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  24 
  25 #ifndef SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP
  26 #define SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP
  27 
  28 #include "gc/shared/collectedHeap.hpp"
  29 #include "gc/shared/collectorPolicy.hpp"
  30 #include "gc/shared/generation.hpp"
  31 #include "gc/shared/oopStorageParState.hpp"
  32 #include "gc/shared/softRefGenPolicy.hpp"
  33 
  34 class AdaptiveSizePolicy;
  35 class GCPolicyCounters;
  36 class GenerationSpec;
  37 class StrongRootsScope;
  38 class SubTasksDone;
  39 class WorkGang;
  40 
  41 // A "GenCollectedHeap" is a CollectedHeap that uses generational
  42 // collection.  It has two generations, young and old.
  43 class GenCollectedHeap : public CollectedHeap {
  44   friend class GenCollectorPolicy;
  45   friend class Generation;
  46   friend class DefNewGeneration;
  47   friend class TenuredGeneration;
  48   friend class ConcurrentMarkSweepGeneration;
  49   friend class CMSCollector;
  50   friend class GenMarkSweep;
  51   friend class VM_GenCollectForAllocation;
  52   friend class VM_GenCollectFull;
  53   friend class VM_GenCollectFullConcurrent;
  54   friend class VM_GC_HeapInspection;
  55   friend class VM_HeapDumper;
  56   friend class HeapInspection;
  57   friend class GCCauseSetter;
  58   friend class VMStructs;
  59 public:
  60   friend class VM_PopulateDumpSharedSpace;
  61 
  62   enum GenerationType {
  63     YoungGen,
  64     OldGen
  65   };
  66 
  67 protected:
  68   Generation* _young_gen;
  69   Generation* _old_gen;
  70 
  71 private:
  72   GenerationSpec* _young_gen_spec;
  73   GenerationSpec* _old_gen_spec;
  74 
  75   // The singleton CardTable Remembered Set.
  76   CardTableRS* _rem_set;
  77 
  78   // The generational collector policy.
  79   GenCollectorPolicy* _gen_policy;
  80 
  81   SoftRefGenPolicy _soft_ref_gen_policy;
  82 
  83   // The sizing of the heap is controlled by a sizing policy.
  84   AdaptiveSizePolicy* _size_policy;
  85 
  86   GCPolicyCounters* _gc_policy_counters;
  87 
  88   // Indicates that the most recent previous incremental collection failed.
  89   // The flag is cleared when an action is taken that might clear the
  90   // condition that caused that incremental collection to fail.
  91   bool _incremental_collection_failed;
  92 
  93   // In support of ExplicitGCInvokesConcurrent functionality
  94   unsigned int _full_collections_completed;
  95 
  96   // Collects the given generation.
  97   void collect_generation(Generation* gen, bool full, size_t size, bool is_tlab,
  98                           bool run_verification, bool clear_soft_refs,
  99                           bool restore_marks_for_biased_locking);
 100 
 101   // Reserve aligned space for the heap as needed by the contained generations.
 102   char* allocate(size_t alignment, ReservedSpace* heap_rs);
 103 
 104   // Initialize ("weak") refs processing support
 105   void ref_processing_init();
 106 
 107 protected:
 108 
 109   // The set of potentially parallel tasks in root scanning.
 110   enum GCH_strong_roots_tasks {
 111     GCH_PS_Universe_oops_do,
 112     GCH_PS_JNIHandles_oops_do,
 113     GCH_PS_ObjectSynchronizer_oops_do,
 114     GCH_PS_FlatProfiler_oops_do,
 115     GCH_PS_Management_oops_do,
 116     GCH_PS_SystemDictionary_oops_do,
 117     GCH_PS_ClassLoaderDataGraph_oops_do,
 118     GCH_PS_jvmti_oops_do,
 119     GCH_PS_CodeCache_oops_do,
 120     GCH_PS_aot_oops_do,
 121     GCH_PS_younger_gens,
 122     // Leave this one last.
