lfstack: implement C++ API based on function overloading
[urcu.git] / include / urcu / lfstack.h
1 #ifndef _URCU_LFSTACK_H
2 #define _URCU_LFSTACK_H
3
4 /*
5 * lfstack.h
6 *
7 * Userspace RCU library - Lock-Free Stack
8 *
9 * Copyright 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 *
11 * This library is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this library; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26 #ifdef __cplusplus
27 extern "C" {
28 #endif
29
30 #include <stdbool.h>
31 #include <pthread.h>
32 #include <urcu/compiler.h>
33
34 /*
35 * Lock-free stack.
36 *
37 * Stack implementing push, pop, pop_all operations, as well as iterator
38 * on the stack head returned by pop_all.
39 *
40 * Synchronization table:
41 *
42 * External synchronization techniques described in the API below is
43 * required between pairs marked with "X". No external synchronization
44 * required between pairs marked with "-".
45 *
46 * cds_lfs_push __cds_lfs_pop __cds_lfs_pop_all
47 * cds_lfs_push - - -
48 * __cds_lfs_pop - X X
49 * __cds_lfs_pop_all - X -
50 *
51 * cds_lfs_pop_blocking and cds_lfs_pop_all_blocking use an internal
52 * mutex to provide synchronization.
53 */
54
55 /*
56 * struct cds_lfs_node is returned by cds_lfs_pop, and also used as
57 * iterator on stack. It is not safe to dereference the node next
58 * pointer when returned by cds_lfs_pop.
59 */
60 struct cds_lfs_node {
61 struct cds_lfs_node *next;
62 };
63
64 /*
65 * struct cds_lfs_head is returned by __cds_lfs_pop_all, and can be used
66 * to begin iteration on the stack. "node" needs to be the first field
67 * of cds_lfs_head, so the end-of-stack pointer value can be used for
68 * both types.
69 */
70 struct cds_lfs_head {
71 struct cds_lfs_node node;
72 };
73
74 struct __cds_lfs_stack {
75 struct cds_lfs_head *head;
76 };
77
78 struct cds_lfs_stack {
79 struct cds_lfs_head *head;
80 pthread_mutex_t lock;
81 };
82
83 /*
84 * In C, the transparent union allows calling functions that work on
85 * both struct cds_lfs_stack and struct __cds_lfs_stack on any of those
86 * two types.
87 *
88 * In C++, implement static inline wrappers using function overloading
89 * to obtain an API similar to C.
90 */
91 typedef union {
92 struct __cds_lfs_stack *_s;
93 struct cds_lfs_stack *s;
94 } caa_c_transparent_union cds_lfs_stack_ptr_t;
95
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
102 #define cds_lfs_destroy _cds_lfs_destroy
103 #define __cds_lfs_init ___cds_lfs_init
104 #define cds_lfs_empty _cds_lfs_empty
105 #define cds_lfs_push _cds_lfs_push
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
118
119 #else /* !_LGPL_SOURCE */
120
121 /*
122 * cds_lfs_node_init: initialize lock-free stack node.
123 */
124 extern void cds_lfs_node_init(struct cds_lfs_node *node);
125
126 /*
127 * cds_lfs_init: initialize lock-free stack (with locking). Pair with
128 * cds_lfs_destroy().
129 */
130 extern void cds_lfs_init(struct cds_lfs_stack *s);
131
132 /*
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.
141 */
142 extern void __cds_lfs_init(struct __cds_lfs_stack *s);
143
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 */
149 extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s);
150
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 */
159 extern bool cds_lfs_push(cds_lfs_stack_ptr_t s,
160 struct cds_lfs_node *node);
161
162 /*
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.
188 *
189 * Returns NULL if stack is empty.
190 *
191 * __cds_lfs_pop needs to be synchronized using one of the following
192 * techniques:
193 *
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.
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).
204 */
205 extern struct cds_lfs_node *__cds_lfs_pop(cds_lfs_stack_ptr_t s);
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,
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.
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 */
226 extern struct cds_lfs_head *__cds_lfs_pop_all(cds_lfs_stack_ptr_t s);
227
228 #endif /* !_LGPL_SOURCE */
229
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
260 #ifdef __cplusplus
261 }
262
263 /*
264 * In C++, implement static inline wrappers using function overloading
265 * to obtain an API similar to C.
266 */
267
268 static inline cds_lfs_stack_ptr_t __cds_lfs_stack_cast(struct __cds_lfs_stack *s)
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
284 static inline bool cds_lfs_empty(struct __cds_lfs_stack *_s)
285 {
286 return cds_lfs_empty(__cds_lfs_stack_cast(_s));
287 }
288
289 static inline bool cds_lfs_empty(struct cds_lfs_stack *s)
290 {
291 return cds_lfs_empty(cds_lfs_stack_cast(s));
292 }
293
294 static inline bool cds_lfs_push(struct __cds_lfs_stack *s,
295 struct cds_lfs_node *node)
296 {
297 return cds_lfs_push(__cds_lfs_stack_cast(s), node);
298 }
299
300 static inline bool cds_lfs_push(struct cds_lfs_stack *s,
301 struct cds_lfs_node *node)
302 {
303 return cds_lfs_push(cds_lfs_stack_cast(s), node);
304 }
305
306 static inline struct cds_lfs_node *__cds_lfs_pop(struct __cds_lfs_stack *s)
307 {
308 return __cds_lfs_pop(__cds_lfs_stack_cast(s));
309 }
310
311 static inline struct cds_lfs_node *__cds_lfs_pop(struct cds_lfs_stack *s)
312 {
313 return __cds_lfs_pop(cds_lfs_stack_cast(s));
314 }
315
316 static inline struct cds_lfs_head *__cds_lfs_pop_all(struct __cds_lfs_stack *s)
317 {
318 return __cds_lfs_pop_all(__cds_lfs_stack_cast(s));
319 }
320
321 static inline struct cds_lfs_head *__cds_lfs_pop_all(struct cds_lfs_stack *s)
322 {
323 return __cds_lfs_pop_all(cds_lfs_stack_cast(s));
324 }
325
326 #endif /* __cplusplus */
327
328 #endif /* _URCU_LFSTACK_H */
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