cancellation-token

When I create a default CancellationToken I can see in the debugger that the CancellationToken has a CancellationTokenSource associated with it which is stored in the private m_source field: I am wondering how can that be as for structs the default keyword "will return each member of the struct initialized to zero or null depending on whether they are value or reference types" and CancellationTokenSource is a reference type. CancellationToken does have 2 constructors that set this field however they are irrelevant as default(CancellationToken) doesn't call constructors and new

Looking at the implementation of CancellationToken.None , it is simply returning default(CancellationToken) . However, I see no reference in CancellationToken 's documentation that the two are equivalent. I'd like to offer an API like this but not until I'm sure it'll always work: Task DoSomething(CancellationToken token = default(CancellationToken)) Is it defined behavior that default(CancellationToken) is the same as CancellationToken.None , or is this just an implementation detail? After filing an issue with corefx, the documentation remarks have been updated to make this a guaranteed

There are some people on my team who really love coding with async Task . And sometimes they like to use CancellationToken parameters. What I'm unsure about is whether we should as a team be using this style of code (A): async Task<someObject> DoStuff(CancellationToken t) { while (!t.IsCanceled) { try { Task.Delay(5000, t); } catch (AggregateException e) // or is it TaskCanceledException or OperationCanceledException? I don't know? :) { } // poll something, return someObject, or null } return null; } This obviously means the caller probably has to check the cancellation token themselves to

Here is a sample code that creates a new task that simulates a long running process.There is nothing much on the task as such and purely focuses on the cancelling features.I am using cancellation token to cancel the task and the code works fine for me. CancellationTokenSource CTS= new CancellationTokenSource(); Task<Boolean> PTask = new Task<Boolean>(() => { while (true) { if (!CTS.Token.IsCancellationRequested) { Thread.Sleep(5000); } else{Console.WriteLine("Thread Cancelled");break;} } return true; }, CTS.Token, TaskCreationOptions.None); PTask.Start(); Console.WriteLine("Hit Enter to cancel

I have some async code that I would like to add a CancellationToken to. However, there are many implementations where this is not needed so I would like to have a default parameter - perhaps CancellationToken.None. However, Task<x> DoStuff(...., CancellationToken ct = null) yields A value of type '' cannot be used as a default parameter because there are no standard conversions to type 'System.Threading.CancellationToken' and Task<x> DoStuff(...., CancellationToken ct = CancellationToken.None) Default parameter value for 'ct' must be a compile-time constant Is there any way to have a default

I am trying learn how to cancel Task using cancellation token. Here, I have written a UnitTest for it but I am not getting the way it is working. [TestMethod] public async Task Task_should_not_run_when_token_cancelled_before_its_call() { var cts = new CancellationTokenSource(); var token = cts.Token; cts.Cancel(); Debug.WriteLine("Calling Cancellable Method".ToUpper()); try { await CheckMeCalled(token); } catch (Exception expException) { } } private async Task CheckMeCalled(CancellationToken ct) { Debug.WriteLine("Before task delayed".ToUpper()); await Task.Delay(5000); Debug.WriteLine("After