private Func <EventStoreCatchUpSubscription, ResolvedEvent, Task> EventAppeared(
ProjectionHandler projection,
string projectionName
) => async(_, e) =>
{
// check system event
if (e.OriginalEvent.EventType.StartsWith("$"))
{
return;
}
var @event = this._serializer.Deserialize(Type.GetType(e.Event.EventType), Encoding.UTF8.GetString(e.Event.Data));
if (@event == null)
{
throw new ArgumentNullException(nameof(@event));
}
await projection.Handle(@event);
await _checkpointStore.SetLastCheckpoint(projectionName, e.OriginalPosition);
var metadata = this._serializer.Deserialize <EventMetadata>(Encoding.UTF8.GetString(e.Event.Metadata));
ISnapshotter snapshotter = _snapshotters.FirstOrDefault(
x => x.ShouldTakeSnapshot(Type.GetType(metadata.AggregateAssemblyQualifiedName), e) && !metadata.IsSnapshot);
if (snapshotter != null)
{
await snapshotter.TakeSnapshot(e.OriginalStreamId);
}
};
private async Task StartProjection(ProjectionHandler projection)
{
var projectionTypeName = projection.GetType().FullName;
Position lastCheckpoint = await _checkpointStore.GetLastCheckpoint <Position>(projectionTypeName);
var settings = new CatchUpSubscriptionSettings(
_maxLiveQueueSize,
_readBatchSize,
false,
false,
projectionTypeName
);
_connection.SubscribeToAllFrom(
lastCheckpoint,
settings,
EventAppeared(projection, projectionTypeName),
LiveProcessingStarted(projection, projectionTypeName),
SubscriptionDropped(projection, projectionTypeName)
);
}
private Action <EventStoreCatchUpSubscription, SubscriptionDropReason, Exception> SubscriptionDropped(ProjectionHandler projection, string projectionName)
=> (subscription, reason, ex) =>
{
subscription.Stop();
switch (reason)
{
case SubscriptionDropReason.UserInitiated:
break;
case SubscriptionDropReason.SubscribingError:
case SubscriptionDropReason.ServerError:
case SubscriptionDropReason.ConnectionClosed:
case SubscriptionDropReason.CatchUpError:
case SubscriptionDropReason.ProcessingQueueOverflow:
case SubscriptionDropReason.EventHandlerException:
Task.Run(() => StartProjection(projection));
break;
default:
break;
}
};
private static Action <EventStoreCatchUpSubscription> LiveProcessingStarted(ProjectionHandler projection, string projectionName)
=> _ =>
{
};
