Boost.asio客戶端/服務器TIME_WAIT爲什麼？

Question

我想在一些API中運行一些功能測試。

我的API有一個客戶端和一個服務器端。 客戶端只連接並設置一個標誌。服務器只接受連接。

這是一個測試情況下，我有：

BOOST_AUTO_TEST_CASE(client_can_connect_to_server) { 
     boost::asio::io_service serverService; 
     std::thread serverLoop([&serverService] { serverService.run(); }); 

     boost::asio::io_service clientService; 
     std::thread clientLoop([&clientService] { clientService.run(); }); 

     // std::this_thread::sleep_for(10ms); Maybe wait for server loop to start...? 


     auto connectionSuccess = connectTo("127.0.0.1", "54321", kAuthData, ioService); 

     BOOST_REQUIRE(blockForDurationOrWhile 
         (timeout, 
         [&] { return connectionSuccess.wait_for(0s) != std::future_status::ready; }) == ExitStatus::ConditionSatisfied); 

     serverService.stop(); 
     clientLoop.join(); 
     serverService.join();  
    } 

我有兩件事情在這裏的麻煩：

1. 的連接超時超過一半的時間，但有時工作。

2. 當通過成功通過測試結束的程序完成程序時，似乎netstat顯示某種類型的套接字泄漏，狀態爲TIME_WAIT。我正在關閉並關閉插座。我無法弄清楚什麼是錯的。這被示爲應用程序退出後周圍30-45秒：

   TCP 0 0 IP6-本地主機：52256的IP6-本地主機：54321 TIME_WAIT
   TCP 0 0 IP6-本地主機：54321的IP6-本地主機：52256 TIME_WAIT

代碼客戶端和服務器的代碼如下：

std::future<bool> connectTo(std::string const & host, 
          std::string const & port, 
          std::string const & authData, 
          boost::asio::io_service & s, 
          std::chrono::high_resolution_clock::duration timeout = kCortexTryConnectTimeout) { 
    using namespace boost::asio; 
    using boost::asio::ip::tcp; 

    std::promise<bool> p; 
    auto res = p.get_future(); 
    spawn 
     (s, 
     [&s, host, port, p = std::move(p)](yield_context yield) mutable { 
      tcp::socket socket(s); 
      BOOST_SCOPE_EXIT(&socket) { 
       std::cout << "Closing client socket\n"; 
       if (socket.is_open()) { 
        boost::system::error_code ec{}; 
        socket.shutdown(boost::asio::ip::tcp::socket::shutdown_both, ec); 
        socket.close(); 
        std::cout << "Client socket closed\n"; 
       } 
      } BOOST_SCOPE_EXIT_END 

      std::cout << "Client trying to connect\n"; 
      tcp::resolver resolver(s); 
      boost::system::error_code ec{boost::asio::error::operation_aborted}; 
      boost::asio::async_connect(socket, resolver.resolve({host, port}), yield[ec]); 
      std::cout << "Client Connected\n"; 
      if (!ec) p.set_value(true); 
      else p.set_value(false); 
     }); 
    return res; 
} 

服務器處理連接：

class ConnectionsAcceptorTask { 
public: 
    //Session handling for Cortex. Will move out of here 
    class Session : public std::enable_shared_from_this<Session> { 
    public: 
     explicit Session(boost::asio::ip::tcp::socket socket) : _socket(std::move(socket)) {} 
     void start() {} 

     ~Session() { 
      if (_socket.is_open()) { 
       boost::system::error_code ec{}; 
       _socket.shutdown(boost::asio::ip::tcp::socket::shutdown_both, ec); 
       _socket.close(); 
      } 
     } 
    private: 
     boost::asio::ip::tcp::socket _socket; 
    }; 

    ConnectionsAcceptorTask(unsigned int port, 
          io_service & s) 
     : _port(port), 
      _ioService(&s) 
    {} 

    void operator()() { 
     namespace ba = boost::asio; 
     using boost::asio::ip::tcp; 
     ba::spawn 
      (*_ioService, 
      [s = _ioService, port = this->_port](ba::yield_context yield) { 

       tcp::acceptor acceptor 
        (*s, 
        tcp::endpoint(tcp::v4(), port)); 
       acceptor.set_option(boost::asio::socket_base::reuse_address(true)); 

       BOOST_SCOPE_EXIT(&acceptor) { 
        std::cout << "Closing acceptor\n"; 
        if (acceptor.is_open()) { 
         acceptor.close(); 
         std::cout << "Acceptor closed\n"; 
        } 
       } BOOST_SCOPE_EXIT_END 

       for (;;) { 
        boost::system::error_code ec{}; 
        tcp::socket socket(*s); 
        acceptor.async_accept(socket, yield[ec]); 

        if (!ec) std::make_shared<Session>(std::move(socket))->start(); 
       } 
      }); 
    } 
private: 
    unsigned int _port = 0; 
    boost::asio::io_service * _ioService; 
}; 

Answer 1

TIME_WAIT狀態不是套接字泄漏。它是TCP連接拆除的正常部分，在RFC 793中有詳細說明。