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