1 /*
2 * Copyright (c) 1997, 2012, 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 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP
27
28 #include "gc_interface/collectedHeap.hpp"
29 #include "memory/universe.hpp"
30 #include "oops/markOop.hpp"
31 #include "oops/oop.hpp"
32 #include "runtime/timer.hpp"
33 #include "utilities/growableArray.hpp"
34 #include "utilities/stack.hpp"
35 #include "utilities/taskqueue.hpp"
36
37 class ReferenceProcessor;
38 class DataLayout;
39
40 // MarkSweep takes care of global mark-compact garbage collection for a
41 // GenCollectedHeap using a four-phase pointer forwarding algorithm. All
42 // generations are assumed to support marking; those that can also support
43 // compaction.
44 //
45 // Class unloading will only occur when a full gc is invoked.
46
47 // declared at end
48 class PreservedMark;
49
50 class MarkSweep : AllStatic {
51 //
52 // Inline closure decls
53 //
54 class FollowRootClosure: public OopsInGenClosure {
55 public:
56 virtual void do_oop(oop* p);
57 virtual void do_oop(narrowOop* p);
58 };
59
60 class MarkAndPushClosure: public OopClosure {
61 public:
62 virtual void do_oop(oop* p);
63 virtual void do_oop(narrowOop* p);
64 };
65
66 // The one and only place to start following the classes.
67 // Should only be applied to the ClassLoaderData klasses list.
68 class FollowKlassClosure : public KlassClosure {
69 public:
70 void do_klass(Klass* klass);
71 };
72 class AdjustKlassClosure : public KlassClosure {
73 public:
74 void do_klass(Klass* klass);
75 };
76
77 class FollowStackClosure: public VoidClosure {
78 public:
79 virtual void do_void();
80 };
81
82 class AdjustPointerClosure: public OopsInGenClosure {
83 public:
84 virtual void do_oop(oop* p);
85 virtual void do_oop(narrowOop* p);
86 };
87
88 // Used for java/lang/ref handling
89 class IsAliveClosure: public BoolObjectClosure {
90 public:
91 virtual void do_object(oop p);
92 virtual bool do_object_b(oop p);
93 };
94
95 class KeepAliveClosure: public OopClosure {
96 protected:
97 template <class T> void do_oop_work(T* p);
98 public:
99 virtual void do_oop(oop* p);
100 virtual void do_oop(narrowOop* p);
101 };
102
103 //
104 // Friend decls
105 //
106 friend class AdjustPointerClosure;
107 friend class KeepAliveClosure;
108 friend class VM_MarkSweep;
109 friend void marksweep_init();
110
111 //
112 // Vars
113 //
114 protected:
115 // Total invocations of a MarkSweep collection
116 static unsigned int _total_invocations;
117
118 // Traversal stacks used during phase1
119 static Stack<oop, mtGC> _marking_stack;
120 static Stack<ObjArrayTask, mtGC> _objarray_stack;
121
122 // Space for storing/restoring mark word
123 static Stack<markOop, mtGC> _preserved_mark_stack;
124 static Stack<oop, mtGC> _preserved_oop_stack;
125 static size_t _preserved_count;
126 static size_t _preserved_count_max;
127 static PreservedMark* _preserved_marks;
128
129 // Reference processing (used in ...follow_contents)
130 static ReferenceProcessor* _ref_processor;
131
132 // Non public closures
133 static KeepAliveClosure keep_alive;
134
135 // Debugging
136 static void trace(const char* msg) PRODUCT_RETURN;
137
138 public:
139 // Public closures
140 static IsAliveClosure is_alive;
141 static FollowRootClosure follow_root_closure;
142 static CodeBlobToOopClosure follow_code_root_closure; // => follow_root_closure
143 static MarkAndPushClosure mark_and_push_closure;
144 static FollowKlassClosure follow_klass_closure;
145 static FollowStackClosure follow_stack_closure;
146 static AdjustPointerClosure adjust_pointer_closure;
147 static AdjustKlassClosure adjust_klass_closure;
148
149 // Accessors
150 static unsigned int total_invocations() { return _total_invocations; }
151
152 // Reference Processing
153 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
154
155 // Call backs for marking
156 static void mark_object(oop obj);
157 // Mark pointer and follow contents. Empty marking stack afterwards.
158 template <class T> static inline void follow_root(T* p);
159
160 // Check mark and maybe push on marking stack
161 template <class T> static void mark_and_push(T* p);
162
163 static inline void push_objarray(oop obj, size_t index);
164
165 static void follow_stack(); // Empty marking stack.
166
167 static void follow_klass(Klass* klass);
168 static void adjust_klass(Klass* klass);
169
170 static void follow_class_loader(ClassLoaderData* cld);
171 static void adjust_class_loader(ClassLoaderData* cld);
172
173 static void preserve_mark(oop p, markOop mark);
174 // Save the mark word so it can be restored later
175 static void adjust_marks(); // Adjust the pointers in the preserved marks table
176 static void restore_marks(); // Restore the marks that we saved in preserve_mark
177
178 template <class T> static inline void adjust_pointer(T* p);
179 };
180
181 class PreservedMark VALUE_OBJ_CLASS_SPEC {
182 private:
183 oop _obj;
184 markOop _mark;
185
186 public:
187 void init(oop obj, markOop mark) {
188 _obj = obj;
189 _mark = mark;
190 }
191
192 void adjust_pointer() {
193 MarkSweep::adjust_pointer(&_obj);
194 }
195
196 void restore() {
197 _obj->set_mark(_mark);
198 }
199 };
200
201 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP