Question

I have a design question. Is it better to define separate classes for SENDING and RECEIVING. Or, is it better to define a single Thread class? I like the idea of a single Thread class because it is easier to share a queue which can be locked by mutex.

Design Option #1 (Separate):

mySendThread = new SendThread(); // Have thread properties and separate members

myRcvThread = new RcvThread(); // Have thread properties and separate members

Design Option #2 (Master):

Master thread –

Execute() 
{
    if (threadType == RCV_THREAD)
    {
        globalVar = new MasterThread(serialPortHandle);
    }
    while (!Terminated)
    {
        if (threadType == RCV_THREAD)
        {
            if(globalVar) 
            {  
                // do work
            }
        }
        if (threadType == SND_THREAD)
        {
            tCountSnd = GetTickCount() / SND_THREAD_DELAY;
            if (tCountSnd != tCountSnd2) {
               tCountSnd2 = tCountSnd;
               if (globalVar) {
                   // do sending work
               }
            }
        }
     }
}

Answer 1

I’ve designed a thread for communicating on the serial port (in Python, not C++, but it doesn’t matter much) as follows:

There’s a single thread and two queues – one for sent and one for received messages. The thread always listens (asynchronously) on both the serial port (for received data) and the sending queue (to send stuff the application asks to send).

1. If data arrived on the serial port, it’s placed in the receive queue for the application’s use
2. If the application placed data into the send queue, the thread sends it down the serial port

This design makes more sense to me because the single resource (the serial port) is held by a single thread, and not shared by two. Breaking it to several classes sounds like an overkill to me, since reading/writing from queues and reading/writing from the serial port is a trivial operation (naturally the serial port is wrapped in a convenient class – by the way I really recommend this class by Ramon De Klein)

Oh, and it works very well.