fortuna/fortuna.h

#ifndef FORTUNA_FORTUNA_H
#define FORTUNA_FORTUNA_H

#include "accumulator.h"
#include "generator.h"
#include "pool.h"

#include <fmt/core.h>

#include <array>
#include <atomic>
#include <cassert>
#include <chrono>
#include <cstdint>
#include <exception>
#include <latch>
#include <memory>
#include <mutex>
#include <thread>

namespace fortuna {

class Fortuna final {
public:
	static constexpr const char NUM_OF_POOLS{32};
	static constexpr const uint64_t two_pow_twenty{1048576};
	std::mutex mtx;
	std::mutex mtx_random_data;
	std::mutex mtx_p_pools;
	mutable std::mutex mtx_accu; // used in const fun, too
	std::mutex print_mtx;
	std::jthread th_sfm;
	std::jthread th_urandom;

	Fortuna();
	~Fortuna() noexcept;

	[[optimize_for_synchronized]] auto random_data(const uint64_t) -> void;
	[[optimize_for_synchronized]] auto moar_random_data(const uint64_t&)
		-> void;

	auto set_reseed_ctr_to_null() -> void {
		std::scoped_lock sl(mtx_accu, print_mtx);
		this->_p_accumulator->set_reseed_ctr_to_null();
		fmt::print(stderr, "reseed_ctr set to 0x00\n");
	}

	auto incr_reseed_ctr() -> void {
		std::scoped_lock sl(mtx, mtx_accu);
		this->_p_accumulator->incr_reseed_ctr();
	}

	auto get_reseed_ctr() const -> uint64_t {
		std::lock_guard<std::mutex> lg(mtx_accu);
		return this->_p_accumulator->get_reseed_ctr();
	}

	auto initialize_prng() -> void {
		try {
			std::call_once(PRNG_init, [] { ; });

			set_reseed_ctr_to_null();

			std::scoped_lock sl(mtx_accu, mtx_p_pools);

			{
				std::lock_guard<std::mutex> lg(print_mtx);

				R.initialize_pools();
				fmt::print(stderr, "[i] fortuna: pools initialized\n");
			}

			this->_p_accumulator->set_pools_ptr(R._p_pools);
			this->_p_accumulator->set_gen_ptr(R.Gen);

			this->sync_point.count_down();
		}
		catch (std::exception& e) {
			std::lock_guard<std::mutex> lg(print_mtx);
			fmt::print(
				stderr,
				"{}\n[!] fortuna: fatal error, PRNG initialization FAILED!\n\n",
				e.what());
			throw;
		}

		std::lock_guard<std::mutex> lg(print_mtx);
		fmt::print(stderr, "[*] fortuna: PRNG initialized\n");
	}

	auto seed_file_manager_service() -> void;

	auto urandom_entropy_src_service() -> void;

	auto stop_running() -> int {
		try {
			fmt::print(stderr, "[i] fortuna: received the stop request...\n");
			this->continue_running.store(false);
		}
		catch (std::exception& e) {
			throw;
		}
		return 0;
	}

	// PRNG state
	class R_state {
		friend fortuna::Fortuna;

	public:
		R_state() noexcept {}
		~R_state() noexcept = default;

	protected:
		auto initialize_pools() -> void {
			unsigned int i{accumulator::Accumulator::init_pool_num};
			assert(i == 0);
			for (; i < Fortuna::NUM_OF_POOLS; ++i) {
				this->_p_pools->at(i).initialize_pool(i);
			}
		}

	private:
		generator::Generator Gen;

		// _p_pools points to the array of 32 Pool objects
		std::shared_ptr<std::array<accumulator::Pool, Fortuna::NUM_OF_POOLS>>
			_p_pools{std::make_shared<
				std::array<accumulator::Pool, Fortuna::NUM_OF_POOLS>>()};

		std::chrono::steady_clock::time_point last_reseed;
	}; // class R_state

	fortuna::Fortuna::R_state R;
	std::shared_ptr<accumulator::Accumulator> _p_accumulator{
		std::make_shared<accumulator::Accumulator>()};

	std::latch sync_point{1}; // wait for init before spawning the threads
	std::latch die_point{2}; // wait for service threads to die
	std::atomic<bool> continue_running{true};
	std::once_flag PRNG_init;

}; // class Fortuna

} // namespace fortuna

#endif // FORTUNA_FORTUNA_H