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hi.go
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hi.go
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/*
* Created on Fri May 25 2018
*
* Copyright (c) WangKai
* Email persistence201306@gmail.com
*/
package hi
import (
"context"
"fmt"
"strings"
"time"
"google.golang.org/grpc/resolver"
"github.com/coreos/etcd/clientv3"
)
const (
DefaultScheme = "hi"
)
var (
cli *clientv3.Client
)
func parseTarget(target string) (ret resolver.Target) {
var ok bool
ret.Scheme, ret.Endpoint, ok = split2(target, "://")
if !ok {
return resolver.Target{Endpoint: target}
}
ret.Authority, ret.Endpoint, _ = split2(ret.Endpoint, "/")
return ret
}
func split2(s, sep string) (string, string, bool) {
spl := strings.SplitN(s, sep, 2)
if len(spl) < 2 {
return "", "", false
}
return spl[0], spl[1], true
}
type hi struct {
Endpoints []string
Scheme string
}
// NewHi create a Hi instance
func NewHi(endpoints []string, scheme string) hi {
if scheme == "" {
scheme = DefaultScheme
}
return hi{Endpoints: endpoints, Scheme: scheme}
}
// Unregiste delete name from etcd
func (h *hi) Unregister(name string) error {
_, err := cli.Delete(context.Background(), name, clientv3.WithPrefix())
if err != nil {
return err
}
return nil
}
// Register register microserver address under the scheme/name
func (h *hi) Register(name, addr string) error {
var err error
// create client if not define
if cli == nil {
cli, err = clientv3.New(clientv3.Config{
Endpoints: h.Endpoints,
DialTimeout: 10 * time.Second,
})
if err != nil {
return err
}
}
// create lease with 12s TTL
leaseResp, err := cli.Grant(context.Background(), 12)
if err != nil {
return err
}
// put key & value
key := fmt.Sprintf("%s/%s/%s", h.Scheme, name, addr)
_, err = cli.Put(context.Background(), key, addr, clientv3.WithLease(leaseResp.ID))
if err != nil {
return err
}
// generate a goroutine to keep lease alive per 10s
go func() {
for range time.Tick(time.Second * 10) {
cli.KeepAliveOnce(context.Background(), leaseResp.ID)
}
}()
return nil
}