/*
* Copyright (c) 2009-2012 Petri Lehtinen <petri@digip.org>
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See LICENSE for details.
*/
#include <stdlib.h>
#include <string.h>
#include <jansson_config.h> /* for JSON_INLINE */
#include "jansson_private.h" /* for container_of() */
#include "hashtable.h"
typedef struct hashtable_list list_t;
typedef struct hashtable_pair pair_t;
typedef struct hashtable_bucket bucket_t;
#define list_to_pair(list_) container_of(list_, pair_t, list)
/* From http://www.cse.yorku.ca/~oz/hash.html */
static size_t hash_str(const void *ptr)
{
const char *str = (const char *)ptr;
size_t hash = 5381;
size_t c;
while((c = (size_t)*str))
{
hash = ((hash << 5) + hash) + c;
str++;
}
return hash;
}
static JSON_INLINE void list_init(list_t *list)
{
list->next = list;
list->prev = list;
}
static JSON_INLINE void list_insert(list_t *list, list_t *node)
{
node->next = list;
node->prev = list->prev;
list->prev->next = node;
list->prev = node;
}
static JSON_INLINE void list_remove(list_t *list)
{
list->prev->next = list->next;
list->next->prev = list->prev;
}
static JSON_INLINE int bucket_is_empty(hashtable_t *hashtable, bucket_t *bucket)
{
return bucket->first == &hashtable->list && bucket->first == bucket->last;
}
static void insert_to_bucket(hashtable_t *hashtable, bucket_t *bucket,
list_t *list)
{
if(bucket_is_empty(hashtable, bucket))
{
list_insert(&hashtable->list, list);
bucket->first = bucket->last = list;
}
else
{
list_insert(bucket->first, list);
bucket->first = list;
}
}
static size_t primes[] = {
5, 13, 23, 53, 97, 193, 389, 769, 1543, 3079, 6151, 12289, 24593,
49157, 98317, 196613, 393241, 786433, 1572869, 3145739, 6291469,
12582917, 25165843, 50331653, 100663319, 201326611, 402653189,
805306457, 1610612741
};
static JSON_INLINE size_t num_buckets(hashtable_t *hashtable)
{
return primes[hashtable->num_buckets];
}
static pair_t *hashtable_find_pair(hashtable_t *hashtable, bucket_t *bucket,
const char *key, size_t hash)
{
list_t *list;
pair_t *pair;
if(bucket_is_empty(hashtable, bucket))
return NULL;
list = bucket->first;
while(1)
{
pair = list_to_pair(list);
if(pair->hash == hash && strcmp(pair->key, key) == 0)
return pair;
if(list == bucket->last)
break;
list = list->next;
}
return NULL;
}
/* returns 0 on success, -1 if key was not found */
static int hashtable_do_del(hashtable_t *hashtable,
const char *key, size_t hash)
{
pair_t *pair;
bucket_t *bucket;
size_t index;
index = hash % num_buckets(hashtable);
bucket = &hashtable->buckets[index];
pair = hashtable_find_pair(hashtable, bucket, key, hash);
if(!pair)
return -1;
if(&pair->list == bucket->first && &pair->list == bucket->last)
bucket->first = bucket->last = &hashtable->list;
else if(&pair->list == bucket->first)
bucket->first = pair->list.next;
else if(&pair->list == bucket->last)
bucket->last = pair->list.prev;
list_remove(&pair->list);
json_decref(pair->value);
jsonp_free(pair);
hashtable->size--;
return 0;
}
static void hashtable_do_clear(hashtable_t *hashtable)
{
list_t *list, *next;
pair_t *pair;
for(list = hashtable->list.next; list != &hashtable->list; list = next)
{
next = list->next;
pair = list_to_pair(list);
json_decref(pair->value);
jsonp_free(pair);
}
}
static int hashtable_do_rehash(hashtable_t *hashtable)
{
list_t *list, *next;
pair_t *pair;
size_t i, index, new_size;
jsonp_free(hashtable->buckets);
hashtable->num_buckets++;
new_size = num_buckets(hashtable);
hashtable->buckets = jsonp_malloc(new_size * sizeof(bucket_t));
if(!hashtable->buckets)
return -1;
