urcu/wfqueue.h

   1 #ifndef _URCU_WFQUEUE_H
   2 #define _URCU_WFQUEUE_H
   3
   4 /*
   5  * wfqueue.h
   6  *
   7  * Userspace RCU library - Queue with Wait-Free Enqueue/Blocking Dequeue
   8  *
   9  * Copyright 2010 - 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 #include <pthread.h>
  27 #include <assert.h>
  28 #include <urcu/compiler.h>
  29
  30 #ifdef __cplusplus
  31 extern "C" {
  32 #endif
  33
  34 /*
  35  * Queue with wait-free enqueue/blocking dequeue.
  36  * This implementation adds a dummy head node when the queue is empty to ensure
  37  * we can always update the queue locklessly.
  38  *
  39  * Inspired from half-wait-free/half-blocking queue implementation done by
  40  * Paul E. McKenney.
  41  */
  42
  43 struct wfq_node {
  44         struct wfq_node *next;
  45 };
  46
  47 struct wfq_queue {
  48         struct wfq_node *head, **tail;
  49         struct wfq_node dummy;  /* Dummy node */
  50         pthread_mutex_t lock;
  51 };
  52
  53 #ifdef _LGPL_SOURCE
  54
  55 #include <urcu/wfqueue-static.h>
  56
  57 #define wfq_node_init           _wfq_node_init
  58 #define wfq_init                _wfq_init
  59 #define wfq_enqueue             _wfq_enqueue
  60 #define wfq_dequeue_blocking    _wfq_dequeue_blocking
  61
  62 #else /* !_LGPL_SOURCE */
  63
  64 extern void wfq_node_init(struct wfq_node *node);
  65 extern void wfq_init(struct wfq_queue *q);
  66 extern void wfq_enqueue(struct wfq_queue *q, struct wfq_node *node);
  67 extern struct wfq_node *wfq_dequeue_blocking(struct wfq_queue *q);
  68
  69 #endif /* !_LGPL_SOURCE */
  70
  71 #ifdef __cplusplus
  72 }
  73 #endif
  74
  75 #endif /* _URCU_WFQUEUE_H */