utils.h

// Copyright (c) 2014-2026 Savoir-faire Linux Inc.
// SPDX-License-Identifier: MIT
#pragma once
 
#include "def.h"
 
#include <type_traits>
#include <msgpack.hpp>
#include <fmt/format.h>
 
#include <chrono>
#include <random>
#include <functional>
#include <map>
#include <string_view>
 
#include <cstdarg>
 
#define WANT4 1
#define WANT6 2

namespace dht {
 
using NetId = uint32_t;
using want_t = int_fast8_t;
 
OPENDHT_PUBLIC const char* version();
 
// shortcut for std::shared_ptr
template<class T>
using Sp = std::shared_ptr<T>;
 
template<typename Key, typename Item, typename Condition>
void
erase_if(std::map<Key, Item>& map, const Condition& condition)
{
    for (auto it = map.begin(); it != map.end();) {
        if (condition(*it)) {
            it = map.erase(it);
        } else {
            ++it;
        }
    }
}
 
template<typename... Args>
std::string
concat(Args&&... args)
{
    static_assert((std::is_constructible_v<std::string_view, Args&&> && ...));
    std::string s;
    s.reserve((std::string_view {args}.size() + ...));
    (s.append(std::forward<Args>(args)), ...);
    return s;
}

OPENDHT_PUBLIC std::pair<std::string_view, std::string_view> splitPort(std::string_view s);
 
class OPENDHT_PUBLIC DhtException : public std::runtime_error
{
public:
    DhtException(const std::string& str = "")
        : std::runtime_error("DhtException occurred: " + str)
    {}
};
 
class OPENDHT_PUBLIC SocketException : public DhtException
{
public:
    SocketException(int err)
        : DhtException(strerror(err))
    {}
};
 
// Time related definitions and utility functions
 
using clock = std::chrono::steady_clock;
using system_clock = std::chrono::system_clock;
using time_point = clock::time_point;
using duration = clock::duration;
 
OPENDHT_PUBLIC time_point from_system_time(system_clock::time_point t,
                                           time_point steady_now,
                                           system_clock::time_point system_now);
OPENDHT_PUBLIC time_point from_system_time(system_clock::time_point t);
OPENDHT_PUBLIC system_clock::time_point to_system_time(time_point t,
                                                       time_point steady_now,
                                                       system_clock::time_point system_now);
OPENDHT_PUBLIC system_clock::time_point to_system_time(time_point t);
OPENDHT_PUBLIC time_point from_time_t(std::time_t t);
OPENDHT_PUBLIC std::time_t to_time_t(time_point t);
 
template<class DT>
static std::string
print_duration(DT d)
{
    if (d < std::chrono::seconds(0)) {
        return "-" + print_duration(-d);
    } else if (d < std::chrono::milliseconds(1)) {
        return fmt::format("{:.3g} us",
                           std::chrono::duration_cast<std::chrono::duration<double, std::micro>>(d).count());
    } else if (d < std::chrono::seconds(1)) {
        return fmt::format("{:.3g} ms",
                           std::chrono::duration_cast<std::chrono::duration<double, std::milli>>(d).count());
    } else if (d < std::chrono::minutes(1)) {
        return fmt::format("{:.3g} s", std::chrono::duration_cast<std::chrono::duration<double>>(d).count());
    } else if (d < std::chrono::hours(1)) {
        return fmt::format("{:.3g} min",
                           std::chrono::duration_cast<std::chrono::duration<double, std::ratio<60>>>(d).count());
    } else if (d < std::chrono::hours(72)) {
        return fmt::format("{:.3g} h",
                           std::chrono::duration_cast<std::chrono::duration<double, std::ratio<3600>>>(d).count());
    } else {
        return fmt::format("{:.3g} days",
                           std::chrono::duration_cast<std::chrono::duration<double, std::ratio<86400>>>(d).count());
    }
}
 
template<class TimePoint>
static std::string
print_time_relative(TimePoint now, TimePoint d)
{
    using namespace std::literals;
    if (d == TimePoint::min())
        return "never"s;
    if (d == now)
        return "now"s;
    return (d > now) ? concat("in "sv, print_duration(d - now)) : concat(print_duration(now - d), " ago"sv);
}
 
OPENDHT_PUBLIC std::string printByteCount(size_t bytes);
 
template<typename Duration = duration>
class uniform_duration_distribution : public std::uniform_int_distribution<typename Duration::rep>
{
    using Base = std::uniform_int_distribution<typename Duration::rep>;
    using param_type = typename Base::param_type;
 
public:
    uniform_duration_distribution(Duration min, Duration max)
        : Base(min.count(), max.count())
    {}
    template<class Generator>
    Duration operator()(Generator&& g)
    {
        return Duration(Base::operator()(g));
    }
    template<class Generator>
    Duration operator()(Generator&& g, const param_type& params)
    {
        return Duration(Base::operator()(g, params));
    }
};
 
// Serialization related definitions and utility functions

using Blob = std::vector<uint8_t>;

OPENDHT_PUBLIC Blob unpackBlob(const msgpack::object& o);
 
template<typename Type>
Blob
packMsg(const Type& t)
{
    msgpack::sbuffer buffer;
    msgpack::packer<msgpack::sbuffer> pk(&buffer);
    pk.pack(t);
    return {buffer.data(), buffer.data() + buffer.size()};
}
 
template<typename Type>
Type
unpackMsg(const Blob& b)
{
    msgpack::unpacked msg_res = msgpack::unpack((const char*) b.data(), b.size());
    return msg_res.get().as<Type>();
}
 
inline msgpack::unpacked
unpackMsg(const Blob& b)
{
    return msgpack::unpack((const char*) b.data(), b.size());
}
 
OPENDHT_PUBLIC msgpack::object* findMapValue(const msgpack::object& map, const char* key, size_t length);
 
inline msgpack::object*
findMapValue(const msgpack::object& map, const char* key)
{
    return findMapValue(map, key, strlen(key));
}
inline msgpack::object*
findMapValue(const msgpack::object& map, std::string_view key)
{
    return findMapValue(map, key.data(), key.size());
}
 
} // namespace dht