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