Question

I haven’t really played with asyn operations before or multiple threads so this is all new to me. So I was hoping for some guidance

Suppose I have a class something like below

public class pinger
{


    // Constructor
    public Pinger()
    {
     do while exit = False;
    Uri url = new Uri("www.abhisheksur.com");
        string pingurl = string.Format("{0}", url.Host);
        string host = pingurl;
        bool result = false;
        Ping p = new Ping();
        try
        {
            PingReply reply = p.Send(host, 3000);
            if (reply.Status == IPStatus.Success)
                result = true;
        }
        catch { }
      //wait 2 seconds
      loop;
    }


}

so I can call this with

Pinger firstone = new Pinger

What I want if for control to then return to the main thread leaving the created instance running and pinging the host every two seconds and updating the result variable, that I can then use a get property when I want to know the status from the main thread.

Can any one suggest some good reading / examples to introduce me to multi threading in c#, using Ping as an example seemed a good easy thing to try this out with 🙂

Cheers

Aaron

Answer 1

I can outline how the class should look 🙂

public class pinger
{
    private Uri m_theUri;
    private Thread m_pingThread;
    private ManualResetEvent m_pingThreadShouldStop;

    private volatile bool m_lastPingResult = false;

    public Pinger(Uri theUri)
    {
        m_theUri = theUri;
    }


    public void Start()
    {
        if (m_pingThread == null)
        {
            m_pingThreadShouldStop = new ManualResetEvent(false);
            m_pingThread = new Thread(new ParameterizedThreadStart(DoPing));
            m_pingThread.Start(m_theUri);
        }
    }

    public void Stop()
    {
        if (m_pingThread !=  null)
        {
            m_pingThreadShouldStop.Set();
            m_pingThread.Join();

            m_pingThreadShouldStop.Close();
        }
    }


    public void DoPing(object state)
    {
        Uri myUri = state as Uri;
        while (!m_pingThreadShouldStop.WaitOne(50))
        {
            // Get the result for the ping
            ...

            // Set the property
            m_lastPingResult = pingResult;
        }
    }


    public bool LastPingResult
    {
        get { return m_lastPingResult; }
    }
}

What does it do? It is a new class with a Start and a Stop method. Start starts the ping, Stop stops the ping.

Pinging is done in a separate thread and with every ping, the result property is updated.