rev 12505 : imported patch g1_whitebox
rev 12506 : [mq]: list_phases

   1 /*
   2  * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  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).
  14  *
  15  * You should have received a copy of the GNU General Public License version
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
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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 G1HeapVerifier;
  91 class G1HeapSizingPolicy;
  92 
  93 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
  94 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
  95 
  96 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
  97 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
  98 
  99 // The G1 STW is alive closure.
 100 // An instance is embedded into the G1CH and used as the
 101 // (optional) _is_alive_non_header closure in the STW
 102 // reference processor. It is also extensively used during
 103 // reference processing during STW evacuation pauses.
 104 class G1STWIsAliveClosure: public BoolObjectClosure {
 105   G1CollectedHeap* _g1;
 106 public:
 107   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 108   bool do_object_b(oop p);
 109 };
 110 
 111 class RefineCardTableEntryClosure;
 112 
 113 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 114  private:
 115   void reset_from_card_cache(uint start_idx, size_t num_regions);
 116  public:
 117   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 118 };
 119 
 120 class G1CollectedHeap : public CollectedHeap {
 121   friend class G1FreeCollectionSetTask;
 122   friend class VM_CollectForMetadataAllocation;
 123   friend class VM_G1CollectForAllocation;
 124   friend class VM_G1CollectFull;
 125   friend class VM_G1IncCollectionPause;
 126   friend class VMStructs;
 127   friend class MutatorAllocRegion;
 128   friend class G1GCAllocRegion;
 129   friend class G1HeapVerifier;
 130 
 131   // Closures used in implementation.
 132   friend class G1ParScanThreadState;
 133   friend class G1ParScanThreadStateSet;
 134   friend class G1ParTask;
 135   friend class G1PLABAllocator;
 136   friend class G1PrepareCompactClosure;
 137 
 138   // Other related classes.
 139   friend class HeapRegionClaimer;
 140 
 141   // Testing classes.
 142   friend class G1CheckCSetFastTableClosure;
 143 
 144 private:
 145   WorkGang* _workers;
 146   G1CollectorPolicy* _collector_policy;
 147 
 148   static size_t _humongous_object_threshold_in_words;
 149 
 150   // The secondary free list which contains regions that have been
 151   // freed up during the cleanup process. This will be appended to
 152   // the master free list when appropriate.
 153   FreeRegionList _secondary_free_list;
 154 
 155   // It keeps track of the old regions.
 156   HeapRegionSet _old_set;
 157 
 158   // It keeps track of the humongous regions.
 159   HeapRegionSet _humongous_set;
 160 
 161   void eagerly_reclaim_humongous_regions();
 162 
 163   // The number of regions we could create by expansion.
 164   uint _expansion_regions;
 165 
 166   // The block offset table for the G1 heap.
 167   G1BlockOffsetTable* _bot;
 168 
 169   // Tears down the region sets / lists so that they are empty and the
 170   // regions on the heap do not belong to a region set / list. The
 171   // only exception is the humongous set which we leave unaltered. If
 172   // free_list_only is true, it will only tear down the master free
 173   // list. It is called before a Full GC (free_list_only == false) or
 174   // before heap shrinking (free_list_only == true).
 175   void tear_down_region_sets(bool free_list_only);
 176 
 177   // Rebuilds the region sets / lists so that they are repopulated to
 178   // reflect the contents of the heap. The only exception is the
 179   // humongous set which was not torn down in the first place. If
 180   // free_list_only is true, it will only rebuild the master free
 181   // list. It is called after a Full GC (free_list_only == false) or
 182   // after heap shrinking (free_list_only == true).
 183   void rebuild_region_sets(bool free_list_only);
 184 
 185   // Callback for region mapping changed events.
 186   G1RegionMappingChangedListener _listener;
 187 
 188   // The sequence of all heap regions in the heap.
 189   HeapRegionManager _hrm;
 190 
 191   // Manages all allocations with regions except humongous object allocations.
 192   G1Allocator* _allocator;
 193 
 194   // Manages all heap verification.
 195   G1HeapVerifier* _verifier;
 196 
 197   // Outside of GC pauses, the number of bytes used in all regions other
 198   // than the current allocation region(s).
 199   size_t _summary_bytes_used;
 200 
 201   void increase_used(size_t bytes);
 202   void decrease_used(size_t bytes);
 203 
 204   void set_used(size_t bytes);
 205 
 206   // Class that handles archive allocation ranges.
 207   G1ArchiveAllocator* _archive_allocator;
 208 
 209   // Statistics for each allocation context
 210   AllocationContextStats _allocation_context_stats;
 211 
 212   // GC allocation statistics policy for survivors.
 213   G1EvacStats _survivor_evac_stats;
 214 
 215   // GC allocation statistics policy for tenured objects.
 216   G1EvacStats _old_evac_stats;
 217 
 218   // It specifies whether we should attempt to expand the heap after a
 219   // region allocation failure. If heap expansion fails we set this to
 220   // false so that we don't re-attempt the heap expansion (it's likely
 221   // that subsequent expansion attempts will also fail if one fails).
 222   // Currently, it is only consulted during GC and it's reset at the
 223   // start of each GC.
 224   bool _expand_heap_after_alloc_failure;
 225 
 226   // Helper for monitoring and management support.
 227   G1MonitoringSupport* _g1mm;
 228 
 229   // Records whether the region at the given index is (still) a
 230   // candidate for eager reclaim.  Only valid for humongous start
 231   // regions; other regions have unspecified values.  Humongous start
 232   // regions are initialized at start of collection pause, with
 233   // candidates removed from the set as they are found reachable from
 234   // roots or the young generation.
 235   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 236    protected:
 237     bool default_value() const { return false; }
 238    public:
 239     void clear() { G1BiasedMappedArray<bool>::clear(); }
 240     void set_candidate(uint region, bool value) {
 241       set_by_index(region, value);
 242     }
 243     bool is_candidate(uint region) {
 244       return get_by_index(region);
 245     }
 246   };
 247 
 248   HumongousReclaimCandidates _humongous_reclaim_candidates;
 249   // Stores whether during humongous object registration we found candidate regions.
 250   // If not, we can skip a few steps.
 251   bool _has_humongous_reclaim_candidates;
 252 
 253   volatile uint _gc_time_stamp;
 254 
 255   G1HRPrinter _hr_printer;
 256 
 257   // It decides whether an explicit GC should start a concurrent cycle
 258   // instead of doing a STW GC. Currently, a concurrent cycle is
 259   // explicitly started if:
 260   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 261   // (b) cause == _g1_humongous_allocation
 262   // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 263   // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 264   // (e) cause == _update_allocation_context_stats_inc
 265   // (f) cause == _wb_conc_mark
 266   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 267 
 268   // indicates whether we are in young or mixed GC mode
 269   G1CollectorState _collector_state;
 270 
 271   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 272   // concurrent cycles) we have started.
