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