public static async Task <long?> Handle <S, C>(CommandEnvelope <C> commandEnvelope, IAggregate <S> aggregate, IEventStore eventStore, CancellationToken cancel = default) where C : class where S : class
{
if (commandEnvelope.AggregateId == null || commandEnvelope.Command == null)
{
throw new Exception();
}
var streamName = aggregate.GetStreamName(commandEnvelope.AggregateId);
var(version, state) = await Load(streamName, aggregate, eventStore, cancel);
var events = aggregate.Handle(state, commandEnvelope.Command)
.Select((e, i) => e.CreateEventEnvelope(commandEnvelope.AggregateId, version + i + 1))
.ToArray();
return(await eventStore.Save(streamName, cancel, events));
}
private async Task Save(IAggregate aggregate, string correlationId, string causationId)
{
var commitHeaders = new Dictionary <string, object>();
var metaData = _environment.GetMetaData().MetaData;
foreach (var item in metaData)
{
commitHeaders[item.Key] = item.Value;
}
if (!string.IsNullOrEmpty(correlationId))
{
commitHeaders[CorrelationIdKey] = correlationId;
}
if (!string.IsNullOrEmpty(causationId))
{
commitHeaders[CausationIdKey] = causationId;
}
commitHeaders[AggregateClrTypeHeader] = aggregate.GetType().AssemblyQualifiedName;
commitHeaders[AggregateIdHeader] = aggregate.Id;
_environment.GetSettings <EventStoreSettings>().ModifyHeaders(commitHeaders);
var streamName = aggregate.GetStreamName(_environment);
var eventStream = aggregate.GetUncommittedChanges();
var newEvents = eventStream.Events.ToList();
var originalVersion = aggregate.Version - newEvents.Count;
var versionToExpect = originalVersion == 0 ? ExpectedVersion.Any : originalVersion - 1;
while (true)
{
try
{
await SaveEventsToStream(streamName, versionToExpect, newEvents, commitHeaders).ConfigureAwait(false);
break;
}
catch (WrongExpectedVersionException ex)
{
_environment.Log(ex, "Events where added to aggregate with id: {0} since last load. Checking for conflicts and trying again...", LogLevel.Warn, aggregate.Id);
}
catch (AggregateException ae)
{
if (!(ae.InnerException is WrongExpectedVersionException))
{
throw;
}
_environment.Log(ae.InnerException, "Events where added to aggregate with id: {0} since last load. Checking for conflicts and trying again...", LogLevel.Warn, aggregate.Id);
}
var storedEvents = (await LoadEventsFromStream(streamName, versionToExpect < 0 ? 0 : versionToExpect, int.MaxValue).ConfigureAwait(false)).ToList();
var currentVersion = storedEvents.Select(x => x.OriginalEventNumber).OrderByDescending(x => x).FirstOrDefault();
if (_checkConflicts.HasConflicts(newEvents, storedEvents, _environment))
{
throw new ConflictingEventException(streamName, versionToExpect, currentVersion);
}
versionToExpect = currentVersion;
}
aggregate.ClearUncommittedChanges();
}