Reliable Actor timers are modelled on timers available in the system.Timers namespace. The timers are usually used to carry out routine operations in the lifetime of an Actor, for example processing input data at a certain rate. You can declare and register a timer in your application using the following code, usually in the OnActivateAsync method:

private IActorTimer _updateTimer; 
protected override Task OnActivateAsync() 
    { 
        ... 

         _updateTimer = RegisterTimer( 
            CallBackMethod,                     // Callback method 
            ObjectParameter,                   // Parameter to pass to 
                                                  the callback method 
            TimeSpan.FromMilliseconds(15),  // Amount of time to delay 
                                               before the callback is 
                                               invoked 
            TimeSpan.FromMilliseconds(15)); // Time interval between 
                                               invocations of the 
                                               callback method 

        return base.OnActivateAsync(); 
    } 

The CallBack method is simply a function that accepts the parameter that you passed while declaring the timer:

    private Task CallBackMethod(object state) 
    { 
        ... 
        return Task.FromResult(true); 
    } 

Finally, you can unregister a timer using the UnregisterTimer method:

protected override Task OnDeactivateAsync() 
    { 
        if (_updateTimer != null) 
        { 
            UnregisterTimer(_updateTimer); 
        }  
        return base.OnDeactivateAsync(); 
    } 

Because of the turn wise concurrency feature of Reliable Actors, no two concurrent executions of the callback method will take place at any time. The time will be stopped while the callback is executing and will be restarted when it has completed.

It is important to note that if the Actor doesn't receive external invocations, it will be deactivated and garbage collected after a period of time. When this happens, the timers won't be activated any more. Therefore, it is important that you register the timer again in the OnActivateAsync method when the Actor is reactivated.