1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
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  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  24 
  25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
  26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
  27 
  28 #include "gc/g1/concurrentMark.hpp"
  29 #include "gc/g1/evacuationInfo.hpp"
  30 #include "gc/g1/g1AllocationContext.hpp"
  31 #include "gc/g1/g1BiasedArray.hpp"
  32 #include "gc/g1/g1CollectorState.hpp"
  33 #include "gc/g1/g1HRPrinter.hpp"
  34 #include "gc/g1/g1InCSetState.hpp"
  35 #include "gc/g1/g1MonitoringSupport.hpp"
  36 #include "gc/g1/g1EvacStats.hpp"
  37 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
  38 #include "gc/g1/g1YCTypes.hpp"
  39 #include "gc/g1/hSpaceCounters.hpp"
  40 #include "gc/g1/heapRegionManager.hpp"
  41 #include "gc/g1/heapRegionSet.hpp"
  42 #include "gc/g1/youngList.hpp"
  43 #include "gc/shared/barrierSet.hpp"
  44 #include "gc/shared/collectedHeap.hpp"
  45 #include "gc/shared/plab.hpp"
  46 #include "memory/memRegion.hpp"
  47 #include "utilities/stack.hpp"
  48 
  49 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  50 // It uses the "Garbage First" heap organization and algorithm, which
  51 // may combine concurrent marking with parallel, incremental compaction of
  52 // heap subsets that will yield large amounts of garbage.
  53 
  54 // Forward declarations
  55 class HeapRegion;
  56 class HRRSCleanupTask;
  57 class GenerationSpec;
  58 class OopsInHeapRegionClosure;
  59 class G1ParScanThreadState;
  60 class G1ParScanThreadStateSet;
  61 class G1KlassScanClosure;
  62 class G1ParScanThreadState;
  63 class ObjectClosure;
  64 class SpaceClosure;
  65 class CompactibleSpaceClosure;
  66 class Space;
  67 class G1CollectorPolicy;
  68 class G1RemSet;
  69 class HeapRegionRemSetIterator;
  70 class ConcurrentMark;
  71 class ConcurrentMarkThread;
  72 class ConcurrentG1Refine;
  73 class ConcurrentGCTimer;
  74 class GenerationCounters;
  75 class STWGCTimer;
  76 class G1NewTracer;
  77 class G1OldTracer;
  78 class EvacuationFailedInfo;
  79 class nmethod;
  80 class Ticks;
  81 class WorkGang;
  82 class G1Allocator;
  83 class G1ArchiveAllocator;
  84 
  85 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
  86 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
  87 
  88 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
  89 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
  90 
  91 // The G1 STW is alive closure.
  92 // An instance is embedded into the G1CH and used as the
  93 // (optional) _is_alive_non_header closure in the STW
  94 // reference processor. It is also extensively used during
  95 // reference processing during STW evacuation pauses.
  96 class G1STWIsAliveClosure: public BoolObjectClosure {
  97   G1CollectedHeap* _g1;
  98 public:
  99   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 100   bool do_object_b(oop p);
 101 };
 102 
 103 class RefineCardTableEntryClosure;
 104 
 105 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 106  private:
 107   void reset_from_card_cache(uint start_idx, size_t num_regions);
 108  public:
 109   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 110 };
 111 
 112 class G1CollectedHeap : public CollectedHeap {
 113   friend class VM_CollectForMetadataAllocation;
 114   friend class VM_G1CollectForAllocation;
 115   friend class VM_G1CollectFull;
 116   friend class VM_G1IncCollectionPause;
 117   friend class VMStructs;
 118   friend class MutatorAllocRegion;
 119   friend class G1GCAllocRegion;
 120 
 121   // Closures used in implementation.
 122   friend class G1ParScanThreadState;
 123   friend class G1ParScanThreadStateSet;
 124   friend class G1ParTask;
 125   friend class G1PLABAllocator;
 126   friend class G1PrepareCompactClosure;
 127 
 128   // Other related classes.
 129   friend class HeapRegionClaimer;
 130 
 131   // Testing classes.
 132   friend class G1CheckCSetFastTableClosure;
 133 
 134 private:
 135   WorkGang* _workers;
 136 
 137   static size_t _humongous_object_threshold_in_words;
 138 
 139   // The secondary free list which contains regions that have been
 140   // freed up during the cleanup process. This will be appended to
 141   // the master free list when appropriate.
 142   FreeRegionList _secondary_free_list;
 143 
 144   // It keeps track of the old regions.
 145   HeapRegionSet _old_set;
 146 
 147   // It keeps track of the humongous regions.
 148   HeapRegionSet _humongous_set;
 149 
 150   void eagerly_reclaim_humongous_regions();
 151 
 152   // The number of regions we could create by expansion.
 153   uint _expansion_regions;
 154 
 155   // The block offset table for the G1 heap.
 156   G1BlockOffsetSharedArray* _bot_shared;
 157 
 158   // Tears down the region sets / lists so that they are empty and the
 159   // regions on the heap do not belong to a region set / list. The
 160   // only exception is the humongous set which we leave unaltered. If
 161   // free_list_only is true, it will only tear down the master free
 162   // list. It is called before a Full GC (free_list_only == false) or
 163   // before heap shrinking (free_list_only == true).
 164   void tear_down_region_sets(bool free_list_only);
 165 
 166   // Rebuilds the region sets / lists so that they are repopulated to
 167   // reflect the contents of the heap. The only exception is the
 168   // humongous set which was not torn down in the first place. If
 169   // free_list_only is true, it will only rebuild the master free
 170   // list. It is called after a Full GC (free_list_only == false) or
 171   // after heap shrinking (free_list_only == true).
 172   void rebuild_region_sets(bool free_list_only);
 173 
 174   // Callback for region mapping changed events.
 175   G1RegionMappingChangedListener _listener;
 176 
 177   // The sequence of all heap regions in the heap.
 178   HeapRegionManager _hrm;
 179 
 180   // Manages all allocations with regions except humongous object allocations.
 181   G1Allocator* _allocator;
 182 
 183   // Outside of GC pauses, the number of bytes used in all regions other
 184   // than the current allocation region(s).
 185   size_t _summary_bytes_used;
 186 
 187   void increase_used(size_t bytes);
 188   void decrease_used(size_t bytes);
 189 
 190   void set_used(size_t bytes);
 191 
 192   // Class that handles archive allocation ranges.
 193   G1ArchiveAllocator* _archive_allocator;
 194 
 195   // Statistics for each allocation context
 196   AllocationContextStats _allocation_context_stats;
 197 
 198   // GC allocation statistics policy for survivors.
 199   G1EvacStats _survivor_evac_stats;
 200 
 201   // GC allocation statistics policy for tenured objects.
 202   G1EvacStats _old_evac_stats;
 203 
 204   // It specifies whether we should attempt to expand the heap after a
 205   // region allocation failure. If heap expansion fails we set this to
 206   // false so that we don't re-attempt the heap expansion (it's likely
 207   // that subsequent expansion attempts will also fail if one fails).
 208   // Currently, it is only consulted during GC and it's reset at the
 209   // start of each GC.
 210   bool _expand_heap_after_alloc_failure;
 211 
 212   // Helper for monitoring and management support.
 213   G1MonitoringSupport* _g1mm;
 214 
 215   // Records whether the region at the given index is (still) a
 216   // candidate for eager reclaim.  Only valid for humongous start
 217   // regions; other regions have unspecified values.  Humongous start
 218   // regions are initialized at start of collection pause, with
 219   // candidates removed from the set as they are found reachable from
 220   // roots or the young generation.
