Embedio: How to detect when server started listening?

[3da]

How to wait server started listening event?

Currently I do the following hack:

        _task = _server.RunAsync();

        while (!_server.Listener.IsListening)
        {
            await Task.Delay(500);
            if (_task.Exception != null)
                throw new Exception("Error listen server", _task.Exception);

        }

[geoperez]

We can probably add a state property, like Stopped, Loading, Running, Stopping... What do you think?

[3da]

In my case I need to detect when server is started listening or failed because port is busy.

So I made such trick:

    public async Task StartListen()
    {
        if (_task != null)
            throw new Exception("Server already started");
        _task = _server.RunAsync();

        while (!_server.Listener.IsListening)
        {
            await Task.Delay(500);
            if (_task.Exception != null)
                throw new Exception("Error listen server", _task.Exception);

        }
    }

In my opinion it would be better if WebServer had method Task WaitForListen()

[3da]

Another idea is WebServer should have event which signals about started listening.
Then it will be possible for trick similar to https://stackoverflow.com/a/19104345

[geoperez]

I like the idea of events, probably a single event StateChanged. What do you think?

[3da]

I like the idea of events, probably a single event StateChanged. What do you think?

Yeah, fine. This will solve the problem of detecting when this happened.

[geoperez]

I created a new branch for this issue: Issue257-WebServerEvent

[geoperez]

@3da I pushed some changes:

https://github.com/unosquare/embedio/commit/ba820e4ca8857c9c024529e792e5f2e230796d03

What do you think?

[3da]

What do you think?

Term "Running" is not clear. But "Listening" has only one meaning for everybody in my opinion.
How do you think?

[geoperez]

Makes sense. I'll change it.

[geoperez]

Done!

[3da]

Thanks!

[geoperez]

I'll release this version probably tomorrow.

[geoperez]

I just published the new Nuget v2.5.0. Can I close this issue?

[3da]

Hi.

Looks like there is not enough something.

I started 3 servers on port 666 in the same time.
First all of them sent me State = Loading. Then one of them sent me State = Listening.
2 other servers have not sent any event.

So again I can't detect when 2 other servers failed to start listening.
I am sorry, probably I didn't explain my problem clearly.

[3da]

So currently the only way to detect error when starting listening is to check Exception on Task.

[3da]

Okay, I got it.

    public async Task StartListen()
    {
        if (_task != null)
            throw new Exception("Server already started");

        var tcs = new TaskCompletionSource<object>();

        _server.StateChanged += (sender, e) =>
        {
            if (e.NewState == WebServerState.Listening)
                tcs.SetResult(null);
        };

        _task = _server.RunAsync();

        await await Task.WhenAny(tcs.Task, _task);
    }

But it works only if I add event handler before _server.RunAsync(). And this is logically.