Merge branch 'master' into v9

Signed-off-by: monkey <golang@88.com>

cluster.go

@@ -68,6 +68,9 @@ type ClusterOptions struct {
 	ReadTimeout  time.Duration
 	WriteTimeout time.Duration
 
+	// PoolFIFO uses FIFO mode for each node connection pool GET/PUT (default LIFO).
+	PoolFIFO bool
+
 	// PoolSize applies per cluster node and not for the whole cluster.
 	PoolSize           int
 	MinIdleConns       int
@@ -146,6 +149,7 @@ func (opt *ClusterOptions) clientOptions() *Options {
 		ReadTimeout:  opt.ReadTimeout,
 		WriteTimeout: opt.WriteTimeout,
 
+		PoolFIFO:           opt.PoolFIFO,
 		PoolSize:           opt.PoolSize,
 		MinIdleConns:       opt.MinIdleConns,
 		MaxConnAge:         opt.MaxConnAge,
@@ -591,8 +595,16 @@ func (c *clusterState) slotRandomNode(slot int) (*clusterNode, error) {
 	if len(nodes) == 0 {
 		return c.nodes.Random()
 	}
-	n := rand.Intn(len(nodes))
-	return nodes[n], nil
+	if len(nodes) == 1 {
+		return nodes[0], nil
+	}
+	randomNodes := rand.Perm(len(nodes))
+	for _, idx := range randomNodes {
+		if node := nodes[idx]; !node.Failing() {
+			return node, nil
+		}
+	}
+	return nodes[randomNodes[0]], nil
 }
 
 func (c *clusterState) slotNodes(slot int) []*clusterNode {