1/*
2 * Copyright (c) 2016, 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,
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24
25#ifndef SHARE_GC_SHARED_PRESERVEDMARKS_HPP
26#define SHARE_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
33class PreservedMarksSet;
34class WorkGang;
35
36class PreservedMarks {
37private:
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 inline void set_mark() const;
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
56public:
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
77class RemoveForwardedPointerClosure: public ObjectClosure {
78public:
79 virtual void do_object(oop obj);
80};
81
82class RestorePreservedMarksTaskExecutor {
83public:
84 void virtual restore(PreservedMarksSet* preserved_marks_set,
85 volatile size_t* total_size_addr) = 0;
86};
87
88class SharedRestorePreservedMarksTaskExecutor : public RestorePreservedMarksTaskExecutor {
89private:
90 WorkGang* _workers;
91
92public:
93 SharedRestorePreservedMarksTaskExecutor(WorkGang* workers) : _workers(workers) { }
94
95 void restore(PreservedMarksSet* preserved_marks_set,
96 volatile size_t* total_size_addr);
97
98};
99
100class PreservedMarksSet : public CHeapObj<mtGC> {
101private:
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
116public:
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_GC_SHARED_PRESERVEDMARKS_HPP
150