Fix: powerpc32: transparent unions alter calling convention
[urcu.git] / include / urcu / lfstack.h
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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
27extern "C" {
28#endif
29
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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 */
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59struct cds_lfs_node {
60 struct cds_lfs_node *next;
61};
62
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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 */
69struct cds_lfs_head {
70 struct cds_lfs_node node;
71};
72
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73struct __cds_lfs_stack {
74 struct cds_lfs_head *head;
75};
76
d3bfcb24 77struct cds_lfs_stack {
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78 struct cds_lfs_head *head;
79 pthread_mutex_t lock;
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80};
81
48a8832b 82/*
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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
85 * two types.
28757437 86 *
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87 * In C++, implement static inline wrappers using function overloading
88 * to obtain an API similar to C.
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89 *
90 * Avoid complaints from clang++ not knowing the transparent union
91 * attribute.
48a8832b 92 */
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93#if defined(__clang__)
94#pragma clang diagnostic push
95#pragma clang diagnostic ignored "-Wignored-attributes"
96#endif
5135c0fd 97typedef union {
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98 struct __cds_lfs_stack *_s;
99 struct cds_lfs_stack *s;
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100} __attribute__((__transparent_union__)) cds_lfs_stack_ptr_t;
101#if defined(__clang__)
102#pragma clang diagnostic pop
103#endif
48a8832b 104
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105#ifdef _LGPL_SOURCE
106
107#include <urcu/static/lfstack.h>
108
109#define cds_lfs_node_init _cds_lfs_node_init
110#define cds_lfs_init _cds_lfs_init
200d100e 111#define cds_lfs_destroy _cds_lfs_destroy
817a0178 112#define __cds_lfs_init ___cds_lfs_init
7294103b 113#define cds_lfs_empty _cds_lfs_empty
d3bfcb24 114#define cds_lfs_push _cds_lfs_push
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115
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
119
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
123
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
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127
128#else /* !_LGPL_SOURCE */
129
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130/*
131 * cds_lfs_node_init: initialize lock-free stack node.
132 */
d3bfcb24 133extern void cds_lfs_node_init(struct cds_lfs_node *node);
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134
135/*
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136 * cds_lfs_init: initialize lock-free stack (with locking). Pair with
137 * cds_lfs_destroy().
7294103b 138 */
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139extern void cds_lfs_init(struct cds_lfs_stack *s);
140
48a8832b 141/*
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142 * cds_lfs_destroy: destroy lock-free stack (with lock). Pair with
143 * cds_lfs_init().
144 */
145extern void cds_lfs_destroy(struct cds_lfs_stack *s);
146
147/*
148 * __cds_lfs_init: initialize lock-free stack (without lock).
149 * Don't pair with any destroy function.
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150 */
151extern void __cds_lfs_init(struct __cds_lfs_stack *s);
152
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153/*
154 * cds_lfs_empty: return whether lock-free stack is empty.
155 *
156 * No memory barrier is issued. No mutual exclusion is required.
157 */
48a8832b 158extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s);
7294103b 159
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160/*
161 * cds_lfs_push: push a node into the stack.
162 *
163 * Does not require any synchronization with other push nor pop.
164 *
165 * Returns 0 if the stack was empty prior to adding the node.
166 * Returns non-zero otherwise.
167 */
48a8832b 168extern bool cds_lfs_push(cds_lfs_stack_ptr_t s,
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169 struct cds_lfs_node *node);
170
171/*
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172 * cds_lfs_pop_blocking: pop a node from the stack.
173 *
174 * Calls __cds_lfs_pop with an internal pop mutex held.
175 */
176extern struct cds_lfs_node *cds_lfs_pop_blocking(struct cds_lfs_stack *s);
177
178/*
179 * cds_lfs_pop_all_blocking: pop all nodes from a stack.
180 *
181 * Calls __cds_lfs_pop_all with an internal pop mutex held.
182 */
183extern struct cds_lfs_head *cds_lfs_pop_all_blocking(struct cds_lfs_stack *s);
184
185/*
186 * cds_lfs_pop_lock: lock stack pop-protection mutex.
187 */
188extern void cds_lfs_pop_lock(struct cds_lfs_stack *s);
189
190/*
191 * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
192 */
193extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s);
194
195/*
196 * __cds_lfs_pop: pop a node from the stack.
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197 *
198 * Returns NULL if stack is empty.
199 *
7294103b 200 * __cds_lfs_pop needs to be synchronized using one of the following
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201 * techniques:
202 *
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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
208 * __cds_lfs_pop_all.
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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).
d3bfcb24 213 */
48a8832b 214extern struct cds_lfs_node *__cds_lfs_pop(cds_lfs_stack_ptr_t s);
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215
216/*
217 * __cds_lfs_pop_all: pop all nodes from a stack.
218 *
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:
222 *
223 * 1) If __cds_lfs_pop is called under rcu read lock critical section,
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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.
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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).
234 */
48a8832b 235extern struct cds_lfs_head *__cds_lfs_pop_all(cds_lfs_stack_ptr_t s);
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236
237#endif /* !_LGPL_SOURCE */
238
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239/*
240 * cds_lfs_for_each: Iterate over all nodes returned by
241 * __cds_lfs_pop_all.
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).
244 *
245 * Content written into each node before push is guaranteed to be
246 * consistent, but no other memory ordering is ensured.
247 */
248#define cds_lfs_for_each(__head, __node) \
249 for (__node = &__head->node; \
250 __node != NULL; \
251 __node = __node->next)
252
253/*
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
259 * internally).
260 *
261 * Content written into each node before push is guaranteed to be
262 * consistent, but no other memory ordering is ensured.
263 */
264#define cds_lfs_for_each_safe(__head, __node, __n) \
265 for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
266 __node != NULL; \
267 __node = __n, __n = (__node ? __node->next : NULL))
268
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269#ifdef __cplusplus
270}
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271
272/*
273 * In C++, implement static inline wrappers using function overloading
274 * to obtain an API similar to C.
275 */
276
3a602ac1 277static inline cds_lfs_stack_ptr_t cds_lfs_stack_cast(struct __cds_lfs_stack *s)
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278{
279 cds_lfs_stack_ptr_t ret = {
280 ._s = s,
281 };
282 return ret;
283}
284
285static inline cds_lfs_stack_ptr_t cds_lfs_stack_cast(struct cds_lfs_stack *s)
286{
287 cds_lfs_stack_ptr_t ret = {
288 .s = s,
289 };
290 return ret;
291}
292
9298902c 293template<typename T> static inline bool cds_lfs_empty(T s)
e9349020 294{
3a602ac1 295 return cds_lfs_empty(cds_lfs_stack_cast(s));
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296}
297
9298902c 298template<typename T> static inline bool cds_lfs_push(T s,
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299 struct cds_lfs_node *node)
300{
301 return cds_lfs_push(cds_lfs_stack_cast(s), node);
302}
303
9298902c 304template<typename T> static inline struct cds_lfs_node *__cds_lfs_pop(T s)
e9349020 305{
3a602ac1 306 return __cds_lfs_pop(cds_lfs_stack_cast(s));
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307}
308
9298902c 309template<typename T> static inline struct cds_lfs_head *__cds_lfs_pop_all(T s)
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310{
311 return __cds_lfs_pop_all(cds_lfs_stack_cast(s));
312}
313
314#endif /* __cplusplus */
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315
316#endif /* _URCU_LFSTACK_H */
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