 221   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 222    protected:
 223     bool default_value() const { return false; }
 224    public:
 225     void clear() { G1BiasedMappedArray<bool>::clear(); }
 226     void set_candidate(uint region, bool value) {
 227       set_by_index(region, value);
 228     }
 229     bool is_candidate(uint region) {
 230       return get_by_index(region);
 231     }
 232   };
 233 
 234   HumongousReclaimCandidates _humongous_reclaim_candidates;
 235   // Stores whether during humongous object registration we found candidate regions.
 236   // If not, we can skip a few steps.
 237   bool _has_humongous_reclaim_candidates;
 238 
 239   volatile unsigned _gc_time_stamp;
 240 
 241   G1HRPrinter _hr_printer;
 242 
 243   // It decides whether an explicit GC should start a concurrent cycle
 244   // instead of doing a STW GC. Currently, a concurrent cycle is
 245   // explicitly started if:
 246   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 247   // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 248   // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 249   // (d) cause == _g1_humongous_allocation
 250   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 251 
 252   // indicates whether we are in young or mixed GC mode
 253   G1CollectorState _collector_state;
 254 
 255   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 256   // concurrent cycles) we have started.
 257   volatile uint _old_marking_cycles_started;
 258 
 259   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 260   // concurrent cycles) we have completed.
 261   volatile uint _old_marking_cycles_completed;
 262 
 263   bool _heap_summary_sent;
 264 
 265   // This is a non-product method that is helpful for testing. It is
 266   // called at the end of a GC and artificially expands the heap by
 267   // allocating a number of dead regions. This way we can induce very
 268   // frequent marking cycles and stress the cleanup / concurrent
 269   // cleanup code more (as all the regions that will be allocated by
 270   // this method will be found dead by the marking cycle).
 271   void allocate_dummy_regions() PRODUCT_RETURN;
 272 
 273   // Clear RSets after a compaction. It also resets the GC time stamps.
 274   void clear_rsets_post_compaction();
 275 
 276   // If the HR printer is active, dump the state of the regions in the
 277   // heap after a compaction.
 278   void print_hrm_post_compaction();
 279 
 280   // Create a memory mapper for auxiliary data structures of the given size and
 281   // translation factor.
 282   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 283                                                          size_t size,
 284                                                          size_t translation_factor);
 285 
 286   double verify(bool guard, const char* msg);
 287   void verify_before_gc();
 288   void verify_after_gc();
 289 
 290   void log_gc_header();
 291   void log_gc_footer(double pause_time_sec);
 292 
 293   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 294 
 295   // These are macros so that, if the assert fires, we get the correct
 296   // line number, file, etc.
 297 
 298 #define heap_locking_asserts_params(_extra_message_)                          \
 299   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 300   (_extra_message_),                                                          \
 301   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 302   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 303   BOOL_TO_STR(Thread::current()->is_VM_thread())
 304 
 305 #define assert_heap_locked()                                                  \
 306   do {                                                                        \
 307     assert(Heap_lock->owned_by_self(),                                        \
 308            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 309   } while (0)
 310 
 311 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 312   do {                                                                        \
 313     assert(Heap_lock->owned_by_self() ||                                      \
 314            (SafepointSynchronize::is_at_safepoint() &&                        \
 315              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 316            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 317                                         "should be at a safepoint"));         \
 318   } while (0)
 319 
 320 #define assert_heap_locked_and_not_at_safepoint()                             \
 321   do {                                                                        \
 322     assert(Heap_lock->owned_by_self() &&                                      \
 323                                     !SafepointSynchronize::is_at_safepoint(), \
 324           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 325                                        "should not be at a safepoint"));      \
 326   } while (0)
 327 
 328 #define assert_heap_not_locked()                                              \
 329   do {                                                                        \
 330     assert(!Heap_lock->owned_by_self(),                                       \
 331         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 332   } while (0)
 333 
 334 #define assert_heap_not_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 not be holding the Heap_lock and "  \
 339                                    "should not be at a safepoint"));          \
 340   } while (0)
 341 
 342 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 343   do {                                                                        \
 344     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 345               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 346            heap_locking_asserts_params("should be at a safepoint"));          \
 347   } while (0)
 348 
 349 #define assert_not_at_safepoint()                                             \
 350   do {                                                                        \
 351     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 352            heap_locking_asserts_params("should not be at a safepoint"));      \
 353   } while (0)
 354 
 355 protected:
 356 
 357   // The young region list.
 358   YoungList*  _young_list;
 359 
 360   // The current policy object for the collector.
 361   G1CollectorPolicy* _g1_policy;
 362 
 363   // This is the second level of trying to allocate a new region. If
 364   // new_region() didn't find a region on the free_list, this call will
 365   // check whether there's anything available on the
 366   // secondary_free_list and/or wait for more regions to appear on
 367   // that list, if _free_regions_coming is set.
 368   HeapRegion* new_region_try_secondary_free_list(bool is_old);
 369 
 370   // Try to allocate a single non-humongous HeapRegion sufficient for
 371   // an allocation of the given word_size. If do_expand is true,
 372   // attempt to expand the heap if necessary to satisfy the allocation
 373   // request. If the region is to be used as an old region or for a
 374   // humongous object, set is_old to true. If not, to false.
 375   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 376 
 377   // Initialize a contiguous set of free regions of length num_regions
 378   // and starting at index first so that they appear as a single
 379   // humongous region.
 380   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 381                                                       uint num_regions,
 382                                                       size_t word_size,
 383                                                       AllocationContext_t context);
 384 
 385   // Attempt to allocate a humongous object of the given size. Return
 386   // NULL if unsuccessful.
 387   HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
 388 
 389   // The following two methods, allocate_new_tlab() and
 390   // mem_allocate(), are the two main entry points from the runtime
 391   // into the G1's allocation routines. They have the following
 392   // assumptions:
 393   //
 394   // * They should both be called outside safepoints.
 395   //
 396   // * They should both be called without holding the Heap_lock.
 397   //
 398   // * All allocation requests for new TLABs should go to
 399   //   allocate_new_tlab().
 400   //
 401   // * All non-TLAB allocation requests should go to mem_allocate().
 402   //
 403   // * If either call cannot satisfy the allocation request using the
 404   //   current allocating region, they will try to get a new one. If
 405   //   this fails, they will attempt to do an evacuation pause and
 406   //   retry the allocation.
 407   //
 408   // * If all allocation attempts fail, even after trying to schedule
 409   //   an evacuation pause, allocate_new_tlab() will return NULL,
 410   //   whereas mem_allocate() will attempt a heap expansion and/or
 411   //   schedule a Full GC.
 412   //
 413   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 414   //   should never be called with word_size being humongous. All
 415   //   humongous allocation requests should go to mem_allocate() which
 416   //   will satisfy them with a special path.
 417 
 418   virtual HeapWord* allocate_new_tlab(size_t word_size);
 419 
 420   virtual HeapWord* mem_allocate(size_t word_size,
 421                                  bool*  gc_overhead_limit_was_exceeded);
 422 
 423   // The following three methods take a gc_count_before_ret
 424   // parameter which is used to return the GC count if the method
 425   // returns NULL. Given that we are required to read the GC count
 426   // while holding the Heap_lock, and these paths will take the
 427   // Heap_lock at some point, it's easier to get them to read the GC
 428   // count while holding the Heap_lock before they return NULL instead
 429   // of the caller (namely: mem_allocate()) having to also take the
 430   // Heap_lock just to read the GC count.
 431 
 432   // First-level mutator allocation attempt: try to allocate out of
 433   // the mutator alloc region without taking the Heap_lock. This
 434   // should only be used for non-humongous allocations.
 435   inline HeapWord* attempt_allocation(size_t word_size,
 436                                       uint* gc_count_before_ret,
 437                                       uint* gclocker_retry_count_ret);
 438 
 439   // Second-level mutator allocation attempt: take the Heap_lock and
 440   // retry the allocation attempt, potentially scheduling a GC
 441   // pause. This should only be used for non-humongous allocations.
 442   HeapWord* attempt_allocation_slow(size_t word_size,
 443                                     AllocationContext_t context,
 444                                     uint* gc_count_before_ret,
 445                                     uint* gclocker_retry_count_ret);
 446 
 447   // Takes the Heap_lock and attempts a humongous allocation. It can
 448   // potentially schedule a GC pause.
 449   HeapWord* attempt_allocation_humongous(size_t word_size,
 450                                          uint* gc_count_before_ret,
 451                                          uint* gclocker_retry_count_ret);
 452 
 453   // Allocation attempt that should be called during safepoints (e.g.,
 454   // at the end of a successful GC). expect_null_mutator_alloc_region
 455   // specifies whether the mutator alloc region is expected to be NULL
 456   // or not.
 457   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 458                                             AllocationContext_t context,
 459                                             bool expect_null_mutator_alloc_region);
 460 
 461   // These methods are the "callbacks" from the G1AllocRegion class.
 462 
 463   // For mutator alloc regions.
 464   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 465   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 466                                    size_t allocated_bytes);
 467 
 468   // For GC alloc regions.
 469   HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
 470                                   InCSetState dest);
 471   void retire_gc_alloc_region(HeapRegion* alloc_region,
 472                               size_t allocated_bytes, InCSetState dest);
 473 
 474   // - if explicit_gc is true, the GC is for a System.gc() or a heap
 475   //   inspection request and should collect the entire heap
 476   // - if clear_all_soft_refs is true, all soft references should be
 477   //   cleared during the GC
 478   // - if explicit_gc is false, word_size describes the allocation that
 479   //   the GC should attempt (at least) to satisfy
 480   // - it returns false if it is unable to do the collection due to the
 481   //   GC locker being active, true otherwise
 482   bool do_collection(bool explicit_gc,
 483                      bool clear_all_soft_refs,
 484                      size_t word_size);
 485 
 486   // Callback from VM_G1CollectFull operation.
 487   // Perform a full collection.
 488   virtual void do_full_collection(bool clear_all_soft_refs);
 489 
 490   // Resize the heap if necessary after a full collection.  If this is
 491   // after a collect-for allocation, "word_size" is the allocation size,
 492   // and will be considered part of the used portion of the heap.
 493   void resize_if_necessary_after_full_collection(size_t word_size);
 494 
 495   // Callback from VM_G1CollectForAllocation operation.
 496   // This function does everything necessary/possible to satisfy a
 497   // failed allocation request (including collection, expansion, etc.)
 498   HeapWord* satisfy_failed_allocation(size_t word_size,
 499                                       AllocationContext_t context,
 500                                       bool* succeeded);
 501 private:
 502   // Helper method for satisfy_failed_allocation()
 503   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 504                                              AllocationContext_t context,
 505                                              bool do_gc,
 506                                              bool clear_all_soft_refs,
 507                                              bool expect_null_mutator_alloc_region,
 508                                              bool* gc_succeeded);
 509 
 510 protected:
 511   // Attempting to expand the heap sufficiently
 512   // to support an allocation of the given "word_size".  If
 513   // successful, perform the allocation and return the address of the
 514   // allocated block, or else "NULL".
 515   HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
 516 
 517   // Process any reference objects discovered during
 518   // an incremental evacuation pause.
 519   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 520 
 521   // Enqueue any remaining discovered references
 522   // after processing.
 523   void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 524 
 525 public:
 526   WorkGang* workers() const { return _workers; }
 527 
 528   G1Allocator* allocator() {
 529     return _allocator;
 530   }
 531 
 532   G1MonitoringSupport* g1mm() {
 533     assert(_g1mm != NULL, "should have been initialized");
 534     return _g1mm;
 535   }
 536 
 537   // Expand the garbage-first heap by at least the given size (in bytes!).
 538   // Returns true if the heap was expanded by the requested amount;
 539   // false otherwise.
 540   // (Rounds up to a HeapRegion boundary.)
 541   bool expand(size_t expand_bytes, double* expand_time_ms = NULL);
 542 
 543   // Returns the PLAB statistics for a given destination.
 544   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 545 
 546   // Determines PLAB size for a given destination.
 547   inline size_t desired_plab_sz(InCSetState dest);
 548 
 549   inline AllocationContextStats& allocation_context_stats();
 550 
 551   // Do anything common to GC's.
 552   void gc_prologue(bool full);
 553   void gc_epilogue(bool full);
 554 
 555   // Modify the reclaim candidate set and test for presence.
 556   // These are only valid for starts_humongous regions.
 557   inline void set_humongous_reclaim_candidate(uint region, bool value);
 558   inline bool is_humongous_reclaim_candidate(uint region);
 559 
 560   // Remove from the reclaim candidate set.  Also remove from the
 561   // collection set so that later encounters avoid the slow path.
 562   inline void set_humongous_is_live(oop obj);
 563 
 564   // Register the given region to be part of the collection set.
 565   inline void register_humongous_region_with_cset(uint index);
 566   // Register regions with humongous objects (actually on the start region) in
 567   // the in_cset_fast_test table.
 568   void register_humongous_regions_with_cset();
 569   // We register a region with the fast "in collection set" test. We
 570   // simply set to true the array slot corresponding to this region.
 571   void register_young_region_with_cset(HeapRegion* r) {
 572     _in_cset_fast_test.set_in_young(r->hrm_index());
 573   }
 574   void register_old_region_with_cset(HeapRegion* r) {
 575     _in_cset_fast_test.set_in_old(r->hrm_index());
 576   }
 577   void clear_in_cset(const HeapRegion* hr) {
 578     _in_cset_fast_test.clear(hr);
 579   }
 580 
 581   void clear_cset_fast_test() {
 582     _in_cset_fast_test.clear();
 583   }
 584 
 585   // This is called at the start of either a concurrent cycle or a Full
 586   // GC to update the number of old marking cycles started.
 587   void increment_old_marking_cycles_started();
 588 
 589   // This is called at the end of either a concurrent cycle or a Full
 590   // GC to update the number of old marking cycles completed. Those two
 591   // can happen in a nested fashion, i.e., we start a concurrent
 592   // cycle, a Full GC happens half-way through it which ends first,
 593   // and then the cycle notices that a Full GC happened and ends
 594   // too. The concurrent parameter is a boolean to help us do a bit
 595   // tighter consistency checking in the method. If concurrent is
 596   // false, the caller is the inner caller in the nesting (i.e., the
 597   // Full GC). If concurrent is true, the caller is the outer caller
 598   // in this nesting (i.e., the concurrent cycle). Further nesting is
 599   // not currently supported. The end of this call also notifies
 600   // the FullGCCount_lock in case a Java thread is waiting for a full
 601   // GC to happen (e.g., it called System.gc() with
 602   // +ExplicitGCInvokesConcurrent).
