596 lines
13 KiB
Go
596 lines
13 KiB
Go
package redis
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import (
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"context"
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"errors"
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"fmt"
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"strings"
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"sync"
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"time"
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"github.com/go-redis/redis/v7/internal"
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"github.com/go-redis/redis/v7/internal/pool"
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"github.com/go-redis/redis/v7/internal/proto"
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)
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const pingTimeout = 30 * time.Second
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var errPingTimeout = errors.New("redis: ping timeout")
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// PubSub implements Pub/Sub commands as described in
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// http://redis.io/topics/pubsub. Message receiving is NOT safe
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// for concurrent use by multiple goroutines.
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//
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// PubSub automatically reconnects to Redis Server and resubscribes
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// to the channels in case of network errors.
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type PubSub struct {
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opt *Options
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newConn func([]string) (*pool.Conn, error)
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closeConn func(*pool.Conn) error
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mu sync.Mutex
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cn *pool.Conn
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channels map[string]struct{}
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patterns map[string]struct{}
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closed bool
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exit chan struct{}
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cmd *Cmd
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chOnce sync.Once
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msgCh chan *Message
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allCh chan interface{}
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ping chan struct{}
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}
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func (c *PubSub) String() string {
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channels := mapKeys(c.channels)
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channels = append(channels, mapKeys(c.patterns)...)
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return fmt.Sprintf("PubSub(%s)", strings.Join(channels, ", "))
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}
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func (c *PubSub) init() {
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c.exit = make(chan struct{})
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}
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func (c *PubSub) connWithLock() (*pool.Conn, error) {
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c.mu.Lock()
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cn, err := c.conn(nil)
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c.mu.Unlock()
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return cn, err
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}
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func (c *PubSub) conn(newChannels []string) (*pool.Conn, error) {
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if c.closed {
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return nil, pool.ErrClosed
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}
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if c.cn != nil {
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return c.cn, nil
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}
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channels := mapKeys(c.channels)
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channels = append(channels, newChannels...)
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cn, err := c.newConn(channels)
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if err != nil {
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return nil, err
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}
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if err := c.resubscribe(cn); err != nil {
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_ = c.closeConn(cn)
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return nil, err
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}
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c.cn = cn
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return cn, nil
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}
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func (c *PubSub) writeCmd(ctx context.Context, cn *pool.Conn, cmd Cmder) error {
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return cn.WithWriter(ctx, c.opt.WriteTimeout, func(wr *proto.Writer) error {
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return writeCmd(wr, cmd)
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})
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}
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func (c *PubSub) resubscribe(cn *pool.Conn) error {
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var firstErr error
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if len(c.channels) > 0 {
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firstErr = c._subscribe(cn, "subscribe", mapKeys(c.channels))
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}
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if len(c.patterns) > 0 {
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err := c._subscribe(cn, "psubscribe", mapKeys(c.patterns))
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if err != nil && firstErr == nil {
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firstErr = err
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}
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}
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return firstErr
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}
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func mapKeys(m map[string]struct{}) []string {
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s := make([]string, len(m))
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i := 0
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for k := range m {
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s[i] = k
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i++
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}
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return s
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}
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func (c *PubSub) _subscribe(
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cn *pool.Conn, redisCmd string, channels []string,
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) error {
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args := make([]interface{}, 0, 1+len(channels))
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args = append(args, redisCmd)
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for _, channel := range channels {
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args = append(args, channel)
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}
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cmd := NewSliceCmd(args...)
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return c.writeCmd(context.TODO(), cn, cmd)
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}
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func (c *PubSub) releaseConnWithLock(cn *pool.Conn, err error, allowTimeout bool) {
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c.mu.Lock()
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c.releaseConn(cn, err, allowTimeout)
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c.mu.Unlock()
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}
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func (c *PubSub) releaseConn(cn *pool.Conn, err error, allowTimeout bool) {
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if c.cn != cn {
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return
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}
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if isBadConn(err, allowTimeout) {
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c.reconnect(err)
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}
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}
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func (c *PubSub) reconnect(reason error) {
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_ = c.closeTheCn(reason)
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_, _ = c.conn(nil)
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}
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func (c *PubSub) closeTheCn(reason error) error {
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if c.cn == nil {
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return nil
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}
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if !c.closed {
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internal.Logger.Printf("redis: discarding bad PubSub connection: %s", reason)
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}
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err := c.closeConn(c.cn)
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c.cn = nil
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return err
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}
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func (c *PubSub) Close() error {
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c.mu.Lock()
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defer c.mu.Unlock()
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if c.closed {
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return pool.ErrClosed
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}
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c.closed = true
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close(c.exit)
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return c.closeTheCn(pool.ErrClosed)
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}
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// Subscribe the client to the specified channels. It returns
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// empty subscription if there are no channels.
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func (c *PubSub) Subscribe(channels ...string) error {
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c.mu.Lock()
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defer c.mu.Unlock()
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err := c.subscribe("subscribe", channels...)
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if c.channels == nil {
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c.channels = make(map[string]struct{})
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}
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for _, s := range channels {
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c.channels[s] = struct{}{}
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}
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return err
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}
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// PSubscribe the client to the given patterns. It returns
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// empty subscription if there are no patterns.
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func (c *PubSub) PSubscribe(patterns ...string) error {
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c.mu.Lock()
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defer c.mu.Unlock()
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err := c.subscribe("psubscribe", patterns...)
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if c.patterns == nil {
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c.patterns = make(map[string]struct{})
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}
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for _, s := range patterns {
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c.patterns[s] = struct{}{}
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}
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return err
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}
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// Unsubscribe the client from the given channels, or from all of
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// them if none is given.
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func (c *PubSub) Unsubscribe(channels ...string) error {
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c.mu.Lock()
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defer c.mu.Unlock()
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for _, channel := range channels {
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delete(c.channels, channel)
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}
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err := c.subscribe("unsubscribe", channels...)
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return err
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}
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// PUnsubscribe the client from the given patterns, or from all of
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// them if none is given.
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func (c *PubSub) PUnsubscribe(patterns ...string) error {
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c.mu.Lock()
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defer c.mu.Unlock()
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for _, pattern := range patterns {
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delete(c.patterns, pattern)
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}
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err := c.subscribe("punsubscribe", patterns...)
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return err
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}
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func (c *PubSub) subscribe(redisCmd string, channels ...string) error {
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cn, err := c.conn(channels)
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if err != nil {
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return err
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}
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err = c._subscribe(cn, redisCmd, channels)
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c.releaseConn(cn, err, false)
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return err
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}
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func (c *PubSub) Ping(payload ...string) error {
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args := []interface{}{"ping"}
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if len(payload) == 1 {
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args = append(args, payload[0])
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}
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cmd := NewCmd(args...)
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cn, err := c.connWithLock()
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if err != nil {
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return err
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}
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err = c.writeCmd(context.TODO(), cn, cmd)
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c.releaseConnWithLock(cn, err, false)
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return err
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}
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// Subscription received after a successful subscription to channel.
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type Subscription struct {
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// Can be "subscribe", "unsubscribe", "psubscribe" or "punsubscribe".
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Kind string
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// Channel name we have subscribed to.
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Channel string
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// Number of channels we are currently subscribed to.
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Count int
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}
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func (m *Subscription) String() string {
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return fmt.Sprintf("%s: %s", m.Kind, m.Channel)
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}
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// Message received as result of a PUBLISH command issued by another client.
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type Message struct {
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Channel string
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Pattern string
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Payload string
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}
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func (m *Message) String() string {
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return fmt.Sprintf("Message<%s: %s>", m.Channel, m.Payload)
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}
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// Pong received as result of a PING command issued by another client.
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type Pong struct {
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Payload string
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}
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func (p *Pong) String() string {
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if p.Payload != "" {
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return fmt.Sprintf("Pong<%s>", p.Payload)
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}
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return "Pong"
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}
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func (c *PubSub) newMessage(reply interface{}) (interface{}, error) {
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switch reply := reply.(type) {
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case string:
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return &Pong{
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Payload: reply,
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}, nil
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case []interface{}:
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switch kind := reply[0].(string); kind {
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case "subscribe", "unsubscribe", "psubscribe", "punsubscribe":
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// Can be nil in case of "unsubscribe".
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channel, _ := reply[1].(string)
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return &Subscription{
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Kind: kind,
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Channel: channel,
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Count: int(reply[2].(int64)),
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}, nil
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case "message":
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return &Message{
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Channel: reply[1].(string),
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Payload: reply[2].(string),
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}, nil
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case "pmessage":
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return &Message{
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Pattern: reply[1].(string),
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Channel: reply[2].(string),
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Payload: reply[3].(string),
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}, nil
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case "pong":
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return &Pong{
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Payload: reply[1].(string),
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}, nil
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default:
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return nil, fmt.Errorf("redis: unsupported pubsub message: %q", kind)
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}
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default:
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return nil, fmt.Errorf("redis: unsupported pubsub message: %#v", reply)
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}
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}
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// ReceiveTimeout acts like Receive but returns an error if message
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// is not received in time. This is low-level API and in most cases
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// Channel should be used instead.
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func (c *PubSub) ReceiveTimeout(timeout time.Duration) (interface{}, error) {
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if c.cmd == nil {
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c.cmd = NewCmd()
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}
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cn, err := c.connWithLock()
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if err != nil {
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return nil, err
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}
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err = cn.WithReader(context.TODO(), timeout, func(rd *proto.Reader) error {
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return c.cmd.readReply(rd)
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})
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c.releaseConnWithLock(cn, err, timeout > 0)
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if err != nil {
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return nil, err
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}
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return c.newMessage(c.cmd.Val())
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}
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// Receive returns a message as a Subscription, Message, Pong or error.
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// See PubSub example for details. This is low-level API and in most cases
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// Channel should be used instead.
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func (c *PubSub) Receive() (interface{}, error) {
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return c.ReceiveTimeout(0)
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}
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// ReceiveMessage returns a Message or error ignoring Subscription and Pong
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// messages. This is low-level API and in most cases Channel should be used
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// instead.
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func (c *PubSub) ReceiveMessage() (*Message, error) {
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for {
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msg, err := c.Receive()
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if err != nil {
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return nil, err
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}
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switch msg := msg.(type) {
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case *Subscription:
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// Ignore.
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case *Pong:
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// Ignore.
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case *Message:
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return msg, nil
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default:
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err := fmt.Errorf("redis: unknown message: %T", msg)
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return nil, err
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}
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}
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}
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// Channel returns a Go channel for concurrently receiving messages.
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// The channel is closed together with the PubSub. If the Go channel
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// is blocked full for 30 seconds the message is dropped.
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// Receive* APIs can not be used after channel is created.
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//
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// go-redis periodically sends ping messages to test connection health
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// and re-subscribes if ping can not not received for 30 seconds.
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func (c *PubSub) Channel() <-chan *Message {
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return c.ChannelSize(100)
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}
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// ChannelSize is like Channel, but creates a Go channel
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// with specified buffer size.
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func (c *PubSub) ChannelSize(size int) <-chan *Message {
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c.chOnce.Do(func() {
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c.initPing()
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c.initMsgChan(size)
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})
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if c.msgCh == nil {
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err := fmt.Errorf("redis: Channel can't be called after ChannelWithSubscriptions")
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panic(err)
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}
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if cap(c.msgCh) != size {
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err := fmt.Errorf("redis: PubSub.Channel size can not be changed once created")
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panic(err)
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}
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return c.msgCh
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}
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// ChannelWithSubscriptions is like Channel, but message type can be either
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// *Subscription or *Message. Subscription messages can be used to detect
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// reconnections.
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//
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// ChannelWithSubscriptions can not be used together with Channel or ChannelSize.
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func (c *PubSub) ChannelWithSubscriptions(size int) <-chan interface{} {
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c.chOnce.Do(func() {
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c.initPing()
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c.initAllChan(size)
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})
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if c.allCh == nil {
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err := fmt.Errorf("redis: ChannelWithSubscriptions can't be called after Channel")
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panic(err)
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}
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if cap(c.allCh) != size {
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err := fmt.Errorf("redis: PubSub.Channel size can not be changed once created")
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panic(err)
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}
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return c.allCh
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}
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func (c *PubSub) initPing() {
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c.ping = make(chan struct{}, 1)
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go func() {
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timer := time.NewTimer(pingTimeout)
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timer.Stop()
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healthy := true
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for {
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timer.Reset(pingTimeout)
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select {
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case <-c.ping:
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healthy = true
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if !timer.Stop() {
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<-timer.C
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}
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case <-timer.C:
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pingErr := c.Ping()
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if healthy {
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healthy = false
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} else {
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if pingErr == nil {
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pingErr = errPingTimeout
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}
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c.mu.Lock()
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c.reconnect(pingErr)
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healthy = true
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c.mu.Unlock()
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}
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case <-c.exit:
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return
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}
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}
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}()
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}
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// initMsgChan must be in sync with initAllChan.
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func (c *PubSub) initMsgChan(size int) {
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c.msgCh = make(chan *Message, size)
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go func() {
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timer := time.NewTimer(pingTimeout)
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timer.Stop()
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var errCount int
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for {
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msg, err := c.Receive()
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if err != nil {
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if err == pool.ErrClosed {
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close(c.msgCh)
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return
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}
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if errCount > 0 {
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time.Sleep(c.retryBackoff(errCount))
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}
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errCount++
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continue
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}
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errCount = 0
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// Any message is as good as a ping.
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select {
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case c.ping <- struct{}{}:
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default:
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}
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switch msg := msg.(type) {
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case *Subscription:
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// Ignore.
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case *Pong:
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// Ignore.
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case *Message:
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timer.Reset(pingTimeout)
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select {
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case c.msgCh <- msg:
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if !timer.Stop() {
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<-timer.C
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}
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case <-timer.C:
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internal.Logger.Printf(
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"redis: %s channel is full for %s (message is dropped)", c, pingTimeout)
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}
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default:
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internal.Logger.Printf("redis: unknown message type: %T", msg)
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}
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}
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}()
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}
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// initAllChan must be in sync with initMsgChan.
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func (c *PubSub) initAllChan(size int) {
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c.allCh = make(chan interface{}, size)
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go func() {
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timer := time.NewTimer(pingTimeout)
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timer.Stop()
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var errCount int
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for {
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msg, err := c.Receive()
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if err != nil {
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if err == pool.ErrClosed {
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close(c.allCh)
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return
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}
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if errCount > 0 {
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time.Sleep(c.retryBackoff(errCount))
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}
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errCount++
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continue
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}
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errCount = 0
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// Any message is as good as a ping.
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select {
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case c.ping <- struct{}{}:
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default:
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}
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switch msg := msg.(type) {
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case *Subscription:
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c.sendMessage(msg, timer)
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case *Pong:
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// Ignore.
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case *Message:
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c.sendMessage(msg, timer)
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default:
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internal.Logger.Printf("redis: unknown message type: %T", msg)
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}
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}
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}()
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}
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func (c *PubSub) sendMessage(msg interface{}, timer *time.Timer) {
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timer.Reset(pingTimeout)
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select {
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case c.allCh <- msg:
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if !timer.Stop() {
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<-timer.C
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}
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case <-timer.C:
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internal.Logger.Printf(
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"redis: %s channel is full for %s (message is dropped)", c, pingTimeout)
|
|
}
|
|
}
|
|
|
|
func (c *PubSub) retryBackoff(attempt int) time.Duration {
|
|
return internal.RetryBackoff(attempt, c.opt.MinRetryBackoff, c.opt.MaxRetryBackoff)
|
|
}
|