 273   volatile uint _old_marking_cycles_started;
 274 
 275   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 276   // concurrent cycles) we have completed.
 277   volatile uint _old_marking_cycles_completed;
 278 
 279   // This is a non-product method that is helpful for testing. It is
 280   // called at the end of a GC and artificially expands the heap by
 281   // allocating a number of dead regions. This way we can induce very
 282   // frequent marking cycles and stress the cleanup / concurrent
 283   // cleanup code more (as all the regions that will be allocated by
 284   // this method will be found dead by the marking cycle).
 285   void allocate_dummy_regions() PRODUCT_RETURN;
 286 
 287   // Clear RSets after a compaction. It also resets the GC time stamps.
 288   void clear_rsets_post_compaction();
 289 
 290   // If the HR printer is active, dump the state of the regions in the
 291   // heap after a compaction.
 292   void print_hrm_post_compaction();
 293 
 294   // Create a memory mapper for auxiliary data structures of the given size and
 295   // translation factor.
 296   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 297                                                          size_t size,
 298                                                          size_t translation_factor);
 299 
 300   static G1Policy* create_g1_policy();
 301 
 302   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 303 
 304   void process_weak_jni_handles();
 305 
 306   // These are macros so that, if the assert fires, we get the correct
 307   // line number, file, etc.
 308 
 309 #define heap_locking_asserts_params(_extra_message_)                          \
 310   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 311   (_extra_message_),                                                          \
 312   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 313   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 314   BOOL_TO_STR(Thread::current()->is_VM_thread())
 315 
 316 #define assert_heap_locked()                                                  \
 317   do {                                                                        \
 318     assert(Heap_lock->owned_by_self(),                                        \
 319            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 320   } while (0)
 321 
 322 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 323   do {                                                                        \
 324     assert(Heap_lock->owned_by_self() ||                                      \
 325            (SafepointSynchronize::is_at_safepoint() &&                        \
 326              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 327            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 328                                         "should be at a safepoint"));         \
 329   } while (0)
 330 
 331 #define assert_heap_locked_and_not_at_safepoint()                             \
 332   do {                                                                        \
 333     assert(Heap_lock->owned_by_self() &&                                      \
 334                                     !SafepointSynchronize::is_at_safepoint(), \
 335           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 336                                        "should not be at a safepoint"));      \
 337   } while (0)
 338 
 339 #define assert_heap_not_locked()                                              \
 340   do {                                                                        \
 341     assert(!Heap_lock->owned_by_self(),                                       \
 342         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 343   } while (0)
 344 
 345 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 346   do {                                                                        \
 347     assert(!Heap_lock->owned_by_self() &&                                     \
 348                                     !SafepointSynchronize::is_at_safepoint(), \
 349       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 350                                    "should not be at a safepoint"));          \
 351   } while (0)
 352 
 353 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 354   do {                                                                        \
 355     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 356               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 357            heap_locking_asserts_params("should be at a safepoint"));          \
 358   } while (0)
 359 
 360 #define assert_not_at_safepoint()                                             \
 361   do {                                                                        \
 362     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 363            heap_locking_asserts_params("should not be at a safepoint"));      \
 364   } while (0)
 365 
 366 protected:
 367 
 368   // The young region list.
 369   G1EdenRegions _eden;
 370   G1SurvivorRegions _survivor;
 371 
 372   // The current policy object for the collector.
 373   G1Policy* _g1_policy;
 374   G1HeapSizingPolicy* _heap_sizing_policy;
 375 
 376   G1CollectionSet _collection_set;
 377 
 378   // This is the second level of trying to allocate a new region. If
 379   // new_region() didn't find a region on the free_list, this call will
 380   // check whether there's anything available on the
 381   // secondary_free_list and/or wait for more regions to appear on
 382   // that list, if _free_regions_coming is set.
 383   HeapRegion* new_region_try_secondary_free_list(bool is_old);
 384 
 385   // Try to allocate a single non-humongous HeapRegion sufficient for
 386   // an allocation of the given word_size. If do_expand is true,
 387   // attempt to expand the heap if necessary to satisfy the allocation
 388   // request. If the region is to be used as an old region or for a
 389   // humongous object, set is_old to true. If not, to false.
 390   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 391 
 392   // Initialize a contiguous set of free regions of length num_regions
 393   // and starting at index first so that they appear as a single
 394   // humongous region.
 395   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 396                                                       uint num_regions,
 397                                                       size_t word_size,
 398                                                       AllocationContext_t context);
 399 
 400   // Attempt to allocate a humongous object of the given size. Return
 401   // NULL if unsuccessful.
 402   HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
 403 
 404   // The following two methods, allocate_new_tlab() and
 405   // mem_allocate(), are the two main entry points from the runtime
 406   // into the G1's allocation routines. They have the following
 407   // assumptions:
 408   //
 409   // * They should both be called outside safepoints.
 410   //
 411   // * They should both be called without holding the Heap_lock.
 412   //
 413   // * All allocation requests for new TLABs should go to
 414   //   allocate_new_tlab().
 415   //
 416   // * All non-TLAB allocation requests should go to mem_allocate().
 417   //
 418   // * If either call cannot satisfy the allocation request using the
 419   //   current allocating region, they will try to get a new one. If
 420   //   this fails, they will attempt to do an evacuation pause and
 421   //   retry the allocation.
 422   //
 423   // * If all allocation attempts fail, even after trying to schedule
 424   //   an evacuation pause, allocate_new_tlab() will return NULL,
 425   //   whereas mem_allocate() will attempt a heap expansion and/or
 426   //   schedule a Full GC.
 427   //
 428   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 429   //   should never be called with word_size being humongous. All
 430   //   humongous allocation requests should go to mem_allocate() which
 431   //   will satisfy them with a special path.
 432 
 433   virtual HeapWord* allocate_new_tlab(size_t word_size);
 434 
 435   virtual HeapWord* mem_allocate(size_t word_size,
 436                                  bool*  gc_overhead_limit_was_exceeded);
 437 
 438   // The following three methods take a gc_count_before_ret
 439   // parameter which is used to return the GC count if the method
 440   // returns NULL. Given that we are required to read the GC count
 441   // while holding the Heap_lock, and these paths will take the
 442   // Heap_lock at some point, it's easier to get them to read the GC
 443   // count while holding the Heap_lock before they return NULL instead
 444   // of the caller (namely: mem_allocate()) having to also take the
 445   // Heap_lock just to read the GC count.
