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/*
Using tdb as a hash table
Copyright (C) Amitay Isaacs 2015
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 __CTDB_DB_HASH_H__
#define __CTDB_DB_HASH_H__
#include <talloc.h>
#include <tdb.h>
/**
* @file db_hash.h
*
* @brief Use tdb database as a hash table
*
* This uses in-memory tdb databases to create a fixed sized hash table.
*/
/**
* @brief Hash type to indicate the hashing function to use.
*
* DB_HASH_SIMPLE uses default hashing function
* DB_HASH_COMPLEX uses jenkins hashing function
*/
enum db_hash_type {
DB_HASH_SIMPLE,
DB_HASH_COMPLEX,
};
/**
* @brief Parser callback function called when fetching a record
*
* This function is called when fetching a record. This function should
* not modify key and data arguments.
*
* The function should return 0 on success and errno on error.
*/
typedef int (*db_hash_record_parser_fn)(uint8_t *keybuf, size_t keylen,
uint8_t *databuf, size_t datalen,
void *private_data);
/**
* @brief Abstract structure representing tdb hash table
*/
struct db_hash_context;
/**
* @brief Initialize tdb hash table
*
* This returns a new tdb hash table context which is a talloc context. Freeing
* this context will free all the memory associated with the hash table.
*
* @param[in] mem_ctx Talloc memory context
* @param[in] name The name for the hash table
* @param[in] hash_size The size of the hash table
* @param[in] type The type of hashing function to use
* @param[out] result The new db_hash_context structure
* @return 0 on success, errno on failure
*/
int db_hash_init(TALLOC_CTX *mem_ctx, const char *name, int hash_size,
enum db_hash_type type, struct db_hash_context **result);
/**
* @brief Insert a record into the hash table
*
* The key and data can be any binary data. Insert only if the record does not
* exist. If the record already exists, return error.
*
* @param[in] dh The tdb hash table context
* @param[in] keybuf The key buffer
* @param[in] keylen The key length
* @param[in] databuf The data buffer
* @param[in] datalen The data length
* @return 0 on success, errno on failure
*/
int db_hash_insert(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen,
uint8_t *databuf, size_t datalen);
/**
* @brief Add a record into the hash table
*
* The key and data can be any binary data. If the record does not exist,
* insert the record. If the record already exists, replace the record.
*
* @param[in] dh The tdb hash table context
* @param[in] keybuf The key buffer
* @param[in] keylen The key length
* @param[in] databuf The data buffer
* @param[in] datalen The data length
* @return 0 on success, errno on failure
*/
int db_hash_add(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen,
uint8_t *databuf, size_t datalen);
/**
* @brief Delete a record from the hash table
*
* @param[in] dh The tdb hash table context
* @param[in] keybuf The key buffer
* @param[in] keylen The key length
* @return 0 on success, errno on failure
*/
int db_hash_delete(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen);
/**
* @brief Fetch a record from the hash table
*
* The key and data can be any binary data.
*
* @param[in] dh The tdb hash table context
* @param[in] keybuf The key buffer
* @param[in] keylen The key length
* @param[in] parser Function called when the matching record is found
* @param[in] private_data Private data to parser function
* @return 0 on success, errno on failure
*/
int db_hash_fetch(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen,
db_hash_record_parser_fn parser, void *private_data);
/**
* @brief Check if a record exists in the hash table
*
* @param[in] dh The tdb hash table context
* @param[in] keybuf The key buffer
* @param[in] keylen The key length
* @return 0 if the record exists, errno on failure
*/
int db_hash_exists(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen);
/**
* @brief Traverse the database without modification
*
* The parser function should return non-zero value to stop traverse.
*
* @param[in] dh The tdb hash table context
* @param[in] parser Function called for each record
* @param[in] private_data Private data to parser function
* @param[out] count Number of records traversed
* @return 0 on success, errno on failure
*/
int db_hash_traverse(struct db_hash_context *dh,
db_hash_record_parser_fn parser, void *private_data,
int *count);
/**
* @brief Traverse the database for modifications
*
* The parser function should return non-zero value to stop traverse.
*
* @param[in] dh The tdb hash table context
* @param[in] parser Function called for each record
* @param[in] private_data Private data to parser function
* @param[out] count Number of records traversed
* @return 0 on success, errno on failure
*/
int db_hash_traverse_update(struct db_hash_context *dh,
db_hash_record_parser_fn parser,
void *private_data, int *count);
#endif /* __CTDB_DB_HASH_H__ */
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