1 /*
2 * Copyright (c) 2017, 2018, 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/g1/g1FullGCCompactionPoint.hpp"
27 #include "gc/g1/heapRegion.hpp"
28 #include "oops/oop.inline.hpp"
29 #include "utilities/debug.hpp"
30
31 G1FullGCCompactionPoint::G1FullGCCompactionPoint() :
32 _current_region(NULL),
33 _threshold(NULL),
34 _compaction_top(NULL) {
35 _compaction_regions = new (ResourceObj::C_HEAP, mtGC) GrowableArray<HeapRegion*>(32, mtGC);
36 _compaction_region_iterator = _compaction_regions->begin();
37 }
38
39 G1FullGCCompactionPoint::~G1FullGCCompactionPoint() {
40 delete _compaction_regions;
41 }
42
43 void G1FullGCCompactionPoint::update() {
44 if (is_initialized()) {
45 _current_region->set_compaction_top(_compaction_top);
46 }
47 }
48
49 void G1FullGCCompactionPoint::initialize_values(bool init_threshold) {
50 _compaction_top = _current_region->compaction_top();
51 if (init_threshold) {
52 _threshold = _current_region->initialize_threshold();
53 }
54 }
55
56 bool G1FullGCCompactionPoint::has_regions() {
57 return !_compaction_regions->is_empty();
58 }
59
60 bool G1FullGCCompactionPoint::is_initialized() {
61 return _current_region != NULL;
62 }
63
64 void G1FullGCCompactionPoint::initialize(HeapRegion* hr, bool init_threshold) {
65 _current_region = hr;
66 initialize_values(init_threshold);
67 }
68
69 HeapRegion* G1FullGCCompactionPoint::current_region() {
70 return *_compaction_region_iterator;
71 }
72
73 HeapRegion* G1FullGCCompactionPoint::next_region() {
74 HeapRegion* next = *(++_compaction_region_iterator);
75 assert(next != NULL, "Must return valid region");
76 return next;
77 }
78
79 GrowableArray<HeapRegion*>* G1FullGCCompactionPoint::regions() {
80 return _compaction_regions;
81 }
82
83 bool G1FullGCCompactionPoint::object_will_fit(size_t size) {
84 size_t space_left = pointer_delta(_current_region->end(), _compaction_top);
85 return size <= space_left;
86 }
87
88 void G1FullGCCompactionPoint::switch_region() {
89 // Save compaction top in the region.
90 _current_region->set_compaction_top(_compaction_top);
91 // Get the next region and re-initialize the values.
92 _current_region = next_region();
93 initialize_values(true);
94 }
95
96 void G1FullGCCompactionPoint::forward(oop object, size_t size) {
97 assert(_current_region != NULL, "Must have been initialized");
98
99 // Ensure the object fit in the current region.
100 while (!object_will_fit(size)) {
101 switch_region();
102 }
103
104 // Store a forwarding pointer if the object should be moved.
105 if (cast_from_oop<HeapWord*>(object) != _compaction_top) {
106 object->forward_to(cast_to_oop(_compaction_top));
107 } else {
108 if (object->forwardee() != NULL) {
109 // Object should not move but mark-word is used so it looks like the
110 // object is forwarded. Need to clear the mark and it's no problem
111 // since it will be restored by preserved marks. There is an exception
112 // with BiasedLocking, in this case forwardee() will return NULL
113 // even if the mark-word is used. This is no problem since
114 // forwardee() will return NULL in the compaction phase as well.
115 object->init_mark();
116 } else {
117 // Make sure object has the correct mark-word set or that it will be
118 // fixed when restoring the preserved marks.
119 assert(object->mark() == markWord::prototype_for_klass(object->klass()) || // Correct mark
120 object->mark_must_be_preserved() || // Will be restored by PreservedMarksSet
121 (UseBiasedLocking && object->has_bias_pattern()), // Will be restored by BiasedLocking
122 "should have correct prototype obj: " PTR_FORMAT " mark: " PTR_FORMAT " prototype: " PTR_FORMAT,
123 p2i(object), object->mark().value(), markWord::prototype_for_klass(object->klass()).value());
124 }
125 assert(object->forwardee() == NULL, "should be forwarded to NULL");
126 }
127
128 // Update compaction values.
129 _compaction_top += size;
130 if (_compaction_top > _threshold) {
131 _threshold = _current_region->cross_threshold(_compaction_top - size, _compaction_top);
132 }
133 }
134
135 void G1FullGCCompactionPoint::add(HeapRegion* hr) {
136 _compaction_regions->append(hr);
137 }
138
139 HeapRegion* G1FullGCCompactionPoint::remove_last() {
140 return _compaction_regions->pop();
141 }