1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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  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).
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  24 
  25 #ifndef SHARE_VM_GC_SERIAL_DEFNEWGENERATION_HPP
  26 #define SHARE_VM_GC_SERIAL_DEFNEWGENERATION_HPP
  27 
  28 #include "gc/serial/cSpaceCounters.hpp"
  29 #include "gc/shared/ageTable.hpp"
  30 #include "gc/shared/copyFailedInfo.hpp"
  31 #include "gc/shared/generation.hpp"
  32 #include "gc/shared/generationCounters.hpp"
  33 #include "gc/shared/preservedMarks.hpp"
  34 #include "utilities/stack.hpp"
  35 
  36 class ContiguousSpace;
  37 class ScanClosure;
  38 class STWGCTimer;
  39 class CSpaceCounters;
  40 class ScanWeakRefClosure;
  41 
  42 // DefNewGeneration is a young generation containing eden, from- and
  43 // to-space.
  44 
  45 class DefNewGeneration: public Generation {
  46   friend class VMStructs;
  47 
  48 protected:
  49   Generation* _old_gen;
  50   uint        _tenuring_threshold;   // Tenuring threshold for next collection.
  51   AgeTable    _age_table;
  52   // Size of object to pretenure in words; command line provides bytes
  53   size_t      _pretenure_size_threshold_words;
  54 
  55   AgeTable*   age_table() { return &_age_table; }
  56 
  57   // Initialize state to optimistically assume no promotion failure will
  58   // happen.
  59   void   init_assuming_no_promotion_failure();
  60   // True iff a promotion has failed in the current collection.
  61   bool   _promotion_failed;
  62   bool   promotion_failed() { return _promotion_failed; }
  63   PromotionFailedInfo _promotion_failed_info;
  64 
  65   // Handling promotion failure.  A young generation collection
  66   // can fail if a live object cannot be copied out of its
  67   // location in eden or from-space during the collection.  If
  68   // a collection fails, the young generation is left in a
  69   // consistent state such that it can be collected by a
  70   // full collection.
  71   //   Before the collection
  72   //     Objects are in eden or from-space
  73   //     All roots into the young generation point into eden or from-space.
  74   //
  75   //   After a failed collection
  76   //     Objects may be in eden, from-space, or to-space
  77   //     An object A in eden or from-space may have a copy B
  78   //       in to-space.  If B exists, all roots that once pointed
  79   //       to A must now point to B.
  80   //     All objects in the young generation are unmarked.
  81   //     Eden, from-space, and to-space will all be collected by
  82   //       the full collection.
  83   void handle_promotion_failure(oop);
  84 
  85   // In the absence of promotion failure, we wouldn't look at "from-space"
  86   // objects after a young-gen collection.  When promotion fails, however,
  87   // the subsequent full collection will look at from-space objects:
  88   // therefore we must remove their forwarding pointers.
  89   void remove_forwarding_pointers();
  90 
  91   // Preserved marks
  92   PreservedMarksSet _preserved_marks_set;
  93 
  94   // Promotion failure handling
  95   ExtendedOopClosure *_promo_failure_scan_stack_closure;
  96   void set_promo_failure_scan_stack_closure(ExtendedOopClosure *scan_stack_closure) {
  97     _promo_failure_scan_stack_closure = scan_stack_closure;
  98   }
  99 
 100   Stack<oop, mtGC> _promo_failure_scan_stack;
 101   void drain_promo_failure_scan_stack(void);
 102   bool _promo_failure_drain_in_progress;
 103 
 104   // Performance Counters
 105   GenerationCounters*  _gen_counters;
 106   CSpaceCounters*      _eden_counters;
 107   CSpaceCounters*      _from_counters;
 108   CSpaceCounters*      _to_counters;
 109 
 110   // sizing information
 111   size_t               _max_eden_size;
 112   size_t               _max_survivor_size;
 113 
 114   // Allocation support
 115   bool _should_allocate_from_space;
 116   bool should_allocate_from_space() const {
 117     return _should_allocate_from_space;
 118   }
 119   void clear_should_allocate_from_space() {
 120     _should_allocate_from_space = false;
 121   }
 122   void set_should_allocate_from_space() {
 123     _should_allocate_from_space = true;
 124   }
 125 
 126   // Tenuring
 127   void adjust_desired_tenuring_threshold();
 128 
 129   // Spaces
 130   ContiguousSpace* _eden_space;
 131   ContiguousSpace* _from_space;
 132   ContiguousSpace* _to_space;
 133 
 134   STWGCTimer* _gc_timer;
 135 
 136   enum SomeProtectedConstants {
 137     // Generations are GenGrain-aligned and have size that are multiples of
 138     // GenGrain.
