1 /* 2 * Copyright (c) 2016, 2018, 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_SHARED_PRESERVEDMARKS_HPP 26 #define SHARE_VM_GC_SHARED_PRESERVEDMARKS_HPP 27 28 #include "memory/allocation.hpp" 29 #include "memory/padded.hpp" 30 #include "oops/oop.hpp" 31 #include "utilities/stack.hpp" 32 33 class PreservedMarksSet; 34 class WorkGang; 35 36 class PreservedMarks { 37 private: 38 class OopAndMarkOop { 39 private: 40 oop _o; 41 markOop _m; 42 43 public: 44 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { } 45 46 oop get_oop() { return _o; } 47 void set_mark() const { _o->set_mark(_m); } 48 void set_oop(oop obj) { _o = obj; } 49 }; 50 typedef Stack<OopAndMarkOop, mtGC> OopAndMarkOopStack; 51 52 OopAndMarkOopStack _stack; 53 54 inline bool should_preserve_mark(oop obj, markOop m) const; 55 56 public: 57 size_t size() const { return _stack.size(); } 58 inline void push(oop obj, markOop m); 59 inline void push_if_necessary(oop obj, markOop m); 60 // Iterate over the stack, restore all preserved marks, and 61 // reclaim the memory taken up by the stack segments. 62 void restore(); 63 // Iterate over the stack, adjust all preserved marks according 64 // to their forwarding location stored in the mark. 65 void adjust_during_full_gc(); 66 67 void restore_and_increment(volatile size_t* const _total_size_addr); 68 inline static void init_forwarded_mark(oop obj); 69 70 // Assert the stack is empty and has no cached segments. 71 void assert_empty() PRODUCT_RETURN; 72 73 inline PreservedMarks(); 74 ~PreservedMarks() { assert_empty(); } 75 }; 76 77 class RemoveForwardedPointerClosure: public ObjectClosure { 78 public: 79 virtual void do_object(oop obj); 80 }; 81 82 class RestorePreservedMarksTaskExecutor { 83 public: 84 void virtual restore(PreservedMarksSet* preserved_marks_set, 85 volatile size_t* total_size_addr) = 0; 86 }; 87 88 class SharedRestorePreservedMarksTaskExecutor : public RestorePreservedMarksTaskExecutor { 89 private: 90 WorkGang* _workers; 91 92 public: 93 SharedRestorePreservedMarksTaskExecutor(WorkGang* workers) : _workers(workers) { } 94 95 void restore(PreservedMarksSet* preserved_marks_set, 96 volatile size_t* total_size_addr); 97 98 }; 99 100 class PreservedMarksSet : public CHeapObj<mtGC> { 101 private: 102 // true -> _stacks will be allocated in the C heap 103 // false -> _stacks will be allocated in the resource arena 104 const bool _in_c_heap; 105 106 // Number of stacks we have allocated (typically, one stack per GC worker). 107 // This should be >= 1 if the stacks have been initialized, 108 // or == 0 if they have not. 109 uint _num; 110 111 // Stack array (typically, one stack per GC worker) of length _num. 112 // This should be != NULL if the stacks have been initialized, 113 // or == NULL if they have not. 114 Padded<PreservedMarks>* _stacks; 115 116 public: 117 uint num() const { return _num; } 118 119 // Return the i'th stack. 120 PreservedMarks* get(uint i = 0) const { 121 assert(_num > 0 && _stacks != NULL, "stacks should have been initialized"); 122 assert(i < _num, "pre-condition"); 123 return (_stacks + i); 124 } 125 126 // Allocate stack array. 127 void init(uint num); 128 129 // Iterate over all stacks, restore all preserved marks, and reclaim 130 // the memory taken up by the stack segments. 131 // Supported executors: SharedRestorePreservedMarksTaskExecutor (Serial, CMS, G1), 132 // PSRestorePreservedMarksTaskExecutor (PS). 133 inline void restore(RestorePreservedMarksTaskExecutor* executor); 134 135 // Reclaim stack array. 136 void reclaim(); 137 138 // Assert all the stacks are empty and have no cached segments. 139 void assert_empty() PRODUCT_RETURN; 140 141 PreservedMarksSet(bool in_c_heap) 142 : _in_c_heap(in_c_heap), _num(0), _stacks(NULL) { } 143 144 ~PreservedMarksSet() { 145 assert(_stacks == NULL && _num == 0, "stacks should have been reclaimed"); 146 } 147 }; 148 149 #endif // SHARE_VM_GC_SHARED_PRESERVEDMARKS_HPP