Keep track of used channels and close the connection on stop

[cjmurph]

TcpListener doesn't keep track of used channels and close them on stop. The result is that any established connection continues to be served even after the listener is stopped.
One example is using Griffin.WebServer.HttpServer to serve a web page. If the HttpServer is stopped, the connection remains, until the client browser is stopped.

[jgauffin]

Thank you again :)

A question about the stop method:

Shouldn't you await the channels when they are stopping since the listener.Stop() method is synchronous? Something like:

var tasks = _usedChannels.Values.Select(x => x.CloseAsync()).ToList();
if (tasks.Any())
    Task.WaitAll(tasks);

once the _usedChannels are closed, empty the list in case of the listener being restarted:

_usedChannels.Clear();

[cjmurph]

The channels are removed from the dictionary when the channel disconnect event fires. This event fires when you stop the channel so the following is executed.

ITcpChannel removed;
_usedChannels.TryRemove(source.ChannelId, out removed);

In my testing this appears to work well.

[jgauffin]

that's true. so that part is OK.

Wait for the channels in Stop() before returning.

[cjmurph]

OK, it's your framework, but I think it would be better to not block the stop method. Maybe return and fire a stopped event when the tasks finish, maybe even throw a stopping event first. thoughts?

[jgauffin]

If the method had been named InitiateShutdown(), BeginStop() or similar I would have agreed. But the contract says "Stop", thus anyone looking at that method would expect it to completely stop which also includes all channels stopping. I should have done that from the start and I'm glad that you pointed it out.

What you can do is to add the behavior as I suggested to the Stop() method, but also introduce StopAsync() method which would return a Task and internally await all channels. Anyone wanting to just signal stop and then move on can then use that method.

[cjmurph]

agreed, how about I block the stop method and if you choose you can merge the pull request and create the asynchronous version to your liking?

[jgauffin]

sure

[cjmurph]

There you go.
Thanks for the awesome web server by the way! It's a great way to serve up data without needing elevated privileges.

[jgauffin]

thank you.

[jgauffin]

I'm working on HTTP2. Will probably be included in Griffin.Framework sometimes during the summer.