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
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  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.
  22  *
  23  */
  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 G1ParScanThreadState;
  64 class G1ParScanThreadStateSet;
  65 class G1KlassScanClosure;
  66 class G1ParScanThreadState;
  67 class ObjectClosure;
  68 class SpaceClosure;
  69 class CompactibleSpaceClosure;
  70 class Space;
  71 class G1CollectionSet;
  72 class G1CollectorPolicy;
  73 class G1Policy;
  74 class G1HotCardCache;
  75 class G1RemSet;
  76 class HeapRegionRemSetIterator;
  77 class G1ConcurrentMark;
  78 class ConcurrentMarkThread;
  79 class ConcurrentG1Refine;
  80 class GenerationCounters;
  81 class STWGCTimer;
  82 class G1NewTracer;
  83 class EvacuationFailedInfo;
  84 class nmethod;
  85 class Ticks;
  86 class WorkGang;
  87 class G1Allocator;
  88 class G1ArchiveAllocator;
  89 class G1HeapVerifier;
  90 class G1HeapSizingPolicy;
  91 class G1HeapSummary;
  92 class G1EvacSummary;
  93 
  94 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
  95 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
  96 
  97 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
  98 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
  99 
 100 // The G1 STW is alive closure.
 101 // An instance is embedded into the G1CH and used as the
 102 // (optional) _is_alive_non_header closure in the STW
 103 // reference processor. It is also extensively used during
 104 // reference processing during STW evacuation pauses.
 105 class G1STWIsAliveClosure: public BoolObjectClosure {
 106   G1CollectedHeap* _g1;
 107 public:
 108   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 109   bool do_object_b(oop p);
 110 };
 111 
 112 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 113  private:
 114   void reset_from_card_cache(uint start_idx, size_t num_regions);
 115  public:
 116   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 117 };
 118 
 119 class G1CollectedHeap : public CollectedHeap {
 120   friend class G1FreeCollectionSetTask;
 121   friend class VM_CollectForMetadataAllocation;
 122   friend class VM_G1CollectForAllocation;
 123   friend class VM_G1CollectFull;
 124   friend class VM_G1IncCollectionPause;
 125   friend class VMStructs;
 126   friend class MutatorAllocRegion;
 127   friend class G1GCAllocRegion;
 128   friend class G1HeapVerifier;
 129 
 130   // Closures used in implementation.
 131   friend class G1ParScanThreadState;
 132   friend class G1ParScanThreadStateSet;
 133   friend class G1ParTask;
 134   friend class G1PLABAllocator;
 135   friend class G1PrepareCompactClosure;
 136 
 137   // Other related classes.
 138   friend class HeapRegionClaimer;
 139 
 140   // Testing classes.
 141   friend class G1CheckCSetFastTableClosure;
 142 
 143 private:
 144   WorkGang* _workers;
 145   G1CollectorPolicy* _collector_policy;
 146 
 147   static size_t _humongous_object_threshold_in_words;
 148 
 149   // The secondary free list which contains regions that have been
 150   // freed up during the cleanup process. This will be appended to
 151   // the master free list when appropriate.
 152   FreeRegionList _secondary_free_list;
 153 
 154   // It keeps track of the old regions.
 155   HeapRegionSet _old_set;
 156 
 157   // It keeps track of the humongous regions.
 158   HeapRegionSet _humongous_set;
 159 
 160   void eagerly_reclaim_humongous_regions();
 161   // Start a new incremental collection set for the next pause.
 162   void start_new_collection_set();
 163 
 164   // The number of regions we could create by expansion.
 165   uint _expansion_regions;
 166 
 167   // The block offset table for the G1 heap.
 168   G1BlockOffsetTable* _bot;
 169 
 170   // Tears down the region sets / lists so that they are empty and the
 171   // regions on the heap do not belong to a region set / list. The
 172   // only exception is the humongous set which we leave unaltered. If
 173   // free_list_only is true, it will only tear down the master free
 174   // list. It is called before a Full GC (free_list_only == false) or
 175   // before heap shrinking (free_list_only == true).
 176   void tear_down_region_sets(bool free_list_only);
 177 
 178   // Rebuilds the region sets / lists so that they are repopulated to
 179   // reflect the contents of the heap. The only exception is the
 180   // humongous set which was not torn down in the first place. If
 181   // free_list_only is true, it will only rebuild the master free
 182   // list. It is called after a Full GC (free_list_only == false) or
 183   // after heap shrinking (free_list_only == true).
 184   void rebuild_region_sets(bool free_list_only);
 185 
 186   // Callback for region mapping changed events.
 187   G1RegionMappingChangedListener _listener;
 188 
 189   // The sequence of all heap regions in the heap.
 190   HeapRegionManager _hrm;
 191 
 192   // Manages all allocations with regions except humongous object allocations.
 193   G1Allocator* _allocator;
 194 
 195   // Manages all heap verification.
 196   G1HeapVerifier* _verifier;
 197 
 198   // Outside of GC pauses, the number of bytes used in all regions other
 199   // than the current allocation region(s).
 200   size_t _summary_bytes_used;
 201 
 202   void increase_used(size_t bytes);
 203   void decrease_used(size_t bytes);
 204 
 205   void set_used(size_t bytes);
 206 
 207   // Class that handles archive allocation ranges.
 208   G1ArchiveAllocator* _archive_allocator;
 209 
 210   // Statistics for each allocation context
 211   AllocationContextStats _allocation_context_stats;
 212 
 213   // GC allocation statistics policy for survivors.
 214   G1EvacStats _survivor_evac_stats;
 215 
 216   // GC allocation statistics policy for tenured objects.
 217   G1EvacStats _old_evac_stats;
 218 
 219   // It specifies whether we should attempt to expand the heap after a
 220   // region allocation failure. If heap expansion fails we set this to
 221   // false so that we don't re-attempt the heap expansion (it's likely
 222   // that subsequent expansion attempts will also fail if one fails).
 223   // Currently, it is only consulted during GC and it's reset at the
 224   // start of each GC.
 225   bool _expand_heap_after_alloc_failure;
 226 
 227   // Helper for monitoring and management support.
 228   G1MonitoringSupport* _g1mm;
 229 
 230   // Records whether the region at the given index is (still) a
 231   // candidate for eager reclaim.  Only valid for humongous start
 232   // regions; other regions have unspecified values.  Humongous start
 233   // regions are initialized at start of collection pause, with
 234   // candidates removed from the set as they are found reachable from
 235   // roots or the young generation.
 236   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 237    protected:
 238     bool default_value() const { return false; }
 239    public:
 240     void clear() { G1BiasedMappedArray<bool>::clear(); }
 241     void set_candidate(uint region, bool value) {
 242       set_by_index(region, value);
 243     }
 244     bool is_candidate(uint region) {
 245       return get_by_index(region);
 246     }
 247   };
 248 
 249   HumongousReclaimCandidates _humongous_reclaim_candidates;
 250   // Stores whether during humongous object registration we found candidate regions.
