/// <summary>
/// Subscribes the specified aggregator to a catchup.
/// </summary>
/// <typeparam name="TProjection">The type of the projection.</typeparam>
/// <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="aggregator">The aggregator.</param>
/// <returns>A disposable that, when disposed, unsubscribes the aggregator.</returns>
public static IDisposable Subscribe <TProjection, TData, TCursor>(
this IStreamCatchup <TData, TCursor> catchup,
IStreamAggregator <TProjection, TData> aggregator,
FetchAndSaveProjection <TProjection> manageProjection,
HandleAggregatorError <TProjection> onError = null)
{
return(catchup.SubscribeAggregator(aggregator, manageProjection, onError));
}
public static FetchAndSaveProjection <TProjection> Catch <TProjection>(
this FetchAndSaveProjection <TProjection> fetchAndSaveProjection,
HandleAggregatorError <TProjection> onError)
{
return(async(id, aggregate) =>
{
Exception innerException = null;
try
{
await fetchAndSaveProjection(id, async projection =>
{
var resultingProjection = default(TProjection);
try
{
resultingProjection = await aggregate(projection);
}
catch (Exception exception)
{
var error = CheckErrorHandler(onError, exception, projection);
if (!error.ShouldContinue)
{
throw;
}
innerException = exception;
return error.Projection;
}
return resultingProjection;
});
}
catch (Exception exception)
{
if (exception != innerException)
{
var error = CheckErrorHandler(onError, exception);
if (!error.ShouldContinue)
{
throw;
}
}
}
});
}
internal static StreamCatchupError <TProjection> CheckErrorHandler <TProjection>(
this HandleAggregatorError <TProjection> onError,
Exception exception,
TProjection projection = default(TProjection))
{
var error = new StreamCatchupError <TProjection>
{
Exception = exception,
Projection = projection
};
onError(error);
return(error);
}
public IDisposable SubscribeAggregator <TProjection>(
IStreamAggregator <TProjection, TData> aggregator,
FetchAndSaveProjection <TProjection> fetchAndSaveProjection,
HandleAggregatorError <TProjection> onError)
{
var added = aggregatorSubscriptions.TryAdd(typeof(TProjection),
new AggregatorSubscription <TProjection, TData>(aggregator,
fetchAndSaveProjection,
onError));
if (!added)
{
throw new InvalidOperationException(string.Format("Aggregator for projection of type {0} is already subscribed.", typeof(TProjection)));
}
return(Disposable.Create(() =>
{
IAggregatorSubscription _;
aggregatorSubscriptions.TryRemove(typeof(TProjection), out _);
}));
}
public AggregatorSubscription(
IStreamAggregator <TProjection, TData> aggregator,
FetchAndSaveProjection <TProjection> fetchAndSaveProjection = null,
HandleAggregatorError <TProjection> onError = null)
{
if (aggregator == null)
{
throw new ArgumentNullException("aggregator");
}
OnError = onError ?? (error => { });
if (onError != null)
{
fetchAndSaveProjection = fetchAndSaveProjection.Catch(onError);
}
FetchAndSaveProjection = fetchAndSaveProjection ??
(async(streamId, aggregate) =>
{
await aggregate(Activator.CreateInstance <TProjection>());
});
Aggregator = aggregator;
}
