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"
27 djb2_hash(const unsigned char *str
)
29 unsigned long hash
= 5381;
32 hash
= ((hash
<< 5) + hash
) + c
; /* hash * 33 + c */
37 hash_index(hash_table_t
*hash
, const char *key
)
39 return djb2_hash((const unsigned char *)key
) % hash
->n_buckets
;
43 * this is an open table keyed by strings
46 hash_table_init(const char *name
, hash_table_t
*hash
, int len
)
48 if (hash
->entries
!= NULL
) {
49 opkg_msg(ERROR
, "Internal error: non empty hash table.\n");
53 memset(hash
, 0, sizeof(hash_table_t
));
56 hash
->n_buckets
= len
;
57 hash
->entries
= xcalloc(hash
->n_buckets
, sizeof(hash_entry_t
));
61 hash_print_stats(hash_table_t
*hash
)
63 printf("hash_table: %s, %d bytes\n"
64 "\tn_buckets=%d, n_elements=%d, n_collisions=%d\n"
65 "\tmax_bucket_len=%d, n_used_buckets=%d, ave_bucket_len=%.2f\n"
66 "\tn_hits=%d, n_misses=%d\n",
68 hash
->n_buckets
*(int)sizeof(hash_entry_t
),
74 (hash
->n_used_buckets
?
75 ((float)hash
->n_elements
)/hash
->n_used_buckets
: 0.0f
),
80 void hash_table_deinit(hash_table_t
*hash
)
86 /* free the reminaing entries */
87 for (i
= 0; i
< hash
->n_buckets
; i
++) {
88 hash_entry_t
*hash_entry
= (hash
->entries
+ i
);
89 free (hash_entry
->key
);
90 /* skip the first entry as this is part of the array */
91 hash_entry
= hash_entry
->next
;
94 hash_entry_t
*old
= hash_entry
;
95 hash_entry
= hash_entry
->next
;
101 free (hash
->entries
);
103 hash
->entries
= NULL
;
107 void *hash_table_get(hash_table_t
*hash
, const char *key
)
109 int ndx
= hash_index(hash
, key
);
110 hash_entry_t
*hash_entry
= hash
->entries
+ ndx
;
115 if (strcmp(key
, hash_entry
->key
) == 0) {
117 return hash_entry
->data
;
120 hash_entry
= hash_entry
->next
;
126 int hash_table_insert(hash_table_t
*hash
, const char *key
, void *value
)
129 int ndx
= hash_index(hash
, key
);
130 hash_entry_t
*hash_entry
= hash
->entries
+ ndx
;
131 if (hash_entry
->key
) {
132 if (strcmp(hash_entry
->key
, key
) == 0) {
133 /* alread in table, update the value */
134 hash_entry
->data
= value
;
138 * if this is a collision, we have to go to the end of the ll,
139 * then add a new entry
140 * before we can hook up the value
142 while (hash_entry
->next
) {
143 hash_entry
= hash_entry
->next
;
144 if (strcmp(hash_entry
->key
, key
) == 0) {
145 hash_entry
->data
= value
;
150 hash_entry
->next
= xcalloc(1, sizeof(hash_entry_t
));
151 hash_entry
= hash_entry
->next
;
152 hash_entry
->next
= NULL
;
154 hash
->n_collisions
++;
155 if (++bucket_len
> hash
->max_bucket_len
)
156 hash
->max_bucket_len
= bucket_len
;
159 hash
->n_used_buckets
++;
162 hash_entry
->key
= xstrdup(key
);
163 hash_entry
->data
= value
;
168 int hash_table_remove(hash_table_t
*hash
, const char *key
)
170 int ndx
= hash_index(hash
, key
);
171 hash_entry_t
*hash_entry
= hash
->entries
+ ndx
;
172 hash_entry_t
*next_entry
=NULL
, *last_entry
=NULL
;
177 if (strcmp(key
, hash_entry
->key
) == 0) {
178 free(hash_entry
->key
);
180 last_entry
->next
= hash_entry
->next
;
183 next_entry
= hash_entry
->next
;
185 memmove(hash_entry
, next_entry
, sizeof(hash_entry_t
));
188 memset(hash_entry
, 0 , sizeof(hash_entry_t
));
194 last_entry
= hash_entry
;
195 hash_entry
= hash_entry
->next
;
200 void hash_table_foreach(hash_table_t
*hash
, void (*f
)(const char *key
, void *entry
, void *data
), void *data
)
206 for (i
= 0; i
< hash
->n_buckets
; i
++) {
207 hash_entry_t
*hash_entry
= (hash
->entries
+ i
);
209 if(hash_entry
->key
) {
210 f(hash_entry
->key
, hash_entry
->data
, data
);
212 } while((hash_entry
= hash_entry
->next
));