orotool/src/app_config.cpp

/* Copyright 2020, Michele Santullo
 * This file is part of orotool.
 *
 * Orotool 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.
 *
 * Orotool 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 Orotool.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "app_config.hpp"
#include "orotool_config.hpp"
#include <fstream>
#include <string>
#include <string_view>
#include <thread>
#include <algorithm>
#include <stdexcept>
#include <iostream>

namespace duck {

namespace {
	constexpr const char g_db_path_sect[] = "system";
	constexpr const char g_db_path[] = "db_path";

	constexpr const char g_worker_threads_sect[] = "system";
	constexpr const char g_worker_threads[] = "worker_threads";

	std::string whole_ini() {
		std::ifstream input(g_config_file_path);
		input >> std::noskipws;
		return { std::istream_iterator<char>(input), std::istream_iterator<char>() };
	}

	std::string_view value_ifp (
		const kamokan::IniFile& ini,
		std::string_view section,
		std::string_view key,
		std::string_view def,
		bool allow_empty
	) {
		const auto& map = ini.parsed();
		auto it_section = map.find(section);
		if (map.end() == it_section)
			return def;

		auto it_setting = it_section->second.find(key);
		if (it_section->second.end() == it_setting)
			return def;

		if (not allow_empty and it_setting->second.empty())
			return def;
		else
			return it_setting->second;
	}
} //unnamed namespace

AppConfig::AppConfig() :
	m_ini(whole_ini())
{
}

AppConfig::~AppConfig() noexcept = default;

std::string_view AppConfig::db_path() const {
	return value_ifp(m_ini, g_db_path_sect, g_db_path, g_def_sqlite_db_name, false);
}

std::size_t AppConfig::worker_threads() const {
	std::string_view opt_name(g_worker_threads);

	std::string_view val = value_ifp(m_ini, g_worker_threads_sect, opt_name, g_def_worker_threads, false);
	if (val == "max") {
		return std::max(3U, std::thread::hardware_concurrency()) - 1;
	}
	else {
		try {
			const std::size_t num = std::stoul(std::string(val.data(), val.size()));
			const std::size_t hard_max = 4U * std::thread::hardware_concurrency();
			return std::max<std::size_t>(2U, std::min(num, hard_max));
		}
		catch (const std::logic_error& err) {
			std::cerr << "Error reading setting " << opt_name << ": " << err.what() << '\n';
			return std::stoul(g_def_worker_threads);
		}
	}
}

} //namespace duck