FdListener.hpp

// SPDX-FileCopyrightText: 2025-2026 Vincent Leroy
// SPDX-License-Identifier: MIT
//
// This file is part of dfx.
//
// Licensed under the MIT License. See the LICENSE file in the project root
// for full license information.
 
#pragma once
 
// Standard includes
#include <atomic>
#include <functional>
#include <thread>
 
// Project includes
#include <dfx-utilities/BorrowedFd.hpp>
#include <dfx-fdwatch/Events.hpp>
#include <dfx-utilities/OwnedFd.hpp>
 
namespace dfx::Runtime
{
class FdListener
{
public:
    struct FdInfo
    {
        Utils::BorrowedFd fd;

        FdWatch::EventTriggers events;

        FdWatch::EventInterests eventInterest;
    };
 
public:
    using Callback = std::move_only_function<void (std::vector<FdInfo> fdInfos)>;
 
public:
    explicit FdListener(Callback cb);

    ~FdListener();

    bool isRunning() const noexcept { return _running.load(std::memory_order::relaxed); }

    void registerFd(Utils::BorrowedFd fd, FdWatch::EventInterests events);

    void deregisterFd(Utils::BorrowedFd fd) noexcept;

    void updateFdEvents(Utils::BorrowedFd fd, FdWatch::EventInterests events);

    void rearmFd(Utils::BorrowedFd fd, FdWatch::EventInterests events);
 
private:
    void _start();
    void _stop() noexcept;
 
    void _init();
    void _listen(std::stop_token stopToken) noexcept;
    void _cleanup() noexcept;
 
private:
    Utils::OwnedFd _epfd;
    Utils::OwnedFd _evtfd;
    Callback _cb;
 
private:
    std::atomic_bool _running{false};
    std::jthread     _listener;
};
} // !namespace dfx::Runtime