1 /*
2 * Copyright (c) 1997, 2022, 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.
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23 */
24
25 #ifndef SHARE_GC_SERIAL_MARKSWEEP_HPP
26 #define SHARE_GC_SERIAL_MARKSWEEP_HPP
27
28 #include "gc/shared/collectedHeap.hpp"
29 #include "gc/shared/referenceProcessor.hpp"
30 #include "gc/shared/stringdedup/stringDedup.hpp"
31 #include "gc/shared/taskqueue.hpp"
32 #include "memory/iterator.hpp"
33 #include "oops/markWord.hpp"
34 #include "oops/oop.hpp"
35 #include "runtime/timer.hpp"
36 #include "utilities/growableArray.hpp"
37 #include "utilities/stack.hpp"
38
39 class DataLayout;
40 class SerialOldTracer;
41 class STWGCTimer;
42
43 // MarkSweep takes care of global mark-compact garbage collection for a
44 // GenCollectedHeap using a four-phase pointer forwarding algorithm. All
45 // generations are assumed to support marking; those that can also support
46 // compaction.
47 //
48 // Class unloading will only occur when a full gc is invoked.
49
50 // declared at end
51 class PreservedMark;
52 class MarkAndPushClosure;
53 class AdjustPointerClosure;
54
55 class MarkSweep : AllStatic {
56 //
57 // Inline closure decls
58 //
59 class FollowRootClosure: public BasicOopIterateClosure {
60 public:
61 virtual void do_oop(oop* p);
62 virtual void do_oop(narrowOop* p);
63 };
64
65 class FollowStackClosure: public VoidClosure {
66 public:
67 virtual void do_void();
68 };
69
70 // Used for java/lang/ref handling
71 class IsAliveClosure: public BoolObjectClosure {
72 public:
73 virtual bool do_object_b(oop p);
74 };
75
76 class KeepAliveClosure: public OopClosure {
77 protected:
78 template <class T> void do_oop_work(T* p);
79 public:
80 virtual void do_oop(oop* p);
81 virtual void do_oop(narrowOop* p);
82 };
83
84 //
85 // Friend decls
86 //
87 friend class AdjustPointerClosure;
88 friend class KeepAliveClosure;
89
90 //
91 // Vars
92 //
93 protected:
94 // Total invocations of a MarkSweep collection
95 static uint _total_invocations;
96
97 // Traversal stacks used during phase1
98 static Stack<oop, mtGC> _marking_stack;
99 static Stack<ObjArrayTask, mtGC> _objarray_stack;
100
101 // Space for storing/restoring mark word
102 static Stack<PreservedMark, mtGC> _preserved_overflow_stack;
103 static size_t _preserved_count;
104 static size_t _preserved_count_max;
105 static PreservedMark* _preserved_marks;
106
107 static AlwaysTrueClosure _always_true_closure;
108 static ReferenceProcessor* _ref_processor;
109
110 static STWGCTimer* _gc_timer;
111 static SerialOldTracer* _gc_tracer;
112
113 static StringDedup::Requests* _string_dedup_requests;
114
115 // Non public closures
116 static KeepAliveClosure keep_alive;
117
118 public:
119 static void initialize();
120
121 // Public closures
122 static IsAliveClosure is_alive;
123 static FollowRootClosure follow_root_closure;
124 static MarkAndPushClosure mark_and_push_closure;
125 static FollowStackClosure follow_stack_closure;
126 static CLDToOopClosure follow_cld_closure;
127 static AdjustPointerClosure adjust_pointer_closure;
128 static CLDToOopClosure adjust_cld_closure;
129
130 // Accessors
131 static uint total_invocations() { return _total_invocations; }
132
133 // Reference Processing
134 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
135
136 static STWGCTimer* gc_timer() { return _gc_timer; }
137 static SerialOldTracer* gc_tracer() { return _gc_tracer; }
138
139 static void preserve_mark(oop p, markWord mark);
140 // Save the mark word so it can be restored later
141 static void adjust_marks(); // Adjust the pointers in the preserved marks table
142 static void restore_marks(); // Restore the marks that we saved in preserve_mark
143
144 static size_t adjust_pointers(oop obj);
145
146 static void follow_stack(); // Empty marking stack.
147
148 template <class T> static inline void adjust_pointer(T* p);
149
150 // Check mark and maybe push on marking stack
151 template <class T> static void mark_and_push(T* p);
152
153 private:
154 // Call backs for marking
155 static void mark_object(oop obj);
156 // Mark pointer and follow contents. Empty marking stack afterwards.
157 template <class T> static inline void follow_root(T* p);
158
159 static inline void push_objarray(oop obj, size_t index);
160
161 static void follow_object(oop obj);
162
163 static void follow_array(objArrayOop array);
164
165 static void follow_array_chunk(objArrayOop array, int index);
166 };
167
168 class MarkAndPushClosure: public ClaimMetadataVisitingOopIterateClosure {
169 public:
170 MarkAndPushClosure(int claim) : ClaimMetadataVisitingOopIterateClosure(claim) {}
171
172 template <typename T> void do_oop_work(T* p);
173 virtual void do_oop( oop* p);
174 virtual void do_oop(narrowOop* p);
175
176 void set_ref_discoverer(ReferenceDiscoverer* rd) {
177 set_ref_discoverer_internal(rd);
178 }
179 };
180
181 class AdjustPointerClosure: public BasicOopIterateClosure {
182 public:
183 template <typename T> void do_oop_work(T* p);
184 virtual void do_oop(oop* p);
185 virtual void do_oop(narrowOop* p);
186 virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
187 };
188
189 class PreservedMark {
190 private:
191 oop _obj;
192 markWord _mark;
193
194 public:
195 PreservedMark(oop obj, markWord mark) : _obj(obj), _mark(mark) {}
196 void adjust_pointer();
197 void restore();
198 };
199
200 #endif // SHARE_GC_SERIAL_MARKSWEEP_HPP