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load.go
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load.go
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package easyetcd
import (
"flag"
"log"
"path"
"reflect"
"strings"
"github.com/coreos/go-etcd/etcd"
"github.com/qiniu/errors"
"github.com/qiniu/http/misc/strconv"
)
var (
confName *string
)
func Init(cFlag, default_conf string) {
confName = flag.String(cFlag, default_conf, "the etcd config file")
}
func Load(conf interface{}) error {
if !flag.Parsed() {
flag.Parse()
}
log.Println("use the etcd file of:", *confName)
client, err := etcd.NewClientFromFile(*confName)
if err != nil {
return err
}
return LoadWithEtcdClient(client, "appName", conf)
}
var (
defaultTag = "json"
)
func LoadWithEtcdClient(client *etcd.Client, app string, conf interface{}) (err error) {
v := reflect.ValueOf(conf)
if v.Kind() != reflect.Ptr {
err = errors.New("etcdcfg.LoadWithEtcdClient: ret.type != pointer")
return
}
if v.Elem().Kind() != reflect.Struct {
err = errors.New("etcdcfg.LoadWithEtcdClient: ret.type != struct")
return
}
resp, err := client.Get(app, true, true)
if err != nil {
err = errors.Info(err, "etcd.Get").Detail(err)
return
}
err = parseNode(client, "/"+app+"/", &v, resp.Node)
if err != nil {
}
return
}
func parseNode(client *etcd.Client, name string, v *reflect.Value, root *etcd.Node) (err error) {
if v.Kind() == reflect.Ptr {
if v.IsNil() {
nv := reflect.New(v.Type().Elem())
v.Set(nv)
}
*v = v.Elem()
}
switch v.Kind() {
case reflect.Struct:
if !root.Dir {
err = errors.New("node of " + name + "is not dir")
return
}
vt := v.Type()
for i := 0; i < v.NumField(); i++ {
sv := v.Field(i)
sf := vt.Field(i)
tag := sf.Tag.Get(defaultTag)
if tag == "" {
// do not parse value without tag
continue
}
tagv, ok := parseTag(tag)
if !ok {
log.Println("tag is empty:", sf.Name)
continue
}
tagv = path.Join(name, tagv)
for _, node := range root.Nodes {
if node.Key == tagv {
parseNode(client, tagv, &sv, node)
break
}
}
if client != nil && v.CanAddr() {
vPtr := v.Addr()
reloadMethodName := "Reload" + sf.Name
reloadMethod := vPtr.MethodByName(reloadMethodName)
if reloadMethod.IsValid() {
previousValue := sv
// check reloadMethod's arguments
receiver := make(chan *etcd.Response)
go func() {
_, err := client.Watch(tagv, 0, true, receiver, nil)
if err != nil {
// deliver err to outside
panic(err)
}
}()
go func() {
for {
resp := <-receiver
rv := reflect.New(sf.Type)
parseNode(nil, tagv, &rv, resp.Node)
if reflect.DeepEqual(previousValue.Interface(), rv.Interface()) {
continue
}
previousValue = rv
reloadMethod.Call([]reflect.Value{rv})
}
}()
}
}
}
case reflect.Slice:
if !root.Dir {
err = errors.New("node of " + name + "is not dir")
return
}
n := len(root.Nodes)
vt := v.Type()
slice := reflect.MakeSlice(vt, n, n)
for i := 0; i < n; i++ {
sv := slice.Index(i)
err = parseNode(client, root.Nodes[i].Key, &sv, root.Nodes[i])
if err != nil {
return
}
}
v.Set(slice)
case reflect.Map:
if !root.Dir {
err = errors.New("node of " + name + "is not dir")
return
}
vt := v.Type()
keyT, valueT := vt.Key(), vt.Elem()
mp := reflect.MakeMap(vt)
for _, node := range root.Nodes {
key := reflect.New(keyT)
key = key.Elem()
err = strconv.ParseValue(key, node.Key[len(name)+1:])
if err != nil {
return
}
var value reflect.Value
value = reflect.New(valueT)
value = value.Elem()
err = parseNode(client, node.Key, &value, node)
if err != nil {
return
}
mp.SetMapIndex(key, value)
}
v.Set(mp)
default:
err = strconv.ParseValue(*v, root.Value)
}
return
}
func parseTag(tag string) (v string, ok bool) {
parts := strings.Split(tag, ",")
v = parts[0]
if v != "" {
ok = true
}
// todo: add some opt
return
}