doc/examples/rculfqueue/cds_lfq_enqueue.c

   1 /*
   2  * Copyright (C) 2013  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
   5  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
   6  *
   7  * Permission is hereby granted to use or copy this program for any
   8  * purpose,  provided the above notices are retained on all copies.
   9  * Permission to modify the code and to distribute modified code is
  10  * granted, provided the above notices are retained, and a notice that
  11  * the code was modified is included with the above copyright notice.
  12  *
  13  * This example shows how to enqueue nodes into a RCU lock-free queue.
  14  * This queue requires using a RCU scheme.
  15  */
  16
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19
  20 #include <urcu/urcu-memb.h>     /* RCU flavor */
  21 #include <urcu/rculfqueue.h>    /* RCU Lock-free queue */
  22 #include <urcu/compiler.h>      /* For CAA_ARRAY_SIZE */
  23
  24 /*
  25  * Nodes populated into the queue.
  26  */
  27 struct mynode {
  28         int value;                      /* Node content */
  29         struct cds_lfq_node_rcu node;   /* Chaining in queue */
  30 };
  31
  32 int main(int argc, char **argv)
  33 {
  34         int values[] = { -5, 42, 36, 24, };
  35         struct cds_lfq_queue_rcu myqueue;       /* Queue */
  36         unsigned int i;
  37         int ret = 0;
  38
  39         /*
  40          * Each thread need using RCU read-side need to be explicitly
  41          * registered.
  42          */
  43         urcu_memb_register_thread();
  44
  45         cds_lfq_init_rcu(&myqueue, urcu_memb_call_rcu);
  46
  47         /*
  48          * Enqueue nodes.
  49          */
  50         for (i = 0; i < CAA_ARRAY_SIZE(values); i++) {
  51                 struct mynode *node;
  52
  53                 node = malloc(sizeof(*node));
  54                 if (!node) {
  55                         ret = -1;
  56                         goto end;
  57                 }
  58
  59                 cds_lfq_node_init_rcu(&node->node);
  60                 node->value = values[i];
  61                 /*
  62                  * Both enqueue and dequeue need to be called within RCU
  63                  * read-side critical section.
  64                  */
  65                 urcu_memb_read_lock();
  66                 cds_lfq_enqueue_rcu(&myqueue, &node->node);
  67                 urcu_memb_read_unlock();
  68         }
  69
  70 end:
  71         urcu_memb_unregister_thread();
  72         return ret;
  73 }