src: Add DMA localagent

Change-Id: Ibcee814fbc9a904448eeb368a1a26bbb69cf54aa
Signed-off-by: Toshiaki Takahashi <takahashi.tsc@ncos.nec.co.jp>

1 files changed, 1624 insertions, 0 deletions

diff --git a/src/dma/vendor/github.com/go-redis/redis/cluster.go b/src/dma/vendor/github.com/go-redis/redis/cluster.go
new file mode 100644
index 00000000..7a1af143
--- /dev/null
+++ b/src/dma/vendor/github.com/go-redis/redis/cluster.go
@@ -0,0 +1,1624 @@
+package redis
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"math"
+	"math/rand"
+	"net"
+	"sort"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/go-redis/redis/internal"
+	"github.com/go-redis/redis/internal/hashtag"
+	"github.com/go-redis/redis/internal/pool"
+	"github.com/go-redis/redis/internal/proto"
+	"github.com/go-redis/redis/internal/singleflight"
+)
+
+var errClusterNoNodes = fmt.Errorf("redis: cluster has no nodes")
+
+// ClusterOptions are used to configure a cluster client and should be
+// passed to NewClusterClient.
+type ClusterOptions struct {
+	// A seed list of host:port addresses of cluster nodes.
+	Addrs []string
+
+	// The maximum number of retries before giving up. Command is retried
+	// on network errors and MOVED/ASK redirects.
+	// Default is 8 retries.
+	MaxRedirects int
+
+	// Enables read-only commands on slave nodes.
+	ReadOnly bool
+	// Allows routing read-only commands to the closest master or slave node.
+	// It automatically enables ReadOnly.
+	RouteByLatency bool
+	// Allows routing read-only commands to the random master or slave node.
+	// It automatically enables ReadOnly.
+	RouteRandomly bool
+
+	// Optional function that returns cluster slots information.
+	// It is useful to manually create cluster of standalone Redis servers
+	// and load-balance read/write operations between master and slaves.
+	// It can use service like ZooKeeper to maintain configuration information
+	// and Cluster.ReloadState to manually trigger state reloading.
+	ClusterSlots func() ([]ClusterSlot, error)
+
+	// Following options are copied from Options struct.
+
+	OnConnect func(*Conn) error
+
+	MaxRetries      int
+	MinRetryBackoff time.Duration
+	MaxRetryBackoff time.Duration
+	Password        string
+
+	DialTimeout  time.Duration
+	ReadTimeout  time.Duration
+	WriteTimeout time.Duration
+
+	// PoolSize applies per cluster node and not for the whole cluster.
+	PoolSize           int
+	PoolTimeout        time.Duration
+	IdleTimeout        time.Duration
+	IdleCheckFrequency time.Duration
+
+	TLSConfig *tls.Config
+}
+
+func (opt *ClusterOptions) init() {
+	if opt.MaxRedirects == -1 {
+		opt.MaxRedirects = 0
+	} else if opt.MaxRedirects == 0 {
+		opt.MaxRedirects = 8
+	}
+
+	if opt.RouteByLatency || opt.RouteRandomly {
+		opt.ReadOnly = true
+	}
+
+	switch opt.ReadTimeout {
+	case -1:
+		opt.ReadTimeout = 0
+	case 0:
+		opt.ReadTimeout = 3 * time.Second
+	}
+	switch opt.WriteTimeout {
+	case -1:
+		opt.WriteTimeout = 0
+	case 0:
+		opt.WriteTimeout = opt.ReadTimeout
+	}
+
+	switch opt.MinRetryBackoff {
+	case -1:
+		opt.MinRetryBackoff = 0
+	case 0:
+		opt.MinRetryBackoff = 8 * time.Millisecond
+	}
+	switch opt.MaxRetryBackoff {
+	case -1:
+		opt.MaxRetryBackoff = 0
+	case 0:
+		opt.MaxRetryBackoff = 512 * time.Millisecond
+	}
+}
+
+func (opt *ClusterOptions) clientOptions() *Options {
+	const disableIdleCheck = -1
+
+	return &Options{
+		OnConnect: opt.OnConnect,
+
+		MaxRetries:      opt.MaxRetries,
+		MinRetryBackoff: opt.MinRetryBackoff,
+		MaxRetryBackoff: opt.MaxRetryBackoff,
+		Password:        opt.Password,
+		readOnly:        opt.ReadOnly,
+
+		DialTimeout:  opt.DialTimeout,
+		ReadTimeout:  opt.ReadTimeout,
+		WriteTimeout: opt.WriteTimeout,
+
+		PoolSize:    opt.PoolSize,
+		PoolTimeout: opt.PoolTimeout,
+		IdleTimeout: opt.IdleTimeout,
+
+		IdleCheckFrequency: disableIdleCheck,
+
+		TLSConfig: opt.TLSConfig,
+	}
+}
+
+//------------------------------------------------------------------------------
+
+type clusterNode struct {
+	Client *Client
+
+	latency    uint32 // atomic
+	generation uint32 // atomic
+	loading    uint32 // atomic
+}
+
+func newClusterNode(clOpt *ClusterOptions, addr string) *clusterNode {
+	opt := clOpt.clientOptions()
+	opt.Addr = addr
+	node := clusterNode{
+		Client: NewClient(opt),
+	}
+
+	node.latency = math.MaxUint32
+	if clOpt.RouteByLatency {
+		go node.updateLatency()
+	}
+
+	return &node
+}
+
+func (n *clusterNode) String() string {
+	return n.Client.String()
+}
+
+func (n *clusterNode) Close() error {
+	return n.Client.Close()
+}
+
+func (n *clusterNode) updateLatency() {
+	const probes = 10
+
+	var latency uint32
+	for i := 0; i < probes; i++ {
+		start := time.Now()
+		n.Client.Ping()
+		probe := uint32(time.Since(start) / time.Microsecond)
+		latency = (latency + probe) / 2
