CancellationToken

Context: CancellationToken is passed to asynchronous methods to allow cancellation. The method can check IsCancellationRequested or call ThrowIfCancellationRequested().

using System.Threading;
using System.Threading.Tasks;

public class Processor
{
    public async Task ProcessAsync(CancellationToken token)
    {
        for (int i = 0; i < 100; i++)
        {
            token.ThrowIfCancellationRequested();
            await Task.Delay(100, token);
        }
    }
}

Default token

Use CancellationToken.None when you have no token to pass.

await processor.ProcessAsync(CancellationToken.None);

Real-world usage example

EF Core queries: ToListAsync(cancellationToken) accepts a token to cancel the database query.

Example: EF Core cancellation

Related sections

• 9.7 Cancellation tokens
• 9.7.3 ThrowIfCancellationRequested