1 #ifdef USE_PRAGMA_IDENT_HDR 2 #pragma ident "@(#)defNewGeneration.hpp 1.40 07/05/17 15:54:44 JVM" 3 #endif 4 /* 5 * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved. 6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 7 * 8 * This code is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License version 2 only, as 10 * published by the Free Software Foundation. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 23 * CA 95054 USA or visit www.sun.com if you need additional information or 24 * have any questions. 25 * 26 */ 27 28 class EdenSpace; 29 class ContiguousSpace; 30 class ScanClosure; 31 32 // DefNewGeneration is a young generation containing eden, from- and 33 // to-space. 34 35 class DefNewGeneration: public Generation { 36 friend class VMStructs; 37 38 protected: 39 Generation* _next_gen; 40 int _tenuring_threshold; // Tenuring threshold for next collection. 41 ageTable _age_table; 42 // Size of object to pretenure in words; command line provides bytes 43 size_t _pretenure_size_threshold_words; 44 45 ageTable* age_table() { return &_age_table; } 46 // Initialize state to optimistically assume no promotion failure will 47 // happen. 48 void init_assuming_no_promotion_failure(); 49 // True iff a promotion has failed in the current collection. 50 bool _promotion_failed; 51 bool promotion_failed() { return _promotion_failed; } 52 53 // Handling promotion failure. A young generation collection 54 // can fail if a live object cannot be copied out of its 55 // location in eden or from-space during the collection. If 56 // a collection fails, the young generation is left in a 57 // consistent state such that it can be collected by a 58 // full collection. 59 // Before the collection 60 // Objects are in eden or from-space 61 // All roots into the young generation point into eden or from-space. 62 // 63 // After a failed collection 64 // Objects may be in eden, from-space, or to-space 65 // An object A in eden or from-space may have a copy B 66 // in to-space. If B exists, all roots that once pointed 67 // to A must now point to B. 68 // All objects in the young generation are unmarked. 69 // Eden, from-space, and to-space will all be collected by 70 // the full collection. 71 void handle_promotion_failure(oop); 72 73 // In the absence of promotion failure, we wouldn't look at "from-space" 74 // objects after a young-gen collection. When promotion fails, however, 75 // the subsequent full collection will look at from-space objects: 76 // therefore we must remove their forwarding pointers. 77 void remove_forwarding_pointers(); 78 79 // Preserve the mark of "obj", if necessary, in preparation for its mark 80 // word being overwritten with a self-forwarding-pointer. 81 void preserve_mark_if_necessary(oop obj, markOop m); 82 83 // When one is non-null, so is the other. Together, they each pair is 84 // an object with a preserved mark, and its mark value. 85 GrowableArray<oop>* _objs_with_preserved_marks; 86 GrowableArray<markOop>* _preserved_marks_of_objs; 87 88 // Returns true if the collection can be safely attempted. 89 // If this method returns false, a collection is not 90 // guaranteed to fail but the system may not be able 91 // to recover from the failure. 92 bool collection_attempt_is_safe(); 93 94 // Promotion failure handling 95 OopClosure *_promo_failure_scan_stack_closure; 96 void set_promo_failure_scan_stack_closure(OopClosure *scan_stack_closure) { 97 _promo_failure_scan_stack_closure = scan_stack_closure; 98 } 99 100 GrowableArray<oop>* _promo_failure_scan_stack; 101 GrowableArray<oop>* promo_failure_scan_stack() const { 102 return _promo_failure_scan_stack; 103 } 104 void push_on_promo_failure_scan_stack(oop); 105 void drain_promo_failure_scan_stack(void); 106 bool _promo_failure_drain_in_progress; 107 108 // Performance Counters 109 GenerationCounters* _gen_counters; 110 CSpaceCounters* _eden_counters; 111 CSpaceCounters* _from_counters; 112 CSpaceCounters* _to_counters; 113 114 // sizing information 115 size_t _max_eden_size; 116 size_t _max_survivor_size; 117 118 // Allocation support 119 bool _should_allocate_from_space; 120 bool should_allocate_from_space() const { 121 return _should_allocate_from_space; 122 } 123 void clear_should_allocate_from_space() { 124 _should_allocate_from_space = false; 125 } 126 void set_should_allocate_from_space() { 127 _should_allocate_from_space = true; 128 } 129 130 protected: 131 // Spaces 132 EdenSpace* _eden_space; 133 ContiguousSpace* _from_space; 134 ContiguousSpace* _to_space; 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_size_down(n, alignment) : alignment; 147 } 148 149 public: // was "protected" but caused compile error on win32 150 class IsAliveClosure: public BoolObjectClosure { 151 Generation* _g; 152 public: 153 IsAliveClosure(Generation* g); 154 void do_object(oop p); 155 bool do_object_b(oop p); 156 }; 157 158 class KeepAliveClosure: public OopClosure { 159 protected: 160 ScanWeakRefClosure* _cl; 161 CardTableRS* _rs; 162 template <class T> void do_oop_work(T* p); 163 public: 164 KeepAliveClosure(ScanWeakRefClosure* cl); 165 virtual void do_oop(oop* p); 166 virtual void do_oop(narrowOop* p); 167 }; 168 169 class FastKeepAliveClosure: public KeepAliveClosure { 170 protected: 171 HeapWord* _boundary; 172 template <class T> void do_oop_work(T* p); 173 public: 174 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl); 175 virtual void do_oop(oop* p); 176 virtual void do_oop(narrowOop* p); 177 }; 178 179 class EvacuateFollowersClosure: public VoidClosure { 180 GenCollectedHeap* _gch; 181 int _level; 182 ScanClosure* _scan_cur_or_nonheap; 183 ScanClosure* _scan_older; 184 public: 185 EvacuateFollowersClosure(GenCollectedHeap* gch, int level, 186 ScanClosure* cur, ScanClosure* older); 187 void do_void(); 188 }; 189 190 class FastEvacuateFollowersClosure; 191 friend class FastEvacuateFollowersClosure; 192 class FastEvacuateFollowersClosure: public VoidClosure { 193 GenCollectedHeap* _gch; 194 int _level; 195 DefNewGeneration* _gen; 196 FastScanClosure* _scan_cur_or_nonheap; 197 FastScanClosure* _scan_older; 198 public: 199 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level, 200 DefNewGeneration* gen, 201 FastScanClosure* cur, 202 FastScanClosure* older); 203 void do_void(); 204 }; 205 206 public: 207 DefNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level, 208 const char* policy="Copy"); 209 210 virtual Generation::Name kind() { return Generation::DefNew; } 211 212 // Accessing spaces 213 EdenSpace* eden() const { return _eden_space; } 214 ContiguousSpace* from() const { return _from_space; } 215 ContiguousSpace* to() const { return _to_space; } 216 217 virtual CompactibleSpace* first_compaction_space() const; 218 219 // Space enquiries 220 size_t capacity() const; 221 size_t used() const; 222 size_t free() const; 223 size_t max_capacity() const; 224 size_t capacity_before_gc() const; 225 size_t unsafe_max_alloc_nogc() const; 226 size_t contiguous_available() const; 227 228 size_t max_eden_size() const { return _max_eden_size; } 229 size_t max_survivor_size() const { return _max_survivor_size; } 230 231 bool supports_inline_contig_alloc() const { return true; } 232 HeapWord** top_addr() const; 233 HeapWord** end_addr() const; 234 235 // Thread-local allocation buffers 236 bool supports_tlab_allocation() const { return true; } 237 size_t tlab_capacity() 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 void object_iterate_since_last_GC(ObjectClosure* cl); 252 253 void younger_refs_iterate(OopsInGenClosure* cl); 254 255 void space_iterate(SpaceClosure* blk, bool usedOnly = false); 256 257 // Allocation support 258 virtual bool should_allocate(size_t word_size, bool is_tlab) { 259 assert(UseTLAB || !is_tlab, "Should not allocate tlab"); 260 261 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize); 262 263 const bool non_zero = word_size > 0; 264 const bool overflows = word_size >= overflow_limit; 265 const bool check_too_big = _pretenure_size_threshold_words > 0; 266 const bool not_too_big = word_size < _pretenure_size_threshold_words; 267 const bool size_ok = is_tlab || !check_too_big || not_too_big; 268 269 bool result = !overflows && 270 non_zero && 271 size_ok; 272 273 return result; 274 } 275 276 HeapWord* allocate(size_t word_size, bool is_tlab); 277 HeapWord* allocate_from_space(size_t word_size); 278 279 HeapWord* par_allocate(size_t word_size, bool is_tlab); 280 281 // Prologue & Epilogue 282 virtual void gc_prologue(bool full); 283 virtual void gc_epilogue(bool full); 284 285 // Save the tops for eden, from, and to 286 virtual void record_spaces_top(); 287 288 // Doesn't require additional work during GC prologue and epilogue 289 virtual bool performs_in_place_marking() const { return false; } 290 291 // Accessing marks 292 void save_marks(); 293 void reset_saved_marks(); 294 bool no_allocs_since_save_marks(); 295 296 // Need to declare the full complement of closures, whether we'll 297 // override them or not, or get message from the compiler: 298 // oop_since_save_marks_iterate_nv hides virtual function... 299 #define DefNew_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ 300 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); 301 302 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DECL) 303 304 #undef DefNew_SINCE_SAVE_MARKS_DECL 305 306 // For non-youngest collection, the DefNewGeneration can contribute 307 // "to-space". 308 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor, 309 size_t max_alloc_words); 310 311 // Reset for contribution of "to-space". 312 virtual void reset_scratch(); 313 314 // GC support 315 virtual void compute_new_size(); 316 virtual void collect(bool full, 317 bool clear_all_soft_refs, 318 size_t size, 319 bool is_tlab); 320 HeapWord* expand_and_allocate(size_t size, 321 bool is_tlab, 322 bool parallel = false); 323 324 oop copy_to_survivor_space(oop old); 325 int tenuring_threshold() { return _tenuring_threshold; } 326 327 // Performance Counter support 328 void update_counters(); 329 330 // Printing 331 virtual const char* name() const; 332 virtual const char* short_name() const { return "DefNew"; } 333 334 bool must_be_youngest() const { return true; } 335 bool must_be_oldest() const { return false; } 336 337 // PrintHeapAtGC support. 338 void print_on(outputStream* st) const; 339 340 void verify(bool allow_dirty); 341 342 protected: 343 // If clear_space is true, clear the survivor spaces. Eden is 344 // cleared if the minimum size of eden is 0. If mangle_space 345 // is true, also mangle the space in debug mode. 346 void compute_space_boundaries(uintx minimum_eden_size, 347 bool clear_space, 348 bool mangle_space); 349 // Scavenge support 350 void swap_spaces(); 351 };