chore: added logger warning and simplified ewma calculation

Signed-off-by: Theis Randeris Mathiassen <[email protected]>

Author: Theis-Mathiassen

service/sharddistributor/store/etcd/executorstore/etcdstore.go

@@ -178,6 +178,11 @@ func (s *executorStoreImpl) updateShardStatisticsFromHeartbeat(ctx context.Conte
 
 	for shardID, report := range reported {
 		if report == nil {
+			s.logger.Warn("empty report; skipping EWMA update",
+				tag.ShardNamespace(namespace),
+				tag.ShardExecutor(executorID),
+				tag.ShardKey(shardID),
+			)
 			continue
 		}
 
@@ -820,19 +825,12 @@ func (s *executorStoreImpl) applyShardStatisticsUpdates(ctx context.Context, nam
 	}
 }
 
-// ewmaSmoothedLoad computes an EWMA for shard load.
 func ewmaSmoothedLoad(prev, current float64, lastUpdate, now int64) float64 {
 	const tauSeconds = 30.0 // smaller = more responsive, larger = smoother, slower
-	if lastUpdate <= 0 {
-		return current
-	}
-	dt := now - lastUpdate
-	if dt < 0 {
-		dt = 0
-	}
-	if tauSeconds <= 0 {
+	if lastUpdate <= 0 || tauSeconds <= 0 {
 		return current
 	}
+	dt := max(now-lastUpdate, 0)
 	alpha := 1 - math.Exp(-float64(dt)/tauSeconds)
 	return (1-alpha)*prev + alpha*current
 }