 603   void increment_old_marking_cycles_completed(bool concurrent);
 604 
 605   uint old_marking_cycles_completed() {
 606     return _old_marking_cycles_completed;
 607   }
 608 
 609   void register_concurrent_cycle_start(const Ticks& start_time);
 610   void register_concurrent_cycle_end();
 611   void trace_heap_after_concurrent_cycle();
 612 
 613   G1HRPrinter* hr_printer() { return &_hr_printer; }
 614 
 615   // Allocates a new heap region instance.
 616   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 617 
 618   // Allocate the highest free region in the reserved heap. This will commit
 619   // regions as necessary.
 620   HeapRegion* alloc_highest_free_region();
 621 
 622   // Frees a non-humongous region by initializing its contents and
 623   // adding it to the free list that's passed as a parameter (this is
 624   // usually a local list which will be appended to the master free
 625   // list later). The used bytes of freed regions are accumulated in
 626   // pre_used. If par is true, the region's RSet will not be freed
 627   // up. The assumption is that this will be done later.
 628   // The locked parameter indicates if the caller has already taken
 629   // care of proper synchronization. This may allow some optimizations.
 630   void free_region(HeapRegion* hr,
 631                    FreeRegionList* free_list,
 632                    bool par,
 633                    bool locked = false);
 634 
 635   // It dirties the cards that cover the block so that the post
 636   // write barrier never queues anything when updating objects on this
 637   // block. It is assumed (and in fact we assert) that the block
 638   // belongs to a young region.
 639   inline void dirty_young_block(HeapWord* start, size_t word_size);
 640 
 641   // Frees a humongous region by collapsing it into individual regions
 642   // and calling free_region() for each of them. The freed regions
 643   // will be added to the free list that's passed as a parameter (this
 644   // is usually a local list which will be appended to the master free
 645   // list later). The used bytes of freed regions are accumulated in
 646   // pre_used. If par is true, the region's RSet will not be freed
 647   // up. The assumption is that this will be done later.
 648   void free_humongous_region(HeapRegion* hr,
 649                              FreeRegionList* free_list,
 650                              bool par);
 651 
 652   // Facility for allocating in 'archive' regions in high heap memory and
 653   // recording the allocated ranges. These should all be called from the
 654   // VM thread at safepoints, without the heap lock held. They can be used
 655   // to create and archive a set of heap regions which can be mapped at the
 656   // same fixed addresses in a subsequent JVM invocation.
 657   void begin_archive_alloc_range();
 658 
 659   // Check if the requested size would be too large for an archive allocation.
 660   bool is_archive_alloc_too_large(size_t word_size);
 661 
 662   // Allocate memory of the requested size from the archive region. This will
 663   // return NULL if the size is too large or if no memory is available. It
 664   // does not trigger a garbage collection.
 665   HeapWord* archive_mem_allocate(size_t word_size);
 666 
 667   // Optionally aligns the end address and returns the allocated ranges in
 668   // an array of MemRegions in order of ascending addresses.
 669   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 670                                size_t end_alignment_in_bytes = 0);
 671 
 672   // Facility for allocating a fixed range within the heap and marking
 673   // the containing regions as 'archive'. For use at JVM init time, when the
 674   // caller may mmap archived heap data at the specified range(s).
 675   // Verify that the MemRegions specified in the argument array are within the
 676   // reserved heap.
 677   bool check_archive_addresses(MemRegion* range, size_t count);
 678 
 679   // Commit the appropriate G1 regions containing the specified MemRegions
 680   // and mark them as 'archive' regions. The regions in the array must be
 681   // non-overlapping and in order of ascending address.
 682   bool alloc_archive_regions(MemRegion* range, size_t count);
 683 
 684   // Insert any required filler objects in the G1 regions around the specified
 685   // ranges to make the regions parseable. This must be called after
 686   // alloc_archive_regions, and after class loading has occurred.
 687   void fill_archive_regions(MemRegion* range, size_t count);
 688 
 689   // For each of the specified MemRegions, uncommit the containing G1 regions
 690   // which had been allocated by alloc_archive_regions. This should be called
 691   // rather than fill_archive_regions at JVM init time if the archive file
 692   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 693   void dealloc_archive_regions(MemRegion* range, size_t count);
 694 
 695   // Wrapper function of CollectedHeap::fill_with_objects() with setting
 696   // _filler_array_max_size = _humongous_object_threshold_in_words.
 697   static void fill_with_non_humongous_objects(HeapWord* start, size_t words, bool zap = true);
 698 
 699 protected:
 700 
 701   // Shrink the garbage-first heap by at most the given size (in bytes!).
 702   // (Rounds down to a HeapRegion boundary.)
 703   virtual void shrink(size_t expand_bytes);
 704   void shrink_helper(size_t expand_bytes);
 705 
 706   #if TASKQUEUE_STATS
 707   static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
 708   void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
 709   void reset_taskqueue_stats();
 710   #endif // TASKQUEUE_STATS
 711 
 712   // Schedule the VM operation that will do an evacuation pause to
 713   // satisfy an allocation request of word_size. *succeeded will
 714   // return whether the VM operation was successful (it did do an
 715   // evacuation pause) or not (another thread beat us to it or the GC
 716   // locker was active). Given that we should not be holding the
 717   // Heap_lock when we enter this method, we will pass the
 718   // gc_count_before (i.e., total_collections()) as a parameter since
 719   // it has to be read while holding the Heap_lock. Currently, both
 720   // methods that call do_collection_pause() release the Heap_lock
 721   // before the call, so it's easy to read gc_count_before just before.
 722   HeapWord* do_collection_pause(size_t         word_size,
 723                                 uint           gc_count_before,
 724                                 bool*          succeeded,
 725                                 GCCause::Cause gc_cause);
 726 
 727   void wait_for_root_region_scanning();
 728 
 729   // The guts of the incremental collection pause, executed by the vm
 730   // thread. It returns false if it is unable to do the collection due
 731   // to the GC locker being active, true otherwise
 732   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 733 
 734   // Actually do the work of evacuating the collection set.
 735   virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
 736 
 737   void pre_evacuate_collection_set();
 738   void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 739 
 740   // Print the header for the per-thread termination statistics.
 741   static void print_termination_stats_hdr(outputStream* const st);
 742   // Print actual per-thread termination statistics.
 743   void print_termination_stats(outputStream* const st,
 744                                uint worker_id,
 745                                double elapsed_ms,
 746                                double strong_roots_ms,
 747                                double term_ms,
 748                                size_t term_attempts,
 749                                size_t alloc_buffer_waste,
 750                                size_t undo_waste) const;
 751   // Update object copying statistics.
 752   void record_obj_copy_mem_stats();
 753 
 754   // The g1 remembered set of the heap.
 755   G1RemSet* _g1_rem_set;
 756 
 757   // A set of cards that cover the objects for which the Rsets should be updated
 758   // concurrently after the collection.
 759   DirtyCardQueueSet _dirty_card_queue_set;
 760 
 761   // The closure used to refine a single card.
 762   RefineCardTableEntryClosure* _refine_cte_cl;
 763 
 764   // A DirtyCardQueueSet that is used to hold cards that contain
 765   // references into the current collection set. This is used to
 766   // update the remembered sets of the regions in the collection
 767   // set in the event of an evacuation failure.