for(i = 0; i < num_buckets(hashtable); i++)
{
hashtable->buckets[i].first = hashtable->buckets[i].last =
&hashtable->list;
}
list = hashtable->list.next;
list_init(&hashtable->list);
for(; list != &hashtable->list; list = next) {
next = list->next;
pair = list_to_pair(list);
index = pair->hash % new_size;
insert_to_bucket(hashtable, &hashtable->buckets[index], &pair->list);
}
return 0;
}
int hashtable_init(hashtable_t *hashtable)
{
size_t i;
hashtable->size = 0;
hashtable->num_buckets = 0; /* index to primes[] */
hashtable->buckets = jsonp_malloc(num_buckets(hashtable) * sizeof(bucket_t));
if(!hashtable->buckets)
return -1;
list_init(&hashtable->list);
for(i = 0; i < num_buckets(hashtable); i++)
{
hashtable->buckets[i].first = hashtable->buckets[i].last =
&hashtable->list;
}
return 0;
}
void hashtable_close(hashtable_t *hashtable)
{
hashtable_do_clear(hashtable);
jsonp_free(hashtable->buckets);
}
int hashtable_set(hashtable_t *hashtable,
const char *key, size_t serial,
json_t *value)
{
pair_t *pair;
bucket_t *bucket;
size_t hash, index;
/* rehash if the load ratio exceeds 1 */
if(hashtable->size >= num_buckets(hashtable))
if(hashtable_do_rehash(hashtable))
return -1;
hash = hash_str(key);
index = hash % num_buckets(hashtable);
bucket = &hashtable->buckets[index];
pair = hashtable_find_pair(hashtable, bucket, key, hash);
if(pair)
{
json_decref(pair->value);
pair->value = value;
}
else
{
/* offsetof(...) returns the size of pair_t without the last,
flexible member. This way, the correct amount is
allocated. */
pair = jsonp_malloc(offsetof(pair_t, key) + strlen(key) + 1);
if(!pair)
return -1;
pair->hash = hash;
pair->serial = serial;
strcpy(pair->key, key);
pair->value = value;
list_init(&pair->list);
insert_to_bucket(hashtable, bucket, &pair->list);
hashtable->size++;
}
return 0;
}
void *hashtable_get(hashtable_t *hashtable, const char *key)
{
pair_t *pair;
size_t hash;
bucket_t *bucket;
hash = hash_str(key);
bucket = &hashtable->buckets[hash % num_buckets(hashtable)];
pair = hashtable_find_pair(hashtable, bucket, key, hash);
if(!pair)
return NULL;
return pair->value;
}
int hashtable_del(hashtable_t *hashtable, const char *key)
{
size_t hash = hash_str(key);
return hashtable_do_del(hashtable, key, hash);
}
void hashtable_clear(hashtable_t *hashtable)
{
size_t i;
hashtable_do_clear(hashtable);
for(i = 0; i < num_buckets(hashtable); i++)
{
hashtable->buckets[i].first = hashtable->buckets[i].last =
&hashtable->list;
}
list_init(&hashtable->list);
hashtable->size = 0;
}
void *hashtable_iter(hashtable_t *hashtable)
{
return hashtable_iter_next(hashtable, &hashtable->list);
}
void *hashtable_iter_at(hashtable_t *hashtable, const char *key)
{
pair_t *pair;
size_t hash;
bucket_t *bucket;
hash = hash_str(key);
bucket = &hashtable->buckets[hash % num_buckets(hashtable)];
pair = hashtable_find_pair(hashtable, bucket, key, hash);
if(!pair)
return NULL;
return &pair->list;
}
void *hashtable_iter_next(hashtable_t *hashtable, void *iter)
{
list_t *list = (list_t *)iter;
if(list->next == &hashtable->list)
return NULL;
return list->next;
}
void *hashtable_iter_key(void *iter)
{
pair_t *pair = list_to_pair((list_t *)iter);
return pair->key;
}
size_t hashtable_iter_serial(void *iter)
{
pair_t *pair = list_to_pair((list_t *)iter);
return pair->serial;
}
void *hashtable_iter_value(void *iter)
{
pair_t *pair = list_to_pair((list_t *)iter);
return pair->value;
}
void hashtable_iter_set(void *iter, json_t *value)
{
pair_t *pair = list_to_pair((list_t *)iter);
json_decref(pair->value);
pair->value = value;
}