 123     GCH_PS_NumElements
 124   };
 125 
 126   // Data structure for claiming the (potentially) parallel tasks in
 127   // (gen-specific) roots processing.
 128   SubTasksDone* _process_strong_tasks;
 129 
 130   GCMemoryManager* _young_manager;
 131   GCMemoryManager* _old_manager;
 132 
 133   // Helper functions for allocation
 134   HeapWord* attempt_allocation(size_t size,
 135                                bool   is_tlab,
 136                                bool   first_only);
 137 
 138   // Helper function for two callbacks below.
 139   // Considers collection of the first max_level+1 generations.
 140   void do_collection(bool           full,
 141                      bool           clear_all_soft_refs,
 142                      size_t         size,
 143                      bool           is_tlab,
 144                      GenerationType max_generation);
 145 
 146   // Callback from VM_GenCollectForAllocation operation.
 147   // This function does everything necessary/possible to satisfy an
 148   // allocation request that failed in the youngest generation that should
 149   // have handled it (including collection, expansion, etc.)
 150   HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
 151 
 152   // Callback from VM_GenCollectFull operation.
 153   // Perform a full collection of the first max_level+1 generations.
 154   virtual void do_full_collection(bool clear_all_soft_refs);
 155   void do_full_collection(bool clear_all_soft_refs, GenerationType max_generation);
 156 
 157   // Does the "cause" of GC indicate that
 158   // we absolutely __must__ clear soft refs?
 159   bool must_clear_all_soft_refs();
 160 
 161   GenCollectedHeap(GenCollectorPolicy *policy,
 162                    Generation::Name young,
 163                    Generation::Name old,
 164                    const char* policy_counters_name);
 165 
 166 public:
 167 
 168   // Returns JNI_OK on success
 169   virtual jint initialize();
 170   virtual CardTableRS* create_rem_set(const MemRegion& reserved_region);
 171 
 172   void initialize_size_policy(size_t init_eden_size,
 173                               size_t init_promo_size,
 174                               size_t init_survivor_size);
 175 
 176   // Does operations required after initialization has been done.
 177   void post_initialize();
 178 
 179   Generation* young_gen() const { return _young_gen; }
 180   Generation* old_gen()   const { return _old_gen; }
 181 
 182   bool is_young_gen(const Generation* gen) const { return gen == _young_gen; }
 183   bool is_old_gen(const Generation* gen) const { return gen == _old_gen; }
 184 
 185   GenerationSpec* young_gen_spec() const;
 186   GenerationSpec* old_gen_spec() const;
 187 
 188   // The generational collector policy.
 189   GenCollectorPolicy* gen_policy() const { return _gen_policy; }
 190 
 191   virtual CollectorPolicy* collector_policy() const { return gen_policy(); }
 192 
 193   virtual SoftRefPolicy* soft_ref_policy() { return &_soft_ref_gen_policy; }
 194 
 195   // Adaptive size policy
 196   virtual AdaptiveSizePolicy* size_policy() {
 197     return _size_policy;
 198   }
 199 
 200   // Performance Counter support
 201   GCPolicyCounters* counters()     { return _gc_policy_counters; }
 202 
 203   // Return the (conservative) maximum heap alignment
 204   static size_t conservative_max_heap_alignment() {
 205     return Generation::GenGrain;
 206   }
 207 
 208   size_t capacity() const;
 209   size_t used() const;
 210 
 211   // Save the "used_region" for both generations.
 212   void save_used_regions();
 213 
 214   size_t max_capacity() const;
 215 
 216   HeapWord* mem_allocate(size_t size, bool*  gc_overhead_limit_was_exceeded);
 217 
 218   // We may support a shared contiguous allocation area, if the youngest
 219   // generation does.
 220   bool supports_inline_contig_alloc() const;
 221   HeapWord* volatile* top_addr() const;
 222   HeapWord** end_addr() const;
 223 
 224   // Perform a full collection of the heap; intended for use in implementing
 225   // "System.gc". This implies as full a collection as the CollectedHeap
 226   // supports. Caller does not hold the Heap_lock on entry.
