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 ExtendedOopClosure { 64 public: 65 template <typename T> void do_oop_nv(T* p); 66 virtual void do_oop(oop* p); 67 virtual void do_oop(narrowOop* p); 68 }; 69 70 class FollowStackClosure: public VoidClosure { 71 public: 72 virtual void do_void(); 73 }; 74 75 class AdjustPointerClosure: public OopsInGenClosure { 76 public: 77 template <typename T> void do_oop_nv(T* p); 78 virtual void do_oop(oop* p); 79 virtual void do_oop(narrowOop* p); 80 81 // This closure provides its own oop verification code. 82 debug_only(virtual bool should_verify_oops() { return false; }) 83 }; 84 85 // Used for java/lang/ref handling 86 class IsAliveClosure: public BoolObjectClosure { 87 public: 88 virtual bool do_object_b(oop p); 89 }; 90 91 class KeepAliveClosure: public OopClosure { 92 protected: 93 template <class T> void do_oop_work(T* p); 94 public: 95 virtual void do_oop(oop* p); 96 virtual void do_oop(narrowOop* p); 97 }; 98 99 // 100 // Friend decls 101 // 102 friend class AdjustPointerClosure; 103 friend class KeepAliveClosure; 104 friend class VM_MarkSweep; 105 friend void marksweep_init(); 106 107 // 108 // Vars 109 // 110 protected: 111 // Total invocations of a MarkSweep collection 112 static uint _total_invocations; 113 114 // Traversal stacks used during phase1 115 static Stack<oop, mtGC> _marking_stack; 116 static Stack<ObjArrayTask, mtGC> _objarray_stack; 117 118 // Space for storing/restoring mark word 119 static Stack<markOop, mtGC> _preserved_mark_stack; 120 static Stack<oop, mtGC> _preserved_oop_stack; 121 static size_t _preserved_count; 122 static size_t _preserved_count_max; 123 static PreservedMark* _preserved_marks; 124 125 // Reference processing (used in ...follow_contents) 126 static ReferenceProcessor* _ref_processor; 127 128 static STWGCTimer* _gc_timer; 129 static SerialOldTracer* _gc_tracer; 130 131 // Non public closures 132 static KeepAliveClosure keep_alive; 133 134 public: 135 // Public closures 136 static IsAliveClosure is_alive; 137 static FollowRootClosure follow_root_closure; 138 static MarkAndPushClosure mark_and_push_closure; 139 static FollowStackClosure follow_stack_closure; 140 static CLDToOopClosure follow_cld_closure; 141 static AdjustPointerClosure adjust_pointer_closure; 142 static CLDToOopClosure adjust_cld_closure; 143 144 // Accessors 145 static uint total_invocations() { return _total_invocations; } 146 147 // Reference Processing 148 static ReferenceProcessor* const ref_processor() { return _ref_processor; } 149 150 static STWGCTimer* gc_timer() { return _gc_timer; } 151 static SerialOldTracer* gc_tracer() { return _gc_tracer; } 152 153 // Call backs for marking 154 static void mark_object(oop obj); 155 // Mark pointer and follow contents. Empty marking stack afterwards. 156 template <class T> static inline void follow_root(T* p); 157 158 // Check mark and maybe push on marking stack 159 template <class T> static void mark_and_push(T* p); 160 161 static inline void push_objarray(oop obj, size_t index); 162 163 static void follow_stack(); // Empty marking stack. 164 165 static void follow_object(oop obj); 166 167 static void follow_array(objArrayOop array, int index); 168 169 static void follow_klass(Klass* klass); 170 171 static void follow_class_loader(ClassLoaderData* cld); 172 173 static int adjust_pointers(oop obj); 174 175 static void preserve_mark(oop p, markOop mark); 176 // Save the mark word so it can be restored later 177 static void adjust_marks(); // Adjust the pointers in the preserved marks table 178 static void restore_marks(); // Restore the marks that we saved in preserve_mark 179 180 template <class T> static inline void adjust_pointer(T* p); 181 }; 182 183 class PreservedMark VALUE_OBJ_CLASS_SPEC { 184 private: 185 oop _obj; 186 markOop _mark; 187 188 public: 189 void init(oop obj, markOop mark) { 190 _obj = obj; 191 _mark = mark; 192 } 193 194 void adjust_pointer(); 195 void restore(); 196 }; 197 198 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP