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提升asio:如何保持客户端连接活着?

发布时间:2020-12-16 09:31:00 所属栏目:百科 来源:网络整理
导读:我尝试创建一个在服务器上保持连接活动的客户端. 但是,当我收到一次数据时,连接已关闭.我不明白为什么. 我认为我应该制作一个循环,但我们告诉我这不是一个好主意. class client{public: client(boost::asio::io_service io_service,const std::string host,c
我尝试创建一个在服务器上保持连接活动的客户端.

但是,当我收到一次数据时,连接已关闭.我不明白为什么.

我认为我应该制作一个循环,但我们告诉我这不是一个好主意.

class client
{
public:
  client(boost::asio::io_service& io_service,const std::string& host,const std::string& service)
    : connection_(io_service)
  {
    // Resolve the host name into an IP address.
    boost::asio::ip::tcp::resolver resolver(io_service);
    boost::asio::ip::tcp::resolver::query query(host,service);
    boost::asio::ip::tcp::resolver::iterator endpoint_iterator =
      resolver.resolve(query);
    boost::asio::ip::tcp::endpoint endpoint = *endpoint_iterator;

    // Start an asynchronous connect operation.
    connection_.socket().async_connect(endpoint,boost::bind(&client::handle_connect,this,boost::asio::placeholders::error,++endpoint_iterator));
  }

  /// Handle completion of a connect operation.
  void handle_connect(const boost::system::error_code& e,boost::asio::ip::tcp::resolver::iterator endpoint_iterator)
  {
    if (!e)
    {
      // Successfully established connection. Start operation to read the list
      // of stocks. The connection::async_read() function will automatically
      // decode the data that is read from the underlying socket.
      connection_.async_read(stocks_,boost::bind(&client::handle_read,boost::asio::placeholders::error));
    }
    else
    {
      std::cerr << e.message() << std::endl;
    }
  }

  /// Handle completion of a read operation.
  void handle_read(const boost::system::error_code& e)
  {
    if (!e)
    {
      // Print out the data that was received.
      for (std::size_t i = 0; i < stocks_.size(); ++i)
      {
        std::cout << "Paquet numero " << i << "n";
        std::cout << "  age: " << stocks_[i].age << "n";
        std::cout << "  name: " << stocks_[i].nom << "n";
      }

                // Maybe Should i put something here ?
    }
    else
    {
      // An error occurred.
        std::cerr << "Error : " << e.message() << std::endl;
        connection_.socket().close();
    }

    // or maybe here ?

  }

private:
  /// The connection to the server.
  connection            connection_;
  std::vector<stock>    stocks_;
};

主要看起来像这样:

int main(int argc,char* argv[])
{
  try
  {
    // Check command line arguments.
    if (argc != 3)
    {
      std::cerr << "Usage: client <host> <port>" << std::endl;
      return 1;
    }

    boost::asio::io_service io_service;

    client client(io_service,argv[1],argv[2]);
    io_service.run();
  }
  catch (std::exception& e)
  {
    std::cerr << e.what() << std::endl;
  }

  return 0;
}

解决方法

首先,您的asio io_service正在完成工作.在handle_read中,你把评论“也许我应该把东西放在这里”你可以安排下一个异步读操作:

connection_.async_read(stocks_,boost::asio::placeholders::error));

通常情况下,如果您是异步编程,一旦是异步编程.调用handler,你将调用下一个异步.操作,就像你在异步连接处理程序中所做的那样.

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