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d3d3857f MJ |
1 | // SPDX-FileCopyrightText: 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
2 | // | |
3 | // SPDX-License-Identifier: LGPL-2.1-or-later | |
4 | ||
d3bfcb24 MD |
5 | #ifndef _URCU_LFSTACK_H |
6 | #define _URCU_LFSTACK_H | |
7 | ||
8 | /* | |
d3bfcb24 | 9 | * Userspace RCU library - Lock-Free Stack |
d3bfcb24 MD |
10 | */ |
11 | ||
12 | #ifdef __cplusplus | |
13 | extern "C" { | |
14 | #endif | |
15 | ||
7294103b MD |
16 | #include <stdbool.h> |
17 | #include <pthread.h> | |
18 | ||
19 | /* | |
20 | * Lock-free stack. | |
21 | * | |
22 | * Stack implementing push, pop, pop_all operations, as well as iterator | |
23 | * on the stack head returned by pop_all. | |
24 | * | |
25 | * Synchronization table: | |
26 | * | |
27 | * External synchronization techniques described in the API below is | |
28 | * required between pairs marked with "X". No external synchronization | |
29 | * required between pairs marked with "-". | |
30 | * | |
31 | * cds_lfs_push __cds_lfs_pop __cds_lfs_pop_all | |
32 | * cds_lfs_push - - - | |
33 | * __cds_lfs_pop - X X | |
34 | * __cds_lfs_pop_all - X - | |
35 | * | |
36 | * cds_lfs_pop_blocking and cds_lfs_pop_all_blocking use an internal | |
37 | * mutex to provide synchronization. | |
38 | */ | |
39 | ||
40 | /* | |
41 | * struct cds_lfs_node is returned by cds_lfs_pop, and also used as | |
42 | * iterator on stack. It is not safe to dereference the node next | |
43 | * pointer when returned by cds_lfs_pop. | |
44 | */ | |
d3bfcb24 MD |
45 | struct cds_lfs_node { |
46 | struct cds_lfs_node *next; | |
47 | }; | |
48 | ||
7294103b MD |
49 | /* |
50 | * struct cds_lfs_head is returned by __cds_lfs_pop_all, and can be used | |
51 | * to begin iteration on the stack. "node" needs to be the first field | |
52 | * of cds_lfs_head, so the end-of-stack pointer value can be used for | |
53 | * both types. | |
54 | */ | |
55 | struct cds_lfs_head { | |
56 | struct cds_lfs_node node; | |
57 | }; | |
58 | ||
48a8832b MD |
59 | struct __cds_lfs_stack { |
60 | struct cds_lfs_head *head; | |
61 | }; | |
62 | ||
d3bfcb24 | 63 | struct cds_lfs_stack { |
7294103b MD |
64 | struct cds_lfs_head *head; |
65 | pthread_mutex_t lock; | |
d3bfcb24 MD |
66 | }; |
67 | ||
48a8832b | 68 | /* |
e9349020 MD |
69 | * In C, the transparent union allows calling functions that work on |
70 | * both struct cds_lfs_stack and struct __cds_lfs_stack on any of those | |
71 | * two types. | |
28757437 | 72 | * |
e9349020 MD |
73 | * In C++, implement static inline wrappers using function overloading |
74 | * to obtain an API similar to C. | |
087bce43 MD |
75 | * |
76 | * Avoid complaints from clang++ not knowing the transparent union | |
77 | * attribute. | |
48a8832b | 78 | */ |
087bce43 MD |
79 | #if defined(__clang__) |
80 | #pragma clang diagnostic push | |
81 | #pragma clang diagnostic ignored "-Wignored-attributes" | |
82 | #endif | |
5135c0fd | 83 | typedef union { |
48a8832b MD |
84 | struct __cds_lfs_stack *_s; |
85 | struct cds_lfs_stack *s; | |
087bce43 | 86 | } __attribute__((__transparent_union__)) cds_lfs_stack_ptr_t; |
394e0556 MD |
87 | |
88 | typedef union { | |
