Select random node when there are no keys.

cluster.go

@@ -12,6 +12,72 @@ import (
 	"gopkg.in/redis.v4/internal/pool"
 )
 
+// ClusterOptions are used to configure a cluster client and should be
+// passed to NewClusterClient.
+type ClusterOptions struct {
+	// A seed list of host:port addresses of cluster nodes.
+	Addrs []string
+
+	// The maximum number of retries before giving up. Command is retried
+	// on network errors and MOVED/ASK redirects.
+	// Default is 16.
+	MaxRedirects int
+
+	// Enables read queries for a connection to a Redis Cluster slave node.
+	ReadOnly bool
+
+	// Enables routing read-only queries to the closest master or slave node.
+	RouteByLatency bool
+
+	// Following options are copied from Options struct.
+
+	Password string
+
+	DialTimeout  time.Duration
+	ReadTimeout  time.Duration
+	WriteTimeout time.Duration
+
+	// PoolSize applies per cluster node and not for the whole cluster.
+	PoolSize           int
+	PoolTimeout        time.Duration
+	IdleTimeout        time.Duration
+	IdleCheckFrequency time.Duration
+}
+
+func (opt *ClusterOptions) init() {
+	if opt.MaxRedirects == -1 {
+		opt.MaxRedirects = 0
+	} else if opt.MaxRedirects == 0 {
+		opt.MaxRedirects = 16
+	}
+
+	if opt.RouteByLatency {
+		opt.ReadOnly = true
+	}
+}
+
+func (opt *ClusterOptions) clientOptions() *Options {
+	const disableIdleCheck = -1
+
+	return &Options{
+		Password: opt.Password,
+		ReadOnly: opt.ReadOnly,
+
+		DialTimeout:  opt.DialTimeout,
+		ReadTimeout:  opt.ReadTimeout,
+		WriteTimeout: opt.WriteTimeout,
+
+		PoolSize:    opt.PoolSize,
+		PoolTimeout: opt.PoolTimeout,
+		IdleTimeout: opt.IdleTimeout,
+
+		// IdleCheckFrequency is not copied to disable reaper
+		IdleCheckFrequency: disableIdleCheck,
+	}
+}
+
+//------------------------------------------------------------------------------
+
 type clusterNode struct {
 	Client  *Client
 	Latency time.Duration
@@ -36,8 +102,8 @@ type ClusterClient struct {
 	slots  [][]*clusterNode
 	closed bool
 
-	cmdsInfo     map[string]*CommandInfo
 	cmdsInfoOnce *sync.Once
+	cmdsInfo     map[string]*CommandInfo
 
 	// Reports where slots reloading is in progress.
 	reloading uint32
@@ -81,19 +147,22 @@ func (c *ClusterClient) cmdInfo(name string) *CommandInfo {
 		}
 		c.cmdsInfoOnce = &sync.Once{}
 	})
+	if c.cmdsInfo == nil {
+		return nil
+	}
 	return c.cmdsInfo[name]
 }
 
 func (c *ClusterClient) getNodes() map[string]*clusterNode {
 	var nodes map[string]*clusterNode
-	c.mu.RLock()
 	if !c.closed {
 		nodes = make(map[string]*clusterNode, len(c.nodes))
+		c.mu.RLock()
 		for addr, node := range c.nodes {
 			nodes[addr] = node
 		}
-	}
 		c.mu.RUnlock()
+	}
 	return nodes
 }
 
@@ -257,18 +326,11 @@ func (c *ClusterClient) slotClosestNode(slot int) (*clusterNode, error) {
 
 func (c *ClusterClient) cmdSlotAndNode(cmd Cmder) (int, *clusterNode, error) {
 	cmdInfo := c.cmdInfo(cmd.arg(0))
-	if cmdInfo == nil {
+	firstKey := cmd.arg(cmdFirstKeyPos(cmd, cmdInfo))
-		internal.Logf("info for cmd=%s not found", cmd.arg(0))
+	if firstKey == "" {
 		node, err := c.randomNode()
-		return 0, node, err
+		return -1, node, err
 	}
-
-	if cmdInfo.FirstKeyPos == -1 {
-		node, err := c.randomNode()
-		return 0, node, err
-	}
-
-	firstKey := cmd.arg(int(cmdInfo.FirstKeyPos))
 	slot := hashtag.Slot(firstKey)
 
 	if cmdInfo.ReadOnly && c.opt.ReadOnly {
@@ -330,10 +392,12 @@ func (c *ClusterClient) Process(cmd Cmder) error {
 		var addr string
 		moved, ask, addr = errors.IsMoved(err)
 		if moved || ask {
+			if slot >= 0 {
 				master, _ := c.slotMasterNode(slot)
 				if moved && (master == nil || master.Client.getAddr() != addr) {
 					c.lazyReloadSlots()
 				}
+			}
 
 			node, err = c.nodeByAddr(addr)
 			if err != nil {
@@ -609,69 +673,3 @@ func (c *ClusterClient) execClusterCmds(
 
 	return failedCmds, retErr
 }
-
-//------------------------------------------------------------------------------
-
-// ClusterOptions are used to configure a cluster client and should be
-// passed to NewClusterClient.
-type ClusterOptions struct {
-	// A seed list of host:port addresses of cluster nodes.
-	Addrs []string
-
-	// The maximum number of retries before giving up. Command is retried
-	// on network errors and MOVED/ASK redirects.
-	// Default is 16.
-	MaxRedirects int
-
-	// Enables read queries for a connection to a Redis Cluster slave node.
-	ReadOnly bool
-
-	// Enables routing read-only queries to the closest master or slave node.
-	RouteByLatency bool
-
-	// Following options are copied from Options struct.
-
-	Password string
-
-	DialTimeout  time.Duration
-	ReadTimeout  time.Duration
-	WriteTimeout time.Duration
-
-	// PoolSize applies per cluster node and not for the whole cluster.
-	PoolSize           int
-	PoolTimeout        time.Duration
-	IdleTimeout        time.Duration
-	IdleCheckFrequency time.Duration
-}
-
-func (opt *ClusterOptions) init() {
-	if opt.MaxRedirects == -1 {
-		opt.MaxRedirects = 0
-	} else if opt.MaxRedirects == 0 {
-		opt.MaxRedirects = 16
-	}
-
-	if opt.RouteByLatency {
-		opt.ReadOnly = true
-	}
-}
-
-func (opt *ClusterOptions) clientOptions() *Options {
-	const disableIdleCheck = -1
-
-	return &Options{
-		Password: opt.Password,
-		ReadOnly: opt.ReadOnly,
-
-		DialTimeout:  opt.DialTimeout,
-		ReadTimeout:  opt.ReadTimeout,
-		WriteTimeout: opt.WriteTimeout,
-
-		PoolSize:    opt.PoolSize,
-		PoolTimeout: opt.PoolTimeout,
-		IdleTimeout: opt.IdleTimeout,
-
-		// IdleCheckFrequency is not copied to disable reaper
-		IdleCheckFrequency: disableIdleCheck,
-	}
-}

command.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/go-redis/redis/internal"
+
 	"gopkg.in/redis.v4/internal/pool"
 	"gopkg.in/redis.v4/internal/proto"
 )
@@ -88,6 +90,22 @@ func cmdString(cmd Cmder, val interface{}) string {
 
 }
 
+func cmdFirstKeyPos(cmd Cmder, info *CommandInfo) int {
+	switch cmd.arg(0) {
+	case "eval", "evalsha":
+		if cmd.arg(2) != "0" {
+			return 3
+		} else {
+			return 0
+		}
+	}
+	if info == nil {
+		internal.Logf("info for cmd=%s not found", cmd.arg(0))
+		return -1
+	}
+	return int(info.FirstKeyPos)
+}
+
 //------------------------------------------------------------------------------
 
 type baseCmd struct {
@@ -109,12 +127,11 @@ func (cmd *baseCmd) args() []interface{} {
 }
 
 func (cmd *baseCmd) arg(pos int) string {
-	if len(cmd._args) > pos {
+	if pos < 0 || pos >= len(cmd._args) {
-		if s, ok := cmd._args[pos].(string); ok {
-			return s
-		}
-	}
 		return ""
+	}
+	s, _ := cmd._args[pos].(string)
+	return s
 }
 
 func (cmd *baseCmd) readTimeout() *time.Duration {

main_test.go

@@ -138,7 +138,6 @@ func redisRingOptions() *redis.RingOptions {
 		PoolTimeout:        30 * time.Second,
 		IdleTimeout:        500 * time.Millisecond,
 		IdleCheckFrequency: 500 * time.Millisecond,
-		RouteByEvalKeys:    true,
 	}
 }
 

ring.go

@@ -3,6 +3,8 @@ package redis
 import (
 	"errors"
 	"fmt"
+	"math/rand"
+	"strconv"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -40,9 +42,6 @@ type RingOptions struct {
 	PoolTimeout        time.Duration
 	IdleTimeout        time.Duration
 	IdleCheckFrequency time.Duration
-
-	// RouteByEvalKeys flag to enable eval and evalsha key position parsing for sharding
-	RouteByEvalKeys bool
 }
 
 func (opt *RingOptions) init() {
@@ -131,12 +130,10 @@ type Ring struct {
 	hash   *consistenthash.Map
 	shards map[string]*ringShard
 
-	cmdsInfo     map[string]*CommandInfo
 	cmdsInfoOnce *sync.Once
+	cmdsInfo     map[string]*CommandInfo
 
 	closed bool
-
-	routeByEvalKeys bool
 }
 
 var _ Cmdable = (*Ring)(nil)
@@ -159,7 +156,6 @@ func NewRing(opt *RingOptions) *Ring {
 		clopt.Addr = addr
 		ring.addClient(name, NewClient(clopt))
 	}
-	ring.routeByEvalKeys = opt.RouteByEvalKeys
 	go ring.heartbeat()
 	return ring
 }
@@ -227,30 +223,6 @@ func (c *Ring) cmdInfo(name string) *CommandInfo {
 	return c.cmdsInfo[name]
 }
 
-func (c *Ring) getEvalFirstKey(cmd Cmder) string {
-	if c.routeByEvalKeys && cmd.arg(2) != "0" {
-		return cmd.arg(3)
-	} else {
-		return cmd.arg(0)
-	}
-}
-
-func (c *Ring) cmdFirstKey(cmd Cmder) string {
-	switch cmd.arg(0) {
-	case "eval":
-		return c.getEvalFirstKey(cmd)
-	case "evalsha":
-		return c.getEvalFirstKey(cmd)
-	}
-
-	cmdInfo := c.cmdInfo(cmd.arg(0))
-	if cmdInfo == nil {
-		internal.Logf("info for cmd=%s not found", cmd.arg(0))
-		return ""
-	}
-	return cmd.arg(int(cmdInfo.FirstKeyPos))
-}
-
 func (c *Ring) addClient(name string, cl *Client) {
 	c.mu.Lock()
 	c.hash.Add(name)
@@ -258,14 +230,17 @@ func (c *Ring) addClient(name string, cl *Client) {
 	c.mu.Unlock()
 }
 
-func (c *Ring) getClient(key string) (*Client, error) {
+func (c *Ring) shardByKey(key string) (*Client, error) {
+	key = hashtag.Key(key)
+
 	c.mu.RLock()
 
 	if c.closed {
+		c.mu.RUnlock()
 		return nil, pool.ErrClosed
 	}
 
-	name := c.hash.Get(hashtag.Key(key))
+	name := c.hash.Get(key)
 	if name == "" {
 		c.mu.RUnlock()
 		return nil, errRingShardsDown
@@ -276,8 +251,32 @@ func (c *Ring) getClient(key string) (*Client, error) {
 	return cl, nil
 }
 
+func (c *Ring) randomShard() (*Client, error) {
+	return c.shardByKey(strconv.Itoa(rand.Int()))
+}
+
+func (c *Ring) shardByName(name string) (*Client, error) {
+	if name == "" {
+		return c.randomShard()
+	}
+
+	c.mu.RLock()
+	cl := c.shards[name].Client
+	c.mu.RUnlock()
+	return cl, nil
+}
+
+func (c *Ring) cmdShard(cmd Cmder) (*Client, error) {
+	cmdInfo := c.cmdInfo(cmd.arg(0))
+	firstKey := cmd.arg(cmdFirstKeyPos(cmd, cmdInfo))
+	if firstKey == "" {
+		return c.randomShard()
+	}
+	return c.shardByKey(firstKey)
+}
+
 func (c *Ring) Process(cmd Cmder) error {
-	cl, err := c.getClient(c.cmdFirstKey(cmd))
+	cl, err := c.cmdShard(cmd)
 	if err != nil {
 		cmd.setErr(err)
 		return err
@@ -285,17 +284,18 @@ func (c *Ring) Process(cmd Cmder) error {
 	return cl.baseClient.Process(cmd)
 }
 
-// rebalance removes dead shards from the c.
+// rebalance removes dead shards from the Ring.
 func (c *Ring) rebalance() {
-	defer c.mu.Unlock()
+	hash := consistenthash.New(c.nreplicas, nil)
-	c.mu.Lock()
-
-	c.hash = consistenthash.New(c.nreplicas, nil)
 	for name, shard := range c.shards {
 		if shard.IsUp() {
-			c.hash.Add(name)
+			hash.Add(name)
 		}
 	}
+
+	c.mu.Lock()
+	c.hash = hash
+	c.mu.Unlock()
 }
 
 // heartbeat monitors state of each shard in the ring.
@@ -370,13 +370,10 @@ func (c *Ring) pipelineExec(cmds []Cmder) error {
 
 	cmdsMap := make(map[string][]Cmder)
 	for _, cmd := range cmds {
-		name := c.hash.Get(hashtag.Key(c.cmdFirstKey(cmd)))
+		cmdInfo := c.cmdInfo(cmd.arg(0))
-		if name == "" {
+		name := cmd.arg(cmdFirstKeyPos(cmd, cmdInfo))
-			cmd.setErr(errRingShardsDown)
+		if name != "" {
-			if retErr == nil {
+			name = c.hash.Get(hashtag.Key(name))
-				retErr = errRingShardsDown
-			}
-			continue
 		}
 		cmdsMap[name] = append(cmdsMap[name], cmd)
 	}
@@ -385,7 +382,15 @@ func (c *Ring) pipelineExec(cmds []Cmder) error {
 		failedCmdsMap := make(map[string][]Cmder)
 
 		for name, cmds := range cmdsMap {
-			client := c.shards[name].Client
+			client, err := c.shardByName(name)
+			if err != nil {
+				setCmdsErr(cmds, err)
+				if retErr == nil {
+					retErr = err
+				}
+				continue
+			}
+
 			cn, _, err := client.conn()
 			if err != nil {
 				setCmdsErr(cmds, err)