 139     MinFreeScratchWords = 100
 140   };
 141 
 142   // Return the size of a survivor space if this generation were of size
 143   // gen_size.
 144   size_t compute_survivor_size(size_t gen_size, size_t alignment) const {
 145     size_t n = gen_size / (SurvivorRatio + 2);
 146     return n > alignment ? align_down(n, alignment) : alignment;
 147   }
 148 
 149  public:  // was "protected" but caused compile error on win32
 150   class IsAliveClosure: public BoolObjectClosure {
 151     Generation* _young_gen;
 152   public:
 153     IsAliveClosure(Generation* young_gen);
 154     bool do_object_b(oop p);
 155   };
 156 
 157   class KeepAliveClosure: public OopClosure {
 158   protected:
 159     ScanWeakRefClosure* _cl;
 160     CardTableRS* _rs;
 161     template <class T> void do_oop_work(T* p);
 162   public:
 163     KeepAliveClosure(ScanWeakRefClosure* cl);
 164     virtual void do_oop(oop* p);
 165     virtual void do_oop(narrowOop* p);
 166   };
 167 
 168   class FastKeepAliveClosure: public KeepAliveClosure {
 169   protected:
 170     HeapWord* _boundary;
 171     template <class T> void do_oop_work(T* p);
 172   public:
 173     FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl);
 174     virtual void do_oop(oop* p);
 175     virtual void do_oop(narrowOop* p);
 176   };
 177 
 178   class EvacuateFollowersClosure: public VoidClosure {
 179     GenCollectedHeap* _gch;
 180     ScanClosure* _scan_cur_or_nonheap;
 181     ScanClosure* _scan_older;
 182   public:
 183     EvacuateFollowersClosure(GenCollectedHeap* gch,
 184                              ScanClosure* cur, ScanClosure* older);
 185     void do_void();
 186   };
 187 
 188   class FastEvacuateFollowersClosure: public VoidClosure {
 189     GenCollectedHeap* _gch;
 190     DefNewGeneration* _young_gen;
 191     FastScanClosure* _scan_cur_or_nonheap;
 192     FastScanClosure* _scan_older;
 193   public:
 194     FastEvacuateFollowersClosure(GenCollectedHeap* gch,
 195                                  FastScanClosure* cur,
 196                                  FastScanClosure* older);
 197     void do_void();
 198   };
 199 
 200  public:
 201   DefNewGeneration(ReservedSpace rs, size_t initial_byte_size,
 202                    const char* policy="Copy");
 203 
 204   virtual void ref_processor_init();
 205 
 206   virtual Generation::Name kind() { return Generation::DefNew; }
 207 
 208   // Accessing spaces
 209   ContiguousSpace* eden() const           { return _eden_space; }
 210   ContiguousSpace* from() const           { return _from_space; }
 211   ContiguousSpace* to()   const           { return _to_space;   }
 212 
 213   virtual CompactibleSpace* first_compaction_space() const;
 214 
 215   // Space enquiries
 216   size_t capacity() const;
 217   size_t used() const;
 218   size_t free() const;
 219   size_t max_capacity() const;
 220   size_t capacity_before_gc() const;
 221   size_t unsafe_max_alloc_nogc() const;
 222   size_t contiguous_available() const;
 223 
 224   size_t max_eden_size() const              { return _max_eden_size; }
 225   size_t max_survivor_size() const          { return _max_survivor_size; }
 226 
 227   bool supports_inline_contig_alloc() const { return true; }
 228   HeapWord* volatile* top_addr() const;
 229   HeapWord** end_addr() const;
 230 
 231   // Thread-local allocation buffers
 232   bool supports_tlab_allocation() const { return true; }
 233   size_t tlab_capacity() const;
 234   size_t tlab_used() const;
 235   size_t unsafe_max_tlab_alloc() const;
 236 
 237   // Grow the generation by the specified number of bytes.
 238   // The size of bytes is assumed to be properly aligned.
 239   // Return true if the expansion was successful.
 240   bool expand(size_t bytes);
 241 
 242   // DefNewGeneration cannot currently expand except at
 243   // a GC.
 244   virtual bool is_maximal_no_gc() const { return true; }
 245 
 246   // Iteration
 247   void object_iterate(ObjectClosure* blk);
 248 
 249   void younger_refs_iterate(OopsInGenClosure* cl, uint n_threads);
 250 
 251   void space_iterate(SpaceClosure* blk, bool usedOnly = false);
 252 
 253   // Allocation support
 254   virtual bool should_allocate(size_t word_size, bool is_tlab) {
 255     assert(UseTLAB || !is_tlab, "Should not allocate tlab");
 256 
 257     size_t overflow_limit    = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
 258 
 259     const bool non_zero      = word_size > 0;
 260     const bool overflows     = word_size >= overflow_limit;
 261     const bool check_too_big = _pretenure_size_threshold_words > 0;
 262     const bool not_too_big   = word_size < _pretenure_size_threshold_words;
 263     const bool size_ok       = is_tlab || !check_too_big || not_too_big;
 264 
 265     bool result = !overflows &&
 266                   non_zero   &&
 267                   size_ok;
 268 
 269     return result;
 270   }
 271 
 272   HeapWord* allocate(size_t word_size, bool is_tlab);
 273   HeapWord* allocate_from_space(size_t word_size);
 274 
 275   HeapWord* par_allocate(size_t word_size, bool is_tlab);
 276 
 277   virtual void gc_epilogue(bool full);
 278 
 279   // Save the tops for eden, from, and to
 280   virtual void record_spaces_top();
 281 
 282   // Accessing marks
 283   void save_marks();
 284   void reset_saved_marks();
 285   bool no_allocs_since_save_marks();
 286 
 287   // Need to declare the full complement of closures, whether we'll
 288   // override them or not, or get message from the compiler:
 289   //   oop_since_save_marks_iterate_nv hides virtual function...
 290 #define DefNew_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
 291   void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
 292 
 293   ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DECL)
 294 
 295 #undef DefNew_SINCE_SAVE_MARKS_DECL
 296 
 297   // For non-youngest collection, the DefNewGeneration can contribute
 298   // "to-space".
 299   virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
 300                           size_t max_alloc_words);
 301 
 302   // Reset for contribution of "to-space".
 303   virtual void reset_scratch();
 304 
 305   // GC support
 306   virtual void compute_new_size();
 307 
 308   // Returns true if the collection is likely to be safely
 309   // completed. Even if this method returns true, a collection
 310   // may not be guaranteed to succeed, and the system should be
 311   // able to safely unwind and recover from that failure, albeit
 312   // at some additional cost. Override superclass's implementation.
 313   virtual bool collection_attempt_is_safe();
 314 
 315   virtual void collect(bool   full,
 316                        bool   clear_all_soft_refs,
 317                        size_t size,
 318                        bool   is_tlab);
 319   HeapWord* expand_and_allocate(size_t size,
 320                                 bool is_tlab,
 321                                 bool parallel = false);
 322 
 323   oop copy_to_survivor_space(oop old);
 324   uint tenuring_threshold() { return _tenuring_threshold; }
 325 
 326   // Performance Counter support
 327   void update_counters();
 328 
 329   // Printing
 330   virtual const char* name() const;
 331   virtual const char* short_name() const { return "DefNew"; }
 332 
 333   void print_on(outputStream* st) const;
 334 
 335   void verify();
 336 
 337   bool promo_failure_scan_is_complete() const {
 338     return _promo_failure_scan_stack.is_empty();
 339   }
 340 
 341  protected:
 342   // If clear_space is true, clear the survivor spaces.  Eden is
 343   // cleared if the minimum size of eden is 0.  If mangle_space
 344   // is true, also mangle the space in debug mode.
 345   void compute_space_boundaries(uintx minimum_eden_size,
 346                                 bool clear_space,
 347                                 bool mangle_space);
 348 
 349   // Return adjusted new size for NewSizeThreadIncrease.
 350   // If any overflow happens, revert to previous new size.
 351   size_t adjust_for_thread_increase(size_t new_size_candidate,
 352                                     size_t new_size_before,
 353                                     size_t alignment) const;
 354 
 355 
 356   // Scavenge support
 357   void swap_spaces();
 358 };
 359 
 360 #endif // SHARE_VM_GC_SERIAL_DEFNEWGENERATION_HPP