+	}
+	atomic.StoreUint32(&n.latency, latency)
+}
+
+func (n *clusterNode) Latency() time.Duration {
+	latency := atomic.LoadUint32(&n.latency)
+	return time.Duration(latency) * time.Microsecond
+}
+
+func (n *clusterNode) MarkAsLoading() {
+	atomic.StoreUint32(&n.loading, uint32(time.Now().Unix()))
+}
+
+func (n *clusterNode) Loading() bool {
+	const minute = int64(time.Minute / time.Second)
+
+	loading := atomic.LoadUint32(&n.loading)
+	if loading == 0 {
+		return false
+	}
+	if time.Now().Unix()-int64(loading) < minute {
+		return true
+	}
+	atomic.StoreUint32(&n.loading, 0)
+	return false
+}
+
+func (n *clusterNode) Generation() uint32 {
+	return atomic.LoadUint32(&n.generation)
+}
+
+func (n *clusterNode) SetGeneration(gen uint32) {
+	for {
+		v := atomic.LoadUint32(&n.generation)
+		if gen < v || atomic.CompareAndSwapUint32(&n.generation, v, gen) {
+			break
+		}
+	}
+}
+
+//------------------------------------------------------------------------------
+
+type clusterNodes struct {
+	opt *ClusterOptions
+
+	mu           sync.RWMutex
+	allAddrs     []string
+	allNodes     map[string]*clusterNode
+	clusterAddrs []string
+	closed       bool
+
+	nodeCreateGroup singleflight.Group
+
+	_generation uint32 // atomic
+}
+
+func newClusterNodes(opt *ClusterOptions) *clusterNodes {
+	return &clusterNodes{
+		opt: opt,
+
+		allAddrs: opt.Addrs,
+		allNodes: make(map[string]*clusterNode),
+	}
+}
+
+func (c *clusterNodes) Close() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.closed {
+		return nil
+	}
+	c.closed = true
+
+	var firstErr error
+	for _, node := range c.allNodes {
+		if err := node.Client.Close(); err != nil && firstErr == nil {
+			firstErr = err
+		}
+	}
+
+	c.allNodes = nil
+	c.clusterAddrs = nil
+
+	return firstErr
+}
+
+func (c *clusterNodes) Addrs() ([]string, error) {
+	var addrs []string
+	c.mu.RLock()
+	closed := c.closed
+	if !closed {
+		if len(c.clusterAddrs) > 0 {
+			addrs = c.clusterAddrs
+		} else {
+			addrs = c.allAddrs
+		}
+	}
+	c.mu.RUnlock()
+
+	if closed {
+		return nil, pool.ErrClosed
+	}
+	if len(addrs) == 0 {
+		return nil, errClusterNoNodes
+	}
+	return addrs, nil
+}
+
+func (c *clusterNodes) NextGeneration() uint32 {
+	return atomic.AddUint32(&c._generation, 1)
+}
+
+// GC removes unused nodes.
+func (c *clusterNodes) GC(generation uint32) {
+	var collected []*clusterNode
+	c.mu.Lock()
+	for addr, node := range c.allNodes {
+		if node.Generation() >= generation {
+			continue
+		}
+
+		c.clusterAddrs = remove(c.clusterAddrs, addr)
+		delete(c.allNodes, addr)
+		collected = append(collected, node)
+	}
+	c.mu.Unlock()
+
+	for _, node := range collected {
+		_ = node.Client.Close()
+	}
+}
+
+func (c *clusterNodes) Get(addr string) (*clusterNode, error) {
+	var node *clusterNode
+	var err error
+	c.mu.RLock()
+	if c.closed {
+		err = pool.ErrClosed
+	} else {
+		node = c.allNodes[addr]
+	}
+	c.mu.RUnlock()
+	return node, err
+}
+
+func (c *clusterNodes) GetOrCreate(addr string) (*clusterNode, error) {
+	node, err := c.Get(addr)
+	if err != nil {
+		return nil, err
+	}
+	if node != nil {
+		return node, nil
+	}
+
+	v, err := c.nodeCreateGroup.Do(addr, func() (interface{}, error) {
+		node := newClusterNode(c.opt, addr)
+		return node, nil
+	})
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.closed {
+		return nil, pool.ErrClosed
+	}
+
+	node, ok := c.allNodes[addr]
+	if ok {
+		_ = v.(*clusterNode).Close()
+		return node, err
+	}
+	node = v.(*clusterNode)
+
+	c.allAddrs = appendIfNotExists(c.allAddrs, addr)
+	if err == nil {
+		c.clusterAddrs = append(c.clusterAddrs, addr)
+	}
+	c.allNodes[addr] = node
+
+	return node, err
+}
+
+func (c *clusterNodes) All() ([]*clusterNode, error) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	if c.closed {
+		return nil, pool.ErrClosed
+	}
+
+	cp := make([]*clusterNode, 0, len(c.allNodes))
+	for _, node := range c.allNodes {
+		cp = append(cp, node)
+	}
+	return cp, nil
+}
+
+func (c *clusterNodes) Random() (*clusterNode, error) {
+	addrs, err := c.Addrs()
+	if err != nil {
+		return nil, err
+	}
+
+	n := rand.Intn(len(addrs))
+	return c.GetOrCreate(addrs[n])
+}
+
+//------------------------------------------------------------------------------
+
+type clusterSlot struct {
+	start, end int
+	nodes      []*clusterNode
+}
+
+type clusterSlotSlice []*clusterSlot
+
+func (p clusterSlotSlice) Len() int {
+	return len(p)
+}
+
+func (p clusterSlotSlice) Less(i, j int) bool {
+	return p[i].start < p[j].start
+}
+
+func (p clusterSlotSlice) Swap(i, j int) {
+	p[i], p[j] = p[j], p[i]
+}
+
+type clusterState struct {
+	nodes   *clusterNodes
+	Masters []*clusterNode
+	Slaves  []*clusterNode
+
+	slots []*clusterSlot
+
+	generation uint32
+	createdAt  time.Time
+}
+
+func newClusterState(
+	nodes *clusterNodes, slots []ClusterSlot, origin string,
