mirror of
https://github.com/matrix-construct/construct
synced 2024-11-09 11:31:11 +01:00
108 lines
3.2 KiB
C++
108 lines
3.2 KiB
C++
/*
|
|
* charybdis: 21st Century IRC++d
|
|
*
|
|
* Copyright (C) 2017 Charybdis Development Team
|
|
* Copyright (C) 2017 Jason Volk <jason@zemos.net>
|
|
*
|
|
* Permission to use, copy, modify, and/or distribute this software for any
|
|
* purpose with or without fee is hereby granted, provided that the above
|
|
* copyright notice and this permission notice is present in all copies.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
|
|
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
|
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
|
|
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
|
|
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
|
|
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
|
|
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#pragma once
|
|
#define HAVE_IRCD_CUCKOO_H
|
|
|
|
/// Cuckoo filtering and hashing.
|
|
///
|
|
/// This is an API for building cuckoo filters for efficient set membership
|
|
/// tests. Cuckoo filters are a recently celebrated result by Bin Fan inspired
|
|
/// by Mitzenmacher's seminal thesis: the Power Of Two choices in randomized
|
|
/// linear load balancing. These filters are used extensively to optimize
|
|
/// queries made into matrix room state after accumulating events.
|
|
///
|
|
/// Note that the hash residue has to be kept secret from an adversary who
|
|
/// may try to craft strings to attack the filter. A secret salt should be
|
|
/// used. Filters may also be serialized to the db so the salt will have to
|
|
/// persist secretly too.
|
|
///
|
|
namespace ircd::cuckoo
|
|
{
|
|
IRCD_EXCEPTION(ircd::error, error)
|
|
|
|
template<class word, size_t words> struct entry;
|
|
template<class entry, size_t entries> struct bucket;
|
|
template<class bucket, size_t buckets> struct table;
|
|
|
|
struct filter;
|
|
struct counter;
|
|
}
|
|
|
|
template<class word,
|
|
size_t words>
|
|
struct ircd::cuckoo::entry
|
|
:std::array<word, words>
|
|
{
|
|
using array_type = std::array<word, words>;
|
|
|
|
};
|
|
|
|
template<class entry,
|
|
size_t entries>
|
|
struct ircd::cuckoo::bucket
|
|
:std::array<entry, entries>
|
|
{
|
|
using array_type = std::array<entry, entries>;
|
|
|
|
};
|
|
|
|
template<class bucket,
|
|
size_t buckets>
|
|
struct ircd::cuckoo::table
|
|
:std::array<bucket, buckets>
|
|
{
|
|
using array_type = std::array<bucket, buckets>;
|
|
|
|
static_assert(is_powerof2(buckets), "Bucket count must be power of 2");
|
|
};
|
|
|
|
struct ircd::cuckoo::filter
|
|
{
|
|
using entry = cuckoo::entry<uint8_t, 1>;
|
|
using bucket = cuckoo::bucket<entry, 1>;
|
|
using table = cuckoo::table<bucket, 32>;
|
|
|
|
table a, b;
|
|
|
|
bool has(const string_view &) const;
|
|
|
|
void add(const string_view &);
|
|
void del(const string_view &);
|
|
};
|
|
|
|
struct ircd::cuckoo::counter
|
|
{
|
|
using int_t = int32_t;
|
|
using entry = cuckoo::entry<int_t, 1>;
|
|
using bucket = cuckoo::bucket<entry, 1>;
|
|
using table = cuckoo::table<bucket, 32>;
|
|
|
|
table a, b;
|
|
|
|
int_t count(const string_view &) const;
|
|
bool has(const string_view &) const;
|
|
|
|
void add(const string_view &);
|
|
void del(const string_view &);
|
|
};
|