Add ForEachMaster API.

cluster.go

@@ -13,8 +13,8 @@ import (
 
 type clusterNode struct {
 	Addr    string
-	Latency int
 	Client  *Client
+	Latency time.Duration
 }
 
 // ClusterClient is a Redis Cluster client representing a pool of zero
@@ -73,8 +73,8 @@ func (c *ClusterClient) cmdInfo(name string) *CommandInfo {
 }
 
 func (c *ClusterClient) getNodes() map[string]*clusterNode {
-	c.mu.RLock()
 	var nodes map[string]*clusterNode
+	c.mu.RLock()
 	if !c.closed {
 		nodes = make(map[string]*clusterNode, len(c.nodes))
 		for addr, node := range c.nodes {
@@ -95,7 +95,7 @@ func (c *ClusterClient) Watch(fn func(*Tx) error, keys ...string) error {
 
 // PoolStats returns accumulated connection pool stats.
 func (c *ClusterClient) PoolStats() *PoolStats {
-	acc := PoolStats{}
+	var acc PoolStats
 	for _, node := range c.getNodes() {
 		s := node.Client.connPool.Stats()
 		acc.Requests += s.Requests
@@ -214,7 +214,6 @@ func (c *ClusterClient) slotSlaveNode(slot int) (*clusterNode, error) {
 		n := rand.Intn(len(nodes)-1) + 1
 		return nodes[n], nil
 	}
-
 }
 
 func (c *ClusterClient) slotClosestNode(slot int) (*clusterNode, error) {
@@ -261,19 +260,19 @@ func (c *ClusterClient) cmdSlotAndNode(cmd Cmder) (int, *clusterNode, error) {
 	return slot, node, err
 }
 
-func (c *ClusterClient) Process(cmd Cmder) {
-	var ask bool
+func (c *ClusterClient) Process(cmd Cmder) error {
 	slot, node, err := c.cmdSlotAndNode(cmd)
+	if err != nil {
+		cmd.setErr(err)
+		return err
+	}
+
+	var ask bool
 	for attempt := 0; attempt <= c.opt.MaxRedirects; attempt++ {
 		if attempt > 0 {
 			cmd.reset()
 		}
 
-		if err != nil {
-			cmd.setErr(err)
-			return
-		}
-
 		if ask {
 			pipe := node.Client.Pipeline()
 			pipe.Process(NewCmd("ASKING"))
@@ -288,7 +287,7 @@ func (c *ClusterClient) Process(cmd Cmder) {
 		// If there is no (real) error, we are done!
 		err := cmd.Err()
 		if err == nil {
-			return
+			return nil
 		}
 
 		// On network errors try random node.
@@ -307,11 +306,58 @@ func (c *ClusterClient) Process(cmd Cmder) {
 			}
 
 			node, err = c.nodeByAddr(addr)
+			if err != nil {
+				cmd.setErr(err)
+				return err
+			}
 			continue
 		}
 
 		break
 	}
+
+	return cmd.Err()
+}
+
+// ForEachMaster concurrently calls the fn on each master node in the cluster.
+// It returns the first error if any.
+func (c *ClusterClient) ForEachMaster(fn func(client *Client) error) error {
+	c.mu.RLock()
+	slots := c.slots
+	c.mu.RUnlock()
+
+	var retErr error
+	var mu sync.Mutex
+
+	var wg sync.WaitGroup
+	visited := make(map[*clusterNode]struct{})
+	for _, nodes := range slots {
+		if len(nodes) == 0 {
+			continue
+		}
+
+		master := nodes[0]
+		if _, ok := visited[master]; ok {
+			continue
+		}
+		visited[master] = struct{}{}
+
+		wg.Add(1)
+		go func(node *clusterNode) {
+			err := fn(node.Client)
+			if err != nil {
+				mu.Lock()
+				if retErr == nil {
+					retErr = err
+				}
+				mu.Unlock()
+			}
+			wg.Done()
+		}(master)
+	}
+	wg.Wait()
+
+	return retErr
 }
 
 // closeClients closes all clients and returns the first error if there are any.
@@ -327,9 +373,6 @@ func (c *ClusterClient) closeClients() error {
 
 func (c *ClusterClient) setSlots(cs []ClusterSlot) {
 	slots := make([][]*clusterNode, hashtag.SlotNumber)
-	for i := 0; i < hashtag.SlotNumber; i++ {
-		slots[i] = nil
-	}
 	for _, s := range cs {
 		var nodes []*clusterNode
 		for _, n := range s.Nodes {
@@ -351,17 +394,11 @@ func (c *ClusterClient) setSlots(cs []ClusterSlot) {
 	c.mu.Unlock()
 }
 
-func (c *ClusterClient) setNodesLatency() {
-	nodes := c.getNodes()
-	for _, node := range nodes {
-		var latency int
-		for i := 0; i < 10; i++ {
-			t1 := time.Now()
-			node.Client.Ping()
-			latency += int(time.Since(t1) / time.Millisecond)
-		}
-		node.Latency = latency
+func (c *ClusterClient) lazyReloadSlots() {
+	if !atomic.CompareAndSwapUint32(&c.reloading, 0, 1) {
+		return
 	}
+	go c.reloadSlots()
 }
 
 func (c *ClusterClient) reloadSlots() {
@@ -384,11 +421,17 @@ func (c *ClusterClient) reloadSlots() {
 	}
 }
 
-func (c *ClusterClient) lazyReloadSlots() {
-	if !atomic.CompareAndSwapUint32(&c.reloading, 0, 1) {
-		return
+func (c *ClusterClient) setNodesLatency() {
+	const n = 10
+	for _, node := range c.getNodes() {
+		var latency time.Duration
+		for i := 0; i < n; i++ {
+			t1 := time.Now()
+			node.Client.Ping()
+			latency += time.Since(t1)
+		}
+		node.Latency = latency / n
 	}
-	go c.reloadSlots()
 }
 
 // reaper closes idle connections to the cluster.
@@ -435,7 +478,7 @@ func (c *ClusterClient) Pipelined(fn func(*Pipeline) error) ([]Cmder, error) {
 
 func (c *ClusterClient) pipelineExec(cmds []Cmder) error {
 	var retErr error
-	returnError := func(err error) {
+	setRetErr := func(err error) {
 		if retErr == nil {
 			retErr = err
 		}
@@ -446,7 +489,7 @@ func (c *ClusterClient) pipelineExec(cmds []Cmder) error {
 		_, node, err := c.cmdSlotAndNode(cmd)
 		if err != nil {
 			cmd.setErr(err)
-			returnError(err)
+			setRetErr(err)
 			continue
 		}
 		cmdsMap[node] = append(cmdsMap[node], cmd)
@@ -461,21 +504,21 @@ func (c *ClusterClient) pipelineExec(cmds []Cmder) error {
 				node, err = c.randomNode()
 				if err != nil {
 					setCmdsErr(cmds, err)
-					returnError(err)
+					setRetErr(err)
 					continue
 				}
 			}
 
 			cn, err := node.Client.conn()
 			if err != nil {
-				setCmdsErr(cmds, retErr)
-				returnError(err)
+				setCmdsErr(cmds, err)
+				setRetErr(err)
 				continue
 			}
 
 			failedCmds, err = c.execClusterCmds(cn, cmds, failedCmds)
 			if err != nil {
-				returnError(err)
+				setRetErr(err)
 			}
 			node.Client.putConn(cn, err, false)
 		}
@@ -495,7 +538,7 @@ func (c *ClusterClient) execClusterCmds(
 	}
 
 	var retErr error
-	returnError := func(err error) {
+	setRetErr := func(err error) {
 		if retErr == nil {
 			retErr = err
 		}
@@ -515,7 +558,7 @@ func (c *ClusterClient) execClusterCmds(
 			cmd.reset()
 			node, err := c.nodeByAddr(addr)
 			if err != nil {
-				returnError(err)
+				setRetErr(err)
 				continue
 			}
 			failedCmds[node] = append(failedCmds[node], cmd)
@@ -523,12 +566,12 @@ func (c *ClusterClient) execClusterCmds(
 			cmd.reset()
 			node, err := c.nodeByAddr(addr)
 			if err != nil {
-				returnError(err)
+				setRetErr(err)
 				continue
 			}
 			failedCmds[node] = append(failedCmds[node], NewCmd("ASKING"), cmd)
 		} else {
-			returnError(err)
+			setRetErr(err)
 		}
 	}
 

cluster_test.go

@@ -336,11 +336,11 @@ var _ = Describe("ClusterClient", func() {
 			Expect(cnt).To(Equal(int64(1)))
 		})
 
-		It("should return pool stats", func() {
+		It("returns pool stats", func() {
 			Expect(client.PoolStats()).To(BeAssignableToTypeOf(&redis.PoolStats{}))
 		})
 
-		It("should follow redirects", func() {
+		It("follows redirects", func() {
 			Expect(client.Set("A", "VALUE", 0).Err()).NotTo(HaveOccurred())
 
 			slot := hashtag.Slot("A")
@@ -351,7 +351,7 @@ var _ = Describe("ClusterClient", func() {
 			Expect(val).To(Equal("VALUE"))
 		})
 
-		It("should return error when there are no attempts left", func() {
+		It("returns an error when there are no attempts left", func() {
 			client := cluster.clusterClient(&redis.ClusterOptions{
 				MaxRedirects: -1,
 			})
@@ -366,7 +366,7 @@ var _ = Describe("ClusterClient", func() {
 			Expect(client.Close()).NotTo(HaveOccurred())
 		})
 
-		It("should Watch", func() {
+		It("supports Watch", func() {
 			var incr func(string) error
 
 			// Transactionally increments key using GET and SET commands.
@@ -461,17 +461,35 @@ var _ = Describe("ClusterClient", func() {
 			Expect(c.Err()).NotTo(HaveOccurred())
 			Expect(c.Val()).To(Equal("C_value"))
 		})
+
+		It("calls fn for every master node", func() {
+			for i := 0; i < 10; i++ {
+				Expect(client.Set(strconv.Itoa(i), "", 0).Err()).NotTo(HaveOccurred())
+			}
+
+			err := client.ForEachMaster(func(master *redis.Client) error {
+				return master.FlushDb().Err()
+			})
+			Expect(err).NotTo(HaveOccurred())
+
+			for _, client := range cluster.masters() {
+				keys, err := client.Keys("*").Result()
+				Expect(err).NotTo(HaveOccurred())
+				Expect(keys).To(HaveLen(0))
+			}
+		})
 	}
 
 	Describe("default ClusterClient", func() {
 		BeforeEach(func() {
 			client = cluster.clusterClient(nil)
+
+			_ = client.ForEachMaster(func(master *redis.Client) error {
+				return master.FlushDb().Err()
+			})
 		})
 
 		AfterEach(func() {
-			for _, client := range cluster.masters() {
-				Expect(client.FlushDb().Err()).NotTo(HaveOccurred())
-			}
 			Expect(client.Close()).NotTo(HaveOccurred())
 		})
 
@@ -483,12 +501,14 @@ var _ = Describe("ClusterClient", func() {
 			client = cluster.clusterClient(&redis.ClusterOptions{
 				RouteByLatency: true,
 			})
+
+			_ = client.ForEachMaster(func(master *redis.Client) error {
+				return master.FlushDb().Err()
+			})
 		})
 
