1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
   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/g1HeapVerifier.hpp"
  38 #include "gc/g1/g1HRPrinter.hpp"
  39 #include "gc/g1/g1InCSetState.hpp"
  40 #include "gc/g1/g1MonitoringSupport.hpp"
  41 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
  42 #include "gc/g1/g1SurvivorRegions.hpp"
  43 #include "gc/g1/g1YCTypes.hpp"
  44 #include "gc/g1/hSpaceCounters.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/plab.hpp"
  50 #include "gc/shared/preservedMarks.hpp"
  51 #include "memory/memRegion.hpp"
  52 #include "utilities/stack.hpp"
  53 
  54 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  55 // It uses the "Garbage First" heap organization and algorithm, which
  56 // may combine concurrent marking with parallel, incremental compaction of
  57 // heap subsets that will yield large amounts of garbage.
  58 
  59 // Forward declarations
  60 class HeapRegion;
  61 class HRRSCleanupTask;
  62 class GenerationSpec;
  63 class OopsInHeapRegionClosure;
  64 class G1ParScanThreadState;
  65 class G1ParScanThreadStateSet;
  66 class G1KlassScanClosure;
  67 class G1ParScanThreadState;
  68 class ObjectClosure;
  69 class SpaceClosure;
  70 class CompactibleSpaceClosure;
  71 class Space;
  72 class G1CollectionSet;
  73 class G1CollectorPolicy;
  74 class G1Policy;
  75 class G1HotCardCache;
  76 class G1RemSet;
  77 class HeapRegionRemSetIterator;
  78 class G1ConcurrentMark;
  79 class ConcurrentMarkThread;
  80 class ConcurrentG1Refine;
  81 class GenerationCounters;
  82 class STWGCTimer;
  83 class G1NewTracer;
  84 class EvacuationFailedInfo;
  85 class nmethod;
  86 class Ticks;
  87 class WorkGang;
  88 class G1Allocator;
  89 class G1ArchiveAllocator;
  90 class G1FullGCScope;
  91 class G1HeapVerifier;
  92 class G1HeapSizingPolicy;
  93 
  94 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
  95 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
  96 
  97 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
  98 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
  99 
 100 // The G1 STW is alive closure.
 101 // An instance is embedded into the G1CH and used as the
 102 // (optional) _is_alive_non_header closure in the STW
 103 // reference processor. It is also extensively used during
 104 // reference processing during STW evacuation pauses.
 105 class G1STWIsAliveClosure: public BoolObjectClosure {
 106   G1CollectedHeap* _g1;
 107 public:
 108   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 109   bool do_object_b(oop p);
 110 };
 111 
 112 class RefineCardTableEntryClosure;
 113 
 114 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 115  private:
 116   void reset_from_card_cache(uint start_idx, size_t num_regions);
 117  public:
 118   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 119 };
 120 
 121 class G1CollectedHeap : public CollectedHeap {
 122   friend class G1FreeCollectionSetTask;
 123   friend class VM_CollectForMetadataAllocation;
 124   friend class VM_G1CollectForAllocation;
 125   friend class VM_G1CollectFull;
 126   friend class VM_G1IncCollectionPause;
 127   friend class VMStructs;
 128   friend class MutatorAllocRegion;
 129   friend class G1GCAllocRegion;
 130   friend class G1HeapVerifier;
 131 
 132   // Closures used in implementation.
 133   friend class G1ParScanThreadState;
 134   friend class G1ParScanThreadStateSet;
 135   friend class G1ParTask;
 136   friend class G1PLABAllocator;
 137   friend class G1PrepareCompactClosure;
 138 
 139   // Other related classes.
 140   friend class HeapRegionClaimer;
 141 
 142   // Testing classes.
 143   friend class G1CheckCSetFastTableClosure;
 144 
 145 private:
 146   WorkGang* _workers;
 147   G1CollectorPolicy* _collector_policy;
 148 
 149   static size_t _humongous_object_threshold_in_words;
 150 
 151   // The secondary free list which contains regions that have been
 152   // freed up during the cleanup process. This will be appended to
 153   // the master free list when appropriate.
 154   FreeRegionList _secondary_free_list;
 155 
 156   // It keeps track of the old regions.
 157   HeapRegionSet _old_set;
 158 
 159   // It keeps track of the humongous regions.
 160   HeapRegionSet _humongous_set;
 161 
 162   void eagerly_reclaim_humongous_regions();
 163   // Start a new incremental collection set for the next pause.
 164   void start_new_collection_set();
 165 
 166   // The number of regions we could create by expansion.
 167   uint _expansion_regions;
 168 
 169   // The block offset table for the G1 heap.
 170   G1BlockOffsetTable* _bot;
 171 
 172   // Tears down the region sets / lists so that they are empty and the
 173   // regions on the heap do not belong to a region set / list. The
 174   // only exception is the humongous set which we leave unaltered. If
 175   // free_list_only is true, it will only tear down the master free
 176   // list. It is called before a Full GC (free_list_only == false) or
 177   // before heap shrinking (free_list_only == true).
 178   void tear_down_region_sets(bool free_list_only);
 179 
 180   // Rebuilds the region sets / lists so that they are repopulated to
 181   // reflect the contents of the heap. The only exception is the
 182   // humongous set which was not torn down in the first place. If
 183   // free_list_only is true, it will only rebuild the master free
 184   // list. It is called after a Full GC (free_list_only == false) or
 185   // after heap shrinking (free_list_only == true).
 186   void rebuild_region_sets(bool free_list_only);
 187 
 188   // Callback for region mapping changed events.
 189   G1RegionMappingChangedListener _listener;
 190 
 191   // The sequence of all heap regions in the heap.