 251   // If not, we can skip a few steps.
 252   bool _has_humongous_reclaim_candidates;
 253 
 254   volatile uint _gc_time_stamp;
 255 
 256   G1HRPrinter _hr_printer;
 257 
 258   // It decides whether an explicit GC should start a concurrent cycle
 259   // instead of doing a STW GC. Currently, a concurrent cycle is
 260   // explicitly started if:
 261   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 262   // (b) cause == _g1_humongous_allocation
 263   // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 264   // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 265   // (e) cause == _update_allocation_context_stats_inc
 266   // (f) cause == _wb_conc_mark
 267   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 268 
 269   // indicates whether we are in young or mixed GC mode
 270   G1CollectorState _collector_state;
 271 
 272   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 273   // concurrent cycles) we have started.
 274   volatile uint _old_marking_cycles_started;
 275 
 276   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 277   // concurrent cycles) we have completed.
 278   volatile uint _old_marking_cycles_completed;
 279 
 280   // This is a non-product method that is helpful for testing. It is
 281   // called at the end of a GC and artificially expands the heap by
 282   // allocating a number of dead regions. This way we can induce very
 283   // frequent marking cycles and stress the cleanup / concurrent
 284   // cleanup code more (as all the regions that will be allocated by
 285   // this method will be found dead by the marking cycle).
 286   void allocate_dummy_regions() PRODUCT_RETURN;
 287 
 288   // Clear RSets after a compaction. It also resets the GC time stamps.
 289   void clear_rsets_post_compaction();
 290 
 291   // If the HR printer is active, dump the state of the regions in the
 292   // heap after a compaction.
 293   void print_hrm_post_compaction();
 294 
 295   // Create a memory mapper for auxiliary data structures of the given size and
 296   // translation factor.
 297   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 298                                                          size_t size,
 299                                                          size_t translation_factor);
 300 
 301   static G1Policy* create_g1_policy();
 302 
 303   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 304 
 305   void process_weak_jni_handles();
 306 
 307   // These are macros so that, if the assert fires, we get the correct
 308   // line number, file, etc.
 309 
 310 #define heap_locking_asserts_params(_extra_message_)                          \
 311   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 312   (_extra_message_),                                                          \
 313   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 314   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 315   BOOL_TO_STR(Thread::current()->is_VM_thread())
 316 
 317 #define assert_heap_locked()                                                  \
 318   do {                                                                        \
 319     assert(Heap_lock->owned_by_self(),                                        \
 320            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 321   } while (0)
 322 
 323 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 324   do {                                                                        \
 325     assert(Heap_lock->owned_by_self() ||                                      \
 326            (SafepointSynchronize::is_at_safepoint() &&                        \
 327              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 328            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 329                                         "should be at a safepoint"));         \
 330   } while (0)
 331 
 332 #define assert_heap_locked_and_not_at_safepoint()                             \
 333   do {                                                                        \
 334     assert(Heap_lock->owned_by_self() &&                                      \
 335                                     !SafepointSynchronize::is_at_safepoint(), \
 336           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 337                                        "should not be at a safepoint"));      \
 338   } while (0)
 339 
 340 #define assert_heap_not_locked()                                              \
 341   do {                                                                        \
 342     assert(!Heap_lock->owned_by_self(),                                       \
 343         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 344   } while (0)
 345 
 346 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 347   do {                                                                        \
 348     assert(!Heap_lock->owned_by_self() &&                                     \
 349                                     !SafepointSynchronize::is_at_safepoint(), \
 350       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 351                                    "should not be at a safepoint"));          \
 352   } while (0)
 353 
 354 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 355   do {                                                                        \
 356     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 357               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 358            heap_locking_asserts_params("should be at a safepoint"));          \
 359   } while (0)
 360 
 361 #define assert_not_at_safepoint()                                             \
 362   do {                                                                        \
 363     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 364            heap_locking_asserts_params("should not be at a safepoint"));      \
 365   } while (0)
 366 
 367 protected:
 368 
 369   // The young region list.
 370   G1EdenRegions _eden;
 371   G1SurvivorRegions _survivor;
 372 
 373   // The current policy object for the collector.
 374   G1Policy* _g1_policy;
 375   G1HeapSizingPolicy* _heap_sizing_policy;
 376 
 377   G1CollectionSet _collection_set;
 378 
 379   // This is the second level of trying to allocate a new region. If
 380   // new_region() didn't find a region on the free_list, this call will
 381   // check whether there's anything available on the
 382   // secondary_free_list and/or wait for more regions to appear on
 383   // that list, if _free_regions_coming is set.
 384   HeapRegion* new_region_try_secondary_free_list(bool is_old);
 385 
 386   // Try to allocate a single non-humongous HeapRegion sufficient for
 387   // an allocation of the given word_size. If do_expand is true,
 388   // attempt to expand the heap if necessary to satisfy the allocation
 389   // request. If the region is to be used as an old region or for a
 390   // humongous object, set is_old to true. If not, to false.
 391   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 392 
 393   // Initialize a contiguous set of free regions of length num_regions
 394   // and starting at index first so that they appear as a single
 395   // humongous region.
 396   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 397                                                       uint num_regions,
 398                                                       size_t word_size,
 399                                                       AllocationContext_t context);
 400 
 401   // Attempt to allocate a humongous object of the given size. Return
 402   // NULL if unsuccessful.
 403   HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
 404 
 405   // The following two methods, allocate_new_tlab() and
 406   // mem_allocate(), are the two main entry points from the runtime
 407   // into the G1's allocation routines. They have the following
 408   // assumptions:
 409   //
 410   // * They should both be called outside safepoints.
 411   //
 412   // * They should both be called without holding the Heap_lock.
 413   //
 414   // * All allocation requests for new TLABs should go to
 415   //   allocate_new_tlab().
 416   //
 417   // * All non-TLAB allocation requests should go to mem_allocate().
 418   //
 419   // * If either call cannot satisfy the allocation request using the
 420   //   current allocating region, they will try to get a new one. If
 421   //   this fails, they will attempt to do an evacuation pause and
 422   //   retry the allocation.
 423   //
 424   // * If all allocation attempts fail, even after trying to schedule
 425   //   an evacuation pause, allocate_new_tlab() will return NULL,
 426   //   whereas mem_allocate() will attempt a heap expansion and/or
 427   //   schedule a Full GC.
 428   //
 429   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 430   //   should never be called with word_size being humongous. All
 431   //   humongous allocation requests should go to mem_allocate() which
 432   //   will satisfy them with a special path.
 433 
 434   virtual HeapWord* allocate_new_tlab(size_t word_size);
 435 
 436   virtual HeapWord* mem_allocate(size_t word_size,
 437                                  bool*  gc_overhead_limit_was_exceeded);
 438 
 439   // The following three methods take a gc_count_before_ret
 440   // parameter which is used to return the GC count if the method
 441   // returns NULL. Given that we are required to read the GC count
 442   // while holding the Heap_lock, and these paths will take the
 443   // Heap_lock at some point, it's easier to get them to read the GC
 444   // count while holding the Heap_lock before they return NULL instead
 445   // of the caller (namely: mem_allocate()) having to also take the
 446   // Heap_lock just to read the GC count.
