rearrange code

checked_node.go

@@ -158,3 +158,31 @@ func checkNodes[T Querier](ctx context.Context, discoverer NodeDiscoverer[T], ch
 
 	return res
 }
+
+// pickNodeByCriterion is a helper function to pick a single node by given criterion
+func pickNodeByCriterion[T Querier](nodes CheckedNodes[T], picker NodePicker[T], criterion NodeStateCriterion) *Node[T] {
+	var subset []CheckedNode[T]
+
+	switch criterion {
+	case Alive:
+		subset = nodes.alive
+	case Primary:
+		subset = nodes.primaries
+	case Standby:
+		subset = nodes.standbys
+	case PreferPrimary:
+		if subset = nodes.primaries; len(subset) == 0 {
+			subset = nodes.standbys
+		}
+	case PreferStandby:
+		if subset = nodes.standbys; len(subset) == 0 {
+			subset = nodes.primaries
+		}
+	}
+
+	if len(subset) == 0 {
+		return nil
+	}
+
+	return picker.PickNode(subset).Node
+}

cluster.go

@@ -173,7 +173,8 @@ func (cl *Cluster[T]) backgroundNodesUpdate(ctx context.Context) {
 	}
 }
 
-// updateNodes checks all nodes and notifies all subscribers
+// updateNodes performs a new round of cluster state check
+// and notifies all subscribers afterwards
 func (cl *Cluster[T]) updateNodes(ctx context.Context) {
 	cl.tracer.UpdateNodes()
 
@@ -189,31 +190,3 @@ func (cl *Cluster[T]) updateNodes(ctx context.Context) {
 
 	cl.tracer.NotifiedWaiters()
 }
-
-// pickNodeByCriterion is a helper function to pick a single node by given criterion
-func pickNodeByCriterion[T Querier](nodes CheckedNodes[T], picker NodePicker[T], criterion NodeStateCriterion) *Node[T] {
-	var subset []CheckedNode[T]
-
-	switch criterion {
-	case Alive:
-		subset = nodes.alive
-	case Primary:
-		subset = nodes.primaries
-	case Standby:
-		subset = nodes.standbys
-	case PreferPrimary:
-		if subset = nodes.primaries; len(subset) == 0 {
-			subset = nodes.standbys
-		}
-	case PreferStandby:
-		if subset = nodes.standbys; len(subset) == 0 {
-			subset = nodes.primaries
-		}
-	}
-
-	if len(subset) == 0 {
-		return nil
-	}
-
-	return picker.PickNode(subset).Node
-}