 192   HeapRegionManager _hrm;
 193 
 194   // Manages all allocations with regions except humongous object allocations.
 195   G1Allocator* _allocator;
 196 
 197   // Manages all heap verification.
 198   G1HeapVerifier* _verifier;
 199 
 200   // Outside of GC pauses, the number of bytes used in all regions other
 201   // than the current allocation region(s).
 202   size_t _summary_bytes_used;
 203 
 204   void increase_used(size_t bytes);
 205   void decrease_used(size_t bytes);
 206 
 207   void set_used(size_t bytes);
 208 
 209   // Class that handles archive allocation ranges.
 210   G1ArchiveAllocator* _archive_allocator;
 211 
 212   // Statistics for each allocation context
 213   AllocationContextStats _allocation_context_stats;
 214 
 215   // GC allocation statistics policy for survivors.
 216   G1EvacStats _survivor_evac_stats;
 217 
 218   // GC allocation statistics policy for tenured objects.
 219   G1EvacStats _old_evac_stats;
 220 
 221   // It specifies whether we should attempt to expand the heap after a
 222   // region allocation failure. If heap expansion fails we set this to
 223   // false so that we don't re-attempt the heap expansion (it's likely
 224   // that subsequent expansion attempts will also fail if one fails).
 225   // Currently, it is only consulted during GC and it's reset at the
 226   // start of each GC.
 227   bool _expand_heap_after_alloc_failure;
 228 
 229   // Helper for monitoring and management support.
 230   G1MonitoringSupport* _g1mm;
 231 
 232   // Records whether the region at the given index is (still) a
 233   // candidate for eager reclaim.  Only valid for humongous start
 234   // regions; other regions have unspecified values.  Humongous start
 235   // regions are initialized at start of collection pause, with
 236   // candidates removed from the set as they are found reachable from
 237   // roots or the young generation.
 238   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 239    protected:
 240     bool default_value() const { return false; }
 241    public:
 242     void clear() { G1BiasedMappedArray<bool>::clear(); }
 243     void set_candidate(uint region, bool value) {
 244       set_by_index(region, value);
 245     }
 246     bool is_candidate(uint region) {
 247       return get_by_index(region);
 248     }
 249   };
 250 
 251   HumongousReclaimCandidates _humongous_reclaim_candidates;
 252   // Stores whether during humongous object registration we found candidate regions.
 253   // If not, we can skip a few steps.
 254   bool _has_humongous_reclaim_candidates;
 255 
 256   volatile uint _gc_time_stamp;
 257 
 258   G1HRPrinter _hr_printer;
 259 
 260   // It decides whether an explicit GC should start a concurrent cycle
 261   // instead of doing a STW GC. Currently, a concurrent cycle is
 262   // explicitly started if:
 263   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 264   // (b) cause == _g1_humongous_allocation
 265   // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 266   // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 267   // (e) cause == _update_allocation_context_stats_inc
 268   // (f) cause == _wb_conc_mark
 269   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 270 
 271   // indicates whether we are in young or mixed GC mode
 272   G1CollectorState _collector_state;
 273 
 274   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 275   // concurrent cycles) we have started.
 276   volatile uint _old_marking_cycles_started;
 277 
 278   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 279   // concurrent cycles) we have completed.
 280   volatile uint _old_marking_cycles_completed;
 281 
 282   // This is a non-product method that is helpful for testing. It is
 283   // called at the end of a GC and artificially expands the heap by
 284   // allocating a number of dead regions. This way we can induce very
 285   // frequent marking cycles and stress the cleanup / concurrent
 286   // cleanup code more (as all the regions that will be allocated by
 287   // this method will be found dead by the marking cycle).
 288   void allocate_dummy_regions() PRODUCT_RETURN;
 289 
 290   // Clear RSets after a compaction. It also resets the GC time stamps.
 291   void clear_rsets_post_compaction();
 292 
 293   // If the HR printer is active, dump the state of the regions in the
 294   // heap after a compaction.
 295   void print_hrm_post_compaction();
 296 
 297   // Create a memory mapper for auxiliary data structures of the given size and
 298   // translation factor.
 299   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 300                                                          size_t size,
 301                                                          size_t translation_factor);
 302 
 303   static G1Policy* create_g1_policy();
 304 
 305   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 306 
 307   void process_weak_jni_handles();
 308 
 309   // These are macros so that, if the assert fires, we get the correct
 310   // line number, file, etc.
 311 
 312 #define heap_locking_asserts_params(_extra_message_)                          \
 313   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 314   (_extra_message_),                                                          \
 315   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 316   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 317   BOOL_TO_STR(Thread::current()->is_VM_thread())
 318 
 319 #define assert_heap_locked()                                                  \
 320   do {                                                                        \
 321     assert(Heap_lock->owned_by_self(),                                        \
 322            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 323   } while (0)
 324 
 325 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 326   do {                                                                        \
 327     assert(Heap_lock->owned_by_self() ||                                      \
 328            (SafepointSynchronize::is_at_safepoint() &&                        \
 329              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 330            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 331                                         "should be at a safepoint"));         \
 332   } while (0)
 333 
 334 #define assert_heap_locked_and_not_at_safepoint()                             \
 335   do {                                                                        \
 336     assert(Heap_lock->owned_by_self() &&                                      \
 337                                     !SafepointSynchronize::is_at_safepoint(), \
 338           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 339                                        "should not be at a safepoint"));      \
 340   } while (0)
 341 
 342 #define assert_heap_not_locked()                                              \
 343   do {                                                                        \
 344     assert(!Heap_lock->owned_by_self(),                                       \
 345         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 346   } while (0)
 347 
 348 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 349   do {                                                                        \
 350     assert(!Heap_lock->owned_by_self() &&                                     \
 351                                     !SafepointSynchronize::is_at_safepoint(), \
 352       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 353                                    "should not be at a safepoint"));          \
 354   } while (0)
 355 
 356 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 357   do {                                                                        \
 358     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 359               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 360            heap_locking_asserts_params("should be at a safepoint"));          \
 361   } while (0)
 362 
 363 #define assert_not_at_safepoint()                                             \
 364   do {                                                                        \
 365     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 366            heap_locking_asserts_params("should not be at a safepoint"));      \
 367   } while (0)
 368 
 369 protected:
 370 
 371   // The young region list.
