1 /*
2 * Copyright (c) 2016, 2020, 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_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
33 class AbstractGangTask;
34 class PreservedMarksSet;
35 class WorkGang;
36
37 class PreservedMarks {
38 private:
39 class OopAndMarkWord {
40 private:
41 oop _o;
42 markWord _m;
43
44 public:
45 OopAndMarkWord(oop obj, markWord m) : _o(obj), _m(m) { }
46
47 oop get_oop() { return _o; }
48 inline void set_mark() const;
49 void set_oop(oop obj) { _o = obj; }
50 };
51 typedef Stack<OopAndMarkWord, mtGC> OopAndMarkWordStack;
52
53 OopAndMarkWordStack _stack;
54
55 inline bool should_preserve_mark(oop obj, markWord m) const;
56
57 public:
58 size_t size() const { return _stack.size(); }
59 inline void push(oop obj, markWord m);
60 inline void push_if_necessary(oop obj, markWord m);
61 // Iterate over the stack, restore all preserved marks, and
62 // reclaim the memory taken up by the stack segments.
63 void restore();
64 // Iterate over the stack, adjust all preserved marks according
65 // to their forwarding location stored in the mark.
66 void adjust_during_full_gc();
67
68 void restore_and_increment(volatile size_t* const _total_size_addr);
69 inline static void init_forwarded_mark(oop obj);
70
71 // Assert the stack is empty and has no cached segments.
72 void assert_empty() PRODUCT_RETURN;
73
74 inline PreservedMarks();
75 ~PreservedMarks() { assert_empty(); }
76 };
77
78 class RemoveForwardedPointerClosure: public ObjectClosure {
79 public:
80 virtual void do_object(oop obj);
81 };
82
83 class PreservedMarksSet : public CHeapObj<mtGC> {
84 private:
85 // true -> _stacks will be allocated in the C heap
86 // false -> _stacks will be allocated in the resource arena
87 const bool _in_c_heap;
88
89 // Number of stacks we have allocated (typically, one stack per GC worker).
90 // This should be >= 1 if the stacks have been initialized,
91 // or == 0 if they have not.
92 uint _num;
93
94 // Stack array (typically, one stack per GC worker) of length _num.
95 // This should be != NULL if the stacks have been initialized,
96 // or == NULL if they have not.
97 Padded<PreservedMarks>* _stacks;
98
99 public:
100 uint num() const { return _num; }
101
102 // Return the i'th stack.
103 PreservedMarks* get(uint i = 0) const {
104 assert(_num > 0 && _stacks != NULL, "stacks should have been initialized");
105 assert(i < _num, "pre-condition");
106 return (_stacks + i);
107 }
108
109 // Allocate stack array.
110 void init(uint num);
111
112 // Iterate over all stacks, restore all preserved marks, and reclaim
113 // the memory taken up by the stack segments using the given WorkGang. If the WorkGang
114 // is NULL, perform the work serially in the current thread.
115 void restore(WorkGang* workers);
116
117 AbstractGangTask* create_task();
118
119 // Reclaim stack array.
120 void reclaim();
121
122 // Assert all the stacks are empty and have no cached segments.
123 void assert_empty() PRODUCT_RETURN;
124
125 PreservedMarksSet(bool in_c_heap)
126 : _in_c_heap(in_c_heap), _num(0), _stacks(NULL) { }
127
128 ~PreservedMarksSet() {
129 assert(_stacks == NULL && _num == 0, "stacks should have been reclaimed");
130 }
131 };
132
133 #endif // SHARE_GC_SHARED_PRESERVEDMARKS_HPP