1 /*
   2  * Copyright (c) 2013, 2018, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
  25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
  26 
  27 #include "gc/shared/markBitMap.hpp"
  28 #include "gc/shared/softRefPolicy.hpp"
  29 #include "gc/shared/collectedHeap.hpp"
  30 #include "gc/shenandoah/shenandoahAsserts.hpp"
  31 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
  32 #include "gc/shenandoah/shenandoahLock.hpp"
  33 #include "gc/shenandoah/shenandoahEvacOOMHandler.hpp"
  34 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
  35 #include "services/memoryManager.hpp"
  36 
  37 class ConcurrentGCTimer;
  38 class ReferenceProcessor;
  39 class ShenandoahAllocTracker;
  40 class ShenandoahCollectorPolicy;
  41 class ShenandoahControlThread;
  42 class ShenandoahGCSession;
  43 class ShenandoahGCStateResetter;
  44 class ShenandoahHeuristics;
  45 class ShenandoahMarkingContext;
  46 class ShenandoahMode;
  47 class ShenandoahPhaseTimings;
  48 class ShenandoahHeap;
  49 class ShenandoahHeapRegion;
  50 class ShenandoahHeapRegionClosure;
  51 class ShenandoahCollectionSet;
  52 class ShenandoahFreeSet;
  53 class ShenandoahConcurrentMark;
  54 class ShenandoahMarkCompact;
  55 class ShenandoahMonitoringSupport;
  56 class ShenandoahPacer;
  57 class ShenandoahTraversalGC;
  58 class ShenandoahVerifier;
  59 class ShenandoahWorkGang;
  60 class VMStructs;
  61 
  62 class ShenandoahRegionIterator : public StackObj {
  63 private:
  64   ShenandoahHeap* _heap;
  65 
  66   DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
  67   volatile size_t _index;
  68   DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
  69 
  70   // No implicit copying: iterators should be passed by reference to capture the state
  71   ShenandoahRegionIterator(const ShenandoahRegionIterator& that);
  72   ShenandoahRegionIterator& operator=(const ShenandoahRegionIterator& o);
  73 
  74 public:
  75   ShenandoahRegionIterator();
  76   ShenandoahRegionIterator(ShenandoahHeap* heap);
  77 
  78   // Reset iterator to default state
  79   void reset();
  80 
  81   // Returns next region, or NULL if there are no more regions.
  82   // This is multi-thread-safe.
  83   inline ShenandoahHeapRegion* next();
  84 
  85   // This is *not* MT safe. However, in the absence of multithreaded access, it
  86   // can be used to determine if there is more work to do.
  87   bool has_next() const;
  88 };
  89 
  90 class ShenandoahHeapRegionClosure : public StackObj {
  91 public:
  92   virtual void heap_region_do(ShenandoahHeapRegion* r) = 0;
  93   virtual bool is_thread_safe() { return false; }
  94 };
  95 
  96 #ifdef ASSERT
  97 class ShenandoahAssertToSpaceClosure : public OopClosure {
  98 private:
  99   template <class T>
 100   void do_oop_work(T* p);
 101 public:
 102   void do_oop(narrowOop* p);
 103   void do_oop(oop* p);
 104 };
 105 #endif
 106 
 107 typedef ShenandoahLock    ShenandoahHeapLock;
 108 typedef ShenandoahLocker  ShenandoahHeapLocker;
 109 
 110 // Shenandoah GC is low-pause concurrent GC that uses Brooks forwarding pointers
 111 // to encode forwarding data. See BrooksPointer for details on forwarding data encoding.
 112 // See ShenandoahControlThread for GC cycle structure.
 113 //
 114 class ShenandoahHeap : public CollectedHeap {
 115   friend class ShenandoahAsserts;
 116   friend class VMStructs;
 117   friend class ShenandoahGCSession;
 118   friend class ShenandoahGCStateResetter;
 119 
 120 // ---------- Locks that guard important data structures in Heap
 121 //
 122 private:
 123   ShenandoahHeapLock _lock;
 124 
 125 public:
 126   ShenandoahHeapLock* lock() {
 127     return &_lock;
 128   }
 129 
 130   void assert_heaplock_owned_by_current_thread()     NOT_DEBUG_RETURN;
 131   void assert_heaplock_not_owned_by_current_thread() NOT_DEBUG_RETURN;
 132   void assert_heaplock_or_safepoint()                NOT_DEBUG_RETURN;
 133 
 134 // ---------- Initialization, termination, identification, printing routines
 135 //
 136 public:
 137   static ShenandoahHeap* heap();
 138   static ShenandoahHeap* heap_no_check();
 139 
 140   const char* name()          const { return "Shenandoah"; }
 141   ShenandoahHeap::Name kind() const { return CollectedHeap::Shenandoah; }
 142 
 143   ShenandoahHeap(ShenandoahCollectorPolicy* policy);
 144   jint initialize();
 145   void post_initialize();
 146   void initialize_heuristics();
 147 
 148   void initialize_serviceability();
 149 
 150   void print_on(outputStream* st)              const;
 151   void print_extended_on(outputStream *st)     const;
 152   void print_tracing_info()                    const;
 153   void print_gc_threads_on(outputStream* st)   const;
 154   void print_heap_regions_on(outputStream* st) const;
 155 
 156   void stop();
 157 
 158   void prepare_for_verify();
 159   void verify(VerifyOption vo);
 160 
 161 // ---------- Heap counters and metrics
 162 //
 163 private:
 164            size_t _initial_size;
 165            size_t _minimum_size;
 166   DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
 167   volatile size_t _used;
 168   volatile size_t _committed;
 169   volatile size_t _bytes_allocated_since_gc_start;
 170   DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
 171 
 172 public:
 173   void increase_used(size_t bytes);
 174   void decrease_used(size_t bytes);
 175   void set_used(size_t bytes);
 176 
 177   void increase_committed(size_t bytes);
 178   void decrease_committed(size_t bytes);
 179   void increase_allocated(size_t bytes);
 180 
 181   size_t bytes_allocated_since_gc_start();
 182   void reset_bytes_allocated_since_gc_start();
 183 
 184   size_t min_capacity()     const;
 185   size_t max_capacity()     const;
 186   size_t initial_capacity() const;
 187   size_t capacity()         const;
 188   size_t used()             const;
 189   size_t committed()        const;
 190 
 191 // ---------- Workers handling
 192 //
 193 private:
 194   uint _max_workers;
 195   ShenandoahWorkGang* _workers;
 196   ShenandoahWorkGang* _safepoint_workers;
 197 
 198 public:
 199   uint max_workers();
 200   void assert_gc_workers(uint nworker) NOT_DEBUG_RETURN;
 201 
 202   WorkGang* workers() const;
 203   WorkGang* get_safepoint_workers();
 204 
 205   void gc_threads_do(ThreadClosure* tcl) const;
 206 
 207 // ---------- Heap regions handling machinery
 208 //
 209 private:
 210   MemRegion _heap_region;
 211   bool      _heap_region_special;
 212   size_t    _num_regions;
 213   ShenandoahHeapRegion** _regions;
 214   ShenandoahRegionIterator _update_refs_iterator;
 215 
 216 public:
 217   inline size_t num_regions() const { return _num_regions; }
 218   inline bool is_heap_region_special() { return _heap_region_special; }
 219 
 220   inline ShenandoahHeapRegion* const heap_region_containing(const void* addr) const;
 221   inline size_t heap_region_index_containing(const void* addr) const;
 222 
 223   inline ShenandoahHeapRegion* const get_region(size_t region_idx) const;
 224 
 225   void heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
 226   void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
 227 
 228 // ---------- GC state machinery
 229 //
 230 // GC state describes the important parts of collector state, that may be
 231 // used to make barrier selection decisions in the native and generated code.
 232 // Multiple bits can be set at once.
 233 //
 234 // Important invariant: when GC state is zero, the heap is stable, and no barriers
 235 // are required.
 236 //
 237 public:
 238   enum GCStateBitPos {
 239     // Heap has forwarded objects: needs LRB barriers.
 240     HAS_FORWARDED_BITPOS   = 0,
 241 
 242     // Heap is under marking: needs SATB barriers.
 243     MARKING_BITPOS    = 1,
 244 
 245     // Heap is under evacuation: needs LRB barriers. (Set together with HAS_FORWARDED)
 246     EVACUATION_BITPOS = 2,
 247 
 248     // Heap is under updating: needs no additional barriers.
 249     UPDATEREFS_BITPOS = 3,
 250 
 251     // Heap is under traversal collection
 252     TRAVERSAL_BITPOS  = 4
 253   };
 254 
 255   enum GCState {
 256     STABLE        = 0,
 257     HAS_FORWARDED = 1 << HAS_FORWARDED_BITPOS,
 258     MARKING       = 1 << MARKING_BITPOS,
 259     EVACUATION    = 1 << EVACUATION_BITPOS,
 260     UPDATEREFS    = 1 << UPDATEREFS_BITPOS,
 261     TRAVERSAL     = 1 << TRAVERSAL_BITPOS
 262   };
 263 
 264 private:
 265   ShenandoahSharedBitmap _gc_state;
 266   ShenandoahSharedFlag   _degenerated_gc_in_progress;
 267   ShenandoahSharedFlag   _full_gc_in_progress;
 268   ShenandoahSharedFlag   _full_gc_move_in_progress;
 269   ShenandoahSharedFlag   _progress_last_gc;
 270 
 271   void set_gc_state_all_threads(char state);
 272   void set_gc_state_mask(uint mask, bool value);
 273 
 274 public:
 275   char gc_state() const;
 276   static address gc_state_addr();
 277 
 278   void set_concurrent_mark_in_progress(bool in_progress);
 279   void set_evacuation_in_progress(bool in_progress);
 280   void set_update_refs_in_progress(bool in_progress);
 281   void set_degenerated_gc_in_progress(bool in_progress);
 282   void set_full_gc_in_progress(bool in_progress);
 283   void set_full_gc_move_in_progress(bool in_progress);
 284   void set_concurrent_traversal_in_progress(bool in_progress);
 285   void set_has_forwarded_objects(bool cond);
 286 
 287   inline bool is_stable() const;
 288   inline bool is_idle() const;
 289   inline bool is_concurrent_mark_in_progress() const;
 290   inline bool is_update_refs_in_progress() const;
 291   inline bool is_evacuation_in_progress() const;
 292   inline bool is_degenerated_gc_in_progress() const;
 293   inline bool is_full_gc_in_progress() const;
 294   inline bool is_full_gc_move_in_progress() const;
 295   inline bool is_concurrent_traversal_in_progress() const;
 296   inline bool has_forwarded_objects() const;
 297   inline bool is_gc_in_progress_mask(uint mask) const;
 298 
 299 // ---------- GC cancellation and degeneration machinery
 300 //
 301 // Cancelled GC flag is used to notify concurrent phases that they should terminate.
 302 //
 303 public:
 304   enum ShenandoahDegenPoint {
 305     _degenerated_unset,
 306     _degenerated_traversal,
 307     _degenerated_outside_cycle,
 308     _degenerated_mark,
 309     _degenerated_evac,
 310     _degenerated_updaterefs,
 311     _DEGENERATED_LIMIT
 312   };
 313 
 314   static const char* degen_point_to_string(ShenandoahDegenPoint point) {
 315     switch (point) {
 316       case _degenerated_unset:
 317         return "<UNSET>";
 318       case _degenerated_traversal:
 319         return "Traversal";
 320       case _degenerated_outside_cycle:
 321         return "Outside of Cycle";
 322       case _degenerated_mark:
 323         return "Mark";
 324       case _degenerated_evac:
 325         return "Evacuation";
 326       case _degenerated_updaterefs:
 327         return "Update Refs";
 328       default:
 329         ShouldNotReachHere();
 330         return "ERROR";
 331     }
 332   };
 333 
 334 private:
 335   enum CancelState {
 336     // Normal state. GC has not been cancelled and is open for cancellation.
 337     // Worker threads can suspend for safepoint.
 338     CANCELLABLE,
 339 
 340     // GC has been cancelled. Worker threads can not suspend for
 341     // safepoint but must finish their work as soon as possible.
 342     CANCELLED,
 343 
 344     // GC has not been cancelled and must not be cancelled. At least
 345     // one worker thread checks for pending safepoint and may suspend
 346     // if a safepoint is pending.
 347     NOT_CANCELLED
 348   };
 349 
 350   ShenandoahSharedEnumFlag<CancelState> _cancelled_gc;
 351   inline bool try_cancel_gc();
 352 
 353 public:
 354   static address cancelled_gc_addr();
 355 
 356   inline bool cancelled_gc() const;
 357   inline bool check_cancelled_gc_and_yield(bool sts_active = true);
 358 
 359   inline void clear_cancelled_gc();
 360 
 361   void cancel_gc(GCCause::Cause cause);
 362 
 363 // ---------- GC operations entry points
 364 //
 365 public:
 366   // Entry points to STW GC operations, these cause a related safepoint, that then
 367   // call the entry method below
 368   void vmop_entry_init_mark();
 369   void vmop_entry_final_mark();
 370   void vmop_entry_final_evac();
 371   void vmop_entry_init_updaterefs();
 372   void vmop_entry_final_updaterefs();
 373   void vmop_entry_init_traversal();
 374   void vmop_entry_final_traversal();
 375   void vmop_entry_full(GCCause::Cause cause);
 376   void vmop_degenerated(ShenandoahDegenPoint point);
 377 
 378   // Entry methods to normally STW GC operations. These set up logging, monitoring
 379   // and workers for net VM operation
 380   void entry_init_mark();
 381   void entry_final_mark();
 382   void entry_final_evac();
 383   void entry_init_updaterefs();
 384   void entry_final_updaterefs();
 385   void entry_init_traversal();
 386   void entry_final_traversal();
 387   void entry_full(GCCause::Cause cause);
 388   void entry_degenerated(int point);
 389 
 390   // Entry methods to normally concurrent GC operations. These set up logging, monitoring
 391   // for concurrent operation.
 392   void entry_reset();
 393   void entry_mark();
 394   void entry_preclean();
 395   void entry_cleanup();
 396   void entry_evac();
 397   void entry_updaterefs();
 398   void entry_traversal();
 399   void entry_uncommit(double shrink_before);
 400 
 401 private:
 402   // Actual work for the phases
 403   void op_init_mark();
 404   void op_final_mark();
 405   void op_final_evac();
 406   void op_init_updaterefs();
 407   void op_final_updaterefs();
 408   void op_init_traversal();
 409   void op_final_traversal();
 410   void op_full(GCCause::Cause cause);
 411   void op_degenerated(ShenandoahDegenPoint point);
 412   void op_degenerated_fail();
 413   void op_degenerated_futile();
 414 
 415   void op_reset();
 416   void op_mark();
 417   void op_preclean();
 418   void op_cleanup();
 419   void op_conc_evac();
 420   void op_stw_evac();
 421   void op_updaterefs();
 422   void op_traversal();
 423   void op_uncommit(double shrink_before);
 424 
 425   // Messages for GC trace events, they have to be immortal for
 426   // passing around the logging/tracing systems
 427   const char* init_mark_event_message() const;
 428   const char* final_mark_event_message() const;
 429   const char* conc_mark_event_message() const;
 430   const char* degen_event_message(ShenandoahDegenPoint point) const;
 431 
 432 // ---------- GC subsystems
 433 //
 434 private:
 435   ShenandoahControlThread*   _control_thread;
 436   ShenandoahCollectorPolicy* _shenandoah_policy;
 437   ShenandoahMode*            _gc_mode;
 438   ShenandoahHeuristics*      _heuristics;
 439   ShenandoahFreeSet*         _free_set;
 440   ShenandoahConcurrentMark*  _scm;
 441   ShenandoahTraversalGC*     _traversal_gc;
 442   ShenandoahMarkCompact*     _full_gc;
 443   ShenandoahPacer*           _pacer;
 444   ShenandoahVerifier*        _verifier;
 445 
 446   ShenandoahAllocTracker*    _alloc_tracker;
 447   ShenandoahPhaseTimings*    _phase_timings;
 448 
 449   ShenandoahControlThread*   control_thread()          { return _control_thread;    }
 450   ShenandoahMarkCompact*     full_gc()                 { return _full_gc;           }
 451 
 452 public:
 453   ShenandoahCollectorPolicy* shenandoah_policy() const { return _shenandoah_policy; }
 454   ShenandoahHeuristics*      heuristics()        const { return _heuristics;        }
 455   ShenandoahFreeSet*         free_set()          const { return _free_set;          }
 456   ShenandoahConcurrentMark*  concurrent_mark()         { return _scm;               }
 457   ShenandoahTraversalGC*     traversal_gc()      const { return _traversal_gc;      }
 458   bool                       is_traversal_mode() const { return _traversal_gc != NULL; }
 459   ShenandoahPacer*           pacer()             const { return _pacer;             }
 460 
 461   ShenandoahPhaseTimings*    phase_timings()     const { return _phase_timings;     }
 462   ShenandoahAllocTracker*    alloc_tracker()     const { return _alloc_tracker;     }
 463 
 464   ShenandoahVerifier*        verifier();
 465 
 466 // ---------- VM subsystem bindings
 467 //
 468 private:
 469   ShenandoahMonitoringSupport* _monitoring_support;
 470   MemoryPool*                  _memory_pool;
 471   GCMemoryManager              _stw_memory_manager;
 472   GCMemoryManager              _cycle_memory_manager;
 473   ConcurrentGCTimer*           _gc_timer;
 474   SoftRefPolicy                _soft_ref_policy;
 475 
 476 public:
 477   ShenandoahMonitoringSupport* monitoring_support() { return _monitoring_support;    }
 478   GCMemoryManager* cycle_memory_manager()           { return &_cycle_memory_manager; }
 479   GCMemoryManager* stw_memory_manager()             { return &_stw_memory_manager;   }
 480   SoftRefPolicy* soft_ref_policy()                  { return &_soft_ref_policy;      }
 481 
 482   GrowableArray<GCMemoryManager*> memory_managers();
 483   GrowableArray<MemoryPool*> memory_pools();
 484   MemoryUsage memory_usage();
 485   GCTracer* tracer();
 486   GCTimer* gc_timer() const;
 487   CollectorPolicy* collector_policy() const;
 488 
 489 // ---------- Reference processing
 490 //
 491 private:
 492   AlwaysTrueClosure    _subject_to_discovery;
 493   ReferenceProcessor*  _ref_processor;
 494   ShenandoahSharedFlag _process_references;
 495 
 496   void ref_processing_init();
 497 
 498 public:
 499   ReferenceProcessor* ref_processor() { return _ref_processor; }
 500   void set_process_references(bool pr);
 501   bool process_references() const;
 502 
 503 // ---------- Class Unloading
 504 //
 505 private:
 506   ShenandoahSharedFlag _unload_classes;
 507 
 508 public:
 509   void set_unload_classes(bool uc);
 510   bool unload_classes() const;
 511 
 512   // Delete entries for dead interned string and clean up unreferenced symbols
 513   // in symbol table, possibly in parallel.