 447 
 448   // First-level mutator allocation attempt: try to allocate out of
 449   // the mutator alloc region without taking the Heap_lock. This
 450   // should only be used for non-humongous allocations.
 451   inline HeapWord* attempt_allocation(size_t word_size,
 452                                       uint* gc_count_before_ret,
 453                                       uint* gclocker_retry_count_ret);
 454 
 455   // Second-level mutator allocation attempt: take the Heap_lock and
 456   // retry the allocation attempt, potentially scheduling a GC
 457   // pause. This should only be used for non-humongous allocations.
 458   HeapWord* attempt_allocation_slow(size_t word_size,
 459                                     AllocationContext_t context,
 460                                     uint* gc_count_before_ret,
 461                                     uint* gclocker_retry_count_ret);
 462 
 463   // Takes the Heap_lock and attempts a humongous allocation. It can
 464   // potentially schedule a GC pause.
 465   HeapWord* attempt_allocation_humongous(size_t word_size,
 466                                          uint* gc_count_before_ret,
 467                                          uint* gclocker_retry_count_ret);
 468 
 469   // Allocation attempt that should be called during safepoints (e.g.,
 470   // at the end of a successful GC). expect_null_mutator_alloc_region
 471   // specifies whether the mutator alloc region is expected to be NULL
 472   // or not.
 473   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 474                                             AllocationContext_t context,
 475                                             bool expect_null_mutator_alloc_region);
 476 
 477   // These methods are the "callbacks" from the G1AllocRegion class.
 478 
 479   // For mutator alloc regions.
 480   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 481   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 482                                    size_t allocated_bytes);
 483 
 484   // For GC alloc regions.
 485   bool has_more_regions(InCSetState dest);
 486   HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
 487   void retire_gc_alloc_region(HeapRegion* alloc_region,
 488                               size_t allocated_bytes, InCSetState dest);
 489 
 490   // - if explicit_gc is true, the GC is for a System.gc() etc,
 491   //   otherwise it's for a failed allocation.
 492   // - if clear_all_soft_refs is true, all soft references should be
 493   //   cleared during the GC.
 494   // - it returns false if it is unable to do the collection due to the
 495   //   GC locker being active, true otherwise.
 496   bool do_full_collection(bool explicit_gc,
 497                           bool clear_all_soft_refs);
 498 
 499   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 500   virtual void do_full_collection(bool clear_all_soft_refs);
 501 
 502   // Resize the heap if necessary after a full collection.
 503   void resize_if_necessary_after_full_collection();
 504 
 505   // Callback from VM_G1CollectForAllocation operation.
 506   // This function does everything necessary/possible to satisfy a
 507   // failed allocation request (including collection, expansion, etc.)
 508   HeapWord* satisfy_failed_allocation(size_t word_size,
 509                                       AllocationContext_t context,
 510                                       bool* succeeded);
 511 private:
 512   // Helper method for satisfy_failed_allocation()
 513   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 514                                              AllocationContext_t context,
 515                                              bool do_gc,
 516                                              bool clear_all_soft_refs,
 517                                              bool expect_null_mutator_alloc_region,
 518                                              bool* gc_succeeded);
 519 
 520 protected:
 521   // Attempting to expand the heap sufficiently
 522   // to support an allocation of the given "word_size".  If
 523   // successful, perform the allocation and return the address of the
 524   // allocated block, or else "NULL".
 525   HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
 526 
 527   // Preserve any referents discovered by concurrent marking that have not yet been
 528   // copied by the STW pause.
 529   void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
 530   // Process any reference objects discovered during
 531   // an incremental evacuation pause.
 532   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 533 
 534   // Enqueue any remaining discovered references
 535   // after processing.
 536   void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 537 
 538   // Merges the information gathered on a per-thread basis for all worker threads
 539   // during GC into global variables.
 540   void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
 541 public:
 542   WorkGang* workers() const { return _workers; }
 543 
 544   G1Allocator* allocator() {
 545     return _allocator;
 546   }
 547 
 548   G1HeapVerifier* verifier() {
 549     return _verifier;
 550   }
 551 
 552   G1MonitoringSupport* g1mm() {
 553     assert(_g1mm != NULL, "should have been initialized");
 554     return _g1mm;
 555   }
 556 
 557   // Expand the garbage-first heap by at least the given size (in bytes!).
 558   // Returns true if the heap was expanded by the requested amount;
 559   // false otherwise.
 560   // (Rounds up to a HeapRegion boundary.)
 561   bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
 562 
 563   // Returns the PLAB statistics for a given destination.
 564   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 565 
 566   // Determines PLAB size for a given destination.
 567   inline size_t desired_plab_sz(InCSetState dest);
 568 
 569   inline AllocationContextStats& allocation_context_stats();
 570 
 571   // Do anything common to GC's.
 572   void gc_prologue(bool full);
 573   void gc_epilogue(bool full);
 574 
 575   // Modify the reclaim candidate set and test for presence.
 576   // These are only valid for starts_humongous regions.
 577   inline void set_humongous_reclaim_candidate(uint region, bool value);
 578   inline bool is_humongous_reclaim_candidate(uint region);
 579 
 580   // Remove from the reclaim candidate set.  Also remove from the
 581   // collection set so that later encounters avoid the slow path.
 582   inline void set_humongous_is_live(oop obj);
 583 
 584   // Register the given region to be part of the collection set.
 585   inline void register_humongous_region_with_cset(uint index);
 586   // Register regions with humongous objects (actually on the start region) in
 587   // the in_cset_fast_test table.
 588   void register_humongous_regions_with_cset();
 589   // We register a region with the fast "in collection set" test. We
 590   // simply set to true the array slot corresponding to this region.
 591   void register_young_region_with_cset(HeapRegion* r) {
 592     _in_cset_fast_test.set_in_young(r->hrm_index());
 593   }
 594   void register_old_region_with_cset(HeapRegion* r) {
 595     _in_cset_fast_test.set_in_old(r->hrm_index());
 596   }
 597   inline void register_ext_region_with_cset(HeapRegion* r) {
 598     _in_cset_fast_test.set_ext(r->hrm_index());
 599   }
 600   void clear_in_cset(const HeapRegion* hr) {
 601     _in_cset_fast_test.clear(hr);
 602   }
 603 
 604   void clear_cset_fast_test() {
 605     _in_cset_fast_test.clear();
 606   }
 607 
 608   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 609 
 610   // This is called at the start of either a concurrent cycle or a Full
 611   // GC to update the number of old marking cycles started.
 612   void increment_old_marking_cycles_started();
 613 
 614   // This is called at the end of either a concurrent cycle or a Full
 615   // GC to update the number of old marking cycles completed. Those two
 616   // can happen in a nested fashion, i.e., we start a concurrent
 617   // cycle, a Full GC happens half-way through it which ends first,
 618   // and then the cycle notices that a Full GC happened and ends
 619   // too. The concurrent parameter is a boolean to help us do a bit
 620   // tighter consistency checking in the method. If concurrent is
 621   // false, the caller is the inner caller in the nesting (i.e., the
 622   // Full GC). If concurrent is true, the caller is the outer caller
 623   // in this nesting (i.e., the concurrent cycle). Further nesting is
 624   // not currently supported. The end of this call also notifies
 625   // the FullGCCount_lock in case a Java thread is waiting for a full
 626   // GC to happen (e.g., it called System.gc() with
 627   // +ExplicitGCInvokesConcurrent).
 628   void increment_old_marking_cycles_completed(bool concurrent);
 629 
 630   uint old_marking_cycles_completed() {
 631     return _old_marking_cycles_completed;
 632   }
 633 
 634   G1HRPrinter* hr_printer() { return &_hr_printer; }
 635 
 636   // Allocates a new heap region instance.
 637   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 638 
 639   // Allocate the highest free region in the reserved heap. This will commit
 640   // regions as necessary.
 641   HeapRegion* alloc_highest_free_region();
 642 
 643   // Frees a non-humongous region by initializing its contents and
 644   // adding it to the free list that's passed as a parameter (this is
 645   // usually a local list which will be appended to the master free
 646   // list later). The used bytes of freed regions are accumulated in
 647   // pre_used. If skip_remset is true, the region's RSet will not be freed
 648   // up. If skip_hot_card_cache is true, the region's hot card cache will not
 649   // be freed up. The assumption is that this will be done later.
 650   // The locked parameter indicates if the caller has already taken
 651   // care of proper synchronization. This may allow some optimizations.
 652   void free_region(HeapRegion* hr,
 653                    FreeRegionList* free_list,
 654                    bool skip_remset,
 655                    bool skip_hot_card_cache = false,
 656                    bool locked = false);
 657 
 658   // It dirties the cards that cover the block so that the post
 659   // write barrier never queues anything when updating objects on this
 660   // block. It is assumed (and in fact we assert) that the block
 661   // belongs to a young region.
 662   inline void dirty_young_block(HeapWord* start, size_t word_size);
 663 
 664   // Frees a humongous region by collapsing it into individual regions
 665   // and calling free_region() for each of them. The freed regions
 666   // will be added to the free list that's passed as a parameter (this
 667   // is usually a local list which will be appended to the master free
 668   // list later). The used bytes of freed regions are accumulated in
 669   // pre_used. If skip_remset is true, the region's RSet will not be freed
 670   // up. The assumption is that this will be done later.
 671   void free_humongous_region(HeapRegion* hr,
 672                              FreeRegionList* free_list,
 673                              bool skip_remset);
 674 
 675   // Facility for allocating in 'archive' regions in high heap memory and
 676   // recording the allocated ranges. These should all be called from the
 677   // VM thread at safepoints, without the heap lock held. They can be used
 678   // to create and archive a set of heap regions which can be mapped at the
 679   // same fixed addresses in a subsequent JVM invocation.
 680   void begin_archive_alloc_range();
 681 
 682   // Check if the requested size would be too large for an archive allocation.
 683   bool is_archive_alloc_too_large(size_t word_size);
 684 
 685   // Allocate memory of the requested size from the archive region. This will
 686   // return NULL if the size is too large or if no memory is available. It
 687   // does not trigger a garbage collection.
 688   HeapWord* archive_mem_allocate(size_t word_size);
 689 
 690   // Optionally aligns the end address and returns the allocated ranges in
 691   // an array of MemRegions in order of ascending addresses.
 692   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 693                                size_t end_alignment_in_bytes = 0);
 694 
 695   // Facility for allocating a fixed range within the heap and marking
 696   // the containing regions as 'archive'. For use at JVM init time, when the
 697   // caller may mmap archived heap data at the specified range(s).
 698   // Verify that the MemRegions specified in the argument array are within the
 699   // reserved heap.
 700   bool check_archive_addresses(MemRegion* range, size_t count);
 701 
 702   // Commit the appropriate G1 regions containing the specified MemRegions
 703   // and mark them as 'archive' regions. The regions in the array must be
 704   // non-overlapping and in order of ascending address.
 705   bool alloc_archive_regions(MemRegion* range, size_t count);
 706 
 707   // Insert any required filler objects in the G1 regions around the specified
 708   // ranges to make the regions parseable. This must be called after
 709   // alloc_archive_regions, and after class loading has occurred.
 710   void fill_archive_regions(MemRegion* range, size_t count);
 711 
 712   // For each of the specified MemRegions, uncommit the containing G1 regions
 713   // which had been allocated by alloc_archive_regions. This should be called
 714   // rather than fill_archive_regions at JVM init time if the archive file
 715   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 716   void dealloc_archive_regions(MemRegion* range, size_t count);
 717 
 718 protected:
 719 
 720   // Shrink the garbage-first heap by at most the given size (in bytes!).
 721   // (Rounds down to a HeapRegion boundary.)
 722   virtual void shrink(size_t expand_bytes);
 723   void shrink_helper(size_t expand_bytes);
 724 
 725   #if TASKQUEUE_STATS
 726   static void print_taskqueue_stats_hdr(outputStream* const st);
 727   void print_taskqueue_stats() const;
 728   void reset_taskqueue_stats();
 729   #endif // TASKQUEUE_STATS
 730 
 731   // Schedule the VM operation that will do an evacuation pause to
 732   // satisfy an allocation request of word_size. *succeeded will
 733   // return whether the VM operation was successful (it did do an
 734   // evacuation pause) or not (another thread beat us to it or the GC
 735   // locker was active). Given that we should not be holding the
 736   // Heap_lock when we enter this method, we will pass the
 737   // gc_count_before (i.e., total_collections()) as a parameter since
 738   // it has to be read while holding the Heap_lock. Currently, both
 739   // methods that call do_collection_pause() release the Heap_lock
 740   // before the call, so it's easy to read gc_count_before just before.
 741   HeapWord* do_collection_pause(size_t         word_size,
 742                                 uint           gc_count_before,
 743                                 bool*          succeeded,
 744                                 GCCause::Cause gc_cause);
 745 
 746   void wait_for_root_region_scanning();
 747 
 748   // The guts of the incremental collection pause, executed by the vm
 749   // thread. It returns false if it is unable to do the collection due
 750   // to the GC locker being active, true otherwise
 751   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 752 
 753   // Actually do the work of evacuating the collection set.
 754   virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
 755 
 756   void pre_evacuate_collection_set();
 757   void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 758 
 759   // Print the header for the per-thread termination statistics.
 760   static void print_termination_stats_hdr();
 761   // Print actual per-thread termination statistics.
