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
36 * Stack implementing push, pop, pop_all operations, as well as iterator
37 * on the stack head returned by pop_all.
39 * Synchronization table:
41 * External synchronization techniques described in the API below is
42 * required between pairs marked with "X". No external synchronization
43 * required between pairs marked with "-".
45 * cds_lfs_push __cds_lfs_pop __cds_lfs_pop_all
48 * __cds_lfs_pop_all - X -
50 * cds_lfs_pop_blocking and cds_lfs_pop_all_blocking use an internal
51 * mutex to provide synchronization.
55 * struct cds_lfs_node is returned by cds_lfs_pop, and also used as
56 * iterator on stack. It is not safe to dereference the node next
57 * pointer when returned by cds_lfs_pop.
60 struct cds_lfs_node
*next
;
64 * struct cds_lfs_head is returned by __cds_lfs_pop_all, and can be used
65 * to begin iteration on the stack. "node" needs to be the first field
66 * of cds_lfs_head, so the end-of-stack pointer value can be used for
70 struct cds_lfs_node node
;
73 struct __cds_lfs_stack
{
74 struct cds_lfs_head
*head
;
77 struct cds_lfs_stack
{
78 struct cds_lfs_head
*head
;
83 * In C, the transparent union allows calling functions that work on
84 * both struct cds_lfs_stack and struct __cds_lfs_stack on any of those
87 * In C++, implement static inline wrappers using function overloading
88 * to obtain an API similar to C.
90 * Avoid complaints from clang++ not knowing the transparent union
93 #if defined(__clang__)
94 #pragma clang diagnostic push
95 #pragma clang diagnostic ignored "-Wignored-attributes"
98 struct __cds_lfs_stack
*_s
;
99 struct cds_lfs_stack
*s
;
100 } __attribute__((__transparent_union__
)) cds_lfs_stack_ptr_t
;
101 #if defined(__clang__)
102 #pragma clang diagnostic pop
107 #include <urcu/static/lfstack.h>
109 #define cds_lfs_node_init _cds_lfs_node_init
110 #define cds_lfs_init _cds_lfs_init
111 #define cds_lfs_destroy _cds_lfs_destroy
112 #define __cds_lfs_init ___cds_lfs_init
113 #define cds_lfs_empty _cds_lfs_empty
114 #define cds_lfs_push _cds_lfs_push
116 /* Locking performed internally */
117 #define cds_lfs_pop_blocking _cds_lfs_pop_blocking
118 #define cds_lfs_pop_all_blocking _cds_lfs_pop_all_blocking
120 /* Synchronize pop with internal mutex */
121 #define cds_lfs_pop_lock _cds_lfs_pop_lock
122 #define cds_lfs_pop_unlock _cds_lfs_pop_unlock
124 /* Synchronization ensured by the caller. See synchronization table. */
125 #define __cds_lfs_pop ___cds_lfs_pop
126 #define __cds_lfs_pop_all ___cds_lfs_pop_all
128 #else /* !_LGPL_SOURCE */
131 * cds_lfs_node_init: initialize lock-free stack node.
133 extern void cds_lfs_node_init(struct cds_lfs_node
*node
);
136 * cds_lfs_init: initialize lock-free stack (with locking). Pair with
139 extern void cds_lfs_init(struct cds_lfs_stack
*s
);
142 * cds_lfs_destroy: destroy lock-free stack (with lock). Pair with
145 extern void cds_lfs_destroy(struct cds_lfs_stack
*s
);
148 * __cds_lfs_init: initialize lock-free stack (without lock).
149 * Don't pair with any destroy function.
151 extern void __cds_lfs_init(struct __cds_lfs_stack
*s
);
154 * cds_lfs_empty: return whether lock-free stack is empty.
156 * No memory barrier is issued. No mutual exclusion is required.
158 extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s
);
161 * cds_lfs_push: push a node into the stack.
163 * Does not require any synchronization with other push nor pop.
165 * Returns 0 if the stack was empty prior to adding the node.
166 * Returns non-zero otherwise.
168 extern bool cds_lfs_push(cds_lfs_stack_ptr_t s
,
169 struct cds_lfs_node
*node
);
172 * cds_lfs_pop_blocking: pop a node from the stack.
174 * Calls __cds_lfs_pop with an internal pop mutex held.
