/**
* mds — A micro-display server
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* 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 3 of the License, 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "hash-table.h"
#include <stdlib.h>
#include <errno.h>
/**
* Test if a key matches the key in a bucket
*
* @param T The instance of the hash table
* @param B The bucket
* @param K The key
* @param H The hash of the key
*/
#define TEST_KEY(T, B, K, H) \
((B->key == K) || (T->key_comparator && (B->hash == H) && T->key_comparator(B->key, K)))
/**
* Calculate the hash of a key
*
* @param this The hash table
* @param key The key to hash
* @return The hash of the key
*/
static inline size_t __attribute__((const)) hash(const hash_table_t* restrict this, size_t key)
{
return this->hasher ? this->hasher(key) : key;
}
/**
* Truncates the hash of a key to constrain it to the buckets
*
* @param this The hash table
* @param key The key to hash
* @return A non-negative value less the the table's capacity
*/
static inline size_t __attribute__((pure)) truncate_hash(const hash_table_t* restrict this, size_t hash)
{
return hash % this->capacity;
}
/**
* Grow the table
*
* @param this The hash table
* @return Non zero on error, errno will be set accordingly
*/
static int rehash(hash_table_t* restrict this)
{
hash_entry_t** old_buckets = this->buckets;
size_t old_capacity = this->capacity;
size_t i = old_capacity, index;
hash_entry_t* bucket;
hash_entry_t* destination;
hash_entry_t* next;
this->buckets = calloc((old_capacity * 2 + 1), sizeof(hash_entry_t*));
if (this->buckets == NULL)
return -1;
this->capacity = old_capacity * 2 + 1;
this->threshold = (size_t)((float)(this->capacity) * this->load_factor);
while (i)
{
bucket = this->buckets[--i];
while (bucket)
{
index = truncate_hash(this, bucket->hash);
if ((destination = this->buckets[index]))
{
next = destination->next;
while (next)
{
destination = next;
next = destination->next;
}
destination->next = bucket;
}
else
this->buckets[index] = bucket;
next = bucket->next;
bucket->next = NULL;
bucket = next;
}
}
free(old_buckets);
return 0;
}
/**
* Create a hash table
*
* @param this Memory slot in which to store the new hash table
* @param initial_capacity The initial capacity of the table
* @param load_factor The load factor of the table, i.e. when to grow the table
* @return Non-zero on error, `errno` will have been set accordingly
*/
int hash_table_create_fine_tuned(hash_table_t* restrict this, size_t initial_capacity, float load_factor)
{
this->buckets = NULL;
this->capacity = initial_capacity ? initial_capacity : 1;
this->buckets = calloc(this->capacity, sizeof(hash_entry_t*));
if (this->buckets == NULL)
return -1;
this->load_factor = load_factor;
this->threshold = (size_t)((float)(this->capacity) * load_factor);
this->size = 0;
this->value_comparator = NULL;
this->key_comparator = NULL;
this->hasher = NULL;
return 0;
}
/**
* Release all resources in a hash table, should
* be done even if construction fails
*
* @param this The hash table
* @param keys_freer Function that frees a key, `NULL` if keys should not be freed
* @param values_freer Function that frees a value, `NULL` if value should not be freed
*/
void hash_table_destroy(hash_table_t* restrict this, free_func* key_freer, free_func* value_freer)
{
size_t i = this->capacity;
hash_entry_t* bucket;
hash_entry_t* last;
if (this->buckets != NULL)
{
while (i)
{
bucket = this->buckets[--i];
while (bucket)
{
if (key_freer != NULL)
key_freer(bucket->key);
if (value_freer != NULL)
value_freer(bucket->value);
bucket = (last = bucket)->next;
free(last);
}
}
free(this->buckets);
}
}
/**
* Check whether a value is stored in the table
*
* @param this The hash table
* @param value The value
* @return Whether the value is stored in the table
*/
int hash_table_contains_value(const hash_table_t* restrict this, size_t value)
{
size_t i = this->capacity;
hash_entry_t* restrict bucket;
while (i)
{
bucket = this->buckets[--i];
while (bucket != NULL)
{
if (bucket->value == value)
return 1;
if (this->value_comparator && this->value_comparator(bucket->value, value))
return 1;
bucket = bucket->next;
}
}
return 0;
}
/**
* Check whether a key is used in the table
*
* @param this The hash table
* @param key The key
* @return Whether the key is used
*/
int hash_table_contains_key(const hash_table_t* restrict this, size_t key)
{
size_t key_hash = hash(this, key);
size_t index = truncate_hash(this, key_hash);
hash_entry_t* restrict bucket = this->buckets[index];
while (bucket)
{
if (TEST_KEY(this, bucket, key, key_hash))
return 1;
bucket = bucket->next;
}
return 0;
}
/**
* Look up a value in the table
*
* @param this The hash table
* @param key The key associated with the value
* @return The value associated with the key, 0 if the key was not used
*/
size_t hash_table_get(const hash_table_t* restrict this, size_t key)
{
size_t key_hash = hash(this, key);
size_t index = truncate_hash(this, key_hash);
hash_entry_t* restrict bucket = this->buckets[index];
while (bucket)
{
if (TEST_KEY(this, bucket, key, key_hash))
return bucket->value;
bucket = bucket->next;
}
return 0;
}
/**
* Add an entry to the table
*
* @param this The hash table
* @param key The key of the entry to add
* @param value The value of the entry to add
* @return The previous value associated with the key, 0 if the key was not used.
* 0 will also be returned on error, check the `errno` variable.
*/
size_t hash_table_put(hash_table_t* restrict this, size_t key, size_t value)
{
size_t key_hash = hash(this, key);
size_t index = truncate_hash(this, key_hash);
hash_entry_t* restrict bucket = this->buckets[index];
size_t rc;
while (bucket)
if (TEST_KEY(this, bucket, key, key_hash))
{
rc = bucket->value;
bucket->value = value;
return rc;
}
else
bucket = bucket->next;
if (++(this->size) > this->threshold)
{
errno = 0;
if (rehash(this))
return 0;
index = truncate_hash(this, key_hash);
}
errno = 0;
bucket = malloc(sizeof(hash_entry_t));
if (bucket == NULL)
return 0;
bucket->value = value;
bucket->key = key;
bucket->hash = key_hash;
bucket->next = this->buckets[index];
this->buckets[index] = bucket;
return 0;
}
/**
* Remove an entry in the table
*
* @param this The hash table
* @param key The key of the entry to remove
* @return The previous value associated with the key, 0 if the key was not used
*/
size_t hash_table_remove(hash_table_t* restrict this, size_t key)
{
size_t key_hash = hash(this, key);
size_t index = truncate_hash(this, key_hash);
hash_entry_t* bucket = this->buckets[index];
hash_entry_t* last = NULL;
size_t rc;
while (bucket)
{
if (TEST_KEY(this, bucket, key, key_hash))
{
if (last == NULL)
this->buckets[index] = bucket->next;
else
last->next = bucket->next;
this->size--;
rc = bucket->value;
free(bucket);
return rc;
}
last = bucket;
bucket = bucket->next;
}
return 0;
}
/**
* Remove all entries in the table
*
* @param this The hash table
*/
void hash_table_clear(hash_table_t* restrict this)
{
hash_entry_t** buf;
hash_entry_t* bucket;
size_t i, ptr;
if (this->size)
{
buf = alloca((this->size + 1) * sizeof(hash_entry_t*));
i = this->capacity;
while (i)
{
bucket = this->buckets[--i];
ptr = 0;
buf[ptr++] = bucket;
while (bucket)
{
bucket = bucket->next;
buf[ptr++] = bucket;
}
while (ptr)
free(buf[--ptr]);
this->buckets[i] = NULL;
}
this->size = 0;
}
}
/**
* Calculate the buffer size need to marshal a hash table
*
* @param this The hash table
* @return The number of bytes to allocate to the output buffer
*/
size_t hash_table_marshal_size(const hash_table_t* restrict this)
{
size_t n = this->capacity;
size_t rc = 3 * sizeof(size_t) + sizeof(float) + n * sizeof(size_t);
size_t i, m = 0;
for (i = 0; i < n; i++)
{
hash_entry_t* restrict bucket = this->buckets[i];
while (bucket != NULL)
{
bucket = bucket->next;
m++;
}
}
return rc + m * 3 * sizeof(size_t);
}
/**
* Marshals a hash table
*
* @param this The hash table
* @param data Output buffer for the marshalled data
*/
void hash_table_marshal(const hash_table_t* restrict this, char* restrict data)
{
size_t i, n = this->capacity;
((size_t*)data)[0] = this->capacity;
data += 1 * sizeof(size_t) / sizeof(char);
((float*)data)[0] = this->load_factor;
data += 1 * sizeof(float) / sizeof(char);
((size_t*)data)[0] = this->threshold;
((size_t*)data)[1] = this->size;
data += 2 * sizeof(size_t) / sizeof(char);
for (i = 0; i < n; i++)
{
hash_entry_t* restrict bucket = this->buckets[i];
size_t m = 0;
while (bucket != NULL)
{
((size_t*)data)[1 + m * 3 + 0] = bucket->key;
((size_t*)data)[1 + m * 3 + 1] = bucket->value;
((size_t*)data)[1 + m * 3 + 2] = bucket->hash;
bucket = bucket->next;
m++;
}
((size_t*)data)[0] = m;
data += (1 + m * 3) * sizeof(size_t) / sizeof(char);
}
}
/**
* Unmarshals a hash table
*
* @param this Memory slot in which to store the new hash table
* @param data In buffer with the marshalled data
* @param remapper Function that translates values, `NULL` if not translation takes place
* @return Non-zero one error, errno will be set accordingly.
* Destroy the table on error.
*/
int hash_table_unmarshal(hash_table_t* restrict this, char* restrict data, remap_func* remapper)
{
size_t i, n;
this->value_comparator = NULL;
this->key_comparator = NULL;
this->hasher = NULL;
this->capacity = n = ((size_t*)data)[0];
data += 1 * sizeof(size_t) / sizeof(char);
this->load_factor = ((float*)data)[0];
data += 1 * sizeof(float) / sizeof(char);
this->threshold = ((size_t*)data)[0];
this->size = ((size_t*)data)[1];
data += 2 * sizeof(size_t) / sizeof(char);
this->buckets = calloc(this->capacity, sizeof(hash_entry_t*));
if (this->buckets == NULL)
return -1;
for (i = 0; i < n; i++)
{
size_t m = ((size_t*)data)[0];
hash_entry_t* restrict bucket;
data += 1 * sizeof(size_t) / sizeof(char);
this->buckets[i] = bucket = malloc(sizeof(hash_entry_t));
if (bucket == NULL)
return -1;
while (m--)
{
if (m == 0)
bucket->next = NULL;
else
{
bucket->next = malloc(sizeof(hash_entry_t));
if (bucket->next == NULL)
return -1;
}
bucket->key = ((size_t*)data)[0];
bucket->value = ((size_t*)data)[1];
if (remapper != NULL)
bucket->value = remapper(bucket->value);
bucket->hash = ((size_t*)data)[2];
data += 3 * sizeof(size_t) / sizeof(char);
}
}
return 0;
}
