1 /*
2 * Copyright (c) 2001, 2016, 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.
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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 // Preserved marks
93 PreservedMarksSet _preserved_marks_set;
94
95 // Promotion failure handling
96 ExtendedOopClosure *_promo_failure_scan_stack_closure;
97 void set_promo_failure_scan_stack_closure(ExtendedOopClosure *scan_stack_closure) {
98 _promo_failure_scan_stack_closure = scan_stack_closure;
99 }
100
101 Stack<oop, mtGC> _promo_failure_scan_stack;
102 void drain_promo_failure_scan_stack(void);
103 bool _promo_failure_drain_in_progress;
104
105 // Performance Counters
106 GenerationCounters* _gen_counters;
107 CSpaceCounters* _eden_counters;
108 CSpaceCounters* _from_counters;
109 CSpaceCounters* _to_counters;
110
111 // sizing information
112 size_t _max_eden_size;
113 size_t _max_survivor_size;
114
115 // Allocation support
116 bool _should_allocate_from_space;
117 bool should_allocate_from_space() const {
118 return _should_allocate_from_space;
119 }
120 void clear_should_allocate_from_space() {
121 _should_allocate_from_space = false;
122 }
123 void set_should_allocate_from_space() {
124 _should_allocate_from_space = true;
125 }
126
127 // Tenuring
128 void adjust_desired_tenuring_threshold();
129
130 // Spaces
131 ContiguousSpace* _eden_space;
132 ContiguousSpace* _from_space;
133 ContiguousSpace* _to_space;
134
135 STWGCTimer* _gc_timer;
136
137 enum SomeProtectedConstants {
138 // Generations are GenGrain-aligned and have size that are multiples of
139 // GenGrain.
140 MinFreeScratchWords = 100
141 };
142
143 // Return the size of a survivor space if this generation were of size
144 // gen_size.
145 size_t compute_survivor_size(size_t gen_size, size_t alignment) const {
146 size_t n = gen_size / (SurvivorRatio + 2);
147 return n > alignment ? align_down(n, alignment) : alignment;
148 }
149
150 public: // was "protected" but caused compile error on win32
151 class IsAliveClosure: public BoolObjectClosure {
152 Generation* _young_gen;
153 public:
154 IsAliveClosure(Generation* young_gen);
155 bool do_object_b(oop p);
156 };
157
158 class KeepAliveClosure: public OopClosure {
159 protected:
160 ScanWeakRefClosure* _cl;
161 CardTableRS* _rs;
162 template <class T> void do_oop_work(T* p);
163 public:
164 KeepAliveClosure(ScanWeakRefClosure* cl);
165 virtual void do_oop(oop* p);
166 virtual void do_oop(narrowOop* p);
167 };
168
169 class FastKeepAliveClosure: public KeepAliveClosure {
170 protected:
171 HeapWord* _boundary;
172 template <class T> void do_oop_work(T* p);
173 public:
174 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl);
175 virtual void do_oop(oop* p);
176 virtual void do_oop(narrowOop* p);
177 };
178
179 class EvacuateFollowersClosure: public VoidClosure {
180 GenCollectedHeap* _gch;
181 ScanClosure* _scan_cur_or_nonheap;
182 ScanClosure* _scan_older;
183 public:
184 EvacuateFollowersClosure(GenCollectedHeap* gch,
185 ScanClosure* cur, ScanClosure* older);
186 void do_void();
187 };
188
189 class FastEvacuateFollowersClosure: public VoidClosure {
190 GenCollectedHeap* _gch;
191 DefNewGeneration* _young_gen;
192 FastScanClosure* _scan_cur_or_nonheap;
193 FastScanClosure* _scan_older;
194 public:
195 FastEvacuateFollowersClosure(GenCollectedHeap* gch,
196 FastScanClosure* cur,
197 FastScanClosure* older);
198 void do_void();
199 };
200
201 public:
202 DefNewGeneration(ReservedSpace rs, size_t initial_byte_size,
203 const char* policy="Copy");
204
205 virtual void ref_processor_init();
206
207 virtual Generation::Name kind() { return Generation::DefNew; }
208
209 // Accessing spaces
210 ContiguousSpace* eden() const { return _eden_space; }
211 ContiguousSpace* from() const { return _from_space; }
212 ContiguousSpace* to() const { return _to_space; }
213
214 virtual CompactibleSpace* first_compaction_space() const;
215
216 // Space enquiries
217 size_t capacity() const;
218 size_t used() const;
219 size_t free() const;
220 size_t max_capacity() const;
221 size_t capacity_before_gc() const;
222 size_t unsafe_max_alloc_nogc() const;
223 size_t contiguous_available() const;
224
225 size_t max_eden_size() const { return _max_eden_size; }
226 size_t max_survivor_size() const { return _max_survivor_size; }
227
228 bool supports_inline_contig_alloc() const { return true; }
229 HeapWord* volatile* top_addr() const;
230 HeapWord** end_addr() const;
231
232 // Thread-local allocation buffers
233 bool supports_tlab_allocation() const { return true; }
234 size_t tlab_capacity() const;
235 size_t tlab_used() const;
236 size_t unsafe_max_tlab_alloc() const;
237
238 // Grow the generation by the specified number of bytes.
239 // The size of bytes is assumed to be properly aligned.
240 // Return true if the expansion was successful.
241 bool expand(size_t bytes);
242
243 // DefNewGeneration cannot currently expand except at
244 // a GC.
245 virtual bool is_maximal_no_gc() const { return true; }
246
247 // Iteration
248 void object_iterate(ObjectClosure* blk);
249
250 void younger_refs_iterate(OopsInGenClosure* cl, uint n_threads);
251
252 void space_iterate(SpaceClosure* blk, bool usedOnly = false);
253
254 // Allocation support
255 virtual bool should_allocate(size_t word_size, bool is_tlab) {
256 assert(UseTLAB || !is_tlab, "Should not allocate tlab");
257
258 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
259
260 const bool non_zero = word_size > 0;
261 const bool overflows = word_size >= overflow_limit;
262 const bool check_too_big = _pretenure_size_threshold_words > 0;
263 const bool not_too_big = word_size < _pretenure_size_threshold_words;
264 const bool size_ok = is_tlab || !check_too_big || not_too_big;
265
266 bool result = !overflows &&
267 non_zero &&
268 size_ok;
269
270 return result;
271 }
272
273 HeapWord* allocate(size_t word_size, bool is_tlab);
274 HeapWord* allocate_from_space(size_t word_size);
275
276 HeapWord* par_allocate(size_t word_size, bool is_tlab);
277
278 virtual void gc_epilogue(bool full);
279
280 // Save the tops for eden, from, and to
281 virtual void record_spaces_top();
282
283 // Accessing marks
284 void save_marks();
285 void reset_saved_marks();
286 bool no_allocs_since_save_marks();
287
288 // Need to declare the full complement of closures, whether we'll
289 // override them or not, or get message from the compiler:
290 // oop_since_save_marks_iterate_nv hides virtual function...
291 #define DefNew_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
292 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
293
294 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DECL)
295
296 #undef DefNew_SINCE_SAVE_MARKS_DECL
297
298 // For non-youngest collection, the DefNewGeneration can contribute
299 // "to-space".
300 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
301 size_t max_alloc_words);
302
303 // Reset for contribution of "to-space".
304 virtual void reset_scratch();
305
306 // GC support
307 virtual void compute_new_size();
308
309 // Returns true if the collection is likely to be safely
310 // completed. Even if this method returns true, a collection
311 // may not be guaranteed to succeed, and the system should be
312 // able to safely unwind and recover from that failure, albeit
313 // at some additional cost. Override superclass's implementation.
314 virtual bool collection_attempt_is_safe();
315
316 virtual void collect(bool full,
317 bool clear_all_soft_refs,
318 size_t size,
319 bool is_tlab);
320 HeapWord* expand_and_allocate(size_t size,
321 bool is_tlab,
322 bool parallel = false);
323
324 oop copy_to_survivor_space(oop old);
325 uint tenuring_threshold() { return _tenuring_threshold; }
326
327 // Performance Counter support
328 void update_counters();
329
330 // Printing
331 virtual const char* name() const;
332 virtual const char* short_name() const { return "DefNew"; }
333
334 void print_on(outputStream* st) const;
335
336 void verify();
337
338 bool promo_failure_scan_is_complete() const {
339 return _promo_failure_scan_stack.is_empty();
340 }
341
342 protected:
343 // If clear_space is true, clear the survivor spaces. Eden is
344 // cleared if the minimum size of eden is 0. If mangle_space
345 // is true, also mangle the space in debug mode.
346 void compute_space_boundaries(uintx minimum_eden_size,
347 bool clear_space,
348 bool mangle_space);
349
350 // Return adjusted new size for NewSizeThreadIncrease.
351 // If any overflow happens, revert to previous new size.
352 size_t adjust_for_thread_increase(size_t new_size_candidate,
353 size_t new_size_before,
354 size_t alignment) const;
355
356
357 // Scavenge support
358 void swap_spaces();
359 };
360
361 #endif // SHARE_VM_GC_SERIAL_DEFNEWGENERATION_HPP