NotSupportedException: 'Cancellation of stream writes is not supported by this gRPC implementation.'

Grpc.Net 2.46.0, Grpc.Core 2.46.1

Is your feature request related to a problem? Please describe.

As an API user, i want to know if IAsyncStreamWriter supports WriteAsync(message, CancellationToken). I don’t want to guess or to catch NotSupportedException thrown by the default implementation.

Describe the solution you’d like

change the default implementation, remove NotSupportedException:

public interface IAsyncStreamWriter<T>
{
    Task WriteAsync(T message, CancellationToken cancellationToken) => WriteAsync(message);
}

Describe alternatives you’ve considered

add indicator whether the current AsyncStreamWriter supports WriteAsync(message, CancellationToken)

public interface IAsyncStreamWriter<T>
{
    bool CanCancelWriteAsync => false; // default false;

    Task WriteAsync(T message, CancellationToken cancellationToken)
    {
        if (cancellationToken.CanBeCanceled && !CanCancelWriteAsync)
        {
            throw new NotSupportedException("Cancellation of stream writes is not supported by this gRPC implementation.");
        }

        return WriteAsync(message);
    }
}

Additional context

Few examples of WriteAsync in context of Grpc.Net and Grpc.Core WriteAsyncChallenge.zip.

[Falco20019]

This sadly also did bite us… ReSharper is creating warnings that there is a variant with cancellation token support. Our users just applied it (as it’s usually useful) and found out later that this is throwing an exception. So I’m also not too happy with the solution. In my opinion, the macro checking for #if NETSTANDARD2_1_OR_GREATER is misleading.

[JamesNK]

Thank you for your feedback. We’re closing this issue as the behavior discussed is by design.