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 cds_wfq_node {
  44         struct cds_wfq_node *next;
  45 };
  46
  47 struct cds_wfq_queue {
  48         struct cds_wfq_node *head, **tail;
  49         struct cds_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 cds_wfq_node_init               _cds_wfq_node_init
  58 #define cds_wfq_init            _cds_wfq_init
  59 #define cds_wfq_enqueue         _cds_wfq_enqueue
  60 #define __cds_wfq_dequeue_blocking      ___cds_wfq_dequeue_blocking
  61 #define cds_wfq_dequeue_blocking        _cds_wfq_dequeue_blocking
  62
  63 #else /* !_LGPL_SOURCE */
  64
  65 extern void cds_wfq_node_init(struct cds_wfq_node *node);
  66 extern void cds_wfq_init(struct cds_wfq_queue *q);
  67 extern void cds_wfq_enqueue(struct cds_wfq_queue *q, struct cds_wfq_node *node);
  68 /* __cds_wfq_dequeue_blocking: caller ensures mutual exclusion between dequeues */
  69 extern struct cds_wfq_node *__cds_wfq_dequeue_blocking(struct cds_wfq_queue *q);
  70 extern struct cds_wfq_node *cds_wfq_dequeue_blocking(struct cds_wfq_queue *q);
  71
  72 #endif /* !_LGPL_SOURCE */
  73
  74 #ifdef __cplusplus
  75 }
  76 #endif
  77
  78 #endif /* _URCU_WFQUEUE_H */