 227   virtual void collect(GCCause::Cause cause);
 228 
 229   // The same as above but assume that the caller holds the Heap_lock.
 230   void collect_locked(GCCause::Cause cause);
 231 
 232   // Perform a full collection of generations up to and including max_generation.
 233   // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry.
 234   void collect(GCCause::Cause cause, GenerationType max_generation);
 235 
 236   // Returns "TRUE" iff "p" points into the committed areas of the heap.
 237   // The methods is_in(), is_in_closed_subset() and is_in_youngest() may
 238   // be expensive to compute in general, so, to prevent
 239   // their inadvertent use in product jvm's, we restrict their use to
 240   // assertion checking or verification only.
 241   bool is_in(const void* p) const;
 242 
 243   // Returns true if the reference is to an object in the reserved space
 244   // for the young generation.
 245   // Assumes the the young gen address range is less than that of the old gen.
 246   bool is_in_young(oop p);
 247 
 248 #ifdef ASSERT
 249   bool is_in_partial_collection(const void* p);
 250 #endif
 251 
 252   virtual bool is_scavengable(oop obj) {
 253     return is_in_young(obj);
 254   }
 255 
 256   // Optimized nmethod scanning support routines
 257   virtual void register_nmethod(nmethod* nm);
 258   virtual void verify_nmethod(nmethod* nmethod);
 259 
 260   // Iteration functions.
 261   void oop_iterate_no_header(OopClosure* cl);
 262   void oop_iterate(ExtendedOopClosure* cl);
 263   void object_iterate(ObjectClosure* cl);
 264   void safe_object_iterate(ObjectClosure* cl);
 265   Space* space_containing(const void* addr) const;
 266 
 267   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
 268   // each address in the (reserved) heap is a member of exactly
 269   // one block.  The defining characteristic of a block is that it is
 270   // possible to find its size, and thus to progress forward to the next
 271   // block.  (Blocks may be of different sizes.)  Thus, blocks may
 272   // represent Java objects, or they might be free blocks in a
 273   // free-list-based heap (or subheap), as long as the two kinds are
 274   // distinguishable and the size of each is determinable.
 275 
 276   // Returns the address of the start of the "block" that contains the
 277   // address "addr".  We say "blocks" instead of "object" since some heaps
 278   // may not pack objects densely; a chunk may either be an object or a
 279   // non-object.
 280   virtual HeapWord* block_start(const void* addr) const;
 281 
 282   // Requires "addr" to be the start of a chunk, and returns its size.
 283   // "addr + size" is required to be the start of a new chunk, or the end
 284   // of the active area of the heap. Assumes (and verifies in non-product
 285   // builds) that addr is in the allocated part of the heap and is
 286   // the start of a chunk.
 287   virtual size_t block_size(const HeapWord* addr) const;
 288 
 289   // Requires "addr" to be the start of a block, and returns "TRUE" iff
 290   // the block is an object. Assumes (and verifies in non-product
 291   // builds) that addr is in the allocated part of the heap and is
 292   // the start of a chunk.
 293   virtual bool block_is_obj(const HeapWord* addr) const;
 294 
 295   // Section on TLAB's.
 296   virtual bool supports_tlab_allocation() const;
 297   virtual size_t tlab_capacity(Thread* thr) const;
 298   virtual size_t tlab_used(Thread* thr) const;
 299   virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
 300   virtual HeapWord* allocate_new_tlab(size_t min_size,
 301                                       size_t requested_size,
 302                                       size_t* actual_size);
 303 
 304   // The "requestor" generation is performing some garbage collection
 305   // action for which it would be useful to have scratch space.  The
 306   // requestor promises to allocate no more than "max_alloc_words" in any
 307   // older generation (via promotion say.)   Any blocks of space that can
 308   // be provided are returned as a list of ScratchBlocks, sorted by
 309   // decreasing size.
 310   ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
 311   // Allow each generation to reset any scratch space that it has
 312   // contributed as it needs.
 313   void release_scratch();
 314 
 315   // Ensure parsability: override
 316   virtual void ensure_parsability(bool retire_tlabs);
 317 
 318   // Time in ms since the longest time a collector ran in
 319   // in any generation.
 320   virtual jlong millis_since_last_gc();
 321 
 322   // Total number of full collections completed.
 323   unsigned int total_full_collections_completed() {
 324     assert(_full_collections_completed <= _total_full_collections,
 325            "Can't complete more collections than were started");
 326     return _full_collections_completed;
 327   }
 328 
 329   // Update above counter, as appropriate, at the end of a stop-world GC cycle
 330   unsigned int update_full_collections_completed();
 331   // Update above counter, as appropriate, at the end of a concurrent GC cycle
 332   unsigned int update_full_collections_completed(unsigned int count);
 333 
 334   // Update "time of last gc" for all generations to "now".
 335   void update_time_of_last_gc(jlong now) {
 336     _young_gen->update_time_of_last_gc(now);
 337     _old_gen->update_time_of_last_gc(now);
 338   }
 339 
 340   // Update the gc statistics for each generation.
 341   void update_gc_stats(Generation* current_generation, bool full) {
 342     _old_gen->update_gc_stats(current_generation, full);
 343   }
 344 
 345   bool no_gc_in_progress() { return !is_gc_active(); }
 346 
 347   // Override.
 348   void prepare_for_verify();
 349 
 350   // Override.
 351   void verify(VerifyOption option);
 352 
 353   // Override.
 354   virtual void print_on(outputStream* st) const;
 355   virtual void print_gc_threads_on(outputStream* st) const;
 356   virtual void gc_threads_do(ThreadClosure* tc) const;
 357   virtual void print_tracing_info() const;
 358 
 359   void print_heap_change(size_t young_prev_used, size_t old_prev_used) const;
 360 
 361   // The functions below are helper functions that a subclass of
 362   // "CollectedHeap" can use in the implementation of its virtual
 363   // functions.
 364 
 365   class GenClosure : public StackObj {
 366    public:
 367     virtual void do_generation(Generation* gen) = 0;
 368   };
 369 
 370   // Apply "cl.do_generation" to all generations in the heap
 371   // If "old_to_young" determines the order.
 372   void generation_iterate(GenClosure* cl, bool old_to_young);
 373 
 374   // Return "true" if all generations have reached the
 375   // maximal committed limit that they can reach, without a garbage
 376   // collection.
 377   virtual bool is_maximal_no_gc() const;
 378 
 379   // This function returns the CardTableRS object that allows us to scan
 380   // generations in a fully generational heap.
 381   CardTableRS* rem_set() { return _rem_set; }
 382 
 383   // Convenience function to be used in situations where the heap type can be
 384   // asserted to be this type.
 385   static GenCollectedHeap* heap();
 386 
 387   // The ScanningOption determines which of the roots
 388   // the closure is applied to:
 389   // "SO_None" does none;
 390   enum ScanningOption {
 391     SO_None                =  0x0,
 392     SO_AllCodeCache        =  0x8,
 393     SO_ScavengeCodeCache   = 0x10
 394   };
 395 
 396  protected:
 397   void process_roots(StrongRootsScope* scope,
 398                      ScanningOption so,
 399                      OopClosure* strong_roots,
 400                      OopClosure* weak_roots,
 401                      CLDClosure* strong_cld_closure,
 402                      CLDClosure* weak_cld_closure,
 403                      CodeBlobToOopClosure* code_roots);
 404 
 405   void process_string_table_roots(StrongRootsScope* scope,
 406                                   OopClosure* root_closure,
 407                                   OopStorage::ParState<false, false>* par_state_string);
 408 
 409   // Accessor for memory state verification support
 410   NOT_PRODUCT(
 411     virtual size_t skip_header_HeapWords() { return 0; }
 412   )
 413 
 414   virtual void gc_prologue(bool full);
 415   virtual void gc_epilogue(bool full);
 416 
 417  public:
 418   void young_process_roots(StrongRootsScope* scope,
 419                            OopsInGenClosure* root_closure,
 420                            OopsInGenClosure* old_gen_closure,
 421                            CLDClosure* cld_closure,
 422                            OopStorage::ParState<false, false>* par_state_string = NULL);
 423 
 424   void full_process_roots(StrongRootsScope* scope,
 425                           bool is_adjust_phase,
 426                           ScanningOption so,
 427                           bool only_strong_roots,
 428                           OopsInGenClosure* root_closure,
 429                           CLDClosure* cld_closure,
 430                           OopStorage::ParState<false, false>* par_state_string = NULL);
 431 
 432   // Apply "root_closure" to all the weak roots of the system.
 433   // These include JNI weak roots, string table,
 434   // and referents of reachable weak refs.
 435   void gen_process_weak_roots(OopClosure* root_closure);
 436 
 437   // Set the saved marks of generations, if that makes sense.
 438   // In particular, if any generation might iterate over the oops
 439   // in other generations, it should call this method.
 440   void save_marks();
 441 
 442   // Returns "true" iff no allocations have occurred since the last
 443   // call to "save_marks".
 444   bool no_allocs_since_save_marks();
 445 
 446   // Returns true if an incremental collection is likely to fail.
 447   // We optionally consult the young gen, if asked to do so;
 448   // otherwise we base our answer on whether the previous incremental
 449   // collection attempt failed with no corrective action as of yet.
 450   bool incremental_collection_will_fail(bool consult_young) {
 451     // The first disjunct remembers if an incremental collection failed, even
 452     // when we thought (second disjunct) that it would not.
 453     return incremental_collection_failed() ||
 454            (consult_young && !_young_gen->collection_attempt_is_safe());
 455   }
 456 
 457   // If a generation bails out of an incremental collection,
 458   // it sets this flag.
 459   bool incremental_collection_failed() const {
 460     return _incremental_collection_failed;
 461   }
 462   void set_incremental_collection_failed() {
 463     _incremental_collection_failed = true;
 464   }
 465   void clear_incremental_collection_failed() {
 466     _incremental_collection_failed = false;
 467   }
 468 
 469   // Promotion of obj into gen failed.  Try to promote obj to higher
 470   // gens in ascending order; return the new location of obj if successful.
 471   // Otherwise, try expand-and-allocate for obj in both the young and old
 472   // generation; return the new location of obj if successful.  Otherwise, return NULL.
 473   oop handle_failed_promotion(Generation* old_gen,
 474                               oop obj,
 475                               size_t obj_size);
 476 
 477 
 478 private:
 479   // Return true if an allocation should be attempted in the older generation
 480   // if it fails in the younger generation.  Return false, otherwise.
 481   bool should_try_older_generation_allocation(size_t word_size) const;
 482 
 483   // Try to allocate space by expanding the heap.
 484   HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
 485 
 486   HeapWord* mem_allocate_work(size_t size,
 487                               bool is_tlab,
 488                               bool* gc_overhead_limit_was_exceeded);
 489 
 490   // Override
 491   void check_for_non_bad_heap_word_value(HeapWord* addr,
 492     size_t size) PRODUCT_RETURN;
 493 
 494 #if INCLUDE_SERIALGC
 495   // For use by mark-sweep.  As implemented, mark-sweep-compact is global
 496   // in an essential way: compaction is performed across generations, by
 497   // iterating over spaces.
 498   void prepare_for_compaction();
 499 #endif
 500 
 501   // Perform a full collection of the generations up to and including max_generation.
 502   // This is the low level interface used by the public versions of
 503   // collect() and collect_locked(). Caller holds the Heap_lock on entry.
 504   void collect_locked(GCCause::Cause cause, GenerationType max_generation);
 505 
 506   // Save the tops of the spaces in all generations
 507   void record_gen_tops_before_GC() PRODUCT_RETURN;
 508 };
 509 
 510 #endif // SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP