1 /*
2 * Copyright (c) 2012, 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_JFR_RECORDER_STORAGE_JFRBUFFER_HPP
26 #define SHARE_VM_JFR_RECORDER_STORAGE_JFRBUFFER_HPP
27
28 #include "memory/allocation.hpp"
29
30 //
31 // Represents a piece of committed memory.
32 //
33 // u1* _pos <-- next store position
34 // u1* _top <-- next unflushed position
35 //
36 // const void* _identity <-- acquired by
37 //
38 // Must be the owner before attempting stores.
39 // Use acquire() and/or try_acquire() for exclusive access
40 // to the (entire) buffer (cas identity).
41 //
42 // Stores to the buffer should uphold transactional semantics.
43 // A new _pos must be updated only after all intended stores have completed.
44 // The relation between _pos and _top must hold atomically,
45 // e.g. the delta must always be fully parsable.
46 // _top can move concurrently by other threads but is always <= _pos.
47 //
48 class JfrBuffer {
49 private:
50 JfrBuffer* _next;
51 JfrBuffer* _prev;
52 const void* volatile _identity;
53 u1* _pos;
54 mutable const u1* volatile _top;
55 u2 _flags;
56 u2 _header_size;
57 u4 _size;
58
59 const u1* stable_top() const;
60 void clear_flags();
61
62 public:
63 JfrBuffer();
64 bool initialize(size_t header_size, size_t size, const void* id = NULL);
65 void reinitialize();
66 void concurrent_reinitialization();
67 size_t discard();
68 JfrBuffer* next() const {
69 return _next;
70 }
71
72 JfrBuffer* prev() const {
73 return _prev;
74 }
75
76 void set_next(JfrBuffer* next) {
77 _next = next;
78 }
79
80 void set_prev(JfrBuffer* prev) {
81 _prev = prev;
82 }
83
84 const u1* start() const {
85 return ((const u1*)this) + _header_size;
86 }
87
88 u1* start() {
89 return ((u1*)this) + _header_size;
90 }
91
92 const u1* end() const {
93 return start() + size();
94 }
95
96 const u1* pos() const {
97 return _pos;
98 }
99
100 u1* pos() {
101 return _pos;
102 }
103
104 u1** pos_address() {
105 return (u1**)&_pos;
106 }
107
108 void set_pos(u1* new_pos) {
109 assert(new_pos <= end(), "invariant");
110 _pos = new_pos;
111 }
112
113 void set_pos(size_t size) {
114 assert(_pos + size <= end(), "invariant");
115 _pos += size;
116 }
117
118 const u1* top() const;
119 void set_top(const u1* new_top);
120 const u1* concurrent_top() const;
121 void set_concurrent_top(const u1* new_top);
122
123 size_t header_size() const {
124 return _header_size;
125 }
126
127 size_t size() const {
128 return _size * BytesPerWord;
129 }
130
131 size_t total_size() const {
132 return header_size() + size();
133 }
134
135 size_t free_size() const {
136 return end() - pos();
137 }
138
139 size_t unflushed_size() const;
140
141 bool empty() const {
142 return pos() == start();
143 }
144
145 const void* identity() const {
146 return _identity;
147 }
148
149 void clear_identity();
150
151 void acquire(const void* id);
152 bool try_acquire(const void* id);
153 void release();
154
155 void move(JfrBuffer* const to, size_t size);
156 void concurrent_move_and_reinitialize(JfrBuffer* const to, size_t size);
157
158 bool transient() const;
159 void set_transient();
160 void clear_transient();
161
162 bool lease() const;
163 void set_lease();
164 void clear_lease();
165
166 bool retired() const;
167 void set_retired();
168 void clear_retired();
169
170 debug_only(bool acquired_by_self() const;)
171 };
172
173 class JfrAgeNode : public JfrBuffer {
174 private:
175 JfrBuffer* _retired;
176
177 public:
178 JfrAgeNode() : _retired(NULL) {}
179 void set_retired_buffer(JfrBuffer* retired) {
180 _retired = retired;
181 }
182 JfrBuffer* retired_buffer() const {
183 return _retired;
184 }
185 };
186
187 #endif // SHARE_VM_JFR_RECORDER_STORAGE_JFRBUFFER_HPP