 		AfterEach(func() {
-			for _, client := range cluster.masters() {
-				Expect(client.FlushDb().Err()).NotTo(HaveOccurred())
-			}
+			client.FlushDb()
 			Expect(client.Close()).NotTo(HaveOccurred())
 		})
 

command.go

@@ -31,6 +31,7 @@ var (
 type Cmder interface {
 	args() []interface{}
 	arg(int) string
+
 	readReply(*pool.Conn) error
 	setErr(error)
 	reset()
@@ -142,7 +143,9 @@ type Cmd struct {
 }
 
 func NewCmd(args ...interface{}) *Cmd {
-	return &Cmd{baseCmd: newBaseCmd(args)}
+	return &Cmd{
+		baseCmd: newBaseCmd(args),
+	}
 }
 
 func (cmd *Cmd) reset() {

commands.go

@@ -52,11 +52,11 @@ func formatSec(dur time.Duration) string {
 }
 
 type cmdable struct {
-	process func(cmd Cmder)
+	process func(cmd Cmder) error
 }
 
 type statefulCmdable struct {
-	process func(cmd Cmder)
+	process func(cmd Cmder) error
 }
 
 //------------------------------------------------------------------------------

pipeline.go

@@ -22,10 +22,11 @@ type Pipeline struct {
 	closed int32
 }
 
-func (pipe *Pipeline) Process(cmd Cmder) {
+func (pipe *Pipeline) Process(cmd Cmder) error {
 	pipe.mu.Lock()
 	pipe.cmds = append(pipe.cmds, cmd)
 	pipe.mu.Unlock()
+	return nil
 }
 
 // Close closes the pipeline, releasing any open resources.

redis.go

@@ -74,7 +74,7 @@ func (c *baseClient) initConn(cn *pool.Conn) error {
 	return err
 }
 
-func (c *baseClient) Process(cmd Cmder) {
+func (c *baseClient) Process(cmd Cmder) error {
 	for i := 0; i <= c.opt.MaxRetries; i++ {
 		if i > 0 {
 			cmd.reset()
@@ -83,7 +83,7 @@ func (c *baseClient) Process(cmd Cmder) {
 		cn, err := c.conn()
 		if err != nil {
 			cmd.setErr(err)
-			return
+			return err
 		}
 
 		readTimeout := cmd.readTimeout()
@@ -100,7 +100,7 @@ func (c *baseClient) Process(cmd Cmder) {
 			if err != nil && shouldRetry(err) {
 				continue
 			}
-			return
+			return err
 		}
 
 		err = cmd.readReply(cn)
@@ -109,8 +109,10 @@ func (c *baseClient) Process(cmd Cmder) {
 			continue
 		}
 
-		return
+		return err
 	}
+
+	return cmd.Err()
 }
 
 func (c *baseClient) closed() bool {

ring.go

@@ -199,13 +199,13 @@ func (ring *Ring) getClient(key string) (*Client, error) {
 	return cl, nil
 }
 
-func (ring *Ring) Process(cmd Cmder) {
+func (ring *Ring) Process(cmd Cmder) error {
 	cl, err := ring.getClient(ring.cmdFirstKey(cmd))
 	if err != nil {
 		cmd.setErr(err)
-		return
+		return err
 	}
-	cl.baseClient.Process(cmd)
+	return cl.baseClient.Process(cmd)
 }
 
 // rebalance removes dead shards from the ring.

tx.go

@@ -50,12 +50,12 @@ func (c *Client) Watch(fn func(*Tx) error, keys ...string) error {
 	return retErr
 }
 
-func (tx *Tx) Process(cmd Cmder) {
+func (tx *Tx) Process(cmd Cmder) error {
 	if tx.cmds == nil {
-		tx.baseClient.Process(cmd)
-	} else {
-		tx.cmds = append(tx.cmds, cmd)
+		return tx.baseClient.Process(cmd)
 	}
+	tx.cmds = append(tx.cmds, cmd)
+	return nil
 }
 
 // close closes the transaction, releasing any open resources.