vttablet: Change comments, variables and help text to better reflect that the new method operates on a comma separated list.

go/vt/topo/topoproto/tablet.go

@@ -146,7 +146,7 @@ var SlaveTabletTypes = []topodatapb.TabletType{
 	topodatapb.TabletType_DRAINED,
 }
 
-// ParseTabletType parses the tablet type into the enum
+// ParseTabletType parses the tablet type into the enum.
 func ParseTabletType(param string) (topodatapb.TabletType, error) {
 	value, ok := topodatapb.TabletType_value[strings.ToUpper(param)]
 	if !ok {
@@ -155,17 +155,17 @@ func ParseTabletType(param string) (topodatapb.TabletType, error) {
 	return topodatapb.TabletType(value), nil
 }
 
-// ParseTabletTypes parses the tablet type into the enum
+// ParseTabletTypes parses a comma separated list of tablet types and returns a slice with the respective enums.
 func ParseTabletTypes(param string) ([]topodatapb.TabletType, error) {
-	var sourceTabletTypes []topodatapb.TabletType
+	var tabletTypes []topodatapb.TabletType
 	for _, typeStr := range strings.Split(param, ",") {
 		t, err := ParseTabletType(typeStr)
 		if err != nil {
-			return nil, fmt.Errorf("unknown tablet type: %v", typeStr)
+			return nil, err
 		}
-		sourceTabletTypes = append(sourceTabletTypes, t)
+		tabletTypes = append(tabletTypes, t)
 	}
-	return sourceTabletTypes, nil
+	return tabletTypes, nil
 }
 
 // TabletTypeLString returns a lower case version of the tablet type,

go/vt/vttablet/tabletmanager/binlog_players.go

@@ -53,7 +53,7 @@ var (
 	healthCheckTopologyRefresh = flag.Duration("binlog_player_healthcheck_topology_refresh", 30*time.Second, "refresh interval for re-reading the topology")
 	healthcheckRetryDelay      = flag.Duration("binlog_player_healthcheck_retry_delay", 5*time.Second, "delay before retrying a failed healthcheck")
 	healthCheckTimeout         = flag.Duration("binlog_player_healthcheck_timeout", time.Minute, "the health check timeout period")
-	sourceTabletTypeStr        = flag.String("binlog_player_tablet_type", "REPLICA", "which tablet type that is used as a source")
+	sourceTabletTypeStr        = flag.String("binlog_player_tablet_type", "REPLICA", "comma separated list of tablet types used as a source")
 )
 
 func init() {