+) (*clusterState, error) {
+	c := clusterState{
+		nodes: nodes,
+
+		slots: make([]*clusterSlot, 0, len(slots)),
+
+		generation: nodes.NextGeneration(),
+		createdAt:  time.Now(),
+	}
+
+	isLoopbackOrigin := isLoopbackAddr(origin)
+	for _, slot := range slots {
+		var nodes []*clusterNode
+		for i, slotNode := range slot.Nodes {
+			addr := slotNode.Addr
+			if !isLoopbackOrigin && useOriginAddr(origin, addr) {
+				addr = origin
+			}
+
+			node, err := c.nodes.GetOrCreate(addr)
+			if err != nil {
+				return nil, err
+			}
+
+			node.SetGeneration(c.generation)
+			nodes = append(nodes, node)
+
+			if i == 0 {
+				c.Masters = appendUniqueNode(c.Masters, node)
+			} else {
+				c.Slaves = appendUniqueNode(c.Slaves, node)
+			}
+		}
+
+		c.slots = append(c.slots, &clusterSlot{
+			start: slot.Start,
+			end:   slot.End,
+			nodes: nodes,
+		})
+	}
+
+	sort.Sort(clusterSlotSlice(c.slots))
+
+	time.AfterFunc(time.Minute, func() {
+		nodes.GC(c.generation)
+	})
+
+	return &c, nil
+}
+
+func (c *clusterState) slotMasterNode(slot int) (*clusterNode, error) {
+	nodes := c.slotNodes(slot)
+	if len(nodes) > 0 {
+		return nodes[0], nil
+	}
+	return c.nodes.Random()
+}
+
+func (c *clusterState) slotSlaveNode(slot int) (*clusterNode, error) {
+	nodes := c.slotNodes(slot)
+	switch len(nodes) {
+	case 0:
+		return c.nodes.Random()
+	case 1:
+		return nodes[0], nil
+	case 2:
+		if slave := nodes[1]; !slave.Loading() {
+			return slave, nil
+		}
+		return nodes[0], nil
+	default:
+		var slave *clusterNode
+		for i := 0; i < 10; i++ {
+			n := rand.Intn(len(nodes)-1) + 1
+			slave = nodes[n]
+			if !slave.Loading() {
+				break
+			}
+		}
+		return slave, nil
+	}
+}
+
+func (c *clusterState) slotClosestNode(slot int) (*clusterNode, error) {
+	const threshold = time.Millisecond
+
+	nodes := c.slotNodes(slot)
+	if len(nodes) == 0 {
+		return c.nodes.Random()
+	}
+
+	var node *clusterNode
+	for _, n := range nodes {
+		if n.Loading() {
+			continue
+		}
+		if node == nil || node.Latency()-n.Latency() > threshold {
+			node = n
+		}
+	}
+	return node, nil
+}
+
+func (c *clusterState) slotRandomNode(slot int) *clusterNode {
+	nodes := c.slotNodes(slot)
+	n := rand.Intn(len(nodes))
+	return nodes[n]
+}
+
+func (c *clusterState) slotNodes(slot int) []*clusterNode {
+	i := sort.Search(len(c.slots), func(i int) bool {
+		return c.slots[i].end >= slot
+	})
+	if i >= len(c.slots) {
+		return nil
+	}
+	x := c.slots[i]
+	if slot >= x.start && slot <= x.end {
+		return x.nodes
+	}
+	return nil
+}
+
+func (c *clusterState) IsConsistent() bool {
+	if c.nodes.opt.ClusterSlots != nil {
+		return true
+	}
+	return len(c.Masters) <= len(c.Slaves)
+}
+
+//------------------------------------------------------------------------------
+
+type clusterStateHolder struct {
+	load func() (*clusterState, error)
+
+	state atomic.Value
+
+	firstErrMu sync.RWMutex
+	firstErr   error
+
+	reloading uint32 // atomic
+}
+
+func newClusterStateHolder(fn func() (*clusterState, error)) *clusterStateHolder {
+	return &clusterStateHolder{
+		load: fn,
+	}
+}
+
+func (c *clusterStateHolder) Reload() (*clusterState, error) {
+	state, err := c.reload()
+	if err != nil {
+		return nil, err
+	}
+	if !state.IsConsistent() {
+		time.AfterFunc(time.Second, c.LazyReload)
+	}
+	return state, nil
+}
+
+func (c *clusterStateHolder) reload() (*clusterState, error) {
+	state, err := c.load()
+	if err != nil {
+		c.firstErrMu.Lock()
+		if c.firstErr == nil {
+			c.firstErr = err
+		}
+		c.firstErrMu.Unlock()
+		return nil, err
+	}
+	c.state.Store(state)
+	return state, nil
+}
+
+func (c *clusterStateHolder) LazyReload() {
+	if !atomic.CompareAndSwapUint32(&c.reloading, 0, 1) {
+		return
+	}
+	go func() {
+		defer atomic.StoreUint32(&c.reloading, 0)
+
+		for {
+			state, err := c.reload()
+			if err != nil {
+				return
+			}
+			time.Sleep(100 * time.Millisecond)
+			if state.IsConsistent() {
+				return
+			}
+		}
+	}()
+}
+
+func (c *clusterStateHolder) Get() (*clusterState, error) {
+	v := c.state.Load()
+	if v != nil {
+		state := v.(*clusterState)
+		if time.Since(state.createdAt) > time.Minute {
+			c.LazyReload()
+		}
+		return state, nil
+	}
+
+	c.firstErrMu.RLock()
+	err := c.firstErr
+	c.firstErrMu.RUnlock()
+	if err != nil {
+		return nil, err
+	}
+
+	return nil, errors.New("redis: cluster has no state")
+}
+
+func (c *clusterStateHolder) ReloadOrGet() (*clusterState, error) {
+	state, err := c.Reload()
+	if err == nil {
+		return state, nil
+	}
+	return c.Get()
+}
+
+//------------------------------------------------------------------------------
+
+// ClusterClient is a Redis Cluster client representing a pool of zero
+// or more underlying connections. It's safe for concurrent use by
+// multiple goroutines.
