Built in background-scheduling system in .NET?

问题:

I ask though I doubt there is any such system.

Basically I need to schedule tasks to execute at some point in the future (usually no more than a few seconds or possibly minutes from now), and have some way of cancelling that request unless too late.

Ie. code that would look like this:

var x = Scheduler.Schedule(() => SomethingSomething(), TimeSpan.FromSeconds(5));
...
x.Dispose(); // cancels the request

Is there any such system in .NET? Is there anything in TPL that can help me?

I need to run such future-actions from various instances in a system here, and would rather avoid each such class instance to have its own thread and deal with this.

Also note that I don't want this (or similar, for instance through Tasks):

new Thread(new ThreadStart(() =>
{
    Thread.Sleep(5000);
    SomethingSomething();
})).Start();

There will potentially be a few such tasks to execute, they don't need to be executed in any particular order, except for close to their deadline, and it isn't vital that they have anything like a realtime performance concept. I just want to avoid spinning up a separate thread for each such action.

回答1:

Since you don't want to have external reference, you might want to have a look at System.Threading.Timer, or System.Timers.Timer. Note that those classes are technically very different from the WinForms Timer component.

回答2:

Use quartz.net (open source).

回答3:

Well.....Actually you can do exactly what you asked....

  IDisposable kill = null;

  kill = Scheduler.TaskPool.Schedule(() => DoSomething(), dueTime);

  kill.Dispose();

Using Rx the Reactive Framework from our buddies at Microsoft :)

Rx is quite amazing. I've all but replaced events with it. It is just plain yummy...

Hi I'm Rusty I'm an Rx addict...and I like it.

回答4:

While not explicitly built-in to .NET, have you considered writing EXEs that you can schedule via Windows Scheduled Tasks? If you're using .NET, you'll probably be using Windows, and isn't this exactly what Scheduled Tasks is for?

I'm not aware of how to integrate scheduled tasks into a .NET solution, but surely you could write components that get called from scheduled tasks.

回答5:

If you are willing ot use .NET 4, then the new System.Threading.Tasks provides a way to create custom schedulers for tasks. I haven't looked into it too closely, but it seems you could derive your own scheduler and let it run tasks as you see fit.

回答6:

In addition to the answers supplied, this can also be done with the threadpool:

public static RegisteredWaitHandle Schedule(Action action, TimeSpan dueTime)
{
    var handle = new ManualResetEvent(false);
    return ThreadPool.RegisterWaitForSingleObject(
                                         handle, 
                                         (s, t) =>
                                         {
                                             action();
                                             handle.Dispose();
                                         }, 
                                         null, 
                                         (int) dueTime.TotalMilliseconds, true);
}

The RegisteredWaitHandle has an Unregister method that can be used to cancel the request