feat: stream room updates SSE endpoint

via subscription to redis with enriched channel

rooms/room.go

@@ -35,10 +35,11 @@ func (r *Room)InitMaps() {
 // if you are speaking - change nothing
 // if nobody is speaking, set this person as a first speaker
 func (r *Room) RaiseHand(p PersonId, gesture HandGesture) Room {
-	if (r.CurrentSpeaker == p) {
-		// if person already speaking, should first end speaking
-		return *r
-	}
+	// TODO This is temporary
+	// if (r.CurrentSpeaker == p) {
+	// 	// if person already speaking, should first end speaking
+	// 	return *r
+	// }
 	r.ParticipantHands[p] = gesture
 	if r.CurrentSpeaker == PersonId(0) {
 		r.CurrentSpeaker = p

rooms/rooms_manager.go

@@ -5,8 +5,8 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"math/rand"
 	"log"
+	"math/rand"
 
 	"github.com/redis/go-redis/v9"
 )
@@ -15,26 +15,25 @@ type PersonId int
 
 func (p PersonId) MarshalBinary() ([]byte, error) {
 	bytes, err := json.Marshal(p)
-    return bytes, err
+	return bytes, err
 }
 
 func (p *PersonId) UnmarshalBinary(data []byte) error {
 	err := json.Unmarshal(data, p)
-    return err
+	return err
 }
 
 // TODO move to rooms i guess
 func RandomPersonId() PersonId {
 	randInt := rand.Int()
 	if randInt == 0 {
-		 randInt = 1
+		randInt = 1
 	}
 	return PersonId(randInt)
 }
 
-
 type Person struct {
-	Id     		 PersonId
+	Id           PersonId
 	Name         string
 	PasswordHash string
 }
@@ -48,20 +47,21 @@ func (r *Room) UnmarshalBinary(data []byte) error {
 	return json.Unmarshal(data, r)
 }
 
-
 // let's check whether it will be possible to save nested structs
 
 type RoomManager interface {
 	Get(roomName string) (Room, bool, error)
 	Save(room Room) error
 	Update(ctx context.Context, roomName string, f func(fromRoom Room) (toRoom Room)) error
+	Subscribe(ctx context.Context, roomName string) <-chan Room
 }
+
 const roomRedisPrefix = "room"
+
 func roomNameToRedisId(roomName string) string {
 	return fmt.Sprintf("%s:%s", roomRedisPrefix, roomName)
 }
 
-
 type RedisRM struct {
 	Rdb *redis.Client
 }
@@ -80,11 +80,70 @@ func (redisRM RedisRM) Get(roomName string) (Room, bool, error) {
 	return readRoom, true, nil
 }
 
+func (redisRM RedisRM) Subscribe(ctx context.Context, roomName string) <-chan Room {
+	// pubsub := redisRM.Rdb.Subscribe(ctx, roomNameToRedisId(roomName))
+	key := fmt.Sprintf( "__keyspace@0__:room:%s", roomName)
+	log.Printf("><> about to subscribe to %s\n", key)
+	pubsub := redisRM.Rdb.Subscribe(ctx, key)
+
+	redisMsgChan := pubsub.Channel()
+
+	roomChannel := make(chan Room)
+
+	go func() {
+		defer log.Printf(">>> stopping redis subscription to %s\n", roomName)
+		defer pubsub.Close() // this was my problem, cooool
+
+		var initialRoom Room
+		err := redisRM.Rdb.Get(ctx, roomNameToRedisId(roomName)).Scan(&initialRoom)
+		if err != nil {
+			log.Printf("in stream for %s got initial error %s/n", roomName, err)
+			close(roomChannel)
+			return
+		}
+		roomChannel <- initialRoom
+
+		for {
+			select {
+			case msg := <-redisMsgChan:
+				log.Printf("> subscribe got message %v\n", msg)
+
+				if msg == nil {
+					log.Print("> subscribe got nil redis message for some reason")
+					return
+				}
+				log.Printf(">>> chan: %s, patt: %s, payload: %s, payloadSlice: %v\n", msg.Channel, msg.Pattern, msg.Payload, msg.PayloadSlice)
+				if msg.Payload == "del" {
+					// room has been deleted, can stop the stream
+					close(roomChannel)
+					return
+				}
+				// for any other event - read the room state and put into room channel
+				var room Room
+				err := redisRM.Rdb.Get(ctx, roomNameToRedisId(roomName)).Scan(&room)
+				if err != nil {
+					log.Printf("in stream for %s got error %s/n", roomName, err)
+					close(roomChannel)
+				}
+				roomChannel <- room
+			case <-ctx.Done():
+				log.Println("got Done in subscribe")
+				close(roomChannel)
+				return
+			}
+
+		}
+	}()
+
+	return roomChannel
+}
+
 var maxRetries int = 20
+
 func (redisRM RedisRM) Update(ctx context.Context, roomName string, f func(fromRoom Room) (toRoom Room)) error {
 	// transactional function
 	roomKey := roomNameToRedisId(roomName)
-	txf := func (tx *redis.Tx) error {
+	txf := func(tx *redis.Tx) error {
 		var savedRoom Room
 		err := tx.Get(ctx, roomKey).Scan(&savedRoom)
 		if err != nil {
@@ -95,6 +154,7 @@ func (redisRM RedisRM) Update(ctx context.Context, roomName string, f func(fromR
 		room := f(savedRoom)
 
 		_, err = tx.Pipelined(ctx, func(pipe redis.Pipeliner) error {
+			log.Printf(">> about to Set %s to %v", roomName, room)
 			pipe.Set(ctx, roomKey, &room, 0)
 			return nil
 		})