Fix merge conflicts.

.config/dotnet-tools.json

@@ -15,7 +15,7 @@
       ]
     },
     "jetbrains.resharper.globaltools": {
-      "version": "2020.2.4",
+      "version": "2020.3.2",
       "commands": [
         "jb"
       ]

Directory.Build.props

@@ -16,7 +16,7 @@
     <EmbeddedResource Include="Resources\**\*.*" />
   </ItemGroup>
   <ItemGroup Label="Code Analysis">
-    <PackageReference Include="Microsoft.CodeAnalysis.BannedApiAnalyzers" Version="3.3.1" PrivateAssets="All" />
+    <PackageReference Include="Microsoft.CodeAnalysis.BannedApiAnalyzers" Version="3.3.2" PrivateAssets="All" />
     <AdditionalFiles Include="$(MSBuildThisFileDirectory)CodeAnalysis\BannedSymbols.txt" />
     <PackageReference Include="Microsoft.CodeAnalysis.FxCopAnalyzers" Version="3.3.1" PrivateAssets="All" />
   </ItemGroup>

Gemfile.lock

@@ -1,27 +1,27 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    CFPropertyList (3.0.2)
+    CFPropertyList (3.0.3)
     addressable (2.7.0)
       public_suffix (>= 2.0.2, < 5.0)
     atomos (0.1.3)
     aws-eventstream (1.1.0)
-    aws-partitions (1.354.0)
+    aws-partitions (1.413.0)
-    aws-sdk-core (3.104.3)
+    aws-sdk-core (3.110.0)
       aws-eventstream (~> 1, >= 1.0.2)
       aws-partitions (~> 1, >= 1.239.0)
       aws-sigv4 (~> 1.1)
       jmespath (~> 1.0)
-    aws-sdk-kms (1.36.0)
+    aws-sdk-kms (1.40.0)
-      aws-sdk-core (~> 3, >= 3.99.0)
+      aws-sdk-core (~> 3, >= 3.109.0)
       aws-sigv4 (~> 1.1)
-    aws-sdk-s3 (1.78.0)
+    aws-sdk-s3 (1.87.0)
-      aws-sdk-core (~> 3, >= 3.104.3)
+      aws-sdk-core (~> 3, >= 3.109.0)
       aws-sdk-kms (~> 1)
       aws-sigv4 (~> 1.1)
-    aws-sigv4 (1.2.1)
+    aws-sigv4 (1.2.2)
       aws-eventstream (~> 1, >= 1.0.2)
-    babosa (1.0.3)
+    babosa (1.0.4)
     claide (1.0.3)
     colored (1.2)
     colored2 (3.1.2)
@@ -29,22 +29,23 @@ GEM
       highline (~> 1.7.2)
     declarative (0.0.20)
     declarative-option (0.1.0)
-    digest-crc (0.6.1)
+    digest-crc (0.6.3)
-      rake (~> 13.0)
+      rake (>= 12.0.0, < 14.0.0)
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
     dotenv (2.7.6)
-    emoji_regex (3.0.0)
+    emoji_regex (3.2.1)
-    excon (0.76.0)
+    excon (0.78.1)
-    faraday (1.0.1)
+    faraday (1.2.0)
       multipart-post (>= 1.2, < 3)
-    faraday-cookie_jar (0.0.6)
+      ruby2_keywords
-      faraday (>= 0.7.4)
+    faraday-cookie_jar (0.0.7)
+      faraday (>= 0.8.0)
       http-cookie (~> 1.0.0)
     faraday_middleware (1.0.0)
       faraday (~> 1.0)
-    fastimage (2.2.0)
+    fastimage (2.2.1)
-    fastlane (2.156.0)
+    fastlane (2.170.0)
       CFPropertyList (>= 2.3, < 4.0.0)
       addressable (>= 2.3, < 3.0.0)
       aws-sdk-s3 (~> 1.0)
@@ -96,17 +97,17 @@ GEM
     google-cloud-core (1.5.0)
       google-cloud-env (~> 1.0)
       google-cloud-errors (~> 1.0)
-    google-cloud-env (1.3.3)
+    google-cloud-env (1.4.0)
       faraday (>= 0.17.3, < 2.0)
     google-cloud-errors (1.0.1)
-    google-cloud-storage (1.27.0)
+    google-cloud-storage (1.29.2)
       addressable (~> 2.5)
       digest-crc (~> 0.4)
       google-api-client (~> 0.33)
       google-cloud-core (~> 1.2)
       googleauth (~> 0.9)
       mini_mime (~> 1.0)
-    googleauth (0.13.1)
+    googleauth (0.14.0)
       faraday (>= 0.17.3, < 2.0)
       jwt (>= 1.4, < 3.0)
       memoist (~> 0.16)
@@ -118,10 +119,10 @@ GEM
       domain_name (~> 0.5)
     httpclient (2.8.3)
     jmespath (1.4.0)
-    json (2.3.1)
+    json (2.5.1)
-    jwt (2.2.1)
+    jwt (2.2.2)
     memoist (0.16.2)
-    mini_magick (4.10.1)
+    mini_magick (4.11.0)
     mini_mime (1.0.2)
     mini_portile2 (2.4.0)
     multi_json (1.15.0)
@@ -132,14 +133,15 @@ GEM
       mini_portile2 (~> 2.4.0)
     os (1.1.1)
     plist (3.5.0)
-    public_suffix (4.0.5)
+    public_suffix (4.0.6)
-    rake (13.0.1)
+    rake (13.0.3)
     representable (3.0.4)
       declarative (< 0.1.0)
       declarative-option (< 0.2.0)
       uber (< 0.2.0)
     retriable (3.1.2)
     rouge (2.0.7)
+    ruby2_keywords (0.0.2)
     rubyzip (2.3.0)
     security (0.1.3)
     signet (0.14.0)
@@ -168,7 +170,7 @@ GEM
     unf_ext (0.0.7.7)
     unicode-display_width (1.7.0)
     word_wrap (1.0.0)
-    xcodeproj (1.18.0)
+    xcodeproj (1.19.0)
       CFPropertyList (>= 2.3.3, < 4.0)
       atomos (~> 0.1.3)
       claide (>= 1.0.2, < 2.0)

osu.Android.props

@@ -52,6 +52,6 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="ppy.osu.Game.Resources" Version="2020.1202.0" />
-    <PackageReference Include="ppy.osu.Framework.Android" Version="2020.1222.0" />
+    <PackageReference Include="ppy.osu.Framework.Android" Version="2020.1229.0" />
   </ItemGroup>
 </Project>

osu.Android/OsuGameActivity.cs

@@ -18,7 +18,9 @@ using osu.Game.Database;
 namespace osu.Android
 {
     [Activity(Theme = "@android:style/Theme.NoTitleBar", MainLauncher = true, ScreenOrientation = ScreenOrientation.FullUser, SupportsPictureInPicture = false, ConfigurationChanges = ConfigChanges.Orientation | ConfigChanges.ScreenSize, HardwareAccelerated = false, LaunchMode = LaunchMode.SingleInstance)]
-    [IntentFilter(new[] { Intent.ActionDefault, Intent.ActionSend, Intent.ActionSendMultiple }, Categories = new[] { Intent.CategoryDefault }, DataPathPatterns = new[] { ".*\\.osz", ".*\\.osk" }, DataMimeType = "application/*")]
+    [IntentFilter(new[] { Intent.ActionView }, Categories = new[] { Intent.CategoryDefault }, DataScheme = "content", DataPathPattern = ".*\\\\.osz", DataHost = "*", DataMimeType = "*/*")]
+    [IntentFilter(new[] { Intent.ActionView }, Categories = new[] { Intent.CategoryDefault }, DataScheme = "content", DataPathPattern = ".*\\\\.osk", DataHost = "*", DataMimeType = "*/*")]
+    [IntentFilter(new[] { Intent.ActionSend, Intent.ActionSendMultiple }, Categories = new[] { Intent.CategoryDefault }, DataMimeTypes = new[] { "application/zip", "application/octet-stream" })]
     [IntentFilter(new[] { Intent.ActionView }, Categories = new[] { Intent.CategoryBrowsable, Intent.CategoryDefault }, DataSchemes = new[] { "osu", "osump" })]
     public class OsuGameActivity : AndroidGameActivity
     {

osu.Game.Rulesets.Catch.Tests/osu.Game.Rulesets.Catch.Tests.csproj

@@ -2,7 +2,7 @@
   <Import Project="..\osu.TestProject.props" />
   <ItemGroup Label="Package References">
     <PackageReference Include="Appveyor.TestLogger" Version="2.0.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
     <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.17.0" />
     <PackageReference Update="Microsoft.EntityFrameworkCore.Sqlite" Version="2.1.4" />

osu.Game.Rulesets.Mania.Tests/osu.Game.Rulesets.Mania.Tests.csproj

@@ -2,7 +2,7 @@
   <Import Project="..\osu.TestProject.props" />
   <ItemGroup Label="Package References">
     <PackageReference Include="Appveyor.TestLogger" Version="2.0.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
     <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.17.0" />
     <PackageReference Update="Microsoft.EntityFrameworkCore.Sqlite" Version="2.1.4" />

osu.Game.Rulesets.Osu.Tests/osu.Game.Rulesets.Osu.Tests.csproj

@@ -2,7 +2,7 @@
   <Import Project="..\osu.TestProject.props" />
   <ItemGroup Label="Package References">
     <PackageReference Include="Appveyor.TestLogger" Version="2.0.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
     <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.17.0" />
     <PackageReference Update="Microsoft.EntityFrameworkCore.Sqlite" Version="2.1.4" />

osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyCursorTrail.cs

@@ -20,17 +20,14 @@ namespace osu.Game.Rulesets.Osu.Skinning.Legacy
         private double lastTrailTime;
         private IBindable<float> cursorSize;
 
-        public LegacyCursorTrail()
-        {
-            Blending = BlendingParameters.Additive;
-        }
-
         [BackgroundDependencyLoader]
         private void load(ISkinSource skin, OsuConfigManager config)
         {
             Texture = skin.GetTexture("cursortrail");
             disjointTrail = skin.GetTexture("cursormiddle") == null;
 
+            Blending = !disjointTrail ? BlendingParameters.Additive : BlendingParameters.Inherit;
+
             if (Texture != null)
             {
                 // stable "magic ratio". see OsuPlayfieldAdjustmentContainer for full explanation.

