fix golint issues in core/discov (#479)

core/discov/publisher.go

@@ -11,8 +11,10 @@ import (
 )
 
 type (
+	// PublisherOption defines the method to customize a Publisher.
 	PublisherOption func(client *Publisher)
 
+	// A Publisher can be used to publish the value to an etcd cluster on the given key.
 	Publisher struct {
 		endpoints  []string
 		key        string
@@ -26,6 +28,10 @@ type (
 	}
 )
 
+// NewPublisher returns a Publisher.
+// endpoints is the hosts of the etcd cluster.
+// key:value are a pair to be published.
+// opts are used to customize the Publisher.
 func NewPublisher(endpoints []string, key, value string, opts ...PublisherOption) *Publisher {
 	publisher := &Publisher{
 		endpoints:  endpoints,
@@ -43,6 +49,7 @@ func NewPublisher(endpoints []string, key, value string, opts ...PublisherOption
 	return publisher
 }
 
+// KeepAlive keeps key:value alive.
 func (p *Publisher) KeepAlive() error {
 	cli, err := internal.GetRegistry().GetConn(p.endpoints)
 	if err != nil {
@@ -61,14 +68,17 @@ func (p *Publisher) KeepAlive() error {
 	return p.keepAliveAsync(cli)
 }
 
+// Pause pauses the renewing of key:value.
 func (p *Publisher) Pause() {
 	p.pauseChan <- lang.Placeholder
 }
 
+// Resume resumes the renewing of key:value.
 func (p *Publisher) Resume() {
 	p.resumeChan <- lang.Placeholder
 }
 
+// Stop stops the renewing and revokes the registration.
 func (p *Publisher) Stop() {
 	p.quit.Close()
 }
@@ -135,6 +145,7 @@ func (p *Publisher) revoke(cli internal.EtcdClient) {
 	}
 }
 
+// WithId customizes a Publisher with the id.
 func WithId(id int64) PublisherOption {
 	return func(publisher *Publisher) {
 		publisher.id = id