1 /*
2 * Copyright (c) 2015, Red Hat, Inc. and/or its affiliates.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP
26
27 #include "classfile/javaClasses.inline.hpp"
28 #include "gc/shenandoah/brooksPointer.hpp"
29 #include "gc/shenandoah/shenandoahAsserts.hpp"
30 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
31 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
32 #include "gc/shenandoah/shenandoahStringDedup.hpp"
33 #include "memory/iterator.inline.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "runtime/prefetch.inline.hpp"
36
37 template <class T, bool COUNT_LIVENESS>
38 void ShenandoahConcurrentMark::do_task(ShenandoahObjToScanQueue* q, T* cl, jushort* live_data, ShenandoahMarkTask* task) {
39 oop obj = task->obj();
40
41 shenandoah_assert_not_forwarded(NULL, obj);
42 shenandoah_assert_marked_next(NULL, obj);
43 shenandoah_assert_not_in_cset_except(NULL, obj, _heap->cancelled_concgc());
44
45 if (task->is_not_chunked()) {
46 if (COUNT_LIVENESS) count_liveness(live_data, obj);
47 if (obj->is_instance()) {
48 // Case 1: Normal oop, process as usual.
49 obj->oop_iterate(cl);
50 } else if (obj->is_objArray()) {
51 // Case 2: Object array instance and no chunk is set. Must be the first
52 // time we visit it, start the chunked processing.
53 do_chunked_array_start<T>(q, cl, obj);
54 } else {
55 // Case 3: Primitive array. Do nothing, no oops there. We use the same
56 // performance tweak TypeArrayKlass::oop_oop_iterate_impl is using:
57 // We skip iterating over the klass pointer since we know that
58 // Universe::TypeArrayKlass never moves.
59 assert (obj->is_typeArray(), "should be type array");
60 }
61 } else {
62 // Case 4: Array chunk, has sensible chunk id. Process it.
63 do_chunked_array<T>(q, cl, obj, task->chunk(), task->pow());
64 }
65 }
66
67 inline void ShenandoahConcurrentMark::count_liveness(jushort* live_data, oop obj) {
68 size_t region_idx = _heap->heap_region_index_containing(obj);
69 jushort cur = live_data[region_idx];
70 int size = obj->size() + BrooksPointer::word_size();
71 int max = (1 << (sizeof(jushort) * 8)) - 1;
72 if (size >= max) {
73 // too big, add to region data directly
74 _heap->regions()->get(region_idx)->increase_live_data_words(size);
75 } else {
76 int new_val = cur + size;
77 if (new_val >= max) {
78 // overflow, flush to region data
79 _heap->regions()->get(region_idx)->increase_live_data_words(new_val);
80 live_data[region_idx] = 0;
81 } else {
82 // still good, remember in locals
83 live_data[region_idx] = (jushort) new_val;
84 }
85 }
86 }
87
88 template <class T>
89 inline void ShenandoahConcurrentMark::do_chunked_array_start(ShenandoahObjToScanQueue* q, T* cl, oop obj) {
90 assert(obj->is_objArray(), "expect object array");
91 objArrayOop array = objArrayOop(obj);
92 int len = array->length();
93
94 if (len <= (int) ObjArrayMarkingStride*2) {
95 // A few slices only, process directly
96 array->oop_iterate_range(cl, 0, len);
97 } else {
98 int bits = log2_long(len);
99 // Compensate for non-power-of-two arrays, cover the array in excess:
100 if (len != (1 << bits)) bits++;
101
102 // Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to
103 // boundaries against array->length(), touching the array header on every chunk.
104 //
105 // To do this, we cut the prefix in full-sized chunks, and submit them on the queue.
106 // If the array is not divided in chunk sizes, then there would be an irregular tail,
107 // which we will process separately.
108
109 int last_idx = 0;
110
111 int chunk = 1;
112 int pow = bits;
113
114 // Handle overflow
115 if (pow >= 31) {
116 assert (pow == 31, "sanity");
117 pow--;
118 chunk = 2;
119 last_idx = (1 << pow);
120 bool pushed = q->push(ShenandoahMarkTask(array, 1, pow));
121 assert(pushed, "overflow queue should always succeed pushing");
122 }
123
124 // Split out tasks, as suggested in ObjArrayChunkedTask docs. Record the last
125 // successful right boundary to figure out the irregular tail.
126 while ((1 << pow) > (int)ObjArrayMarkingStride &&
127 (chunk*2 < ShenandoahMarkTask::chunk_size())) {
128 pow--;
129 int left_chunk = chunk*2 - 1;
130 int right_chunk = chunk*2;
131 int left_chunk_end = left_chunk * (1 << pow);
132 if (left_chunk_end < len) {
133 bool pushed = q->push(ShenandoahMarkTask(array, left_chunk, pow));
134 assert(pushed, "overflow queue should always succeed pushing");
135 chunk = right_chunk;
136 last_idx = left_chunk_end;
137 } else {
138 chunk = left_chunk;
139 }
140 }
141
142 // Process the irregular tail, if present
143 int from = last_idx;
144 if (from < len) {
145 array->oop_iterate_range(cl, from, len);
146 }
147 }
148 }
149
150 template <class T>
151 inline void ShenandoahConcurrentMark::do_chunked_array(ShenandoahObjToScanQueue* q, T* cl, oop obj, int chunk, int pow) {
152 assert(obj->is_objArray(), "expect object array");
153 objArrayOop array = objArrayOop(obj);
154
155 assert (ObjArrayMarkingStride > 0, "sanity");
156
157 // Split out tasks, as suggested in ObjArrayChunkedTask docs. Avoid pushing tasks that
158 // are known to start beyond the array.
159 while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < ShenandoahMarkTask::chunk_size())) {
160 pow--;
161 chunk *= 2;
162 bool pushed = q->push(ShenandoahMarkTask(array, chunk - 1, pow));
163 assert(pushed, "overflow queue should always succeed pushing");
164 }
165
166 int chunk_size = 1 << pow;
167
168 int from = (chunk - 1) * chunk_size;
169 int to = chunk * chunk_size;
170
171 #ifdef ASSERT
172 int len = array->length();
173 assert (0 <= from && from < len, "from is sane: %d/%d", from, len);
174 assert (0 < to && to <= len, "to is sane: %d/%d", to, len);
175 #endif
176
177 array->oop_iterate_range(cl, from, to);
178 }
179
180 inline bool ShenandoahConcurrentMark::try_queue(ShenandoahObjToScanQueue* q, ShenandoahMarkTask &task) {
181 return (q->pop_buffer(task) ||
182 q->pop_local(task) ||
183 q->pop_overflow(task));
184 }
185
186 class ShenandoahSATBBufferClosure : public SATBBufferClosure {
187 private:
188 ShenandoahObjToScanQueue* _queue;
189 ShenandoahHeap* _heap;
190 public:
191 ShenandoahSATBBufferClosure(ShenandoahObjToScanQueue* q) :
192 _queue(q), _heap(ShenandoahHeap::heap())
193 {
194 }
195
196 void do_buffer(void** buffer, size_t size) {
197 for (size_t i = 0; i < size; ++i) {
198 oop* p = (oop*) &buffer[i];
199 ShenandoahConcurrentMark::mark_through_ref<oop, RESOLVE>(p, _heap, _queue);
200 }
201 }
202 };
203
204 inline bool ShenandoahConcurrentMark::try_draining_satb_buffer(ShenandoahObjToScanQueue *q, ShenandoahMarkTask &task) {
205 ShenandoahSATBBufferClosure cl(q);
206 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
207 bool had_refs = satb_mq_set.apply_closure_to_completed_buffer(&cl);
208 return had_refs && try_queue(q, task);
209 }
210
211 template<class T, UpdateRefsMode UPDATE_REFS>
212 inline void ShenandoahConcurrentMark::mark_through_ref(T *p, ShenandoahHeap* heap, ShenandoahObjToScanQueue* q) {
213 ShenandoahConcurrentMark::mark_through_ref<T, UPDATE_REFS, false /* string dedup */>(p, heap, q, NULL);
214 }
215
216 template<class T, UpdateRefsMode UPDATE_REFS, bool STRING_DEDUP>
217 inline void ShenandoahConcurrentMark::mark_through_ref(T *p, ShenandoahHeap* heap, ShenandoahObjToScanQueue* q, ShenandoahStrDedupQueue* dq) {
218 T o = oopDesc::load_heap_oop(p);
219 if (! oopDesc::is_null(o)) {
220 oop obj = oopDesc::decode_heap_oop_not_null(o);
221 switch (UPDATE_REFS) {
222 case NONE:
223 break;
224 case RESOLVE:
225 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
226 break;
227 case SIMPLE:
228 // We piggy-back reference updating to the marking tasks.
229 obj = heap->update_with_forwarded_not_null(p, obj);
230 break;
231 case CONCURRENT:
232 obj = heap->maybe_update_with_forwarded_not_null(p, obj);
233 break;
234 default:
235 ShouldNotReachHere();
236 }
237
238 // Note: Only when concurrently updating references can obj become NULL here.
239 // It happens when a mutator thread beats us by writing another value. In that
240 // case we don't need to do anything else.
241 if (UPDATE_REFS != CONCURRENT || !oopDesc::is_null(obj)) {
242 shenandoah_assert_not_forwarded(p, obj);
243 shenandoah_assert_not_in_cset_except(p, obj, heap->cancelled_concgc());
244
245 if (heap->mark_next(obj)) {
246 bool pushed = q->push(ShenandoahMarkTask(obj));
247 assert(pushed, "overflow queue should always succeed pushing");
248
249 if (STRING_DEDUP && ShenandoahStringDedup::is_candidate(obj)) {
250 assert(ShenandoahStringDedup::is_enabled(), "Must be enabled");
251 assert(dq != NULL, "Dedup queue not set");
252 ShenandoahStringDedup::enqueue_candidate(obj, dq);
253 }
254 }
255
256 shenandoah_assert_marked_next(p, obj);
257 }
258 }
259 }
260
261 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP