feat(pubsub): support sharded pub/sub

cluster.go

@@ -1528,6 +1528,16 @@ func (c *ClusterClient) PSubscribe(ctx context.Context, channels ...string) *Pub
 	return pubsub
 }
 
+// SSubscribe Subscribes the client to the specified shard channels.
+func (c *ClusterClient) SSubscribe(ctx context.Context, channels ...string) *PubSub {
+	pubsub := c.pubSub()
+	if len(channels) > 0 {
+		_ = pubsub.SSubscribe(ctx, channels...)
+	}
+	return pubsub
+}
+
+
 func (c *ClusterClient) retryBackoff(attempt int) time.Duration {
 	return internal.RetryBackoff(attempt, c.opt.MinRetryBackoff, c.opt.MaxRetryBackoff)
 }

cluster_test.go

@@ -549,6 +549,30 @@ var _ = Describe("ClusterClient", func() {
 			}, 30*time.Second).ShouldNot(HaveOccurred())
 		})
 
+		It("supports sharded PubSub", func() {
+			pubsub := client.SSubscribe(ctx, "mychannel")
+			defer pubsub.Close()
+
+			Eventually(func() error {
+				_, err := client.SPublish(ctx, "mychannel", "hello").Result()
+				if err != nil {
+					return err
+				}
+
+				msg, err := pubsub.ReceiveTimeout(ctx, time.Second)
+				if err != nil {
+					return err
+				}
+
+				_, ok := msg.(*redis.Message)
+				if !ok {
+					return fmt.Errorf("got %T, wanted *redis.Message", msg)
+				}
+
+				return nil
+			}, 30*time.Second).ShouldNot(HaveOccurred())
+		})
+
 		It("supports PubSub.Ping without channels", func() {
 			pubsub := client.Subscribe(ctx)
 			defer pubsub.Close()

commands.go

@@ -345,9 +345,12 @@ type Cmdable interface {
 	ScriptLoad(ctx context.Context, script string) *StringCmd
 
 	Publish(ctx context.Context, channel string, message interface{}) *IntCmd
+	SPublish(ctx context.Context, channel string, message interface{}) *IntCmd
 	PubSubChannels(ctx context.Context, pattern string) *StringSliceCmd
 	PubSubNumSub(ctx context.Context, channels ...string) *StringIntMapCmd
 	PubSubNumPat(ctx context.Context) *IntCmd
+	PubSubShardChannels(ctx context.Context, pattern string) *StringSliceCmd
+	PubSubShardNumSub(ctx context.Context, channels ...string) *StringIntMapCmd
 
 	ClusterSlots(ctx context.Context) *ClusterSlotsCmd
 	ClusterNodes(ctx context.Context) *StringCmd
@@ -3078,6 +3081,12 @@ func (c cmdable) Publish(ctx context.Context, channel string, message interface{
 	return cmd
 }
 
+func (c cmdable) SPublish(ctx context.Context, channel string, message interface{}) *IntCmd {
+	cmd := NewIntCmd(ctx, "spublish", channel, message)
+	_ = c(ctx, cmd)
+	return cmd
+}
+
 func (c cmdable) PubSubChannels(ctx context.Context, pattern string) *StringSliceCmd {
 	args := []interface{}{"pubsub", "channels"}
 	if pattern != "*" {
@@ -3100,6 +3109,28 @@ func (c cmdable) PubSubNumSub(ctx context.Context, channels ...string) *StringIn
 	return cmd
 }
 
+func (c cmdable) PubSubShardChannels(ctx context.Context, pattern string) *StringSliceCmd {
+	args := []interface{}{"pubsub", "shardchannels"}
+	if pattern != "*" {
+		args = append(args, pattern)
+	}
+	cmd := NewStringSliceCmd(ctx, args...)
+	_ = c(ctx, cmd)
+	return cmd
+}
+
+func (c cmdable) PubSubShardNumSub(ctx context.Context, channels ...string) *StringIntMapCmd {
+	args := make([]interface{}, 2+len(channels))
+	args[0] = "pubsub"
+	args[1] = "shardnumsub"
+	for i, channel := range channels {
+		args[2+i] = channel
+	}
+	cmd := NewStringIntMapCmd(ctx, args...)
+	_ = c(ctx, cmd)
+	return cmd
+}
+
 func (c cmdable) PubSubNumPat(ctx context.Context) *IntCmd {
 	cmd := NewIntCmd(ctx, "pubsub", "numpat")
 	_ = c(ctx, cmd)

pubsub.go

@@ -28,6 +28,7 @@ type PubSub struct {
 	cn       *pool.Conn
 	channels map[string]struct{}
 	patterns map[string]struct{}
+	schannels map[string]struct{}
 
 	closed bool
 	exit   chan struct{}
@@ -46,6 +47,7 @@ func (c *PubSub) init() {
 func (c *PubSub) String() string {
 	channels := mapKeys(c.channels)
 	channels = append(channels, mapKeys(c.patterns)...)
+	channels = append(channels, mapKeys(c.schannels)...)
 	return fmt.Sprintf("PubSub(%s)", strings.Join(channels, ", "))
 }
 
@@ -101,6 +103,13 @@ func (c *PubSub) resubscribe(ctx context.Context, cn *pool.Conn) error {
 		}
 	}
 
+	if len(c.schannels) > 0 {
+		err := c._subscribe(ctx, cn, "ssubscribe", mapKeys(c.schannels))
+		if err != nil && firstErr == nil {
+			firstErr = err
+		}
+	}
+
 	return firstErr
 }
 
@@ -208,6 +217,21 @@ func (c *PubSub) PSubscribe(ctx context.Context, patterns ...string) error {
 	return err
 }
 
+// SSubscribe Subscribes the client to the specified shard channels.
+func (c *PubSub) SSubscribe(ctx context.Context, channels ...string) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	err := c.subscribe(ctx, "ssubscribe", channels...)
+	if c.schannels == nil {
+		c.schannels = make(map[string]struct{})
+	}
+	for _, s := range channels {
+		c.schannels[s] = struct{}{}
+	}
+	return err
+}
+
 // Unsubscribe the client from the given channels, or from all of
 // them if none is given.
 func (c *PubSub) Unsubscribe(ctx context.Context, channels ...string) error {
@@ -234,6 +258,19 @@ func (c *PubSub) PUnsubscribe(ctx context.Context, patterns ...string) error {
 	return err
 }
 
+// SUnsubscribe unsubscribes the client from the given shard channels,
+// or from all of them if none is given.
+func (c *PubSub) SUnsubscribe(ctx context.Context, channels ...string) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	for _, channel := range channels {
+		delete(c.schannels, channel)
+	}
+	err := c.subscribe(ctx, "sunsubscribe", channels...)
+	return err
+}
+
 func (c *PubSub) subscribe(ctx context.Context, redisCmd string, channels ...string) error {
 	cn, err := c.conn(ctx, channels)
 	if err != nil {
@@ -311,7 +348,7 @@ func (c *PubSub) newMessage(reply interface{}) (interface{}, error) {
 		}, nil
 	case []interface{}:
 		switch kind := reply[0].(string); kind {
-		case "subscribe", "unsubscribe", "psubscribe", "punsubscribe":
+		case "subscribe", "unsubscribe", "psubscribe", "punsubscribe", "ssubscribe", "sunsubscribe":
 			// Can be nil in case of "unsubscribe".
 			channel, _ := reply[1].(string)
 			return &Subscription{
@@ -319,7 +356,7 @@ func (c *PubSub) newMessage(reply interface{}) (interface{}, error) {
 				Channel: channel,
 				Count:   int(reply[2].(int64)),
 			}, nil
-		case "message":
+		case "message", "smessage":
 			switch payload := reply[2].(type) {
 			case string:
 				return &Message{

pubsub_test.go

@@ -102,6 +102,35 @@ var _ = Describe("PubSub", func() {
 		Expect(len(channels)).To(BeNumerically(">=", 2))
 	})
 
+	It("should sharded pub/sub channels", func() {
+		channels, err := client.PubSubShardChannels(ctx, "mychannel*").Result()
+		Expect(err).NotTo(HaveOccurred())
+		Expect(channels).To(BeEmpty())
+
+		pubsub := client.SSubscribe(ctx, "mychannel", "mychannel2")
+		defer pubsub.Close()
+
+		channels, err = client.PubSubShardChannels(ctx, "mychannel*").Result()
+		Expect(err).NotTo(HaveOccurred())
+		Expect(channels).To(ConsistOf([]string{"mychannel", "mychannel2"}))
+
+		channels, err = client.PubSubShardChannels(ctx, "").Result()
+		Expect(err).NotTo(HaveOccurred())
+		Expect(channels).To(BeEmpty())
+
+		channels, err = client.PubSubShardChannels(ctx, "*").Result()
+		Expect(err).NotTo(HaveOccurred())
+		Expect(len(channels)).To(BeNumerically(">=", 2))
+
+		nums, err := client.PubSubShardNumSub(ctx, "mychannel", "mychannel2", "mychannel3").Result()
+		Expect(err).NotTo(HaveOccurred())
+		Expect(nums).To(Equal(map[string]int64{
+			"mychannel":  1,
+			"mychannel2": 1,
+			"mychannel3": 0,
+		}))
+	})
+
 	It("should return the numbers of subscribers", func() {
 		pubsub := client.Subscribe(ctx, "mychannel", "mychannel2")
 		defer pubsub.Close()
@@ -204,6 +233,82 @@ var _ = Describe("PubSub", func() {
 		Expect(stats.Misses).To(Equal(uint32(1)))
 	})
 
+	It("should sharded pub/sub", func() {
+		pubsub := client.SSubscribe(ctx, "mychannel", "mychannel2")
+		defer pubsub.Close()
+
+		{
+			msgi, err := pubsub.ReceiveTimeout(ctx, time.Second)
+			Expect(err).NotTo(HaveOccurred())
+			subscr := msgi.(*redis.Subscription)
+			Expect(subscr.Kind).To(Equal("ssubscribe"))
+			Expect(subscr.Channel).To(Equal("mychannel"))
+			Expect(subscr.Count).To(Equal(1))
+		}
+
+		{
+			msgi, err := pubsub.ReceiveTimeout(ctx, time.Second)
+			Expect(err).NotTo(HaveOccurred())
+			subscr := msgi.(*redis.Subscription)
+			Expect(subscr.Kind).To(Equal("ssubscribe"))
+			Expect(subscr.Channel).To(Equal("mychannel2"))
+			Expect(subscr.Count).To(Equal(2))
+		}
+
+		{
+			msgi, err := pubsub.ReceiveTimeout(ctx, time.Second)
+			Expect(err.(net.Error).Timeout()).To(Equal(true))
+			Expect(msgi).NotTo(HaveOccurred())
+		}
+
+		n, err := client.SPublish(ctx, "mychannel", "hello").Result()
+		Expect(err).NotTo(HaveOccurred())
+		Expect(n).To(Equal(int64(1)))
+
+		n, err = client.SPublish(ctx, "mychannel2", "hello2").Result()
+		Expect(err).NotTo(HaveOccurred())
+		Expect(n).To(Equal(int64(1)))
+
+		Expect(pubsub.SUnsubscribe(ctx, "mychannel", "mychannel2")).NotTo(HaveOccurred())
+
+		{
+			msgi, err := pubsub.ReceiveTimeout(ctx, time.Second)
+			Expect(err).NotTo(HaveOccurred())
+			msg := msgi.(*redis.Message)
+			Expect(msg.Channel).To(Equal("mychannel"))
+			Expect(msg.Payload).To(Equal("hello"))
+		}
+
+		{
+			msgi, err := pubsub.ReceiveTimeout(ctx, time.Second)
+			Expect(err).NotTo(HaveOccurred())
+			msg := msgi.(*redis.Message)
+			Expect(msg.Channel).To(Equal("mychannel2"))
+			Expect(msg.Payload).To(Equal("hello2"))
+		}
+
+		{
+			msgi, err := pubsub.ReceiveTimeout(ctx, time.Second)
+			Expect(err).NotTo(HaveOccurred())
+			subscr := msgi.(*redis.Subscription)
+			Expect(subscr.Kind).To(Equal("sunsubscribe"))
+			Expect(subscr.Channel).To(Equal("mychannel"))
+			Expect(subscr.Count).To(Equal(1))
+		}
+
+		{
+			msgi, err := pubsub.ReceiveTimeout(ctx, time.Second)
+			Expect(err).NotTo(HaveOccurred())
+			subscr := msgi.(*redis.Subscription)
+			Expect(subscr.Kind).To(Equal("sunsubscribe"))
+			Expect(subscr.Channel).To(Equal("mychannel2"))
+			Expect(subscr.Count).To(Equal(0))
+		}
+
+		stats := client.PoolStats()
+		Expect(stats.Misses).To(Equal(uint32(1)))
+	})
+
 	It("should ping/pong", func() {
 		pubsub := client.Subscribe(ctx, "mychannel")
 		defer pubsub.Close()

redis.go

@@ -691,6 +691,16 @@ func (c *Client) PSubscribe(ctx context.Context, channels ...string) *PubSub {
 	return pubsub
 }
 
+// SSubscribe Subscribes the client to the specified shard channels.
+// Channels can be omitted to create empty subscription.
+func (c *Client) SSubscribe(ctx context.Context, channels ...string) *PubSub {
+	pubsub := c.pubSub()
+	if len(channels) > 0 {
+		_ = pubsub.SSubscribe(ctx, channels...)
+	}
+	return pubsub
+}
+
 //------------------------------------------------------------------------------
 
 type conn struct {

ring.go

@@ -504,6 +504,19 @@ func (c *Ring) PSubscribe(ctx context.Context, channels ...string) *PubSub {
 	return shard.Client.PSubscribe(ctx, channels...)
 }
 
+// SSubscribe Subscribes the client to the specified shard channels.
+func (c *Ring) SSubscribe(ctx context.Context, channels ...string) *PubSub {
+	if len(channels) == 0 {
+		panic("at least one channel is required")
+	}
+	shard, err := c.shards.GetByKey(channels[0])
+	if err != nil {
+		// TODO: return PubSub with sticky error
+		panic(err)
+	}
+	return shard.Client.SSubscribe(ctx, channels...)
+}
+
 // ForEachShard concurrently calls the fn on each live shard in the ring.
 // It returns the first error if any.
 func (c *Ring) ForEachShard(

universal.go

@@ -190,6 +190,7 @@ type UniversalClient interface {
 	Process(ctx context.Context, cmd Cmder) error
 	Subscribe(ctx context.Context, channels ...string) *PubSub
 	PSubscribe(ctx context.Context, channels ...string) *PubSub
+	SSubscribe(ctx context.Context, channels ...string) *PubSub
 	Close() error
 	PoolStats() *PoolStats
 }