add some String() to make codes easier to read and debug

go/topology/data_node.go

@@ -1,6 +1,7 @@
 package topology
 
 import (
+	"fmt"
 	"strconv"
 
 	"github.com/chrislusf/weed-fs/go/glog"
@@ -26,6 +27,10 @@ func NewDataNode(id string) *DataNode {
 	return s
 }
 
+func (dn *DataNode) String() string {
+	return fmt.Sprintf("NodeImpl:%s ,volumes:%v, Ip:%s, Port:%d, PublicUrl:%s, Dead:%v", dn.NodeImpl.String(), dn.volumes, dn.Ip, dn.Port, dn.PublicUrl, dn.Dead)
+}
+
 func (dn *DataNode) AddOrUpdateVolume(v storage.VolumeInfo) {
 	if _, ok := dn.volumes[v.Id]; !ok {
 		dn.volumes[v.Id] = v