asio無法將消息寫入服務器兩次以上

Question

經過對該頁面的調查后，我嘗試編寫一個小程序來將消息寫入由python腳本開發的本地服務器。到目前為止，到目前為止，問題是我只能將消息寫入服務器一次。

#include <boost/array.hpp>
#include <boost/asio.hpp>

#include <iostream>
#include <string>

std::string input;
boost::asio::io_service io_service;
boost::asio::ip::tcp::resolver resolver(io_service);
boost::asio::ip::tcp::socket sock(io_service);
boost::array<char, 4096> buffer;

void connect_handler(const boost::system::error_code &ec)
{
    if(!ec){
        boost::asio::write(sock, boost::asio::buffer(input));
    }
}

void resolve_handler(const boost::system::error_code &ec, boost::asio::ip::tcp::resolver::iterator it)
{
    if (!ec){
        sock.async_connect(*it, connect_handler);
    }
}

void write_to_server(std::string const &message)
{
    boost::asio::ip::tcp::resolver::query query("127.0.0.1", "9999");
    input = message;
    resolver.async_resolve(query, resolve_handler);
    io_service.run();
}

int main()
{
    write_to_server("123");
    write_to_server("456");
}

這是python腳本

import SocketServer

class MyTCPHandler(SocketServer.BaseRequestHandler):
    """
    The RequestHandler class for our server.

    It is instantiated once per connection to the server, and must
    override the handle() method to implement communication to the
    client.
    """

    def handle(self):
        # self.request is the TCP socket connected to the client
        self.data = self.request.recv(1024).strip()
        print "{} wrote:".format(self.client_address[0])
        print self.data
        # just send back the same data, but upper-cased
        self.request.sendall(self.data.upper())     

if __name__ == "__main__":
    HOST, PORT = "localhost", 9999

    # Create the server, binding to localhost on port 9999
    server = SocketServer.TCPServer((HOST, PORT), MyTCPHandler)

    # Activate the server; this will keep running until you
    # interrupt the program with Ctrl-C
    server.serve_forever()

Answer 1

兩次使用之間未reset您的io_service 。

如果要在停止后再次使用相同的io_service ，則必須調用reset成員函數。

write_to_server("123");
io_service.reset();
write_to_server("456");

---

也就是說，這不是設計全部內容的最佳方法，您可能應該使用相同的io_service並不要停止它，但是由於io_service的run成員函數將是程序的主循環，因此您必須要么在連接回調中一個接一個地發送消息，或者創建某種事件驅動的程序，在該程序中，根據用戶輸入（例如，在stdin或套接字等上讀取）發送消息。 但這僅在您開發更大，更復雜的程序時才應考慮。