 446 
 447   // First-level mutator allocation attempt: try to allocate out of
 448   // the mutator alloc region without taking the Heap_lock. This
 449   // should only be used for non-humongous allocations.
 450   inline HeapWord* attempt_allocation(size_t word_size,
 451                                       uint* gc_count_before_ret,
 452                                       uint* gclocker_retry_count_ret);
 453 
 454   // Second-level mutator allocation attempt: take the Heap_lock and
 455   // retry the allocation attempt, potentially scheduling a GC
 456   // pause. This should only be used for non-humongous allocations.
 457   HeapWord* attempt_allocation_slow(size_t word_size,
 458                                     AllocationContext_t context,
 459                                     uint* gc_count_before_ret,
 460                                     uint* gclocker_retry_count_ret);
 461 
 462   // Takes the Heap_lock and attempts a humongous allocation. It can
 463   // potentially schedule a GC pause.
 464   HeapWord* attempt_allocation_humongous(size_t word_size,
 465                                          uint* gc_count_before_ret,
 466                                          uint* gclocker_retry_count_ret);
 467 
 468   // Allocation attempt that should be called during safepoints (e.g.,
 469   // at the end of a successful GC). expect_null_mutator_alloc_region
 470   // specifies whether the mutator alloc region is expected to be NULL
 471   // or not.
 472   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 473                                             AllocationContext_t context,
 474                                             bool expect_null_mutator_alloc_region);
 475 
 476   // These methods are the "callbacks" from the G1AllocRegion class.
 477 
 478   // For mutator alloc regions.
 479   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 480   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 481                                    size_t allocated_bytes);
 482 
 483   // For GC alloc regions.
 484   bool has_more_regions(InCSetState dest);
 485   HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
 486   void retire_gc_alloc_region(HeapRegion* alloc_region,
 487                               size_t allocated_bytes, InCSetState dest);
 488 
 489   // - if explicit_gc is true, the GC is for a System.gc() etc,
 490   //   otherwise it's for a failed allocation.
 491   // - if clear_all_soft_refs is true, all soft references should be
 492   //   cleared during the GC.
 493   // - it returns false if it is unable to do the collection due to the
 494   //   GC locker being active, true otherwise.
 495   bool do_full_collection(bool explicit_gc,
 496                           bool clear_all_soft_refs);
 497 
 498   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 499   virtual void do_full_collection(bool clear_all_soft_refs);
 500 
 501   // Resize the heap if necessary after a full collection.
 502   void resize_if_necessary_after_full_collection();
 503 
 504   // Callback from VM_G1CollectForAllocation operation.
 505   // This function does everything necessary/possible to satisfy a
 506   // failed allocation request (including collection, expansion, etc.)
 507   HeapWord* satisfy_failed_allocation(size_t word_size,
 508                                       AllocationContext_t context,
 509                                       bool* succeeded);
 510 private:
 511   // Helper method for satisfy_failed_allocation()
 512   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 513                                              AllocationContext_t context,
 514                                              bool do_gc,
 515                                              bool clear_all_soft_refs,
 516                                              bool expect_null_mutator_alloc_region,
 517                                              bool* gc_succeeded);
 518 
 519 protected:
 520   // Attempting to expand the heap sufficiently
 521   // to support an allocation of the given "word_size".  If
 522   // successful, perform the allocation and return the address of the
 523   // allocated block, or else "NULL".
 524   HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
 525 
 526   // Preserve any referents discovered by concurrent marking that have not yet been
 527   // copied by the STW pause.
 528   void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
 529   // Process any reference objects discovered during
 530   // an incremental evacuation pause.
 531   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 532 
 533   // Enqueue any remaining discovered references
 534   // after processing.
 535   void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 536 
 537   // Merges the information gathered on a per-thread basis for all worker threads
 538   // during GC into global variables.
 539   void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
 540 public:
 541   WorkGang* workers() const { return _workers; }
 542 
 543   G1Allocator* allocator() {
 544     return _allocator;
 545   }
 546 
 547   G1HeapVerifier* verifier() {
 548     return _verifier;
 549   }
 550 
 551   G1MonitoringSupport* g1mm() {
 552     assert(_g1mm != NULL, "should have been initialized");
 553     return _g1mm;
 554   }
 555 
 556   // Expand the garbage-first heap by at least the given size (in bytes!).
 557   // Returns true if the heap was expanded by the requested amount;
 558   // false otherwise.
 559   // (Rounds up to a HeapRegion boundary.)
 560   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 561 
 562   // Returns the PLAB statistics for a given destination.
 563   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 564 
 565   // Determines PLAB size for a given destination.
 566   inline size_t desired_plab_sz(InCSetState dest);
 567 
 568   inline AllocationContextStats& allocation_context_stats();
 569 
 570   // Do anything common to GC's.
 571   void gc_prologue(bool full);
 572   void gc_epilogue(bool full);
 573 
 574   // Modify the reclaim candidate set and test for presence.
 575   // These are only valid for starts_humongous regions.
 576   inline void set_humongous_reclaim_candidate(uint region, bool value);
 577   inline bool is_humongous_reclaim_candidate(uint region);
 578 
 579   // Remove from the reclaim candidate set.  Also remove from the
 580   // collection set so that later encounters avoid the slow path.
 581   inline void set_humongous_is_live(oop obj);
 582 
 583   // Register the given region to be part of the collection set.
 584   inline void register_humongous_region_with_cset(uint index);
 585   // Register regions with humongous objects (actually on the start region) in
 586   // the in_cset_fast_test table.
 587   void register_humongous_regions_with_cset();
 588   // We register a region with the fast "in collection set" test. We
 589   // simply set to true the array slot corresponding to this region.
 590   void register_young_region_with_cset(HeapRegion* r) {
 591     _in_cset_fast_test.set_in_young(r->hrm_index());
 592   }
 593   void register_old_region_with_cset(HeapRegion* r) {
 594     _in_cset_fast_test.set_in_old(r->hrm_index());
 595   }
 596   inline void register_ext_region_with_cset(HeapRegion* r) {
 597     _in_cset_fast_test.set_ext(r->hrm_index());
 598   }
 599   void clear_in_cset(const HeapRegion* hr) {
 600     _in_cset_fast_test.clear(hr);
 601   }
 602 
 603   void clear_cset_fast_test() {
 604     _in_cset_fast_test.clear();
 605   }
 606 
 607   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 608 
 609   // This is called at the start of either a concurrent cycle or a Full
 610   // GC to update the number of old marking cycles started.
 611   void increment_old_marking_cycles_started();
 612 
 613   // This is called at the end of either a concurrent cycle or a Full
 614   // GC to update the number of old marking cycles completed. Those two
 615   // can happen in a nested fashion, i.e., we start a concurrent
 616   // cycle, a Full GC happens half-way through it which ends first,
 617   // and then the cycle notices that a Full GC happened and ends
 618   // too. The concurrent parameter is a boolean to help us do a bit
 619   // tighter consistency checking in the method. If concurrent is
 620   // false, the caller is the inner caller in the nesting (i.e., the
 621   // Full GC). If concurrent is true, the caller is the outer caller
 622   // in this nesting (i.e., the concurrent cycle). Further nesting is
 623   // not currently supported. The end of this call also notifies
 624   // the FullGCCount_lock in case a Java thread is waiting for a full
 625   // GC to happen (e.g., it called System.gc() with
 626   // +ExplicitGCInvokesConcurrent).
 627   void increment_old_marking_cycles_completed(bool concurrent);
 628 
 629   uint old_marking_cycles_completed() {
 630     return _old_marking_cycles_completed;
 631   }
 632 
 633   G1HRPrinter* hr_printer() { return &_hr_printer; }
 634 
 635   // Allocates a new heap region instance.
 636   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 637 
 638   // Allocate the highest free region in the reserved heap. This will commit
 639   // regions as necessary.
 640   HeapRegion* alloc_highest_free_region();
 641 
 642   // Frees a non-humongous region by initializing its contents and
 643   // adding it to the free list that's passed as a parameter (this is
 644   // 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 skip_remset is true, the region's RSet will not be freed
 647   // up. If skip_hot_card_cache is true, the region's hot card cache will not
 648   // be freed up. The assumption is that this will be done later.
 649   // The locked parameter indicates if the caller has already taken
 650   // care of proper synchronization. This may allow some optimizations.
 651   void free_region(HeapRegion* hr,
 652                    FreeRegionList* free_list,
 653                    bool skip_remset,
 654                    bool skip_hot_card_cache = false,
 655                    bool locked = false);
 656 
 657   // It dirties the cards that cover the block so that the post
 658   // write barrier never queues anything when updating objects on this
 659   // block. It is assumed (and in fact we assert) that the block
 660   // belongs to a young region.
 661   inline void dirty_young_block(HeapWord* start, size_t word_size);
 662 
 663   // Frees a humongous region by collapsing it into individual regions
 664   // and calling free_region() for each of them. The freed regions
 665   // will be added to the free list that's passed as a parameter (this
 666   // is usually a local list which will be appended to the master free
 667   // list later). The used bytes of freed regions are accumulated in
 668   // pre_used. If skip_remset is true, the region's RSet will not be freed
 669   // up. The assumption is that this will be done later.
 670   void free_humongous_region(HeapRegion* hr,
 671                              FreeRegionList* free_list,
 672                              bool skip_remset);
 673 
 674   // Facility for allocating in 'archive' regions in high heap memory and
 675   // recording the allocated ranges. These should all be called from the
 676   // VM thread at safepoints, without the heap lock held. They can be used
 677   // to create and archive a set of heap regions which can be mapped at the
 678   // same fixed addresses in a subsequent JVM invocation.
 679   void begin_archive_alloc_range();
 680 
 681   // Check if the requested size would be too large for an archive allocation.
 682   bool is_archive_alloc_too_large(size_t word_size);
 683 
 684   // Allocate memory of the requested size from the archive region. This will
 685   // return NULL if the size is too large or if no memory is available. It
 686   // does not trigger a garbage collection.
 687   HeapWord* archive_mem_allocate(size_t word_size);
 688 
 689   // Optionally aligns the end address and returns the allocated ranges in
 690   // an array of MemRegions in order of ascending addresses.
 691   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 692                                size_t end_alignment_in_bytes = 0);
 693 
 694   // Facility for allocating a fixed range within the heap and marking
 695   // the containing regions as 'archive'. For use at JVM init time, when the
 696   // caller may mmap archived heap data at the specified range(s).
 697   // Verify that the MemRegions specified in the argument array are within the
 698   // reserved heap.
 699   bool check_archive_addresses(MemRegion* range, size_t count);
 700 
 701   // Commit the appropriate G1 regions containing the specified MemRegions
 702   // and mark them as 'archive' regions. The regions in the array must be
 703   // non-overlapping and in order of ascending address.
 704   bool alloc_archive_regions(MemRegion* range, size_t count);
 705 
 706   // Insert any required filler objects in the G1 regions around the specified
 707   // ranges to make the regions parseable. This must be called after
 708   // alloc_archive_regions, and after class loading has occurred.
 709   void fill_archive_regions(MemRegion* range, size_t count);
 710 
 711   // For each of the specified MemRegions, uncommit the containing G1 regions
 712   // which had been allocated by alloc_archive_regions. This should be called
 713   // rather than fill_archive_regions at JVM init time if the archive file
 714   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 715   void dealloc_archive_regions(MemRegion* range, size_t count);
 716 
 717 protected:
 718 
 719   // Shrink the garbage-first heap by at most the given size (in bytes!).
 720   // (Rounds down to a HeapRegion boundary.)
 721   virtual void shrink(size_t expand_bytes);
 722   void shrink_helper(size_t expand_bytes);
 723 
 724   #if TASKQUEUE_STATS
 725   static void print_taskqueue_stats_hdr(outputStream* const st);
 726   void print_taskqueue_stats() const;
 727   void reset_taskqueue_stats();
 728   #endif // TASKQUEUE_STATS
 729 
 730   // Schedule the VM operation that will do an evacuation pause to
 731   // satisfy an allocation request of word_size. *succeeded will
 732   // return whether the VM operation was successful (it did do an
 733   // evacuation pause) or not (another thread beat us to it or the GC
 734   // locker was active). Given that we should not be holding the
 735   // Heap_lock when we enter this method, we will pass the
 736   // gc_count_before (i.e., total_collections()) as a parameter since
 737   // it has to be read while holding the Heap_lock. Currently, both
 738   // methods that call do_collection_pause() release the Heap_lock
 739   // before the call, so it's easy to read gc_count_before just before.
 740   HeapWord* do_collection_pause(size_t         word_size,
 741                                 uint           gc_count_before,
 742                                 bool*          succeeded,
 743                                 GCCause::Cause gc_cause);
 744 
 745   void wait_for_root_region_scanning();
 746 
 747   // The guts of the incremental collection pause, executed by the vm
 748   // thread. It returns false if it is unable to do the collection due
 749   // to the GC locker being active, true otherwise
 750   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 751 
 752   // Actually do the work of evacuating the collection set.
 753   virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
 754 
 755   void pre_evacuate_collection_set();
 756   void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 757 
 758   // Print the header for the per-thread termination statistics.
 759   static void print_termination_stats_hdr();
 760   // Print actual per-thread termination statistics.
 761   void print_termination_stats(uint worker_id,
 762                                double elapsed_ms,
 763                                double strong_roots_ms,
 764                                double term_ms,
 765                                size_t term_attempts,
 766                                size_t alloc_buffer_waste,
 767                                size_t undo_waste) const;
 768   // Update object copying statistics.
 769   void record_obj_copy_mem_stats();
 770 
 771   // The hot card cache for remembered set insertion optimization.
 772   G1HotCardCache* _hot_card_cache;
 773 
 774   // The g1 remembered set of the heap.
 775   G1RemSet* _g1_rem_set;
 776 
 777   // A set of cards that cover the objects for which the Rsets should be updated
 778   // concurrently after the collection.
 779   DirtyCardQueueSet _dirty_card_queue_set;
 780 
 781   // The closure used to refine a single card.
 782   RefineCardTableEntryClosure* _refine_cte_cl;
 783 
 784   // After a collection pause, convert the regions in the collection set into free
 785   // regions.
 786   void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 787 
 788   // Abandon the current collection set without recording policy
 789   // statistics or updating free lists.
 790   void abandon_collection_set(G1CollectionSet* collection_set);
 791 
 792   // The concurrent marker (and the thread it runs in.)
 793   G1ConcurrentMark* _cm;
 794   ConcurrentMarkThread* _cmThread;
 795 
 796   // The concurrent refiner.
 797   ConcurrentG1Refine* _cg1r;
 798 
 799   // The parallel task queues
 800   RefToScanQueueSet *_task_queues;
 801 
 802   // True iff a evacuation has failed in the current collection.
 803   bool _evacuation_failed;
 804 
 805   EvacuationFailedInfo* _evacuation_failed_info_array;
 806 
 807   // Failed evacuations cause some logical from-space objects to have
 808   // forwarding pointers to themselves.  Reset them.
 809   void remove_self_forwarding_pointers();
 810 
 811   // Restore the objects in the regions in the collection set after an
 812   // evacuation failure.
 813   void restore_after_evac_failure();
 814 
 815   PreservedMarksSet _preserved_marks_set;
 816 
 817   // Preserve the mark of "obj", if necessary, in preparation for its mark
 818   // word being overwritten with a self-forwarding-pointer.
 819   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 820 
 821 #ifndef PRODUCT
 822   // Support for forcing evacuation failures. Analogous to
 823   // PromotionFailureALot for the other collectors.
 824 
 825   // Records whether G1EvacuationFailureALot should be in effect
 826   // for the current GC
 827   bool _evacuation_failure_alot_for_current_gc;
 828 
 829   // Used to record the GC number for interval checking when
 830   // determining whether G1EvaucationFailureALot is in effect
 831   // for the current GC.
 832   size_t _evacuation_failure_alot_gc_number;
 833 
 834   // Count of the number of evacuations between failures.
 835   volatile size_t _evacuation_failure_alot_count;
 836 
 837   // Set whether G1EvacuationFailureALot should be in effect
 838   // for the current GC (based upon the type of GC and which
 839   // command line flags are set);
 840   inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
 841                                                   bool during_initial_mark,
 842                                                   bool during_marking);
 843 
 844   inline void set_evacuation_failure_alot_for_current_gc();
 845 
 846   // Return true if it's time to cause an evacuation failure.
 847   inline bool evacuation_should_fail();
 848 
 849   // Reset the G1EvacuationFailureALot counters.  Should be called at
 850   // the end of an evacuation pause in which an evacuation failure occurred.
 851   inline void reset_evacuation_should_fail();
 852 #endif // !PRODUCT
 853 
 854   // ("Weak") Reference processing support.
 855   //
 856   // G1 has 2 instances of the reference processor class. One
 857   // (_ref_processor_cm) handles reference object discovery
 858   // and subsequent processing during concurrent marking cycles.
 859   //
 860   // The other (_ref_processor_stw) handles reference object
 861   // discovery and processing during full GCs and incremental
 862   // evacuation pauses.
 863   //
 864   // During an incremental pause, reference discovery will be
 865   // temporarily disabled for _ref_processor_cm and will be
 866   // enabled for _ref_processor_stw. At the end of the evacuation
 867   // pause references discovered by _ref_processor_stw will be
 868   // processed and discovery will be disabled. The previous
 869   // setting for reference object discovery for _ref_processor_cm
 870   // will be re-instated.
 871   //
 872   // At the start of marking:
 873   //  * Discovery by the CM ref processor is verified to be inactive
 874   //    and it's discovered lists are empty.
 875   //  * Discovery by the CM ref processor is then enabled.
 876   //
 877   // At the end of marking:
 878   //  * Any references on the CM ref processor's discovered
 879   //    lists are processed (possibly MT).
 880   //
 881   // At the start of full GC we:
 882   //  * Disable discovery by the CM ref processor and
 883   //    empty CM ref processor's discovered lists
 884   //    (without processing any entries).
 885   //  * Verify that the STW ref processor is inactive and it's
 886   //    discovered lists are empty.
 887   //  * Temporarily set STW ref processor discovery as single threaded.
 888   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 889   //    field.
 890   //  * Finally enable discovery by the STW ref processor.
 891   //
 892   // The STW ref processor is used to record any discovered
 893   // references during the full GC.
 894   //
 895   // At the end of a full GC we:
 896   //  * Enqueue any reference objects discovered by the STW ref processor
 897   //    that have non-live referents. This has the side-effect of
 898   //    making the STW ref processor inactive by disabling discovery.
 899   //  * Verify that the CM ref processor is still inactive
 900   //    and no references have been placed on it's discovered
 901   //    lists (also checked as a precondition during initial marking).
 902 
 903   // The (stw) reference processor...
 904   ReferenceProcessor* _ref_processor_stw;
 905 
 906   STWGCTimer* _gc_timer_stw;
 907 
 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   volatile bool _free_regions_coming;
 937 
 938 public:
 939 
 940   void set_refine_cte_cl_concurrency(bool concurrent);
 941 
 942   RefToScanQueue *task_queue(uint i) const;
 943 
 944   uint num_task_queues() const;
 945 
 946   // A set of cards where updates happened during the GC
 947   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 948 
 949   // Create a G1CollectedHeap with the specified policy.
 950   // Must call the initialize method afterwards.
 951   // May not return if something goes wrong.
 952   G1CollectedHeap(G1CollectorPolicy* policy);
 953 
 954   // Initialize the G1CollectedHeap to have the initial and
 955   // maximum sizes and remembered and barrier sets
 956   // specified by the policy object.
 957   jint initialize();
 958 
 959   virtual void stop();
 960 
 961   // Return the (conservative) maximum heap alignment for any G1 heap
 962   static size_t conservative_max_heap_alignment();
 963 
 964   // Does operations required after initialization has been done.
