Add separate path for friend presence notifications

It proved to be too difficult to deal with the flow that clears user
states on stopping the watching of global presence updates. It's not
helped in the least that friends are updated via the API, so there's a
third flow to consider (and the timings therein - both server-spectator
and friends are updated concurrently).

Simplest is to separate the friends flow, though this does mean some
logic and state duplication.

osu.Game.Tests/Visual/Components/TestSceneFriendPresenceNotifier.cs

@@ -56,16 +56,16 @@ namespace osu.Game.Tests.Visual.Components
         [Test]
         public void TestNotifications()
         {
-            AddStep("bring friend 1 online", () => metadataClient.UserPresenceUpdated(1, new UserPresence { Status = UserStatus.Online }));
+            AddStep("bring friend 1 online", () => metadataClient.FriendPresenceUpdated(1, new UserPresence { Status = UserStatus.Online }));
             AddUntilStep("wait for notification", () => notificationOverlay.AllNotifications.Count(), () => Is.EqualTo(1));
-            AddStep("bring friend 1 offline", () => metadataClient.UserPresenceUpdated(1, null));
+            AddStep("bring friend 1 offline", () => metadataClient.FriendPresenceUpdated(1, null));
             AddUntilStep("wait for notification", () => notificationOverlay.AllNotifications.Count(), () => Is.EqualTo(2));
         }
 
         [Test]
         public void TestSingleUserNotificationOpensChat()
         {
-            AddStep("bring friend 1 online", () => metadataClient.UserPresenceUpdated(1, new UserPresence { Status = UserStatus.Online }));
+            AddStep("bring friend 1 online", () => metadataClient.FriendPresenceUpdated(1, new UserPresence { Status = UserStatus.Online }));
             AddUntilStep("wait for notification", () => notificationOverlay.AllNotifications.Count(), () => Is.EqualTo(1));
 
             AddStep("click notification", () =>
@@ -83,8 +83,8 @@ namespace osu.Game.Tests.Visual.Components
         {
             AddStep("bring friends 1 & 2 online", () =>
             {
-                metadataClient.UserPresenceUpdated(1, new UserPresence { Status = UserStatus.Online });
+                metadataClient.FriendPresenceUpdated(1, new UserPresence { Status = UserStatus.Online });
-                metadataClient.UserPresenceUpdated(2, new UserPresence { Status = UserStatus.Online });
+                metadataClient.FriendPresenceUpdated(2, new UserPresence { Status = UserStatus.Online });
             });
 
             AddUntilStep("wait for notification", () => notificationOverlay.AllNotifications.Count(), () => Is.EqualTo(1));
@@ -112,7 +112,7 @@ namespace osu.Game.Tests.Visual.Components
             AddStep("bring friends 1-10 online", () =>
             {
                 for (int i = 1; i <= 10; i++)
-                    metadataClient.UserPresenceUpdated(i, new UserPresence { Status = UserStatus.Online });
+                    metadataClient.FriendPresenceUpdated(i, new UserPresence { Status = UserStatus.Online });
             });
 
             AddUntilStep("wait for notification", () => notificationOverlay.AllNotifications.Count(), () => Is.EqualTo(1));
@@ -120,7 +120,7 @@ namespace osu.Game.Tests.Visual.Components
             AddStep("bring friends 1-10 offline", () =>
             {
                 for (int i = 1; i <= 10; i++)
-                    metadataClient.UserPresenceUpdated(i, null);
+                    metadataClient.FriendPresenceUpdated(i, null);
             });
 
             AddUntilStep("wait for notification", () => notificationOverlay.AllNotifications.Count(), () => Is.EqualTo(2));

osu.Game/Online/API/APIAccess.cs

@@ -6,6 +6,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 using System.Net;
 using System.Net.Http;
 using System.Net.Sockets;
@@ -18,6 +19,7 @@ using osu.Framework.Extensions.ObjectExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Logging;
 using osu.Game.Configuration;
+using osu.Game.Extensions;
 using osu.Game.Localisation;
 using osu.Game.Online.API.Requests;
 using osu.Game.Online.API.Requests.Responses;
@@ -75,7 +77,6 @@ namespace osu.Game.Online.API
 
         protected bool HasLogin => authentication.Token.Value != null || (!string.IsNullOrEmpty(ProvidedUsername) && !string.IsNullOrEmpty(password));
 
-        private readonly Dictionary<int, APIRelation> friendsMapping = new Dictionary<int, APIRelation>();
         private readonly CancellationTokenSource cancellationToken = new CancellationTokenSource();
 
         private readonly Logger log;
@@ -404,8 +405,6 @@ namespace osu.Game.Online.API
 
         public IChatClient GetChatClient() => new WebSocketChatClient(this);
 
-        public APIRelation GetFriend(int userId) => friendsMapping.GetValueOrDefault(userId);
-
         public RegistrationRequest.RegistrationRequestErrors CreateAccount(string email, string username, string password)
         {
             Debug.Assert(State.Value == APIState.Offline);
@@ -597,8 +596,6 @@ namespace osu.Game.Online.API
             Schedule(() =>
             {
                 setLocalUser(createGuestUser());
-
-                friendsMapping.Clear();
                 friends.Clear();
             });
 
@@ -615,12 +612,14 @@ namespace osu.Game.Online.API
             friendsReq.Failure += _ => state.Value = APIState.Failing;
             friendsReq.Success += res =>
             {
-                friendsMapping.Clear();
+                // Add new friends into local list.
-                friends.Clear();
+                HashSet<int> friendsSet = friends.Select(f => f.TargetID).ToHashSet();
+                friends.AddRange(res.Where(f => !friendsSet.Contains(f.TargetID)));
 
-                foreach (var u in res)
+                // Remove non-friends from local lists.
-                    friendsMapping[u.TargetID] = u;
+                friendsSet.Clear();
-                friends.AddRange(res);
+                friendsSet.AddRange(res.Select(f => f.TargetID));
+                friends.RemoveAll(f => !friendsSet.Contains(f.TargetID));
             };
 
             Queue(friendsReq);

osu.Game/Online/API/DummyAPIAccess.cs

@@ -2,7 +2,6 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
-using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using osu.Framework.Bindables;
@@ -195,8 +194,6 @@ namespace osu.Game.Online.API
 
         public IChatClient GetChatClient() => new TestChatClientConnector(this);
 
-        public APIRelation? GetFriend(int userId) => Friends.FirstOrDefault(r => r.TargetID == userId);
-
         public RegistrationRequest.RegistrationRequestErrors? CreateAccount(string email, string username, string password)
         {
             Thread.Sleep(200);

osu.Game/Online/API/IAPIProvider.cs

@@ -152,13 +152,6 @@ namespace osu.Game.Online.API
         /// </summary>
         IChatClient GetChatClient();
 
-        /// <summary>
-        /// Retrieves a friend from a given user ID.
-        /// </summary>
-        /// <param name="userId">The friend's user ID.</param>
-        /// <returns>The <see cref="APIRelation"/> object representing the friend, if any.</returns>
-        APIRelation? GetFriend(int userId);
-
         /// <summary>
         /// Create a new user account. This is a blocking operation.
         /// </summary>

osu.Game/Online/FriendPresenceNotifier.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Collections.Generic;
+using System.Collections.Specialized;
 using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
@@ -43,7 +44,10 @@ namespace osu.Game.Online
         private OsuConfigManager config { get; set; } = null!;
 
         private readonly Bindable<bool> notifyOnFriendPresenceChange = new BindableBool();
-        private readonly IBindableDictionary<int, UserPresence> userStates = new BindableDictionary<int, UserPresence>();
+
+        private readonly IBindableList<APIRelation> friends = new BindableList<APIRelation>();
+        private readonly IBindableDictionary<int, UserPresence> friendStates = new BindableDictionary<int, UserPresence>();
+
         private readonly HashSet<APIUser> onlineAlertQueue = new HashSet<APIUser>();
         private readonly HashSet<APIUser> offlineAlertQueue = new HashSet<APIUser>();
 
@@ -56,42 +60,11 @@ namespace osu.Game.Online
 
             config.BindWith(OsuSetting.NotifyOnFriendPresenceChange, notifyOnFriendPresenceChange);
 
-            userStates.BindTo(metadataClient.UserStates);
+            friends.BindTo(api.Friends);
-            userStates.BindCollectionChanged((_, args) =>
+            friends.BindCollectionChanged(onFriendsChanged, true);
-            {
-                switch (args.Action)
-                {
-                    case NotifyDictionaryChangedAction.Add:
-                        foreach ((int userId, var _) in args.NewItems!)
-                        {
-                            if (api.GetFriend(userId)?.TargetUser is APIUser user)
-                            {
-                                if (!offlineAlertQueue.Remove(user))
-                                {
-                                    onlineAlertQueue.Add(user);
-                                    lastOnlineAlertTime ??= Time.Current;
-                                }
-                            }
-                        }
 
-                        break;
+            friendStates.BindTo(metadataClient.FriendStates);
-
+            friendStates.BindCollectionChanged(onFriendStatesChanged, true);
-                    case NotifyDictionaryChangedAction.Remove:
-                        foreach ((int userId, var _) in args.OldItems!)
-                        {
-                            if (api.GetFriend(userId)?.TargetUser is APIUser user)
-                            {
-                                if (!onlineAlertQueue.Remove(user))
-                                {
-                                    offlineAlertQueue.Add(user);
-                                    lastOfflineAlertTime ??= Time.Current;
-                                }
-                            }
-                        }
-
-                        break;
-                }
-            });
         }
 
         protected override void Update()
@@ -102,6 +75,82 @@ namespace osu.Game.Online
             alertOfflineUsers();
         }
 
+        private void onFriendsChanged(object? sender, NotifyCollectionChangedEventArgs e)
+        {
+            switch (e.Action)
+            {
+                case NotifyCollectionChangedAction.Add:
+                    foreach (APIRelation friend in e.NewItems!.Cast<APIRelation>())
+                    {
+                        if (friend.TargetUser is not APIUser user)
+                            continue;
+
+                        if (friendStates.TryGetValue(friend.TargetID, out _))
+                            markUserOnline(user);
+                    }
+
+                    break;
+
+                case NotifyCollectionChangedAction.Remove:
+                    foreach (APIRelation friend in e.OldItems!.Cast<APIRelation>())
+                    {
+                        if (friend.TargetUser is not APIUser user)
+                            continue;
+
+                        onlineAlertQueue.Remove(user);
+                        offlineAlertQueue.Remove(user);
+                    }
+
+                    break;
+            }
+        }
+
+        private void onFriendStatesChanged(object? sender, NotifyDictionaryChangedEventArgs<int, UserPresence> e)
+        {
+            switch (e.Action)
+            {
+                case NotifyDictionaryChangedAction.Add:
+                    foreach ((int friendId, _) in e.NewItems!)
+                    {
+                        APIRelation? friend = friends.FirstOrDefault(f => f.TargetID == friendId);
+
+                        if (friend?.TargetUser is APIUser user)
+                            markUserOnline(user);
+                    }
+
+                    break;
+
+                case NotifyDictionaryChangedAction.Remove:
+                    foreach ((int friendId, _) in e.OldItems!)
+                    {
+                        APIRelation? friend = friends.FirstOrDefault(f => f.TargetID == friendId);
+
+                        if (friend?.TargetUser is APIUser user)
+                            markUserOffline(user);
+                    }
+
+                    break;
+            }
+        }
+
+        private void markUserOnline(APIUser user)
+        {
+            if (!offlineAlertQueue.Remove(user))
+            {
+                onlineAlertQueue.Add(user);
+                lastOnlineAlertTime ??= Time.Current;
+            }
+        }
+
+        private void markUserOffline(APIUser user)
+        {
+            if (!onlineAlertQueue.Remove(user))
+            {
+                offlineAlertQueue.Add(user);
+                lastOfflineAlertTime ??= Time.Current;
+            }
+        }
+
         private void alertOnlineUsers()
         {
             if (onlineAlertQueue.Count == 0)

osu.Game/Online/Metadata/IMetadataClient.cs

@@ -21,6 +21,11 @@ namespace osu.Game.Online.Metadata
         /// </summary>
         Task UserPresenceUpdated(int userId, UserPresence? status);
 
