protected async Task StoreCheckpoint(ulong? position, CancellationToken cancellationToken) {
_lastProcessedPosition = position;
var checkpoint = new Checkpoint(_subscriptionId, position);
await _checkpointStore.StoreCheckpoint(checkpoint, cancellationToken);
}
private Task On(RawEvent rawEvent, Position?position, DateTime eventCreationTime)
{
var @event = _deserializer.Deserialize(rawEvent);
_log.Debug("Projecting event {event}", rawEvent.Body.ToString());
try
{
// return Measure(() =>// Should be moved to a messenger decorator
// {
var envelopedEvent = new EventEnvelope(
new MessageChainInfo(@event.Id.ToString()
, @event.Metadata.CorrelationId
, @event.Metadata.CausationId)
, @event.Body);
_messenger.Dispatch(envelopedEvent);
return(_checkpointStore.StoreCheckpoint(position));
// }, rawEvent.EventType
// , eventCreationTime
// , _subscriptionName);
}
catch (Exception exception)
{
_log.Error(exception
, "Error occured when projecting the event {event} from {subscriptionName}"
, @event
, _subscriptionName);
throw;
}
}
async Task EventAppeared(
EventStoreCatchUpSubscription _,
ResolvedEvent resolvedEvent)
{
if (resolvedEvent.Event.EventType.StartsWith("$"))
{
return;
}
var @event = resolvedEvent.Deserialze();
Log.Debug("Projecting event {event}", @event.ToString());
try
{
await Task.WhenAll(_projections.Select(x => x.Project(@event)));
await _checkpointStore.StoreCheckpoint(
resolvedEvent.OriginalPosition.Value
);
}
catch (Exception e)
{
Log.Error(
e,
"Error occured when projecting the event {event}",
@event
);
throw;
}
}
async Task Handler(StreamSubscription sub, ResolvedEvent re, CancellationToken cancellationToken)
{
if (re.Event.EventType.StartsWith("$"))
{
return;
}
var evt = re.Deserialize();
await Task.WhenAll(_projections.Select(x => x.HandleEvent(evt)));
_checkpoint.Position = (long?)re.Event.Position.CommitPosition;
await _checkpointStore.StoreCheckpoint(_checkpoint, cancellationToken);
}
private async Task EventAppeared(EventStoreCatchUpSubscription _, ResolvedEvent resolvedEvent)
{
if (resolvedEvent.Event.EventType.StartsWith("$"))
{
return;
}
var @event = resolvedEvent.Deserialzie();
Log.Debug("Projecting event {type}", @event.GetType().Name);
await Task.WhenAll(_projections.Select(x => x.Project(@event)));
await _checkpointStore.StoreCheckpoint(resolvedEvent.OriginalPosition.Value);
}
async Task EventAppeared(
EventStoreCatchUpSubscription _,
ResolvedEvent resolvedEvent)
{
if (resolvedEvent.Event.EventType.StartsWith("$"))
{
return;
}
var @event = resolvedEvent.Deserialze();
_log.Debug("Projecting event {event}", @event.ToString());
try
{
await PrometheusMetrics.Measure(async() =>
{
await Task.WhenAll(_eventHandlers.Select(x => x(@event)));
await _checkpointStore.StoreCheckpoint(
resolvedEvent.OriginalPosition.Value
);
}, PrometheusMetrics.SubscriptionTimer(_subscriptionName));
PrometheusMetrics.ObserveLeadTime(
resolvedEvent.Event.EventType,
resolvedEvent.Event.Created,
_subscriptionName);
}
catch (Exception e)
{
_log.Error(
e,
"Error occured when projecting the event {event}",
@event
);
throw;
}
}
async Task EventAppeared(
EventStoreCatchUpSubscription _,
ResolvedEvent resolvedEvent
)
{
if (resolvedEvent.Event.EventType.StartsWith("$"))
{
return;
}
var @event = resolvedEvent.Deserialze();
Log.Debug("Projecting event {event}", @event.ToString());
try
{
await Task.WhenAll(
_subscriptions.Select(x => x.Project(@event))
);
await _checkpointStore.StoreCheckpoint(
// ReSharper disable once PossibleInvalidOperationException
_isAllStream
?resolvedEvent.OriginalPosition.Value.CommitPosition
: resolvedEvent.Event.EventNumber
);
}
catch (Exception e)
{
Log.Error(
e,
"Error occured when projecting the event {event}",
@event
);
throw;
}
}
public async Task Replicate(
IEventReader reader, IEventWriter writer, ICheckpointStore checkpointStore,
CancellationToken cancellationToken,
Func <EventRead, bool> filter,
Func <EventRead, ValueTask <EventWrite> > transform
)
{
var cts = new CancellationTokenSource();
var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, cts.Token);
var start = await checkpointStore.LoadCheckpoint();
var retryPolicy = Policy
.Handle <Exception>(ex => !(ex is OperationCanceledException))
.RetryForeverAsync(ex => Log.Warn(ex, "Writer error: {Error}, retrying", ex.Message));
var channel = Channel.CreateBounded <EventRead>(Capacity)
.Source(reader.ReadEvents(start, linkedCts.Token));
if (filter != null)
{
channel = channel.Filter(x => Try(x, filter));
}
Func <EventRead, ValueTask <EventWrite> > transformFunction;
if (transform != null)
{
transformFunction = TryTransform;
}
else
{
transformFunction = DefaultTransform;
}
var resultChannel = channel
.PipeAsync(5, transformFunction, Capacity, false, linkedCts.Token)
.PipeAsync(WriteEvent, Capacity, true, linkedCts.Token)
.Batch(1024, true, true);
var lastPosition = new Position();
try {
await resultChannel.ReadUntilCancelledAsync(linkedCts.Token, StoreCheckpoint, true);
}
catch (Exception e) {
Log.Fatal(e, "Unable to proceed: {Error}", e.Message);
}
finally {
Log.Info("Last recorded position: {Position}", lastPosition);
}
async ValueTask <Position> WriteEvent(EventWrite write)
{
await retryPolicy.ExecuteAsync(() => writer.WriteEvent(write));
return(write.SourcePosition);
}
T Try <T>(EventRead evt, Func <EventRead, T> func)
{
try {
return(func(evt));
}
catch (Exception e) {
Log.Error(e, "Error in the pipeline: {Error}", e.Message);
cts.Cancel();
throw;
}
}
async ValueTask <EventWrite> TryTransform(EventRead evt) => await Try(evt, transform);
ValueTask StoreCheckpoint(List <Position> positions)
{
lastPosition = positions.Last();
return(checkpointStore.StoreCheckpoint(lastPosition));
}
}
