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 *
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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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16 * 2 along with this work; if not, write to the Free Software Foundation,
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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 STWGCTimer;
39 class CSpaceCounters;
40 class ScanWeakRefClosure;
41 class SerialHeap;
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 OopIterateClosure *_promo_failure_scan_stack_closure;
99 void set_promo_failure_scan_stack_closure(OopIterateClosure *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 FastEvacuateFollowersClosure: public VoidClosure {
182 SerialHeap* _heap;
183 FastScanClosure* _scan_cur_or_nonheap;
184 FastScanClosure* _scan_older;
185 public:
186 FastEvacuateFollowersClosure(SerialHeap* heap,
187 FastScanClosure* cur,
188 FastScanClosure* older);
189 void do_void();
190 };
191
192 public:
193 DefNewGeneration(ReservedSpace rs,
194 size_t initial_byte_size,
195 size_t min_byte_size,
196 size_t max_byte_size,
197 const char* policy="Serial young collection pauses");
198
199 virtual void ref_processor_init();
200
201 virtual Generation::Name kind() { return Generation::DefNew; }
202
203 // Accessing spaces
204 ContiguousSpace* eden() const { return _eden_space; }
205 ContiguousSpace* from() const { return _from_space; }
206 ContiguousSpace* to() const { return _to_space; }
207
208 virtual CompactibleSpace* first_compaction_space() const;
209
210 // Space enquiries
211 size_t capacity() const;
212 size_t used() const;
213 size_t free() const;
214 size_t max_capacity() const;
215 size_t capacity_before_gc() const;
216 size_t unsafe_max_alloc_nogc() const;
217 size_t contiguous_available() const;
218
219 size_t max_eden_size() const { return _max_eden_size; }
220 size_t max_survivor_size() const { return _max_survivor_size; }
221
222 bool supports_inline_contig_alloc() const { return true; }
223 HeapWord* volatile* top_addr() const;
224 HeapWord** end_addr() const;
225
226 // Thread-local allocation buffers
227 bool supports_tlab_allocation() const { return true; }
228 size_t tlab_capacity() const;
229 size_t tlab_used() const;
230 size_t unsafe_max_tlab_alloc() const;
231
232 // Grow the generation by the specified number of bytes.
233 // The size of bytes is assumed to be properly aligned.
234 // Return true if the expansion was successful.
235 bool expand(size_t bytes);
236
237 // DefNewGeneration cannot currently expand except at
238 // a GC.
239 virtual bool is_maximal_no_gc() const { return true; }
240
241 // Iteration
242 void object_iterate(ObjectClosure* blk);
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_GC_SERIAL_DEFNEWGENERATION_HPP