Cleanup: enable signed/unsigned compare compiler warning
[urcu.git] / doc / examples / rculfhash / cds_lfht_for_each_entry_duplicate.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 iterate on duplicate keys within a RCU
14 * lock-free hash table. 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 int seqnum; /* Our node sequence number */
32 struct cds_lfht_node node; /* Chaining in hash table */
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 int main(int argc, char **argv)
46 {
47 int values[] = { -5, 42, 42, 36, 24, }; /* 42 is duplicated */
48 int lookup_values[] = { 42, 200, 36, };
49 struct cds_lfht *ht; /* Hash table */
50 unsigned int i;
51 int ret = 0, seqnum = 0;
52 uint32_t seed;
53 struct cds_lfht_iter iter; /* For iteration on hash table */
54 struct mynode *node;
55
56 /*
57 * Each thread need using RCU read-side need to be explicitly
58 * registered.
59 */
60 urcu_memb_register_thread();
61
62 /* Use time as seed for hash table hashing. */
63 seed = (uint32_t) time(NULL);
64
65 /*
66 * Allocate hash table.
67 */
68 ht = cds_lfht_new_flavor(1, 1, 0,
69 CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING,
70 &urcu_memb_flavor, NULL);
71 if (!ht) {
72 printf("Error allocating hash table\n");
73 ret = -1;
74 goto end;
75 }
76
77 /*
78 * Add nodes to hash table.
79 */
80 for (i = 0; i < CAA_ARRAY_SIZE(values); i++) {
81 unsigned long hash;
82 int value;
83
84 node = malloc(sizeof(*node));
85 if (!node) {
86 ret = -1;
87 goto end;
88 }
89
90 cds_lfht_node_init(&node->node);
91 value = values[i];
92 node->value = value;
93 node->seqnum = seqnum++;
94 hash = jhash(&value, sizeof(value), seed);
95
96 /*
97 * cds_lfht_add() needs to be called from RCU read-side
98 * critical section.
99 */
100 urcu_memb_read_lock();
101 cds_lfht_add(ht, hash, &node->node);
102 printf("Add (key: %d, seqnum: %d)\n",
103 node->value, node->seqnum);
104 urcu_memb_read_unlock();
105 }
106
107 /*
108 * Iterate over each hash table node. Those will appear in
109 * random order, depending on the hash seed. Iteration needs to
110 * be performed within RCU read-side critical section.
111 */
112 printf("hash table content (random order):");
113 urcu_memb_read_lock();
114 cds_lfht_for_each_entry(ht, &iter, node, node) {
115 printf(" (key: %d, seqnum: %d)",
116 node->value, node->seqnum);
117 }
118 urcu_memb_read_unlock();
119 printf("\n");
120
121 /*
122 * Lookup queries. Note that which node (seqnum) within
123 * duplicates will be found by lookup is random.
124 */
125 printf("Lookups, with iteration on duplicates:\n");
126 for (i = 0; i < CAA_ARRAY_SIZE(lookup_values); i++) {
127 int value = lookup_values[i];
128 unsigned long hash = jhash(&value, sizeof(value), seed);
129
130 printf("lookup key: %d\n", value);
131 urcu_memb_read_lock();
132 cds_lfht_for_each_entry_duplicate(ht, hash, match,
133 &value, &iter, node, node) {
134 printf(" (key %d, seqnum %d) found\n",
135 node->value, node->seqnum);
136 }
137 urcu_memb_read_unlock();
138 }
139
140 end:
141 urcu_memb_unregister_thread();
142 return ret;
143 }
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