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hashtable.c
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hashtable.c
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/*
Copyright (C) 2015 Datto Inc.
This file is part of throughputd.
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License version 2 as published
by the Free Software Foundation.
*/
#include <stdlib.h>
#include <errno.h>
#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include "debug.h"
#include "hashtable.h"
#define HASH_FUNCTION_MULTIPLIER 96
void hashtable_destroy(struct hashtable *ht){
PRINT_DEBUG("freeing buckets");
if(ht->buckets) free(ht->buckets);
}
void hashtable_free(struct hashtable *ht){
PRINT_DEBUG("destroying hashtable variables");
hashtable_destroy(ht);
PRINT_DEBUG("freeing hashtable struct");
free(ht);
}
int hashtable_init(struct hashtable *ht, uint64_t array_size){
int ret;
uint32_t i;
PRINT_DEBUG("allocating %llu buckets", (unsigned long long)array_size);
ht->buckets = malloc(array_size * sizeof(struct list_link));
if(!ht->buckets){
ret = ENOMEM;
PRINT_ERROR(ret, "error allocating hashtable backing array");
goto error;
}
for(i = 0; i < array_size; i++){
list_init(&ht->buckets[i]);
}
ht->array_size = array_size;
ht->current_size = 0;
return 0;
error:
PRINT_ERROR(ret, "error initializing hashtable");
if(ht->buckets) free(ht->buckets);
return ret;
}
int hashtable_alloc(uint64_t array_size, struct hashtable **ht_out){
int ret;
struct hashtable *ht;
PRINT_DEBUG("allocating hashtable struct");
ht = malloc(sizeof(struct hashtable));
if(!ht){
ret = ENOMEM;
PRINT_ERROR(ret, "error allocating hashtable");
goto error;
}
PRINT_DEBUG("initializing hashtable struct");
ret = hashtable_init(ht, array_size);
if(ret) goto error;
*ht_out = ht;
return 0;
error:
PRINT_ERROR(ret, "error allocating and initializing hashtable");
if(ht) free(ht);
*ht_out = NULL;
return ret;
}
static uint32_t __hashtable_hash(struct hashtable *ht, const char *key){
const uint8_t *c;
uint32_t hash = 0;
if(!key) return 0;
for (c = (uint8_t *)key; *c; c++){
hash = hash * HASH_FUNCTION_MULTIPLIER + *c;
}
return hash % ht->array_size;
}
static struct hashtable_link *__hashtable_find(struct hashtable *ht, uint32_t hash, char *key){
struct hashtable_link *cur;
PRINT_DEBUG("searching bucket %d for key %s", hash, key);
list_for_each_entry(cur, &ht->buckets[hash], link){
if(!strcmp(key, cur->key)) return cur;
}
return NULL;
}
struct hashtable_link *hashtable_find(struct hashtable *ht, char *key){
return __hashtable_find(ht, __hashtable_hash(ht, key), key);
}
int hashtable_insert(struct hashtable *ht, char *key, struct hashtable_link *hl){
uint32_t hash = __hashtable_hash(ht, key);
PRINT_DEBUG("searching for existing key");
if(__hashtable_find(ht, hash, key) != NULL) return EEXIST;
PRINT_DEBUG("key doesnt exist; adding element");
hl->key = key;
list_add_head(&hl->link, &ht->buckets[hash]);
ht->current_size++;
return 0;
}
struct hashtable_link *hashtable_delete(struct hashtable *ht, char *key){
struct hashtable_link *cur;
uint32_t hash = __hashtable_hash(ht, key);
struct list_link *prev_link = &ht->buckets[hash];
list_for_each_entry(cur, &ht->buckets[hash], link){
if(!strcmp(key, cur->key)){
list_del_next(prev_link);
ht->current_size--;
return cur;
}
prev_link = prev_link->next;
}
return NULL;
}
int hashtable_for_each_key(struct hashtable *ht, foreach_cb cb, void *data){
int ret;
uint32_t i;
struct hashtable_link *cur, *n;
for(i = 0; i < ht->array_size; i++){
list_for_each_entry_safe(cur, n, &ht->buckets[i], link){
ret = cb(ht, cur, data);
if(ret) return ret;
}
}
return 0;
}
void hashtable_print(struct hashtable *ht){
uint32_t i;
struct hashtable_link *cur;
for(i = 0; i < ht->array_size; i++){
printf("%d: ", i);
list_for_each_entry(cur, &ht->buckets[i], link){
printf("%s -> ", cur->key);
}
printf("\n");
}
}