io_context.hh

#pragma once

#include "lazy.hh"
#include <set>
#include <stdexcept>
#include <sys/epoll.h>
#include <vector>

#include "socket_accept_operation.hh"
#include "socket_recv_operation.hh"
#include "socket_send_operation.hh"

/* Just an epoll wrapper */
class Socket;

struct oneway_task {
    struct promise_type {
        std::suspend_never initial_suspend() noexcept { return {}; }
        std::suspend_never final_suspend() noexcept { return {}; }
        void unhandled_exception() { }
        oneway_task get_return_object() { return {}; }
        void return_void() { }
    };
};

class IOContext {
public:
    IOContext()
        : fd_{epoll_create1(0)}
    {
        if (fd_ == -1)
            throw std::runtime_error{"epoll_create1"};
    }

    void run();
    void spawn(std::lazy<>&& task);

private:
    constexpr static std::size_t max_events = 10;
    const int fd_;

    // Fill it by watchRead / watchWrite
    std::set<Socket*> processedSockets_;
    std::vector<std::lazy<>> delayDestructor_;

    friend Socket;
    friend SocketAcceptOperation;
    friend SocketRecvOperation;
    friend SocketSendOperation;
    void attach(Socket* socket);
    void watchRead(Socket* socket);
    void unwatchRead(Socket* socket);
    void watchWrite(Socket* socket);
    void unwatchWrite(Socket* socket);
    void detach(Socket* socket);

    void cleanIO();
};