 965   void post_initialize();
 966 
 967   // Initialize weak reference processing.
 968   void ref_processing_init();
 969 
 970   virtual Name kind() const {
 971     return CollectedHeap::G1CollectedHeap;
 972   }
 973 
 974   virtual const char* name() const {
 975     return "G1";
 976   }
 977 
 978   const G1CollectorState* collector_state() const { return &_collector_state; }
 979   G1CollectorState* collector_state() { return &_collector_state; }
 980 
 981   // The current policy object for the collector.
 982   G1Policy* g1_policy() const { return _g1_policy; }
 983 
 984   const G1CollectionSet* collection_set() const { return &_collection_set; }
 985   G1CollectionSet* collection_set() { return &_collection_set; }
 986 
 987   virtual CollectorPolicy* collector_policy() const;
 988 
 989   // Adaptive size policy.  No such thing for g1.
 990   virtual AdaptiveSizePolicy* size_policy() { return NULL; }
 991 
 992   // The rem set and barrier set.
 993   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
 994 
 995   // Try to minimize the remembered set.
 996   void scrub_rem_set();
 997 
 998   uint get_gc_time_stamp() {
 999     return _gc_time_stamp;
1000   }
1001 
1002   inline void reset_gc_time_stamp();
1003 
1004   void check_gc_time_stamps() PRODUCT_RETURN;
1005 
1006   inline void increment_gc_time_stamp();
1007 
1008   // Reset the given region's GC timestamp. If it's starts humongous,
1009   // also reset the GC timestamp of its corresponding
1010   // continues humongous regions too.
1011   void reset_gc_time_stamps(HeapRegion* hr);
1012 
1013   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1014   void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1015 
1016   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1017   void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1018 
1019   // The shared block offset table array.
1020   G1BlockOffsetTable* bot() const { return _bot; }
1021 
1022   // Reference Processing accessors
1023 
1024   // The STW reference processor....
1025   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1026 
1027   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1028 
1029   // The Concurrent Marking reference processor...
1030   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1031 
1032   virtual size_t capacity() const;
1033   virtual size_t used() const;
1034   // This should be called when we're not holding the heap lock. The
1035   // result might be a bit inaccurate.
1036   size_t used_unlocked() const;
1037   size_t recalculate_used() const;
1038 
1039   // These virtual functions do the actual allocation.
1040   // Some heaps may offer a contiguous region for shared non-blocking
1041   // allocation, via inlined code (by exporting the address of the top and
1042   // end fields defining the extent of the contiguous allocation region.)
1043   // But G1CollectedHeap doesn't yet support this.
1044 
1045   virtual bool is_maximal_no_gc() const {
1046     return _hrm.available() == 0;
1047   }
1048 
1049   // The current number of regions in the heap.
1050   uint num_regions() const { return _hrm.length(); }
1051 
1052   // The max number of regions in the heap.
1053   uint max_regions() const { return _hrm.max_length(); }
1054 
1055   // The number of regions that are completely free.
1056   uint num_free_regions() const { return _hrm.num_free_regions(); }
1057 
1058   MemoryUsage get_auxiliary_data_memory_usage() const {
1059     return _hrm.get_auxiliary_data_memory_usage();
1060   }
1061 
1062   // The number of regions that are not completely free.
1063   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1064 
1065 #ifdef ASSERT
1066   bool is_on_master_free_list(HeapRegion* hr) {
1067     return _hrm.is_free(hr);
1068   }
1069 #endif // ASSERT
1070 
1071   // Wrapper for the region list operations that can be called from
1072   // methods outside this class.
1073 
1074   void secondary_free_list_add(FreeRegionList* list) {
1075     _secondary_free_list.add_ordered(list);
1076   }
1077 
1078   void append_secondary_free_list() {
1079     _hrm.insert_list_into_free_list(&_secondary_free_list);
1080   }
1081 
1082   void append_secondary_free_list_if_not_empty_with_lock() {
1083     // If the secondary free list looks empty there's no reason to
1084     // take the lock and then try to append it.
1085     if (!_secondary_free_list.is_empty()) {
1086       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1087       append_secondary_free_list();
1088     }
1089   }
1090 
1091   inline void old_set_add(HeapRegion* hr);
1092   inline void old_set_remove(HeapRegion* hr);
1093 
1094   size_t non_young_capacity_bytes() {
1095     return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1096   }
1097 
1098   void set_free_regions_coming();
1099   void reset_free_regions_coming();
1100   bool free_regions_coming() { return _free_regions_coming; }
1101   void wait_while_free_regions_coming();
1102 
1103   // Determine whether the given region is one that we are using as an
1104   // old GC alloc region.
1105   bool is_old_gc_alloc_region(HeapRegion* hr);
1106 
1107   // Perform a collection of the heap; intended for use in implementing
1108   // "System.gc".  This probably implies as full a collection as the
1109   // "CollectedHeap" supports.
1110   virtual void collect(GCCause::Cause cause);
1111 
1112   virtual bool copy_allocation_context_stats(const jint* contexts,
1113                                              jlong* totals,
1114                                              jbyte* accuracy,
1115                                              jint len);
1116 
1117   // True iff an evacuation has failed in the most-recent collection.
1118   bool evacuation_failed() { return _evacuation_failed; }
1119 
1120   void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1121   void prepend_to_freelist(FreeRegionList* list);
1122   void decrement_summary_bytes(size_t bytes);
1123 
1124   virtual bool is_in(const void* p) const;
1125 #ifdef ASSERT
1126   // Returns whether p is in one of the available areas of the heap. Slow but
1127   // extensive version.
1128   bool is_in_exact(const void* p) const;
1129 #endif
1130 
1131   // Return "TRUE" iff the given object address is within the collection
1132   // set. Slow implementation.
1133   bool obj_in_cs(oop obj);
1134 
1135   inline bool is_in_cset(const HeapRegion *hr);
1136   inline bool is_in_cset(oop obj);
1137 
1138   inline bool is_in_cset_or_humongous(const oop obj);
1139 
1140  private:
1141   // This array is used for a quick test on whether a reference points into
1142   // the collection set or not. Each of the array's elements denotes whether the
1143   // corresponding region is in the collection set or not.
1144   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1145 
1146  public:
1147 
1148   inline InCSetState in_cset_state(const oop obj);
1149 
1150   // Return "TRUE" iff the given object address is in the reserved
1151   // region of g1.
