path: root/src/libmdsserver/hash-table.h

/**
 * mds — A micro-display server
 * Copyright © 2014, 2015, 2016, 2017  Mattias Andrée (maandree@kth.se)
 * 
 * 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/>.
 */
#ifndef MDS_LIBMDSSERVER_HASH_TABLE_H
#define MDS_LIBMDSSERVER_HASH_TABLE_H


#include "table-common.h"



#define HASH_TABLE_T_VERSION 0

/**
 * Hash table entry
 */
typedef struct hash_entry
{
	/**
	 * A key
	 */
	size_t key;

	/**
	 * The value associated with the key
	 */
	size_t value;

	/**
	 * The truncated hash value of the key
	 */
	size_t hash;

	/**
	 * The next entry in the bucket
	 */
	struct hash_entry *next;

} hash_entry_t;


/**
 * Value lookup table based on hash value, that do not support
 */
typedef struct hash_table
{
	/**
	 * The table's capacity, i.e. the number of buckets
	 */
	size_t capacity;

	/**
	 * Entry buckets
	 */
	hash_entry_t **buckets;

	/**
	 * When, in the ratio of entries comparied to the capacity, to grow the table
	 */
	float load_factor;

	/**
	 * When, in the number of entries, to grow the table
	 */
	size_t threshold;

	/**
	 * The number of entries stored in the table
	 */
	size_t size;

	/**
	 * Check whether two values are equal
	 * 
	 * If this function pointer is `NULL`, the identity is used
	 * 
	 * Be aware, this variable cannot be marshalled
	 */
	compare_func *value_comparator;

	/**
	 * Check whether two keys are equal
	 * 
	 * If this function pointer is `NULL`, the identity is used
	 * 
	 * Be aware, this variable cannot be marshalled
	 */
	compare_func *key_comparator;

	/**
	 * Calculate the hash of a key
	 * 
	 * If this function pointer is `NULL`, the identity hash is used
	 * 
	 * Be aware, this variable cannot be marshalled
	 * 
	 * @param   key  The key
	 * @return       The hash of the key
	 */
	hash_func *hasher;

} hash_table_t;



/**
 * 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
 */
__attribute__((nonnull))
int hash_table_create_fine_tuned(hash_table_t *restrict this, size_t initial_capacity, float load_factor);

/**
 * Create a hash table
 * 
 * @param   this:hash_table_t*       Memory slot in which to store the new hash table
 * @param   initial_capacity:size_t  The initial capacity of the table
 * @return  :int                     Non-zero on error, `errno` will have been set accordingly
 */
#define hash_table_create_tuned(this, initial_capacity)\
	hash_table_create_fine_tuned(this, initial_capacity, 0.75f)

/**
 * Create a hash table
 * 
 * @param   this:hash_table_t*  Memory slot in which to store the new hash table
 * @return  :int                Non-zero on error, `errno` will have been set accordingly
 */
#define hash_table_create(this)\
	hash_table_create_tuned(this, 16)

/**
 * 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
 */
__attribute__((nonnull(1)))
void hash_table_destroy(hash_table_t *restrict this, free_func *key_freer, free_func *value_freer);

/**
 * 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
 */
__attribute__((pure, nonnull))
int hash_table_contains_value(const hash_table_t *restrict this, size_t value);

/**
 * Check whether a key is used in the table
 * 
 * @param   this  The hash table
 * @param   key   The key
 * @return        Whether the key is used
 */
__attribute__((pure, nonnull))
int hash_table_contains_key(const hash_table_t *restrict this, size_t key);

/**
 * 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
 */
__attribute__((pure, nonnull))
size_t hash_table_get(const hash_table_t *restrict this, size_t key);

/**
 * Look up an entry in the table
 * 
 * @param   this  The hash table
 * @param   key   The key associated with the value
 * @return        The entry associated with the key, `NULL` if the key was not used
 */
__attribute__((pure, nonnull))
hash_entry_t *hash_table_get_entry(const hash_table_t *restrict this, size_t key);

/**
 * 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.
 */
__attribute__((nonnull))
size_t hash_table_put(hash_table_t *restrict this, size_t key, size_t value);

/**
 * 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
 */
__attribute__((nonnull))
size_t hash_table_remove(hash_table_t *restrict this, size_t key);

/**
 * Remove all entries in the table
 * 
 * @param  this  The hash table
 */
__attribute__((nonnull))
void hash_table_clear(hash_table_t *restrict this);

/**
 * Wrapper for `for` keyword that iterates over entry element in a hash table
 * 
 * @param  this:hash_table_t    The hash table
 * @param  i:size_t             The variable to store the buckey index in at each iteration
 * @param  entry:hash_entry_t*  The variable to store the entry in at each iteration
 */
#define foreach_hash_table_entry(this, i, entry)\
	for (i = 0; i < (this).capacity; i++)\
		for (entry = (this).buckets[i]; entry; entry = entry->next)

/**
 * 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
 */
__attribute__((pure, nonnull))
size_t hash_table_marshal_size(const hash_table_t *restrict this);

/**
 * Marshals a hash table
 * 
 * @param  this  The hash table
 * @param  data  Output buffer for the marshalled data
 */
__attribute__((nonnull))
void hash_table_marshal(const hash_table_t *restrict this, char *restrict data);

/**
 * 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 on error, `errno` will be set accordingly.
 *                    Destroy the table on error.
 */
__attribute__((nonnull(1, 2)))
int hash_table_unmarshal(hash_table_t *restrict this, char *restrict data, remap_func *remapper);


#endif