From 029065eb68819816ef5da0343397d4cefbba7ad0 Mon Sep 17 00:00:00 2001
From: Vladimir Mihailenco <vladimir.webdev@gmail.com>
Date: Mon, 13 Jul 2015 13:45:37 +0300
Subject: [PATCH] Fix nil pool on read timeout. Fixes #135.

---
 conn.go       |  5 ++---
 pool.go       | 34 ++++++++++++++++++++--------------
 redis_test.go | 14 ++++++++++++++
 3 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/conn.go b/conn.go
index bf104d9..9dc2ede 100644
--- a/conn.go
+++ b/conn.go
@@ -42,9 +42,8 @@ func (cn *conn) init(opt *Options) error {
 		return nil
 	}
 
-	// Use connection to connect to redis
-	pool := newSingleConnPool(nil, false)
-	pool.SetConn(cn)
+	// Use connection to connect to Redis.
+	pool := newSingleConnPoolConn(cn)
 
 	// Client is not closed because we want to reuse underlying connection.
 	client := newClient(opt, pool)
diff --git a/pool.go b/pool.go
index 714cbe5..71ac456 100644
--- a/pool.go
+++ b/pool.go
@@ -329,13 +329,10 @@ func newSingleConnPool(pool pool, reusable bool) *singleConnPool {
 	}
 }
 
-func (p *singleConnPool) SetConn(cn *conn) {
-	p.mx.Lock()
-	if p.cn != nil {
-		panic("p.cn != nil")
+func newSingleConnPoolConn(cn *conn) *singleConnPool {
+	return &singleConnPool{
+		cn: cn,
 	}
-	p.cn = cn
-	p.mx.Unlock()
 }
 
 func (p *singleConnPool) First() *conn {
@@ -365,6 +362,14 @@ func (p *singleConnPool) Get() (*conn, error) {
 	return p.cn, nil
 }
 
+func (p *singleConnPool) put() (err error) {
+	if p.pool != nil {
+		err = p.pool.Put(p.cn)
+	}
+	p.cn = nil
+	return err
+}
+
 func (p *singleConnPool) Put(cn *conn) error {
 	defer p.mx.Unlock()
 	p.mx.Lock()
@@ -377,6 +382,14 @@ func (p *singleConnPool) Put(cn *conn) error {
 	return nil
 }
 
+func (p *singleConnPool) remove() (err error) {
+	if p.pool != nil {
+		err = p.pool.Remove(p.cn)
+	}
+	p.cn = nil
+	return err
+}
+
 func (p *singleConnPool) Remove(cn *conn) error {
 	defer p.mx.Unlock()
 	p.mx.Lock()
@@ -392,12 +405,6 @@ func (p *singleConnPool) Remove(cn *conn) error {
 	return p.remove()
 }
 
-func (p *singleConnPool) remove() error {
-	err := p.pool.Remove(p.cn)
-	p.cn = nil
-	return err
-}
-
 func (p *singleConnPool) Len() int {
 	defer p.mx.Unlock()
 	p.mx.Lock()
@@ -426,8 +433,7 @@ func (p *singleConnPool) Close() error {
 	var err error
 	if p.cn != nil {
 		if p.reusable {
-			err = p.pool.Put(p.cn)
-			p.cn = nil
+			err = p.put()
 		} else {
 			err = p.remove()
 		}
diff --git a/redis_test.go b/redis_test.go
index ac5ee7c..3c0d635 100644
--- a/redis_test.go
+++ b/redis_test.go
@@ -134,6 +134,20 @@ var _ = Describe("Client", func() {
 		Expect(db1.FlushDb().Err()).NotTo(HaveOccurred())
 	})
 
+	It("should support DB selection with read timeout (issue #135)", func() {
+		for i := 0; i < 100; i++ {
+			db1 := redis.NewClient(&redis.Options{
+				Addr:        redisAddr,
+				DB:          1,
+				ReadTimeout: time.Nanosecond,
+			})
+
+			err := db1.Ping().Err()
+			Expect(err).To(HaveOccurred())
+			Expect(err.(net.Error).Timeout()).To(BeTrue())
+		}
+	})
+
 	It("should retry command on network error", func() {
 		Expect(client.Close()).NotTo(HaveOccurred())