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
88 struct __cds_lfs_stack
*_s
;
89 struct cds_lfs_stack
*s
;
90 } __attribute__((__transparent_union__
)) 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_destroy _cds_lfs_destroy
99 #define __cds_lfs_init ___cds_lfs_init
100 #define cds_lfs_empty _cds_lfs_empty
101 #define cds_lfs_push _cds_lfs_push
103 /* Locking performed internally */
104 #define cds_lfs_pop_blocking _cds_lfs_pop_blocking
105 #define cds_lfs_pop_all_blocking _cds_lfs_pop_all_blocking
107 /* Synchronize pop with internal mutex */
108 #define cds_lfs_pop_lock _cds_lfs_pop_lock
109 #define cds_lfs_pop_unlock _cds_lfs_pop_unlock
111 /* Synchronization ensured by the caller. See synchronization table. */
112 #define __cds_lfs_pop ___cds_lfs_pop
113 #define __cds_lfs_pop_all ___cds_lfs_pop_all
115 #else /* !_LGPL_SOURCE */
118 * cds_lfs_node_init: initialize lock-free stack node.
120 extern void cds_lfs_node_init(struct cds_lfs_node
*node
);
123 * cds_lfs_init: initialize lock-free stack (with locking). Pair with
126 extern void cds_lfs_init(struct cds_lfs_stack
*s
);
129 * cds_lfs_destroy: destroy lock-free stack (with lock). Pair with
132 extern void cds_lfs_destroy(struct cds_lfs_stack
*s
);
135 * __cds_lfs_init: initialize lock-free stack (without lock).
136 * Don't pair with any destroy function.
138 extern void __cds_lfs_init(struct __cds_lfs_stack
*s
);
141 * cds_lfs_empty: return whether lock-free stack is empty.
143 * No memory barrier is issued. No mutual exclusion is required.
145 extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s
);
148 * cds_lfs_push: push a node into the stack.
150 * Does not require any synchronization with other push nor pop.
152 * Returns 0 if the stack was empty prior to adding the node.
153 * Returns non-zero otherwise.
155 extern bool cds_lfs_push(cds_lfs_stack_ptr_t s
,
156 struct cds_lfs_node
*node
);
159 * cds_lfs_pop_blocking: pop a node from the stack.
161 * Calls __cds_lfs_pop with an internal pop mutex held.
163 extern struct cds_lfs_node
*cds_lfs_pop_blocking(struct cds_lfs_stack
*s
);
166 * cds_lfs_pop_all_blocking: pop all nodes from a stack.
168 * Calls __cds_lfs_pop_all with an internal pop mutex held.
170 extern struct cds_lfs_head
*cds_lfs_pop_all_blocking(struct cds_lfs_stack
*s
);
173 * cds_lfs_pop_lock: lock stack pop-protection mutex.
175 extern void cds_lfs_pop_lock(struct cds_lfs_stack
*s
);
178 * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
180 extern void cds_lfs_pop_unlock(struct cds_lfs_stack
*s
);
183 * __cds_lfs_pop: pop a node from the stack.
185 * Returns NULL if stack is empty.
187 * __cds_lfs_pop needs to be synchronized using one of the following
190 * 1) Calling __cds_lfs_pop under rcu read lock critical section.
191 * Both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a
192 * grace period to pass before freeing the returned node or pushing
193 * the node back into the stack. It is valid to overwrite the content
194 * of cds_lfs_node immediately after __cds_lfs_pop and
196 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
197 * and __cds_lfs_pop_all callers.
198 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
199 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
201 extern struct cds_lfs_node
*__cds_lfs_pop(cds_lfs_stack_ptr_t s
);
204 * __cds_lfs_pop_all: pop all nodes from a stack.
206 * __cds_lfs_pop_all does not require any synchronization with other
207 * push, nor with other __cds_lfs_pop_all, but requires synchronization
208 * matching the technique used to synchronize __cds_lfs_pop:
210 * 1) If __cds_lfs_pop is called under rcu read lock critical section,
211 * both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a
212 * grace period to pass before freeing the returned node or pushing
213 * the node back into the stack. It is valid to overwrite the content
214 * of cds_lfs_node immediately after __cds_lfs_pop and
215 * __cds_lfs_pop_all. No RCU read-side critical section is needed
216 * around __cds_lfs_pop_all.
217 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
218 * __cds_lfs_pop_all callers.
219 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
220 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
222 extern struct cds_lfs_head
*__cds_lfs_pop_all(cds_lfs_stack_ptr_t s
);
224 #endif /* !_LGPL_SOURCE */
227 * cds_lfs_for_each: Iterate over all nodes returned by
229 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
230 * @__node: node to use as iterator (struct cds_lfs_node pointer).
232 * Content written into each node before push is guaranteed to be
233 * consistent, but no other memory ordering is ensured.
235 #define cds_lfs_for_each(__head, __node) \
236 for (__node = &__head->node; \
238 __node = __node->next)
241 * cds_lfs_for_each_safe: Iterate over all nodes returned by
242 * __cds_lfs_pop_all, safe against node deletion.
243 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
244 * @__node: node to use as iterator (struct cds_lfs_node pointer).
245 * @__n: struct cds_lfs_node pointer holding the next pointer (used
248 * Content written into each node before push is guaranteed to be
249 * consistent, but no other memory ordering is ensured.
251 #define cds_lfs_for_each_safe(__head, __node, __n) \
252 for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
254 __node = __n, __n = (__node ? __node->next : NULL))
260 #endif /* _URCU_LFSTACK_H */
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