如何为多线程客户端访问多个线程上的相同套接字

Question

I have a multi-threaded client that's set up in order to receive messages on one thread from the server, while the other thread waits for user input in order to send a message to the server.

I am new to this, and what my code currently does is: both threads would individually connect to server, which made the server recognise the single client as two clients (since both threads connected to server individually). How do I fix this so that the receive and send connections would utilise the same connection?

I have included the relevant portion of my client code (connecting to server is through the function connectToServer)

/*thread for sending messages to server*/
DWORD WINAPI send_handle_thread(LPVOID threadInfo)
{
/*structure contains all the data this callback works on*/
myThreadArgument* send_argument = (myThreadArgument*)threadInfo;

/*get client connection*/
myTcpSocket my_client(PORTNUM);

string server_ip_address = "";
readServerConfig(server_ip_address);

my_client.connectToServer(server_ip_address, ADDRESS); //this is where the thread connects to server

while (1)
{
    /*send messages*/

}
return 1;
}

/*thread for receiving messages from server*/
DWORD WINAPI rec_handle_thread(LPVOID threadInfo)
{
/*structure contains all the data this callback works on*/
myThreadArgument* send_argument = (myThreadArgument*)threadInfo;

/*get client connection*/
myTcpSocket my_client(PORTNUM);

string server_ip_address = "";
readServerConfig(server_ip_address);

my_client.connectToServer(server_ip_address, ADDRESS); //this is where thread connects to server

int rec_bytes = 0;

while (1)
{
    /*receive messages*/

}
return 1;
}

int main()
{
/*build a semaphore to synchronise access to std::cout*/
mySemaphore cout_semaphore(string(""),1);

/*initialize the winsock library*/
myTcpSocket::initialize();

/*get local (client) information (assume neither the name nor the address is given)*/
myHostInfo client_info;
string client_name = client_info.getHostName();
string client_ip_address = client_info.getHostIPAddress();

cout << "local host (client) information: " << endl;
cout << "   name:       " << client_name << endl;
cout << "   address:    " << client_ip_address << endl << endl;

/*retrieve server's IP name and address*/
string server_ip_address = "";
readServerConfig(server_ip_address);

myHostInfo server_info(server_ip_address, ADDRESS);
string server_name = server_info.getHostName();

cout << "remote host (server) information: " << endl;
cout << "   name:       " << server_name << endl;
cout << "   address:    " << server_ip_address << endl;

/*retrieve client's IP name and address*/
myTcpSocket my_client(PORTNUM);
cout << my_client;

/*create thread to send messages to server*/
myThreadArgument* send_argument = new myThreadArgument(&my_client, &cout_semaphore, client_name);
myThread* send_thread = new myThread(send_handle_thread, (void*)send_argument);
send_thread->execute();

/*create thread to receive message from server*/
myThreadArgument* rec_argument = new myThreadArgument(&my_client, &cout_semaphore, client_name);
myThread* rec_thread = new myThread(rec_handle_thread, (void*)rec_argument);
rec_thread->execute();

while (1)
{
    Sleep(300);
    cout << "main thread";
}

return 1;
}

connectToServer code:

void myTcpSocket::connectToServer(string& serverNameOrAddr,hostType hType)
{ 
/* 
   when this method is called, a client socket has been built already,
   so we have the socketId and portNumber ready.

   a myHostInfo instance is created, no matter how the server's name is 
   given (such as www.yuchen.net) or the server's address is given (such
   as 169.56.32.35), we can use this myHostInfo instance to get the 
   IP address of the server
*/

myHostInfo serverInfo(serverNameOrAddr,hType);

// Store the IP address and socket port number  
struct sockaddr_in serverAddress;
serverAddress.sin_family = AF_INET;
serverAddress.sin_addr.s_addr = inet_addr(serverInfo.getHostIPAddress());
serverAddress.sin_port = htons(portNumber);

// Connect to the given address
try 
{
    if (connect(socketId,(struct sockaddr *)&serverAddress,sizeof(serverAddress)) == -1)
    {
        #ifdef WINDOWS_7 //XP
            int errorCode = 0;
            string errorMsg = "error calling connect():\n";
            detectErrorConnect(&errorCode,errorMsg);
            myException socketConnectException(errorCode,errorMsg);
            throw socketConnectException;
        #endif

        #ifdef UNIX
            myException unixSocketConnectException(0,"unix: error calling connect()");
            throw unixSocketConnectException;
        #endif
    }
}
catch(myException& excp)
{
    excp.response();
    exit(1);
}
}

Answer 1

Just use the same socket FD in both places. You don't even have to synchronize when using it.