From 316917d99f6c31c77647e82e11cae046747e5069 Mon Sep 17 00:00:00 2001
From: Vladimir Mihailenco <vladimir.webdev@gmail.com>
Date: Tue, 7 Aug 2018 10:33:07 +0300
Subject: [PATCH] pubsub: log an error on reconnect

---
 pubsub.go | 42 +++++++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/pubsub.go b/pubsub.go
index 546c234..5e2a863 100644
--- a/pubsub.go
+++ b/pubsub.go
@@ -131,24 +131,27 @@ func (c *PubSub) _releaseConn(cn *pool.Conn, err error, allowTimeout bool) {
 		return
 	}
 	if internal.IsBadConn(err, allowTimeout) {
-		c._reconnect()
+		c._reconnect(err)
 	}
 }
 
-func (c *PubSub) _closeTheCn() error {
-	var err error
-	if c.cn != nil {
-		err = c.closeConn(c.cn)
-		c.cn = nil
-	}
-	return err
-}
-
-func (c *PubSub) _reconnect() {
-	_ = c._closeTheCn()
+func (c *PubSub) _reconnect(reason error) {
+	_ = c._closeTheCn(reason)
 	_, _ = c._conn(nil)
 }
 
+func (c *PubSub) _closeTheCn(reason error) error {
+	if c.cn == nil {
+		return nil
+	}
+	if !c.closed {
+		internal.Logf("redis: discarding bad PubSub connection: %s", reason)
+	}
+	err := c.closeConn(c.cn)
+	c.cn = nil
+	return err
+}
+
 func (c *PubSub) Close() error {
 	c.mu.Lock()
 	defer c.mu.Unlock()
@@ -159,7 +162,7 @@ func (c *PubSub) Close() error {
 	c.closed = true
 	close(c.exit)
 
-	err := c._closeTheCn()
+	err := c._closeTheCn(pool.ErrClosed)
 	return err
 }
 
@@ -432,22 +435,23 @@ func (c *PubSub) initChannel() {
 		timer := time.NewTimer(timeout)
 		timer.Stop()
 
-		var hasPing bool
+		var healthy bool
+		var pingErr error
 		for {
 			timer.Reset(timeout)
 			select {
 			case <-c.ping:
-				hasPing = true
+				healthy = true
 				if !timer.Stop() {
 					<-timer.C
 				}
 			case <-timer.C:
-				if hasPing {
-					hasPing = false
-					_ = c.Ping()
+				if healthy {
+					healthy = false
+					pingErr = c.Ping()
 				} else {
 					c.mu.Lock()
-					c._reconnect()
+					c._reconnect(pingErr)
 					c.mu.Unlock()
 				}
 			case <-c.exit: