1 /*
2 * Copyright (c) 1997, 2013, 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 class SerialOldTracer;
40 class STWGCTimer;
41
42 // MarkSweep takes care of global mark-compact garbage collection for a
43 // GenCollectedHeap using a four-phase pointer forwarding algorithm. All
44 // generations are assumed to support marking; those that can also support
45 // compaction.
46 //
47 // Class unloading will only occur when a full gc is invoked.
48
49 // declared at end
50 class PreservedMark;
51
52 class MarkSweep : AllStatic {
53 //
54 // Inline closure decls
55 //
56 class FollowRootClosure: public OopsInGenClosure {
57 public:
58 virtual void do_oop(oop* p);
59 virtual void do_oop(narrowOop* p);
60 };
61
62 class MarkAndPushClosure: public OopClosure {
63 public:
64 virtual void do_oop(oop* p);
65 virtual void do_oop(narrowOop* p);
66 };
67
68 // The one and only place to start following the classes.
69 // Should only be applied to the ClassLoaderData klasses list.
70 class FollowKlassClosure : public KlassClosure {
71 public:
72 void do_klass(Klass* klass);
73 };
74 class AdjustKlassClosure : public KlassClosure {
75 public:
76 void do_klass(Klass* klass);
77 };
78
79 class FollowStackClosure: public VoidClosure {
80 public:
81 virtual void do_void();
82 };
83
84 class AdjustPointerClosure: public OopsInGenClosure {
85 public:
86 virtual void do_oop(oop* p);
87 virtual void do_oop(narrowOop* p);
88 };
89
90 // Used for java/lang/ref handling
91 class IsAliveClosure: public BoolObjectClosure {
92 public:
93 virtual bool do_object_b(oop p);
94 };
95
96 class KeepAliveClosure: public OopClosure {
97 protected:
98 template <class T> void do_oop_work(T* p);
99 public:
100 virtual void do_oop(oop* p);
101 virtual void do_oop(narrowOop* p);
102 };
103
104 //
105 // Friend decls
106 //
107 friend class AdjustPointerClosure;
108 friend class KeepAliveClosure;
109 friend class VM_MarkSweep;
110 friend void marksweep_init();
111
112 //
113 // Vars
114 //
115 protected:
116 // Total invocations of a MarkSweep collection
117 static uint _total_invocations;
118
119 // Traversal stacks used during phase1
120 static Stack<oop, mtGC> _marking_stack;
121 static Stack<ObjArrayTask, mtGC> _objarray_stack;
122
123 // Space for storing/restoring mark word
124 static Stack<markOop, mtGC> _preserved_mark_stack;
125 static Stack<oop, mtGC> _preserved_oop_stack;
126 static size_t _preserved_count;
127 static size_t _preserved_count_max;
128 static PreservedMark* _preserved_marks;
129
130 // Reference processing (used in ...follow_contents)
131 static ReferenceProcessor* _ref_processor;
132
133 static STWGCTimer* _gc_timer;
134 static SerialOldTracer* _gc_tracer;
135
136 // Non public closures
137 static KeepAliveClosure keep_alive;
138
139 // Debugging
140 static void trace(const char* msg) PRODUCT_RETURN;
141
142 public:
143 // Public closures
144 static IsAliveClosure is_alive;
145 static FollowRootClosure follow_root_closure;
146 static MarkAndPushClosure mark_and_push_closure;
147 static FollowKlassClosure follow_klass_closure;
148 static FollowStackClosure follow_stack_closure;
149 static AdjustPointerClosure adjust_pointer_closure;
150 static AdjustKlassClosure adjust_klass_closure;
151
152 // Accessors
153 static uint total_invocations() { return _total_invocations; }
154
155 // Reference Processing
156 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
157
158 static STWGCTimer* gc_timer() { return _gc_timer; }
159 static SerialOldTracer* gc_tracer() { return _gc_tracer; }
160
161 // Call backs for marking
162 static void mark_object(oop obj);
163 // Mark pointer and follow contents. Empty marking stack afterwards.
164 template <class T> static inline void follow_root(T* p);
165
166 // Check mark and maybe push on marking stack
167 template <class T> static void mark_and_push(T* p);
168
169 static inline void push_objarray(oop obj, size_t index);
170
171 static void follow_stack(); // Empty marking stack.
172
173 static void follow_klass(Klass* klass);
174
175 static void follow_class_loader(ClassLoaderData* cld);
176
177 static void preserve_mark(oop p, markOop mark);
178 // Save the mark word so it can be restored later
179 static void adjust_marks(); // Adjust the pointers in the preserved marks table
180 static void restore_marks(); // Restore the marks that we saved in preserve_mark
181
182 template <class T> static inline void adjust_pointer(T* p);
183 };
184
185 class PreservedMark VALUE_OBJ_CLASS_SPEC {
186 private:
187 oop _obj;
188 markOop _mark;
189
190 public:
191 void init(oop obj, markOop mark) {
192 _obj = obj;
193 _mark = mark;
194 }
195
196 void adjust_pointer() {
197 MarkSweep::adjust_pointer(&_obj);
198 }
199
200 void restore() {
201 _obj->set_mark(_mark);
202 }
203 };
204
205 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP