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()
 	}
-	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 {
-		internal.Logf("info for cmd=%s not found", cmd.arg(0))
+	firstKey := cmd.arg(cmdFirstKeyPos(cmd, cmdInfo))
+	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 {
@@ -330,9 +392,11 @@ func (c *ClusterClient) Process(cmd Cmder) error {
 		var addr string
 		moved, ask, addr = errors.IsMoved(err)
 		if moved || ask {
-			master, _ := c.slotMasterNode(slot)
-			if moved && (master == nil || master.Client.getAddr() != addr) {
-				c.lazyReloadSlots()
+			if slot >= 0 {
+				master, _ := c.slotMasterNode(slot)
+				if moved && (master == nil || master.Client.getAddr() != addr) {
+					c.lazyReloadSlots()
+				}
 			}
 
 			node, err = c.nodeByAddr(addr)
@@ -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 s, ok := cmd._args[pos].(string); ok {
-			return s
-		}
+	if pos < 0 || pos >= len(cmd._args) {
+		return ""
 	}
-	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,
 	}
 }