 768   DirtyCardQueueSet _into_cset_dirty_card_queue_set;
 769 
 770   // After a collection pause, make the regions in the CS into free
 771   // regions.
 772   void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 773 
 774   // Abandon the current collection set without recording policy
 775   // statistics or updating free lists.
 776   void abandon_collection_set(HeapRegion* cs_head);
 777 
 778   // The concurrent marker (and the thread it runs in.)
 779   ConcurrentMark* _cm;
 780   ConcurrentMarkThread* _cmThread;
 781 
 782   // The concurrent refiner.
 783   ConcurrentG1Refine* _cg1r;
 784 
 785   // The parallel task queues
 786   RefToScanQueueSet *_task_queues;
 787 
 788   // True iff a evacuation has failed in the current collection.
 789   bool _evacuation_failed;
 790 
 791   EvacuationFailedInfo* _evacuation_failed_info_array;
 792 
 793   // Failed evacuations cause some logical from-space objects to have
 794   // forwarding pointers to themselves.  Reset them.
 795   void remove_self_forwarding_pointers();
 796 
 797   struct OopAndMarkOop {
 798    private:
 799     oop _o;
 800     markOop _m;
 801    public:
 802     OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) {
 803     }
 804 
 805     void set_mark() {
 806       _o->set_mark(_m);
 807     }
 808   };
 809 
 810   typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack;
 811   // Stores marks with the corresponding oop that we need to preserve during evacuation
 812   // failure.
 813   OopAndMarkOopStack*  _preserved_objs;
 814 
 815   // Preserve the mark of "obj", if necessary, in preparation for its mark
 816   // word being overwritten with a self-forwarding-pointer.
 817   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 818 
 819 #ifndef PRODUCT
 820   // Support for forcing evacuation failures. Analogous to
 821   // PromotionFailureALot for the other collectors.
 822 
 823   // Records whether G1EvacuationFailureALot should be in effect
 824   // for the current GC
 825   bool _evacuation_failure_alot_for_current_gc;
 826 
 827   // Used to record the GC number for interval checking when
 828   // determining whether G1EvaucationFailureALot is in effect
 829   // for the current GC.
 830   size_t _evacuation_failure_alot_gc_number;
 831 
 832   // Count of the number of evacuations between failures.
 833   volatile size_t _evacuation_failure_alot_count;
 834 
 835   // Set whether G1EvacuationFailureALot should be in effect
 836   // for the current GC (based upon the type of GC and which
 837   // command line flags are set);
 838   inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
 839                                                   bool during_initial_mark,
 840                                                   bool during_marking);
 841 
 842   inline void set_evacuation_failure_alot_for_current_gc();
 843 
 844   // Return true if it's time to cause an evacuation failure.
 845   inline bool evacuation_should_fail();
 846 
 847   // Reset the G1EvacuationFailureALot counters.  Should be called at
 848   // the end of an evacuation pause in which an evacuation failure occurred.
 849   inline void reset_evacuation_should_fail();
 850 #endif // !PRODUCT
 851 
 852   // ("Weak") Reference processing support.
 853   //
 854   // G1 has 2 instances of the reference processor class. One
 855   // (_ref_processor_cm) handles reference object discovery
 856   // and subsequent processing during concurrent marking cycles.
 857   //
 858   // The other (_ref_processor_stw) handles reference object
 859   // discovery and processing during full GCs and incremental
 860   // evacuation pauses.
 861   //
 862   // During an incremental pause, reference discovery will be
 863   // temporarily disabled for _ref_processor_cm and will be
 864   // enabled for _ref_processor_stw. At the end of the evacuation
 865   // pause references discovered by _ref_processor_stw will be
 866   // processed and discovery will be disabled. The previous
 867   // setting for reference object discovery for _ref_processor_cm
 868   // will be re-instated.
 869   //
 870   // At the start of marking:
 871   //  * Discovery by the CM ref processor is verified to be inactive
 872   //    and it's discovered lists are empty.
 873   //  * Discovery by the CM ref processor is then enabled.
 874   //
 875   // At the end of marking:
 876   //  * Any references on the CM ref processor's discovered
 877   //    lists are processed (possibly MT).
 878   //
 879   // At the start of full GC we:
 880   //  * Disable discovery by the CM ref processor and
 881   //    empty CM ref processor's discovered lists
 882   //    (without processing any entries).
 883   //  * Verify that the STW ref processor is inactive and it's
 884   //    discovered lists are empty.
 885   //  * Temporarily set STW ref processor discovery as single threaded.
 886   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 887   //    field.
 888   //  * Finally enable discovery by the STW ref processor.
 889   //
 890   // The STW ref processor is used to record any discovered
 891   // references during the full GC.
 892   //
 893   // At the end of a full GC we:
 894   //  * Enqueue any reference objects discovered by the STW ref processor
 895   //    that have non-live referents. This has the side-effect of
 896   //    making the STW ref processor inactive by disabling discovery.
 897   //  * Verify that the CM ref processor is still inactive
 898   //    and no references have been placed on it's discovered
 899   //    lists (also checked as a precondition during initial marking).
 900 
 901   // The (stw) reference processor...
 902   ReferenceProcessor* _ref_processor_stw;
 903 
 904   STWGCTimer* _gc_timer_stw;
 905   ConcurrentGCTimer* _gc_timer_cm;
 906 
 907   G1OldTracer* _gc_tracer_cm;
 908   G1NewTracer* _gc_tracer_stw;
 909 
 910   // During reference object discovery, the _is_alive_non_header
 911   // closure (if non-null) is applied to the referent object to
 912   // determine whether the referent is live. If so then the
 913   // reference object does not need to be 'discovered' and can
 914   // be treated as a regular oop. This has the benefit of reducing
 915   // the number of 'discovered' reference objects that need to
 916   // be processed.
 917   //
 918   // Instance of the is_alive closure for embedding into the
 919   // STW reference processor as the _is_alive_non_header field.
 920   // Supplying a value for the _is_alive_non_header field is
 921   // optional but doing so prevents unnecessary additions to
 922   // the discovered lists during reference discovery.
 923   G1STWIsAliveClosure _is_alive_closure_stw;
 924 
 925   // The (concurrent marking) reference processor...
 926   ReferenceProcessor* _ref_processor_cm;
 927 
 928   // Instance of the concurrent mark is_alive closure for embedding
 929   // into the Concurrent Marking reference processor as the
 930   // _is_alive_non_header field. Supplying a value for the
 931   // _is_alive_non_header field is optional but doing so prevents
 932   // unnecessary additions to the discovered lists during reference
 933   // discovery.
 934   G1CMIsAliveClosure _is_alive_closure_cm;
 935 
 936   // Cache used by G1CollectedHeap::start_cset_region_for_worker().
 937   HeapRegion** _worker_cset_start_region;
 938 
 939   // Time stamp to validate the regions recorded in the cache
 940   // used by G1CollectedHeap::start_cset_region_for_worker().
 941   // The heap region entry for a given worker is valid iff
 942   // the associated time stamp value matches the current value
 943   // of G1CollectedHeap::_gc_time_stamp.
 944   uint* _worker_cset_start_region_time_stamp;
 945 
 946   volatile bool _free_regions_coming;
 947 
 948 public:
 949 
 950   void set_refine_cte_cl_concurrency(bool concurrent);
 951 
 952   RefToScanQueue *task_queue(uint i) const;
 953 
 954   uint num_task_queues() const;
 955 
 956   // A set of cards where updates happened during the GC
 957   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 958 
 959   // A DirtyCardQueueSet that is used to hold cards that contain
 960   // references into the current collection set. This is used to
 961   // update the remembered sets of the regions in the collection
 962   // set in the event of an evacuation failure.
 963   DirtyCardQueueSet& into_cset_dirty_card_queue_set()
 964         { return _into_cset_dirty_card_queue_set; }
 965 
 966   // Create a G1CollectedHeap with the specified policy.
 967   // Must call the initialize method afterwards.
 968   // May not return if something goes wrong.
 969   G1CollectedHeap(G1CollectorPolicy* policy);
 970 
 971   // Initialize the G1CollectedHeap to have the initial and
 972   // maximum sizes and remembered and barrier sets
 973   // specified by the policy object.
 974   jint initialize();
 975 
 976   virtual void stop();
 977 
 978   // Return the (conservative) maximum heap alignment for any G1 heap
 979   static size_t conservative_max_heap_alignment();
 980 
 981   // Does operations required after initialization has been done.
 982   void post_initialize();
 983 
 984   // Initialize weak reference processing.
 985   void ref_processing_init();
 986 
 987   virtual Name kind() const {
 988     return CollectedHeap::G1CollectedHeap;
 989   }
 990 
 991   const G1CollectorState* collector_state() const { return &_collector_state; }
 992   G1CollectorState* collector_state() { return &_collector_state; }
 993 
 994   // The current policy object for the collector.
 995   G1CollectorPolicy* g1_policy() const { return _g1_policy; }
 996 
 997   virtual CollectorPolicy* collector_policy() const;
 998 
 999   // Adaptive size policy.  No such thing for g1.
1000   virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1001 
1002   // The rem set and barrier set.
1003   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1004 
1005   unsigned get_gc_time_stamp() {
1006     return _gc_time_stamp;
1007   }
1008 
1009   inline void reset_gc_time_stamp();
1010 
1011   void check_gc_time_stamps() PRODUCT_RETURN;
1012 
1013   inline void increment_gc_time_stamp();
1014 
1015   // Reset the given region's GC timestamp. If it's starts humongous,
1016   // also reset the GC timestamp of its corresponding
1017   // continues humongous regions too.
1018   void reset_gc_time_stamps(HeapRegion* hr);
1019 
1020   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1021   void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1022 
1023   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1024   void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1025 
1026   // The shared block offset table array.
1027   G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1028 
1029   // Reference Processing accessors
1030 
1031   // The STW reference processor....
1032   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1033 
1034   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1035 
1036   // The Concurrent Marking reference processor...
1037   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1038 
1039   ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1040   G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1041 
1042   virtual size_t capacity() const;
1043   virtual size_t used() const;
1044   // This should be called when we're not holding the heap lock. The
1045   // result might be a bit inaccurate.
1046   size_t used_unlocked() const;
1047   size_t recalculate_used() const;
1048 
1049   // These virtual functions do the actual allocation.
1050   // Some heaps may offer a contiguous region for shared non-blocking
1051   // allocation, via inlined code (by exporting the address of the top and
1052   // end fields defining the extent of the contiguous allocation region.)
1053   // But G1CollectedHeap doesn't yet support this.
1054 
1055   virtual bool is_maximal_no_gc() const {
1056     return _hrm.available() == 0;
1057   }
1058 
1059   // The current number of regions in the heap.
1060   uint num_regions() const { return _hrm.length(); }
1061 
1062   // The max number of regions in the heap.
1063   uint max_regions() const { return _hrm.max_length(); }
1064 
1065   // The number of regions that are completely free.
1066   uint num_free_regions() const { return _hrm.num_free_regions(); }
1067 
1068   MemoryUsage get_auxiliary_data_memory_usage() const {
1069     return _hrm.get_auxiliary_data_memory_usage();
1070   }
1071 
1072   // The number of regions that are not completely free.
1073   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1074 
1075   void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1076   void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1077   void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1078   void verify_dirty_young_regions() PRODUCT_RETURN;
1079 
1080 #ifndef PRODUCT
1081   // Make sure that the given bitmap has no marked objects in the
1082   // range [from,limit). If it does, print an error message and return
1083   // false. Otherwise, just return true. bitmap_name should be "prev"
1084   // or "next".
1085   bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1086                                 HeapWord* from, HeapWord* limit);
1087 
1088   // Verify that the prev / next bitmap range [tams,end) for the given
1089   // region has no marks. Return true if all is well, false if errors
1090   // are detected.
1091   bool verify_bitmaps(const char* caller, HeapRegion* hr);
1092 #endif // PRODUCT
1093 
1094   // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1095   // the given region do not have any spurious marks. If errors are
1096   // detected, print appropriate error messages and crash.
1097   void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1098 
1099   // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1100   // have any spurious marks. If errors are detected, print
1101   // appropriate error messages and crash.
1102   void check_bitmaps(const char* caller) PRODUCT_RETURN;
1103 
1104   // Do sanity check on the contents of the in-cset fast test table.
1105   bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1106 
1107   // verify_region_sets() performs verification over the region
1108   // lists. It will be compiled in the product code to be used when
1109   // necessary (i.e., during heap verification).
1110   void verify_region_sets();
1111 
1112   // verify_region_sets_optional() is planted in the code for
1113   // list verification in non-product builds (and it can be enabled in
1114   // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1115 #if HEAP_REGION_SET_FORCE_VERIFY
1116   void verify_region_sets_optional() {
1117     verify_region_sets();
1118   }
1119 #else // HEAP_REGION_SET_FORCE_VERIFY
1120   void verify_region_sets_optional() { }
1121 #endif // HEAP_REGION_SET_FORCE_VERIFY
1122 
1123 #ifdef ASSERT
1124   bool is_on_master_free_list(HeapRegion* hr) {
1125     return _hrm.is_free(hr);
1126   }
1127 #endif // ASSERT
1128 
1129   // Wrapper for the region list operations that can be called from
1130   // methods outside this class.
1131 
1132   void secondary_free_list_add(FreeRegionList* list) {
1133     _secondary_free_list.add_ordered(list);
1134   }
1135 
1136   void append_secondary_free_list() {
1137     _hrm.insert_list_into_free_list(&_secondary_free_list);
1138   }
1139 
1140   void append_secondary_free_list_if_not_empty_with_lock() {
1141     // If the secondary free list looks empty there's no reason to
1142     // take the lock and then try to append it.
1143     if (!_secondary_free_list.is_empty()) {
1144       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1145       append_secondary_free_list();
1146     }
1147   }
1148 
1149   inline void old_set_add(HeapRegion* hr);
1150   inline void old_set_remove(HeapRegion* hr);
1151 
1152   size_t non_young_capacity_bytes() {
1153     return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1154   }
1155 
1156   void set_free_regions_coming();
1157   void reset_free_regions_coming();
1158   bool free_regions_coming() { return _free_regions_coming; }
1159   void wait_while_free_regions_coming();
1160 
1161   // Determine whether the given region is one that we are using as an
1162   // old GC alloc region.
1163   bool is_old_gc_alloc_region(HeapRegion* hr);
1164 
1165   // Perform a collection of the heap; intended for use in implementing
1166   // "System.gc".  This probably implies as full a collection as the
1167   // "CollectedHeap" supports.
