1 #ifndef _URCU_LFSTACK_H
2 #define _URCU_LFSTACK_H
7 * Userspace RCU library - Lock-Free Stack
9 * Copyright 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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.
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.
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
32 #include <urcu/compiler.h>
37 * Stack implementing push, pop, pop_all operations, as well as iterator
38 * on the stack head returned by pop_all.
40 * Synchronization table:
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 "-".
46 * cds_lfs_push __cds_lfs_pop __cds_lfs_pop_all
49 * __cds_lfs_pop_all - X -
51 * cds_lfs_pop_blocking and cds_lfs_pop_all_blocking use an internal
52 * mutex to provide synchronization.
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.
61 struct cds_lfs_node
*next
;
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
71 struct cds_lfs_node node
;
74 struct __cds_lfs_stack
{
75 struct cds_lfs_head
*head
;
78 struct cds_lfs_stack
{
79 struct cds_lfs_head
*head
;
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
88 * In C++, implement static inline wrappers using function overloading
89 * to obtain an API similar to C.
92 struct __cds_lfs_stack
*_s
;
93 struct cds_lfs_stack
*s
;
94 } caa_c_transparent_union cds_lfs_stack_ptr_t
;
98 #include <urcu/static/lfstack.h>
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
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
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
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
119 #else /* !_LGPL_SOURCE */
122 * cds_lfs_node_init: initialize lock-free stack node.
124 extern void cds_lfs_node_init(struct cds_lfs_node
*node
);
127 * cds_lfs_init: initialize lock-free stack (with locking). Pair with
130 extern void cds_lfs_init(struct cds_lfs_stack
*s
);
133 * cds_lfs_destroy: destroy lock-free stack (with lock). Pair with
136 extern void cds_lfs_destroy(struct cds_lfs_stack
*s
);
139 * __cds_lfs_init: initialize lock-free stack (without lock).
140 * Don't pair with any destroy function.
142 extern void __cds_lfs_init(struct __cds_lfs_stack
*s
);
145 * cds_lfs_empty: return whether lock-free stack is empty.
147 * No memory barrier is issued. No mutual exclusion is required.
149 extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s
);
152 * cds_lfs_push: push a node into the stack.
154 * Does not require any synchronization with other push nor pop.
156 * Returns 0 if the stack was empty prior to adding the node.
157 * Returns non-zero otherwise.
159 extern bool cds_lfs_push(cds_lfs_stack_ptr_t s
,
160 struct cds_lfs_node
*node
);
163 * cds_lfs_pop_blocking: pop a node from the stack.
165 * Calls __cds_lfs_pop with an internal pop mutex held.
167 extern struct cds_lfs_node
*cds_lfs_pop_blocking(struct cds_lfs_stack
*s
);
170 * cds_lfs_pop_all_blocking: pop all nodes from a stack.
172 * Calls __cds_lfs_pop_all with an internal pop mutex held.
174 extern struct cds_lfs_head
*cds_lfs_pop_all_blocking(struct cds_lfs_stack
*s
);
177 * cds_lfs_pop_lock: lock stack pop-protection mutex.
179 extern void cds_lfs_pop_lock(struct cds_lfs_stack
*s
);
182 * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
184 extern void cds_lfs_pop_unlock(struct cds_lfs_stack
*s
);
187 * __cds_lfs_pop: pop a node from the stack.
189 * Returns NULL if stack is empty.
191 * __cds_lfs_pop needs to be synchronized using one of the following
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
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).
205 extern struct cds_lfs_node
*__cds_lfs_pop(cds_lfs_stack_ptr_t s
);
208 * __cds_lfs_pop_all: pop all nodes from a stack.
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:
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).
226 extern struct cds_lfs_head
*__cds_lfs_pop_all(cds_lfs_stack_ptr_t s
);
228 #endif /* !_LGPL_SOURCE */
231 * cds_lfs_for_each: Iterate over all nodes returned by
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).
236 * Content written into each node before push is guaranteed to be
237 * consistent, but no other memory ordering is ensured.
239 #define cds_lfs_for_each(__head, __node) \
240 for (__node = &__head->node; \
242 __node = __node->next)
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
252 * Content written into each node before push is guaranteed to be
253 * consistent, but no other memory ordering is ensured.
255 #define cds_lfs_for_each_safe(__head, __node, __n) \
256 for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
258 __node = __n, __n = (__node ? __node->next : NULL))
264 * In C++, implement static inline wrappers using function overloading
265 * to obtain an API similar to C.
268 static inline cds_lfs_stack_ptr_t
cds_lfs_stack_cast(struct __cds_lfs_stack
*s
)
270 cds_lfs_stack_ptr_t ret
= {
276 static inline cds_lfs_stack_ptr_t
cds_lfs_stack_cast(struct cds_lfs_stack
*s
)
278 cds_lfs_stack_ptr_t ret
= {
284 static inline bool cds_lfs_empty(struct __cds_lfs_stack
*s
)
286 return cds_lfs_empty(cds_lfs_stack_cast(s
));
289 static inline bool cds_lfs_empty(struct cds_lfs_stack
*s
)
291 return cds_lfs_empty(cds_lfs_stack_cast(s
));
294 static inline bool cds_lfs_push(struct __cds_lfs_stack
*s
,
295 struct cds_lfs_node
*node
)
297 return cds_lfs_push(cds_lfs_stack_cast(s
), node
);
300 static inline bool cds_lfs_push(struct cds_lfs_stack
*s
,
301 struct cds_lfs_node
*node
)
303 return cds_lfs_push(cds_lfs_stack_cast(s
), node
);
306 static inline struct cds_lfs_node
*__cds_lfs_pop(struct __cds_lfs_stack
*s
)
308 return __cds_lfs_pop(cds_lfs_stack_cast(s
));
311 static inline struct cds_lfs_node
*__cds_lfs_pop(struct cds_lfs_stack
*s
)
313 return __cds_lfs_pop(cds_lfs_stack_cast(s
));
316 static inline struct cds_lfs_head
*__cds_lfs_pop_all(struct __cds_lfs_stack
*s
)
318 return __cds_lfs_pop_all(cds_lfs_stack_cast(s
));
321 static inline struct cds_lfs_head
*__cds_lfs_pop_all(struct cds_lfs_stack
*s
)
323 return __cds_lfs_pop_all(cds_lfs_stack_cast(s
));
326 #endif /* __cplusplus */
328 #endif /* _URCU_LFSTACK_H */