netsurf/utils/bloom.h

100 lines
2.7 KiB
C

/*
* Copyright 2013 Rob Kendrick <rjek@netsurf-browser.org>
*
* This file is part of NetSurf, http://www.netsurf-browser.org/
*
* NetSurf 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; version 2 of the License.
*
* NetSurf 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
* Trivial bloom filter */
#ifndef _NETSURF_UTILS_BLOOM_H_
#define _NETSURF_UTILS_BLOOM_H_
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
struct bloom_filter;
/**
* Create a new bloom filter.
*
* \param size Size of bloom filter in bytes
* \return Handle for newly-created bloom filter, or NULL
*/
struct bloom_filter *bloom_create(size_t size);
/**
* Destroy a previously-created bloom filter
*
* \param b Bloom filter to destroy
*/
void bloom_destroy(struct bloom_filter *b);
/**
* Insert a string of given length (may include NULs) into the filter,
* using an internal hash function.
*
* \param b Bloom filter to add to
* \param s Pointer to data
* \param z Length of data
*/
void bloom_insert_str(struct bloom_filter *b, const char *s, size_t z);
/**
* Insert a given hash value into the filter, should you already have
* one to hand.
*
* \param b Bloom filter to add to
* \param hash Value to add
*/
void bloom_insert_hash(struct bloom_filter *b, uint32_t hash);
/**
* Search the filter for the given string, assuming it was added by
* bloom_insert_str(). May return false-positives.
*
* \param b Bloom filter to search
* \param s Pointer to data to search for
* \param z Length of data
*
* \return False if never added, True if it might have been.
*/
bool bloom_search_str(struct bloom_filter *b, const char *s, size_t z);
/**
* Search the filter for the given hash value, assuming it was added by
* bloom_insert_hash(). May return false-positives.
*
* \param b Bloom filter to search
* \param hash Hash value to search for
*
* \return False if never added, True if it might have been.
*/
bool bloom_search_hash(struct bloom_filter *b, uint32_t hash);
/**
* Find out how many items have been added to this bloom filter. This
* is useful for deciding the size of a new bloom filter should you
* need to rehash it.
*
* \param b Bloom filter to examine
*
* \return Number of items that have been added
*/
uint32_t bloom_items(struct bloom_filter *b);
#endif