Add sync => go-sync

sync/leader/etcd/etcd.go

@@ -0,0 +1,145 @@
+package etcd
+
+import (
+	"context"
+	"log"
+	"path"
+	"strings"
+
+	"github.com/micro/go-micro/sync/leader"
+	client "go.etcd.io/etcd/clientv3"
+	cc "go.etcd.io/etcd/clientv3/concurrency"
+)
+
+type etcdLeader struct {
+	opts   leader.Options
+	path   string
+	client *client.Client
+}
+
+type etcdElected struct {
+	s  *cc.Session
+	e  *cc.Election
+	id string
+}
+
+func (e *etcdLeader) Elect(id string, opts ...leader.ElectOption) (leader.Elected, error) {
+	var options leader.ElectOptions
+	for _, o := range opts {
+		o(&options)
+	}
+
+	// make path
+	path := path.Join(e.path, strings.Replace(id, "/", "-", -1))
+
+	s, err := cc.NewSession(e.client)
+	if err != nil {
+		return nil, err
+	}
+
+	l := cc.NewElection(s, path)
+
+	ctx, _ := context.WithCancel(context.Background())
+
+	if err := l.Campaign(ctx, id); err != nil {
+		return nil, err
+	}
+
+	return &etcdElected{
+		e:  l,
+		id: id,
+	}, nil
+}
+
+func (e *etcdLeader) Follow() chan string {
+	ch := make(chan string)
+
+	s, err := cc.NewSession(e.client)
+	if err != nil {
+		return ch
+	}
+
+	l := cc.NewElection(s, e.path)
+	ech := l.Observe(context.Background())
+
+	go func() {
+		for {
+			select {
+			case r, ok := <-ech:
+				if !ok {
+					return
+				}
+				ch <- string(r.Kvs[0].Value)
+			}
+		}
+	}()
+
+	return ch
+}
+
+func (e *etcdLeader) String() string {
+	return "etcd"
+}
+
+func (e *etcdElected) Reelect() error {
+	ctx, _ := context.WithCancel(context.Background())
+	return e.e.Campaign(ctx, e.id)
+}
+
+func (e *etcdElected) Revoked() chan bool {
+	ch := make(chan bool, 1)
+	ech := e.e.Observe(context.Background())
+
+	go func() {
+		for r := range ech {
+			if string(r.Kvs[0].Value) != e.id {
+				ch <- true
+				close(ch)
+				return
+			}
+		}
+	}()
+
+	return ch
+}
+
+func (e *etcdElected) Resign() error {
+	return e.e.Resign(context.Background())
+}
+
+func (e *etcdElected) Id() string {
+	return e.id
+}
+
+func NewLeader(opts ...leader.Option) leader.Leader {
+	var options leader.Options
+	for _, o := range opts {
+		o(&options)
+	}
+
+	var endpoints []string
+
+	for _, addr := range options.Nodes {
+		if len(addr) > 0 {
+			endpoints = append(endpoints, addr)
+		}
+	}
+
+	if len(endpoints) == 0 {
+		endpoints = []string{"http://127.0.0.1:2379"}
+	}
+
+	// TODO: parse addresses
+	c, err := client.New(client.Config{
+		Endpoints: endpoints,
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	return &etcdLeader{
+		path:   "/micro/leader",
+		client: c,
+		opts:   options,
+	}
+}