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474190bf 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 do a non-circular RCU linked list | |
14 | * traversal, safely against concurrent RCU updates. | |
15 | */ | |
16 | ||
17 | #include <stdio.h> | |
18 | ||
b9050d91 | 19 | #include <urcu/urcu-memb.h> /* Userspace RCU flavor */ |
474190bf MD |
20 | #include <urcu/rcuhlist.h> /* RCU hlist */ |
21 | #include <urcu/compiler.h> /* For CAA_ARRAY_SIZE */ | |
22 | ||
23 | /* | |
24 | * Nodes populated into the list. | |
25 | */ | |
26 | struct mynode { | |
27 | int value; /* Node content */ | |
28 | struct cds_hlist_node node; /* Linked-list chaining */ | |
29 | }; | |
30 | ||
31 | int main(int argc, char **argv) | |
32 | { | |
33 | int values[] = { -5, 42, 36, 24, }; | |
34 | CDS_HLIST_HEAD(mylist); /* Defines an empty hlist head */ | |
35 | unsigned int i; | |
36 | int ret = 0; | |
37 | struct mynode *node; | |
38 | ||
39 | /* | |
40 | * Each thread need using RCU read-side need to be explicitly | |
41 | * registered. | |
42 | */ | |
b9050d91 | 43 | urcu_memb_register_thread(); |
474190bf MD |
44 | |
45 | /* | |
46 | * Adding nodes to the linked-list. Safe against concurrent | |
47 | * RCU traversals, require mutual exclusion with list updates. | |
48 | */ | |
49 | for (i = 0; i < CAA_ARRAY_SIZE(values); i++) { | |
50 | node = malloc(sizeof(*node)); | |
51 | if (!node) { | |
52 | ret = -1; | |
53 | goto end; | |
54 | } | |
55 | node->value = values[i]; | |
56 | cds_hlist_add_head_rcu(&node->node, &mylist); | |
57 | } | |
58 | ||
59 | /* | |
60 | * RCU-safe iteration on the list. | |
61 | */ | |
62 | printf("mylist content:"); | |
63 | ||
64 | /* | |
65 | * Surround the RCU read-side critical section with rcu_read_lock() | |
66 | * and rcu_read_unlock(). | |
67 | */ | |
b9050d91 | 68 | urcu_memb_read_lock(); |
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69 | |
70 | /* | |
71 | * This traversal can be performed concurrently with RCU | |
72 | * updates. | |
73 | */ | |
74 | cds_hlist_for_each_entry_rcu_2(node, &mylist, node) { | |
75 | printf(" %d", node->value); | |
76 | } | |
77 | ||
b9050d91 | 78 | urcu_memb_read_unlock(); |
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79 | |
80 | printf("\n"); | |
81 | end: | |
b9050d91 | 82 | urcu_memb_unregister_thread(); |
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83 | return ret; |
84 | } |