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
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_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
37class ContiguousSpace;
38class ScanClosure;
39class STWGCTimer;
40class CSpaceCounters;
41class ScanWeakRefClosure;
42class SerialHeap;
43
44// DefNewGeneration is a young generation containing eden, from- and
45// to-space.
46
47class DefNewGeneration: public Generation {
48 friend class VMStructs;
49
50protected:
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 OopIterateClosure *_promo_failure_scan_stack_closure;
100 void set_promo_failure_scan_stack_closure(OopIterateClosure *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,
195 size_t initial_byte_size,
196 size_t min_byte_size,
197 size_t max_byte_size,
198 const char* policy="Serial young collection pauses");
199
200 virtual void ref_processor_init();
201
202 virtual Generation::Name kind() { return Generation::DefNew; }
203
204 // Accessing spaces
205 ContiguousSpace* eden() const { return _eden_space; }
206 ContiguousSpace* from() const { return _from_space; }
207 ContiguousSpace* to() const { return _to_space; }
208
209 virtual CompactibleSpace* first_compaction_space() const;
210
211 // Space enquiries
212 size_t capacity() const;
213 size_t used() const;
214 size_t free() const;
215 size_t max_capacity() const;
216 size_t capacity_before_gc() const;
217 size_t unsafe_max_alloc_nogc() const;
218 size_t contiguous_available() const;
219
220 size_t max_eden_size() const { return _max_eden_size; }
221 size_t max_survivor_size() const { return _max_survivor_size; }
222
223 bool supports_inline_contig_alloc() const { return true; }
224 HeapWord* volatile* top_addr() const;
225 HeapWord** end_addr() const;
226
227 // Thread-local allocation buffers
228 bool supports_tlab_allocation() const { return true; }
229 size_t tlab_capacity() const;
230 size_t tlab_used() const;
231 size_t unsafe_max_tlab_alloc() const;
232
233 // Grow the generation by the specified number of bytes.
234 // The size of bytes is assumed to be properly aligned.
235 // Return true if the expansion was successful.
236 bool expand(size_t bytes);
237
238 // DefNewGeneration cannot currently expand except at
239 // a GC.
240 virtual bool is_maximal_no_gc() const { return true; }
241
242 // Iteration
243 void object_iterate(ObjectClosure* blk);
244
245 void younger_refs_iterate(OopsInGenClosure* cl, uint n_threads);
246
247 void space_iterate(SpaceClosure* blk, bool usedOnly = false);
248
249 // Allocation support
250 virtual bool should_allocate(size_t word_size, bool is_tlab) {
251 assert(UseTLAB || !is_tlab, "Should not allocate tlab");
252
253 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
254
255 const bool non_zero = word_size > 0;
256 const bool overflows = word_size >= overflow_limit;
257 const bool check_too_big = _pretenure_size_threshold_words > 0;
258 const bool not_too_big = word_size < _pretenure_size_threshold_words;
259 const bool size_ok = is_tlab || !check_too_big || not_too_big;
260
261 bool result = !overflows &&
262 non_zero &&
263 size_ok;
264
265 return result;
266 }
267
268 HeapWord* allocate(size_t word_size, bool is_tlab);
269 HeapWord* allocate_from_space(size_t word_size);
270
271 HeapWord* par_allocate(size_t word_size, bool is_tlab);
272
273 virtual void gc_epilogue(bool full);
274
275 // Save the tops for eden, from, and to
276 virtual void record_spaces_top();
277
278 // Accessing marks
279 void save_marks();
280 void reset_saved_marks();
281 bool no_allocs_since_save_marks();
282
283 // Need to declare the full complement of closures, whether we'll
284 // override them or not, or get message from the compiler:
285 // oop_since_save_marks_iterate_nv hides virtual function...
286 template <typename OopClosureType>
287 void oop_since_save_marks_iterate(OopClosureType* cl);
288
289 // For non-youngest collection, the DefNewGeneration can contribute
290 // "to-space".
291 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
292 size_t max_alloc_words);
293
294 // Reset for contribution of "to-space".
295 virtual void reset_scratch();
296
297 // GC support
298 virtual void compute_new_size();
299
300 // Returns true if the collection is likely to be safely
301 // completed. Even if this method returns true, a collection
302 // may not be guaranteed to succeed, and the system should be
303 // able to safely unwind and recover from that failure, albeit
304 // at some additional cost. Override superclass's implementation.
305 virtual bool collection_attempt_is_safe();
306
307 virtual void collect(bool full,
308 bool clear_all_soft_refs,
309 size_t size,
310 bool is_tlab);
311 HeapWord* expand_and_allocate(size_t size,
312 bool is_tlab,
313 bool parallel = false);
314
315 oop copy_to_survivor_space(oop old);
316 uint tenuring_threshold() { return _tenuring_threshold; }
317
318 // Performance Counter support
319 void update_counters();
320
321 // Printing
322 virtual const char* name() const;
323 virtual const char* short_name() const { return "DefNew"; }
324
325 void print_on(outputStream* st) const;
326
327 void verify();
328
329 bool promo_failure_scan_is_complete() const {
330 return _promo_failure_scan_stack.is_empty();
331 }
332
333 protected:
334 // If clear_space is true, clear the survivor spaces. Eden is
335 // cleared if the minimum size of eden is 0. If mangle_space
336 // is true, also mangle the space in debug mode.
337 void compute_space_boundaries(uintx minimum_eden_size,
338 bool clear_space,
339 bool mangle_space);
340
341 // Return adjusted new size for NewSizeThreadIncrease.
342 // If any overflow happens, revert to previous new size.
343 size_t adjust_for_thread_increase(size_t new_size_candidate,
344 size_t new_size_before,
345 size_t alignment) const;
346
347
348 // Scavenge support
349 void swap_spaces();
350};
351
352#endif // SHARE_GC_SERIAL_DEFNEWGENERATION_HPP
353