1 /* 2 * Copyright (c) 2001, 2015, 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 "gc_implementation/shared/copyFailedInfo.hpp" 32 #include "memory/generation.hpp" 33 #include "utilities/stack.hpp" 34 35 class ContiguousSpace; 36 class ScanClosure; 37 class STWGCTimer; 38 class CSpaceCounters; 39 class ScanWeakRefClosure; 40 41 // DefNewGeneration is a young generation containing eden, from- and 42 // to-space. 43 44 class DefNewGeneration: public Generation { 45 friend class VMStructs; 46 47 protected: 48 Generation* _old_gen; 49 uint _tenuring_threshold; // Tenuring threshold for next collection. 50 ageTable _age_table; 51 // Size of object to pretenure in words; command line provides bytes 52 size_t _pretenure_size_threshold_words; 53 54 ageTable* age_table() { return &_age_table; } 55 56 // Initialize state to optimistically assume no promotion failure will 57 // happen. 58 void init_assuming_no_promotion_failure(); 59 // True iff a promotion has failed in the current collection. 60 bool _promotion_failed; 61 bool promotion_failed() { return _promotion_failed; } 62 PromotionFailedInfo _promotion_failed_info; 63 64 // Handling promotion failure. A young generation collection 65 // can fail if a live object cannot be copied out of its 66 // location in eden or from-space during the collection. If 67 // a collection fails, the young generation is left in a 68 // consistent state such that it can be collected by a 69 // full collection. 70 // Before the collection 71 // Objects are in eden or from-space 72 // All roots into the young generation point into eden or from-space. 73 // 74 // After a failed collection 75 // Objects may be in eden, from-space, or to-space 76 // An object A in eden or from-space may have a copy B 77 // in to-space. If B exists, all roots that once pointed 78 // to A must now point to B. 79 // All objects in the young generation are unmarked. 80 // Eden, from-space, and to-space will all be collected by 81 // the full collection. 82 void handle_promotion_failure(oop); 83 84 // In the absence of promotion failure, we wouldn't look at "from-space" 85 // objects after a young-gen collection. When promotion fails, however, 86 // the subsequent full collection will look at from-space objects: 87 // therefore we must remove their forwarding pointers. 88 void remove_forwarding_pointers(); 89 90 // Preserve the mark of "obj", if necessary, in preparation for its mark 91 // word being overwritten with a self-forwarding-pointer. 92 void preserve_mark_if_necessary(oop obj, markOop m); 93 void preserve_mark(oop obj, markOop m); // work routine used by the above 94 95 // Together, these keep <object with a preserved mark, mark value> pairs. 96 // They should always contain the same number of elements. 97 Stack<oop, mtGC> _objs_with_preserved_marks; 98 Stack<markOop, mtGC> _preserved_marks_of_objs; 99 100 // Promotion failure handling 101 ExtendedOopClosure *_promo_failure_scan_stack_closure; 102 void set_promo_failure_scan_stack_closure(ExtendedOopClosure *scan_stack_closure) { 103 _promo_failure_scan_stack_closure = scan_stack_closure; 104 } 105 106 Stack<oop, mtGC> _promo_failure_scan_stack; 107 void drain_promo_failure_scan_stack(void); 108 bool _promo_failure_drain_in_progress; 109 110 // Performance Counters 111 GenerationCounters* _gen_counters; 112 CSpaceCounters* _eden_counters; 113 CSpaceCounters* _from_counters; 114 CSpaceCounters* _to_counters; 115 116 // sizing information 117 size_t _max_eden_size; 118 size_t _max_survivor_size; 119 120 // Allocation support 121 bool _should_allocate_from_space; 122 bool should_allocate_from_space() const { 123 return _should_allocate_from_space; 124 } 125 void clear_should_allocate_from_space() { 126 _should_allocate_from_space = false; 127 } 128 void set_should_allocate_from_space() { 129 _should_allocate_from_space = true; 130 } 131 132 // Tenuring 133 void adjust_desired_tenuring_threshold(); 134 135 // Spaces 136 ContiguousSpace* _eden_space; 137 ContiguousSpace* _from_space; 138 ContiguousSpace* _to_space; 139 140 STWGCTimer* _gc_timer; 141 142 enum SomeProtectedConstants { 143 // Generations are GenGrain-aligned and have size that are multiples of 144 // GenGrain. 145 MinFreeScratchWords = 100 146 }; 147 148 // Return the size of a survivor space if this generation were of size 149 // gen_size. 150 size_t compute_survivor_size(size_t gen_size, size_t alignment) const { 151 size_t n = gen_size / (SurvivorRatio + 2); 152 return n > alignment ? align_size_down(n, alignment) : alignment; 153 } 154 155 public: // was "protected" but caused compile error on win32 156 class IsAliveClosure: public BoolObjectClosure { 157 Generation* _g; 158 public: 159 IsAliveClosure(Generation* g); 160 bool do_object_b(oop p); 161 }; 162 163 class KeepAliveClosure: public OopClosure { 164 protected: 165 ScanWeakRefClosure* _cl; 166 CardTableRS* _rs; 167 template <class T> void do_oop_work(T* p); 168 public: 169 KeepAliveClosure(ScanWeakRefClosure* cl); 170 virtual void do_oop(oop* p); 171 virtual void do_oop(narrowOop* p); 172 }; 173 174 class FastKeepAliveClosure: public KeepAliveClosure { 175 protected: 176 HeapWord* _boundary; 177 template <class T> void do_oop_work(T* p); 178 public: 179 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl); 180 virtual void do_oop(oop* p); 181 virtual void do_oop(narrowOop* p); 182 }; 183 184 class EvacuateFollowersClosure: public VoidClosure { 185 GenCollectedHeap* _gch; 186 int _level; 187 ScanClosure* _scan_cur_or_nonheap; 188 ScanClosure* _scan_older; 189 public: 190 EvacuateFollowersClosure(GenCollectedHeap* gch, int level, 191 ScanClosure* cur, ScanClosure* older); 192 void do_void(); 193 }; 194 195 class FastEvacuateFollowersClosure: public VoidClosure { 196 GenCollectedHeap* _gch; 197 int _level; 198 DefNewGeneration* _gen; 199 FastScanClosure* _scan_cur_or_nonheap; 200 FastScanClosure* _scan_older; 201 public: 202 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level, 203 DefNewGeneration* gen, 204 FastScanClosure* cur, 205 FastScanClosure* older); 206 void do_void(); 207 }; 208 209 public: 210 DefNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level, 211 const char* policy="Copy"); 212 213 virtual void ref_processor_init(); 214 215 virtual Generation::Name kind() { return Generation::DefNew; } 216 217 // Accessing spaces 218 ContiguousSpace* eden() const { return _eden_space; } 219 ContiguousSpace* from() const { return _from_space; } 220 ContiguousSpace* to() const { return _to_space; } 221 222 virtual CompactibleSpace* first_compaction_space() const; 223 224 // Space enquiries 225 size_t capacity() const; 226 size_t used() const; 227 size_t free() const; 228 size_t max_capacity() const; 229 size_t capacity_before_gc() const; 230 size_t unsafe_max_alloc_nogc() const; 231 size_t contiguous_available() const; 232 233 size_t max_eden_size() const { return _max_eden_size; } 234 size_t max_survivor_size() const { return _max_survivor_size; } 235 236 bool supports_inline_contig_alloc() const { return true; } 237 HeapWord** top_addr() const; 238 HeapWord** end_addr() const; 239 240 // Thread-local allocation buffers 241 bool supports_tlab_allocation() const { return true; } 242 size_t tlab_capacity() const; 243 size_t tlab_used() const; 244 size_t unsafe_max_tlab_alloc() const; 245 246 // Grow the generation by the specified number of bytes. 247 // The size of bytes is assumed to be properly aligned. 248 // Return true if the expansion was successful. 249 bool expand(size_t bytes); 250 251 // DefNewGeneration cannot currently expand except at 252 // a GC. 253 virtual bool is_maximal_no_gc() const { return true; } 254 255 // Iteration 256 void object_iterate(ObjectClosure* blk); 257 258 void younger_refs_iterate(OopsInGenClosure* cl); 259 260 void space_iterate(SpaceClosure* blk, bool usedOnly = false); 261 262 // Allocation support 263 virtual bool should_allocate(size_t word_size, bool is_tlab) { 264 assert(UseTLAB || !is_tlab, "Should not allocate tlab"); 265 266 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize); 267 268 const bool non_zero = word_size > 0; 269 const bool overflows = word_size >= overflow_limit; 270 const bool check_too_big = _pretenure_size_threshold_words > 0; 271 const bool not_too_big = word_size < _pretenure_size_threshold_words; 272 const bool size_ok = is_tlab || !check_too_big || not_too_big; 273 274 bool result = !overflows && 275 non_zero && 276 size_ok; 277 278 return result; 279 } 280 281 HeapWord* allocate(size_t word_size, bool is_tlab); 282 HeapWord* allocate_from_space(size_t word_size); 283 284 HeapWord* par_allocate(size_t word_size, bool is_tlab); 285 286 virtual void gc_epilogue(bool full); 287 288 // Save the tops for eden, from, and to 289 virtual void record_spaces_top(); 290 291 // Doesn't require additional work during GC prologue and epilogue 292 virtual bool performs_in_place_marking() const { return false; } 293 294 // Accessing marks 295 void save_marks(); 296 void reset_saved_marks(); 297 bool no_allocs_since_save_marks(); 298 299 // Need to declare the full complement of closures, whether we'll 300 // override them or not, or get message from the compiler: 301 // oop_since_save_marks_iterate_nv hides virtual function... 302 #define DefNew_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ 303 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); 304 305 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DECL) 306 307 #undef DefNew_SINCE_SAVE_MARKS_DECL 308 309 // For non-youngest collection, the DefNewGeneration can contribute 310 // "to-space". 311 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor, 312 size_t max_alloc_words); 313 314 // Reset for contribution of "to-space". 315 virtual void reset_scratch(); 316 317 // GC support 318 virtual void compute_new_size(); 319 320 // Returns true if the collection is likely to be safely 321 // completed. Even if this method returns true, a collection 322 // may not be guaranteed to succeed, and the system should be 323 // able to safely unwind and recover from that failure, albeit 324 // at some additional cost. Override superclass's implementation. 325 virtual bool collection_attempt_is_safe(); 326 327 virtual void collect(bool full, 328 bool clear_all_soft_refs, 329 size_t size, 330 bool is_tlab); 331 HeapWord* expand_and_allocate(size_t size, 332 bool is_tlab, 333 bool parallel = false); 334 335 oop copy_to_survivor_space(oop old); 336 uint tenuring_threshold() { return _tenuring_threshold; } 337 338 // Performance Counter support 339 void update_counters(); 340 341 // Printing 342 virtual const char* name() const; 343 virtual const char* short_name() const { return "DefNew"; } 344 345 // PrintHeapAtGC support. 346 void print_on(outputStream* st) const; 347 348 void verify(); 349 350 bool promo_failure_scan_is_complete() const { 351 return _promo_failure_scan_stack.is_empty(); 352 } 353 354 protected: 355 // If clear_space is true, clear the survivor spaces. Eden is 356 // cleared if the minimum size of eden is 0. If mangle_space 357 // is true, also mangle the space in debug mode. 358 void compute_space_boundaries(uintx minimum_eden_size, 359 bool clear_space, 360 bool mangle_space); 361 // Scavenge support 362 void swap_spaces(); 363 }; 364 365 #endif // SHARE_VM_MEMORY_DEFNEWGENERATION_HPP