1 /* hash.c - hash tables for opkg
3 Steven M. Ayer, Jamey Hicks
5 Copyright (C) 2002 Compaq Computer Corporation
7 This program is free software; you can redistribute it and/or
8 modify it under the terms of the GNU General Public License as
9 published by the Free Software Foundation; either version 2, or (at
10 your option) any later version.
12 This program is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 General Public License for more details.
21 #include "hash_table.h"
22 #include "opkg_message.h"
23 #include "libbb/libbb.h"
25 static unsigned long djb2_hash(const unsigned char *str
)
27 unsigned long hash
= 5381;
30 hash
= ((hash
<< 5) + hash
) + c
; /* hash * 33 + c */
34 static int hash_index(hash_table_t
* hash
, const char *key
)
36 return djb2_hash((const unsigned char *)key
) % hash
->n_buckets
;
40 * this is an open table keyed by strings
42 void hash_table_init(const char *name
, hash_table_t
* hash
, int len
)
44 if (hash
->entries
!= NULL
) {
45 opkg_msg(ERROR
, "Internal error: non empty hash table.\n");
49 memset(hash
, 0, sizeof(hash_table_t
));
52 hash
->n_buckets
= len
;
53 hash
->entries
= xcalloc(hash
->n_buckets
, sizeof(hash_entry_t
));
56 void hash_print_stats(hash_table_t
* hash
)
58 printf("hash_table: %s, %d bytes\n"
59 "\tn_buckets=%d, n_elements=%d, n_collisions=%d\n"
60 "\tmax_bucket_len=%d, n_used_buckets=%d, ave_bucket_len=%.2f\n"
61 "\tn_hits=%d, n_misses=%d\n",
63 hash
->n_buckets
* (int)sizeof(hash_entry_t
),
69 (hash
->n_used_buckets
?
70 ((float)hash
->n_elements
) / hash
->n_used_buckets
: 0.0f
),
71 hash
->n_hits
, hash
->n_misses
);
74 void hash_table_deinit(hash_table_t
* hash
)
80 /* free the reminaing entries */
81 for (i
= 0; i
< hash
->n_buckets
; i
++) {
82 hash_entry_t
*hash_entry
= (hash
->entries
+ i
);
83 free(hash_entry
->key
);
84 /* skip the first entry as this is part of the array */
85 hash_entry
= hash_entry
->next
;
87 hash_entry_t
*old
= hash_entry
;
88 hash_entry
= hash_entry
->next
;
100 void *hash_table_get(hash_table_t
* hash
, const char *key
)
102 int ndx
= hash_index(hash
, key
);
103 hash_entry_t
*hash_entry
= hash
->entries
+ ndx
;
105 if (hash_entry
->key
) {
106 if (strcmp(key
, hash_entry
->key
) == 0) {
108 return hash_entry
->data
;
111 hash_entry
= hash_entry
->next
;
117 int hash_table_insert(hash_table_t
* hash
, const char *key
, void *value
)
120 int ndx
= hash_index(hash
, key
);
121 hash_entry_t
*hash_entry
= hash
->entries
+ ndx
;
122 if (hash_entry
->key
) {
123 if (strcmp(hash_entry
->key
, key
) == 0) {
124 /* alread in table, update the value */
125 hash_entry
->data
= value
;
129 * if this is a collision, we have to go to the end of the ll,
130 * then add a new entry
131 * before we can hook up the value
133 while (hash_entry
->next
) {
134 hash_entry
= hash_entry
->next
;
135 if (strcmp(hash_entry
->key
, key
) == 0) {
136 hash_entry
->data
= value
;
141 hash_entry
->next
= xcalloc(1, sizeof(hash_entry_t
));
142 hash_entry
= hash_entry
->next
;
143 hash_entry
->next
= NULL
;
145 hash
->n_collisions
++;
146 if (++bucket_len
> hash
->max_bucket_len
)
147 hash
->max_bucket_len
= bucket_len
;
150 hash
->n_used_buckets
++;
153 hash_entry
->key
= xstrdup(key
);
154 hash_entry
->data
= value
;
159 int hash_table_remove(hash_table_t
* hash
, const char *key
)
161 int ndx
= hash_index(hash
, key
);
162 hash_entry_t
*hash_entry
= hash
->entries
+ ndx
;
163 hash_entry_t
*next_entry
= NULL
, *last_entry
= NULL
;
165 if (hash_entry
->key
) {
166 if (strcmp(key
, hash_entry
->key
) == 0) {
167 free(hash_entry
->key
);
169 last_entry
->next
= hash_entry
->next
;
172 next_entry
= hash_entry
->next
;
174 memmove(hash_entry
, next_entry
,
175 sizeof(hash_entry_t
));
178 memset(hash_entry
, 0,
179 sizeof(hash_entry_t
));
185 last_entry
= hash_entry
;
186 hash_entry
= hash_entry
->next
;
191 void hash_table_foreach(hash_table_t
* hash
,
192 void (*f
) (const char *key
, void *entry
, void *data
),
199 for (i
= 0; i
< hash
->n_buckets
; i
++) {
200 hash_entry_t
*hash_entry
= (hash
->entries
+ i
);
202 if (hash_entry
->key
) {
203 f(hash_entry
->key
, hash_entry
->data
, data
);
205 } while ((hash_entry
= hash_entry
->next
));