1168   virtual void collect(GCCause::Cause cause);
1169 
1170   // The same as above but assume that the caller holds the Heap_lock.
1171   void collect_locked(GCCause::Cause cause);
1172 
1173   virtual bool copy_allocation_context_stats(const jint* contexts,
1174                                              jlong* totals,
1175                                              jbyte* accuracy,
1176                                              jint len);
1177 
1178   // True iff an evacuation has failed in the most-recent collection.
1179   bool evacuation_failed() { return _evacuation_failed; }
1180 
1181   void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1182   void prepend_to_freelist(FreeRegionList* list);
1183   void decrement_summary_bytes(size_t bytes);
1184 
1185   // Returns "TRUE" iff "p" points into the committed areas of the heap.
1186   virtual bool is_in(const void* p) const;
1187 #ifdef ASSERT
1188   // Returns whether p is in one of the available areas of the heap. Slow but
1189   // extensive version.
1190   bool is_in_exact(const void* p) const;
1191 #endif
1192 
1193   // Return "TRUE" iff the given object address is within the collection
1194   // set. Slow implementation.
1195   bool obj_in_cs(oop obj);
1196 
1197   inline bool is_in_cset(const HeapRegion *hr);
1198   inline bool is_in_cset(oop obj);
1199 
1200   inline bool is_in_cset_or_humongous(const oop obj);
1201 
1202  private:
1203   // This array is used for a quick test on whether a reference points into
1204   // the collection set or not. Each of the array's elements denotes whether the
1205   // corresponding region is in the collection set or not.
1206   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1207 
1208  public:
1209 
1210   inline InCSetState in_cset_state(const oop obj);
1211 
1212   // Return "TRUE" iff the given object address is in the reserved
1213   // region of g1.
1214   bool is_in_g1_reserved(const void* p) const {
1215     return _hrm.reserved().contains(p);
1216   }
1217 
1218   // Returns a MemRegion that corresponds to the space that has been
1219   // reserved for the heap
1220   MemRegion g1_reserved() const {
1221     return _hrm.reserved();
1222   }
1223 
1224   virtual bool is_in_closed_subset(const void* p) const;
1225 
1226   G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1227     return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1228   }
1229 
1230   // This resets the card table to all zeros.  It is used after
1231   // a collection pause which used the card table to claim cards.
1232   void cleanUpCardTable();
1233 
1234   // Iteration functions.
1235 
1236   // Iterate over all objects, calling "cl.do_object" on each.
1237   virtual void object_iterate(ObjectClosure* cl);
1238 
1239   virtual void safe_object_iterate(ObjectClosure* cl) {
1240     object_iterate(cl);
1241   }
1242 
1243   // Iterate over heap regions, in address order, terminating the
1244   // iteration early if the "doHeapRegion" method returns "true".
1245   void heap_region_iterate(HeapRegionClosure* blk) const;
1246 
1247   // Return the region with the given index. It assumes the index is valid.
1248   inline HeapRegion* region_at(uint index) const;
1249 
1250   // Calculate the region index of the given address. Given address must be
1251   // within the heap.
1252   inline uint addr_to_region(HeapWord* addr) const;
1253 
1254   inline HeapWord* bottom_addr_for_region(uint index) const;
1255 
1256   // Iterate over the heap regions in parallel. Assumes that this will be called
1257   // in parallel by ParallelGCThreads worker threads with distinct worker ids
1258   // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1259   // to each of the regions, by attempting to claim the region using the
1260   // HeapRegionClaimer and, if successful, applying the closure to the claimed
1261   // region. The concurrent argument should be set to true if iteration is
1262   // performed concurrently, during which no assumptions are made for consistent
1263   // attributes of the heap regions (as they might be modified while iterating).
1264   void heap_region_par_iterate(HeapRegionClosure* cl,
1265                                uint worker_id,
1266                                HeapRegionClaimer* hrclaimer,
1267                                bool concurrent = false) const;
1268 
1269   // Clear the cached cset start regions and (more importantly)
1270   // the time stamps. Called when we reset the GC time stamp.
1271   void clear_cset_start_regions();
1272 
1273   // Given the id of a worker, obtain or calculate a suitable
1274   // starting region for iterating over the current collection set.
1275   HeapRegion* start_cset_region_for_worker(uint worker_i);
1276 
1277   // Iterate over the regions (if any) in the current collection set.
1278   void collection_set_iterate(HeapRegionClosure* blk);
1279 
1280   // As above but starting from region r
1281   void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1282 
1283   HeapRegion* next_compaction_region(const HeapRegion* from) const;
1284 
1285   // Returns the HeapRegion that contains addr. addr must not be NULL.
1286   template <class T>
1287   inline HeapRegion* heap_region_containing_raw(const T addr) const;
1288 
1289   // Returns the HeapRegion that contains addr. addr must not be NULL.
1290   // If addr is within a humongous continues region, it returns its humongous start region.
1291   template <class T>
1292   inline HeapRegion* heap_region_containing(const T addr) const;
1293 
1294   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1295   // each address in the (reserved) heap is a member of exactly
1296   // one block.  The defining characteristic of a block is that it is
1297   // possible to find its size, and thus to progress forward to the next
1298   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1299   // represent Java objects, or they might be free blocks in a
1300   // free-list-based heap (or subheap), as long as the two kinds are
1301   // distinguishable and the size of each is determinable.
1302 
1303   // Returns the address of the start of the "block" that contains the
1304   // address "addr".  We say "blocks" instead of "object" since some heaps
1305   // may not pack objects densely; a chunk may either be an object or a
1306   // non-object.
1307   virtual HeapWord* block_start(const void* addr) const;
1308 
1309   // Requires "addr" to be the start of a chunk, and returns its size.
1310   // "addr + size" is required to be the start of a new chunk, or the end
1311   // of the active area of the heap.
1312   virtual size_t block_size(const HeapWord* addr) const;
1313 
1314   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1315   // the block is an object.
1316   virtual bool block_is_obj(const HeapWord* addr) const;
1317 
1318   // Section on thread-local allocation buffers (TLABs)
1319   // See CollectedHeap for semantics.
1320 
1321   bool supports_tlab_allocation() const;
1322   size_t tlab_capacity(Thread* ignored) const;
1323   size_t tlab_used(Thread* ignored) const;
1324   size_t max_tlab_size() const;
1325   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1326 
1327   // Can a compiler initialize a new object without store barriers?
1328   // This permission only extends from the creation of a new object
1329   // via a TLAB up to the first subsequent safepoint. If such permission
1330   // is granted for this heap type, the compiler promises to call
1331   // defer_store_barrier() below on any slow path allocation of
1332   // a new object for which such initializing store barriers will
1333   // have been elided. G1, like CMS, allows this, but should be
1334   // ready to provide a compensating write barrier as necessary
1335   // if that storage came out of a non-young region. The efficiency
1336   // of this implementation depends crucially on being able to
1337   // answer very efficiently in constant time whether a piece of
1338   // storage in the heap comes from a young region or not.
1339   // See ReduceInitialCardMarks.
1340   virtual bool can_elide_tlab_store_barriers() const {
1341     return true;
1342   }
1343 
1344   virtual bool card_mark_must_follow_store() const {
1345     return true;
1346   }
1347 
1348   inline bool is_in_young(const oop obj);
1349 
1350   virtual bool is_scavengable(const void* addr);
1351 
1352   // We don't need barriers for initializing stores to objects
1353   // in the young gen: for the SATB pre-barrier, there is no
1354   // pre-value that needs to be remembered; for the remembered-set
1355   // update logging post-barrier, we don't maintain remembered set
1356   // information for young gen objects.
