/*
* Copyright (C) 2006-2009 B.A.T.M.A.N. contributors:
*
* Simon Wunderlich, Marek Lindner
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*
*/
#include "main.h"
#include "hash.h"
/* clears the hash */
void hash_init(struct hashtable_t *hash)
{
int i;
hash->elements = 0;
for (i = 0 ; i < hash->size; i++)
hash->table[i] = NULL;
}
/* remove the hash structure. if hashdata_free_cb != NULL, this function will be
* called to remove the elements inside of the hash. if you don't remove the
* elements, memory might be leaked. */
void hash_delete(struct hashtable_t *hash, hashdata_free_cb free_cb)
{
struct element_t *bucket, *last_bucket;
int i;
for (i = 0; i < hash->size; i++) {
bucket = hash->table[i];
while (bucket != NULL) {
if (free_cb != NULL)
free_cb(bucket->data);
last_bucket = bucket;
bucket = bucket->next;
kfree(last_bucket);
}
}
hash_destroy(hash);
}
/* free only the hashtable and the hash itself. */
void hash_destroy(struct hashtable_t *hash)
{
kfree(hash->table);
kfree(hash);
}
/* iterate though the hash. First element is selected if an iterator
* initialized with HASHIT() is supplied as iter. Use the returned
* (or supplied) iterator to access the elements until hash_iterate returns
* NULL. */
struct hash_it_t *hash_iterate(struct hashtable_t *hash,
struct hash_it_t *iter)
{
if (!hash)
return NULL;
if (!iter)
return NULL;
/* sanity checks first (if our bucket got deleted in the last
* iteration): */
if (iter->bucket != NULL) {
if (iter->first_bucket != NULL) {
/* we're on the first element and it got removed after
* the last iteration. */
if ((*iter->first_bucket) != iter->bucket) {
/* there are still other elements in the list */
if ((*iter->first_bucket) != NULL) {
iter->prev_bucket = NULL;
iter->bucket = (*iter->first_bucket);
iter->first_bucket =
&hash->table[iter->index];
return iter;
} else {
iter->bucket = NULL;
}
}
} else if (iter->prev_bucket != NULL) {
/*
* we're not on the first element, and the bucket got
* removed after the last iteration. the last bucket's
* next pointer is not pointing to our actual bucket
* anymore. select the next.
*/
if (iter->prev_bucket->next != iter->bucket)
iter->bucket = iter->prev_bucket;
}
}
/* now as we are sane, select the next one if there is some */
if (iter->bucket != NULL) {
if (iter->bucket->next != NULL) {
iter->prev_bucket = iter->bucket;
iter->bucket = iter->bucket->next;
iter->first_bucket = NULL;
return iter;
}
}
/* if not returned yet, we've reached the last one on the index and have
* to search forward */
iter->index++;
/* go through the entries of the hash table */
while (iter->index < hash->size) {
if ((hash->table[iter->index]) != NULL) {
iter->prev_bucket = NULL;
iter->bucket = hash->table[iter->index];
iter->first_bucket = &hash->table[iter->index];
return iter;
} else {
iter->index++;
}
}
/* nothing to iterate over anymore */
return NULL;
}
/* allocates and clears the hash */
struct hashtable_t *hash_new(int size, hashdata_compare_cb compare,
hashdata_choose_cb choose)
{
struct hashtable_t *hash;
hash = kmalloc(sizeof(struct hashtable_t) , GFP_ATOMIC);
if (hash == NULL)
return NULL;
hash->size = size;
hash->table = kmalloc(sizeof(struct element_t *) * size, GFP_ATOMIC);
if (hash->table == NULL) {
kfree(hash);
return NULL;
}
hash_init(hash);
hash->compare = compare;
hash->choose = choose;
return hash;
}
/* adds data to the hashtable. returns 0 on success, -1 on error */
int hash_add(struct hashtable_t *hash, void *data)
{
int index;
struct element_t *bucket, *prev_bucket = NULL;
if (!hash)
return -1;
index = hash->choose(data, hash->size);
bucket = hash->table[index];
while (bucket != NULL) {
if (hash->compare(bucket->data, data))
return -1;
prev_bucket = bucket;
bucket = bucket->next;
}
/* found the tail of the list, add new element */
bucket = kmalloc(sizeof(struct element_t), GFP_ATOMIC);
if (bucket == NULL)
return -1;
bucket->data = data;
bucket->next = NULL;
/* and link it */
if (prev_bucket == NULL)
hash->table[index] = bucket;
else
prev_bucket->next = bucket;
hash->elements++;
return 0;
}
/* finds data, based on the key in keydata. returns the found data on success,
* or NULL on error */
void *hash_find(struct hashtable_t *hash, void *keydata)
{
int index;
struct element_t *bucket;
if (!hash)
return NULL;
index = hash->choose(keydata , hash->size);
bucket = hash->table[index];
while (bucket != NULL) {
if (hash->compare(bucket->data, keydata))
return bucket->data;
bucket = bucket->next;
}
return NULL;
}
/* remove bucket (this might be used in hash_iterate() if you already found the
* bucket you want to delete and don't need the overhead to find it again with
* hash_remove(). But usually, you don't want to use this function, as it
* fiddles with hash-internals. */
void *hash_remove_bucket(struct hashtable_t *hash, struct hash_it_t *hash_it_t)
{
void *data_save;
data_save = hash_it_t->bucket->data;
if (hash_it_t->prev_bucket != NULL)
hash_it_t->prev_bucket->next = hash_it_t->bucket->next;
else if (hash_it_t->first_bucket != NULL)
(*hash_it_t->first_bucket) = hash_it_t->bucket->next;
kfree(hash_it_t->bucket);
hash->elements--;
return data_save;
}
/* removes data from hash, if found. returns pointer do data on success, so you
* can remove the used structure yourself, or NULL on error . data could be the
* structure you use with just the key filled, we just need the key for
* comparing. */
void *hash_remove(struct hashtable_t *hash, void *data)
{
struct hash_it_t hash_it_t;
hash_it_t.index = hash->choose(data, hash->size);
hash_it_t.bucket = hash->table[hash_it_t.index];
hash_it_t.prev_bucket = NULL;
while (hash_it_t.bucket != NULL) {
if (hash->compare(hash_it_t.bucket->data, data)) {
hash_it_t.first_bucket =
(hash_it_t.bucket ==
hash->table[hash_it_t.index] ?
&hash->table[hash_it_t.index] : NULL);
return hash_remove_bucket(hash, &hash_it_t);
}
hash_it_t.prev_bucket = hash_it_t.bucket;
hash_it_t.bucket = hash_it_t.bucket->next;
}
return NULL;
}
/* resize the hash, returns the pointer to the new hash or NULL on
* error. removes the old hash on success. */
struct hashtable_t *hash_resize(struct hashtable_t *hash, int size)
{
struct hashtable_t *new_hash;
struct element_t *bucket;
int i;
/* initialize a new hash with the new size */
new_hash = hash_new(size, hash->compare, hash->choose);
if (new_hash == NULL)
return NULL;
/* copy the elements */
for (i = 0; i < hash->size; i++) {
bucket = hash->table[i];
while (bucket != NULL) {
hash_add(new_hash, bucket->data);
bucket = bucket->next;
}
}
/* remove hash and eventual overflow buckets but not the content
* itself. */
hash_delete(hash, NULL);
return new_hash;
}