1152   bool is_in_g1_reserved(const void* p) const {
1153     return _hrm.reserved().contains(p);
1154   }
1155 
1156   // Returns a MemRegion that corresponds to the space that has been
1157   // reserved for the heap
1158   MemRegion g1_reserved() const {
1159     return _hrm.reserved();
1160   }
1161 
1162   virtual bool is_in_closed_subset(const void* p) const;
1163 
1164   G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1165     return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1166   }
1167 
1168   // Iteration functions.
1169 
1170   // Iterate over all objects, calling "cl.do_object" on each.
1171   virtual void object_iterate(ObjectClosure* cl);
1172 
1173   virtual void safe_object_iterate(ObjectClosure* cl) {
1174     object_iterate(cl);
1175   }
1176 
1177   // Iterate over heap regions, in address order, terminating the
1178   // iteration early if the "doHeapRegion" method returns "true".
1179   void heap_region_iterate(HeapRegionClosure* blk) const;
1180 
1181   // Return the region with the given index. It assumes the index is valid.
1182   inline HeapRegion* region_at(uint index) const;
1183 
1184   // Return the next region (by index) that is part of the same
1185   // humongous object that hr is part of.
1186   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1187 
1188   // Calculate the region index of the given address. Given address must be
1189   // within the heap.
1190   inline uint addr_to_region(HeapWord* addr) const;
1191 
1192   inline HeapWord* bottom_addr_for_region(uint index) const;
1193 
1194   // Iterate over the heap regions in parallel. Assumes that this will be called
1195   // in parallel by ParallelGCThreads worker threads with distinct worker ids
1196   // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1197   // to each of the regions, by attempting to claim the region using the
1198   // HeapRegionClaimer and, if successful, applying the closure to the claimed
1199   // region. The concurrent argument should be set to true if iteration is
1200   // performed concurrently, during which no assumptions are made for consistent
1201   // attributes of the heap regions (as they might be modified while iterating).
1202   void heap_region_par_iterate(HeapRegionClosure* cl,
1203                                uint worker_id,
1204                                HeapRegionClaimer* hrclaimer,
1205                                bool concurrent = false) const;
1206 
1207   // Iterate over the regions (if any) in the current collection set.
1208   void collection_set_iterate(HeapRegionClosure* blk);
1209 
1210   // Iterate over the regions (if any) in the current collection set. Starts the
1211   // iteration over the entire collection set so that the start regions of a given
1212   // worker id over the set active_workers are evenly spread across the set of
1213   // collection set regions.
1214   void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1215 
1216   HeapRegion* next_compaction_region(const HeapRegion* from) const;
1217 
1218   // Returns the HeapRegion that contains addr. addr must not be NULL.
1219   template <class T>
1220   inline HeapRegion* heap_region_containing(const T addr) const;
1221 
1222   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1223   // each address in the (reserved) heap is a member of exactly
1224   // one block.  The defining characteristic of a block is that it is
1225   // possible to find its size, and thus to progress forward to the next
1226   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1227   // represent Java objects, or they might be free blocks in a
1228   // free-list-based heap (or subheap), as long as the two kinds are
1229   // distinguishable and the size of each is determinable.
1230 
1231   // Returns the address of the start of the "block" that contains the
1232   // address "addr".  We say "blocks" instead of "object" since some heaps
1233   // may not pack objects densely; a chunk may either be an object or a
1234   // non-object.
1235   virtual HeapWord* block_start(const void* addr) const;
1236 
1237   // Requires "addr" to be the start of a chunk, and returns its size.
1238   // "addr + size" is required to be the start of a new chunk, or the end
1239   // of the active area of the heap.
1240   virtual size_t block_size(const HeapWord* addr) const;
1241 
1242   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1243   // the block is an object.
1244   virtual bool block_is_obj(const HeapWord* addr) const;
1245 
1246   // Section on thread-local allocation buffers (TLABs)
1247   // See CollectedHeap for semantics.
1248 
1249   bool supports_tlab_allocation() const;
1250   size_t tlab_capacity(Thread* ignored) const;
1251   size_t tlab_used(Thread* ignored) const;
1252   size_t max_tlab_size() const;
1253   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1254 
1255   // Can a compiler initialize a new object without store barriers?
1256   // This permission only extends from the creation of a new object
1257   // via a TLAB up to the first subsequent safepoint. If such permission
1258   // is granted for this heap type, the compiler promises to call
1259   // defer_store_barrier() below on any slow path allocation of
1260   // a new object for which such initializing store barriers will
1261   // have been elided. G1, like CMS, allows this, but should be
1262   // ready to provide a compensating write barrier as necessary
1263   // if that storage came out of a non-young region. The efficiency
1264   // of this implementation depends crucially on being able to
1265   // answer very efficiently in constant time whether a piece of
1266   // storage in the heap comes from a young region or not.
1267   // See ReduceInitialCardMarks.
1268   virtual bool can_elide_tlab_store_barriers() const {
1269     return true;
1270   }
1271 
1272   virtual bool card_mark_must_follow_store() const {
1273     return true;
1274   }
1275 
1276   inline bool is_in_young(const oop obj);
1277 
1278   virtual bool is_scavengable(const void* addr);
1279 
1280   // We don't need barriers for initializing stores to objects
1281   // in the young gen: for the SATB pre-barrier, there is no
1282   // pre-value that needs to be remembered; for the remembered-set
1283   // update logging post-barrier, we don't maintain remembered set
1284   // information for young gen objects.
1285   virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1286 
1287   // Returns "true" iff the given word_size is "very large".
1288   static bool is_humongous(size_t word_size) {
1289     // Note this has to be strictly greater-than as the TLABs
1290     // are capped at the humongous threshold and we want to
1291     // ensure that we don't try to allocate a TLAB as
1292     // humongous and that we don't allocate a humongous
1293     // object in a TLAB.
1294     return word_size > _humongous_object_threshold_in_words;
1295   }
1296 
1297   // Returns the humongous threshold for a specific region size
1298   static size_t humongous_threshold_for(size_t region_size) {
1299     return (region_size / 2);
1300   }
1301 
1302   // Returns the number of regions the humongous object of the given word size
1303   // requires.
1304   static size_t humongous_obj_size_in_regions(size_t word_size);
1305 
1306   // Print the maximum heap capacity.
1307   virtual size_t max_capacity() const;
1308 
1309   virtual jlong millis_since_last_gc();
1310 
1311 
1312   // Convenience function to be used in situations where the heap type can be
1313   // asserted to be this type.
1314   static G1CollectedHeap* heap();
1315 
1316   void set_region_short_lived_locked(HeapRegion* hr);
1317   // add appropriate methods for any other surv rate groups
1318 
1319   const G1SurvivorRegions* survivor() const { return &_survivor; }
1320 
1321   uint survivor_regions_count() const {
1322     return _survivor.length();
1323   }
1324 
1325   uint eden_regions_count() const {
1326     return _eden.length();
1327   }
1328 
1329   uint young_regions_count() const {
1330     return _eden.length() + _survivor.length();
1331   }
1332 
1333   uint old_regions_count() const { return _old_set.length(); }
1334 
1335   uint humongous_regions_count() const { return _humongous_set.length(); }
1336 
1337 #ifdef ASSERT
1338   bool check_young_list_empty();
1339 #endif
1340 
1341   // *** Stuff related to concurrent marking.  It's not clear to me that so
1342   // many of these need to be public.
1343 
1344   // The functions below are helper functions that a subclass of
1345   // "CollectedHeap" can use in the implementation of its virtual
1346   // functions.
1347   // This performs a concurrent marking of the live objects in a
1348   // bitmap off to the side.
1349   void doConcurrentMark();
1350 
1351   bool isMarkedPrev(oop obj) const;
1352   bool isMarkedNext(oop obj) const;
1353 
1354   // Determine if an object is dead, given the object and also
1355   // the region to which the object belongs. An object is dead
1356   // iff a) it was not allocated since the last mark, b) it
1357   // is not marked, and c) it is not in an archive region.
1358   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1359     return
1360       !hr->obj_allocated_since_prev_marking(obj) &&
1361       !isMarkedPrev(obj) &&
1362       !hr->is_archive();
1363   }
1364 
1365   // This function returns true when an object has been
1366   // around since the previous marking and hasn't yet
1367   // been marked during this marking, and is not in an archive region.
1368   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1369     return
1370       !hr->obj_allocated_since_next_marking(obj) &&
1371       !isMarkedNext(obj) &&
1372       !hr->is_archive();
1373   }
1374 
1375   // Determine if an object is dead, given only the object itself.
1376   // This will find the region to which the object belongs and
1377   // then call the region version of the same function.
1378 
1379   // Added if it is NULL it isn't dead.
1380 
1381   inline bool is_obj_dead(const oop obj) const;
1382 
1383   inline bool is_obj_ill(const oop obj) const;
1384 
1385   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1386 
1387   // Refinement
1388 
1389   ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1390 
1391   // Optimized nmethod scanning support routines
1392 
1393   // Register the given nmethod with the G1 heap.
1394   virtual void register_nmethod(nmethod* nm);
1395 
1396   // Unregister the given nmethod from the G1 heap.
1397   virtual void unregister_nmethod(nmethod* nm);
1398 
1399   // Free up superfluous code root memory.
1400   void purge_code_root_memory();
1401 
1402   // Rebuild the strong code root lists for each region
1403   // after a full GC.
1404   void rebuild_strong_code_roots();
1405 
1406   // Delete entries for dead interned string and clean up unreferenced symbols
1407   // in symbol table, possibly in parallel.
1408   void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1409 
1410   // Parallel phase of unloading/cleaning after G1 concurrent mark.
1411   void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1412 
1413   // Redirty logged cards in the refinement queue.
1414   void redirty_logged_cards();
1415   // Verification
1416 
1417   // Perform any cleanup actions necessary before allowing a verification.
1418   virtual void prepare_for_verify();
1419 
1420   // Perform verification.
1421 
1422   // vo == UsePrevMarking  -> use "prev" marking information,
1423   // vo == UseNextMarking -> use "next" marking information
1424   // vo == UseMarkWord    -> use the mark word in the object header
1425   //
1426   // NOTE: Only the "prev" marking information is guaranteed to be
1427   // consistent most of the time, so most calls to this should use
1428   // vo == UsePrevMarking.
1429   // Currently, there is only one case where this is called with
1430   // vo == UseNextMarking, which is to verify the "next" marking
1431   // information at the end of remark.
1432   // Currently there is only one place where this is called with
1433   // vo == UseMarkWord, which is to verify the marking during a
1434   // full GC.
1435   void verify(VerifyOption vo);
1436 
1437   // WhiteBox testing support.
1438   virtual bool supports_concurrent_phase_control() const;
1439   virtual const char* const* concurrent_phases() const;
1440   virtual bool request_concurrent_phase(const char* phase);
1441 
1442   // The methods below are here for convenience and dispatch the
1443   // appropriate method depending on value of the given VerifyOption
1444   // parameter. The values for that parameter, and their meanings,
1445   // are the same as those above.
1446 
1447   bool is_obj_dead_cond(const oop obj,
1448                         const HeapRegion* hr,
1449                         const VerifyOption vo) const;
1450 
1451   bool is_obj_dead_cond(const oop obj,
1452                         const VerifyOption vo) const;
1453 
1454   G1HeapSummary create_g1_heap_summary();
1455   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1456 
1457   // Printing
1458 private:
1459   void print_heap_regions() const;
1460   void print_regions_on(outputStream* st) const;
1461 
1462 public:
1463   virtual void print_on(outputStream* st) const;
1464   virtual void print_extended_on(outputStream* st) const;
1465   virtual void print_on_error(outputStream* st) const;
1466 
1467   virtual void print_gc_threads_on(outputStream* st) const;
1468   virtual void gc_threads_do(ThreadClosure* tc) const;
1469 
1470   // Override
1471   void print_tracing_info() const;
1472 
1473   // The following two methods are helpful for debugging RSet issues.
1474   void print_cset_rsets() PRODUCT_RETURN;
1475   void print_all_rsets() PRODUCT_RETURN;
1476 
1477 public:
1478   size_t pending_card_num();
1479 
1480 protected:
1481   size_t _max_heap_capacity;
1482 };
1483 
1484 class G1ParEvacuateFollowersClosure : public VoidClosure {
1485 private:
1486   double _start_term;
1487   double _term_time;
1488   size_t _term_attempts;
1489 
1490   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1491   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1492 protected:
1493   G1CollectedHeap*              _g1h;
1494   G1ParScanThreadState*         _par_scan_state;
1495   RefToScanQueueSet*            _queues;
1496   ParallelTaskTerminator*       _terminator;
1497 
1498   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1499   RefToScanQueueSet*      queues()         { return _queues; }
1500   ParallelTaskTerminator* terminator()     { return _terminator; }
1501 
1502 public:
1503   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1504                                 G1ParScanThreadState* par_scan_state,
1505                                 RefToScanQueueSet* queues,
1506                                 ParallelTaskTerminator* terminator)
1507     : _g1h(g1h), _par_scan_state(par_scan_state),
1508       _queues(queues), _terminator(terminator),
1509       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1510 
1511   void do_void();
1512 
1513   double term_time() const { return _term_time; }
1514   size_t term_attempts() const { return _term_attempts; }
1515 
1516 private:
1517   inline bool offer_termination();
1518 };
1519 
1520 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
--- EOF ---