1 /* 2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 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. 8 * 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). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 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 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_MEMORY_DEFNEWGENERATION_HPP 26 #define SHARE_VM_MEMORY_DEFNEWGENERATION_HPP 27 28 #include "gc_implementation/shared/ageTable.hpp" 29 #include "gc_implementation/shared/cSpaceCounters.hpp" 30 #include "gc_implementation/shared/generationCounters.hpp" 31 #include "memory/generation.inline.hpp" 32 #include "utilities/stack.hpp" 33 34 class EdenSpace; 35 class ContiguousSpace; 36 class ScanClosure; 37 38 // DefNewGeneration is a young generation containing eden, from- and 39 // to-space. 40 41 class DefNewGeneration: public Generation { 42 friend class VMStructs; 43 44 protected: 45 Generation* _next_gen; 46 uint _tenuring_threshold; // Tenuring threshold for next collection. 47 ageTable _age_table; 48 // Size of object to pretenure in words; command line provides bytes 49 size_t _pretenure_size_threshold_words; 50 51 ageTable* age_table() { return &_age_table; } 52 // Initialize state to optimistically assume no promotion failure will 53 // happen. 54 void init_assuming_no_promotion_failure(); 55 // True iff a promotion has failed in the current collection. 56 bool _promotion_failed; 57 bool promotion_failed() { return _promotion_failed; } 58 59 // Handling promotion failure. A young generation collection 60 // can fail if a live object cannot be copied out of its 61 // location in eden or from-space during the collection. If 62 // a collection fails, the young generation is left in a 63 // consistent state such that it can be collected by a 64 // full collection. 65 // Before the collection 66 // Objects are in eden or from-space 67 // All roots into the young generation point into eden or from-space. 68 // 69 // After a failed collection 70 // Objects may be in eden, from-space, or to-space 71 // An object A in eden or from-space may have a copy B 72 // in to-space. If B exists, all roots that once pointed 73 // to A must now point to B. 74 // All objects in the young generation are unmarked. 75 // Eden, from-space, and to-space will all be collected by 76 // the full collection. 77 void handle_promotion_failure(oop); 78 79 // In the absence of promotion failure, we wouldn't look at "from-space" 80 // objects after a young-gen collection. When promotion fails, however, 81 // the subsequent full collection will look at from-space objects: 82 // therefore we must remove their forwarding pointers. 83 void remove_forwarding_pointers(); 84 85 // Preserve the mark of "obj", if necessary, in preparation for its mark 86 // word being overwritten with a self-forwarding-pointer. 87 void preserve_mark_if_necessary(oop obj, markOop m); 88 void preserve_mark(oop obj, markOop m); // work routine used by the above 89 90 // Together, these keep <object with a preserved mark, mark value> pairs. 91 // They should always contain the same number of elements. 92 Stack<oop, mtGC> _objs_with_preserved_marks; 93 Stack<markOop, mtGC> _preserved_marks_of_objs; 94 95 // Promotion failure handling 96 ExtendedOopClosure *_promo_failure_scan_stack_closure; 97 void set_promo_failure_scan_stack_closure(ExtendedOopClosure *scan_stack_closure) { 98 _promo_failure_scan_stack_closure = scan_stack_closure; 99 } 100 101 Stack<oop, mtGC> _promo_failure_scan_stack; 102 void drain_promo_failure_scan_stack(void); 103 bool _promo_failure_drain_in_progress; 104 105 // Performance Counters 106 GenerationCounters* _gen_counters; 107 CSpaceCounters* _eden_counters; 108 CSpaceCounters* _from_counters; 109 CSpaceCounters* _to_counters; 110 111 // sizing information 112 size_t _max_eden_size; 113 size_t _max_survivor_size; 114 115 // Allocation support 116 bool _should_allocate_from_space; 117 bool should_allocate_from_space() const { 118 return _should_allocate_from_space; 119 } 120 void clear_should_allocate_from_space() { 121 _should_allocate_from_space = false; 122 } 123 void set_should_allocate_from_space() { 124 _should_allocate_from_space = true; 125 } 126 127 // Tenuring 128 void adjust_desired_tenuring_threshold(); 129 130 // Spaces 131 EdenSpace* _eden_space; 132 ContiguousSpace* _from_space; 133 ContiguousSpace* _to_space; 134 135 enum SomeProtectedConstants { 136 // Generations are GenGrain-aligned and have size that are multiples of 137 // GenGrain. 138 MinFreeScratchWords = 100 139 }; 140 141 // Return the size of a survivor space if this generation were of size 142 // gen_size. 143 size_t compute_survivor_size(size_t gen_size, size_t alignment) const { 144 size_t n = gen_size / (SurvivorRatio + 2); 145 return n > alignment ? align_size_down(n, alignment) : alignment; 146 } 147 148 public: // was "protected" but caused compile error on win32 149 class IsAliveClosure: public BoolObjectClosure { 150 Generation* _g; 151 public: 152 IsAliveClosure(Generation* g); 153 bool do_object_b(oop p); 154 }; 155 156 class KeepAliveClosure: public OopClosure { 157 protected: 158 ScanWeakRefClosure* _cl; 159 CardTableRS* _rs; 160 template <class T> void do_oop_work(T* p); 161 public: 162 KeepAliveClosure(ScanWeakRefClosure* cl); 163 virtual void do_oop(oop* p); 164 virtual void do_oop(narrowOop* p); 165 }; 166 167 class FastKeepAliveClosure: public KeepAliveClosure { 168 protected: 169 HeapWord* _boundary; 170 template <class T> void do_oop_work(T* p); 171 public: 172 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl); 173 virtual void do_oop(oop* p); 174 virtual void do_oop(narrowOop* p); 175 }; 176 177 class EvacuateFollowersClosure: public VoidClosure { 178 GenCollectedHeap* _gch; 179 int _level; 180 ScanClosure* _scan_cur_or_nonheap; 181 ScanClosure* _scan_older; 182 public: 183 EvacuateFollowersClosure(GenCollectedHeap* gch, int level, 184 ScanClosure* cur, ScanClosure* older); 185 void do_void(); 186 }; 187 188 class FastEvacuateFollowersClosure: public VoidClosure { 189 GenCollectedHeap* _gch; 190 int _level; 191 DefNewGeneration* _gen; 192 FastScanClosure* _scan_cur_or_nonheap; 193 FastScanClosure* _scan_older; 194 public: 195 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level, 196 DefNewGeneration* gen, 197 FastScanClosure* cur, 198 FastScanClosure* older); 199 void do_void(); 200 }; 201 202 public: 203 DefNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level, 204 const char* policy="Copy"); 205 206 virtual Generation::Name kind() { return Generation::DefNew; } 207 208 // Accessing spaces 209 EdenSpace* 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** 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 unsafe_max_tlab_alloc() const; 235 236 // Grow the generation by the specified number of bytes. 237 // The size of bytes is assumed to be properly aligned. 238 // Return true if the expansion was successful. 239 bool expand(size_t bytes); 240 241 // DefNewGeneration cannot currently expand except at 242 // a GC. 243 virtual bool is_maximal_no_gc() const { return true; } 244 245 // Iteration 246 void object_iterate(ObjectClosure* blk); 247 void object_iterate_since_last_GC(ObjectClosure* cl); 248 249 void younger_refs_iterate(OopsInGenClosure* cl); 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 // Prologue & Epilogue 278 virtual void gc_prologue(bool full); 279 virtual void gc_epilogue(bool full); 280 281 // Save the tops for eden, from, and to 282 virtual void record_spaces_top(); 283 284 // Doesn't require additional work during GC prologue and epilogue 285 virtual bool performs_in_place_marking() const { return false; } 286 287 // Accessing marks 288 void save_marks(); 289 void reset_saved_marks(); 290 bool no_allocs_since_save_marks(); 291 292 // Need to declare the full complement of closures, whether we'll 293 // override them or not, or get message from the compiler: 294 // oop_since_save_marks_iterate_nv hides virtual function... 295 #define DefNew_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ 296 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); 297 298 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DECL) 299 300 #undef DefNew_SINCE_SAVE_MARKS_DECL 301 302 // For non-youngest collection, the DefNewGeneration can contribute 303 // "to-space". 304 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor, 305 size_t max_alloc_words); 306 307 // Reset for contribution of "to-space". 308 virtual void reset_scratch(); 309 310 // GC support 311 virtual void compute_new_size(); 312 313 // Returns true if the collection is likely to be safely 314 // completed. Even if this method returns true, a collection 315 // may not be guaranteed to succeed, and the system should be 316 // able to safely unwind and recover from that failure, albeit 317 // at some additional cost. Override superclass's implementation. 318 virtual bool collection_attempt_is_safe(); 319 320 virtual void collect(bool full, 321 bool clear_all_soft_refs, 322 size_t size, 323 bool is_tlab); 324 HeapWord* expand_and_allocate(size_t size, 325 bool is_tlab, 326 bool parallel = false); 327 328 oop copy_to_survivor_space(oop old); 329 uint tenuring_threshold() { return _tenuring_threshold; } 330 331 // Performance Counter support 332 void update_counters(); 333 334 // Printing 335 virtual const char* name() const; 336 virtual const char* short_name() const { return "DefNew"; } 337 338 bool must_be_youngest() const { return true; } 339 bool must_be_oldest() const { return false; } 340 341 // PrintHeapAtGC support. 342 void print_on(outputStream* st) const; 343 344 void verify(); 345 346 bool promo_failure_scan_is_complete() const { 347 return _promo_failure_scan_stack.is_empty(); 348 } 349 350 protected: 351 // If clear_space is true, clear the survivor spaces. Eden is 352 // cleared if the minimum size of eden is 0. If mangle_space 353 // is true, also mangle the space in debug mode. 354 void compute_space_boundaries(uintx minimum_eden_size, 355 bool clear_space, 356 bool mangle_space); 357 // Scavenge support 358 void swap_spaces(); 359 }; 360 361 #endif // SHARE_VM_MEMORY_DEFNEWGENERATION_HPP