 514   void unload_classes_and_cleanup_tables(bool full_gc);
 515 
 516 // ---------- Generic interface hooks
 517 // Minor things that super-interface expects us to implement to play nice with
 518 // the rest of runtime. Some of the things here are not required to be implemented,
 519 // and can be stubbed out.
 520 //
 521 public:
 522   AdaptiveSizePolicy* size_policy() shenandoah_not_implemented_return(NULL);
 523   bool is_maximal_no_gc() const shenandoah_not_implemented_return(false);
 524 
 525   bool is_in(const void* p) const;
 526 
 527   // All objects can potentially move
 528   bool is_scavengable(oop obj) { return true; };
 529 
 530   void collect(GCCause::Cause cause);
 531   void do_full_collection(bool clear_all_soft_refs);
 532 
 533   // Used for parsing heap during error printing
 534   HeapWord* block_start(const void* addr) const;
 535   size_t block_size(const HeapWord* addr) const;
 536   bool block_is_obj(const HeapWord* addr) const;
 537 
 538   // Used for native heap walkers: heap dumpers, mostly
 539   void object_iterate(ObjectClosure* cl);
 540   void safe_object_iterate(ObjectClosure* cl);
 541 
 542   // Used by RMI
 543   jlong millis_since_last_gc();
 544 
 545 // ---------- Safepoint interface hooks
 546 //
 547 public:
 548   void safepoint_synchronize_begin();
 549   void safepoint_synchronize_end();
 550 
 551 // ---------- Code roots handling hooks
 552 //
 553 public:
 554   void register_nmethod(nmethod* nm);
 555   void unregister_nmethod(nmethod* nm);
 556 
 557 // ---------- Pinning hooks
 558 //
 559 public:
 560   // Shenandoah supports per-object (per-region) pinning
 561   bool supports_object_pinning() const { return true; }
 562 
 563   oop pin_object(JavaThread* thread, oop obj);
 564   void unpin_object(JavaThread* thread, oop obj);
 565 
 566 // ---------- Allocation support
 567 //
 568 private:
 569   HeapWord* allocate_memory_under_lock(ShenandoahAllocRequest& request, bool& in_new_region);
 570   inline HeapWord* allocate_from_gclab(Thread* thread, size_t size);
 571   HeapWord* allocate_from_gclab_slow(Thread* thread, size_t size);
 572   HeapWord* allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size);
 573   void retire_and_reset_gclabs();
 574 
 575 public:
 576   HeapWord* allocate_memory(ShenandoahAllocRequest& request);
 577   HeapWord* mem_allocate(size_t size, bool* what);
 578   MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
 579                                                size_t size,
 580                                                Metaspace::MetadataType mdtype);
 581 
 582   void notify_mutator_alloc_words(size_t words, bool waste);
 583 
 584   // Shenandoah supports TLAB allocation
 585   bool supports_tlab_allocation() const { return true; }
 586 
 587   HeapWord* allocate_new_tlab(size_t min_size, size_t requested_size, size_t* actual_size);
 588   size_t tlab_capacity(Thread *thr) const;
 589   size_t unsafe_max_tlab_alloc(Thread *thread) const;
 590   size_t max_tlab_size() const;
 591   size_t tlab_used(Thread* ignored) const;
 592 
 593   void accumulate_statistics_tlabs();
 594   void resize_tlabs();
 595 
 596   void ensure_parsability(bool retire_tlabs);
 597   void make_parsable(bool retire_tlabs);
 598 
 599 // ---------- Marking support
 600 //
 601 private:
 602   ShenandoahMarkingContext* _marking_context;
 603   MemRegion  _bitmap_region;
 604   MemRegion  _aux_bitmap_region;
 605   MarkBitMap _verification_bit_map;
 606   MarkBitMap _aux_bit_map;
 607 
 608   size_t _bitmap_size;
 609   size_t _bitmap_regions_per_slice;
 610   size_t _bitmap_bytes_per_slice;
 611 
 612   bool _bitmap_region_special;
 613   bool _aux_bitmap_region_special;
 614 
 615   // Used for buffering per-region liveness data.
 616   // Needed since ShenandoahHeapRegion uses atomics to update liveness.
 617   //
 618   // The array has max-workers elements, each of which is an array of
 619   // jushort * max_regions. The choice of jushort is not accidental:
 620   // there is a tradeoff between static/dynamic footprint that translates
 621   // into cache pressure (which is already high during marking), and
 622   // too many atomic updates. size_t/jint is too large, jbyte is too small.
 623   jushort** _liveness_cache;
 624 
 625 public:
 626   inline ShenandoahMarkingContext* complete_marking_context() const;
 627   inline ShenandoahMarkingContext* marking_context() const;
 628   inline void mark_complete_marking_context();
 629   inline void mark_incomplete_marking_context();
 630 
 631   template<class T>
 632   inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl);
 633 
 634   template<class T>
 635   inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
 636 
 637   template<class T>
 638   inline void marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
 639 
 640   void reset_mark_bitmap();
 641 
 642   // SATB barriers hooks
 643   inline bool requires_marking(const void* entry) const;
 644   void force_satb_flush_all_threads();
 645 
 646   // Support for bitmap uncommits
 647   bool commit_bitmap_slice(ShenandoahHeapRegion *r);
 648   bool uncommit_bitmap_slice(ShenandoahHeapRegion *r);
 649   bool is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self = false);
 650 
 651   // Liveness caching support
 652   jushort* get_liveness_cache(uint worker_id);
 653   void flush_liveness_cache(uint worker_id);
 654 
 655 // ---------- Evacuation support
 656 //
 657 private:
 658   ShenandoahCollectionSet* _collection_set;
 659   ShenandoahEvacOOMHandler _oom_evac_handler;
 660 
 661   void evacuate_and_update_roots();
 662 
 663 public:
 664   static address in_cset_fast_test_addr();
 665 
 666   ShenandoahCollectionSet* collection_set() const { return _collection_set; }
 667 
 668   template <class T>
 669   inline bool in_collection_set(T obj) const;
 670 
 671   // Avoid accidentally calling the method above with ShenandoahHeapRegion*, which would be *wrong*.
 672   inline bool in_collection_set(ShenandoahHeapRegion* r) shenandoah_not_implemented_return(false);
 673 
 674   // Evacuates object src. Returns the evacuated object, either evacuated
 675   // by this thread, or by some other thread.
 676   inline oop evacuate_object(oop src, Thread* thread);
 677 
 678   // Call before/after evacuation.
 679   void enter_evacuation();
 680   void leave_evacuation();
 681 
 682 // ---------- Helper functions
 683 //
 684 public:
 685   template <class T>
 686   inline oop evac_update_with_forwarded(T* p);
 687 
 688   template <class T>
 689   inline oop maybe_update_with_forwarded(T* p);
 690 
 691   template <class T>
 692   inline oop maybe_update_with_forwarded_not_null(T* p, oop obj);
 693 
 694   template <class T>
 695   inline oop update_with_forwarded_not_null(T* p, oop obj);
 696 
 697   static inline oop cas_oop(oop n, narrowOop* addr, oop c);
 698   static inline oop cas_oop(oop n, oop* addr, oop c);
 699 
 700   void trash_humongous_region_at(ShenandoahHeapRegion *r);
 701 
 702   void deduplicate_string(oop str);
 703 
 704   void stop_concurrent_marking();
 705 
 706 private:
 707   void trash_cset_regions();
 708   void update_heap_references(bool concurrent);
 709 
 710 // ---------- Testing helpers functions
 711 //
 712 private:
 713   ShenandoahSharedFlag _inject_alloc_failure;
 714 
 715   void try_inject_alloc_failure();
 716   bool should_inject_alloc_failure();
 717 };
 718 
 719 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP