362caccfa568b8631542238e0172e88763faaa44
[urcu.git] / 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 <assert.h>
28 #include <stdbool.h>
29 #include <urcu/compiler.h>
30
31 #ifdef __cplusplus
32 extern "C" {
33 #endif
34
35 /*
36 * Stack with wait-free push, blocking traversal.
37 *
38 * Stack implementing push, pop, pop_all operations, as well as iterator
39 * on the stack head returned by pop_all.
40 *
41 * Wait-free operations: cds_wfs_push, __cds_wfs_pop_all, cds_wfs_empty,
42 * cds_wfs_first.
43 * Blocking operations: cds_wfs_pop, cds_wfs_pop_all, cds_wfs_next,
44 * iteration on stack head returned by pop_all.
45 *
46 * Synchronization table:
47 *
48 * External synchronization techniques described in the API below is
49 * required between pairs marked with "X". No external synchronization
50 * required between pairs marked with "-".
51 *
52 * cds_wfs_push __cds_wfs_pop __cds_wfs_pop_all
53 * cds_wfs_push - - -
54 * __cds_wfs_pop - X X
55 * __cds_wfs_pop_all - X -
56 *
57 * cds_wfs_pop and cds_wfs_pop_all use an internal mutex to provide
58 * synchronization.
59 */
60
61 #define CDS_WFS_WOULDBLOCK ((void *) -1UL)
62
63 enum cds_wfs_state {
64 CDS_WFS_STATE_LAST = (1U << 0),
65 };
66
67 /*
68 * struct cds_wfs_node is returned by __cds_wfs_pop, and also used as
69 * iterator on stack. It is not safe to dereference the node next
70 * pointer when returned by __cds_wfs_pop_blocking.
71 */
72 struct cds_wfs_node {
73 struct cds_wfs_node *next;
74 };
75
76 /*
77 * struct cds_wfs_head is returned by __cds_wfs_pop_all, and can be used
78 * to begin iteration on the stack. "node" needs to be the first field of
79 * cds_wfs_head, so the end-of-stack pointer value can be used for both
80 * types.
81 */
82 struct cds_wfs_head {
83 struct cds_wfs_node node;
84 };
85
86 struct __cds_wfs_stack {
87 struct cds_wfs_head *head;
88 };
89
90 struct cds_wfs_stack {
91 struct cds_wfs_head *head;
92 pthread_mutex_t lock;
93 };
94
95 /*
96 * The transparent union allows calling functions that work on both
97 * struct cds_wfs_stack and struct __cds_wfs_stack on any of those two
98 * types.
99 */
100 typedef union __attribute__((__transparent_union__)) {
101 struct __cds_wfs_stack *_s;
102 struct cds_wfs_stack *s;
103 } cds_wfs_stack_ptr_t;
104
105 #ifdef _LGPL_SOURCE
106
107 #include <urcu/static/wfstack.h>
108
109 #define cds_wfs_node_init _cds_wfs_node_init
110 #define cds_wfs_init _cds_wfs_init
111 #define __cds_wfs_init ___cds_wfs_init
112 #define cds_wfs_empty _cds_wfs_empty
113 #define cds_wfs_push _cds_wfs_push
114
115 /* Locking performed internally */
116 #define cds_wfs_pop_blocking _cds_wfs_pop_blocking
117 #define cds_wfs_pop_with_state_blocking _cds_wfs_pop_with_state_blocking
118 #define cds_wfs_pop_all_blocking _cds_wfs_pop_all_blocking
119
120 /*
121 * For iteration on cds_wfs_head returned by __cds_wfs_pop_all or
122 * cds_wfs_pop_all_blocking.
123 */
124 #define cds_wfs_first _cds_wfs_first
125 #define cds_wfs_next_blocking _cds_wfs_next_blocking
126 #define cds_wfs_next_nonblocking _cds_wfs_next_nonblocking
127
128 /* Pop locking with internal mutex */
129 #define cds_wfs_pop_lock _cds_wfs_pop_lock
130 #define cds_wfs_pop_unlock _cds_wfs_pop_unlock
131
132 /* Synchronization ensured by the caller. See synchronization table. */
133 #define __cds_wfs_pop_blocking ___cds_wfs_pop_blocking
134 #define __cds_wfs_pop_with_state_blocking \
135 ___cds_wfs_pop_with_state_blocking
136 #define __cds_wfs_pop_nonblocking ___cds_wfs_pop_nonblocking
137 #define __cds_wfs_pop_with_state_nonblocking \
138 ___cds_wfs_pop_with_state_nonblocking
139 #define __cds_wfs_pop_all ___cds_wfs_pop_all
140
141 #else /* !_LGPL_SOURCE */
142
143 /*
144 * cds_wfs_node_init: initialize wait-free stack node.
145 */
146 extern void cds_wfs_node_init(struct cds_wfs_node *node);
147
148 /*
149 * cds_wfs_init: initialize wait-free stack.
150 */
151 extern void cds_wfs_init(struct cds_wfs_stack *s);
152
153 /*
154 * __cds_wfs_init: initialize wait-free stack.
155 */
156 extern void __cds_wfs_init(struct __cds_wfs_stack *s);
157
158 /*
159 * cds_wfs_empty: return whether wait-free stack is empty.
160 *
161 * No memory barrier is issued. No mutual exclusion is required.
162 */
163 extern bool cds_wfs_empty(cds_wfs_stack_ptr_t u_stack);
164
165 /*
166 * cds_wfs_push: push a node into the stack.
167 *
168 * Issues a full memory barrier before push. No mutual exclusion is
169 * required.
170 *
171 * Returns 0 if the stack was empty prior to adding the node.
172 * Returns non-zero otherwise.
173 */
174 extern int cds_wfs_push(cds_wfs_stack_ptr_t u_stack, struct cds_wfs_node *node);
175
176 /*
177 * cds_wfs_pop_blocking: pop a node from the stack.
178 *
179 * Calls __cds_wfs_pop_blocking with an internal pop mutex held.
180 */
181 extern struct cds_wfs_node *cds_wfs_pop_blocking(struct cds_wfs_stack *s);
182
183 /*
184 * cds_wfs_pop_with_state_blocking: pop a node from the stack, with state.
185 *
186 * Same as cds_wfs_pop_blocking, but stores whether the stack was
187 * empty into state (CDS_WFS_STATE_LAST).
188 */
189 extern struct cds_wfs_node *
190 cds_wfs_pop_with_state_blocking(struct cds_wfs_stack *s, int *state);
191
192 /*
193 * cds_wfs_pop_all_blocking: pop all nodes from a stack.
194 *
195 * Calls __cds_wfs_pop_all with an internal pop mutex held.
196 */
197 extern struct cds_wfs_head *cds_wfs_pop_all_blocking(struct cds_wfs_stack *s);
198
199 /*
200 * cds_wfs_first: get first node of a popped stack.
201 *
202 * Content written into the node before enqueue is guaranteed to be
203 * consistent, but no other memory ordering is ensured.
204 *
205 * Used by for-like iteration macros in urcu/wfstack.h:
206 * cds_wfs_for_each_blocking()
207 * cds_wfs_for_each_blocking_safe()
208 *
209 * Returns NULL if popped stack is empty, top stack node otherwise.
210 */
211 extern struct cds_wfs_node *cds_wfs_first(struct cds_wfs_head *head);
212
213 /*
214 * cds_wfs_next_blocking: get next node of a popped stack.
215 *
216 * Content written into the node before enqueue is guaranteed to be
217 * consistent, but no other memory ordering is ensured.
218 *
219 * Used by for-like iteration macros in urcu/wfstack.h:
220 * cds_wfs_for_each_blocking()
221 * cds_wfs_for_each_blocking_safe()
222 *
223 * Returns NULL if reached end of popped stack, non-NULL next stack
224 * node otherwise.
225 */
226 extern struct cds_wfs_node *cds_wfs_next_blocking(struct cds_wfs_node *node);
227
228 /*
229 * cds_wfs_next_nonblocking: get next node of a popped stack.
230 *
231 * Same as cds_wfs_next_blocking, but returns CDS_WFS_WOULDBLOCK if it
232 * needs to block.
233 */
234 extern struct cds_wfs_node *cds_wfs_next_nonblocking(struct cds_wfs_node *node);
235
236 /*
237 * cds_wfs_pop_lock: lock stack pop-protection mutex.
238 */
239 extern void cds_wfs_pop_lock(struct cds_wfs_stack *s);
240
241 /*
242 * cds_wfs_pop_unlock: unlock stack pop-protection mutex.
243 */
244 extern void cds_wfs_pop_unlock(struct cds_wfs_stack *s);
245
246 /*
247 * __cds_wfs_pop_blocking: pop a node from the stack.
248 *
249 * Returns NULL if stack is empty.
250 *
251 * __cds_wfs_pop_blocking needs to be synchronized using one of the
252 * following techniques:
253 *
254 * 1) Calling __cds_wfs_pop_blocking under rcu read lock critical
255 * section. The caller must wait for a grace period to pass before
256 * freeing the returned node or modifying the cds_wfs_node structure.
257 * 2) Using mutual exclusion (e.g. mutexes) to protect
258 * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers.
259 * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
260 * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
261 */
262 extern struct cds_wfs_node *__cds_wfs_pop_blocking(cds_wfs_stack_ptr_t u_stack);
263
264 /*
265 * __cds_wfs_pop_with_state_blocking: pop a node from the stack, with state.
266 *
267 * Same as __cds_wfs_pop_blocking, but stores whether the stack was
268 * empty into state (CDS_WFS_STATE_LAST).
269 */
270 extern struct cds_wfs_node *
271 __cds_wfs_pop_with_state_blocking(cds_wfs_stack_ptr_t u_stack,
272 int *state);
273
274 /*
275 * __cds_wfs_pop_nonblocking: pop a node from the stack.
276 *
277 * Same as __cds_wfs_pop_blocking, but returns CDS_WFS_WOULDBLOCK if
278 * it needs to block.
279 */
280 extern struct cds_wfs_node *__cds_wfs_pop_nonblocking(cds_wfs_stack_ptr_t u_stack);
281
282 /*
283 * __cds_wfs_pop_with_state_nonblocking: pop a node from the stack, with state.
284 *
285 * Same as __cds_wfs_pop_nonblocking, but stores whether the stack was
286 * empty into state (CDS_WFS_STATE_LAST).
287 */
288 extern struct cds_wfs_node *
289 __cds_wfs_pop_with_state_nonblocking(cds_wfs_stack_ptr_t u_stack,
290 int *state);
291
292 /*
293 * __cds_wfs_pop_all: pop all nodes from a stack.
294 *
295 * __cds_wfs_pop_all does not require any synchronization with other
296 * push, nor with other __cds_wfs_pop_all, but requires synchronization
297 * matching the technique used to synchronize __cds_wfs_pop_blocking:
298 *
299 * 1) If __cds_wfs_pop_blocking is called under rcu read lock critical
300 * section, both __cds_wfs_pop_blocking and cds_wfs_pop_all callers
301 * must wait for a grace period to pass before freeing the returned
302 * node or modifying the cds_wfs_node structure. However, no RCU
303 * read-side critical section is needed around __cds_wfs_pop_all.
304 * 2) Using mutual exclusion (e.g. mutexes) to protect
305 * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers.
306 * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
307 * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
308 */
309 extern struct cds_wfs_head *__cds_wfs_pop_all(cds_wfs_stack_ptr_t u_stack);
310
311 #endif /* !_LGPL_SOURCE */
312
313 #ifdef __cplusplus
314 }
315 #endif
316
317 /*
318 * cds_wfs_for_each_blocking: Iterate over all nodes returned by
319 * __cds_wfs_pop_all().
320 * @head: head of the queue (struct cds_wfs_head pointer).
321 * @node: iterator (struct cds_wfs_node pointer).
322 *
323 * Content written into each node before enqueue is guaranteed to be
324 * consistent, but no other memory ordering is ensured.
325 */
326 #define cds_wfs_for_each_blocking(head, node) \
327 for (node = cds_wfs_first(head); \
328 node != NULL; \
329 node = cds_wfs_next_blocking(node))
330
331 /*
332 * cds_wfs_for_each_blocking_safe: Iterate over all nodes returned by
333 * __cds_wfs_pop_all(). Safe against deletion.
334 * @head: head of the queue (struct cds_wfs_head pointer).
335 * @node: iterator (struct cds_wfs_node pointer).
336 * @n: struct cds_wfs_node pointer holding the next pointer (used
337 * internally).
338 *
339 * Content written into each node before enqueue is guaranteed to be
340 * consistent, but no other memory ordering is ensured.
341 */
342 #define cds_wfs_for_each_blocking_safe(head, node, n) \
343 for (node = cds_wfs_first(head), \
344 n = (node ? cds_wfs_next_blocking(node) : NULL); \
345 node != NULL; \
346 node = n, n = (node ? cds_wfs_next_blocking(node) : NULL))
347
348 #endif /* _URCU_WFSTACK_H */
This page took 0.050368 seconds and 3 git commands to generate.