public static ValueTask <IAsyncDisposable> Timer(IAsyncObserver <long> observer, DateTimeOffset dueTime, TimeSpan period, IAsyncScheduler scheduler)
{
if (period < TimeSpan.Zero)
{
throw new ArgumentOutOfRangeException(nameof(period));
}
if (scheduler == null)
{
throw new ArgumentNullException(nameof(scheduler));
}
var tick = 0L;
return(scheduler.ScheduleAsync(async ct =>
{
if (ct.IsCancellationRequested)
{
return;
}
// TODO: Compensate for drift by adding stopwatch functionality.
do
{
await observer.OnNextAsync(tick++).RendezVous(scheduler, ct);
await scheduler.Delay(period, ct).RendezVous(scheduler, ct);
} while (!ct.IsCancellationRequested);
}, dueTime));
}
public static IAsyncObservable <int> ProduceSlowly(this IAsyncScheduler scheduler, params TimeSpan[] delays)
{
return(AsyncObservable.Range(0, delays.Length)
.Select(async(i, ca) =>
{
await scheduler.Delay(delays[i], ca).ConfigureAwait(false);
return i;
}));
}
public static Task <IAsyncDisposable> Generate <TState, TResult>(IAsyncObserver <TResult> observer, TState initialState, Func <TState, Task <bool> > condition, Func <TState, Task <TState> > iterate, Func <TState, Task <TResult> > resultSelector, Func <TState, Task <DateTimeOffset> > timeSelector, IAsyncScheduler scheduler)
{
if (observer == null)
{
throw new ArgumentNullException(nameof(observer));
}
if (condition == null)
{
throw new ArgumentNullException(nameof(condition));
}
if (iterate == null)
{
throw new ArgumentNullException(nameof(iterate));
}
if (resultSelector == null)
{
throw new ArgumentNullException(nameof(resultSelector));
}
if (timeSelector == null)
{
throw new ArgumentNullException(nameof(timeSelector));
}
if (scheduler == null)
{
throw new ArgumentNullException(nameof(scheduler));
}
return(scheduler.ScheduleAsync(async ct =>
{
var first = true;
var state = initialState;
while (!ct.IsCancellationRequested)
{
var hasResult = false;
var result = default(TResult);
var nextDue = default(DateTimeOffset);
try
{
if (first)
{
first = false;
}
else
{
state = await iterate(state).RendezVous(scheduler, ct);
}
hasResult = await condition(state).RendezVous(scheduler, ct);
if (hasResult)
{
result = await resultSelector(state).RendezVous(scheduler, ct);
nextDue = await timeSelector(state).RendezVous(scheduler, ct);
}
}
catch (Exception ex)
{
await observer.OnErrorAsync(ex).RendezVous(scheduler, ct);
return;
}
if (hasResult)
{
await observer.OnNextAsync(result).RendezVous(scheduler, ct);
}
else
{
break;
}
await scheduler.Delay(nextDue).RendezVous(scheduler, ct);
}
if (!ct.IsCancellationRequested)
{
await observer.OnCompletedAsync().RendezVous(scheduler, ct);
}
}));
}
