In computer science terms, a Task is a future or a promise. (Some people use those two terms synonymously, some use them differently, nobody can agree on a precise definition.) Basically, a Task<T> “promises” to return you a T, but not right now honey, I’m kinda busy, why don’t you come back later? A Thread … Read more
Your method doesn’t have any callbacks so there is no reason to use .CallBack(). You can simply return a Task with the desired values using .Returns() and Task.FromResult, e.g.: MyType someValue=…; mock.Setup(arg=>arg.DoSomethingAsync()) .Returns(Task.FromResult(someValue)); Update 2014-06-22 Moq 4.2 has two new extension methods to assist with this. mock.Setup(arg=>arg.DoSomethingAsync()) .ReturnsAsync(someValue); mock.Setup(arg=>arg.DoSomethingAsync()) .ThrowsAsync(new InvalidOperationException()); Update 2016-05-05 As Seth … Read more
If you want to get the exception “asynchronously”, you could do: MyAsyncMethod(). ContinueWith(t => Console.WriteLine(t.Exception), TaskContinuationOptions.OnlyOnFaulted); This will allow you to deal with an exception on a thread other than the “main” thread. This means you don’t have to “wait” for the call to MyAsyncMethod() from the thread that calls MyAsyncMethod; but, still allows you … Read more
Task.WaitAll blocks the current thread until everything has completed. Task.WhenAll returns a task which represents the action of waiting until everything has completed. That means that from an async method, you can use: await Task.WhenAll(tasks); … which means your method will continue when everything’s completed, but you won’t tie up a thread to just hang … Read more
How about this: int timeout = 1000; var task = SomeOperationAsync(); if (await Task.WhenAny(task, Task.Delay(timeout)) == task) { // task completed within timeout } else { // timeout logic } And here’s a great blog post “Crafting a Task.TimeoutAfter Method” (from MS Parallel Library team) with more info on this sort of thing. Addition: at … Read more
int[] ids = new[] { 1, 2, 3, 4, 5 }; Parallel.ForEach(ids, i => DoSomething(1, i, blogClient).Wait()); Although you run the operations in parallel with the above code, this code blocks each thread that each operation runs on. For example, if the network call takes 2 seconds, each thread hangs for 2 seconds w/o doing … Read more
Today, I would recommend using Task.CompletedTask to accomplish this. Pre .net 4.6: Using Task.FromResult(0) or Task.FromResult<object>(null) will incur less overhead than creating a Task with a no-op expression. When creating a Task with a result pre-determined, there is no scheduling overhead involved.
Use Thread.Sleep when you want to block the current thread. Use Task.Delay when you want a logical delay without blocking the current thread. Efficiency should not be a paramount concern with these methods. Their primary real-world use is as retry timers for I/O operations, which are on the order of seconds rather than milliseconds.
Update: ASP.NET Core does not have a SynchronizationContext. If you are on ASP.NET Core, it does not matter whether you use ConfigureAwait(false) or not. For ASP.NET “Full” or “Classic” or whatever, the rest of this answer still applies. Original post (for non-Core ASP.NET): This video by the ASP.NET team has the best information on using … Read more