b6c359767b
instead of dynamically registering hash iterators, calling functions are changed to register the iterator objects statically. The two advantages are: * no memory leaks when aborting from hash_iterate() * no calls to kmalloc/kfree, therefore a little faster/safer Tested with 9 QEMU instances, no obvious regression found. Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de> Signed-off-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
307 lines
7.5 KiB
C
307 lines
7.5 KiB
C
/*
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* Copyright (C) 2006-2009 B.A.T.M.A.N. contributors:
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*
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* Simon Wunderlich, Marek Lindner
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA
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*
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*/
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#include "main.h"
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#include "hash.h"
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/* clears the hash */
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void hash_init(struct hashtable_t *hash)
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{
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int i;
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hash->elements = 0;
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for (i = 0 ; i < hash->size; i++)
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hash->table[i] = NULL;
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}
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/* remove the hash structure. if hashdata_free_cb != NULL, this function will be
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* called to remove the elements inside of the hash. if you don't remove the
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* elements, memory might be leaked. */
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void hash_delete(struct hashtable_t *hash, hashdata_free_cb free_cb)
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{
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struct element_t *bucket, *last_bucket;
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int i;
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for (i = 0; i < hash->size; i++) {
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bucket = hash->table[i];
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while (bucket != NULL) {
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if (free_cb != NULL)
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free_cb(bucket->data);
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last_bucket = bucket;
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bucket = bucket->next;
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kfree(last_bucket);
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}
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}
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hash_destroy(hash);
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}
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/* free only the hashtable and the hash itself. */
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void hash_destroy(struct hashtable_t *hash)
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{
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kfree(hash->table);
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kfree(hash);
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}
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/* iterate though the hash. First element is selected if an iterator
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* initialized with HASHIT() is supplied as iter. Use the returned
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* (or supplied) iterator to access the elements until hash_iterate returns
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* NULL. */
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struct hash_it_t *hash_iterate(struct hashtable_t *hash,
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struct hash_it_t *iter)
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{
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if (!hash)
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return NULL;
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if (!iter)
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return NULL;
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/* sanity checks first (if our bucket got deleted in the last
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* iteration): */
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if (iter->bucket != NULL) {
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if (iter->first_bucket != NULL) {
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/* we're on the first element and it got removed after
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* the last iteration. */
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if ((*iter->first_bucket) != iter->bucket) {
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/* there are still other elements in the list */
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if ((*iter->first_bucket) != NULL) {
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iter->prev_bucket = NULL;
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iter->bucket = (*iter->first_bucket);
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iter->first_bucket =
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&hash->table[iter->index];
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return iter;
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} else {
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iter->bucket = NULL;
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}
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}
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} else if (iter->prev_bucket != NULL) {
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/*
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* we're not on the first element, and the bucket got
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* removed after the last iteration. the last bucket's
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* next pointer is not pointing to our actual bucket
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* anymore. select the next.
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*/
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if (iter->prev_bucket->next != iter->bucket)
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iter->bucket = iter->prev_bucket;
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}
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}
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/* now as we are sane, select the next one if there is some */
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if (iter->bucket != NULL) {
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if (iter->bucket->next != NULL) {
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iter->prev_bucket = iter->bucket;
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iter->bucket = iter->bucket->next;
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iter->first_bucket = NULL;
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return iter;
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}
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}
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/* if not returned yet, we've reached the last one on the index and have
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* to search forward */
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iter->index++;
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/* go through the entries of the hash table */
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while (iter->index < hash->size) {
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if ((hash->table[iter->index]) != NULL) {
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iter->prev_bucket = NULL;
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iter->bucket = hash->table[iter->index];
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iter->first_bucket = &hash->table[iter->index];
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return iter;
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} else {
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iter->index++;
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}
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}
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/* nothing to iterate over anymore */
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return NULL;
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}
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/* allocates and clears the hash */
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struct hashtable_t *hash_new(int size, hashdata_compare_cb compare,
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hashdata_choose_cb choose)
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{
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struct hashtable_t *hash;
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hash = kmalloc(sizeof(struct hashtable_t) , GFP_ATOMIC);
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if (hash == NULL)
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return NULL;
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hash->size = size;
