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/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 ReferenceProcessor;
40 class DataLayout;
41 class SerialOldTracer;
42 class STWGCTimer;
43
44 // MarkSweep takes care of global mark-compact garbage collection for a
45 // GenCollectedHeap using a four-phase pointer forwarding algorithm. All
46 // generations are assumed to support marking; those that can also support
47 // compaction.
48 //
49 // Class unloading will only occur when a full gc is invoked.
50
51 // declared at end
52 class PreservedMark;
53 class MarkAndPushClosure;
54 class AdjustPointerClosure;
55
56 class MarkSweep : AllStatic {
57 //
58 // Inline closure decls
59 //
60 class FollowRootClosure: public BasicOopIterateClosure {
61 public:
62 virtual void do_oop(oop* p);
63 virtual void do_oop(narrowOop* p);
64 };
65
66 class FollowStackClosure: public VoidClosure {
67 public:
68 virtual void do_void();
69 };
70
71 // Used for java/lang/ref handling
72 class IsAliveClosure: public BoolObjectClosure {
73 public:
74 virtual bool do_object_b(oop p);
75 };
76
77 class KeepAliveClosure: public OopClosure {
78 protected:
79 template <class T> void do_oop_work(T* p);
80 public:
81 virtual void do_oop(oop* p);
82 virtual void do_oop(narrowOop* p);
83 };
84
85 //
86 // Friend decls
87 //
88 friend class AdjustPointerClosure;
89 friend class KeepAliveClosure;
90 friend class VM_MarkSweep;
91
92 //
93 // Vars
94 //
95 protected:
96 // Total invocations of a MarkSweep collection
97 static uint _total_invocations;
98
99 // Traversal stacks used during phase1
100 static Stack<oop, mtGC> _marking_stack;
101 static Stack<ObjArrayTask, mtGC> _objarray_stack;
102
103 // Space for storing/restoring mark word
104 static Stack<PreservedMark, mtGC> _preserved_overflow_stack;
105 static size_t _preserved_count;
106 static size_t _preserved_count_max;
107 static PreservedMark* _preserved_marks;
108
109 // Reference processing (used in ...follow_contents)
110 static ReferenceProcessor* _ref_processor;
111
112 static STWGCTimer* _gc_timer;
113 static SerialOldTracer* _gc_tracer;
114
115 static StringDedup::Requests* _string_dedup_requests;
116
117 // Non public closures
118 static KeepAliveClosure keep_alive;
119
120 public:
121 static void initialize();
122
123 // Public closures
124 static IsAliveClosure is_alive;
125 static FollowRootClosure follow_root_closure;
126 static MarkAndPushClosure mark_and_push_closure;
127 static FollowStackClosure follow_stack_closure;
128 static CLDToOopClosure follow_cld_closure;
129 static AdjustPointerClosure adjust_pointer_closure;
130 static CLDToOopClosure adjust_cld_closure;
131
132 // Accessors
133 static uint total_invocations() { return _total_invocations; }
134
135 // Reference Processing
136 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
137 static void set_ref_processor(ReferenceProcessor* rp);
138
139 static STWGCTimer* gc_timer() { return _gc_timer; }
140 static SerialOldTracer* gc_tracer() { return _gc_tracer; }
141
142 static void preserve_mark(oop p, markWord mark);
143 // Save the mark word so it can be restored later
144 static void adjust_marks(); // Adjust the pointers in the preserved marks table
145 static void restore_marks(); // Restore the marks that we saved in preserve_mark
146
147 static size_t adjust_pointers(oop obj);
148
149 static void follow_stack(); // Empty marking stack.
150
151 static void follow_klass(Klass* klass);
152
153 static void follow_cld(ClassLoaderData* cld);
154
155 template <class T> static inline void adjust_pointer(T* p);
156
157 // Check mark and maybe push on marking stack
158 template <class T> static void mark_and_push(T* p);
159
160 private:
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 static inline void push_objarray(oop obj, size_t index);
167
168 static void follow_object(oop obj);
169
170 static void follow_array(objArrayOop array);
171
172 static void follow_array_chunk(objArrayOop array, int index);
173 };
174
175 class MarkAndPushClosure: public OopIterateClosure {
176 public:
177 template <typename T> void do_oop_work(T* p);
178 virtual void do_oop(oop* p);
179 virtual void do_oop(narrowOop* p);
180
181 virtual bool do_metadata() { return true; }
182 virtual void do_klass(Klass* k);
183 virtual void do_cld(ClassLoaderData* cld);
184
185 void set_ref_discoverer(ReferenceDiscoverer* rd) {
186 set_ref_discoverer_internal(rd);
187 }
188 };
189
190 class AdjustPointerClosure: public BasicOopIterateClosure {
191 public:
192 template <typename T> void do_oop_work(T* p);
193 virtual void do_oop(oop* p);
194 virtual void do_oop(narrowOop* p);
195 virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
196 };
197
198 class PreservedMark {
199 private:
200 oop _obj;
201 markWord _mark;
202
203 public:
204 PreservedMark(oop obj, markWord mark) : _obj(obj), _mark(mark) {}
205 void adjust_pointer();
206 void restore();
207 };
208
209 #endif // SHARE_GC_SERIAL_MARKSWEEP_HPP