1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   5  * This code is free software; you can redistribute it and/or modify it
   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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   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  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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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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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/align.hpp"
  35 #include "utilities/stack.hpp"
  36 
  37 class ContiguousSpace;
  38 class ScanClosure;
  39 class STWGCTimer;
  40 class CSpaceCounters;
  41 class ScanWeakRefClosure;
  42 
  43 // DefNewGeneration is a young generation containing eden, from- and
  44 // to-space.
  45 
  46 class DefNewGeneration: public Generation {
  47   friend class VMStructs;
  48 
  49 protected:
  50   Generation* _old_gen;
  51   uint        _tenuring_threshold;   // Tenuring threshold for next collection.
  52   AgeTable    _age_table;
  53   // Size of object to pretenure in words; command line provides bytes
  54   size_t      _pretenure_size_threshold_words;
  55 
  56   AgeTable*   age_table() { return &_age_table; }
  57 
  58   // Initialize state to optimistically assume no promotion failure will
  59   // happen.
  60   void   init_assuming_no_promotion_failure();
  61   // True iff a promotion has failed in the current collection.
  62   bool   _promotion_failed;
  63   bool   promotion_failed() { return _promotion_failed; }
  64   PromotionFailedInfo _promotion_failed_info;
  65 
  66   // Handling promotion failure.  A young generation collection
  67   // can fail if a live object cannot be copied out of its
  68   // location in eden or from-space during the collection.  If
  69   // a collection fails, the young generation is left in a
  70   // consistent state such that it can be collected by a
  71   // full collection.
  72   //   Before the collection
  73   //     Objects are in eden or from-space
  74   //     All roots into the young generation point into eden or from-space.
  75   //
  76   //   After a failed collection
  77   //     Objects may be in eden, from-space, or to-space
  78   //     An object A in eden or from-space may have a copy B
  79   //       in to-space.  If B exists, all roots that once pointed
  80   //       to A must now point to B.
  81   //     All objects in the young generation are unmarked.
  82   //     Eden, from-space, and to-space will all be collected by
  83   //       the full collection.
  84   void handle_promotion_failure(oop);
  85 
  86   // In the absence of promotion failure, we wouldn't look at "from-space"
  87   // objects after a young-gen collection.  When promotion fails, however,
  88   // the subsequent full collection will look at from-space objects:
  89   // therefore we must remove their forwarding pointers.
  90   void remove_forwarding_pointers();
  91 
  92   virtual void restore_preserved_marks();
  93 
  94   // Preserved marks
  95   PreservedMarksSet _preserved_marks_set;
  96 
  97   // Promotion failure handling
  98   ExtendedOopClosure *_promo_failure_scan_stack_closure;
  99   void set_promo_failure_scan_stack_closure(ExtendedOopClosure *scan_stack_closure) {
 100     _promo_failure_scan_stack_closure = scan_stack_closure;
 101   }
 102 
 103   Stack<oop, mtGC> _promo_failure_scan_stack;
 104   void drain_promo_failure_scan_stack(void);
 105   bool _promo_failure_drain_in_progress;
 106 
 107   // Performance Counters
 108   GenerationCounters*  _gen_counters;
 109   CSpaceCounters*      _eden_counters;
 110   CSpaceCounters*      _from_counters;
 111   CSpaceCounters*      _to_counters;
 112 
 113   // sizing information
 114   size_t               _max_eden_size;
 115   size_t               _max_survivor_size;
 116 
 117   // Allocation support
 118   bool _should_allocate_from_space;
 119   bool should_allocate_from_space() const {
 120     return _should_allocate_from_space;
 121   }
 122   void clear_should_allocate_from_space() {
 123     _should_allocate_from_space = false;
 124   }
 125   void set_should_allocate_from_space() {
 126     _should_allocate_from_space = true;
 127   }
 128 
 129   // Tenuring
 130   void adjust_desired_tenuring_threshold();
 131 
 132   // Spaces
 133   ContiguousSpace* _eden_space;
 134   ContiguousSpace* _from_space;
 135   ContiguousSpace* _to_space;
 136 
 137   STWGCTimer* _gc_timer;
 138 
 139   enum SomeProtectedConstants {
 140     // Generations are GenGrain-aligned and have size that are multiples of
 141     // GenGrain.
 142     MinFreeScratchWords = 100
 143   };
 144 
 145   // Return the size of a survivor space if this generation were of size
 146   // gen_size.
 147   size_t compute_survivor_size(size_t gen_size, size_t alignment) const {
 148     size_t n = gen_size / (SurvivorRatio + 2);
 149     return n > alignment ? align_down(n, alignment) : alignment;
 150   }
 151 
 152  public:  // was "protected" but caused compile error on win32
 153   class IsAliveClosure: public BoolObjectClosure {
 154     Generation* _young_gen;
 155   public:
 156     IsAliveClosure(Generation* young_gen);
 157     bool do_object_b(oop p);
 158   };
 159 
 160   class KeepAliveClosure: public OopClosure {
 161   protected:
 162     ScanWeakRefClosure* _cl;
 163     CardTableRS* _rs;
 164     template <class T> void do_oop_work(T* p);
 165   public:
 166     KeepAliveClosure(ScanWeakRefClosure* cl);
 167     virtual void do_oop(oop* p);
 168     virtual void do_oop(narrowOop* p);
 169   };
 170 
 171   class FastKeepAliveClosure: public KeepAliveClosure {
 172   protected:
 173     HeapWord* _boundary;
 174     template <class T> void do_oop_work(T* p);
 175   public:
 176     FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl);
 177     virtual void do_oop(oop* p);
 178     virtual void do_oop(narrowOop* p);
 179   };
 180 
 181   class EvacuateFollowersClosure: public VoidClosure {
 182     GenCollectedHeap* _gch;
 183     ScanClosure* _scan_cur_or_nonheap;
 184     ScanClosure* _scan_older;
 185   public:
 186     EvacuateFollowersClosure(GenCollectedHeap* gch,
 187                              ScanClosure* cur, ScanClosure* older);
 188     void do_void();
 189   };
 190 
 191   class FastEvacuateFollowersClosure: public VoidClosure {
 192     GenCollectedHeap* _gch;
 193     DefNewGeneration* _young_gen;
 194     FastScanClosure* _scan_cur_or_nonheap;
 195     FastScanClosure* _scan_older;
 196   public:
 197     FastEvacuateFollowersClosure(GenCollectedHeap* gch,
 198                                  FastScanClosure* cur,
 199                                  FastScanClosure* older);
 200     void do_void();
 201   };
 202 
 203  public:
 204   DefNewGeneration(ReservedSpace rs, size_t initial_byte_size,
 205                    const char* policy="Copy");
 206 
 207   virtual void ref_processor_init();
 208 
 209   virtual Generation::Name kind() { return Generation::DefNew; }
 210 
 211   // Accessing spaces
 212   ContiguousSpace* eden() const           { return _eden_space; }
 213   ContiguousSpace* from() const           { return _from_space; }
 214   ContiguousSpace* to()   const           { return _to_space;   }
 215 
 216   virtual CompactibleSpace* first_compaction_space() const;
 217 
 218   // Space enquiries
 219   size_t capacity() const;
 220   size_t used() const;
 221   size_t free() const;
 222   size_t max_capacity() const;
 223   size_t capacity_before_gc() const;
 224   size_t unsafe_max_alloc_nogc() const;
 225   size_t contiguous_available() const;
 226 
 227   size_t max_eden_size() const              { return _max_eden_size; }
 228   size_t max_survivor_size() const          { return _max_survivor_size; }
 229 
 230   bool supports_inline_contig_alloc() const { return true; }
 231   HeapWord* volatile* top_addr() const;
 232   HeapWord** end_addr() const;
 233 
 234   // Thread-local allocation buffers
 235   bool supports_tlab_allocation() const { return true; }
 236   size_t tlab_capacity() const;
 237   size_t tlab_used() const;
 238   size_t unsafe_max_tlab_alloc() const;
 239 
 240   // Grow the generation by the specified number of bytes.
 241   // The size of bytes is assumed to be properly aligned.
 242   // Return true if the expansion was successful.
 243   bool expand(size_t bytes);
 244 
 245   // DefNewGeneration cannot currently expand except at
 246   // a GC.