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hash->table = kmalloc(sizeof(struct element_t *) * size, GFP_ATOMIC);
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if (hash->table == NULL) {
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kfree(hash);
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return NULL;
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}
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hash_init(hash);
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hash->compare = compare;
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hash->choose = choose;
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return hash;
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}
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/* adds data to the hashtable. returns 0 on success, -1 on error */
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int hash_add(struct hashtable_t *hash, void *data)
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{
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int index;
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struct element_t *bucket, *prev_bucket = NULL;
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if (!hash)
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return -1;
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index = hash->choose(data, hash->size);
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bucket = hash->table[index];
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while (bucket != NULL) {
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if (hash->compare(bucket->data, data))
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return -1;
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prev_bucket = bucket;
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bucket = bucket->next;
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}
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/* found the tail of the list, add new element */
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bucket = kmalloc(sizeof(struct element_t), GFP_ATOMIC);
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if (bucket == NULL)
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return -1;
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bucket->data = data;
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bucket->next = NULL;
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/* and link it */
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if (prev_bucket == NULL)
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hash->table[index] = bucket;
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else
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prev_bucket->next = bucket;
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hash->elements++;
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return 0;
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}
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/* finds data, based on the key in keydata. returns the found data on success,
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* or NULL on error */
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void *hash_find(struct hashtable_t *hash, void *keydata)
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{
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int index;
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struct element_t *bucket;
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if (!hash)
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return NULL;
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index = hash->choose(keydata , hash->size);
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bucket = hash->table[index];
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while (bucket != NULL) {
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if (hash->compare(bucket->data, keydata))
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return bucket->data;
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bucket = bucket->next;
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}
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return NULL;
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}
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/* remove bucket (this might be used in hash_iterate() if you already found the
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* bucket you want to delete and don't need the overhead to find it again with
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* hash_remove(). But usually, you don't want to use this function, as it
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* fiddles with hash-internals. */
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void *hash_remove_bucket(struct hashtable_t *hash, struct hash_it_t *hash_it_t)
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{
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void *data_save;
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data_save = hash_it_t->bucket->data;
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if (hash_it_t->prev_bucket != NULL)
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hash_it_t->prev_bucket->next = hash_it_t->bucket->next;
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else if (hash_it_t->first_bucket != NULL)
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(*hash_it_t->first_bucket) = hash_it_t->bucket->next;
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kfree(hash_it_t->bucket);
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hash->elements--;
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return data_save;
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}
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/* removes data from hash, if found. returns pointer do data on success, so you
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* can remove the used structure yourself, or NULL on error . data could be the
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* structure you use with just the key filled, we just need the key for
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* comparing. */
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void *hash_remove(struct hashtable_t *hash, void *data)
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{
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struct hash_it_t hash_it_t;
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hash_it_t.index = hash->choose(data, hash->size);
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hash_it_t.bucket = hash->table[hash_it_t.index];
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hash_it_t.prev_bucket = NULL;
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while (hash_it_t.bucket != NULL) {
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if (hash->compare(hash_it_t.bucket->data, data)) {
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hash_it_t.first_bucket =
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(hash_it_t.bucket ==
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hash->table[hash_it_t.index] ?
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&hash->table[hash_it_t.index] : NULL);
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return hash_remove_bucket(hash, &hash_it_t);
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}
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hash_it_t.prev_bucket = hash_it_t.bucket;
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hash_it_t.bucket = hash_it_t.bucket->next;
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}
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return NULL;
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}
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/* resize the hash, returns the pointer to the new hash or NULL on
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* error. removes the old hash on success. */
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struct hashtable_t *hash_resize(struct hashtable_t *hash, int size)
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{
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struct hashtable_t *new_hash;
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struct element_t *bucket;
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int i;
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/* initialize a new hash with the new size */
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new_hash = hash_new(size, hash->compare, hash->choose);
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if (new_hash == NULL)
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return NULL;
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/* copy the elements */
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for (i = 0; i < hash->size; i++) {
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bucket = hash->table[i];
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while (bucket != NULL) {
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hash_add(new_hash, bucket->data);
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bucket = bucket->next;
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}
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}
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/* remove hash and eventual overflow buckets but not the content
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* itself. */
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hash_delete(hash, NULL);
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return new_hash;
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}
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