 762   void print_termination_stats(uint worker_id,
 763                                double elapsed_ms,
 764                                double strong_roots_ms,
 765                                double term_ms,
 766                                size_t term_attempts,
 767                                size_t alloc_buffer_waste,
 768                                size_t undo_waste) const;
 769   // Update object copying statistics.
 770   void record_obj_copy_mem_stats();
 771 
 772   // The hot card cache for remembered set insertion optimization.
 773   G1HotCardCache* _hot_card_cache;
 774 
 775   // The g1 remembered set of the heap.
 776   G1RemSet* _g1_rem_set;
 777 
 778   // A set of cards that cover the objects for which the Rsets should be updated
 779   // concurrently after the collection.
 780   DirtyCardQueueSet _dirty_card_queue_set;
 781 
 782   // After a collection pause, convert the regions in the collection set into free
 783   // regions.
 784   void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 785 
 786   // Abandon the current collection set without recording policy
 787   // statistics or updating free lists.
 788   void abandon_collection_set(G1CollectionSet* collection_set);
 789 
 790   // The concurrent marker (and the thread it runs in.)
 791   G1ConcurrentMark* _cm;
 792   ConcurrentMarkThread* _cmThread;
 793 
 794   // The concurrent refiner.
 795   ConcurrentG1Refine* _cg1r;
 796 
 797   // The parallel task queues
 798   RefToScanQueueSet *_task_queues;
 799 
 800   // True iff a evacuation has failed in the current collection.
 801   bool _evacuation_failed;
 802 
 803   EvacuationFailedInfo* _evacuation_failed_info_array;
 804 
 805   // Failed evacuations cause some logical from-space objects to have
 806   // forwarding pointers to themselves.  Reset them.
 807   void remove_self_forwarding_pointers();
 808 
 809   // Restore the objects in the regions in the collection set after an
 810   // evacuation failure.
 811   void restore_after_evac_failure();
 812 
 813   PreservedMarksSet _preserved_marks_set;
 814 
 815   // Preserve the mark of "obj", if necessary, in preparation for its mark
 816   // word being overwritten with a self-forwarding-pointer.
 817   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 818 
 819 #ifndef PRODUCT
 820   // Support for forcing evacuation failures. Analogous to
 821   // PromotionFailureALot for the other collectors.
 822 
 823   // Records whether G1EvacuationFailureALot should be in effect
 824   // for the current GC
 825   bool _evacuation_failure_alot_for_current_gc;
 826 
 827   // Used to record the GC number for interval checking when
 828   // determining whether G1EvaucationFailureALot is in effect
 829   // for the current GC.
 830   size_t _evacuation_failure_alot_gc_number;
 831 
 832   // Count of the number of evacuations between failures.
 833   volatile size_t _evacuation_failure_alot_count;
 834 
 835   // Set whether G1EvacuationFailureALot should be in effect
 836   // for the current GC (based upon the type of GC and which
 837   // command line flags are set);
 838   inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
 839                                                   bool during_initial_mark,
 840                                                   bool during_marking);
 841 
 842   inline void set_evacuation_failure_alot_for_current_gc();
 843 
 844   // Return true if it's time to cause an evacuation failure.
 845   inline bool evacuation_should_fail();
 846 
 847   // Reset the G1EvacuationFailureALot counters.  Should be called at
 848   // the end of an evacuation pause in which an evacuation failure occurred.
 849   inline void reset_evacuation_should_fail();
 850 #endif // !PRODUCT
 851 
 852   // ("Weak") Reference processing support.
 853   //
 854   // G1 has 2 instances of the reference processor class. One
 855   // (_ref_processor_cm) handles reference object discovery
 856   // and subsequent processing during concurrent marking cycles.
 857   //
 858   // The other (_ref_processor_stw) handles reference object
 859   // discovery and processing during full GCs and incremental
 860   // evacuation pauses.
 861   //
 862   // During an incremental pause, reference discovery will be
 863   // temporarily disabled for _ref_processor_cm and will be
 864   // enabled for _ref_processor_stw. At the end of the evacuation
 865   // pause references discovered by _ref_processor_stw will be
 866   // processed and discovery will be disabled. The previous
 867   // setting for reference object discovery for _ref_processor_cm
 868   // will be re-instated.
 869   //
 870   // At the start of marking:
 871   //  * Discovery by the CM ref processor is verified to be inactive
 872   //    and it's discovered lists are empty.
 873   //  * Discovery by the CM ref processor is then enabled.
 874   //
 875   // At the end of marking:
 876   //  * Any references on the CM ref processor's discovered
 877   //    lists are processed (possibly MT).
 878   //
 879   // At the start of full GC we:
 880   //  * Disable discovery by the CM ref processor and
 881   //    empty CM ref processor's discovered lists
 882   //    (without processing any entries).
 883   //  * Verify that the STW ref processor is inactive and it's
 884   //    discovered lists are empty.
 885   //  * Temporarily set STW ref processor discovery as single threaded.
 886   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 887   //    field.
 888   //  * Finally enable discovery by the STW ref processor.
 889   //
 890   // The STW ref processor is used to record any discovered
 891   // references during the full GC.
 892   //
 893   // At the end of a full GC we:
 894   //  * Enqueue any reference objects discovered by the STW ref processor
 895   //    that have non-live referents. This has the side-effect of
 896   //    making the STW ref processor inactive by disabling discovery.
 897   //  * Verify that the CM ref processor is still inactive
 898   //    and no references have been placed on it's discovered
 899   //    lists (also checked as a precondition during initial marking).
 900 
 901   // The (stw) reference processor...
 902   ReferenceProcessor* _ref_processor_stw;
 903 
 904   STWGCTimer* _gc_timer_stw;
 905 
 906   G1NewTracer* _gc_tracer_stw;
 907 
 908   // During reference object discovery, the _is_alive_non_header
 909   // closure (if non-null) is applied to the referent object to
 910   // determine whether the referent is live. If so then the
 911   // reference object does not need to be 'discovered' and can
 912   // be treated as a regular oop. This has the benefit of reducing
 913   // the number of 'discovered' reference objects that need to
 914   // be processed.
 915   //
 916   // Instance of the is_alive closure for embedding into the
 917   // STW reference processor as the _is_alive_non_header field.
 918   // Supplying a value for the _is_alive_non_header field is
 919   // optional but doing so prevents unnecessary additions to
 920   // the discovered lists during reference discovery.
 921   G1STWIsAliveClosure _is_alive_closure_stw;
 922 
 923   // The (concurrent marking) reference processor...
 924   ReferenceProcessor* _ref_processor_cm;
 925 
 926   // Instance of the concurrent mark is_alive closure for embedding
 927   // into the Concurrent Marking reference processor as the
 928   // _is_alive_non_header field. Supplying a value for the
 929   // _is_alive_non_header field is optional but doing so prevents
 930   // unnecessary additions to the discovered lists during reference
 931   // discovery.
 932   G1CMIsAliveClosure _is_alive_closure_cm;
 933 
 934   volatile bool _free_regions_coming;
 935 
 936 public:
 937 
 938   RefToScanQueue *task_queue(uint i) const;
 939 
 940   uint num_task_queues() const;
 941 
 942   // A set of cards where updates happened during the GC
 943   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 944 
 945   // Create a G1CollectedHeap with the specified policy.
 946   // Must call the initialize method afterwards.
 947   // May not return if something goes wrong.
 948   G1CollectedHeap(G1CollectorPolicy* policy);
 949 
 950 private:
 951   jint initialize_concurrent_refinement();
 952 public:
 953   // Initialize the G1CollectedHeap to have the initial and
 954   // maximum sizes and remembered and barrier sets
 955   // specified by the policy object.
 956   jint initialize();
 957 
 958   virtual void stop();
 959 
 960   // Return the (conservative) maximum heap alignment for any G1 heap
 961   static size_t conservative_max_heap_alignment();
 962 
 963   // Does operations required after initialization has been done.
 964   void post_initialize();
 965 
 966   // Initialize weak reference processing.
 967   void ref_processing_init();
 968 
 969   virtual Name kind() const {
 970     return CollectedHeap::G1CollectedHeap;
 971   }
 972 
 973   virtual const char* name() const {
 974     return "G1";
 975   }
 976 
 977   const G1CollectorState* collector_state() const { return &_collector_state; }
 978   G1CollectorState* collector_state() { return &_collector_state; }
 979 
 980   // The current policy object for the collector.
 981   G1Policy* g1_policy() const { return _g1_policy; }
 982 
 983   const G1CollectionSet* collection_set() const { return &_collection_set; }
 984   G1CollectionSet* collection_set() { return &_collection_set; }
 985 
 986   virtual CollectorPolicy* collector_policy() const;
 987 
 988   // Adaptive size policy.  No such thing for g1.
 989   virtual AdaptiveSizePolicy* size_policy() { return NULL; }
 990 
 991   // The rem set and barrier set.
 992   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
 993 
 994   // Try to minimize the remembered set.
 995   void scrub_rem_set();
 996 
 997   uint get_gc_time_stamp() {
 998     return _gc_time_stamp;
 999   }
1000 
1001   inline void reset_gc_time_stamp();
1002 
1003   void check_gc_time_stamps() PRODUCT_RETURN;
1004 
1005   inline void increment_gc_time_stamp();
1006 
1007   // Reset the given region's GC timestamp. If it's starts humongous,
1008   // also reset the GC timestamp of its corresponding
1009   // continues humongous regions too.
1010   void reset_gc_time_stamps(HeapRegion* hr);
1011 
1012   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1013   void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1014 
1015   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1016   void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1017 
1018   // The shared block offset table array.
1019   G1BlockOffsetTable* bot() const { return _bot; }
1020 
1021   // Reference Processing accessors
1022 
1023   // The STW reference processor....
1024   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1025 
1026   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1027 
1028   // The Concurrent Marking reference processor...
1029   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1030 
1031   virtual size_t capacity() const;
1032   virtual size_t used() const;
1033   // This should be called when we're not holding the heap lock. The
1034   // result might be a bit inaccurate.
1035   size_t used_unlocked() const;
1036   size_t recalculate_used() const;
1037 
1038   // These virtual functions do the actual allocation.
1039   // Some heaps may offer a contiguous region for shared non-blocking
1040   // allocation, via inlined code (by exporting the address of the top and
1041   // end fields defining the extent of the contiguous allocation region.)
1042   // But G1CollectedHeap doesn't yet support this.
1043 
1044   virtual bool is_maximal_no_gc() const {
1045     return _hrm.available() == 0;
1046   }
1047 
1048   // The current number of regions in the heap.
1049   uint num_regions() const { return _hrm.length(); }
1050 
1051   // The max number of regions in the heap.
1052   uint max_regions() const { return _hrm.max_length(); }
1053 
1054   // The number of regions that are completely free.
1055   uint num_free_regions() const { return _hrm.num_free_regions(); }
1056 
1057   MemoryUsage get_auxiliary_data_memory_usage() const {
1058     return _hrm.get_auxiliary_data_memory_usage();
1059   }
1060 
1061   // The number of regions that are not completely free.
1062   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1063 
1064 #ifdef ASSERT
1065   bool is_on_master_free_list(HeapRegion* hr) {
1066     return _hrm.is_free(hr);
1067   }
1068 #endif // ASSERT
1069 
1070   // Wrapper for the region list operations that can be called from
1071   // methods outside this class.
1072 
1073   void secondary_free_list_add(FreeRegionList* list) {
1074     _secondary_free_list.add_ordered(list);
1075   }
1076 
1077   void append_secondary_free_list() {
1078     _hrm.insert_list_into_free_list(&_secondary_free_list);
1079   }
1080 
1081   void append_secondary_free_list_if_not_empty_with_lock() {
1082     // If the secondary free list looks empty there's no reason to
1083     // take the lock and then try to append it.
1084     if (!_secondary_free_list.is_empty()) {
1085       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1086       append_secondary_free_list();
1087     }
1088   }
1089 
1090   inline void old_set_add(HeapRegion* hr);
1091   inline void old_set_remove(HeapRegion* hr);
1092 
1093   size_t non_young_capacity_bytes() {
1094     return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1095   }
1096 
1097   void set_free_regions_coming();
1098   void reset_free_regions_coming();
1099   bool free_regions_coming() { return _free_regions_coming; }
1100   void wait_while_free_regions_coming();
1101 
1102   // Determine whether the given region is one that we are using as an
1103   // old GC alloc region.
1104   bool is_old_gc_alloc_region(HeapRegion* hr);
1105 
1106   // Perform a collection of the heap; intended for use in implementing
1107   // "System.gc".  This probably implies as full a collection as the
1108   // "CollectedHeap" supports.
1109   virtual void collect(GCCause::Cause cause);
1110 
1111   virtual bool copy_allocation_context_stats(const jint* contexts,
1112                                              jlong* totals,
1113                                              jbyte* accuracy,
1114                                              jint len);
1115 
1116   // True iff an evacuation has failed in the most-recent collection.
1117   bool evacuation_failed() { return _evacuation_failed; }
1118 
1119   void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1120   void prepend_to_freelist(FreeRegionList* list);
1121   void decrement_summary_bytes(size_t bytes);
1122 
1123   virtual bool is_in(const void* p) const;
1124 #ifdef ASSERT
1125   // Returns whether p is in one of the available areas of the heap. Slow but
1126   // extensive version.
1127   bool is_in_exact(const void* p) const;
1128 #endif
1129 
1130   // Return "TRUE" iff the given object address is within the collection
1131   // set. Assumes that the reference points into the heap.
1132   inline bool is_in_cset(const HeapRegion *hr);
1133   inline bool is_in_cset(oop obj);
1134   inline bool is_in_cset(HeapWord* addr);
1135 
1136   inline bool is_in_cset_or_humongous(const oop obj);
1137 
1138  private:
1139   // This array is used for a quick test on whether a reference points into
1140   // the collection set or not. Each of the array's elements denotes whether the
1141   // corresponding region is in the collection set or not.