 247   virtual bool is_maximal_no_gc() const { return true; }
 248 
 249   // Iteration
 250   void object_iterate(ObjectClosure* blk);
 251 
 252   void younger_refs_iterate(OopsInGenClosure* cl, uint n_threads);
 253 
 254   void space_iterate(SpaceClosure* blk, bool usedOnly = false);
 255 
 256   // Allocation support
 257   virtual bool should_allocate(size_t word_size, bool is_tlab) {
 258     assert(UseTLAB || !is_tlab, "Should not allocate tlab");
 259 
 260     size_t overflow_limit    = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
 261 
 262     const bool non_zero      = word_size > 0;
 263     const bool overflows     = word_size >= overflow_limit;
 264     const bool check_too_big = _pretenure_size_threshold_words > 0;
 265     const bool not_too_big   = word_size < _pretenure_size_threshold_words;
 266     const bool size_ok       = is_tlab || !check_too_big || not_too_big;
 267 
 268     bool result = !overflows &&
 269                   non_zero   &&
 270                   size_ok;
 271 
 272     return result;
 273   }
 274 
 275   HeapWord* allocate(size_t word_size, bool is_tlab);
 276   HeapWord* allocate_from_space(size_t word_size);
 277 
 278   HeapWord* par_allocate(size_t word_size, bool is_tlab);
 279 
 280   virtual void gc_epilogue(bool full);
 281 
 282   // Save the tops for eden, from, and to
 283   virtual void record_spaces_top();
 284 
 285   // Accessing marks
 286   void save_marks();
 287   void reset_saved_marks();
 288   bool no_allocs_since_save_marks();
 289 
 290   // Need to declare the full complement of closures, whether we'll
 291   // override them or not, or get message from the compiler:
 292   //   oop_since_save_marks_iterate_nv hides virtual function...
 293 #define DefNew_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
 294   void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
 295 
 296   ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DECL)
 297 
 298 #undef DefNew_SINCE_SAVE_MARKS_DECL
 299 
 300   // For non-youngest collection, the DefNewGeneration can contribute
 301   // "to-space".
 302   virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
 303                           size_t max_alloc_words);
 304 
 305   // Reset for contribution of "to-space".
 306   virtual void reset_scratch();
 307 
 308   // GC support
 309   virtual void compute_new_size();
 310 
 311   // Returns true if the collection is likely to be safely
 312   // completed. Even if this method returns true, a collection
 313   // may not be guaranteed to succeed, and the system should be
 314   // able to safely unwind and recover from that failure, albeit
 315   // at some additional cost. Override superclass's implementation.
 316   virtual bool collection_attempt_is_safe();
 317 
 318   virtual void collect(bool   full,
 319                        bool   clear_all_soft_refs,
 320                        size_t size,
 321                        bool   is_tlab);
 322   HeapWord* expand_and_allocate(size_t size,
 323                                 bool is_tlab,
 324                                 bool parallel = false);
 325 
 326   oop copy_to_survivor_space(oop old);
 327   uint tenuring_threshold() { return _tenuring_threshold; }
 328 
 329   // Performance Counter support
 330   void update_counters();
 331 
 332   // Printing
 333   virtual const char* name() const;
 334   virtual const char* short_name() const { return "DefNew"; }
 335 
 336   void print_on(outputStream* st) const;
 337 
 338   void verify();
 339 
 340   bool promo_failure_scan_is_complete() const {
 341     return _promo_failure_scan_stack.is_empty();
 342   }
 343 
 344  protected:
 345   // If clear_space is true, clear the survivor spaces.  Eden is
 346   // cleared if the minimum size of eden is 0.  If mangle_space
 347   // is true, also mangle the space in debug mode.
 348   void compute_space_boundaries(uintx minimum_eden_size,
 349                                 bool clear_space,
 350                                 bool mangle_space);
 351 
 352   // Return adjusted new size for NewSizeThreadIncrease.
 353   // If any overflow happens, revert to previous new size.
 354   size_t adjust_for_thread_increase(size_t new_size_candidate,
 355                                     size_t new_size_before,
 356                                     size_t alignment) const;
 357 
 358 
 359   // Scavenge support
 360   void swap_spaces();
 361 };
 362 
 363 #endif // SHARE_VM_GC_SERIAL_DEFNEWGENERATION_HPP