1 /* 2 * Copyright (c) 2001, 2017, 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_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, GCMemoryManager* mem_mgr, 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