[Boost-users] Synchronous problem with asio

Subject: [Boost-users] Synchronous problem with asio
From: Dan Benèík (eubie_at_[hidden])
Date: 2009-08-11 04:56:28

Dear everybody,
I have a problem using asio. My client/server application requires only synchronous communication. So, using the examples for synchro from the boost homepage, I have set up two procedures to send and receive data. Their code is as follows:

void vReceive(tcp::socket & socket, std::string & szDest){
    char szTmp_Buf [BUF_LEN + 1];
    szDest = "";
    std::cout << "Entering vReceive . . ." << std::endl;

    for (;;){
      char szBuf [BUF_LEN];
      boost::system::error_code error;
      uInt uiBytes_Recv = socket.read_some(boost::asio::buffer(szBuf), error);
      std::cout << " Read " << uiBytes_Recv << " bytes" << std::endl;
      if (error == boost::asio::error::eof)
         break; // Connection closed cleanly by peer.
      else if (error)
         throw boost::system::system_error(error); // Some other error.

      memcpy((void*) szTmp_Buf, (void*) szBuf, uiBytes_Recv );
      szTmp_Buf[ uiBytes_Recv ] = '\0';
      szDest += szTmp_Buf;
      };
   std::cout << "Received" << szDest << std::endl;
   std::cout << "Leaving vReceive . . ." << std::endl << std::endl;
   };

void vSend(tcp::socket & socket, std::string & szSrc){
    std::cout << "Entering vSend . . . " << std::endl;
    std::cout << "Sending " << szSrc << std::endl;
    boost::system::error_code ignored_error;
    boost::asio::write(socket, boost::asio::buffer(szSrc), boost::asio::transfer_all(), ignored_error);
    std::cout << "Leaving vSend . . . " << std::endl << std::endl;
    };

These procedures are just wrappers for the lines of code extracted from the boost examples.

In my test applications, the client calls

vReceive(socket, szDate);
vSend(socket, std::string("Chop Suey!") );
vReceive(socket, szDate);
vSend(socket, std::string("Halo"));

and the server calls

vSend(socket, message);
vReceive(socket, szReceived);
vSend(socket, message);
vReceive(socket, szReceived);

just to test the functionality. The problem is that both applications freeze after the first information exchange, as I have depicted on the following picture ( http://eubie.sweb.cz/asio_problem.JPG ). It seems that vReceive() procedure on the client side doesn´t finish while vSend() finishes on the server side. So, does anybody have any idea, what might be wrong?

Just in case someone wanted to replicate the problem, I uploaded the complete sources to http://eubie.sweb.cz/asio_problem.rar file.

Thank you all in advance, Daniel.