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Passing a cancellation token to an IAsyncEnumerable

I talked about the concept of asynchronous streams before. Thanks to the introduction of the IAsyncEnumerable interface, it allowed us to combine the richness of LINQ with the readibility of async-await to asynchronously access databases, microservices and remote APIs.

As enumerating async streams will typically result in remote asynchronous operations it can take a while to complete. I was wondering how we could cancel these async operations?

To support this use case, IAsyncEnumerable has an extension method ‘WithCancellation()’. The CancellationToken will be passed on to the  IAsyncEnumerable.GetEnumerator method.

More information about what’s happening behind the scenes can be found here.

Remark: There are some further improvements on the way in ASP.NET Core 6 regarding consuming IAsyncEnumerable streams as mentioned in this post: https://www.tpeczek.com/2021/07/aspnet-core-6-and-iasyncenumerable.html.

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