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/g1AllocationContext.hpp"
  30 #include "gc/g1/g1BiasedArray.hpp"
  31 #include "gc/g1/g1CollectionSet.hpp"
  32 #include "gc/g1/g1CollectorState.hpp"
  33 #include "gc/g1/g1ConcurrentMark.hpp"
  34 #include "gc/g1/g1EdenRegions.hpp"
  35 #include "gc/g1/g1EvacFailure.hpp"
  36 #include "gc/g1/g1EvacStats.hpp"
  37 #include "gc/g1/g1HeapTransition.hpp"
  38 #include "gc/g1/g1HeapVerifier.hpp"
  39 #include "gc/g1/g1HRPrinter.hpp"
  40 #include "gc/g1/g1InCSetState.hpp"
  41 #include "gc/g1/g1MonitoringSupport.hpp"
  42 #include "gc/g1/g1SATBCardTableModRefBS.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 "memory/memRegion.hpp"
  53 #include "services/memoryManager.hpp"
  54 #include "utilities/stack.hpp"
  55 
  56 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  57 // It uses the "Garbage First" heap organization and algorithm, which
  58 // may combine concurrent marking with parallel, incremental compaction of
  59 // heap subsets that will yield large amounts of garbage.
  60 
  61 // Forward declarations
  62 class HeapRegion;
  63 class HRRSCleanupTask;
  64 class GenerationSpec;
  65 class G1ParScanThreadState;
  66 class G1ParScanThreadStateSet;
  67 class G1ParScanThreadState;
  68 class MemoryPool;
  69 class ObjectClosure;
  70 class SpaceClosure;
  71 class CompactibleSpaceClosure;
  72 class Space;
  73 class G1CollectionSet;
  74 class G1CollectorPolicy;
  75 class G1Policy;
  76 class G1HotCardCache;
  77 class G1RemSet;
  78 class G1YoungRemSetSamplingThread;
  79 class HeapRegionRemSetIterator;
  80 class G1ConcurrentMark;
  81 class ConcurrentMarkThread;
  82 class G1ConcurrentRefine;
  83 class GenerationCounters;
  84 class STWGCTimer;
  85 class G1NewTracer;
  86 class EvacuationFailedInfo;
  87 class nmethod;
  88 class Ticks;
  89 class WorkGang;
  90 class G1Allocator;
  91 class G1ArchiveAllocator;
  92 class G1FullGCScope;
  93 class G1HeapVerifier;
  94 class G1HeapSizingPolicy;
  95 class G1HeapSummary;
  96 class G1EvacSummary;
  97 
  98 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
  99 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
 100 
 101 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
 102 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
 103 
 104 // The G1 STW is alive closure.
 105 // An instance is embedded into the G1CH and used as the
 106 // (optional) _is_alive_non_header closure in the STW
 107 // reference processor. It is also extensively used during
 108 // reference processing during STW evacuation pauses.
 109 class G1STWIsAliveClosure: public BoolObjectClosure {
 110   G1CollectedHeap* _g1;
 111 public:
 112   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 113   bool do_object_b(oop p);
 114 };
 115 
 116 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 117  private:
 118   void reset_from_card_cache(uint start_idx, size_t num_regions);
 119  public:
 120   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 121 };
 122 
 123 class G1CollectedHeap : public CollectedHeap {
 124   friend class G1FreeCollectionSetTask;
 125   friend class VM_CollectForMetadataAllocation;
 126   friend class VM_G1CollectForAllocation;
 127   friend class VM_G1CollectFull;
 128   friend class VMStructs;
 129   friend class MutatorAllocRegion;
 130   friend class G1FullCollector;
 131   friend class G1GCAllocRegion;
 132   friend class G1HeapVerifier;
 133 
 134   // Closures used in implementation.
 135   friend class G1ParScanThreadState;
 136   friend class G1ParScanThreadStateSet;
 137   friend class G1ParTask;
 138   friend class G1PLABAllocator;
 139   friend class G1PrepareCompactClosure;
 140 
 141   // Other related classes.
 142   friend class HeapRegionClaimer;
 143 
 144   // Testing classes.
 145   friend class G1CheckCSetFastTableClosure;
 146 
 147 private:
 148   G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
 149 
 150   WorkGang* _workers;
 151   G1CollectorPolicy* _collector_policy;
 152 
 153   GCMemoryManager _memory_manager;
 154   GCMemoryManager _full_gc_memory_manager;
 155 
 156   MemoryPool* _eden_pool;
 157   MemoryPool* _survivor_pool;
 158   MemoryPool* _old_pool;
 159 
 160   static size_t _humongous_object_threshold_in_words;
 161 
 162   // The secondary free list which contains regions that have been
 163   // freed up during the cleanup process. This will be appended to
 164   // the master free list when appropriate.
 165   FreeRegionList _secondary_free_list;
 166 
 167   // It keeps track of the old regions.
 168   HeapRegionSet _old_set;
 169 
 170   // It keeps track of the humongous regions.
 171   HeapRegionSet _humongous_set;
 172 
 173   virtual void initialize_serviceability();
 174 
 175   void eagerly_reclaim_humongous_regions();
 176   // Start a new incremental collection set for the next pause.
 177   void start_new_collection_set();
 178 
 179   // The number of regions we could create by expansion.
 180   uint _expansion_regions;
 181 
 182   // The block offset table for the G1 heap.
 183   G1BlockOffsetTable* _bot;
 184 
 185   // Tears down the region sets / lists so that they are empty and the
 186   // regions on the heap do not belong to a region set / list. The
 187   // only exception is the humongous set which we leave unaltered. If
 188   // free_list_only is true, it will only tear down the master free
 189   // list. It is called before a Full GC (free_list_only == false) or
 190   // before heap shrinking (free_list_only == true).
 191   void tear_down_region_sets(bool free_list_only);
 192 
 193   // Rebuilds the region sets / lists so that they are repopulated to
 194   // reflect the contents of the heap. The only exception is the
 195   // humongous set which was not torn down in the first place. If
 196   // free_list_only is true, it will only rebuild the master free
 197   // list. It is called after a Full GC (free_list_only == false) or
 198   // after heap shrinking (free_list_only == true).
 199   void rebuild_region_sets(bool free_list_only);
 200 
 201   // Callback for region mapping changed events.
 202   G1RegionMappingChangedListener _listener;
 203 
 204   // The sequence of all heap regions in the heap.
 205   HeapRegionManager _hrm;
 206 
 207   // Manages all allocations with regions except humongous object allocations.
 208   G1Allocator* _allocator;
 209 
 210   // Manages all heap verification.
 211   G1HeapVerifier* _verifier;
 212 
 213   // Outside of GC pauses, the number of bytes used in all regions other
 214   // than the current allocation region(s).
 215   size_t _summary_bytes_used;
 216 
 217   void increase_used(size_t bytes);
 218   void decrease_used(size_t bytes);
 219 
 220   void set_used(size_t bytes);
 221 
 222   // Class that handles archive allocation ranges.
 223   G1ArchiveAllocator* _archive_allocator;
 224 
 225   // Statistics for each allocation context
 226   AllocationContextStats _allocation_context_stats;
 227 
 228   // GC allocation statistics policy for survivors.
 229   G1EvacStats _survivor_evac_stats;
 230 
 231   // GC allocation statistics policy for tenured objects.
 232   G1EvacStats _old_evac_stats;
 233 
 234   // It specifies whether we should attempt to expand the heap after a
 235   // region allocation failure. If heap expansion fails we set this to
 236   // false so that we don't re-attempt the heap expansion (it's likely
 237   // that subsequent expansion attempts will also fail if one fails).
 238   // Currently, it is only consulted during GC and it's reset at the
 239   // start of each GC.
 240   bool _expand_heap_after_alloc_failure;
 241 
 242   // Helper for monitoring and management support.
 243   G1MonitoringSupport* _g1mm;
 244 
 245   // Records whether the region at the given index is (still) a
 246   // candidate for eager reclaim.  Only valid for humongous start
 247   // regions; other regions have unspecified values.  Humongous start
 248   // regions are initialized at start of collection pause, with
 249   // candidates removed from the set as they are found reachable from
 250   // roots or the young generation.
 251   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 252    protected:
 253     bool default_value() const { return false; }
 254    public:
 255     void clear() { G1BiasedMappedArray<bool>::clear(); }
 256     void set_candidate(uint region, bool value) {
 257       set_by_index(region, value);
 258     }
 259     bool is_candidate(uint region) {
 260       return get_by_index(region);
 261     }
 262   };
 263 
 264   HumongousReclaimCandidates _humongous_reclaim_candidates;
 265   // Stores whether during humongous object registration we found candidate regions.
 266   // If not, we can skip a few steps.
 267   bool _has_humongous_reclaim_candidates;
 268 
 269   volatile uint _gc_time_stamp;
 270 
 271   G1HRPrinter _hr_printer;
 272 
 273   // It decides whether an explicit GC should start a concurrent cycle
 274   // instead of doing a STW GC. Currently, a concurrent cycle is
 275   // explicitly started if:
 276   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 277   // (b) cause == _g1_humongous_allocation
 278   // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 279   // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 280   // (e) cause == _update_allocation_context_stats_inc
 281   // (f) cause == _wb_conc_mark
 282   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 283 
 284   // indicates whether we are in young or mixed GC mode
 285   G1CollectorState _collector_state;
 286 
 287   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 288   // concurrent cycles) we have started.
 289   volatile uint _old_marking_cycles_started;
 290 
 291   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 292   // concurrent cycles) we have completed.
 293   volatile uint _old_marking_cycles_completed;
 294 
 295   // This is a non-product method that is helpful for testing. It is
 296   // called at the end of a GC and artificially expands the heap by
 297   // allocating a number of dead regions. This way we can induce very
 298   // frequent marking cycles and stress the cleanup / concurrent
 299   // cleanup code more (as all the regions that will be allocated by
 300   // this method will be found dead by the marking cycle).
 301   void allocate_dummy_regions() PRODUCT_RETURN;
 302 
 303   // Clear RSets after a compaction. It also resets the GC time stamps.
 304   void clear_rsets_post_compaction();
 305 
 306   // If the HR printer is active, dump the state of the regions in the
 307   // heap after a compaction.
 308   void print_hrm_post_compaction();
 309 
 310   // Create a memory mapper for auxiliary data structures of the given size and
 311   // translation factor.
 312   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 313                                                          size_t size,
 314                                                          size_t translation_factor);
 315 
 316   static G1Policy* create_g1_policy(STWGCTimer* gc_timer);
 317 
 318   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 319 
 320   // These are macros so that, if the assert fires, we get the correct
 321   // line number, file, etc.
 322 
 323 #define heap_locking_asserts_params(_extra_message_)                          \
 324   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 325   (_extra_message_),                                                          \
 326   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 327   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 328   BOOL_TO_STR(Thread::current()->is_VM_thread())
 329 
 330 #define assert_heap_locked()                                                  \
 331   do {                                                                        \
 332     assert(Heap_lock->owned_by_self(),                                        \
 333            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 334   } while (0)
 335 
 336 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 337   do {                                                                        \
 338     assert(Heap_lock->owned_by_self() ||                                      \
 339            (SafepointSynchronize::is_at_safepoint() &&                        \
 340              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 341            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 342                                         "should be at a safepoint"));         \
 343   } while (0)
 344 
 345 #define assert_heap_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 be holding the Heap_lock and "  \
 350                                        "should not be at a safepoint"));      \
 351   } while (0)
 352 
 353 #define assert_heap_not_locked()                                              \
 354   do {                                                                        \
 355     assert(!Heap_lock->owned_by_self(),                                       \
 356         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 357   } while (0)
 358 
 359 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 360   do {                                                                        \
 361     assert(!Heap_lock->owned_by_self() &&                                     \
 362                                     !SafepointSynchronize::is_at_safepoint(), \
 363       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 364                                    "should not be at a safepoint"));          \
 365   } while (0)
 366 
 367 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 368   do {                                                                        \
 369     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 370               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 371            heap_locking_asserts_params("should be at a safepoint"));          \
 372   } while (0)
 373 
 374 #define assert_not_at_safepoint()                                             \
 375   do {                                                                        \
 376     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 377            heap_locking_asserts_params("should not be at a safepoint"));      \
 378   } while (0)
 379 
 380 protected:
 381 
 382   // The young region list.
 383   G1EdenRegions _eden;
 384   G1SurvivorRegions _survivor;
 385 
 386   STWGCTimer* _gc_timer_stw;
 387 
 388   G1NewTracer* _gc_tracer_stw;
 389 
 390   // The current policy object for the collector.
 391   G1Policy* _g1_policy;
 392   G1HeapSizingPolicy* _heap_sizing_policy;
 393 
 394   G1CollectionSet _collection_set;
 395 
 396   // This is the second level of trying to allocate a new region. If
 397   // new_region() didn't find a region on the free_list, this call will
 398   // check whether there's anything available on the
 399   // secondary_free_list and/or wait for more regions to appear on
 400   // that list, if _free_regions_coming is set.
 401   HeapRegion* new_region_try_secondary_free_list(bool is_old);
 402 
 403   // Try to allocate a single non-humongous HeapRegion sufficient for
 404   // an allocation of the given word_size. If do_expand is true,
 405   // attempt to expand the heap if necessary to satisfy the allocation
 406   // request. If the region is to be used as an old region or for a
 407   // humongous object, set is_old to true. If not, to false.
 408   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 409 
 410   // Initialize a contiguous set of free regions of length num_regions
 411   // and starting at index first so that they appear as a single
 412   // humongous region.
 413   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 414                                                       uint num_regions,
 415                                                       size_t word_size,
 416                                                       AllocationContext_t context);
 417 
 418   // Attempt to allocate a humongous object of the given size. Return
 419   // NULL if unsuccessful.
 420   HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
 421 
 422   // The following two methods, allocate_new_tlab() and
 423   // mem_allocate(), are the two main entry points from the runtime
 424   // into the G1's allocation routines. They have the following
 425   // assumptions:
 426   //
 427   // * They should both be called outside safepoints.
 428   //
 429   // * They should both be called without holding the Heap_lock.
 430   //
 431   // * All allocation requests for new TLABs should go to
 432   //   allocate_new_tlab().
 433   //
 434   // * All non-TLAB allocation requests should go to mem_allocate().
 435   //
 436   // * If either call cannot satisfy the allocation request using the
 437   //   current allocating region, they will try to get a new one. If
 438   //   this fails, they will attempt to do an evacuation pause and
 439   //   retry the allocation.
 440   //
 441   // * If all allocation attempts fail, even after trying to schedule
 442   //   an evacuation pause, allocate_new_tlab() will return NULL,
 443   //   whereas mem_allocate() will attempt a heap expansion and/or
 444   //   schedule a Full GC.
 445   //
 446   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 447   //   should never be called with word_size being humongous. All
 448   //   humongous allocation requests should go to mem_allocate() which
 449   //   will satisfy them with a special path.
 450 
 451   virtual HeapWord* allocate_new_tlab(size_t word_size);
 452 
 453   virtual HeapWord* mem_allocate(size_t word_size,
 454                                  bool*  gc_overhead_limit_was_exceeded);
 455 
 456   // First-level mutator allocation attempt: try to allocate out of
 457   // the mutator alloc region without taking the Heap_lock. This
 458   // should only be used for non-humongous allocations.
 459   inline HeapWord* attempt_allocation(size_t word_size);
 460 
 461   // Second-level mutator allocation attempt: take the Heap_lock and
 462   // retry the allocation attempt, potentially scheduling a GC
 463   // pause. This should only be used for non-humongous allocations.
 464   HeapWord* attempt_allocation_slow(size_t word_size,
 465                                     AllocationContext_t context);
 466 
 467   // Takes the Heap_lock and attempts a humongous allocation. It can
 468   // potentially schedule a GC pause.
 469   HeapWord* attempt_allocation_humongous(size_t word_size);
 470 
 471   // Allocation attempt that should be called during safepoints (e.g.,
 472   // at the end of a successful GC). expect_null_mutator_alloc_region
 473   // specifies whether the mutator alloc region is expected to be NULL
 474   // or not.
 475   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 476                                             AllocationContext_t context,
 477                                             bool expect_null_mutator_alloc_region);
 478 
 479   // These methods are the "callbacks" from the G1AllocRegion class.
 480 
 481   // For mutator alloc regions.
 482   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 483   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 484                                    size_t allocated_bytes);
 485 
 486   // For GC alloc regions.
 487   bool has_more_regions(InCSetState dest);
 488   HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
 489   void retire_gc_alloc_region(HeapRegion* alloc_region,
 490                               size_t allocated_bytes, InCSetState dest);
 491 
 492   // - if explicit_gc is true, the GC is for a System.gc() etc,
 493   //   otherwise it's for a failed allocation.
 494   // - if clear_all_soft_refs is true, all soft references should be
 495   //   cleared during the GC.
 496   // - it returns false if it is unable to do the collection due to the
 497   //   GC locker being active, true otherwise.
 498   bool do_full_collection(bool explicit_gc,
 499                           bool clear_all_soft_refs);
 500 
 501   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 502   virtual void do_full_collection(bool clear_all_soft_refs);
 503 
 504   // Resize the heap if necessary after a full collection.
 505   void resize_if_necessary_after_full_collection();
 506 
 507   // Callback from VM_G1CollectForAllocation operation.
 508   // This function does everything necessary/possible to satisfy a
 509   // failed allocation request (including collection, expansion, etc.)
 510   HeapWord* satisfy_failed_allocation(size_t word_size,
 511                                       AllocationContext_t context,
 512                                       bool* succeeded);
 513 private:
 514   // Internal helpers used during full GC to split it up to
 515   // increase readability.
 516   void abort_concurrent_cycle();
 517   void verify_before_full_collection(bool explicit_gc);
 518   void prepare_heap_for_full_collection();
 519   void prepare_heap_for_mutators();
 520   void abort_refinement();
 521   void verify_after_full_collection();
 522   void print_heap_after_full_collection(G1HeapTransition* heap_transition);
 523 
 524   // Helper method for satisfy_failed_allocation()
 525   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 526                                              AllocationContext_t context,
 527                                              bool do_gc,
 528                                              bool clear_all_soft_refs,
 529                                              bool expect_null_mutator_alloc_region,
 530                                              bool* gc_succeeded);
 531 
 532 protected:
 533   // Attempting to expand the heap sufficiently
 534   // to support an allocation of the given "word_size".  If
 535   // successful, perform the allocation and return the address of the
 536   // allocated block, or else "NULL".
 537   HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
 538 
 539   // Preserve any referents discovered by concurrent marking that have not yet been
 540   // copied by the STW pause.
 541   void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
 542   // Process any reference objects discovered during
 543   // an incremental evacuation pause.
 544   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 545 
 546   // Enqueue any remaining discovered references
 547   // after processing.
 548   void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 549 
 550   // Merges the information gathered on a per-thread basis for all worker threads
 551   // during GC into global variables.
 552   void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
 553 public:
 554   G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
 555 
 556   WorkGang* workers() const { return _workers; }
 557 
 558   G1Allocator* allocator() {
 559     return _allocator;
 560   }
 561 
 562   G1HeapVerifier* verifier() {
 563     return _verifier;
 564   }
 565 
 566   G1MonitoringSupport* g1mm() {
 567     assert(_g1mm != NULL, "should have been initialized");
 568     return _g1mm;
 569   }
 570 
 571   // Expand the garbage-first heap by at least the given size (in bytes!).
 572   // Returns true if the heap was expanded by the requested amount;
 573   // false otherwise.
 574   // (Rounds up to a HeapRegion boundary.)
 575   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 576 
 577   // Returns the PLAB statistics for a given destination.
 578   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 579 
 580   // Determines PLAB size for a given destination.
 581   inline size_t desired_plab_sz(InCSetState dest);
 582 
 583   inline AllocationContextStats& allocation_context_stats();
 584 
 585   // Do anything common to GC's.
 586   void gc_prologue(bool full);
 587   void gc_epilogue(bool full);
 588 
 589   // Modify the reclaim candidate set and test for presence.
 590   // These are only valid for starts_humongous regions.
 591   inline void set_humongous_reclaim_candidate(uint region, bool value);
 592   inline bool is_humongous_reclaim_candidate(uint region);
 593 
 594   // Remove from the reclaim candidate set.  Also remove from the
 595   // collection set so that later encounters avoid the slow path.
 596   inline void set_humongous_is_live(oop obj);
 597 
 598   // Register the given region to be part of the collection set.
 599   inline void register_humongous_region_with_cset(uint index);
 600   // Register regions with humongous objects (actually on the start region) in
 601   // the in_cset_fast_test table.
 602   void register_humongous_regions_with_cset();
 603   // We register a region with the fast "in collection set" test. We
 604   // simply set to true the array slot corresponding to this region.
 605   void register_young_region_with_cset(HeapRegion* r) {
 606     _in_cset_fast_test.set_in_young(r->hrm_index());
 607   }
 608   void register_old_region_with_cset(HeapRegion* r) {
 609     _in_cset_fast_test.set_in_old(r->hrm_index());
 610   }
 611   inline void register_ext_region_with_cset(HeapRegion* r) {
 612     _in_cset_fast_test.set_ext(r->hrm_index());
 613   }
 614   void clear_in_cset(const HeapRegion* hr) {
 615     _in_cset_fast_test.clear(hr);
 616   }
 617 
 618   void clear_cset_fast_test() {
 619     _in_cset_fast_test.clear();
 620   }
 621 
 622   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 623 
 624   // This is called at the start of either a concurrent cycle or a Full
 625   // GC to update the number of old marking cycles started.
 626   void increment_old_marking_cycles_started();
 627 
 628   // This is called at the end of either a concurrent cycle or a Full
 629   // GC to update the number of old marking cycles completed. Those two
 630   // can happen in a nested fashion, i.e., we start a concurrent
 631   // cycle, a Full GC happens half-way through it which ends first,
 632   // and then the cycle notices that a Full GC happened and ends
 633   // too. The concurrent parameter is a boolean to help us do a bit
 634   // tighter consistency checking in the method. If concurrent is
 635   // false, the caller is the inner caller in the nesting (i.e., the
 636   // Full GC). If concurrent is true, the caller is the outer caller
 637   // in this nesting (i.e., the concurrent cycle). Further nesting is
 638   // not currently supported. The end of this call also notifies
 639   // the FullGCCount_lock in case a Java thread is waiting for a full
 640   // GC to happen (e.g., it called System.gc() with
 641   // +ExplicitGCInvokesConcurrent).
 642   void increment_old_marking_cycles_completed(bool concurrent);
 643 
 644   uint old_marking_cycles_completed() {
 645     return _old_marking_cycles_completed;
 646   }
 647 
 648   G1HRPrinter* hr_printer() { return &_hr_printer; }
 649 
 650   // Allocates a new heap region instance.
 651   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 652 
 653   // Allocate the highest free region in the reserved heap. This will commit
 654   // regions as necessary.
 655   HeapRegion* alloc_highest_free_region();
 656 
 657   // Frees a non-humongous region by initializing its contents and
 658   // adding it to the free list that's passed as a parameter (this is
 659   // usually a local list which will be appended to the master free
 660   // list later). The used bytes of freed regions are accumulated in
 661   // pre_used. If skip_remset is true, the region's RSet will not be freed
 662   // up. If skip_hot_card_cache is true, the region's hot card cache will not
 663   // be freed up. The assumption is that this will be done later.
 664   // The locked parameter indicates if the caller has already taken
 665   // care of proper synchronization. This may allow some optimizations.
 666   void free_region(HeapRegion* hr,
 667                    FreeRegionList* free_list,
 668                    bool skip_remset,
 669                    bool skip_hot_card_cache = false,
 670                    bool locked = false);
 671 
 672   // It dirties the cards that cover the block so that the post
 673   // write barrier never queues anything when updating objects on this
 674   // block. It is assumed (and in fact we assert) that the block
 675   // belongs to a young region.
 676   inline void dirty_young_block(HeapWord* start, size_t word_size);
 677 
 678   // Frees a humongous region by collapsing it into individual regions
 679   // and calling free_region() for each of them. The freed regions
 680   // will be added to the free list that's passed as a parameter (this
 681   // is usually a local list which will be appended to the master free
 682   // list later). The used bytes of freed regions are accumulated in
 683   // pre_used. If skip_remset is true, the region's RSet will not be freed
 684   // up. The assumption is that this will be done later.
 685   void free_humongous_region(HeapRegion* hr,
 686                              FreeRegionList* free_list,
 687                              bool skip_remset);
 688 
 689   // Facility for allocating in 'archive' regions in high heap memory and
 690   // recording the allocated ranges. These should all be called from the
 691   // VM thread at safepoints, without the heap lock held. They can be used
 692   // to create and archive a set of heap regions which can be mapped at the
 693   // same fixed addresses in a subsequent JVM invocation.
 694   void begin_archive_alloc_range(bool open = false);
 695 
 696   // Check if the requested size would be too large for an archive allocation.
 697   bool is_archive_alloc_too_large(size_t word_size);
 698 
 699   // Allocate memory of the requested size from the archive region. This will
 700   // return NULL if the size is too large or if no memory is available. It
 701   // does not trigger a garbage collection.
 702   HeapWord* archive_mem_allocate(size_t word_size);
 703 
 704   // Optionally aligns the end address and returns the allocated ranges in
 705   // an array of MemRegions in order of ascending addresses.
 706   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 707                                size_t end_alignment_in_bytes = 0);
 708 
 709   // Facility for allocating a fixed range within the heap and marking
 710   // the containing regions as 'archive'. For use at JVM init time, when the
 711   // caller may mmap archived heap data at the specified range(s).
 712   // Verify that the MemRegions specified in the argument array are within the
 713   // reserved heap.
 714   bool check_archive_addresses(MemRegion* range, size_t count);
 715 
 716   // Commit the appropriate G1 regions containing the specified MemRegions
 717   // and mark them as 'archive' regions. The regions in the array must be
 718   // non-overlapping and in order of ascending address.
 719   bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
 720 
 721   // Insert any required filler objects in the G1 regions around the specified
 722   // ranges to make the regions parseable. This must be called after
 723   // alloc_archive_regions, and after class loading has occurred.
 724   void fill_archive_regions(MemRegion* range, size_t count);
 725 
 726   // For each of the specified MemRegions, uncommit the containing G1 regions
 727   // which had been allocated by alloc_archive_regions. This should be called
 728   // rather than fill_archive_regions at JVM init time if the archive file
 729   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 730   void dealloc_archive_regions(MemRegion* range, size_t count);
 731 
 732 protected:
 733 
 734   // Shrink the garbage-first heap by at most the given size (in bytes!).
 735   // (Rounds down to a HeapRegion boundary.)
 736   virtual void shrink(size_t expand_bytes);
 737   void shrink_helper(size_t expand_bytes);
 738 
 739   #if TASKQUEUE_STATS
 740   static void print_taskqueue_stats_hdr(outputStream* const st);
 741   void print_taskqueue_stats() const;
 742   void reset_taskqueue_stats();
 743   #endif // TASKQUEUE_STATS
 744 
 745   // Schedule the VM operation that will do an evacuation pause to
 746   // satisfy an allocation request of word_size. *succeeded will
 747   // return whether the VM operation was successful (it did do an
 748   // evacuation pause) or not (another thread beat us to it or the GC
 749   // locker was active). Given that we should not be holding the
 750   // Heap_lock when we enter this method, we will pass the
 751   // gc_count_before (i.e., total_collections()) as a parameter since
 752   // it has to be read while holding the Heap_lock. Currently, both
 753   // methods that call do_collection_pause() release the Heap_lock
 754   // before the call, so it's easy to read gc_count_before just before.
 755   HeapWord* do_collection_pause(size_t         word_size,
 756                                 uint           gc_count_before,
 757                                 bool*          succeeded,
 758                                 GCCause::Cause gc_cause);
 759 
 760   void wait_for_root_region_scanning();
 761 
 762   // The guts of the incremental collection pause, executed by the vm
 763   // thread. It returns false if it is unable to do the collection due
 764   // to the GC locker being active, true otherwise
 765   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 766 
 767   // Actually do the work of evacuating the collection set.
 768   virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
 769 
 770   void pre_evacuate_collection_set();
 771   void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 772 
 773   // Print the header for the per-thread termination statistics.
 774   static void print_termination_stats_hdr();
 775   // Print actual per-thread termination statistics.
 776   void print_termination_stats(uint worker_id,
 777                                double elapsed_ms,
 778                                double strong_roots_ms,
 779                                double term_ms,
 780                                size_t term_attempts,
 781                                size_t alloc_buffer_waste,
 782                                size_t undo_waste) const;
 783   // Update object copying statistics.
 784   void record_obj_copy_mem_stats();
 785 
 786   // The hot card cache for remembered set insertion optimization.
 787   G1HotCardCache* _hot_card_cache;
 788 
 789   // The g1 remembered set of the heap.
 790   G1RemSet* _g1_rem_set;
 791 
 792   // A set of cards that cover the objects for which the Rsets should be updated
 793   // concurrently after the collection.
 794   DirtyCardQueueSet _dirty_card_queue_set;
 795 
 796   // After a collection pause, convert the regions in the collection set into free
 797   // regions.
 798   void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 799 
 800   // Abandon the current collection set without recording policy
 801   // statistics or updating free lists.
 802   void abandon_collection_set(G1CollectionSet* collection_set);
 803 
 804   // The concurrent marker (and the thread it runs in.)
 805   G1ConcurrentMark* _cm;
 806   ConcurrentMarkThread* _cmThread;
 807 
 808   // The concurrent refiner.
 809   G1ConcurrentRefine* _cr;
 810 
 811   // The parallel task queues
 812   RefToScanQueueSet *_task_queues;
 813 
 814   // True iff a evacuation has failed in the current collection.
 815   bool _evacuation_failed;
 816 
 817   EvacuationFailedInfo* _evacuation_failed_info_array;
 818 
 819   // Failed evacuations cause some logical from-space objects to have
 820   // forwarding pointers to themselves.  Reset them.
 821   void remove_self_forwarding_pointers();
 822 
 823   // Restore the objects in the regions in the collection set after an
 824   // evacuation failure.
 825   void restore_after_evac_failure();
 826 
 827   PreservedMarksSet _preserved_marks_set;
 828 
 829   // Preserve the mark of "obj", if necessary, in preparation for its mark
 830   // word being overwritten with a self-forwarding-pointer.
 831   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 832 
 833 #ifndef PRODUCT
 834   // Support for forcing evacuation failures. Analogous to
 835   // PromotionFailureALot for the other collectors.
 836 
 837   // Records whether G1EvacuationFailureALot should be in effect
 838   // for the current GC
 839   bool _evacuation_failure_alot_for_current_gc;
 840 
 841   // Used to record the GC number for interval checking when
 842   // determining whether G1EvaucationFailureALot is in effect
 843   // for the current GC.
 844   size_t _evacuation_failure_alot_gc_number;
 845 
 846   // Count of the number of evacuations between failures.
 847   volatile size_t _evacuation_failure_alot_count;
 848 
 849   // Set whether G1EvacuationFailureALot should be in effect
 850   // for the current GC (based upon the type of GC and which
 851   // command line flags are set);
 852   inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
 853                                                   bool during_initial_mark,
 854                                                   bool during_marking);
 855 
 856   inline void set_evacuation_failure_alot_for_current_gc();
 857 
 858   // Return true if it's time to cause an evacuation failure.
 859   inline bool evacuation_should_fail();
 860 
 861   // Reset the G1EvacuationFailureALot counters.  Should be called at
 862   // the end of an evacuation pause in which an evacuation failure occurred.
 863   inline void reset_evacuation_should_fail();
 864 #endif // !PRODUCT
 865 
 866   // ("Weak") Reference processing support.
 867   //
 868   // G1 has 2 instances of the reference processor class. One
 869   // (_ref_processor_cm) handles reference object discovery
 870   // and subsequent processing during concurrent marking cycles.
 871   //
 872   // The other (_ref_processor_stw) handles reference object
 873   // discovery and processing during full GCs and incremental
 874   // evacuation pauses.
 875   //
 876   // During an incremental pause, reference discovery will be
 877   // temporarily disabled for _ref_processor_cm and will be
 878   // enabled for _ref_processor_stw. At the end of the evacuation
 879   // pause references discovered by _ref_processor_stw will be
 880   // processed and discovery will be disabled. The previous
 881   // setting for reference object discovery for _ref_processor_cm
 882   // will be re-instated.
 883   //
 884   // At the start of marking:
 885   //  * Discovery by the CM ref processor is verified to be inactive
 886   //    and it's discovered lists are empty.
 887   //  * Discovery by the CM ref processor is then enabled.
 888   //
 889   // At the end of marking:
 890   //  * Any references on the CM ref processor's discovered
 891   //    lists are processed (possibly MT).
 892   //
 893   // At the start of full GC we:
 894   //  * Disable discovery by the CM ref processor and
 895   //    empty CM ref processor's discovered lists
 896   //    (without processing any entries).
 897   //  * Verify that the STW ref processor is inactive and it's
 898   //    discovered lists are empty.
 899   //  * Temporarily set STW ref processor discovery as single threaded.
 900   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 901   //    field.
 902   //  * Finally enable discovery by the STW ref processor.
 903   //
 904   // The STW ref processor is used to record any discovered
 905   // references during the full GC.
 906   //
 907   // At the end of a full GC we:
 908   //  * Enqueue any reference objects discovered by the STW ref processor
 909   //    that have non-live referents. This has the side-effect of
 910   //    making the STW ref processor inactive by disabling discovery.
 911   //  * Verify that the CM ref processor is still inactive
 912   //    and no references have been placed on it's discovered
 913   //    lists (also checked as a precondition during initial marking).
 914 
 915   // The (stw) reference processor...
 916   ReferenceProcessor* _ref_processor_stw;
 917 
 918   // During reference object discovery, the _is_alive_non_header
 919   // closure (if non-null) is applied to the referent object to
 920   // determine whether the referent is live. If so then the
 921   // reference object does not need to be 'discovered' and can
 922   // be treated as a regular oop. This has the benefit of reducing
 923   // the number of 'discovered' reference objects that need to
 924   // be processed.
