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.
22 *
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 SlidingForwarding;
43 class STWGCTimer;
44
45 // MarkSweep takes care of global mark-compact garbage collection for a
46 // GenCollectedHeap using a four-phase pointer forwarding algorithm. All
47 // generations are assumed to support marking; those that can also support
48 // compaction.
49 //
50 // Class unloading will only occur when a full gc is invoked.
51
52 // declared at end
53 class PreservedMark;
54 class MarkAndPushClosure;
55 class AdjustPointerClosure;
56
57 class MarkSweep : AllStatic {
58 //
59 // Inline closure decls
60 //
61 class FollowRootClosure: public BasicOopIterateClosure {
62 public:
63 virtual void do_oop(oop* p);
64 virtual void do_oop(narrowOop* p);
65 };
66
67 class FollowStackClosure: public VoidClosure {
68 public:
69 virtual void do_void();
70 };
71
72 // Used for java/lang/ref handling
73 class IsAliveClosure: public BoolObjectClosure {
74 public:
75 virtual bool do_object_b(oop p);
76 };
77
78 class KeepAliveClosure: public OopClosure {
79 protected:
80 template <class T> void do_oop_work(T* p);
81 public:
82 virtual void do_oop(oop* p);
83 virtual void do_oop(narrowOop* p);
84 };
85
86 //
87 // Friend decls
88 //
89 friend class AdjustPointerClosure;
90 friend class KeepAliveClosure;
91 friend class VM_MarkSweep;
92
93 //
94 // Vars
95 //
96 protected:
97 // Total invocations of a MarkSweep collection
98 static uint _total_invocations;
99
100 // Traversal stacks used during phase1
101 static Stack<oop, mtGC> _marking_stack;
102 static Stack<ObjArrayTask, mtGC> _objarray_stack;
103
104 // Space for storing/restoring mark word
105 static Stack<PreservedMark, mtGC> _preserved_overflow_stack;
106 static size_t _preserved_count;
107 static size_t _preserved_count_max;
108 static PreservedMark* _preserved_marks;
109
110 // Reference processing (used in ...follow_contents)
111 static ReferenceProcessor* _ref_processor;
112
113 static STWGCTimer* _gc_timer;
114 static SerialOldTracer* _gc_tracer;
115
116 static StringDedup::Requests* _string_dedup_requests;
117
118 // Non public closures
119 static KeepAliveClosure keep_alive;
120
121 public:
122 static void initialize();
123
124 // Public closures
125 static IsAliveClosure is_alive;
126 static FollowRootClosure follow_root_closure;
127 static MarkAndPushClosure mark_and_push_closure;
128 static FollowStackClosure follow_stack_closure;
129 static CLDToOopClosure follow_cld_closure;
130
131 // Accessors
132 static uint total_invocations() { return _total_invocations; }
133
134 // Reference Processing
135 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
136 static void set_ref_processor(ReferenceProcessor* rp);
137
138 static STWGCTimer* gc_timer() { return _gc_timer; }
139 static SerialOldTracer* gc_tracer() { return _gc_tracer; }
140
141 static void preserve_mark(oop p, markWord mark);
142 // Save the mark word so it can be restored later
143 static void adjust_marks(); // Adjust the pointers in the preserved marks table
144 static void restore_marks(); // Restore the marks that we saved in preserve_mark
145
146 static size_t adjust_pointers(const SlidingForwarding* const forwarding, oop obj);
147
148 static void follow_stack(); // Empty marking stack.
149
150 static void follow_klass(Klass* klass);
151
152 static void follow_cld(ClassLoaderData* cld);
153
154 template <class T> static inline void adjust_pointer(const SlidingForwarding* const forwarding, 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 private:
160 // Call backs for marking
161 static void mark_object(oop obj);
162 // Mark pointer and follow contents. Empty marking stack afterwards.
163 template <class T> static inline void follow_root(T* p);
164
165 static inline void push_objarray(oop obj, size_t index);
166
167 static void follow_object(oop obj);
168
169 static void follow_array(objArrayOop array);
170
171 static void follow_array_chunk(objArrayOop array, int index);
172 };
173
174 class MarkAndPushClosure: public OopIterateClosure {
175 public:
176 template <typename T> void do_oop_work(T* p);
177 virtual void do_oop(oop* p);
178 virtual void do_oop(narrowOop* p);
179
180 virtual bool do_metadata() { return true; }
181 virtual void do_klass(Klass* k);
182 virtual void do_cld(ClassLoaderData* cld);
183
184 void set_ref_discoverer(ReferenceDiscoverer* rd) {
185 set_ref_discoverer_internal(rd);
186 }
187 };
188
189 class AdjustPointerClosure: public BasicOopIterateClosure {
190 private:
191 const SlidingForwarding* const _forwarding;
192 public:
193 AdjustPointerClosure(const SlidingForwarding* forwarding) : _forwarding(forwarding) {}
194 template <typename T> void do_oop_work(T* p);
195 virtual void do_oop(oop* p);
196 virtual void do_oop(narrowOop* p);
197 virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
198 };
199
200 class PreservedMark {
201 private:
202 oop _obj;
203 markWord _mark;
204
205 public:
206 PreservedMark(oop obj, markWord mark) : _obj(obj), _mark(mark) {}
207 void adjust_pointer(const SlidingForwarding* const forwarding);
208 void restore();
209 };
210
211 #endif // SHARE_GC_SERIAL_MARKSWEEP_HPP