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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/softRefGenPolicy.hpp"
  32 
  33 class AdaptiveSizePolicy;
  34 class GCPolicyCounters;
  35 class GenerationSpec;
  36 class StrongRootsScope;
  37 class SubTasksDone;
  38 class WorkGang;
  39 
  40 // A "GenCollectedHeap" is a CollectedHeap that uses generational
  41 // collection.  It has two generations, young and old.
  42 class GenCollectedHeap : public CollectedHeap {
  43   friend class GenCollectorPolicy;
  44   friend class Generation;
  45   friend class DefNewGeneration;
  46   friend class TenuredGeneration;
  47   friend class ConcurrentMarkSweepGeneration;
  48   friend class CMSCollector;
  49   friend class GenMarkSweep;
  50   friend class VM_GenCollectForAllocation;
  51   friend class VM_GenCollectFull;
  52   friend class VM_GenCollectFullConcurrent;
  53   friend class VM_GC_HeapInspection;
  54   friend class VM_HeapDumper;
  55   friend class HeapInspection;
  56   friend class GCCauseSetter;
  57   friend class VMStructs;
  58 public:
  59   friend class VM_PopulateDumpSharedSpace;
  60 
  61   enum GenerationType {
  62     YoungGen,
  63     OldGen
  64   };
  65 
  66 private:
  67   Generation* _young_gen;
  68   Generation* _old_gen;
  69 
  70   GenerationSpec* _young_gen_spec;
  71   GenerationSpec* _old_gen_spec;
  72 
  73   // The singleton CardTable Remembered Set.
  74   CardTableRS* _rem_set;
  75 
  76   // The generational collector policy.
  77   GenCollectorPolicy* _gen_policy;
  78 
  79   SoftRefGenPolicy _soft_ref_gen_policy;
  80 
  81   // The sizing of the heap is controlled by a sizing policy.
  82   AdaptiveSizePolicy* _size_policy;
  83 
  84   GCPolicyCounters* _gc_policy_counters;
  85 
  86   // Indicates that the most recent previous incremental collection failed.
  87   // The flag is cleared when an action is taken that might clear the
  88   // condition that caused that incremental collection to fail.
  89   bool _incremental_collection_failed;
  90 
  91   // In support of ExplicitGCInvokesConcurrent functionality
  92   unsigned int _full_collections_completed;
  93 
  94   // Collects the given generation.
  95   void collect_generation(Generation* gen, bool full, size_t size, bool is_tlab,
  96                           bool run_verification, bool clear_soft_refs,
  97                           bool restore_marks_for_biased_locking);
  98 
  99   // Reserve aligned space for the heap as needed by the contained generations.
 100   char* allocate(size_t alignment, ReservedSpace* heap_rs);
 101 
 102   // Initialize ("weak") refs processing support
 103   void ref_processing_init();
 104 
 105 protected:
 106 
 107   // The set of potentially parallel tasks in root scanning.
 108   enum GCH_strong_roots_tasks {
 109     GCH_PS_Universe_oops_do,
 110     GCH_PS_JNIHandles_oops_do,
 111     GCH_PS_ObjectSynchronizer_oops_do,
 112     GCH_PS_FlatProfiler_oops_do,
 113     GCH_PS_Management_oops_do,
 114     GCH_PS_SystemDictionary_oops_do,
 115     GCH_PS_ClassLoaderDataGraph_oops_do,
 116     GCH_PS_jvmti_oops_do,
 117     GCH_PS_CodeCache_oops_do,
 118     GCH_PS_aot_oops_do,
 119     GCH_PS_younger_gens,
 120     // Leave this one last.
 121     GCH_PS_NumElements
 122   };
 123 
 124   // Data structure for claiming the (potentially) parallel tasks in
 125   // (gen-specific) roots processing.
 126   SubTasksDone* _process_strong_tasks;
 127 
 128   GCMemoryManager* _young_manager;
 129   GCMemoryManager* _old_manager;
 130 
 131   // Helper functions for allocation
 132   HeapWord* attempt_allocation(size_t size,
 133                                bool   is_tlab,
 134                                bool   first_only);
 135 
 136   // Helper function for two callbacks below.
 137   // Considers collection of the first max_level+1 generations.
 138   void do_collection(bool           full,
 139                      bool           clear_all_soft_refs,
 140                      size_t         size,
 141                      bool           is_tlab,
 142                      GenerationType max_generation);
 143 
 144   // Callback from VM_GenCollectForAllocation operation.
 145   // This function does everything necessary/possible to satisfy an
 146   // allocation request that failed in the youngest generation that should
 147   // have handled it (including collection, expansion, etc.)
 148   HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
 149 
 150   // Callback from VM_GenCollectFull operation.
 151   // Perform a full collection of the first max_level+1 generations.
 152   virtual void do_full_collection(bool clear_all_soft_refs);
 153   void do_full_collection(bool clear_all_soft_refs, GenerationType max_generation);
 154 
 155   // Does the "cause" of GC indicate that
 156   // we absolutely __must__ clear soft refs?
 157   bool must_clear_all_soft_refs();
 158 
 159   GenCollectedHeap(GenCollectorPolicy *policy,
 160                    Generation::Name young,
 161                    Generation::Name old,
 162                    const char* policy_counters_name);
 163 
 164   virtual void check_gen_kinds() = 0;
 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 size);
 301 
 302   // The "requestor" generation is performing some garbage collection
 303   // action for which it would be useful to have scratch space.  The
 304   // requestor promises to allocate no more than "max_alloc_words" in any
 305   // older generation (via promotion say.)   Any blocks of space that can
 306   // be provided are returned as a list of ScratchBlocks, sorted by
 307   // decreasing size.
 308   ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
 309   // Allow each generation to reset any scratch space that it has
 310   // contributed as it needs.
 311   void release_scratch();
 312 
 313   // Ensure parsability: override
 314   virtual void ensure_parsability(bool retire_tlabs);
 315 
 316   // Time in ms since the longest time a collector ran in
 317   // in any generation.
 318   virtual jlong millis_since_last_gc();
 319 
 320   // Total number of full collections completed.
 321   unsigned int total_full_collections_completed() {
 322     assert(_full_collections_completed <= _total_full_collections,
 323            "Can't complete more collections than were started");
 324     return _full_collections_completed;
 325   }
 326 
 327   // Update above counter, as appropriate, at the end of a stop-world GC cycle
 328   unsigned int update_full_collections_completed();
 329   // Update above counter, as appropriate, at the end of a concurrent GC cycle
 330   unsigned int update_full_collections_completed(unsigned int count);
 331 
 332   // Update "time of last gc" for all generations to "now".
 333   void update_time_of_last_gc(jlong now) {
 334     _young_gen->update_time_of_last_gc(now);
 335     _old_gen->update_time_of_last_gc(now);
 336   }
 337 
 338   // Update the gc statistics for each generation.
 339   void update_gc_stats(Generation* current_generation, bool full) {
 340     _old_gen->update_gc_stats(current_generation, full);
 341   }
 342 
 343   bool no_gc_in_progress() { return !is_gc_active(); }
 344 
 345   // Override.
 346   void prepare_for_verify();
 347 
 348   // Override.
 349   void verify(VerifyOption option);
 350 
 351   // Override.
 352   virtual void print_on(outputStream* st) const;
 353   virtual void print_gc_threads_on(outputStream* st) const;
 354   virtual void gc_threads_do(ThreadClosure* tc) const;
 355   virtual void print_tracing_info() const;
 356 
 357   void print_heap_change(size_t young_prev_used, size_t old_prev_used) const;
 358 
 359   // The functions below are helper functions that a subclass of
 360   // "CollectedHeap" can use in the implementation of its virtual
 361   // functions.
 362 
 363   class GenClosure : public StackObj {
 364    public:
 365     virtual void do_generation(Generation* gen) = 0;
 366   };
 367 
 368   // Apply "cl.do_generation" to all generations in the heap
 369   // If "old_to_young" determines the order.
 370   void generation_iterate(GenClosure* cl, bool old_to_young);
 371 
 372   // Return "true" if all generations have reached the
 373   // maximal committed limit that they can reach, without a garbage
 374   // collection.
 375   virtual bool is_maximal_no_gc() const;
 376 
 377   // This function returns the CardTableRS object that allows us to scan
 378   // generations in a fully generational heap.
 379   CardTableRS* rem_set() { return _rem_set; }
 380 
 381   // Convenience function to be used in situations where the heap type can be
 382   // asserted to be this type.
 383   static GenCollectedHeap* heap();
 384 
 385   // The ScanningOption determines which of the roots
 386   // the closure is applied to:
 387   // "SO_None" does none;
 388   enum ScanningOption {
 389     SO_None                =  0x0,
 390     SO_AllCodeCache        =  0x8,
 391     SO_ScavengeCodeCache   = 0x10
 392   };
 393 
 394  protected:
 395   void process_roots(StrongRootsScope* scope,
 396                      ScanningOption so,
 397                      OopClosure* strong_roots,
 398                      OopClosure* weak_roots,
 399                      CLDClosure* strong_cld_closure,
 400                      CLDClosure* weak_cld_closure,
 401                      CodeBlobToOopClosure* code_roots);
 402 
 403   void process_string_table_roots(StrongRootsScope* scope,
 404                                   OopClosure* root_closure);
 405 
 406   // Accessor for memory state verification support
 407   NOT_PRODUCT(
 408     virtual size_t skip_header_HeapWords() { return 0; }
 409   )
 410 
 411   virtual void gc_prologue(bool full);
 412   virtual void gc_epilogue(bool full);
 413 
 414  public:
 415   void young_process_roots(StrongRootsScope* scope,
 416                            OopsInGenClosure* root_closure,
 417                            OopsInGenClosure* old_gen_closure,
 418                            CLDClosure* cld_closure);
 419 
 420   void full_process_roots(StrongRootsScope* scope,
 421                           bool is_adjust_phase,
 422                           ScanningOption so,
 423                           bool only_strong_roots,
 424                           OopsInGenClosure* root_closure,
 425                           CLDClosure* cld_closure);
 426 
 427   // Apply "root_closure" to all the weak roots of the system.
 428   // These include JNI weak roots, string table,
 429   // and referents of reachable weak refs.
 430   void gen_process_weak_roots(OopClosure* root_closure);
 431 
 432   // Set the saved marks of generations, if that makes sense.
 433   // In particular, if any generation might iterate over the oops
 434   // in other generations, it should call this method.
 435   void save_marks();
 436 
 437   // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects
 438   // allocated since the last call to save_marks in generations at or above
 439   // "level".  The "cur" closure is
 440   // applied to references in the generation at "level", and the "older"
 441   // closure to older generations.
 442 #define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix)    \
 443   void oop_since_save_marks_iterate(GenerationType start_gen,           \
 444                                     OopClosureType* cur,                \
 445                                     OopClosureType* older);
 446 
 447   ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL)
 448 
 449 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL
 450 
 451   // Returns "true" iff no allocations have occurred since the last
 452   // call to "save_marks".
 453   bool no_allocs_since_save_marks();
 454 
 455   // Returns true if an incremental collection is likely to fail.
 456   // We optionally consult the young gen, if asked to do so;
 457   // otherwise we base our answer on whether the previous incremental
 458   // collection attempt failed with no corrective action as of yet.
 459   bool incremental_collection_will_fail(bool consult_young) {
 460     // The first disjunct remembers if an incremental collection failed, even
 461     // when we thought (second disjunct) that it would not.
 462     return incremental_collection_failed() ||
 463            (consult_young && !_young_gen->collection_attempt_is_safe());
 464   }
 465 
 466   // If a generation bails out of an incremental collection,
 467   // it sets this flag.
 468   bool incremental_collection_failed() const {
 469     return _incremental_collection_failed;
 470   }
 471   void set_incremental_collection_failed() {
 472     _incremental_collection_failed = true;
 473   }
 474   void clear_incremental_collection_failed() {
 475     _incremental_collection_failed = false;
 476   }
 477 
 478   // Promotion of obj into gen failed.  Try to promote obj to higher
 479   // gens in ascending order; return the new location of obj if successful.
 480   // Otherwise, try expand-and-allocate for obj in both the young and old
 481   // generation; return the new location of obj if successful.  Otherwise, return NULL.
 482   oop handle_failed_promotion(Generation* old_gen,
 483                               oop obj,
 484                               size_t obj_size);
 485 
 486 
 487 private:
 488   // Return true if an allocation should be attempted in the older generation
 489   // if it fails in the younger generation.  Return false, otherwise.
 490   bool should_try_older_generation_allocation(size_t word_size) const;
 491 
 492   // Try to allocate space by expanding the heap.
 493   HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
 494 
 495   HeapWord* mem_allocate_work(size_t size,
 496                               bool is_tlab,
 497                               bool* gc_overhead_limit_was_exceeded);
 498 
 499   // Override
 500   void check_for_non_bad_heap_word_value(HeapWord* addr,
 501     size_t size) PRODUCT_RETURN;
 502 
 503   // For use by mark-sweep.  As implemented, mark-sweep-compact is global
 504   // in an essential way: compaction is performed across generations, by
 505   // iterating over spaces.
 506   void prepare_for_compaction();
 507 
 508   // Perform a full collection of the generations up to and including max_generation.
 509   // This is the low level interface used by the public versions of
 510   // collect() and collect_locked(). Caller holds the Heap_lock on entry.
 511   void collect_locked(GCCause::Cause cause, GenerationType max_generation);
 512 
 513   // Save the tops of the spaces in all generations
 514   void record_gen_tops_before_GC() PRODUCT_RETURN;
 515 };
 516 
 517 #endif // SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP
--- EOF ---