go任务调度5（go操作etcd）

连接etcd：

package main

import (
	"fmt"
	"go.etcd.io/etcd/clientv3"
	"time"
)

var (
	config clientv3.Config
	client *clientv3.Client
	err error
)

func main()  {
	//客户端配置
	config = clientv3.Config{
		Endpoints: []string{"0.0.0.0:2379"}, //集群列表
		DialTimeout: 5 * time.Second,
	}
	//建立连接
	if client, err = clientv3.New(config); err != nil {
		fmt.Println(err)
		return
	}
	client = client
}

---

k-v操作：

package main

import (
	"context"
	"fmt"
	"go.etcd.io/etcd/clientv3"
	//"/coreos/etcd/clientv3"
	"time"
)

var (
	config  clientv3.Config
	client  *clientv3.Client
	err     error
	kv      clientv3.KV
	putResp *clientv3.PutResponse
)

func main() {
	//客户端配置
	config = clientv3.Config{
		Endpoints:   []string{"0.0.0.0:2379"}, //集群列表
		DialTimeout: 5 * time.Second,
	}
	//建立客户端
	if client, err = clientv3.New(config); err != nil {
		fmt.Println(err)
		return
	}
	//操作k-v(用于读写etcd的键值对)
	kv = clientv3.NewKV(client)
	//context.TODO()代表什么都不做，占位就可以了
	//不在这里指定clientv3.WithPrevKV()，则不能得到putResp.PrevKv.Key,putResp.PrevKv.Value
	if putResp, err = kv.Put(context.TODO(), "/cron/jobs/job1", "world", clientv3.WithPrevKV()); err != nil {
		fmt.Println(err)
	} else {
		//输出版本号
		fmt.Println("Revision:", putResp.Header.Revision)
		if putResp.PrevKv != nil {
			//输出上一个k-v
			fmt.Println(string(putResp.PrevKv.Key), ":", string(putResp.PrevKv.Value))
		}
	}
}

运行输出

[root@bogon etcd]# go run demo2.go Revision: 19 /cron/jobs/job1 : hello 查看： [root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl get "/cron/jobs/job1" /cron/jobs/job1 world

---

get：

package main

import (
	"context"
	"fmt"
	"go.etcd.io/etcd/clientv3"
	//"/coreos/etcd/clientv3"
	"time"
)

func main() {
	var (
		config  clientv3.Config
		client  *clientv3.Client
		err     error
		kv      clientv3.KV
		getResp *clientv3.GetResponse
	)

	//客户端配置
	config = clientv3.Config{
		Endpoints:   []string{"0.0.0.0:2379"}, //集群列表
		DialTimeout: 5 * time.Second,
	}
	//建立客户端
	if client, err = clientv3.New(config); err != nil {
		fmt.Println(err)
		return
	}
	//用于读写etcd的键值对
	kv = clientv3.NewKV(client)

	if getResp, err = kv.Get(context.TODO(), "/cron/jobs/job1"); err != nil {
		fmt.Println(err)
	} else {
		fmt.Println(getResp.Kvs)
	}
}

[root@bogon etcd]# go run demo3.go [key:"/cron/jobs/job1" create_revision:4 mod_revision:21 version:16 value:"world" ] (create_revision：创建版本。mod_revision：修改版本。version：自从创建以来修改的次数。)

(敲with列出所有选项)

---

获取指定“目录”下的kvs：

package main

import (
	"context"
	"fmt"
	"go.etcd.io/etcd/clientv3"
	//"/coreos/etcd/clientv3"
	"time"
)

func main() {
	var (
		config  clientv3.Config
		client  *clientv3.Client
		err     error
		kv      clientv3.KV
		getResp *clientv3.GetResponse
	)

	//客户端配置
	config = clientv3.Config{
		Endpoints:   []string{"0.0.0.0:2379"}, //集群列表
		DialTimeout: 5 * time.Second,
	}
	//建立客户端
	if client, err = clientv3.New(config); err != nil {
		fmt.Println(err)
		return
	}
	//用于读写etcd的键值对
	kv = clientv3.NewKV(client)

	//读取/cron/jobs/为前缀的所有key
	if getResp, err = kv.Get(context.TODO(), "/cron/jobs/", clientv3.WithPrefix()); err != nil {
		fmt.Println(err)
	} else { //获取成功，我们遍历所有kvs
		fmt.Println(getResp.Kvs)
	}
}

[root@bogon etcd]# go run demo4.go [key:"/cron/jobs/job1" create_revision:4 mod_revision:21 version:16 value:"world" key:"/cron/jobs/job2" create_revision:5 mod_revision:6 version:2 value:"changed" ]

---

删除：

package main

import (
	"context"
	"fmt"
	"go.etcd.io/etcd/clientv3"
	"go.etcd.io/etcd/mvcc/mvccpb"

	//"/coreos/etcd/clientv3"
	"time"
)

func main() {
	var (
		config  clientv3.Config
		client  *clientv3.Client
		err     error
		kv      clientv3.KV
		delResp	*clientv3.DeleteResponse
		//idx int
		kvpair *mvccpb.KeyValue
	)

	//客户端配置
	config = clientv3.Config{
		Endpoints:   []string{"0.0.0.0:2379"}, //集群列表
		DialTimeout: 5 * time.Second,
	}
	//建立客户端
	if client, err = clientv3.New(config); err != nil {
		fmt.Println(err)
		return
	}
	//用于读写etcd的键值对
	kv = clientv3.NewKV(client)

	//删除kv
	if delResp, err = kv.Delete(context.TODO(), "/cron/jobs/job2/", clientv3.WithPrevKV()); err != nil {
		fmt.Println(err)
		return
	}

	//被删除之前的value是什么
	if len(delResp.PrevKvs) != 0 { //必须有clientv3.WithPrevKV()才能获取delResp.PrevKvs
		for _, kvpair = range delResp.PrevKvs {
			fmt.Println("删除了key:", string(kvpair.Key), " value:", string(kvpair.Value))
		}
	}
}

[root@bogon etcd]# go run demo5.go 删除了key: /cron/jobs/job2 value: changed 再次运行什么也不输出，因为已经删除了： [root@bogon etcd]# go run demo5.go [root@bogon etcd]# 如果要删除以/cron/jobs/job2/“目录”开头的所有kv，则将clientv3.WithPrevKV()改为：clientv3.WithPrefix()。 **clientv3.WithFromKey()则是删除以此开头的所有kv(kv存储是有序的)。 **