1 /*
2 * Copyright (c) 1997, 2019, 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/genOopClosures.hpp"
30 #include "gc/shared/taskqueue.hpp"
31 #include "memory/iterator.hpp"
32 #include "oops/markWord.hpp"
33 #include "oops/oop.hpp"
34 #include "runtime/timer.hpp"
35 #include "utilities/growableArray.hpp"
36 #include "utilities/stack.hpp"
37
38 class ReferenceProcessor;
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
54 class MarkSweep : AllStatic {
55 //
56 // Inline closure decls
57 //
58 class FollowRootClosure: public BasicOopIterateClosure {
59 public:
60 virtual void do_oop(oop* p);
61 virtual void do_oop(narrowOop* p);
62 };
63
64 class FollowStackClosure: public VoidClosure {
65 public:
66 virtual void do_void();
67 };
68
69 // Used for java/lang/ref handling
70 class IsAliveClosure: public BoolObjectClosure {
71 public:
72 virtual bool do_object_b(oop p);
73 };
74
75 class KeepAliveClosure: public OopClosure {
76 protected:
77 template <class T> void do_oop_work(T* p);
78 public:
79 virtual void do_oop(oop* p);
80 virtual void do_oop(narrowOop* p);
81 };
82
83 //
84 // Friend decls
85 //
86 friend class KeepAliveClosure;
87 friend class VM_MarkSweep;
88
89 //
90 // Vars
91 //
92 protected:
93 // Total invocations of a MarkSweep collection
94 static uint _total_invocations;
95
96 // Traversal stacks used during phase1
97 static Stack<oop, mtGC> _marking_stack;
98 static Stack<ObjArrayTask, mtGC> _objarray_stack;
99
100 // Space for storing/restoring mark word
101 static Stack<markWord, mtGC> _preserved_mark_stack;
102 static Stack<oop, mtGC> _preserved_oop_stack;
103 static size_t _preserved_count;
104 static size_t _preserved_count_max;
105 static PreservedMark* _preserved_marks;
106
107 // Reference processing (used in ...follow_contents)
108 static ReferenceProcessor* _ref_processor;
109
110 static STWGCTimer* _gc_timer;
111 static SerialOldTracer* _gc_tracer;
112
113 // Non public closures
114 static KeepAliveClosure keep_alive;
115
116 public:
117 static void initialize();
118
119 // Public closures
120 static IsAliveClosure is_alive;
121 static FollowRootClosure follow_root_closure;
122 static MarkAndPushClosure mark_and_push_closure;
123 static FollowStackClosure follow_stack_closure;
124 static CLDToOopClosure follow_cld_closure;
125
126 // Accessors
127 static uint total_invocations() { return _total_invocations; }
128
129 // Reference Processing
130 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
131 static void set_ref_processor(ReferenceProcessor* rp);
132
133 static STWGCTimer* gc_timer() { return _gc_timer; }
134 static SerialOldTracer* gc_tracer() { return _gc_tracer; }
135
136 static void preserve_mark(oop p, markWord mark);
137 // Save the mark word so it can be restored later
138 template <bool ALT_FWD>
139 static void adjust_marks_impl(); // Adjust the pointers in the preserved marks table
140 static void adjust_marks(); // Adjust the pointers in the preserved marks table
141 static void restore_marks(); // Restore the marks that we saved in preserve_mark
142
143 template <bool ALT_FWD>
144 static int adjust_pointers(oop obj);
145
146 static void follow_stack(); // Empty marking stack.
147
148 static void follow_klass(Klass* klass);
149
150 static void follow_cld(ClassLoaderData* cld);
151
152 template <bool ALT_FWD, class T>
153 static inline void adjust_pointer(T* p);
154
155 // Check mark and maybe push on marking stack
156 template <class T> static void mark_and_push(T* p);
157
158 private:
159 // Call backs for marking
160 static void mark_object(oop obj);
161 // Mark pointer and follow contents. Empty marking stack afterwards.
162 template <class T> static inline void follow_root(T* p);
163
164 static inline void push_objarray(oop obj, size_t index);
165
166 static void follow_object(oop obj);
167
168 static void follow_array(objArrayOop array);
169
170 static void follow_array_chunk(objArrayOop array, int index);
171 };
172
173 class MarkAndPushClosure: public OopIterateClosure {
174 public:
175 template <typename T> void do_oop_work(T* p);
176 virtual void do_oop(oop* p);
177 virtual void do_oop(narrowOop* p);
178
179 virtual bool do_metadata() { return true; }
180 virtual void do_klass(Klass* k);
181 virtual void do_cld(ClassLoaderData* cld);
182
183 void set_ref_discoverer(ReferenceDiscoverer* rd) {
184 set_ref_discoverer_internal(rd);
185 }
186 };
187
188 template <bool ALT_FWD>
189 class AdjustPointerClosure: public BasicOopIterateClosure {
190 public:
191 template <typename T> void do_oop_work(T* p);
192 virtual void do_oop(oop* p);
193 virtual void do_oop(narrowOop* p);
194 virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
195 };
196
197 class PreservedMark {
198 private:
199 oop _obj;
200 markWord _mark;
201
202 public:
203 void init(oop obj, markWord mark) {
204 _obj = obj;
205 _mark = mark;
206 }
207
208 template <bool ALT_FWD>
209 void adjust_pointer();
210 void restore();
211 };
212
213 #endif // SHARE_GC_SERIAL_MARKSWEEP_HPP