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// Copyright 2015 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package util
import (
"encoding/json"
"path"
"github.com/juju/errors"
"github.com/ngaut/go-zookeeper/zk"
"github.com/ngaut/zkhelper"
)
func getLeader(data []byte) (string, error) {
m := struct {
Addr string `json:"Addr"`
}{}
err := json.Unmarshal(data, &m)
if err != nil {
return "", errors.Trace(err)
}
return m.Addr, nil
}
// getLeaderPath gets the leader path in zookeeper.
func getLeaderPath(rootPath string) string {
return path.Join(rootPath, "leader")
}
// func checkLeaderExists(conn zkhelper.Conn) error {
// // the leader node is not ephemeral, so we may meet no any tso server but leader node
// // has the data for last closed tso server.
// // TODO: check children in /candidates, if no child, we will treat it as no leader too.
// return nil
// }
// GetLeaderAddr gets the leader tso address in zookeeper for outer use.
func GetLeader(conn zkhelper.Conn, rootPath string) (string, error) {
data, _, err := conn.Get(getLeaderPath(rootPath))
if err != nil {
return "", errors.Trace(err)
}
// if err != checkLeaderExists(conn); err != nil {
// return "", errors.Trace(err)
// }
return getLeader(data)
}
// GetWatchLeader gets the leader tso address in zookeeper and returns a watcher for leader change.
func GetWatchLeader(conn zkhelper.Conn, rootPath string) (string, <-chan zk.Event, error) {
data, _, watcher, err := conn.GetW(getLeaderPath(rootPath))
if err != nil {
return "", nil, errors.Trace(err)
}
addr, err := getLeader(data)
if err != nil {
return "", nil, errors.Trace(err)
}
// if err != checkLeaderExists(conn); err != nil {
// return "", errors.Trace(err)
// }
return addr, watcher, nil
}