TcpListener and TcpClient (an easy-to-use example) – part 2
Back in 2005 I wrote a blogpost TcpListener and TcpClient (an easy-to-use example). It was really just a piece of code I wrote to quickly finish what I was doing and I put it on my blog. The code was throwaway code, but even after the years it’s still visited a lot on my blog.
Given the code was written 9 years ago, when my skills were 9 years younger and when the world around us was slightly different, different tools etc. I decided to give it a little facelift. Kind of 2014 edition.
class Program
{
public static void Main(string[] args)
{
MainAsync().Wait();
}
static async Task MainAsync()
{
Console.WriteLine("Starting...");
var server = new TcpListener(IPAddress.Parse("0.0.0.0"), 66);
server.Start();
Console.WriteLine("Started.");
while (true)
{
var client = await server.AcceptTcpClientAsync().ConfigureAwait(false);
var cw = new ClientWorking(client, true);
cw.DoSomethingWithClientAsync().NoWarning();
}
// :)
server.Stop();
}
}
class ClientWorking
{
TcpClient _client;
bool _ownsClient;
public ClientWorking(TcpClient client, bool ownsClient)
{
_client = client;
_ownsClient = ownsClient;
}
public async Task DoSomethingWithClientAsync()
{
try
{
using (var stream = _client.GetStream())
{
using (var sr = new StreamReader(stream))
using (var sw = new StreamWriter(stream))
{
await sw.WriteLineAsync("Hi. This is x2 TCP/IP easy-to-use server").ConfigureAwait(false);
await sw.FlushAsync().ConfigureAwait(false);
var data = default(string);
while (!((data = await sr.ReadLineAsync().ConfigureAwait(false)).Equals("exit", StringComparison.OrdinalIgnoreCase)))
{
await sw.WriteLineAsync(data).ConfigureAwait(false);
await sw.FlushAsync().ConfigureAwait(false);
}
}
}
}
finally
{
if (_ownsClient && _client != null)
{
(_client as IDisposable).Dispose();
_client = null;
}
}
}
}
static class TaskExtensions
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void NoWarning(this Task t) { }
}
It’s really nothing special. I just replaced the thread with asynchronous calls. Not that it was not available in 2005. But I had no idea that creating thread is a stupid waste of resources. And programming with APM was (and still is) touch bit harder that “normal” sequential code (that’s where the async/await comes handy). The rest is just some small cleanups and so on.
Maybe I’ll put a task for 2023 to write an – at that time current – version.
