forked from mirror/redis
305 lines
6.8 KiB
Go
305 lines
6.8 KiB
Go
package redis
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import (
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"errors"
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"log"
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"net"
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"strings"
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"sync"
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"time"
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)
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//------------------------------------------------------------------------------
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// FailoverOptions are used to configure a failover client and should
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// be passed to NewFailoverClient.
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type FailoverOptions struct {
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// The master name.
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MasterName string
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// A seed list of host:port addresses of sentinel nodes.
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SentinelAddrs []string
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// Following options are copied from Options struct.
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Password string
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DB int64
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DialTimeout time.Duration
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ReadTimeout time.Duration
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WriteTimeout time.Duration
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PoolSize int
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PoolTimeout time.Duration
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IdleTimeout time.Duration
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MaxRetries int
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}
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func (opt *FailoverOptions) options() *Options {
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return &Options{
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Addr: "FailoverClient",
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DB: opt.DB,
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Password: opt.Password,
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DialTimeout: opt.DialTimeout,
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ReadTimeout: opt.ReadTimeout,
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WriteTimeout: opt.WriteTimeout,
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PoolSize: opt.PoolSize,
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PoolTimeout: opt.PoolTimeout,
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IdleTimeout: opt.IdleTimeout,
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MaxRetries: opt.MaxRetries,
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}
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}
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// NewFailoverClient returns a Redis client with automatic failover
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// capabilities using Redis Sentinel.
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func NewFailoverClient(failoverOpt *FailoverOptions) *Client {
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opt := failoverOpt.options()
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failover := &sentinelFailover{
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masterName: failoverOpt.MasterName,
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sentinelAddrs: failoverOpt.SentinelAddrs,
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opt: opt,
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}
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return newClient(opt, failover.Pool())
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}
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//------------------------------------------------------------------------------
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type sentinelClient struct {
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commandable
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*baseClient
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}
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func newSentinel(opt *Options) *sentinelClient {
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base := &baseClient{
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opt: opt,
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connPool: newConnPool(opt),
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}
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return &sentinelClient{
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baseClient: base,
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commandable: commandable{process: base.process},
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}
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}
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func (c *sentinelClient) PubSub() *PubSub {
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return &PubSub{
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baseClient: &baseClient{
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opt: c.opt,
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connPool: newSingleConnPool(c.connPool, false),
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},
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}
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}
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func (c *sentinelClient) GetMasterAddrByName(name string) *StringSliceCmd {
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cmd := NewStringSliceCmd("SENTINEL", "get-master-addr-by-name", name)
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c.Process(cmd)
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return cmd
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}
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func (c *sentinelClient) Sentinels(name string) *SliceCmd {
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cmd := NewSliceCmd("SENTINEL", "sentinels", name)
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c.Process(cmd)
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return cmd
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}
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type sentinelFailover struct {
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masterName string
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sentinelAddrs []string
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opt *Options
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pool pool
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poolOnce sync.Once
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lock sync.RWMutex
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_sentinel *sentinelClient
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}
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func (d *sentinelFailover) dial() (net.Conn, error) {
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addr, err := d.MasterAddr()
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if err != nil {
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return nil, err
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}
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return net.DialTimeout("tcp", addr, d.opt.DialTimeout)
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}
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func (d *sentinelFailover) Pool() pool {
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d.poolOnce.Do(func() {
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d.opt.Dialer = d.dial
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d.pool = newConnPool(d.opt)
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})
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return d.pool
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}
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func (d *sentinelFailover) MasterAddr() (string, error) {
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defer d.lock.Unlock()
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d.lock.Lock()
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// Try last working sentinel.
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if d._sentinel != nil {
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addr, err := d._sentinel.GetMasterAddrByName(d.masterName).Result()
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if err != nil {
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log.Printf("redis-sentinel: GetMasterAddrByName %q failed: %s", d.masterName, err)
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d.resetSentinel()
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} else {
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addr := net.JoinHostPort(addr[0], addr[1])
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log.Printf("redis-sentinel: %q addr is %s", d.masterName, addr)
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return addr, nil
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}
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}
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for i, sentinelAddr := range d.sentinelAddrs {
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sentinel := newSentinel(&Options{
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Addr: sentinelAddr,
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DialTimeout: d.opt.DialTimeout,
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ReadTimeout: d.opt.ReadTimeout,
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WriteTimeout: d.opt.WriteTimeout,
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PoolSize: d.opt.PoolSize,
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PoolTimeout: d.opt.PoolTimeout,
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IdleTimeout: d.opt.IdleTimeout,
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})
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masterAddr, err := sentinel.GetMasterAddrByName(d.masterName).Result()
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if err != nil {
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log.Printf("redis-sentinel: GetMasterAddrByName %q failed: %s", d.masterName, err)
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sentinel.Close()
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continue
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}
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// Push working sentinel to the top.
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d.sentinelAddrs[0], d.sentinelAddrs[i] = d.sentinelAddrs[i], d.sentinelAddrs[0]
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d.setSentinel(sentinel)
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addr := net.JoinHostPort(masterAddr[0], masterAddr[1])
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log.Printf("redis-sentinel: %q addr is %s", d.masterName, addr)
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return addr, nil
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}
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return "", errors.New("redis: all sentinels are unreachable")
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}
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func (d *sentinelFailover) setSentinel(sentinel *sentinelClient) {
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d.discoverSentinels(sentinel)
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d._sentinel = sentinel
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go d.listen()
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}
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func (d *sentinelFailover) discoverSentinels(sentinel *sentinelClient) {
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sentinels, err := sentinel.Sentinels(d.masterName).Result()
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if err != nil {
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log.Printf("redis-sentinel: Sentinels %q failed: %s", d.masterName, err)
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return
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}
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for _, sentinel := range sentinels {
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vals := sentinel.([]interface{})
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for i := 0; i < len(vals); i += 2 {
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key := vals[i].(string)
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if key == "name" {
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sentinelAddr := vals[i+1].(string)
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if !contains(d.sentinelAddrs, sentinelAddr) {
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log.Printf(
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"redis-sentinel: discovered new %q sentinel: %s",
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d.masterName, sentinelAddr,
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)
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d.sentinelAddrs = append(d.sentinelAddrs, sentinelAddr)
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}
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}
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}
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}
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}
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// closeOldConns closes connections to the old master after failover switch.
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func (d *sentinelFailover) closeOldConns(newMaster string) {
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// Good connections that should be put back to the pool. They
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// can't be put immediately, because pool.First will return them
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// again on next iteration.
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cnsToPut := make([]*conn, 0)
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for {
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cn := d.pool.First()
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if cn == nil {
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break
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}
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if cn.RemoteAddr().String() != newMaster {
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log.Printf(
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"redis-sentinel: closing connection to the old master %s",
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cn.RemoteAddr(),
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)
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d.pool.Remove(cn)
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} else {
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cnsToPut = append(cnsToPut, cn)
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}
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}
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for _, cn := range cnsToPut {
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d.pool.Put(cn)
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}
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}
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func (d *sentinelFailover) listen() {
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var pubsub *PubSub
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for {
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if pubsub == nil {
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pubsub = d._sentinel.PubSub()
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if err := pubsub.Subscribe("+switch-master"); err != nil {
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log.Printf("redis-sentinel: Subscribe failed: %s", err)
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d.lock.Lock()
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d.resetSentinel()
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d.lock.Unlock()
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return
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}
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}
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msgIface, err := pubsub.Receive()
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if err != nil {
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log.Printf("redis-sentinel: Receive failed: %s", err)
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pubsub.Close()
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return
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}
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switch msg := msgIface.(type) {
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case *Message:
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switch msg.Channel {
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case "+switch-master":
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parts := strings.Split(msg.Payload, " ")
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if parts[0] != d.masterName {
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log.Printf("redis-sentinel: ignore new %s addr", parts[0])
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continue
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}
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addr := net.JoinHostPort(parts[3], parts[4])
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log.Printf(
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"redis-sentinel: new %q addr is %s",
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d.masterName, addr,
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)
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d.closeOldConns(addr)
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default:
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log.Printf("redis-sentinel: unsupported message: %s", msg)
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}
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case *Subscription:
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// Ignore.
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default:
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log.Printf("redis-sentinel: unsupported message: %s", msgIface)
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}
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}
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}
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func (d *sentinelFailover) resetSentinel() {
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d._sentinel.Close()
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d._sentinel = nil
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}
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func contains(slice []string, str string) bool {
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for _, s := range slice {
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if s == str {
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return true
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}
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}
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return false
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}
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