1 /*
2 * Copyright (c) 1997, 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 #include "precompiled.hpp"
26 #include "gc/shared/blockOffsetTable.inline.hpp"
27 #include "gc/shared/cardTableRS.hpp"
28 #include "gc/shared/collectedHeap.inline.hpp"
29 #include "gc/shared/gcLocker.hpp"
30 #include "gc/shared/gcTimer.hpp"
31 #include "gc/shared/gcTrace.hpp"
32 #include "gc/shared/genCollectedHeap.hpp"
33 #include "gc/shared/genOopClosures.hpp"
34 #include "gc/shared/genOopClosures.inline.hpp"
35 #include "gc/shared/generation.hpp"
36 #include "gc/shared/generationSpec.hpp"
37 #include "gc/shared/space.inline.hpp"
38 #include "gc/shared/spaceDecorator.inline.hpp"
39 #include "logging/log.hpp"
40 #include "memory/allocation.inline.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "runtime/java.hpp"
43 #include "utilities/copy.hpp"
44 #include "utilities/events.hpp"
45
46 Generation::Generation(ReservedSpace rs, size_t initial_size) :
47 _gc_manager(NULL),
48 _ref_processor(NULL) {
49 if (!_virtual_space.initialize(rs, initial_size)) {
50 vm_exit_during_initialization("Could not reserve enough space for "
51 "object heap");
52 }
53 // Mangle all of the the initial generation.
54 if (ZapUnusedHeapArea) {
55 MemRegion mangle_region((HeapWord*)_virtual_space.low(),
56 (HeapWord*)_virtual_space.high());
57 SpaceMangler::mangle_region(mangle_region);
58 }
59 _reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(),
60 (HeapWord*)_virtual_space.high_boundary());
61 }
62
63 size_t Generation::initial_size() {
64 GenCollectedHeap* gch = GenCollectedHeap::heap();
65 if (gch->is_young_gen(this)) {
66 return gch->young_gen_spec()->init_size();
67 }
68 return gch->old_gen_spec()->init_size();
69 }
70
71 size_t Generation::max_capacity() const {
72 return reserved().byte_size();
73 }
74
75 // By default we get a single threaded default reference processor;
76 // generations needing multi-threaded refs processing or discovery override this method.
77 void Generation::ref_processor_init() {
78 assert(_ref_processor == NULL, "a reference processor already exists");
79 assert(!_reserved.is_empty(), "empty generation?");
80 _span_based_discoverer.set_span(_reserved);
81 _ref_processor = new ReferenceProcessor(&_span_based_discoverer); // a vanilla reference processor
82 if (_ref_processor == NULL) {
83 vm_exit_during_initialization("Could not allocate ReferenceProcessor object");
84 }
85 }
86
87 void Generation::print() const { print_on(tty); }
88
89 void Generation::print_on(outputStream* st) const {
90 st->print(" %-20s", name());
91 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
92 capacity()/K, used()/K);
93 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
94 p2i(_virtual_space.low_boundary()),
95 p2i(_virtual_space.high()),
96 p2i(_virtual_space.high_boundary()));
97 }
98
99 void Generation::print_summary_info_on(outputStream* st) {
100 StatRecord* sr = stat_record();
101 double time = sr->accumulated_time.seconds();
102 st->print_cr("Accumulated %s generation GC time %3.7f secs, "
103 "%u GC's, avg GC time %3.7f",
104 GenCollectedHeap::heap()->is_young_gen(this) ? "young" : "old" ,
105 time,
106 sr->invocations,
107 sr->invocations > 0 ? time / sr->invocations : 0.0);
108 }
109
110 // Utility iterator classes
111
112 class GenerationIsInReservedClosure : public SpaceClosure {
113 public:
114 const void* _p;
115 Space* sp;
116 virtual void do_space(Space* s) {
117 if (sp == NULL) {
118 if (s->is_in_reserved(_p)) sp = s;
119 }
120 }
121 GenerationIsInReservedClosure(const void* p) : _p(p), sp(NULL) {}
122 };
123
124 class GenerationIsInClosure : public SpaceClosure {
125 public:
126 const void* _p;
127 Space* sp;
128 virtual void do_space(Space* s) {
129 if (sp == NULL) {
130 if (s->is_in(_p)) sp = s;
131 }
132 }
133 GenerationIsInClosure(const void* p) : _p(p), sp(NULL) {}
134 };
135
136 bool Generation::is_in(const void* p) const {
137 GenerationIsInClosure blk(p);
138 ((Generation*)this)->space_iterate(&blk);
139 return blk.sp != NULL;
140 }
141
142 size_t Generation::max_contiguous_available() const {
143 // The largest number of contiguous free words in this or any higher generation.
144 size_t avail = contiguous_available();
145 size_t old_avail = 0;
146 if (GenCollectedHeap::heap()->is_young_gen(this)) {
147 old_avail = GenCollectedHeap::heap()->old_gen()->contiguous_available();
148 }
149 return MAX2(avail, old_avail);
150 }
151
152 bool Generation::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
153 size_t available = max_contiguous_available();
154 bool res = (available >= max_promotion_in_bytes);
155 log_trace(gc)("Generation: promo attempt is%s safe: available(" SIZE_FORMAT ") %s max_promo(" SIZE_FORMAT ")",
156 res? "":" not", available, res? ">=":"<", max_promotion_in_bytes);
157 return res;
158 }
159
160 // Ignores "ref" and calls allocate().
161 oop Generation::promote(oop obj, size_t obj_size) {
162 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
163
164 #ifndef PRODUCT
165 if (GenCollectedHeap::heap()->promotion_should_fail()) {
166 return NULL;
167 }
168 #endif // #ifndef PRODUCT
169
170 HeapWord* result = allocate(obj_size, false);
171 if (result != NULL) {
172 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), result, obj_size);
173 return oop(result);
174 } else {
175 GenCollectedHeap* gch = GenCollectedHeap::heap();
176 return gch->handle_failed_promotion(this, obj, obj_size);
177 }
178 }
179
180 oop Generation::par_promote(int thread_num,
181 oop obj, markWord m, size_t word_sz) {
182 // Could do a bad general impl here that gets a lock. But no.
183 ShouldNotCallThis();
184 return NULL;
185 }
186
187 Space* Generation::space_containing(const void* p) const {
188 GenerationIsInReservedClosure blk(p);
189 // Cast away const
190 ((Generation*)this)->space_iterate(&blk);
191 return blk.sp;
192 }
193
194 // Some of these are mediocre general implementations. Should be
195 // overridden to get better performance.
196
197 class GenerationBlockStartClosure : public SpaceClosure {
198 public:
199 const void* _p;
200 HeapWord* _start;
201 virtual void do_space(Space* s) {
202 if (_start == NULL && s->is_in_reserved(_p)) {
203 _start = s->block_start(_p);
204 }
205 }
206 GenerationBlockStartClosure(const void* p) { _p = p; _start = NULL; }
207 };
208
209 HeapWord* Generation::block_start(const void* p) const {
210 GenerationBlockStartClosure blk(p);
211 // Cast away const
212 ((Generation*)this)->space_iterate(&blk);
213 return blk._start;
214 }
215
216 class GenerationBlockSizeClosure : public SpaceClosure {
217 public:
218 const HeapWord* _p;
219 size_t size;
220 virtual void do_space(Space* s) {
221 if (size == 0 && s->is_in_reserved(_p)) {
222 size = s->block_size(_p);
223 }
224 }
225 GenerationBlockSizeClosure(const HeapWord* p) { _p = p; size = 0; }
226 };
227
228 size_t Generation::block_size(const HeapWord* p) const {
229 GenerationBlockSizeClosure blk(p);
230 // Cast away const
231 ((Generation*)this)->space_iterate(&blk);
232 assert(blk.size > 0, "seems reasonable");
233 return blk.size;
234 }
235
236 class GenerationBlockIsObjClosure : public SpaceClosure {
237 public:
238 const HeapWord* _p;
239 bool is_obj;
240 virtual void do_space(Space* s) {
241 if (!is_obj && s->is_in_reserved(_p)) {
242 is_obj |= s->block_is_obj(_p);
243 }
244 }
245 GenerationBlockIsObjClosure(const HeapWord* p) { _p = p; is_obj = false; }
246 };
247
248 bool Generation::block_is_obj(const HeapWord* p) const {
249 GenerationBlockIsObjClosure blk(p);
250 // Cast away const
251 ((Generation*)this)->space_iterate(&blk);
252 return blk.is_obj;
253 }
254
255 class GenerationOopIterateClosure : public SpaceClosure {
256 public:
257 OopIterateClosure* _cl;
258 virtual void do_space(Space* s) {
259 s->oop_iterate(_cl);
260 }
261 GenerationOopIterateClosure(OopIterateClosure* cl) :
262 _cl(cl) {}
263 };
264
265 void Generation::oop_iterate(OopIterateClosure* cl) {
266 GenerationOopIterateClosure blk(cl);
267 space_iterate(&blk);
268 }
269
270 void Generation::younger_refs_in_space_iterate(Space* sp,
271 OopsInGenClosure* cl,
272 uint n_threads) {
273 CardTableRS* rs = GenCollectedHeap::heap()->rem_set();
274 rs->younger_refs_in_space_iterate(sp, cl, n_threads);
275 }
276
277 class GenerationObjIterateClosure : public SpaceClosure {
278 private:
279 ObjectClosure* _cl;
280 public:
281 virtual void do_space(Space* s) {
282 s->object_iterate(_cl);
283 }
284 GenerationObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
285 };
286
287 void Generation::object_iterate(ObjectClosure* cl) {
288 GenerationObjIterateClosure blk(cl);
289 space_iterate(&blk);
290 }
291
292 #if INCLUDE_SERIALGC
293
294 void Generation::prepare_for_compaction(CompactPoint* cp) {
295 // Generic implementation, can be specialized
296 CompactibleSpace* space = first_compaction_space();
297 while (space != NULL) {
298 space->prepare_for_compaction(cp);
299 space = space->next_compaction_space();
300 }
301 }
302
303 class AdjustPointersClosure: public SpaceClosure {
304 public:
305 void do_space(Space* sp) {
306 sp->adjust_pointers();
307 }
308 };
309
310 void Generation::adjust_pointers() {
311 // Note that this is done over all spaces, not just the compactible
312 // ones.
313 AdjustPointersClosure blk;
314 space_iterate(&blk, true);
315 }
316
317 void Generation::compact() {
318 CompactibleSpace* sp = first_compaction_space();
319 while (sp != NULL) {
320 sp->compact();
321 sp = sp->next_compaction_space();
322 }
323 }
324
325 #endif // INCLUDE_SERIALGC