+type ClusterClient struct {
+	cmdable
+
+	ctx context.Context
+
+	opt           *ClusterOptions
+	nodes         *clusterNodes
+	state         *clusterStateHolder
+	cmdsInfoCache *cmdsInfoCache
+
+	process           func(Cmder) error
+	processPipeline   func([]Cmder) error
+	processTxPipeline func([]Cmder) error
+}
+
+// NewClusterClient returns a Redis Cluster client as described in
+// http://redis.io/topics/cluster-spec.
+func NewClusterClient(opt *ClusterOptions) *ClusterClient {
+	opt.init()
+
+	c := &ClusterClient{
+		opt:   opt,
+		nodes: newClusterNodes(opt),
+	}
+	c.state = newClusterStateHolder(c.loadState)
+	c.cmdsInfoCache = newCmdsInfoCache(c.cmdsInfo)
+
+	c.process = c.defaultProcess
+	c.processPipeline = c.defaultProcessPipeline
+	c.processTxPipeline = c.defaultProcessTxPipeline
+
+	c.init()
+
+	_, _ = c.state.Reload()
+	_, _ = c.cmdsInfoCache.Get()
+
+	if opt.IdleCheckFrequency > 0 {
+		go c.reaper(opt.IdleCheckFrequency)
+	}
+
+	return c
+}
+
+// ReloadState reloads cluster state. It calls ClusterSlots func
+// to get cluster slots information.
+func (c *ClusterClient) ReloadState() error {
+	_, err := c.state.Reload()
+	return err
+}
+
+func (c *ClusterClient) init() {
+	c.cmdable.setProcessor(c.Process)
+}
+
+func (c *ClusterClient) Context() context.Context {
+	if c.ctx != nil {
+		return c.ctx
+	}
+	return context.Background()
+}
+
+func (c *ClusterClient) WithContext(ctx context.Context) *ClusterClient {
+	if ctx == nil {
+		panic("nil context")
+	}
+	c2 := c.copy()
+	c2.ctx = ctx
+	return c2
+}
+
+func (c *ClusterClient) copy() *ClusterClient {
+	cp := *c
+	cp.init()
+	return &cp
+}
+
+// Options returns read-only Options that were used to create the client.
+func (c *ClusterClient) Options() *ClusterOptions {
+	return c.opt
+}
+
+func (c *ClusterClient) retryBackoff(attempt int) time.Duration {
+	return internal.RetryBackoff(attempt, c.opt.MinRetryBackoff, c.opt.MaxRetryBackoff)
+}
+
+func (c *ClusterClient) cmdsInfo() (map[string]*CommandInfo, error) {
+	addrs, err := c.nodes.Addrs()
+	if err != nil {
+		return nil, err
+	}
+
+	var firstErr error
+	for _, addr := range addrs {
+		node, err := c.nodes.Get(addr)
+		if err != nil {
+			return nil, err
+		}
+		if node == nil {
+			continue
+		}
+
+		info, err := node.Client.Command().Result()
+		if err == nil {
+			return info, nil
+		}
+		if firstErr == nil {
+			firstErr = err
+		}
+	}
+	return nil, firstErr
+}
+
+func (c *ClusterClient) cmdInfo(name string) *CommandInfo {
+	cmdsInfo, err := c.cmdsInfoCache.Get()
+	if err != nil {
+		return nil
+	}
+
+	info := cmdsInfo[name]
+	if info == nil {
+		internal.Logf("info for cmd=%s not found", name)
+	}
+	return info
+}
+
+func cmdSlot(cmd Cmder, pos int) int {
+	if pos == 0 {
+		return hashtag.RandomSlot()
+	}
+	firstKey := cmd.stringArg(pos)
+	return hashtag.Slot(firstKey)
+}
+
+func (c *ClusterClient) cmdSlot(cmd Cmder) int {
+	cmdInfo := c.cmdInfo(cmd.Name())
+	return cmdSlot(cmd, cmdFirstKeyPos(cmd, cmdInfo))
+}
+
+func (c *ClusterClient) cmdSlotAndNode(cmd Cmder) (int, *clusterNode, error) {
+	state, err := c.state.Get()
+	if err != nil {
+		return 0, nil, err
+	}
+
+	cmdInfo := c.cmdInfo(cmd.Name())
+	slot := cmdSlot(cmd, cmdFirstKeyPos(cmd, cmdInfo))
+
+	if cmdInfo != nil && cmdInfo.ReadOnly && c.opt.ReadOnly {
+		if c.opt.RouteByLatency {
+			node, err := state.slotClosestNode(slot)
+			return slot, node, err
+		}
+
+		if c.opt.RouteRandomly {
+			node := state.slotRandomNode(slot)
+			return slot, node, nil
+		}
+
+		node, err := state.slotSlaveNode(slot)
+		return slot, node, err
+	}
+
+	node, err := state.slotMasterNode(slot)
+	return slot, node, err
+}
+
+func (c *ClusterClient) slotMasterNode(slot int) (*clusterNode, error) {
+	state, err := c.state.Get()
+	if err != nil {
+		return nil, err
+	}
+
+	nodes := state.slotNodes(slot)
+	if len(nodes) > 0 {
+		return nodes[0], nil
+	}
+	return c.nodes.Random()
+}
+
+func (c *ClusterClient) Watch(fn func(*Tx) error, keys ...string) error {
+	if len(keys) == 0 {
+		return fmt.Errorf("redis: Watch requires at least one key")
+	}
+
+	slot := hashtag.Slot(keys[0])
+	for _, key := range keys[1:] {
+		if hashtag.Slot(key) != slot {
+			err := fmt.Errorf("redis: Watch requires all keys to be in the same slot")
+			return err
+		}
+	}
+
+	node, err := c.slotMasterNode(slot)
+	if err != nil {
+		return err
+	}
+
+	for attempt := 0; attempt <= c.opt.MaxRedirects; attempt++ {
+		if attempt > 0 {
+			time.Sleep(c.retryBackoff(attempt))
+		}
+
+		err = node.Client.Watch(fn, keys...)
+		if err == nil {
+			break
+		}
+
+		if internal.IsRetryableError(err, true) {
+			c.state.LazyReload()
+			continue
+		}
+
+		moved, ask, addr := internal.IsMovedError(err)
+		if moved || ask {
+			c.state.LazyReload()
+			node, err = c.nodes.GetOrCreate(addr)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		if err == pool.ErrClosed {
+			node, err = c.slotMasterNode(slot)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		return err
+	}
+
+	return err
+}
+
+// Close closes the cluster client, releasing any open resources.
+//
+// It is rare to Close a ClusterClient, as the ClusterClient is meant
+// to be long-lived and shared between many goroutines.
+func (c *ClusterClient) Close() error {
+	return c.nodes.Close()
+}
+
+func (c *ClusterClient) WrapProcess(
+	fn func(oldProcess func(Cmder) error) func(Cmder) error,
+) {
+	c.process = fn(c.process)
+}
+
+func (c *ClusterClient) Process(cmd Cmder) error {
+	return c.process(cmd)
+}
+
+func (c *ClusterClient) defaultProcess(cmd Cmder) error {
+	var node *clusterNode
+	var ask bool
+	for attempt := 0; attempt <= c.opt.MaxRedirects; attempt++ {
+		if attempt > 0 {
+			time.Sleep(c.retryBackoff(attempt))
+		}
+
+		if node == nil {
+			var err error
+			_, node, err = c.cmdSlotAndNode(cmd)
+			if err != nil {
+				cmd.setErr(err)
+				break
+			}
+		}
+
+		var err error
+		if ask {
+			pipe := node.Client.Pipeline()
+			_ = pipe.Process(NewCmd("ASKING"))
+			_ = pipe.Process(cmd)
+			_, err = pipe.Exec()
+			_ = pipe.Close()
+			ask = false
+		} else {
+			err = node.Client.Process(cmd)
+		}
+
+		// If there is no error - we are done.
+		if err == nil {
+			break
+		}
+
+		// If slave is loading - read from master.
+		if c.opt.ReadOnly && internal.IsLoadingError(err) {
+			node.MarkAsLoading()
+			continue
+		}
+
+		if internal.IsRetryableError(err, true) {
+			c.state.LazyReload()
+
+			// First retry the same node.
+			if attempt == 0 {
+				continue
+			}
+
+			// Second try random node.
+			node, err = c.nodes.Random()
+			if err != nil {
+				break
+			}
+			continue
+		}
+
+		var moved bool
+		var addr string
+		moved, ask, addr = internal.IsMovedError(err)
+		if moved || ask {
+			c.state.LazyReload()
+
+			node, err = c.nodes.GetOrCreate(addr)
+			if err != nil {
+				break
+			}
+			continue
+		}
+
+		if err == pool.ErrClosed {
+			node = nil
+			continue
+		}
+
+		break
+	}
+
+	return cmd.Err()
+}
+
+// ForEachMaster concurrently calls the fn on each master node in the cluster.
+// It returns the first error if any.
+func (c *ClusterClient) ForEachMaster(fn func(client *Client) error) error {
+	state, err := c.state.ReloadOrGet()
+	if err != nil {
+		return err
+	}
+
+	var wg sync.WaitGroup
+	errCh := make(chan error, 1)
+	for _, master := range state.Masters {
+		wg.Add(1)
+		go func(node *clusterNode) {
+			defer wg.Done()
+			err := fn(node.Client)
+			if err != nil {
+				select {
+				case errCh <- err:
+				default:
+				}
+			}
+		}(master)
+	}
+	wg.Wait()
+
+	select {
+	case err := <-errCh:
+		return err
+	default:
+		return nil
+	}
+}
+
+// ForEachSlave concurrently calls the fn on each slave node in the cluster.
+// It returns the first error if any.
+func (c *ClusterClient) ForEachSlave(fn func(client *Client) error) error {
+	state, err := c.state.ReloadOrGet()
+	if err != nil {
+		return err
+	}
+
+	var wg sync.WaitGroup
+	errCh := make(chan error, 1)
+	for _, slave := range state.Slaves {
+		wg.Add(1)
+		go func(node *clusterNode) {
+			defer wg.Done()
+			err := fn(node.Client)
+			if err != nil {
+				select {
+				case errCh <- err:
+				default:
+				}
+			}
+		}(slave)
+	}
+	wg.Wait()
+
+	select {
+	case err := <-errCh:
+		return err
+	default:
+		return nil
+	}
+}
+
+// ForEachNode concurrently calls the fn on each known node in the cluster.
+// It returns the first error if any.
+func (c *ClusterClient) ForEachNode(fn func(client *Client) error) error {
+	state, err := c.state.ReloadOrGet()
+	if err != nil {
+		return err
+	}
+
+	var wg sync.WaitGroup
+	errCh := make(chan error, 1)
+	worker := func(node *clusterNode) {
+		defer wg.Done()
+		err := fn(node.Client)
+		if err != nil {
+			select {
+			case errCh <- err:
+			default:
+			}
+		}
+	}
+
+	for _, node := range state.Masters {
+		wg.Add(1)
+		go worker(node)
+	}
+	for _, node := range state.Slaves {
+		wg.Add(1)
+		go worker(node)
+	}
+
+	wg.Wait()
+	select {
+	case err := <-errCh:
+		return err
+	default:
+		return nil
+	}
+}
+
+// PoolStats returns accumulated connection pool stats.
+func (c *ClusterClient) PoolStats() *PoolStats {
+	var acc PoolStats
+
+	state, _ := c.state.Get()
+	if state == nil {
+		return &acc
+	}
+
+	for _, node := range state.Masters {
+		s := node.Client.connPool.Stats()
+		acc.Hits += s.Hits
+		acc.Misses += s.Misses
+		acc.Timeouts += s.Timeouts
+
+		acc.TotalConns += s.TotalConns
+		acc.FreeConns += s.FreeConns
+		acc.StaleConns += s.StaleConns
+	}
+
+	for _, node := range state.Slaves {
+		s := node.Client.connPool.Stats()
+		acc.Hits += s.Hits
+		acc.Misses += s.Misses
+		acc.Timeouts += s.Timeouts
+
+		acc.TotalConns += s.TotalConns
+		acc.FreeConns += s.FreeConns
+		acc.StaleConns += s.StaleConns
+	}
+
+	return &acc
+}
+
+func (c *ClusterClient) loadState() (*clusterState, error) {
+	if c.opt.ClusterSlots != nil {
+		slots, err := c.opt.ClusterSlots()
+		if err != nil {
+			return nil, err
+		}
+		return newClusterState(c.nodes, slots, "")
+	}
+
+	addrs, err := c.nodes.Addrs()
+	if err != nil {
+		return nil, err
+	}
+
+	var firstErr error
+	for _, addr := range addrs {
+		node, err := c.nodes.GetOrCreate(addr)
+		if err != nil {
+			if firstErr == nil {
+				firstErr = err
+			}
+			continue
+		}
+
+		slots, err := node.Client.ClusterSlots().Result()
+		if err != nil {
+			if firstErr == nil {
+				firstErr = err
+			}
+			continue
+		}
+
+		return newClusterState(c.nodes, slots, node.Client.opt.Addr)
+	}
+
+	return nil, firstErr
+}
+
+// reaper closes idle connections to the cluster.
+func (c *ClusterClient) reaper(idleCheckFrequency time.Duration) {
+	ticker := time.NewTicker(idleCheckFrequency)
+	defer ticker.Stop()
+
+	for range ticker.C {
+		nodes, err := c.nodes.All()
+		if err != nil {
+			break
+		}
+
+		for _, node := range nodes {
+			_, err := node.Client.connPool.(*pool.ConnPool).ReapStaleConns()
+			if err != nil {
+				internal.Logf("ReapStaleConns failed: %s", err)
+			}
+		}
+	}
+}
+
+func (c *ClusterClient) Pipeline() Pipeliner {
+	pipe := Pipeline{
+		exec: c.processPipeline,
+	}
+	pipe.statefulCmdable.setProcessor(pipe.Process)
+	return &pipe
+}
+
+func (c *ClusterClient) Pipelined(fn func(Pipeliner) error) ([]Cmder, error) {
+	return c.Pipeline().Pipelined(fn)
+}
+
+func (c *ClusterClient) WrapProcessPipeline(
+	fn func(oldProcess func([]Cmder) error) func([]Cmder) error,
+) {
+	c.processPipeline = fn(c.processPipeline)
+}
+
+func (c *ClusterClient) defaultProcessPipeline(cmds []Cmder) error {
+	cmdsMap, err := c.mapCmdsByNode(cmds)
+	if err != nil {
+		setCmdsErr(cmds, err)
+		return err
+	}
+
+	for attempt := 0; attempt <= c.opt.MaxRedirects; attempt++ {
+		if attempt > 0 {
+			time.Sleep(c.retryBackoff(attempt))
+		}
+
+		failedCmds := make(map[*clusterNode][]Cmder)
+
+		for node, cmds := range cmdsMap {
+			cn, err := node.Client.getConn()
+			if err != nil {
+				if err == pool.ErrClosed {
+					c.remapCmds(cmds, failedCmds)
+				} else {
+					setCmdsErr(cmds, err)
+				}
+				continue
+			}
+
+			err = c.pipelineProcessCmds(node, cn, cmds, failedCmds)
+			if err == nil || internal.IsRedisError(err) {
+				node.Client.connPool.Put(cn)
+			} else {
+				node.Client.connPool.Remove(cn)
+			}
+		}
+
+		if len(failedCmds) == 0 {
+			break
+		}
+		cmdsMap = failedCmds
+	}
+
+	return firstCmdsErr(cmds)
+}
+
+func (c *ClusterClient) mapCmdsByNode(cmds []Cmder) (map[*clusterNode][]Cmder, error) {
+	state, err := c.state.Get()
+	if err != nil {
+		setCmdsErr(cmds, err)
+		return nil, err
+	}
+
+	cmdsMap := make(map[*clusterNode][]Cmder)
+	cmdsAreReadOnly := c.cmdsAreReadOnly(cmds)
+	for _, cmd := range cmds {
+		var node *clusterNode
+		var err error
+		if cmdsAreReadOnly {
+			_, node, err = c.cmdSlotAndNode(cmd)
+		} else {
+			slot := c.cmdSlot(cmd)
+			node, err = state.slotMasterNode(slot)
+		}
+		if err != nil {
+			return nil, err
+		}
+		cmdsMap[node] = append(cmdsMap[node], cmd)
+	}
+	return cmdsMap, nil
+}
+
+func (c *ClusterClient) cmdsAreReadOnly(cmds []Cmder) bool {
+	for _, cmd := range cmds {
+		cmdInfo := c.cmdInfo(cmd.Name())
+		if cmdInfo == nil || !cmdInfo.ReadOnly {
+			return false
+		}
+	}
+	return true
+}
+
+func (c *ClusterClient) remapCmds(cmds []Cmder, failedCmds map[*clusterNode][]Cmder) {
+	remappedCmds, err := c.mapCmdsByNode(cmds)
+	if err != nil {
+		setCmdsErr(cmds, err)
+		return
+	}
+
+	for node, cmds := range remappedCmds {
+		failedCmds[node] = cmds
+	}
+}
+
+func (c *ClusterClient) pipelineProcessCmds(
+	node *clusterNode, cn *pool.Conn, cmds []Cmder, failedCmds map[*clusterNode][]Cmder,
+) error {
+	cn.SetWriteTimeout(c.opt.WriteTimeout)
+
+	err := writeCmd(cn, cmds...)
+	if err != nil {
+		setCmdsErr(cmds, err)
+		failedCmds[node] = cmds
+		return err
+	}
+
+	// Set read timeout for all commands.
+	cn.SetReadTimeout(c.opt.ReadTimeout)
+
+	return c.pipelineReadCmds(cn, cmds, failedCmds)
+}
+
+func (c *ClusterClient) pipelineReadCmds(
+	cn *pool.Conn, cmds []Cmder, failedCmds map[*clusterNode][]Cmder,
+) error {
+	for _, cmd := range cmds {
+		err := cmd.readReply(cn)
+		if err == nil {
+			continue
+		}
+
+		if c.checkMovedErr(cmd, err, failedCmds) {
+			continue
+		}
+
+		if internal.IsRedisError(err) {
+			continue
+		}
+
+		return err
+	}
+	return nil
+}
+
+func (c *ClusterClient) checkMovedErr(
+	cmd Cmder, err error, failedCmds map[*clusterNode][]Cmder,
+) bool {
+	moved, ask, addr := internal.IsMovedError(err)
+
+	if moved {
+		c.state.LazyReload()
+
+		node, err := c.nodes.GetOrCreate(addr)
+		if err != nil {
+			return false
+		}
+
+		failedCmds[node] = append(failedCmds[node], cmd)
+		return true
+	}
+
+	if ask {
+		node, err := c.nodes.GetOrCreate(addr)
+		if err != nil {
+			return false
+		}
+
+		failedCmds[node] = append(failedCmds[node], NewCmd("ASKING"), cmd)
+		return true
+	}
+
+	return false
+}
+
+// TxPipeline acts like Pipeline, but wraps queued commands with MULTI/EXEC.
+func (c *ClusterClient) TxPipeline() Pipeliner {
+	pipe := Pipeline{
+		exec: c.processTxPipeline,
+	}
+	pipe.statefulCmdable.setProcessor(pipe.Process)
+	return &pipe
+}
+
+func (c *ClusterClient) TxPipelined(fn func(Pipeliner) error) ([]Cmder, error) {
+	return c.TxPipeline().Pipelined(fn)
+}
+
+func (c *ClusterClient) defaultProcessTxPipeline(cmds []Cmder) error {
+	state, err := c.state.Get()
+	if err != nil {
+		return err
+	}
+
+	cmdsMap := c.mapCmdsBySlot(cmds)
+	for slot, cmds := range cmdsMap {
+		node, err := state.slotMasterNode(slot)
+		if err != nil {
+			setCmdsErr(cmds, err)
+			continue
+		}
+		cmdsMap := map[*clusterNode][]Cmder{node: cmds}
+
+		for attempt := 0; attempt <= c.opt.MaxRedirects; attempt++ {
+			if attempt > 0 {
+				time.Sleep(c.retryBackoff(attempt))
+			}
+
+			failedCmds := make(map[*clusterNode][]Cmder)
+
+			for node, cmds := range cmdsMap {
+				cn, err := node.Client.getConn()
+				if err != nil {
+					if err == pool.ErrClosed {
+						c.remapCmds(cmds, failedCmds)
+					} else {
+						setCmdsErr(cmds, err)
+					}
+					continue
+				}
+
+				err = c.txPipelineProcessCmds(node, cn, cmds, failedCmds)
+				if err == nil || internal.IsRedisError(err) {
+					node.Client.connPool.Put(cn)
+				} else {
+					node.Client.connPool.Remove(cn)
+				}
+			}
+
+			if len(failedCmds) == 0 {
+				break
+			}
+			cmdsMap = failedCmds
+		}
+	}
+
+	return firstCmdsErr(cmds)
+}
+
+func (c *ClusterClient) mapCmdsBySlot(cmds []Cmder) map[int][]Cmder {
+	cmdsMap := make(map[int][]Cmder)
+	for _, cmd := range cmds {
+		slot := c.cmdSlot(cmd)
+		cmdsMap[slot] = append(cmdsMap[slot], cmd)
+	}
+	return cmdsMap
+}
+
+func (c *ClusterClient) txPipelineProcessCmds(
+	node *clusterNode, cn *pool.Conn, cmds []Cmder, failedCmds map[*clusterNode][]Cmder,
+) error {
+	cn.SetWriteTimeout(c.opt.WriteTimeout)
+	if err := txPipelineWriteMulti(cn, cmds); err != nil {
+		setCmdsErr(cmds, err)
+		failedCmds[node] = cmds
+		return err
+	}
+
+	// Set read timeout for all commands.