osu.Game.Rulesets.Taiko.Tests/osu.Game.Rulesets.Taiko.Tests.csproj

@@ -2,7 +2,7 @@
   <Import Project="..\osu.TestProject.props" />
   <ItemGroup Label="Package References">
     <PackageReference Include="Appveyor.TestLogger" Version="2.0.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
     <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.17.0" />
     <PackageReference Update="Microsoft.EntityFrameworkCore.Sqlite" Version="2.1.4" />

osu.Game.Tests/NonVisual/Multiplayer/StatefulMultiplayerClientTest.cs

@@ -0,0 +1,57 @@
+// 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.Linq;
+using Humanizer;
+using NUnit.Framework;
+using osu.Framework.Testing;
+using osu.Game.Online.Multiplayer;
+using osu.Game.Tests.Visual.Multiplayer;
+using osu.Game.Users;
+
+namespace osu.Game.Tests.NonVisual.Multiplayer
+{
+    [HeadlessTest]
+    public class StatefulMultiplayerClientTest : MultiplayerTestScene
+    {
+        [Test]
+        public void TestPlayingUserTracking()
+        {
+            int id = 2000;
+
+            AddRepeatStep("add some users", () => Client.AddUser(new User { Id = id++ }), 5);
+            checkPlayingUserCount(0);
+
+            changeState(3, MultiplayerUserState.WaitingForLoad);
+            checkPlayingUserCount(3);
+
+            changeState(3, MultiplayerUserState.Playing);
+            checkPlayingUserCount(3);
+
+            changeState(3, MultiplayerUserState.Results);
+            checkPlayingUserCount(0);
+
+            changeState(6, MultiplayerUserState.WaitingForLoad);
+            checkPlayingUserCount(6);
+
+            AddStep("another user left", () => Client.RemoveUser(Client.Room?.Users.Last().User));
+            checkPlayingUserCount(5);
+
+            AddStep("leave room", () => Client.LeaveRoom());
+            checkPlayingUserCount(0);
+        }
+
+        private void checkPlayingUserCount(int expectedCount)
+            => AddAssert($"{"user".ToQuantity(expectedCount)} playing", () => Client.CurrentMatchPlayingUserIds.Count == expectedCount);
+
+        private void changeState(int userCount, MultiplayerUserState state)
+            => AddStep($"{"user".ToQuantity(userCount)} in {state}", () =>
+            {
+                for (int i = 0; i < userCount; ++i)
+                {
+                    var userId = Client.Room?.Users[i].UserID ?? throw new AssertionException("Room cannot be null!");
+                    Client.ChangeUserState(userId, state);
+                }
+            });
+    }
+}

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

@@ -8,7 +8,6 @@ using osu.Framework.Audio.Track;
 using osu.Framework.Graphics.Containers;
 using osu.Game.Audio;
 using osu.Game.Beatmaps;
-using static osu.Game.Tests.Visual.Components.TestScenePreviewTrackManager.TestPreviewTrackManager;
 
 namespace osu.Game.Tests.Visual.Components
 {
@@ -100,7 +99,7 @@ namespace osu.Game.Tests.Visual.Components
         [Test]
         public void TestNonPresentTrack()
         {
-            TestPreviewTrack track = null;
+            TestPreviewTrackManager.TestPreviewTrack track = null;
 
             AddStep("get non-present track", () =>
             {
@@ -182,9 +181,9 @@ namespace osu.Game.Tests.Visual.Components
             AddAssert("track stopped", () => !track.IsRunning);
         }
 
-        private TestPreviewTrack getTrack() => (TestPreviewTrack)trackManager.Get(null);
+        private TestPreviewTrackManager.TestPreviewTrack getTrack() => (TestPreviewTrackManager.TestPreviewTrack)trackManager.Get(null);
 
-        private TestPreviewTrack getOwnedTrack()
+        private TestPreviewTrackManager.TestPreviewTrack getOwnedTrack()
         {
             var track = getTrack();
 

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

@@ -95,7 +95,7 @@ namespace osu.Game.Tests.Visual.Gameplay
         {
             public bool CheckPositionByUsername(string username, int? expectedPosition)
             {
-                var scoreItem = this.FirstOrDefault(i => i.User.Username == username);
+                var scoreItem = this.FirstOrDefault(i => i.User?.Username == username);
 
                 return scoreItem != null && scoreItem.ScorePosition == expectedPosition;
             }

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

@@ -9,7 +9,7 @@ using osu.Game.Rulesets;
 using osu.Game.Rulesets.Judgements;
 using osu.Game.Rulesets.Osu;
 using osu.Game.Rulesets.Osu.Judgements;
-using osu.Game.Screens.Play;
+using osu.Game.Screens.Play.HUD;
 
 namespace osu.Game.Tests.Visual.Gameplay
 {

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

@@ -22,12 +22,14 @@ using osu.Game.Scoring;
 using osu.Game.Screens.Play.HUD;
 using osu.Game.Tests.Visual.Online;
 
-namespace osu.Game.Tests.Visual.Gameplay
+namespace osu.Game.Tests.Visual.Multiplayer
 {
-    public class TestSceneMultiplayerGameplayLeaderboard : OsuTestScene
+    public class TestSceneMultiplayerGameplayLeaderboard : MultiplayerTestScene
     {
+        private const int users = 16;
+
         [Cached(typeof(SpectatorStreamingClient))]
-        private TestMultiplayerStreaming streamingClient = new TestMultiplayerStreaming(16);
+        private TestMultiplayerStreaming streamingClient = new TestMultiplayerStreaming(users);
 
         [Cached(typeof(UserLookupCache))]
         private UserLookupCache lookupCache = new TestSceneCurrentlyPlayingDisplay.TestUserLookupCache();
@@ -47,10 +49,12 @@ namespace osu.Game.Tests.Visual.Gameplay
         }
 
         [SetUpSteps]
-        public void SetUpSteps()
+        public override void SetUpSteps()
         {
             AddStep("create leaderboard", () =>
             {
+                leaderboard?.Expire();
+
                 OsuScoreProcessor scoreProcessor;
                 Beatmap.Value = CreateWorkingBeatmap(Ruleset.Value);
 
@@ -58,6 +62,9 @@ namespace osu.Game.Tests.Visual.Gameplay
 
                 streamingClient.Start(Beatmap.Value.BeatmapInfo.OnlineBeatmapID ?? 0);
 
+                Client.CurrentMatchPlayingUserIds.Clear();
+                Client.CurrentMatchPlayingUserIds.AddRange(streamingClient.PlayingUsers);
+
                 Children = new Drawable[]
                 {
                     scoreProcessor = new OsuScoreProcessor(),
@@ -81,6 +88,12 @@ namespace osu.Game.Tests.Visual.Gameplay
             AddRepeatStep("update state", () => streamingClient.RandomlyUpdateState(), 100);
         }
 
+        [Test]
+        public void TestUserQuit()
+        {
+            AddRepeatStep("mark user quit", () => Client.CurrentMatchPlayingUserIds.RemoveAt(0), users);
+        }
+
         public class TestMultiplayerStreaming : SpectatorStreamingClient
         {
             public new BindableList<int> PlayingUsers => (BindableList<int>)base.PlayingUsers;

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

@@ -0,0 +1,145 @@
+// 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.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Audio;
+using osu.Framework.Extensions;
+using osu.Framework.Platform;
+using osu.Framework.Screens;
+using osu.Framework.Utils;
+using osu.Game.Beatmaps;
+using osu.Game.Rulesets;
+using osu.Game.Rulesets.Catch;
+using osu.Game.Rulesets.Osu;
+using osu.Game.Rulesets.Osu.Mods;
+using osu.Game.Rulesets.Taiko;
+using osu.Game.Rulesets.Taiko.Mods;
+using osu.Game.Screens.OnlinePlay.Multiplayer;
+using osu.Game.Screens.Select;
+
+namespace osu.Game.Tests.Visual.Multiplayer
+{
+    public class TestSceneMultiplayerMatchSongSelect : RoomTestScene
+    {
+        private BeatmapManager manager;
+        private RulesetStore rulesets;
+
+        private List<BeatmapInfo> beatmaps;
+
+        private TestMultiplayerMatchSongSelect songSelect;
+
+        [BackgroundDependencyLoader]
+        private void load(GameHost host, AudioManager audio)
+        {
+            Dependencies.Cache(rulesets = new RulesetStore(ContextFactory));
+            Dependencies.Cache(manager = new BeatmapManager(LocalStorage, ContextFactory, rulesets, null, audio, host, Beatmap.Default));
+
+            beatmaps = new List<BeatmapInfo>();
+
+            for (int i = 0; i < 8; ++i)
+            {
+                int beatmapId = 10 * 10 + i;
+
+                int length = RNG.Next(30000, 200000);
+                double bpm = RNG.NextSingle(80, 200);
+
+                beatmaps.Add(new BeatmapInfo
+                {
+                    Ruleset = rulesets.GetRuleset(i % 4),
+                    OnlineBeatmapID = beatmapId,
+                    Length = length,
+                    BPM = bpm,
+                    BaseDifficulty = new BeatmapDifficulty()
+                });
+            }
+
+            manager.Import(new BeatmapSetInfo
+            {
+                OnlineBeatmapSetID = 10,
+                Hash = Guid.NewGuid().ToString().ComputeMD5Hash(),
+                Metadata = new BeatmapMetadata
+                {
+                    Artist = "Some Artist",
+                    Title = "Some Beatmap",
+                    AuthorString = "Some Author"
+                },
+                Beatmaps = beatmaps,
+                DateAdded = DateTimeOffset.UtcNow
+            }).Wait();
+        }
+
+        public override void SetUpSteps()
+        {
+            base.SetUpSteps();
+
+            AddStep("reset", () =>
+            {
+                Ruleset.Value = new OsuRuleset().RulesetInfo;
+                Beatmap.SetDefault();
+                SelectedMods.SetDefault();
+            });
+
+            AddStep("create song select", () => LoadScreen(songSelect = new TestMultiplayerMatchSongSelect()));
+            AddUntilStep("wait for present", () => songSelect.IsCurrentScreen());
+        }
+
+        [Test]
+        public void TestBeatmapRevertedOnExitIfNoSelection()
+        {
+            BeatmapInfo selectedBeatmap = null;
+
+            AddStep("select beatmap",
+                () => songSelect.Carousel.SelectBeatmap(selectedBeatmap = beatmaps.Where(beatmap => beatmap.RulesetID == new OsuRuleset().LegacyID).ElementAt(1)));
+            AddUntilStep("wait for selection", () => Beatmap.Value.BeatmapInfo.Equals(selectedBeatmap));
+
+            AddStep("exit song select", () => songSelect.Exit());
+            AddAssert("beatmap reverted", () => Beatmap.IsDefault);
+        }
+
+        [Test]
+        public void TestModsRevertedOnExitIfNoSelection()
+        {
+            AddStep("change mods", () => SelectedMods.Value = new[] { new OsuModDoubleTime() });
+
+            AddStep("exit song select", () => songSelect.Exit());
+            AddAssert("mods reverted", () => SelectedMods.Value.Count == 0);
+        }
+
+        [Test]
+        public void TestRulesetRevertedOnExitIfNoSelection()
+        {
+            AddStep("change ruleset", () => Ruleset.Value = new CatchRuleset().RulesetInfo);
+
+            AddStep("exit song select", () => songSelect.Exit());
+            AddAssert("ruleset reverted", () => Ruleset.Value.Equals(new OsuRuleset().RulesetInfo));
+        }
+
+        [Test]
+        public void TestBeatmapConfirmed()
+        {
+            BeatmapInfo selectedBeatmap = null;
+
+            AddStep("change ruleset", () => Ruleset.Value = new TaikoRuleset().RulesetInfo);
+            AddStep("select beatmap",
+                () => songSelect.Carousel.SelectBeatmap(selectedBeatmap = beatmaps.First(beatmap => beatmap.RulesetID == new TaikoRuleset().LegacyID)));
+            AddUntilStep("wait for selection", () => Beatmap.Value.BeatmapInfo.Equals(selectedBeatmap));
+            AddStep("set mods", () => SelectedMods.Value = new[] { new TaikoModDoubleTime() });
+
+            AddStep("confirm selection", () => songSelect.FinaliseSelection());
+            AddStep("exit song select", () => songSelect.Exit());
+
+            AddAssert("beatmap not changed", () => Beatmap.Value.BeatmapInfo.Equals(selectedBeatmap));
+            AddAssert("ruleset not changed", () => Ruleset.Value.Equals(new TaikoRuleset().RulesetInfo));
+            AddAssert("mods not changed", () => SelectedMods.Value.Single() is TaikoModDoubleTime);
+        }
+
+        private class TestMultiplayerMatchSongSelect : MultiplayerMatchSongSelect
+        {
+            public new BeatmapCarousel Carousel => base.Carousel;
+        }
+    }
+}

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

@@ -43,6 +43,16 @@ namespace osu.Game.Tests.Visual.Multiplayer
             AddAssert("two unique panels", () => this.ChildrenOfType<ParticipantPanel>().Select(p => p.User).Distinct().Count() == 2);
         }
 
+        [Test]
+        public void TestAddNullUser()
+        {
+            AddAssert("one unique panel", () => this.ChildrenOfType<ParticipantPanel>().Select(p => p.User).Distinct().Count() == 1);
+
+            AddStep("add non-resolvable user", () => Client.AddNullUser(-3));
+
+            AddUntilStep("two unique panels", () => this.ChildrenOfType<ParticipantPanel>().Select(p => p.User).Distinct().Count() == 2);
+        }
+
         [Test]
         public void TestRemoveUser()
         {

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

@@ -143,7 +143,6 @@ namespace osu.Game.Tests.Visual.Multiplayer
                 RoomManager =
                 {
                     TimeBetweenListingPolls = { Value = 1 },
-                    TimeBetweenSelectionPolls = { Value = 1 }
                 }
             };
 

osu.Game.Tests/Visual/Online/TestSceneAccountCreationOverlay.cs

@@ -1,6 +1,7 @@
 // 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 NUnit.Framework;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -13,13 +14,12 @@ namespace osu.Game.Tests.Visual.Online
     public class TestSceneAccountCreationOverlay : OsuTestScene
     {
         private readonly Container userPanelArea;
+        private readonly AccountCreationOverlay accountCreation;
 
         private IBindable<User> localUser;
 
         public TestSceneAccountCreationOverlay()
         {
-            AccountCreationOverlay accountCreation;
-
             Children = new Drawable[]
             {
                 accountCreation = new AccountCreationOverlay(),
@@ -31,8 +31,6 @@ namespace osu.Game.Tests.Visual.Online
                     Origin = Anchor.TopRight,
                 },
             };
-
-            AddStep("show", () => accountCreation.Show());
         }
 
         [BackgroundDependencyLoader]
@@ -42,8 +40,19 @@ namespace osu.Game.Tests.Visual.Online
 
             localUser = API.LocalUser.GetBoundCopy();
             localUser.BindValueChanged(user => { userPanelArea.Child = new UserGridPanel(user.NewValue) { Width = 200 }; }, true);
+        }
 
-            AddStep("logout", API.Logout);
+        [Test]
+        public void TestOverlayVisibility()
+        {
+            AddStep("start hidden", () => accountCreation.Hide());
+            AddStep("log out", API.Logout);
+
+            AddStep("show manually", () => accountCreation.Show());
+            AddUntilStep("overlay is visible", () => accountCreation.State.Value == Visibility.Visible);
+
+            AddStep("log back in", () => API.Login("dummy", "password"));
+            AddUntilStep("overlay is hidden", () => accountCreation.State.Value == Visibility.Hidden);
         }
     }
 }

osu.Game.Tests/Visual/Online/TestSceneChangelogOverlay.cs

@@ -1,8 +1,13 @@
 // 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.Collections.Generic;
+using System.Linq;
+using Humanizer;
 using NUnit.Framework;
+using osu.Game.Online.API;
+using osu.Game.Online.API.Requests;
 using osu.Game.Online.API.Requests.Responses;
 using osu.Game.Overlays;
 using osu.Game.Overlays.Changelog;
@@ -12,13 +17,61 @@ namespace osu.Game.Tests.Visual.Online
     [TestFixture]
     public class TestSceneChangelogOverlay : OsuTestScene
     {
+        private DummyAPIAccess dummyAPI => (DummyAPIAccess)API;
+
+        private readonly Dictionary<string, APIUpdateStream> streams;
+        private readonly Dictionary<string, APIChangelogBuild> builds;
+
+        private APIChangelogBuild requestedBuild;
         private TestChangelogOverlay changelog;
 
-        protected override bool UseOnlineAPI => true;
+        public TestSceneChangelogOverlay()
+        {
+            streams = APIUpdateStream.KNOWN_STREAMS.Keys.Select((stream, id) => new APIUpdateStream
+            {
+                Id = id + 1,
+                Name = stream,
+                DisplayName = stream.Humanize(), // not quite there, but good enough.
+            }).ToDictionary(stream => stream.Name);
+
+            string version = DateTimeOffset.Now.ToString("yyyy.Mdd.0");
+            builds = APIUpdateStream.KNOWN_STREAMS.Keys.Select(stream => new APIChangelogBuild
+            {
+                Version = version,
+                DisplayVersion = version,
+                UpdateStream = streams[stream],
+                ChangelogEntries = new List<APIChangelogEntry>()
+            }).ToDictionary(build => build.UpdateStream.Name);
+
+            foreach (var stream in streams.Values)
+                stream.LatestBuild = builds[stream.Name];
+        }
 
         [SetUp]
         public void SetUp() => Schedule(() =>
         {
+            requestedBuild = null;
+
+            dummyAPI.HandleRequest = request =>
+            {
+                switch (request)
+                {
+                    case GetChangelogRequest changelogRequest:
+                        var changelogResponse = new APIChangelogIndex
+                        {
+                            Streams = streams.Values.ToList(),
+                            Builds = builds.Values.ToList()
+                        };
+                        changelogRequest.TriggerSuccess(changelogResponse);
+                        break;
+
+                    case GetChangelogBuildRequest buildRequest:
+                        if (requestedBuild != null)
+                            buildRequest.TriggerSuccess(requestedBuild);
+                        break;
+                }
+            };
+
             Child = changelog = new TestChangelogOverlay();
         });
 
@@ -41,26 +94,60 @@ namespace osu.Game.Tests.Visual.Online
         }
 
         [Test]
-        [Ignore("needs to be updated to not be so server dependent")]
         public void ShowWithBuild()
         {
-            AddStep(@"Show with Lazer 2018.712.0", () =>
+            showBuild(() => new APIChangelogBuild
             {
-                changelog.ShowBuild(new APIChangelogBuild
+                Version = "2018.712.0",
+                DisplayVersion = "2018.712.0",
+                UpdateStream = streams[OsuGameBase.CLIENT_STREAM_NAME],
+                ChangelogEntries = new List<APIChangelogEntry>
                 {
-                    Version = "2018.712.0",
+                    new APIChangelogEntry
-                    DisplayVersion = "2018.712.0",
-                    UpdateStream = new APIUpdateStream { Id = 5, Name = OsuGameBase.CLIENT_STREAM_NAME },
-                    ChangelogEntries = new List<APIChangelogEntry>
                     {
-                        new APIChangelogEntry
+                        Type = ChangelogEntryType.Fix,
+                        Category = "osu!",
+                        Title = "Fix thing",
+                        MessageHtml = "Additional info goes here.",
+                        Repository = "osu",
+                        GithubPullRequestId = 11100,
+                        GithubUser = new APIChangelogUser
                         {
-                            Category = "Test",
+                            OsuUsername = "smoogipoo",
-                            Title = "Title",
+                            UserId = 1040328
-                            MessageHtml = "Message",
                         }
+                    },
+                    new APIChangelogEntry
+                    {
+                        Type = ChangelogEntryType.Add,
+                        Category = "osu!",
+                        Title = "Add thing",
+                        Major = true,
+                        Repository = "ppy/osu-framework",
+                        GithubPullRequestId = 4444,
+                        GithubUser = new APIChangelogUser
+                        {
+                            DisplayName = "frenzibyte",
+                            GithubUrl = "https://github.com/frenzibyte"
+                        }
+                    },
+                    new APIChangelogEntry
+                    {
+                        Type = ChangelogEntryType.Misc,
+                        Category = "Code quality",
+                        Title = "Clean up thing",
+                        GithubUser = new APIChangelogUser
+                        {
+                            DisplayName = "some dude"
+                        }
+                    },
+                    new APIChangelogEntry
+                    {
+                        Type = ChangelogEntryType.Misc,
+                        Category = "Code quality",
+                        Title = "Clean up another thing"
                     }
-                });
+                }
             });
 
             AddUntilStep(@"wait for streams", () => changelog.Streams?.Count > 0);
@@ -71,35 +158,38 @@ namespace osu.Game.Tests.Visual.Online
         [Test]
         public void TestHTMLUnescaping()
         {
-            AddStep(@"Ensure HTML string unescaping", () =>
+            showBuild(() => new APIChangelogBuild
             {
-                changelog.ShowBuild(new APIChangelogBuild
+                Version = "2019.920.0",
+                DisplayVersion = "2019.920.0",
+                UpdateStream = new APIUpdateStream
                 {
-                    Version = "2019.920.0",
+                    Name = "Test",
-                    DisplayVersion = "2019.920.0",
+                    DisplayName = "Test"
-                    UpdateStream = new APIUpdateStream
+                },
+                ChangelogEntries = new List<APIChangelogEntry>
+                {
+                    new APIChangelogEntry
                     {
-                        Name = "Test",
+                        Category = "Testing HTML strings unescaping",
-                        DisplayName = "Test"
+                        Title = "Ensuring HTML strings are being unescaped",
-                    },
+                        MessageHtml = "&quot;&quot;&quot;This text should appear triple-quoted&quot;&quot;&quot;    &gt;_&lt;",
-                    ChangelogEntries = new List<APIChangelogEntry>
+                        GithubUser = new APIChangelogUser
-                    {
-                        new APIChangelogEntry
                         {
-                            Category = "Testing HTML strings unescaping",
+                            DisplayName = "Dummy",
-                            Title = "Ensuring HTML strings are being unescaped",
+                            OsuUsername = "Dummy",
-                            MessageHtml = "&quot;&quot;&quot;This text should appear triple-quoted&quot;&quot;&quot;    &gt;_&lt;",
+                        }
-                            GithubUser = new APIChangelogUser
+                    },
-                            {
+                }
-                                DisplayName = "Dummy",
-                                OsuUsername = "Dummy",
-                            }
-                        },
-                    }
-                });
             });
         }
 
+        private void showBuild(Func<APIChangelogBuild> build)
+        {
+            AddStep("set up build", () => requestedBuild = build.Invoke());
+            AddStep("show build", () => changelog.ShowBuild(requestedBuild));
+        }
+
         private class TestChangelogOverlay : ChangelogOverlay
         {
             public new List<APIUpdateStream> Streams => base.Streams;

osu.Game.Tests/Visual/Online/TestSceneCurrentlyPlayingDisplay.cs

@@ -90,11 +90,17 @@ namespace osu.Game.Tests.Visual.Online
             };
 
             protected override Task<User> ComputeValueAsync(int lookup, CancellationToken token = default)
-                => Task.FromResult(new User
+            {
+                // tests against failed lookups
+                if (lookup == 13)
+                    return Task.FromResult<User>(null);
+
+                return Task.FromResult(new User
                 {
                     Id = lookup,
                     Username = usernames[lookup % usernames.Length],
                 });
+            }
         }
     }
 }

osu.Game.Tests/osu.Game.Tests.csproj

@@ -3,7 +3,7 @@
   <ItemGroup Label="Package References">
     <PackageReference Include="Appveyor.TestLogger" Version="2.0.0" />
     <PackageReference Include="DeepEqual" Version="2.0.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
     <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.17.0" />
     <PackageReference Update="Microsoft.EntityFrameworkCore.Sqlite" Version="2.1.4" />

osu.Game.Tournament.Tests/osu.Game.Tournament.Tests.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
   <ItemGroup Label="Package References">
     <PackageReference Include="Appveyor.TestLogger" Version="2.0.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.8.3" />
     <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.17.0" />
   </ItemGroup>

osu.Game/Database/UserLookupCache.cs

@@ -5,6 +5,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Game.Online.API;
 using osu.Game.Online.API.Requests;
@@ -17,6 +18,13 @@ namespace osu.Game.Database
         [Resolved]
         private IAPIProvider api { get; set; }
 
+        /// <summary>
+        /// Perform an API lookup on the specified user, populating a <see cref="User"/> model.
+        /// </summary>
+        /// <param name="userId">The user to lookup.</param>
+        /// <param name="token">An optional cancellation token.</param>
+        /// <returns>The populated user, or null if the user does not exist or the request could not be satisfied.</returns>
+        [ItemCanBeNull]
         public Task<User> GetUserAsync(int userId, CancellationToken token = default) => GetAsync(userId, token);
 
         protected override async Task<User> ComputeValueAsync(int lookup, CancellationToken token = default)
@@ -72,6 +80,7 @@ namespace osu.Game.Database
             var request = new GetUsersRequest(userTasks.Keys.ToArray());
 
             // rather than queueing, we maintain our own single-threaded request stream.
+            // todo: we probably want retry logic here.
             api.Perform(request);
 
             // Create a new request task if there's still more users to query.
@@ -82,14 +91,19 @@ namespace osu.Game.Database
                     createNewTask();
             }
 
-            foreach (var user in request.Result.Users)
+            List<User> foundUsers = request.Result?.Users;
-            {
-                if (userTasks.TryGetValue(user.Id, out var tasks))
-                {
-                    foreach (var task in tasks)
-                        task.SetResult(user);
 
-                    userTasks.Remove(user.Id);
+            if (foundUsers != null)
+            {
+                foreach (var user in foundUsers)
+                {
+                    if (userTasks.TryGetValue(user.Id, out var tasks))
+                    {
+                        foreach (var task in tasks)
+                            task.SetResult(user);
+
+                        userTasks.Remove(user.Id);
+                    }
                 }
             }
 

osu.Game/Extensions/TaskExtensions.cs

@@ -1,7 +1,11 @@
 // 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.
 
+#nullable enable
+
+using System;
 using System.Threading.Tasks;
+using osu.Framework.Extensions.ExceptionExtensions;
 using osu.Framework.Logging;
 
 namespace osu.Game.Extensions
@@ -13,13 +17,19 @@ namespace osu.Game.Extensions
         /// Avoids unobserved exceptions from being fired.
         /// </summary>
         /// <param name="task">The task.</param>
-        /// <param name="logOnError">Whether errors should be logged as important, or silently ignored.</param>
+        /// <param name="logAsError">
-        public static void CatchUnobservedExceptions(this Task task, bool logOnError = false)
+        /// Whether errors should be logged as errors visible to users, or as debug messages.
+        /// Logging as debug will essentially silence the errors on non-release builds.
+        /// </param>
+        public static void CatchUnobservedExceptions(this Task task, bool logAsError = false)
         {
             task.ContinueWith(t =>
             {
-                if (logOnError)
+                Exception? exception = t.Exception?.AsSingular();
-                    Logger.Log($"Error running task: {t.Exception?.Message ?? "unknown"}", LoggingTarget.Runtime, LogLevel.Important);
+                if (logAsError)
+                    Logger.Error(exception, $"Error running task: {exception?.Message ?? "(unknown)"}", LoggingTarget.Runtime, true);
+                else
+                    Logger.Log($"Error running task: {exception}", LoggingTarget.Runtime, LogLevel.Debug);
             }, TaskContinuationOptions.NotOnRanToCompletion);
         }
     }

osu.Game/Online/API/APIAccess.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.Net;
 using System.Net.Http;
+using System.Net.Sockets;
 using System.Threading;
 using System.Threading.Tasks;
 using Newtonsoft.Json.Linq;
@@ -293,8 +294,21 @@ namespace osu.Game.Online.API
                 failureCount = 0;
                 return true;
             }
+            catch (HttpRequestException re)
+            {
+                log.Add($"{nameof(HttpRequestException)} while performing request {req}: {re.Message}");
+                handleFailure();
+                return false;
+            }
+            catch (SocketException se)
+            {
+                log.Add($"{nameof(SocketException)} while performing request {req}: {se.Message}");
+                handleFailure();
+                return false;
+            }
             catch (WebException we)
             {
+                log.Add($"{nameof(WebException)} while performing request {req}: {we.Message}");
                 handleWebException(we);
                 return false;
             }
@@ -312,7 +326,7 @@ namespace osu.Game.Online.API
         /// </summary>
         public IBindable<APIState> State => state;
 
-        private bool handleWebException(WebException we)
+        private void handleWebException(WebException we)
         {
             HttpStatusCode statusCode = (we.Response as HttpWebResponse)?.StatusCode
                                         ?? (we.Status == WebExceptionStatus.UnknownError ? HttpStatusCode.NotAcceptable : HttpStatusCode.RequestTimeout);
@@ -330,26 +344,24 @@ namespace osu.Game.Online.API
             {
                 case HttpStatusCode.Unauthorized:
                     Logout();
-                    return true;
+                    break;
 
                 case HttpStatusCode.RequestTimeout:
-                    failureCount++;
+                    handleFailure();
-                    log.Add($@"API failure count is now {failureCount}");
+                    break;
-
-                    if (failureCount < 3)
-                        // we might try again at an api level.
-                        return false;
-
-                    if (State.Value == APIState.Online)
-                    {
-                        state.Value = APIState.Failing;
-                        flushQueue();
-                    }
-
-                    return true;
             }
+        }
 
-            return true;
+        private void handleFailure()
+        {
+            failureCount++;
+            log.Add($@"API failure count is now {failureCount}");
+
+            if (failureCount >= 3 && State.Value == APIState.Online)
+            {
+                state.Value = APIState.Failing;
+                flushQueue();
+            }
         }
 
         public bool IsLoggedIn => localUser.Value.Id > 1;

osu.Game/Online/API/Requests/Responses/APIUpdateStream.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using System.Collections.Generic;
 using Newtonsoft.Json;
 using osu.Framework.Graphics.Colour;
 using osuTK.Graphics;
@@ -27,34 +28,16 @@ namespace osu.Game.Online.API.Requests.Responses
 
         public bool Equals(APIUpdateStream other) => Id == other?.Id;
 
-        public ColourInfo Colour
+        internal static readonly Dictionary<string, Color4> KNOWN_STREAMS = new Dictionary<string, Color4>
         {
-            get
+            ["stable40"] = new Color4(102, 204, 255, 255),
-            {
+            ["stable"] = new Color4(34, 153, 187, 255),
-                switch (Name)
+            ["beta40"] = new Color4(255, 221, 85, 255),
-                {
+            ["cuttingedge"] = new Color4(238, 170, 0, 255),
-                    case "stable40":
+            [OsuGameBase.CLIENT_STREAM_NAME] = new Color4(237, 18, 33, 255),
-                        return new Color4(102, 204, 255, 255);
+            ["web"] = new Color4(136, 102, 238, 255)
+        };
 
-                    case "stable":
+        public ColourInfo Colour => KNOWN_STREAMS.TryGetValue(Name, out var colour) ? colour : new Color4(0, 0, 0, 255);
-                        return new Color4(34, 153, 187, 255);
-
-                    case "beta40":
-                        return new Color4(255, 221, 85, 255);
-
-                    case "cuttingedge":
-                        return new Color4(238, 170, 0, 255);
-
-                    case OsuGameBase.CLIENT_STREAM_NAME:
-                        return new Color4(237, 18, 33, 255);
-
-                    case "web":
-                        return new Color4(136, 102, 238, 255);
-
-                    default:
-                        return new Color4(0, 0, 0, 255);
-                }
-            }
-        }
     }
 }

osu.Game/Online/Multiplayer/MultiplayerClient.cs

@@ -88,11 +88,12 @@ namespace osu.Game.Online.Multiplayer
             {
                 isConnected.Value = false;
 
-                if (ex != null)
+                Logger.Log(ex != null
-                {
+                    ? $"Multiplayer client lost connection: {ex}"
-                    Logger.Log($"Multiplayer client lost connection: {ex}", LoggingTarget.Network);
+                    : "Multiplayer client disconnected", LoggingTarget.Network);
+
+                if (connection != null)
                     await tryUntilConnected();
-                }
             };
 
             await tryUntilConnected();

osu.Game/Online/Multiplayer/MultiplayerRoom.cs

@@ -5,9 +5,7 @@
 
 using System;
 using System.Collections.Generic;
-using System.Threading;
 using Newtonsoft.Json;
-using osu.Framework.Allocation;
 
 namespace osu.Game.Online.Multiplayer
 {
@@ -42,35 +40,12 @@ namespace osu.Game.Online.Multiplayer
         /// </summary>
         public MultiplayerRoomUser? Host { get; set; }
 
-        private object writeLock = new object();
-
         [JsonConstructor]
         public MultiplayerRoom(in long roomId)
         {
             RoomID = roomId;
         }
 
-        private object updateLock = new object();
-
-        private ManualResetEventSlim freeForWrite = new ManualResetEventSlim(true);
-
-        /// <summary>
-        /// Request a lock on this room to perform a thread-safe update.
-        /// </summary>
-        public IDisposable LockForUpdate()
-        {
-            // ReSharper disable once InconsistentlySynchronizedField
-            freeForWrite.Wait();
-
-            lock (updateLock)
-            {
-                freeForWrite.Wait();
-                freeForWrite.Reset();
-
-                return new ValueInvokeOnDisposal<MultiplayerRoom>(this, r => freeForWrite.Set());
-            }
-        }
-
         public override string ToString() => $"RoomID:{RoomID} Host:{Host?.UserID} Users:{Users.Count} State:{State} Settings: [{Settings}]";
     }
 }

osu.Game/Online/Multiplayer/StatefulMultiplayerClient.cs

@@ -61,9 +61,9 @@ namespace osu.Game.Online.Multiplayer
         public MultiplayerRoom? Room { get; private set; }
 
         /// <summary>
-        /// The users currently in gameplay.
+        /// The users in the joined <see cref="Room"/> which are participating in the current gameplay loop.
         /// </summary>
-        public readonly BindableList<int> PlayingUsers = new BindableList<int>();
+        public readonly BindableList<int> CurrentMatchPlayingUserIds = new BindableList<int>();
 
         [Resolved]
         private UserLookupCache userLookupCache { get; set; } = null!;
@@ -84,7 +84,7 @@ namespace osu.Game.Online.Multiplayer
             IsConnected.BindValueChanged(connected =>
             {
                 // clean up local room state on server disconnect.
-                if (!connected.NewValue)
+                if (!connected.NewValue && Room != null)
                 {
                     Logger.Log("Connection to multiplayer server was lost.", LoggingTarget.Runtime, LogLevel.Important);
                     LeaveRoom().CatchUnobservedExceptions();
@@ -133,6 +133,7 @@ namespace osu.Game.Online.Multiplayer
 
                 apiRoom = null;
                 Room = null;
+                CurrentMatchPlayingUserIds.Clear();
 
                 RoomUpdated?.Invoke();
             }, false);
@@ -253,7 +254,7 @@ namespace osu.Game.Online.Multiplayer
                     return;
 
                 Room.Users.Remove(user);
-                PlayingUsers.Remove(user.UserID);
+                CurrentMatchPlayingUserIds.Remove(user.UserID);
 
                 RoomUpdated?.Invoke();
             }, false);
@@ -302,8 +303,7 @@ namespace osu.Game.Online.Multiplayer
 
                 Room.Users.Single(u => u.UserID == userId).State = state;
 
-                if (state != MultiplayerUserState.Playing)
+                updateUserPlayingState(userId, state);
-                    PlayingUsers.Remove(userId);
 
                 RoomUpdated?.Invoke();
             }, false);
@@ -337,8 +337,6 @@ namespace osu.Game.Online.Multiplayer
                 if (Room == null)
                     return;
 
-                PlayingUsers.AddRange(Room.Users.Where(u => u.State == MultiplayerUserState.Playing).Select(u => u.UserID));
-
                 MatchStarted?.Invoke();
             }, false);
 
@@ -454,5 +452,24 @@ namespace osu.Game.Online.Multiplayer
             apiRoom.Playlist.Clear(); // Clearing should be unnecessary, but here for sanity.
             apiRoom.Playlist.Add(playlistItem);
         }
+
+        /// <summary>
+        /// For the provided user ID, update whether the user is included in <see cref="CurrentMatchPlayingUserIds"/>.
+        /// </summary>
+        /// <param name="userId">The user's ID.</param>
+        /// <param name="state">The new state of the user.</param>
+        private void updateUserPlayingState(int userId, MultiplayerUserState state)
+        {
+            bool wasPlaying = CurrentMatchPlayingUserIds.Contains(userId);
+            bool isPlaying = state >= MultiplayerUserState.WaitingForLoad && state <= MultiplayerUserState.FinishedPlay;
+
+            if (isPlaying == wasPlaying)
+                return;
+
+            if (isPlaying)
+                CurrentMatchPlayingUserIds.Add(userId);
+            else
+                CurrentMatchPlayingUserIds.Remove(userId);
+        }
     }
 }

osu.Game/Overlays/AccountCreationOverlay.cs

@@ -9,6 +9,7 @@ using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Effects;
 using osu.Framework.Graphics.Shapes;
 using osu.Framework.Screens;
+using osu.Framework.Threading;
 using osu.Game.Graphics;
 using osu.Game.Graphics.Containers;
 using osu.Game.Online.API;
@@ -93,6 +94,11 @@ namespace osu.Game.Overlays
 
             if (welcomeScreen.GetChildScreen() != null)
                 welcomeScreen.MakeCurrent();
+
+            // there might be a stale scheduled hide from a previous API state change.
+            // cancel it here so that the overlay is not hidden again after one frame.
+            scheduledHide?.Cancel();
+            scheduledHide = null;
         }
 
         protected override void PopOut()
@@ -101,7 +107,9 @@ namespace osu.Game.Overlays
             this.FadeOut(100);
         }
 
-        private void apiStateChanged(ValueChangedEvent<APIState> state) => Schedule(() =>
+        private ScheduledDelegate scheduledHide;
+
+        private void apiStateChanged(ValueChangedEvent<APIState> state)
         {
             switch (state.NewValue)
             {
@@ -113,9 +121,10 @@ namespace osu.Game.Overlays
                     break;
 
                 case APIState.Online:
-                    Hide();
+                    scheduledHide?.Cancel();
+                    scheduledHide = Schedule(Hide);
                     break;
             }
-        });
+        }
     }
 }

osu.Game/Overlays/Changelog/ChangelogBuild.cs

@@ -9,14 +9,8 @@ using osu.Game.Graphics.Containers;
 using osu.Game.Online.API.Requests.Responses;
 using System;
 using System.Linq;
-using System.Text.RegularExpressions;
 using osu.Game.Graphics.Sprites;
-using osu.Game.Users;
-using osuTK.Graphics;
 using osu.Framework.Allocation;
-using System.Net;
-using osuTK;
-using osu.Framework.Extensions.Color4Extensions;
 
 namespace osu.Game.Overlays.Changelog
 {
@@ -63,126 +57,7 @@ namespace osu.Game.Overlays.Changelog
                     Margin = new MarginPadding { Top = 35, Bottom = 15 },
                 });
 
