package redis import ( "fmt" "math/rand" "net" "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" ) var errClusterNoNodes = fmt.Errorf("redis: cluster has no nodes") var errNilClusterState = fmt.Errorf("redis: cannot load cluster slots") // 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 16. MaxRedirects int // Enables read-only commands on slave nodes. ReadOnly bool // Allows routing read-only commands to the closest master or slave node. RouteByLatency bool // 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 } func (opt *ClusterOptions) init() { if opt.MaxRedirects == -1 { opt.MaxRedirects = 0 } else if opt.MaxRedirects == 0 { opt.MaxRedirects = 16 } if opt.RouteByLatency { 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, } } //------------------------------------------------------------------------------ type clusterNode struct { Client *Client Latency time.Duration loading time.Time generation uint32 } func newClusterNode(clOpt *ClusterOptions, addr string) *clusterNode { opt := clOpt.clientOptions() opt.Addr = addr node := clusterNode{ Client: NewClient(opt), } if clOpt.RouteByLatency { node.updateLatency() } return &node } func (n *clusterNode) updateLatency() { const probes = 10 for i := 0; i < probes; i++ { start := time.Now() n.Client.Ping() n.Latency += time.Since(start) } n.Latency = n.Latency / probes } func (n *clusterNode) Loading() bool { return !n.loading.IsZero() && time.Since(n.loading) < time.Minute } func (n *clusterNode) Generation() uint32 { return n.generation } func (n *clusterNode) SetGeneration(gen uint32) { if gen < n.generation { panic("gen < n.generation") } n.generation = gen } //------------------------------------------------------------------------------ type clusterNodes struct { opt *ClusterOptions mu sync.RWMutex addrs []string nodes map[string]*clusterNode closed bool generation uint32 } func newClusterNodes(opt *ClusterOptions) *clusterNodes { return &clusterNodes{ opt: opt, nodes: 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.nodes { if err := node.Client.Close(); err != nil && firstErr == nil { firstErr = err } } c.addrs = nil c.nodes = nil return firstErr } func (c *clusterNodes) Addrs() ([]string, error) { c.mu.RLock() closed := c.closed addrs := c.addrs c.mu.RUnlock() if closed { return nil, pool.ErrClosed } if len(addrs) == 0 { return nil, errClusterNoNodes } return addrs, nil } func (c *clusterNodes) NextGeneration() uint32 { c.generation++ return c.generation } // GC removes unused nodes. func (c *clusterNodes) GC(generation uint32) error { var collected []*clusterNode c.mu.Lock() for i := 0; i < len(c.addrs); { addr := c.addrs[i] node := c.nodes[addr] if node.Generation() >= generation { i++ continue } c.addrs = append(c.addrs[:i], c.addrs[i+1:]...) delete(c.nodes, addr) collected = append(collected, node) } c.mu.Unlock() var firstErr error for _, node := range collected { if err := node.Client.Close(); err != nil && firstErr == nil { firstErr = err } } return firstErr } func (c *clusterNodes) All() ([]*clusterNode, error) { c.mu.RLock() defer c.mu.RUnlock() if c.closed { return nil, pool.ErrClosed } nodes := make([]*clusterNode, 0, len(c.nodes)) for _, node := range c.nodes { nodes = append(nodes, node) } return nodes, nil } func (c *clusterNodes) GetOrCreate(addr string) (*clusterNode, error) { var node *clusterNode var ok bool c.mu.RLock() if !c.closed { node, ok = c.nodes[addr] } c.mu.RUnlock() if ok { return node, nil } c.mu.Lock() defer c.mu.Unlock() if c.closed { return nil, pool.ErrClosed } node, ok = c.nodes[addr] if ok { return node, nil } c.addrs = append(c.addrs, addr) node = newClusterNode(c.opt, addr) c.nodes[addr] = node return node, nil } func (c *clusterNodes) Random() (*clusterNode, error) { addrs, err := c.Addrs() if err != nil { return nil, err } var nodeErr error for i := 0; i <= c.opt.MaxRedirects; i++ { n := rand.Intn(len(addrs)) node, err := c.GetOrCreate(addrs[n]) if err != nil { return nil, err } nodeErr = node.Client.ClusterInfo().Err() if nodeErr == nil { return node, nil } } return nil, nodeErr } //------------------------------------------------------------------------------ type clusterState struct { nodes *clusterNodes masters []*clusterNode slaves []*clusterNode slots [][]*clusterNode generation uint32 } func newClusterState(nodes *clusterNodes, slots []ClusterSlot, origin string) (*clusterState, error) { c := clusterState{ nodes: nodes, generation: nodes.NextGeneration(), slots: make([][]*clusterNode, hashtag.SlotNumber), } isLoopbackOrigin := isLoopbackAddr(origin) for _, slot := range slots { var nodes []*clusterNode for i, slotNode := range slot.Nodes { addr := slotNode.Addr if !isLoopbackOrigin && isLoopbackAddr(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 = appendNode(c.masters, node) } else { c.slaves = appendNode(c.slaves, node) } } for i := slot.Start; i <= slot.End; i++ { c.slots[i] = nodes } } 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) slotNodes(slot int) []*clusterNode { if slot >= 0 && slot < len(c.slots) { return c.slots[slot] } return nil } //------------------------------------------------------------------------------ // 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 opt *ClusterOptions nodes *clusterNodes _state atomic.Value cmdsInfoOnce internal.Once cmdsInfo map[string]*CommandInfo // Reports whether slots reloading is in progress. reloading uint32 } // 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.setProcessor(c.Process) // Add initial nodes. for _, addr := range opt.Addrs { _, _ = c.nodes.GetOrCreate(addr) } // Preload cluster slots. for i := 0; i < 10; i++ { state, err := c.reloadState() if err == nil { c._state.Store(state) break } } if opt.IdleCheckFrequency > 0 { go c.reaper(opt.IdleCheckFrequency) } return c } // 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) state() (*clusterState, error) { v := c._state.Load() if v != nil { return v.(*clusterState), nil } _, err := c.nodes.Addrs() if err != nil { return nil, err } c.lazyReloadState() return nil, errNilClusterState } func (c *ClusterClient) cmdInfo(name string) *CommandInfo { err := c.cmdsInfoOnce.Do(func() error { node, err := c.nodes.Random() if err != nil { return err } cmdsInfo, err := node.Client.Command().Result() if err != nil { return err } c.cmdsInfo = cmdsInfo return nil }) if err != nil { return nil } info := c.cmdsInfo[name] if info == nil { internal.Logf("info for cmd=%s not found", name) } return info } func (c *ClusterClient) cmdSlot(cmd Cmder) int { cmdInfo := c.cmdInfo(cmd.Name()) firstKey := cmd.stringArg(cmdFirstKeyPos(cmd, cmdInfo)) return hashtag.Slot(firstKey) } func (c *ClusterClient) cmdSlotAndNode(state *clusterState, cmd Cmder) (int, *clusterNode, error) { cmdInfo := c.cmdInfo(cmd.Name()) firstKey := cmd.stringArg(cmdFirstKeyPos(cmd, cmdInfo)) slot := hashtag.Slot(firstKey) if cmdInfo != nil && cmdInfo.ReadOnly && c.opt.ReadOnly { if c.opt.RouteByLatency { node, err := state.slotClosestNode(slot) return slot, node, err } node, err := state.slotSlaveNode(slot) return slot, node, err } node, err := state.slotMasterNode(slot) return slot, node, err } func (c *ClusterClient) Watch(fn func(*Tx) error, keys ...string) error { if len(keys) == 0 { return fmt.Errorf("redis: keys don't hash to the same slot") } state, err := c.state() if err != nil { return err } slot := hashtag.Slot(keys[0]) for _, key := range keys[1:] { if hashtag.Slot(key) != slot { return fmt.Errorf("redis: Watch requires all keys to be in the same slot") } } node, err := state.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 } moved, ask, addr := internal.IsMovedError(err) if moved || ask { c.lazyReloadState() node, err = c.nodes.GetOrCreate(addr) 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) Process(cmd Cmder) error { state, err := c.state() if err != nil { cmd.setErr(err) return err } _, node, err := c.cmdSlotAndNode(state, cmd) if err != nil { cmd.setErr(err) return err } var ask bool for attempt := 0; attempt <= c.opt.MaxRedirects; attempt++ { if attempt > 0 { time.Sleep(c.retryBackoff(attempt)) } 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) { // TODO: race node.loading = time.Now() continue } if internal.IsRetryableError(err, true) { var nodeErr error node, nodeErr = c.nodes.Random() if nodeErr != nil { break } continue } var moved bool var addr string moved, ask, addr = internal.IsMovedError(err) if moved || ask { c.lazyReloadState() var nodeErr error node, nodeErr = c.nodes.GetOrCreate(addr) if nodeErr != nil { break } 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() 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() 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() 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() 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) lazyReloadState() { if !atomic.CompareAndSwapUint32(&c.reloading, 0, 1) { return } go func() { defer atomic.StoreUint32(&c.reloading, 0) for { state, err := c.reloadState() if err == pool.ErrClosed { return } if err != nil { time.Sleep(time.Millisecond) continue } c._state.Store(state) time.Sleep(5 * time.Second) c.nodes.GC(state.generation) break } }() } // Not thread-safe. func (c *ClusterClient) reloadState() (*clusterState, error) { node, err := c.nodes.Random() if err != nil { return nil, err } slots, err := node.Client.ClusterSlots().Result() if err != nil { return nil, err } return newClusterState(c.nodes, slots, node.Client.opt.Addr) } // 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.pipelineExec, } pipe.setProcessor(pipe.Process) return &pipe } func (c *ClusterClient) Pipelined(fn func(Pipeliner) error) ([]Cmder, error) { return c.Pipeline().Pipelined(fn) } func (c *ClusterClient) pipelineExec(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 { 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() if err != nil { setCmdsErr(cmds, err) return nil, err } cmdsMap := make(map[*clusterNode][]Cmder) for _, cmd := range cmds { 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) pipelineProcessCmds( node *clusterNode, cn *pool.Conn, cmds []Cmder, failedCmds map[*clusterNode][]Cmder, ) error { cn.SetWriteTimeout(c.opt.WriteTimeout) if err := writeCmd(cn, cmds...); 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.lazyReloadState() 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.txPipelineExec, } pipe.setProcessor(pipe.Process) return &pipe } func (c *ClusterClient) TxPipelined(fn func(Pipeliner) error) ([]Cmder, error) { return c.TxPipeline().Pipelined(fn) } func (c *ClusterClient) txPipelineExec(cmds []Cmder) error { state, err := c.state() 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 { 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 { opt := c.opt.clientOptions() var node *clusterNode return &PubSub{ opt: opt, 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 } state, err := c.state() if err != nil { return nil, err } masterNode, err := state.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) }, } } // 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 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 appendNode(nodes []*clusterNode, node *clusterNode) []*clusterNode { for _, n := range nodes { if n == node { return nodes } } return append(nodes, node) }