pubsub: add PING support.

example_test.go

@@ -2,7 +2,6 @@ package redis_test
 
 import (
 	"fmt"
-	"net"
 	"strconv"
 	"sync"
 	"time"
@@ -179,14 +178,14 @@ func ExamplePubSub() {
 		panic(err)
 	}
 
-	for {
+	for i := 0; i < 4; i++ {
 		msgi, err := pubsub.ReceiveTimeout(100 * time.Millisecond)
 		if err != nil {
-			if neterr, ok := err.(net.Error); ok && neterr.Timeout() {
-				// There are no more messages to process. Stop.
-				break
+			err := pubsub.Ping("")
+			if err != nil {
+				panic(err)
 			}
-			panic(err)
+			continue
 		}
 
 		switch msg := msgi.(type) {
@@ -194,6 +193,8 @@ func ExamplePubSub() {
 			fmt.Println(msg.Kind, msg.Channel)
 		case *redis.Message:
 			fmt.Println(msg.Channel, msg.Payload)
+		case *redis.Pong:
+			fmt.Println(msg)
 		default:
 			panic(fmt.Sprintf("unknown message: %#v", msgi))
 		}
@@ -201,6 +202,7 @@ func ExamplePubSub() {
 
 	// Output: subscribe mychannel
 	// mychannel hello
+	// Pong
 }
 
 func ExampleScript() {

pubsub.go

@@ -26,6 +26,20 @@ func (c *Client) Publish(channel, message string) *IntCmd {
 	return req
 }
 
+func (c *PubSub) Ping(payload string) error {
+	cn, err := c.conn()
+	if err != nil {
+		return err
+	}
+
+	args := []interface{}{"PING"}
+	if payload != "" {
+		args = append(args, payload)
+	}
+	cmd := NewCmd(args...)
+	return cn.writeCmds(cmd)
+}
+
 // Message received as result of a PUBLISH command issued by another client.
 type Message struct {
 	Channel string
@@ -48,6 +62,18 @@ func (m *PMessage) String() string {
 	return fmt.Sprintf("PMessage<%s: %s>", m.Channel, m.Payload)
 }
 
+// Pong received as result of a PING command issued by another client.
+type Pong struct {
+	Payload string
+}
+
+func (p *Pong) String() string {
+	if p.Payload != "" {
+		return fmt.Sprintf("Pong<%s>", p.Payload)
+	}
+	return "Pong"
+}
+
 // Message received after a successful subscription to channel.
 type Subscription struct {
 	// Can be "subscribe", "unsubscribe", "psubscribe" or "punsubscribe".
@@ -66,22 +92,8 @@ func (c *PubSub) Receive() (interface{}, error) {
 	return c.ReceiveTimeout(0)
 }
 
-func (c *PubSub) ReceiveTimeout(timeout time.Duration) (interface{}, error) {
-	cn, err := c.conn()
-	if err != nil {
-		return nil, err
-	}
-	cn.ReadTimeout = timeout
-
-	cmd := NewSliceCmd()
-	if err := cmd.parseReply(cn.rd); err != nil {
-		return nil, err
-	}
-
-	reply := cmd.Val()
-
-	kind := reply[0].(string)
-	switch kind {
+func newMessage(reply []interface{}) (interface{}, error) {
+	switch kind := reply[0].(string); kind {
 	case "subscribe", "unsubscribe", "psubscribe", "punsubscribe":
 		return &Subscription{
 			Kind:    kind,
@@ -99,9 +111,27 @@ func (c *PubSub) ReceiveTimeout(timeout time.Duration) (interface{}, error) {
 			Channel: reply[2].(string),
 			Payload: reply[3].(string),
 		}, nil
+	case "pong":
+		return &Pong{
+			Payload: reply[1].(string),
+		}, nil
+	default:
+		return nil, fmt.Errorf("redis: unsupported pubsub notification: %q", kind)
 	}
+}
 
-	return nil, fmt.Errorf("redis: unsupported pubsub notification: %q", kind)
+func (c *PubSub) ReceiveTimeout(timeout time.Duration) (interface{}, error) {
+	cn, err := c.conn()
+	if err != nil {
+		return nil, err
+	}
+	cn.ReadTimeout = timeout
+
+	cmd := NewSliceCmd()
+	if err := cmd.parseReply(cn.rd); err != nil {
+		return nil, err
+	}
+	return newMessage(cmd.Val())
 }
 
 func (c *PubSub) subscribe(cmd string, channels ...string) error {

pubsub_test.go

@@ -12,24 +12,22 @@ import (
 
 var _ = Describe("PubSub", func() {
 	var client *redis.Client
+	var pubsub *redis.PubSub
 
 	BeforeEach(func() {
 		client = redis.NewClient(&redis.Options{
 			Addr: redisAddr,
 		})
+		Expect(client.FlushDb().Err()).NotTo(HaveOccurred())
+		pubsub = client.PubSub()
 	})
 
 	AfterEach(func() {
-		Expect(client.FlushDb().Err()).NotTo(HaveOccurred())
+		Expect(pubsub.Close()).NotTo(HaveOccurred())
 		Expect(client.Close()).NotTo(HaveOccurred())
 	})
 
 	It("should support pattern matching", func() {
-		pubsub := client.PubSub()
-		defer func() {
-			Expect(pubsub.Close()).NotTo(HaveOccurred())
-		}()
-
 		Expect(pubsub.PSubscribe("mychannel*")).NotTo(HaveOccurred())
 
 		pub := client.Publish("mychannel1", "hello")
@@ -77,8 +75,6 @@ var _ = Describe("PubSub", func() {
 		Expect(err).NotTo(HaveOccurred())
 		Expect(channels).To(BeEmpty())
 
-		pubsub := client.PubSub()
-		defer pubsub.Close()
 		Expect(pubsub.Subscribe("mychannel", "mychannel2")).NotTo(HaveOccurred())
 
 		channels, err = client.PubSubChannels("mychannel*").Result()
@@ -95,8 +91,6 @@ var _ = Describe("PubSub", func() {
 	})
 
 	It("should return the numbers of subscribers", func() {
-		pubsub := client.PubSub()
-		defer pubsub.Close()
 		Expect(pubsub.Subscribe("mychannel", "mychannel2")).NotTo(HaveOccurred())
 
 		channels, err := client.PubSubNumSub("mychannel", "mychannel2", "mychannel3").Result()
@@ -113,8 +107,6 @@ var _ = Describe("PubSub", func() {
 		Expect(err).NotTo(HaveOccurred())
 		Expect(num).To(Equal(int64(0)))
 
-		pubsub := client.PubSub()
-		defer pubsub.Close()
 		Expect(pubsub.PSubscribe("*")).NotTo(HaveOccurred())
 
 		num, err = client.PubSubNumPat().Result()
@@ -123,11 +115,6 @@ var _ = Describe("PubSub", func() {
 	})
 
 	It("should pub/sub", func() {
-		pubsub := client.PubSub()
-		defer func() {
-			Expect(pubsub.Close()).NotTo(HaveOccurred())
-		}()
-
 		Expect(pubsub.Subscribe("mychannel", "mychannel2")).NotTo(HaveOccurred())
 
 		pub := client.Publish("mychannel", "hello")
@@ -199,4 +186,36 @@ var _ = Describe("PubSub", func() {
 		}
 	})
 
+	It("should ping/pong", func() {
+		err := pubsub.Subscribe("mychannel")
+		Expect(err).NotTo(HaveOccurred())
+
+		_, err = pubsub.ReceiveTimeout(time.Second)
+		Expect(err).NotTo(HaveOccurred())
+
+		err = pubsub.Ping("")
+		Expect(err).NotTo(HaveOccurred())
+
+		msgi, err := pubsub.ReceiveTimeout(time.Second)
+		Expect(err).NotTo(HaveOccurred())
+		pong := msgi.(*redis.Pong)
+		Expect(pong.Payload).To(Equal(""))
+	})
+
+	It("should ping/pong with payload", func() {
+		err := pubsub.Subscribe("mychannel")
+		Expect(err).NotTo(HaveOccurred())
+
+		_, err = pubsub.ReceiveTimeout(time.Second)
+		Expect(err).NotTo(HaveOccurred())
+
+		err = pubsub.Ping("hello")
+		Expect(err).NotTo(HaveOccurred())
+
+		msgi, err := pubsub.ReceiveTimeout(time.Second)
+		Expect(err).NotTo(HaveOccurred())
+		pong := msgi.(*redis.Pong)
+		Expect(pong.Payload).To(Equal("hello"))
+	})
+
 })