1142   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1143 
1144  public:
1145 
1146   inline InCSetState in_cset_state(const oop obj);
1147 
1148   // Return "TRUE" iff the given object address is in the reserved
1149   // region of g1.
1150   bool is_in_g1_reserved(const void* p) const {
1151     return _hrm.reserved().contains(p);
1152   }
1153 
1154   // Returns a MemRegion that corresponds to the space that has been
1155   // reserved for the heap
1156   MemRegion g1_reserved() const {
1157     return _hrm.reserved();
1158   }
1159 
1160   virtual bool is_in_closed_subset(const void* p) const;
1161 
1162   G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1163     return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1164   }
1165 
1166   // Iteration functions.
1167 
1168   // Iterate over all objects, calling "cl.do_object" on each.
1169   virtual void object_iterate(ObjectClosure* cl);
1170 
1171   virtual void safe_object_iterate(ObjectClosure* cl) {
1172     object_iterate(cl);
1173   }
1174 
1175   // Iterate over heap regions, in address order, terminating the
1176   // iteration early if the "doHeapRegion" method returns "true".
1177   void heap_region_iterate(HeapRegionClosure* blk) const;
1178 
1179   // Return the region with the given index. It assumes the index is valid.
1180   inline HeapRegion* region_at(uint index) const;
1181 
1182   // Return the next region (by index) that is part of the same
1183   // humongous object that hr is part of.
1184   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1185 
1186   // Calculate the region index of the given address. Given address must be
1187   // within the heap.
1188   inline uint addr_to_region(HeapWord* addr) const;
1189 
1190   inline HeapWord* bottom_addr_for_region(uint index) const;
1191 
1192   // Iterate over the heap regions in parallel. Assumes that this will be called
1193   // in parallel by a number of worker threads with distinct worker ids
1194   // in the range passed to the HeapRegionClaimer. Applies "blk->doHeapRegion"
1195   // to each of the regions, by attempting to claim the region using the
1196   // HeapRegionClaimer and, if successful, applying the closure to the claimed
1197   // region.
1198   void heap_region_par_iterate(HeapRegionClosure* cl,
1199                                uint worker_id,
1200                                HeapRegionClaimer* hrclaimer) const;
1201 
1202   // Iterate over the regions (if any) in the current collection set.
1203   void collection_set_iterate(HeapRegionClosure* blk);
1204 
1205   // Iterate over the regions (if any) in the current collection set. Starts the
1206   // iteration over the entire collection set so that the start regions of a given
1207   // worker id over the set active_workers are evenly spread across the set of
1208   // collection set regions.
1209   void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1210 
1211   HeapRegion* next_compaction_region(const HeapRegion* from) const;
1212 
1213   // Returns the HeapRegion that contains addr. addr must not be NULL.
1214   template <class T>
1215   inline HeapRegion* heap_region_containing(const T addr) const;
1216 
1217   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1218   // each address in the (reserved) heap is a member of exactly
1219   // one block.  The defining characteristic of a block is that it is
1220   // possible to find its size, and thus to progress forward to the next
1221   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1222   // represent Java objects, or they might be free blocks in a
1223   // free-list-based heap (or subheap), as long as the two kinds are
1224   // distinguishable and the size of each is determinable.
1225 
1226   // Returns the address of the start of the "block" that contains the
1227   // address "addr".  We say "blocks" instead of "object" since some heaps
1228   // may not pack objects densely; a chunk may either be an object or a
1229   // non-object.
1230   virtual HeapWord* block_start(const void* addr) const;
1231 
1232   // Requires "addr" to be the start of a chunk, and returns its size.
1233   // "addr + size" is required to be the start of a new chunk, or the end
1234   // of the active area of the heap.
1235   virtual size_t block_size(const HeapWord* addr) const;
1236 
1237   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1238   // the block is an object.
1239   virtual bool block_is_obj(const HeapWord* addr) const;
1240 
1241   // Section on thread-local allocation buffers (TLABs)
1242   // See CollectedHeap for semantics.
1243 
1244   bool supports_tlab_allocation() const;
1245   size_t tlab_capacity(Thread* ignored) const;
1246   size_t tlab_used(Thread* ignored) const;
1247   size_t max_tlab_size() const;
1248   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1249 
1250   // Can a compiler initialize a new object without store barriers?
1251   // This permission only extends from the creation of a new object
1252   // via a TLAB up to the first subsequent safepoint. If such permission
1253   // is granted for this heap type, the compiler promises to call
1254   // defer_store_barrier() below on any slow path allocation of
1255   // a new object for which such initializing store barriers will
1256   // have been elided. G1, like CMS, allows this, but should be
1257   // ready to provide a compensating write barrier as necessary
1258   // if that storage came out of a non-young region. The efficiency
1259   // of this implementation depends crucially on being able to
1260   // answer very efficiently in constant time whether a piece of
1261   // storage in the heap comes from a young region or not.
1262   // See ReduceInitialCardMarks.
1263   virtual bool can_elide_tlab_store_barriers() const {
1264     return true;
1265   }
1266 
1267   virtual bool card_mark_must_follow_store() const {
1268     return true;
1269   }
1270 
1271   inline bool is_in_young(const oop obj);
1272 
1273   virtual bool is_scavengable(const void* addr);
1274 
1275   // We don't need barriers for initializing stores to objects
1276   // in the young gen: for the SATB pre-barrier, there is no
1277   // pre-value that needs to be remembered; for the remembered-set
1278   // update logging post-barrier, we don't maintain remembered set
1279   // information for young gen objects.
1280   virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1281 
1282   // Returns "true" iff the given word_size is "very large".
1283   static bool is_humongous(size_t word_size) {
1284     // Note this has to be strictly greater-than as the TLABs
1285     // are capped at the humongous threshold and we want to
1286     // ensure that we don't try to allocate a TLAB as
1287     // humongous and that we don't allocate a humongous
1288     // object in a TLAB.
1289     return word_size > _humongous_object_threshold_in_words;
1290   }
1291 
1292   // Returns the humongous threshold for a specific region size
1293   static size_t humongous_threshold_for(size_t region_size) {
1294     return (region_size / 2);
1295   }
1296 
1297   // Returns the number of regions the humongous object of the given word size
1298   // requires.
1299   static size_t humongous_obj_size_in_regions(size_t word_size);
1300 
1301   // Print the maximum heap capacity.
1302   virtual size_t max_capacity() const;
1303 
1304   virtual jlong millis_since_last_gc();
1305 
1306 
1307   // Convenience function to be used in situations where the heap type can be
1308   // asserted to be this type.
1309   static G1CollectedHeap* heap();
1310 
1311   void set_region_short_lived_locked(HeapRegion* hr);
1312   // add appropriate methods for any other surv rate groups
1313 
1314   const G1SurvivorRegions* survivor() const { return &_survivor; }
1315 
1316   uint survivor_regions_count() const {
1317     return _survivor.length();
1318   }
1319 
1320   uint eden_regions_count() const {
1321     return _eden.length();
1322   }
1323 
1324   uint young_regions_count() const {
1325     return _eden.length() + _survivor.length();
1326   }
1327 
1328   uint old_regions_count() const { return _old_set.length(); }
1329 
1330   uint humongous_regions_count() const { return _humongous_set.length(); }
1331 
1332 #ifdef ASSERT
1333   bool check_young_list_empty();
1334 #endif
1335 
1336   // *** Stuff related to concurrent marking.  It's not clear to me that so
1337   // many of these need to be public.
1338 
1339   // The functions below are helper functions that a subclass of
1340   // "CollectedHeap" can use in the implementation of its virtual
1341   // functions.
1342   // This performs a concurrent marking of the live objects in a
1343   // bitmap off to the side.
1344   void doConcurrentMark();
1345 
1346   bool isMarkedNext(oop obj) const;
1347 
1348   // Determine if an object is dead, given the object and also
1349   // the region to which the object belongs. An object is dead
1350   // iff a) it was not allocated since the last mark, b) it
1351   // is not marked, and c) it is not in an archive region.
1352   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1353     return
1354       hr->is_obj_dead(obj, _cm->prevMarkBitMap()) &&
1355       !hr->is_archive();
1356   }
1357 
1358   // This function returns true when an object has been
1359   // around since the previous marking and hasn't yet
1360   // been marked during this marking, and is not in an archive region.
1361   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1362     return
1363       !hr->obj_allocated_since_next_marking(obj) &&
1364       !isMarkedNext(obj) &&
1365       !hr->is_archive();
1366   }
1367 
1368   // Determine if an object is dead, given only the object itself.
1369   // This will find the region to which the object belongs and
1370   // then call the region version of the same function.
1371 
1372   // Added if it is NULL it isn't dead.
1373 
1374   inline bool is_obj_dead(const oop obj) const;
1375 
1376   inline bool is_obj_ill(const oop obj) const;
1377 
1378   G1ConcurrentMark* concurrent_mark() const { return _cm; }
1379 
1380   // Refinement
1381 
1382   ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1383 
1384   // Optimized nmethod scanning support routines
1385 
1386   // Register the given nmethod with the G1 heap.
1387   virtual void register_nmethod(nmethod* nm);
1388 
1389   // Unregister the given nmethod from the G1 heap.
1390   virtual void unregister_nmethod(nmethod* nm);
1391 
1392   // Free up superfluous code root memory.
1393   void purge_code_root_memory();
1394 
1395   // Rebuild the strong code root lists for each region
1396   // after a full GC.
1397   void rebuild_strong_code_roots();
1398 
1399   // Partial cleaning used when class unloading is disabled.
1400   // Let the caller choose what structures to clean out:
1401   // - StringTable
1402   // - SymbolTable
1403   // - StringDeduplication structures
1404   void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1405 
1406   // Complete cleaning used when class unloading is enabled.
1407   // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1408   void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1409 
1410   // Redirty logged cards in the refinement queue.
1411   void redirty_logged_cards();
1412   // Verification
1413 
1414   // Perform any cleanup actions necessary before allowing a verification.
1415   virtual void prepare_for_verify();
1416 
1417   // Perform verification.
1418 
1419   // vo == UsePrevMarking  -> use "prev" marking information,
1420   // vo == UseNextMarking -> use "next" marking information
1421   // vo == UseMarkWord    -> use the mark word in the object header
1422   //
1423   // NOTE: Only the "prev" marking information is guaranteed to be
1424   // consistent most of the time, so most calls to this should use
1425   // vo == UsePrevMarking.
1426   // Currently, there is only one case where this is called with
1427   // vo == UseNextMarking, which is to verify the "next" marking
1428   // information at the end of remark.
1429   // Currently there is only one place where this is called with
1430   // vo == UseMarkWord, which is to verify the marking during a
1431   // full GC.
1432   void verify(VerifyOption vo);
1433 
1434   // WhiteBox testing support.
1435   virtual bool supports_concurrent_phase_control() const;
1436   virtual const char* const* concurrent_phases() const;
1437   virtual bool request_concurrent_phase(const char* phase);
1438 
1439   // The methods below are here for convenience and dispatch the
1440   // appropriate method depending on value of the given VerifyOption
1441   // parameter. The values for that parameter, and their meanings,
1442   // are the same as those above.
1443 
1444   bool is_obj_dead_cond(const oop obj,
1445                         const HeapRegion* hr,
1446                         const VerifyOption vo) const;
1447 
1448   bool is_obj_dead_cond(const oop obj,
1449                         const VerifyOption vo) const;
1450 
1451   G1HeapSummary create_g1_heap_summary();
1452   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1453 
1454   // Printing
1455 private:
1456   void print_heap_regions() const;
1457   void print_regions_on(outputStream* st) const;
1458 
1459 public:
1460   virtual void print_on(outputStream* st) const;
1461   virtual void print_extended_on(outputStream* st) const;
1462   virtual void print_on_error(outputStream* st) const;
1463 
1464   virtual void print_gc_threads_on(outputStream* st) const;
1465   virtual void gc_threads_do(ThreadClosure* tc) const;
1466 
1467   // Override
1468   void print_tracing_info() const;
1469 
1470   // The following two methods are helpful for debugging RSet issues.
1471   void print_cset_rsets() PRODUCT_RETURN;
1472   void print_all_rsets() PRODUCT_RETURN;
1473 
1474 public:
1475   size_t pending_card_num();
1476 
1477 protected:
1478   size_t _max_heap_capacity;
1479 };
1480 
1481 class G1ParEvacuateFollowersClosure : public VoidClosure {
1482 private:
1483   double _start_term;
1484   double _term_time;
1485   size_t _term_attempts;
1486 
1487   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1488   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1489 protected:
1490   G1CollectedHeap*              _g1h;
1491   G1ParScanThreadState*         _par_scan_state;
1492   RefToScanQueueSet*            _queues;
1493   ParallelTaskTerminator*       _terminator;
1494 
1495   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1496   RefToScanQueueSet*      queues()         { return _queues; }
1497   ParallelTaskTerminator* terminator()     { return _terminator; }
1498 
1499 public:
1500   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1501                                 G1ParScanThreadState* par_scan_state,
1502                                 RefToScanQueueSet* queues,
1503                                 ParallelTaskTerminator* terminator)
1504     : _g1h(g1h), _par_scan_state(par_scan_state),
1505       _queues(queues), _terminator(terminator),
1506       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1507 
1508   void do_void();
1509 
1510   double term_time() const { return _term_time; }
1511   size_t term_attempts() const { return _term_attempts; }
1512 
1513 private:
1514   inline bool offer_termination();
1515 };
1516 
1517 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP