/// <summary>
/// Runs catchup batches repeatedly with a specified interval after each batch.
/// </summary>
/// <typeparam name="TData">The type of the stream's data.</typeparam>
/// <typeparam name="TCursor">The type of the cursor.</typeparam>
/// <param name="catchup">The catchup.</param>
/// <param name="pollInterval">The amount of time to wait after each batch is processed.</param>
/// <returns>A disposable that, when disposed, stops the polling.</returns>
public static IDisposable Poll <TData, TCursor>(
this IStreamCatchup <TData, TCursor> catchup,
TimeSpan pollInterval)
{
var canceled = false;
Task.Run(async() =>
{
while (!canceled)
{
await catchup.RunSingleBatch();
await Task.Delay(pollInterval);
}
});
return(Disposable.Create(() => { canceled = true; }));
}
/// <summary>
/// Runs the catchup query until it reaches an empty batch, then stops.
/// </summary>
public static async Task <ICursor <TCursor> > RunUntilCaughtUp <TData, TCursor>(this IStreamCatchup <TData, TCursor> catchup)
{
ICursor <TCursor> cursor;
var counter = new Counter <TData>();
using (catchup.Subscribe(async(_, batch) => counter.Count(batch), NoCursor(counter)))
{
int countBefore;
do
{
countBefore = counter.Value;
cursor = await catchup.RunSingleBatch();
} while (countBefore != counter.Value);
}
return(cursor);
}
/// <summary>
/// Consumes a single batch from the source stream and updates the subscribed aggregators.
/// </summary>
/// <returns>
/// The updated cursor position after the batch is consumed.
/// </returns>
public override async Task <ICursor <TUpstreamCursor> > RunSingleBatch()
{
return(await upstreamCatchup.RunSingleBatch());
}