-                var fontLarge = OsuFont.GetFont(size: 16);
+                ChangelogEntries.AddRange(categoryEntries.Select(entry => new ChangelogEntry(entry)));
-                var fontMedium = OsuFont.GetFont(size: 12);
-
-                foreach (var entry in categoryEntries)
-                {
-                    var entryColour = entry.Major ? colours.YellowLight : Color4.White;
-
-                    LinkFlowContainer title;
-
-                    var titleContainer = new Container
-                    {
-                        AutoSizeAxes = Axes.Y,
-                        RelativeSizeAxes = Axes.X,
-                        Margin = new MarginPadding { Vertical = 5 },
-                        Children = new Drawable[]
-                        {
-                            new SpriteIcon
-                            {
-                                Anchor = Anchor.CentreLeft,
-                                Origin = Anchor.CentreRight,
-                                Size = new Vector2(10),
-                                Icon = entry.Type == ChangelogEntryType.Fix ? FontAwesome.Solid.Check : FontAwesome.Solid.Plus,
-                                Colour = entryColour.Opacity(0.5f),
-                                Margin = new MarginPadding { Right = 5 },
-                            },
-                            title = new LinkFlowContainer
-                            {
-                                Direction = FillDirection.Full,
-                                RelativeSizeAxes = Axes.X,
-                                AutoSizeAxes = Axes.Y,
-                                TextAnchor = Anchor.BottomLeft,
-                            }
-                        }
-                    };
-
-                    title.AddText(entry.Title, t =>
-                    {
-                        t.Font = fontLarge;
-                        t.Colour = entryColour;
-                    });
-
-                    if (!string.IsNullOrEmpty(entry.Repository))
-                    {
-                        title.AddText(" (", t =>
-                        {
-                            t.Font = fontLarge;
-                            t.Colour = entryColour;
-                        });
-                        title.AddLink($"{entry.Repository.Replace("ppy/", "")}#{entry.GithubPullRequestId}", entry.GithubUrl,
-                            creationParameters: t =>
-                            {
-                                t.Font = fontLarge;
-                                t.Colour = entryColour;
-                            });
-                        title.AddText(")", t =>
-                        {
-                            t.Font = fontLarge;
-                            t.Colour = entryColour;
-                        });
-                    }
-
-                    title.AddText("by ", t =>
-                    {
-                        t.Font = fontMedium;
-                        t.Colour = entryColour;
-                        t.Padding = new MarginPadding { Left = 10 };
-                    });
-
-                    if (entry.GithubUser != null)
-                    {
-                        if (entry.GithubUser.UserId != null)
-                        {
-                            title.AddUserLink(new User
-                            {
-                                Username = entry.GithubUser.OsuUsername,
-                                Id = entry.GithubUser.UserId.Value
-                            }, t =>
-                            {
-                                t.Font = fontMedium;
-                                t.Colour = entryColour;
-                            });
-                        }
-                        else if (entry.GithubUser.GithubUrl != null)
-                        {
-                            title.AddLink(entry.GithubUser.DisplayName, entry.GithubUser.GithubUrl, t =>
-                            {
-                                t.Font = fontMedium;
-                                t.Colour = entryColour;
-                            });
-                        }
-                        else
-                        {
-                            title.AddText(entry.GithubUser.DisplayName, t =>
-                            {
-                                t.Font = fontMedium;
-                                t.Colour = entryColour;
-                            });
-                        }
-                    }
-
-                    ChangelogEntries.Add(titleContainer);
-
-                    if (!string.IsNullOrEmpty(entry.MessageHtml))
-                    {
-                        var message = new TextFlowContainer
-                        {
-                            AutoSizeAxes = Axes.Y,
-                            RelativeSizeAxes = Axes.X,
-                        };
-
-                        // todo: use markdown parsing once API returns markdown
-                        message.AddText(WebUtility.HtmlDecode(Regex.Replace(entry.MessageHtml, @"<(.|\n)*?>", string.Empty)), t =>
-                        {
-                            t.Font = fontMedium;
-                            t.Colour = colourProvider.Foreground1;
-                        });
-
-                        ChangelogEntries.Add(message);
-                    }
-                }
             }
         }
 

osu.Game/Overlays/Changelog/ChangelogEntry.cs

@@ -0,0 +1,202 @@
+// 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.Net;
+using System.Text.RegularExpressions;
+using osu.Framework.Allocation;
+using osu.Framework.Extensions.Color4Extensions;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Containers;
+using osu.Game.Online.API.Requests.Responses;
+using osu.Game.Users;
+using osuTK;
+using osuTK.Graphics;
+
+namespace osu.Game.Overlays.Changelog
+{
+    public class ChangelogEntry : FillFlowContainer
+    {
+        private readonly APIChangelogEntry entry;
+
+        [Resolved]
+        private OsuColour colours { get; set; }
+
+        [Resolved]
+        private OverlayColourProvider colourProvider { get; set; }
+
+        private FontUsage fontLarge;
+        private FontUsage fontMedium;
+
+        public ChangelogEntry(APIChangelogEntry entry)
+        {
+            this.entry = entry;
+
+            RelativeSizeAxes = Axes.X;
+            AutoSizeAxes = Axes.Y;
+            Direction = FillDirection.Vertical;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            fontLarge = OsuFont.GetFont(size: 16);
+            fontMedium = OsuFont.GetFont(size: 12);
+
+            Children = new[]
+            {
+                createTitle(),
+                createMessage()
+            };
+        }
+
+        private Drawable createTitle()
+        {
+            var entryColour = entry.Major ? colours.YellowLight : Color4.White;
+
+            LinkFlowContainer title;
+
+            var titleContainer = new Container
+            {
+                AutoSizeAxes = Axes.Y,
+                RelativeSizeAxes = Axes.X,
+                Margin = new MarginPadding { Vertical = 5 },
+                Children = new Drawable[]
+                {
+                    new SpriteIcon
+                    {
+                        Anchor = Anchor.CentreLeft,
+                        Origin = Anchor.CentreRight,
+                        Size = new Vector2(10),
+                        Icon = getIconForChangelogEntry(entry.Type),
+                        Colour = entryColour.Opacity(0.5f),
+                        Margin = new MarginPadding { Right = 5 },
+                    },
+                    title = new LinkFlowContainer
+                    {
+                        Direction = FillDirection.Full,
+                        RelativeSizeAxes = Axes.X,
+                        AutoSizeAxes = Axes.Y,
+                        TextAnchor = Anchor.BottomLeft,
+                    }
+                }
+            };
+
+            title.AddText(entry.Title, t =>
+            {
+                t.Font = fontLarge;
+                t.Colour = entryColour;
+            });
+
+            if (!string.IsNullOrEmpty(entry.Repository))
+                addRepositoryReference(title, entryColour);
+
+            if (entry.GithubUser != null)
+                addGithubAuthorReference(title, entryColour);
+
+            return titleContainer;
+        }
+
+        private void addRepositoryReference(LinkFlowContainer title, Color4 entryColour)
+        {
+            title.AddText(" (", t =>
+            {
+                t.Font = fontLarge;
+                t.Colour = entryColour;
+            });
+            title.AddLink($"{entry.Repository.Replace("ppy/", "")}#{entry.GithubPullRequestId}", entry.GithubUrl,
+                t =>
+                {
+                    t.Font = fontLarge;
+                    t.Colour = entryColour;
+                });
+            title.AddText(")", t =>
+            {
+                t.Font = fontLarge;
+                t.Colour = entryColour;
+            });
+        }
+
+        private void addGithubAuthorReference(LinkFlowContainer title, Color4 entryColour)
+        {
+            title.AddText("by ", t =>
+            {
+                t.Font = fontMedium;
+                t.Colour = entryColour;
+                t.Padding = new MarginPadding { Left = 10 };
+            });
+
+            if (entry.GithubUser.UserId != null)
+            {
+                title.AddUserLink(new User
+                {
+                    Username = entry.GithubUser.OsuUsername,
+                    Id = entry.GithubUser.UserId.Value
+                }, t =>
+                {
+                    t.Font = fontMedium;
+                    t.Colour = entryColour;
+                });
+            }
+            else if (entry.GithubUser.GithubUrl != null)
+            {
+                title.AddLink(entry.GithubUser.DisplayName, entry.GithubUser.GithubUrl, t =>
+                {
+                    t.Font = fontMedium;
+                    t.Colour = entryColour;
+                });
+            }
+            else
+            {
+                title.AddText(entry.GithubUser.DisplayName, t =>
+                {
+                    t.Font = fontMedium;
+                    t.Colour = entryColour;
+                });
+            }
+        }
+
+        private Drawable createMessage()
+        {
+            if (string.IsNullOrEmpty(entry.MessageHtml))
+                return Empty();
+
+            var message = new TextFlowContainer
+            {
+                AutoSizeAxes = Axes.Y,
+                RelativeSizeAxes = Axes.X,
+            };
+
+            // todo: use markdown parsing once API returns markdown
+            message.AddText(WebUtility.HtmlDecode(Regex.Replace(entry.MessageHtml, @"<(.|\n)*?>", string.Empty)), t =>
+            {
+                t.Font = fontMedium;
+                t.Colour = colourProvider.Foreground1;
+            });
+
+            return message;
+        }
+
+        private static IconUsage getIconForChangelogEntry(ChangelogEntryType entryType)
+        {
+            // compare: https://github.com/ppy/osu-web/blob/master/resources/assets/coffee/react/_components/changelog-entry.coffee#L8-L11
+            switch (entryType)
+            {
+                case ChangelogEntryType.Add:
+                    return FontAwesome.Solid.Plus;
+
+                case ChangelogEntryType.Fix:
+                    return FontAwesome.Solid.Check;
+
+                case ChangelogEntryType.Misc:
+                    return FontAwesome.Regular.Circle;
+
+                default:
+                    throw new ArgumentOutOfRangeException(nameof(entryType), $"Unrecognised entry type {entryType}");
+            }
+        }
+    }
+}

osu.Game/Overlays/Changelog/ChangelogUpdateStreamControl.cs

@@ -7,6 +7,11 @@ namespace osu.Game.Overlays.Changelog
 {
     public class ChangelogUpdateStreamControl : OverlayStreamControl<APIUpdateStream>
     {
+        public ChangelogUpdateStreamControl()
+        {
+            SelectFirstTabByDefault = false;
+        }
+
         protected override OverlayStreamItem<APIUpdateStream> CreateStreamItem(APIUpdateStream value) => new ChangelogUpdateStreamItem(value);
     }
 }

osu.Game/PerformFromMenuRunner.cs

@@ -73,15 +73,19 @@ namespace osu.Game
             // find closest valid target
             IScreen current = getCurrentScreen();
 
+            if (current == null)
+                return;
+
             // a dialog may be blocking the execution for now.
             if (checkForDialog(current)) return;
 
             game?.CloseAllOverlays(false);
 
             // we may already be at the target screen type.
-            if (validScreens.Contains(getCurrentScreen().GetType()) && !beatmap.Disabled)
+            if (validScreens.Contains(current.GetType()) && !beatmap.Disabled)
             {
-                complete();
+                finalAction(current);
+                Cancel();
                 return;
             }
 
@@ -135,11 +139,5 @@ namespace osu.Game
             lastEncounteredDialogScreen = current;
             return true;
         }
-
-        private void complete()
-        {
-            finalAction(getCurrentScreen());
-            Cancel();
-        }
     }
 }

osu.Game/Screens/Menu/ButtonSystem.cs

@@ -156,11 +156,11 @@ namespace osu.Game.Screens.Menu
 
         private void onMultiplayer()
         {
-            if (!api.IsLoggedIn)
+            if (api.State.Value != APIState.Online)
             {
                 notifications?.Post(new SimpleNotification
                 {
-                    Text = "You gotta be logged in to multi 'yo!",
+                    Text = "You gotta be online to multi 'yo!",
                     Icon = FontAwesome.Solid.Globe,
                     Activated = () =>
                     {
@@ -177,11 +177,11 @@ namespace osu.Game.Screens.Menu
 
         private void onPlaylists()
         {
-            if (!api.IsLoggedIn)
+            if (api.State.Value != APIState.Online)
             {
                 notifications?.Post(new SimpleNotification
                 {
-                    Text = "You gotta be logged in to multi 'yo!",
+                    Text = "You gotta be online to view playlists 'yo!",
                     Icon = FontAwesome.Solid.Globe,
                     Activated = () =>
                     {

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

@@ -33,7 +33,6 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
             if (!this.IsCurrentScreen())
             {
                 multiplayerRoomManager.TimeBetweenListingPolls.Value = 0;
-                multiplayerRoomManager.TimeBetweenSelectionPolls.Value = 0;
             }
             else
             {
@@ -41,18 +40,16 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
                 {
                     case LoungeSubScreen _:
                         multiplayerRoomManager.TimeBetweenListingPolls.Value = isIdle ? 120000 : 15000;
-                        multiplayerRoomManager.TimeBetweenSelectionPolls.Value = isIdle ? 120000 : 15000;
                         break;
 
                     // Don't poll inside the match or anywhere else.
                     default:
                         multiplayerRoomManager.TimeBetweenListingPolls.Value = 0;
-                        multiplayerRoomManager.TimeBetweenSelectionPolls.Value = 0;
                         break;
                 }
             }
 
-            Logger.Log($"Polling adjusted (listing: {multiplayerRoomManager.TimeBetweenListingPolls.Value}, selection: {multiplayerRoomManager.TimeBetweenSelectionPolls.Value})");
+            Logger.Log($"Polling adjusted (listing: {multiplayerRoomManager.TimeBetweenListingPolls.Value})");
         }
 
         protected override Room CreateNewRoom()

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

@@ -1,6 +1,7 @@
 // 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.Collections.Generic;
 using System.Linq;
 using Humanizer;
 using osu.Framework.Allocation;
@@ -8,9 +9,12 @@ using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Logging;
 using osu.Framework.Screens;
+using osu.Game.Beatmaps;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Online.Multiplayer;
 using osu.Game.Online.Rooms;
+using osu.Game.Rulesets;
+using osu.Game.Rulesets.Mods;
 using osu.Game.Screens.Select;
 
 namespace osu.Game.Screens.OnlinePlay.Multiplayer
@@ -29,6 +33,12 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
 
         private LoadingLayer loadingLayer;
 
+        private WorkingBeatmap initialBeatmap;
+        private RulesetInfo initialRuleset;
+        private IReadOnlyList<Mod> initialMods;
+
+        private bool itemSelected;
+
         public MultiplayerMatchSongSelect()
         {
             Padding = new MarginPadding { Horizontal = HORIZONTAL_OVERFLOW_PADDING };
@@ -38,10 +48,14 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         private void load()
         {
             AddInternal(loadingLayer = new LoadingLayer(Carousel));
+            initialBeatmap = Beatmap.Value;
+            initialRuleset = Ruleset.Value;
+            initialMods = Mods.Value.ToList();
         }
 
         protected override bool OnStart()
         {
+            itemSelected = true;
             var item = new PlaylistItem();
 
             item.Beatmap.Value = Beatmap.Value.BeatmapInfo;
@@ -82,6 +96,18 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
             return true;
         }
 
+        public override bool OnExiting(IScreen next)
+        {
+            if (!itemSelected)
+            {
+                Beatmap.Value = initialBeatmap;
+                Ruleset.Value = initialRuleset;
+                Mods.Value = initialMods;
+            }
+
+            return base.OnExiting(next);
+        }
+
         protected override BeatmapDetailArea CreateBeatmapDetailArea() => new PlayBeatmapDetailArea();
     }
 }

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

@@ -200,7 +200,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         {
             Debug.Assert(client.Room != null);
 
-            int[] userIds = client.Room.Users.Where(u => u.State >= MultiplayerUserState.WaitingForLoad).Select(u => u.UserID).ToArray();
+            int[] userIds = client.CurrentMatchPlayingUserIds.ToArray();
 
             StartPlay(() => new MultiplayerPlayer(SelectedItem.Value, userIds));
         }

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

@@ -23,7 +23,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         private StatefulMultiplayerClient multiplayerClient { get; set; }
 
         public readonly Bindable<double> TimeBetweenListingPolls = new Bindable<double>();
-        public readonly Bindable<double> TimeBetweenSelectionPolls = new Bindable<double>();
+
         private readonly IBindable<bool> isConnected = new Bindable<bool>();
         private readonly Bindable<bool> allowPolling = new Bindable<bool>();
 
@@ -119,11 +119,6 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
                 TimeBetweenPolls = { BindTarget = TimeBetweenListingPolls },
                 AllowPolling = { BindTarget = allowPolling }
             },
-            new MultiplayerSelectionPollingComponent
-            {
-                TimeBetweenPolls = { BindTarget = TimeBetweenSelectionPolls },
-                AllowPolling = { BindTarget = allowPolling }
-            }
         };
 
         private class MultiplayerListingPollingComponent : ListingPollingComponent
@@ -146,26 +141,5 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
 
             protected override Task Poll() => !AllowPolling.Value ? Task.CompletedTask : base.Poll();
         }
-
-        private class MultiplayerSelectionPollingComponent : SelectionPollingComponent
-        {
-            public readonly IBindable<bool> AllowPolling = new Bindable<bool>();
-
-            protected override void LoadComplete()
-            {
-                base.LoadComplete();
-
-                AllowPolling.BindValueChanged(allowPolling =>
-                {
-                    if (!allowPolling.NewValue)
-                        return;
-
-                    if (IsLoaded)
-                        PollImmediately();
-                });
-            }
-
-            protected override Task Poll() => !AllowPolling.Value ? Task.CompletedTask : base.Poll();
-        }
     }
 }

osu.Game/Screens/OnlinePlay/Multiplayer/Participants/ParticipantPanel.cs

@@ -1,7 +1,6 @@
 // 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.Diagnostics;
 using osu.Framework.Allocation;
 using osu.Framework.Extensions.Color4Extensions;
 using osu.Framework.Graphics;
@@ -45,7 +44,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Participants
         [BackgroundDependencyLoader]
         private void load()
         {
-            Debug.Assert(User.User != null);
+            var user = User.User;
 
             var backgroundColour = Color4Extensions.FromHex("#33413C");
 
@@ -82,7 +81,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Participants
                                 Origin = Anchor.CentreRight,
                                 RelativeSizeAxes = Axes.Both,
                                 Width = 0.75f,
-                                User = User.User,
+                                User = user,
                                 Colour = ColourInfo.GradientHorizontal(Color4.White.Opacity(0), Color4.White.Opacity(0.25f))
                             },
                             new FillFlowContainer
@@ -98,28 +97,28 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Participants
                                         Origin = Anchor.CentreLeft,
                                         RelativeSizeAxes = Axes.Both,
                                         FillMode = FillMode.Fit,
-                                        User = User.User
+                                        User = user
                                     },
                                     new UpdateableFlag
                                     {
                                         Anchor = Anchor.CentreLeft,
                                         Origin = Anchor.CentreLeft,
                                         Size = new Vector2(30, 20),
-                                        Country = User.User.Country
+                                        Country = user?.Country
                                     },
                                     new OsuSpriteText
                                     {
                                         Anchor = Anchor.CentreLeft,
                                         Origin = Anchor.CentreLeft,
                                         Font = OsuFont.GetFont(weight: FontWeight.Bold, size: 18),
-                                        Text = User.User.Username
+                                        Text = user?.Username
                                     },
                                     new OsuSpriteText
                                     {
                                         Anchor = Anchor.CentreLeft,
                                         Origin = Anchor.CentreLeft,
                                         Font = OsuFont.GetFont(size: 14),
-                                        Text = User.User.CurrentModeRank != null ? $"#{User.User.CurrentModeRank}" : string.Empty
+                                        Text = user?.CurrentModeRank != null ? $"#{user.CurrentModeRank}" : string.Empty
                                     }
                                 }
                             },

osu.Game/Screens/OnlinePlay/OnlinePlayScreen.cs

@@ -8,6 +8,7 @@ using osu.Framework.Graphics;
 using osu.Framework.Graphics.Colour;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
+using osu.Framework.Logging;
 using osu.Framework.Screens;
 using osu.Game.Beatmaps.Drawables;
 using osu.Game.Graphics.Containers;
@@ -165,7 +166,10 @@ namespace osu.Game.Screens.OnlinePlay
         private void onlineStateChanged(ValueChangedEvent<APIState> state) => Schedule(() =>
         {
             if (state.NewValue != APIState.Online)
+            {
+                Logger.Log("API connection was lost, can't continue with online play", LoggingTarget.Network, LogLevel.Important);
                 Schedule(forcefullyExit);
+            }
         });
 
         protected override void LoadComplete()

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

@@ -3,6 +3,7 @@
 
 using System;
 using System.Linq;
+using JetBrains.Annotations;
 using osu.Framework.Caching;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
@@ -42,7 +43,7 @@ namespace osu.Game.Screens.Play.HUD
         /// Whether the player should be tracked on the leaderboard.
         /// Set to <c>true</c> for the local player or a player whose replay is currently being played.
         /// </param>
-        public ILeaderboardScore AddPlayer(User user, bool isTracked)
+        public ILeaderboardScore AddPlayer([CanBeNull] User user, bool isTracked)
         {
             var drawable = new GameplayLeaderboardScore(user, isTracked)
             {

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

@@ -1,6 +1,7 @@
 // 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 JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Extensions.Color4Extensions;
@@ -34,6 +35,7 @@ namespace osu.Game.Screens.Play.HUD
         public BindableDouble TotalScore { get; } = new BindableDouble();
         public BindableDouble Accuracy { get; } = new BindableDouble(1);
         public BindableInt Combo { get; } = new BindableInt();
+        public BindableBool HasQuit { get; } = new BindableBool();
 
         private int? scorePosition;
 
@@ -51,10 +53,11 @@ namespace osu.Game.Screens.Play.HUD
                     positionText.Text = $"#{scorePosition.Value.FormatRank()}";
 
                 positionText.FadeTo(scorePosition.HasValue ? 1 : 0);
-                updateColour();
+                updateState();
             }
         }
 
+        [CanBeNull]
         public User User { get; }
 
         private readonly bool trackedPlayer;
@@ -67,7 +70,7 @@ namespace osu.Game.Screens.Play.HUD
         /// </summary>
         /// <param name="user">The score's player.</param>
         /// <param name="trackedPlayer">Whether the player is the local user or a replay player.</param>
-        public GameplayLeaderboardScore(User user, bool trackedPlayer)
+        public GameplayLeaderboardScore([CanBeNull] User user, bool trackedPlayer)
         {
             User = user;
             this.trackedPlayer = trackedPlayer;
@@ -179,7 +182,7 @@ namespace osu.Game.Screens.Play.HUD
                                                 Origin = Anchor.CentreLeft,
                                                 Colour = Color4.White,
                                                 Font = OsuFont.Torus.With(size: 14, weight: FontWeight.SemiBold),
-                                                Text = User.Username,
+                                                Text = User?.Username,
                                                 Truncate = true,
                                                 Shadow = false,
                                             }
@@ -230,20 +233,31 @@ namespace osu.Game.Screens.Play.HUD
             TotalScore.BindValueChanged(v => scoreText.Text = v.NewValue.ToString("N0"), true);
             Accuracy.BindValueChanged(v => accuracyText.Text = v.NewValue.FormatAccuracy(), true);
             Combo.BindValueChanged(v => comboText.Text = $"{v.NewValue}x", true);
+            HasQuit.BindValueChanged(_ => updateState());
         }
 
         protected override void LoadComplete()
         {
             base.LoadComplete();
 
-            updateColour();
+            updateState();
             FinishTransforms(true);
         }
 
         private const double panel_transition_duration = 500;
 
-        private void updateColour()
+        private void updateState()
         {
+            if (HasQuit.Value)
+            {
+                // we will probably want to display this in a better way once we have a design.
+                // and also show states other than quit.
+                mainFillContainer.ResizeWidthTo(regular_width, panel_transition_duration, Easing.OutElastic);
+                panelColour = Color4.Gray;
+                textColour = Color4.White;
+                return;
+            }
+
             if (scorePosition == 1)
             {
                 mainFillContainer.ResizeWidthTo(EXTENDED_WIDTH, panel_transition_duration, Easing.OutElastic);

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

@@ -10,5 +10,7 @@ namespace osu.Game.Screens.Play.HUD
         BindableDouble TotalScore { get; }
         BindableDouble Accuracy { get; }
         BindableInt Combo { get; }
+
+        BindableBool HasQuit { get; }
     }
 }

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

@@ -2,12 +2,15 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Collections.Generic;
+using System.Collections.Specialized;
+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 +21,21 @@ 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>
@@ -33,43 +47,68 @@ 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);
+                var leaderboardScore = AddPlayer(resolvedUser, resolvedUser?.Id == api.LocalUser.Value.Id);
 
                 ((IBindable<double>)leaderboardScore.Accuracy).BindTo(trackedUser.Accuracy);
                 ((IBindable<double>)leaderboardScore.TotalScore).BindTo(trackedUser.Score);
                 ((IBindable<int>)leaderboardScore.Combo).BindTo(trackedUser.CurrentCombo);
+                ((IBindable<bool>)leaderboardScore.HasQuit).BindTo(trackedUser.UserQuit);
             }
 
             scoringMode = config.GetBindable<ScoringMode>(OsuSetting.ScoreDisplayMode);
             scoringMode.BindValueChanged(updateAllScores, true);
         }
 
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            // BindableList handles binding in a really bad way (Clear then AddRange) so we need to do this manually..
+            foreach (int userId in playingUsers)
+            {
+                if (!multiplayerClient.CurrentMatchPlayingUserIds.Contains(userId))
+                    usersChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, new[] { userId }));
+            }
+
+            playingUsers.BindTo(multiplayerClient.CurrentMatchPlayingUserIds);
+            playingUsers.BindCollectionChanged(usersChanged);
+        }
+
+        private void usersChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            switch (e.Action)
+            {
+                case NotifyCollectionChangedAction.Remove:
+                    foreach (var userId in e.OldItems.OfType<int>())
+                    {
+                        streamingClient.StopWatchingUser(userId);
+
+                        if (userScores.TryGetValue(userId, out var trackedData))
+                            trackedData.MarkUserQuit();
+                    }
+
+                    break;
+            }
+        }
+
         private void updateAllScores(ValueChangedEvent<ScoringMode> mode)
         {
             foreach (var trackedData in userScores.Values)
@@ -91,7 +130,7 @@ namespace osu.Game.Screens.Play.HUD
 
             if (streamingClient != null)
             {
-                foreach (var user in userIds)
+                foreach (var user in playingUsers)
                 {
                     streamingClient.StopWatchingUser(user);
                 }
@@ -114,9 +153,15 @@ namespace osu.Game.Screens.Play.HUD
 
             private readonly BindableInt currentCombo = new BindableInt();
 
+            public IBindable<bool> UserQuit => userQuit;
+
+            private readonly BindableBool userQuit = new BindableBool();
+
             [CanBeNull]
             public FrameHeader LastHeader;
 
+            public void MarkUserQuit() => userQuit.Value = true;
+
             public void UpdateScore(ScoreProcessor processor, ScoringMode mode)
             {
                 if (LastHeader == null)

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

@@ -5,10 +5,9 @@ using System;
 using osu.Framework.Bindables;
 using osu.Game.Rulesets.Judgements;
 using osu.Game.Rulesets.Scoring;
-using osu.Game.Screens.Play.HUD;
 using osu.Game.Skinning;
 
-namespace osu.Game.Screens.Play
+namespace osu.Game.Screens.Play.HUD
 {
     public class SkinnableHealthDisplay : SkinnableDrawable, IHealthDisplay
     {

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

@@ -28,6 +28,8 @@ namespace osu.Game.Tests.Visual.Multiplayer
 
         public void AddUser(User user) => ((IMultiplayerClient)this).UserJoined(new MultiplayerRoomUser(user.Id) { User = user });
 
+        public void AddNullUser(int userId) => ((IMultiplayerClient)this).UserJoined(new MultiplayerRoomUser(userId));
+
         public void RemoveUser(User user)
         {
             Debug.Assert(Room != null);

osu.Game/osu.Game.csproj

@@ -21,12 +21,12 @@
     <PackageReference Include="Dapper" Version="2.0.78" />
     <PackageReference Include="DiffPlex" Version="1.6.3" />
     <PackageReference Include="Humanizer" Version="2.8.26" />
-    <PackageReference Include="Microsoft.AspNetCore.SignalR.Client" Version="3.1.9" />
+    <PackageReference Include="Microsoft.AspNetCore.SignalR.Client" Version="3.1.10" />
-    <PackageReference Include="Microsoft.AspNetCore.SignalR.Protocols.NewtonsoftJson" Version="3.1.9" />
+    <PackageReference Include="Microsoft.AspNetCore.SignalR.Protocols.NewtonsoftJson" Version="3.1.10" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="2.2.6" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite.Core" Version="2.2.6" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
-    <PackageReference Include="ppy.osu.Framework" Version="2020.1222.0" />
+    <PackageReference Include="ppy.osu.Framework" Version="2020.1229.0" />
     <PackageReference Include="ppy.osu.Game.Resources" Version="2020.1202.0" />
     <PackageReference Include="Sentry" Version="2.1.8" />
     <PackageReference Include="SharpCompress" Version="0.26.0" />

osu.iOS.props

@@ -70,7 +70,7 @@
     <Reference Include="System.Net.Http" />
   </ItemGroup>
   <ItemGroup Label="Package References">
-    <PackageReference Include="ppy.osu.Framework.iOS" Version="2020.1222.0" />
+    <PackageReference Include="ppy.osu.Framework.iOS" Version="2020.1229.0" />
     <PackageReference Include="ppy.osu.Game.Resources" Version="2020.1202.0" />
   </ItemGroup>
   <!-- See https://github.com/dotnet/runtime/issues/35988 (can be removed after Xamarin uses net5.0 / net6.0) -->
@@ -88,7 +88,7 @@
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="2.2.6" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite.Core" Version="2.2.6" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
-    <PackageReference Include="ppy.osu.Framework" Version="2020.1222.0" />
+    <PackageReference Include="ppy.osu.Framework" Version="2020.1229.0" />
     <PackageReference Include="SharpCompress" Version="0.26.0" />
     <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="SharpRaven" Version="2.4.0" />

osu.sln.DotSettings

@@ -106,6 +106,7 @@
 	<s:String x:Key="/Default/CodeInspection/Highlighting/InspectionSeverities/=MergeCastWithTypeCheck/@EntryIndexedValue">HINT</s:String>
 	<s:String x:Key="/Default/CodeInspection/Highlighting/InspectionSeverities/=MergeConditionalExpression/@EntryIndexedValue">WARNING</s:String>
 	<s:String x:Key="/Default/CodeInspection/Highlighting/InspectionSeverities/=MergeSequentialChecks/@EntryIndexedValue">WARNING</s:String>
+	<s:String x:Key="/Default/CodeInspection/Highlighting/InspectionSeverities/=MergeSequentialPatterns/@EntryIndexedValue">DO_NOT_SHOW</s:String>
 	<s:String x:Key="/Default/CodeInspection/Highlighting/InspectionSeverities/=MethodHasAsyncOverload/@EntryIndexedValue">WARNING</s:String>
 	<s:String x:Key="/Default/CodeInspection/Highlighting/InspectionSeverities/=MethodHasAsyncOverloadWithCancellation/@EntryIndexedValue">WARNING</s:String>
 	<s:String x:Key="/Default/CodeInspection/Highlighting/InspectionSeverities/=MethodSupportsCancellation/@EntryIndexedValue">WARNING</s:String>