long poll routing first version

server/router.go

@@ -2,6 +2,7 @@ package server
 
 import (
 	"context"
+	"sync"
 	"time"
 
 	"forge.redroom.link/yves/meowlib"
@@ -56,7 +57,10 @@ func (r *RedisRouter) Route(msg *meowlib.ToServerMessage) (*meowlib.FromServerMe
 		if err != nil {
 			return nil, err
 		}
-
+		if msg.Timeout > 0 {
+			// set timeout for the lookup
+			r.subscribe(msg)
+		}
 	}
 	// manage Matriochka
 	if msg.MatriochkaMessage != nil {
@@ -165,6 +169,61 @@ func (r *RedisRouter) checkForMessage(msg *meowlib.ToServerMessage) (*meowlib.Fr
 	return &from_server, nil
 }
 
+func goSubscribeAndListen(client *redis.Client, key string, messages chan<- string, wg *sync.WaitGroup, done <-chan struct{}) {
+	defer wg.Done()
+	pubsub := client.Subscribe(key)
+	defer pubsub.Close()
+
+	// Create a new channel for the messages from this subscription
+	myMessages := make(chan *redis.Message)
+	go func() {
+		for {
+			msg, err := pubsub.ReceiveMessage()
+			if err != nil {
+				close(myMessages)
+				return
+			}
+			myMessages <- msg
+		}
+	}()
+
+	// Wait for a message or for the done signal
+	select {
+	case msg := <-myMessages:
+		messages <- msg.Payload
+	case <-done:
+		return
+	}
+}
+
+func (r *RedisRouter) subscribe(msg *meowlib.ToServerMessage) (*meowlib.FromServerMessage, error) {
+	var from_server meowlib.FromServerMessage
+	// update messages counter
+	err := r.Client.Incr("statistics:messages:messagessubscription").Err()
+	if err != nil {
+		return nil, err
+	}
+	messages := make(chan string)
+	var wg sync.WaitGroup
+	done := make(chan struct{})
+	// extract lookup keys and subscribe
+	for _, rq := range msg.PullRequest {
+		wg.Add(1)
+		// subscribe to the lookup key
+		go goSubscribeAndListen(r.Client, rq.LookupKey, messages, &wg, done)
+	}
+	// wait for timeout or message
+	select {
+	case <-messages:
+		close(done)
+		return r.checkForMessage(msg)
+	case <-time.After(10 * time.Second): // 10 seconds timeout
+		close(done)
+	}
+	wg.Wait()
+	return &from_server, nil
+}
+
 func (r *RedisRouter) handleInvitation(msg *meowlib.ToServerMessage) (*meowlib.FromServerMessage, error) {
 	var from_server meowlib.FromServerMessage
 	// update messages counter