Fix multiplayer leaderboard not unsubscribing from quit users

osu.Game.Tests/Visual/Gameplay/TestSceneMultiplayerGameplayLeaderboard.cs

@@ -20,11 +20,12 @@ using osu.Game.Rulesets.Osu.Scoring;
 using osu.Game.Rulesets.Scoring;
 using osu.Game.Scoring;
 using osu.Game.Screens.Play.HUD;
+using osu.Game.Tests.Visual.Multiplayer;
 using osu.Game.Tests.Visual.Online;
 
 namespace osu.Game.Tests.Visual.Gameplay
 {
-    public class TestSceneMultiplayerGameplayLeaderboard : OsuTestScene
+    public class TestSceneMultiplayerGameplayLeaderboard : MultiplayerTestScene
     {
         [Cached(typeof(SpectatorStreamingClient))]
         private TestMultiplayerStreaming streamingClient = new TestMultiplayerStreaming(16);
@@ -47,7 +48,7 @@ namespace osu.Game.Tests.Visual.Gameplay
         }
 
         [SetUpSteps]
-        public void SetUpSteps()
+        public override void SetUpSteps()
         {
             AddStep("create leaderboard", () =>
             {

osu.Game/Screens/Play/HUD/MultiplayerGameplayLeaderboard.cs

@@ -2,12 +2,16 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.Diagnostics;
+using System.Linq;
 using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Game.Configuration;
 using osu.Game.Database;
 using osu.Game.Online.API;
+using osu.Game.Online.Multiplayer;
 using osu.Game.Online.Spectator;
 using osu.Game.Rulesets.Scoring;
 
@@ -18,10 +22,21 @@ namespace osu.Game.Screens.Play.HUD
     {
         private readonly ScoreProcessor scoreProcessor;
 
-        private readonly int[] userIds;
-
         private readonly Dictionary<int, TrackedUserData> userScores = new Dictionary<int, TrackedUserData>();
 
+        [Resolved]
+        private SpectatorStreamingClient streamingClient { get; set; }
+
+        [Resolved]
+        private StatefulMultiplayerClient multiplayerClient { get; set; }
+
+        [Resolved]
+        private UserLookupCache userLookupCache { get; set; }
+
+        private Bindable<ScoringMode> scoringMode;
+
+        private readonly BindableList<int> playingUsers;
+
         /// <summary>
         /// Construct a new leaderboard.
         /// </summary>
@@ -33,32 +48,24 @@ namespace osu.Game.Screens.Play.HUD
             this.scoreProcessor = scoreProcessor;
 
             // todo: this will likely be passed in as User instances.
-            this.userIds = userIds;
+            playingUsers = new BindableList<int>(userIds);
         }
 
-        [Resolved]
-        private SpectatorStreamingClient streamingClient { get; set; }
-
-        [Resolved]
-        private UserLookupCache userLookupCache { get; set; }
-
-        private Bindable<ScoringMode> scoringMode;
-
         [BackgroundDependencyLoader]
         private void load(OsuConfigManager config, IAPIProvider api)
         {
             streamingClient.OnNewFrames += handleIncomingFrames;
 
-            foreach (var user in userIds)
+            foreach (var userId in playingUsers)
             {
-                streamingClient.WatchUser(user);
+                streamingClient.WatchUser(userId);
 
                 // probably won't be required in the final implementation.
-                var resolvedUser = userLookupCache.GetUserAsync(user).Result;
+                var resolvedUser = userLookupCache.GetUserAsync(userId).Result;
 
                 var trackedUser = new TrackedUserData();
 
-                userScores[user] = trackedUser;
+                userScores[userId] = trackedUser;
                 var leaderboardScore = AddPlayer(resolvedUser, resolvedUser.Id == api.LocalUser.Value.Id);
 
                 ((IBindable<double>)leaderboardScore.Accuracy).BindTo(trackedUser.Accuracy);
@@ -70,6 +77,28 @@ namespace osu.Game.Screens.Play.HUD
             scoringMode.BindValueChanged(updateAllScores, true);
         }
 
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            playingUsers.BindCollectionChanged(usersChanged);
+            playingUsers.BindTo(multiplayerClient.PlayingUsers);
+        }
+
+        private void usersChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            switch (e.Action)
+            {
+                case NotifyCollectionChangedAction.Remove:
+                    foreach (var userId in e.OldItems.OfType<int>())
+                    {
+                        streamingClient.StopWatchingUser(userId);
+                    }
+
+                    break;
+            }
+        }
+
         private void updateAllScores(ValueChangedEvent<ScoringMode> mode)
         {
             foreach (var trackedData in userScores.Values)
@@ -91,7 +120,7 @@ namespace osu.Game.Screens.Play.HUD
 
             if (streamingClient != null)
             {
-                foreach (var user in userIds)
+                foreach (var user in playingUsers)
                 {
                     streamingClient.StopWatchingUser(user);
                 }