First changes to move away from central registry of all players

1. Introduce 'usher' that opens lobbies and fills it and waits for them
   to be filled
2. Add global registry of all games

chess/chess_move.go

@@ -1,4 +1,4 @@
-package server
+package chess
 
 type Move struct {
 	StartSquare Coordinate `json:"startSquare"`

chess/lobby.go

@@ -1,4 +1,4 @@
-package server
+package chess
 
 import (
 	"sync"

chess/match.go

@@ -1,4 +1,4 @@
-package server
+package chess
 
 import (
 	"log"

chess/player.go

@@ -1,4 +1,4 @@
-package server
+package chess
 
 import (
 	"context"
@@ -14,6 +14,8 @@ type Player struct {
 	InGame            bool
 	wsConnEstablished chan bool
 	context           context.Context
+
+	JoinedLobby chan bool
 }
 
 type PlayerInfo struct {
@@ -26,6 +28,7 @@ func NewPlayer(uuid uuid.UUID) *Player {
 		Conn:              nil,
 		InGame:            false,
 		wsConnEstablished: make(chan bool),
+		JoinedLobby:       make(chan bool),
 	}
 }
 

chess/server.go

@@ -1,4 +1,4 @@
-package server
+package chess
 
 import (
 	"net/http"

lobby_registry/lobby.go

@@ -0,0 +1,33 @@
+package lobby_registry
+
+import (
+	"local/m/mchess_server/chess"
+
+	"github.com/google/uuid"
+)
+
+type Lobby struct {
+	uuid    uuid.UUID
+	players []*chess.Player
+}
+
+func NewEmptyLobbyByUUID(uuid uuid.UUID) *Lobby {
+	return &Lobby{uuid: uuid}
+}
+
+func (w *Lobby) AddPlayer(player *chess.Player) {
+	w.players = append(w.players, player)
+	player.JoinedLobby <- true
+}
+
+func (w *Lobby) IsFull() bool {
+	return len(w.players) == 2
+}
+
+func (l *Lobby) GetPlayer1() *chess.Player {
+	return l.players[0]
+}
+
+func (l *Lobby) GetPlayer2() *chess.Player {
+	return l.players[1]
+}

lobby_registry/registry.go

@@ -0,0 +1,41 @@
+package lobby_registry
+
+import (
+	"github.com/google/uuid"
+)
+
+type LobbyRegistry struct {
+	lobbies map[uuid.UUID]*Lobby
+}
+
+var instance *LobbyRegistry
+
+func GetLobbyRegistry() *LobbyRegistry {
+	if instance == nil {
+		instance = newLobbyRegistry()
+	}
+
+	return instance
+}
+
+func newLobbyRegistry() *LobbyRegistry {
+	return &LobbyRegistry{lobbies: make(map[uuid.UUID]*Lobby)}
+}
+
+func (r *LobbyRegistry) GetLobbyForPlayer() *Lobby {
+	for _, lobby := range r.lobbies {
+		if !lobby.IsFull() {
+			return lobby
+		}
+	}
+
+	newLobby := NewEmptyLobbyByUUID(uuid.New())
+	r.addNewLobby(newLobby)
+	return newLobby
+}
+
+func (r *LobbyRegistry) addNewLobby(lobby *Lobby) uuid.UUID {
+	uuid := uuid.New()
+	r.lobbies[uuid] = lobby
+	return uuid
+}

main.go

@@ -2,7 +2,8 @@ package main
 
 import (
 	"context"
-	"local/m/mchess_server/server"
+	"local/m/mchess_server/chess"
+	"local/m/mchess_server/usher"
 	"log"
 	"net/http"
 	"os"
@@ -50,16 +51,21 @@ func registerForRandomGame(c *gin.Context) {
 		3. Only after a second player joins, respond with player id and game id.
 	*/
 
-	player := server.NewPlayer(uuid.New())
+	player := chess.NewPlayer(uuid.New())
 
-	lobby := server.GetLobby()
-	lobby.Lock()
-	server.GetLobby().RegisterPlayer(player)
-	lobby.Unlock()
+	usher := usher.GetUsher()
+	lobby := usher.WelcomeNewPlayer(player)
+	usher.AddPlayerToLobby(player, lobby)
+
+	// Counter point to this approach:
+	// Waiting for two players might not be necessary.
+	// Just open the lobby and respond with lobby/game id and player id
+	// The waiting can be done in the game handler until both players opened a ws connection
+	usher.WaitForTwoPlayersInLobby(lobby)
 
 	log.Println("responding with player id ", player.Uuid)
 
-	c.IndentedJSON(http.StatusOK, server.PlayerInfo{
+	c.IndentedJSON(http.StatusOK, chess.PlayerInfo{
 		PlayerID: player.Uuid,
 	})
 }
@@ -86,7 +92,10 @@ func waitForAndHandlePlayerID(ctx context.Context, conn websocket.Conn) {
 		return
 	}
 
-	lobby := server.GetLobby()
+	// since we cannot use the lobby anymore (it does not exist anymore after this change) the client needs to
+	// send game id and player id so we can make the connection to the player
+	//lobby := chess.GetLobby()
+
 	player, found := lobby.GetPlayer(uuid)
 	if !found {
 		conn.Close(websocket.StatusCode(400), "player not found")

usher/usher.go

@@ -0,0 +1,39 @@
+package usher
+
+import (
+	"local/m/mchess_server/chess"
+	lobbies "local/m/mchess_server/lobby_registry"
+)
+
+type Usher struct {
+}
+
+var instance *Usher
+
+func NewUsher() *Usher {
+	return &Usher{}
+}
+
+func GetUsher() *Usher {
+	if instance == nil {
+		instance = NewUsher()
+	}
+	return instance
+}
+
+func (u *Usher) WelcomeNewPlayer(player *chess.Player) *lobbies.Lobby {
+	lobby := lobbies.GetLobbyRegistry().GetLobbyForPlayer()
+	return lobby
+}
+
+func (u *Usher) AddPlayerToLobby(player *chess.Player, lobby *lobbies.Lobby) {
+	lobby.AddPlayer(player)
+}
+
+func (u *Usher) WaitForTwoPlayersInLobby(lobby *lobbies.Lobby) {
+	player1 := lobby.GetPlayer1()
+	<-player1.JoinedLobby
+
+	player2 := lobby.GetPlayer2()
+	<-player2.JoinedLobby
+}