rev 60421 : [mq]: 8248401-stefank-review

   1 /*
   2  * Copyright (c) 2001, 2020, 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  *
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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
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  24 
  25 #ifndef SHARE_GC_G1_G1COLLECTEDHEAP_HPP
  26 #define SHARE_GC_G1_G1COLLECTEDHEAP_HPP
  27 
  28 #include "gc/g1/g1BarrierSet.hpp"
  29 #include "gc/g1/g1BiasedArray.hpp"
  30 #include "gc/g1/g1CardTable.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/g1EvacuationInfo.hpp"
  38 #include "gc/g1/g1GCPhaseTimes.hpp"
  39 #include "gc/g1/g1HeapTransition.hpp"
  40 #include "gc/g1/g1HeapVerifier.hpp"
  41 #include "gc/g1/g1HRPrinter.hpp"
  42 #include "gc/g1/g1HeapRegionAttr.hpp"
  43 #include "gc/g1/g1MonitoringSupport.hpp"
  44 #include "gc/g1/g1NUMA.hpp"
  45 #include "gc/g1/g1RedirtyCardsQueue.hpp"
  46 #include "gc/g1/g1SurvivorRegions.hpp"
  47 #include "gc/g1/g1YCTypes.hpp"
  48 #include "gc/g1/heapRegionManager.hpp"
  49 #include "gc/g1/heapRegionSet.hpp"
  50 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
  51 #include "gc/shared/barrierSet.hpp"
  52 #include "gc/shared/collectedHeap.hpp"
  53 #include "gc/shared/gcHeapSummary.hpp"
  54 #include "gc/shared/plab.hpp"
  55 #include "gc/shared/preservedMarks.hpp"
  56 #include "gc/shared/softRefPolicy.hpp"
  57 #include "gc/shared/taskqueue.hpp"
  58 #include "memory/memRegion.hpp"
  59 #include "utilities/stack.hpp"
  60 
  61 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  62 // It uses the "Garbage First" heap organization and algorithm, which
  63 // may combine concurrent marking with parallel, incremental compaction of
  64 // heap subsets that will yield large amounts of garbage.
  65 
  66 // Forward declarations
  67 class HeapRegion;
  68 class GenerationSpec;
  69 class G1ParScanThreadState;
  70 class G1ParScanThreadStateSet;
  71 class G1ParScanThreadState;
  72 class MemoryPool;
  73 class MemoryManager;
  74 class ObjectClosure;
  75 class SpaceClosure;
  76 class CompactibleSpaceClosure;
  77 class Space;
  78 class G1CardTableEntryClosure;
  79 class G1CollectionSet;
  80 class G1Policy;
  81 class G1HotCardCache;
  82 class G1RemSet;
  83 class G1YoungRemSetSamplingThread;
  84 class G1ConcurrentMark;
  85 class G1ConcurrentMarkThread;
  86 class G1ConcurrentRefine;
  87 class GenerationCounters;
  88 class STWGCTimer;
  89 class G1NewTracer;
  90 class EvacuationFailedInfo;
  91 class nmethod;
  92 class WorkGang;
  93 class G1Allocator;
  94 class G1ArchiveAllocator;
  95 class G1FullGCScope;
  96 class G1HeapVerifier;
  97 class G1HeapSizingPolicy;
  98 class G1HeapSummary;
  99 class G1EvacSummary;
 100 
 101 typedef OverflowTaskQueue<ScannerTask, mtGC>           G1ScannerTasksQueue;
 102 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet;
 103 
 104 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
 105 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
 106 
 107 // The G1 STW is alive closure.
 108 // An instance is embedded into the G1CH and used as the
 109 // (optional) _is_alive_non_header closure in the STW
 110 // reference processor. It is also extensively used during
 111 // reference processing during STW evacuation pauses.
 112 class G1STWIsAliveClosure : public BoolObjectClosure {
 113   G1CollectedHeap* _g1h;
 114 public:
 115   G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
 116   bool do_object_b(oop p);
 117 };
 118 
 119 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
 120   G1CollectedHeap* _g1h;
 121 public:
 122   G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
 123   bool do_object_b(oop p);
 124 };
 125 
 126 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 127  private:
 128   void reset_from_card_cache(uint start_idx, size_t num_regions);
 129  public:
 130   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 131 };
 132 
 133 class G1CollectedHeap : public CollectedHeap {
 134   friend class VM_CollectForMetadataAllocation;
 135   friend class VM_G1CollectForAllocation;
 136   friend class VM_G1CollectFull;
 137   friend class VM_G1TryInitiateConcMark;
 138   friend class VMStructs;
 139   friend class MutatorAllocRegion;
 140   friend class G1FullCollector;
 141   friend class G1GCAllocRegion;
 142   friend class G1HeapVerifier;
 143 
 144   // Closures used in implementation.
 145   friend class G1ParScanThreadState;
 146   friend class G1ParScanThreadStateSet;
 147   friend class G1EvacuateRegionsTask;
 148   friend class G1PLABAllocator;
 149 
 150   // Other related classes.
 151   friend class HeapRegionClaimer;
 152 
 153   // Testing classes.
 154   friend class G1CheckRegionAttrTableClosure;
 155 
 156 private:
 157   G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
 158 
 159   WorkGang* _workers;
 160   G1CardTable* _card_table;
 161 
 162   Ticks _collection_pause_end;
 163 
 164   SoftRefPolicy      _soft_ref_policy;
 165 
 166   static size_t _humongous_object_threshold_in_words;
 167 
 168   // These sets keep track of old, archive and humongous regions respectively.
 169   HeapRegionSet _old_set;
 170   HeapRegionSet _archive_set;
 171   HeapRegionSet _humongous_set;
 172 
 173   void eagerly_reclaim_humongous_regions();
 174   // Start a new incremental collection set for the next pause.
 175   void start_new_collection_set();
 176 
 177   // The block offset table for the G1 heap.
 178   G1BlockOffsetTable* _bot;
 179 
 180   // Tears down the region sets / lists so that they are empty and the
 181   // regions on the heap do not belong to a region set / list. The
 182   // only exception is the humongous set which we leave unaltered. If
 183   // free_list_only is true, it will only tear down the master free
 184   // list. It is called before a Full GC (free_list_only == false) or
 185   // before heap shrinking (free_list_only == true).
 186   void tear_down_region_sets(bool free_list_only);
 187 
 188   // Rebuilds the region sets / lists so that they are repopulated to
 189   // reflect the contents of the heap. The only exception is the
 190   // humongous set which was not torn down in the first place. If
 191   // free_list_only is true, it will only rebuild the master free
 192   // list. It is called after a Full GC (free_list_only == false) or
 193   // after heap shrinking (free_list_only == true).
 194   void rebuild_region_sets(bool free_list_only);
 195 
 196   // Callback for region mapping changed events.
 197   G1RegionMappingChangedListener _listener;
 198 
 199   // Handle G1 NUMA support.
 200   G1NUMA* _numa;
 201 
 202   // The sequence of all heap regions in the heap.
 203   HeapRegionManager* _hrm;
 204 
 205   // Manages all allocations with regions except humongous object allocations.
