CODEWITHSUNDEEP
c++multithreadingtcpnetwork-programmingboost-asio
Jackmekiss
Jackmekiss

Reputation: 743

boost asio - io_service don't wait connection into threads

I want to create a server async with multi threads. When I create a thread_group and waiting for some connections in asynchronous way. My program don't wait and termine immediatly.

void Server::configServer() {
    _ip = boost::asio::ip::address_v4::from_string("127.0.0.1");
    boost::asio::ip::tcp::resolver resolver(_io_service);
    _endpoint = *resolver.resolve({tcp::v4(), _port});
    std::cout << "Server address: " << _ip.to_string() << ":" << _port << std::endl;

    _acceptor.close();
    _acceptor.open(_endpoint.protocol());
    _acceptor.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
    _acceptor.bind(_endpoint);
    _acceptor.listen();
    for (int i = 0; i < 8; ++i) {
        _threads.create_thread(boost::bind(&boost::asio::io_service::run, &_io_service));
    }
    _threads.join_all();
    std::cout << "Server is set up" << std::endl;
    run();
}

void Server::run() {
    Connection::pointer newConnection = Connection::create(_acceptor.get_io_service());
    std::cout << "Server is running" << std::endl;

    _acceptor.async_accept(newConnection->socket(),
        boost::bind(&Server::handleAccept, this, newConnection,
        boost::asio::placeholders::error));
}

void Server::handleAccept(Connection::pointer newConnection, const boost::system::error_code& error) {
    if (!error) {
        std::cout << "Reçu un client!" << std::endl;
        newConnection->start();
        run();
    }
}

Can you tell me what am I doing wrong ?

Upvotes: 1

Views: 624

Answers (1)

rafix07
rafix07

Reputation: 20936

run works as long as there are any pending tasks/handlers to be processed.

In your case you started run, then first async_ method was called. So run ends immediately due to no handlers to be called.

You should init some asynchronous task, then invoke run or use object called work guard. You didn't specify which version of Boost you use, but there are two options:

  • in olders io_service/io_context::work (ref)
  • current, executor_work_guard (ref)

In your class you can add executor_work_guard as additional member variable:

class Server {
    boost::asio::io_context _io_service;
    boost::asio::executor_work_guard<boost::asio::io_context::executor_type> guard;

    Server() : ...., guard(boost::asio::make_work_guard(_io_service)) {

    }
};

with this approach, run doesn't return even if there are no handlers to be processed.

Upvotes: 2

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