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