Use PubSub.Channel to not burn CPU on errors

example_test.go

@@ -20,7 +20,6 @@ func init() {
 		PoolSize:     10,
 		PoolTimeout:  30 * time.Second,
 	})
-	//	redisdb.FlushDB()
 }
 
 func ExampleNewClient() {

pubsub.go

@@ -51,7 +51,6 @@ func (c *PubSub) _conn(newChannels []string) (*pool.Conn, error) {
 	if c.closed {
 		return nil, pool.ErrClosed
 	}
-
 	if c.cn != nil {
 		return c.cn, nil
 	}

sentinel.go

@@ -119,7 +119,7 @@ func NewSentinelClient(opt *Options) *SentinelClient {
 	return c
 }
 
-func (c *SentinelClient) PubSub() *PubSub {
+func (c *SentinelClient) pubSub() *PubSub {
 	pubsub := &PubSub{
 		opt: c.opt,
 
@@ -132,14 +132,34 @@ func (c *SentinelClient) PubSub() *PubSub {
 	return pubsub
 }
 
+// Subscribe subscribes the client to the specified channels.
+// Channels can be omitted to create empty subscription.
+func (c *SentinelClient) Subscribe(channels ...string) *PubSub {
+	pubsub := c.pubSub()
+	if len(channels) > 0 {
+		_ = pubsub.Subscribe(channels...)
+	}
+	return pubsub
+}
+
+// PSubscribe subscribes the client to the given patterns.
+// Patterns can be omitted to create empty subscription.
+func (c *SentinelClient) PSubscribe(channels ...string) *PubSub {
+	pubsub := c.pubSub()
+	if len(channels) > 0 {
+		_ = pubsub.PSubscribe(channels...)
+	}
+	return pubsub
+}
+
 func (c *SentinelClient) GetMasterAddrByName(name string) *StringSliceCmd {
-	cmd := NewStringSliceCmd("SENTINEL", "get-master-addr-by-name", name)
+	cmd := NewStringSliceCmd("sentinel", "get-master-addr-by-name", name)
 	c.Process(cmd)
 	return cmd
 }
 
 func (c *SentinelClient) Sentinels(name string) *SliceCmd {
-	cmd := NewSliceCmd("SENTINEL", "sentinels", name)
+	cmd := NewSliceCmd("sentinel", "sentinels", name)
 	c.Process(cmd)
 	return cmd
 }
@@ -158,77 +178,70 @@ type sentinelFailover struct {
 	sentinel    *SentinelClient
 }
 
-func (d *sentinelFailover) Close() error {
+func (c *sentinelFailover) Close() error {
-	return d.resetSentinel()
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.closeSentinel()
 }
 
-func (d *sentinelFailover) Pool() *pool.ConnPool {
+func (c *sentinelFailover) Pool() *pool.ConnPool {
-	d.poolOnce.Do(func() {
+	c.poolOnce.Do(func() {
-		d.opt.Dialer = d.dial
+		c.opt.Dialer = c.dial
-		d.pool = newConnPool(d.opt)
+		c.pool = newConnPool(c.opt)
 	})
-	return d.pool
+	return c.pool
 }
 
-func (d *sentinelFailover) dial() (net.Conn, error) {
+func (c *sentinelFailover) dial() (net.Conn, error) {
-	addr, err := d.MasterAddr()
+	addr, err := c.MasterAddr()
 	if err != nil {
 		return nil, err
 	}
-	return net.DialTimeout("tcp", addr, d.opt.DialTimeout)
+	return net.DialTimeout("tcp", addr, c.opt.DialTimeout)
 }
 
-func (d *sentinelFailover) MasterAddr() (string, error) {
+func (c *sentinelFailover) MasterAddr() (string, error) {
-	d.mu.Lock()
+	addr, err := c.masterAddr()
-	defer d.mu.Unlock()
-
-	addr, err := d.masterAddr()
 	if err != nil {
 		return "", err
 	}
-	d._switchMaster(addr)
+	c.switchMaster(addr)
-
 	return addr, nil
 }
 
-func (d *sentinelFailover) masterAddr() (string, error) {
+func (c *sentinelFailover) masterAddr() (string, error) {
-	// Try last working sentinel.
+	addr := c.getMasterAddr()
-	if d.sentinel != nil {
+	if addr != "" {
-		addr, err := d.sentinel.GetMasterAddrByName(d.masterName).Result()
-		if err == nil {
-			addr := net.JoinHostPort(addr[0], addr[1])
 		return addr, nil
 	}
 
-		internal.Logf("sentinel: GetMasterAddrByName name=%q failed: %s",
+	c.mu.Lock()
-			d.masterName, err)
+	defer c.mu.Unlock()
-		d._resetSentinel()
-	}
 
-	for i, sentinelAddr := range d.sentinelAddrs {
+	for i, sentinelAddr := range c.sentinelAddrs {
 		sentinel := NewSentinelClient(&Options{
 			Addr: sentinelAddr,
 
-			DialTimeout:  d.opt.DialTimeout,
+			DialTimeout:  c.opt.DialTimeout,
-			ReadTimeout:  d.opt.ReadTimeout,
+			ReadTimeout:  c.opt.ReadTimeout,
-			WriteTimeout: d.opt.WriteTimeout,
+			WriteTimeout: c.opt.WriteTimeout,
 
-			PoolSize:    d.opt.PoolSize,
+			PoolSize:    c.opt.PoolSize,
-			PoolTimeout: d.opt.PoolTimeout,
+			PoolTimeout: c.opt.PoolTimeout,
-			IdleTimeout: d.opt.IdleTimeout,
+			IdleTimeout: c.opt.IdleTimeout,
 		})
 
-		masterAddr, err := sentinel.GetMasterAddrByName(d.masterName).Result()
+		masterAddr, err := sentinel.GetMasterAddrByName(c.masterName).Result()
 		if err != nil {
 			internal.Logf("sentinel: GetMasterAddrByName master=%q failed: %s",
-				d.masterName, err)
+				c.masterName, err)
 			sentinel.Close()
 			continue
 		}
 
 		// Push working sentinel to the top.
-		d.sentinelAddrs[0], d.sentinelAddrs[i] = d.sentinelAddrs[i], d.sentinelAddrs[0]
+		c.sentinelAddrs[0], c.sentinelAddrs[i] = c.sentinelAddrs[i], c.sentinelAddrs[0]
-		d.setSentinel(sentinel)
+		c.setSentinel(sentinel)
 
 		addr := net.JoinHostPort(masterAddr[0], masterAddr[1])
 		return addr, nil
@@ -237,17 +250,41 @@ func (d *sentinelFailover) masterAddr() (string, error) {
 	return "", errors.New("redis: all sentinels are unreachable")
 }
 
-func (c *sentinelFailover) switchMaster(addr string) {
+func (c *sentinelFailover) getMasterAddr() string {
+	c.mu.RLock()
+	sentinel := c.sentinel
+	c.mu.RUnlock()
+
+	if sentinel == nil {
+		return ""
+	}
+
+	addr, err := sentinel.GetMasterAddrByName(c.masterName).Result()
+	if err != nil {
+		internal.Logf("sentinel: GetMasterAddrByName name=%q failed: %s",
+			c.masterName, err)
 		c.mu.Lock()
-	c._switchMaster(addr)
+		if c.sentinel == sentinel {
+			c.closeSentinel()
+		}
 		c.mu.Unlock()
+		return ""
+	}
+
+	return net.JoinHostPort(addr[0], addr[1])
 }
 
-func (c *sentinelFailover) _switchMaster(addr string) {
+func (c *sentinelFailover) switchMaster(addr string) {
-	if c._masterAddr == addr {
+	c.mu.RLock()
+	masterAddr := c._masterAddr
+	c.mu.RUnlock()
+	if masterAddr == addr {
 		return
 	}
 