1357   virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1358 
1359   // Returns "true" iff the given word_size is "very large".
1360   static bool is_humongous(size_t word_size) {
1361     // Note this has to be strictly greater-than as the TLABs
1362     // are capped at the humongous threshold and we want to
1363     // ensure that we don't try to allocate a TLAB as
1364     // humongous and that we don't allocate a humongous
1365     // object in a TLAB.
1366     return word_size > _humongous_object_threshold_in_words;
1367   }
1368 
1369   // Returns the humongous threshold for a specific region size
1370   static size_t humongous_threshold_for(size_t region_size) {
1371     return (region_size / 2);
1372   }
1373 
1374   // Update mod union table with the set of dirty cards.
1375   void updateModUnion();
1376 
1377   // Set the mod union bits corresponding to the given memRegion.  Note
1378   // that this is always a safe operation, since it doesn't clear any
1379   // bits.
1380   void markModUnionRange(MemRegion mr);
1381 
1382   // Print the maximum heap capacity.
1383   virtual size_t max_capacity() const;
1384 
1385   virtual jlong millis_since_last_gc();
1386 
1387 
1388   // Convenience function to be used in situations where the heap type can be
1389   // asserted to be this type.
1390   static G1CollectedHeap* heap();
1391 
1392   void set_region_short_lived_locked(HeapRegion* hr);
1393   // add appropriate methods for any other surv rate groups
1394 
1395   YoungList* young_list() const { return _young_list; }
1396 
1397   // debugging
1398   bool check_young_list_well_formed() {
1399     return _young_list->check_list_well_formed();
1400   }
1401 
1402   bool check_young_list_empty(bool check_heap,
1403                               bool check_sample = true);
1404 
1405   // *** Stuff related to concurrent marking.  It's not clear to me that so
1406   // many of these need to be public.
1407 
1408   // The functions below are helper functions that a subclass of
1409   // "CollectedHeap" can use in the implementation of its virtual
1410   // functions.
1411   // This performs a concurrent marking of the live objects in a
1412   // bitmap off to the side.
1413   void doConcurrentMark();
1414 
1415   bool isMarkedPrev(oop obj) const;
1416   bool isMarkedNext(oop obj) const;
1417 
1418   // Determine if an object is dead, given the object and also
1419   // the region to which the object belongs. An object is dead
1420   // iff a) it was not allocated since the last mark, b) it
1421   // is not marked, and c) it is not in an archive region.
1422   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1423     return
1424       !hr->obj_allocated_since_prev_marking(obj) &&
1425       !isMarkedPrev(obj) &&
1426       !hr->is_archive();
1427   }
1428 
1429   // This function returns true when an object has been
1430   // around since the previous marking and hasn't yet
1431   // been marked during this marking, and is not in an archive region.
1432   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1433     return
1434       !hr->obj_allocated_since_next_marking(obj) &&
1435       !isMarkedNext(obj) &&
1436       !hr->is_archive();
1437   }
1438 
1439   // Determine if an object is dead, given only the object itself.
1440   // This will find the region to which the object belongs and
1441   // then call the region version of the same function.
1442 
1443   // Added if it is NULL it isn't dead.
1444 
1445   inline bool is_obj_dead(const oop obj) const;
1446 
1447   inline bool is_obj_ill(const oop obj) const;
1448 
1449   bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1450   HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1451   bool is_marked(oop obj, VerifyOption vo);
1452   const char* top_at_mark_start_str(VerifyOption vo);
1453 
1454   ConcurrentMark* concurrent_mark() const { return _cm; }
1455 
1456   // Refinement
1457 
1458   ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1459 
1460   // The dirty cards region list is used to record a subset of regions
1461   // whose cards need clearing. The list if populated during the
1462   // remembered set scanning and drained during the card table
1463   // cleanup. Although the methods are reentrant, population/draining
1464   // phases must not overlap. For synchronization purposes the last
1465   // element on the list points to itself.
1466   HeapRegion* _dirty_cards_region_list;
1467   void push_dirty_cards_region(HeapRegion* hr);
1468   HeapRegion* pop_dirty_cards_region();
1469 
1470   // Optimized nmethod scanning support routines
1471 
1472   // Register the given nmethod with the G1 heap.
1473   virtual void register_nmethod(nmethod* nm);
1474 
1475   // Unregister the given nmethod from the G1 heap.
1476   virtual void unregister_nmethod(nmethod* nm);
1477 
1478   // Free up superfluous code root memory.
1479   void purge_code_root_memory();
1480 
1481   // Rebuild the strong code root lists for each region
1482   // after a full GC.
1483   void rebuild_strong_code_roots();
1484 
1485   // Delete entries for dead interned string and clean up unreferenced symbols
1486   // in symbol table, possibly in parallel.
1487   void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1488 
1489   // Parallel phase of unloading/cleaning after G1 concurrent mark.
1490   void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1491 
1492   // Redirty logged cards in the refinement queue.
1493   void redirty_logged_cards();
1494   // Verification
1495 
1496   // Perform any cleanup actions necessary before allowing a verification.
1497   virtual void prepare_for_verify();
1498 
1499   // Perform verification.
1500 
1501   // vo == UsePrevMarking  -> use "prev" marking information,
1502   // vo == UseNextMarking -> use "next" marking information
1503   // vo == UseMarkWord    -> use the mark word in the object header
1504   //
1505   // NOTE: Only the "prev" marking information is guaranteed to be
1506   // consistent most of the time, so most calls to this should use
1507   // vo == UsePrevMarking.
1508   // Currently, there is only one case where this is called with
1509   // vo == UseNextMarking, which is to verify the "next" marking
1510   // information at the end of remark.
1511   // Currently there is only one place where this is called with
1512   // vo == UseMarkWord, which is to verify the marking during a
1513   // full GC.
1514   void verify(bool silent, VerifyOption vo);
1515 
1516   // Override; it uses the "prev" marking information
1517   virtual void verify(bool silent);
1518 
1519   // The methods below are here for convenience and dispatch the
1520   // appropriate method depending on value of the given VerifyOption
1521   // parameter. The values for that parameter, and their meanings,
1522   // are the same as those above.
1523 
1524   bool is_obj_dead_cond(const oop obj,
1525                         const HeapRegion* hr,
1526                         const VerifyOption vo) const;
1527 
1528   bool is_obj_dead_cond(const oop obj,
1529                         const VerifyOption vo) const;
1530 
1531   G1HeapSummary create_g1_heap_summary();
1532   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1533 
1534   // Printing
1535 
1536   virtual void print_on(outputStream* st) const;
1537   virtual void print_extended_on(outputStream* st) const;
1538   virtual void print_on_error(outputStream* st) const;
1539 
1540   virtual void print_gc_threads_on(outputStream* st) const;
1541   virtual void gc_threads_do(ThreadClosure* tc) const;
1542 
1543   // Override
1544   void print_tracing_info() const;
1545 
1546   // The following two methods are helpful for debugging RSet issues.
1547   void print_cset_rsets() PRODUCT_RETURN;
1548   void print_all_rsets() PRODUCT_RETURN;
1549 
1550 public:
1551   size_t pending_card_num();
1552 
1553 protected:
1554   size_t _max_heap_capacity;
1555 };
1556 
1557 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP