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comparison src/share/vm/gc_implementation/shared/markSweep.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ba764ed4b6f2 |
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1 /* | |
2 * Copyright 1997-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 class ReferenceProcessor; | |
26 | |
27 // MarkSweep takes care of global mark-compact garbage collection for a | |
28 // GenCollectedHeap using a four-phase pointer forwarding algorithm. All | |
29 // generations are assumed to support marking; those that can also support | |
30 // compaction. | |
31 // | |
32 // Class unloading will only occur when a full gc is invoked. | |
33 | |
34 // If VALIDATE_MARK_SWEEP is defined, the -XX:+ValidateMarkSweep flag will | |
35 // be operational, and will provide slow but comprehensive self-checks within | |
36 // the GC. This is not enabled by default in product or release builds, | |
37 // since the extra call to track_adjusted_pointer() in _adjust_pointer() | |
38 // would be too much overhead, and would disturb performance measurement. | |
39 // However, debug builds are sometimes way too slow to run GC tests! | |
40 #ifdef ASSERT | |
41 #define VALIDATE_MARK_SWEEP 1 | |
42 #endif | |
43 #ifdef VALIDATE_MARK_SWEEP | |
44 #define VALIDATE_MARK_SWEEP_ONLY(code) code | |
45 #else | |
46 #define VALIDATE_MARK_SWEEP_ONLY(code) | |
47 #endif | |
48 | |
49 | |
50 // declared at end | |
51 class PreservedMark; | |
52 | |
53 class MarkSweep : AllStatic { | |
54 // | |
55 // In line closure decls | |
56 // | |
57 | |
58 class FollowRootClosure: public OopsInGenClosure{ | |
59 public: | |
60 void do_oop(oop* p) { follow_root(p); } | |
61 virtual const bool do_nmethods() const { return true; } | |
62 }; | |
63 | |
64 class MarkAndPushClosure: public OopClosure { | |
65 public: | |
66 void do_oop(oop* p) { mark_and_push(p); } | |
67 virtual const bool do_nmethods() const { return true; } | |
68 }; | |
69 | |
70 class FollowStackClosure: public VoidClosure { | |
71 public: | |
72 void do_void() { follow_stack(); } | |
73 }; | |
74 | |
75 class AdjustPointerClosure: public OopsInGenClosure { | |
76 bool _is_root; | |
77 public: | |
78 AdjustPointerClosure(bool is_root) : _is_root(is_root) {} | |
79 void do_oop(oop* p) { _adjust_pointer(p, _is_root); } | |
80 }; | |
81 | |
82 // Used for java/lang/ref handling | |
83 class IsAliveClosure: public BoolObjectClosure { | |
84 public: | |
85 void do_object(oop p) { assert(false, "don't call"); } | |
86 bool do_object_b(oop p) { return p->is_gc_marked(); } | |
87 }; | |
88 | |
89 class KeepAliveClosure: public OopClosure { | |
90 public: | |
91 void do_oop(oop* p); | |
92 }; | |
93 | |
94 // | |
95 // Friend decls | |
96 // | |
97 | |
98 friend class AdjustPointerClosure; | |
99 friend class KeepAliveClosure; | |
100 friend class VM_MarkSweep; | |
101 friend void marksweep_init(); | |
102 | |
103 // | |
104 // Vars | |
105 // | |
106 protected: | |
107 // Traversal stack used during phase1 | |
108 static GrowableArray<oop>* _marking_stack; | |
109 // Stack for live klasses to revisit at end of marking phase | |
110 static GrowableArray<Klass*>* _revisit_klass_stack; | |
111 | |
112 // Space for storing/restoring mark word | |
113 static GrowableArray<markOop>* _preserved_mark_stack; | |
114 static GrowableArray<oop>* _preserved_oop_stack; | |
115 static size_t _preserved_count; | |
116 static size_t _preserved_count_max; | |
117 static PreservedMark* _preserved_marks; | |
118 | |
119 // Reference processing (used in ...follow_contents) | |
120 static ReferenceProcessor* _ref_processor; | |
121 | |
122 #ifdef VALIDATE_MARK_SWEEP | |
123 static GrowableArray<oop*>* _root_refs_stack; | |
124 static GrowableArray<oop> * _live_oops; | |
125 static GrowableArray<oop> * _live_oops_moved_to; | |
126 static GrowableArray<size_t>* _live_oops_size; | |
127 static size_t _live_oops_index; | |
128 static size_t _live_oops_index_at_perm; | |
129 static GrowableArray<oop*>* _other_refs_stack; | |
130 static GrowableArray<oop*>* _adjusted_pointers; | |
131 static bool _pointer_tracking; | |
132 static bool _root_tracking; | |
133 | |
134 // The following arrays are saved since the time of the last GC and | |
135 // assist in tracking down problems where someone has done an errant | |
136 // store into the heap, usually to an oop that wasn't properly | |
137 // handleized across a GC. If we crash or otherwise fail before the | |
138 // next GC, we can query these arrays to find out the object we had | |
139 // intended to do the store to (assuming it is still alive) and the | |
140 // offset within that object. Covered under RecordMarkSweepCompaction. | |
141 static GrowableArray<HeapWord*> * _cur_gc_live_oops; | |
142 static GrowableArray<HeapWord*> * _cur_gc_live_oops_moved_to; | |
143 static GrowableArray<size_t>* _cur_gc_live_oops_size; | |
144 static GrowableArray<HeapWord*> * _last_gc_live_oops; | |
145 static GrowableArray<HeapWord*> * _last_gc_live_oops_moved_to; | |
146 static GrowableArray<size_t>* _last_gc_live_oops_size; | |
147 #endif | |
148 | |
149 | |
150 // Non public closures | |
151 static IsAliveClosure is_alive; | |
152 static KeepAliveClosure keep_alive; | |
153 | |
154 // Class unloading. Update subklass/sibling/implementor links at end of marking phase. | |
155 static void follow_weak_klass_links(); | |
156 | |
157 // Debugging | |
158 static void trace(const char* msg) PRODUCT_RETURN; | |
159 | |
160 public: | |
161 // Public closures | |
162 static FollowRootClosure follow_root_closure; | |
163 static MarkAndPushClosure mark_and_push_closure; | |
164 static FollowStackClosure follow_stack_closure; | |
165 static AdjustPointerClosure adjust_root_pointer_closure; | |
166 static AdjustPointerClosure adjust_pointer_closure; | |
167 | |
168 // Reference Processing | |
169 static ReferenceProcessor* const ref_processor() { return _ref_processor; } | |
170 | |
171 // Call backs for marking | |
172 static void mark_object(oop obj); | |
173 static void follow_root(oop* p); // Mark pointer and follow contents. Empty marking | |
174 | |
175 // stack afterwards. | |
176 | |
177 static void mark_and_follow(oop* p); // Mark pointer and follow contents. | |
178 static void _mark_and_push(oop* p); // Mark pointer and push obj on | |
179 // marking stack. | |
180 | |
181 | |
182 static void mark_and_push(oop* p) { // Check mark and maybe push on | |
183 // marking stack | |
184 // assert(Universe::is_reserved_heap((oop)p), "we should only be traversing objects here"); | |
185 oop m = *p; | |
186 if (m != NULL && !m->mark()->is_marked()) { | |
187 _mark_and_push(p); | |
188 } | |
189 } | |
190 | |
191 static void follow_stack(); // Empty marking stack. | |
192 | |
193 | |
194 static void preserve_mark(oop p, markOop mark); // Save the mark word so it can be restored later | |
195 static void adjust_marks(); // Adjust the pointers in the preserved marks table | |
196 static void restore_marks(); // Restore the marks that we saved in preserve_mark | |
197 | |
198 static void _adjust_pointer(oop* p, bool isroot); | |
199 | |
200 static void adjust_root_pointer(oop* p) { _adjust_pointer(p, true); } | |
201 static void adjust_pointer(oop* p) { _adjust_pointer(p, false); } | |
202 | |
203 #ifdef VALIDATE_MARK_SWEEP | |
204 static void track_adjusted_pointer(oop* p, oop newobj, bool isroot); | |
205 static void check_adjust_pointer(oop* p); // Adjust this pointer | |
206 static void track_interior_pointers(oop obj); | |
207 static void check_interior_pointers(); | |
208 | |
209 static void reset_live_oop_tracking(bool at_perm); | |
210 static void register_live_oop(oop p, size_t size); | |
211 static void validate_live_oop(oop p, size_t size); | |
212 static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top); | |
213 static void compaction_complete(); | |
214 | |
215 // Querying operation of RecordMarkSweepCompaction results. | |
216 // Finds and prints the current base oop and offset for a word | |
217 // within an oop that was live during the last GC. Helpful for | |
218 // tracking down heap stomps. | |
219 static void print_new_location_of_heap_address(HeapWord* q); | |
220 #endif | |
221 | |
222 // Call backs for class unloading | |
223 static void revisit_weak_klass_link(Klass* k); // Update subklass/sibling/implementor links at end of marking. | |
224 }; | |
225 | |
226 | |
227 class PreservedMark VALUE_OBJ_CLASS_SPEC { | |
228 private: | |
229 oop _obj; | |
230 markOop _mark; | |
231 | |
232 public: | |
233 void init(oop obj, markOop mark) { | |
234 _obj = obj; | |
235 _mark = mark; | |
236 } | |
237 | |
238 void adjust_pointer() { | |
239 MarkSweep::adjust_pointer(&_obj); | |
240 } | |
241 | |
242 void restore() { | |
243 _obj->set_mark(_mark); | |
244 } | |
245 }; |