Executing a function periodically after the function completes its task

Question

I am building a windows store app using C# and xaml. I need to refresh the data after certain interval of time (bring the new data from the server). I used ThreadPoolTimer t

Answer 1

I think an easier way to do this is with async:

private async Task PeriodicallyRefreshDataAsync(TimeSpan period)
{
  while (true)
  {
    n++; 
    Debug.WriteLine("hello" + n);
    await dp.RefreshAsync(); //Function to refresh the data
    bv.Text = "timer thread" + n;
    await Task.Delay(period);
  }
}

TimeSpan period = TimeSpan.FromMinutes(15); 
Task refreshTask = PeriodicallyRefreshDataAsync(period);

This solution also provides a Task which can be used to detect errors.

Answer 2

The AutoResetEvent will solve this problem. Declare a class-level AutoResetEvent instance.

AutoResetEvent _refreshWaiter = new AutoResetEvent(true);

Then inside your code: 1. wait on it till it is signaled, and 2. pass its reference as an argument to RefreshAsync method.

TimeSpan period = TimeSpan.FromMinutes(15); 
   ThreadPoolTimer PeriodicTimer =  ThreadPoolTimer.CreatePeriodicTimer(async(source)=> {  
   // 1. wait till signaled. execution will block here till _refreshWaiter.Set() is called.
   _refreshWaiter.WaitOne();
   n++; 
   Debug.WriteLine("hello" + n);
   // 2. pass _refreshWaiter reference as an argument
   await dp.RefreshAsync(_refreshWaiter); //Function to refresh the data
   await Dispatcher.RunAsync(CoreDispatcherPriority.High,
                () =>
                {
                    bv.Text = "timer thread" + n;

                });

        }, period);

Finally, at the end of dp.RefreshAsync method, call _refreshWaiter.Set(); so that if 15 seconds have passed then the next RefreshAsync may be called. Note that if RefreshAsync method takes less than 15 minutes, the execution proceeds as normal.