| 1 | #ifndef _URCU_WFCQUEUE_H |
| 2 | #define _URCU_WFCQUEUE_H |
| 3 | |
| 4 | /* |
| 5 | * wfcqueue.h |
| 6 | * |
| 7 | * Userspace RCU library - Concurrent Queue with Wait-Free Enqueue/Blocking Dequeue |
| 8 | * |
| 9 | * Copyright 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 10 | * Copyright 2011-2012 - Lai Jiangshan <laijs@cn.fujitsu.com> |
| 11 | * |
| 12 | * This library is free software; you can redistribute it and/or |
| 13 | * modify it under the terms of the GNU Lesser General Public |
| 14 | * License as published by the Free Software Foundation; either |
| 15 | * version 2.1 of the License, or (at your option) any later version. |
| 16 | * |
| 17 | * This library is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 20 | * Lesser General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU Lesser General Public |
| 23 | * License along with this library; if not, write to the Free Software |
| 24 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 25 | */ |
| 26 | |
| 27 | #include <pthread.h> |
| 28 | #include <assert.h> |
| 29 | #include <stdbool.h> |
| 30 | #include <urcu/compiler.h> |
| 31 | #include <urcu/arch.h> |
| 32 | |
| 33 | #ifdef __cplusplus |
| 34 | extern "C" { |
| 35 | #endif |
| 36 | |
| 37 | /* |
| 38 | * Concurrent queue with wait-free enqueue/blocking dequeue. |
| 39 | * |
| 40 | * This queue has been designed and implemented collaboratively by |
| 41 | * Mathieu Desnoyers and Lai Jiangshan. Inspired from |
| 42 | * half-wait-free/half-blocking queue implementation done by Paul E. |
| 43 | * McKenney. |
| 44 | */ |
| 45 | |
| 46 | struct cds_wfcq_node { |
| 47 | struct cds_wfcq_node *next; |
| 48 | }; |
| 49 | |
| 50 | /* |
| 51 | * Do not put head and tail on the same cache-line if concurrent |
| 52 | * enqueue/dequeue are expected from many CPUs. This eliminates |
| 53 | * false-sharing between enqueue and dequeue. |
| 54 | */ |
| 55 | struct cds_wfcq_head { |
| 56 | struct cds_wfcq_node node; |
| 57 | pthread_mutex_t lock; |
| 58 | }; |
| 59 | |
| 60 | struct cds_wfcq_tail { |
| 61 | struct cds_wfcq_node *p; |
| 62 | }; |
| 63 | |
| 64 | #ifdef _LGPL_SOURCE |
| 65 | |
| 66 | #include <urcu/static/wfcqueue.h> |
| 67 | |
| 68 | #define cds_wfcq_node_init _cds_wfcq_node_init |
| 69 | #define cds_wfcq_init _cds_wfcq_init |
| 70 | #define cds_wfcq_empty _cds_wfcq_empty |
| 71 | #define cds_wfcq_enqueue _cds_wfcq_enqueue |
| 72 | |
| 73 | /* Dequeue locking */ |
| 74 | #define cds_wfcq_dequeue_lock _cds_wfcq_dequeue_lock |
| 75 | #define cds_wfcq_dequeue_unlock _cds_wfcq_dequeue_unlock |
| 76 | |
| 77 | /* Locking performed within cds_wfcq calls. */ |
| 78 | #define cds_wfcq_dequeue_blocking _cds_wfcq_dequeue_blocking |
| 79 | #define cds_wfcq_splice_blocking _cds_wfcq_splice_blocking |
| 80 | #define cds_wfcq_first_blocking _cds_wfcq_first_blocking |
| 81 | #define cds_wfcq_next_blocking _cds_wfcq_next_blocking |
| 82 | |
| 83 | /* Locking ensured by caller by holding cds_wfcq_dequeue_lock() */ |
| 84 | #define __cds_wfcq_dequeue_blocking ___cds_wfcq_dequeue_blocking |
| 85 | #define __cds_wfcq_splice_blocking ___cds_wfcq_splice_blocking |
| 86 | #define __cds_wfcq_first_blocking ___cds_wfcq_first_blocking |
| 87 | #define __cds_wfcq_next_blocking ___cds_wfcq_next_blocking |
| 88 | |
| 89 | #else /* !_LGPL_SOURCE */ |
| 90 | |
| 91 | /* |
| 92 | * Mutual exclusion of cds_wfcq_* / __cds_wfcq_* API |
| 93 | * |
| 94 | * Unless otherwise stated, the caller must ensure mutual exclusion of |
| 95 | * queue update operations "dequeue" and "splice" (for source queue). |
| 96 | * Queue read operations "first" and "next", which are used by |
| 97 | * "for_each" iterations, need to be protected against concurrent |
| 98 | * "dequeue" and "splice" (for source queue) by the caller. |
| 99 | * "enqueue", "splice" (for destination queue), and "empty" are the only |
| 100 | * operations that can be used without any mutual exclusion. |
| 101 | * Mutual exclusion can be ensured by holding cds_wfcq_dequeue_lock(). |
| 102 | * |
| 103 | * For convenience, cds_wfcq_dequeue_blocking() and |
| 104 | * cds_wfcq_splice_blocking() hold the dequeue lock. |
| 105 | * |
| 106 | * Besides locking, mutual exclusion of dequeue, splice and iteration |
| 107 | * can be ensured by performing all of those operations from a single |
| 108 | * thread, without requiring any lock. |
| 109 | */ |
| 110 | |
| 111 | /* |
| 112 | * cds_wfcq_node_init: initialize wait-free queue node. |
| 113 | */ |
| 114 | extern void cds_wfcq_node_init(struct cds_wfcq_node *node); |
| 115 | |
| 116 | /* |
| 117 | * cds_wfcq_init: initialize wait-free queue. |
| 118 | */ |
| 119 | extern void cds_wfcq_init(struct cds_wfcq_head *head, |
| 120 | struct cds_wfcq_tail *tail); |
| 121 | |
| 122 | /* |
| 123 | * cds_wfcq_empty: return whether wait-free queue is empty. |
| 124 | * |
| 125 | * No memory barrier is issued. No mutual exclusion is required. |
| 126 | */ |
| 127 | extern bool cds_wfcq_empty(struct cds_wfcq_head *head, |
| 128 | struct cds_wfcq_tail *tail); |
| 129 | |
| 130 | /* |
| 131 | * cds_wfcq_dequeue_lock: take the dequeue mutual exclusion lock. |
| 132 | */ |
| 133 | extern void cds_wfcq_dequeue_lock(struct cds_wfcq_head *head, |
| 134 | struct cds_wfcq_tail *tail); |
| 135 | |
| 136 | /* |
| 137 | * cds_wfcq_dequeue_unlock: release the dequeue mutual exclusion lock. |
| 138 | */ |
| 139 | extern void cds_wfcq_dequeue_unlock(struct cds_wfcq_head *head, |
| 140 | struct cds_wfcq_tail *tail); |
| 141 | |
| 142 | /* |
| 143 | * cds_wfcq_enqueue: enqueue a node into a wait-free queue. |
| 144 | * |
| 145 | * Issues a full memory barrier before enqueue. No mutual exclusion is |
| 146 | * required. |
| 147 | */ |
| 148 | extern void cds_wfcq_enqueue(struct cds_wfcq_head *head, |
| 149 | struct cds_wfcq_tail *tail, |
| 150 | struct cds_wfcq_node *node); |
| 151 | |
| 152 | /* |
| 153 | * cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue. |
| 154 | * |
| 155 | * Content written into the node before enqueue is guaranteed to be |
| 156 | * consistent, but no other memory ordering is ensured. |
| 157 | * It is valid to reuse and free a dequeued node immediately. |
| 158 | * Mutual exlusion with cds_wfcq_dequeue_blocking and dequeue lock is |
| 159 | * ensured. |
| 160 | */ |
| 161 | extern struct cds_wfcq_node *cds_wfcq_dequeue_blocking( |
| 162 | struct cds_wfcq_head *head, |
| 163 | struct cds_wfcq_tail *tail); |
| 164 | |
| 165 | /* |
| 166 | * cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q. |
| 167 | * |
| 168 | * Dequeue all nodes from src_q. |
| 169 | * dest_q must be already initialized. |
| 170 | * Content written into the node before enqueue is guaranteed to be |
| 171 | * consistent, but no other memory ordering is ensured. |
| 172 | * Mutual exlusion with cds_wfcq_dequeue_blocking and dequeue lock is |
| 173 | * ensured. |
| 174 | */ |
| 175 | extern void cds_wfcq_splice_blocking( |
| 176 | struct cds_wfcq_head *dest_q_head, |
| 177 | struct cds_wfcq_tail *dest_q_tail, |
| 178 | struct cds_wfcq_head *src_q_head, |
| 179 | struct cds_wfcq_tail *src_q_tail); |
| 180 | |
| 181 | /* |
| 182 | * __cds_wfcq_dequeue_blocking: |
| 183 | * |
| 184 | * Content written into the node before enqueue is guaranteed to be |
| 185 | * consistent, but no other memory ordering is ensured. |
| 186 | * It is valid to reuse and free a dequeued node immediately. |
| 187 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
| 188 | * caller. |
| 189 | */ |
| 190 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_blocking( |
| 191 | struct cds_wfcq_head *head, |
| 192 | struct cds_wfcq_tail *tail); |
| 193 | |
| 194 | /* |
| 195 | * __cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q. |
| 196 | * |
| 197 | * Dequeue all nodes from src_q. |
| 198 | * dest_q must be already initialized. |
| 199 | * Content written into the node before enqueue is guaranteed to be |
| 200 | * consistent, but no other memory ordering is ensured. |
| 201 | * Dequeue/splice/iteration mutual exclusion for src_q should be ensured |
| 202 | * by the caller. |
| 203 | */ |
| 204 | extern void __cds_wfcq_splice_blocking( |
| 205 | struct cds_wfcq_head *dest_q_head, |
| 206 | struct cds_wfcq_tail *dest_q_tail, |
| 207 | struct cds_wfcq_head *src_q_head, |
| 208 | struct cds_wfcq_tail *src_q_tail); |
| 209 | |
| 210 | /* |
| 211 | * __cds_wfcq_first_blocking: get first node of a queue, without dequeuing. |
| 212 | * |
| 213 | * Content written into the node before enqueue is guaranteed to be |
| 214 | * consistent, but no other memory ordering is ensured. |
| 215 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
| 216 | * caller. |
| 217 | * |
| 218 | * Used by for-like iteration macros: |
| 219 | * __cds_wfcq_for_each_blocking() |
| 220 | * __cds_wfcq_for_each_blocking_safe() |
| 221 | */ |
| 222 | extern struct cds_wfcq_node *__cds_wfcq_first_blocking( |
| 223 | struct cds_wfcq_head *head, |
| 224 | struct cds_wfcq_tail *tail); |
| 225 | |
| 226 | /* |
| 227 | * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing. |
| 228 | * |
| 229 | * Content written into the node before enqueue is guaranteed to be |
| 230 | * consistent, but no other memory ordering is ensured. |
| 231 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
| 232 | * caller. |
| 233 | * |
| 234 | * Used by for-like iteration macros: |
| 235 | * __cds_wfcq_for_each_blocking() |
| 236 | * __cds_wfcq_for_each_blocking_safe() |
| 237 | */ |
| 238 | extern struct cds_wfcq_node *__cds_wfcq_next_blocking( |
| 239 | struct cds_wfcq_head *head, |
| 240 | struct cds_wfcq_tail *tail, |
| 241 | struct cds_wfcq_node *node); |
| 242 | |
| 243 | #endif /* !_LGPL_SOURCE */ |
| 244 | |
| 245 | /* |
| 246 | * __cds_wfcq_for_each_blocking: Iterate over all nodes in a queue, |
| 247 | * without dequeuing them. |
| 248 | * @head: head of the queue (struct cds_wfcq_head pointer). |
| 249 | * @tail: tail of the queue (struct cds_wfcq_tail pointer). |
| 250 | * @node: iterator on the queue (struct cds_wfcq_node pointer). |
| 251 | * |
| 252 | * Content written into each node before enqueue is guaranteed to be |
| 253 | * consistent, but no other memory ordering is ensured. |
| 254 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
| 255 | * caller. |
| 256 | */ |
| 257 | #define __cds_wfcq_for_each_blocking(head, tail, node) \ |
| 258 | for (node = __cds_wfcq_first_blocking(head, tail); \ |
| 259 | node != NULL; \ |
| 260 | node = __cds_wfcq_next_blocking(head, tail, node)) |
| 261 | |
| 262 | /* |
| 263 | * __cds_wfcq_for_each_blocking_safe: Iterate over all nodes in a queue, |
| 264 | * without dequeuing them. Safe against deletion. |
| 265 | * @head: head of the queue (struct cds_wfcq_head pointer). |
| 266 | * @tail: tail of the queue (struct cds_wfcq_tail pointer). |
| 267 | * @node: iterator on the queue (struct cds_wfcq_node pointer). |
| 268 | * @n: struct cds_wfcq_node pointer holding the next pointer (used |
| 269 | * internally). |
| 270 | * |
| 271 | * Content written into each node before enqueue is guaranteed to be |
| 272 | * consistent, but no other memory ordering is ensured. |
| 273 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
| 274 | * caller. |
| 275 | */ |
| 276 | #define __cds_wfcq_for_each_blocking_safe(head, tail, node, n) \ |
| 277 | for (node = __cds_wfcq_first_blocking(head, tail), \ |
| 278 | n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL); \ |
| 279 | node != NULL; \ |
| 280 | node = n, n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL)) |
| 281 | |
| 282 | #ifdef __cplusplus |
| 283 | } |
| 284 | #endif |
| 285 | |
| 286 | #endif /* _URCU_WFCQUEUE_H */ |