Fix: handle sys_futex() FUTEX_WAIT interrupted by signal
[urcu.git] / urcu / lfstack.h
1 #ifndef _URCU_LFSTACK_H
2 #define _URCU_LFSTACK_H
3
4 /*
5 * lfstack.h
6 *
7 * Userspace RCU library - Lock-Free Stack
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 #ifdef __cplusplus
27 extern "C" {
28 #endif
29
30 #include <stdbool.h>
31 #include <pthread.h>
32
33 /*
34 * Lock-free stack.
35 *
36 * Stack implementing push, pop, pop_all operations, as well as iterator
37 * on the stack head returned by pop_all.
38 *
39 * Synchronization table:
40 *
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 "-".
44 *
45 * cds_lfs_push __cds_lfs_pop __cds_lfs_pop_all
46 * cds_lfs_push - - -
47 * __cds_lfs_pop - X X
48 * __cds_lfs_pop_all - X -
49 *
50 * cds_lfs_pop_blocking and cds_lfs_pop_all_blocking use an internal
51 * mutex to provide synchronization.
52 */
53
54 /*
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.
58 */
59 struct cds_lfs_node {
60 struct cds_lfs_node *next;
61 };
62
63 /*
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
67 * both types.
68 */
69 struct cds_lfs_head {
70 struct cds_lfs_node node;
71 };
72
73 struct __cds_lfs_stack {
74 struct cds_lfs_head *head;
75 };
76
77 struct cds_lfs_stack {
78 struct cds_lfs_head *head;
79 pthread_mutex_t lock;
80 };
81
82 /*
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
85 * types.
86 */
87 typedef union {
88 struct __cds_lfs_stack *_s;
89 struct cds_lfs_stack *s;
90 } __attribute__((__transparent_union__)) cds_lfs_stack_ptr_t;
91
92 #ifdef _LGPL_SOURCE
93
94 #include <urcu/static/lfstack.h>
95
96 #define cds_lfs_node_init _cds_lfs_node_init
97 #define cds_lfs_init _cds_lfs_init
98 #define __cds_lfs_init ___cds_lfs_init
99 #define cds_lfs_empty _cds_lfs_empty
100 #define cds_lfs_push _cds_lfs_push
101
102 /* Locking performed internally */
103 #define cds_lfs_pop_blocking _cds_lfs_pop_blocking
104 #define cds_lfs_pop_all_blocking _cds_lfs_pop_all_blocking
105
106 /* Synchronize pop with internal mutex */
107 #define cds_lfs_pop_lock _cds_lfs_pop_lock
108 #define cds_lfs_pop_unlock _cds_lfs_pop_unlock
109
110 /* Synchronization ensured by the caller. See synchronization table. */
111 #define __cds_lfs_pop ___cds_lfs_pop
112 #define __cds_lfs_pop_all ___cds_lfs_pop_all
113
114 #else /* !_LGPL_SOURCE */
115
116 /*
117 * cds_lfs_node_init: initialize lock-free stack node.
118 */
119 extern void cds_lfs_node_init(struct cds_lfs_node *node);
120
121 /*
122 * cds_lfs_init: initialize lock-free stack.
123 */
124 extern void cds_lfs_init(struct cds_lfs_stack *s);
125
126 /*
127 * __cds_lfs_init: initialize lock-free stack.
128 */
129 extern void __cds_lfs_init(struct __cds_lfs_stack *s);
130
131 /*
132 * cds_lfs_empty: return whether lock-free stack is empty.
133 *
134 * No memory barrier is issued. No mutual exclusion is required.
135 */
136 extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s);
137
138 /*
139 * cds_lfs_push: push a node into the stack.
140 *
141 * Does not require any synchronization with other push nor pop.
142 *
143 * Returns 0 if the stack was empty prior to adding the node.
144 * Returns non-zero otherwise.
145 */
146 extern bool cds_lfs_push(cds_lfs_stack_ptr_t s,
147 struct cds_lfs_node *node);
148
149 /*
150 * cds_lfs_pop_blocking: pop a node from the stack.
151 *
152 * Calls __cds_lfs_pop with an internal pop mutex held.
153 */
154 extern struct cds_lfs_node *cds_lfs_pop_blocking(struct cds_lfs_stack *s);
155
156 /*
157 * cds_lfs_pop_all_blocking: pop all nodes from a stack.
158 *
159 * Calls __cds_lfs_pop_all with an internal pop mutex held.
160 */
161 extern struct cds_lfs_head *cds_lfs_pop_all_blocking(struct cds_lfs_stack *s);
162
163 /*
164 * cds_lfs_pop_lock: lock stack pop-protection mutex.
165 */
166 extern void cds_lfs_pop_lock(struct cds_lfs_stack *s);
167
168 /*
169 * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
170 */
171 extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s);
172
173 /*
174 * __cds_lfs_pop: pop a node from the stack.
175 *
176 * Returns NULL if stack is empty.
177 *
178 * __cds_lfs_pop needs to be synchronized using one of the following
179 * techniques:
180 *
181 * 1) Calling __cds_lfs_pop under rcu read lock critical section. The
182 * caller must wait for a grace period to pass before freeing the
183 * returned node or modifying the cds_lfs_node structure.
184 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
185 * and __cds_lfs_pop_all callers.
186 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
187 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
188 */
189 extern struct cds_lfs_node *__cds_lfs_pop(cds_lfs_stack_ptr_t s);
190
191 /*
192 * __cds_lfs_pop_all: pop all nodes from a stack.
193 *
194 * __cds_lfs_pop_all does not require any synchronization with other
195 * push, nor with other __cds_lfs_pop_all, but requires synchronization
196 * matching the technique used to synchronize __cds_lfs_pop:
197 *
198 * 1) If __cds_lfs_pop is called under rcu read lock critical section,
199 * both __cds_lfs_pop and cds_lfs_pop_all callers must wait for a
200 * grace period to pass before freeing the returned node or modifying
201 * the cds_lfs_node structure. However, no RCU read-side critical
202 * section is needed around __cds_lfs_pop_all.
203 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
204 * __cds_lfs_pop_all callers.
205 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
206 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
207 */
208 extern struct cds_lfs_head *__cds_lfs_pop_all(cds_lfs_stack_ptr_t s);
209
210 #endif /* !_LGPL_SOURCE */
211
212 /*
213 * cds_lfs_for_each: Iterate over all nodes returned by
214 * __cds_lfs_pop_all.
215 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
216 * @__node: node to use as iterator (struct cds_lfs_node pointer).
217 *
218 * Content written into each node before push is guaranteed to be
219 * consistent, but no other memory ordering is ensured.
220 */
221 #define cds_lfs_for_each(__head, __node) \
222 for (__node = &__head->node; \
223 __node != NULL; \
224 __node = __node->next)
225
226 /*
227 * cds_lfs_for_each_safe: Iterate over all nodes returned by
228 * __cds_lfs_pop_all, safe against node deletion.
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).
231 * @__n: struct cds_lfs_node pointer holding the next pointer (used
232 * internally).
233 *
234 * Content written into each node before push is guaranteed to be
235 * consistent, but no other memory ordering is ensured.
236 */
237 #define cds_lfs_for_each_safe(__head, __node, __n) \
238 for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
239 __node != NULL; \
240 __node = __n, __n = (__node ? __node->next : NULL))
241
242 #ifdef __cplusplus
243 }
244 #endif
245
246 #endif /* _URCU_LFSTACK_H */
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