Merge pull request #24438 from peppy/multi-spectator-flow-fixes

Fix issues switching to new beatmap in multiplayer spectator

osu.Game.Tests/Visual/Multiplayer/TestSceneMultiSpectatorScreen.cs

@@ -79,6 +79,20 @@ namespace osu.Game.Tests.Visual.Multiplayer
             AddWaitStep("wait a bit", 20);
         }
 
+        [Test]
+        public void TestMultipleStartRequests()
+        {
+            int[] userIds = getPlayerIds(2);
+
+            start(userIds);
+            loadSpectateScreen();
+
+            sendFrames(userIds, 1000);
+            AddWaitStep("wait a bit", 20);
+
+            start(userIds);
+        }
+
         [Test]
         public void TestDelayedStart()
         {

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerMatchSubScreen.cs

@@ -371,9 +371,6 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
 
         private void onLoadRequested()
         {
-            if (BeatmapAvailability.Value.State != DownloadState.LocallyAvailable)
-                return;
-
             // In the case of spectating, IMultiplayerClient.LoadRequested can be fired while the game is still spectating a previous session.
             // For now, we want to game to switch to the new game so need to request exiting from the play screen.
             if (!ParentScreen.IsCurrentScreen())
@@ -391,6 +388,9 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
             if (client.LocalUser?.State == MultiplayerUserState.Spectating && (SelectedItem.Value == null || Beatmap.IsDefault))
                 return;
 
+            if (BeatmapAvailability.Value.State != DownloadState.LocallyAvailable)
+                return;
+
             StartPlay();
         }
 

osu.Game/Screens/OnlinePlay/Multiplayer/Spectate/MultiSpectatorScreen.cs

@@ -214,7 +214,20 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         }
 
         protected override void StartGameplay(int userId, SpectatorGameplayState spectatorGameplayState)
-            => instances.Single(i => i.UserId == userId).LoadScore(spectatorGameplayState.Score);
+        {
+            var playerArea = instances.Single(i => i.UserId == userId);
+
+            // The multiplayer spectator flow requires the client to return to a higher level screen
+            // (ie. StartGameplay should only be called once per player).
+            //
+            // Meanwhile, the solo spectator flow supports multiple `StartGameplay` calls.
+            // To ensure we don't crash out in an edge case where this is called more than once in multiplayer,
+            // guard against re-entry for the same player.
+            if (playerArea.Score != null)
+                return;
+
+            playerArea.LoadScore(spectatorGameplayState.Score);
+        }
 
         protected override void QuitGameplay(int userId)
         {