1 /*
2 * Copyright (c) 1997, 2015, 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/genOopClosures.hpp"
30 #include "memory/iterator.hpp"
31 #include "oops/markOop.hpp"
32 #include "oops/oop.hpp"
33 #include "runtime/timer.hpp"
34 #include "utilities/growableArray.hpp"
35 #include "utilities/stack.hpp"
36 #include "utilities/taskqueue.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
53 class MarkSweep : AllStatic {
54 //
55 // Inline closure decls
56 //
57 class FollowRootClosure: public OopsInGenClosure {
58 public:
59 virtual void do_oop(oop* p);
60 virtual void do_oop(narrowOop* p);
61 };
62
63 class MarkAndPushClosure: public OopClosure {
64 public:
65 virtual void do_oop(oop* p);
66 virtual void do_oop(narrowOop* p);
67 };
68
69 class FollowStackClosure: public VoidClosure {
70 public:
71 virtual void do_void();
72 };
73
74 class AdjustPointerClosure: public OopsInGenClosure {
75 public:
76 virtual void do_oop(oop* p);
77 virtual void do_oop(narrowOop* p);
78 };
79
80 // Used for java/lang/ref handling
81 class IsAliveClosure: public BoolObjectClosure {
82 public:
83 virtual bool do_object_b(oop p);
84 };
85
86 class KeepAliveClosure: public OopClosure {
87 protected:
88 template <class T> void do_oop_work(T* p);
89 public:
90 virtual void do_oop(oop* p);
91 virtual void do_oop(narrowOop* p);
92 };
93
94 //
95 // Friend decls
96 //
97 friend class AdjustPointerClosure;
98 friend class KeepAliveClosure;
99 friend class VM_MarkSweep;
100 friend void marksweep_init();
101
102 //
103 // Vars
104 //
105 protected:
106 // Total invocations of a MarkSweep collection
107 static uint _total_invocations;
108
109 // Traversal stacks used during phase1
110 static Stack<oop, mtGC> _marking_stack;
111 static Stack<ObjArrayTask, mtGC> _objarray_stack;
112
113 // Space for storing/restoring mark word
114 static Stack<markOop, mtGC> _preserved_mark_stack;
115 static Stack<oop, mtGC> _preserved_oop_stack;
116 static size_t _preserved_count;
117 static size_t _preserved_count_max;
118 static PreservedMark* _preserved_marks;
119
120 // Reference processing (used in ...follow_contents)
121 static ReferenceProcessor* _ref_processor;
122
123 static STWGCTimer* _gc_timer;
124 static SerialOldTracer* _gc_tracer;
125
126 // Non public closures
127 static KeepAliveClosure keep_alive;
128
129 // Debugging
130 static void trace(const char* msg) PRODUCT_RETURN;
131
132 public:
133 // Public closures
134 static IsAliveClosure is_alive;
135 static FollowRootClosure follow_root_closure;
136 static MarkAndPushClosure mark_and_push_closure;
137 static FollowStackClosure follow_stack_closure;
138 static CLDToOopClosure follow_cld_closure;
139 static AdjustPointerClosure adjust_pointer_closure;
140 static CLDToOopClosure adjust_cld_closure;
141
142 // Accessors
143 static uint total_invocations() { return _total_invocations; }
144
145 // Reference Processing
146 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
147
148 static STWGCTimer* gc_timer() { return _gc_timer; }
149 static SerialOldTracer* gc_tracer() { return _gc_tracer; }
150
151 // Call backs for marking
152 static void mark_object(oop obj);
153 // Mark pointer and follow contents. Empty marking stack afterwards.
154 template <class T> static inline void follow_root(T* p);
155
156 // Check mark and maybe push on marking stack
157 template <class T> static void mark_and_push(T* p);
158
159 static inline void push_objarray(oop obj, size_t index);
160
161 static void follow_stack(); // Empty marking stack.
162
163 static void follow_object(oop obj);
164
165 static void follow_array(objArrayOop array, int index);
166
167 static void follow_klass(Klass* klass);
168
169 static void follow_class_loader(ClassLoaderData* cld);
170
171 static int adjust_pointers(oop obj);
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 void restore();
194 };
195
196 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP