WebSocket4Net Extensions: OpenAsync

I recently talked about .NET WebSocket Libraries, and how I like using WebSocket4Net as a .NET WebSocket client. That library is great, but really wanted it to have two additional features:

1. Retry logic for opening a connection.
2. An OpenAsync method.

...so I created an extension method that does both!

WebSocket4Net Extensions

public static class WebSocketExtensions

{

    public static async Task OpenAsync(

        this WebSocket webSocket,

        int retryCount = 5,

        CancellationToken cancelToken = default(CancellationToken))

    {

        var failCount = 0;

        var exceptions = new List<Exception>(retryCount);

        var openCompletionSource = new TaskCompletionSource<bool>();

        cancelToken.Register(() => openCompletionSource.TrySetCanceled());

        EventHandler openHandler = (s, e) => openCompletionSource.TrySetResult(true);

        EventHandler<ErrorEventArgs> errorHandler = (s, e) =>

        {

            if (exceptions.All(ex => ex.Message != e.Exception.Message))

            {

                exceptions.Add(e.Exception);

            }

        };

        EventHandler closeHandler = (s, e) =>

        {

            if (cancelToken.IsCancellationRequested)

            {

                openCompletionSource.TrySetCanceled();

            }

            else if (++failCount < retryCount)

            {

                webSocket.Open();

            }

            else

            {

                var exception = exceptions.Count == 1

                    ? exceptions.Single()

                    : new AggregateException(exceptions);

                var webSocketException = new WebSocketException(

                    "Unable to connect", 

                    exception);

                openCompletionSource.TrySetException(webSocketException);

            }

        };

        try

        {

            webSocket.Opened += openHandler;

            webSocket.Error += errorHandler;

            webSocket.Closed += closeHandler;

            webSocket.Open();

            await openCompletionSource.Task.ConfigureAwait(false);

        }

        finally

        {

            webSocket.Opened -= openHandler;

            webSocket.Error -= errorHandler;

            webSocket.Closed -= closeHandler;

        }

    }

Enjoy,
Tom