wfstack: implement C++ API based on function overloading
[urcu.git] / include / urcu / wfstack.h
1 #ifndef _URCU_WFSTACK_H
2 #define _URCU_WFSTACK_H
3
4 /*
5 * urcu/wfstack.h
6 *
7 * Userspace RCU library - Stack with wait-free push, blocking traversal.
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 #include <pthread.h>
27 #include <stdbool.h>
28 #include <urcu/compiler.h>
29
30 #ifdef __cplusplus
31 extern "C" {
32 #endif
33
34 /*
35 * Stack with wait-free push, blocking traversal.
36 *
37 * Stack implementing push, pop, pop_all operations, as well as iterator
38 * on the stack head returned by pop_all.
39 *
40 * Wait-free operations: cds_wfs_push, __cds_wfs_pop_all, cds_wfs_empty,
41 * cds_wfs_first.
42 * Blocking operations: cds_wfs_pop, cds_wfs_pop_all, cds_wfs_next,
43 * iteration on stack head returned by pop_all.
44 *
45 * Synchronization table:
46 *
47 * External synchronization techniques described in the API below is
48 * required between pairs marked with "X". No external synchronization
49 * required between pairs marked with "-".
50 *
51 * cds_wfs_push __cds_wfs_pop __cds_wfs_pop_all
52 * cds_wfs_push - - -
53 * __cds_wfs_pop - X X
54 * __cds_wfs_pop_all - X -
55 *
56 * cds_wfs_pop and cds_wfs_pop_all use an internal mutex to provide
57 * synchronization.
58 */
59
60 #define CDS_WFS_WOULDBLOCK ((struct cds_wfs_node *) -1UL)
61
62 enum cds_wfs_state {
63 CDS_WFS_STATE_LAST = (1U << 0),
64 };
65
66 /*
67 * struct cds_wfs_node is returned by __cds_wfs_pop, and also used as
68 * iterator on stack. It is not safe to dereference the node next
69 * pointer when returned by __cds_wfs_pop_blocking.
70 */
71 struct cds_wfs_node {
72 struct cds_wfs_node *next;
73 };
74
75 /*
76 * struct cds_wfs_head is returned by __cds_wfs_pop_all, and can be used
77 * to begin iteration on the stack. "node" needs to be the first field of
78 * cds_wfs_head, so the end-of-stack pointer value can be used for both
79 * types.
80 */
81 struct cds_wfs_head {
82 struct cds_wfs_node node;
83 };
84
85 struct __cds_wfs_stack {
86 struct cds_wfs_head *head;
87 };
88
89 struct cds_wfs_stack {
90 struct cds_wfs_head *head;
91 pthread_mutex_t lock;
92 };
93
94 /*
95 * In C, the transparent union allows calling functions that work on both
96 * struct cds_wfs_stack and struct __cds_wfs_stack on any of those two
97 * types.
98 *
99 * In C++, implement static inline wrappers using function overloading
100 * to obtain an API similar to C.
101 */
102 typedef union {
103 struct __cds_wfs_stack *_s;
104 struct cds_wfs_stack *s;
105 } caa_c_transparent_union cds_wfs_stack_ptr_t;
106
107 #ifdef _LGPL_SOURCE
108
109 #include <urcu/static/wfstack.h>
110
111 #define cds_wfs_node_init _cds_wfs_node_init
112 #define cds_wfs_init _cds_wfs_init
113 #define cds_wfs_destroy _cds_wfs_destroy
114 #define __cds_wfs_init ___cds_wfs_init
115 #define cds_wfs_empty _cds_wfs_empty
116 #define cds_wfs_push _cds_wfs_push
117
118 /* Locking performed internally */
119 #define cds_wfs_pop_blocking _cds_wfs_pop_blocking
120 #define cds_wfs_pop_with_state_blocking _cds_wfs_pop_with_state_blocking
121 #define cds_wfs_pop_all_blocking _cds_wfs_pop_all_blocking
122
123 /*
124 * For iteration on cds_wfs_head returned by __cds_wfs_pop_all or
125 * cds_wfs_pop_all_blocking.
126 */
127 #define cds_wfs_first _cds_wfs_first
128 #define cds_wfs_next_blocking _cds_wfs_next_blocking
129 #define cds_wfs_next_nonblocking _cds_wfs_next_nonblocking
130
131 /* Pop locking with internal mutex */
132 #define cds_wfs_pop_lock _cds_wfs_pop_lock
133 #define cds_wfs_pop_unlock _cds_wfs_pop_unlock
134
135 /* Synchronization ensured by the caller. See synchronization table. */
136 #define __cds_wfs_pop_blocking ___cds_wfs_pop_blocking
137 #define __cds_wfs_pop_with_state_blocking \
138 ___cds_wfs_pop_with_state_blocking
139 #define __cds_wfs_pop_nonblocking ___cds_wfs_pop_nonblocking
140 #define __cds_wfs_pop_with_state_nonblocking \
141 ___cds_wfs_pop_with_state_nonblocking
142 #define __cds_wfs_pop_all ___cds_wfs_pop_all
143
144 #else /* !_LGPL_SOURCE */
145
146 /*
147 * cds_wfs_node_init: initialize wait-free stack node.
148 */
149 extern void cds_wfs_node_init(struct cds_wfs_node *node);
150
151 /*
152 * cds_wfs_init: initialize wait-free stack (with lock). Pair with
153 * cds_wfs_destroy().
154 */
155 extern void cds_wfs_init(struct cds_wfs_stack *s);
156
157 /*
158 * cds_wfs_destroy: destroy wait-free stack (with lock). Pair with
159 * cds_wfs_init().
160 */
161 extern void cds_wfs_destroy(struct cds_wfs_stack *s);
162
163 /*
164 * __cds_wfs_init: initialize wait-free stack (no lock). Don't pair with
165 * any destroy function.
166 */
167 extern void __cds_wfs_init(struct __cds_wfs_stack *s);
168
169 /*
170 * cds_wfs_empty: return whether wait-free stack is empty.
171 *
172 * No memory barrier is issued. No mutual exclusion is required.
173 */
174 extern bool cds_wfs_empty(cds_wfs_stack_ptr_t u_stack);
175
176 /*
177 * cds_wfs_push: push a node into the stack.
178 *
179 * Issues a full memory barrier before push. No mutual exclusion is
180 * required.
181 *
182 * Returns 0 if the stack was empty prior to adding the node.
183 * Returns non-zero otherwise.
184 */
185 extern int cds_wfs_push(cds_wfs_stack_ptr_t u_stack, struct cds_wfs_node *node);
186
187 /*
188 * cds_wfs_pop_blocking: pop a node from the stack.
189 *
190 * Calls __cds_wfs_pop_blocking with an internal pop mutex held.
191 */
192 extern struct cds_wfs_node *cds_wfs_pop_blocking(struct cds_wfs_stack *s);
193
194 /*
195 * cds_wfs_pop_with_state_blocking: pop a node from the stack, with state.
196 *
197 * Same as cds_wfs_pop_blocking, but stores whether the stack was
198 * empty into state (CDS_WFS_STATE_LAST).
199 */
200 extern struct cds_wfs_node *
201 cds_wfs_pop_with_state_blocking(struct cds_wfs_stack *s, int *state);
202
203 /*
204 * cds_wfs_pop_all_blocking: pop all nodes from a stack.
205 *
206 * Calls __cds_wfs_pop_all with an internal pop mutex held.
207 */
208 extern struct cds_wfs_head *cds_wfs_pop_all_blocking(struct cds_wfs_stack *s);
209
210 /*
211 * cds_wfs_first: get first node of a popped stack.
212 *
213 * Content written into the node before enqueue is guaranteed to be
214 * consistent, but no other memory ordering is ensured.
215 *
216 * Used by for-like iteration macros in urcu/wfstack.h:
217 * cds_wfs_for_each_blocking()
218 * cds_wfs_for_each_blocking_safe()
219 *
220 * Returns NULL if popped stack is empty, top stack node otherwise.
221 */
222 extern struct cds_wfs_node *cds_wfs_first(struct cds_wfs_head *head);
223
224 /*
225 * cds_wfs_next_blocking: get next node of a popped stack.
226 *
227 * Content written into the node before enqueue is guaranteed to be
228 * consistent, but no other memory ordering is ensured.
229 *
230 * Used by for-like iteration macros in urcu/wfstack.h:
231 * cds_wfs_for_each_blocking()
232 * cds_wfs_for_each_blocking_safe()
233 *
234 * Returns NULL if reached end of popped stack, non-NULL next stack
235 * node otherwise.
236 */
237 extern struct cds_wfs_node *cds_wfs_next_blocking(struct cds_wfs_node *node);
238
239 /*
240 * cds_wfs_next_nonblocking: get next node of a popped stack.
241 *
242 * Same as cds_wfs_next_blocking, but returns CDS_WFS_WOULDBLOCK if it
243 * needs to block.
244 */
245 extern struct cds_wfs_node *cds_wfs_next_nonblocking(struct cds_wfs_node *node);
246
247 /*
248 * cds_wfs_pop_lock: lock stack pop-protection mutex.
249 */
250 extern void cds_wfs_pop_lock(struct cds_wfs_stack *s);
251
252 /*
253 * cds_wfs_pop_unlock: unlock stack pop-protection mutex.
254 */
255 extern void cds_wfs_pop_unlock(struct cds_wfs_stack *s);
256
257 /*
258 * __cds_wfs_pop_blocking: pop a node from the stack.
259 *
260 * Returns NULL if stack is empty.
261 *
262 * __cds_wfs_pop_blocking needs to be synchronized using one of the
263 * following techniques:
264 *
265 * 1) Calling __cds_wfs_pop_blocking under rcu read lock critical
266 * section. The caller must wait for a grace period to pass before
267 * freeing the returned node or modifying the cds_wfs_node structure.
268 * 2) Using mutual exclusion (e.g. mutexes) to protect
269 * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers.
270 * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
271 * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
272 */
273 extern struct cds_wfs_node *__cds_wfs_pop_blocking(cds_wfs_stack_ptr_t u_stack);
274
275 /*
276 * __cds_wfs_pop_with_state_blocking: pop a node from the stack, with state.
277 *
278 * Same as __cds_wfs_pop_blocking, but stores whether the stack was
279 * empty into state (CDS_WFS_STATE_LAST).
280 */
281 extern struct cds_wfs_node *
282 __cds_wfs_pop_with_state_blocking(cds_wfs_stack_ptr_t u_stack,
283 int *state);
284
285 /*
286 * __cds_wfs_pop_nonblocking: pop a node from the stack.
287 *
288 * Same as __cds_wfs_pop_blocking, but returns CDS_WFS_WOULDBLOCK if
289 * it needs to block.
290 */
291 extern struct cds_wfs_node *__cds_wfs_pop_nonblocking(cds_wfs_stack_ptr_t u_stack);
292
293 /*
294 * __cds_wfs_pop_with_state_nonblocking: pop a node from the stack, with state.
295 *
296 * Same as __cds_wfs_pop_nonblocking, but stores whether the stack was
297 * empty into state (CDS_WFS_STATE_LAST).
298 */
299 extern struct cds_wfs_node *
300 __cds_wfs_pop_with_state_nonblocking(cds_wfs_stack_ptr_t u_stack,
301 int *state);
302
303 /*
304 * __cds_wfs_pop_all: pop all nodes from a stack.
305 *
306 * __cds_wfs_pop_all does not require any synchronization with other
307 * push, nor with other __cds_wfs_pop_all, but requires synchronization
308 * matching the technique used to synchronize __cds_wfs_pop_blocking:
309 *
310 * 1) If __cds_wfs_pop_blocking is called under rcu read lock critical
311 * section, both __cds_wfs_pop_blocking and cds_wfs_pop_all callers
312 * must wait for a grace period to pass before freeing the returned
313 * node or modifying the cds_wfs_node structure. However, no RCU
314 * read-side critical section is needed around __cds_wfs_pop_all.
315 * 2) Using mutual exclusion (e.g. mutexes) to protect
316 * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers.
317 * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
318 * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
319 */
320 extern struct cds_wfs_head *__cds_wfs_pop_all(cds_wfs_stack_ptr_t u_stack);
321
322 #endif /* !_LGPL_SOURCE */
323
324 /*
325 * cds_wfs_for_each_blocking: Iterate over all nodes returned by
326 * __cds_wfs_pop_all().
327 * @head: head of the queue (struct cds_wfs_head pointer).
328 * @node: iterator (struct cds_wfs_node pointer).
329 *
330 * Content written into each node before enqueue is guaranteed to be
331 * consistent, but no other memory ordering is ensured.
332 */
333 #define cds_wfs_for_each_blocking(head, node) \
334 for (node = cds_wfs_first(head); \
335 node != NULL; \
336 node = cds_wfs_next_blocking(node))
337
338 /*
339 * cds_wfs_for_each_blocking_safe: Iterate over all nodes returned by
340 * __cds_wfs_pop_all(). Safe against deletion.
341 * @head: head of the queue (struct cds_wfs_head pointer).
342 * @node: iterator (struct cds_wfs_node pointer).
343 * @n: struct cds_wfs_node pointer holding the next pointer (used
344 * internally).
345 *
346 * Content written into each node before enqueue is guaranteed to be
347 * consistent, but no other memory ordering is ensured.
348 */
349 #define cds_wfs_for_each_blocking_safe(head, node, n) \
350 for (node = cds_wfs_first(head), \
351 n = (node ? cds_wfs_next_blocking(node) : NULL); \
352 node != NULL; \
353 node = n, n = (node ? cds_wfs_next_blocking(node) : NULL))
354
355 #ifdef __cplusplus
356 }
357
358 /*
359 * In C++, implement static inline wrappers using function overloading
360 * to obtain an API similar to C.
361 */
362
363 static inline cds_wfs_stack_ptr_t __cds_wfs_stack_cast(struct __cds_wfs_stack *s)
364 {
365 cds_wfs_stack_ptr_t ret = {
366 ._s = s,
367 };
368 return ret;
369 }
370
371 static inline cds_wfs_stack_ptr_t cds_wfs_stack_cast(struct cds_wfs_stack *s)
372 {
373 cds_wfs_stack_ptr_t ret = {
374 .s = s,
375 };
376 return ret;
377 }
378
379 static inline bool cds_wfs_empty(struct __cds_wfs_stack *s)
380 {
381 return cds_wfs_empty(__cds_wfs_stack_cast(s));
382 }
383
384 static inline bool cds_wfs_empty(struct cds_wfs_stack *s)
385 {
386 return cds_wfs_empty(cds_wfs_stack_cast(s));
387 }
388
389 static inline int cds_wfs_push(struct __cds_wfs_stack *s, struct cds_wfs_node *node)
390 {
391 return cds_wfs_push(__cds_wfs_stack_cast(s), node);
392 }
393
394 static inline int cds_wfs_push(struct cds_wfs_stack *s, struct cds_wfs_node *node)
395 {
396 return cds_wfs_push(cds_wfs_stack_cast(s), node);
397 }
398
399 static inline struct cds_wfs_node *__cds_wfs_pop_blocking(struct __cds_wfs_stack *s)
400 {
401 return __cds_wfs_pop_blocking(__cds_wfs_stack_cast(s));
402 }
403
404 static inline struct cds_wfs_node *__cds_wfs_pop_blocking(struct cds_wfs_stack *s)
405 {
406 return __cds_wfs_pop_blocking(cds_wfs_stack_cast(s));
407 }
408
409 static inline struct cds_wfs_node *
410 __cds_wfs_pop_with_state_blocking(struct __cds_wfs_stack *s, int *state)
411 {
412 return __cds_wfs_pop_with_state_blocking(__cds_wfs_stack_cast(s), state);
413 }
414
415 static inline struct cds_wfs_node *
416 __cds_wfs_pop_with_state_blocking(struct cds_wfs_stack *s, int *state)
417 {
418 return __cds_wfs_pop_with_state_blocking(cds_wfs_stack_cast(s), state);
419 }
420
421 static inline struct cds_wfs_node *__cds_wfs_pop_nonblocking(struct __cds_wfs_stack *s)
422
423 {
424 return __cds_wfs_pop_nonblocking(__cds_wfs_stack_cast(s));
425 }
426
427 static inline struct cds_wfs_node *__cds_wfs_pop_nonblocking(struct cds_wfs_stack *s)
428 {
429 return __cds_wfs_pop_nonblocking(cds_wfs_stack_cast(s));
430 }
431
432 static inline struct cds_wfs_node *
433 __cds_wfs_pop_with_state_nonblocking(struct __cds_wfs_stack *s, int *state)
434 {
435 return __cds_wfs_pop_with_state_nonblocking(__cds_wfs_stack_cast(s), state);
436 }
437
438 static inline struct cds_wfs_node *
439 __cds_wfs_pop_with_state_nonblocking(struct cds_wfs_stack *s, int *state)
440 {
441 return __cds_wfs_pop_with_state_nonblocking(cds_wfs_stack_cast(s), state);
442 }
443
444 static inline struct cds_wfs_head *__cds_wfs_pop_all(struct __cds_wfs_stack *s)
445 {
446 return __cds_wfs_pop_all(__cds_wfs_stack_cast(s));
447 }
448
449 static inline struct cds_wfs_head *__cds_wfs_pop_all(struct cds_wfs_stack *s)
450 {
451 return __cds_wfs_pop_all(cds_wfs_stack_cast(s));
452 }
453
454 #endif
455
456 #endif /* _URCU_WFSTACK_H */
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