Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
217 views
in Technique[技术] by (71.8m points)

c# - Why does BeginReceive() not return for more than one read?

In the code below, I make a call from Main() to Receive(), which in turn calls the Async BeginReceive(), and completes receiving the data in a background thread.

The Problem: For the first read, BeginReceive is succesful and appends the StringBuilder. However, when called again, the if(bytesread>0) condition is never reached and thus I never act on the data received. I want BeginReceive to deal with more than one read, and (i think this is related with the threading) I would like for the Main() function to be always listening for new COMMANDS from the client (not new connections, I'd like to keep the same Socket). Is this even possible?

Attempts At Solution: I added the ManualResetEvent in an attempt to stop the Main() function from exiting prior to the Async reading going on in another thread.

Relevant Code in Main():

        Receive(server); //await instructions from the client
        done.WaitOne(); //This is a ManualResetEvent.
        Console.ReadLine();

Method Definitions:

        public static void Receive(Socket server)
    {
        try
        {
            SocketArgs sockargs = new SocketArgs();
            sockargs.handler = server;


             server.BeginReceive(sockargs.buffer, 0, sockargs.buffersize, 0, new AsyncCallback(ReceiveCallBack), sockargs);

        }
        catch
        {

        }
    }
    public static void ReceiveCallBack(IAsyncResult ia)
    {
        try
        {
            SocketArgs sockargs = (SocketArgs)ia.AsyncState;
            Socket server = sockargs.handler;
            int BytesRead = server.EndReceive(ia);
            if (BytesRead > 0)
            {
                //Continue reading data.
                sockargs.sb.Append(Encoding.ASCII.GetString(sockargs.buffer, 0, BytesRead));
                MessageBox.Show(sockargs.sb.ToString());
                server.BeginReceive(sockargs.buffer, 0, sockargs.buffersize, 0, new AsyncCallback(ReceiveCallBack), sockargs);
            }
            else
            { //Do stuff with sb.ToString()



                done.Set();
            }
        }
        catch(Exception e)
        {
            MessageBox.Show(e.ToString());
        }
    }
See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

Reset the event so that WaitOne blocks again. As per the comments the event is erroneously left in a set state causing Main to exit.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

1.4m articles

1.4m replys

5 comments

57.0k users

...