Execute task on current thread

Question

Is it possible to force a task to execute synchronously, on the current thread?

That is, is it possible, by e.g. passing some parameter to StartNew(), to make this code:

Task.Factory.StartNew(() => ThisShouldBeExecutedSynchronously()); 

behave like this:

ThisShouldBeExecutedSynchronously(); 

Background:

I have an interface called IThreads:

public interface IThreads {     Task<TRet> StartNew<TRet>(Func<TRet> func); } 

I would like to have two implemenetations of this, one normal that uses threads:

public class Threads : IThreads {     public Task<TRet> StartNew<TRet>(Func<TRet> func)     {         return Task.Factory.StartNew(func);     } } 

And one that does not use threads (used in some testing scenarios):

public class NoThreading : IThreads {     public Task<TRet> StartNew<TRet>(Func<TRet> func)     {         // What do I write here?     } } 

I could let the NoThreading version just call func(), but I want to return an instance of Task<TRet> on which I can perform operations such as ContinueWith().

Answer 1

You can simply return the result of func() wrapped in a Task.

public class NoThreading : IThreads {     public Task<TRet> StartNew<TRet>(Func<TRet> func)     {         return Task.FromResult(func());     } } 

Now you can attach "continue with" tasks to this.

Answer 2

Task scheduler decides whether to run a task on a new thread or on the current thread. There is an option to force running it on a new thread, but none forcing it to run on the current thread.

But there is a method Task.RunSynchronously() which

Runs the Task synchronously on the current TaskScheduler.

More on MSDN.

Also if you are using async/await there is already a similar question on that.