Refactor appservices component (#2687)

This PR refactors the app services component. It makes the following changes:

* Each appservice now gets its own NATS JetStream consumer
* The appservice database is now removed entirely, since we just use JetStream as a data source instead
* The entire component is now much simpler and we deleted lots of lines of code 💅

The result is that it should be much lighter and hopefully much more performant.

2 files changed, 17 insertions, 19 deletions

diff --git a/setup/jetstream/helpers.go b/setup/jetstream/helpers.go
index f47637c6..1ec860b0 100644
--- a/setup/jetstream/helpers.go
+++ b/setup/jetstream/helpers.go
@@ -34,14 +34,6 @@ func JetStreamConsumer(
 		}
 	}()
 
-	// If the batch size is greater than 1, we will want to acknowledge all
-	// received messages in the batch. Below we will send an acknowledgement
-	// for the most recent message in the batch and AckAll will ensure that
-	// all messages that came before it are also acknowledged implicitly.
-	if batch > 1 {
-		opts = append(opts, nats.AckAll())
-	}
-
 	name := durable + "Pull"
 	sub, err := js.PullSubscribe(subj, name, opts...)
 	if err != nil {
@@ -89,21 +81,26 @@ func JetStreamConsumer(
 			if len(msgs) < 1 {
 				continue
 			}
-			msg := msgs[len(msgs)-1] // most recent message, in case of AckAll
-			if err = msg.InProgress(nats.Context(ctx)); err != nil {
-				logrus.WithContext(ctx).WithField("subject", subj).Warn(fmt.Errorf("msg.InProgress: %w", err))
-				sentry.CaptureException(err)
-				continue
+			for _, msg := range msgs {
+				if err = msg.InProgress(nats.Context(ctx)); err != nil {
+					logrus.WithContext(ctx).WithField("subject", subj).Warn(fmt.Errorf("msg.InProgress: %w", err))
+					sentry.CaptureException(err)
+					continue
+				}
 			}
 			if f(ctx, msgs) {
-				if err = msg.AckSync(nats.Context(ctx)); err != nil {
-					logrus.WithContext(ctx).WithField("subject", subj).Warn(fmt.Errorf("msg.AckSync: %w", err))
-					sentry.CaptureException(err)
+				for _, msg := range msgs {
+					if err = msg.AckSync(nats.Context(ctx)); err != nil {
+						logrus.WithContext(ctx).WithField("subject", subj).Warn(fmt.Errorf("msg.AckSync: %w", err))
+						sentry.CaptureException(err)
+					}
 				}
 			} else {
-				if err = msg.Nak(nats.Context(ctx)); err != nil {
-					logrus.WithContext(ctx).WithField("subject", subj).Warn(fmt.Errorf("msg.Nak: %w", err))
-					sentry.CaptureException(err)
+				for _, msg := range msgs {
+					if err = msg.Nak(nats.Context(ctx)); err != nil {
+						logrus.WithContext(ctx).WithField("subject", subj).Warn(fmt.Errorf("msg.Nak: %w", err))
+						sentry.CaptureException(err)
+					}
 				}
 			}
 		}
diff --git a/setup/jetstream/nats.go b/setup/jetstream/nats.go
index 051d55a3..3660e91e 100644
--- a/setup/jetstream/nats.go
+++ b/setup/jetstream/nats.go
@@ -183,6 +183,7 @@ func setupNATS(process *process.ProcessContext, cfg *config.JetStream, nc *natsc
 		OutputReceiptEvent:      {"SyncAPIEDUServerReceiptConsumer", "FederationAPIEDUServerConsumer"},
 		OutputSendToDeviceEvent: {"SyncAPIEDUServerSendToDeviceConsumer", "FederationAPIEDUServerConsumer"},
 		OutputTypingEvent:       {"SyncAPIEDUServerTypingConsumer", "FederationAPIEDUServerConsumer"},
+		OutputRoomEvent:         {"AppserviceRoomserverConsumer"},
 	} {
 		streamName := cfg.Matrix.JetStream.Prefixed(stream)
 		for _, consumer := range consumers {