176 extern struct cds_lfs_node
*cds_lfs_pop_blocking(struct cds_lfs_stack
*s
);
179 * cds_lfs_pop_all_blocking: pop all nodes from a stack.
181 * Calls __cds_lfs_pop_all with an internal pop mutex held.
183 extern struct cds_lfs_head
*cds_lfs_pop_all_blocking(struct cds_lfs_stack
*s
);
186 * cds_lfs_pop_lock: lock stack pop-protection mutex.
188 extern void cds_lfs_pop_lock(struct cds_lfs_stack
*s
);
191 * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
193 extern void cds_lfs_pop_unlock(struct cds_lfs_stack
*s
);
196 * __cds_lfs_pop: pop a node from the stack.
198 * Returns NULL if stack is empty.
200 * __cds_lfs_pop needs to be synchronized using one of the following
203 * 1) Calling __cds_lfs_pop under rcu read lock critical section.
204 * Both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a
205 * grace period to pass before freeing the returned node or pushing
206 * the node back into the stack. It is valid to overwrite the content
207 * of cds_lfs_node immediately after __cds_lfs_pop and
209 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
210 * and __cds_lfs_pop_all callers.
211 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
212 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
214 extern struct cds_lfs_node
*__cds_lfs_pop(cds_lfs_stack_ptr_t s
);
217 * __cds_lfs_pop_all: pop all nodes from a stack.
219 * __cds_lfs_pop_all does not require any synchronization with other
220 * push, nor with other __cds_lfs_pop_all, but requires synchronization
221 * matching the technique used to synchronize __cds_lfs_pop:
223 * 1) If __cds_lfs_pop is called under rcu read lock critical section,
224 * both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a
225 * grace period to pass before freeing the returned node or pushing
226 * the node back into the stack. It is valid to overwrite the content
227 * of cds_lfs_node immediately after __cds_lfs_pop and
228 * __cds_lfs_pop_all. No RCU read-side critical section is needed
229 * around __cds_lfs_pop_all.
230 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
231 * __cds_lfs_pop_all callers.
232 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
233 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
235 extern struct cds_lfs_head
*__cds_lfs_pop_all(cds_lfs_stack_ptr_t s
);
237 #endif /* !_LGPL_SOURCE */
240 * cds_lfs_for_each: Iterate over all nodes returned by
242 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
243 * @__node: node to use as iterator (struct cds_lfs_node pointer).
245 * Content written into each node before push is guaranteed to be
246 * consistent, but no other memory ordering is ensured.
248 #define cds_lfs_for_each(__head, __node) \
249 for (__node = &__head->node; \
251 __node = __node->next)
254 * cds_lfs_for_each_safe: Iterate over all nodes returned by
255 * __cds_lfs_pop_all, safe against node deletion.
256 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
257 * @__node: node to use as iterator (struct cds_lfs_node pointer).
258 * @__n: struct cds_lfs_node pointer holding the next pointer (used
261 * Content written into each node before push is guaranteed to be
262 * consistent, but no other memory ordering is ensured.
264 #define cds_lfs_for_each_safe(__head, __node, __n) \
265 for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
267 __node = __n, __n = (__node ? __node->next : NULL))
273 * In C++, implement static inline wrappers using function overloading
274 * to obtain an API similar to C.
277 static inline cds_lfs_stack_ptr_t
cds_lfs_stack_cast(struct __cds_lfs_stack
*s
)
279 cds_lfs_stack_ptr_t ret
= {
285 static inline cds_lfs_stack_ptr_t
cds_lfs_stack_cast(struct cds_lfs_stack
*s
)
287 cds_lfs_stack_ptr_t ret
= {
293 template<typename T
> static inline bool cds_lfs_empty(T s
)
295 return cds_lfs_empty(cds_lfs_stack_cast(s
));
298 template<typename T
> static inline bool cds_lfs_push(T s
,
299 struct cds_lfs_node
*node
)
301 return cds_lfs_push(cds_lfs_stack_cast(s
), node
);
304 template<typename T
> static inline struct cds_lfs_node
*__cds_lfs_pop(T s
)
306 return __cds_lfs_pop(cds_lfs_stack_cast(s
));
309 template<typename T
> static inline struct cds_lfs_head
*__cds_lfs_pop_all(T s
)
311 return __cds_lfs_pop_all(cds_lfs_stack_cast(s
));
314 #endif /* __cplusplus */
316 #endif /* _URCU_LFSTACK_H */
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