kgo: add NodeName for easy user formatting of internal seed node IDs

pkg/kgo/broker.go

@@ -82,11 +82,22 @@ type promisedResp struct {
 	readEnqueue  time.Time
 }
 
+// NodeName returns the name of a node, given the kgo internal node ID.
+//
+// Internally, seed brokers are stored with very negative node IDs, and these
+// node IDs are visible in the BrokerMetadata struct. You can use NodeName to
+// convert the negative node ID into "seed_#". Brokers discovered through
+// metadata responses have standard non-negative numbers and this function just
+// returns the number as a string.
+func NodeName(nodeID int32) string {
+	return logID(nodeID)
+}
+
 func logID(id int32) string {
 	if id >= -10 {
 		return strconv.FormatInt(int64(id), 10)
 	}
-	return "seed " + strconv.FormatInt(int64(id)-math.MinInt32, 10)
+	return "seed_" + strconv.FormatInt(int64(id)-math.MinInt32, 10)
 }
 
 // BrokerMetadata is metadata for a broker.
@@ -96,7 +107,8 @@ type BrokerMetadata struct {
 	// NodeID is the broker node ID.
 	//
 	// Seed brokers will have very negative IDs; kgo does not try to map
-	// seed brokers to loaded brokers.
+	// seed brokers to loaded brokers. You can use NodeName to convert
+	// the seed node ID into a formatted string.
 	NodeID int32
 
 	// Port is the port of the broker.