rev 7249 : 8061748: Remove check_ct_logs_at_safepoint()
Summary: Remove unused function and related closure class
Reviewed-by:
Contributed-by: kim.barrett@oracle.com

   1 /*
   2  * Copyright (c) 2001, 2014, 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_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
  27 
  28 #include "gc_implementation/g1/g1AllocationContext.hpp"
  29 #include "gc_implementation/g1/g1Allocator.hpp"
  30 #include "gc_implementation/g1/concurrentMark.hpp"
  31 #include "gc_implementation/g1/evacuationInfo.hpp"
  32 #include "gc_implementation/g1/g1AllocRegion.hpp"
  33 #include "gc_implementation/g1/g1BiasedArray.hpp"
  34 #include "gc_implementation/g1/g1HRPrinter.hpp"
  35 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
  36 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
  37 #include "gc_implementation/g1/g1YCTypes.hpp"
  38 #include "gc_implementation/g1/heapRegionManager.hpp"
  39 #include "gc_implementation/g1/heapRegionSet.hpp"
  40 #include "gc_implementation/shared/hSpaceCounters.hpp"
  41 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
  42 #include "memory/barrierSet.hpp"
  43 #include "memory/memRegion.hpp"
  44 #include "memory/sharedHeap.hpp"
  45 #include "utilities/stack.hpp"
  46 
  47 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  48 // It uses the "Garbage First" heap organization and algorithm, which
  49 // may combine concurrent marking with parallel, incremental compaction of
  50 // heap subsets that will yield large amounts of garbage.
  51 
  52 // Forward declarations
  53 class HeapRegion;
  54 class HRRSCleanupTask;
  55 class GenerationSpec;
  56 class OopsInHeapRegionClosure;
  57 class G1KlassScanClosure;
  58 class G1ScanHeapEvacClosure;
  59 class ObjectClosure;
  60 class SpaceClosure;
  61 class CompactibleSpaceClosure;
  62 class Space;
  63 class G1CollectorPolicy;
  64 class GenRemSet;
  65 class G1RemSet;
  66 class HeapRegionRemSetIterator;
  67 class ConcurrentMark;
  68 class ConcurrentMarkThread;
  69 class ConcurrentG1Refine;
  70 class ConcurrentGCTimer;
  71 class GenerationCounters;
  72 class STWGCTimer;
  73 class G1NewTracer;
  74 class G1OldTracer;
  75 class EvacuationFailedInfo;
  76 class nmethod;
  77 class Ticks;
  78 
  79 typedef OverflowTaskQueue<StarTask, mtGC>         RefToScanQueue;
  80 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
  81 
  82 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
  83 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
  84 
  85 class YoungList : public CHeapObj<mtGC> {
  86 private:
  87   G1CollectedHeap* _g1h;
  88 
  89   HeapRegion* _head;
  90 
  91   HeapRegion* _survivor_head;
  92   HeapRegion* _survivor_tail;
  93 
  94   HeapRegion* _curr;
  95 
  96   uint        _length;
  97   uint        _survivor_length;
  98 
  99   size_t      _last_sampled_rs_lengths;
 100   size_t      _sampled_rs_lengths;
 101 
 102   void         empty_list(HeapRegion* list);
 103 
 104 public:
 105   YoungList(G1CollectedHeap* g1h);
 106 
 107   void         push_region(HeapRegion* hr);
 108   void         add_survivor_region(HeapRegion* hr);
 109 
 110   void         empty_list();
 111   bool         is_empty() { return _length == 0; }
 112   uint         length() { return _length; }
 113   uint         survivor_length() { return _survivor_length; }
 114 
 115   // Currently we do not keep track of the used byte sum for the
 116   // young list and the survivors and it'd be quite a lot of work to
 117   // do so. When we'll eventually replace the young list with
 118   // instances of HeapRegionLinkedList we'll get that for free. So,
 119   // we'll report the more accurate information then.
 120   size_t       eden_used_bytes() {
 121     assert(length() >= survivor_length(), "invariant");
 122     return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
 123   }
 124   size_t       survivor_used_bytes() {
 125     return (size_t) survivor_length() * HeapRegion::GrainBytes;
 126   }
 127 
 128   void rs_length_sampling_init();
 129   bool rs_length_sampling_more();
 130   void rs_length_sampling_next();
 131 
 132   void reset_sampled_info() {
 133     _last_sampled_rs_lengths =   0;
 134   }
 135   size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
 136 
 137   // for development purposes
 138   void reset_auxilary_lists();
 139   void clear() { _head = NULL; _length = 0; }
 140 
 141   void clear_survivors() {
 142     _survivor_head    = NULL;
 143     _survivor_tail    = NULL;
 144     _survivor_length  = 0;
 145   }
 146 
 147   HeapRegion* first_region() { return _head; }
 148   HeapRegion* first_survivor_region() { return _survivor_head; }
 149   HeapRegion* last_survivor_region() { return _survivor_tail; }
 150 
 151   // debugging
 152   bool          check_list_well_formed();
 153   bool          check_list_empty(bool check_sample = true);
 154   void          print();
 155 };
 156 
 157 // The G1 STW is alive closure.
 158 // An instance is embedded into the G1CH and used as the
 159 // (optional) _is_alive_non_header closure in the STW
 160 // reference processor. It is also extensively used during
 161 // reference processing during STW evacuation pauses.
 162 class G1STWIsAliveClosure: public BoolObjectClosure {
 163   G1CollectedHeap* _g1;
 164 public:
 165   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 166   bool do_object_b(oop p);
 167 };
 168 
 169 class RefineCardTableEntryClosure;
 170 
 171 class G1RegionMappingChangedListener : public G1MappingChangedListener {
 172  private:
 173   void reset_from_card_cache(uint start_idx, size_t num_regions);
 174  public:
 175   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
 176 };
 177 
 178 class G1CollectedHeap : public SharedHeap {
 179   friend class VM_CollectForMetadataAllocation;
 180   friend class VM_G1CollectForAllocation;
 181   friend class VM_G1CollectFull;
 182   friend class VM_G1IncCollectionPause;
 183   friend class VMStructs;
 184   friend class MutatorAllocRegion;
 185   friend class SurvivorGCAllocRegion;
 186   friend class OldGCAllocRegion;
 187   friend class G1Allocator;
 188   friend class G1DefaultAllocator;
 189   friend class G1ResManAllocator;
 190 
 191   // Closures used in implementation.
 192   template <G1Barrier barrier, G1Mark do_mark_object>
 193   friend class G1ParCopyClosure;
 194   friend class G1IsAliveClosure;
 195   friend class G1EvacuateFollowersClosure;
 196   friend class G1ParScanThreadState;
 197   friend class G1ParScanClosureSuper;
 198   friend class G1ParEvacuateFollowersClosure;
 199   friend class G1ParTask;
 200   friend class G1ParGCAllocator;
 201   friend class G1DefaultParGCAllocator;
 202   friend class G1FreeGarbageRegionClosure;
 203   friend class RefineCardTableEntryClosure;
 204   friend class G1PrepareCompactClosure;
 205   friend class RegionSorter;
 206   friend class RegionResetter;
 207   friend class CountRCClosure;
 208   friend class EvacPopObjClosure;
 209   friend class G1ParCleanupCTTask;
 210 
 211   friend class G1FreeHumongousRegionClosure;
 212   // Other related classes.
 213   friend class G1MarkSweep;
 214   friend class HeapRegionClaimer;
 215 
 216 private:
 217   // The one and only G1CollectedHeap, so static functions can find it.
 218   static G1CollectedHeap* _g1h;
 219 
 220   static size_t _humongous_object_threshold_in_words;
 221 
 222   // The secondary free list which contains regions that have been
 223   // freed up during the cleanup process. This will be appended to
 224   // the master free list when appropriate.
 225   FreeRegionList _secondary_free_list;
 226 
 227   // It keeps track of the old regions.
 228   HeapRegionSet _old_set;
 229 
 230   // It keeps track of the humongous regions.
 231   HeapRegionSet _humongous_set;
 232 
 233   void clear_humongous_is_live_table();
 234   void eagerly_reclaim_humongous_regions();
 235 
 236   // The number of regions we could create by expansion.
 237   uint _expansion_regions;
 238 
 239   // The block offset table for the G1 heap.
