1 /*
2 * Copyright (c) 2016, 2018, Red Hat, Inc. All rights reserved.
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 #include "precompiled.hpp"
25
26 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
27 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
28 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
29 #include "gc/shenandoah/shenandoahUtils.hpp"
30 #include "runtime/atomic.hpp"
31 #include "utilities/copy.hpp"
32
33 ShenandoahCollectionSet::ShenandoahCollectionSet(ShenandoahHeap* heap, HeapWord* heap_base) :
34 _map_size(heap->num_regions()),
35 _region_size_bytes_shift(ShenandoahHeapRegion::region_size_bytes_shift()),
36 _cset_map(NEW_C_HEAP_ARRAY(jbyte, _map_size, mtGC)),
37 _biased_cset_map(_cset_map - ((uintx)heap_base >> _region_size_bytes_shift)),
38 _heap(heap),
39 _garbage(0),
40 _live_data(0),
41 _used(0),
42 _region_count(0),
43 _current_index(0) {
44 // Use 1-byte data type
45 STATIC_ASSERT(sizeof(jbyte) == 1);
46
47 // Initialize cset map
48 Copy::zero_to_bytes(_cset_map, _map_size);
49 }
50
51 void ShenandoahCollectionSet::add_region(ShenandoahHeapRegion* r) {
52 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
53 assert(Thread::current()->is_VM_thread(), "Must be VMThread");
54 assert(!is_in(r), "Already in collection set");
55 _cset_map[r->region_number()] = 1;
56 _region_count ++;
57 _garbage += r->garbage();
58 _live_data += r->get_live_data_bytes();
59 _used += r->used();
60 }
61
62 bool ShenandoahCollectionSet::add_region_check_for_duplicates(ShenandoahHeapRegion* r) {
63 if (!is_in(r)) {
64 add_region(r);
65 return true;
66 } else {
67 return false;
68 }
69 }
70
71 void ShenandoahCollectionSet::remove_region(ShenandoahHeapRegion* r) {
72 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
73 assert(Thread::current()->is_VM_thread(), "Must be VMThread");
74 assert(is_in(r), "Not in collection set");
75 _cset_map[r->region_number()] = 0;
76 _region_count --;
77 }
78
79 void ShenandoahCollectionSet::update_region_status() {
80 for (size_t index = 0; index < _heap->num_regions(); index ++) {
81 ShenandoahHeapRegion* r = _heap->get_region(index);
82 if (is_in(r)) {
83 r->make_cset();
84 } else {
85 assert (!r->is_cset(), "should not be cset");
86 }
87 }
88 }
89
90 void ShenandoahCollectionSet::clear() {
91 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
92 Copy::zero_to_bytes(_cset_map, _map_size);
93
94 #ifdef ASSERT
95 for (size_t index = 0; index < _heap->num_regions(); index ++) {
96 assert (!_heap->get_region(index)->is_cset(), "should have been cleared before");
97 }
98 #endif
99
100 _garbage = 0;
101 _live_data = 0;
102 _used = 0;
103
104 _region_count = 0;
105 _current_index = 0;
106 }
107
108 ShenandoahHeapRegion* ShenandoahCollectionSet::claim_next() {
109 size_t num_regions = _heap->num_regions();
110 if (_current_index >= (jint)num_regions) {
111 return NULL;
112 }
113
114 jint saved_current = _current_index;
115 size_t index = (size_t)saved_current;
116
117 while(index < num_regions) {
118 if (is_in(index)) {
119 jint cur = Atomic::cmpxchg((jint)(index + 1), &_current_index, saved_current);
120 assert(cur >= (jint)saved_current, "Must move forward");
121 if (cur == saved_current) {
122 assert(is_in(index), "Invariant");
123 return _heap->get_region(index);
124 } else {
125 index = (size_t)cur;
126 saved_current = cur;
127 }
128 } else {
129 index ++;
130 }
131 }
132 return NULL;
133 }
134
135 ShenandoahHeapRegion* ShenandoahCollectionSet::next() {
136 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
137 assert(Thread::current()->is_VM_thread(), "Must be VMThread");
138 size_t num_regions = _heap->num_regions();
139 for (size_t index = (size_t)_current_index; index < num_regions; index ++) {
140 if (is_in(index)) {
141 _current_index = (jint)(index + 1);
142 return _heap->get_region(index);
143 }
144 }
145
146 return NULL;
147 }
148
149 void ShenandoahCollectionSet::print_on(outputStream* out) const {
150 out->print_cr("Collection Set : " SIZE_FORMAT "", count());
151
152 debug_only(size_t regions = 0;)
153 for (size_t index = 0; index < _heap->num_regions(); index ++) {
154 if (is_in(index)) {
155 _heap->get_region(index)->print_on(out);
156 debug_only(regions ++;)
157 }
158 }
159 assert(regions == count(), "Must match");
160 }