 372   G1EdenRegions _eden;
 373   G1SurvivorRegions _survivor;
 374 
 375   // The current policy object for the collector.
 376   G1Policy* _g1_policy;
 377   G1HeapSizingPolicy* _heap_sizing_policy;
 378 
 379   G1CollectionSet _collection_set;
 380 
 381   // This is the second level of trying to allocate a new region. If
 382   // new_region() didn't find a region on the free_list, this call will
 383   // check whether there's anything available on the
 384   // secondary_free_list and/or wait for more regions to appear on
 385   // that list, if _free_regions_coming is set.
 386   HeapRegion* new_region_try_secondary_free_list(bool is_old);
 387 
 388   // Try to allocate a single non-humongous HeapRegion sufficient for
 389   // an allocation of the given word_size. If do_expand is true,
 390   // attempt to expand the heap if necessary to satisfy the allocation
 391   // request. If the region is to be used as an old region or for a
 392   // humongous object, set is_old to true. If not, to false.
 393   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 394 
 395   // Initialize a contiguous set of free regions of length num_regions
 396   // and starting at index first so that they appear as a single
 397   // humongous region.
 398   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 399                                                       uint num_regions,
 400                                                       size_t word_size,
 401                                                       AllocationContext_t context);
 402 
 403   // Attempt to allocate a humongous object of the given size. Return
 404   // NULL if unsuccessful.
 405   HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
 406 
 407   // The following two methods, allocate_new_tlab() and
 408   // mem_allocate(), are the two main entry points from the runtime
 409   // into the G1's allocation routines. They have the following
 410   // assumptions:
 411   //
 412   // * They should both be called outside safepoints.
 413   //
 414   // * They should both be called without holding the Heap_lock.
 415   //
 416   // * All allocation requests for new TLABs should go to
 417   //   allocate_new_tlab().
 418   //
 419   // * All non-TLAB allocation requests should go to mem_allocate().
 420   //
 421   // * If either call cannot satisfy the allocation request using the
 422   //   current allocating region, they will try to get a new one. If
 423   //   this fails, they will attempt to do an evacuation pause and
 424   //   retry the allocation.
 425   //
 426   // * If all allocation attempts fail, even after trying to schedule
 427   //   an evacuation pause, allocate_new_tlab() will return NULL,
 428   //   whereas mem_allocate() will attempt a heap expansion and/or
 429   //   schedule a Full GC.
 430   //
 431   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 432   //   should never be called with word_size being humongous. All
 433   //   humongous allocation requests should go to mem_allocate() which
 434   //   will satisfy them with a special path.
 435 
 436   virtual HeapWord* allocate_new_tlab(size_t word_size);
 437 
 438   virtual HeapWord* mem_allocate(size_t word_size,
 439                                  bool*  gc_overhead_limit_was_exceeded);
 440 
 441   // The following three methods take a gc_count_before_ret
 442   // parameter which is used to return the GC count if the method
 443   // returns NULL. Given that we are required to read the GC count
 444   // while holding the Heap_lock, and these paths will take the
 445   // Heap_lock at some point, it's easier to get them to read the GC
 446   // count while holding the Heap_lock before they return NULL instead
 447   // of the caller (namely: mem_allocate()) having to also take the
 448   // Heap_lock just to read the GC count.
 449 
 450   // First-level mutator allocation attempt: try to allocate out of
 451   // the mutator alloc region without taking the Heap_lock. This
 452   // should only be used for non-humongous allocations.
 453   inline HeapWord* attempt_allocation(size_t word_size,
 454                                       uint* gc_count_before_ret,
 455                                       uint* gclocker_retry_count_ret);
 456 
 457   // Second-level mutator allocation attempt: take the Heap_lock and
 458   // retry the allocation attempt, potentially scheduling a GC
 459   // pause. This should only be used for non-humongous allocations.
 460   HeapWord* attempt_allocation_slow(size_t word_size,
 461                                     AllocationContext_t context,
 462                                     uint* gc_count_before_ret,
 463                                     uint* gclocker_retry_count_ret);
 464 
 465   // Takes the Heap_lock and attempts a humongous allocation. It can
 466   // potentially schedule a GC pause.
 467   HeapWord* attempt_allocation_humongous(size_t word_size,
 468                                          uint* gc_count_before_ret,
 469                                          uint* gclocker_retry_count_ret);
 470 
 471   // Allocation attempt that should be called during safepoints (e.g.,
 472   // at the end of a successful GC). expect_null_mutator_alloc_region
 473   // specifies whether the mutator alloc region is expected to be NULL
 474   // or not.
 475   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 476                                             AllocationContext_t context,
 477                                             bool expect_null_mutator_alloc_region);
 478 
 479   // These methods are the "callbacks" from the G1AllocRegion class.
 480 
 481   // For mutator alloc regions.
 482   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 483   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 484                                    size_t allocated_bytes);
 485 
 486   // For GC alloc regions.
