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