升壓asio定時器不能阻止讀取呼叫

Question

我有以下服務器代碼。等待客戶端連接，並且一旦客戶端連接它就會啓動從客戶端接收數據的線程，主線程將等待另一個客戶端連接。此代碼工作正常。

現在我必須指定服務器會等待一段時間說10秒，從連接的客戶端接收數據。否則服務器將在指定時間內沒有收到數據的情況下關閉通訊。我已經實現了相同的計時器，但不知何故，它不工作，並且timer_callback不會在時間流逝後調用。

#include <ctime> 
#include <iostream> 
#include <string> 
#include <boost/asio.hpp> 
#include <sys/socket.h> 
#include <unistd.h> 
#include <string> 
#include <boost/bind.hpp> 
#include <boost/thread.hpp> 
#include <boost/date_time.hpp> 

using namespace std; 
using boost::asio::ip::tcp; 

void run(boost::shared_ptr<tcp::socket> my_socket) 
{ 
    while (1) 
    { 
     char buf[128]; 
     boost::system::error_code error; 

     size_t len = my_socket->read_some(boost::asio::buffer(buf, 128), error); 
     std::cout << "len : " << len << std::endl; 

     if (error == boost::asio::error::eof) 
     { 
      cout << "\t(boost::asio::error::eof)" << endl; 
      if (my_socket->is_open()) 
      { 
       boost::system::error_code ec; 
       cout << "\tSocket closing" << endl; 
       my_socket->shutdown(boost::asio::ip::tcp::socket::shutdown_both, ec); 
       cout << "\tShutdown " << ec.message() << endl; 
       //cout << "normal close : " << ::close(my_socket->native_handle()) << endl; 
       my_socket->close(ec); 
       cout << "\tSocket closed" << endl; 
      } 
      break; // Connection closed cleanly by peer. 
     } 
     else if (error) 
     { 
      std::cout << "Exception : " << error.message() << std::endl; 
      break; 
     } 
     else 
     { 
      for (unsigned int i = 0; i < len; i++) 
       printf("%02x ", buf[i] & 0xFF); 
      printf("\n"); 
     } 
    } 
} 

void timer_callback(boost::shared_ptr<tcp::socket> my_socket, const boost::system::error_code& error) 
{ 
    std::cout << "timer expired.... " << std::endl; 
    if (error != boost::asio::error::operation_aborted) 
    { 
     // do something 
     std::string str_error = "timer expired " + error.message(); 
     my_socket->shutdown(boost::asio::ip::tcp::socket::shutdown_both); 
     my_socket->close(); 
    } 
    else 
    { 
     std::cout << "timer cancelled ..." << error.message() << std::endl; 
    } 
} 

int main() 
{ 
    const int S = 1000; 
    vector<boost::shared_ptr<boost::thread> > arr_thr(S); 
    boost::asio::io_service io_service; 
    boost::asio::deadline_timer timer(io_service); 

    try 
    { 
     for (uint32_t i = 0;; i++) 
     { 

      tcp::endpoint endpoint(tcp::v6(), 10001); 

      boost::shared_ptr<tcp::socket> my_socket(new tcp::socket(io_service)); 
      tcp::endpoint end_type; 

      tcp::acceptor acceptor(io_service, endpoint); 

      std::cout << "before accept" << endl; 
      acceptor.accept(*my_socket, end_type); 

      usleep(10000); 

      std::cout << "connected... hdl : " << my_socket->native_handle() << std::endl; 

      boost::asio::ip::address addr = end_type.address(); 
      std::string sClientIp = addr.to_string(); 

      std::cout << "\tclient IP : " << sClientIp << std::endl; 

      timer.expires_from_now(boost::posix_time::seconds(10)); 
      timer.async_wait(
        boost::bind(&timer_callback, my_socket, boost::asio::placeholders::error)); 

      arr_thr[i] = boost::shared_ptr<boost::thread>(new boost::thread(&run, my_socket)); 
     } 
    } catch (std::exception& e) 
    { 
     std::cerr << e.what() << std::endl; 
    } 

    return 0; 
} 

Answer 1

它看起來像你想要做在主線程的accept和async_wait，做一些阻擋在單獨的線程讀取。

有多種問題，這種做法。首先你的accept被阻塞，所以定時器在主線程等待接受時不能運行。也沒有呼叫io_servicerun或poll，所以異步處理程序將永遠不會被調用。

你必須使用async_accept如果你想將它與async_wait在同一個線程混合。

但是您仍然無法取消另一個線程讀取的阻塞。 documentation指出同時使用來自多個線程的套接字是不安全的（共享對象：不安全）。

我會建議你使用完全異步設計。