
 748                                size_t alloc_buffer_waste,
 749                                size_t undo_waste) const;
 750   // Update object copying statistics.
 751   void record_obj_copy_mem_stats();
 752 
 753   // The hot card cache for remembered set insertion optimization.
 754   G1HotCardCache* _hot_card_cache;
 755 
 756   // The g1 remembered set of the heap.
 757   G1RemSet* _g1_rem_set;
 758 
 759   // A set of cards that cover the objects for which the Rsets should be updated
 760   // concurrently after the collection.
 761   DirtyCardQueueSet _dirty_card_queue_set;
 762 
 763   // After a collection pause, convert the regions in the collection set into free
 764   // regions.
 765   void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 766 
 767   // Abandon the current collection set without recording policy
 768   // statistics or updating free lists.
 769   void abandon_collection_set(G1CollectionSet* collection_set);
 770 
 771   // The concurrent marker (and the thread it runs in.)
 772   G1ConcurrentMark* _cm;
 773   G1ConcurrentMarkThread* _cm_thread;
 774 
 775   // The concurrent refiner.
 776   G1ConcurrentRefine* _cr;
 777 
 778   // The parallel task queues
 779   RefToScanQueueSet *_task_queues;
 780 
 781   // True iff a evacuation has failed in the current collection.
 782   bool _evacuation_failed;
 783 
 784   EvacuationFailedInfo* _evacuation_failed_info_array;
 785 
 786   // Failed evacuations cause some logical from-space objects to have
 787   // forwarding pointers to themselves.  Reset them.
 788   void remove_self_forwarding_pointers();
 789 
 790   // Restore the objects in the regions in the collection set after an
 791   // evacuation failure.
 792   void restore_after_evac_failure();
 793 
 794   PreservedMarksSet _preserved_marks_set;
 795 
 796   // Preserve the mark of "obj", if necessary, in preparation for its mark
 797   // word being overwritten with a self-forwarding-pointer.
 798   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 799 
 800 #ifndef PRODUCT
 801   // Support for forcing evacuation failures. Analogous to
 802   // PromotionFailureALot for the other collectors.
 803 
 804   // Records whether G1EvacuationFailureALot should be in effect
 805   // for the current GC
 806   bool _evacuation_failure_alot_for_current_gc;
 807 
 808   // Used to record the GC number for interval checking when
 809   // determining whether G1EvaucationFailureALot is in effect
 810   // for the current GC.
 811   size_t _evacuation_failure_alot_gc_number;
 812 
 813   // Count of the number of evacuations between failures.
 814   volatile size_t _evacuation_failure_alot_count;
 815 
 816   // Set whether G1EvacuationFailureALot should be in effect
 817   // for the current GC (based upon the type of GC and which
 818   // command line flags are set);
 819   inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
 820                                                   bool during_initial_mark,
 821                                                   bool mark_or_rebuild_in_progress);
 822 
 823   inline void set_evacuation_failure_alot_for_current_gc();
 824 
 825   // Return true if it's time to cause an evacuation failure.
 826   inline bool evacuation_should_fail();
 827 
 828   // Reset the G1EvacuationFailureALot counters.  Should be called at
 829   // the end of an evacuation pause in which an evacuation failure occurred.
 830   inline void reset_evacuation_should_fail();
 831 #endif // !PRODUCT
 832 
 833   // ("Weak") Reference processing support.
 834   //
 835   // G1 has 2 instances of the reference processor class. One
 836   // (_ref_processor_cm) handles reference object discovery
 837   // and subsequent processing during concurrent marking cycles.
 838   //
 839   // The other (_ref_processor_stw) handles reference object
 840   // discovery and processing during full GCs and incremental
 841   // evacuation pauses.
 842   //
 843   // During an incremental pause, reference discovery will be
 844   // temporarily disabled for _ref_processor_cm and will be
 845   // enabled for _ref_processor_stw. At the end of the evacuation
 846   // pause references discovered by _ref_processor_stw will be
 847   // processed and discovery will be disabled. The previous
 848   // setting for reference object discovery for _ref_processor_cm
 849   // will be re-instated.
