Sockets boost async\u accept不使用boost asio使用\u future选项

我想在有超时的

boost:：asio:：ip:：tcp:：socket上侦听。为此，我使用了
std:：future:：wait_For
函数。下面是我的代码：

std::optional<boost::asio::ip::tcp::socket> server::listen()
{
    boost::asio::ip::tcp::socket sock(io_service);
    std::future<void> accept_status = acceptor.async_accept(
        sock, boost::asio::use_future);
    if (accept_status.wait_for(std::chrono::seconds(10)) == std::future_status::timeout)
    {
        // I hope there's no race-condition between
        // accepting a connection and calling cancel
        acceptor.cancel();
        std::cerr << "Timeout" << std::endl;
        return {};
    }
    std::cerr << "Accepted a connection" << std::endl;
    return {std::move(sock)};
}

由
g++-std=c++17.cpp-lpthread-lboost\u system-o编译

我得到的结果是：

Connected to server
Timeout
Timeout
Timeout
Timeout
Timeout
Timeout
Timeout
Timeout
Timeout
Timeout
Timeout
Timeout
Timeout
...

要回答您的要求：

“future对象和异步接受函数不通信”--不可能

“客户端可以连接，但我仍然得到一个超时。”，--您的客户端连接到侦听器是一个事件，执行完成处理程序（设置承诺）是另一个事件

所以连接可能在第9秒被接受，而回调可能计划在第11秒运行（例如）

记住，我们处理的是异步操作，所以我认为对未来事件进行绝对预测是不对的

除此之外

// I hope there's no race-condition between
        // accepting a connection and calling cancel
        acceptor.cancel();
        std::cerr << "Timeout" << std::endl;
        return {};

在您的程序中有许多事情需要注意（避免不必要的旋转循环，不要忘记连接或分离
std:：thread
，并确保在使用
async*
version时调用
io\u service:：run
）

你增加了超时时间并检查了吗？嗨@Explorer\N，我已经编辑了这个问题以添加一个示例程序。你能在你的系统上测试它吗？你有没有看到
io\u service.run（）
？谢谢。我应该研究如何在异步调用中正确使用boost io服务。
// I hope there's no race-condition between
        // accepting a connection and calling cancel
        acceptor.cancel();
        std::cerr << "Timeout" << std::endl;
        return {};

using namespace std;

void server_listen() {
    boost::asio::io_service io_service;
    boost::asio::ip::tcp::endpoint endpoint(boost::asio::ip::tcp::v4(), 31132);
    boost::asio::ip::tcp::acceptor acceptor(io_service, endpoint);
    boost::asio::ip::tcp::socket socket(io_service);
    auto work = make_work_guard(io_service);
    using type= std::decay_t<decltype(work)>;
    std::thread io([&](){io_service.run();});
    std::future<void> accept_status = acceptor.async_accept(
            socket, boost::asio::use_future);
    if(accept_status.wait_for(std::chrono::seconds(10)) == std::future_status::timeout) {
        acceptor.cancel();
        std::cerr << "Timeout\n";
        work.~type();
        //break;
    } else {
        std::cout<<"future is ready\n";
        work.~type();
       // break;
    }

    io.join();
    // if I replace the lines starting from the async_accept call
    // by just the following, everything works as expected
    // acceptor.accept(socket);
    std::cout << "Accepted a connection\n";

}

void client_connect() {
    boost::asio::io_service io_service;
    boost::asio::ip::tcp::resolver resolver(io_service);
    boost::asio::ip::tcp::socket socket(io_service);
    boost::asio::ip::tcp::endpoint endpoint(*resolver.resolve({"127.0.0.1", std::to_string(31132)}));
    socket.connect(endpoint);
    std::cout << "Connected to server\n";

}
enter code here
int main() {
    std::thread server(server_listen);
    std::this_thread::sleep_for(std::chrono::seconds(2));
    std::thread client(client_connect);
    server.join(); client.join();
}

Start
Connected to server
future is ready
Accepted a connection
0
Finish