+        /// <summary>
+        /// Delivers and update of the <see cref="UserPresence"/> of a friend with the supplied <paramref name="userId"/>.
+        /// </summary>
+        Task FriendPresenceUpdated(int userId, UserPresence? presence);
+
         /// <summary>
         /// Delivers an update of the current "daily challenge" status.
         /// Null value means there is no "daily challenge" currently active.

osu.Game/Online/Metadata/MetadataClient.cs

@@ -42,6 +42,11 @@ namespace osu.Game.Online.Metadata
         /// </summary>
         public abstract IBindableDictionary<int, UserPresence> UserStates { get; }
 
+        /// <summary>
+        /// Dictionary keyed by user ID containing all of the <see cref="UserPresence"/> information about currently online friends received from the server.
+        /// </summary>
+        public abstract IBindableDictionary<int, UserPresence> FriendStates { get; }
+
         /// <inheritdoc/>
         public abstract Task UpdateActivity(UserActivity? activity);
 
@@ -57,6 +62,9 @@ namespace osu.Game.Online.Metadata
         /// <inheritdoc/>
         public abstract Task UserPresenceUpdated(int userId, UserPresence? presence);
 
+        /// <inheritdoc/>
+        public abstract Task FriendPresenceUpdated(int userId, UserPresence? presence);
+
         #endregion
 
         #region Daily Challenge

osu.Game/Online/Metadata/OnlineMetadataClient.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Diagnostics;
-using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.SignalR.Client;
@@ -27,14 +26,14 @@ namespace osu.Game.Online.Metadata
         public override IBindableDictionary<int, UserPresence> UserStates => userStates;
         private readonly BindableDictionary<int, UserPresence> userStates = new BindableDictionary<int, UserPresence>();
 
+        public override IBindableDictionary<int, UserPresence> FriendStates => friendStates;
+        private readonly BindableDictionary<int, UserPresence> friendStates = new BindableDictionary<int, UserPresence>();
+
         public override IBindable<DailyChallengeInfo?> DailyChallengeInfo => dailyChallengeInfo;
         private readonly Bindable<DailyChallengeInfo?> dailyChallengeInfo = new Bindable<DailyChallengeInfo?>();
 
         private readonly string endpoint;
 
-        [Resolved]
-        private IAPIProvider api { get; set; } = null!;
-
         private IHubClientConnector? connector;
         private Bindable<int> lastQueueId = null!;
         private IBindable<APIUser> localUser = null!;
@@ -49,7 +48,7 @@ namespace osu.Game.Online.Metadata
         }
 
         [BackgroundDependencyLoader]
-        private void load(OsuConfigManager config)
+        private void load(IAPIProvider api, OsuConfigManager config)
         {
             // Importantly, we are intentionally not using MessagePack here to correctly support derived class serialization.
             // More information on the limitations / reasoning can be found in osu-server-spectator's initialisation code.
@@ -63,6 +62,7 @@ namespace osu.Game.Online.Metadata
                     // https://github.com/dotnet/aspnetcore/issues/15198
                     connection.On<BeatmapUpdates>(nameof(IMetadataClient.BeatmapSetsUpdated), ((IMetadataClient)this).BeatmapSetsUpdated);
                     connection.On<int, UserPresence?>(nameof(IMetadataClient.UserPresenceUpdated), ((IMetadataClient)this).UserPresenceUpdated);
+                    connection.On<int, UserPresence?>(nameof(IMetadataClient.FriendPresenceUpdated), ((IMetadataClient)this).FriendPresenceUpdated);
                     connection.On<DailyChallengeInfo?>(nameof(IMetadataClient.DailyChallengeUpdated), ((IMetadataClient)this).DailyChallengeUpdated);
                     connection.On<MultiplayerRoomScoreSetEvent>(nameof(IMetadataClient.MultiplayerRoomScoreSet), ((IMetadataClient)this).MultiplayerRoomScoreSet);
                     connection.On(nameof(IStatefulUserHubClient.DisconnectRequested), ((IMetadataClient)this).DisconnectRequested);
@@ -108,6 +108,7 @@ namespace osu.Game.Online.Metadata
                 {
                     isWatchingUserPresence.Value = false;
                     userStates.Clear();
+                    friendStates.Clear();
                     dailyChallengeInfo.Value = null;
                 });
                 return;
@@ -209,6 +210,19 @@ namespace osu.Game.Online.Metadata
             return Task.CompletedTask;
         }
 
+        public override Task FriendPresenceUpdated(int userId, UserPresence? presence)
+        {
+            Schedule(() =>
+            {
+                if (presence?.Status != null)
+                    friendStates[userId] = presence.Value;
+                else
+                    friendStates.Remove(userId);
+            });
+
+            return Task.CompletedTask;
+        }
+
         public override async Task BeginWatchingUserPresence()
         {
             if (connector?.IsConnected.Value != true)
@@ -228,15 +242,7 @@ namespace osu.Game.Online.Metadata
                     throw new OperationCanceledException();
 
                 // must be scheduled before any remote calls to avoid mis-ordering.
-                Schedule(() =>
+                Schedule(() => userStates.Clear());
-                {
-                    foreach (int userId in userStates.Keys.ToArray())
-                    {
-                        if (api.GetFriend(userId) == null)
-                            userStates.Remove(userId);
-                    }
-                });
-
                 Debug.Assert(connection != null);
                 await connection.InvokeAsync(nameof(IMetadataServer.EndWatchingUserPresence)).ConfigureAwait(false);
                 Logger.Log($@"{nameof(OnlineMetadataClient)} stopped watching user presence", LoggingTarget.Network);

osu.Game/Tests/Visual/Metadata/TestMetadataClient.cs

@@ -2,7 +2,6 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
-using System.Linq;
 using System.Threading.Tasks;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
@@ -23,6 +22,9 @@ namespace osu.Game.Tests.Visual.Metadata
         public override IBindableDictionary<int, UserPresence> UserStates => userStates;
         private readonly BindableDictionary<int, UserPresence> userStates = new BindableDictionary<int, UserPresence>();
 
+        public override IBindableDictionary<int, UserPresence> FriendStates => friendStates;
+        private readonly BindableDictionary<int, UserPresence> friendStates = new BindableDictionary<int, UserPresence>();
+
         public override Bindable<DailyChallengeInfo?> DailyChallengeInfo => dailyChallengeInfo;
         private readonly Bindable<DailyChallengeInfo?> dailyChallengeInfo = new Bindable<DailyChallengeInfo?>();
 
@@ -67,7 +69,7 @@ namespace osu.Game.Tests.Visual.Metadata
 
         public override Task UserPresenceUpdated(int userId, UserPresence? presence)
         {
-            if (isWatchingUserPresence.Value || api.Friends.Any(f => f.TargetID == userId))
+            if (isWatchingUserPresence.Value)
             {
                 if (presence.HasValue)
                     userStates[userId] = presence.Value;
@@ -78,6 +80,16 @@ namespace osu.Game.Tests.Visual.Metadata
             return Task.CompletedTask;
         }
 
+        public override Task FriendPresenceUpdated(int userId, UserPresence? presence)
+        {
+            if (presence.HasValue)
+                friendStates[userId] = presence.Value;
+            else
+                friendStates.Remove(userId);
+
+            return Task.CompletedTask;
+        }
+
         public override Task<BeatmapUpdates> GetChangesSince(int queueId)
             => Task.FromResult(new BeatmapUpdates(Array.Empty<int>(), queueId));