 850   //
 851   // At the start of marking:
 852   //  * Discovery by the CM ref processor is verified to be inactive
 853   //    and it's discovered lists are empty.
 854   //  * Discovery by the CM ref processor is then enabled.
 855   //
 856   // At the end of marking:
 857   //  * Any references on the CM ref processor's discovered
 858   //    lists are processed (possibly MT).
 859   //
 860   // At the start of full GC we:
 861   //  * Disable discovery by the CM ref processor and
 862   //    empty CM ref processor's discovered lists
 863   //    (without processing any entries).
 864   //  * Verify that the STW ref processor is inactive and it's
 865   //    discovered lists are empty.
 866   //  * Temporarily set STW ref processor discovery as single threaded.
 867   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 868   //    field.
 869   //  * Finally enable discovery by the STW ref processor.
 870   //
 871   // The STW ref processor is used to record any discovered
 872   // references during the full GC.
 873   //
 874   // At the end of a full GC we:
 875   //  * Enqueue any reference objects discovered by the STW ref processor
 876   //    that have non-live referents. This has the side-effect of
 877   //    making the STW ref processor inactive by disabling discovery.
 878   //  * Verify that the CM ref processor is still inactive
 879   //    and no references have been placed on it's discovered
 880   //    lists (also checked as a precondition during initial marking).
 881 
 882   // The (stw) reference processor...
 883   ReferenceProcessor* _ref_processor_stw;
 884 
 885   // During reference object discovery, the _is_alive_non_header
 886   // closure (if non-null) is applied to the referent object to
 887   // determine whether the referent is live. If so then the
 888   // reference object does not need to be 'discovered' and can
 889   // be treated as a regular oop. This has the benefit of reducing
 890   // the number of 'discovered' reference objects that need to
 891   // be processed.
 892   //
 893   // Instance of the is_alive closure for embedding into the
 894   // STW reference processor as the _is_alive_non_header field.
 895   // Supplying a value for the _is_alive_non_header field is
 896   // optional but doing so prevents unnecessary additions to
 897   // the discovered lists during reference discovery.
 898   G1STWIsAliveClosure _is_alive_closure_stw;
 899 
 900   // The (concurrent marking) reference processor...
 901   ReferenceProcessor* _ref_processor_cm;
 902 
 903   // Instance of the concurrent mark is_alive closure for embedding
 904   // into the Concurrent Marking reference processor as the
 905   // _is_alive_non_header field. Supplying a value for the
 906   // _is_alive_non_header field is optional but doing so prevents
 907   // unnecessary additions to the discovered lists during reference
 908   // discovery.
 909   G1CMIsAliveClosure _is_alive_closure_cm;
 910 
 911 public:
 912 
 913   RefToScanQueue *task_queue(uint i) const;
 914 
 915   uint num_task_queues() const;
 916 
 917   // A set of cards where updates happened during the GC
 918   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 919 
 920   // Create a G1CollectedHeap with the specified policy.
 921   // Must call the initialize method afterwards.
 922   // May not return if something goes wrong.
 923   G1CollectedHeap(G1CollectorPolicy* policy);
 924 
 925 private:
 926   jint initialize_concurrent_refinement();
 927   jint initialize_young_gen_sampling_thread();
 928 public:
 929   // Initialize the G1CollectedHeap to have the initial and
 930   // maximum sizes and remembered and barrier sets
 931   // specified by the policy object.
 932   jint initialize();
 933 
 934   virtual void stop();
 935   virtual void safepoint_synchronize_begin();
 936   virtual void safepoint_synchronize_end();
 937 
 938   // Return the (conservative) maximum heap alignment for any G1 heap
 939   static size_t conservative_max_heap_alignment();
 940 
 941   // Does operations required after initialization has been done.
 942   void post_initialize();
 943 
 944   // Initialize weak reference processing.
 945   void ref_processing_init();
 946 
 947   virtual Name kind() const {
 948     return CollectedHeap::G1;
 949   }
 950 
 951   virtual const char* name() const {
 952     return "G1";
 953   }
 954 
 955   const G1CollectorState* collector_state() const { return &_collector_state; }
 956   G1CollectorState* collector_state() { return &_collector_state; }
 957 
 958   // The current policy object for the collector.
