Re: CSocket, best way to wait for a reply?

simon wrote: 
Hi,

I have a 'client' and a 'server', (both the same sub-classes of CSocket).
Basically the client sends a message to the server and in turn the server sends a message back to the client.
I allow a few seconds for the server to reply back to the client. Ideally it should not take more than a few milliseconds.
The client waits for it's reply, (recognized by a special header in the message).

So what I have is a function that does something like...

void MyMessage( void *pData, int nSize )
{
pMySocket->Send( pData, nSize );

//    wait for a reply from the server
while( pMySocket->pReplyBuffer == NULL ){
    sleep(0);    //    give time back to the queue
                    //    wait for a few seconds only
}

//     either timeout or no reply sent
}

//    The server then receives the message sent
//    sends a reply back to the client
//    who in turn fills the void *pReplyBuffer
//
//    once "pReplyBuffer" is no longer NULL I know that data has returned.

But I have 2 problems

1) As you can see the wait is totally inadequate. it hangs the system. So what would be the best way to wait for a few seconds?
What I am doing now is ::PeekMessage( &msg, 0, 0, PR_REMOVE), but I don't feel good handling ALL the messages that way.
PeekMessages only for socket ones does not seem to work and still causes the system to hang.

2) Sometimes the Send(..) -> (who then calls the SendChunk() function), simply hangs and waits forever for the PumpMessages(FD_WRITE) to return.
What could I be doing wrong.

Many thanks

Simon



You are trying to write procedural code in an event-driven environment using an event-driven socket class. After you send you should simply return to MFC. If desired, you can also disable some controls and use SetTimer to detect a timeout in the response. But you must keep the MFC message loop running normally so your application will not appear "hung."

After a while, the OnReceive function in your socket class will be called with the response.

--
Scott McPhillips [VC++ MVP]

.

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