Having a problem with some socket code
From: Tony Caduto (acaduto_at_amsoftwaredesign.com)
Date: 08/19/04
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Date: Wed, 18 Aug 2004 22:34:18 -0500
Hi,
I am developing a socket server in C# and I want it to be blocking.
Anyway I have it working with threads, as each client connects the socket
spawned from the accept method is sent to a client thread.
In each thread I have a loop like below:
the data_available method is a wrapper around Socket.Poll() so I can use it
in miliseconds instead of micro.
Basicly I read a command via a streamreader and that all works, then
depending on the command I may go into a recieve or send variable length
data method that calls recieve directly to get the size of the data in the
first 4 bytes, then read the rest.
This all works great if I don't use the Poll method to prevent the blocking
read. I don't want it to block on readline because I have other things I
want to do in the loop. I picked up the recievevardata method from Richard
Blum's book C# network programming. Good book by the way :-)
It almost seems like the readline method is causing a timing issue because
if I put a sleep(500) on the client between commands it works with the Poll
(data_available wrapper method)
public void connection_loop()
{
while(true)
{
if (fclientsock.data_available(1000) )
{
try
{
command = sr.ReadLine();
process_command(command);
if (command==null)
break;
}
catch(IOException e)
{
Console.WriteLine("IO ERROR: "+e.Message);
break;
}
finally
{
//ensure all data in the buffer is sent
with the poll method the following function fails to get the correct size in
the first 4 bytes. I need a function like this to be compatible with Indy's
sendstream method which works exactly the same. (Indy is a Borland Delphi
socket library)
public byte[] recievevardata(bool indycompatible)
{
int total = 0;
int recv;
byte[] datasize = new byte[4];
recv = fsocket.Receive(datasize,0,4,0);
int size = BitConverter.ToInt32(datasize,0);
//needed for compatiblility with Indy's writestream method
if(indycompatible)
size = IPAddress.NetworkToHostOrder(size);
int dataleft = size;
byte[] data = new byte[size];
while(total < size)
{
recv = fsocket.Receive(data,total,dataleft,0);
if (recv==0) //disconnect occured while in transfer
{
data = Encoding.ASCII.GetBytes("exit ");
break;
}
total += recv;
dataleft -= recv;
Thread.Sleep(0); //don't hog the cpu
}
return data;
}
}
}
-- Tony Caduto Inexpensive Corporate Messaging AM Software Design http://www.amsoftwaredesign.com
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