1 /*
   2  * Copyright (c) 2001, 2015, 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/concurrentMark.hpp"
  29 #include "gc/g1/evacuationInfo.hpp"
  30 #include "gc/g1/g1AllocationContext.hpp"
  31 #include "gc/g1/g1BiasedArray.hpp"
  32 #include "gc/g1/g1CollectorState.hpp"
  33 #include "gc/g1/g1HRPrinter.hpp"
  34 #include "gc/g1/g1InCSetState.hpp"
  35 #include "gc/g1/g1MonitoringSupport.hpp"
  36 #include "gc/g1/g1EvacFailure.hpp"
  37 #include "gc/g1/g1EvacStats.hpp"
  38 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
  39 #include "gc/g1/g1YCTypes.hpp"
  40 #include "gc/g1/hSpaceCounters.hpp"
  41 #include "gc/g1/heapRegionManager.hpp"
  42 #include "gc/g1/heapRegionSet.hpp"
  43 #include "gc/g1/youngList.hpp"
  44 #include "gc/shared/barrierSet.hpp"
  45 #include "gc/shared/collectedHeap.hpp"
  46 #include "gc/shared/plab.hpp"
  47 #include "memory/memRegion.hpp"
  48 #include "utilities/stack.hpp"
  49 
  50 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  51 // It uses the "Garbage First" heap organization and algorithm, which
  52 // may combine concurrent marking with parallel, incremental compaction of
  53 // heap subsets that will yield large amounts of garbage.
  54 
  55 // Forward declarations
  56 class HeapRegion;
  57 class HRRSCleanupTask;
  58 class GenerationSpec;
  59 class OopsInHeapRegionClosure;
  60 class G1ParScanThreadState;
  61 class G1ParScanThreadStateSet;
  62 class G1KlassScanClosure;
  63 class G1ParScanThreadState;
  64 class ObjectClosure;
  65 class SpaceClosure;
  66 class CompactibleSpaceClosure;
  67 class Space;
  68 class G1CollectorPolicy;
  69 class G1RemSet;
  70 class HeapRegionRemSetIterator;
  71 class ConcurrentMark;
  72 class ConcurrentMarkThread;
  73 class ConcurrentG1Refine;
  74 class ConcurrentGCTimer;
  75 class GenerationCounters;
  76 class STWGCTimer;
  77 class G1NewTracer;
  78 class G1OldTracer;
  79 class EvacuationFailedInfo;
  80 class nmethod;
  81 class Ticks;
  82 class WorkGang;
  83 class G1Allocator;
  84 class G1ArchiveAllocator;
  85 class G1HeapVerifier;
  86 
  87 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
  88 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
  89 
  90 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
  91 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
  92 
  93 // The G1 STW is alive closure.
  94 // An instance is embedded into the G1CH and used as the
  95 // (optional) _is_alive_non_header closure in the STW
  96 // reference processor. It is also extensively used during
  97 // reference processing during STW evacuation pauses.
  98 class G1STWIsAliveClosure: public BoolObjectClosure {
  99   G1CollectedHeap* _g1;
 100 public:
 101   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 102   bool do_object_b(oop p);
 103 };
 104 
 105 class RefineCardTableEntryClosure;
 106 
 107 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 108  private:
 109   void reset_from_card_cache(uint start_idx, size_t num_regions);
 110  public:
 111   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 112 };
 113 
 114 class G1CollectedHeap : public CollectedHeap {
 115   friend class VM_CollectForMetadataAllocation;
 116   friend class VM_G1CollectForAllocation;
 117   friend class VM_G1CollectFull;
 118   friend class VM_G1IncCollectionPause;
 119   friend class VMStructs;
 120   friend class MutatorAllocRegion;
 121   friend class G1GCAllocRegion;
 122   friend class G1HeapVerifier;
 123 
 124   // Closures used in implementation.
 125   friend class G1ParScanThreadState;
 126   friend class G1ParScanThreadStateSet;
 127   friend class G1ParTask;
 128   friend class G1PLABAllocator;
 129   friend class G1PrepareCompactClosure;
 130 
 131   // Other related classes.
 132   friend class HeapRegionClaimer;
 133 
 134   // Testing classes.
 135   friend class G1CheckCSetFastTableClosure;
 136 
 137 private:
 138   WorkGang* _workers;
 139 
 140   static size_t _humongous_object_threshold_in_words;
 141 
 142   // The secondary free list which contains regions that have been
 143   // freed up during the cleanup process. This will be appended to
 144   // the master free list when appropriate.
 145   FreeRegionList _secondary_free_list;
 146 
 147   // It keeps track of the old regions.
 148   HeapRegionSet _old_set;
 149 
 150   // It keeps track of the humongous regions.
 151   HeapRegionSet _humongous_set;
 152 
 153   void eagerly_reclaim_humongous_regions();
 154 
 155   // The number of regions we could create by expansion.
 156   uint _expansion_regions;
 157 
 158   // The block offset table for the G1 heap.
 159   G1BlockOffsetTable* _bot;
 160 
 161   // Tears down the region sets / lists so that they are empty and the
 162   // regions on the heap do not belong to a region set / list. The
 163   // only exception is the humongous set which we leave unaltered. If
 164   // free_list_only is true, it will only tear down the master free
 165   // list. It is called before a Full GC (free_list_only == false) or
 166   // before heap shrinking (free_list_only == true).
 167   void tear_down_region_sets(bool free_list_only);
 168 
 169   // Rebuilds the region sets / lists so that they are repopulated to
 170   // reflect the contents of the heap. The only exception is the
 171   // humongous set which was not torn down in the first place. If
 172   // free_list_only is true, it will only rebuild the master free
 173   // list. It is called after a Full GC (free_list_only == false) or
 174   // after heap shrinking (free_list_only == true).
 175   void rebuild_region_sets(bool free_list_only);
 176 
 177   // Callback for region mapping changed events.
 178   G1RegionMappingChangedListener _listener;
 179 
 180   // The sequence of all heap regions in the heap.
 181   HeapRegionManager _hrm;
 182 
 183   // Manages all allocations with regions except humongous object allocations.
 184   G1Allocator* _allocator;
 185 
 186   // Manages all heap verification.
 187   G1HeapVerifier* _verifier;
 188 
 189   // Outside of GC pauses, the number of bytes used in all regions other
 190   // than the current allocation region(s).
 191   size_t _summary_bytes_used;
 192 
 193   void increase_used(size_t bytes);
 194   void decrease_used(size_t bytes);
 195 
 196   void set_used(size_t bytes);
 197 
 198   // Class that handles archive allocation ranges.
 199   G1ArchiveAllocator* _archive_allocator;
 200 
 201   // Statistics for each allocation context
 202   AllocationContextStats _allocation_context_stats;
 203 
 204   // GC allocation statistics policy for survivors.
 205   G1EvacStats _survivor_evac_stats;
 206 
 207   // GC allocation statistics policy for tenured objects.
 208   G1EvacStats _old_evac_stats;
 209 
 210   // It specifies whether we should attempt to expand the heap after a
 211   // region allocation failure. If heap expansion fails we set this to
 212   // false so that we don't re-attempt the heap expansion (it's likely
 213   // that subsequent expansion attempts will also fail if one fails).
 214   // Currently, it is only consulted during GC and it's reset at the
 215   // start of each GC.
 216   bool _expand_heap_after_alloc_failure;
 217 
 218   // Helper for monitoring and management support.
 219   G1MonitoringSupport* _g1mm;
 220 
 221   // Records whether the region at the given index is (still) a
 222   // candidate for eager reclaim.  Only valid for humongous start
 223   // regions; other regions have unspecified values.  Humongous start
 224   // regions are initialized at start of collection pause, with
 225   // candidates removed from the set as they are found reachable from
 226   // roots or the young generation.
 227   class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
 228    protected:
 229     bool default_value() const { return false; }
 230    public:
 231     void clear() { G1BiasedMappedArray<bool>::clear(); }
 232     void set_candidate(uint region, bool value) {
 233       set_by_index(region, value);
 234     }
 235     bool is_candidate(uint region) {
 236       return get_by_index(region);
 237     }
 238   };
 239 
 240   HumongousReclaimCandidates _humongous_reclaim_candidates;
 241   // Stores whether during humongous object registration we found candidate regions.
 242   // If not, we can skip a few steps.
 243   bool _has_humongous_reclaim_candidates;
 244 
 245   volatile unsigned _gc_time_stamp;
 246 
 247   G1HRPrinter _hr_printer;
 248 
 249   // It decides whether an explicit GC should start a concurrent cycle
 250   // instead of doing a STW GC. Currently, a concurrent cycle is
 251   // explicitly started if:
 252   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 253   // (b) cause == _g1_humongous_allocation
 254   // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 255   // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
 256   // (e) cause == _update_allocation_context_stats_inc
 257   // (f) cause == _wb_conc_mark
 258   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 259 
 260   // indicates whether we are in young or mixed GC mode
 261   G1CollectorState _collector_state;
 262 
 263   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 264   // concurrent cycles) we have started.
 265   volatile uint _old_marking_cycles_started;
 266 
 267   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 268   // concurrent cycles) we have completed.
 269   volatile uint _old_marking_cycles_completed;
 270 
 271   bool _heap_summary_sent;
 272 
 273   // This is a non-product method that is helpful for testing. It is
 274   // called at the end of a GC and artificially expands the heap by
 275   // allocating a number of dead regions. This way we can induce very
 276   // frequent marking cycles and stress the cleanup / concurrent
 277   // cleanup code more (as all the regions that will be allocated by
 278   // this method will be found dead by the marking cycle).
 279   void allocate_dummy_regions() PRODUCT_RETURN;
 280 
 281   // Clear RSets after a compaction. It also resets the GC time stamps.
 282   void clear_rsets_post_compaction();
 283 
 284   // If the HR printer is active, dump the state of the regions in the
 285   // heap after a compaction.
 286   void print_hrm_post_compaction();
 287 
 288   // Create a memory mapper for auxiliary data structures of the given size and
 289   // translation factor.
 290   static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
 291                                                          size_t size,
 292                                                          size_t translation_factor);
 293 
 294   void log_gc_footer(jlong pause_time_counter);
 295 
 296   void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 297 
 298   void process_weak_jni_handles();
 299 
 300   // These are macros so that, if the assert fires, we get the correct
 301   // line number, file, etc.
 302 
 303 #define heap_locking_asserts_params(_extra_message_)                          \
 304   "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",            \
 305   (_extra_message_),                                                          \
 306   BOOL_TO_STR(Heap_lock->owned_by_self()),                                    \
 307   BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),                       \
 308   BOOL_TO_STR(Thread::current()->is_VM_thread())
 309 
 310 #define assert_heap_locked()                                                  \
 311   do {                                                                        \
 312     assert(Heap_lock->owned_by_self(),                                        \
 313            heap_locking_asserts_params("should be holding the Heap_lock"));   \
 314   } while (0)
 315 
 316 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 317   do {                                                                        \
 318     assert(Heap_lock->owned_by_self() ||                                      \
 319            (SafepointSynchronize::is_at_safepoint() &&                        \
 320              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 321            heap_locking_asserts_params("should be holding the Heap_lock or "  \
 322                                         "should be at a safepoint"));         \
 323   } while (0)
 324 
 325 #define assert_heap_locked_and_not_at_safepoint()                             \
 326   do {                                                                        \
 327     assert(Heap_lock->owned_by_self() &&                                      \
 328                                     !SafepointSynchronize::is_at_safepoint(), \
 329           heap_locking_asserts_params("should be holding the Heap_lock and "  \
 330                                        "should not be at a safepoint"));      \
 331   } while (0)
 332 
 333 #define assert_heap_not_locked()                                              \
 334   do {                                                                        \
 335     assert(!Heap_lock->owned_by_self(),                                       \
 336         heap_locking_asserts_params("should not be holding the Heap_lock"));  \
 337   } while (0)
 338 
 339 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 340   do {                                                                        \
 341     assert(!Heap_lock->owned_by_self() &&                                     \
 342                                     !SafepointSynchronize::is_at_safepoint(), \
 343       heap_locking_asserts_params("should not be holding the Heap_lock and "  \
 344                                    "should not be at a safepoint"));          \
 345   } while (0)
 346 
 347 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 348   do {                                                                        \
 349     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 350               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 351            heap_locking_asserts_params("should be at a safepoint"));          \
 352   } while (0)
 353 
 354 #define assert_not_at_safepoint()                                             \
 355   do {                                                                        \
 356     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 357            heap_locking_asserts_params("should not be at a safepoint"));      \
 358   } while (0)
 359 
 360 protected:
 361 
 362   // The young region list.
 363   YoungList*  _young_list;
 364 
 365   // The current policy object for the collector.
 366   G1CollectorPolicy* _g1_policy;
 367 
 368   // This is the second level of trying to allocate a new region. If
 369   // new_region() didn't find a region on the free_list, this call will
 370   // check whether there's anything available on the
 371   // secondary_free_list and/or wait for more regions to appear on
 372   // that list, if _free_regions_coming is set.
 373   HeapRegion* new_region_try_secondary_free_list(bool is_old);
 374 
 375   // Try to allocate a single non-humongous HeapRegion sufficient for
 376   // an allocation of the given word_size. If do_expand is true,
 377   // attempt to expand the heap if necessary to satisfy the allocation
 378   // request. If the region is to be used as an old region or for a
 379   // humongous object, set is_old to true. If not, to false.
 380   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 381 
 382   // Initialize a contiguous set of free regions of length num_regions
 383   // and starting at index first so that they appear as a single
 384   // humongous region.
 385   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 386                                                       uint num_regions,
 387                                                       size_t word_size,
 388                                                       AllocationContext_t context);
 389 
 390   // Attempt to allocate a humongous object of the given size. Return
 391   // NULL if unsuccessful.
 392   HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
 393 
 394   // The following two methods, allocate_new_tlab() and
 395   // mem_allocate(), are the two main entry points from the runtime
 396   // into the G1's allocation routines. They have the following
 397   // assumptions:
 398   //
 399   // * They should both be called outside safepoints.
 400   //
 401   // * They should both be called without holding the Heap_lock.
 402   //
 403   // * All allocation requests for new TLABs should go to
 404   //   allocate_new_tlab().
 405   //
 406   // * All non-TLAB allocation requests should go to mem_allocate().
 407   //
 408   // * If either call cannot satisfy the allocation request using the
 409   //   current allocating region, they will try to get a new one. If
 410   //   this fails, they will attempt to do an evacuation pause and
 411   //   retry the allocation.
 412   //
 413   // * If all allocation attempts fail, even after trying to schedule
 414   //   an evacuation pause, allocate_new_tlab() will return NULL,
 415   //   whereas mem_allocate() will attempt a heap expansion and/or
 416   //   schedule a Full GC.
 417   //
 418   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 419   //   should never be called with word_size being humongous. All
 420   //   humongous allocation requests should go to mem_allocate() which
 421   //   will satisfy them with a special path.
 422 
 423   virtual HeapWord* allocate_new_tlab(size_t word_size);
 424 
 425   virtual HeapWord* mem_allocate(size_t word_size,
 426                                  bool*  gc_overhead_limit_was_exceeded);
 427 
 428   // The following three methods take a gc_count_before_ret
 429   // parameter which is used to return the GC count if the method
 430   // returns NULL. Given that we are required to read the GC count
 431   // while holding the Heap_lock, and these paths will take the
 432   // Heap_lock at some point, it's easier to get them to read the GC
 433   // count while holding the Heap_lock before they return NULL instead
 434   // of the caller (namely: mem_allocate()) having to also take the
 435   // Heap_lock just to read the GC count.
 436 
 437   // First-level mutator allocation attempt: try to allocate out of
 438   // the mutator alloc region without taking the Heap_lock. This
 439   // should only be used for non-humongous allocations.
 440   inline HeapWord* attempt_allocation(size_t word_size,
 441                                       uint* gc_count_before_ret,
 442                                       uint* gclocker_retry_count_ret);
 443 
 444   // Second-level mutator allocation attempt: take the Heap_lock and
 445   // retry the allocation attempt, potentially scheduling a GC
 446   // pause. This should only be used for non-humongous allocations.
 447   HeapWord* attempt_allocation_slow(size_t word_size,
 448                                     AllocationContext_t context,
 449                                     uint* gc_count_before_ret,
 450                                     uint* gclocker_retry_count_ret);
 451 
 452   // Takes the Heap_lock and attempts a humongous allocation. It can
 453   // potentially schedule a GC pause.
 454   HeapWord* attempt_allocation_humongous(size_t word_size,
 455                                          uint* gc_count_before_ret,
 456                                          uint* gclocker_retry_count_ret);
 457 
 458   // Allocation attempt that should be called during safepoints (e.g.,
 459   // at the end of a successful GC). expect_null_mutator_alloc_region
 460   // specifies whether the mutator alloc region is expected to be NULL
 461   // or not.
 462   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 463                                             AllocationContext_t context,
 464                                             bool expect_null_mutator_alloc_region);
 465 
 466   // These methods are the "callbacks" from the G1AllocRegion class.
 467 
 468   // For mutator alloc regions.
 469   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 470   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 471                                    size_t allocated_bytes);
 472 
 473   // For GC alloc regions.
 474   HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
 475                                   InCSetState dest);
 476   void retire_gc_alloc_region(HeapRegion* alloc_region,
 477                               size_t allocated_bytes, InCSetState dest);
 478 
 479   // - if explicit_gc is true, the GC is for a System.gc() etc,
 480   //   otherwise it's for a failed allocation.
 481   // - if clear_all_soft_refs is true, all soft references should be
 482   //   cleared during the GC.
 483   // - it returns false if it is unable to do the collection due to the
 484   //   GC locker being active, true otherwise.
 485   bool do_full_collection(bool explicit_gc,
 486                           bool clear_all_soft_refs);
 487 
 488   // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
 489   virtual void do_full_collection(bool clear_all_soft_refs);
 490 
 491   // Resize the heap if necessary after a full collection.
 492   void resize_if_necessary_after_full_collection();
 493 
 494   // Callback from VM_G1CollectForAllocation operation.
 495   // This function does everything necessary/possible to satisfy a
 496   // failed allocation request (including collection, expansion, etc.)
 497   HeapWord* satisfy_failed_allocation(size_t word_size,
 498                                       AllocationContext_t context,
 499                                       bool* succeeded);
 500 private:
 501   // Helper method for satisfy_failed_allocation()
 502   HeapWord* satisfy_failed_allocation_helper(size_t word_size,
 503                                              AllocationContext_t context,
 504                                              bool do_gc,
 505                                              bool clear_all_soft_refs,
 506                                              bool expect_null_mutator_alloc_region,
 507                                              bool* gc_succeeded);
 508 
 509 protected:
 510   // Attempting to expand the heap sufficiently
 511   // to support an allocation of the given "word_size".  If
 512   // successful, perform the allocation and return the address of the
 513   // allocated block, or else "NULL".
 514   HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
 515 
 516   // Process any reference objects discovered during
 517   // an incremental evacuation pause.
 518   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 519 
 520   // Enqueue any remaining discovered references
 521   // after processing.
 522   void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 523 
 524 public:
 525   WorkGang* workers() const { return _workers; }
 526 
 527   G1Allocator* allocator() {
 528     return _allocator;
 529   }
 530 
 531   G1HeapVerifier* verifier() {
 532     return _verifier;
 533   }
 534 
 535   G1MonitoringSupport* g1mm() {
 536     assert(_g1mm != NULL, "should have been initialized");
 537     return _g1mm;
 538   }
 539 
 540   // Expand the garbage-first heap by at least the given size (in bytes!).
 541   // Returns true if the heap was expanded by the requested amount;
 542   // false otherwise.
 543   // (Rounds up to a HeapRegion boundary.)
 544   bool expand(size_t expand_bytes, double* expand_time_ms = NULL);
 545 
 546   // Returns the PLAB statistics for a given destination.
 547   inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
 548 
 549   // Determines PLAB size for a given destination.
 550   inline size_t desired_plab_sz(InCSetState dest);
 551 
 552   inline AllocationContextStats& allocation_context_stats();
 553 
 554   // Do anything common to GC's.
 555   void gc_prologue(bool full);
 556   void gc_epilogue(bool full);
 557 
 558   // Modify the reclaim candidate set and test for presence.
 559   // These are only valid for starts_humongous regions.
 560   inline void set_humongous_reclaim_candidate(uint region, bool value);
 561   inline bool is_humongous_reclaim_candidate(uint region);
 562 
 563   // Remove from the reclaim candidate set.  Also remove from the
 564   // collection set so that later encounters avoid the slow path.
 565   inline void set_humongous_is_live(oop obj);
 566 
 567   // Register the given region to be part of the collection set.
 568   inline void register_humongous_region_with_cset(uint index);
 569   // Register regions with humongous objects (actually on the start region) in
 570   // the in_cset_fast_test table.
 571   void register_humongous_regions_with_cset();
 572   // We register a region with the fast "in collection set" test. We
 573   // simply set to true the array slot corresponding to this region.
 574   void register_young_region_with_cset(HeapRegion* r) {
 575     _in_cset_fast_test.set_in_young(r->hrm_index());
 576   }
 577   void register_old_region_with_cset(HeapRegion* r) {
 578     _in_cset_fast_test.set_in_old(r->hrm_index());
 579   }
 580   inline void register_ext_region_with_cset(HeapRegion* r) {
 581     _in_cset_fast_test.set_ext(r->hrm_index());
 582   }
 583   void clear_in_cset(const HeapRegion* hr) {
 584     _in_cset_fast_test.clear(hr);
 585   }
 586 
 587   void clear_cset_fast_test() {
 588     _in_cset_fast_test.clear();
 589   }
 590 
 591   bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
 592 
 593   // This is called at the start of either a concurrent cycle or a Full
 594   // GC to update the number of old marking cycles started.
 595   void increment_old_marking_cycles_started();
 596 
 597   // This is called at the end of either a concurrent cycle or a Full
 598   // GC to update the number of old marking cycles completed. Those two
 599   // can happen in a nested fashion, i.e., we start a concurrent
 600   // cycle, a Full GC happens half-way through it which ends first,
 601   // and then the cycle notices that a Full GC happened and ends
 602   // too. The concurrent parameter is a boolean to help us do a bit
 603   // tighter consistency checking in the method. If concurrent is
 604   // false, the caller is the inner caller in the nesting (i.e., the
 605   // Full GC). If concurrent is true, the caller is the outer caller
 606   // in this nesting (i.e., the concurrent cycle). Further nesting is
 607   // not currently supported. The end of this call also notifies
 608   // the FullGCCount_lock in case a Java thread is waiting for a full
 609   // GC to happen (e.g., it called System.gc() with
 610   // +ExplicitGCInvokesConcurrent).
 611   void increment_old_marking_cycles_completed(bool concurrent);
 612 
 613   uint old_marking_cycles_completed() {
 614     return _old_marking_cycles_completed;
 615   }
 616 
 617   void register_concurrent_cycle_start(const Ticks& start_time);
 618   void register_concurrent_cycle_end();
 619   void trace_heap_after_concurrent_cycle();
 620 
 621   G1HRPrinter* hr_printer() { return &_hr_printer; }
 622 
 623   // Allocates a new heap region instance.
 624   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 625 
 626   // Allocate the highest free region in the reserved heap. This will commit
 627   // regions as necessary.
 628   HeapRegion* alloc_highest_free_region();
 629 
 630   // Frees a non-humongous region by initializing its contents and
 631   // adding it to the free list that's passed as a parameter (this is
 632   // usually a local list which will be appended to the master free
 633   // list later). The used bytes of freed regions are accumulated in
 634   // pre_used. If par is true, the region's RSet will not be freed
 635   // up. The assumption is that this will be done later.
 636   // The locked parameter indicates if the caller has already taken
 637   // care of proper synchronization. This may allow some optimizations.
 638   void free_region(HeapRegion* hr,
 639                    FreeRegionList* free_list,
 640                    bool par,
 641                    bool locked = false);
 642 
 643   // It dirties the cards that cover the block so that the post
 644   // write barrier never queues anything when updating objects on this
 645   // block. It is assumed (and in fact we assert) that the block
 646   // belongs to a young region.
 647   inline void dirty_young_block(HeapWord* start, size_t word_size);
 648 
 649   // Frees a humongous region by collapsing it into individual regions
 650   // and calling free_region() for each of them. The freed regions
 651   // will be added to the free list that's passed as a parameter (this
 652   // is usually a local list which will be appended to the master free
 653   // list later). The used bytes of freed regions are accumulated in
 654   // pre_used. If par is true, the region's RSet will not be freed
 655   // up. The assumption is that this will be done later.
 656   void free_humongous_region(HeapRegion* hr,
 657                              FreeRegionList* free_list,
 658                              bool par);
 659 
 660   // Facility for allocating in 'archive' regions in high heap memory and
 661   // recording the allocated ranges. These should all be called from the
 662   // VM thread at safepoints, without the heap lock held. They can be used
 663   // to create and archive a set of heap regions which can be mapped at the
 664   // same fixed addresses in a subsequent JVM invocation.
 665   void begin_archive_alloc_range();
 666 
 667   // Check if the requested size would be too large for an archive allocation.
 668   bool is_archive_alloc_too_large(size_t word_size);
 669 
 670   // Allocate memory of the requested size from the archive region. This will
 671   // return NULL if the size is too large or if no memory is available. It
 672   // does not trigger a garbage collection.
 673   HeapWord* archive_mem_allocate(size_t word_size);
 674 
 675   // Optionally aligns the end address and returns the allocated ranges in
 676   // an array of MemRegions in order of ascending addresses.
 677   void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
 678                                size_t end_alignment_in_bytes = 0);
 679 
 680   // Facility for allocating a fixed range within the heap and marking
 681   // the containing regions as 'archive'. For use at JVM init time, when the
 682   // caller may mmap archived heap data at the specified range(s).
 683   // Verify that the MemRegions specified in the argument array are within the
 684   // reserved heap.
 685   bool check_archive_addresses(MemRegion* range, size_t count);
 686 
 687   // Commit the appropriate G1 regions containing the specified MemRegions
 688   // and mark them as 'archive' regions. The regions in the array must be
 689   // non-overlapping and in order of ascending address.
 690   bool alloc_archive_regions(MemRegion* range, size_t count);
 691 
 692   // Insert any required filler objects in the G1 regions around the specified
 693   // ranges to make the regions parseable. This must be called after
 694   // alloc_archive_regions, and after class loading has occurred.
 695   void fill_archive_regions(MemRegion* range, size_t count);
 696 
 697   // For each of the specified MemRegions, uncommit the containing G1 regions
 698   // which had been allocated by alloc_archive_regions. This should be called
 699   // rather than fill_archive_regions at JVM init time if the archive file
 700   // mapping failed, with the same non-overlapping and sorted MemRegion array.
