Commit | Line | Data |
---|---|---|
d4b71408 MD |
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 dequeue nodes from a RCU lock-free queue. | |
14 | * This queue requires using a RCU scheme. | |
15 | */ | |
16 | ||
17 | #include <stdio.h> | |
18 | #include <stdlib.h> | |
19 | ||
b9050d91 | 20 | #include <urcu/urcu-memb.h> /* RCU flavor */ |
d4b71408 MD |
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 | struct rcu_head rcu_head; /* For call_rcu() */ | |
31 | }; | |
32 | ||
33 | static | |
34 | void free_node(struct rcu_head *head) | |
35 | { | |
36 | struct mynode *node = | |
37 | caa_container_of(head, struct mynode, rcu_head); | |
38 | ||
39 | free(node); | |
40 | } | |
41 | ||
42 | int main(int argc, char **argv) | |
43 | { | |
44 | int values[] = { -5, 42, 36, 24, }; | |
45 | struct cds_lfq_queue_rcu myqueue; /* Queue */ | |
46 | unsigned int i; | |
47 | int ret = 0; | |
48 | ||
49 | /* | |
50 | * Each thread need using RCU read-side need to be explicitly | |
51 | * registered. | |
52 | */ | |
b9050d91 | 53 | urcu_memb_register_thread(); |
d4b71408 | 54 | |
b9050d91 | 55 | cds_lfq_init_rcu(&myqueue, urcu_memb_call_rcu); |
d4b71408 MD |
56 | |
57 | /* | |
58 | * Enqueue nodes. | |
59 | */ | |
60 | for (i = 0; i < CAA_ARRAY_SIZE(values); i++) { | |
61 | struct mynode *node; | |
62 | ||
63 | node = malloc(sizeof(*node)); | |
64 | if (!node) { | |
65 | ret = -1; | |
66 | goto end; | |
67 | } | |
68 | ||
69 | cds_lfq_node_init_rcu(&node->node); | |
70 | node->value = values[i]; | |
71 | /* | |
72 | * Both enqueue and dequeue need to be called within RCU | |
73 | * read-side critical section. | |
74 | */ | |
b9050d91 | 75 | urcu_memb_read_lock(); |
d4b71408 | 76 | cds_lfq_enqueue_rcu(&myqueue, &node->node); |
b9050d91 | 77 | urcu_memb_read_unlock(); |
d4b71408 MD |
78 | } |
79 | ||
80 | /* | |
81 | * Dequeue each node from the queue. Those will be dequeued from | |
82 | * the oldest (first enqueued) to the newest (last enqueued). | |
83 | */ | |
84 | printf("dequeued content:"); | |
85 | for (;;) { | |
86 | struct cds_lfq_node_rcu *qnode; | |
87 | struct mynode *node; | |
88 | ||
89 | /* | |
90 | * Both enqueue and dequeue need to be called within RCU | |
91 | * read-side critical section. | |
92 | */ | |
b9050d91 | 93 | urcu_memb_read_lock(); |
d4b71408 | 94 | qnode = cds_lfq_dequeue_rcu(&myqueue); |
b9050d91 | 95 | urcu_memb_read_unlock(); |
d4b71408 MD |
96 | if (!qnode) { |
97 | break; /* Queue is empty. */ | |
98 | } | |
99 | /* Getting the container structure from the node */ | |
100 | node = caa_container_of(qnode, struct mynode, node); | |
101 | printf(" %d", node->value); | |
b9050d91 | 102 | urcu_memb_call_rcu(&node->rcu_head, free_node); |
d4b71408 MD |
103 | } |
104 | printf("\n"); | |
105 | /* | |
106 | * Release memory used by the queue. | |
107 | */ | |
108 | ret = cds_lfq_destroy_rcu(&myqueue); | |
109 | if (ret) { | |
110 | printf("Error destroying queue (non-empty)\n"); | |
111 | } | |
112 | end: | |
b9050d91 | 113 | urcu_memb_unregister_thread(); |
d4b71408 MD |
114 | return ret; |
115 | } |