89 | const struct __cds_lfs_stack *_s; | |
90 | const struct cds_lfs_stack *s; | |
91 | } __attribute__((__transparent_union__)) cds_lfs_stack_const_ptr_t; | |
087bce43 MD |
92 | #if defined(__clang__) |
93 | #pragma clang diagnostic pop | |
94 | #endif | |
48a8832b | 95 | |
d3bfcb24 MD |
96 | #ifdef _LGPL_SOURCE |
97 | ||
98 | #include <urcu/static/lfstack.h> | |
99 | ||
100 | #define cds_lfs_node_init _cds_lfs_node_init | |
101 | #define cds_lfs_init _cds_lfs_init | |
200d100e | 102 | #define cds_lfs_destroy _cds_lfs_destroy |
817a0178 | 103 | #define __cds_lfs_init ___cds_lfs_init |
7294103b | 104 | #define cds_lfs_empty _cds_lfs_empty |
d3bfcb24 | 105 | #define cds_lfs_push _cds_lfs_push |
7294103b MD |
106 | |
107 | /* Locking performed internally */ | |
108 | #define cds_lfs_pop_blocking _cds_lfs_pop_blocking | |
109 | #define cds_lfs_pop_all_blocking _cds_lfs_pop_all_blocking | |
110 | ||
111 | /* Synchronize pop with internal mutex */ | |
112 | #define cds_lfs_pop_lock _cds_lfs_pop_lock | |
113 | #define cds_lfs_pop_unlock _cds_lfs_pop_unlock | |
114 | ||
115 | /* Synchronization ensured by the caller. See synchronization table. */ | |
116 | #define __cds_lfs_pop ___cds_lfs_pop | |
117 | #define __cds_lfs_pop_all ___cds_lfs_pop_all | |
d3bfcb24 MD |
118 | |
119 | #else /* !_LGPL_SOURCE */ | |
120 | ||
7294103b MD |
121 | /* |
122 | * cds_lfs_node_init: initialize lock-free stack node. | |
123 | */ | |
d3bfcb24 | 124 | extern void cds_lfs_node_init(struct cds_lfs_node *node); |
7294103b MD |
125 | |
126 | /* | |
200d100e MD |
127 | * cds_lfs_init: initialize lock-free stack (with locking). Pair with |
128 | * cds_lfs_destroy(). | |
7294103b | 129 | */ |
d3bfcb24 MD |
130 | extern void cds_lfs_init(struct cds_lfs_stack *s); |
131 | ||
48a8832b | 132 | /* |
200d100e MD |
133 | * cds_lfs_destroy: destroy lock-free stack (with lock). Pair with |
134 | * cds_lfs_init(). | |
135 | */ | |
136 | extern void cds_lfs_destroy(struct cds_lfs_stack *s); | |
137 | ||
138 | /* | |
139 | * __cds_lfs_init: initialize lock-free stack (without lock). | |
140 | * Don't pair with any destroy function. | |
48a8832b MD |
141 | */ |
142 | extern void __cds_lfs_init(struct __cds_lfs_stack *s); | |
143 | ||
7294103b MD |
144 | /* |
145 | * cds_lfs_empty: return whether lock-free stack is empty. | |
146 | * | |
147 | * No memory barrier is issued. No mutual exclusion is required. | |
148 | */ | |
394e0556 | 149 | extern bool cds_lfs_empty(cds_lfs_stack_const_ptr_t s); |
7294103b | 150 | |
d3bfcb24 MD |
151 | /* |
152 | * cds_lfs_push: push a node into the stack. | |
153 | * | |
154 | * Does not require any synchronization with other push nor pop. | |
155 | * | |
156 | * Returns 0 if the stack was empty prior to adding the node. | |
157 | * Returns non-zero otherwise. | |
158 | */ | |
48a8832b | 159 | extern bool cds_lfs_push(cds_lfs_stack_ptr_t s, |
d3bfcb24 MD |
160 | struct cds_lfs_node *node); |
161 | ||
162 | /* | |
7294103b MD |
163 | * cds_lfs_pop_blocking: pop a node from the stack. |
164 | * | |
165 | * Calls __cds_lfs_pop with an internal pop mutex held. | |
166 | */ | |
167 | extern struct cds_lfs_node *cds_lfs_pop_blocking(struct cds_lfs_stack *s); | |
168 | ||
169 | /* | |
170 | * cds_lfs_pop_all_blocking: pop all nodes from a stack. | |
171 | * | |
172 | * Calls __cds_lfs_pop_all with an internal pop mutex held. | |
173 | */ | |
174 | extern struct cds_lfs_head *cds_lfs_pop_all_blocking(struct cds_lfs_stack *s); | |
175 | ||
176 | /* | |
177 | * cds_lfs_pop_lock: lock stack pop-protection mutex. | |
178 | */ | |
179 | extern void cds_lfs_pop_lock(struct cds_lfs_stack *s); | |
180 | ||
181 | /* | |
182 | * cds_lfs_pop_unlock: unlock stack pop-protection mutex. | |
183 | */ | |
184 | extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s); | |
185 | ||
186 | /* | |
187 | * __cds_lfs_pop: pop a node from the stack. | |
d3bfcb24 MD |
188 | * |
189 | * Returns NULL if stack is empty. | |
190 | * | |
7294103b | 191 | * __cds_lfs_pop needs to be synchronized using one of the following |
d3bfcb24 MD |
192 | * techniques: |
193 | * | |
f9b5c2b6 MD |
194 | * 1) Calling __cds_lfs_pop under rcu read lock critical section. |
195 | * Both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a | |
196 | * grace period to pass before freeing the returned node or pushing | |
197 | * the node back into the stack. It is valid to overwrite the content | |
198 | * of cds_lfs_node immediately after __cds_lfs_pop and | |
199 | * __cds_lfs_pop_all. | |
7294103b MD |
200 | * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop |
201 | * and __cds_lfs_pop_all callers. | |
202 | * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and | |
203 | * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme). | |
d3bfcb24 | 204 | */ |
48a8832b | 205 | extern struct cds_lfs_node *__cds_lfs_pop(cds_lfs_stack_ptr_t s); |
7294103b MD |
206 | |
207 | /* | |
208 | * __cds_lfs_pop_all: pop all nodes from a stack. | |
209 | * | |
210 | * __cds_lfs_pop_all does not require any synchronization with other | |
211 | * push, nor with other __cds_lfs_pop_all, but requires synchronization | |
212 | * matching the technique used to synchronize __cds_lfs_pop: | |
213 | * | |
214 | * 1) If __cds_lfs_pop is called under rcu read lock critical section, | |
f9b5c2b6 MD |
215 | * both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a |
216 | * grace period to pass before freeing the returned node or pushing | |
217 | * the node back into the stack. It is valid to overwrite the content | |
218 | * of cds_lfs_node immediately after __cds_lfs_pop and | |
219 | * __cds_lfs_pop_all. No RCU read-side critical section is needed | |
220 | * around __cds_lfs_pop_all. | |
7294103b MD |
221 | * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and |
222 | * __cds_lfs_pop_all callers. | |
223 | * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and | |
224 | * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme). | |
225 | */ | |
48a8832b | 226 | extern struct cds_lfs_head *__cds_lfs_pop_all(cds_lfs_stack_ptr_t s); |
d3bfcb24 MD |
227 | |
228 | #endif /* !_LGPL_SOURCE */ | |
229 | ||
7294103b MD |
230 | /* |
231 | * cds_lfs_for_each: Iterate over all nodes returned by | |
232 | * __cds_lfs_pop_all. | |
233 | * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer). | |
234 | * @__node: node to use as iterator (struct cds_lfs_node pointer). | |
235 | * | |
236 | * Content written into each node before push is guaranteed to be | |
237 | * consistent, but no other memory ordering is ensured. | |
238 | */ | |
239 | #define cds_lfs_for_each(__head, __node) \ | |
240 | for (__node = &__head->node; \ | |
241 | __node != NULL; \ | |
242 | __node = __node->next) | |
243 | ||
244 | /* | |
245 | * cds_lfs_for_each_safe: Iterate over all nodes returned by | |
246 | * __cds_lfs_pop_all, safe against node deletion. | |
247 | * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer). | |
248 | * @__node: node to use as iterator (struct cds_lfs_node pointer). | |
249 | * @__n: struct cds_lfs_node pointer holding the next pointer (used | |
250 | * internally). | |
251 | * | |
252 | * Content written into each node before push is guaranteed to be | |
253 | * consistent, but no other memory ordering is ensured. | |
254 | */ | |
255 | #define cds_lfs_for_each_safe(__head, __node, __n) \ | |
256 | for (__node = &__head->node, __n = (__node ? __node->next : NULL); \ | |
257 | __node != NULL; \ | |
258 | __node = __n, __n = (__node ? __node->next : NULL)) | |
259 | ||
d3bfcb24 MD |
260 | #ifdef __cplusplus |
261 | } | |
e9349020 MD |
262 | |
263 | /* | |
264 | * In C++, implement static inline wrappers using function overloading | |
265 | * to obtain an API similar to C. | |
266 | */ | |
267 | ||
3a602ac1 | 268 | static inline cds_lfs_stack_ptr_t cds_lfs_stack_cast(struct __cds_lfs_stack *s) |
e9349020 MD |
269 | { |
270 | cds_lfs_stack_ptr_t ret = { | |
271 | ._s = s, | |
272 | }; | |
273 | return ret; | |
274 | } | |
275 | ||
276 | static inline cds_lfs_stack_ptr_t cds_lfs_stack_cast(struct cds_lfs_stack *s) | |
277 | { | |
278 | cds_lfs_stack_ptr_t ret = { | |
279 | .s = s, | |
280 | }; | |
281 | return ret; | |
282 | } | |
283 | ||
394e0556 MD |
284 | static inline cds_lfs_stack_const_ptr_t cds_lfs_stack_const_cast(const struct __cds_lfs_stack *s) |
285 | { | |
286 | cds_lfs_stack_const_ptr_t ret = { | |
287 | ._s = s, | |
288 | }; | |
289 | return ret; | |
290 | } | |
291 | ||
292 | static inline cds_lfs_stack_const_ptr_t cds_lfs_stack_const_cast(const struct cds_lfs_stack *s) | |
293 | { | |
294 | cds_lfs_stack_const_ptr_t ret = { | |
295 | .s = s, | |
296 | }; | |
297 | return ret; | |
298 | } | |
299 | ||
9298902c | 300 | template<typename T> static inline bool cds_lfs_empty(T s) |
e9349020 | 301 | { |
394e0556 | 302 | return cds_lfs_empty(cds_lfs_stack_const_cast(s)); |
e9349020 MD |
303 | } |
304 | ||
9298902c | 305 | template<typename T> static inline bool cds_lfs_push(T s, |
e9349020 MD |
306 | struct cds_lfs_node *node) |
307 | { | |
308 | return cds_lfs_push(cds_lfs_stack_cast(s), node); | |
309 | } | |
310 | ||
9298902c | 311 | template<typename T> static inline struct cds_lfs_node *__cds_lfs_pop(T s) |
e9349020 | 312 | { |
3a602ac1 | 313 | return __cds_lfs_pop(cds_lfs_stack_cast(s)); |
e9349020 MD |
314 | } |
315 | ||
9298902c | 316 | template<typename T> static inline struct cds_lfs_head *__cds_lfs_pop_all(T s) |
e9349020 MD |
317 | { |
318 | return __cds_lfs_pop_all(cds_lfs_stack_cast(s)); | |
319 | } | |
320 | ||
321 | #endif /* __cplusplus */ | |
d3bfcb24 MD |
322 | |
323 | #endif /* _URCU_LFSTACK_H */ |