 206   G1Allocator* _allocator;
 207 
 208   // Manages all heap verification.
 209   G1HeapVerifier* _verifier;
 210 
 211   // Outside of GC pauses, the number of bytes used in all regions other
 212   // than the current allocation region(s).
 213   volatile size_t _summary_bytes_used;
 214 
 215   void increase_used(size_t bytes);
 216   void decrease_used(size_t bytes);
 217 
 218   void set_used(size_t bytes);
 219 
 220   // Number of bytes used in all regions during GC. Typically changed when
 221   // retiring a GC alloc region.
 222   size_t _bytes_used_during_gc;
 223 
 224   // Class that handles archive allocation ranges.
 225   G1ArchiveAllocator* _archive_allocator;
 226 
 227   // GC allocation statistics policy for survivors.
 228   G1EvacStats _survivor_evac_stats;
 229 
 230   // GC allocation statistics policy for tenured objects.
 231   G1EvacStats _old_evac_stats;
 232 
 233   // It specifies whether we should attempt to expand the heap after a
 234   // region allocation failure. If heap expansion fails we set this to
 235   // false so that we don't re-attempt the heap expansion (it's likely
 236   // that subsequent expansion attempts will also fail if one fails).
 237   // Currently, it is only consulted during GC and it's reset at the
 238   // start of each GC.
 239   bool _expand_heap_after_alloc_failure;
 240 
 241   // Helper for monitoring and management support.
 242   G1MonitoringSupport* _g1mm;
 243 
 244   // Records whether the region at the given index is (still) a
 245   // candidate for eager reclaim.  Only valid for humongous start
 246   // regions; other regions have unspecified values.  Humongous start
 247   // regions are initialized at start of collection pause, with
 248   // candidates removed from the set as they are found reachable from
 249   // roots or the young generation.
 250   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 251    protected:
 252     bool default_value() const { return false; }
 253    public:
 254     void clear() { G1BiasedMappedArray<bool>::clear(); }
 255     void set_candidate(uint region, bool value) {
 256       set_by_index(region, value);
 257     }
 258     bool is_candidate(uint region) {
 259       return get_by_index(region);
 260     }
 261   };
 262 
 263   HumongousReclaimCandidates _humongous_reclaim_candidates;
 264   // Stores whether during humongous object registration we found candidate regions.
 265   // If not, we can skip a few steps.
 266   bool _has_humongous_reclaim_candidates;
 267 
 268   G1HRPrinter _hr_printer;
 269 
 270   // Return true if an explicit GC should start a concurrent cycle instead
 271   // of doing a STW full GC. A concurrent cycle should be started if:
 272   // (a) cause == _g1_humongous_allocation,
 273   // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent,
 274   // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent,
 275   // (d) cause == _wb_conc_mark or _wb_breakpoint,
 276   // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent.
 277   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 278 
 279   // Attempt to start a concurrent cycle with the indicated cause.
 280   // precondition: should_do_concurrent_full_gc(cause)
 281   bool try_collect_concurrently(GCCause::Cause cause,
 282                                 uint gc_counter,
 283                                 uint old_marking_started_before);
 284 
 285   // Return true if should upgrade to full gc after an incremental one.
 286   bool should_upgrade_to_full_gc(GCCause::Cause cause);
 287 
 288   // indicates whether we are in young or mixed GC mode
 289   G1CollectorState _collector_state;
 290 
 291   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 292   // concurrent cycles) we have started.
 293   volatile uint _old_marking_cycles_started;
 294 
 295   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 296   // concurrent cycles) we have completed.
 297   volatile uint _old_marking_cycles_completed;
 298 
 299   // This is a non-product method that is helpful for testing. It is
 300   // called at the end of a GC and artificially expands the heap by
 301   // allocating a number of dead regions. This way we can induce very
 302   // frequent marking cycles and stress the cleanup / concurrent
 303   // cleanup code more (as all the regions that will be allocated by
 304   // this method will be found dead by the marking cycle).
 305   void allocate_dummy_regions() PRODUCT_RETURN;
 306 
 307   // If the HR printer is active, dump the state of the regions in the
 308   // heap after a compaction.
 309   void print_hrm_post_compaction();
 310 
 311   // Create a memory mapper for auxiliary data structures of the given size and
 312   // translation factor.
 313   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 314                                                          size_t size,
 315                                                          size_t translation_factor);
 316 
 317   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 318 
 319   // These are macros so that, if the assert fires, we get the correct
 320   // line number, file, etc.
 321 
 322 #define heap_locking_asserts_params(_extra_message_)                          \
 323   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 324   (_extra_message_),                                                          \
 325   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 326   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 327   BOOL_TO_STR(Thread::current()->is_VM_thread())
 328 
 329 #define assert_heap_locked()                                                  \
 330   do {                                                                        \
 331     assert(Heap_lock->owned_by_self(),                                        \
 332            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 333   } while (0)
 334 
 335 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 336   do {                                                                        \
 337     assert(Heap_lock->owned_by_self() ||                                      \
 338            (SafepointSynchronize::is_at_safepoint() &&                        \
 339              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 340            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 341                                         "should be at a safepoint"));         \
 342   } while (0)
 343 
 344 #define assert_heap_locked_and_not_at_safepoint()                             \
 345   do {                                                                        \
 346     assert(Heap_lock->owned_by_self() &&                                      \
 347                                     !SafepointSynchronize::is_at_safepoint(), \
 348           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 349                                        "should not be at a safepoint"));      \
 350   } while (0)
 351 
 352 #define assert_heap_not_locked()                                              \
 353   do {                                                                        \
 354     assert(!Heap_lock->owned_by_self(),                                       \
 355         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 356   } while (0)
 357 
 358 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 359   do {                                                                        \
 360     assert(!Heap_lock->owned_by_self() &&                                     \
 361                                     !SafepointSynchronize::is_at_safepoint(), \
 362       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 363                                    "should not be at a safepoint"));          \
 364   } while (0)
 365 
 366 #define assert_at_safepoint_on_vm_thread()                                    \
 367   do {                                                                        \
 368     assert_at_safepoint();                                                    \
 369     assert(Thread::current_or_null() != NULL, "no current thread");           \
 370     assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
 371   } while (0)
 372 
 373 #ifdef ASSERT
 374 #define assert_used_and_recalculate_used_equal(g1h)                           \
 375   do {                                                                        \
 376     size_t cur_used_bytes = g1h->used();                                      \
 377     size_t recal_used_bytes = g1h->recalculate_used();                        \
 378     assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \
 379            " same as recalculated used(" SIZE_FORMAT ").",                    \
 380            cur_used_bytes, recal_used_bytes);                                 \
 381   } while (0)
 382 #else
 383 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0)
 384 #endif
 385 
 386   const char* young_gc_name() const;
 387 
 388   // The young region list.
 389   G1EdenRegions _eden;
 390   G1SurvivorRegions _survivor;
 391 
 392   STWGCTimer* _gc_timer_stw;
 393 
 394   G1NewTracer* _gc_tracer_stw;
 395 
 396   // The current policy object for the collector.
 397   G1Policy* _policy;
 398   G1HeapSizingPolicy* _heap_sizing_policy;
 399 
 400   G1CollectionSet _collection_set;
 401 
 402   // Try to allocate a single non-humongous HeapRegion sufficient for
 403   // an allocation of the given word_size. If do_expand is true,
 404   // attempt to expand the heap if necessary to satisfy the allocation
 405   // request. 'type' takes the type of region to be allocated. (Use constants
 406   // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
 407   HeapRegion* new_region(size_t word_size,
 408                          HeapRegionType type,
 409                          bool do_expand,
 410                          uint node_index = G1NUMA::AnyNodeIndex);
 411 
 412   // Initialize a contiguous set of free regions of length num_regions
 413   // and starting at index first so that they appear as a single
 414   // humongous region.
 415   HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
 416                                                       uint num_regions,
 417                                                       size_t word_size);
 418 
 419   // Attempt to allocate a humongous object of the given size. Return
 420   // NULL if unsuccessful.
 421   HeapWord* humongous_obj_allocate(size_t word_size);
 422 
 423   // The following two methods, allocate_new_tlab() and
 424   // mem_allocate(), are the two main entry points from the runtime
 425   // into the G1's allocation routines. They have the following
 426   // assumptions:
 427   //
 428   // * They should both be called outside safepoints.
 429   //
 430   // * They should both be called without holding the Heap_lock.
 431   //
 432   // * All allocation requests for new TLABs should go to
 433   //   allocate_new_tlab().
 434   //
 435   // * All non-TLAB allocation requests should go to mem_allocate().
 436   //
 437   // * If either call cannot satisfy the allocation request using the
 438   //   current allocating region, they will try to get a new one. If
 439   //   this fails, they will attempt to do an evacuation pause and
 440   //   retry the allocation.
 441   //
 442   // * If all allocation attempts fail, even after trying to schedule
 443   //   an evacuation pause, allocate_new_tlab() will return NULL,
 444   //   whereas mem_allocate() will attempt a heap expansion and/or
 445   //   schedule a Full GC.
 446   //
 447   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 448   //   should never be called with word_size being humongous. All
 449   //   humongous allocation requests should go to mem_allocate() which
 450   //   will satisfy them with a special path.
 451 
 452   virtual HeapWord* allocate_new_tlab(size_t min_size,
 453                                       size_t requested_size,
 454                                       size_t* actual_size);
 455 
 456   virtual HeapWord* mem_allocate(size_t word_size,
 457                                  bool*  gc_overhead_limit_was_exceeded);
 458 
 459   // First-level mutator allocation attempt: try to allocate out of
 460   // the mutator alloc region without taking the Heap_lock. This
 461   // should only be used for non-humongous allocations.
 462   inline HeapWord* attempt_allocation(size_t min_word_size,
 463                                       size_t desired_word_size,
 464                                       size_t* actual_word_size);
 465 
 466   // Second-level mutator allocation attempt: take the Heap_lock and
 467   // retry the allocation attempt, potentially scheduling a GC
 468   // pause. This should only be used for non-humongous allocations.
 469   HeapWord* attempt_allocation_slow(size_t word_size);
 470 
 471   // Takes the Heap_lock and attempts a humongous allocation. It can
 472   // potentially schedule a GC pause.
 473   HeapWord* attempt_allocation_humongous(size_t word_size);
 474 
 475   // Allocation attempt that should be called during safepoints (e.g.,
 476   // at the end of a successful GC). expect_null_mutator_alloc_region
 477   // specifies whether the mutator alloc region is expected to be NULL
 478   // or not.
 479   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 480                                             bool expect_null_mutator_alloc_region);
 481 
 482   // These methods are the "callbacks" from the G1AllocRegion class.
 483 
 484   // For mutator alloc regions.
 485   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index);
 486   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 487                                    size_t allocated_bytes);
 488 
 489   // For GC alloc regions.
 490   bool has_more_regions(G1HeapRegionAttr dest);
 491   HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index);
 492   void retire_gc_alloc_region(HeapRegion* alloc_region,
 493                               size_t allocated_bytes, G1HeapRegionAttr dest);
 494 
 495   // - if explicit_gc is true, the GC is for a System.gc() etc,
 496   //   otherwise it's for a failed allocation.
 497   // - if clear_all_soft_refs is true, all soft references should be
 498   //   cleared during the GC.
 499   // - it returns false if it is unable to do the collection due to the
 500   //   GC locker being active, true otherwise.
 501   bool do_full_collection(bool explicit_gc,
 502                           bool clear_all_soft_refs);
 503 
 504   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 505   virtual void do_full_collection(bool clear_all_soft_refs);
 506 
 507   // Callback from VM_G1CollectForAllocation operation.
 508   // This function does everything necessary/possible to satisfy a
 509   // failed allocation request (including collection, expansion, etc.)
 510   HeapWord* satisfy_failed_allocation(size_t word_size,
 511                                       bool* succeeded);
 512   // Internal helpers used during full GC to split it up to
 513   // increase readability.
 514   void abort_concurrent_cycle();
 515   void verify_before_full_collection(bool explicit_gc);
 516   void prepare_heap_for_full_collection();
 517   void prepare_heap_for_mutators();
 518   void abort_refinement();
 519   void verify_after_full_collection();
 520   void print_heap_after_full_collection(G1HeapTransition* heap_transition);
 521 
 522   // Helper method for satisfy_failed_allocation()
 523   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 524                                              bool do_gc,
 525                                              bool clear_all_soft_refs,
 526                                              bool expect_null_mutator_alloc_region,
 527                                              bool* gc_succeeded);
 528 
 529   // Attempting to expand the heap sufficiently
 530   // to support an allocation of the given "word_size".  If
 531   // successful, perform the allocation and return the address of the
 532   // allocated block, or else "NULL".
 533   HeapWord* expand_and_allocate(size_t word_size);
 534 
 535   // Process any reference objects discovered.
 536   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 537 
 538   // If during a concurrent start pause we may install a pending list head which is not
 539   // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking
 540   // to discover.
 541   void make_pending_list_reachable();
 542 
 543   // Merges the information gathered on a per-thread basis for all worker threads
 544   // during GC into global variables.
 545   void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
 546 
 547   void verify_numa_regions(const char* desc);
 548 
 549 public:
 550   G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
 551 
 552   WorkGang* workers() const { return _workers; }
 553 
 554   // Runs the given AbstractGangTask with the current active workers, returning the
 555   // total time taken.
 556   Tickspan run_task(AbstractGangTask* task);
 557 
 558   G1Allocator* allocator() {
 559     return _allocator;
 560   }
 561 
 562   G1HeapVerifier* verifier() {
 563     return _verifier;
 564   }
 565 
 566   G1MonitoringSupport* g1mm() {
 567     assert(_g1mm != NULL, "should have been initialized");
 568     return _g1mm;
 569   }
 570 
 571   void resize_heap_if_necessary();
 572 
 573   G1NUMA* numa() const { return _numa; }
 574 
 575   // Expand the garbage-first heap by at least the given size (in bytes!).
 576   // Returns true if the heap was expanded by the requested amount;
 577   // false otherwise.
 578   // (Rounds up to a HeapRegion boundary.)
 579   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 580   bool expand_single_region(uint node_index);
 581 
 582   // Returns the PLAB statistics for a given destination.
 583   inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest);
 584 
 585   // Determines PLAB size for a given destination.
 586   inline size_t desired_plab_sz(G1HeapRegionAttr dest);
 587 
 588   // Do anything common to GC's.
 589   void gc_prologue(bool full);
 590   void gc_epilogue(bool full);
 591 
 592   // Does the given region fulfill remembered set based eager reclaim candidate requirements?
 593   bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
 594 
 595   // Modify the reclaim candidate set and test for presence.
 596   // These are only valid for starts_humongous regions.
 597   inline void set_humongous_reclaim_candidate(uint region, bool value);
 598   inline bool is_humongous_reclaim_candidate(uint region);
 599   inline void set_has_humongous_reclaim_candidate(bool value);
 600 
 601   // Remove from the reclaim candidate set.  Also remove from the
 602   // collection set so that later encounters avoid the slow path.
 603   inline void set_humongous_is_live(oop obj);
 604 
 605   // Register the given region to be part of the collection set.
 606   inline void register_humongous_region_with_region_attr(uint index);
 607 
 608   // We register a region with the fast "in collection set" test. We
 609   // simply set to true the array slot corresponding to this region.
 610   void register_young_region_with_region_attr(HeapRegion* r) {
 611     _region_attr.set_in_young(r->hrm_index());
 612   }
 613   inline void register_region_with_region_attr(HeapRegion* r);
 614   inline void register_old_region_with_region_attr(HeapRegion* r);
 615   inline void register_optional_region_with_region_attr(HeapRegion* r);
 616 
 617   void clear_region_attr(const HeapRegion* hr) {
 618     _region_attr.clear(hr);
 619   }
 620 
 621   void clear_region_attr() {
 622     _region_attr.clear();
 623   }
 624 
 625   // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking
 626   // for all regions.
 627   void verify_region_attr_remset_update() PRODUCT_RETURN;
 628 
 629   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 630 
 631   // This is called at the start of either a concurrent cycle or a Full
 632   // GC to update the number of old marking cycles started.
 633   void increment_old_marking_cycles_started();
 634 
 635   // This is called at the end of either a concurrent cycle or a Full
 636   // GC to update the number of old marking cycles completed. Those two
 637   // can happen in a nested fashion, i.e., we start a concurrent
 638   // cycle, a Full GC happens half-way through it which ends first,
 639   // and then the cycle notices that a Full GC happened and ends
 640   // too. The concurrent parameter is a boolean to help us do a bit
 641   // tighter consistency checking in the method. If concurrent is
 642   // false, the caller is the inner caller in the nesting (i.e., the
 643   // Full GC). If concurrent is true, the caller is the outer caller
 644   // in this nesting (i.e., the concurrent cycle). Further nesting is
 645   // not currently supported. The end of this call also notifies
 646   // the G1OldGCCount_lock in case a Java thread is waiting for a full
 647   // GC to happen (e.g., it called System.gc() with
 648   // +ExplicitGCInvokesConcurrent).
 649   // liveness_completed should indicate that during that old marking
 650   // cycle the whole heap has actually been examined for live objects.
 651   void increment_old_marking_cycles_completed(bool concurrent, bool liveness_completed);

 652 
 653   uint old_marking_cycles_completed() {
 654     return _old_marking_cycles_completed;
 655   }
 656 
 657   G1HRPrinter* hr_printer() { return &_hr_printer; }
 658 
 659   // Allocates a new heap region instance.
 660   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 661 
 662   // Allocate the highest free region in the reserved heap. This will commit
 663   // regions as necessary.
 664   HeapRegion* alloc_highest_free_region();
 665 
 666   // Frees a region by resetting its metadata and adding it to the free list
 667   // passed as a parameter (this is usually a local list which will be appended
 668   // to the master free list later or NULL if free list management is handled
 669   // in another way).
 670   // Callers must ensure they are the only one calling free on the given region
 671   // at the same time.
 672   void free_region(HeapRegion* hr, FreeRegionList* free_list);
 673 
 674   // It dirties the cards that cover the block so that the post
 675   // write barrier never queues anything when updating objects on this
 676   // block. It is assumed (and in fact we assert) that the block
 677   // belongs to a young region.
 678   inline void dirty_young_block(HeapWord* start, size_t word_size);
 679 
 680   // Frees a humongous region by collapsing it into individual regions
 681   // and calling free_region() for each of them. The freed regions
 682   // will be added to the free list that's passed as a parameter (this
 683   // is usually a local list which will be appended to the master free
 684   // list later).
 685   // The method assumes that only a single thread is ever calling
 686   // this for a particular region at once.
 687   void free_humongous_region(HeapRegion* hr,
 688                              FreeRegionList* free_list);
 689 
 690   // Facility for allocating in 'archive' regions in high heap memory and
 691   // recording the allocated ranges. These should all be called from the
 692   // VM thread at safepoints, without the heap lock held. They can be used
 693   // to create and archive a set of heap regions which can be mapped at the
 694   // same fixed addresses in a subsequent JVM invocation.
 695   void begin_archive_alloc_range(bool open = false);
 696 
 697   // Check if the requested size would be too large for an archive allocation.
 698   bool is_archive_alloc_too_large(size_t word_size);
 699 
 700   // Allocate memory of the requested size from the archive region. This will
 701   // return NULL if the size is too large or if no memory is available. It
 702   // does not trigger a garbage collection.
 703   HeapWord* archive_mem_allocate(size_t word_size);
 704 
 705   // Optionally aligns the end address and returns the allocated ranges in
 706   // an array of MemRegions in order of ascending addresses.
 707   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 708                                size_t end_alignment_in_bytes = 0);
 709 
 710   // Facility for allocating a fixed range within the heap and marking
 711   // the containing regions as 'archive'. For use at JVM init time, when the
 712   // caller may mmap archived heap data at the specified range(s).
 713   // Verify that the MemRegions specified in the argument array are within the
 714   // reserved heap.
 715   bool check_archive_addresses(MemRegion* range, size_t count);
 716 
 717   // Commit the appropriate G1 regions containing the specified MemRegions
 718   // and mark them as 'archive' regions. The regions in the array must be
 719   // non-overlapping and in order of ascending address.
 720   bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
 721 
 722   // Insert any required filler objects in the G1 regions around the specified
 723   // ranges to make the regions parseable. This must be called after
 724   // alloc_archive_regions, and after class loading has occurred.
 725   void fill_archive_regions(MemRegion* range, size_t count);
 726 
 727   // For each of the specified MemRegions, uncommit the containing G1 regions
 728   // which had been allocated by alloc_archive_regions. This should be called
 729   // rather than fill_archive_regions at JVM init time if the archive file
 730   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 731   void dealloc_archive_regions(MemRegion* range, size_t count);
 732 
 733   oop materialize_archived_object(oop obj);
 734 
 735 private:
 736 
 737   // Shrink the garbage-first heap by at most the given size (in bytes!).
 738   // (Rounds down to a HeapRegion boundary.)
 739   void shrink(size_t shrink_bytes);
 740   void shrink_helper(size_t expand_bytes);
 741 
 742   #if TASKQUEUE_STATS
 743   static void print_taskqueue_stats_hdr(outputStream* const st);
 744   void print_taskqueue_stats() const;
 745   void reset_taskqueue_stats();
 746   #endif // TASKQUEUE_STATS
 747 
 748   // Schedule the VM operation that will do an evacuation pause to
 749   // satisfy an allocation request of word_size. *succeeded will
 750   // return whether the VM operation was successful (it did do an
 751   // evacuation pause) or not (another thread beat us to it or the GC
 752   // locker was active). Given that we should not be holding the
 753   // Heap_lock when we enter this method, we will pass the
 754   // gc_count_before (i.e., total_collections()) as a parameter since
 755   // it has to be read while holding the Heap_lock. Currently, both
 756   // methods that call do_collection_pause() release the Heap_lock
 757   // before the call, so it's easy to read gc_count_before just before.
 758   HeapWord* do_collection_pause(size_t         word_size,
 759                                 uint           gc_count_before,
 760                                 bool*          succeeded,
 761                                 GCCause::Cause gc_cause);
 762 
 763   void wait_for_root_region_scanning();
 764 
 765   // Perform an incremental collection at a safepoint, possibly
 766   // followed by a by-policy upgrade to a full collection.  Returns
 767   // false if unable to do the collection due to the GC locker being
 768   // active, true otherwise.
 769   // precondition: at safepoint on VM thread
 770   // precondition: !is_gc_active()
 771   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 772 
 773   // Helper for do_collection_pause_at_safepoint, containing the guts
 774   // of the incremental collection pause, executed by the vm thread.
 775   void do_collection_pause_at_safepoint_helper(double target_pause_time_ms);
 776 
 777   G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
 778   void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
 779   void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
 780 
 781   void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
 782 
 783   // Actually do the work of evacuating the parts of the collection set.
 784   void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states);
 785   void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
 786 private:
 787   // Evacuate the next set of optional regions.
 788   void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
 789 
 790 public:
 791   void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 792   void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
 793                                     G1RedirtyCardsQueueSet* rdcqs,
 794                                     G1ParScanThreadStateSet* pss);
 795 
 796   void expand_heap_after_young_collection();
 797   // Update object copying statistics.
 798   void record_obj_copy_mem_stats();
 799 
 800   // The hot card cache for remembered set insertion optimization.
 801   G1HotCardCache* _hot_card_cache;
 802 
 803   // The g1 remembered set of the heap.
 804   G1RemSet* _rem_set;
 805 
 806   // After a collection pause, convert the regions in the collection set into free
 807   // regions.
 808   void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 809 
 810   // Abandon the current collection set without recording policy
 811   // statistics or updating free lists.
 812   void abandon_collection_set(G1CollectionSet* collection_set);
 813 
 814   // The concurrent marker (and the thread it runs in.)
 815   G1ConcurrentMark* _cm;
 816   G1ConcurrentMarkThread* _cm_thread;
 817 
 818   // The concurrent refiner.
 819   G1ConcurrentRefine* _cr;
 820 
 821   // The parallel task queues
 822   G1ScannerTasksQueueSet *_task_queues;
 823 
 824   // True iff a evacuation has failed in the current collection.
 825   bool _evacuation_failed;
 826 
 827   EvacuationFailedInfo* _evacuation_failed_info_array;
 828 
 829   // Failed evacuations cause some logical from-space objects to have
 830   // forwarding pointers to themselves.  Reset them.
 831   void remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs);
 832 
 833   // Restore the objects in the regions in the collection set after an
 834   // evacuation failure.
 835   void restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs);
 836 
 837   PreservedMarksSet _preserved_marks_set;
 838 
 839   // Preserve the mark of "obj", if necessary, in preparation for its mark
 840   // word being overwritten with a self-forwarding-pointer.
 841   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m);
 842 
 843 #ifndef PRODUCT
 844   // Support for forcing evacuation failures. Analogous to
 845   // PromotionFailureALot for the other collectors.
 846 
 847   // Records whether G1EvacuationFailureALot should be in effect
 848   // for the current GC
 849   bool _evacuation_failure_alot_for_current_gc;
 850 
 851   // Used to record the GC number for interval checking when
 852   // determining whether G1EvaucationFailureALot is in effect
 853   // for the current GC.
 854   size_t _evacuation_failure_alot_gc_number;
 855 
 856   // Count of the number of evacuations between failures.
 857   volatile size_t _evacuation_failure_alot_count;
 858 
 859   // Set whether G1EvacuationFailureALot should be in effect
 860   // for the current GC (based upon the type of GC and which
 861   // command line flags are set);
 862   inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
 863                                                   bool during_concurrent_start,
 864                                                   bool mark_or_rebuild_in_progress);
 865 
 866   inline void set_evacuation_failure_alot_for_current_gc();
 867 
 868   // Return true if it's time to cause an evacuation failure.
 869   inline bool evacuation_should_fail();
 870 
 871   // Reset the G1EvacuationFailureALot counters.  Should be called at
 872   // the end of an evacuation pause in which an evacuation failure occurred.
 873   inline void reset_evacuation_should_fail();
 874 #endif // !PRODUCT
 875 
 876   // ("Weak") Reference processing support.
 877   //
 878   // G1 has 2 instances of the reference processor class. One
 879   // (_ref_processor_cm) handles reference object discovery
 880   // and subsequent processing during concurrent marking cycles.
 881   //
 882   // The other (_ref_processor_stw) handles reference object
 883   // discovery and processing during full GCs and incremental
 884   // evacuation pauses.
 885   //
 886   // During an incremental pause, reference discovery will be
 887   // temporarily disabled for _ref_processor_cm and will be
 888   // enabled for _ref_processor_stw. At the end of the evacuation
 889   // pause references discovered by _ref_processor_stw will be
 890   // processed and discovery will be disabled. The previous
 891   // setting for reference object discovery for _ref_processor_cm
 892   // will be re-instated.
 893   //
 894   // At the start of marking:
 895   //  * Discovery by the CM ref processor is verified to be inactive
 896   //    and it's discovered lists are empty.
 897   //  * Discovery by the CM ref processor is then enabled.
 898   //
 899   // At the end of marking:
 900   //  * Any references on the CM ref processor's discovered
 901   //    lists are processed (possibly MT).
 902   //
 903   // At the start of full GC we:
 904   //  * Disable discovery by the CM ref processor and
 905   //    empty CM ref processor's discovered lists
 906   //    (without processing any entries).
 907   //  * Verify that the STW ref processor is inactive and it's
 908   //    discovered lists are empty.
 909   //  * Temporarily set STW ref processor discovery as single threaded.
 910   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 911   //    field.
 912   //  * Finally enable discovery by the STW ref processor.
 913   //
 914   // The STW ref processor is used to record any discovered
 915   // references during the full GC.
 916   //
 917   // At the end of a full GC we:
 918   //  * Enqueue any reference objects discovered by the STW ref processor
 919   //    that have non-live referents. This has the side-effect of
 920   //    making the STW ref processor inactive by disabling discovery.
 921   //  * Verify that the CM ref processor is still inactive
 922   //    and no references have been placed on it's discovered
 923   //    lists (also checked as a precondition during concurrent start).
 924 
 925   // The (stw) reference processor...
 926   ReferenceProcessor* _ref_processor_stw;
 927 
 928   // During reference object discovery, the _is_alive_non_header
 929   // closure (if non-null) is applied to the referent object to
 930   // determine whether the referent is live. If so then the
 931   // reference object does not need to be 'discovered' and can
 932   // be treated as a regular oop. This has the benefit of reducing
 933   // the number of 'discovered' reference objects that need to
 934   // be processed.
 935   //
 936   // Instance of the is_alive closure for embedding into the
 937   // STW reference processor as the _is_alive_non_header field.
 938   // Supplying a value for the _is_alive_non_header field is
 939   // optional but doing so prevents unnecessary additions to
 940   // the discovered lists during reference discovery.
 941   G1STWIsAliveClosure _is_alive_closure_stw;
 942 
 943   G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
 944 
 945   // The (concurrent marking) reference processor...
 946   ReferenceProcessor* _ref_processor_cm;
 947 
 948   // Instance of the concurrent mark is_alive closure for embedding
 949   // into the Concurrent Marking reference processor as the
 950   // _is_alive_non_header field. Supplying a value for the
 951   // _is_alive_non_header field is optional but doing so prevents
 952   // unnecessary additions to the discovered lists during reference
 953   // discovery.
 954   G1CMIsAliveClosure _is_alive_closure_cm;
 955 
 956   G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
 957 public:
 958 
 959   G1ScannerTasksQueue* task_queue(uint i) const;
 960 
 961   uint num_task_queues() const;
 962 
 963   // Create a G1CollectedHeap.
 964   // Must call the initialize method afterwards.
 965   // May not return if something goes wrong.
 966   G1CollectedHeap();
 967 
 968 private:
 969   jint initialize_concurrent_refinement();
 970   jint initialize_young_gen_sampling_thread();
 971 public:
 972   // Initialize the G1CollectedHeap to have the initial and
 973   // maximum sizes and remembered and barrier sets
 974   // specified by the policy object.
 975   jint initialize();
 976 
 977   virtual void stop();
 978   virtual void safepoint_synchronize_begin();
 979   virtual void safepoint_synchronize_end();
 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::G1;
 989   }
 990 
 991   virtual const char* name() const {
 992     return "G1";
 993   }
 994 
 995   const G1CollectorState* collector_state() const { return &_collector_state; }
 996   G1CollectorState* collector_state() { return &_collector_state; }
 997 
 998   // The current policy object for the collector.
 999   G1Policy* policy() const { return _policy; }
1000   // The remembered set.
1001   G1RemSet* rem_set() const { return _rem_set; }
1002 
1003   inline G1GCPhaseTimes* phase_times() const;
1004 
1005   HeapRegionManager* hrm() const { return _hrm; }
1006 
1007   const G1CollectionSet* collection_set() const { return &_collection_set; }
1008   G1CollectionSet* collection_set() { return &_collection_set; }
1009 
1010   virtual SoftRefPolicy* soft_ref_policy();
1011 
1012   virtual void initialize_serviceability();
1013   virtual MemoryUsage memory_usage();
1014   virtual GrowableArray<GCMemoryManager*> memory_managers();
1015   virtual GrowableArray<MemoryPool*> memory_pools();
1016 
1017   // Try to minimize the remembered set.
1018   void scrub_rem_set();
1019 
1020   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1021   void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id);
1022 
1023   // The shared block offset table array.
1024   G1BlockOffsetTable* bot() const { return _bot; }
1025 
1026   // Reference Processing accessors
1027 
1028   // The STW reference processor....
1029   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1030 
1031   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1032 
1033   // The Concurrent Marking reference processor...
1034   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1035 
1036   size_t unused_committed_regions_in_bytes() const;
1037 
1038   virtual size_t capacity() const;
1039   virtual size_t used() const;
1040   // This should be called when we're not holding the heap lock. The
1041   // result might be a bit inaccurate.
1042   size_t used_unlocked() const;
1043   size_t recalculate_used() const;
1044 
1045   // These virtual functions do the actual allocation.
1046   // Some heaps may offer a contiguous region for shared non-blocking
1047   // allocation, via inlined code (by exporting the address of the top and
1048   // end fields defining the extent of the contiguous allocation region.)
1049   // But G1CollectedHeap doesn't yet support this.
1050 
1051   virtual bool is_maximal_no_gc() const {
1052     return _hrm->available() == 0;
1053   }
1054 
1055   // Returns whether there are any regions left in the heap for allocation.
1056   bool has_regions_left_for_allocation() const {
1057     return !is_maximal_no_gc() || num_free_regions() != 0;
1058   }
1059 
1060   // The current number of regions in the heap.
1061   uint num_regions() const { return _hrm->length(); }
1062 
1063   // The max number of regions in the heap.
1064   uint max_regions() const { return _hrm->max_length(); }
1065 
1066   // Max number of regions that can be comitted.
1067   uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1068 
1069   // The number of regions that are completely free.
1070   uint num_free_regions() const { return _hrm->num_free_regions(); }
1071 
1072   // The number of regions that can be allocated into.
1073   uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1074 
1075   MemoryUsage get_auxiliary_data_memory_usage() const {
1076     return _hrm->get_auxiliary_data_memory_usage();
1077   }
1078 
1079   // The number of regions that are not completely free.
1080   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1081 
1082 #ifdef ASSERT
1083   bool is_on_master_free_list(HeapRegion* hr) {
1084     return _hrm->is_free(hr);
1085   }
1086 #endif // ASSERT
1087 
1088   inline void old_set_add(HeapRegion* hr);
1089   inline void old_set_remove(HeapRegion* hr);
1090 
1091   inline void archive_set_add(HeapRegion* hr);
1092 
1093   size_t non_young_capacity_bytes() {
1094     return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1095   }
1096 
1097   // Determine whether the given region is one that we are using as an
1098   // old GC alloc region.
1099   bool is_old_gc_alloc_region(HeapRegion* hr);
1100 
1101   // Perform a collection of the heap; intended for use in implementing
1102   // "System.gc".  This probably implies as full a collection as the
1103   // "CollectedHeap" supports.
1104   virtual void collect(GCCause::Cause cause);
1105 
1106   // Perform a collection of the heap with the given cause.
1107   // Returns whether this collection actually executed.
1108   bool try_collect(GCCause::Cause cause);
1109 
1110   // True iff an evacuation has failed in the most-recent collection.
1111   bool evacuation_failed() { return _evacuation_failed; }
1112 
1113   void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1114   void prepend_to_freelist(FreeRegionList* list);
1115   void decrement_summary_bytes(size_t bytes);
1116 
1117   virtual bool is_in(const void* p) const;
1118 #ifdef ASSERT
1119   // Returns whether p is in one of the available areas of the heap. Slow but
1120   // extensive version.
1121   bool is_in_exact(const void* p) const;
1122 #endif
1123 
1124   // Return "TRUE" iff the given object address is within the collection
1125   // set. Assumes that the reference points into the heap.
1126   inline bool is_in_cset(const HeapRegion *hr);
1127   inline bool is_in_cset(oop obj);
1128   inline bool is_in_cset(HeapWord* addr);
1129 
1130   inline bool is_in_cset_or_humongous(const oop obj);
1131 
1132  private:
1133   // This array is used for a quick test on whether a reference points into
1134   // the collection set or not. Each of the array's elements denotes whether the
1135   // corresponding region is in the collection set or not.
1136   G1HeapRegionAttrBiasedMappedArray _region_attr;
1137 
1138  public:
1139 
1140   inline G1HeapRegionAttr region_attr(const void* obj) const;
1141   inline G1HeapRegionAttr region_attr(uint idx) const;
1142 
1143   // Return "TRUE" iff the given object address is in the reserved
1144   // region of g1.
1145   bool is_in_g1_reserved(const void* p) const {
1146     return _hrm->reserved().contains(p);
1147   }
1148 
1149   // Returns a MemRegion that corresponds to the space that has been
1150   // reserved for the heap
1151   MemRegion g1_reserved() const {
1152     return _hrm->reserved();
1153   }
1154 
1155   MemRegion reserved_region() const {
1156     return _reserved;
1157   }
1158 
1159   HeapWord* base() const {
1160     return _reserved.start();
1161   }
1162 
1163   bool is_in_reserved(const void* addr) const {
1164     return _reserved.contains(addr);
1165   }
1166 
1167   G1HotCardCache* hot_card_cache() const { return _hot_card_cache; }
1168 
1169   G1CardTable* card_table() const {
1170     return _card_table;
1171   }
1172 
1173   // Iteration functions.
1174 
1175   // Iterate over all objects, calling "cl.do_object" on each.
1176   virtual void object_iterate(ObjectClosure* cl);
1177 
1178   // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1179   virtual void keep_alive(oop obj);
1180 
1181   // Iterate over heap regions, in address order, terminating the
1182   // iteration early if the "do_heap_region" method returns "true".
1183   void heap_region_iterate(HeapRegionClosure* blk) const;
1184 
1185   // Return the region with the given index. It assumes the index is valid.
1186   inline HeapRegion* region_at(uint index) const;
1187   inline HeapRegion* region_at_or_null(uint index) const;
1188 
1189   // Return the next region (by index) that is part of the same
1190   // humongous object that hr is part of.
1191   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1192 
1193   // Calculate the region index of the given address. Given address must be
1194   // within the heap.
1195   inline uint addr_to_region(HeapWord* addr) const;
1196 
1197   inline HeapWord* bottom_addr_for_region(uint index) const;
1198 
1199   // Two functions to iterate over the heap regions in parallel. Threads
1200   // compete using the HeapRegionClaimer to claim the regions before
1201   // applying the closure on them.
1202   // The _from_worker_offset version uses the HeapRegionClaimer and
1203   // the worker id to calculate a start offset to prevent all workers to
1204   // start from the point.
1205   void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1206                                                   HeapRegionClaimer* hrclaimer,
1207                                                   uint worker_id) const;
1208 
1209   void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1210                                           HeapRegionClaimer* hrclaimer) const;
1211 
1212   // Iterate over all regions in the collection set in parallel.
1213   void collection_set_par_iterate_all(HeapRegionClosure* cl,
1214                                       HeapRegionClaimer* hr_claimer,
1215                                       uint worker_id);
1216 
1217   // Iterate over all regions currently in the current collection set.
1218   void collection_set_iterate_all(HeapRegionClosure* blk);
1219 
1220   // Iterate over the regions in the current increment of the collection set.
1221   // Starts the iteration so that the start regions of a given worker id over the
1222   // set active_workers are evenly spread across the set of collection set regions
1223   // to be iterated.
1224   // The variant with the HeapRegionClaimer guarantees that the closure will be
1225   // applied to a particular region exactly once.
1226   void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) {
1227     collection_set_iterate_increment_from(blk, NULL, worker_id);
1228   }
1229   void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id);
1230 
1231   // Returns the HeapRegion that contains addr. addr must not be NULL.
1232   template <class T>
1233   inline HeapRegion* heap_region_containing(const T addr) const;
1234 
1235   // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1236   // region. addr must not be NULL.
1237   template <class T>
1238   inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1239 
1240   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1241   // each address in the (reserved) heap is a member of exactly
1242   // one block.  The defining characteristic of a block is that it is
1243   // possible to find its size, and thus to progress forward to the next
1244   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1245   // represent Java objects, or they might be free blocks in a
1246   // free-list-based heap (or subheap), as long as the two kinds are
1247   // distinguishable and the size of each is determinable.
1248 
1249   // Returns the address of the start of the "block" that contains the
1250   // address "addr".  We say "blocks" instead of "object" since some heaps
1251   // may not pack objects densely; a chunk may either be an object or a
1252   // non-object.
1253   HeapWord* block_start(const void* addr) const;
1254 
1255   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1256   // the block is an object.
1257   bool block_is_obj(const HeapWord* addr) const;
1258 
1259   // Section on thread-local allocation buffers (TLABs)
1260   // See CollectedHeap for semantics.
1261 
1262   bool supports_tlab_allocation() const;
1263   size_t tlab_capacity(Thread* ignored) const;
1264   size_t tlab_used(Thread* ignored) const;
1265   size_t max_tlab_size() const;
1266   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1267 
1268   inline bool is_in_young(const oop obj);
1269 
1270   // Returns "true" iff the given word_size is "very large".
1271   static bool is_humongous(size_t word_size) {
1272     // Note this has to be strictly greater-than as the TLABs
1273     // are capped at the humongous threshold and we want to
1274     // ensure that we don't try to allocate a TLAB as
1275     // humongous and that we don't allocate a humongous
1276     // object in a TLAB.
1277     return word_size > _humongous_object_threshold_in_words;
1278   }
1279 
1280   // Returns the humongous threshold for a specific region size
1281   static size_t humongous_threshold_for(size_t region_size) {
1282     return (region_size / 2);
1283   }
1284 
1285   // Returns the number of regions the humongous object of the given word size
1286   // requires.
1287   static size_t humongous_obj_size_in_regions(size_t word_size);
1288 
1289   // Print the maximum heap capacity.
1290   virtual size_t max_capacity() const;
1291 
1292   // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1293   virtual size_t max_reserved_capacity() const;
1294 
1295   Tickspan time_since_last_collection() const { return Ticks::now() - _collection_pause_end; }
1296 
1297   // Convenience function to be used in situations where the heap type can be
1298   // asserted to be this type.
