fix rpc client panic cause by concurrent close (#1359)

* fix rpc client panic cause by concurrent close

Signed-off-by: crazycs520 <crazycs520@gmail.com>

* address comment

Signed-off-by: crazycs520 <crazycs520@gmail.com>

* refine

Signed-off-by: crazycs520 <crazycs520@gmail.com>

---------

Signed-off-by: crazycs520 <crazycs520@gmail.com>

internal/client/client.go

@@ -860,6 +860,10 @@ func (c *RPCClient) CloseAddr(addr string) error {
 
 func (c *RPCClient) CloseAddrVer(addr string, ver uint64) error {
 	c.Lock()
+	if c.isClosed {
+		c.Unlock()
+		return nil
+	}
 	conn, ok := c.conns[addr]
 	if ok {
 		if conn.ver <= ver {

internal/client/client_test.go

@@ -1047,3 +1047,23 @@ func TestFastFailWhenNoAvailableConn(t *testing.T) {
 	require.Equal(t, "no available connections", err.Error())
 	require.Less(t, time.Since(start), timeout)
 }
+
+func TestConcurrentCloseConnPanic(t *testing.T) {
+	client := NewRPCClient()
+	addr := "127.0.0.1:6379"
+	_, err := client.getConnArray(addr, true)
+	assert.Nil(t, err)
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		err := client.Close()
+		assert.Nil(t, err)
+	}()
+	go func() {
+		defer wg.Done()
+		err := client.CloseAddr(addr)
+		assert.Nil(t, err)
+	}()
+	wg.Wait()
+}