 925   //
 926   // Instance of the is_alive closure for embedding into the
 927   // STW reference processor as the _is_alive_non_header field.
 928   // Supplying a value for the _is_alive_non_header field is
 929   // optional but doing so prevents unnecessary additions to
 930   // the discovered lists during reference discovery.
 931   G1STWIsAliveClosure _is_alive_closure_stw;
 932 
 933   // The (concurrent marking) reference processor...
 934   ReferenceProcessor* _ref_processor_cm;
 935 
 936   // Instance of the concurrent mark is_alive closure for embedding
 937   // into the Concurrent Marking reference processor as the
 938   // _is_alive_non_header field. Supplying a value for the
 939   // _is_alive_non_header field is optional but doing so prevents
 940   // unnecessary additions to the discovered lists during reference
 941   // discovery.
 942   G1CMIsAliveClosure _is_alive_closure_cm;
 943 
 944   volatile bool _free_regions_coming;
 945 
 946 public:
 947 
 948   RefToScanQueue *task_queue(uint i) const;
 949 
 950   uint num_task_queues() const;
 951 
 952   // A set of cards where updates happened during the GC
 953   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 954 
 955   // Create a G1CollectedHeap with the specified policy.
 956   // Must call the initialize method afterwards.
 957   // May not return if something goes wrong.
 958   G1CollectedHeap(G1CollectorPolicy* policy);
 959 
 960 private:
 961   jint initialize_concurrent_refinement();
 962   jint initialize_young_gen_sampling_thread();
 963 public:
 964   // Initialize the G1CollectedHeap to have the initial and
 965   // maximum sizes and remembered and barrier sets
 966   // specified by the policy object.
 967   jint initialize();
 968 
 969   virtual void stop();
 970   virtual void safepoint_synchronize_begin();
 971   virtual void safepoint_synchronize_end();
 972 
 973   // Return the (conservative) maximum heap alignment for any G1 heap
 974   static size_t conservative_max_heap_alignment();
 975 
 976   // Does operations required after initialization has been done.
 977   void post_initialize();
 978 
 979   // Initialize weak reference processing.
 980   void ref_processing_init();
 981 
 982   virtual Name kind() const {
 983     return CollectedHeap::G1CollectedHeap;
 984   }
 985 
 986   virtual const char* name() const {
 987     return "G1";
 988   }
 989 
 990   const G1CollectorState* collector_state() const { return &_collector_state; }
 991   G1CollectorState* collector_state() { return &_collector_state; }
 992 
 993   // The current policy object for the collector.
 994   G1Policy* g1_policy() const { return _g1_policy; }
 995 
 996   const G1CollectionSet* collection_set() const { return &_collection_set; }
 997   G1CollectionSet* collection_set() { return &_collection_set; }
 998 
 999   virtual CollectorPolicy* collector_policy() const;
1000 
1001   // Adaptive size policy.  No such thing for g1.
1002   virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1003 
1004   virtual GrowableArray<GCMemoryManager*> memory_managers();
1005   virtual GrowableArray<MemoryPool*> memory_pools();
1006 
1007   // The rem set and barrier set.
1008   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1009 
1010   // Try to minimize the remembered set.
1011   void scrub_rem_set();
1012 
1013   uint get_gc_time_stamp() {
1014     return _gc_time_stamp;
1015   }
1016 
1017   inline void reset_gc_time_stamp();
1018 
1019   void check_gc_time_stamps() PRODUCT_RETURN;
1020 
1021   inline void increment_gc_time_stamp();
1022 
1023   // Reset the given region's GC timestamp. If it's starts humongous,
1024   // also reset the GC timestamp of its corresponding
1025   // continues humongous regions too.
1026   void reset_gc_time_stamps(HeapRegion* hr);
1027 
1028   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1029   void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1030 
1031   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1032   void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1033 
1034   // The shared block offset table array.
1035   G1BlockOffsetTable* bot() const { return _bot; }
1036 
1037   // Reference Processing accessors
1038 
1039   // The STW reference processor....
1040   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1041 
1042   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1043 
1044   // The Concurrent Marking reference processor...
1045   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1046 
1047   size_t unused_committed_regions_in_bytes() const;
1048   virtual size_t capacity() const;
1049   virtual size_t used() const;
1050   // This should be called when we're not holding the heap lock. The
1051   // result might be a bit inaccurate.
1052   size_t used_unlocked() const;
1053   size_t recalculate_used() const;
1054 
1055   // These virtual functions do the actual allocation.
1056   // Some heaps may offer a contiguous region for shared non-blocking
1057   // allocation, via inlined code (by exporting the address of the top and
1058   // end fields defining the extent of the contiguous allocation region.)
1059   // But G1CollectedHeap doesn't yet support this.
1060 
1061   virtual bool is_maximal_no_gc() const {
1062     return _hrm.available() == 0;
1063   }
1064 
1065   // Returns whether there are any regions left in the heap for allocation.
1066   bool has_regions_left_for_allocation() const {
1067     return !is_maximal_no_gc() || num_free_regions() != 0;
1068   }
1069 
1070   // The current number of regions in the heap.
1071   uint num_regions() const { return _hrm.length(); }
1072 
1073   // The max number of regions in the heap.
1074   uint max_regions() const { return _hrm.max_length(); }
1075 
1076   // The number of regions that are completely free.
1077   uint num_free_regions() const { return _hrm.num_free_regions(); }
1078 
1079   MemoryUsage get_auxiliary_data_memory_usage() const {
1080     return _hrm.get_auxiliary_data_memory_usage();
1081   }
1082 
1083   // The number of regions that are not completely free.
1084   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1085 
1086 #ifdef ASSERT
1087   bool is_on_master_free_list(HeapRegion* hr) {
1088     return _hrm.is_free(hr);
1089   }
1090 #endif // ASSERT
1091 
1092   // Wrapper for the region list operations that can be called from
1093   // methods outside this class.
1094 
1095   void secondary_free_list_add(FreeRegionList* list) {
1096     _secondary_free_list.add_ordered(list);
1097   }
1098 
1099   void append_secondary_free_list() {
1100     _hrm.insert_list_into_free_list(&_secondary_free_list);
1101   }
1102 
1103   void append_secondary_free_list_if_not_empty_with_lock() {
1104     // If the secondary free list looks empty there's no reason to
1105     // take the lock and then try to append it.
1106     if (!_secondary_free_list.is_empty()) {
1107       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1108       append_secondary_free_list();
1109     }
1110   }
1111 
1112   inline void old_set_add(HeapRegion* hr);
1113   inline void old_set_remove(HeapRegion* hr);
1114 
1115   size_t non_young_capacity_bytes() {
1116     return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1117   }
1118 
1119   void set_free_regions_coming();
1120   void reset_free_regions_coming();
1121   bool free_regions_coming() { return _free_regions_coming; }
1122   void wait_while_free_regions_coming();
1123 
1124   // Determine whether the given region is one that we are using as an
1125   // old GC alloc region.
1126   bool is_old_gc_alloc_region(HeapRegion* hr);
1127 
1128   // Perform a collection of the heap; intended for use in implementing
1129   // "System.gc".  This probably implies as full a collection as the
1130   // "CollectedHeap" supports.
1131   virtual void collect(GCCause::Cause cause);
1132 
1133   virtual bool copy_allocation_context_stats(const jint* contexts,
1134                                              jlong* totals,
1135                                              jbyte* accuracy,
1136                                              jint len);
1137 
1138   // True iff an evacuation has failed in the most-recent collection.
1139   bool evacuation_failed() { return _evacuation_failed; }
1140 
1141   void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1142   void prepend_to_freelist(FreeRegionList* list);
1143   void decrement_summary_bytes(size_t bytes);
1144 
1145   virtual bool is_in(const void* p) const;
1146 #ifdef ASSERT
1147   // Returns whether p is in one of the available areas of the heap. Slow but
1148   // extensive version.
1149   bool is_in_exact(const void* p) const;
1150 #endif
1151 
1152   // Return "TRUE" iff the given object address is within the collection
1153   // set. Assumes that the reference points into the heap.
1154   inline bool is_in_cset(const HeapRegion *hr);
1155   inline bool is_in_cset(oop obj);
1156   inline bool is_in_cset(HeapWord* addr);
1157 
1158   inline bool is_in_cset_or_humongous(const oop obj);
1159 
1160  private:
1161   // This array is used for a quick test on whether a reference points into
1162   // the collection set or not. Each of the array's elements denotes whether the
1163   // corresponding region is in the collection set or not.
1164   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1165 
1166  public:
1167 
1168   inline InCSetState in_cset_state(const oop obj);
1169 
1170   // Return "TRUE" iff the given object address is in the reserved
1171   // region of g1.
1172   bool is_in_g1_reserved(const void* p) const {
1173     return _hrm.reserved().contains(p);
1174   }
1175 
1176   // Returns a MemRegion that corresponds to the space that has been
1177   // reserved for the heap
1178   MemRegion g1_reserved() const {
1179     return _hrm.reserved();
1180   }
1181 
1182   virtual bool is_in_closed_subset(const void* p) const;
1183 
1184   G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1185     return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1186   }
1187 
1188   G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1189 
1190   // Iteration functions.
1191 
1192   // Iterate over all objects, calling "cl.do_object" on each.
1193   virtual void object_iterate(ObjectClosure* cl);
1194 
1195   virtual void safe_object_iterate(ObjectClosure* cl) {
1196     object_iterate(cl);
1197   }
1198 
1199   // Iterate over heap regions, in address order, terminating the
1200   // iteration early if the "do_heap_region" method returns "true".
1201   void heap_region_iterate(HeapRegionClosure* blk) const;
1202 
1203   // Return the region with the given index. It assumes the index is valid.
1204   inline HeapRegion* region_at(uint index) const;
1205 
1206   // Return the next region (by index) that is part of the same
1207   // humongous object that hr is part of.
1208   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1209 
1210   // Calculate the region index of the given address. Given address must be
1211   // within the heap.
1212   inline uint addr_to_region(HeapWord* addr) const;
1213 
1214   inline HeapWord* bottom_addr_for_region(uint index) const;
1215 
1216   // Two functions to iterate over the heap regions in parallel. Threads
1217   // compete using the HeapRegionClaimer to claim the regions before
1218   // applying the closure on them.
1219   // The _from_worker_offset version uses the HeapRegionClaimer and
1220   // the worker id to calculate a start offset to prevent all workers to
1221   // start from the point.
1222   void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1223                                                   HeapRegionClaimer* hrclaimer,
1224                                                   uint worker_id) const;
1225 
1226   void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1227                                           HeapRegionClaimer* hrclaimer) const;
1228 
1229   // Iterate over the regions (if any) in the current collection set.
1230   void collection_set_iterate(HeapRegionClosure* blk);
1231 
1232   // Iterate over the regions (if any) in the current collection set. Starts the
1233   // iteration over the entire collection set so that the start regions of a given
1234   // worker id over the set active_workers are evenly spread across the set of
1235   // collection set regions.
1236   void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1237 
1238   // Returns the HeapRegion that contains addr. addr must not be NULL.
1239   template <class T>
1240   inline HeapRegion* heap_region_containing(const T addr) const;
1241 
1242   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1243   // each address in the (reserved) heap is a member of exactly
1244   // one block.  The defining characteristic of a block is that it is
1245   // possible to find its size, and thus to progress forward to the next
1246   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1247   // represent Java objects, or they might be free blocks in a
1248   // free-list-based heap (or subheap), as long as the two kinds are
1249   // distinguishable and the size of each is determinable.
1250 
1251   // Returns the address of the start of the "block" that contains the
1252   // address "addr".  We say "blocks" instead of "object" since some heaps
1253   // may not pack objects densely; a chunk may either be an object or a
1254   // non-object.
1255   virtual HeapWord* block_start(const void* addr) const;
1256 
1257   // Requires "addr" to be the start of a chunk, and returns its size.
1258   // "addr + size" is required to be the start of a new chunk, or the end
1259   // of the active area of the heap.
1260   virtual size_t block_size(const HeapWord* addr) const;
1261 
1262   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1263   // the block is an object.
1264   virtual bool block_is_obj(const HeapWord* addr) const;
1265 
1266   // Section on thread-local allocation buffers (TLABs)
1267   // See CollectedHeap for semantics.
1268 
1269   bool supports_tlab_allocation() const;
1270   size_t tlab_capacity(Thread* ignored) const;
1271   size_t tlab_used(Thread* ignored) const;
1272   size_t max_tlab_size() const;
1273   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1274 
1275   inline bool is_in_young(const oop obj);
1276 
1277   // Returns "true" iff the given word_size is "very large".
1278   static bool is_humongous(size_t word_size) {
1279     // Note this has to be strictly greater-than as the TLABs
1280     // are capped at the humongous threshold and we want to
1281     // ensure that we don't try to allocate a TLAB as
1282     // humongous and that we don't allocate a humongous
1283     // object in a TLAB.
1284     return word_size > _humongous_object_threshold_in_words;
1285   }
1286 
1287   // Returns the humongous threshold for a specific region size
1288   static size_t humongous_threshold_for(size_t region_size) {
1289     return (region_size / 2);
1290   }
1291 
1292   // Returns the number of regions the humongous object of the given word size
1293   // requires.
1294   static size_t humongous_obj_size_in_regions(size_t word_size);
1295 
1296   // Print the maximum heap capacity.
1297   virtual size_t max_capacity() const;
1298 
1299   virtual jlong millis_since_last_gc();
1300 
1301 
1302   // Convenience function to be used in situations where the heap type can be
1303   // asserted to be this type.
1304   static G1CollectedHeap* heap();
1305 
1306   void set_region_short_lived_locked(HeapRegion* hr);
1307   // add appropriate methods for any other surv rate groups
1308 
1309   const G1SurvivorRegions* survivor() const { return &_survivor; }
1310 
1311   uint survivor_regions_count() const {
1312     return _survivor.length();
1313   }
1314 
1315   uint eden_regions_count() const {
1316     return _eden.length();
1317   }
1318 
1319   uint young_regions_count() const {
1320     return _eden.length() + _survivor.length();
1321   }
1322 
1323   uint old_regions_count() const { return _old_set.length(); }
1324 
1325   uint humongous_regions_count() const { return _humongous_set.length(); }
1326 
1327 #ifdef ASSERT
1328   bool check_young_list_empty();
1329 #endif
1330 
1331   // *** Stuff related to concurrent marking.  It's not clear to me that so
1332   // many of these need to be public.
1333 
1334   // The functions below are helper functions that a subclass of
1335   // "CollectedHeap" can use in the implementation of its virtual
1336   // functions.
1337   // This performs a concurrent marking of the live objects in a
1338   // bitmap off to the side.
1339   void doConcurrentMark();
1340 
1341   bool isMarkedNext(oop obj) const;
1342 
1343   // Determine if an object is dead, given the object and also
1344   // the region to which the object belongs. An object is dead
1345   // iff a) it was not allocated since the last mark, b) it
1346   // is not marked, and c) it is not in an archive region.
1347   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1348     return
1349       hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1350       !hr->is_archive();
1351   }
1352 
1353   // This function returns true when an object has been
1354   // around since the previous marking and hasn't yet
1355   // been marked during this marking, and is not in an archive region.
1356   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1357     return
1358       !hr->obj_allocated_since_next_marking(obj) &&
1359       !isMarkedNext(obj) &&
1360       !hr->is_archive();
1361   }
1362 
1363   // Determine if an object is dead, given only the object itself.
1364   // This will find the region to which the object belongs and
1365   // then call the region version of the same function.
1366 
1367   // Added if it is NULL it isn't dead.
1368 
1369   inline bool is_obj_dead(const oop obj) const;
1370 
1371   inline bool is_obj_ill(const oop obj) const;
1372 
1373   inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1374   inline bool is_obj_dead_full(const oop obj) const;
1375 
1376   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1377 
1378   // Refinement
1379 
1380   G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1381 
1382   // Optimized nmethod scanning support routines
1383 
1384   // Is an oop scavengeable
1385   virtual bool is_scavengable(oop obj);
1386 
1387   // Register the given nmethod with the G1 heap.
1388   virtual void register_nmethod(nmethod* nm);
1389 
1390   // Unregister the given nmethod from the G1 heap.
1391   virtual void unregister_nmethod(nmethod* nm);
1392 
1393   // Free up superfluous code root memory.
1394   void purge_code_root_memory();
1395 
1396   // Rebuild the strong code root lists for each region
1397   // after a full GC.
1398   void rebuild_strong_code_roots();
1399 
1400   // Partial cleaning used when class unloading is disabled.
1401   // Let the caller choose what structures to clean out:
1402   // - StringTable
1403   // - SymbolTable
1404   // - StringDeduplication structures
1405   void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1406 
1407   // Complete cleaning used when class unloading is enabled.
1408   // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1409   void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1410 
1411   // Redirty logged cards in the refinement queue.
1412   void redirty_logged_cards();
1413   // Verification
1414 
1415   // Perform any cleanup actions necessary before allowing a verification.
1416   virtual void prepare_for_verify();
1417 
1418   // Perform verification.
1419 
1420   // vo == UsePrevMarking -> use "prev" marking information,
1421   // vo == UseNextMarking -> use "next" marking information
1422   // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1423   //
1424   // NOTE: Only the "prev" marking information is guaranteed to be
1425   // consistent most of the time, so most calls to this should use
1426   // vo == UsePrevMarking.
1427   // Currently, there is only one case where this is called with
1428   // vo == UseNextMarking, which is to verify the "next" marking
1429   // information at the end of remark.
1430   // Currently there is only one place where this is called with
1431   // vo == UseFullMarking, which is to verify the marking during a
1432   // full GC.
1433   void verify(VerifyOption vo);
1434 
1435   // WhiteBox testing support.
1436   virtual bool supports_concurrent_phase_control() const;
1437   virtual const char* const* concurrent_phases() const;
1438   virtual bool request_concurrent_phase(const char* phase);
1439 
1440   // The methods below are here for convenience and dispatch the
1441   // appropriate method depending on value of the given VerifyOption
1442   // parameter. The values for that parameter, and their meanings,
1443   // are the same as those above.
1444 
1445   bool is_obj_dead_cond(const oop obj,
1446                         const HeapRegion* hr,
1447                         const VerifyOption vo) const;
1448 
1449   bool is_obj_dead_cond(const oop obj,
1450                         const VerifyOption vo) const;
1451 
1452   G1HeapSummary create_g1_heap_summary();
1453   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1454 
1455   // Printing
1456 private:
1457   void print_heap_regions() const;
1458   void print_regions_on(outputStream* st) const;
1459 
1460 public:
1461   virtual void print_on(outputStream* st) const;
1462   virtual void print_extended_on(outputStream* st) const;
1463   virtual void print_on_error(outputStream* st) const;
1464 
1465   virtual void print_gc_threads_on(outputStream* st) const;
1466   virtual void gc_threads_do(ThreadClosure* tc) const;
1467 
1468   // Override
1469   void print_tracing_info() const;
1470 
1471   // The following two methods are helpful for debugging RSet issues.
1472   void print_cset_rsets() PRODUCT_RETURN;
1473   void print_all_rsets() PRODUCT_RETURN;
1474 
1475 public:
1476   size_t pending_card_num();
1477 
1478 protected:
1479   size_t _max_heap_capacity;
1480 };
1481 
1482 class G1ParEvacuateFollowersClosure : public VoidClosure {
1483 private:
1484   double _start_term;
1485   double _term_time;
1486   size_t _term_attempts;
1487 
1488   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1489   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1490 protected:
1491   G1CollectedHeap*              _g1h;
1492   G1ParScanThreadState*         _par_scan_state;
1493   RefToScanQueueSet*            _queues;
1494   ParallelTaskTerminator*       _terminator;
1495 
1496   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1497   RefToScanQueueSet*      queues()         { return _queues; }
1498   ParallelTaskTerminator* terminator()     { return _terminator; }
1499 
1500 public:
1501   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1502                                 G1ParScanThreadState* par_scan_state,
1503                                 RefToScanQueueSet* queues,
1504                                 ParallelTaskTerminator* terminator)
1505     : _g1h(g1h), _par_scan_state(par_scan_state),
1506       _queues(queues), _terminator(terminator),
1507       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1508 
1509   void do_void();
1510 
1511   double term_time() const { return _term_time; }
1512   size_t term_attempts() const { return _term_attempts; }
1513 
1514 private:
1515   inline bool offer_termination();
1516 };
1517 
1518 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP