Question

Sometimes I create a method like this

Task<int> f()
{
    if (...) return Task.Factory.StartNew(() => 42); // in this case, result already known
    else ... // return some "real task"
}

But I was wondering if there is a way to create a task thas is already completed, so that I won’t incur any potential overhead of scheduling the “calculation” 42

Answer 1

Use TaskCompletionSource<T>:

TaskCompletionSource<int> tcs = new TaskCompletionSource<int>();
tcs.SetResult(42);
return tcs.Task;

(via MSDN)