 959   G1Policy* g1_policy() const { return _g1_policy; }
 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 GrowableArray<GCMemoryManager*> memory_managers();
 969   virtual GrowableArray<MemoryPool*> memory_pools();
 970 
 971   // The rem set and barrier set.
 972   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
 973 
 974   // Try to minimize the remembered set.
 975   void scrub_rem_set();
 976 
 977   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
 978   void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
 979 
 980   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
 981   void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
 982 
 983   // The shared block offset table array.
 984   G1BlockOffsetTable* bot() const { return _bot; }
 985 
 986   // Reference Processing accessors
 987 
 988   // The STW reference processor....
 989   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
 990 
 991   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
 992 
 993   // The Concurrent Marking reference processor...
 994   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
 995 
 996   size_t unused_committed_regions_in_bytes() const;
 997   virtual size_t capacity() const;
 998   virtual size_t used() const;
 999   // This should be called when we're not holding the heap lock. The
1000   // result might be a bit inaccurate.
1001   size_t used_unlocked() const;
1002   size_t recalculate_used() const;
1003 
1004   // These virtual functions do the actual allocation.
1005   // Some heaps may offer a contiguous region for shared non-blocking
1006   // allocation, via inlined code (by exporting the address of the top and
1007   // end fields defining the extent of the contiguous allocation region.)
1008   // But G1CollectedHeap doesn't yet support this.
1009 
1010   virtual bool is_maximal_no_gc() const {
1011     return _hrm.available() == 0;
1012   }
1013 
1014   // Returns whether there are any regions left in the heap for allocation.
1015   bool has_regions_left_for_allocation() const {
1016     return !is_maximal_no_gc() || num_free_regions() != 0;
1017   }
1018 
1019   // The current number of regions in the heap.
1020   uint num_regions() const { return _hrm.length(); }
1021 
1022   // The max number of regions in the heap.
1023   uint max_regions() const { return _hrm.max_length(); }
1024 
1025   // The number of regions that are completely free.
1026   uint num_free_regions() const { return _hrm.num_free_regions(); }
1027 
1028   MemoryUsage get_auxiliary_data_memory_usage() const {
1029     return _hrm.get_auxiliary_data_memory_usage();
1030   }
1031 
1032   // The number of regions that are not completely free.
1033   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1034 
1035 #ifdef ASSERT
1036   bool is_on_master_free_list(HeapRegion* hr) {
1037     return _hrm.is_free(hr);
1038   }
1039 #endif // ASSERT
1040 
1041   inline void old_set_add(HeapRegion* hr);
1042   inline void old_set_remove(HeapRegion* hr);
1043 
1044   size_t non_young_capacity_bytes() {
1045     return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1046   }
1047 
1048   // Determine whether the given region is one that we are using as an
1049   // old GC alloc region.
1050   bool is_old_gc_alloc_region(HeapRegion* hr);
1051 
1052   // Perform a collection of the heap; intended for use in implementing
1053   // "System.gc".  This probably implies as full a collection as the
1054   // "CollectedHeap" supports.
1055   virtual void collect(GCCause::Cause cause);
1056 
1057   // True iff an evacuation has failed in the most-recent collection.
1058   bool evacuation_failed() { return _evacuation_failed; }
1059 
1060   void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1061   void prepend_to_freelist(FreeRegionList* list);
1062   void decrement_summary_bytes(size_t bytes);
1063 
1064   virtual bool is_in(const void* p) const;
1065 #ifdef ASSERT
1066   // Returns whether p is in one of the available areas of the heap. Slow but
1067   // extensive version.
1068   bool is_in_exact(const void* p) const;
1069 #endif
1070 
1071   // Return "TRUE" iff the given object address is within the collection
1072   // set. Assumes that the reference points into the heap.
1073   inline bool is_in_cset(const HeapRegion *hr);
1074   inline bool is_in_cset(oop obj);
1075   inline bool is_in_cset(HeapWord* addr);
1076 
1077   inline bool is_in_cset_or_humongous(const oop obj);
1078 
1079  private:
1080   // This array is used for a quick test on whether a reference points into
1081   // the collection set or not. Each of the array's elements denotes whether the
1082   // corresponding region is in the collection set or not.
1083   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1084 
1085  public:
1086 
1087   inline InCSetState in_cset_state(const oop obj);
1088 
1089   // Return "TRUE" iff the given object address is in the reserved
1090   // region of g1.
1091   bool is_in_g1_reserved(const void* p) const {
1092     return _hrm.reserved().contains(p);
1093   }
1094 
1095   // Returns a MemRegion that corresponds to the space that has been
1096   // reserved for the heap
1097   MemRegion g1_reserved() const {
1098     return _hrm.reserved();
1099   }
1100 
1101   virtual bool is_in_closed_subset(const void* p) const;
1102 
1103   G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1104 
1105   G1CardTable* card_table() const {
1106     return _card_table;
1107   }
1108 
1109   // Iteration functions.
1110 
1111   // Iterate over all objects, calling "cl.do_object" on each.
1112   virtual void object_iterate(ObjectClosure* cl);
1113 
1114   virtual void safe_object_iterate(ObjectClosure* cl) {
1115     object_iterate(cl);
1116   }
1117 
1118   // Iterate over heap regions, in address order, terminating the
1119   // iteration early if the "do_heap_region" method returns "true".
1120   void heap_region_iterate(HeapRegionClosure* blk) const;
1121 
1122   // Return the region with the given index. It assumes the index is valid.
1123   inline HeapRegion* region_at(uint index) const;
1124 
1125   // Return the next region (by index) that is part of the same
1126   // humongous object that hr is part of.
1127   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1128 
1129   // Calculate the region index of the given address. Given address must be
1130   // within the heap.
1131   inline uint addr_to_region(HeapWord* addr) const;
1132 
1133   inline HeapWord* bottom_addr_for_region(uint index) const;
1134 
1135   // Two functions to iterate over the heap regions in parallel. Threads
1136   // compete using the HeapRegionClaimer to claim the regions before
1137   // applying the closure on them.
1138   // The _from_worker_offset version uses the HeapRegionClaimer and
1139   // the worker id to calculate a start offset to prevent all workers to
1140   // start from the point.
1141   void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1142                                                   HeapRegionClaimer* hrclaimer,
1143                                                   uint worker_id) const;
1144 
1145   void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1146                                           HeapRegionClaimer* hrclaimer) const;
1147 
1148   // Iterate over the regions (if any) in the current collection set.
1149   void collection_set_iterate(HeapRegionClosure* blk);
1150 
1151   // Iterate over the regions (if any) in the current collection set. Starts the
1152   // iteration over the entire collection set so that the start regions of a given
1153   // worker id over the set active_workers are evenly spread across the set of
1154   // collection set regions.
1155   void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1156 
1157   // Returns the HeapRegion that contains addr. addr must not be NULL.
1158   template <class T>
1159   inline HeapRegion* heap_region_containing(const T addr) const;
1160 
1161   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1162   // each address in the (reserved) heap is a member of exactly
1163   // one block.  The defining characteristic of a block is that it is
1164   // possible to find its size, and thus to progress forward to the next
1165   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1166   // represent Java objects, or they might be free blocks in a
1167   // free-list-based heap (or subheap), as long as the two kinds are
1168   // distinguishable and the size of each is determinable.
1169 
1170   // Returns the address of the start of the "block" that contains the
1171   // address "addr".  We say "blocks" instead of "object" since some heaps
1172   // may not pack objects densely; a chunk may either be an object or a
1173   // non-object.
1174   virtual HeapWord* block_start(const void* addr) const;
1175 
1176   // Requires "addr" to be the start of a chunk, and returns its size.
1177   // "addr + size" is required to be the start of a new chunk, or the end
1178   // of the active area of the heap.
1179   virtual size_t block_size(const HeapWord* addr) const;
1180 
1181   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1182   // the block is an object.
1183   virtual bool block_is_obj(const HeapWord* addr) const;
1184 
1185   // Section on thread-local allocation buffers (TLABs)
1186   // See CollectedHeap for semantics.
1187 
1188   bool supports_tlab_allocation() const;
1189   size_t tlab_capacity(Thread* ignored) const;
1190   size_t tlab_used(Thread* ignored) const;
1191   size_t max_tlab_size() const;
1192   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1193 
1194   inline bool is_in_young(const oop obj);
1195 
1196   // Returns "true" iff the given word_size is "very large".
1197   static bool is_humongous(size_t word_size) {
1198     // Note this has to be strictly greater-than as the TLABs
1199     // are capped at the humongous threshold and we want to
1200     // ensure that we don't try to allocate a TLAB as
1201     // humongous and that we don't allocate a humongous
1202     // object in a TLAB.
1203     return word_size > _humongous_object_threshold_in_words;
1204   }
1205 
1206   // Returns the humongous threshold for a specific region size
1207   static size_t humongous_threshold_for(size_t region_size) {
1208     return (region_size / 2);
1209   }
1210 
1211   // Returns the number of regions the humongous object of the given word size
1212   // requires.
1213   static size_t humongous_obj_size_in_regions(size_t word_size);
1214 
1215   // Print the maximum heap capacity.
1216   virtual size_t max_capacity() const;
1217 
1218   virtual jlong millis_since_last_gc();
1219 
1220 
1221   // Convenience function to be used in situations where the heap type can be
1222   // asserted to be this type.
1223   static G1CollectedHeap* heap();
1224 
1225   void set_region_short_lived_locked(HeapRegion* hr);
1226   // add appropriate methods for any other surv rate groups
1227 
1228   const G1SurvivorRegions* survivor() const { return &_survivor; }
1229 
1230   uint survivor_regions_count() const {
1231     return _survivor.length();
1232   }
1233 
1234   uint eden_regions_count() const {
1235     return _eden.length();
1236   }
1237 
1238   uint young_regions_count() const {
1239     return _eden.length() + _survivor.length();
1240   }
1241 
1242   uint old_regions_count() const { return _old_set.length(); }
1243 
1244   uint humongous_regions_count() const { return _humongous_set.length(); }
1245 
1246 #ifdef ASSERT
1247   bool check_young_list_empty();
1248 #endif
1249 
1250   // *** Stuff related to concurrent marking.  It's not clear to me that so
1251   // many of these need to be public.
1252 
1253   // The functions below are helper functions that a subclass of
1254   // "CollectedHeap" can use in the implementation of its virtual
1255   // functions.
1256   // This performs a concurrent marking of the live objects in a
1257   // bitmap off to the side.
1258   void do_concurrent_mark();
1259 
1260   bool is_marked_next(oop obj) const;
1261 
1262   // Determine if an object is dead, given the object and also
1263   // the region to which the object belongs. An object is dead
1264   // iff a) it was not allocated since the last mark, b) it
1265   // is not marked, and c) it is not in an archive region.
1266   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1267     return
1268       hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1269       !hr->is_archive();
1270   }
1271 
1272   // This function returns true when an object has been
1273   // around since the previous marking and hasn't yet
1274   // been marked during this marking, and is not in an archive region.
1275   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1276     return
1277       !hr->obj_allocated_since_next_marking(obj) &&
1278       !is_marked_next(obj) &&
1279       !hr->is_archive();
1280   }
1281 
1282   // Determine if an object is dead, given only the object itself.
1283   // This will find the region to which the object belongs and
1284   // then call the region version of the same function.
1285 
1286   // Added if it is NULL it isn't dead.
1287 
1288   inline bool is_obj_dead(const oop obj) const;
1289 
1290   inline bool is_obj_ill(const oop obj) const;
1291 
1292   inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1293   inline bool is_obj_dead_full(const oop obj) const;
1294 
1295   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1296 
1297   // Refinement
1298 
1299   G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1300 
1301   // Optimized nmethod scanning support routines
1302 
1303   // Is an oop scavengeable
1304   virtual bool is_scavengable(oop obj);
1305 
1306   // Register the given nmethod with the G1 heap.
1307   virtual void register_nmethod(nmethod* nm);
1308 
1309   // Unregister the given nmethod from the G1 heap.
1310   virtual void unregister_nmethod(nmethod* nm);
1311 
1312   // Free up superfluous code root memory.
1313   void purge_code_root_memory();
1314 
1315   // Rebuild the strong code root lists for each region
1316   // after a full GC.
