Cleanup: enable signed/unsigned compare compiler warning
[urcu.git] / doc / examples / rculfhash / cds_lfht_del.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 remove nodes from a RCU lock-free hash table.
14 * This hash table requires using a RCU scheme.
15 */
16
17 #include <stdio.h>
18 #include <stdlib.h>
19 #include <time.h>
20
21 #include <urcu/urcu-memb.h> /* RCU flavor */
22 #include <urcu/rculfhash.h> /* RCU Lock-free hash table */
23 #include <urcu/compiler.h> /* For CAA_ARRAY_SIZE */
24 #include "jhash.h" /* Example hash function */
25
26 /*
27 * Nodes populated into the hash table.
28 */
29 struct mynode {
30 int value; /* Node content */
31 struct cds_lfht_node node; /* Chaining in hash table */
32 struct rcu_head rcu_head; /* For call_rcu() */
33 };
34
35 static
36 int match(struct cds_lfht_node *ht_node, const void *_key)
37 {
38 struct mynode *node =
39 caa_container_of(ht_node, struct mynode, node);
40 const int *key = _key;
41
42 return *key == node->value;
43 }
44
45 static
46 void free_node(struct rcu_head *head)
47 {
48 struct mynode *node = caa_container_of(head, struct mynode, rcu_head);
49
50 free(node);
51 }
52
53 int main(int argc, char **argv)
54 {
55 int values[] = { -5, 42, 42, 36, 24, }; /* 42 is duplicated */
56 int remove_values[] = { 42, 36, 24, 123, };
57 struct cds_lfht *ht; /* Hash table */
58 unsigned int i;
59 int ret = 0;
60 uint32_t seed;
61 struct cds_lfht_iter iter; /* For iteration on hash table */
62 struct cds_lfht_node *ht_node;
63 struct mynode *node;
64
65 /*
66 * Each thread need using RCU read-side need to be explicitly
67 * registered.
68 */
69 urcu_memb_register_thread();
70
71 /* Use time as seed for hash table hashing. */
72 seed = (uint32_t) time(NULL);
73
74 /*
75 * Allocate hash table.
76 */
77 ht = cds_lfht_new_flavor(1, 1, 0,
78 CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING,
79 &urcu_memb_flavor, NULL);
80 if (!ht) {
81 printf("Error allocating hash table\n");
82 ret = -1;
83 goto end;
84 }
85
86 /*
87 * Add nodes to hash table.
88 */
89 for (i = 0; i < CAA_ARRAY_SIZE(values); i++) {
90 unsigned long hash;
91 int value;
92
93 node = malloc(sizeof(*node));
94 if (!node) {
95 ret = -1;
96 goto end;
97 }
98
99 cds_lfht_node_init(&node->node);
100 value = values[i];
101 node->value = value;
102 hash = jhash(&value, sizeof(value), seed);
103
104 /*
105 * cds_lfht_add() needs to be called from RCU read-side
106 * critical section.
107 */
108 urcu_memb_read_lock();
109 cds_lfht_add(ht, hash, &node->node);
110 urcu_memb_read_unlock();
111 }
112
113 /*
114 * Iterate over each hash table node. Those will appear in
115 * random order, depending on the hash seed. Iteration needs to
116 * be performed within RCU read-side critical section.
117 */
118 printf("hash table content (random order):");
119 urcu_memb_read_lock();
120 cds_lfht_for_each_entry(ht, &iter, node, node) {
121 printf(" %d", node->value);
122 }
123 urcu_memb_read_unlock();
124 printf("\n");
125
126 /*
127 * Remove one node for each key, if such a node is present.
128 */
129 printf("removing keys (single key, not duplicates):");
130 for (i = 0; i < CAA_ARRAY_SIZE(remove_values); i++) {
131 unsigned long hash;
132 int value;
133
134 value = remove_values[i];
135 hash = jhash(&value, sizeof(value), seed);
136 printf(" %d", value);
137 urcu_memb_read_lock();
138 cds_lfht_lookup(ht, hash, match, &value, &iter);
139 ht_node = cds_lfht_iter_get_node(&iter);
140 if (ht_node) {
141 ret = cds_lfht_del(ht, ht_node);
142 if (ret) {
143 printf(" (concurrently deleted)");
144 } else {
145 struct mynode *del_node =
146 caa_container_of(ht_node,
147 struct mynode, node);
148 urcu_memb_call_rcu(&del_node->rcu_head, free_node);
149 }
150 } else {
151 printf(" (not found)");
152 }
153 urcu_memb_read_unlock();
154 }
155 printf("\n");
156
157 printf("hash table content (random order):");
158 urcu_memb_read_lock();
159 cds_lfht_for_each_entry(ht, &iter, node, node) {
160 printf(" %d", node->value);
161 }
162 urcu_memb_read_unlock();
163 printf("\n");
164
165 end:
166 urcu_memb_unregister_thread();
167 return ret;
168 }
This page took 0.044675 seconds and 4 git commands to generate.