Etcd client golang example code

1. 监视某一个节点

watcher := kAPI.Watcher("workers/", &client.WatcherOptions{
        Recursive: true,
    })
    for {
        res, err := watcher.Next(context.Background())
        if err != nil {
            log.Println("Error watch workers:", err)
            break
        }
        if res.Action == "expire" {
            member, ok := m.members[res.Node.Key]
            if ok {
                member.InGroup = false
            }
        } else if res.Action == "set" || res.Action == "update"{
            info := &WorkerInfo{}
            err := json.Unmarshal([]byte(res.Node.Value), info)
            if err != nil {
                log.Print(err)
            }
            if _, ok := m.members[info.Name]; ok {
                m.UpdateWorker(info)
            } else {
                m.AddWorker(info)
            }
        } else if res.Action == "delete" {
            delete(m.members, res.Node.Key)
        }
    }

2. Create a Config and exchange it for a Client:

import (
	"net/http"

	"github.com/coreos/etcd/client"
	"golang.org/x/net/context"
)

cfg := client.Config{
	Endpoints: []string{"http://127.0.0.1:2379"},
	Transport: DefaultTransport,
}

c, err := client.New(cfg)
if err != nil {
	// handle error
}

Clients are safe for concurrent use by multiple goroutines.

3. Create a KeysAPI using the Client, then use it to interact with etcd:
kAPI := client.NewKeysAPI(c)

// create a new key /foo with the value "bar"
_, err = kAPI.Create(context.Background(), "/foo", "bar")
if err != nil {
	// handle error
}

// delete the newly created key only if the value is still "bar"
_, err = kAPI.Delete(context.Background(), "/foo", &DeleteOptions{PrevValue: "bar"})
if err != nil {
	// handle error
}
4. Use a custom context to set timeouts on your operations:
import "time"

ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()

// set a new key, ignoring it's previous state
_, err := kAPI.Set(ctx, "/ping", "pong", nil)
if err != nil {
	if err == context.DeadlineExceeded {
		// request took longer than 5s
	} else {
		// handle error
	}
}
参考： https://godoc.org/github.com/coreos/etcd/client
https://github.com/coreos/etcd/blob/master/client/README.md
http://daizuozhuo.github.io/etcd-service-discovery/
注意： 此文章只是我个人笔记， 如有错漏，请一定指正， 共同学习， 我的邮箱: htyu_0203_39@sina.com

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