 487   bool has_more_regions(InCSetState dest);
 488   HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
 489   void retire_gc_alloc_region(HeapRegion* alloc_region,
 490                               size_t allocated_bytes, InCSetState dest);
 491 
 492   // - if explicit_gc is true, the GC is for a System.gc() etc,
 493   //   otherwise it's for a failed allocation.
 494   // - if clear_all_soft_refs is true, all soft references should be
 495   //   cleared during the GC.
 496   // - it returns false if it is unable to do the collection due to the
 497   //   GC locker being active, true otherwise.
 498   bool do_full_collection(bool explicit_gc,
 499                           bool clear_all_soft_refs);
 500 
 501   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 502   virtual void do_full_collection(bool clear_all_soft_refs);
 503 
 504   // Resize the heap if necessary after a full collection.
 505   void resize_if_necessary_after_full_collection();
 506 
 507   // Callback from VM_G1CollectForAllocation operation.
 508   // This function does everything necessary/possible to satisfy a
 509   // failed allocation request (including collection, expansion, etc.)
 510   HeapWord* satisfy_failed_allocation(size_t word_size,
 511                                       AllocationContext_t context,
 512                                       bool* succeeded);
 513 private:
 514   // Internal helpers used during full GC to split it up to
 515   // increase readability.
 516   void do_full_collection_inner(G1FullGCScope* scope);
 517   void abort_concurrent_cycle();
 518   void prepare_heap_for_full_collection();
 519   void reset_card_cache_and_queue();
 520   void verify_before_full_collection(bool explicit_gc);
 521   void verify_after_full_collection();
 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   WorkGang* workers() const { return _workers; }
 554 
 555   G1Allocator* allocator() {
 556     return _allocator;
 557   }
 558 
 559   G1HeapVerifier* verifier() {
 560     return _verifier;
 561   }
 562 
 563   G1MonitoringSupport* g1mm() {
 564     assert(_g1mm != NULL, "should have been initialized");
 565     return _g1mm;
 566   }
 567 
 568   // Expand the garbage-first heap by at least the given size (in bytes!).
 569   // Returns true if the heap was expanded by the requested amount;
 570   // false otherwise.
 571   // (Rounds up to a HeapRegion boundary.)
 572   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 573 
 574   // Returns the PLAB statistics for a given destination.
 575   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 576 
 577   // Determines PLAB size for a given destination.
 578   inline size_t desired_plab_sz(InCSetState dest);
 579 
 580   inline AllocationContextStats& allocation_context_stats();
 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();
 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);
 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   // The closure used to refine a single card.
 794   RefineCardTableEntryClosure* _refine_cte_cl;
 795 
 796   // After a collection pause, convert the regions in the collection set into free
 797   // regions.
 798   void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 799 
 800   // Abandon the current collection set without recording policy
 801   // statistics or updating free lists.
 802   void abandon_collection_set(G1CollectionSet* collection_set);
 803 
 804   // The concurrent marker (and the thread it runs in.)
 805   G1ConcurrentMark* _cm;
 806   ConcurrentMarkThread* _cmThread;
 807 
 808   // The concurrent refiner.
 809   ConcurrentG1Refine* _cg1r;
 810 
 811   // The parallel task queues
 812   RefToScanQueueSet *_task_queues;
 813 
 814   // True iff a evacuation has failed in the current collection.
 815   bool _evacuation_failed;
 816 
 817   EvacuationFailedInfo* _evacuation_failed_info_array;
 818 
 819   // Failed evacuations cause some logical from-space objects to have
 820   // forwarding pointers to themselves.  Reset them.
 821   void remove_self_forwarding_pointers();
 822 
 823   // Restore the objects in the regions in the collection set after an
 824   // evacuation failure.
 825   void restore_after_evac_failure();
 826 
 827   PreservedMarksSet _preserved_marks_set;
 828 
 829   // Preserve the mark of "obj", if necessary, in preparation for its mark
 830   // word being overwritten with a self-forwarding-pointer.
 831   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 832 
 833 #ifndef PRODUCT
 834   // Support for forcing evacuation failures. Analogous to
 835   // PromotionFailureALot for the other collectors.
 836 
 837   // Records whether G1EvacuationFailureALot should be in effect
 838   // for the current GC
 839   bool _evacuation_failure_alot_for_current_gc;
 840 
 841   // Used to record the GC number for interval checking when
 842   // determining whether G1EvaucationFailureALot is in effect
 843   // for the current GC.
 844   size_t _evacuation_failure_alot_gc_number;
 845 
 846   // Count of the number of evacuations between failures.
 847   volatile size_t _evacuation_failure_alot_count;
 848 
 849   // Set whether G1EvacuationFailureALot should be in effect
 850   // for the current GC (based upon the type of GC and which
 851   // command line flags are set);
 852   inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
 853                                                   bool during_initial_mark,
 854                                                   bool during_marking);
 855 
 856   inline void set_evacuation_failure_alot_for_current_gc();
 857 
 858   // Return true if it's time to cause an evacuation failure.
 859   inline bool evacuation_should_fail();
 860 
 861   // Reset the G1EvacuationFailureALot counters.  Should be called at
 862   // the end of an evacuation pause in which an evacuation failure occurred.
 863   inline void reset_evacuation_should_fail();
 864 #endif // !PRODUCT
 865 
 866   // ("Weak") Reference processing support.
 867   //
 868   // G1 has 2 instances of the reference processor class. One
 869   // (_ref_processor_cm) handles reference object discovery
 870   // and subsequent processing during concurrent marking cycles.
 871   //
 872   // The other (_ref_processor_stw) handles reference object
 873   // discovery and processing during full GCs and incremental
 874   // evacuation pauses.
 875   //
 876   // During an incremental pause, reference discovery will be
 877   // temporarily disabled for _ref_processor_cm and will be
 878   // enabled for _ref_processor_stw. At the end of the evacuation
 879   // pause references discovered by _ref_processor_stw will be
 880   // processed and discovery will be disabled. The previous
 881   // setting for reference object discovery for _ref_processor_cm
 882   // will be re-instated.
 883   //
 884   // At the start of marking:
 885   //  * Discovery by the CM ref processor is verified to be inactive
 886   //    and it's discovered lists are empty.
 887   //  * Discovery by the CM ref processor is then enabled.
 888   //
 889   // At the end of marking:
 890   //  * Any references on the CM ref processor's discovered
 891   //    lists are processed (possibly MT).
 892   //
 893   // At the start of full GC we:
 894   //  * Disable discovery by the CM ref processor and
 895   //    empty CM ref processor's discovered lists
 896   //    (without processing any entries).
 897   //  * Verify that the STW ref processor is inactive and it's
 898   //    discovered lists are empty.
 899   //  * Temporarily set STW ref processor discovery as single threaded.
 900   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 901   //    field.
 902   //  * Finally enable discovery by the STW ref processor.
 903   //
 904   // The STW ref processor is used to record any discovered
 905   // references during the full GC.
 906   //
 907   // At the end of a full GC we:
 908   //  * Enqueue any reference objects discovered by the STW ref processor
 909   //    that have non-live referents. This has the side-effect of
 910   //    making the STW ref processor inactive by disabling discovery.
 911   //  * Verify that the CM ref processor is still inactive
 912   //    and no references have been placed on it's discovered
 913   //    lists (also checked as a precondition during initial marking).
 914 
 915   // The (stw) reference processor...
 916   ReferenceProcessor* _ref_processor_stw;
 917 
 918   STWGCTimer* _gc_timer_stw;
 919 
 920   G1NewTracer* _gc_tracer_stw;
 921 
 922   // During reference object discovery, the _is_alive_non_header
 923   // closure (if non-null) is applied to the referent object to
 924   // determine whether the referent is live. If so then the
 925   // reference object does not need to be 'discovered' and can
 926   // be treated as a regular oop. This has the benefit of reducing
 927   // the number of 'discovered' reference objects that need to
 928   // be processed.
 929   //
 930   // Instance of the is_alive closure for embedding into the
 931   // STW reference processor as the _is_alive_non_header field.
 932   // Supplying a value for the _is_alive_non_header field is
 933   // optional but doing so prevents unnecessary additions to
 934   // the discovered lists during reference discovery.
 935   G1STWIsAliveClosure _is_alive_closure_stw;
 936 
 937   // The (concurrent marking) reference processor...
 938   ReferenceProcessor* _ref_processor_cm;
 939 
 940   // Instance of the concurrent mark is_alive closure for embedding
 941   // into the Concurrent Marking reference processor as the
 942   // _is_alive_non_header field. Supplying a value for the
 943   // _is_alive_non_header field is optional but doing so prevents
 944   // unnecessary additions to the discovered lists during reference
 945   // discovery.
 946   G1CMIsAliveClosure _is_alive_closure_cm;
 947 
 948   volatile bool _free_regions_coming;
 949 
 950 public:
 951 
 952   void set_refine_cte_cl_concurrency(bool concurrent);
 953 
 954   RefToScanQueue *task_queue(uint i) const;
 955 
 956   uint num_task_queues() const;
 957 
 958   // A set of cards where updates happened during the GC
 959   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 960 
 961   // Create a G1CollectedHeap with the specified policy.
 962   // Must call the initialize method afterwards.
 963   // May not return if something goes wrong.
 964   G1CollectedHeap(G1CollectorPolicy* policy);
 965 
 966   // Initialize the G1CollectedHeap to have the initial and
 967   // maximum sizes and remembered and barrier sets
 968   // specified by the policy object.
 969   jint initialize();
 970 
 971   virtual void stop();
 972 
 973   // Return the (conservative) maximum heap alignment for any G1 heap
 974   static size_t conservative_max_heap_alignment();
 975 
 976   // Does operations required after initialization has been done.
 977   void post_initialize();
 978 
 979   // Initialize weak reference processing.
 980   void ref_processing_init();
 981 
 982   virtual Name kind() const {
 983     return CollectedHeap::G1CollectedHeap;
 984   }
 985 
 986   virtual const char* name() const {
 987     return "G1";
 988   }
 989 
 990   const G1CollectorState* collector_state() const { return &_collector_state; }
 991   G1CollectorState* collector_state() { return &_collector_state; }
 992 
 993   // The current policy object for the collector.
 994   G1Policy* g1_policy() const { return _g1_policy; }
 995 
 996   const G1CollectionSet* collection_set() const { return &_collection_set; }
 997   G1CollectionSet* collection_set() { return &_collection_set; }
 998 
 999   virtual CollectorPolicy* collector_policy() const;
1000 
1001   // Adaptive size policy.  No such thing for g1.
1002   virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1003 
1004   // The rem set and barrier set.
1005   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1006 
1007   // Try to minimize the remembered set.
1008   void scrub_rem_set();
1009 
1010   uint get_gc_time_stamp() {
1011     return _gc_time_stamp;
1012   }
1013 
1014   inline void reset_gc_time_stamp();
1015 
1016   void check_gc_time_stamps() PRODUCT_RETURN;
1017 
1018   inline void increment_gc_time_stamp();
1019 
1020   // Reset the given region's GC timestamp. If it's starts humongous,
1021   // also reset the GC timestamp of its corresponding
1022   // continues humongous regions too.
1023   void reset_gc_time_stamps(HeapRegion* hr);
1024 
1025   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1026   void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1027 
1028   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1029   void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1030 
1031   // The shared block offset table array.
1032   G1BlockOffsetTable* bot() const { return _bot; }
1033 
1034   // Reference Processing accessors
1035 
1036   // The STW reference processor....
1037   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1038 
1039   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1040 
1041   // The Concurrent Marking reference processor...
1042   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1043 
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   // The current number of regions in the heap.
1062   uint num_regions() const { return _hrm.length(); }
1063 
1064   // The max number of regions in the heap.
1065   uint max_regions() const { return _hrm.max_length(); }
1066 
1067   // The number of regions that are completely free.
1068   uint num_free_regions() const { return _hrm.num_free_regions(); }
1069 
1070   MemoryUsage get_auxiliary_data_memory_usage() const {
1071     return _hrm.get_auxiliary_data_memory_usage();
1072   }
1073 
1074   // The number of regions that are not completely free.
1075   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1076 
1077 #ifdef ASSERT
1078   bool is_on_master_free_list(HeapRegion* hr) {
1079     return _hrm.is_free(hr);
1080   }
1081 #endif // ASSERT
1082 
1083   // Wrapper for the region list operations that can be called from
1084   // methods outside this class.
1085 
1086   void secondary_free_list_add(FreeRegionList* list) {
1087     _secondary_free_list.add_ordered(list);
1088   }
1089 
1090   void append_secondary_free_list() {
1091     _hrm.insert_list_into_free_list(&_secondary_free_list);
1092   }
1093 
1094   void append_secondary_free_list_if_not_empty_with_lock() {
1095     // If the secondary free list looks empty there's no reason to
1096     // take the lock and then try to append it.
1097     if (!_secondary_free_list.is_empty()) {
1098       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1099       append_secondary_free_list();
1100     }
1101   }
1102 
1103   inline void old_set_add(HeapRegion* hr);
1104   inline void old_set_remove(HeapRegion* hr);
1105 
1106   size_t non_young_capacity_bytes() {
1107     return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1108   }
1109 
1110   void set_free_regions_coming();
1111   void reset_free_regions_coming();
1112   bool free_regions_coming() { return _free_regions_coming; }
1113   void wait_while_free_regions_coming();
1114 
1115   // Determine whether the given region is one that we are using as an
1116   // old GC alloc region.
1117   bool is_old_gc_alloc_region(HeapRegion* hr);
1118 
1119   // Perform a collection of the heap; intended for use in implementing
1120   // "System.gc".  This probably implies as full a collection as the
1121   // "CollectedHeap" supports.
1122   virtual void collect(GCCause::Cause cause);
1123 
1124   virtual bool copy_allocation_context_stats(const jint* contexts,
1125                                              jlong* totals,
1126                                              jbyte* accuracy,
1127                                              jint len);
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 
1148   inline bool is_in_cset_or_humongous(const oop obj);
1149 
1150  private:
1151   // This array is used for a quick test on whether a reference points into
1152   // the collection set or not. Each of the array's elements denotes whether the
1153   // corresponding region is in the collection set or not.
1154   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1155 
1156  public:
1157 
1158   inline InCSetState in_cset_state(const oop obj);
1159 
1160   // Return "TRUE" iff the given object address is in the reserved
1161   // region of g1.
1162   bool is_in_g1_reserved(const void* p) const {
1163     return _hrm.reserved().contains(p);
1164   }
1165 
1166   // Returns a MemRegion that corresponds to the space that has been
1167   // reserved for the heap
1168   MemRegion g1_reserved() const {
1169     return _hrm.reserved();
1170   }
1171 
1172   virtual bool is_in_closed_subset(const void* p) const;
1173 
1174   G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1175     return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1176   }
1177 
1178   // Iteration functions.
1179 
1180   // Iterate over all objects, calling "cl.do_object" on each.
1181   virtual void object_iterate(ObjectClosure* cl);
1182 
1183   virtual void safe_object_iterate(ObjectClosure* cl) {
1184     object_iterate(cl);
1185   }
1186 
1187   // Iterate over heap regions, in address order, terminating the
1188   // iteration early if the "doHeapRegion" method returns "true".
1189   void heap_region_iterate(HeapRegionClosure* blk) const;
1190 
1191   // Return the region with the given index. It assumes the index is valid.
1192   inline HeapRegion* region_at(uint index) const;
1193 
1194   // Return the next region (by index) that is part of the same
1195   // humongous object that hr is part of.
1196   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1197 
1198   // Calculate the region index of the given address. Given address must be
1199   // within the heap.
1200   inline uint addr_to_region(HeapWord* addr) const;
1201 
1202   inline HeapWord* bottom_addr_for_region(uint index) const;
1203 
1204   // Iterate over the heap regions in parallel. Assumes that this will be called
1205   // in parallel by ParallelGCThreads worker threads with distinct worker ids
1206   // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1207   // to each of the regions, by attempting to claim the region using the
1208   // HeapRegionClaimer and, if successful, applying the closure to the claimed
1209   // region. The concurrent argument should be set to true if iteration is
1210   // performed concurrently, during which no assumptions are made for consistent
1211   // attributes of the heap regions (as they might be modified while iterating).
1212   void heap_region_par_iterate(HeapRegionClosure* cl,
1213                                uint worker_id,
1214                                HeapRegionClaimer* hrclaimer,
1215                                bool concurrent = false) const;
1216 
1217   // Iterate over the regions (if any) in the current collection set.
1218   void collection_set_iterate(HeapRegionClosure* blk);
1219 
1220   // Iterate over the regions (if any) in the current collection set. Starts the
1221   // iteration over the entire collection set so that the start regions of a given
1222   // worker id over the set active_workers are evenly spread across the set of
1223   // collection set regions.
1224   void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1225 
1226   HeapRegion* next_compaction_region(const HeapRegion* from) const;
1227 
1228   // Returns the HeapRegion that contains addr. addr must not be NULL.
1229   template <class T>
1230   inline HeapRegion* heap_region_containing(const T addr) const;
1231 
1232   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1233   // each address in the (reserved) heap is a member of exactly
1234   // one block.  The defining characteristic of a block is that it is
1235   // possible to find its size, and thus to progress forward to the next
1236   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1237   // represent Java objects, or they might be free blocks in a
1238   // free-list-based heap (or subheap), as long as the two kinds are
1239   // distinguishable and the size of each is determinable.
1240 
1241   // Returns the address of the start of the "block" that contains the
1242   // address "addr".  We say "blocks" instead of "object" since some heaps
1243   // may not pack objects densely; a chunk may either be an object or a
1244   // non-object.
1245   virtual HeapWord* block_start(const void* addr) const;
1246 
1247   // Requires "addr" to be the start of a chunk, and returns its size.
1248   // "addr + size" is required to be the start of a new chunk, or the end
1249   // of the active area of the heap.
1250   virtual size_t block_size(const HeapWord* addr) const;
1251 
1252   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1253   // the block is an object.
1254   virtual bool block_is_obj(const HeapWord* addr) const;
1255 
1256   // Section on thread-local allocation buffers (TLABs)
1257   // See CollectedHeap for semantics.
1258 
1259   bool supports_tlab_allocation() const;
1260   size_t tlab_capacity(Thread* ignored) const;
1261   size_t tlab_used(Thread* ignored) const;
1262   size_t max_tlab_size() const;
1263   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1264 
1265   // Can a compiler initialize a new object without store barriers?
1266   // This permission only extends from the creation of a new object
1267   // via a TLAB up to the first subsequent safepoint. If such permission
1268   // is granted for this heap type, the compiler promises to call
1269   // defer_store_barrier() below on any slow path allocation of
1270   // a new object for which such initializing store barriers will
1271   // have been elided. G1, like CMS, allows this, but should be
1272   // ready to provide a compensating write barrier as necessary
1273   // if that storage came out of a non-young region. The efficiency
1274   // of this implementation depends crucially on being able to
1275   // answer very efficiently in constant time whether a piece of
1276   // storage in the heap comes from a young region or not.
1277   // See ReduceInitialCardMarks.
1278   virtual bool can_elide_tlab_store_barriers() const {
1279     return true;
1280   }
1281 
1282   virtual bool card_mark_must_follow_store() const {
1283     return true;
1284   }
1285 
1286   inline bool is_in_young(const oop obj);
1287 
1288   virtual bool is_scavengable(const void* addr);
1289 
1290   // We don't need barriers for initializing stores to objects
1291   // in the young gen: for the SATB pre-barrier, there is no
1292   // pre-value that needs to be remembered; for the remembered-set
1293   // update logging post-barrier, we don't maintain remembered set
1294   // information for young gen objects.
1295   virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1296 
1297   // Returns "true" iff the given word_size is "very large".
1298   static bool is_humongous(size_t word_size) {
1299     // Note this has to be strictly greater-than as the TLABs
1300     // are capped at the humongous threshold and we want to
1301     // ensure that we don't try to allocate a TLAB as
1302     // humongous and that we don't allocate a humongous
1303     // object in a TLAB.
1304     return word_size > _humongous_object_threshold_in_words;
1305   }
1306 
1307   // Returns the humongous threshold for a specific region size
1308   static size_t humongous_threshold_for(size_t region_size) {
1309     return (region_size / 2);
1310   }
1311 
1312   // Returns the number of regions the humongous object of the given word size
1313   // requires.
1314   static size_t humongous_obj_size_in_regions(size_t word_size);
1315 
1316   // Print the maximum heap capacity.
1317   virtual size_t max_capacity() const;
1318 
1319   virtual jlong millis_since_last_gc();
1320 
1321 
1322   // Convenience function to be used in situations where the heap type can be
1323   // asserted to be this type.
1324   static G1CollectedHeap* heap();
1325 
1326   void set_region_short_lived_locked(HeapRegion* hr);
1327   // add appropriate methods for any other surv rate groups
1328 
1329   const G1SurvivorRegions* survivor() const { return &_survivor; }
1330 
1331   uint survivor_regions_count() const {
1332     return _survivor.length();
1333   }
1334 
1335   uint eden_regions_count() const {
1336     return _eden.length();
1337   }
1338 
1339   uint young_regions_count() const {
1340     return _eden.length() + _survivor.length();
1341   }
1342 
1343   uint old_regions_count() const { return _old_set.length(); }
1344 
1345   uint humongous_regions_count() const { return _humongous_set.length(); }
1346 
1347 #ifdef ASSERT
1348   bool check_young_list_empty();
1349 #endif
1350 
1351   // *** Stuff related to concurrent marking.  It's not clear to me that so
1352   // many of these need to be public.
1353 
1354   // The functions below are helper functions that a subclass of
1355   // "CollectedHeap" can use in the implementation of its virtual
1356   // functions.
1357   // This performs a concurrent marking of the live objects in a
1358   // bitmap off to the side.
1359   void doConcurrentMark();
1360 
1361   bool isMarkedNext(oop obj) const;
1362 
1363   // Determine if an object is dead, given the object and also
1364   // the region to which the object belongs. An object is dead
1365   // iff a) it was not allocated since the last mark, b) it
1366   // is not marked, and c) it is not in an archive region.
1367   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1368     return
1369       hr->is_obj_dead(obj, _cm->prevMarkBitMap()) &&
1370       !hr->is_archive();
1371   }
1372 
1373   // This function returns true when an object has been
1374   // around since the previous marking and hasn't yet
1375   // been marked during this marking, and is not in an archive region.
1376   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1377     return
1378       !hr->obj_allocated_since_next_marking(obj) &&
1379       !isMarkedNext(obj) &&
1380       !hr->is_archive();
1381   }
1382 
1383   // Determine if an object is dead, given only the object itself.
1384   // This will find the region to which the object belongs and
1385   // then call the region version of the same function.
1386 
1387   // Added if it is NULL it isn't dead.
1388 
1389   inline bool is_obj_dead(const oop obj) const;
1390 
1391   inline bool is_obj_ill(const oop obj) const;
1392 
1393   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1394 
1395   // Refinement
1396 
1397   ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1398 
1399   // Optimized nmethod scanning support routines
1400 
1401   // Register the given nmethod with the G1 heap.
1402   virtual void register_nmethod(nmethod* nm);
1403 
1404   // Unregister the given nmethod from the G1 heap.
1405   virtual void unregister_nmethod(nmethod* nm);
1406 
1407   // Free up superfluous code root memory.
1408   void purge_code_root_memory();
1409 
1410   // Rebuild the strong code root lists for each region
1411   // after a full GC.
1412   void rebuild_strong_code_roots();
1413 
1414   // Partial cleaning used when class unloading is disabled.
1415   // Let the caller choose what structures to clean out:
1416   // - StringTable
1417   // - SymbolTable
1418   // - StringDeduplication structures
1419   void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1420 
1421   // Complete cleaning used when class unloading is enabled.
1422   // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1423   void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1424 
1425   // Redirty logged cards in the refinement queue.
1426   void redirty_logged_cards();
1427   // Verification
1428 
1429   // Perform any cleanup actions necessary before allowing a verification.
1430   virtual void prepare_for_verify();
1431 
1432   // Perform verification.
1433 
1434   // vo == UsePrevMarking  -> use "prev" marking information,
1435   // vo == UseNextMarking -> use "next" marking information
1436   // vo == UseMarkWord    -> use the mark word in the object header
1437   //
1438   // NOTE: Only the "prev" marking information is guaranteed to be
1439   // consistent most of the time, so most calls to this should use
1440   // vo == UsePrevMarking.
1441   // Currently, there is only one case where this is called with
1442   // vo == UseNextMarking, which is to verify the "next" marking
1443   // information at the end of remark.
1444   // Currently there is only one place where this is called with
1445   // vo == UseMarkWord, which is to verify the marking during a
1446   // full GC.
1447   void verify(VerifyOption vo);
1448 
1449   // WhiteBox testing support.
1450   virtual bool supports_concurrent_phase_control() const;
1451   virtual const char* const* concurrent_phases() const;
1452   virtual bool request_concurrent_phase(const char* phase);
1453 
1454   // The methods below are here for convenience and dispatch the
1455   // appropriate method depending on value of the given VerifyOption
1456   // parameter. The values for that parameter, and their meanings,
1457   // are the same as those above.
1458 
1459   bool is_obj_dead_cond(const oop obj,
1460                         const HeapRegion* hr,
1461                         const VerifyOption vo) const;
1462 
1463   bool is_obj_dead_cond(const oop obj,
1464                         const VerifyOption vo) const;
1465 
1466   G1HeapSummary create_g1_heap_summary();
1467   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1468 
1469   // Printing
1470 private:
1471   void print_heap_regions() const;
1472   void print_regions_on(outputStream* st) const;
1473 
1474 public:
1475   virtual void print_on(outputStream* st) const;
1476   virtual void print_extended_on(outputStream* st) const;
1477   virtual void print_on_error(outputStream* st) const;
1478 
1479   virtual void print_gc_threads_on(outputStream* st) const;
1480   virtual void gc_threads_do(ThreadClosure* tc) const;
1481 
1482   // Override
1483   void print_tracing_info() const;
1484 
1485   // The following two methods are helpful for debugging RSet issues.
1486   void print_cset_rsets() PRODUCT_RETURN;
1487   void print_all_rsets() PRODUCT_RETURN;
1488 
1489 public:
1490   size_t pending_card_num();
1491 
1492 protected:
1493   size_t _max_heap_capacity;
1494 };
1495 
1496 class G1ParEvacuateFollowersClosure : public VoidClosure {
1497 private:
1498   double _start_term;
1499   double _term_time;
1500   size_t _term_attempts;
1501 
1502   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1503   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1504 protected:
1505   G1CollectedHeap*              _g1h;
1506   G1ParScanThreadState*         _par_scan_state;
1507   RefToScanQueueSet*            _queues;
1508   ParallelTaskTerminator*       _terminator;
1509 
1510   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1511   RefToScanQueueSet*      queues()         { return _queues; }
1512   ParallelTaskTerminator* terminator()     { return _terminator; }
1513 
1514 public:
1515   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1516                                 G1ParScanThreadState* par_scan_state,
1517                                 RefToScanQueueSet* queues,
1518                                 ParallelTaskTerminator* terminator)
1519     : _g1h(g1h), _par_scan_state(par_scan_state),
1520       _queues(queues), _terminator(terminator),
1521       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1522 
1523   void do_void();
1524 
1525   double term_time() const { return _term_time; }
1526   size_t term_attempts() const { return _term_attempts; }
1527 
1528 private:
1529   inline bool offer_termination();
1530 };
1531 
1532 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP