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/* hash.c - hash tables for opkg
Steven M. Ayer, Jamey Hicks
Copyright (C) 2002 Compaq Computer Corporation
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "hash_table.h"
#include "opkg_message.h"
#include "libbb/libbb.h"
static unsigned long
djb2_hash(const unsigned char *str)
{
unsigned long hash = 5381;
int c;
while ((c = *str++))
hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
return hash;
}
static int
hash_index(hash_table_t *hash, const char *key)
{
return djb2_hash((const unsigned char *)key) % hash->n_buckets;
}
/*
* this is an open table keyed by strings
*/
void
hash_table_init(const char *name, hash_table_t *hash, int len)
{
if (hash->entries != NULL) {
opkg_msg(ERROR, "Internal error: non empty hash table.\n");
return;
}
memset(hash, 0, sizeof(hash_table_t));
hash->name = name;
hash->n_buckets = len;
hash->entries = xcalloc(hash->n_buckets, sizeof(hash_entry_t));
}
void
hash_print_stats(hash_table_t *hash)
{
printf("hash_table: %s, %d bytes\n"
"\tn_buckets=%d, n_elements=%d, n_collisions=%d\n"
"\tmax_bucket_len=%d, n_used_buckets=%d, ave_bucket_len=%.2f\n"
"\tn_hits=%d, n_misses=%d\n",
hash->name,
hash->n_buckets*(int)sizeof(hash_entry_t),
hash->n_buckets,
hash->n_elements,
hash->n_collisions,
hash->max_bucket_len,
hash->n_used_buckets,
(hash->n_used_buckets ?
((float)hash->n_elements)/hash->n_used_buckets : 0.0f),
hash->n_hits,
hash->n_misses);
}
void hash_table_deinit(hash_table_t *hash)
{
int i;
if (!hash)
return;
/* free the reminaing entries */
for (i = 0; i < hash->n_buckets; i++) {
hash_entry_t *hash_entry = (hash->entries + i);
free (hash_entry->key);
/* skip the first entry as this is part of the array */
hash_entry = hash_entry->next;
while (hash_entry)
{
hash_entry_t *old = hash_entry;
hash_entry = hash_entry->next;
free (old->key);
free (old);
}
}
free (hash->entries);
hash->entries = NULL;
hash->n_buckets = 0;
}
void *hash_table_get(hash_table_t *hash, const char *key)
{
int ndx= hash_index(hash, key);
hash_entry_t *hash_entry = hash->entries + ndx;
while (hash_entry)
{
if (hash_entry->key)
{
if (strcmp(key, hash_entry->key) == 0) {
hash->n_hits++;
return hash_entry->data;
}
}
hash_entry = hash_entry->next;
}
hash->n_misses++;
return NULL;
}
int hash_table_insert(hash_table_t *hash, const char *key, void *value)
{
int bucket_len = 0;
int ndx= hash_index(hash, key);
hash_entry_t *hash_entry = hash->entries + ndx;
if (hash_entry->key) {
if (strcmp(hash_entry->key, key) == 0) {
/* alread in table, update the value */
hash_entry->data = value;
return 0;
} else {
/*
* if this is a collision, we have to go to the end of the ll,
* then add a new entry
* before we can hook up the value
*/
while (hash_entry->next) {
hash_entry = hash_entry->next;
if (strcmp(hash_entry->key, key) == 0) {
hash_entry->data = value;
return 0;
}
bucket_len++;
}
hash_entry->next = xcalloc(1, sizeof(hash_entry_t));
hash_entry = hash_entry->next;
hash_entry->next = NULL;
hash->n_collisions++;
if (++bucket_len > hash->max_bucket_len)
hash->max_bucket_len = bucket_len;
}
} else
hash->n_used_buckets++;
hash->n_elements++;
hash_entry->key = xstrdup(key);
hash_entry->data = value;
return 0;
}
int hash_table_remove(hash_table_t *hash, const char *key)
{
int ndx= hash_index(hash, key);
hash_entry_t *hash_entry = hash->entries + ndx;
hash_entry_t *next_entry=NULL, *last_entry=NULL;
while (hash_entry)
{
if (hash_entry->key)
{
if (strcmp(key, hash_entry->key) == 0) {
free(hash_entry->key);
if (last_entry) {
last_entry->next = hash_entry->next;
free(hash_entry);
} else {
next_entry = hash_entry->next;
if (next_entry) {
memmove(hash_entry, next_entry, sizeof(hash_entry_t));
free(next_entry);
} else {
memset(hash_entry, 0 , sizeof(hash_entry_t));
}
}
return 1;
}
}
last_entry = hash_entry;
hash_entry = hash_entry->next;
}
return 0;
}
void hash_table_foreach(hash_table_t *hash, void (*f)(const char *key, void *entry, void *data), void *data)
{
int i;
if (!hash || !f)
return;
for (i = 0; i < hash->n_buckets; i++) {
hash_entry_t *hash_entry = (hash->entries + i);
do {
if(hash_entry->key) {
f(hash_entry->key, hash_entry->data, data);
}
} while((hash_entry = hash_entry->next));
}
}
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