public override async Task OnActivateAsync()
{
// set current grain key as aggregateName
var nameSplit = GrainReference.GetPrimaryKeyString().Split(':');
var rootAggregateName = nameSplit[0];
_aggregateName = nameSplit[1];
// set metric names
_underPressureMetricName = $"StreamDispatcher.{_aggregateName}.UnderPressure";
_queueSizeMetricName = $"StreamDispatcher.{_aggregateName}.QueueSize";
// get IAggregateStreamSettings instance from service collection filtered by grainKey
var aggregateStreamSettings = ServiceProvider.GetServices <IAggregateStreamSettings>().FirstOrDefault(g => g.AggregateName == rootAggregateName);
// throw if not able to get StreamSettings
if (aggregateStreamSettings == null)
{
throw new InvalidOperationException($"unable to retrieve IAggregateStreamSettings for {nameSplit[0]}");
}
// store grain resolver
if (!aggregateStreamSettings.EventDispatcherSettingsMap.TryGetValue(_aggregateName, out _eventDispatcherSettings))
{
throw new InvalidOperationException($"unable to retrieve EventDispatcherSettings for {_aggregateName}");
}
if (_eventDispatcherSettings.PersistDispatcherState)
{
// call base OnActivateAsync
await base.OnActivateAsync();
// set LastNotifiedEventVersion if needed
if (State.LastNotifiedEventId == 0)
{
// get last event from db
var lastEvent = await EventSource.GetLastAggregateEvent(rootAggregateName);
// get LastNotifiedEventVersion as latest aggregate version from db or 0
await ApplyEvent(new UpdatedLastNotifiedEventId { LastNotifiedEventId = lastEvent?.Id ?? 0 });
// sync up lastQueuedEventId and LastNotifiedEventId
_lastQueuedEventId = State.LastNotifiedEventId;
}
// sync up lastQueuedEventId and LastNotifiedEventId
_lastQueuedEventId = State.LastNotifiedEventId;
}
// register pollForEvents method
this.RegisterTimer(NotifySubscribers, null, TimeSpan.FromSeconds(1), _notifyInterval);
// register metrics reporter
this.RegisterTimer(ReportMetrics, null, TimeSpan.FromSeconds(30), TimeSpan.FromMinutes(1));
}