1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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).
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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.inline.hpp"
33 #include "utilities/stack.hpp"
34
35 class EdenSpace;
36 class ContiguousSpace;
37 class ScanClosure;
38 class STWGCTimer;
39
40 // DefNewGeneration is a young generation containing eden, from- and
41 // to-space.
42
43 class DefNewGeneration: public Generation {
44 friend class VMStructs;
45
46 protected:
47 Generation* _next_gen;
48 uint _tenuring_threshold; // Tenuring threshold for next collection.
49 ageTable _age_table;
50 // Size of object to pretenure in words; command line provides bytes
51 size_t _pretenure_size_threshold_words;
52
53 ageTable* age_table() { return &_age_table; }
54
55 // Initialize state to optimistically assume no promotion failure will
56 // happen.
57 void init_assuming_no_promotion_failure();
58 // True iff a promotion has failed in the current collection.
59 bool _promotion_failed;
60 bool promotion_failed() { return _promotion_failed; }
61 PromotionFailedInfo _promotion_failed_info;
62
63 // Handling promotion failure. A young generation collection
64 // can fail if a live object cannot be copied out of its
65 // location in eden or from-space during the collection. If
66 // a collection fails, the young generation is left in a
67 // consistent state such that it can be collected by a
68 // full collection.
69 // Before the collection
70 // Objects are in eden or from-space
71 // All roots into the young generation point into eden or from-space.
72 //
73 // After a failed collection
74 // Objects may be in eden, from-space, or to-space
75 // An object A in eden or from-space may have a copy B
76 // in to-space. If B exists, all roots that once pointed
77 // to A must now point to B.
78 // All objects in the young generation are unmarked.
79 // Eden, from-space, and to-space will all be collected by
80 // the full collection.
81 void handle_promotion_failure(oop);
82
83 // In the absence of promotion failure, we wouldn't look at "from-space"
84 // objects after a young-gen collection. When promotion fails, however,
85 // the subsequent full collection will look at from-space objects:
86 // therefore we must remove their forwarding pointers.
87 void remove_forwarding_pointers();
88
89 // Preserve the mark of "obj", if necessary, in preparation for its mark
90 // word being overwritten with a self-forwarding-pointer.
91 void preserve_mark_if_necessary(oop obj, markOop m);
92 void preserve_mark(oop obj, markOop m); // work routine used by the above
93
94 // Together, these keep <object with a preserved mark, mark value> pairs.
95 // They should always contain the same number of elements.
96 Stack<oop, mtGC> _objs_with_preserved_marks;
97 Stack<markOop, mtGC> _preserved_marks_of_objs;
98
99 // Promotion failure handling
100 ExtendedOopClosure *_promo_failure_scan_stack_closure;
101 void set_promo_failure_scan_stack_closure(ExtendedOopClosure *scan_stack_closure) {
102 _promo_failure_scan_stack_closure = scan_stack_closure;
103 }
104
105 Stack<oop, mtGC> _promo_failure_scan_stack;
106 void drain_promo_failure_scan_stack(void);
107 bool _promo_failure_drain_in_progress;
108
109 // Performance Counters
110 GenerationCounters* _gen_counters;
111 CSpaceCounters* _eden_counters;
112 CSpaceCounters* _from_counters;
113 CSpaceCounters* _to_counters;
114
115 // sizing information
116 size_t _max_eden_size;
117 size_t _max_survivor_size;
118
119 // Allocation support
120 bool _should_allocate_from_space;
121 bool should_allocate_from_space() const {
122 return _should_allocate_from_space;
123 }
124 void clear_should_allocate_from_space() {
125 _should_allocate_from_space = false;
126 }
127 void set_should_allocate_from_space() {
128 _should_allocate_from_space = true;
129 }
130
131 // Tenuring
132 void adjust_desired_tenuring_threshold();
133
134 // Spaces
135 EdenSpace* _eden_space;
136 ContiguousSpace* _from_space;
137 ContiguousSpace* _to_space;
138
139 STWGCTimer* _gc_timer;
140
141 enum SomeProtectedConstants {
142 // Generations are GenGrain-aligned and have size that are multiples of
143 // GenGrain.
144 MinFreeScratchWords = 100
145 };
146
147 // Return the size of a survivor space if this generation were of size
148 // gen_size.
149 size_t compute_survivor_size(size_t gen_size, size_t alignment) const {
150 size_t n = gen_size / (SurvivorRatio + 2);
151 return n > alignment ? align_size_down(n, alignment) : alignment;
152 }
153
154 public: // was "protected" but caused compile error on win32
155 class IsAliveClosure: public BoolObjectClosure {
156 Generation* _g;
157 public:
158 IsAliveClosure(Generation* g);
159 bool do_object_b(oop p);
160 };
161
162 class KeepAliveClosure: public OopClosure {
163 protected:
164 ScanWeakRefClosure* _cl;
165 CardTableRS* _rs;
166 template <class T> void do_oop_work(T* p);
167 public:
168 KeepAliveClosure(ScanWeakRefClosure* cl);
169 virtual void do_oop(oop* p);
170 virtual void do_oop(narrowOop* p);
171 };
172
173 class FastKeepAliveClosure: public KeepAliveClosure {
174 protected:
175 HeapWord* _boundary;
176 template <class T> void do_oop_work(T* p);
177 public:
178 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl);
179 virtual void do_oop(oop* p);
180 virtual void do_oop(narrowOop* p);
181 };
182
183 class EvacuateFollowersClosure: public VoidClosure {
184 GenCollectedHeap* _gch;
185 int _level;
186 ScanClosure* _scan_cur_or_nonheap;
187 ScanClosure* _scan_older;
188 public:
189 EvacuateFollowersClosure(GenCollectedHeap* gch, int level,
190 ScanClosure* cur, ScanClosure* older);
191 void do_void();
192 };
193
194 class FastEvacuateFollowersClosure: public VoidClosure {
195 GenCollectedHeap* _gch;
196 int _level;
197 DefNewGeneration* _gen;
198 FastScanClosure* _scan_cur_or_nonheap;
199 FastScanClosure* _scan_older;
200 public:
201 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level,
202 DefNewGeneration* gen,
203 FastScanClosure* cur,
204 FastScanClosure* older);
205 void do_void();
206 };
207
208 public:
209 DefNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
210 const char* policy="Copy");
211
212 virtual void ref_processor_init();
213
214 virtual Generation::Name kind() { return Generation::DefNew; }
215
216 // Accessing spaces
217 EdenSpace* eden() const { return _eden_space; }
218 ContiguousSpace* from() const { return _from_space; }
219 ContiguousSpace* to() const { return _to_space; }
220
221 virtual CompactibleSpace* first_compaction_space() const;
222
223 // Space enquiries
224 size_t capacity() const;
225 size_t used() const;
226 size_t free() const;
227 size_t max_capacity() const;
228 size_t capacity_before_gc() const;
229 size_t unsafe_max_alloc_nogc() const;
230 size_t contiguous_available() const;
231
232 size_t max_eden_size() const { return _max_eden_size; }
233 size_t max_survivor_size() const { return _max_survivor_size; }
234
235 bool supports_inline_contig_alloc() const { return true; }
236 HeapWord** top_addr() const;
237 HeapWord** end_addr() const;
238
239 // Thread-local allocation buffers
240 bool supports_tlab_allocation() const { return true; }
241 size_t tlab_capacity() const;
242 size_t tlab_used() const;
243 size_t unsafe_max_tlab_alloc() const;
244
245 // Grow the generation by the specified number of bytes.
246 // The size of bytes is assumed to be properly aligned.
247 // Return true if the expansion was successful.
248 bool expand(size_t bytes);
249
250 // DefNewGeneration cannot currently expand except at
251 // a GC.
252 virtual bool is_maximal_no_gc() const { return true; }
253
254 // Iteration
255 void object_iterate(ObjectClosure* blk);
256
257 void younger_refs_iterate(OopsInGenClosure* cl);
258
259 void space_iterate(SpaceClosure* blk, bool usedOnly = false);
260
261 // Allocation support
262 virtual bool should_allocate(size_t word_size, bool is_tlab) {
263 assert(UseTLAB || !is_tlab, "Should not allocate tlab");
264
265 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
266
267 const bool non_zero = word_size > 0;
268 const bool overflows = word_size >= overflow_limit;
269 const bool check_too_big = _pretenure_size_threshold_words > 0;
270 const bool not_too_big = word_size < _pretenure_size_threshold_words;
271 const bool size_ok = is_tlab || !check_too_big || not_too_big;
272
273 bool result = !overflows &&
274 non_zero &&
275 size_ok;
276
277 return result;
278 }
279
280 HeapWord* allocate(size_t word_size, bool is_tlab);
281 HeapWord* allocate_from_space(size_t word_size);
282
283 HeapWord* par_allocate(size_t word_size, bool is_tlab);
284
285 // Prologue & Epilogue
286 virtual void gc_prologue(bool full);
287 virtual void gc_epilogue(bool full);
288
289 // Save the tops for eden, from, and to
290 virtual void record_spaces_top();
291
292 // Doesn't require additional work during GC prologue and epilogue
293 virtual bool performs_in_place_marking() const { return false; }
294
295 // Accessing marks
296 void save_marks();
297 void reset_saved_marks();
298 bool no_allocs_since_save_marks();
299
300 // Need to declare the full complement of closures, whether we'll
301 // override them or not, or get message from the compiler:
302 // oop_since_save_marks_iterate_nv hides virtual function...
303 #define DefNew_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
304 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
305
306 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DECL)
307
308 #undef DefNew_SINCE_SAVE_MARKS_DECL
309
310 // For non-youngest collection, the DefNewGeneration can contribute
311 // "to-space".
312 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
313 size_t max_alloc_words);
314
315 // Reset for contribution of "to-space".
316 virtual void reset_scratch();
317
318 // GC support
319 virtual void compute_new_size();
320
321 // Returns true if the collection is likely to be safely
322 // completed. Even if this method returns true, a collection
323 // may not be guaranteed to succeed, and the system should be
324 // able to safely unwind and recover from that failure, albeit
325 // at some additional cost. Override superclass's implementation.
326 virtual bool collection_attempt_is_safe();
327
328 virtual void collect(bool full,
329 bool clear_all_soft_refs,
330 size_t size,
331 bool is_tlab);
332 HeapWord* expand_and_allocate(size_t size,
333 bool is_tlab,
334 bool parallel = false);
335
336 oop copy_to_survivor_space(oop old);
337 uint tenuring_threshold() { return _tenuring_threshold; }
338
339 // Performance Counter support
340 void update_counters();
341
342 // Printing
343 virtual const char* name() const;
344 virtual const char* short_name() const { return "DefNew"; }
345
346 bool must_be_youngest() const { return true; }
347 bool must_be_oldest() const { return false; }
348
349 // PrintHeapAtGC support.
350 void print_on(outputStream* st) const;
351
352 void verify();
353
354 bool promo_failure_scan_is_complete() const {
355 return _promo_failure_scan_stack.is_empty();
356 }
357
358 protected:
359 // If clear_space is true, clear the survivor spaces. Eden is
360 // cleared if the minimum size of eden is 0. If mangle_space
361 // is true, also mangle the space in debug mode.
362 void compute_space_boundaries(uintx minimum_eden_size,
363 bool clear_space,
364 bool mangle_space);
365 // Scavenge support
366 void swap_spaces();
367 };
368
369 #endif // SHARE_VM_MEMORY_DEFNEWGENERATION_HPP