1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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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/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/g1SATBCardTableModRefBS.hpp"
  44 #include "gc/g1/g1SurvivorRegions.hpp"
  45 #include "gc/g1/g1YCTypes.hpp"
  46 #include "gc/g1/heapRegionManager.hpp"
  47 #include "gc/g1/heapRegionSet.hpp"
  48 #include "gc/shared/barrierSet.hpp"
  49 #include "gc/shared/collectedHeap.hpp"
  50 #include "gc/shared/gcHeapSummary.hpp"
  51 #include "gc/shared/plab.hpp"
  52 #include "gc/shared/preservedMarks.hpp"
  53 #include "gc/shared/softRefPolicy.hpp"
  54 #include "memory/memRegion.hpp"
  55 #include "services/memoryManager.hpp"
  56 #include "utilities/stack.hpp"
  57 
  58 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  59 // It uses the "Garbage First" heap organization and algorithm, which
  60 // may combine concurrent marking with parallel, incremental compaction of
  61 // heap subsets that will yield large amounts of garbage.
  62 
  63 // Forward declarations
  64 class HeapRegion;
  65 class HRRSCleanupTask;
  66 class GenerationSpec;
  67 class G1ParScanThreadState;
  68 class G1ParScanThreadStateSet;
  69 class G1ParScanThreadState;
  70 class MemoryPool;
  71 class ObjectClosure;
  72 class SpaceClosure;
  73 class CompactibleSpaceClosure;
  74 class Space;
  75 class G1CollectionSet;
  76 class G1CollectorPolicy;
  77 class G1Policy;
  78 class G1HotCardCache;
  79 class G1RemSet;
  80 class G1YoungRemSetSamplingThread;
  81 class HeapRegionRemSetIterator;
  82 class G1ConcurrentMark;
  83 class ConcurrentMarkThread;
  84 class G1ConcurrentRefine;
  85 class GenerationCounters;
  86 class STWGCTimer;
  87 class G1NewTracer;
  88 class EvacuationFailedInfo;
  89 class nmethod;
  90 class Ticks;
  91 class WorkGang;
  92 class G1Allocator;
  93 class G1ArchiveAllocator;
  94 class G1FullGCScope;
  95 class G1HeapVerifier;
  96 class G1HeapSizingPolicy;
  97 class G1HeapSummary;
  98 class G1EvacSummary;
  99 
 100 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
 101 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
 102 
 103 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
 104 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
 105 
 106 // The G1 STW is alive closure.
 107 // An instance is embedded into the G1CH and used as the
 108 // (optional) _is_alive_non_header closure in the STW
 109 // reference processor. It is also extensively used during
 110 // reference processing during STW evacuation pauses.
 111 class G1STWIsAliveClosure: public BoolObjectClosure {
 112   G1CollectedHeap* _g1;
 113 public:
 114   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 115   bool do_object_b(oop p);
 116 };
 117 
 118 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 119  private:
 120   void reset_from_card_cache(uint start_idx, size_t num_regions);
 121  public:
 122   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 123 };
 124 
 125 class G1CollectedHeap : public CollectedHeap {
 126   friend class G1FreeCollectionSetTask;
 127   friend class VM_CollectForMetadataAllocation;
 128   friend class VM_G1CollectForAllocation;
 129   friend class VM_G1CollectFull;
 130   friend class VMStructs;
 131   friend class MutatorAllocRegion;
 132   friend class G1FullCollector;
 133   friend class G1GCAllocRegion;
 134   friend class G1HeapVerifier;
 135 
 136   // Closures used in implementation.
 137   friend class G1ParScanThreadState;
 138   friend class G1ParScanThreadStateSet;
 139   friend class G1ParTask;
 140   friend class G1PLABAllocator;
 141   friend class G1PrepareCompactClosure;
 142 
 143   // Other related classes.
 144   friend class HeapRegionClaimer;
 145 
 146   // Testing classes.
 147   friend class G1CheckCSetFastTableClosure;
 148 
 149 private:
 150   G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
 151 
 152   WorkGang* _workers;
 153   G1CollectorPolicy* _collector_policy;
 154   G1CardTable* _card_table;
 155 
 156   SoftRefPolicy      _soft_ref_policy;
 157 
 158   GCMemoryManager _memory_manager;
 159   GCMemoryManager _full_gc_memory_manager;
 160 
 161   MemoryPool* _eden_pool;
 162   MemoryPool* _survivor_pool;
 163   MemoryPool* _old_pool;
 164 
 165   static size_t _humongous_object_threshold_in_words;
 166 
 167   // The secondary free list which contains regions that have been
 168   // freed up during the cleanup process. This will be appended to
 169   // the master free list when appropriate.
 170   FreeRegionList _secondary_free_list;
 171 
 172   // It keeps track of the old regions.
 173   HeapRegionSet _old_set;
 174 
 175   // It keeps track of the humongous regions.
 176   HeapRegionSet _humongous_set;
 177 
 178   virtual void initialize_serviceability();
 179 
 180   void eagerly_reclaim_humongous_regions();
 181   // Start a new incremental collection set for the next pause.
 182   void start_new_collection_set();
 183 
 184   // The number of regions we could create by expansion.
 185   uint _expansion_regions;
 186 
 187   // The block offset table for the G1 heap.
 188   G1BlockOffsetTable* _bot;
 189 
 190   // Tears down the region sets / lists so that they are empty and the
 191   // regions on the heap do not belong to a region set / list. The
 192   // only exception is the humongous set which we leave unaltered. If
 193   // free_list_only is true, it will only tear down the master free
 194   // list. It is called before a Full GC (free_list_only == false) or
 195   // before heap shrinking (free_list_only == true).
 196   void tear_down_region_sets(bool free_list_only);
 197 
 198   // Rebuilds the region sets / lists so that they are repopulated to
 199   // reflect the contents of the heap. The only exception is the
 200   // humongous set which was not torn down in the first place. If
 201   // free_list_only is true, it will only rebuild the master free
 202   // list. It is called after a Full GC (free_list_only == false) or
 203   // after heap shrinking (free_list_only == true).
 204   void rebuild_region_sets(bool free_list_only);
 205 
 206   // Callback for region mapping changed events.
 207   G1RegionMappingChangedListener _listener;
 208 
 209   // The sequence of all heap regions in the heap.
 210   HeapRegionManager _hrm;
 211 
 212   // Manages all allocations with regions except humongous object allocations.
 213   G1Allocator* _allocator;
 214 
 215   // Manages all heap verification.
 216   G1HeapVerifier* _verifier;
 217 
 218   // Outside of GC pauses, the number of bytes used in all regions other
 219   // than the current allocation region(s).
 220   size_t _summary_bytes_used;
 221 
 222   void increase_used(size_t bytes);
 223   void decrease_used(size_t bytes);
 224 
 225   void set_used(size_t bytes);
 226 
 227   // Class that handles archive allocation ranges.
 228   G1ArchiveAllocator* _archive_allocator;
 229 
 230   // GC allocation statistics policy for survivors.
 231   G1EvacStats _survivor_evac_stats;
 232 
 233   // GC allocation statistics policy for tenured objects.
 234   G1EvacStats _old_evac_stats;
 235 
 236   // It specifies whether we should attempt to expand the heap after a
 237   // region allocation failure. If heap expansion fails we set this to
 238   // false so that we don't re-attempt the heap expansion (it's likely
 239   // that subsequent expansion attempts will also fail if one fails).
 240   // Currently, it is only consulted during GC and it's reset at the
 241   // start of each GC.
 242   bool _expand_heap_after_alloc_failure;
 243 
 244   // Helper for monitoring and management support.
 245   G1MonitoringSupport* _g1mm;
 246 
 247   // Records whether the region at the given index is (still) a
 248   // candidate for eager reclaim.  Only valid for humongous start
 249   // regions; other regions have unspecified values.  Humongous start
 250   // regions are initialized at start of collection pause, with
 251   // candidates removed from the set as they are found reachable from
 252   // roots or the young generation.
 253   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 254    protected:
 255     bool default_value() const { return false; }
 256    public:
 257     void clear() { G1BiasedMappedArray<bool>::clear(); }
 258     void set_candidate(uint region, bool value) {
 259       set_by_index(region, value);
 260     }
 261     bool is_candidate(uint region) {
 262       return get_by_index(region);
 263     }
 264   };
 265 
 266   HumongousReclaimCandidates _humongous_reclaim_candidates;
 267   // Stores whether during humongous object registration we found candidate regions.
 268   // If not, we can skip a few steps.
 269   bool _has_humongous_reclaim_candidates;
 270 
 271   volatile uint _gc_time_stamp;
 272 
 273   G1HRPrinter _hr_printer;
 274 
 275   // It decides whether an explicit GC should start a concurrent cycle
 276   // instead of doing a STW GC. Currently, a concurrent cycle is
 277   // explicitly started if:
 278   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 279   // (b) cause == _g1_humongous_allocation
 280   // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 281   // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 282   // (e) cause == _wb_conc_mark
 283   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 284 
 285   // indicates whether we are in young or mixed GC mode
 286   G1CollectorState _collector_state;
 287 
 288   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 289   // concurrent cycles) we have started.
 290   volatile uint _old_marking_cycles_started;
 291 
 292   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 293   // concurrent cycles) we have completed.
 294   volatile uint _old_marking_cycles_completed;
 295 
 296   // This is a non-product method that is helpful for testing. It is
 297   // called at the end of a GC and artificially expands the heap by
 298   // allocating a number of dead regions. This way we can induce very
 299   // frequent marking cycles and stress the cleanup / concurrent
 300   // cleanup code more (as all the regions that will be allocated by
 301   // this method will be found dead by the marking cycle).
 302   void allocate_dummy_regions() PRODUCT_RETURN;
 303 
 304   // Clear RSets after a compaction. It also resets the GC time stamps.
 305   void clear_rsets_post_compaction();
 306 
 307   // If the HR printer is active, dump the state of the regions in the
 308   // heap after a compaction.
 309   void print_hrm_post_compaction();
 310 
 311   // Create a memory mapper for auxiliary data structures of the given size and
 312   // translation factor.
 313   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 314                                                          size_t size,
 315                                                          size_t translation_factor);
 316 
 317   static G1Policy* create_g1_policy(STWGCTimer* gc_timer);
 318 
 319   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 320 
 321   // These are macros so that, if the assert fires, we get the correct
 322   // line number, file, etc.
 323 
 324 #define heap_locking_asserts_params(_extra_message_)                          \
 325   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 326   (_extra_message_),                                                          \
 327   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 328   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 329   BOOL_TO_STR(Thread::current()->is_VM_thread())
 330 
 331 #define assert_heap_locked()                                                  \
 332   do {                                                                        \
 333     assert(Heap_lock->owned_by_self(),                                        \
 334            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 335   } while (0)
 336 
 337 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 338   do {                                                                        \
 339     assert(Heap_lock->owned_by_self() ||                                      \
 340            (SafepointSynchronize::is_at_safepoint() &&                        \
 341              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 342            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 343                                         "should be at a safepoint"));         \
 344   } while (0)
 345 
 346 #define assert_heap_locked_and_not_at_safepoint()                             \
 347   do {                                                                        \
 348     assert(Heap_lock->owned_by_self() &&                                      \
 349                                     !SafepointSynchronize::is_at_safepoint(), \
 350           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 351                                        "should not be at a safepoint"));      \
 352   } while (0)
 353 
 354 #define assert_heap_not_locked()                                              \
 355   do {                                                                        \
 356     assert(!Heap_lock->owned_by_self(),                                       \
 357         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 358   } while (0)
 359 
 360 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 361   do {                                                                        \
 362     assert(!Heap_lock->owned_by_self() &&                                     \
 363                                     !SafepointSynchronize::is_at_safepoint(), \
 364       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 365                                    "should not be at a safepoint"));          \
 366   } while (0)
 367 
 368 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 369   do {                                                                        \
 370     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 371               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 372            heap_locking_asserts_params("should be at a safepoint"));          \
 373   } while (0)
 374 
 375 #define assert_not_at_safepoint()                                             \
 376   do {                                                                        \
 377     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 378            heap_locking_asserts_params("should not be at a safepoint"));      \
 379   } while (0)
 380 
 381 protected:
 382 
 383   // The young region list.
 384   G1EdenRegions _eden;
 385   G1SurvivorRegions _survivor;
 386 
 387   STWGCTimer* _gc_timer_stw;
 388 
 389   G1NewTracer* _gc_tracer_stw;
 390 
 391   // The current policy object for the collector.
 392   G1Policy* _g1_policy;
 393   G1HeapSizingPolicy* _heap_sizing_policy;
 394 
 395   G1CollectionSet _collection_set;
 396 
 397   // This is the second level of trying to allocate a new region. If
 398   // new_region() didn't find a region on the free_list, this call will
 399   // check whether there's anything available on the
 400   // secondary_free_list and/or wait for more regions to appear on
 401   // that list, if _free_regions_coming is set.
 402   HeapRegion* new_region_try_secondary_free_list(bool is_old);
 403 
 404   // Try to allocate a single non-humongous HeapRegion sufficient for
 405   // an allocation of the given word_size. If do_expand is true,
 406   // attempt to expand the heap if necessary to satisfy the allocation
 407   // request. If the region is to be used as an old region or for a
 408   // humongous object, set is_old to true. If not, to false.
 409   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 410 
 411   // Initialize a contiguous set of free regions of length num_regions
 412   // and starting at index first so that they appear as a single
 413   // humongous region.
 414   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 415                                                       uint num_regions,
 416                                                       size_t word_size,
 417                                                       AllocationContext_t context);
 418 
 419   // Attempt to allocate a humongous object of the given size. Return
 420   // NULL if unsuccessful.
 421   HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
 422 
 423   // The following two methods, allocate_new_tlab() and
 424   // mem_allocate(), are the two main entry points from the runtime
 425   // into the G1's allocation routines. They have the following
 426   // assumptions:
 427   //
 428   // * They should both be called outside safepoints.
 429   //
 430   // * They should both be called without holding the Heap_lock.
 431   //
 432   // * All allocation requests for new TLABs should go to
 433   //   allocate_new_tlab().
 434   //
 435   // * All non-TLAB allocation requests should go to mem_allocate().
 436   //
 437   // * If either call cannot satisfy the allocation request using the
 438   //   current allocating region, they will try to get a new one. If
 439   //   this fails, they will attempt to do an evacuation pause and
 440   //   retry the allocation.
 441   //
 442   // * If all allocation attempts fail, even after trying to schedule
 443   //   an evacuation pause, allocate_new_tlab() will return NULL,
 444   //   whereas mem_allocate() will attempt a heap expansion and/or
 445   //   schedule a Full GC.
 446   //
 447   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 448   //   should never be called with word_size being humongous. All
 449   //   humongous allocation requests should go to mem_allocate() which
 450   //   will satisfy them with a special path.
 451 
 452   virtual HeapWord* allocate_new_tlab(size_t word_size);
 453 
 454   virtual HeapWord* mem_allocate(size_t word_size,
 455                                  bool*  gc_overhead_limit_was_exceeded);
 456 
 457   // First-level mutator allocation attempt: try to allocate out of
 458   // the mutator alloc region without taking the Heap_lock. This
 459   // should only be used for non-humongous allocations.
 460   inline HeapWord* attempt_allocation(size_t word_size);
 461 
 462   // Second-level mutator allocation attempt: take the Heap_lock and
 463   // retry the allocation attempt, potentially scheduling a GC
 464   // pause. This should only be used for non-humongous allocations.
 465   HeapWord* attempt_allocation_slow(size_t word_size,
 466                                     AllocationContext_t context);
 467 
 468   // Takes the Heap_lock and attempts a humongous allocation. It can
 469   // potentially schedule a GC pause.
 470   HeapWord* attempt_allocation_humongous(size_t word_size);
 471 
 472   // Allocation attempt that should be called during safepoints (e.g.,
 473   // at the end of a successful GC). expect_null_mutator_alloc_region
 474   // specifies whether the mutator alloc region is expected to be NULL
 475   // or not.
 476   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 477                                             AllocationContext_t context,
 478                                             bool expect_null_mutator_alloc_region);
 479 
 480   // These methods are the "callbacks" from the G1AllocRegion class.
 481 
 482   // For mutator alloc regions.
 483   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 484   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 485                                    size_t allocated_bytes);
 486 
 487   // For GC alloc regions.
 488   bool has_more_regions(InCSetState dest);
 489   HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
 490   void retire_gc_alloc_region(HeapRegion* alloc_region,
 491                               size_t allocated_bytes, InCSetState dest);
 492 
 493   // - if explicit_gc is true, the GC is for a System.gc() etc,
 494   //   otherwise it's for a failed allocation.
 495   // - if clear_all_soft_refs is true, all soft references should be
 496   //   cleared during the GC.
 497   // - it returns false if it is unable to do the collection due to the
 498   //   GC locker being active, true otherwise.
 499   bool do_full_collection(bool explicit_gc,
 500                           bool clear_all_soft_refs);
 501 
 502   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 503   virtual void do_full_collection(bool clear_all_soft_refs);
 504 
 505   // Resize the heap if necessary after a full collection.
 506   void resize_if_necessary_after_full_collection();
 507 
 508   // Callback from VM_G1CollectForAllocation operation.
 509   // This function does everything necessary/possible to satisfy a
 510   // failed allocation request (including collection, expansion, etc.)
 511   HeapWord* satisfy_failed_allocation(size_t word_size,
 512                                       AllocationContext_t context,
 513                                       bool* succeeded);
 514 private:
 515   // Internal helpers used during full GC to split it up to
 516   // increase readability.
 517   void abort_concurrent_cycle();
 518   void verify_before_full_collection(bool explicit_gc);
 519   void prepare_heap_for_full_collection();
 520   void prepare_heap_for_mutators();
 521   void abort_refinement();
 522   void verify_after_full_collection();
 523   void print_heap_after_full_collection(G1HeapTransition* heap_transition);
 524 
 525   // Helper method for satisfy_failed_allocation()
 526   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 527                                              AllocationContext_t context,
 528                                              bool do_gc,
 529                                              bool clear_all_soft_refs,
 530                                              bool expect_null_mutator_alloc_region,
 531                                              bool* gc_succeeded);
 532 
 533 protected:
 534   // Attempting to expand the heap sufficiently
 535   // to support an allocation of the given "word_size".  If
 536   // successful, perform the allocation and return the address of the
 537   // allocated block, or else "NULL".
 538   HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
 539 
 540   // Preserve any referents discovered by concurrent marking that have not yet been
 541   // copied by the STW pause.
 542   void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
 543   // Process any reference objects discovered during
 544   // an incremental evacuation pause.
 545   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 546 
 547   // Enqueue any remaining discovered references
 548   // after processing.
 549   void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 550 
 551   // Merges the information gathered on a per-thread basis for all worker threads
 552   // during GC into global variables.
 553   void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
 554 public:
 555   G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
 556 
 557   WorkGang* workers() const { return _workers; }
 558 
 559   G1Allocator* allocator() {
 560     return _allocator;
 561   }
 562 
 563   G1HeapVerifier* verifier() {
 564     return _verifier;
 565   }
 566 
 567   G1MonitoringSupport* g1mm() {
 568     assert(_g1mm != NULL, "should have been initialized");
 569     return _g1mm;
 570   }
 571 
 572   // Expand the garbage-first heap by at least the given size (in bytes!).
 573   // Returns true if the heap was expanded by the requested amount;
 574   // false otherwise.
 575   // (Rounds up to a HeapRegion boundary.)
 576   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 577 
 578   // Returns the PLAB statistics for a given destination.
 579   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 580 
 581   // Determines PLAB size for a given destination.
 582   inline size_t desired_plab_sz(InCSetState dest);
 583 
 584   // Do anything common to GC's.
 585   void gc_prologue(bool full);
 586   void gc_epilogue(bool full);
 587 
 588   // Modify the reclaim candidate set and test for presence.
 589   // These are only valid for starts_humongous regions.
 590   inline void set_humongous_reclaim_candidate(uint region, bool value);
 591   inline bool is_humongous_reclaim_candidate(uint region);
 592 
 593   // Remove from the reclaim candidate set.  Also remove from the
 594   // collection set so that later encounters avoid the slow path.
 595   inline void set_humongous_is_live(oop obj);
 596 
 597   // Register the given region to be part of the collection set.
 598   inline void register_humongous_region_with_cset(uint index);
 599   // Register regions with humongous objects (actually on the start region) in
 600   // the in_cset_fast_test table.
 601   void register_humongous_regions_with_cset();
 602   // We register a region with the fast "in collection set" test. We
 603   // simply set to true the array slot corresponding to this region.
 604   void register_young_region_with_cset(HeapRegion* r) {
 605     _in_cset_fast_test.set_in_young(r->hrm_index());
 606   }
 607   void register_old_region_with_cset(HeapRegion* r) {
 608     _in_cset_fast_test.set_in_old(r->hrm_index());
 609   }
 610   inline void register_ext_region_with_cset(HeapRegion* r) {
 611     _in_cset_fast_test.set_ext(r->hrm_index());
 612   }
 613   void clear_in_cset(const HeapRegion* hr) {
 614     _in_cset_fast_test.clear(hr);
 615   }
 616 
 617   void clear_cset_fast_test() {
 618     _in_cset_fast_test.clear();
 619   }
 620 
 621   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 622 
 623   // This is called at the start of either a concurrent cycle or a Full
 624   // GC to update the number of old marking cycles started.
 625   void increment_old_marking_cycles_started();
 626 
 627   // This is called at the end of either a concurrent cycle or a Full
 628   // GC to update the number of old marking cycles completed. Those two
 629   // can happen in a nested fashion, i.e., we start a concurrent
 630   // cycle, a Full GC happens half-way through it which ends first,
 631   // and then the cycle notices that a Full GC happened and ends
 632   // too. The concurrent parameter is a boolean to help us do a bit
 633   // tighter consistency checking in the method. If concurrent is
 634   // false, the caller is the inner caller in the nesting (i.e., the
 635   // Full GC). If concurrent is true, the caller is the outer caller
 636   // in this nesting (i.e., the concurrent cycle). Further nesting is
 637   // not currently supported. The end of this call also notifies
 638   // the FullGCCount_lock in case a Java thread is waiting for a full
 639   // GC to happen (e.g., it called System.gc() with
 640   // +ExplicitGCInvokesConcurrent).
 641   void increment_old_marking_cycles_completed(bool concurrent);
 642 
 643   uint old_marking_cycles_completed() {
 644     return _old_marking_cycles_completed;
 645   }
 646 
 647   G1HRPrinter* hr_printer() { return &_hr_printer; }
 648 
 649   // Allocates a new heap region instance.
 650   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 651 
 652   // Allocate the highest free region in the reserved heap. This will commit
 653   // regions as necessary.
 654   HeapRegion* alloc_highest_free_region();
 655 
 656   // Frees a non-humongous region by initializing its contents and
 657   // adding it to the free list that's passed as a parameter (this is
 658   // usually a local list which will be appended to the master free
 659   // list later). The used bytes of freed regions are accumulated in
 660   // pre_used. If skip_remset is true, the region's RSet will not be freed
 661   // up. If skip_hot_card_cache is true, the region's hot card cache will not
 662   // be freed up. The assumption is that this will be done later.
 663   // The locked parameter indicates if the caller has already taken
 664   // care of proper synchronization. This may allow some optimizations.
 665   void free_region(HeapRegion* hr,
 666                    FreeRegionList* free_list,
 667                    bool skip_remset,
 668                    bool skip_hot_card_cache = false,
 669                    bool locked = false);
 670 
 671   // It dirties the cards that cover the block so that the post
 672   // write barrier never queues anything when updating objects on this
 673   // block. It is assumed (and in fact we assert) that the block
 674   // belongs to a young region.
 675   inline void dirty_young_block(HeapWord* start, size_t word_size);
 676 
 677   // Frees a humongous region by collapsing it into individual regions
 678   // and calling free_region() for each of them. The freed regions
 679   // will be added to the free list that's passed as a parameter (this
 680   // is usually a local list which will be appended to the master free
 681   // list later). The used bytes of freed regions are accumulated in
 682   // pre_used. If skip_remset is true, the region's RSet will not be freed
 683   // up. The assumption is that this will be done later.
 684   void free_humongous_region(HeapRegion* hr,
 685                              FreeRegionList* free_list,
 686                              bool skip_remset);
 687 
 688   // Facility for allocating in 'archive' regions in high heap memory and
 689   // recording the allocated ranges. These should all be called from the
 690   // VM thread at safepoints, without the heap lock held. They can be used
 691   // to create and archive a set of heap regions which can be mapped at the
 692   // same fixed addresses in a subsequent JVM invocation.
 693   void begin_archive_alloc_range(bool open = false);
 694 
 695   // Check if the requested size would be too large for an archive allocation.
 696   bool is_archive_alloc_too_large(size_t word_size);
 697 
 698   // Allocate memory of the requested size from the archive region. This will
 699   // return NULL if the size is too large or if no memory is available. It
 700   // does not trigger a garbage collection.
 701   HeapWord* archive_mem_allocate(size_t word_size);
 702 
 703   // Optionally aligns the end address and returns the allocated ranges in
 704   // an array of MemRegions in order of ascending addresses.
 705   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 706                                size_t end_alignment_in_bytes = 0);
 707 
 708   // Facility for allocating a fixed range within the heap and marking
 709   // the containing regions as 'archive'. For use at JVM init time, when the
 710   // caller may mmap archived heap data at the specified range(s).
 711   // Verify that the MemRegions specified in the argument array are within the
 712   // reserved heap.
 713   bool check_archive_addresses(MemRegion* range, size_t count);
 714 
 715   // Commit the appropriate G1 regions containing the specified MemRegions
 716   // and mark them as 'archive' regions. The regions in the array must be
 717   // non-overlapping and in order of ascending address.
 718   bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
 719 
 720   // Insert any required filler objects in the G1 regions around the specified
 721   // ranges to make the regions parseable. This must be called after
 722   // alloc_archive_regions, and after class loading has occurred.
 723   void fill_archive_regions(MemRegion* range, size_t count);
 724 
 725   // For each of the specified MemRegions, uncommit the containing G1 regions
 726   // which had been allocated by alloc_archive_regions. This should be called
 727   // rather than fill_archive_regions at JVM init time if the archive file
 728   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 729   void dealloc_archive_regions(MemRegion* range, size_t count);
 730 
 731 protected:
 732 
 733   // Shrink the garbage-first heap by at most the given size (in bytes!).
 734   // (Rounds down to a HeapRegion boundary.)
 735   virtual void shrink(size_t expand_bytes);
 736   void shrink_helper(size_t expand_bytes);
 737 
 738   #if TASKQUEUE_STATS
 739   static void print_taskqueue_stats_hdr(outputStream* const st);
 740   void print_taskqueue_stats() const;
 741   void reset_taskqueue_stats();
 742   #endif // TASKQUEUE_STATS
 743 
 744   // Schedule the VM operation that will do an evacuation pause to
 745   // satisfy an allocation request of word_size. *succeeded will
 746   // return whether the VM operation was successful (it did do an
 747   // evacuation pause) or not (another thread beat us to it or the GC
 748   // locker was active). Given that we should not be holding the
 749   // Heap_lock when we enter this method, we will pass the
 750   // gc_count_before (i.e., total_collections()) as a parameter since
 751   // it has to be read while holding the Heap_lock. Currently, both
 752   // methods that call do_collection_pause() release the Heap_lock
 753   // before the call, so it's easy to read gc_count_before just before.
 754   HeapWord* do_collection_pause(size_t         word_size,
 755                                 uint           gc_count_before,
 756                                 bool*          succeeded,
 757                                 GCCause::Cause gc_cause);
 758 
 759   void wait_for_root_region_scanning();
 760 
 761   // The guts of the incremental collection pause, executed by the vm
 762   // thread. It returns false if it is unable to do the collection due
 763   // to the GC locker being active, true otherwise
 764   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 765 
 766   // Actually do the work of evacuating the collection set.
 767   virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
 768 
 769   void pre_evacuate_collection_set();
 770   void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 771 
 772   // Print the header for the per-thread termination statistics.
 773   static void print_termination_stats_hdr();
 774   // Print actual per-thread termination statistics.
 775   void print_termination_stats(uint worker_id,
 776                                double elapsed_ms,
 777                                double strong_roots_ms,
 778                                double term_ms,
 779                                size_t term_attempts,
 780                                size_t alloc_buffer_waste,
 781                                size_t undo_waste) const;
 782   // Update object copying statistics.
 783   void record_obj_copy_mem_stats();
 784 
 785   // The hot card cache for remembered set insertion optimization.
 786   G1HotCardCache* _hot_card_cache;
 787 
 788   // The g1 remembered set of the heap.
 789   G1RemSet* _g1_rem_set;
 790 
 791   // A set of cards that cover the objects for which the Rsets should be updated
 792   // concurrently after the collection.
 793   DirtyCardQueueSet _dirty_card_queue_set;
 794 
 795   // After a collection pause, convert the regions in the collection set into free
 796   // regions.
 797   void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 798 
 799   // Abandon the current collection set without recording policy
 800   // statistics or updating free lists.
 801   void abandon_collection_set(G1CollectionSet* collection_set);
 802 
 803   // The concurrent marker (and the thread it runs in.)
 804   G1ConcurrentMark* _cm;
 805   ConcurrentMarkThread* _cmThread;
 806 
 807   // The concurrent refiner.
 808   G1ConcurrentRefine* _cr;
 809 
 810   // The parallel task queues
 811   RefToScanQueueSet *_task_queues;
 812 
 813   // True iff a evacuation has failed in the current collection.
 814   bool _evacuation_failed;
 815 
 816   EvacuationFailedInfo* _evacuation_failed_info_array;
 817 
 818   // Failed evacuations cause some logical from-space objects to have
 819   // forwarding pointers to themselves.  Reset them.
 820   void remove_self_forwarding_pointers();
 821 
 822   // Restore the objects in the regions in the collection set after an
 823   // evacuation failure.
 824   void restore_after_evac_failure();
 825 
 826   PreservedMarksSet _preserved_marks_set;
 827 
 828   // Preserve the mark of "obj", if necessary, in preparation for its mark
 829   // word being overwritten with a self-forwarding-pointer.
 830   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 831 
 832 #ifndef PRODUCT
 833   // Support for forcing evacuation failures. Analogous to
 834   // PromotionFailureALot for the other collectors.
 835 
 836   // Records whether G1EvacuationFailureALot should be in effect
 837   // for the current GC
 838   bool _evacuation_failure_alot_for_current_gc;
 839 
 840   // Used to record the GC number for interval checking when
 841   // determining whether G1EvaucationFailureALot is in effect
 842   // for the current GC.
 843   size_t _evacuation_failure_alot_gc_number;
 844 
 845   // Count of the number of evacuations between failures.
 846   volatile size_t _evacuation_failure_alot_count;
 847 
 848   // Set whether G1EvacuationFailureALot should be in effect
 849   // for the current GC (based upon the type of GC and which
 850   // command line flags are set);
 851   inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
 852                                                   bool during_initial_mark,
 853                                                   bool during_marking);
 854 
 855   inline void set_evacuation_failure_alot_for_current_gc();
 856 
 857   // Return true if it's time to cause an evacuation failure.
 858   inline bool evacuation_should_fail();
 859 
 860   // Reset the G1EvacuationFailureALot counters.  Should be called at
 861   // the end of an evacuation pause in which an evacuation failure occurred.
 862   inline void reset_evacuation_should_fail();
 863 #endif // !PRODUCT
 864 
 865   // ("Weak") Reference processing support.
 866   //
 867   // G1 has 2 instances of the reference processor class. One
 868   // (_ref_processor_cm) handles reference object discovery
 869   // and subsequent processing during concurrent marking cycles.
 870   //
 871   // The other (_ref_processor_stw) handles reference object
 872   // discovery and processing during full GCs and incremental
 873   // evacuation pauses.
 874   //
 875   // During an incremental pause, reference discovery will be
 876   // temporarily disabled for _ref_processor_cm and will be
 877   // enabled for _ref_processor_stw. At the end of the evacuation
 878   // pause references discovered by _ref_processor_stw will be
 879   // processed and discovery will be disabled. The previous
 880   // setting for reference object discovery for _ref_processor_cm
 881   // will be re-instated.
 882   //
 883   // At the start of marking:
 884   //  * Discovery by the CM ref processor is verified to be inactive
 885   //    and it's discovered lists are empty.
 886   //  * Discovery by the CM ref processor is then enabled.
 887   //
 888   // At the end of marking:
 889   //  * Any references on the CM ref processor's discovered
 890   //    lists are processed (possibly MT).
 891   //
 892   // At the start of full GC we:
 893   //  * Disable discovery by the CM ref processor and
 894   //    empty CM ref processor's discovered lists
 895   //    (without processing any entries).
 896   //  * Verify that the STW ref processor is inactive and it's
 897   //    discovered lists are empty.
 898   //  * Temporarily set STW ref processor discovery as single threaded.
 899   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 900   //    field.
 901   //  * Finally enable discovery by the STW ref processor.
 902   //
 903   // The STW ref processor is used to record any discovered
 904   // references during the full GC.
 905   //
 906   // At the end of a full GC we:
 907   //  * Enqueue any reference objects discovered by the STW ref processor
 908   //    that have non-live referents. This has the side-effect of
 909   //    making the STW ref processor inactive by disabling discovery.
 910   //  * Verify that the CM ref processor is still inactive
 911   //    and no references have been placed on it's discovered
 912   //    lists (also checked as a precondition during initial marking).
 913 
 914   // The (stw) reference processor...
 915   ReferenceProcessor* _ref_processor_stw;
 916 
 917   // During reference object discovery, the _is_alive_non_header
 918   // closure (if non-null) is applied to the referent object to
 919   // determine whether the referent is live. If so then the
 920   // reference object does not need to be 'discovered' and can
 921   // be treated as a regular oop. This has the benefit of reducing
 922   // the number of 'discovered' reference objects that need to
 923   // be processed.
 924   //
 925   // Instance of the is_alive closure for embedding into the
 926   // STW reference processor as the _is_alive_non_header field.
 927   // Supplying a value for the _is_alive_non_header field is
 928   // optional but doing so prevents unnecessary additions to
 929   // the discovered lists during reference discovery.
 930   G1STWIsAliveClosure _is_alive_closure_stw;
 931 
 932   // The (concurrent marking) reference processor...
 933   ReferenceProcessor* _ref_processor_cm;
 934 
 935   // Instance of the concurrent mark is_alive closure for embedding
 936   // into the Concurrent Marking reference processor as the
 937   // _is_alive_non_header field. Supplying a value for the
 938   // _is_alive_non_header field is optional but doing so prevents
 939   // unnecessary additions to the discovered lists during reference
 940   // discovery.
 941   G1CMIsAliveClosure _is_alive_closure_cm;
 942 
 943   volatile bool _free_regions_coming;
 944 
 945 public:
 946 
 947   RefToScanQueue *task_queue(uint i) const;
 948 
 949   uint num_task_queues() const;
 950 
 951   // A set of cards where updates happened during the GC
 952   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 953 
 954   // Create a G1CollectedHeap with the specified policy.
 955   // Must call the initialize method afterwards.
 956   // May not return if something goes wrong.
 957   G1CollectedHeap(G1CollectorPolicy* policy);
 958 
 959 private:
 960   jint initialize_concurrent_refinement();
 961   jint initialize_young_gen_sampling_thread();
 962 public:
 963   // Initialize the G1CollectedHeap to have the initial and
 964   // maximum sizes and remembered and barrier sets
 965   // specified by the policy object.
 966   jint initialize();
 967 
 968   virtual void stop();
 969   virtual void safepoint_synchronize_begin();
 970   virtual void safepoint_synchronize_end();
 971 
 972   // Return the (conservative) maximum heap alignment for any G1 heap
 973   static size_t conservative_max_heap_alignment();
 974 
 975   // Does operations required after initialization has been done.
 976   void post_initialize();
 977 
 978   // Initialize weak reference processing.
 979   void ref_processing_init();
 980 
 981   virtual Name kind() const {
 982     return CollectedHeap::G1CollectedHeap;
 983   }
 984 
 985   virtual const char* name() const {
 986     return "G1";
 987   }
 988 
 989   const G1CollectorState* collector_state() const { return &_collector_state; }
 990   G1CollectorState* collector_state() { return &_collector_state; }
 991 
 992   // The current policy object for the collector.
 993   G1Policy* g1_policy() const { return _g1_policy; }
 994 
 995   const G1CollectionSet* collection_set() const { return &_collection_set; }
 996   G1CollectionSet* collection_set() { return &_collection_set; }
 997 
 998   virtual CollectorPolicy* collector_policy() const;
 999 
1000   virtual SoftRefPolicy* soft_ref_policy();
1001 
1002   virtual GrowableArray<GCMemoryManager*> memory_managers();
1003   virtual GrowableArray<MemoryPool*> memory_pools();
1004 
1005   // The rem set and barrier set.
1006   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1007 
1008   // Try to minimize the remembered set.
1009   void scrub_rem_set();
1010 
1011   uint get_gc_time_stamp() {
1012     return _gc_time_stamp;
1013   }
1014 
1015   inline void reset_gc_time_stamp();
1016 
1017   void check_gc_time_stamps() PRODUCT_RETURN;
1018 
1019   inline void increment_gc_time_stamp();
1020 
1021   // Reset the given region's GC timestamp. If it's starts humongous,
1022   // also reset the GC timestamp of its corresponding
1023   // continues humongous regions too.
1024   void reset_gc_time_stamps(HeapRegion* hr);
1025 
1026   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1027   void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1028 
1029   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1030   void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1031 
1032   // The shared block offset table array.
1033   G1BlockOffsetTable* bot() const { return _bot; }
1034 
1035   // Reference Processing accessors
1036 
1037   // The STW reference processor....
1038   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1039 
1040   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1041 
1042   // The Concurrent Marking reference processor...
1043   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1044 
1045   size_t unused_committed_regions_in_bytes() const;
1046   virtual size_t capacity() const;
1047   virtual size_t used() const;
1048   // This should be called when we're not holding the heap lock. The
1049   // result might be a bit inaccurate.
1050   size_t used_unlocked() const;
1051   size_t recalculate_used() const;
1052 
1053   // These virtual functions do the actual allocation.
1054   // Some heaps may offer a contiguous region for shared non-blocking
1055   // allocation, via inlined code (by exporting the address of the top and
1056   // end fields defining the extent of the contiguous allocation region.)
1057   // But G1CollectedHeap doesn't yet support this.
1058 
1059   virtual bool is_maximal_no_gc() const {
1060     return _hrm.available() == 0;
1061   }
1062 
1063   // Returns whether there are any regions left in the heap for allocation.
1064   bool has_regions_left_for_allocation() const {
1065     return !is_maximal_no_gc() || num_free_regions() != 0;
1066   }
1067 
1068   // The current number of regions in the heap.
1069   uint num_regions() const { return _hrm.length(); }
1070 
1071   // The max number of regions in the heap.
1072   uint max_regions() const { return _hrm.max_length(); }
1073 
1074   // The number of regions that are completely free.
1075   uint num_free_regions() const { return _hrm.num_free_regions(); }
1076 
1077   MemoryUsage get_auxiliary_data_memory_usage() const {
1078     return _hrm.get_auxiliary_data_memory_usage();
1079   }
1080 
1081   // The number of regions that are not completely free.
1082   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1083 
1084 #ifdef ASSERT
1085   bool is_on_master_free_list(HeapRegion* hr) {
1086     return _hrm.is_free(hr);
1087   }
1088 #endif // ASSERT
1089 
1090   // Wrapper for the region list operations that can be called from
1091   // methods outside this class.
1092 
1093   void secondary_free_list_add(FreeRegionList* list) {
1094     _secondary_free_list.add_ordered(list);
1095   }
1096 
1097   void append_secondary_free_list() {
1098     _hrm.insert_list_into_free_list(&_secondary_free_list);
1099   }
1100 
1101   void append_secondary_free_list_if_not_empty_with_lock() {
1102     // If the secondary free list looks empty there's no reason to
1103     // take the lock and then try to append it.
1104     if (!_secondary_free_list.is_empty()) {
1105       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1106       append_secondary_free_list();
1107     }
1108   }
1109 
1110   inline void old_set_add(HeapRegion* hr);
1111   inline void old_set_remove(HeapRegion* hr);
1112 
1113   size_t non_young_capacity_bytes() {
1114     return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1115   }
1116 
1117   void set_free_regions_coming();
1118   void reset_free_regions_coming();
1119   bool free_regions_coming() { return _free_regions_coming; }
1120   void wait_while_free_regions_coming();
1121 
1122   // Determine whether the given region is one that we are using as an
1123   // old GC alloc region.
1124   bool is_old_gc_alloc_region(HeapRegion* hr);
1125 
1126   // Perform a collection of the heap; intended for use in implementing
1127   // "System.gc".  This probably implies as full a collection as the
1128   // "CollectedHeap" supports.
1129   virtual void collect(GCCause::Cause cause);
1130 
1131   // True iff an evacuation has failed in the most-recent collection.
1132   bool evacuation_failed() { return _evacuation_failed; }
1133 
1134   void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1135   void prepend_to_freelist(FreeRegionList* list);
1136   void decrement_summary_bytes(size_t bytes);
1137 
1138   virtual bool is_in(const void* p) const;
1139 #ifdef ASSERT
1140   // Returns whether p is in one of the available areas of the heap. Slow but
1141   // extensive version.
1142   bool is_in_exact(const void* p) const;
1143 #endif
1144 
1145   // Return "TRUE" iff the given object address is within the collection
1146   // set. Assumes that the reference points into the heap.
1147   inline bool is_in_cset(const HeapRegion *hr);
1148   inline bool is_in_cset(oop obj);
1149   inline bool is_in_cset(HeapWord* addr);
1150 
1151   inline bool is_in_cset_or_humongous(const oop obj);
1152 
1153  private:
1154   // This array is used for a quick test on whether a reference points into
1155   // the collection set or not. Each of the array's elements denotes whether the
1156   // corresponding region is in the collection set or not.
1157   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1158 
1159  public:
1160 
1161   inline InCSetState in_cset_state(const oop obj);
1162 
1163   // Return "TRUE" iff the given object address is in the reserved
1164   // region of g1.
1165   bool is_in_g1_reserved(const void* p) const {
1166     return _hrm.reserved().contains(p);
1167   }
1168 
1169   // Returns a MemRegion that corresponds to the space that has been
1170   // reserved for the heap
1171   MemRegion g1_reserved() const {
1172     return _hrm.reserved();
1173   }
1174 
1175   virtual bool is_in_closed_subset(const void* p) const;
1176 
1177   G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1178     return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1179   }
1180 
1181   G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1182 
1183   G1CardTable* card_table() const {
1184     return _card_table;
1185   }
1186 
1187   // Iteration functions.
1188 
1189   // Iterate over all objects, calling "cl.do_object" on each.
1190   virtual void object_iterate(ObjectClosure* cl);
1191 
1192   virtual void safe_object_iterate(ObjectClosure* cl) {
1193     object_iterate(cl);
1194   }
1195 
1196   // Iterate over heap regions, in address order, terminating the
1197   // iteration early if the "do_heap_region" method returns "true".
1198   void heap_region_iterate(HeapRegionClosure* blk) const;
1199 
1200   // Return the region with the given index. It assumes the index is valid.
1201   inline HeapRegion* region_at(uint index) const;
1202 
1203   // Return the next region (by index) that is part of the same
1204   // humongous object that hr is part of.
1205   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1206 
1207   // Calculate the region index of the given address. Given address must be
1208   // within the heap.
1209   inline uint addr_to_region(HeapWord* addr) const;
1210 
1211   inline HeapWord* bottom_addr_for_region(uint index) const;
1212 
1213   // Two functions to iterate over the heap regions in parallel. Threads
1214   // compete using the HeapRegionClaimer to claim the regions before
1215   // applying the closure on them.
1216   // The _from_worker_offset version uses the HeapRegionClaimer and
1217   // the worker id to calculate a start offset to prevent all workers to
1218   // start from the point.
1219   void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1220                                                   HeapRegionClaimer* hrclaimer,
1221                                                   uint worker_id) const;
1222 
1223   void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1224                                           HeapRegionClaimer* hrclaimer) const;
1225 
1226   // Iterate over the regions (if any) in the current collection set.
1227   void collection_set_iterate(HeapRegionClosure* blk);
1228 
1229   // Iterate over the regions (if any) in the current collection set. Starts the
1230   // iteration over the entire collection set so that the start regions of a given
1231   // worker id over the set active_workers are evenly spread across the set of
1232   // collection set regions.
1233   void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1234 
1235   // Returns the HeapRegion that contains addr. addr must not be NULL.
1236   template <class T>
1237   inline HeapRegion* heap_region_containing(const T addr) const;
1238 
1239   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1240   // each address in the (reserved) heap is a member of exactly
1241   // one block.  The defining characteristic of a block is that it is
1242   // possible to find its size, and thus to progress forward to the next
1243   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1244   // represent Java objects, or they might be free blocks in a
1245   // free-list-based heap (or subheap), as long as the two kinds are
1246   // distinguishable and the size of each is determinable.
1247 
1248   // Returns the address of the start of the "block" that contains the
1249   // address "addr".  We say "blocks" instead of "object" since some heaps
1250   // may not pack objects densely; a chunk may either be an object or a
1251   // non-object.
1252   virtual HeapWord* block_start(const void* addr) const;
1253 
1254   // Requires "addr" to be the start of a chunk, and returns its size.
1255   // "addr + size" is required to be the start of a new chunk, or the end
1256   // of the active area of the heap.
1257   virtual size_t block_size(const HeapWord* addr) const;
1258 
1259   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1260   // the block is an object.
1261   virtual bool block_is_obj(const HeapWord* addr) const;
1262 
1263   // Section on thread-local allocation buffers (TLABs)
1264   // See CollectedHeap for semantics.
1265 
1266   bool supports_tlab_allocation() const;
1267   size_t tlab_capacity(Thread* ignored) const;
1268   size_t tlab_used(Thread* ignored) const;
1269   size_t max_tlab_size() const;
1270   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1271 
1272   inline bool is_in_young(const oop obj);
1273 
1274   // Returns "true" iff the given word_size is "very large".
1275   static bool is_humongous(size_t word_size) {
1276     // Note this has to be strictly greater-than as the TLABs
1277     // are capped at the humongous threshold and we want to
1278     // ensure that we don't try to allocate a TLAB as
1279     // humongous and that we don't allocate a humongous
1280     // object in a TLAB.
1281     return word_size > _humongous_object_threshold_in_words;
1282   }
1283 
1284   // Returns the humongous threshold for a specific region size
1285   static size_t humongous_threshold_for(size_t region_size) {
1286     return (region_size / 2);
1287   }
1288 
1289   // Returns the number of regions the humongous object of the given word size
1290   // requires.
1291   static size_t humongous_obj_size_in_regions(size_t word_size);
1292 
1293   // Print the maximum heap capacity.
1294   virtual size_t max_capacity() const;
1295 
1296   virtual jlong millis_since_last_gc();
1297 
1298 
1299   // Convenience function to be used in situations where the heap type can be
1300   // asserted to be this type.
1301   static G1CollectedHeap* heap();
1302 
1303   void set_region_short_lived_locked(HeapRegion* hr);
1304   // add appropriate methods for any other surv rate groups
1305 
1306   const G1SurvivorRegions* survivor() const { return &_survivor; }
1307 
1308   uint survivor_regions_count() const {
1309     return _survivor.length();
1310   }
1311 
1312   uint eden_regions_count() const {
1313     return _eden.length();
1314   }
1315 
1316   uint young_regions_count() const {
1317     return _eden.length() + _survivor.length();
1318   }
1319 
1320   uint old_regions_count() const { return _old_set.length(); }
1321 
1322   uint humongous_regions_count() const { return _humongous_set.length(); }
1323 
1324 #ifdef ASSERT
1325   bool check_young_list_empty();
1326 #endif
1327 
1328   // *** Stuff related to concurrent marking.  It's not clear to me that so
1329   // many of these need to be public.
1330 
1331   // The functions below are helper functions that a subclass of
1332   // "CollectedHeap" can use in the implementation of its virtual
1333   // functions.
1334   // This performs a concurrent marking of the live objects in a
1335   // bitmap off to the side.
1336   void doConcurrentMark();
1337 
1338   bool isMarkedNext(oop obj) const;
1339 
1340   // Determine if an object is dead, given the object and also
1341   // the region to which the object belongs. An object is dead
1342   // iff a) it was not allocated since the last mark, b) it
1343   // is not marked, and c) it is not in an archive region.
1344   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1345     return
1346       hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1347       !hr->is_archive();
1348   }
1349 
1350   // This function returns true when an object has been
1351   // around since the previous marking and hasn't yet
1352   // been marked during this marking, and is not in an archive region.
1353   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1354     return
1355       !hr->obj_allocated_since_next_marking(obj) &&
1356       !isMarkedNext(obj) &&
1357       !hr->is_archive();
1358   }
1359 
1360   // Determine if an object is dead, given only the object itself.
1361   // This will find the region to which the object belongs and
1362   // then call the region version of the same function.
1363 
1364   // Added if it is NULL it isn't dead.
1365 
1366   inline bool is_obj_dead(const oop obj) const;
1367 
1368   inline bool is_obj_ill(const oop obj) const;
1369 
1370   inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1371   inline bool is_obj_dead_full(const oop obj) const;
1372 
1373   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1374 
1375   // Refinement
1376 
1377   G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1378 
1379   // Optimized nmethod scanning support routines
1380 
1381   // Is an oop scavengeable
1382   virtual bool is_scavengable(oop obj);
1383 
1384   // Register the given nmethod with the G1 heap.
1385   virtual void register_nmethod(nmethod* nm);
1386 
1387   // Unregister the given nmethod from the G1 heap.
1388   virtual void unregister_nmethod(nmethod* nm);
1389 
1390   // Free up superfluous code root memory.
1391   void purge_code_root_memory();
1392 
1393   // Rebuild the strong code root lists for each region
1394   // after a full GC.
1395   void rebuild_strong_code_roots();
1396 
1397   // Partial cleaning used when class unloading is disabled.
1398   // Let the caller choose what structures to clean out:
1399   // - StringTable
1400   // - SymbolTable
1401   // - StringDeduplication structures
1402   void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1403 
1404   // Complete cleaning used when class unloading is enabled.
1405   // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1406   void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1407 
1408   // Redirty logged cards in the refinement queue.
1409   void redirty_logged_cards();
1410   // Verification
1411 
1412   // Perform any cleanup actions necessary before allowing a verification.
1413   virtual void prepare_for_verify();
1414 
1415   // Perform verification.
1416 
1417   // vo == UsePrevMarking -> use "prev" marking information,
1418   // vo == UseNextMarking -> use "next" marking information
1419   // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1420   //
1421   // NOTE: Only the "prev" marking information is guaranteed to be
1422   // consistent most of the time, so most calls to this should use
1423   // vo == UsePrevMarking.
1424   // Currently, there is only one case where this is called with
1425   // vo == UseNextMarking, which is to verify the "next" marking
1426   // information at the end of remark.
1427   // Currently there is only one place where this is called with
1428   // vo == UseFullMarking, which is to verify the marking during a
1429   // full GC.
1430   void verify(VerifyOption vo);
1431 
1432   // WhiteBox testing support.
1433   virtual bool supports_concurrent_phase_control() const;
1434   virtual const char* const* concurrent_phases() const;
1435   virtual bool request_concurrent_phase(const char* phase);
1436 
1437   // The methods below are here for convenience and dispatch the
1438   // appropriate method depending on value of the given VerifyOption
1439   // parameter. The values for that parameter, and their meanings,
1440   // are the same as those above.
1441 
1442   bool is_obj_dead_cond(const oop obj,
1443                         const HeapRegion* hr,
1444                         const VerifyOption vo) const;
1445 
1446   bool is_obj_dead_cond(const oop obj,
1447                         const VerifyOption vo) const;
1448 
1449   G1HeapSummary create_g1_heap_summary();
1450   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1451 
1452   // Printing
1453 private:
1454   void print_heap_regions() const;
1455   void print_regions_on(outputStream* st) const;
1456 
1457 public:
1458   virtual void print_on(outputStream* st) const;
1459   virtual void print_extended_on(outputStream* st) const;
1460   virtual void print_on_error(outputStream* st) const;
1461 
1462   virtual void print_gc_threads_on(outputStream* st) const;
1463   virtual void gc_threads_do(ThreadClosure* tc) const;
1464 
1465   // Override
1466   void print_tracing_info() const;
1467 
1468   // The following two methods are helpful for debugging RSet issues.
1469   void print_cset_rsets() PRODUCT_RETURN;
1470   void print_all_rsets() PRODUCT_RETURN;
1471 
1472 public:
1473   size_t pending_card_num();
1474 
1475 protected:
1476   size_t _max_heap_capacity;
1477 };
1478 
1479 class G1ParEvacuateFollowersClosure : public VoidClosure {
1480 private:
1481   double _start_term;
1482   double _term_time;
1483   size_t _term_attempts;
1484 
1485   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1486   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1487 protected:
1488   G1CollectedHeap*              _g1h;
1489   G1ParScanThreadState*         _par_scan_state;
1490   RefToScanQueueSet*            _queues;
1491   ParallelTaskTerminator*       _terminator;
1492 
1493   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1494   RefToScanQueueSet*      queues()         { return _queues; }
1495   ParallelTaskTerminator* terminator()     { return _terminator; }
1496 
1497 public:
1498   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1499                                 G1ParScanThreadState* par_scan_state,
1500                                 RefToScanQueueSet* queues,
1501                                 ParallelTaskTerminator* terminator)
1502     : _g1h(g1h), _par_scan_state(par_scan_state),
1503       _queues(queues), _terminator(terminator),
1504       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1505 
1506   void do_void();
1507 
1508   double term_time() const { return _term_time; }
1509   size_t term_attempts() const { return _term_attempts; }
1510 
1511 private:
1512   inline bool offer_termination();
1513 };
1514 
1515 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP