1 /*
   2  * Copyright (c) 2001, 2012, 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/concurrentMark.hpp"
  29 #include "gc_implementation/g1/g1AllocRegion.hpp"
  30 #include "gc_implementation/g1/g1HRPrinter.hpp"
  31 #include "gc_implementation/g1/g1RemSet.hpp"
  32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
  33 #include "gc_implementation/g1/heapRegionSeq.hpp"
  34 #include "gc_implementation/g1/heapRegionSets.hpp"
  35 #include "gc_implementation/shared/hSpaceCounters.hpp"
  36 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
  37 #include "memory/barrierSet.hpp"
  38 #include "memory/memRegion.hpp"
  39 #include "memory/sharedHeap.hpp"
  40 
  41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
  42 // It uses the "Garbage First" heap organization and algorithm, which
  43 // may combine concurrent marking with parallel, incremental compaction of
  44 // heap subsets that will yield large amounts of garbage.
  45 
  46 class HeapRegion;
  47 class HRRSCleanupTask;
  48 class PermanentGenerationSpec;
  49 class GenerationSpec;
  50 class OopsInHeapRegionClosure;
  51 class G1ScanHeapEvacClosure;
  52 class ObjectClosure;
  53 class SpaceClosure;
  54 class CompactibleSpaceClosure;
  55 class Space;
  56 class G1CollectorPolicy;
  57 class GenRemSet;
  58 class G1RemSet;
  59 class HeapRegionRemSetIterator;
  60 class ConcurrentMark;
  61 class ConcurrentMarkThread;
  62 class ConcurrentG1Refine;
  63 class GenerationCounters;
  64 
  65 typedef OverflowTaskQueue<StarTask>         RefToScanQueue;
  66 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
  67 
  68 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
  69 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
  70 
  71 enum GCAllocPurpose {
  72   GCAllocForTenured,
  73   GCAllocForSurvived,
  74   GCAllocPurposeCount
  75 };
  76 
  77 class YoungList : public CHeapObj {
  78 private:
  79   G1CollectedHeap* _g1h;
  80 
  81   HeapRegion* _head;
  82 
  83   HeapRegion* _survivor_head;
  84   HeapRegion* _survivor_tail;
  85 
  86   HeapRegion* _curr;
  87 
  88   uint        _length;
  89   uint        _survivor_length;
  90 
  91   size_t      _last_sampled_rs_lengths;
  92   size_t      _sampled_rs_lengths;
  93 
  94   void         empty_list(HeapRegion* list);
  95 
  96 public:
  97   YoungList(G1CollectedHeap* g1h);
  98 
  99   void         push_region(HeapRegion* hr);
 100   void         add_survivor_region(HeapRegion* hr);
 101 
 102   void         empty_list();
 103   bool         is_empty() { return _length == 0; }
 104   uint         length() { return _length; }
 105   uint         survivor_length() { return _survivor_length; }
 106 
 107   // Currently we do not keep track of the used byte sum for the
 108   // young list and the survivors and it'd be quite a lot of work to
 109   // do so. When we'll eventually replace the young list with
 110   // instances of HeapRegionLinkedList we'll get that for free. So,
 111   // we'll report the more accurate information then.
 112   size_t       eden_used_bytes() {
 113     assert(length() >= survivor_length(), "invariant");
 114     return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
 115   }
 116   size_t       survivor_used_bytes() {
 117     return (size_t) survivor_length() * HeapRegion::GrainBytes;
 118   }
 119 
 120   void rs_length_sampling_init();
 121   bool rs_length_sampling_more();
 122   void rs_length_sampling_next();
 123 
 124   void reset_sampled_info() {
 125     _last_sampled_rs_lengths =   0;
 126   }
 127   size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
 128 
 129   // for development purposes
 130   void reset_auxilary_lists();
 131   void clear() { _head = NULL; _length = 0; }
 132 
 133   void clear_survivors() {
 134     _survivor_head    = NULL;
 135     _survivor_tail    = NULL;
 136     _survivor_length  = 0;
 137   }
 138 
 139   HeapRegion* first_region() { return _head; }
 140   HeapRegion* first_survivor_region() { return _survivor_head; }
 141   HeapRegion* last_survivor_region() { return _survivor_tail; }
 142 
 143   // debugging
 144   bool          check_list_well_formed();
 145   bool          check_list_empty(bool check_sample = true);
 146   void          print();
 147 };
 148 
 149 class MutatorAllocRegion : public G1AllocRegion {
 150 protected:
 151   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
 152   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 153 public:
 154   MutatorAllocRegion()
 155     : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
 156 };
 157 
 158 // The G1 STW is alive closure.
 159 // An instance is embedded into the G1CH and used as the
 160 // (optional) _is_alive_non_header closure in the STW
 161 // reference processor. It is also extensively used during
 162 // refence processing during STW evacuation pauses.
 163 class G1STWIsAliveClosure: public BoolObjectClosure {
 164   G1CollectedHeap* _g1;
 165 public:
 166   G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
 167   void do_object(oop p) { assert(false, "Do not call."); }
 168   bool do_object_b(oop p);
 169 };
 170 
 171 class SurvivorGCAllocRegion : public G1AllocRegion {
 172 protected:
 173   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
 174   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 175 public:
 176   SurvivorGCAllocRegion()
 177   : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
 178 };
 179 
 180 class OldGCAllocRegion : public G1AllocRegion {
 181 protected:
 182   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
 183   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 184 public:
 185   OldGCAllocRegion()
 186   : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
 187 };
 188 
 189 class RefineCardTableEntryClosure;
 190 
 191 class G1CollectedHeap : public SharedHeap {
 192   friend class VM_G1CollectForAllocation;
 193   friend class VM_GenCollectForPermanentAllocation;
 194   friend class VM_G1CollectFull;
 195   friend class VM_G1IncCollectionPause;
 196   friend class VMStructs;
 197   friend class MutatorAllocRegion;
 198   friend class SurvivorGCAllocRegion;
 199   friend class OldGCAllocRegion;
 200 
 201   // Closures used in implementation.
 202   template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
 203   friend class G1ParCopyClosure;
 204   friend class G1IsAliveClosure;
 205   friend class G1EvacuateFollowersClosure;
 206   friend class G1ParScanThreadState;
 207   friend class G1ParScanClosureSuper;
 208   friend class G1ParEvacuateFollowersClosure;
 209   friend class G1ParTask;
 210   friend class G1FreeGarbageRegionClosure;
 211   friend class RefineCardTableEntryClosure;
 212   friend class G1PrepareCompactClosure;
 213   friend class RegionSorter;
 214   friend class RegionResetter;
 215   friend class CountRCClosure;
 216   friend class EvacPopObjClosure;
 217   friend class G1ParCleanupCTTask;
 218 
 219   // Other related classes.
 220   friend class G1MarkSweep;
 221 
 222 private:
 223   // The one and only G1CollectedHeap, so static functions can find it.
 224   static G1CollectedHeap* _g1h;
 225 
 226   static size_t _humongous_object_threshold_in_words;
 227 
 228   // Storage for the G1 heap (excludes the permanent generation).
 229   VirtualSpace _g1_storage;
 230   MemRegion    _g1_reserved;
 231 
 232   // The part of _g1_storage that is currently committed.
 233   MemRegion _g1_committed;
 234 
 235   // The master free list. It will satisfy all new region allocations.
 236   MasterFreeRegionList      _free_list;
 237 
 238   // The secondary free list which contains regions that have been
 239   // freed up during the cleanup process. This will be appended to the
 240   // master free list when appropriate.
 241   SecondaryFreeRegionList   _secondary_free_list;
 242 
 243   // It keeps track of the old regions.
 244   MasterOldRegionSet        _old_set;
 245 
 246   // It keeps track of the humongous regions.
 247   MasterHumongousRegionSet  _humongous_set;
 248 
 249   // The number of regions we could create by expansion.
 250   uint _expansion_regions;
 251 
 252   // The block offset table for the G1 heap.
 253   G1BlockOffsetSharedArray* _bot_shared;
 254 
 255   // Tears down the region sets / lists so that they are empty and the
 256   // regions on the heap do not belong to a region set / list. The
 257   // only exception is the humongous set which we leave unaltered. If
 258   // free_list_only is true, it will only tear down the master free
 259   // list. It is called before a Full GC (free_list_only == false) or
 260   // before heap shrinking (free_list_only == true).
 261   void tear_down_region_sets(bool free_list_only);
 262 
 263   // Rebuilds the region sets / lists so that they are repopulated to
 264   // reflect the contents of the heap. The only exception is the
 265   // humongous set which was not torn down in the first place. If
 266   // free_list_only is true, it will only rebuild the master free
 267   // list. It is called after a Full GC (free_list_only == false) or
 268   // after heap shrinking (free_list_only == true).
 269   void rebuild_region_sets(bool free_list_only);
 270 
 271   // The sequence of all heap regions in the heap.
 272   HeapRegionSeq _hrs;
 273 
 274   // Alloc region used to satisfy mutator allocation requests.
 275   MutatorAllocRegion _mutator_alloc_region;
 276 
 277   // Alloc region used to satisfy allocation requests by the GC for
 278   // survivor objects.
 279   SurvivorGCAllocRegion _survivor_gc_alloc_region;
 280 
 281   // Alloc region used to satisfy allocation requests by the GC for
 282   // old objects.
 283   OldGCAllocRegion _old_gc_alloc_region;
 284 
 285   // The last old region we allocated to during the last GC.
 286   // Typically, it is not full so we should re-use it during the next GC.
 287   HeapRegion* _retained_old_gc_alloc_region;
 288 
 289   // It specifies whether we should attempt to expand the heap after a
 290   // region allocation failure. If heap expansion fails we set this to
 291   // false so that we don't re-attempt the heap expansion (it's likely
 292   // that subsequent expansion attempts will also fail if one fails).
 293   // Currently, it is only consulted during GC and it's reset at the
 294   // start of each GC.
 295   bool _expand_heap_after_alloc_failure;
 296 
 297   // It resets the mutator alloc region before new allocations can take place.
 298   void init_mutator_alloc_region();
 299 
 300   // It releases the mutator alloc region.
 301   void release_mutator_alloc_region();
 302 
 303   // It initializes the GC alloc regions at the start of a GC.
 304   void init_gc_alloc_regions();
 305 
 306   // It releases the GC alloc regions at the end of a GC.
 307   void release_gc_alloc_regions();
 308 
 309   // It does any cleanup that needs to be done on the GC alloc regions
 310   // before a Full GC.
 311   void abandon_gc_alloc_regions();
 312 
 313   // Helper for monitoring and management support.
 314   G1MonitoringSupport* _g1mm;
 315 
 316   // Determines PLAB size for a particular allocation purpose.
 317   static size_t desired_plab_sz(GCAllocPurpose purpose);
 318 
 319   // Outside of GC pauses, the number of bytes used in all regions other
 320   // than the current allocation region.
 321   size_t _summary_bytes_used;
 322 
 323   // This is used for a quick test on whether a reference points into
 324   // the collection set or not. Basically, we have an array, with one
 325   // byte per region, and that byte denotes whether the corresponding
 326   // region is in the collection set or not. The entry corresponding
 327   // the bottom of the heap, i.e., region 0, is pointed to by
 328   // _in_cset_fast_test_base.  The _in_cset_fast_test field has been
 329   // biased so that it actually points to address 0 of the address
 330   // space, to make the test as fast as possible (we can simply shift
 331   // the address to address into it, instead of having to subtract the
 332   // bottom of the heap from the address before shifting it; basically
 333   // it works in the same way the card table works).
 334   bool* _in_cset_fast_test;
 335 
 336   // The allocated array used for the fast test on whether a reference
 337   // points into the collection set or not. This field is also used to
 338   // free the array.
 339   bool* _in_cset_fast_test_base;
 340 
 341   // The length of the _in_cset_fast_test_base array.
 342   uint _in_cset_fast_test_length;
 343 
 344   volatile unsigned _gc_time_stamp;
 345 
 346   size_t* _surviving_young_words;
 347 
 348   G1HRPrinter _hr_printer;
 349 
 350   void setup_surviving_young_words();
 351   void update_surviving_young_words(size_t* surv_young_words);
 352   void cleanup_surviving_young_words();
 353 
 354   // It decides whether an explicit GC should start a concurrent cycle
 355   // instead of doing a STW GC. Currently, a concurrent cycle is
 356   // explicitly started if:
 357   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
 358   // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
 359   // (c) cause == _g1_humongous_allocation
 360   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 361 
 362   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 363   // concurrent cycles) we have started.
 364   volatile unsigned int _old_marking_cycles_started;
 365 
 366   // Keeps track of how many "old marking cycles" (i.e., Full GCs or
 367   // concurrent cycles) we have completed.
 368   volatile unsigned int _old_marking_cycles_completed;
 369 
 370   // This is a non-product method that is helpful for testing. It is
 371   // called at the end of a GC and artificially expands the heap by
 372   // allocating a number of dead regions. This way we can induce very
 373   // frequent marking cycles and stress the cleanup / concurrent
 374   // cleanup code more (as all the regions that will be allocated by
 375   // this method will be found dead by the marking cycle).
 376   void allocate_dummy_regions() PRODUCT_RETURN;
 377 
 378   // These are macros so that, if the assert fires, we get the correct
 379   // line number, file, etc.
 380 
 381 #define heap_locking_asserts_err_msg(_extra_message_)                         \
 382   err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",    \
 383           (_extra_message_),                                                  \
 384           BOOL_TO_STR(Heap_lock->owned_by_self()),                            \
 385           BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),               \
 386           BOOL_TO_STR(Thread::current()->is_VM_thread()))
 387 
 388 #define assert_heap_locked()                                                  \
 389   do {                                                                        \
 390     assert(Heap_lock->owned_by_self(),                                        \
 391            heap_locking_asserts_err_msg("should be holding the Heap_lock"));  \
 392   } while (0)
 393 
 394 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
 395   do {                                                                        \
 396     assert(Heap_lock->owned_by_self() ||                                      \
 397            (SafepointSynchronize::is_at_safepoint() &&                        \
 398              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
 399            heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
 400                                         "should be at a safepoint"));         \
 401   } while (0)
 402 
 403 #define assert_heap_locked_and_not_at_safepoint()                             \
 404   do {                                                                        \
 405     assert(Heap_lock->owned_by_self() &&                                      \
 406                                     !SafepointSynchronize::is_at_safepoint(), \
 407           heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
 408                                        "should not be at a safepoint"));      \
 409   } while (0)
 410 
 411 #define assert_heap_not_locked()                                              \
 412   do {                                                                        \
 413     assert(!Heap_lock->owned_by_self(),                                       \
 414         heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
 415   } while (0)
 416 
 417 #define assert_heap_not_locked_and_not_at_safepoint()                         \
 418   do {                                                                        \
 419     assert(!Heap_lock->owned_by_self() &&                                     \
 420                                     !SafepointSynchronize::is_at_safepoint(), \
 421       heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
 422                                    "should not be at a safepoint"));          \
 423   } while (0)
 424 
 425 #define assert_at_safepoint(_should_be_vm_thread_)                            \
 426   do {                                                                        \
 427     assert(SafepointSynchronize::is_at_safepoint() &&                         \
 428               ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
 429            heap_locking_asserts_err_msg("should be at a safepoint"));         \
 430   } while (0)
 431 
 432 #define assert_not_at_safepoint()                                             \
 433   do {                                                                        \
 434     assert(!SafepointSynchronize::is_at_safepoint(),                          \
 435            heap_locking_asserts_err_msg("should not be at a safepoint"));     \
 436   } while (0)
 437 
 438 protected:
 439 
 440   // The young region list.
 441   YoungList*  _young_list;
 442 
 443   // The current policy object for the collector.
 444   G1CollectorPolicy* _g1_policy;
 445 
 446   // This is the second level of trying to allocate a new region. If
 447   // new_region() didn't find a region on the free_list, this call will
 448   // check whether there's anything available on the
 449   // secondary_free_list and/or wait for more regions to appear on
 450   // that list, if _free_regions_coming is set.
 451   HeapRegion* new_region_try_secondary_free_list();
 452 
 453   // Try to allocate a single non-humongous HeapRegion sufficient for
 454   // an allocation of the given word_size. If do_expand is true,
 455   // attempt to expand the heap if necessary to satisfy the allocation
 456   // request.
 457   HeapRegion* new_region(size_t word_size, bool do_expand);
 458 
 459   // Attempt to satisfy a humongous allocation request of the given
 460   // size by finding a contiguous set of free regions of num_regions
 461   // length and remove them from the master free list. Return the
 462   // index of the first region or G1_NULL_HRS_INDEX if the search
 463   // was unsuccessful.
 464   uint humongous_obj_allocate_find_first(uint num_regions,
 465                                          size_t word_size);
 466 
 467   // Initialize a contiguous set of free regions of length num_regions
 468   // and starting at index first so that they appear as a single
 469   // humongous region.
 470   HeapWord* humongous_obj_allocate_initialize_regions(uint first,
 471                                                       uint num_regions,
 472                                                       size_t word_size);
 473 
 474   // Attempt to allocate a humongous object of the given size. Return
 475   // NULL if unsuccessful.
 476   HeapWord* humongous_obj_allocate(size_t word_size);
 477 
 478   // The following two methods, allocate_new_tlab() and
 479   // mem_allocate(), are the two main entry points from the runtime
 480   // into the G1's allocation routines. They have the following
 481   // assumptions:
 482   //
 483   // * They should both be called outside safepoints.
 484   //
 485   // * They should both be called without holding the Heap_lock.
 486   //
 487   // * All allocation requests for new TLABs should go to
 488   //   allocate_new_tlab().
 489   //
 490   // * All non-TLAB allocation requests should go to mem_allocate().
 491   //
 492   // * If either call cannot satisfy the allocation request using the
 493   //   current allocating region, they will try to get a new one. If
 494   //   this fails, they will attempt to do an evacuation pause and
 495   //   retry the allocation.
 496   //
 497   // * If all allocation attempts fail, even after trying to schedule
 498   //   an evacuation pause, allocate_new_tlab() will return NULL,
 499   //   whereas mem_allocate() will attempt a heap expansion and/or
 500   //   schedule a Full GC.
 501   //
 502   // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
 503   //   should never be called with word_size being humongous. All
 504   //   humongous allocation requests should go to mem_allocate() which
 505   //   will satisfy them with a special path.
 506 
 507   virtual HeapWord* allocate_new_tlab(size_t word_size);
 508 
 509   virtual HeapWord* mem_allocate(size_t word_size,
 510                                  bool*  gc_overhead_limit_was_exceeded);
 511 
 512   // The following three methods take a gc_count_before_ret
 513   // parameter which is used to return the GC count if the method
 514   // returns NULL. Given that we are required to read the GC count
 515   // while holding the Heap_lock, and these paths will take the
 516   // Heap_lock at some point, it's easier to get them to read the GC
 517   // count while holding the Heap_lock before they return NULL instead
 518   // of the caller (namely: mem_allocate()) having to also take the
 519   // Heap_lock just to read the GC count.
 520 
 521   // First-level mutator allocation attempt: try to allocate out of
 522   // the mutator alloc region without taking the Heap_lock. This
 523   // should only be used for non-humongous allocations.
 524   inline HeapWord* attempt_allocation(size_t word_size,
 525                                       unsigned int* gc_count_before_ret);
 526 
 527   // Second-level mutator allocation attempt: take the Heap_lock and
 528   // retry the allocation attempt, potentially scheduling a GC
 529   // pause. This should only be used for non-humongous allocations.
 530   HeapWord* attempt_allocation_slow(size_t word_size,
 531                                     unsigned int* gc_count_before_ret);
 532 
 533   // Takes the Heap_lock and attempts a humongous allocation. It can
 534   // potentially schedule a GC pause.
 535   HeapWord* attempt_allocation_humongous(size_t word_size,
 536                                          unsigned int* gc_count_before_ret);
 537 
 538   // Allocation attempt that should be called during safepoints (e.g.,
 539   // at the end of a successful GC). expect_null_mutator_alloc_region
 540   // specifies whether the mutator alloc region is expected to be NULL
 541   // or not.
 542   HeapWord* attempt_allocation_at_safepoint(size_t word_size,
 543                                        bool expect_null_mutator_alloc_region);
 544 
 545   // It dirties the cards that cover the block so that so that the post
 546   // write barrier never queues anything when updating objects on this
 547   // block. It is assumed (and in fact we assert) that the block
 548   // belongs to a young region.
 549   inline void dirty_young_block(HeapWord* start, size_t word_size);
 550 
 551   // Allocate blocks during garbage collection. Will ensure an
 552   // allocation region, either by picking one or expanding the
 553   // heap, and then allocate a block of the given size. The block
 554   // may not be a humongous - it must fit into a single heap region.
 555   HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
 556 
 557   HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
 558                                     HeapRegion*    alloc_region,
 559                                     bool           par,
 560                                     size_t         word_size);
 561 
 562   // Ensure that no further allocations can happen in "r", bearing in mind
 563   // that parallel threads might be attempting allocations.
 564   void par_allocate_remaining_space(HeapRegion* r);
 565 
 566   // Allocation attempt during GC for a survivor object / PLAB.
 567   inline HeapWord* survivor_attempt_allocation(size_t word_size);
 568 
 569   // Allocation attempt during GC for an old object / PLAB.
 570   inline HeapWord* old_attempt_allocation(size_t word_size);
 571 
 572   // These methods are the "callbacks" from the G1AllocRegion class.
 573 
 574   // For mutator alloc regions.
 575   HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
 576   void retire_mutator_alloc_region(HeapRegion* alloc_region,
 577                                    size_t allocated_bytes);
 578 
 579   // For GC alloc regions.
 580   HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
 581                                   GCAllocPurpose ap);
 582   void retire_gc_alloc_region(HeapRegion* alloc_region,
 583                               size_t allocated_bytes, GCAllocPurpose ap);
 584 
 585   // - if explicit_gc is true, the GC is for a System.gc() or a heap
 586   //   inspection request and should collect the entire heap
 587   // - if clear_all_soft_refs is true, all soft references should be
 588   //   cleared during the GC
 589   // - if explicit_gc is false, word_size describes the allocation that
 590   //   the GC should attempt (at least) to satisfy
 591   // - it returns false if it is unable to do the collection due to the
 592   //   GC locker being active, true otherwise
 593   bool do_collection(bool explicit_gc,
 594                      bool clear_all_soft_refs,
 595                      size_t word_size);
 596 
 597   // Callback from VM_G1CollectFull operation.
 598   // Perform a full collection.
 599   void do_full_collection(bool clear_all_soft_refs);
 600 
 601   // Resize the heap if necessary after a full collection.  If this is
 602   // after a collect-for allocation, "word_size" is the allocation size,
 603   // and will be considered part of the used portion of the heap.
 604   void resize_if_necessary_after_full_collection(size_t word_size);
 605 
 606   // Callback from VM_G1CollectForAllocation operation.
 607   // This function does everything necessary/possible to satisfy a
 608   // failed allocation request (including collection, expansion, etc.)
 609   HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
 610 
 611   // Attempting to expand the heap sufficiently
 612   // to support an allocation of the given "word_size".  If
 613   // successful, perform the allocation and return the address of the
 614   // allocated block, or else "NULL".
 615   HeapWord* expand_and_allocate(size_t word_size);
 616 
 617   // Process any reference objects discovered during
 618   // an incremental evacuation pause.
 619   void process_discovered_references();
 620 
 621   // Enqueue any remaining discovered references
 622   // after processing.
 623   void enqueue_discovered_references();
 624 
 625 public:
 626 
 627   G1MonitoringSupport* g1mm() {
 628     assert(_g1mm != NULL, "should have been initialized");
 629     return _g1mm;
 630   }
 631 
 632   // Expand the garbage-first heap by at least the given size (in bytes!).
 633   // Returns true if the heap was expanded by the requested amount;
 634   // false otherwise.
 635   // (Rounds up to a HeapRegion boundary.)
 636   bool expand(size_t expand_bytes);
 637 
 638   // Do anything common to GC's.
 639   virtual void gc_prologue(bool full);
 640   virtual void gc_epilogue(bool full);
 641 
 642   // We register a region with the fast "in collection set" test. We
 643   // simply set to true the array slot corresponding to this region.
 644   void register_region_with_in_cset_fast_test(HeapRegion* r) {
 645     assert(_in_cset_fast_test_base != NULL, "sanity");
 646     assert(r->in_collection_set(), "invariant");
 647     uint index = r->hrs_index();
 648     assert(index < _in_cset_fast_test_length, "invariant");
 649     assert(!_in_cset_fast_test_base[index], "invariant");
 650     _in_cset_fast_test_base[index] = true;
 651   }
 652 
 653   // This is a fast test on whether a reference points into the
 654   // collection set or not. It does not assume that the reference
 655   // points into the heap; if it doesn't, it will return false.
 656   bool in_cset_fast_test(oop obj) {
 657     assert(_in_cset_fast_test != NULL, "sanity");
 658     if (_g1_committed.contains((HeapWord*) obj)) {
 659       // no need to subtract the bottom of the heap from obj,
 660       // _in_cset_fast_test is biased
 661       uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
 662       bool ret = _in_cset_fast_test[index];
 663       // let's make sure the result is consistent with what the slower
 664       // test returns
 665       assert( ret || !obj_in_cs(obj), "sanity");
 666       assert(!ret ||  obj_in_cs(obj), "sanity");
 667       return ret;
 668     } else {
 669       return false;
 670     }
 671   }
 672 
 673   void clear_cset_fast_test() {
 674     assert(_in_cset_fast_test_base != NULL, "sanity");
 675     memset(_in_cset_fast_test_base, false,
 676            (size_t) _in_cset_fast_test_length * sizeof(bool));
 677   }
 678 
 679   // This is called at the start of either a concurrent cycle or a Full
 680   // GC to update the number of old marking cycles started.
 681   void increment_old_marking_cycles_started();
 682 
 683   // This is called at the end of either a concurrent cycle or a Full
 684   // GC to update the number of old marking cycles completed. Those two
 685   // can happen in a nested fashion, i.e., we start a concurrent
 686   // cycle, a Full GC happens half-way through it which ends first,
 687   // and then the cycle notices that a Full GC happened and ends
 688   // too. The concurrent parameter is a boolean to help us do a bit
 689   // tighter consistency checking in the method. If concurrent is
 690   // false, the caller is the inner caller in the nesting (i.e., the
 691   // Full GC). If concurrent is true, the caller is the outer caller
 692   // in this nesting (i.e., the concurrent cycle). Further nesting is
 693   // not currently supported. The end of this call also notifies
 694   // the FullGCCount_lock in case a Java thread is waiting for a full
 695   // GC to happen (e.g., it called System.gc() with
 696   // +ExplicitGCInvokesConcurrent).
 697   void increment_old_marking_cycles_completed(bool concurrent);
 698 
 699   unsigned int old_marking_cycles_completed() {
 700     return _old_marking_cycles_completed;
 701   }
 702 
 703   G1HRPrinter* hr_printer() { return &_hr_printer; }
 704 
 705 protected:
 706 
 707   // Shrink the garbage-first heap by at most the given size (in bytes!).
 708   // (Rounds down to a HeapRegion boundary.)
 709   virtual void shrink(size_t expand_bytes);
 710   void shrink_helper(size_t expand_bytes);
 711 
 712   #if TASKQUEUE_STATS
 713   static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
 714   void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
 715   void reset_taskqueue_stats();
 716   #endif // TASKQUEUE_STATS
 717 
 718   // Schedule the VM operation that will do an evacuation pause to
 719   // satisfy an allocation request of word_size. *succeeded will
 720   // return whether the VM operation was successful (it did do an
 721   // evacuation pause) or not (another thread beat us to it or the GC
 722   // locker was active). Given that we should not be holding the
 723   // Heap_lock when we enter this method, we will pass the
 724   // gc_count_before (i.e., total_collections()) as a parameter since
 725   // it has to be read while holding the Heap_lock. Currently, both
 726   // methods that call do_collection_pause() release the Heap_lock
 727   // before the call, so it's easy to read gc_count_before just before.
 728   HeapWord* do_collection_pause(size_t       word_size,
 729                                 unsigned int gc_count_before,
 730                                 bool*        succeeded);
 731 
 732   // The guts of the incremental collection pause, executed by the vm
 733   // thread. It returns false if it is unable to do the collection due
 734   // to the GC locker being active, true otherwise
 735   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 736 
 737   // Actually do the work of evacuating the collection set.
 738   void evacuate_collection_set();
 739 
 740   // The g1 remembered set of the heap.
 741   G1RemSet* _g1_rem_set;
 742   // And it's mod ref barrier set, used to track updates for the above.
 743   ModRefBarrierSet* _mr_bs;
 744 
 745   // A set of cards that cover the objects for which the Rsets should be updated
 746   // concurrently after the collection.
 747   DirtyCardQueueSet _dirty_card_queue_set;
 748 
 749   // The Heap Region Rem Set Iterator.
 750   HeapRegionRemSetIterator** _rem_set_iterator;
 751 
 752   // The closure used to refine a single card.
 753   RefineCardTableEntryClosure* _refine_cte_cl;
 754 
 755   // A function to check the consistency of dirty card logs.
 756   void check_ct_logs_at_safepoint();
 757 
 758   // A DirtyCardQueueSet that is used to hold cards that contain
 759   // references into the current collection set. This is used to
 760   // update the remembered sets of the regions in the collection
 761   // set in the event of an evacuation failure.
 762   DirtyCardQueueSet _into_cset_dirty_card_queue_set;
 763 
 764   // After a collection pause, make the regions in the CS into free
 765   // regions.
 766   void free_collection_set(HeapRegion* cs_head);
 767 
 768   // Abandon the current collection set without recording policy
 769   // statistics or updating free lists.
 770   void abandon_collection_set(HeapRegion* cs_head);
 771 
 772   // Applies "scan_non_heap_roots" to roots outside the heap,
 773   // "scan_rs" to roots inside the heap (having done "set_region" to
 774   // indicate the region in which the root resides), and does "scan_perm"
 775   // (setting the generation to the perm generation.)  If "scan_rs" is
 776   // NULL, then this step is skipped.  The "worker_i"
 777   // param is for use with parallel roots processing, and should be
 778   // the "i" of the calling parallel worker thread's work(i) function.
 779   // In the sequential case this param will be ignored.
 780   void g1_process_strong_roots(bool collecting_perm_gen,
 781                                ScanningOption so,
 782                                OopClosure* scan_non_heap_roots,
 783                                OopsInHeapRegionClosure* scan_rs,
 784                                OopsInGenClosure* scan_perm,
 785                                int worker_i);
 786 
 787   // Apply "blk" to all the weak roots of the system.  These include
 788   // JNI weak roots, the code cache, system dictionary, symbol table,
 789   // string table, and referents of reachable weak refs.
 790   void g1_process_weak_roots(OopClosure* root_closure,
 791                              OopClosure* non_root_closure);
 792 
 793   // Frees a non-humongous region by initializing its contents and
 794   // adding it to the free list that's passed as a parameter (this is
 795   // usually a local list which will be appended to the master free
 796   // list later). The used bytes of freed regions are accumulated in
 797   // pre_used. If par is true, the region's RSet will not be freed
 798   // up. The assumption is that this will be done later.
 799   void free_region(HeapRegion* hr,
 800                    size_t* pre_used,
 801                    FreeRegionList* free_list,
 802                    bool par);
 803 
 804   // Frees a humongous region by collapsing it into individual regions
 805   // and calling free_region() for each of them. The freed regions
 806   // will be added to the free list that's passed as a parameter (this
 807   // is usually a local list which will be appended to the master free
 808   // list later). The used bytes of freed regions are accumulated in
 809   // pre_used. If par is true, the region's RSet will not be freed
 810   // up. The assumption is that this will be done later.
 811   void free_humongous_region(HeapRegion* hr,
 812                              size_t* pre_used,
 813                              FreeRegionList* free_list,
 814                              HumongousRegionSet* humongous_proxy_set,
 815                              bool par);
 816 
 817   // Notifies all the necessary spaces that the committed space has
 818   // been updated (either expanded or shrunk). It should be called
 819   // after _g1_storage is updated.
 820   void update_committed_space(HeapWord* old_end, HeapWord* new_end);
 821 
 822   // The concurrent marker (and the thread it runs in.)
 823   ConcurrentMark* _cm;
 824   ConcurrentMarkThread* _cmThread;
 825   bool _mark_in_progress;
 826 
 827   // The concurrent refiner.
 828   ConcurrentG1Refine* _cg1r;
 829 
 830   // The parallel task queues
 831   RefToScanQueueSet *_task_queues;
 832 
 833   // True iff a evacuation has failed in the current collection.
 834   bool _evacuation_failed;
 835 
 836   // Set the attribute indicating whether evacuation has failed in the
 837   // current collection.
 838   void set_evacuation_failed(bool b) { _evacuation_failed = b; }
 839 
 840   // Failed evacuations cause some logical from-space objects to have
 841   // forwarding pointers to themselves.  Reset them.
 842   void remove_self_forwarding_pointers();
 843 
 844   // When one is non-null, so is the other.  Together, they each pair is
 845   // an object with a preserved mark, and its mark value.
 846   GrowableArray<oop>*     _objs_with_preserved_marks;
 847   GrowableArray<markOop>* _preserved_marks_of_objs;
 848 
 849   // Preserve the mark of "obj", if necessary, in preparation for its mark
 850   // word being overwritten with a self-forwarding-pointer.
 851   void preserve_mark_if_necessary(oop obj, markOop m);
 852 
 853   // The stack of evac-failure objects left to be scanned.
 854   GrowableArray<oop>*    _evac_failure_scan_stack;
 855   // The closure to apply to evac-failure objects.
 856 
 857   OopsInHeapRegionClosure* _evac_failure_closure;
 858   // Set the field above.
 859   void
 860   set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
 861     _evac_failure_closure = evac_failure_closure;
 862   }
 863 
 864   // Push "obj" on the scan stack.
 865   void push_on_evac_failure_scan_stack(oop obj);
 866   // Process scan stack entries until the stack is empty.
 867   void drain_evac_failure_scan_stack();
 868   // True iff an invocation of "drain_scan_stack" is in progress; to
 869   // prevent unnecessary recursion.
 870   bool _drain_in_progress;
 871 
 872   // Do any necessary initialization for evacuation-failure handling.
 873   // "cl" is the closure that will be used to process evac-failure
 874   // objects.
 875   void init_for_evac_failure(OopsInHeapRegionClosure* cl);
 876   // Do any necessary cleanup for evacuation-failure handling data
 877   // structures.
 878   void finalize_for_evac_failure();
 879 
 880   // An attempt to evacuate "obj" has failed; take necessary steps.
 881   oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
 882   void handle_evacuation_failure_common(oop obj, markOop m);
 883 
 884   // ("Weak") Reference processing support.
 885   //
 886   // G1 has 2 instances of the referece processor class. One
 887   // (_ref_processor_cm) handles reference object discovery
 888   // and subsequent processing during concurrent marking cycles.
 889   //
 890   // The other (_ref_processor_stw) handles reference object
 891   // discovery and processing during full GCs and incremental
 892   // evacuation pauses.
 893   //
 894   // During an incremental pause, reference discovery will be
 895   // temporarily disabled for _ref_processor_cm and will be
 896   // enabled for _ref_processor_stw. At the end of the evacuation
 897   // pause references discovered by _ref_processor_stw will be
 898   // processed and discovery will be disabled. The previous
 899   // setting for reference object discovery for _ref_processor_cm
 900   // will be re-instated.
 901   //
 902   // At the start of marking:
 903   //  * Discovery by the CM ref processor is verified to be inactive
 904   //    and it's discovered lists are empty.
 905   //  * Discovery by the CM ref processor is then enabled.
 906   //
 907   // At the end of marking:
 908   //  * Any references on the CM ref processor's discovered
 909   //    lists are processed (possibly MT).
 910   //
 911   // At the start of full GC we:
 912   //  * Disable discovery by the CM ref processor and
 913   //    empty CM ref processor's discovered lists
 914   //    (without processing any entries).
 915   //  * Verify that the STW ref processor is inactive and it's
 916   //    discovered lists are empty.
 917   //  * Temporarily set STW ref processor discovery as single threaded.
 918   //  * Temporarily clear the STW ref processor's _is_alive_non_header
 919   //    field.
 920   //  * Finally enable discovery by the STW ref processor.
 921   //
 922   // The STW ref processor is used to record any discovered
 923   // references during the full GC.
 924   //
 925   // At the end of a full GC we:
 926   //  * Enqueue any reference objects discovered by the STW ref processor
 927   //    that have non-live referents. This has the side-effect of
 928   //    making the STW ref processor inactive by disabling discovery.
 929   //  * Verify that the CM ref processor is still inactive
 930   //    and no references have been placed on it's discovered
 931   //    lists (also checked as a precondition during initial marking).
 932 
 933   // The (stw) reference processor...
 934   ReferenceProcessor* _ref_processor_stw;
 935 
 936   // During reference object discovery, the _is_alive_non_header
 937   // closure (if non-null) is applied to the referent object to
 938   // determine whether the referent is live. If so then the
 939   // reference object does not need to be 'discovered' and can
 940   // be treated as a regular oop. This has the benefit of reducing
 941   // the number of 'discovered' reference objects that need to
 942   // be processed.
 943   //
 944   // Instance of the is_alive closure for embedding into the
 945   // STW reference processor as the _is_alive_non_header field.
 946   // Supplying a value for the _is_alive_non_header field is
 947   // optional but doing so prevents unnecessary additions to
 948   // the discovered lists during reference discovery.
 949   G1STWIsAliveClosure _is_alive_closure_stw;
 950 
 951   // The (concurrent marking) reference processor...
 952   ReferenceProcessor* _ref_processor_cm;
 953 
 954   // Instance of the concurrent mark is_alive closure for embedding
 955   // into the Concurrent Marking reference processor as the
 956   // _is_alive_non_header field. Supplying a value for the
 957   // _is_alive_non_header field is optional but doing so prevents
 958   // unnecessary additions to the discovered lists during reference
 959   // discovery.
 960   G1CMIsAliveClosure _is_alive_closure_cm;
 961 
 962   // Cache used by G1CollectedHeap::start_cset_region_for_worker().
 963   HeapRegion** _worker_cset_start_region;
 964 
 965   // Time stamp to validate the regions recorded in the cache
 966   // used by G1CollectedHeap::start_cset_region_for_worker().
 967   // The heap region entry for a given worker is valid iff
 968   // the associated time stamp value matches the current value
 969   // of G1CollectedHeap::_gc_time_stamp.
 970   unsigned int* _worker_cset_start_region_time_stamp;
 971 
 972   enum G1H_process_strong_roots_tasks {
 973     G1H_PS_filter_satb_buffers,
 974     G1H_PS_refProcessor_oops_do,
 975     // Leave this one last.
 976     G1H_PS_NumElements
 977   };
 978 
 979   SubTasksDone* _process_strong_tasks;
 980 
 981   volatile bool _free_regions_coming;
 982 
 983 public:
 984 
 985   SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
 986 
 987   void set_refine_cte_cl_concurrency(bool concurrent);
 988 
 989   RefToScanQueue *task_queue(int i) const;
 990 
 991   // A set of cards where updates happened during the GC
 992   DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
 993 
 994   // A DirtyCardQueueSet that is used to hold cards that contain
 995   // references into the current collection set. This is used to
 996   // update the remembered sets of the regions in the collection
 997   // set in the event of an evacuation failure.
 998   DirtyCardQueueSet& into_cset_dirty_card_queue_set()
 999         { return _into_cset_dirty_card_queue_set; }
1000 
1001   // Create a G1CollectedHeap with the specified policy.
1002   // Must call the initialize method afterwards.
1003   // May not return if something goes wrong.
1004   G1CollectedHeap(G1CollectorPolicy* policy);
1005 
1006   // Initialize the G1CollectedHeap to have the initial and
1007   // maximum sizes, permanent generation, and remembered and barrier sets
1008   // specified by the policy object.
1009   jint initialize();
1010 
1011   // Initialize weak reference processing.
1012   virtual void ref_processing_init();
1013 
1014   void set_par_threads(uint t) {
1015     SharedHeap::set_par_threads(t);
1016     // Done in SharedHeap but oddly there are
1017     // two _process_strong_tasks's in a G1CollectedHeap
1018     // so do it here too.
1019     _process_strong_tasks->set_n_threads(t);
1020   }
1021 
1022   // Set _n_par_threads according to a policy TBD.
1023   void set_par_threads();
1024 
1025   void set_n_termination(int t) {
1026     _process_strong_tasks->set_n_threads(t);
1027   }
1028 
1029   virtual CollectedHeap::Name kind() const {
1030     return CollectedHeap::G1CollectedHeap;
1031   }
1032 
1033   // The current policy object for the collector.
1034   G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1035 
1036   // Adaptive size policy.  No such thing for g1.
1037   virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1038 
1039   // The rem set and barrier set.
1040   G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1041   ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1042 
1043   // The rem set iterator.
1044   HeapRegionRemSetIterator* rem_set_iterator(int i) {
1045     return _rem_set_iterator[i];
1046   }
1047 
1048   HeapRegionRemSetIterator* rem_set_iterator() {
1049     return _rem_set_iterator[0];
1050   }
1051 
1052   unsigned get_gc_time_stamp() {
1053     return _gc_time_stamp;
1054   }
1055 
1056   void reset_gc_time_stamp() {
1057     _gc_time_stamp = 0;
1058     OrderAccess::fence();
1059     // Clear the cached CSet starting regions and time stamps.
1060     // Their validity is dependent on the GC timestamp.
1061     clear_cset_start_regions();
1062   }
1063 
1064   void increment_gc_time_stamp() {
1065     ++_gc_time_stamp;
1066     OrderAccess::fence();
1067   }
1068 
1069   void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1070                                   DirtyCardQueue* into_cset_dcq,
1071                                   bool concurrent, int worker_i);
1072 
1073   // The shared block offset table array.
1074   G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1075 
1076   // Reference Processing accessors
1077 
1078   // The STW reference processor....
1079   ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1080 
1081   // The Concurent Marking reference processor...
1082   ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1083 
1084   virtual size_t capacity() const;
1085   virtual size_t used() const;
1086   // This should be called when we're not holding the heap lock. The
1087   // result might be a bit inaccurate.
1088   size_t used_unlocked() const;
1089   size_t recalculate_used() const;
1090 
1091   // These virtual functions do the actual allocation.
1092   // Some heaps may offer a contiguous region for shared non-blocking
1093   // allocation, via inlined code (by exporting the address of the top and
1094   // end fields defining the extent of the contiguous allocation region.)
1095   // But G1CollectedHeap doesn't yet support this.
1096 
1097   // Return an estimate of the maximum allocation that could be performed
1098   // without triggering any collection or expansion activity.  In a
1099   // generational collector, for example, this is probably the largest
1100   // allocation that could be supported (without expansion) in the youngest
1101   // generation.  It is "unsafe" because no locks are taken; the result
1102   // should be treated as an approximation, not a guarantee, for use in
1103   // heuristic resizing decisions.
1104   virtual size_t unsafe_max_alloc();
1105 
1106   virtual bool is_maximal_no_gc() const {
1107     return _g1_storage.uncommitted_size() == 0;
1108   }
1109 
1110   // The total number of regions in the heap.
1111   uint n_regions() { return _hrs.length(); }
1112 
1113   // The max number of regions in the heap.
1114   uint max_regions() { return _hrs.max_length(); }
1115 
1116   // The number of regions that are completely free.
1117   uint free_regions() { return _free_list.length(); }
1118 
1119   // The number of regions that are not completely free.
1120   uint used_regions() { return n_regions() - free_regions(); }
1121 
1122   // The number of regions available for "regular" expansion.
1123   uint expansion_regions() { return _expansion_regions; }
1124 
1125   // Factory method for HeapRegion instances. It will return NULL if
1126   // the allocation fails.
1127   HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1128 
1129   void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1130   void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1131   void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1132   void verify_dirty_young_regions() PRODUCT_RETURN;
1133 
1134   // verify_region_sets() performs verification over the region
1135   // lists. It will be compiled in the product code to be used when
1136   // necessary (i.e., during heap verification).
1137   void verify_region_sets();
1138 
1139   // verify_region_sets_optional() is planted in the code for
1140   // list verification in non-product builds (and it can be enabled in
1141   // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1142 #if HEAP_REGION_SET_FORCE_VERIFY
1143   void verify_region_sets_optional() {
1144     verify_region_sets();
1145   }
1146 #else // HEAP_REGION_SET_FORCE_VERIFY
1147   void verify_region_sets_optional() { }
1148 #endif // HEAP_REGION_SET_FORCE_VERIFY
1149 
1150 #ifdef ASSERT
1151   bool is_on_master_free_list(HeapRegion* hr) {
1152     return hr->containing_set() == &_free_list;
1153   }
1154 
1155   bool is_in_humongous_set(HeapRegion* hr) {
1156     return hr->containing_set() == &_humongous_set;
1157   }
1158 #endif // ASSERT
1159 
1160   // Wrapper for the region list operations that can be called from
1161   // methods outside this class.
1162 
1163   void secondary_free_list_add_as_tail(FreeRegionList* list) {
1164     _secondary_free_list.add_as_tail(list);
1165   }
1166 
1167   void append_secondary_free_list() {
1168     _free_list.add_as_head(&_secondary_free_list);
1169   }
1170 
1171   void append_secondary_free_list_if_not_empty_with_lock() {
1172     // If the secondary free list looks empty there's no reason to
1173     // take the lock and then try to append it.
1174     if (!_secondary_free_list.is_empty()) {
1175       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1176       append_secondary_free_list();
1177     }
1178   }
1179 
1180   void old_set_remove(HeapRegion* hr) {
1181     _old_set.remove(hr);
1182   }
1183 
1184   size_t non_young_capacity_bytes() {
1185     return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1186   }
1187 
1188   void set_free_regions_coming();
1189   void reset_free_regions_coming();
1190   bool free_regions_coming() { return _free_regions_coming; }
1191   void wait_while_free_regions_coming();
1192 
1193   // Determine whether the given region is one that we are using as an
1194   // old GC alloc region.
1195   bool is_old_gc_alloc_region(HeapRegion* hr) {
1196     return hr == _retained_old_gc_alloc_region;
1197   }
1198 
1199   // Perform a collection of the heap; intended for use in implementing
1200   // "System.gc".  This probably implies as full a collection as the
1201   // "CollectedHeap" supports.
1202   virtual void collect(GCCause::Cause cause);
1203 
1204   // The same as above but assume that the caller holds the Heap_lock.
1205   void collect_locked(GCCause::Cause cause);
1206 
1207   // This interface assumes that it's being called by the
1208   // vm thread. It collects the heap assuming that the
1209   // heap lock is already held and that we are executing in
1210   // the context of the vm thread.
1211   virtual void collect_as_vm_thread(GCCause::Cause cause);
1212 
1213   // True iff a evacuation has failed in the most-recent collection.
1214   bool evacuation_failed() { return _evacuation_failed; }
1215 
1216   // It will free a region if it has allocated objects in it that are
1217   // all dead. It calls either free_region() or
1218   // free_humongous_region() depending on the type of the region that
1219   // is passed to it.
1220   void free_region_if_empty(HeapRegion* hr,
1221                             size_t* pre_used,
1222                             FreeRegionList* free_list,
1223                             OldRegionSet* old_proxy_set,
1224                             HumongousRegionSet* humongous_proxy_set,
1225                             HRRSCleanupTask* hrrs_cleanup_task,
1226                             bool par);
1227 
1228   // It appends the free list to the master free list and updates the
1229   // master humongous list according to the contents of the proxy
1230   // list. It also adjusts the total used bytes according to pre_used
1231   // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1232   void update_sets_after_freeing_regions(size_t pre_used,
1233                                        FreeRegionList* free_list,
1234                                        OldRegionSet* old_proxy_set,
1235                                        HumongousRegionSet* humongous_proxy_set,
1236                                        bool par);
1237 
1238   // Returns "TRUE" iff "p" points into the committed areas of the heap.
1239   virtual bool is_in(const void* p) const;
1240 
1241   // Return "TRUE" iff the given object address is within the collection
1242   // set.
1243   inline bool obj_in_cs(oop obj);
1244 
1245   // Return "TRUE" iff the given object address is in the reserved
1246   // region of g1 (excluding the permanent generation).
1247   bool is_in_g1_reserved(const void* p) const {
1248     return _g1_reserved.contains(p);
1249   }
1250 
1251   // Returns a MemRegion that corresponds to the space that has been
1252   // reserved for the heap
1253   MemRegion g1_reserved() {
1254     return _g1_reserved;
1255   }
1256 
1257   // Returns a MemRegion that corresponds to the space that has been
1258   // committed in the heap
1259   MemRegion g1_committed() {
1260     return _g1_committed;
1261   }
1262 
1263   virtual bool is_in_closed_subset(const void* p) const;
1264 
1265   // This resets the card table to all zeros.  It is used after
1266   // a collection pause which used the card table to claim cards.
1267   void cleanUpCardTable();
1268 
1269   // Iteration functions.
1270 
1271   // Iterate over all the ref-containing fields of all objects, calling
1272   // "cl.do_oop" on each.
1273   virtual void oop_iterate(OopClosure* cl) {
1274     oop_iterate(cl, true);
1275   }
1276   void oop_iterate(OopClosure* cl, bool do_perm);
1277 
1278   // Same as above, restricted to a memory region.
1279   virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1280     oop_iterate(mr, cl, true);
1281   }
1282   void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1283 
1284   // Iterate over all objects, calling "cl.do_object" on each.
1285   virtual void object_iterate(ObjectClosure* cl) {
1286     object_iterate(cl, true);
1287   }
1288   virtual void safe_object_iterate(ObjectClosure* cl) {
1289     object_iterate(cl, true);
1290   }
1291   void object_iterate(ObjectClosure* cl, bool do_perm);
1292 
1293   // Iterate over all objects allocated since the last collection, calling
1294   // "cl.do_object" on each.  The heap must have been initialized properly
1295   // to support this function, or else this call will fail.
1296   virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1297 
1298   // Iterate over all spaces in use in the heap, in ascending address order.
1299   virtual void space_iterate(SpaceClosure* cl);
1300 
1301   // Iterate over heap regions, in address order, terminating the
1302   // iteration early if the "doHeapRegion" method returns "true".
1303   void heap_region_iterate(HeapRegionClosure* blk) const;
1304 
1305   // Iterate over heap regions starting with r (or the first region if "r"
1306   // is NULL), in address order, terminating early if the "doHeapRegion"
1307   // method returns "true".
1308   void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1309 
1310   // Return the region with the given index. It assumes the index is valid.
1311   HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1312 
1313   // Divide the heap region sequence into "chunks" of some size (the number
1314   // of regions divided by the number of parallel threads times some
1315   // overpartition factor, currently 4).  Assumes that this will be called
1316   // in parallel by ParallelGCThreads worker threads with discinct worker
1317   // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1318   // calls will use the same "claim_value", and that that claim value is
1319   // different from the claim_value of any heap region before the start of
1320   // the iteration.  Applies "blk->doHeapRegion" to each of the regions, by
1321   // attempting to claim the first region in each chunk, and, if
1322   // successful, applying the closure to each region in the chunk (and
1323   // setting the claim value of the second and subsequent regions of the
1324   // chunk.)  For now requires that "doHeapRegion" always returns "false",
1325   // i.e., that a closure never attempt to abort a traversal.
1326   void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1327                                        uint worker,
1328                                        uint no_of_par_workers,
1329                                        jint claim_value);
1330 
1331   // It resets all the region claim values to the default.
1332   void reset_heap_region_claim_values();
1333 
1334   // Resets the claim values of regions in the current
1335   // collection set to the default.
1336   void reset_cset_heap_region_claim_values();
1337 
1338 #ifdef ASSERT
1339   bool check_heap_region_claim_values(jint claim_value);
1340 
1341   // Same as the routine above but only checks regions in the
1342   // current collection set.
1343   bool check_cset_heap_region_claim_values(jint claim_value);
1344 #endif // ASSERT
1345 
1346   // Clear the cached cset start regions and (more importantly)
1347   // the time stamps. Called when we reset the GC time stamp.
1348   void clear_cset_start_regions();
1349 
1350   // Given the id of a worker, obtain or calculate a suitable
1351   // starting region for iterating over the current collection set.
1352   HeapRegion* start_cset_region_for_worker(int worker_i);
1353 
1354   // Iterate over the regions (if any) in the current collection set.
1355   void collection_set_iterate(HeapRegionClosure* blk);
1356 
1357   // As above but starting from region r
1358   void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1359 
1360   // Returns the first (lowest address) compactible space in the heap.
1361   virtual CompactibleSpace* first_compactible_space();
1362 
1363   // A CollectedHeap will contain some number of spaces.  This finds the
1364   // space containing a given address, or else returns NULL.
1365   virtual Space* space_containing(const void* addr) const;
1366 
1367   // A G1CollectedHeap will contain some number of heap regions.  This
1368   // finds the region containing a given address, or else returns NULL.
1369   template <class T>
1370   inline HeapRegion* heap_region_containing(const T addr) const;
1371 
1372   // Like the above, but requires "addr" to be in the heap (to avoid a
1373   // null-check), and unlike the above, may return an continuing humongous
1374   // region.
1375   template <class T>
1376   inline HeapRegion* heap_region_containing_raw(const T addr) const;
1377 
1378   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1379   // each address in the (reserved) heap is a member of exactly
1380   // one block.  The defining characteristic of a block is that it is
1381   // possible to find its size, and thus to progress forward to the next
1382   // block.  (Blocks may be of different sizes.)  Thus, blocks may
1383   // represent Java objects, or they might be free blocks in a
1384   // free-list-based heap (or subheap), as long as the two kinds are
1385   // distinguishable and the size of each is determinable.
1386 
1387   // Returns the address of the start of the "block" that contains the
1388   // address "addr".  We say "blocks" instead of "object" since some heaps
1389   // may not pack objects densely; a chunk may either be an object or a
1390   // non-object.
1391   virtual HeapWord* block_start(const void* addr) const;
1392 
1393   // Requires "addr" to be the start of a chunk, and returns its size.
1394   // "addr + size" is required to be the start of a new chunk, or the end
1395   // of the active area of the heap.
1396   virtual size_t block_size(const HeapWord* addr) const;
1397 
1398   // Requires "addr" to be the start of a block, and returns "TRUE" iff
1399   // the block is an object.
1400   virtual bool block_is_obj(const HeapWord* addr) const;
1401 
1402   // Does this heap support heap inspection? (+PrintClassHistogram)
1403   virtual bool supports_heap_inspection() const { return true; }
1404 
1405   // Section on thread-local allocation buffers (TLABs)
1406   // See CollectedHeap for semantics.
1407 
1408   virtual bool supports_tlab_allocation() const;
1409   virtual size_t tlab_capacity(Thread* thr) const;
1410   virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1411 
1412   // Can a compiler initialize a new object without store barriers?
1413   // This permission only extends from the creation of a new object
1414   // via a TLAB up to the first subsequent safepoint. If such permission
1415   // is granted for this heap type, the compiler promises to call
1416   // defer_store_barrier() below on any slow path allocation of
1417   // a new object for which such initializing store barriers will
1418   // have been elided. G1, like CMS, allows this, but should be
1419   // ready to provide a compensating write barrier as necessary
1420   // if that storage came out of a non-young region. The efficiency
1421   // of this implementation depends crucially on being able to
1422   // answer very efficiently in constant time whether a piece of
1423   // storage in the heap comes from a young region or not.
1424   // See ReduceInitialCardMarks.
1425   virtual bool can_elide_tlab_store_barriers() const {
1426     return true;
1427   }
1428 
1429   virtual bool card_mark_must_follow_store() const {
1430     return true;
1431   }
1432 
1433   bool is_in_young(const oop obj) {
1434     HeapRegion* hr = heap_region_containing(obj);
1435     return hr != NULL && hr->is_young();
1436   }
1437 
1438 #ifdef ASSERT
1439   virtual bool is_in_partial_collection(const void* p);
1440 #endif
1441 
1442   virtual bool is_scavengable(const void* addr);
1443 
1444   // We don't need barriers for initializing stores to objects
1445   // in the young gen: for the SATB pre-barrier, there is no
1446   // pre-value that needs to be remembered; for the remembered-set
1447   // update logging post-barrier, we don't maintain remembered set
1448   // information for young gen objects.
1449   virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1450     return is_in_young(new_obj);
1451   }
1452 
1453   // Can a compiler elide a store barrier when it writes
1454   // a permanent oop into the heap?  Applies when the compiler
1455   // is storing x to the heap, where x->is_perm() is true.
1456   virtual bool can_elide_permanent_oop_store_barriers() const {
1457     // At least until perm gen collection is also G1-ified, at
1458     // which point this should return false.
1459     return true;
1460   }
1461 
1462   // Returns "true" iff the given word_size is "very large".
1463   static bool isHumongous(size_t word_size) {
1464     // Note this has to be strictly greater-than as the TLABs
1465     // are capped at the humongous thresold and we want to
1466     // ensure that we don't try to allocate a TLAB as
1467     // humongous and that we don't allocate a humongous
1468     // object in a TLAB.
1469     return word_size > _humongous_object_threshold_in_words;
1470   }
1471 
1472   // Update mod union table with the set of dirty cards.
1473   void updateModUnion();
1474 
1475   // Set the mod union bits corresponding to the given memRegion.  Note
1476   // that this is always a safe operation, since it doesn't clear any
1477   // bits.
1478   void markModUnionRange(MemRegion mr);
1479 
1480   // Records the fact that a marking phase is no longer in progress.
1481   void set_marking_complete() {
1482     _mark_in_progress = false;
1483   }
1484   void set_marking_started() {
1485     _mark_in_progress = true;
1486   }
1487   bool mark_in_progress() {
1488     return _mark_in_progress;
1489   }
1490 
1491   // Print the maximum heap capacity.
1492   virtual size_t max_capacity() const;
1493 
1494   virtual jlong millis_since_last_gc();
1495 
1496   // Perform any cleanup actions necessary before allowing a verification.
1497   virtual void prepare_for_verify();
1498 
1499   // Perform verification.
1500 
1501   // vo == UsePrevMarking  -> use "prev" marking information,
1502   // vo == UseNextMarking -> use "next" marking information
1503   // vo == UseMarkWord    -> use the mark word in the object header
1504   //
1505   // NOTE: Only the "prev" marking information is guaranteed to be
1506   // consistent most of the time, so most calls to this should use
1507   // vo == UsePrevMarking.
1508   // Currently, there is only one case where this is called with
1509   // vo == UseNextMarking, which is to verify the "next" marking
1510   // information at the end of remark.
1511   // Currently there is only one place where this is called with
1512   // vo == UseMarkWord, which is to verify the marking during a
1513   // full GC.
1514   void verify(bool silent, VerifyOption vo);
1515 
1516   // Override; it uses the "prev" marking information
1517   virtual void verify(bool silent);
1518   virtual void print_on(outputStream* st) const;
1519   virtual void print_extended_on(outputStream* st) const;
1520 
1521   virtual void print_gc_threads_on(outputStream* st) const;
1522   virtual void gc_threads_do(ThreadClosure* tc) const;
1523 
1524   // Override
1525   void print_tracing_info() const;
1526 
1527   // The following two methods are helpful for debugging RSet issues.
1528   void print_cset_rsets() PRODUCT_RETURN;
1529   void print_all_rsets() PRODUCT_RETURN;
1530 
1531   // Convenience function to be used in situations where the heap type can be
1532   // asserted to be this type.
1533   static G1CollectedHeap* heap();
1534 
1535   void set_region_short_lived_locked(HeapRegion* hr);
1536   // add appropriate methods for any other surv rate groups
1537 
1538   YoungList* young_list() { return _young_list; }
1539 
1540   // debugging
1541   bool check_young_list_well_formed() {
1542     return _young_list->check_list_well_formed();
1543   }
1544 
1545   bool check_young_list_empty(bool check_heap,
1546                               bool check_sample = true);
1547 
1548   // *** Stuff related to concurrent marking.  It's not clear to me that so
1549   // many of these need to be public.
1550 
1551   // The functions below are helper functions that a subclass of
1552   // "CollectedHeap" can use in the implementation of its virtual
1553   // functions.
1554   // This performs a concurrent marking of the live objects in a
1555   // bitmap off to the side.
1556   void doConcurrentMark();
1557 
1558   bool isMarkedPrev(oop obj) const;
1559   bool isMarkedNext(oop obj) const;
1560 
1561   // vo == UsePrevMarking -> use "prev" marking information,
1562   // vo == UseNextMarking -> use "next" marking information,
1563   // vo == UseMarkWord    -> use mark word from object header
1564   bool is_obj_dead_cond(const oop obj,
1565                         const HeapRegion* hr,
1566                         const VerifyOption vo) const {
1567 
1568     switch (vo) {
1569       case VerifyOption_G1UsePrevMarking:
1570         return is_obj_dead(obj, hr);
1571       case VerifyOption_G1UseNextMarking:
1572         return is_obj_ill(obj, hr);
1573       default:
1574         assert(vo == VerifyOption_G1UseMarkWord, "must be");
1575         return !obj->is_gc_marked();
1576     }
1577   }
1578 
1579   // Determine if an object is dead, given the object and also
1580   // the region to which the object belongs. An object is dead
1581   // iff a) it was not allocated since the last mark and b) it
1582   // is not marked.
1583 
1584   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1585     return
1586       !hr->obj_allocated_since_prev_marking(obj) &&
1587       !isMarkedPrev(obj);
1588   }
1589 
1590   // This is used when copying an object to survivor space.
1591   // If the object is marked live, then we mark the copy live.
1592   // If the object is allocated since the start of this mark
1593   // cycle, then we mark the copy live.
1594   // If the object has been around since the previous mark
1595   // phase, and hasn't been marked yet during this phase,
1596   // then we don't mark it, we just wait for the
1597   // current marking cycle to get to it.
1598 
1599   // This function returns true when an object has been
1600   // around since the previous marking and hasn't yet
1601   // been marked during this marking.
1602 
1603   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1604     return
1605       !hr->obj_allocated_since_next_marking(obj) &&
1606       !isMarkedNext(obj);
1607   }
1608 
1609   // Determine if an object is dead, given only the object itself.
1610   // This will find the region to which the object belongs and
1611   // then call the region version of the same function.
1612 
1613   // Added if it is in permanent gen it isn't dead.
1614   // Added if it is NULL it isn't dead.
1615 
1616   // vo == UsePrevMarking -> use "prev" marking information,
1617   // vo == UseNextMarking -> use "next" marking information,
1618   // vo == UseMarkWord    -> use mark word from object header
1619   bool is_obj_dead_cond(const oop obj,
1620                         const VerifyOption vo) const {
1621 
1622     switch (vo) {
1623       case VerifyOption_G1UsePrevMarking:
1624         return is_obj_dead(obj);
1625       case VerifyOption_G1UseNextMarking:
1626         return is_obj_ill(obj);
1627       default:
1628         assert(vo == VerifyOption_G1UseMarkWord, "must be");
1629         return !obj->is_gc_marked();
1630     }
1631   }
1632 
1633   bool is_obj_dead(const oop obj) const {
1634     const HeapRegion* hr = heap_region_containing(obj);
1635     if (hr == NULL) {
1636       if (Universe::heap()->is_in_permanent(obj))
1637         return false;
1638       else if (obj == NULL) return false;
1639       else return true;
1640     }
1641     else return is_obj_dead(obj, hr);
1642   }
1643 
1644   bool is_obj_ill(const oop obj) const {
1645     const HeapRegion* hr = heap_region_containing(obj);
1646     if (hr == NULL) {
1647       if (Universe::heap()->is_in_permanent(obj))
1648         return false;
1649       else if (obj == NULL) return false;
1650       else return true;
1651     }
1652     else return is_obj_ill(obj, hr);
1653   }
1654 
1655   // The following is just to alert the verification code
1656   // that a full collection has occurred and that the
1657   // remembered sets are no longer up to date.
1658   bool _full_collection;
1659   void set_full_collection() { _full_collection = true;}
1660   void clear_full_collection() {_full_collection = false;}
1661   bool full_collection() {return _full_collection;}
1662 
1663   ConcurrentMark* concurrent_mark() const { return _cm; }
1664   ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1665 
1666   // The dirty cards region list is used to record a subset of regions
1667   // whose cards need clearing. The list if populated during the
1668   // remembered set scanning and drained during the card table
1669   // cleanup. Although the methods are reentrant, population/draining
1670   // phases must not overlap. For synchronization purposes the last
1671   // element on the list points to itself.
1672   HeapRegion* _dirty_cards_region_list;
1673   void push_dirty_cards_region(HeapRegion* hr);
1674   HeapRegion* pop_dirty_cards_region();
1675 
1676 public:
1677   void stop_conc_gc_threads();
1678 
1679   size_t pending_card_num();
1680   size_t max_pending_card_num();
1681   size_t cards_scanned();
1682 
1683 protected:
1684   size_t _max_heap_capacity;
1685 };
1686 
1687 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1688 private:
1689   bool        _retired;
1690 
1691 public:
1692   G1ParGCAllocBuffer(size_t gclab_word_size);
1693 
1694   void set_buf(HeapWord* buf) {
1695     ParGCAllocBuffer::set_buf(buf);
1696     _retired = false;
1697   }
1698 
1699   void retire(bool end_of_gc, bool retain) {
1700     if (_retired)
1701       return;
1702     ParGCAllocBuffer::retire(end_of_gc, retain);
1703     _retired = true;
1704   }
1705 };
1706 
1707 class G1ParScanThreadState : public StackObj {
1708 protected:
1709   G1CollectedHeap* _g1h;
1710   RefToScanQueue*  _refs;
1711   DirtyCardQueue   _dcq;
1712   CardTableModRefBS* _ct_bs;
1713   G1RemSet* _g1_rem;
1714 
1715   G1ParGCAllocBuffer  _surviving_alloc_buffer;
1716   G1ParGCAllocBuffer  _tenured_alloc_buffer;
1717   G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1718   ageTable            _age_table;
1719 
1720   size_t           _alloc_buffer_waste;
1721   size_t           _undo_waste;
1722 
1723   OopsInHeapRegionClosure*      _evac_failure_cl;
1724   G1ParScanHeapEvacClosure*     _evac_cl;
1725   G1ParScanPartialArrayClosure* _partial_scan_cl;
1726 
1727   int _hash_seed;
1728   uint _queue_num;
1729 
1730   size_t _term_attempts;
1731 
1732   double _start;
1733   double _start_strong_roots;
1734   double _strong_roots_time;
1735   double _start_term;
1736   double _term_time;
1737 
1738   // Map from young-age-index (0 == not young, 1 is youngest) to
1739   // surviving words. base is what we get back from the malloc call
1740   size_t* _surviving_young_words_base;
1741   // this points into the array, as we use the first few entries for padding
1742   size_t* _surviving_young_words;
1743 
1744 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1745 
1746   void   add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1747 
1748   void   add_to_undo_waste(size_t waste)         { _undo_waste += waste; }
1749 
1750   DirtyCardQueue& dirty_card_queue()             { return _dcq;  }
1751   CardTableModRefBS* ctbs()                      { return _ct_bs; }
1752 
1753   template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1754     if (!from->is_survivor()) {
1755       _g1_rem->par_write_ref(from, p, tid);
1756     }
1757   }
1758 
1759   template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1760     // If the new value of the field points to the same region or
1761     // is the to-space, we don't need to include it in the Rset updates.
1762     if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1763       size_t card_index = ctbs()->index_for(p);
1764       // If the card hasn't been added to the buffer, do it.
1765       if (ctbs()->mark_card_deferred(card_index)) {
1766         dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1767       }
1768     }
1769   }
1770 
1771 public:
1772   G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1773 
1774   ~G1ParScanThreadState() {
1775     FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1776   }
1777 
1778   RefToScanQueue*   refs()            { return _refs;             }
1779   ageTable*         age_table()       { return &_age_table;       }
1780 
1781   G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1782     return _alloc_buffers[purpose];
1783   }
1784 
1785   size_t alloc_buffer_waste() const              { return _alloc_buffer_waste; }
1786   size_t undo_waste() const                      { return _undo_waste; }
1787 
1788 #ifdef ASSERT
1789   bool verify_ref(narrowOop* ref) const;
1790   bool verify_ref(oop* ref) const;
1791   bool verify_task(StarTask ref) const;
1792 #endif // ASSERT
1793 
1794   template <class T> void push_on_queue(T* ref) {
1795     assert(verify_ref(ref), "sanity");
1796     refs()->push(ref);
1797   }
1798 
1799   template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1800     if (G1DeferredRSUpdate) {
1801       deferred_rs_update(from, p, tid);
1802     } else {
1803       immediate_rs_update(from, p, tid);
1804     }
1805   }
1806 
1807   HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1808 
1809     HeapWord* obj = NULL;
1810     size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1811     if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1812       G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1813       assert(gclab_word_size == alloc_buf->word_sz(),
1814              "dynamic resizing is not supported");
1815       add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1816       alloc_buf->retire(false, false);
1817 
1818       HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1819       if (buf == NULL) return NULL; // Let caller handle allocation failure.
1820       // Otherwise.
1821       alloc_buf->set_buf(buf);
1822 
1823       obj = alloc_buf->allocate(word_sz);
1824       assert(obj != NULL, "buffer was definitely big enough...");
1825     } else {
1826       obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1827     }
1828     return obj;
1829   }
1830 
1831   HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1832     HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1833     if (obj != NULL) return obj;
1834     return allocate_slow(purpose, word_sz);
1835   }
1836 
1837   void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1838     if (alloc_buffer(purpose)->contains(obj)) {
1839       assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1840              "should contain whole object");
1841       alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1842     } else {
1843       CollectedHeap::fill_with_object(obj, word_sz);
1844       add_to_undo_waste(word_sz);
1845     }
1846   }
1847 
1848   void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1849     _evac_failure_cl = evac_failure_cl;
1850   }
1851   OopsInHeapRegionClosure* evac_failure_closure() {
1852     return _evac_failure_cl;
1853   }
1854 
1855   void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1856     _evac_cl = evac_cl;
1857   }
1858 
1859   void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1860     _partial_scan_cl = partial_scan_cl;
1861   }
1862 
1863   int* hash_seed() { return &_hash_seed; }
1864   uint queue_num() { return _queue_num; }
1865 
1866   size_t term_attempts() const  { return _term_attempts; }
1867   void note_term_attempt() { _term_attempts++; }
1868 
1869   void start_strong_roots() {
1870     _start_strong_roots = os::elapsedTime();
1871   }
1872   void end_strong_roots() {
1873     _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1874   }
1875   double strong_roots_time() const { return _strong_roots_time; }
1876 
1877   void start_term_time() {
1878     note_term_attempt();
1879     _start_term = os::elapsedTime();
1880   }
1881   void end_term_time() {
1882     _term_time += (os::elapsedTime() - _start_term);
1883   }
1884   double term_time() const { return _term_time; }
1885 
1886   double elapsed_time() const {
1887     return os::elapsedTime() - _start;
1888   }
1889 
1890   static void
1891     print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1892   void
1893     print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1894 
1895   size_t* surviving_young_words() {
1896     // We add on to hide entry 0 which accumulates surviving words for
1897     // age -1 regions (i.e. non-young ones)
1898     return _surviving_young_words;
1899   }
1900 
1901   void retire_alloc_buffers() {
1902     for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1903       size_t waste = _alloc_buffers[ap]->words_remaining();
1904       add_to_alloc_buffer_waste(waste);
1905       _alloc_buffers[ap]->retire(true, false);
1906     }
1907   }
1908 
1909   template <class T> void deal_with_reference(T* ref_to_scan) {
1910     if (has_partial_array_mask(ref_to_scan)) {
1911       _partial_scan_cl->do_oop_nv(ref_to_scan);
1912     } else {
1913       // Note: we can use "raw" versions of "region_containing" because
1914       // "obj_to_scan" is definitely in the heap, and is not in a
1915       // humongous region.
1916       HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1917       _evac_cl->set_region(r);
1918       _evac_cl->do_oop_nv(ref_to_scan);
1919     }
1920   }
1921 
1922   void deal_with_reference(StarTask ref) {
1923     assert(verify_task(ref), "sanity");
1924     if (ref.is_narrow()) {
1925       deal_with_reference((narrowOop*)ref);
1926     } else {
1927       deal_with_reference((oop*)ref);
1928     }
1929   }
1930 
1931 public:
1932   void trim_queue();
1933 };
1934 
1935 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP