feat(go): batch redis fast writer projections

go/vehicle-gateway/cmd/nats-fast-writer/main.go

@@ -194,6 +194,10 @@ type fastUpdater interface {
 	FastUpdate(context.Context, envelope.FrameEnvelope) error
 }
 
+type fastBatchUpdater interface {
+	FastUpdateBatch(context.Context, []envelope.FrameEnvelope) error
+}
+
 type fastMessage struct {
 	subject string
 	data    []byte
@@ -290,6 +294,25 @@ func processFastBatch(ctx context.Context, registry *metrics.Registry, appender
 	if err != nil {
 		return fmt.Errorf("tdengine batch append: %w", err)
 	}
+	if batchUpdater, ok := updater.(fastBatchUpdater); ok {
+		started = time.Now()
+		err = batchUpdater.FastUpdateBatch(ctx, envelopes)
+		recordFastWriterStageDuration(registry, subject, "redis", statusFromError(err), time.Since(started))
+		if err != nil {
+			return fmt.Errorf("redis fast batch update: %w", err)
+		}
+		for _, msg := range validMessages {
+			if msg.ack != nil {
+				started = time.Now()
+				err = msg.ack()
+				recordFastWriterStageDuration(registry, msg.subject, "ack", statusFromError(err), time.Since(started))
+				if err != nil {
+					return fmt.Errorf("nats ack: %w", err)
+				}
+			}
+		}
+		return nil
+	}
 	for i, env := range envelopes {
 		msg := validMessages[i]
 		started = time.Now()