mirror of
https://github.com/boostorg/bloom.git
synced 2026-01-27 18:52:10 +00:00
94 lines
2.3 KiB
C++
94 lines
2.3 KiB
C++
/* Serialization of boost::bloom::filter.
|
|
*
|
|
* Copyright 2025 Joaquin M Lopez Munoz.
|
|
* Distributed under the Boost Software License, Version 1.0.
|
|
* (See accompanying file LICENSE_1_0.txt or copy at
|
|
* http://www.boost.org/LICENSE_1_0.txt)
|
|
*
|
|
* See https://www.boost.org/libs/bloom for library home page.
|
|
*/
|
|
|
|
#include <boost/bloom/filter.hpp>
|
|
#include <boost/bloom/multiblock.hpp>
|
|
#include <boost/core/detail/splitmix64.hpp>
|
|
#include <boost/cstdint.hpp>
|
|
#include <boost/uuid/uuid.hpp>
|
|
#include <cstring>
|
|
#include <fstream>
|
|
#include <iostream>
|
|
|
|
/* emits a deterministic pseudorandom sequence of UUIDs */
|
|
|
|
struct uuid_generator
|
|
{
|
|
boost::uuids::uuid operator()()
|
|
{
|
|
boost::uint64_t x = rng();
|
|
std::memcpy(&data[0], &x, sizeof(x));
|
|
x = rng();
|
|
std::memcpy(&data[8], &x, sizeof(x));
|
|
|
|
return {data};
|
|
}
|
|
|
|
boost::detail::splitmix64 rng;
|
|
std::uint8_t data[16];
|
|
};
|
|
|
|
using filter = boost::bloom::filter<
|
|
boost::uuids::uuid, 1, boost::bloom::multiblock<boost::uint64_t, 8> >;
|
|
|
|
static constexpr std::size_t num_elements = 10000;
|
|
|
|
/* creates a filter with num_elements UUIDs */
|
|
|
|
filter create_filter()
|
|
{
|
|
uuid_generator gen;
|
|
filter f(num_elements, 0.005);
|
|
for(std::size_t i = 0; i < num_elements; ++i) f.insert(gen());
|
|
return f;
|
|
}
|
|
|
|
static constexpr const char* filename = "filter.bin";
|
|
|
|
void save_filter(const filter& f)
|
|
{
|
|
std::ofstream out(filename, std::ios::binary | std::ios::trunc);
|
|
std::size_t c=f.capacity();
|
|
out.write((const char*) &c, sizeof(c)); /* save capacity (bits) */
|
|
auto s = f.array();
|
|
out.write((const char*) s.data(), s.size()); /* save array */
|
|
}
|
|
|
|
filter load_filter()
|
|
{
|
|
std::ifstream in(filename, std::ios::binary);
|
|
std::size_t c;
|
|
in.read((char*) &c, sizeof(c));
|
|
filter f(c);
|
|
auto s = f.array();
|
|
in.read((char*) s.data(), s.size()); /* load array */
|
|
return f;
|
|
}
|
|
|
|
int main()
|
|
{
|
|
/* creates and saves filter and then loads it */
|
|
|
|
save_filter(create_filter());
|
|
auto f = load_filter();
|
|
|
|
/* Check that all the UUIDs used on filter creation are actually contained
|
|
* in the restored filter.
|
|
*/
|
|
|
|
uuid_generator gen;
|
|
std::size_t n = 0;
|
|
for(std::size_t i = 0; i < num_elements; ++i) {
|
|
if (f.may_contain(gen())) ++n;
|
|
}
|
|
if (n == num_elements) std::cout << "all elements in filter\n";
|
|
else std::cout << "something went wrong\n";
|
|
}
|