1317   void rebuild_strong_code_roots();
1318 
1319   // Partial cleaning used when class unloading is disabled.
1320   // Let the caller choose what structures to clean out:
1321   // - StringTable
1322   // - SymbolTable
1323   // - StringDeduplication structures
1324   void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1325 
1326   // Complete cleaning used when class unloading is enabled.
1327   // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1328   void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1329 
1330   // Redirty logged cards in the refinement queue.
1331   void redirty_logged_cards();
1332   // Verification
1333 
1334   // Perform any cleanup actions necessary before allowing a verification.
1335   virtual void prepare_for_verify();
1336 
1337   // Perform verification.
1338 
1339   // vo == UsePrevMarking -> use "prev" marking information,
1340   // vo == UseNextMarking -> use "next" marking information
1341   // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1342   //
1343   // NOTE: Only the "prev" marking information is guaranteed to be
1344   // consistent most of the time, so most calls to this should use
1345   // vo == UsePrevMarking.
1346   // Currently, there is only one case where this is called with
1347   // vo == UseNextMarking, which is to verify the "next" marking
1348   // information at the end of remark.
1349   // Currently there is only one place where this is called with
1350   // vo == UseFullMarking, which is to verify the marking during a
1351   // full GC.
1352   void verify(VerifyOption vo);
1353 
1354   // WhiteBox testing support.
1355   virtual bool supports_concurrent_phase_control() const;
1356   virtual const char* const* concurrent_phases() const;
1357   virtual bool request_concurrent_phase(const char* phase);
1358 
1359   // The methods below are here for convenience and dispatch the
1360   // appropriate method depending on value of the given VerifyOption
1361   // parameter. The values for that parameter, and their meanings,
1362   // are the same as those above.
1363 
1364   bool is_obj_dead_cond(const oop obj,
1365                         const HeapRegion* hr,
1366                         const VerifyOption vo) const;
1367 
1368   bool is_obj_dead_cond(const oop obj,
1369                         const VerifyOption vo) const;
1370 
1371   G1HeapSummary create_g1_heap_summary();
1372   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1373 
1374   // Printing
1375 private:
1376   void print_heap_regions() const;
1377   void print_regions_on(outputStream* st) const;
1378 
1379 public:
1380   virtual void print_on(outputStream* st) const;
1381   virtual void print_extended_on(outputStream* st) const;
1382   virtual void print_on_error(outputStream* st) const;
1383 
1384   virtual void print_gc_threads_on(outputStream* st) const;
1385   virtual void gc_threads_do(ThreadClosure* tc) const;
1386 
1387   // Override
1388   void print_tracing_info() const;
1389 
1390   // The following two methods are helpful for debugging RSet issues.
1391   void print_cset_rsets() PRODUCT_RETURN;
1392   void print_all_rsets() PRODUCT_RETURN;
1393 
1394 public:
1395   size_t pending_card_num();
1396 
1397 private:
1398   size_t _max_heap_capacity;
1399 };
1400 
1401 class G1ParEvacuateFollowersClosure : public VoidClosure {
1402 private:
1403   double _start_term;
1404   double _term_time;
1405   size_t _term_attempts;
1406 
1407   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1408   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1409 protected:
1410   G1CollectedHeap*              _g1h;
1411   G1ParScanThreadState*         _par_scan_state;
1412   RefToScanQueueSet*            _queues;
1413   ParallelTaskTerminator*       _terminator;
1414 
1415   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1416   RefToScanQueueSet*      queues()         { return _queues; }
1417   ParallelTaskTerminator* terminator()     { return _terminator; }
1418 
1419 public:
1420   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1421                                 G1ParScanThreadState* par_scan_state,
1422                                 RefToScanQueueSet* queues,
1423                                 ParallelTaskTerminator* terminator)
1424     : _g1h(g1h), _par_scan_state(par_scan_state),
1425       _queues(queues), _terminator(terminator),
1426       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1427 
1428   void do_void();
1429 
1430   double term_time() const { return _term_time; }
1431   size_t term_attempts() const { return _term_attempts; }
1432 
1433 private:
1434   inline bool offer_termination();
1435 };
1436 
1437 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP