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pubsub.go
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pubsub.go
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package redis
import (
"fmt"
"log"
"net"
"time"
)
// Posts a message to the given channel.
func (c *Client) Publish(channel, message string) *IntCmd {
req := NewIntCmd("PUBLISH", channel, message)
c.Process(req)
return req
}
// PubSub implements Pub/Sub commands as described in
// http://redis.io/topics/pubsub. It's NOT safe for concurrent use by
// multiple goroutines.
type PubSub struct {
*baseClient
channels []string
patterns []string
}
// Deprecated. Use Subscribe/PSubscribe instead.
func (c *Client) PubSub() *PubSub {
return &PubSub{
baseClient: &baseClient{
opt: c.opt,
connPool: newStickyConnPool(c.connPool, false),
},
}
}
// Subscribes the client to the specified channels.
func (c *Client) Subscribe(channels ...string) (*PubSub, error) {
pubsub := c.PubSub()
return pubsub, pubsub.Subscribe(channels...)
}
// Subscribes the client to the given patterns.
func (c *Client) PSubscribe(channels ...string) (*PubSub, error) {
pubsub := c.PubSub()
return pubsub, pubsub.PSubscribe(channels...)
}
func (c *PubSub) subscribe(cmd string, channels ...string) error {
cn, _, err := c.conn()
if err != nil {
return err
}
args := make([]interface{}, 1+len(channels))
args[0] = cmd
for i, channel := range channels {
args[1+i] = channel
}
req := NewSliceCmd(args...)
return cn.writeCmds(req)
}
// Subscribes the client to the specified channels.
func (c *PubSub) Subscribe(channels ...string) error {
err := c.subscribe("SUBSCRIBE", channels...)
if err == nil {
c.channels = append(c.channels, channels...)
}
return err
}
// Subscribes the client to the given patterns.
func (c *PubSub) PSubscribe(patterns ...string) error {
err := c.subscribe("PSUBSCRIBE", patterns...)
if err == nil {
c.channels = append(c.channels, patterns...)
}
return err
}
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
}
// Unsubscribes the client from the given channels, or from all of
// them if none is given.
func (c *PubSub) Unsubscribe(channels ...string) error {
err := c.subscribe("UNSUBSCRIBE", channels...)
if err == nil {
c.channels = remove(c.channels, channels...)
}
return err
}
// Unsubscribes the client from the given patterns, or from all of
// them if none is given.
func (c *PubSub) PUnsubscribe(patterns ...string) error {
err := c.subscribe("PUNSUBSCRIBE", patterns...)
if err == nil {
c.patterns = remove(c.patterns, patterns...)
}
return err
}
func (c *PubSub) Ping(payload string) error {
cn, _, err := c.conn()
if err != nil {
return err
}
args := []interface{}{"PING"}
if payload != "" {
args = append(args, payload)
}
cmd := NewCmd(args...)
return cn.writeCmds(cmd)
}
// Message received after a successful subscription to channel.
type Subscription struct {
// Can be "subscribe", "unsubscribe", "psubscribe" or "punsubscribe".
Kind string
// Channel name we have subscribed to.
Channel string
// Number of channels we are currently subscribed to.
Count int
}
func (m *Subscription) String() string {
return fmt.Sprintf("%s: %s", m.Kind, m.Channel)
}
// Message received as result of a PUBLISH command issued by another client.
type Message struct {
Channel string
Pattern string
Payload string
}
func (m *Message) String() string {
return fmt.Sprintf("Message<%s: %s>", m.Channel, m.Payload)
}
// TODO: remove PMessage if favor of Message
// Message matching a pattern-matching subscription received as result
// of a PUBLISH command issued by another client.
type PMessage struct {
Channel string
Pattern string
Payload string
}
func (m *PMessage) String() string {
return fmt.Sprintf("PMessage<%s: %s>", m.Channel, m.Payload)
}
// Pong received as result of a PING command issued by another client.
type Pong struct {
Payload string
}
func (p *Pong) String() string {
if p.Payload != "" {
return fmt.Sprintf("Pong<%s>", p.Payload)
}
return "Pong"
}
func newMessage(reply []interface{}) (interface{}, error) {
switch kind := reply[0].(string); kind {
case "subscribe", "unsubscribe", "psubscribe", "punsubscribe":
return &Subscription{
Kind: kind,
Channel: reply[1].(string),
Count: int(reply[2].(int64)),
}, nil
case "message":
return &Message{
Channel: reply[1].(string),
Payload: reply[2].(string),
}, nil
case "pmessage":
return &PMessage{
Pattern: reply[1].(string),
Channel: reply[2].(string),
Payload: reply[3].(string),
}, nil
case "pong":
return &Pong{
Payload: reply[1].(string),
}, nil
default:
return nil, fmt.Errorf("redis: unsupported pubsub notification: %q", kind)
}
}
// ReceiveTimeout acts like Receive but returns an error if message
// is not received in time. This is low-level API and most clients
// should use ReceiveMessage.
func (c *PubSub) ReceiveTimeout(timeout time.Duration) (interface{}, error) {
cn, _, err := c.conn()
if err != nil {
return nil, err
}
cn.ReadTimeout = timeout
cmd := NewSliceCmd()
err = cmd.readReply(cn)
c.putConn(cn, err)
if err != nil {
return nil, err
}
return newMessage(cmd.Val())
}
// Receive returns a message as a Subscription, Message, PMessage,
// Pong or error. See PubSub example for details. This is low-level
// API and most clients should use ReceiveMessage.
func (c *PubSub) Receive() (interface{}, error) {
return c.ReceiveTimeout(0)
}
func (c *PubSub) reconnect() {
// Close current connection.
c.connPool.Remove(nil) // nil to force removal
if len(c.channels) > 0 {
if err := c.Subscribe(c.channels...); err != nil {
log.Printf("redis: Subscribe failed: %s", err)
}
}
if len(c.patterns) > 0 {
if err := c.PSubscribe(c.patterns...); err != nil {
log.Printf("redis: Subscribe failed: %s", err)
}
}
}
// ReceiveMessage returns a message or error. It automatically
// reconnects to Redis in case of network errors.
func (c *PubSub) ReceiveMessage() (*Message, error) {
var badConn bool
for {
msgi, err := c.ReceiveTimeout(5 * time.Second)
if err != nil {
if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
if badConn {
c.reconnect()
badConn = false
continue
}
err := c.Ping("")
if err != nil {
c.reconnect()
} else {
badConn = true
}
continue
}
if isNetworkError(err) {
c.reconnect()
continue
}
return nil, err
}
switch msg := msgi.(type) {
case *Subscription:
// Ignore.
case *Pong:
badConn = false
// Ignore.
case *Message:
return msg, nil
case *PMessage:
return &Message{
Channel: msg.Channel,
Pattern: msg.Pattern,
Payload: msg.Payload,
}, nil
default:
return nil, fmt.Errorf("redis: unknown message: %T", msgi)
}
}
}