如何在 c# function 中设置超时？

Question

I've recently created a function into my c# program which exectuses some queries and other stuff, and I was wondering if there exists a way to set a timeout for that function: in particlar I'd like my program to be able to stop if the function hasn't been completely executed after 10 minutes. I would also like to know if it is possible to implement this control inside the function itself, so as not to write it every time I call it.

Answer 1

The best way is to let the method take a cancellationToken . It needs to check this token frequently and abort if it has been cancelled. Create a token that cancels after some timeout by creating a cancellationTokenSource: new CancellationTokenSource(timeout) and handing the token it owns to the function. For long running methods it would be good practice to take a cancellation token and some way to report progress.

If there is no way to modify the function an alternative might be something like this:

    public async Task<(T Result, bool Completed)> RunTimeoutFunction<T>(Func<T> func, TimeSpan timeout)
    {
        var funcTask = Task.Run(func);
        var timeoutTask = Task.Delay(timeout);
        var completedTask = await Task.WhenAny(funcTask, timeoutTask);
        if (completedTask == timeoutTask)
        {
            return (default, false);
        }

        return (funcTask.Result, true);
    }

The obvious downside is that the function will continue to run in the background even after the timeout. This is however kind of unavoidable unless the function can be cancelled cooperatively. A third alternative would be to put the function in a separate process, then you can safely kill the process after the timeout.