 701   void dealloc_archive_regions(MemRegion* range, size_t count);
 702 
 703 protected:
 704 
 705   // Shrink the garbage-first heap by at most the given size (in bytes!).
 706   // (Rounds down to a HeapRegion boundary.)
 707   virtual void shrink(size_t expand_bytes);
 708   void shrink_helper(size_t expand_bytes);
 709 
 710   #if TASKQUEUE_STATS
 711   static void print_taskqueue_stats_hdr(outputStream* const st);
 712   void print_taskqueue_stats() const;
 713   void reset_taskqueue_stats();
 714   #endif // TASKQUEUE_STATS
 715 
 716   // Schedule the VM operation that will do an evacuation pause to
 717   // satisfy an allocation request of word_size. *succeeded will
 718   // return whether the VM operation was successful (it did do an
 719   // evacuation pause) or not (another thread beat us to it or the GC
 720   // locker was active). Given that we should not be holding the
 721   // Heap_lock when we enter this method, we will pass the
 722   // gc_count_before (i.e., total_collections()) as a parameter since
 723   // it has to be read while holding the Heap_lock. Currently, both
 724   // methods that call do_collection_pause() release the Heap_lock
 725   // before the call, so it's easy to read gc_count_before just before.
 726   HeapWord* do_collection_pause(size_t         word_size,
 727                                 uint           gc_count_before,
 728                                 bool*          succeeded,
 729                                 GCCause::Cause gc_cause);
 730 
 731   void wait_for_root_region_scanning();
 732 
 733   // The guts of the incremental collection pause, executed by the vm
 734   // thread. It returns false if it is unable to do the collection due
 735   // to the GC locker being active, true otherwise
 736   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 737 
 738   // Actually do the work of evacuating the collection set.
 739   virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
 740 
 741   void pre_evacuate_collection_set();
 742   void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
 743 
 744   // Print the header for the per-thread termination statistics.
 745   static void print_termination_stats_hdr();
 746   // Print actual per-thread termination statistics.
 747   void print_termination_stats(uint worker_id,
 748                                double elapsed_ms,
 749                                double strong_roots_ms,
 750                                double term_ms,
 751                                size_t term_attempts,
 752                                size_t alloc_buffer_waste,
 753                                size_t undo_waste) const;
 754   // Update object copying statistics.
 755   void record_obj_copy_mem_stats();
 756 
 757   // The g1 remembered set of the heap.
 758   G1RemSet* _g1_rem_set;
 759 
 760   // A set of cards that cover the objects for which the Rsets should be updated
 761   // concurrently after the collection.
 762   DirtyCardQueueSet _dirty_card_queue_set;
 763 
 764   // The closure used to refine a single card.
 765   RefineCardTableEntryClosure* _refine_cte_cl;
 766 
 767   // After a collection pause, make the regions in the CS into free
 768   // regions.
 769   void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 770 
 771   // Abandon the current collection set without recording policy
 772   // statistics or updating free lists.
 773   void abandon_collection_set(HeapRegion* cs_head);
 774 
 775   // The concurrent marker (and the thread it runs in.)
 776   ConcurrentMark* _cm;
 777   ConcurrentMarkThread* _cmThread;
 778 
 779   // The concurrent refiner.
 780   ConcurrentG1Refine* _cg1r;
 781 
 782   // The parallel task queues
 783   RefToScanQueueSet *_task_queues;
 784 
 785   // True iff a evacuation has failed in the current collection.
 786   bool _evacuation_failed;
 787 
 788   EvacuationFailedInfo* _evacuation_failed_info_array;
 789 
 790   // Failed evacuations cause some logical from-space objects to have
 791   // forwarding pointers to themselves.  Reset them.
 792   void remove_self_forwarding_pointers();
 793 
 794   // Restore the preserved mark words for objects with self-forwarding pointers.
 795   void restore_preserved_marks();
 796 
 797   // Restore the objects in the regions in the collection set after an
 798   // evacuation failure.
 799   void restore_after_evac_failure();
 800 
 801   // Stores marks with the corresponding oop that we need to preserve during evacuation
 802   // failure.
 803   OopAndMarkOopStack*  _preserved_objs;
 804 
 805   // Preserve the mark of "obj", if necessary, in preparation for its mark
 806   // word being overwritten with a self-forwarding-pointer.
 807   void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
 808 
 809 #ifndef PRODUCT
 810   // Support for forcing evacuation failures. Analogous to
 811   // PromotionFailureALot for the other collectors.
 812 
 813   // Records whether G1EvacuationFailureALot should be in effect
 814   // for the current GC
 815   bool _evacuation_failure_alot_for_current_gc;
 816 
 817   // Used to record the GC number for interval checking when
 818   // determining whether G1EvaucationFailureALot is in effect
 819   // for the current GC.
 820   size_t _evacuation_failure_alot_gc_number;
 821 
 822   // Count of the number of evacuations between failures.
 823   volatile size_t _evacuation_failure_alot_count;
 824 
 825   // Set whether G1EvacuationFailureALot should be in effect
 826   // for the current GC (based upon the type of GC and which
 827   // command line flags are set);
 828   inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
 829                                                   bool during_initial_mark,
 830                                                   bool during_marking);
 831 
 832   inline void set_evacuation_failure_alot_for_current_gc();
 833 
 834   // Return true if it's time to cause an evacuation failure.
 835   inline bool evacuation_should_fail();
 836 
 837   // Reset the G1EvacuationFailureALot counters.  Should be called at
 838   // the end of an evacuation pause in which an evacuation failure occurred.
 839   inline void reset_evacuation_should_fail();
 840 #endif // !PRODUCT
 841 
 842   // ("Weak") Reference processing support.
 843   //
 844   // G1 has 2 instances of the reference processor class. One
 845   // (_ref_processor_cm) handles reference object discovery
 846   // and subsequent processing during concurrent marking cycles.
 847   //
 848   // The other (_ref_processor_stw) handles reference object
 849   // discovery and processing during full GCs and incremental
 850   // evacuation pauses.
 851   //
 852   // During an incremental pause, reference discovery will be
 853   // temporarily disabled for _ref_processor_cm and will be
 854   // enabled for _ref_processor_stw. At the end of the evacuation
 855   // pause references discovered by _ref_processor_stw will be
 856   // processed and discovery will be disabled. The previous
 857   // setting for reference object discovery for _ref_processor_cm
 858   // will be re-instated.
 859   //
 860   // At the start of marking:
 861   //  * Discovery by the CM ref processor is verified to be inactive
 862   //    and it's discovered lists are empty.
 863   //  * Discovery by the CM ref processor is then enabled.
 864   //
 865   // At the end of marking:
 866   //  * Any references on the CM ref processor's discovered
 867   //    lists are processed (possibly MT).
 868   //
 869   // At the start of full GC we:
 870   //  * Disable discovery by the CM ref processor and
 871   //    empty CM ref processor's discovered lists
 872   //    (without processing any entries).
 873   //  * Verify that the STW ref processor is inactive and it's
 874   //    discovered lists are empty.
 875   //  * Temporarily set STW ref processor discovery as single threaded.
 876   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 877   //    field.
 878   //  * Finally enable discovery by the STW ref processor.
 879   //
 880   // The STW ref processor is used to record any discovered
 881   // references during the full GC.
 882   //
 883   // At the end of a full GC we:
 884   //  * Enqueue any reference objects discovered by the STW ref processor
 885   //    that have non-live referents. This has the side-effect of
 886   //    making the STW ref processor inactive by disabling discovery.
 887   //  * Verify that the CM ref processor is still inactive
 888   //    and no references have been placed on it's discovered
 889   //    lists (also checked as a precondition during initial marking).
 890 
 891   // The (stw) reference processor...
 892   ReferenceProcessor* _ref_processor_stw;
 893 
 894   STWGCTimer* _gc_timer_stw;
 895   ConcurrentGCTimer* _gc_timer_cm;
 896 
 897   G1OldTracer* _gc_tracer_cm;
 898   G1NewTracer* _gc_tracer_stw;
 899 
 900   // During reference object discovery, the _is_alive_non_header
 901   // closure (if non-null) is applied to the referent object to
 902   // determine whether the referent is live. If so then the
 903   // reference object does not need to be 'discovered' and can
 904   // be treated as a regular oop. This has the benefit of reducing
 905   // the number of 'discovered' reference objects that need to
 906   // be processed.
 907   //
 908   // Instance of the is_alive closure for embedding into the
 909   // STW reference processor as the _is_alive_non_header field.
 910   // Supplying a value for the _is_alive_non_header field is
 911   // optional but doing so prevents unnecessary additions to
 912   // the discovered lists during reference discovery.
 913   G1STWIsAliveClosure _is_alive_closure_stw;
 914 
 915   // The (concurrent marking) reference processor...
 916   ReferenceProcessor* _ref_processor_cm;
 917 
 918   // Instance of the concurrent mark is_alive closure for embedding
 919   // into the Concurrent Marking reference processor as the
 920   // _is_alive_non_header field. Supplying a value for the
 921   // _is_alive_non_header field is optional but doing so prevents
 922   // unnecessary additions to the discovered lists during reference
 923   // discovery.
 924   G1CMIsAliveClosure _is_alive_closure_cm;
 925 
 926   // Cache used by G1CollectedHeap::start_cset_region_for_worker().
 927   HeapRegion** _worker_cset_start_region;
 928 
 929   // Time stamp to validate the regions recorded in the cache
 930   // used by G1CollectedHeap::start_cset_region_for_worker().
 931   // The heap region entry for a given worker is valid iff
 932   // the associated time stamp value matches the current value
 933   // of G1CollectedHeap::_gc_time_stamp.
 934   uint* _worker_cset_start_region_time_stamp;
 935 
 936   volatile bool _free_regions_coming;
 937 
 938 public:
 939 
 940   void set_refine_cte_cl_concurrency(bool concurrent);
 941 
 942   RefToScanQueue *task_queue(uint i) const;
 943 
 944   uint num_task_queues() const;
 945 
 946   // A set of cards where updates happened during the GC
 947   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 948 
 949   // Create a G1CollectedHeap with the specified policy.
 950   // Must call the initialize method afterwards.
 951   // May not return if something goes wrong.
 952   G1CollectedHeap(G1CollectorPolicy* policy);
 953 
 954   // Initialize the G1CollectedHeap to have the initial and
 955   // maximum sizes and remembered and barrier sets
 956   // specified by the policy object.
 957   jint initialize();
 958 
 959   virtual void stop();
 960 
 961   // Return the (conservative) maximum heap alignment for any G1 heap
 962   static size_t conservative_max_heap_alignment();
 963 
 964   // Does operations required after initialization has been done.
 965   void post_initialize();
 966 
 967   // Initialize weak reference processing.
 968   void ref_processing_init();
 969 
 970   virtual Name kind() const {
 971     return CollectedHeap::G1CollectedHeap;
 972   }
 973 
 974   virtual const char* name() const {
 975     return "G1";
 976   }
 977 
 978   const G1CollectorState* collector_state() const { return &_collector_state; }
 979   G1CollectorState* collector_state() { return &_collector_state; }
 980 
 981   // The current policy object for the collector.
 982   G1CollectorPolicy* g1_policy() const { return _g1_policy; }
 983 
 984   virtual CollectorPolicy* collector_policy() const;
 985 
 986   // Adaptive size policy.  No such thing for g1.
 987   virtual AdaptiveSizePolicy* size_policy() { return NULL; }
 988 
 989   // The rem set and barrier set.
 990   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
 991 
 992   void scrub_rem_set(BitMap* region_bm, BitMap* card_bm);
 993 
 994   unsigned get_gc_time_stamp() {
 995     return _gc_time_stamp;
 996   }
 997 
 998   inline void reset_gc_time_stamp();
 999 
1000   void check_gc_time_stamps() PRODUCT_RETURN;
1001 
1002   inline void increment_gc_time_stamp();
1003 
1004   // Reset the given region's GC timestamp. If it's starts humongous,
1005   // also reset the GC timestamp of its corresponding
1006   // continues humongous regions too.
1007   void reset_gc_time_stamps(HeapRegion* hr);
1008 
1009   // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1010   void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1011 
1012   // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1013   void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1014 
1015   // The shared block offset table array.
1016   G1BlockOffsetTable* bot() const { return _bot; }
1017 
1018   // Reference Processing accessors
1019 
1020   // The STW reference processor....
1021   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1022 
1023   G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1024 
1025   // The Concurrent Marking reference processor...
1026   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1027 
1028   ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1029   G1OldTracer* gc_tracer_cm() const { return _gc_tracer_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. Slow implementation.
1132   bool obj_in_cs(oop obj);
1133 
1134   inline bool is_in_cset(const HeapRegion *hr);
1135   inline bool is_in_cset(oop obj);
1136 
1137   inline bool is_in_cset_or_humongous(const oop obj);
1138 
1139  private:
1140   // This array is used for a quick test on whether a reference points into
1141   // the collection set or not. Each of the array's elements denotes whether the
1142   // corresponding region is in the collection set or not.
1143   G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1144 
1145  public:
1146 
1147   inline InCSetState in_cset_state(const oop obj);
1148 
1149   // Return "TRUE" iff the given object address is in the reserved
1150   // region of g1.
1151   bool is_in_g1_reserved(const void* p) const {
1152     return _hrm.reserved().contains(p);
1153   }
1154 
1155   // Returns a MemRegion that corresponds to the space that has been
1156   // reserved for the heap
1157   MemRegion g1_reserved() const {
1158     return _hrm.reserved();
1159   }
1160 
1161   virtual bool is_in_closed_subset(const void* p) const;
1162 
1163   G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1164     return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1165   }
1166 
1167   // This resets the card table to all zeros.  It is used after
1168   // a collection pause which used the card table to claim cards.
1169   void cleanUpCardTable();
1170 
1171   // Iteration functions.
1172 
1173   // Iterate over all objects, calling "cl.do_object" on each.
1174   virtual void object_iterate(ObjectClosure* cl);
1175 
1176   virtual void safe_object_iterate(ObjectClosure* cl) {
1177     object_iterate(cl);
1178   }
1179 
1180   // Iterate over heap regions, in address order, terminating the
1181   // iteration early if the "doHeapRegion" method returns "true".
1182   void heap_region_iterate(HeapRegionClosure* blk) const;
1183 
1184   // Return the region with the given index. It assumes the index is valid.
1185   inline HeapRegion* region_at(uint index) const;
1186 
1187   // Return the next region (by index) that is part of the same
1188   // humongous object that hr is part of.
1189   inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1190 
1191   // Calculate the region index of the given address. Given address must be
1192   // within the heap.
1193   inline uint addr_to_region(HeapWord* addr) const;
1194 
1195   inline HeapWord* bottom_addr_for_region(uint index) const;
1196 
1197   // Iterate over the heap regions in parallel. Assumes that this will be called
1198   // in parallel by ParallelGCThreads worker threads with distinct worker ids
1199   // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1200   // to each of the regions, by attempting to claim the region using the
1201   // HeapRegionClaimer and, if successful, applying the closure to the claimed
1202   // region. The concurrent argument should be set to true if iteration is
1203   // performed concurrently, during which no assumptions are made for consistent
1204   // attributes of the heap regions (as they might be modified while iterating).
1205   void heap_region_par_iterate(HeapRegionClosure* cl,
1206                                uint worker_id,
1207                                HeapRegionClaimer* hrclaimer,
1208                                bool concurrent = false) const;
1209 
1210   // Clear the cached cset start regions and (more importantly)
1211   // the time stamps. Called when we reset the GC time stamp.
1212   void clear_cset_start_regions();
1213 
1214   // Given the id of a worker, obtain or calculate a suitable
1215   // starting region for iterating over the current collection set.
1216   HeapRegion* start_cset_region_for_worker(uint worker_i);
1217 
1218   // Iterate over the regions (if any) in the current collection set.
1219   void collection_set_iterate(HeapRegionClosure* blk);
1220 
1221   // As above but starting from region r
1222   void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1223 
1224   HeapRegion* next_compaction_region(const HeapRegion* from) const;
1225 
1226   // Returns the HeapRegion that contains addr. addr must not be NULL.
1227   template <class T>
1228   inline HeapRegion* heap_region_containing(const T addr) const;
1229 
1230   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1231   // each address in the (reserved) heap is a member of exactly
1232   // one block.  The defining characteristic of a block is that it is
1233   // possible to find its size, and thus to progress forward to the next
1234   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1235   // represent Java objects, or they might be free blocks in a
1236   // free-list-based heap (or subheap), as long as the two kinds are
1237   // distinguishable and the size of each is determinable.
1238 
1239   // Returns the address of the start of the "block" that contains the
1240   // address "addr".  We say "blocks" instead of "object" since some heaps
1241   // may not pack objects densely; a chunk may either be an object or a
1242   // non-object.
1243   virtual HeapWord* block_start(const void* addr) const;
1244 
1245   // Requires "addr" to be the start of a chunk, and returns its size.
1246   // "addr + size" is required to be the start of a new chunk, or the end
1247   // of the active area of the heap.
1248   virtual size_t block_size(const HeapWord* addr) const;
1249 
1250   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1251   // the block is an object.
1252   virtual bool block_is_obj(const HeapWord* addr) const;
1253 
1254   // Section on thread-local allocation buffers (TLABs)
1255   // See CollectedHeap for semantics.
1256 
1257   bool supports_tlab_allocation() const;
1258   size_t tlab_capacity(Thread* ignored) const;
1259   size_t tlab_used(Thread* ignored) const;
1260   size_t max_tlab_size() const;
1261   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1262 
1263   // Can a compiler initialize a new object without store barriers?
1264   // This permission only extends from the creation of a new object
1265   // via a TLAB up to the first subsequent safepoint. If such permission
1266   // is granted for this heap type, the compiler promises to call
1267   // defer_store_barrier() below on any slow path allocation of
1268   // a new object for which such initializing store barriers will
1269   // have been elided. G1, like CMS, allows this, but should be
1270   // ready to provide a compensating write barrier as necessary
1271   // if that storage came out of a non-young region. The efficiency
1272   // of this implementation depends crucially on being able to
1273   // answer very efficiently in constant time whether a piece of
1274   // storage in the heap comes from a young region or not.
1275   // See ReduceInitialCardMarks.
1276   virtual bool can_elide_tlab_store_barriers() const {
1277     return true;
1278   }
1279 
1280   virtual bool card_mark_must_follow_store() const {
1281     return true;
1282   }
1283 
1284   inline bool is_in_young(const oop obj);
1285 
1286   virtual bool is_scavengable(const void* addr);
1287 
1288   // We don't need barriers for initializing stores to objects
1289   // in the young gen: for the SATB pre-barrier, there is no
1290   // pre-value that needs to be remembered; for the remembered-set
1291   // update logging post-barrier, we don't maintain remembered set
1292   // information for young gen objects.
1293   virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1294 
1295   // Returns "true" iff the given word_size is "very large".
1296   static bool is_humongous(size_t word_size) {
1297     // Note this has to be strictly greater-than as the TLABs
1298     // are capped at the humongous threshold and we want to
1299     // ensure that we don't try to allocate a TLAB as
1300     // humongous and that we don't allocate a humongous
1301     // object in a TLAB.
1302     return word_size > _humongous_object_threshold_in_words;
1303   }
1304 
1305   // Returns the humongous threshold for a specific region size
1306   static size_t humongous_threshold_for(size_t region_size) {
1307     return (region_size / 2);
1308   }
1309 
1310   // Returns the number of regions the humongous object of the given word size
1311   // requires.
1312   static size_t humongous_obj_size_in_regions(size_t word_size);
1313 
1314   // Print the maximum heap capacity.
1315   virtual size_t max_capacity() const;
1316 
1317   virtual jlong millis_since_last_gc();
1318 
1319 
1320   // Convenience function to be used in situations where the heap type can be
1321   // asserted to be this type.
1322   static G1CollectedHeap* heap();
1323 
1324   void set_region_short_lived_locked(HeapRegion* hr);
1325   // add appropriate methods for any other surv rate groups
1326 
1327   YoungList* young_list() const { return _young_list; }
1328 
1329   uint old_regions_count() const { return _old_set.length(); }
1330 
1331   uint humongous_regions_count() const { return _humongous_set.length(); }
1332 
1333   // debugging
1334   bool check_young_list_well_formed() {
1335     return _young_list->check_list_well_formed();
1336   }
1337 
1338   bool check_young_list_empty(bool check_heap,
1339                               bool check_sample = true);
1340 
1341   // *** Stuff related to concurrent marking.  It's not clear to me that so
1342   // many of these need to be public.
1343 
1344   // The functions below are helper functions that a subclass of
1345   // "CollectedHeap" can use in the implementation of its virtual
1346   // functions.
1347   // This performs a concurrent marking of the live objects in a
1348   // bitmap off to the side.
1349   void doConcurrentMark();
1350 
1351   bool isMarkedPrev(oop obj) const;
1352   bool isMarkedNext(oop obj) const;
1353 
1354   // Determine if an object is dead, given the object and also
1355   // the region to which the object belongs. An object is dead
1356   // iff a) it was not allocated since the last mark, b) it
1357   // is not marked, and c) it is not in an archive region.
1358   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1359     return
1360       !hr->obj_allocated_since_prev_marking(obj) &&
1361       !isMarkedPrev(obj) &&
1362       !hr->is_archive();
1363   }
1364 
1365   // This function returns true when an object has been
1366   // around since the previous marking and hasn't yet
1367   // been marked during this marking, and is not in an archive region.
1368   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1369     return
1370       !hr->obj_allocated_since_next_marking(obj) &&
1371       !isMarkedNext(obj) &&
1372       !hr->is_archive();
1373   }
1374 
1375   // Determine if an object is dead, given only the object itself.
1376   // This will find the region to which the object belongs and
1377   // then call the region version of the same function.
1378 
1379   // Added if it is NULL it isn't dead.
1380 
1381   inline bool is_obj_dead(const oop obj) const;
1382 
1383   inline bool is_obj_ill(const oop obj) const;
1384 
1385   ConcurrentMark* concurrent_mark() const { return _cm; }
1386 
1387   // Refinement
1388 
1389   ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1390 
1391   // The dirty cards region list is used to record a subset of regions
1392   // whose cards need clearing. The list if populated during the
1393   // remembered set scanning and drained during the card table
1394   // cleanup. Although the methods are reentrant, population/draining
1395   // phases must not overlap. For synchronization purposes the last
1396   // element on the list points to itself.
1397   HeapRegion* _dirty_cards_region_list;
1398   void push_dirty_cards_region(HeapRegion* hr);
1399   HeapRegion* pop_dirty_cards_region();
1400 
1401   // Optimized nmethod scanning support routines
1402 
1403   // Register the given nmethod with the G1 heap.
1404   virtual void register_nmethod(nmethod* nm);
1405 
1406   // Unregister the given nmethod from the G1 heap.
1407   virtual void unregister_nmethod(nmethod* nm);
1408 
1409   // Free up superfluous code root memory.
1410   void purge_code_root_memory();
1411 
1412   // Rebuild the strong code root lists for each region
1413   // after a full GC.
1414   void rebuild_strong_code_roots();
1415 
1416   // Delete entries for dead interned string and clean up unreferenced symbols
1417   // in symbol table, possibly in parallel.
1418   void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1419 
1420   // Parallel phase of unloading/cleaning after G1 concurrent mark.
1421   void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1422 
1423   // Redirty logged cards in the refinement queue.
1424   void redirty_logged_cards();
1425   // Verification
1426 
1427   // Perform any cleanup actions necessary before allowing a verification.
1428   virtual void prepare_for_verify();
1429 
1430   // Perform verification.
1431 
1432   // vo == UsePrevMarking  -> use "prev" marking information,
1433   // vo == UseNextMarking -> use "next" marking information
1434   // vo == UseMarkWord    -> use the mark word in the object header
1435   //
1436   // NOTE: Only the "prev" marking information is guaranteed to be
1437   // consistent most of the time, so most calls to this should use
1438   // vo == UsePrevMarking.
1439   // Currently, there is only one case where this is called with
1440   // vo == UseNextMarking, which is to verify the "next" marking
1441   // information at the end of remark.
1442   // Currently there is only one place where this is called with
1443   // vo == UseMarkWord, which is to verify the marking during a
1444   // full GC.
1445   void verify(VerifyOption vo);
1446 
1447   // The methods below are here for convenience and dispatch the
1448   // appropriate method depending on value of the given VerifyOption
1449   // parameter. The values for that parameter, and their meanings,
1450   // are the same as those above.
1451 
1452   bool is_obj_dead_cond(const oop obj,
1453                         const HeapRegion* hr,
1454                         const VerifyOption vo) const;
1455 
1456   bool is_obj_dead_cond(const oop obj,
1457                         const VerifyOption vo) const;
1458 
1459   G1HeapSummary create_g1_heap_summary();
1460   G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1461 
1462   // Printing
1463 
1464   virtual void print_on(outputStream* st) const;
1465   virtual void print_extended_on(outputStream* st) const;
1466   virtual void print_on_error(outputStream* st) const;
1467 
1468   virtual void print_gc_threads_on(outputStream* st) const;
1469   virtual void gc_threads_do(ThreadClosure* tc) const;
1470 
1471   // Override
1472   void print_tracing_info() const;
1473 
1474   // The following two methods are helpful for debugging RSet issues.
1475   void print_cset_rsets() PRODUCT_RETURN;
1476   void print_all_rsets() PRODUCT_RETURN;
1477 
1478 public:
1479   size_t pending_card_num();
1480 
1481 protected:
1482   size_t _max_heap_capacity;
1483 };
1484 
1485 class G1ParEvacuateFollowersClosure : public VoidClosure {
1486 private:
1487   double _start_term;
1488   double _term_time;
1489   size_t _term_attempts;
1490 
1491   void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1492   void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1493 protected:
1494   G1CollectedHeap*              _g1h;
1495   G1ParScanThreadState*         _par_scan_state;
1496   RefToScanQueueSet*            _queues;
1497   ParallelTaskTerminator*       _terminator;
1498 
1499   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
1500   RefToScanQueueSet*      queues()         { return _queues; }
1501   ParallelTaskTerminator* terminator()     { return _terminator; }
1502 
1503 public:
1504   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1505                                 G1ParScanThreadState* par_scan_state,
1506                                 RefToScanQueueSet* queues,
1507                                 ParallelTaskTerminator* terminator)
1508     : _g1h(g1h), _par_scan_state(par_scan_state),
1509       _queues(queues), _terminator(terminator),
1510       _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1511 
1512   void do_void();
1513 
1514   double term_time() const { return _term_time; }
1515   size_t term_attempts() const { return _term_attempts; }
1516 
1517 private:
1518   inline bool offer_termination();
1519 };
1520 
1521 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP