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 "gc/shenandoah/brooksPointer.hpp"
28 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
29 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
30 #include "memory/iterator.inline.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/prefetch.inline.hpp"
33
34 template <class T, bool COUNT_LIVENESS>
35 void ShenandoahConcurrentMark::do_task(ShenandoahObjToScanQueue* q, T* cl, jushort* live_data, ShenandoahMarkTask* task) {
36 oop obj = task->obj();
37
38 assert(obj != NULL, "expect non-null object");
39 assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static_not_null(obj)), "expect forwarded obj in queue");
40 assert(_heap->cancelled_concgc()
41 || oopDesc::bs()->is_safe(obj),
42 "we don't want to mark objects in from-space");
43 assert(_heap->is_in(obj), "referenced objects must be in the heap. No?");
44 assert(_heap->is_marked(obj), "only marked objects on task queue");
45
46 if (task->is_not_chunked()) {
47 if (COUNT_LIVENESS) count_liveness(live_data, obj);
48 if (obj->is_instance()) {
49 // Case 1: Normal oop, process as usual.
50 obj->oop_iterate(cl);
51 } else if (obj->is_objArray()) {
52 // Case 2: Object array instance and no chunk is set. Must be the first
53 // time we visit it, start the chunked processing.
54 do_chunked_array_start<T>(q, cl, obj);
55 } else {
56 // Case 3: Primitive array. Do nothing, no oops there. We use the same
57 // performance tweak TypeArrayKlass::oop_oop_iterate_impl is using:
58 // We skip iterating over the klass pointer since we know that
59 // Universe::TypeArrayKlass never moves.
60 assert (obj->is_typeArray(), "should be type array");
61 }
62 } else {
63 // Case 4: Array chunk, has sensible chunk id. Process it.
64 do_chunked_array<T>(q, cl, obj, task->chunk(), task->pow());
65 }
66 }
67
68 inline void ShenandoahConcurrentMark::count_liveness(jushort* live_data, oop obj) {
69 size_t region_idx = _heap->heap_region_index_containing(obj);
70 jushort cur = live_data[region_idx];
71 int size = obj->size() + BrooksPointer::word_size();
72 int max = (1 << (sizeof(jushort) * 8)) - 1;
73 if (size >= max) {
74 // too big, add to region data directly
75 _heap->regions()->get(region_idx)->increase_live_data_words(size);
76 } else {
77 int new_val = cur + size;
78 if (new_val >= max) {
79 // overflow, flush to region data
80 _heap->regions()->get(region_idx)->increase_live_data_words(new_val);
81 live_data[region_idx] = 0;
82 } else {
83 // still good, remember in locals
84 live_data[region_idx] = (jushort) new_val;
85 }
86 }
87 }
88
89 template <class T>
90 inline void ShenandoahConcurrentMark::do_chunked_array_start(ShenandoahObjToScanQueue* q, T* cl, oop obj) {
91 assert(obj->is_objArray(), "expect object array");
92 objArrayOop array = objArrayOop(obj);
93 int len = array->length();
94
95 if (len <= (int) ObjArrayMarkingStride*2) {
96 // A few slices only, process directly
97 array->oop_iterate_range(cl, 0, len);
98 } else {
99 int bits = log2_long(len);
100 // Compensate for non-power-of-two arrays, cover the array in excess:
101 if (len != (1 << bits)) bits++;
102
103 // Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to
104 // boundaries against array->length(), touching the array header on every chunk.
105 //
106 // To do this, we cut the prefix in full-sized chunks, and submit them on the queue.
107 // If the array is not divided in chunk sizes, then there would be an irregular tail,
108 // which we will process separately.
109
110 int last_idx = 0;
111
112 int chunk = 1;
113 int pow = bits;
114
115 // Handle overflow
116 if (pow >= 31) {
117 assert (pow == 31, "sanity");
118 pow--;
119 chunk = 2;
120 last_idx = (1 << pow);
121 bool pushed = q->push(ShenandoahMarkTask(array, 1, pow));
122 assert(pushed, "overflow queue should always succeed pushing");
123 }
124
125 // Split out tasks, as suggested in ObjArrayChunkedTask docs. Record the last
126 // successful right boundary to figure out the irregular tail.
127 while ((1 << pow) > (int)ObjArrayMarkingStride &&
128 (chunk*2 < ShenandoahMarkTask::chunk_size())) {
129 pow--;
130 int left_chunk = chunk*2 - 1;
131 int right_chunk = chunk*2;
132 int left_chunk_end = left_chunk * (1 << pow);
133 if (left_chunk_end < len) {
134 bool pushed = q->push(ShenandoahMarkTask(array, left_chunk, pow));
135 assert(pushed, "overflow queue should always succeed pushing");
136 chunk = right_chunk;
137 last_idx = left_chunk_end;
138 } else {
139 chunk = left_chunk;
140 }
141 }
142
143 // Process the irregular tail, if present
144 int from = last_idx;
145 if (from < len) {
146 array->oop_iterate_range(cl, from, len);
147 }
148 }
149 }
150
151 template <class T>
152 inline void ShenandoahConcurrentMark::do_chunked_array(ShenandoahObjToScanQueue* q, T* cl, oop obj, int chunk, int pow) {
153 assert(obj->is_objArray(), "expect object array");
154 objArrayOop array = objArrayOop(obj);
155
156 assert (ObjArrayMarkingStride > 0, "sanity");
157
158 // Split out tasks, as suggested in ObjArrayChunkedTask docs. Avoid pushing tasks that
159 // are known to start beyond the array.
160 while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < ShenandoahMarkTask::chunk_size())) {
161 pow--;
162 chunk *= 2;
163 bool pushed = q->push(ShenandoahMarkTask(array, chunk - 1, pow));
164 assert(pushed, "overflow queue should always succeed pushing");
165 }
166
167 int chunk_size = 1 << pow;
168
169 int from = (chunk - 1) * chunk_size;
170 int to = chunk * chunk_size;
171
172 #ifdef ASSERT
173 int len = array->length();
174 assert (0 <= from && from < len, "from is sane: %d/%d", from, len);
175 assert (0 < to && to <= len, "to is sane: %d/%d", to, len);
176 #endif
177
178 array->oop_iterate_range(cl, from, to);
179 }
180
181 inline bool ShenandoahConcurrentMark::try_queue(ShenandoahObjToScanQueue* q, ShenandoahMarkTask &task) {
182 return (q->pop_buffer(task) ||
183 q->pop_local(task) ||
184 q->pop_overflow(task));
185 }
186
187 class ShenandoahSATBBufferClosure : public SATBBufferClosure {
188 private:
189 ShenandoahObjToScanQueue* _queue;
190 ShenandoahHeap* _heap;
191 public:
192 ShenandoahSATBBufferClosure(ShenandoahObjToScanQueue* q) :
193 _queue(q), _heap(ShenandoahHeap::heap())
194 {
195 }
196
197 void do_buffer(void** buffer, size_t size) {
198 for (size_t i = 0; i < size; ++i) {
199 oop* p = (oop*) &buffer[i];
200 ShenandoahConcurrentMark::mark_through_ref<oop, RESOLVE>(p, _heap, _queue);
201 }
202 }
203 };
204
205 inline bool ShenandoahConcurrentMark::try_draining_satb_buffer(ShenandoahObjToScanQueue *q, ShenandoahMarkTask &task) {
206 ShenandoahSATBBufferClosure cl(q);
207 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
208 bool had_refs = satb_mq_set.apply_closure_to_completed_buffer(&cl);
209 return had_refs && try_queue(q, task);
210 }
211
212 template<class T, UpdateRefsMode UPDATE_REFS>
213 inline void ShenandoahConcurrentMark::mark_through_ref(T *p, ShenandoahHeap* heap, ShenandoahObjToScanQueue* q) {
214 T o = oopDesc::load_heap_oop(p);
215 if (! oopDesc::is_null(o)) {
216 oop obj = oopDesc::decode_heap_oop_not_null(o);
217 switch (UPDATE_REFS) {
218 case NONE:
219 break;
220 case RESOLVE:
221 obj = ShenandoahBarrierSet::resolve_oop_static_not_null(obj);
222 break;
223 case SIMPLE:
224 // We piggy-back reference updating to the marking tasks.
225 obj = heap->update_oop_ref_not_null(p, obj);
226 break;
227 case CONCURRENT:
228 obj = heap->maybe_update_oop_ref_not_null(p, obj);
229 break;
230 default:
231 ShouldNotReachHere();
232 }
233 assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static(obj)), "need to-space object here");
234
235 // Note: Only when concurrently updating references can obj become NULL here.
236 // It happens when a mutator thread beats us by writing another value. In that
237 // case we don't need to do anything else.
238 if (UPDATE_REFS != CONCURRENT || !oopDesc::is_null(obj)) {
239 assert(!oopDesc::is_null(obj), "Must not be null here");
240 assert(heap->is_in(obj), "We shouldn't be calling this on objects not in the heap: " PTR_FORMAT, p2i(obj));
241 assert(oopDesc::bs()->is_safe(obj), "Only mark objects in from-space");
242
243 if (heap->mark(obj)) {
244 log_develop_trace(gc, marking)("Marked obj: " PTR_FORMAT, p2i((HeapWord*) obj));
245
246 bool pushed = q->push(ShenandoahMarkTask(obj));
247 assert(pushed, "overflow queue should always succeed pushing");
248 } else {
249 log_develop_trace(gc, marking)("Failed to mark obj (already marked): " PTR_FORMAT, p2i((HeapWord*) obj));
250 assert(heap->is_marked(obj), "Consistency: should be marked.");
251 }
252 }
253 }
254 }
255
256 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP