/// <summary>
/// Schedules a periodic piece of work on the dispatcher, using a <see cref="Windows.Threading.DispatcherTimer"/> object.
/// </summary>
/// <typeparam name="TState">The type of the state passed to the scheduled action.</typeparam>
/// <param name="state">Initial state passed to the action upon the first iteration.</param>
/// <param name="period">Period for running the work periodically.</param>
/// <param name="action">Action to be executed, potentially updating the state.</param>
/// <returns>The disposable object used to cancel the scheduled recurring action (best effort).</returns>
/// <exception cref="ArgumentNullException"><paramref name="action"/> is <c>null</c>.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="period"/> is less than <see cref="TimeSpan.Zero"/>.</exception>
public IDisposable SchedulePeriodic <TState>(TState state, TimeSpan period, Func <TState, TState> action)
{
if (period < TimeSpan.Zero)
{
throw new ArgumentOutOfRangeException(nameof(period));
}
if (action == null)
{
throw new ArgumentNullException(nameof(action));
}
var timer = new Windows.Threading.DispatcherTimer(Priority, Dispatcher);
var state1 = state;
timer.Tick += (s, e) =>
{
state1 = action(state1);
};
timer.Interval = period;
timer.Start();
return(Disposable.Create(() =>
{
var t = Interlocked.Exchange(ref timer, null);
if (t != null)
{
t.Stop();
action = _ => _;
}
}));
}
private IDisposable ScheduleSlow <TState>(TState state, TimeSpan dueTime, Func <IScheduler, TState, IDisposable> action)
{
var d = new MultipleAssignmentDisposable();
var timer = new Windows.Threading.DispatcherTimer(Priority, Dispatcher);
timer.Tick += (s, e) =>
{
var t = Interlocked.Exchange(ref timer, null);
if (t != null)
{
try
{
d.Disposable = action(this, state);
}
finally
{
t.Stop();
action = null;
}
}
};
timer.Interval = dueTime;
timer.Start();
d.Disposable = Disposable.Create(() =>
{
var t = Interlocked.Exchange(ref timer, null);
if (t != null)
{
t.Stop();
action = (_, __) => Disposable.Empty;
}
});
return(d);
}