fix: BAC-25 Race Condition: Websocket Promises (#99)

Reviewed-on: #99
Reviewed-by: lq64 <lq@blackhole.local>
Co-authored-by: Janis <janis.e.20@gmx.de>
Co-committed-by: Janis <janis.e.20@gmx.de>

knockoutwhistweb/app/model/sessions/UserSession.scala

@@ -26,6 +26,7 @@ class UserSession(val user: User, val host: Boolean, val gameLobby: GameLobby) e
         else canInteract = Some(InteractionType.Card)
       case _ =>
     }
+    websocketActor.foreach(_.solveRequests())
     websocketActor.foreach(_.transmitEventToClient(event))
   }
 
@@ -38,49 +39,41 @@ class UserSession(val user: User, val host: Boolean, val gameLobby: GameLobby) e
   }
 
   def handleWebResponse(eventType: String, data: JsObject): Unit = {
-    lock.lock()
-    val result = Try {
-      eventType match {
-        case "ping" =>
-          // No action needed for Ping
-          ()
-        case "StartGame" =>
-          gameLobby.startGame(user)
-        case "PlayCard" =>
-          val maybeCardIndex: Option[String] = (data \ "cardindex").asOpt[String]
-          maybeCardIndex match {
-            case Some(index) =>
-              val session = gameLobby.getUserSession(user.id)
-              gameLobby.playCard(session, index.toInt)
-            case None =>
-              println("Card Index not found or is not a number.")
-          }
-        case "PickTrumpsuit" =>
-          val maybeSuitIndex: Option[Int] = (data \ "suitIndex").asOpt[Int]
-          maybeSuitIndex match {
-            case Some(index) =>
-              val session = gameLobby.getUserSession(user.id)
-              gameLobby.selectTrump(session, index)
-            case None =>
-              println("Card Index not found or is not a number.")
-          }
-        case "KickPlayer" =>
-          val maybePlayerId: Option[String] = (data \ "playerId").asOpt[String]
-          maybePlayerId match {
-            case Some(id) =>
-              val playerUUID = UUID.fromString(id)
-              gameLobby.leaveGame(playerUUID, true)
-            case None =>
-              println("Player ID not found or is not a valid UUID.")
-          }
-        case "ReturnToLobby" =>
-          gameLobby.returnToLobby(this)
-      }
-    }
-    lock.unlock()
-    if (result.isFailure) {
-      val throwable = result.failed.get
-      throw throwable
+    eventType match {
+      case "ping" =>
+        // No action needed for Ping
+        ()
+      case "StartGame" =>
+        gameLobby.startGame(user)
+      case "PlayCard" =>
+        val maybeCardIndex: Option[String] = (data \ "cardindex").asOpt[String]
+        maybeCardIndex match {
+          case Some(index) =>
+            val session = gameLobby.getUserSession(user.id)
+            gameLobby.playCard(session, index.toInt)
+          case None =>
+            println("Card Index not found or is not a number.")
+        }
+      case "PickTrumpsuit" =>
+        val maybeSuitIndex: Option[Int] = (data \ "suitIndex").asOpt[Int]
+        maybeSuitIndex match {
+          case Some(index) =>
+            val session = gameLobby.getUserSession(user.id)
+            gameLobby.selectTrump(session, index)
+          case None =>
+            println("Card Index not found or is not a number.")
+        }
+      case "KickPlayer" =>
+        val maybePlayerId: Option[String] = (data \ "playerId").asOpt[String]
+        maybePlayerId match {
+          case Some(id) =>
+            val playerUUID = UUID.fromString(id)
+            gameLobby.leaveGame(playerUUID, true)
+          case None =>
+            println("Player ID not found or is not a valid UUID.")
+        }
+      case "ReturnToLobby" =>
+        gameLobby.returnToLobby(this)
     }
   }
 

knockoutwhistweb/app/model/sessions/UserWebsocketActor.scala

@@ -5,6 +5,7 @@ import org.apache.pekko.actor.{Actor, ActorRef}
 import play.api.libs.json.{JsObject, JsValue, Json}
 import util.WebsocketEventMapper
 
+import scala.collection.mutable
 import scala.util.{Failure, Success, Try}
 
 class UserWebsocketActor(
@@ -12,6 +13,8 @@ class UserWebsocketActor(
                           session: UserSession
                         ) extends Actor {
 
+  private val requests: mutable.Map[String, String] = mutable.Map()
+
   {
     session.lock.lock()
     if (session.websocketActor.isDefined) {
@@ -48,12 +51,14 @@ class UserWebsocketActor(
   }
 
   private def handle(json: JsValue): Unit = {
+    session.lock.lock()
     val idOpt = (json \ "id").asOpt[String]
     if (idOpt.isEmpty) {
       transmitJsonToClient(Json.obj(
         "status" -> "error",
         "error" -> "Missing 'id' field"
       ))
+      session.lock.unlock()
       return
     }
     val id = idOpt.get
@@ -65,17 +70,25 @@ class UserWebsocketActor(
         "status" -> "error",
         "error" -> "Missing 'event' field"
       ))
+      session.lock.unlock()
       return
     }
     val statusOpt = (json \ "status").asOpt[String]
     if (statusOpt.isDefined) {
+      session.lock.unlock()
       return
     }
     val event = eventOpt.get
     val data = (json \ "data").asOpt[JsObject].getOrElse(Json.obj())
+    requests += (id -> event)
     val result = Try {
       session.handleWebResponse(event, data)
     }
+    if (!requests.contains(id)) {
+      session.lock.unlock()
+      return
+    }
+    requests -= id
     if (result.isSuccess) {
       transmitJsonToClient(Json.obj(
         "id" -> id,
@@ -90,6 +103,7 @@ class UserWebsocketActor(
         "error" -> result.failed.get.getMessage
       ))
     }
+    session.lock.unlock()
   }
 
   def transmitJsonToClient(jsonObj: JsValue): Unit = {
@@ -100,4 +114,20 @@ class UserWebsocketActor(
     transmitJsonToClient(WebsocketEventMapper.toJson(event, session))
   }
 
+  def solveRequests(): Unit = {
+    if (!session.lock.isHeldByCurrentThread)
+      return;
+    if (requests.isEmpty)
+      return;
+    val pendingRequests = requests.toMap
+    requests.clear()
+    pendingRequests.foreach { case (id, event) =>
+      transmitJsonToClient(Json.obj(
+        "id" -> id,
+        "event" -> event,
+        "status" -> "success"
+      ))
+    }
+  }
+
 }