+	cn.SetReadTimeout(c.opt.ReadTimeout)
+
+	if err := c.txPipelineReadQueued(cn, cmds, failedCmds); err != nil {
+		setCmdsErr(cmds, err)
+		return err
+	}
+
+	return pipelineReadCmds(cn, cmds)
+}
+
+func (c *ClusterClient) txPipelineReadQueued(
+	cn *pool.Conn, cmds []Cmder, failedCmds map[*clusterNode][]Cmder,
+) error {
+	// Parse queued replies.
+	var statusCmd StatusCmd
+	if err := statusCmd.readReply(cn); err != nil {
+		return err
+	}
+
+	for _, cmd := range cmds {
+		err := statusCmd.readReply(cn)
+		if err == nil {
+			continue
+		}
+
+		if c.checkMovedErr(cmd, err, failedCmds) || internal.IsRedisError(err) {
+			continue
+		}
+
+		return err
+	}
+
+	// Parse number of replies.
+	line, err := cn.Rd.ReadLine()
+	if err != nil {
+		if err == Nil {
+			err = TxFailedErr
+		}
+		return err
+	}
+
+	switch line[0] {
+	case proto.ErrorReply:
+		err := proto.ParseErrorReply(line)
+		for _, cmd := range cmds {
+			if !c.checkMovedErr(cmd, err, failedCmds) {
+				break
+			}
+		}
+		return err
+	case proto.ArrayReply:
+		// ok
+	default:
+		err := fmt.Errorf("redis: expected '*', but got line %q", line)
+		return err
+	}
+
+	return nil
+}
+
+func (c *ClusterClient) pubSub(channels []string) *PubSub {
+	var node *clusterNode
+	pubsub := &PubSub{
+		opt: c.opt.clientOptions(),
+
+		newConn: func(channels []string) (*pool.Conn, error) {
+			if node == nil {
+				var slot int
+				if len(channels) > 0 {
+					slot = hashtag.Slot(channels[0])
+				} else {
+					slot = -1
+				}
+
+				masterNode, err := c.slotMasterNode(slot)
+				if err != nil {
+					return nil, err
+				}
+				node = masterNode
+			}
+			return node.Client.newConn()
+		},
+		closeConn: func(cn *pool.Conn) error {
+			return node.Client.connPool.CloseConn(cn)
+		},
+	}
+	pubsub.init()
+	return pubsub
+}
+
+// Subscribe subscribes the client to the specified channels.
+// Channels can be omitted to create empty subscription.
+func (c *ClusterClient) Subscribe(channels ...string) *PubSub {
+	pubsub := c.pubSub(channels)
+	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 *ClusterClient) PSubscribe(channels ...string) *PubSub {
+	pubsub := c.pubSub(channels)
+	if len(channels) > 0 {
+		_ = pubsub.PSubscribe(channels...)
+	}
+	return pubsub
+}
+
+func useOriginAddr(originAddr, nodeAddr string) bool {
+	nodeHost, nodePort, err := net.SplitHostPort(nodeAddr)
+	if err != nil {
+		return false
+	}
+
+	nodeIP := net.ParseIP(nodeHost)
+	if nodeIP == nil {
+		return false
+	}
+
+	if !nodeIP.IsLoopback() {
+		return false
+	}
+
+	_, originPort, err := net.SplitHostPort(originAddr)
+	if err != nil {
+		return false
+	}
+
+	return nodePort == originPort
+}
+
+func isLoopbackAddr(addr string) bool {
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		return false
+	}
+
+	ip := net.ParseIP(host)
+	if ip == nil {
+		return false
+	}
+
+	return ip.IsLoopback()
+}
+
+func appendUniqueNode(nodes []*clusterNode, node *clusterNode) []*clusterNode {
+	for _, n := range nodes {
+		if n == node {
+			return nodes
+		}
+	}
+	return append(nodes, node)
+}
+
+func appendIfNotExists(ss []string, es ...string) []string {
+loop:
+	for _, e := range es {
+		for _, s := range ss {
+			if s == e {
+				continue loop
+			}
+		}
+		ss = append(ss, e)
+	}
+	return ss
+}
+
+func remove(ss []string, es ...string) []string {
+	if len(es) == 0 {
+		return ss[:0]
+	}
+	for _, e := range es {
+		for i, s := range ss {
+			if s == e {
+				ss = append(ss[:i], ss[i+1:]...)
+				break
+			}
+		}
+	}
+	return ss
+}