[Vendor] Update go-redis to v8.5.0 (#13749)

* Update go-redis to v8.4.0

* github.com/go-redis/redis/v8  v8.4.0 -> v8.5.0

* Apply suggestions from code review

Co-authored-by: zeripath <art27@cantab.net>

* TODO

* Use the Queue termination channel as the default context for pushes

Signed-off-by: Andrew Thornton <art27@cantab.net>

* missed one

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: zeripath <art27@cantab.net>

vendor/github.com/go-redis/redis/v8/sentinel.go

@@ -0,0 +1,738 @@
+package redis
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"net"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/go-redis/redis/v8/internal"
+	"github.com/go-redis/redis/v8/internal/pool"
+	"github.com/go-redis/redis/v8/internal/rand"
+)
+
+//------------------------------------------------------------------------------
+
+// FailoverOptions are used to configure a failover client and should
+// be passed to NewFailoverClient.
+type FailoverOptions struct {
+	// The master name.
+	MasterName string
+	// A seed list of host:port addresses of sentinel nodes.
+	SentinelAddrs []string
+	// Sentinel password from "requirepass <password>" (if enabled) in Sentinel configuration
+	SentinelPassword string
+
+	// Allows routing read-only commands to the closest master or slave node.
+	// This option only works with NewFailoverClusterClient.
+	RouteByLatency bool
+	// Allows routing read-only commands to the random master or slave node.
+	// This option only works with NewFailoverClusterClient.
+	RouteRandomly bool
+
+	// Route all commands to slave read-only nodes.
+	SlaveOnly bool
+
+	// Following options are copied from Options struct.
+
+	Dialer    func(ctx context.Context, network, addr string) (net.Conn, error)
+	OnConnect func(ctx context.Context, cn *Conn) error
+
+	Username string
+	Password string
+	DB       int
+
+	MaxRetries      int
+	MinRetryBackoff time.Duration
+	MaxRetryBackoff time.Duration
+
+	DialTimeout  time.Duration
+	ReadTimeout  time.Duration
+	WriteTimeout time.Duration
+
+	PoolSize           int
+	MinIdleConns       int
+	MaxConnAge         time.Duration
+	PoolTimeout        time.Duration
+	IdleTimeout        time.Duration
+	IdleCheckFrequency time.Duration
+
+	TLSConfig *tls.Config
+}
+
+func (opt *FailoverOptions) clientOptions() *Options {
+	return &Options{
+		Addr: "FailoverClient",
+
+		Dialer:    opt.Dialer,
+		OnConnect: opt.OnConnect,
+
+		DB:       opt.DB,
+		Username: opt.Username,
+		Password: opt.Password,
+
+		MaxRetries:      opt.MaxRetries,
+		MinRetryBackoff: opt.MinRetryBackoff,
+		MaxRetryBackoff: opt.MaxRetryBackoff,
+
+		DialTimeout:  opt.DialTimeout,
+		ReadTimeout:  opt.ReadTimeout,
+		WriteTimeout: opt.WriteTimeout,
+
+		PoolSize:           opt.PoolSize,
+		PoolTimeout:        opt.PoolTimeout,
+		IdleTimeout:        opt.IdleTimeout,
+		IdleCheckFrequency: opt.IdleCheckFrequency,
+		MinIdleConns:       opt.MinIdleConns,
+		MaxConnAge:         opt.MaxConnAge,
+
+		TLSConfig: opt.TLSConfig,
+	}
+}
+
+func (opt *FailoverOptions) sentinelOptions(addr string) *Options {
+	return &Options{
+		Addr: addr,
+
+		Dialer:    opt.Dialer,
+		OnConnect: opt.OnConnect,
+
+		DB:       0,
+		Password: opt.SentinelPassword,
+
+		MaxRetries:      opt.MaxRetries,
+		MinRetryBackoff: opt.MinRetryBackoff,
+		MaxRetryBackoff: opt.MaxRetryBackoff,
+
+		DialTimeout:  opt.DialTimeout,
+		ReadTimeout:  opt.ReadTimeout,
+		WriteTimeout: opt.WriteTimeout,
+
+		PoolSize:           opt.PoolSize,
+		PoolTimeout:        opt.PoolTimeout,
+		IdleTimeout:        opt.IdleTimeout,
+		IdleCheckFrequency: opt.IdleCheckFrequency,
+		MinIdleConns:       opt.MinIdleConns,
+		MaxConnAge:         opt.MaxConnAge,
+
+		TLSConfig: opt.TLSConfig,
+	}
+}
+
+func (opt *FailoverOptions) clusterOptions() *ClusterOptions {
+	return &ClusterOptions{
+		Dialer:    opt.Dialer,
+		OnConnect: opt.OnConnect,
+
+		Username: opt.Username,
+		Password: opt.Password,
+
+		MaxRedirects: opt.MaxRetries,
+
+		RouteByLatency: opt.RouteByLatency,
+		RouteRandomly:  opt.RouteRandomly,
+
+		MinRetryBackoff: opt.MinRetryBackoff,
+		MaxRetryBackoff: opt.MaxRetryBackoff,
+
+		DialTimeout:  opt.DialTimeout,
+		ReadTimeout:  opt.ReadTimeout,
+		WriteTimeout: opt.WriteTimeout,
+
+		PoolSize:           opt.PoolSize,
+		PoolTimeout:        opt.PoolTimeout,
+		IdleTimeout:        opt.IdleTimeout,
+		IdleCheckFrequency: opt.IdleCheckFrequency,
+		MinIdleConns:       opt.MinIdleConns,
+		MaxConnAge:         opt.MaxConnAge,
+
+		TLSConfig: opt.TLSConfig,
+	}
+}
+
+// NewFailoverClient returns a Redis client that uses Redis Sentinel
+// for automatic failover. It's safe for concurrent use by multiple
+// goroutines.
+func NewFailoverClient(failoverOpt *FailoverOptions) *Client {
+	if failoverOpt.RouteByLatency {
+		panic("to route commands by latency, use NewFailoverClusterClient")
+	}
+	if failoverOpt.RouteRandomly {
+		panic("to route commands randomly, use NewFailoverClusterClient")
+	}
+
+	sentinelAddrs := make([]string, len(failoverOpt.SentinelAddrs))
+	copy(sentinelAddrs, failoverOpt.SentinelAddrs)
+
+	failover := &sentinelFailover{
+		opt:           failoverOpt,
+		sentinelAddrs: sentinelAddrs,
+	}
+
+	opt := failoverOpt.clientOptions()
+	opt.Dialer = masterSlaveDialer(failover)
+	opt.init()
+
+	connPool := newConnPool(opt)
+
+	failover.mu.Lock()
+	failover.onFailover = func(ctx context.Context, addr string) {
+		_ = connPool.Filter(func(cn *pool.Conn) bool {
+			return cn.RemoteAddr().String() != addr
+		})
+	}
+	failover.mu.Unlock()
+
+	c := Client{
+		baseClient: newBaseClient(opt, connPool),
+		ctx:        context.Background(),
+	}
+	c.cmdable = c.Process
+	c.onClose = failover.Close
+
+	return &c
+}
+
+func masterSlaveDialer(
+	failover *sentinelFailover,
+) func(ctx context.Context, network, addr string) (net.Conn, error) {
+	return func(ctx context.Context, network, _ string) (net.Conn, error) {
+		var addr string
+		var err error
+
+		if failover.opt.SlaveOnly {
+			addr, err = failover.RandomSlaveAddr(ctx)
+		} else {
+			addr, err = failover.MasterAddr(ctx)
+			if err == nil {
+				failover.trySwitchMaster(ctx, addr)
+			}
+		}
+
+		if err != nil {
+			return nil, err
+		}
+		if failover.opt.Dialer != nil {
+			return failover.opt.Dialer(ctx, network, addr)
+		}
+		return net.DialTimeout("tcp", addr, failover.opt.DialTimeout)
+	}
+}
+
+//------------------------------------------------------------------------------
+
+// SentinelClient is a client for a Redis Sentinel.
+type SentinelClient struct {
+	*baseClient
+	hooks
+	ctx context.Context
+}
+
+func NewSentinelClient(opt *Options) *SentinelClient {
+	opt.init()
+	c := &SentinelClient{
+		baseClient: &baseClient{
+			opt:      opt,
+			connPool: newConnPool(opt),
+		},
+		ctx: context.Background(),
+	}
+	return c
+}
+
+func (c *SentinelClient) Context() context.Context {
+	return c.ctx
+}
+
+func (c *SentinelClient) WithContext(ctx context.Context) *SentinelClient {
+	if ctx == nil {
+		panic("nil context")
+	}
+	clone := *c
+	clone.ctx = ctx
+	return &clone
+}
+
+func (c *SentinelClient) Process(ctx context.Context, cmd Cmder) error {
+	return c.hooks.process(ctx, cmd, c.baseClient.process)
+}
+
+func (c *SentinelClient) pubSub() *PubSub {
+	pubsub := &PubSub{
+		opt: c.opt,
+
+		newConn: func(ctx context.Context, channels []string) (*pool.Conn, error) {
+			return c.newConn(ctx)
+		},
+		closeConn: c.connPool.CloseConn,
+	}
+	pubsub.init()
+	return pubsub
+}
+
+// Ping is used to test if a connection is still alive, or to
+// measure latency.
+func (c *SentinelClient) Ping(ctx context.Context) *StringCmd {
+	cmd := NewStringCmd(ctx, "ping")
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// Subscribe subscribes the client to the specified channels.
+// Channels can be omitted to create empty subscription.
+func (c *SentinelClient) Subscribe(ctx context.Context, channels ...string) *PubSub {
+	pubsub := c.pubSub()
+	if len(channels) > 0 {
+		_ = pubsub.Subscribe(ctx, channels...)
+	}
+	return pubsub
+}
+
+// PSubscribe subscribes the client to the given patterns.
+// Patterns can be omitted to create empty subscription.
+func (c *SentinelClient) PSubscribe(ctx context.Context, channels ...string) *PubSub {
+	pubsub := c.pubSub()
+	if len(channels) > 0 {
+		_ = pubsub.PSubscribe(ctx, channels...)
+	}
+	return pubsub
+}
+
+func (c *SentinelClient) GetMasterAddrByName(ctx context.Context, name string) *StringSliceCmd {
+	cmd := NewStringSliceCmd(ctx, "sentinel", "get-master-addr-by-name", name)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+func (c *SentinelClient) Sentinels(ctx context.Context, name string) *SliceCmd {
+	cmd := NewSliceCmd(ctx, "sentinel", "sentinels", name)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// Failover forces a failover as if the master was not reachable, and without
+// asking for agreement to other Sentinels.
+func (c *SentinelClient) Failover(ctx context.Context, name string) *StatusCmd {
+	cmd := NewStatusCmd(ctx, "sentinel", "failover", name)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// Reset resets all the masters with matching name. The pattern argument is a
+// glob-style pattern. The reset process clears any previous state in a master
+// (including a failover in progress), and removes every slave and sentinel
+// already discovered and associated with the master.
+func (c *SentinelClient) Reset(ctx context.Context, pattern string) *IntCmd {
+	cmd := NewIntCmd(ctx, "sentinel", "reset", pattern)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// FlushConfig forces Sentinel to rewrite its configuration on disk, including
+// the current Sentinel state.
+func (c *SentinelClient) FlushConfig(ctx context.Context) *StatusCmd {
+	cmd := NewStatusCmd(ctx, "sentinel", "flushconfig")
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// Master shows the state and info of the specified master.
+func (c *SentinelClient) Master(ctx context.Context, name string) *StringStringMapCmd {
+	cmd := NewStringStringMapCmd(ctx, "sentinel", "master", name)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// Masters shows a list of monitored masters and their state.
+func (c *SentinelClient) Masters(ctx context.Context) *SliceCmd {
+	cmd := NewSliceCmd(ctx, "sentinel", "masters")
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// Slaves shows a list of slaves for the specified master and their state.
+func (c *SentinelClient) Slaves(ctx context.Context, name string) *SliceCmd {
+	cmd := NewSliceCmd(ctx, "sentinel", "slaves", name)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// CkQuorum checks if the current Sentinel configuration is able to reach the
+// quorum needed to failover a master, and the majority needed to authorize the
+// failover. This command should be used in monitoring systems to check if a
+// Sentinel deployment is ok.
+func (c *SentinelClient) CkQuorum(ctx context.Context, name string) *StringCmd {
+	cmd := NewStringCmd(ctx, "sentinel", "ckquorum", name)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// Monitor tells the Sentinel to start monitoring a new master with the specified
+// name, ip, port, and quorum.
+func (c *SentinelClient) Monitor(ctx context.Context, name, ip, port, quorum string) *StringCmd {
+	cmd := NewStringCmd(ctx, "sentinel", "monitor", name, ip, port, quorum)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// Set is used in order to change configuration parameters of a specific master.
+func (c *SentinelClient) Set(ctx context.Context, name, option, value string) *StringCmd {
+	cmd := NewStringCmd(ctx, "sentinel", "set", name, option, value)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+// Remove is used in order to remove the specified master: the master will no
+// longer be monitored, and will totally be removed from the internal state of
+// the Sentinel.
+func (c *SentinelClient) Remove(ctx context.Context, name string) *StringCmd {
+	cmd := NewStringCmd(ctx, "sentinel", "remove", name)
+	_ = c.Process(ctx, cmd)
+	return cmd
+}
+
+//------------------------------------------------------------------------------
+
+type sentinelFailover struct {
+	opt *FailoverOptions
+
+	sentinelAddrs []string
+
+	onFailover func(ctx context.Context, addr string)
+	onUpdate   func(ctx context.Context)
+
+	mu          sync.RWMutex
+	_masterAddr string
+	sentinel    *SentinelClient
+	pubsub      *PubSub
+}
+
+func (c *sentinelFailover) Close() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.sentinel != nil {
+		return c.closeSentinel()
+	}
+	return nil
+}
+
+func (c *sentinelFailover) closeSentinel() error {
+	firstErr := c.pubsub.Close()
+	c.pubsub = nil
+
+	err := c.sentinel.Close()
+	if err != nil && firstErr == nil {
+		firstErr = err
+	}
+	c.sentinel = nil
+
+	return firstErr
+}
+
+func (c *sentinelFailover) RandomSlaveAddr(ctx context.Context) (string, error) {
+	addresses, err := c.slaveAddrs(ctx)
+	if err != nil {
+		return "", err
+	}
+	if len(addresses) == 0 {
+		return c.MasterAddr(ctx)
+	}
+	return addresses[rand.Intn(len(addresses))], nil
+}
+
+func (c *sentinelFailover) MasterAddr(ctx context.Context) (string, error) {
+	c.mu.RLock()
+	sentinel := c.sentinel
+	c.mu.RUnlock()
+
+	if sentinel != nil {
+		addr := c.getMasterAddr(ctx, sentinel)
+		if addr != "" {
+			return addr, nil
+		}
+	}
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.sentinel != nil {
+		addr := c.getMasterAddr(ctx, c.sentinel)
+		if addr != "" {
+			return addr, nil
+		}
+		_ = c.closeSentinel()
+	}
+
+	for i, sentinelAddr := range c.sentinelAddrs {
+		sentinel := NewSentinelClient(c.opt.sentinelOptions(sentinelAddr))
+
+		masterAddr, err := sentinel.GetMasterAddrByName(ctx, c.opt.MasterName).Result()
+		if err != nil {
+			internal.Logger.Printf(ctx, "sentinel: GetMasterAddrByName master=%q failed: %s",
+				c.opt.MasterName, err)
+			_ = sentinel.Close()
+			continue
+		}
+
+		// Push working sentinel to the top.
+		c.sentinelAddrs[0], c.sentinelAddrs[i] = c.sentinelAddrs[i], c.sentinelAddrs[0]
+		c.setSentinel(ctx, sentinel)
+
+		addr := net.JoinHostPort(masterAddr[0], masterAddr[1])
+		return addr, nil
+	}
+
+	return "", errors.New("redis: all sentinels specified in configuration are unreachable")
+}
+
+func (c *sentinelFailover) slaveAddrs(ctx context.Context) ([]string, error) {
+	c.mu.RLock()
+	sentinel := c.sentinel
+	c.mu.RUnlock()
+
+	if sentinel != nil {
+		addrs := c.getSlaveAddrs(ctx, sentinel)
+		if len(addrs) > 0 {
+			return addrs, nil
+		}
+	}
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.sentinel != nil {
+		addrs := c.getSlaveAddrs(ctx, c.sentinel)
+		if len(addrs) > 0 {
+			return addrs, nil
+		}
+		_ = c.closeSentinel()
+	}
+
+	for i, sentinelAddr := range c.sentinelAddrs {
+		sentinel := NewSentinelClient(c.opt.sentinelOptions(sentinelAddr))
+
+		slaves, err := sentinel.Slaves(ctx, c.opt.MasterName).Result()
+		if err != nil {
+			internal.Logger.Printf(ctx, "sentinel: Slaves master=%q failed: %s",
+				c.opt.MasterName, err)
+			_ = sentinel.Close()
+			continue
+		}
+
+		// Push working sentinel to the top.
+		c.sentinelAddrs[0], c.sentinelAddrs[i] = c.sentinelAddrs[i], c.sentinelAddrs[0]
+		c.setSentinel(ctx, sentinel)
+
+		addrs := parseSlaveAddrs(slaves)
+		return addrs, nil
+	}
+
+	return []string{}, errors.New("redis: all sentinels specified in configuration are unreachable")
+}
+
+func (c *sentinelFailover) getMasterAddr(ctx context.Context, sentinel *SentinelClient) string {
+	addr, err := sentinel.GetMasterAddrByName(ctx, c.opt.MasterName).Result()
+	if err != nil {
+		internal.Logger.Printf(ctx, "sentinel: GetMasterAddrByName name=%q failed: %s",
+			c.opt.MasterName, err)
+		return ""
+	}
+	return net.JoinHostPort(addr[0], addr[1])
+}
+
+func (c *sentinelFailover) getSlaveAddrs(ctx context.Context, sentinel *SentinelClient) []string {
+	addrs, err := sentinel.Slaves(ctx, c.opt.MasterName).Result()
+	if err != nil {
+		internal.Logger.Printf(ctx, "sentinel: Slaves name=%q failed: %s",
+			c.opt.MasterName, err)
+		return []string{}
+	}
+	return parseSlaveAddrs(addrs)
+}
+
+func parseSlaveAddrs(addrs []interface{}) []string {
+	nodes := make([]string, 0, len(addrs))
+
+	for _, node := range addrs {
+		ip := ""
+		port := ""
+		flags := []string{}
+		lastkey := ""
+		isDown := false
+
+		for _, key := range node.([]interface{}) {
+			switch lastkey {
+			case "ip":
+				ip = key.(string)
+			case "port":
+				port = key.(string)
+			case "flags":
+				flags = strings.Split(key.(string), ",")
+			}
+			lastkey = key.(string)
+		}
+
+		for _, flag := range flags {
+			switch flag {
+			case "s_down", "o_down", "disconnected":
+				isDown = true
+			}
+		}
+
+		if !isDown {
+			nodes = append(nodes, net.JoinHostPort(ip, port))
+		}
+	}
+
+	return nodes
+}
+
+func (c *sentinelFailover) trySwitchMaster(ctx context.Context, addr string) {
+	c.mu.RLock()
+	currentAddr := c._masterAddr
+	c.mu.RUnlock()
+
+	if addr == currentAddr {
+		return
+	}
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if addr == c._masterAddr {
+		return
+	}
+	c._masterAddr = addr
+
+	internal.Logger.Printf(ctx, "sentinel: new master=%q addr=%q",
+		c.opt.MasterName, addr)
+	if c.onFailover != nil {
+		c.onFailover(ctx, addr)
+	}
+}
+
+func (c *sentinelFailover) setSentinel(ctx context.Context, sentinel *SentinelClient) {
+	if c.sentinel != nil {
+		panic("not reached")
+	}
+	c.sentinel = sentinel
+	c.discoverSentinels(ctx)
+
+	c.pubsub = sentinel.Subscribe(ctx, "+switch-master", "+slave-reconf-done")
+	go c.listen(c.pubsub)
+}
+
+func (c *sentinelFailover) discoverSentinels(ctx context.Context) {
+	sentinels, err := c.sentinel.Sentinels(ctx, c.opt.MasterName).Result()
+	if err != nil {
+		internal.Logger.Printf(ctx, "sentinel: Sentinels master=%q failed: %s", c.opt.MasterName, err)
+		return
+	}
+	for _, sentinel := range sentinels {
+		vals := sentinel.([]interface{})
+		for i := 0; i < len(vals); i += 2 {
+			key := vals[i].(string)
+			if key == "name" {
+				sentinelAddr := vals[i+1].(string)
+				if !contains(c.sentinelAddrs, sentinelAddr) {
+					internal.Logger.Printf(ctx, "sentinel: discovered new sentinel=%q for master=%q",
+						sentinelAddr, c.opt.MasterName)
+					c.sentinelAddrs = append(c.sentinelAddrs, sentinelAddr)
+				}
+			}
+		}
+	}
+}
+
+func (c *sentinelFailover) listen(pubsub *PubSub) {
+	ctx := context.TODO()
+
+	if c.onUpdate != nil {
+		c.onUpdate(ctx)
+	}
+
+	ch := pubsub.Channel()
+	for msg := range ch {
+		if msg.Channel == "+switch-master" {
+			parts := strings.Split(msg.Payload, " ")
+			if parts[0] != c.opt.MasterName {
+				internal.Logger.Printf(pubsub.getContext(), "sentinel: ignore addr for master=%q", parts[0])
+				continue
+			}
+			addr := net.JoinHostPort(parts[3], parts[4])
+			c.trySwitchMaster(pubsub.getContext(), addr)
+		}
+
+		if c.onUpdate != nil {
+			c.onUpdate(ctx)
+		}
+	}
+}
+
+func contains(slice []string, str string) bool {
+	for _, s := range slice {
+		if s == str {
+			return true
+		}
+	}
+	return false
+}
+
+//------------------------------------------------------------------------------
+
+// NewFailoverClusterClient returns a client that supports routing read-only commands
+// to a slave node.
+func NewFailoverClusterClient(failoverOpt *FailoverOptions) *ClusterClient {
+	sentinelAddrs := make([]string, len(failoverOpt.SentinelAddrs))
+	copy(sentinelAddrs, failoverOpt.SentinelAddrs)
+
+	failover := &sentinelFailover{
+		opt:           failoverOpt,
+		sentinelAddrs: sentinelAddrs,
+	}
+
+	opt := failoverOpt.clusterOptions()
+	opt.ClusterSlots = func(ctx context.Context) ([]ClusterSlot, error) {
+		masterAddr, err := failover.MasterAddr(ctx)
+		if err != nil {
+			return nil, err
+		}
+
+		nodes := []ClusterNode{{
+			Addr: masterAddr,
+		}}
+
+		slaveAddrs, err := failover.slaveAddrs(ctx)
+		if err != nil {
+			return nil, err
+		}
+
+		for _, slaveAddr := range slaveAddrs {
+			nodes = append(nodes, ClusterNode{
+				Addr: slaveAddr,
+			})
+		}
+
+		slots := []ClusterSlot{
+			{
+				Start: 0,
+				End:   16383,
+				Nodes: nodes,
+			},
+		}
+		return slots, nil
+	}
+
+	c := NewClusterClient(opt)
+
+	failover.mu.Lock()
+	failover.onUpdate = func(ctx context.Context) {
+		c.ReloadState(ctx)
+	}
+	failover.mu.Unlock()
+
+	return c
+}