1 /*
2 * Copyright (c) 2001, 2019, 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
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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 *
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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23 */
24
25 #ifndef SHARE_GC_SERIAL_DEFNEWGENERATION_HPP
26 #define SHARE_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 CSpaceCounters;
39 class DefNewYoungerGenClosure;
40 class DefNewScanClosure;
41 class ScanWeakRefClosure;
42 class SerialHeap;
43 class STWGCTimer;
44
45 // DefNewGeneration is a young generation containing eden, from- and
46 // to-space.
47
48 class DefNewGeneration: public Generation {
49 friend class VMStructs;
50
51 protected:
52 Generation* _old_gen;
53 uint _tenuring_threshold; // Tenuring threshold for next collection.
54 AgeTable _age_table;
55 // Size of object to pretenure in words; command line provides bytes
56 size_t _pretenure_size_threshold_words;
57
58 AgeTable* age_table() { return &_age_table; }
59
60 // Initialize state to optimistically assume no promotion failure will
61 // happen.
62 void init_assuming_no_promotion_failure();
63 // True iff a promotion has failed in the current collection.
64 bool _promotion_failed;
65 bool promotion_failed() { return _promotion_failed; }
66 PromotionFailedInfo _promotion_failed_info;
67
68 // Handling promotion failure. A young generation collection
69 // can fail if a live object cannot be copied out of its
70 // location in eden or from-space during the collection. If
71 // a collection fails, the young generation is left in a
72 // consistent state such that it can be collected by a
73 // full collection.
74 // Before the collection
75 // Objects are in eden or from-space
76 // All roots into the young generation point into eden or from-space.
77 //
78 // After a failed collection
79 // Objects may be in eden, from-space, or to-space
80 // An object A in eden or from-space may have a copy B
81 // in to-space. If B exists, all roots that once pointed
82 // to A must now point to B.
83 // All objects in the young generation are unmarked.
84 // Eden, from-space, and to-space will all be collected by
85 // the full collection.
86 void handle_promotion_failure(oop);
87
88 // In the absence of promotion failure, we wouldn't look at "from-space"
89 // objects after a young-gen collection. When promotion fails, however,
90 // the subsequent full collection will look at from-space objects:
91 // therefore we must remove their forwarding pointers.
92 void remove_forwarding_pointers();
93
94 virtual void restore_preserved_marks();
95
96 // Preserved marks
97 PreservedMarksSet _preserved_marks_set;
98
99 // Promotion failure handling
100 OopIterateClosure *_promo_failure_scan_stack_closure;
101 void set_promo_failure_scan_stack_closure(OopIterateClosure *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 ContiguousSpace* _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_down(n, alignment) : alignment;
152 }
153
154 public: // was "protected" but caused compile error on win32
155 class IsAliveClosure: public BoolObjectClosure {
156 Generation* _young_gen;
157 public:
158 IsAliveClosure(Generation* young_gen);
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 FastEvacuateFollowersClosure: public VoidClosure {
184 SerialHeap* _heap;
185 DefNewScanClosure* _scan_cur_or_nonheap;
186 DefNewYoungerGenClosure* _scan_older;
187 public:
188 FastEvacuateFollowersClosure(SerialHeap* heap,
189 DefNewScanClosure* cur,
190 DefNewYoungerGenClosure* older);
191 void do_void();
192 };
193
194 public:
195 DefNewGeneration(ReservedSpace rs,
196 size_t initial_byte_size,
197 size_t min_byte_size,
198 size_t max_byte_size,
199 const char* policy="Serial young collection pauses");
200
201 virtual void ref_processor_init();
202
203 virtual Generation::Name kind() { return Generation::DefNew; }
204
205 // Accessing spaces
206 ContiguousSpace* eden() const { return _eden_space; }
207 ContiguousSpace* from() const { return _from_space; }
208 ContiguousSpace* to() const { return _to_space; }
209
210 virtual CompactibleSpace* first_compaction_space() const;
211
212 // Space enquiries
213 size_t capacity() const;
214 size_t used() const;
215 size_t free() const;
216 size_t max_capacity() const;
217 size_t capacity_before_gc() const;
218 size_t unsafe_max_alloc_nogc() const;
219 size_t contiguous_available() const;
220
221 size_t max_eden_size() const { return _max_eden_size; }
222 size_t max_survivor_size() const { return _max_survivor_size; }
223
224 bool supports_inline_contig_alloc() const { return true; }
225 HeapWord* volatile* top_addr() const;
226 HeapWord** end_addr() const;
227
228 // Thread-local allocation buffers
229 bool supports_tlab_allocation() const { return true; }
230 size_t tlab_capacity() const;
231 size_t tlab_used() const;
232 size_t unsafe_max_tlab_alloc() const;
233
234 // Grow the generation by the specified number of bytes.
235 // The size of bytes is assumed to be properly aligned.
236 // Return true if the expansion was successful.
237 bool expand(size_t bytes);
238
239 // DefNewGeneration cannot currently expand except at
240 // a GC.
241 virtual bool is_maximal_no_gc() const { return true; }
242
243 // Iteration
244 void object_iterate(ObjectClosure* blk);
245
246 void space_iterate(SpaceClosure* blk, bool usedOnly = false);
247
248 // Allocation support
249 virtual bool should_allocate(size_t word_size, bool is_tlab) {
250 assert(UseTLAB || !is_tlab, "Should not allocate tlab");
251
252 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
253
254 const bool non_zero = word_size > 0;
255 const bool overflows = word_size >= overflow_limit;
256 const bool check_too_big = _pretenure_size_threshold_words > 0;
257 const bool not_too_big = word_size < _pretenure_size_threshold_words;
258 const bool size_ok = is_tlab || !check_too_big || not_too_big;
259
260 bool result = !overflows &&
261 non_zero &&
262 size_ok;
263
264 return result;
265 }
266
267 HeapWord* allocate(size_t word_size, bool is_tlab);
268 HeapWord* allocate_from_space(size_t word_size);
269
270 HeapWord* par_allocate(size_t word_size, bool is_tlab);
271
272 virtual void gc_epilogue(bool full);
273
274 // Save the tops for eden, from, and to
275 virtual void record_spaces_top();
276
277 // Accessing marks
278 void save_marks();
279 void reset_saved_marks();
280 bool no_allocs_since_save_marks();
281
282 // Need to declare the full complement of closures, whether we'll
283 // override them or not, or get message from the compiler:
284 // oop_since_save_marks_iterate_nv hides virtual function...
285 template <typename OopClosureType>
286 void oop_since_save_marks_iterate(OopClosureType* cl);
287
288 // For non-youngest collection, the DefNewGeneration can contribute
289 // "to-space".
290 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
291 size_t max_alloc_words);
292
293 // Reset for contribution of "to-space".
294 virtual void reset_scratch();
295
296 // GC support
297 virtual void compute_new_size();
298
299 // Returns true if the collection is likely to be safely
300 // completed. Even if this method returns true, a collection
301 // may not be guaranteed to succeed, and the system should be
302 // able to safely unwind and recover from that failure, albeit
303 // at some additional cost. Override superclass's implementation.
304 virtual bool collection_attempt_is_safe();
305
306 virtual void collect(bool full,
307 bool clear_all_soft_refs,
308 size_t size,
309 bool is_tlab);
310 HeapWord* expand_and_allocate(size_t size,
311 bool is_tlab,
312 bool parallel = false);
313
314 oop copy_to_survivor_space(oop old);
315 uint tenuring_threshold() { return _tenuring_threshold; }
316
317 // Performance Counter support
318 void update_counters();
319
320 // Printing
321 virtual const char* name() const;
322 virtual const char* short_name() const { return "DefNew"; }
323
324 void print_on(outputStream* st) const;
325
326 void verify();
327
328 bool promo_failure_scan_is_complete() const {
329 return _promo_failure_scan_stack.is_empty();
330 }
331
332 protected:
333 // If clear_space is true, clear the survivor spaces. Eden is
334 // cleared if the minimum size of eden is 0. If mangle_space
335 // is true, also mangle the space in debug mode.
336 void compute_space_boundaries(uintx minimum_eden_size,
337 bool clear_space,
338 bool mangle_space);
339
340 // Return adjusted new size for NewSizeThreadIncrease.
341 // If any overflow happens, revert to previous new size.
342 size_t adjust_for_thread_increase(size_t new_size_candidate,
343 size_t new_size_before,
344 size_t alignment) const;
345
346
347 // Scavenge support
348 void swap_spaces();
349 };
350
351 #endif // SHARE_GC_SERIAL_DEFNEWGENERATION_HPP