Add OnlineMetadataClient

osu.Game/Online/EndpointConfiguration.cs

@@ -39,5 +39,10 @@ namespace osu.Game.Online
         /// The endpoint for the SignalR multiplayer server.
         /// </summary>
         public string MultiplayerEndpointUrl { get; set; }
+
+        /// <summary>
+        /// The endpoint for the SignalR metadata server.
+        /// </summary>
+        public string MetadataEndpointUrl { get; set; }
     }
 }

osu.Game/Online/Metadata/BeatmapUpdates.cs

@@ -0,0 +1,28 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using MessagePack;
+
+namespace osu.Game.Online.Metadata
+{
+    /// <summary>
+    /// Describes a set of beatmaps which have been updated in some way.
+    /// </summary>
+    [MessagePackObject]
+    [Serializable]
+    public class BeatmapUpdates
+    {
+        [Key(0)]
+        public int[] BeatmapSetIDs { get; set; }
+
+        [Key(1)]
+        public uint LastProcessedQueueID { get; set; }
+
+        public BeatmapUpdates(int[] beatmapSetIDs, uint lastProcessedQueueID)
+        {
+            BeatmapSetIDs = beatmapSetIDs;
+            LastProcessedQueueID = lastProcessedQueueID;
+        }
+    }
+}

osu.Game/Online/Metadata/IMetadataClient.cs

@@ -0,0 +1,12 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Threading.Tasks;
+
+namespace osu.Game.Online.Metadata
+{
+    public interface IMetadataClient
+    {
+        Task BeatmapSetsUpdated(BeatmapUpdates updates);
+    }
+}

osu.Game/Online/Metadata/IMetadataServer.cs

@@ -0,0 +1,21 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Threading.Tasks;
+
+namespace osu.Game.Online.Metadata
+{
+    /// <summary>
+    /// Metadata server is responsible for keeping the osu! client up-to-date with any changes.
+    /// </summary>
+    public interface IMetadataServer
+    {
+        /// <summary>
+        /// Get any changes since a specific point in the queue.
+        /// Should be used to allow the client to catch up with any changes after being closed or disconnected.
+        /// </summary>
+        /// <param name="queueId">The last processed queue ID.</param>
+        /// <returns></returns>
+        Task<BeatmapUpdates> GetChangesSince(uint queueId);
+    }
+}

osu.Game/Online/Metadata/MetadataClient.cs

@@ -0,0 +1,15 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Threading.Tasks;
+using osu.Framework.Graphics;
+
+namespace osu.Game.Online.Metadata
+{
+    public abstract class MetadataClient : Component, IMetadataClient, IMetadataServer
+    {
+        public abstract Task BeatmapSetsUpdated(BeatmapUpdates updates);
+
+        public abstract Task<BeatmapUpdates> GetChangesSince(uint queueId);
+    }
+}

osu.Game/Online/Metadata/OnlineMetadataClient.cs

@@ -0,0 +1,61 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.SignalR.Client;
+using osu.Framework.Allocation;
+using osu.Framework.Logging;
+using osu.Game.Online.API;
+
+namespace osu.Game.Online.Metadata
+{
+    public class OnlineMetadataClient : MetadataClient
+    {
+        private readonly string endpoint;
+
+        private IHubClientConnector? connector;
+
+        private HubConnection? connection => connector?.CurrentConnection;
+
+        public OnlineMetadataClient(EndpointConfiguration endpoints)
+        {
+            endpoint = endpoints.MetadataEndpointUrl;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(IAPIProvider api)
+        {
+            // 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.
+            connector = api.GetHubConnector(nameof(OnlineMetadataClient), endpoint);
+
+            if (connector != null)
+            {
+                connector.ConfigureConnection = connection =>
+                {
+                    // this is kind of SILLY
+                    // https://github.com/dotnet/aspnetcore/issues/15198
+                    connection.On<BeatmapUpdates>(nameof(IMetadataClient.BeatmapSetsUpdated), ((IMetadataClient)this).BeatmapSetsUpdated);
+                };
+            }
+        }
+
+        public override Task BeatmapSetsUpdated(BeatmapUpdates updates)
+        {
+            Logger.Log($"Received beatmap updates {updates.BeatmapSetIDs.Length} updates with last id {updates.LastProcessedQueueID}");
+            return Task.CompletedTask;
+        }
+
+        public override Task<BeatmapUpdates> GetChangesSince(uint queueId)
+        {
+            throw new NotImplementedException();
+        }
+
+        protected override void Dispose(bool isDisposing)
+        {
+            base.Dispose(isDisposing);
+            connector?.Dispose();
+        }
+    }
+}

osu.Game/OsuGameBase.cs

@@ -5,7 +5,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Threading;
@@ -41,6 +40,7 @@ using osu.Game.IO;
 using osu.Game.Online;
 using osu.Game.Online.API;
 using osu.Game.Online.Chat;
+using osu.Game.Online.Metadata;
 using osu.Game.Online.Multiplayer;
 using osu.Game.Online.Spectator;
 using osu.Game.Overlays;
@@ -52,6 +52,7 @@ using osu.Game.Rulesets.Mods;
 using osu.Game.Scoring;
 using osu.Game.Skinning;
 using osu.Game.Utils;
+using File = System.IO.File;
 using RuntimeInfo = osu.Framework.RuntimeInfo;
 
 namespace osu.Game
@@ -180,6 +181,8 @@ namespace osu.Game
 
         private MultiplayerClient multiplayerClient;
 
+        private MetadataClient metadataClient;
+
         private RealmAccess realm;
 
         protected override Container<Drawable> Content => content;
@@ -265,6 +268,7 @@ namespace osu.Game
 
             dependencies.CacheAs(spectatorClient = new OnlineSpectatorClient(endpoints));
             dependencies.CacheAs(multiplayerClient = new OnlineMultiplayerClient(endpoints));
+            dependencies.CacheAs(metadataClient = new OnlineMetadataClient(endpoints));
 
             var defaultBeatmap = new DummyWorkingBeatmap(Audio, Textures);
 
@@ -316,8 +320,10 @@ namespace osu.Game
             // add api components to hierarchy.
             if (API is APIAccess apiAccess)
                 AddInternal(apiAccess);
+
             AddInternal(spectatorClient);
             AddInternal(multiplayerClient);
+            AddInternal(metadataClient);
 
             AddInternal(rulesetConfigCache);