Timeout on Socket.Connect

[cincuranet]

Hi. What's the recommended approach nowadays when you want to have "connect timeout" aka timeout on Socket.Connect method. The "old" way was to use BeginConnect and AsyncWaitHandle.WaitOne with timeout. But maybe nowadays there's a better way.

[stephentoub]

You can pass a CancellationToken to Socket.ConnectAsync. That token can have cancellation requested manually or via a timer.

[cincuranet]

I don't see an overload for Socket.ConnectAsync with CancellationToken here.

[stephentoub]

All of the {Value}Task-based APIs on Socket are extension methods:
https://docs.microsoft.com/en-us/dotnet/api/system.net.sockets.sockettaskextensions.connectasync?view=net-5.0
(For .NET 6 they've been replicated as instance methods.)

[cincuranet]

Ah, great. I missed that reading just the documentation.

But what would be an equivalent blocking/synchronous code path scenario to match the Socket.Connect itself? Calling Wait or GetAwaiter.GetResult might not be the smartest move here.

[stephentoub]

If the connect is synchronous, then regardless of implementation something needs to trigger something from another thread in order to interrupt the connect. That could be using a timer to call Dispose on the Socket, for example. Or you could just block on the ConnectAsync.

[cincuranet]

OK. Thanks.

As a library writer, I'm sweetly looking at .NET 5 and SocketTaskExtensions.ConnectAsync, yet returning back to multi-targetting.