Add more race tests

cluster.go

@@ -220,7 +220,7 @@ type clusterNodes struct {
 
 	nodeCreateGroup singleflight.Group
 
-	generation uint32
+	_generation uint32 // atomic
 }
 
 func newClusterNodes(opt *ClusterOptions) *clusterNodes {
@@ -277,8 +277,7 @@ func (c *clusterNodes) Addrs() ([]string, error) {
 }
 
 func (c *clusterNodes) NextGeneration() uint32 {
-	c.generation++
-	return c.generation
+	return atomic.AddUint32(&c._generation, 1)
 }
 
 // GC removes unused nodes.

cluster_test.go

@@ -519,8 +519,7 @@ var _ = Describe("ClusterClient", func() {
 			Expect(err).NotTo(HaveOccurred())
 			Expect(res).To(HaveLen(3))
 
-			wanted := []redis.ClusterSlot{
-				{
+			wanted := []redis.ClusterSlot{{
 				Start: 0,
 				End:   4999,
 				Nodes: []redis.ClusterNode{{
@@ -550,8 +549,7 @@ var _ = Describe("ClusterClient", func() {
 					Id:   "",
 					Addr: "127.0.0.1:8225",
 				}},
-				},
-			}
+			}}
 			Expect(assertSlotsEqual(res, wanted)).NotTo(HaveOccurred())
 		})
 
@@ -634,16 +632,18 @@ var _ = Describe("ClusterClient", func() {
 			opt.MaxRetryBackoff = time.Second
 			client = cluster.clusterClient(opt)
 
-			_ = client.ForEachSlave(func(slave *redis.Client) error {
-				defer GinkgoRecover()
-
-				_ = client.ForEachMaster(func(master *redis.Client) error {
+			err := client.ForEachMaster(func(master *redis.Client) error {
 				return master.FlushDB().Err()
 			})
+			Expect(err).NotTo(HaveOccurred())
+
+			_ = client.ForEachSlave(func(slave *redis.Client) error {
+				defer GinkgoRecover()
 
 				Eventually(func() int64 {
 					return slave.DBSize().Val()
 				}, 30*time.Second).Should(Equal(int64(0)))
+
 				return slave.ClusterFailover().Err()
 			})
 		})

commands_test.go

@@ -219,7 +219,7 @@ var _ = Describe("Commands", func() {
 		It("Should Command", func() {
 			cmds, err := client.Command().Result()
 			Expect(err).NotTo(HaveOccurred())
-			Expect(len(cmds)).To(BeNumerically("~", 185, 10))
+			Expect(len(cmds)).To(BeNumerically("~", 200, 20))
 
 			cmd := cmds["mget"]
 			Expect(cmd.Name).To(Equal("mget"))

race_test.go

@@ -316,6 +316,16 @@ var _ = Describe("cluster races", func() {
 		})
 	})
 
+	It("should get", func() {
+		perform(C, func(id int) {
+			for i := 0; i < N; i++ {
+				key := fmt.Sprintf("key_%d_%d", id, i)
+				_, err := client.Get(key).Result()
+				Expect(err).To(Equal(redis.Nil))
+			}
+		})
+	})
+
 	It("should incr", func() {
 		key := "TestIncrFromGoroutines"