Optimize Do("")

redis/conn.go

@@ -366,6 +366,15 @@ func (c *conn) Receive() (reply interface{}, err error) {
 }
 
 func (c *conn) Do(cmd string, args ...interface{}) (interface{}, error) {
+	c.mu.Lock()
+	pending := c.pending
+	c.pending = 0
+	c.mu.Unlock()
+
+	if cmd == "" && pending == 0 {
+		return nil, nil
+	}
+
 	if c.writeTimeout != 0 {
 		c.conn.SetWriteDeadline(time.Now().Add(c.writeTimeout))
 	}
@@ -378,11 +387,6 @@ func (c *conn) Do(cmd string, args ...interface{}) (interface{}, error) {
 		return nil, c.fatal(err)
 	}
 
-	c.mu.Lock()
-	pending := c.pending
-	c.pending = 0
-	c.mu.Unlock()
-
 	if c.readTimeout != 0 {
 		c.conn.SetReadDeadline(time.Now().Add(c.readTimeout))
 	}