1299   static G1CollectedHeap* heap() {
1300     return named_heap<G1CollectedHeap>(CollectedHeap::G1);
1301   }
1302 
1303   void set_region_short_lived_locked(HeapRegion* hr);
1304   // add appropriate methods for any other surv rate groups
1305 
1306   const G1SurvivorRegions* survivor() const { return &_survivor; }
1307 
1308   uint eden_regions_count() const { return _eden.length(); }
1309   uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); }
1310   uint survivor_regions_count() const { return _survivor.length(); }
1311   uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); }
1312   size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1313   size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1314   uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1315   uint old_regions_count() const { return _old_set.length(); }
1316   uint archive_regions_count() const { return _archive_set.length(); }
1317   uint humongous_regions_count() const { return _humongous_set.length(); }
1318 
1319 #ifdef ASSERT
1320   bool check_young_list_empty();
1321 #endif
1322 
1323   // *** Stuff related to concurrent marking.  It's not clear to me that so
1324   // many of these need to be public.
1325 
1326   // The functions below are helper functions that a subclass of
1327   // "CollectedHeap" can use in the implementation of its virtual
1328   // functions.
1329   // This performs a concurrent marking of the live objects in a
1330   // bitmap off to the side.
1331   void do_concurrent_mark();
1332 
1333   bool is_marked_next(oop obj) const;
1334 
1335   // Determine if an object is dead, given the object and also
1336   // the region to which the object belongs. An object is dead
1337   // iff a) it was not allocated since the last mark, b) it
1338   // is not marked, and c) it is not in an archive region.
1339   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1340     return
1341       hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1342       !hr->is_archive();
1343   }
1344 
1345   // This function returns true when an object has been
1346   // around since the previous marking and hasn't yet
1347   // been marked during this marking, and is not in an archive region.
1348   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1349     return
1350       !hr->obj_allocated_since_next_marking(obj) &&
1351       !is_marked_next(obj) &&
1352       !hr->is_archive();
1353   }
1354 
1355   // Determine if an object is dead, given only the object itself.
1356   // This will find the region to which the object belongs and
1357   // then call the region version of the same function.
1358 
1359   // Added if it is NULL it isn't dead.
1360 
1361   inline bool is_obj_dead(const oop obj) const;
1362 
1363   inline bool is_obj_ill(const oop obj) const;
1364 
1365   inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1366   inline bool is_obj_dead_full(const oop obj) const;
1367 
1368   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1369 
1370   // Refinement
1371 
1372   G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1373 
1374   // Optimized nmethod scanning support routines
1375 
1376   // Register the given nmethod with the G1 heap.
1377   virtual void register_nmethod(nmethod* nm);
1378 
1379   // Unregister the given nmethod from the G1 heap.
1380   virtual void unregister_nmethod(nmethod* nm);
1381 
1382   // No nmethod flushing needed.
1383   virtual void flush_nmethod(nmethod* nm) {}
1384 
1385   // No nmethod verification implemented.
1386   virtual void verify_nmethod(nmethod* nm) {}
1387 
1388   // Free up superfluous code root memory.
1389   void purge_code_root_memory();
1390 
1391   // Rebuild the strong code root lists for each region
1392   // after a full GC.
1393   void rebuild_strong_code_roots();
1394 
1395   // Partial cleaning of VM internal data structures.
1396   void string_dedup_cleaning(BoolObjectClosure* is_alive,
1397                              OopClosure* keep_alive,
1398                              G1GCPhaseTimes* phase_times = NULL);
1399 
1400   // Performs cleaning of data structures after class unloading.
1401   void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1402 
1403   // Redirty logged cards in the refinement queue.
1404   void redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs);
1405 
1406   // Verification
1407 
1408   // Deduplicate the string
1409   virtual void deduplicate_string(oop str);
1410 
1411   // Perform any cleanup actions necessary before allowing a verification.
1412   virtual void prepare_for_verify();
1413 
1414   // Perform verification.
1415 
1416   // vo == UsePrevMarking -> use "prev" marking information,
1417   // vo == UseNextMarking -> use "next" marking information
1418   // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1419   //
1420   // NOTE: Only the "prev" marking information is guaranteed to be
1421   // consistent most of the time, so most calls to this should use
1422   // vo == UsePrevMarking.
1423   // Currently, there is only one case where this is called with
1424   // vo == UseNextMarking, which is to verify the "next" marking
1425   // information at the end of remark.
1426   // Currently there is only one place where this is called with
1427   // vo == UseFullMarking, which is to verify the marking during a
1428   // full GC.
1429   void verify(VerifyOption vo);
1430 
1431   // WhiteBox testing support.
1432   virtual bool supports_concurrent_gc_breakpoints() const;
1433   bool is_heterogeneous_heap() const;
1434 
1435   virtual WorkGang* get_safepoint_workers() { return _workers; }
1436 
1437   // The methods below are here for convenience and dispatch the
1438   // appropriate method depending on value of the given VerifyOption
1439   // parameter. The values for that parameter, and their meanings,
1440   // are the same as those above.
1441 
1442   bool is_obj_dead_cond(const oop obj,
1443                         const HeapRegion* hr,
1444                         const VerifyOption vo) const;
1445 
1446   bool is_obj_dead_cond(const oop obj,
1447                         const VerifyOption vo) const;
1448 
1449   G1HeapSummary create_g1_heap_summary();
1450   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1451 
1452   // Printing
1453 private:
1454   void print_heap_regions() const;
1455   void print_regions_on(outputStream* st) const;
1456 
1457 public:
1458   virtual void print_on(outputStream* st) const;
1459   virtual void print_extended_on(outputStream* st) const;
1460   virtual void print_on_error(outputStream* st) const;
1461 
1462   virtual void gc_threads_do(ThreadClosure* tc) const;
1463 
1464   // Override
1465   void print_tracing_info() const;
1466 
1467   // The following two methods are helpful for debugging RSet issues.
1468   void print_cset_rsets() PRODUCT_RETURN;
1469   void print_all_rsets() PRODUCT_RETURN;
1470 
1471   // Used to print information about locations in the hs_err file.
1472   virtual bool print_location(outputStream* st, void* addr) const;
1473 };
1474 
1475 class G1ParEvacuateFollowersClosure : public VoidClosure {
1476 private:
1477   double _start_term;
1478   double _term_time;
1479   size_t _term_attempts;
1480 
1481   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1482   void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1483 protected:
1484   G1CollectedHeap*              _g1h;
1485   G1ParScanThreadState*         _par_scan_state;
1486   G1ScannerTasksQueueSet*       _queues;
1487   TaskTerminator*               _terminator;
1488   G1GCPhaseTimes::GCParPhases   _phase;
1489 
1490   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1491   G1ScannerTasksQueueSet* queues()         { return _queues; }
1492   TaskTerminator*         terminator()     { return _terminator; }
1493 
1494 public:
1495   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1496                                 G1ParScanThreadState* par_scan_state,
1497                                 G1ScannerTasksQueueSet* queues,
1498                                 TaskTerminator* terminator,
1499                                 G1GCPhaseTimes::GCParPhases phase)
1500     : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1501       _g1h(g1h), _par_scan_state(par_scan_state),
1502       _queues(queues), _terminator(terminator), _phase(phase) {}
1503 
1504   void do_void();
1505 
1506   double term_time() const { return _term_time; }
1507   size_t term_attempts() const { return _term_attempts; }
1508 
1509 private:
1510   inline bool offer_termination();
1511 };
1512 
1513 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP
--- EOF ---