CancellationToken UnRegister Action
CancellationToken.Register returns a CancellationTokenRegistration instance. If you call Dispose on that instance, your registration will be removed.
async-ctp
Why does the async keyword exist
It was introduced mainly to avoid backward compatibility issues. If the async-ness of a method must be inferred by the compiler (that would be through the detection of await keywords), then there are subtle scenarios where existing code would suddenly be treated differently, notably when you have identifiers (variable or function names called await). A … Read more
Why use async requests instead of using a larger threadpool?
This is a very good question, and understanding it is key to understand why asynchronous IO is so important. The reason why the new async/await feature has been added to C# 5.0 is to simplify writing asynchronous code. Support for asynchronous processing on the server is not new however, it exists since ASP.NET 2.0. Like … Read more
can not await async lambda
In your lambda example, when you call task.Wait(), you are waiting on the new Task that you constructed, not the delay Task that it returns. To get your desired delay, you would need to also wait on the resulting Task: Task<Task> task = new Task<Task>(async () => { await Task.Delay(1000); }); task.Start(); task.Wait(); task.Result.Wait(); You … Read more
Task does not contain a definition for ‘GetAwaiter’
I had this issue in one of my projects, where I found that I had set my project’s .Net Framework version to 4.0 and async tasks are only supported in .Net Framework 4.5 onwards. I simply changed my project settings to use .Net Framework 4.5 or above and it worked.
Using async-await on .net 4
Microsoft released the Async Targeting Pack (Microsoft.Bcl.Async) through Nuget as a replacement for the AsyncCTP. You can read more about it here: http://blogs.msdn.com/b/bclteam/archive/2013/04/17/microsoft-bcl-async-is-now-stable.aspx. You can read about the previous version here: http://blogs.msdn.com/b/lucian/archive/2012/04/24/async-targeting-pack.aspx. As this pack is officially supported, I now believe the best option for targeting XP + async would be using Visual Studio 2012 … Read more
What’s the difference between returning void and returning a Task?
SLaks and Killercam’s answers are good; I thought I’d just add a bit more context. Your first question is essentially about what methods can be marked async. A method marked as async can return void, Task or Task<T>. What are the differences between them? A Task<T> returning async method can be awaited, and when the … Read more
How to call an async method from a getter or setter?
There is no technical reason that async properties are not allowed in C#. It was a purposeful design decision, because “asynchronous properties” is an oxymoron. Properties should return current values; they should not be kicking off background operations. Usually, when someone wants an “asynchronous property”, what they really want is one of these: An asynchronous … Read more