func (e *RedisEngine) runPubSub() {
conn := redis.PubSubConn{Conn: e.pool.Get()}
defer conn.Close()
e.app.RLock()
adminChannel := e.app.config.AdminChannel
controlChannel := e.app.config.ControlChannel
e.app.RUnlock()
done := make(chan struct{})
defer close(done)
// Run subscriber routine
go func() {
logger.INFO.Println("Starting RedisEngine Subscriber")
defer func() {
logger.INFO.Println("Stopping RedisEngine Subscriber")
}()
for {
select {
case <-done:
return
case r := <-e.subCh:
// Something to subscribe
chIDs := []interface{}{r.Channel}
batch := []subRequest{r}
// Try to gather as many others as we can without waiting
fillBatchFromChan(e.subCh, &batch, &chIDs, RedisSubscribeBatchLimit)
// Send them all
err := conn.Subscribe(chIDs...)
if err != nil {
// Subscribe error is fatal
logger.ERROR.Printf("RedisEngine Subscriber error: %v\n", err)
for i := range batch {
batch[i].done(err)
}
// Close conn, this should cause Receive to return with err below
// and whole runPubSub method to restart
conn.Close()
return
}
for i := range batch {
batch[i].done(nil)
}
case r := <-e.unSubCh:
// Something to subscribe
chIDs := []interface{}{r.Channel}
batch := []subRequest{r}
// Try to gather as many others as we can without waiting
fillBatchFromChan(e.unSubCh, &batch, &chIDs, RedisSubscribeBatchLimit)
// Send them all
err := conn.Unsubscribe(chIDs...)
if err != nil {
// Subscribe error is fatal
logger.ERROR.Printf("RedisEngine Unsubscriber error: %v\n", err)
for i := range batch {
batch[i].done(err)
}
// Close conn, this should cause Receive to return with err below
// and whole runPubSub method to restart
conn.Close()
return
}
for i := range batch {
batch[i].done(nil)
}
}
}
}()
// Subscribe to channels we need in bulk.
// We don't care if they fail since conn will be closed and we'll retry
// if they do anyway.
// This saves a lot of allocating of pointless chans...
r := newSubRequest(adminChannel, false)
e.subCh <- r
r = newSubRequest(controlChannel, false)
e.subCh <- r
for _, chID := range e.app.clients.channels() {
r = newSubRequest(chID, false)
e.subCh <- r
}
for {
switch n := conn.Receive().(type) {
case redis.Message:
e.app.handleMsg(ChannelID(n.Channel), n.Data)
case redis.Subscription:
case error:
logger.ERROR.Printf("RedisEngine Receiver error: %v\n", n)
return
}
}
}
// Applications can receive pushed messages from one goroutine and manage subscriptions from another goroutine.
func ExamplePubSubConn() {
c, err := dial()
if err != nil {
panic(err)
}
defer c.Close()
var wg sync.WaitGroup
wg.Add(2)
psc := redis.PubSubConn{Conn: c}
// This goroutine receives and prints pushed notifications from the server.
// The goroutine exits when the connection is unsubscribed from all
// channels or there is an error.
go func() {
defer wg.Done()
for {
switch n := psc.Receive().(type) {
case redis.Message:
fmt.Printf("Message: %s %s\n", n.Channel, n.Data)
case redis.PMessage:
fmt.Printf("PMessage: %s %s %s\n", n.Pattern, n.Channel, n.Data)
case redis.Subscription:
fmt.Printf("Subscription: %s %s %d\n", n.Kind, n.Channel, n.Count)
if n.Count == 0 {
return
}
case error:
fmt.Printf("error: %v\n", n)
return
}
}
}()
// This goroutine manages subscriptions for the connection.
go func() {
defer wg.Done()
psc.Subscribe("example")
psc.PSubscribe("p*")
// The following function calls publish a message using another
// connection to the Redis server.
publish("example", "hello")
publish("example", "world")
publish("pexample", "foo")
publish("pexample", "bar")
// Unsubscribe from all connections. This will cause the receiving
// goroutine to exit.
psc.Unsubscribe()
psc.PUnsubscribe()
}()
wg.Wait()
// Output:
// Subscription: subscribe example 1
// Subscription: psubscribe p* 2
// Message: example hello
// Message: example world
// PMessage: p* pexample foo
// PMessage: p* pexample bar
// Subscription: unsubscribe example 1
// Subscription: punsubscribe p* 0
}