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/* Copyright (C) 2013 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
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/>.
*/
/*!
* \file hhash.h
*
* \author Marek Vavrusa <marek.vavrusa@nic.cz>
*
* \brief Hopscotch hashing scheme based hash table.
*
* \addtogroup common_lib
* @{
*/
#ifndef _KNOTD_HHTABLE_H_
#define _KNOTD_HHTABLE_H_
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include "common/mempattern.h"
/*! \brief Bitvector type. */
typedef unsigned hhbitvec_t;
/*! \brief Element value. */
typedef void* value_t;
/*! \brief Mode flags. */
enum {
HHASH_INSERT = 1 << 0, /* Insert if not exists. */
HHASH_FORCE = 1 << 1, /* Force vacate a hash bucket. */
HHASH_LEFT = 1 << 2, /* Split left side. */
HHASH_RIGHT = 1 << 3, /* Split right side. */
HHASH_CONSUME = 1 << 4 /* Consume first byte of the split items. */
};
/*! \brief Element descriptor, contains data and bitmap of adjacent items. */
typedef struct hhelem {
hhbitvec_t hop; /* Hop bitvector. */
char *d; /* { value_t val, uint16_t keylen, char[] key } */
} hhelem_t;
typedef struct hhash {
/* Compatibility with HAT-trie nodes. */
uint8_t flag;
uint8_t c0;
uint8_t c1;
/* Metadata */
uint32_t size; /*!< Number of buckets */
uint32_t weight; /*!< Table weight (number of inserted). */
/* Table data storage. */
mm_ctx_t mm; /*!< Memory manager. */
uint32_t *index; /*!< Order index (optional). */
hhelem_t item[]; /*!< Table items. */
} hhash_t;
/*!
* \brief Create hopscotch hash table.
*
* \param size Fixed size.
*
* \return created table
*/
hhash_t *hhash_create(uint32_t size);
/*! \brief Create hopscotch hash table (custom memory manager). */
hhash_t *hhash_create_mm(uint32_t size, const mm_ctx_t *mm);
/*!
* \brief Clear hash table.
*
* \param tbl Hash table.
*/
void hhash_clear(hhash_t *tbl);
/*!
* \brief Free hash table and keys.
*
* \param tbl Hash table.
*/
void hhash_free(hhash_t *tbl);
/*!
* \brief Find key in the hash table and return pointer to it's value.
*
* \param tbl Hash table.
* \param key Key.
* \param len Key length.
*
* \retval pointer to value if found
* \retval NULL if not exists
*/
value_t *hhash_find(hhash_t* tbl, const char* key, uint16_t len);
/*!
* \brief Insert/replace value for given key.
*
* \param tbl Hash table.
* \param key Key.
* \param len Key length.
* \param val Value.
*
* \retval KNOT_EOK
* \retval KNOT_ESPACE
*/
int hhash_insert(hhash_t* tbl, const char* key, uint16_t len, value_t val);
/*!
* \brief Return pointer to value for given key (insert if not exists).
*
* \note This is more complex function than \fn hhash_insert() which is preferred
* for easier usage.
*
* \param tbl Hash table.
* \param key Key.
* \param len Key length.
* \param mode Operation mode flags.
*
* \retval pointer to new/existing value
* \retval NULL if the table is full or no memory
*/
value_t *hhash_map(hhash_t* tbl, const char* key, uint16_t len, uint16_t mode);
/*!
* \brief Remove value from hash table.
*
* \param tbl Hash table.
* \param key Key.
* \param len Key length.
*
* \retval KNOT_EOK
* \retval KNOT_ENOENT
*/
int hhash_del(hhash_t* tbl, const char* key, uint16_t len);
/*
* Hash table allows to build order index for extra memory costs.
* This is not required, but useful if the table is small and insertions
* don't happen very often.
* Keep in mind to rebuild index after the insertions/deletes are complete
*/
/*! \brief Return value from ordered index. */
value_t *hhash_indexval(hhash_t* tbl, unsigned i);
/*! \brief Build index for fast ordered lookup. */
void hhash_build_index(hhash_t* tbl);
/*!
* \brief Find a key that is exact match or lexicographic predecessor.
*
* \retval 0 if exact match
* \retval 1 if couldn't find and no predecessor is found
* \retval -1 if found predecessor
*/
int hhash_find_leq(hhash_t* tbl, const char* key, uint16_t len, value_t **dst);
/*! \brief Hash table iterator. */
typedef struct htable_iter {
unsigned flags; /* Internal */
hhash_t* tbl; /* Iterated table. */
uint32_t i; /* Current direct/indirect index. */
} hhash_iter_t;
/*! \brief Set iterator the the beginning of the table. */
void hhash_iter_begin (hhash_t*, hhash_iter_t*, bool sorted);
/*! \brief Next value. */
void hhash_iter_next (hhash_iter_t*);
/*! \brief Return true if at the end. */
bool hhash_iter_finished (hhash_iter_t*);
/*! \brief Return current key/keylen. */
const char *hhash_iter_key (hhash_iter_t*, uint16_t* len);
/*! \brief Return current value. */
value_t *hhash_iter_val(hhash_iter_t*);
#endif /* _KNOTD_HHTABLE_H_ */
/*! @} */
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