Forcefully exit multiplayer if API loses connectivity

osu.Game/Screens/Multi/Multiplayer.cs

@@ -21,7 +21,7 @@ using osuTK;
 namespace osu.Game.Screens.Multi
 {
     [Cached]
-    public class Multiplayer : OsuScreen
+    public class Multiplayer : OsuScreen, IOnlineComponent
     {
         private readonly MultiplayerWaveContainer waves;
 
@@ -98,6 +98,30 @@ namespace osu.Game.Screens.Multi
             loungeSubScreen.Exited += _ => Exit();
         }
 
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            api.Register(this);
+        }
+
+        public void APIStateChanged(APIAccess api, APIState state)
+        {
+            if (state != APIState.Online)
+                forcefullyExit();
+        }
+
+        private void forcefullyExit()
+        {
+            // This is temporary since we don't currently have a way to force screens to be exited
+            if (IsCurrentScreen)
+                Exit();
+            else
+            {
+                MakeCurrent();
+                Schedule(forcefullyExit);
+            }
+        }
+
         protected override void OnEntering(Screen last)
         {
             Content.FadeIn();
@@ -196,6 +220,12 @@ namespace osu.Game.Screens.Multi
             currentScreen = (OsuScreen)newScreen;
         }
 
+        protected override void Dispose(bool isDisposing)
+        {
+            base.Dispose(isDisposing);
+            api?.Unregister(this);
+        }
+
         private class MultiplayerWaveContainer : WaveContainer
         {
             protected override bool StartHidden => true;