 240   G1BlockOffsetSharedArray* _bot_shared;
 241 
 242   // Tears down the region sets / lists so that they are empty and the
 243   // regions on the heap do not belong to a region set / list. The
 244   // only exception is the humongous set which we leave unaltered. If
 245   // free_list_only is true, it will only tear down the master free
 246   // list. It is called before a Full GC (free_list_only == false) or
 247   // before heap shrinking (free_list_only == true).
 248   void tear_down_region_sets(bool free_list_only);
 249 
 250   // Rebuilds the region sets / lists so that they are repopulated to
 251   // reflect the contents of the heap. The only exception is the
 252   // humongous set which was not torn down in the first place. If
 253   // free_list_only is true, it will only rebuild the master free
 254   // list. It is called after a Full GC (free_list_only == false) or
 255   // after heap shrinking (free_list_only == true).
 256   void rebuild_region_sets(bool free_list_only);
 257 
 258   // Callback for region mapping changed events.
 259   G1RegionMappingChangedListener _listener;
 260 
 261   // The sequence of all heap regions in the heap.
 262   HeapRegionManager _hrm;
 263 
 264   // Class that handles the different kinds of allocations.
 265   G1Allocator* _allocator;
 266 
 267   // Statistics for each allocation context
 268   AllocationContextStats _allocation_context_stats;
 269 
 270   // PLAB sizing policy for survivors.
 271   PLABStats _survivor_plab_stats;
 272 
 273   // PLAB sizing policy for tenured objects.
 274   PLABStats _old_plab_stats;
 275 
 276   // It specifies whether we should attempt to expand the heap after a
 277   // region allocation failure. If heap expansion fails we set this to
 278   // false so that we don't re-attempt the heap expansion (it's likely
 279   // that subsequent expansion attempts will also fail if one fails).
 280   // Currently, it is only consulted during GC and it's reset at the
 281   // start of each GC.
 282   bool _expand_heap_after_alloc_failure;
 283 
 284   // It resets the mutator alloc region before new allocations can take place.
 285   void init_mutator_alloc_region();
 286 
 287   // It releases the mutator alloc region.
 288   void release_mutator_alloc_region();
 289 
 290   // It initializes the GC alloc regions at the start of a GC.
 291   void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
 292 
 293   // It releases the GC alloc regions at the end of a GC.
 294   void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
 295 
 296   // It does any cleanup that needs to be done on the GC alloc regions
 297   // before a Full GC.
 298   void abandon_gc_alloc_regions();
 299 
 300   // Helper for monitoring and management support.
 301   G1MonitoringSupport* _g1mm;
 302 
 303   // Records whether the region at the given index is kept live by roots or
 304   // references from the young generation.
 305   class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> {
 306    protected:
 307     bool default_value() const { return false; }
 308    public:
 309     void clear() { G1BiasedMappedArray<bool>::clear(); }
 310     void set_live(uint region) {
 311       set_by_index(region, true);
 312     }
 313     bool is_live(uint region) {
 314       return get_by_index(region);
 315     }
 316   };
 317 
 318   HumongousIsLiveBiasedMappedArray _humongous_is_live;
 319   // Stores whether during humongous object registration we found candidate regions.
 320   // If not, we can skip a few steps.
 321   bool _has_humongous_reclaim_candidates;
 322 
 323   volatile unsigned _gc_time_stamp;
 324 
 325   size_t* _surviving_young_words;
 326 
 327   G1HRPrinter _hr_printer;
 328 
 329   void setup_surviving_young_words();
 330   void update_surviving_young_words(size_t* surv_young_words);
 331   void cleanup_surviving_young_words();
 332 
 333   // It decides whether an explicit GC should start a concurrent cycle
 334   // instead of doing a STW GC. Currently, a concurrent cycle is
 335   // explicitly started if:
 336   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 337   // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 338   // (c) cause == _g1_humongous_allocation
 339   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 340 
 341   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 342   // concurrent cycles) we have started.
 343   volatile unsigned int _old_marking_cycles_started;
 344 
 345   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 346   // concurrent cycles) we have completed.
 347   volatile unsigned int _old_marking_cycles_completed;
 348 
 349   bool _concurrent_cycle_started;
 350   bool _heap_summary_sent;
 351 
 352   // This is a non-product method that is helpful for testing. It is
 353   // called at the end of a GC and artificially expands the heap by
 354   // allocating a number of dead regions. This way we can induce very
 355   // frequent marking cycles and stress the cleanup / concurrent
 356   // cleanup code more (as all the regions that will be allocated by
 357   // this method will be found dead by the marking cycle).
 358   void allocate_dummy_regions() PRODUCT_RETURN;
 359 
 360   // Clear RSets after a compaction. It also resets the GC time stamps.
 361   void clear_rsets_post_compaction();
 362 
 363   // If the HR printer is active, dump the state of the regions in the
 364   // heap after a compaction.
 365   void print_hrm_post_compaction();
 366 
 367   double verify(bool guard, const char* msg);
 368   void verify_before_gc();
 369   void verify_after_gc();
 370 
 371   void log_gc_header();
 372   void log_gc_footer(double pause_time_sec);
 373 
 374   // These are macros so that, if the assert fires, we get the correct
 375   // line number, file, etc.
 376 
 377 #define heap_locking_asserts_err_msg(_extra_message_)                         \
 378   err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",    \
 379           (_extra_message_),                                                  \
 380           BOOL_TO_STR(Heap_lock->owned_by_self()),                            \
 381           BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),               \
 382           BOOL_TO_STR(Thread::current()->is_VM_thread()))
 383 
 384 #define assert_heap_locked()                                                  \
 385   do {                                                                        \
 386     assert(Heap_lock->owned_by_self(),                                        \
 387            heap_locking_asserts_err_msg("should be holding the Heap_lock"));  \
 388   } while (0)
 389 
 390 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 391   do {                                                                        \
 392     assert(Heap_lock->owned_by_self() ||                                      \
 393            (SafepointSynchronize::is_at_safepoint() &&                        \
 394              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 395            heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
 396                                         "should be at a safepoint"));         \
 397   } while (0)
 398 
 399 #define assert_heap_locked_and_not_at_safepoint()                             \
 400   do {                                                                        \
 401     assert(Heap_lock->owned_by_self() &&                                      \
 402                                     !SafepointSynchronize::is_at_safepoint(), \
 403           heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
 404                                        "should not be at a safepoint"));      \
 405   } while (0)
 406 
 407 #define assert_heap_not_locked()                                              \
 408   do {                                                                        \
 409     assert(!Heap_lock->owned_by_self(),                                       \
 410         heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
 411   } while (0)
 412 
 413 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 414   do {                                                                        \
 415     assert(!Heap_lock->owned_by_self() &&                                     \
 416                                     !SafepointSynchronize::is_at_safepoint(), \
 417       heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
 418                                    "should not be at a safepoint"));          \
 419   } while (0)
 420 
 421 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 422   do {                                                                        \
 423     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 424               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 425            heap_locking_asserts_err_msg("should be at a safepoint"));         \
 426   } while (0)
 427 
 428 #define assert_not_at_safepoint()                                             \
 429   do {                                                                        \
 430     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 431            heap_locking_asserts_err_msg("should not be at a safepoint"));     \
 432   } while (0)
 433 
 434 protected:
 435 
 436   // The young region list.
 437   YoungList*  _young_list;
 438 
 439   // The current policy object for the collector.
 440   G1CollectorPolicy* _g1_policy;
 441 
 442   // This is the second level of trying to allocate a new region. If
 443   // new_region() didn't find a region on the free_list, this call will
 444   // check whether there's anything available on the
 445   // secondary_free_list and/or wait for more regions to appear on
 446   // that list, if _free_regions_coming is set.
 447   HeapRegion* new_region_try_secondary_free_list(bool is_old);
 448 
 449   // Try to allocate a single non-humongous HeapRegion sufficient for
 450   // an allocation of the given word_size. If do_expand is true,
 451   // attempt to expand the heap if necessary to satisfy the allocation
 452   // request. If the region is to be used as an old region or for a
 453   // humongous object, set is_old to true. If not, to false.
 454   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 455 
 456   // Initialize a contiguous set of free regions of length num_regions
 457   // and starting at index first so that they appear as a single
 458   // humongous region.
 459   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 460                                                       uint num_regions,
 461                                                       size_t word_size,
 462                                                       AllocationContext_t context);
 463 
 464   // Attempt to allocate a humongous object of the given size. Return
 465   // NULL if unsuccessful.
 466   HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
 467 
 468   // The following two methods, allocate_new_tlab() and
 469   // mem_allocate(), are the two main entry points from the runtime
 470   // into the G1's allocation routines. They have the following
 471   // assumptions:
 472   //
 473   // * They should both be called outside safepoints.
 474   //
 475   // * They should both be called without holding the Heap_lock.
 476   //
 477   // * All allocation requests for new TLABs should go to
 478   //   allocate_new_tlab().
 479   //
 480   // * All non-TLAB allocation requests should go to mem_allocate().
 481   //
 482   // * If either call cannot satisfy the allocation request using the
 483   //   current allocating region, they will try to get a new one. If
 484   //   this fails, they will attempt to do an evacuation pause and
 485   //   retry the allocation.
 486   //
 487   // * If all allocation attempts fail, even after trying to schedule
 488   //   an evacuation pause, allocate_new_tlab() will return NULL,
 489   //   whereas mem_allocate() will attempt a heap expansion and/or
 490   //   schedule a Full GC.
 491   //
 492   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 493   //   should never be called with word_size being humongous. All
 494   //   humongous allocation requests should go to mem_allocate() which
 495   //   will satisfy them with a special path.
 496 
 497   virtual HeapWord* allocate_new_tlab(size_t word_size);
 498 
 499   virtual HeapWord* mem_allocate(size_t word_size,
 500                                  bool*  gc_overhead_limit_was_exceeded);
 501 
 502   // The following three methods take a gc_count_before_ret
 503   // parameter which is used to return the GC count if the method
 504   // returns NULL. Given that we are required to read the GC count
 505   // while holding the Heap_lock, and these paths will take the
 506   // Heap_lock at some point, it's easier to get them to read the GC
 507   // count while holding the Heap_lock before they return NULL instead
 508   // of the caller (namely: mem_allocate()) having to also take the
 509   // Heap_lock just to read the GC count.
 510 
 511   // First-level mutator allocation attempt: try to allocate out of
 512   // the mutator alloc region without taking the Heap_lock. This
 513   // should only be used for non-humongous allocations.
 514   inline HeapWord* attempt_allocation(size_t word_size,
 515                                       unsigned int* gc_count_before_ret,
 516                                       int* gclocker_retry_count_ret);
 517 
 518   // Second-level mutator allocation attempt: take the Heap_lock and
 519   // retry the allocation attempt, potentially scheduling a GC
 520   // pause. This should only be used for non-humongous allocations.
 521   HeapWord* attempt_allocation_slow(size_t word_size,
 522                                     AllocationContext_t context,
 523                                     unsigned int* gc_count_before_ret,
 524                                     int* gclocker_retry_count_ret);
 525 
 526   // Takes the Heap_lock and attempts a humongous allocation. It can
 527   // potentially schedule a GC pause.
 528   HeapWord* attempt_allocation_humongous(size_t word_size,
 529                                          unsigned int* gc_count_before_ret,
 530                                          int* gclocker_retry_count_ret);
 531 
 532   // Allocation attempt that should be called during safepoints (e.g.,
 533   // at the end of a successful GC). expect_null_mutator_alloc_region
 534   // specifies whether the mutator alloc region is expected to be NULL
 535   // or not.
 536   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 537                                             AllocationContext_t context,
 538                                             bool expect_null_mutator_alloc_region);
 539 
 540   // It dirties the cards that cover the block so that so that the post
 541   // write barrier never queues anything when updating objects on this
 542   // block. It is assumed (and in fact we assert) that the block
 543   // belongs to a young region.
 544   inline void dirty_young_block(HeapWord* start, size_t word_size);
 545 
 546   // Allocate blocks during garbage collection. Will ensure an
 547   // allocation region, either by picking one or expanding the
 548   // heap, and then allocate a block of the given size. The block
 549   // may not be a humongous - it must fit into a single heap region.
 550   HeapWord* par_allocate_during_gc(GCAllocPurpose purpose,
 551                                    size_t word_size,
 552                                    AllocationContext_t context);
 553 
 554   HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
 555                                     HeapRegion*    alloc_region,
 556                                     bool           par,
 557                                     size_t         word_size);
 558 
 559   // Ensure that no further allocations can happen in "r", bearing in mind
 560   // that parallel threads might be attempting allocations.
 561   void par_allocate_remaining_space(HeapRegion* r);
 562 
 563   // Allocation attempt during GC for a survivor object / PLAB.
 564   inline HeapWord* survivor_attempt_allocation(size_t word_size,
 565                                                AllocationContext_t context);
 566 
 567   // Allocation attempt during GC for an old object / PLAB.
 568   inline HeapWord* old_attempt_allocation(size_t word_size,
 569                                           AllocationContext_t context);
 570 
 571   // These methods are the "callbacks" from the G1AllocRegion class.
 572 
 573   // For mutator alloc regions.
 574   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 575   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 576                                    size_t allocated_bytes);
 577 
 578   // For GC alloc regions.
 579   HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
 580                                   GCAllocPurpose ap);
 581   void retire_gc_alloc_region(HeapRegion* alloc_region,
 582                               size_t allocated_bytes, GCAllocPurpose ap);
 583 
 584   // - if explicit_gc is true, the GC is for a System.gc() or a heap
 585   //   inspection request and should collect the entire heap
 586   // - if clear_all_soft_refs is true, all soft references should be
 587   //   cleared during the GC
 588   // - if explicit_gc is false, word_size describes the allocation that
 589   //   the GC should attempt (at least) to satisfy
 590   // - it returns false if it is unable to do the collection due to the
 591   //   GC locker being active, true otherwise
 592   bool do_collection(bool explicit_gc,
 593                      bool clear_all_soft_refs,
 594                      size_t word_size);
 595 
 596   // Callback from VM_G1CollectFull operation.
 597   // Perform a full collection.
 598   virtual void do_full_collection(bool clear_all_soft_refs);
 599 
 600   // Resize the heap if necessary after a full collection.  If this is
 601   // after a collect-for allocation, "word_size" is the allocation size,
 602   // and will be considered part of the used portion of the heap.
 603   void resize_if_necessary_after_full_collection(size_t word_size);
 604 
 605   // Callback from VM_G1CollectForAllocation operation.
 606   // This function does everything necessary/possible to satisfy a
 607   // failed allocation request (including collection, expansion, etc.)
 608   HeapWord* satisfy_failed_allocation(size_t word_size,
 609                                       AllocationContext_t context,
 610                                       bool* succeeded);
 611 
 612   // Attempting to expand the heap sufficiently
 613   // to support an allocation of the given "word_size".  If
 614   // successful, perform the allocation and return the address of the
 615   // allocated block, or else "NULL".
 616   HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
 617 
 618   // Process any reference objects discovered during
 619   // an incremental evacuation pause.
 620   void process_discovered_references(uint no_of_gc_workers);
 621 
 622   // Enqueue any remaining discovered references
 623   // after processing.
 624   void enqueue_discovered_references(uint no_of_gc_workers);
 625 
 626 public:
 627 
 628   G1Allocator* allocator() {
 629     return _allocator;
 630   }
 631 
 632   G1MonitoringSupport* g1mm() {
 633     assert(_g1mm != NULL, "should have been initialized");
 634     return _g1mm;
 635   }
 636 
 637   // Expand the garbage-first heap by at least the given size (in bytes!).
 638   // Returns true if the heap was expanded by the requested amount;
 639   // false otherwise.
 640   // (Rounds up to a HeapRegion boundary.)
 641   bool expand(size_t expand_bytes);
 642 
 643   // Returns the PLAB statistics given a purpose.
 644   PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
 645     PLABStats* stats = NULL;
 646 
 647     switch (purpose) {
 648     case GCAllocForSurvived:
 649       stats = &_survivor_plab_stats;
 650       break;
 651     case GCAllocForTenured:
 652       stats = &_old_plab_stats;
 653       break;
 654     default:
 655       assert(false, "unrecognized GCAllocPurpose");
 656     }
 657 
 658     return stats;
 659   }
 660 
 661   // Determines PLAB size for a particular allocation purpose.
 662   size_t desired_plab_sz(GCAllocPurpose purpose);
 663 
 664   inline AllocationContextStats& allocation_context_stats();
 665 
 666   // Do anything common to GC's.
 667   virtual void gc_prologue(bool full);
 668   virtual void gc_epilogue(bool full);
 669 
 670   inline void set_humongous_is_live(oop obj);
 671 
 672   bool humongous_is_live(uint region) {
 673     return _humongous_is_live.is_live(region);
 674   }
 675 
 676   // Returns whether the given region (which must be a humongous (start) region)
 677   // is to be considered conservatively live regardless of any other conditions.
 678   bool humongous_region_is_always_live(uint index);
 679   // Register the given region to be part of the collection set.
 680   inline void register_humongous_region_with_in_cset_fast_test(uint index);
 681   // Register regions with humongous objects (actually on the start region) in
 682   // the in_cset_fast_test table.
 683   void register_humongous_regions_with_in_cset_fast_test();
 684   // We register a region with the fast "in collection set" test. We
 685   // simply set to true the array slot corresponding to this region.
 686   void register_region_with_in_cset_fast_test(HeapRegion* r) {
 687     _in_cset_fast_test.set_in_cset(r->hrm_index());
 688   }
 689 
 690   // This is a fast test on whether a reference points into the
 691   // collection set or not. Assume that the reference
 692   // points into the heap.
 693   inline bool in_cset_fast_test(oop obj);
 694 
 695   void clear_cset_fast_test() {
 696     _in_cset_fast_test.clear();
 697   }
 698 
 699   // This is called at the start of either a concurrent cycle or a Full
 700   // GC to update the number of old marking cycles started.
 701   void increment_old_marking_cycles_started();
 702 
 703   // This is called at the end of either a concurrent cycle or a Full
 704   // GC to update the number of old marking cycles completed. Those two
 705   // can happen in a nested fashion, i.e., we start a concurrent
 706   // cycle, a Full GC happens half-way through it which ends first,
 707   // and then the cycle notices that a Full GC happened and ends
 708   // too. The concurrent parameter is a boolean to help us do a bit
 709   // tighter consistency checking in the method. If concurrent is
 710   // false, the caller is the inner caller in the nesting (i.e., the
 711   // Full GC). If concurrent is true, the caller is the outer caller
 712   // in this nesting (i.e., the concurrent cycle). Further nesting is
 713   // not currently supported. The end of this call also notifies
 714   // the FullGCCount_lock in case a Java thread is waiting for a full
 715   // GC to happen (e.g., it called System.gc() with
 716   // +ExplicitGCInvokesConcurrent).
 717   void increment_old_marking_cycles_completed(bool concurrent);
 718 
 719   unsigned int old_marking_cycles_completed() {
 720     return _old_marking_cycles_completed;
 721   }
 722 
 723   void register_concurrent_cycle_start(const Ticks& start_time);
 724   void register_concurrent_cycle_end();
 725   void trace_heap_after_concurrent_cycle();
 726 
 727   G1YCType yc_type();
 728 
 729   G1HRPrinter* hr_printer() { return &_hr_printer; }
 730 
 731   // Frees a non-humongous region by initializing its contents and
 732   // adding it to the free list that's passed as a parameter (this is
 733   // usually a local list which will be appended to the master free
 734   // list later). The used bytes of freed regions are accumulated in
 735   // pre_used. If par is true, the region's RSet will not be freed
 736   // up. The assumption is that this will be done later.
 737   // The locked parameter indicates if the caller has already taken
 738   // care of proper synchronization. This may allow some optimizations.
 739   void free_region(HeapRegion* hr,
 740                    FreeRegionList* free_list,
 741                    bool par,
 742                    bool locked = false);
 743 
 744   // Frees a humongous region by collapsing it into individual regions
 745   // and calling free_region() for each of them. The freed regions
 746   // will be added to the free list that's passed as a parameter (this
 747   // is usually a local list which will be appended to the master free
 748   // list later). The used bytes of freed regions are accumulated in
 749   // pre_used. If par is true, the region's RSet will not be freed
 750   // up. The assumption is that this will be done later.
 751   void free_humongous_region(HeapRegion* hr,
 752                              FreeRegionList* free_list,
 753                              bool par);
 754 protected:
 755 
 756   // Shrink the garbage-first heap by at most the given size (in bytes!).
 757   // (Rounds down to a HeapRegion boundary.)
 758   virtual void shrink(size_t expand_bytes);
 759   void shrink_helper(size_t expand_bytes);
 760 
 761   #if TASKQUEUE_STATS
 762   static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
 763   void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
 764   void reset_taskqueue_stats();
 765   #endif // TASKQUEUE_STATS
 766 
 767   // Schedule the VM operation that will do an evacuation pause to
 768   // satisfy an allocation request of word_size. *succeeded will
 769   // return whether the VM operation was successful (it did do an
 770   // evacuation pause) or not (another thread beat us to it or the GC
 771   // locker was active). Given that we should not be holding the
 772   // Heap_lock when we enter this method, we will pass the
 773   // gc_count_before (i.e., total_collections()) as a parameter since
 774   // it has to be read while holding the Heap_lock. Currently, both
 775   // methods that call do_collection_pause() release the Heap_lock
 776   // before the call, so it's easy to read gc_count_before just before.
 777   HeapWord* do_collection_pause(size_t         word_size,
 778                                 unsigned int   gc_count_before,
 779                                 bool*          succeeded,
 780                                 GCCause::Cause gc_cause);
 781 
 782   // The guts of the incremental collection pause, executed by the vm
 783   // thread. It returns false if it is unable to do the collection due
 784   // to the GC locker being active, true otherwise
 785   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 786 
 787   // Actually do the work of evacuating the collection set.
 788   void evacuate_collection_set(EvacuationInfo& evacuation_info);
 789 
 790   // The g1 remembered set of the heap.
 791   G1RemSet* _g1_rem_set;
 792 
 793   // A set of cards that cover the objects for which the Rsets should be updated
 794   // concurrently after the collection.
 795   DirtyCardQueueSet _dirty_card_queue_set;
 796 
 797   // The closure used to refine a single card.
 798   RefineCardTableEntryClosure* _refine_cte_cl;
 799 
 800   // A function to check the consistency of dirty card logs.
 801   void check_ct_logs_at_safepoint();
 802 
 803   // A DirtyCardQueueSet that is used to hold cards that contain
 804   // references into the current collection set. This is used to
 805   // update the remembered sets of the regions in the collection
 806   // set in the event of an evacuation failure.
 807   DirtyCardQueueSet _into_cset_dirty_card_queue_set;
 808 
 809   // After a collection pause, make the regions in the CS into free
 810   // regions.
 811   void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
 812 
 813   // Abandon the current collection set without recording policy
 814   // statistics or updating free lists.
 815   void abandon_collection_set(HeapRegion* cs_head);
 816 
 817   // Applies "scan_non_heap_roots" to roots outside the heap,
 818   // "scan_rs" to roots inside the heap (having done "set_region" to
 819   // indicate the region in which the root resides),
 820   // and does "scan_metadata" If "scan_rs" is
 821   // NULL, then this step is skipped.  The "worker_i"
 822   // param is for use with parallel roots processing, and should be
 823   // the "i" of the calling parallel worker thread's work(i) function.
 824   // In the sequential case this param will be ignored.
 825   void g1_process_roots(OopClosure* scan_non_heap_roots,
 826                         OopClosure* scan_non_heap_weak_roots,
 827                         OopsInHeapRegionClosure* scan_rs,
 828                         CLDClosure* scan_strong_clds,
 829                         CLDClosure* scan_weak_clds,
 830                         CodeBlobClosure* scan_strong_code,
 831                         uint worker_i);
 832 
 833   // The concurrent marker (and the thread it runs in.)
 834   ConcurrentMark* _cm;
 835   ConcurrentMarkThread* _cmThread;
 836   bool _mark_in_progress;
 837 
 838   // The concurrent refiner.
 839   ConcurrentG1Refine* _cg1r;
 840 
 841   // The parallel task queues
 842   RefToScanQueueSet *_task_queues;
 843 
 844   // True iff a evacuation has failed in the current collection.
 845   bool _evacuation_failed;
 846 
 847   EvacuationFailedInfo* _evacuation_failed_info_array;
 848 
 849   // Failed evacuations cause some logical from-space objects to have
 850   // forwarding pointers to themselves.  Reset them.
 851   void remove_self_forwarding_pointers();
 852 
 853   // Together, these store an object with a preserved mark, and its mark value.
 854   Stack<oop, mtGC>     _objs_with_preserved_marks;
 855   Stack<markOop, mtGC> _preserved_marks_of_objs;
 856 
 857   // Preserve the mark of "obj", if necessary, in preparation for its mark
 858   // word being overwritten with a self-forwarding-pointer.
 859   void preserve_mark_if_necessary(oop obj, markOop m);
 860 
 861   // The stack of evac-failure objects left to be scanned.
 862   GrowableArray<oop>*    _evac_failure_scan_stack;
 863   // The closure to apply to evac-failure objects.
 864 
 865   OopsInHeapRegionClosure* _evac_failure_closure;
 866   // Set the field above.
 867   void
 868   set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
 869     _evac_failure_closure = evac_failure_closure;
 870   }
 871 
 872   // Push "obj" on the scan stack.
 873   void push_on_evac_failure_scan_stack(oop obj);
 874   // Process scan stack entries until the stack is empty.
 875   void drain_evac_failure_scan_stack();
 876   // True iff an invocation of "drain_scan_stack" is in progress; to
 877   // prevent unnecessary recursion.
 878   bool _drain_in_progress;
 879 
 880   // Do any necessary initialization for evacuation-failure handling.
 881   // "cl" is the closure that will be used to process evac-failure
 882   // objects.
 883   void init_for_evac_failure(OopsInHeapRegionClosure* cl);
 884   // Do any necessary cleanup for evacuation-failure handling data
 885   // structures.
 886   void finalize_for_evac_failure();
 887 
 888   // An attempt to evacuate "obj" has failed; take necessary steps.
 889   oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
 890   void handle_evacuation_failure_common(oop obj, markOop m);
 891 
 892 #ifndef PRODUCT
 893   // Support for forcing evacuation failures. Analogous to
 894   // PromotionFailureALot for the other collectors.
 895 
 896   // Records whether G1EvacuationFailureALot should be in effect
 897   // for the current GC
 898   bool _evacuation_failure_alot_for_current_gc;
 899 
 900   // Used to record the GC number for interval checking when
 901   // determining whether G1EvaucationFailureALot is in effect
 902   // for the current GC.
 903   size_t _evacuation_failure_alot_gc_number;
 904 
 905   // Count of the number of evacuations between failures.
 906   volatile size_t _evacuation_failure_alot_count;
 907 
 908   // Set whether G1EvacuationFailureALot should be in effect
 909   // for the current GC (based upon the type of GC and which
 910   // command line flags are set);
 911   inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
 912                                                   bool during_initial_mark,
 913                                                   bool during_marking);
 914 
 915   inline void set_evacuation_failure_alot_for_current_gc();
 916 
 917   // Return true if it's time to cause an evacuation failure.
 918   inline bool evacuation_should_fail();
 919 
 920   // Reset the G1EvacuationFailureALot counters.  Should be called at
 921   // the end of an evacuation pause in which an evacuation failure occurred.
 922   inline void reset_evacuation_should_fail();
 923 #endif // !PRODUCT
 924 
 925   // ("Weak") Reference processing support.
 926   //
 927   // G1 has 2 instances of the reference processor class. One
 928   // (_ref_processor_cm) handles reference object discovery
 929   // and subsequent processing during concurrent marking cycles.
 930   //
 931   // The other (_ref_processor_stw) handles reference object
 932   // discovery and processing during full GCs and incremental
 933   // evacuation pauses.
 934   //
 935   // During an incremental pause, reference discovery will be
 936   // temporarily disabled for _ref_processor_cm and will be
 937   // enabled for _ref_processor_stw. At the end of the evacuation
 938   // pause references discovered by _ref_processor_stw will be
 939   // processed and discovery will be disabled. The previous
 940   // setting for reference object discovery for _ref_processor_cm
 941   // will be re-instated.
 942   //
 943   // At the start of marking:
 944   //  * Discovery by the CM ref processor is verified to be inactive
 945   //    and it's discovered lists are empty.
 946   //  * Discovery by the CM ref processor is then enabled.
 947   //
 948   // At the end of marking:
 949   //  * Any references on the CM ref processor's discovered
 950   //    lists are processed (possibly MT).
 951   //
 952   // At the start of full GC we:
 953   //  * Disable discovery by the CM ref processor and
 954   //    empty CM ref processor's discovered lists
 955   //    (without processing any entries).
 956   //  * Verify that the STW ref processor is inactive and it's
 957   //    discovered lists are empty.
 958   //  * Temporarily set STW ref processor discovery as single threaded.
 959   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 960   //    field.
 961   //  * Finally enable discovery by the STW ref processor.
 962   //
 963   // The STW ref processor is used to record any discovered
 964   // references during the full GC.
 965   //
 966   // At the end of a full GC we:
 967   //  * Enqueue any reference objects discovered by the STW ref processor
 968   //    that have non-live referents. This has the side-effect of
 969   //    making the STW ref processor inactive by disabling discovery.
 970   //  * Verify that the CM ref processor is still inactive
 971   //    and no references have been placed on it's discovered
 972   //    lists (also checked as a precondition during initial marking).
 973 
 974   // The (stw) reference processor...
 975   ReferenceProcessor* _ref_processor_stw;
 976 
 977   STWGCTimer* _gc_timer_stw;
 978   ConcurrentGCTimer* _gc_timer_cm;
 979 
 980   G1OldTracer* _gc_tracer_cm;
 981   G1NewTracer* _gc_tracer_stw;
 982 
 983   // During reference object discovery, the _is_alive_non_header
 984   // closure (if non-null) is applied to the referent object to
 985   // determine whether the referent is live. If so then the
 986   // reference object does not need to be 'discovered' and can
 987   // be treated as a regular oop. This has the benefit of reducing
 988   // the number of 'discovered' reference objects that need to
 989   // be processed.
 990   //
 991   // Instance of the is_alive closure for embedding into the
 992   // STW reference processor as the _is_alive_non_header field.
 993   // Supplying a value for the _is_alive_non_header field is
 994   // optional but doing so prevents unnecessary additions to
 995   // the discovered lists during reference discovery.
 996   G1STWIsAliveClosure _is_alive_closure_stw;
 997 
 998   // The (concurrent marking) reference processor...
 999   ReferenceProcessor* _ref_processor_cm;
1000 
1001   // Instance of the concurrent mark is_alive closure for embedding
1002   // into the Concurrent Marking reference processor as the
1003   // _is_alive_non_header field. Supplying a value for the
1004   // _is_alive_non_header field is optional but doing so prevents
1005   // unnecessary additions to the discovered lists during reference
1006   // discovery.
1007   G1CMIsAliveClosure _is_alive_closure_cm;
1008 
1009   // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1010   HeapRegion** _worker_cset_start_region;
1011 
1012   // Time stamp to validate the regions recorded in the cache
1013   // used by G1CollectedHeap::start_cset_region_for_worker().
1014   // The heap region entry for a given worker is valid iff
1015   // the associated time stamp value matches the current value
1016   // of G1CollectedHeap::_gc_time_stamp.
1017   unsigned int* _worker_cset_start_region_time_stamp;
1018 
1019   enum G1H_process_roots_tasks {
1020     G1H_PS_filter_satb_buffers,
1021     G1H_PS_refProcessor_oops_do,
1022     // Leave this one last.
1023     G1H_PS_NumElements
1024   };
1025 
1026   SubTasksDone* _process_strong_tasks;
1027 
1028   volatile bool _free_regions_coming;
1029 
1030 public:
1031 
1032   SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1033 
1034   void set_refine_cte_cl_concurrency(bool concurrent);
1035 
1036   RefToScanQueue *task_queue(int i) const;
1037 
1038   // A set of cards where updates happened during the GC
1039   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1040 
1041   // A DirtyCardQueueSet that is used to hold cards that contain
1042   // references into the current collection set. This is used to
1043   // update the remembered sets of the regions in the collection
1044   // set in the event of an evacuation failure.
1045   DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1046         { return _into_cset_dirty_card_queue_set; }
1047 
1048   // Create a G1CollectedHeap with the specified policy.
1049   // Must call the initialize method afterwards.
1050   // May not return if something goes wrong.
1051   G1CollectedHeap(G1CollectorPolicy* policy);
1052 
1053   // Initialize the G1CollectedHeap to have the initial and
1054   // maximum sizes and remembered and barrier sets
1055   // specified by the policy object.
1056   jint initialize();
1057 
1058   virtual void stop();
1059 
1060   // Return the (conservative) maximum heap alignment for any G1 heap
1061   static size_t conservative_max_heap_alignment();
1062 
1063   // Initialize weak reference processing.
1064   virtual void ref_processing_init();
1065 
1066   void set_par_threads(uint t) {
1067     SharedHeap::set_par_threads(t);
1068     // Done in SharedHeap but oddly there are
1069     // two _process_strong_tasks's in a G1CollectedHeap
1070     // so do it here too.
1071     _process_strong_tasks->set_n_threads(t);
1072   }
1073 
1074   // Set _n_par_threads according to a policy TBD.
1075   void set_par_threads();
1076 
1077   void set_n_termination(int t) {
1078     _process_strong_tasks->set_n_threads(t);
1079   }
1080 
1081   virtual CollectedHeap::Name kind() const {
1082     return CollectedHeap::G1CollectedHeap;
1083   }
1084 
1085   // The current policy object for the collector.
1086   G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1087 
1088   virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1089 
1090   // Adaptive size policy.  No such thing for g1.
1091   virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1092 
1093   // The rem set and barrier set.
1094   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1095 
1096   unsigned get_gc_time_stamp() {
1097     return _gc_time_stamp;
1098   }
1099 
1100   inline void reset_gc_time_stamp();
1101 
1102   void check_gc_time_stamps() PRODUCT_RETURN;
1103 
1104   inline void increment_gc_time_stamp();
1105 
1106   // Reset the given region's GC timestamp. If it's starts humongous,
1107   // also reset the GC timestamp of its corresponding
1108   // continues humongous regions too.
1109   void reset_gc_time_stamps(HeapRegion* hr);
1110 
1111   void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1112                                   DirtyCardQueue* into_cset_dcq,
1113                                   bool concurrent, uint worker_i);
1114 
1115   // The shared block offset table array.
1116   G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1117 
1118   // Reference Processing accessors
1119 
1120   // The STW reference processor....
1121   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1122 
1123   // The Concurrent Marking reference processor...
1124   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1125 
1126   ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1127   G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1128 
1129   virtual size_t capacity() const;
1130   virtual size_t used() const;
1131   // This should be called when we're not holding the heap lock. The
1132   // result might be a bit inaccurate.
1133   size_t used_unlocked() const;
1134   size_t recalculate_used() const;
1135 
1136   // These virtual functions do the actual allocation.
1137   // Some heaps may offer a contiguous region for shared non-blocking
1138   // allocation, via inlined code (by exporting the address of the top and
1139   // end fields defining the extent of the contiguous allocation region.)
1140   // But G1CollectedHeap doesn't yet support this.
1141 
1142   virtual bool is_maximal_no_gc() const {
1143     return _hrm.available() == 0;
1144   }
1145 
1146   // The current number of regions in the heap.
1147   uint num_regions() const { return _hrm.length(); }
1148 
1149   // The max number of regions in the heap.
1150   uint max_regions() const { return _hrm.max_length(); }
1151 
1152   // The number of regions that are completely free.
1153   uint num_free_regions() const { return _hrm.num_free_regions(); }
1154 
1155   // The number of regions that are not completely free.
1156   uint num_used_regions() const { return num_regions() - num_free_regions(); }
1157 
1158   void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1159   void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1160   void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1161   void verify_dirty_young_regions() PRODUCT_RETURN;
1162 
1163 #ifndef PRODUCT
1164   // Make sure that the given bitmap has no marked objects in the
1165   // range [from,limit). If it does, print an error message and return
1166   // false. Otherwise, just return true. bitmap_name should be "prev"
1167   // or "next".
1168   bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1169                                 HeapWord* from, HeapWord* limit);
1170 
1171   // Verify that the prev / next bitmap range [tams,end) for the given
1172   // region has no marks. Return true if all is well, false if errors
1173   // are detected.
1174   bool verify_bitmaps(const char* caller, HeapRegion* hr);
1175 #endif // PRODUCT
1176 
1177   // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1178   // the given region do not have any spurious marks. If errors are
1179   // detected, print appropriate error messages and crash.
1180   void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1181 
1182   // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1183   // have any spurious marks. If errors are detected, print
1184   // appropriate error messages and crash.
1185   void check_bitmaps(const char* caller) PRODUCT_RETURN;
1186 
1187   // verify_region_sets() performs verification over the region
1188   // lists. It will be compiled in the product code to be used when
1189   // necessary (i.e., during heap verification).
1190   void verify_region_sets();
1191 
1192   // verify_region_sets_optional() is planted in the code for
1193   // list verification in non-product builds (and it can be enabled in
1194   // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1195 #if HEAP_REGION_SET_FORCE_VERIFY
1196   void verify_region_sets_optional() {
1197     verify_region_sets();
1198   }
1199 #else // HEAP_REGION_SET_FORCE_VERIFY
1200   void verify_region_sets_optional() { }
1201 #endif // HEAP_REGION_SET_FORCE_VERIFY
1202 
1203 #ifdef ASSERT
1204   bool is_on_master_free_list(HeapRegion* hr) {
1205     return _hrm.is_free(hr);
1206   }
1207 #endif // ASSERT
1208 
1209   // Wrapper for the region list operations that can be called from
1210   // methods outside this class.
1211 
1212   void secondary_free_list_add(FreeRegionList* list) {
1213     _secondary_free_list.add_ordered(list);
1214   }
1215 
1216   void append_secondary_free_list() {
1217     _hrm.insert_list_into_free_list(&_secondary_free_list);
1218   }
1219 
1220   void append_secondary_free_list_if_not_empty_with_lock() {
1221     // If the secondary free list looks empty there's no reason to
1222     // take the lock and then try to append it.
1223     if (!_secondary_free_list.is_empty()) {
1224       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1225       append_secondary_free_list();
1226     }
1227   }
1228 
1229   inline void old_set_remove(HeapRegion* hr);
1230 
1231   size_t non_young_capacity_bytes() {
1232     return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1233   }
1234 
1235   void set_free_regions_coming();
1236   void reset_free_regions_coming();
1237   bool free_regions_coming() { return _free_regions_coming; }
1238   void wait_while_free_regions_coming();
1239 
1240   // Determine whether the given region is one that we are using as an
1241   // old GC alloc region.
1242   bool is_old_gc_alloc_region(HeapRegion* hr) {
1243     return _allocator->is_retained_old_region(hr);
1244   }
1245 
1246   // Perform a collection of the heap; intended for use in implementing
1247   // "System.gc".  This probably implies as full a collection as the
1248   // "CollectedHeap" supports.
1249   virtual void collect(GCCause::Cause cause);
1250 
1251   // The same as above but assume that the caller holds the Heap_lock.
1252   void collect_locked(GCCause::Cause cause);
1253 
1254   virtual void copy_allocation_context_stats(const jint* contexts,
1255                                              jlong* totals,
1256                                              jbyte* accuracy,
1257                                              jint len);
1258 
1259   // True iff an evacuation has failed in the most-recent collection.
1260   bool evacuation_failed() { return _evacuation_failed; }
1261 
1262   void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1263   void prepend_to_freelist(FreeRegionList* list);
1264   void decrement_summary_bytes(size_t bytes);
1265 
1266   // Returns "TRUE" iff "p" points into the committed areas of the heap.
1267   virtual bool is_in(const void* p) const;
1268 #ifdef ASSERT
1269   // Returns whether p is in one of the available areas of the heap. Slow but
1270   // extensive version.
1271   bool is_in_exact(const void* p) const;
1272 #endif
1273 
1274   // Return "TRUE" iff the given object address is within the collection
1275   // set. Slow implementation.
1276   inline bool obj_in_cs(oop obj);
1277 
1278   inline bool is_in_cset(oop obj);
1279 
1280   inline bool is_in_cset_or_humongous(const oop obj);
1281 
1282   enum in_cset_state_t {
1283    InNeither,           // neither in collection set nor humongous
1284    InCSet,              // region is in collection set only
1285    IsHumongous          // region is a humongous start region
1286   };
1287  private:
1288   // Instances of this class are used for quick tests on whether a reference points
1289   // into the collection set or is a humongous object (points into a humongous
1290   // object).
1291   // Each of the array's elements denotes whether the corresponding region is in
1292   // the collection set or a humongous region.
1293   // We use this to quickly reclaim humongous objects: by making a humongous region
1294   // succeed this test, we sort-of add it to the collection set. During the reference
1295   // iteration closures, when we see a humongous region, we simply mark it as
1296   // referenced, i.e. live.
1297   class G1FastCSetBiasedMappedArray : public G1BiasedMappedArray<char> {
1298    protected:
1299     char default_value() const { return G1CollectedHeap::InNeither; }
1300    public:
1301     void set_humongous(uintptr_t index) {
1302       assert(get_by_index(index) != InCSet, "Should not overwrite InCSet values");
1303       set_by_index(index, G1CollectedHeap::IsHumongous);
1304     }
1305 
1306     void clear_humongous(uintptr_t index) {
1307       set_by_index(index, G1CollectedHeap::InNeither);
1308     }
1309 
1310     void set_in_cset(uintptr_t index) {
1311       assert(get_by_index(index) != G1CollectedHeap::IsHumongous, "Should not overwrite IsHumongous value");
1312       set_by_index(index, G1CollectedHeap::InCSet);
1313     }
1314 
1315     bool is_in_cset_or_humongous(HeapWord* addr) const { return get_by_address(addr) != G1CollectedHeap::InNeither; }
1316     bool is_in_cset(HeapWord* addr) const { return get_by_address(addr) == G1CollectedHeap::InCSet; }
1317     G1CollectedHeap::in_cset_state_t at(HeapWord* addr) const { return (G1CollectedHeap::in_cset_state_t)get_by_address(addr); }
1318     void clear() { G1BiasedMappedArray<char>::clear(); }
1319   };
1320 
1321   // This array is used for a quick test on whether a reference points into
1322   // the collection set or not. Each of the array's elements denotes whether the
1323   // corresponding region is in the collection set or not.
1324   G1FastCSetBiasedMappedArray _in_cset_fast_test;
1325 
1326  public:
1327 
1328   inline in_cset_state_t in_cset_state(const oop obj);
1329 
1330   // Return "TRUE" iff the given object address is in the reserved
1331   // region of g1.
1332   bool is_in_g1_reserved(const void* p) const {
1333     return _hrm.reserved().contains(p);
1334   }
1335 
1336   // Returns a MemRegion that corresponds to the space that has been
1337   // reserved for the heap
1338   MemRegion g1_reserved() const {
1339     return _hrm.reserved();
1340   }
1341 
1342   virtual bool is_in_closed_subset(const void* p) const;
1343 
1344   G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1345     return (G1SATBCardTableLoggingModRefBS*) barrier_set();
1346   }
1347 
1348   // This resets the card table to all zeros.  It is used after
1349   // a collection pause which used the card table to claim cards.
1350   void cleanUpCardTable();
1351 
1352   // Iteration functions.
1353 
1354   // Iterate over all the ref-containing fields of all objects, calling
1355   // "cl.do_oop" on each.
1356   virtual void oop_iterate(ExtendedOopClosure* cl);
1357 
1358   // Iterate over all objects, calling "cl.do_object" on each.
1359   virtual void object_iterate(ObjectClosure* cl);
1360 
1361   virtual void safe_object_iterate(ObjectClosure* cl) {
1362     object_iterate(cl);
1363   }
1364 
1365   // Iterate over all spaces in use in the heap, in ascending address order.
1366   virtual void space_iterate(SpaceClosure* cl);
1367 
1368   // Iterate over heap regions, in address order, terminating the
1369   // iteration early if the "doHeapRegion" method returns "true".
1370   void heap_region_iterate(HeapRegionClosure* blk) const;
1371 
1372   // Return the region with the given index. It assumes the index is valid.
1373   inline HeapRegion* region_at(uint index) const;
1374 
1375   // Calculate the region index of the given address. Given address must be
1376   // within the heap.
1377   inline uint addr_to_region(HeapWord* addr) const;
1378 
1379   inline HeapWord* bottom_addr_for_region(uint index) const;
1380 
1381   // Iterate over the heap regions in parallel. Assumes that this will be called
1382   // in parallel by ParallelGCThreads worker threads with distinct worker ids
1383   // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1384   // to each of the regions, by attempting to claim the region using the
1385   // HeapRegionClaimer and, if successful, applying the closure to the claimed
1386   // region.
1387   void heap_region_par_iterate(HeapRegionClosure* cl,
1388                                uint worker_id,
1389                                HeapRegionClaimer* hrclaimer) const;
1390 
1391   // Clear the cached cset start regions and (more importantly)
1392   // the time stamps. Called when we reset the GC time stamp.
1393   void clear_cset_start_regions();
1394 
1395   // Given the id of a worker, obtain or calculate a suitable
1396   // starting region for iterating over the current collection set.
1397   HeapRegion* start_cset_region_for_worker(uint worker_i);
1398 
1399   // Iterate over the regions (if any) in the current collection set.
1400   void collection_set_iterate(HeapRegionClosure* blk);
1401 
1402   // As above but starting from region r
1403   void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1404 
1405   HeapRegion* next_compaction_region(const HeapRegion* from) const;
1406 
1407   // A CollectedHeap will contain some number of spaces.  This finds the
1408   // space containing a given address, or else returns NULL.
1409   virtual Space* space_containing(const void* addr) const;
1410 
1411   // Returns the HeapRegion that contains addr. addr must not be NULL.
1412   template <class T>
1413   inline HeapRegion* heap_region_containing_raw(const T addr) const;
1414 
1415   // Returns the HeapRegion that contains addr. addr must not be NULL.
1416   // If addr is within a humongous continues region, it returns its humongous start region.
1417   template <class T>
1418   inline HeapRegion* heap_region_containing(const T addr) const;
1419 
1420   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1421   // each address in the (reserved) heap is a member of exactly
1422   // one block.  The defining characteristic of a block is that it is
1423   // possible to find its size, and thus to progress forward to the next
1424   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1425   // represent Java objects, or they might be free blocks in a
1426   // free-list-based heap (or subheap), as long as the two kinds are
1427   // distinguishable and the size of each is determinable.
1428 
1429   // Returns the address of the start of the "block" that contains the
1430   // address "addr".  We say "blocks" instead of "object" since some heaps
1431   // may not pack objects densely; a chunk may either be an object or a
1432   // non-object.
1433   virtual HeapWord* block_start(const void* addr) const;
1434 
1435   // Requires "addr" to be the start of a chunk, and returns its size.
1436   // "addr + size" is required to be the start of a new chunk, or the end
1437   // of the active area of the heap.
1438   virtual size_t block_size(const HeapWord* addr) const;
1439 
1440   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1441   // the block is an object.
1442   virtual bool block_is_obj(const HeapWord* addr) const;
1443 
1444   // Does this heap support heap inspection? (+PrintClassHistogram)
1445   virtual bool supports_heap_inspection() const { return true; }
1446 
1447   // Section on thread-local allocation buffers (TLABs)
1448   // See CollectedHeap for semantics.
1449 
1450   bool supports_tlab_allocation() const;
1451   size_t tlab_capacity(Thread* ignored) const;
1452   size_t tlab_used(Thread* ignored) const;
1453   size_t max_tlab_size() const;
1454   size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1455 
1456   // Can a compiler initialize a new object without store barriers?
1457   // This permission only extends from the creation of a new object
1458   // via a TLAB up to the first subsequent safepoint. If such permission
1459   // is granted for this heap type, the compiler promises to call
1460   // defer_store_barrier() below on any slow path allocation of
1461   // a new object for which such initializing store barriers will
1462   // have been elided. G1, like CMS, allows this, but should be
1463   // ready to provide a compensating write barrier as necessary
1464   // if that storage came out of a non-young region. The efficiency
1465   // of this implementation depends crucially on being able to
1466   // answer very efficiently in constant time whether a piece of
1467   // storage in the heap comes from a young region or not.
1468   // See ReduceInitialCardMarks.
1469   virtual bool can_elide_tlab_store_barriers() const {
1470     return true;
1471   }
1472 
1473   virtual bool card_mark_must_follow_store() const {
1474     return true;
1475   }
1476 
1477   inline bool is_in_young(const oop obj);
1478 
1479 #ifdef ASSERT
1480   virtual bool is_in_partial_collection(const void* p);
1481 #endif
1482 
1483   virtual bool is_scavengable(const void* addr);
1484 
1485   // We don't need barriers for initializing stores to objects
1486   // in the young gen: for the SATB pre-barrier, there is no
1487   // pre-value that needs to be remembered; for the remembered-set
1488   // update logging post-barrier, we don't maintain remembered set
1489   // information for young gen objects.
1490   virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1491 
1492   // Returns "true" iff the given word_size is "very large".
1493   static bool is_humongous(size_t word_size) {
1494     // Note this has to be strictly greater-than as the TLABs
1495     // are capped at the humongous threshold and we want to
1496     // ensure that we don't try to allocate a TLAB as
1497     // humongous and that we don't allocate a humongous
1498     // object in a TLAB.
1499     return word_size > _humongous_object_threshold_in_words;
1500   }
1501 
1502   // Update mod union table with the set of dirty cards.
1503   void updateModUnion();
1504 
1505   // Set the mod union bits corresponding to the given memRegion.  Note
1506   // that this is always a safe operation, since it doesn't clear any
1507   // bits.
1508   void markModUnionRange(MemRegion mr);
1509 
1510   // Records the fact that a marking phase is no longer in progress.
1511   void set_marking_complete() {
1512     _mark_in_progress = false;
1513   }
1514   void set_marking_started() {
1515     _mark_in_progress = true;
1516   }
1517   bool mark_in_progress() {
1518     return _mark_in_progress;
1519   }
1520 
1521   // Print the maximum heap capacity.
1522   virtual size_t max_capacity() const;
1523 
1524   virtual jlong millis_since_last_gc();
1525 
1526 
1527   // Convenience function to be used in situations where the heap type can be
1528   // asserted to be this type.
1529   static G1CollectedHeap* heap();
1530 
1531   void set_region_short_lived_locked(HeapRegion* hr);
1532   // add appropriate methods for any other surv rate groups
1533 
1534   YoungList* young_list() const { return _young_list; }
1535 
1536   // debugging
1537   bool check_young_list_well_formed() {
1538     return _young_list->check_list_well_formed();
1539   }
1540 
1541   bool check_young_list_empty(bool check_heap,
1542                               bool check_sample = true);
1543 
1544   // *** Stuff related to concurrent marking.  It's not clear to me that so
1545   // many of these need to be public.
1546 
1547   // The functions below are helper functions that a subclass of
1548   // "CollectedHeap" can use in the implementation of its virtual
1549   // functions.
1550   // This performs a concurrent marking of the live objects in a
1551   // bitmap off to the side.
1552   void doConcurrentMark();
1553 
1554   bool isMarkedPrev(oop obj) const;
1555   bool isMarkedNext(oop obj) const;
1556 
1557   // Determine if an object is dead, given the object and also
1558   // the region to which the object belongs. An object is dead
1559   // iff a) it was not allocated since the last mark and b) it
1560   // is not marked.
1561   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1562     return
1563       !hr->obj_allocated_since_prev_marking(obj) &&
1564       !isMarkedPrev(obj);
1565   }
1566 
1567   // This function returns true when an object has been
1568   // around since the previous marking and hasn't yet
1569   // been marked during this marking.
1570   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1571     return
1572       !hr->obj_allocated_since_next_marking(obj) &&
1573       !isMarkedNext(obj);
1574   }
1575 
1576   // Determine if an object is dead, given only the object itself.
1577   // This will find the region to which the object belongs and
1578   // then call the region version of the same function.
1579 
1580   // Added if it is NULL it isn't dead.
1581 
1582   inline bool is_obj_dead(const oop obj) const;
1583 
1584   inline bool is_obj_ill(const oop obj) const;
1585 
1586   bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1587   HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1588   bool is_marked(oop obj, VerifyOption vo);
1589   const char* top_at_mark_start_str(VerifyOption vo);
1590 
1591   ConcurrentMark* concurrent_mark() const { return _cm; }
1592 
1593   // Refinement
1594 
1595   ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1596 
1597   // The dirty cards region list is used to record a subset of regions
1598   // whose cards need clearing. The list if populated during the
1599   // remembered set scanning and drained during the card table
1600   // cleanup. Although the methods are reentrant, population/draining
1601   // phases must not overlap. For synchronization purposes the last
1602   // element on the list points to itself.
1603   HeapRegion* _dirty_cards_region_list;
1604   void push_dirty_cards_region(HeapRegion* hr);
1605   HeapRegion* pop_dirty_cards_region();
1606 
1607   // Optimized nmethod scanning support routines
1608 
1609   // Register the given nmethod with the G1 heap.
1610   virtual void register_nmethod(nmethod* nm);
1611 
1612   // Unregister the given nmethod from the G1 heap.
1613   virtual void unregister_nmethod(nmethod* nm);
1614 
1615   // Free up superfluous code root memory.
1616   void purge_code_root_memory();
1617 
1618   // Rebuild the strong code root lists for each region
1619   // after a full GC.
1620   void rebuild_strong_code_roots();
1621 
1622   // Delete entries for dead interned string and clean up unreferenced symbols
1623   // in symbol table, possibly in parallel.
1624   void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1625 
1626   // Parallel phase of unloading/cleaning after G1 concurrent mark.
1627   void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1628 
1629   // Redirty logged cards in the refinement queue.
1630   void redirty_logged_cards();
1631   // Verification
1632 
1633   // The following is just to alert the verification code
1634   // that a full collection has occurred and that the
1635   // remembered sets are no longer up to date.
1636   bool _full_collection;
1637   void set_full_collection() { _full_collection = true;}
1638   void clear_full_collection() {_full_collection = false;}
1639   bool full_collection() {return _full_collection;}
1640 
1641   // Perform any cleanup actions necessary before allowing a verification.
1642   virtual void prepare_for_verify();
1643 
1644   // Perform verification.
1645 
1646   // vo == UsePrevMarking  -> use "prev" marking information,
1647   // vo == UseNextMarking -> use "next" marking information
1648   // vo == UseMarkWord    -> use the mark word in the object header
1649   //
1650   // NOTE: Only the "prev" marking information is guaranteed to be
1651   // consistent most of the time, so most calls to this should use
1652   // vo == UsePrevMarking.
1653   // Currently, there is only one case where this is called with
1654   // vo == UseNextMarking, which is to verify the "next" marking
1655   // information at the end of remark.
1656   // Currently there is only one place where this is called with
1657   // vo == UseMarkWord, which is to verify the marking during a
1658   // full GC.
1659   void verify(bool silent, VerifyOption vo);
1660 
1661   // Override; it uses the "prev" marking information
1662   virtual void verify(bool silent);
1663 
1664   // The methods below are here for convenience and dispatch the
1665   // appropriate method depending on value of the given VerifyOption
1666   // parameter. The values for that parameter, and their meanings,
1667   // are the same as those above.
1668 
1669   bool is_obj_dead_cond(const oop obj,
1670                         const HeapRegion* hr,
1671                         const VerifyOption vo) const;
1672 
1673   bool is_obj_dead_cond(const oop obj,
1674                         const VerifyOption vo) const;
1675 
1676   // Printing
1677 
1678   virtual void print_on(outputStream* st) const;
1679   virtual void print_extended_on(outputStream* st) const;
1680   virtual void print_on_error(outputStream* st) const;
1681 
1682   virtual void print_gc_threads_on(outputStream* st) const;
1683   virtual void gc_threads_do(ThreadClosure* tc) const;
1684 
1685   // Override
1686   void print_tracing_info() const;
1687 
1688   // The following two methods are helpful for debugging RSet issues.
1689   void print_cset_rsets() PRODUCT_RETURN;
1690   void print_all_rsets() PRODUCT_RETURN;
1691 
1692 public:
1693   size_t pending_card_num();
1694   size_t cards_scanned();
1695 
1696 protected:
1697   size_t _max_heap_capacity;
1698 };
1699 
1700 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
--- EOF ---