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f7e7a1b8 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 add nodes (allowing duplicate keys) into a | |
14 | * RCU lock-free hash table. | |
15 | * This hash table requires using a RCU scheme. | |
16 | */ | |
17 | ||
18 | #include <stdio.h> | |
19 | #include <stdlib.h> | |
20 | #include <time.h> | |
21 | ||
b9050d91 | 22 | #include <urcu/urcu-memb.h> /* RCU flavor */ |
f7e7a1b8 MD |
23 | #include <urcu/rculfhash.h> /* RCU Lock-free hash table */ |
24 | #include <urcu/compiler.h> /* For CAA_ARRAY_SIZE */ | |
25 | #include "jhash.h" /* Example hash function */ | |
26 | ||
27 | /* | |
28 | * Nodes populated into the hash table. | |
29 | */ | |
30 | struct mynode { | |
31 | int value; /* Node content */ | |
32 | struct cds_lfht_node node; /* Chaining in hash table */ | |
33 | }; | |
34 | ||
70469b43 | 35 | int main(void) |
f7e7a1b8 MD |
36 | { |
37 | int values[] = { -5, 42, 42, 36, 24, }; /* 42 is duplicated */ | |
38 | struct cds_lfht *ht; /* Hash table */ | |
39 | unsigned int i; | |
40 | int ret = 0; | |
41 | uint32_t seed; | |
42 | struct cds_lfht_iter iter; /* For iteration on hash table */ | |
43 | struct mynode *node; | |
44 | ||
45 | /* | |
46 | * Each thread need using RCU read-side need to be explicitly | |
47 | * registered. | |
48 | */ | |
b9050d91 | 49 | urcu_memb_register_thread(); |
f7e7a1b8 MD |
50 | |
51 | /* Use time as seed for hash table hashing. */ | |
52 | seed = (uint32_t) time(NULL); | |
53 | ||
54 | /* | |
55 | * Allocate hash table. | |
56 | */ | |
b9050d91 | 57 | ht = cds_lfht_new_flavor(1, 1, 0, |
f7e7a1b8 | 58 | CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, |
b9050d91 | 59 | &urcu_memb_flavor, NULL); |
f7e7a1b8 MD |
60 | if (!ht) { |
61 | printf("Error allocating hash table\n"); | |
62 | ret = -1; | |
63 | goto end; | |
64 | } | |
65 | ||
66 | /* | |
67 | * Add nodes to hash table. | |
68 | */ | |
69 | for (i = 0; i < CAA_ARRAY_SIZE(values); i++) { | |
70 | unsigned long hash; | |
71 | ||
72 | node = malloc(sizeof(*node)); | |
73 | if (!node) { | |
74 | ret = -1; | |
75 | goto end; | |
76 | } | |
77 | ||
78 | cds_lfht_node_init(&node->node); | |
79 | node->value = values[i]; | |
80 | hash = jhash(&values[i], sizeof(values[i]), seed); | |
81 | ||
82 | /* | |
83 | * cds_lfht_add() needs to be called from RCU read-side | |
84 | * critical section. | |
85 | */ | |
b9050d91 | 86 | urcu_memb_read_lock(); |
f7e7a1b8 | 87 | cds_lfht_add(ht, hash, &node->node); |
b9050d91 | 88 | urcu_memb_read_unlock(); |
f7e7a1b8 MD |
89 | } |
90 | ||
91 | /* | |
92 | * Iterate over each hash table node. Those will appear in | |
93 | * random order, depending on the hash seed. Iteration needs to | |
94 | * be performed within RCU read-side critical section. | |
95 | */ | |
96 | printf("hash table content (random order):"); | |
b9050d91 | 97 | urcu_memb_read_lock(); |
f7e7a1b8 MD |
98 | cds_lfht_for_each_entry(ht, &iter, node, node) { |
99 | printf(" %d", node->value); | |
100 | } | |
b9050d91 | 101 | urcu_memb_read_unlock(); |
f7e7a1b8 MD |
102 | printf("\n"); |
103 | end: | |
b9050d91 | 104 | urcu_memb_unregister_thread(); |
f7e7a1b8 MD |
105 | return ret; |
106 | } |