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 * The transparent union allows calling functions that work on both
84 * struct cds_lfs_stack and struct __cds_lfs_stack on any of those two
87 typedef union __attribute__((__transparent_union__
)) {
88 struct __cds_lfs_stack
*_s
;
89 struct cds_lfs_stack
*s
;
90 } cds_lfs_stack_ptr_t
;
94 #include <urcu/static/lfstack.h>
96 #define cds_lfs_node_init _cds_lfs_node_init
97 #define cds_lfs_init _cds_lfs_init
98 #define cds_lfs_empty _cds_lfs_empty
99 #define cds_lfs_push _cds_lfs_push
101 /* Locking performed internally */
102 #define cds_lfs_pop_blocking _cds_lfs_pop_blocking
103 #define cds_lfs_pop_all_blocking _cds_lfs_pop_all_blocking
105 /* Synchronize pop with internal mutex */
106 #define cds_lfs_pop_lock _cds_lfs_pop_lock
107 #define cds_lfs_pop_unlock _cds_lfs_pop_unlock
109 /* Synchronization ensured by the caller. See synchronization table. */
110 #define __cds_lfs_pop ___cds_lfs_pop
111 #define __cds_lfs_pop_all ___cds_lfs_pop_all
113 #else /* !_LGPL_SOURCE */
116 * cds_lfs_node_init: initialize lock-free stack node.
118 extern void cds_lfs_node_init(struct cds_lfs_node
*node
);
121 * cds_lfs_init: initialize lock-free stack.
123 extern void cds_lfs_init(struct cds_lfs_stack
*s
);
126 * __cds_lfs_init: initialize lock-free stack.
128 extern void __cds_lfs_init(struct __cds_lfs_stack
*s
);
131 * cds_lfs_empty: return whether lock-free stack is empty.
133 * No memory barrier is issued. No mutual exclusion is required.
135 extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s
);
138 * cds_lfs_push: push a node into the stack.
140 * Does not require any synchronization with other push nor pop.
142 * Returns 0 if the stack was empty prior to adding the node.
143 * Returns non-zero otherwise.
145 extern bool cds_lfs_push(cds_lfs_stack_ptr_t s
,
146 struct cds_lfs_node
*node
);
149 * cds_lfs_pop_blocking: pop a node from the stack.
151 * Calls __cds_lfs_pop with an internal pop mutex held.
153 extern struct cds_lfs_node
*cds_lfs_pop_blocking(struct cds_lfs_stack
*s
);
156 * cds_lfs_pop_all_blocking: pop all nodes from a stack.
158 * Calls __cds_lfs_pop_all with an internal pop mutex held.
160 extern struct cds_lfs_head
*cds_lfs_pop_all_blocking(struct cds_lfs_stack
*s
);
163 * cds_lfs_pop_lock: lock stack pop-protection mutex.
165 extern void cds_lfs_pop_lock(struct cds_lfs_stack
*s
);
168 * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
170 extern void cds_lfs_pop_unlock(struct cds_lfs_stack
*s
);
173 * __cds_lfs_pop: pop a node from the stack.
175 * Returns NULL if stack is empty.
177 * __cds_lfs_pop needs to be synchronized using one of the following
180 * 1) Calling __cds_lfs_pop under rcu read lock critical section. The
181 * caller must wait for a grace period to pass before freeing the
182 * returned node or modifying the cds_lfs_node structure.
183 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
184 * and __cds_lfs_pop_all callers.
185 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
186 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
188 extern struct cds_lfs_node
*__cds_lfs_pop(cds_lfs_stack_ptr_t s
);
191 * __cds_lfs_pop_all: pop all nodes from a stack.
193 * __cds_lfs_pop_all does not require any synchronization with other
194 * push, nor with other __cds_lfs_pop_all, but requires synchronization
195 * matching the technique used to synchronize __cds_lfs_pop:
197 * 1) If __cds_lfs_pop is called under rcu read lock critical section,
198 * both __cds_lfs_pop and cds_lfs_pop_all callers must wait for a
199 * grace period to pass before freeing the returned node or modifying
200 * the cds_lfs_node structure. However, no RCU read-side critical
201 * section is needed around __cds_lfs_pop_all.
202 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
203 * __cds_lfs_pop_all callers.
204 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
205 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
207 extern struct cds_lfs_head
*__cds_lfs_pop_all(cds_lfs_stack_ptr_t s
);
209 #endif /* !_LGPL_SOURCE */
212 * cds_lfs_for_each: Iterate over all nodes returned by
214 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
215 * @__node: node to use as iterator (struct cds_lfs_node pointer).
217 * Content written into each node before push is guaranteed to be
218 * consistent, but no other memory ordering is ensured.
220 #define cds_lfs_for_each(__head, __node) \
221 for (__node = &__head->node; \
223 __node = __node->next)
226 * cds_lfs_for_each_safe: Iterate over all nodes returned by
227 * __cds_lfs_pop_all, safe against node deletion.
228 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
229 * @__node: node to use as iterator (struct cds_lfs_node pointer).
230 * @__n: struct cds_lfs_node pointer holding the next pointer (used
233 * Content written into each node before push is guaranteed to be
234 * consistent, but no other memory ordering is ensured.
236 #define cds_lfs_for_each_safe(__head, __node, __n) \
237 for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
239 __node = __n, __n = (__node ? __node->next : NULL))
245 #endif /* _URCU_LFSTACK_H */
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