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
 	internal.Logf("sentinel: new master=%q addr=%q",
 		c.masterName, addr)
 	_ = c.Pool().Filter(func(cn *pool.Conn) bool {
@@ -256,32 +293,22 @@ func (c *sentinelFailover) _switchMaster(addr string) {
 	c._masterAddr = addr
 }
 
-func (d *sentinelFailover) setSentinel(sentinel *SentinelClient) {
+func (c *sentinelFailover) setSentinel(sentinel *SentinelClient) {
-	d.discoverSentinels(sentinel)
+	c.discoverSentinels(sentinel)
-	d.sentinel = sentinel
+	c.sentinel = sentinel
-	go d.listen(sentinel)
+	go c.listen(sentinel)
 }
 
-func (d *sentinelFailover) resetSentinel() error {
+func (c *sentinelFailover) closeSentinel() error {
-	var err error
+	err := c.sentinel.Close()
-	d.mu.Lock()
+	c.sentinel = nil
-	if d.sentinel != nil {
-		err = d._resetSentinel()
-	}
-	d.mu.Unlock()
 	return err
 }
 
-func (d *sentinelFailover) _resetSentinel() error {
+func (c *sentinelFailover) discoverSentinels(sentinel *SentinelClient) {
-	err := d.sentinel.Close()
+	sentinels, err := sentinel.Sentinels(c.masterName).Result()
-	d.sentinel = nil
-	return err
-}
-
-func (d *sentinelFailover) discoverSentinels(sentinel *SentinelClient) {
-	sentinels, err := sentinel.Sentinels(d.masterName).Result()
 	if err != nil {
-		internal.Logf("sentinel: Sentinels master=%q failed: %s", d.masterName, err)
+		internal.Logf("sentinel: Sentinels master=%q failed: %s", c.masterName, err)
 		return
 	}
 	for _, sentinel := range sentinels {
@@ -290,49 +317,36 @@ func (d *sentinelFailover) discoverSentinels(sentinel *SentinelClient) {
 			key := vals[i].(string)
 			if key == "name" {
 				sentinelAddr := vals[i+1].(string)
-				if !contains(d.sentinelAddrs, sentinelAddr) {
+				if !contains(c.sentinelAddrs, sentinelAddr) {
-					internal.Logf(
+					internal.Logf("sentinel: discovered new sentinel=%q for master=%q",
-						"sentinel: discovered new sentinel=%q for master=%q",
+						sentinelAddr, c.masterName)
-						sentinelAddr, d.masterName,
+					c.sentinelAddrs = append(c.sentinelAddrs, sentinelAddr)
-					)
-					d.sentinelAddrs = append(d.sentinelAddrs, sentinelAddr)
 				}
 			}
 		}
 	}
 }
 
-func (d *sentinelFailover) listen(sentinel *SentinelClient) {
+func (c *sentinelFailover) listen(sentinel *SentinelClient) {
-	pubsub := sentinel.PubSub()
+	pubsub := sentinel.Subscribe("+switch-master")
 	defer pubsub.Close()
 
-	err := pubsub.Subscribe("+switch-master")
+	ch := pubsub.Channel()
-	if err != nil {
-		internal.Logf("sentinel: Subscribe failed: %s", err)
-		d.resetSentinel()
-		return
-	}
-
 	for {
-		msg, err := pubsub.ReceiveMessage()
+		msg, ok := <-ch
-		if err != nil {
+		if !ok {
-			if err == pool.ErrClosed {
+			break
-				d.resetSentinel()
-				return
-			}
-			internal.Logf("sentinel: ReceiveMessage failed: %s", err)
-			continue
 		}
 
 		switch msg.Channel {
 		case "+switch-master":
 			parts := strings.Split(msg.Payload, " ")
-			if parts[0] != d.masterName {
+			if parts[0] != c.masterName {
 				internal.Logf("sentinel: ignore addr for master=%q", parts[0])
 				continue
 			}
 			addr := net.JoinHostPort(parts[3], parts[4])
-			d.switchMaster(addr)
+			c.switchMaster(addr)
 		}
 	}
 }