/// <remarks>
/// If the event store is deployed as a cluster, it may be possible to get transient read failures.
/// If an event could not be found on the event stream, try again.
///</remarks>
private async Task ProcessSingleMessageAsync(string stream, Type eventType, IEnumerable handlers, BasicEventInfo eventInfo, string subscriberId)
{
var maxAttempts = Math.Max(_eventNotFoundRetryCount, 1);
object @event = null;
for (var i = 0; i < maxAttempts; i++)
{
if (i > 0)
{
await Task.Delay(_eventNotFoundRetryDelay).ConfigureAwait(false);
}
try
{
Log.Debug(_log, "{0}|{1}: Processing event {2}. Attempt: {3}", stream, subscriberId ?? "default", eventInfo.Id, i + 1);
@event = await _connection.ReadEventBodyAsync(eventType, eventInfo.CanonicalEventLink).ConfigureAwait(false);
if (@event != null)
{
break;
}
}
catch (EventNotFoundException ex)
{
if (i < maxAttempts - 1)
{
Log.Warning(_log, "{0}|{1}: Event could not be found. Attempting to process the event again. {2}: {3}", stream, subscriberId ?? "default", eventInfo.Id, ex.Message);
}
else
{
Log.Error(_log, "{0}|{1}: Event could not be found after {2} attempts. {3}: {4}", stream, subscriberId ?? "default", i + 1, eventInfo.Id, ex.Message);
return;
}
}
catch (Exception ex)
{
Log.Error(_log, "{0}|{1}: Error getting message {2}: {3}", stream, subscriberId ?? "default", eventInfo.Id, ex);
return;
}
}
try
{
await InvokeMessageHandlersForEventMessageAsync(stream, eventType, handlers, @event, eventInfo).ConfigureAwait(false);
}
catch (Exception ex)
{
Log.Error(_log, "{0}|{1}: Error invoking message handlers for message {2}: {3}", stream, subscriberId ?? "default", eventInfo.Id, ex);
}
}
