Rework PubSub conn management

pubsub.go

@@ -20,49 +20,14 @@ type PubSub struct {
 	cn     *pool.Conn
 	closed bool
 
-	cmd *Cmd
-
 	subMu    sync.Mutex
 	channels []string
 	patterns []string
+
+	cmd *Cmd
 }
 
-func (c *PubSub) conn() (*pool.Conn, error) {
-	cn, isNew, err := c._conn()
-	if err != nil {
-		return nil, err
-	}
-
-	if isNew {
-		if err := c.resubscribe(); err != nil {
-			internal.Logf("resubscribe failed: %s", err)
-		}
-	}
-
-	return cn, nil
-}
-
-func (c *PubSub) resubscribe() error {
-	c.subMu.Lock()
-	channels := c.channels
-	patterns := c.patterns
-	c.subMu.Unlock()
-
-	var firstErr error
-	if len(channels) > 0 {
-		if err := c.subscribe("subscribe", channels...); err != nil && firstErr == nil {
-			firstErr = err
-		}
-	}
-	if len(patterns) > 0 {
-		if err := c.subscribe("psubscribe", patterns...); err != nil && firstErr == nil {
-			firstErr = err
-		}
-	}
-	return firstErr
-}
-
-func (c *PubSub) _conn() (*pool.Conn, bool, error) {
+func (c *PubSub) conn() (*pool.Conn, bool, error) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
@@ -86,21 +51,81 @@ func (c *PubSub) _conn() (*pool.Conn, bool, error) {
 		}
 	}
 
+	if err := c.resubscribe(cn); err != nil {
+		return nil, false, err
+	}
+
 	c.cn = cn
 	return cn, true, nil
 }
 
-func (c *PubSub) putConn(cn *pool.Conn, err error) {
-	if internal.IsBadConn(err, true) {
-		c.mu.Lock()
-		if c.cn == cn {
-			_ = c.closeConn()
+func (c *PubSub) resubscribe(cn *pool.Conn) error {
+	c.subMu.Lock()
+	defer c.subMu.Unlock()
+
+	var firstErr error
+	if len(c.channels) > 0 {
+		if err := c._subscribe(cn, "subscribe", c.channels...); err != nil && firstErr == nil {
+			firstErr = err
 		}
-		c.mu.Unlock()
 	}
+	if len(c.patterns) > 0 {
+		if err := c._subscribe(cn, "psubscribe", c.patterns...); err != nil && firstErr == nil {
+			firstErr = err
+		}
+	}
+	return firstErr
+}
+
+func (c *PubSub) putConn(cn *pool.Conn, err error) {
+	if !internal.IsBadConn(err, true) {
+		return
+	}
+
+	c.mu.Lock()
+	if c.cn == cn {
+		_ = c.closeConn()
+	}
+	c.mu.Unlock()
+}
+
+func (c *PubSub) closeConn() error {
+	err := c.base.connPool.CloseConn(c.cn)
+	c.cn = nil
+	return err
+}
+
+func (c *PubSub) Close() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.closed {
+		return pool.ErrClosed
+	}
+	c.closed = true
+
+	if c.cn != nil {
+		return c.closeConn()
+	}
+	return nil
 }
 
 func (c *PubSub) subscribe(redisCmd string, channels ...string) error {
+	cn, isNew, err := c.conn()
+	if err != nil {
+		return err
+	}
+
+	if isNew {
+		return nil
+	}
+
+	err = c._subscribe(cn, redisCmd, channels...)
+	c.putConn(cn, err)
+	return err
+}
+
+func (c *PubSub) _subscribe(cn *pool.Conn, redisCmd string, channels ...string) error {
 	args := make([]interface{}, 1+len(channels))
 	args[0] = redisCmd
 	for i, channel := range channels {
@@ -108,19 +133,8 @@ func (c *PubSub) subscribe(redisCmd string, channels ...string) error {
 	}
 	cmd := NewSliceCmd(args...)
 
-	cn, isNew, err := c._conn()
-	if err != nil {
-		return err
-	}
-
-	if isNew {
-		return c.resubscribe()
-	}
-
 	cn.SetWriteTimeout(c.base.opt.WriteTimeout)
-	err = writeCmd(cn, cmd)
-	c.putConn(cn, err)
-	return err
+	return writeCmd(cn, cmd)
 }
 
 // Subscribes the client to the specified channels.
@@ -157,28 +171,6 @@ func (c *PubSub) PUnsubscribe(patterns ...string) error {
 	return c.subscribe("punsubscribe", patterns...)
 }
 
-func (c *PubSub) Close() error {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
-	if c.closed {
-		return pool.ErrClosed
-	}
-	c.closed = true
-
-	if c.cn != nil {
-		_ = c.closeConn()
-	}
-
-	return nil
-}
-
-func (c *PubSub) closeConn() error {
-	err := c.base.connPool.CloseConn(c.cn)
-	c.cn = nil
-	return err
-}
-
 func (c *PubSub) Ping(payload ...string) error {
 	args := []interface{}{"ping"}
 	if len(payload) == 1 {
@@ -186,7 +178,7 @@ func (c *PubSub) Ping(payload ...string) error {
 	}
 	cmd := NewCmd(args...)
 
-	cn, err := c.conn()
+	cn, _, err := c.conn()
 	if err != nil {
 		return err
 	}
@@ -279,7 +271,7 @@ func (c *PubSub) ReceiveTimeout(timeout time.Duration) (interface{}, error) {
 		c.cmd = NewCmd()
 	}
 
-	cn, err := c.conn()
+	cn, _, err := c.conn()
 	if err != nil {
 		return nil, err
 	}