Pass in master clock instead of slave clock

osu.Game.Tests/OnlinePlay/TestSceneCatchUpSyncManager.cs

@@ -168,6 +168,11 @@ namespace osu.Game.Tests.OnlinePlay
 
             public bool IsCatchingUp { get; set; }
 
+            public IFrameBasedClock Source
+            {
+                set => throw new NotImplementedException();
+            }
+
             public readonly int Id;
 
             public TestSpectatorPlayerClock(int id)

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

@@ -79,7 +79,10 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
             };
 
             for (int i = 0; i < UserIds.Length; i++)
-                grid.Add(instances[i] = new PlayerArea(UserIds[i], new CatchUpSpectatorPlayerClock(masterClockContainer.GameplayClock)));
+            {
+                grid.Add(instances[i] = new PlayerArea(UserIds[i], masterClockContainer.GameplayClock));
+                syncManager.AddPlayerClock(instances[i].GameplayClock);
+            }
 
             // Todo: This is not quite correct - it should be per-user to adjust for other mod combinations.
             var playableBeatmap = Beatmap.Value.GetPlayableBeatmap(Ruleset.Value);

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

@@ -9,6 +9,7 @@ using osu.Framework.Audio;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Timing;
 using osu.Game.Beatmaps;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Rulesets;
@@ -38,7 +39,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         /// The <see cref="ISpectatorPlayerClock"/> used to control the gameplay running state of a loaded <see cref="Player"/>.
         /// </summary>
         [NotNull]
-        public readonly ISpectatorPlayerClock GameplayClock;
+        public readonly ISpectatorPlayerClock GameplayClock = new CatchUpSpectatorPlayerClock();
 
         /// <summary>
         /// The currently-loaded score.
@@ -54,10 +55,9 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         private readonly AudioContainer audioContainer;
         private OsuScreenStack stack;
 
-        public PlayerArea(int userId, [NotNull] ISpectatorPlayerClock gameplayClock)
+        public PlayerArea(int userId, IFrameBasedClock masterClock)
         {
             UserId = userId;
-            GameplayClock = gameplayClock;
 
             RelativeSizeAxes = Axes.Both;
             Masking = true;
@@ -71,6 +71,8 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
                 },
                 loadingLayer = new LoadingLayer(true) { State = { Value = Visibility.Visible } }
             };
+
+            GameplayClock.Source = masterClock;
         }
 
         public void LoadScore([NotNull] Score score)

osu.Game/Screens/OnlinePlay/Multiplayer/Spectate/Sync/CatchUpSpectatorPlayerClock.cs

@@ -1,6 +1,8 @@
 // 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 osu.Framework.Bindables;
 using osu.Framework.Timing;
@@ -17,12 +19,10 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate.Sync
         /// </summary>
         public const double CATCHUP_RATE = 2;
 
-        private readonly IFrameBasedClock masterClock;
+        /// <summary>
-
+        /// The source clock.
-        public CatchUpSpectatorPlayerClock(IFrameBasedClock masterClock)
+        /// </summary>
-        {
+        public IFrameBasedClock? Source { get; set; }
-            this.masterClock = masterClock;
-        }
 
         public double CurrentTime { get; private set; }
 
@@ -52,19 +52,22 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate.Sync
 
         public void ProcessFrame()
         {
-            masterClock.ProcessFrame();
-
             ElapsedFrameTime = 0;
             FramesPerSecond = 0;
 
+            if (Source == null)
+                return;
+
+            Source.ProcessFrame();
+
             if (IsRunning)
             {
-                double elapsedSource = masterClock.ElapsedFrameTime;
+                double elapsedSource = Source.ElapsedFrameTime;
                 double elapsed = elapsedSource * Rate;
 
                 CurrentTime += elapsed;
                 ElapsedFrameTime = elapsed;
-                FramesPerSecond = masterClock.FramesPerSecond;
+                FramesPerSecond = Source.FramesPerSecond;
             }
         }
 

osu.Game/Screens/OnlinePlay/Multiplayer/Spectate/Sync/ISpectatorPlayerClock.cs

@@ -20,5 +20,10 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate.Sync
         /// Whether this clock is resynchronising to the master clock.
         /// </summary>
         bool IsCatchingUp { get; set; }
+
+        /// <summary>
+        /// The source clock
+        /// </summary>
+        IFrameBasedClock Source { set; }
     }
 }