From 55372496d117463c11e8e79043e0f1f1c6580956 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Sun, 9 Sep 2018 22:37:15 +0900
Subject: [PATCH] Fix thread-safety of queued events list in
 ArchiveModelManager

---
 osu.Game/Database/ArchiveModelManager.cs | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/osu.Game/Database/ArchiveModelManager.cs b/osu.Game/Database/ArchiveModelManager.cs
index e9fe943f15..f4f169f27c 100644
--- a/osu.Game/Database/ArchiveModelManager.cs
+++ b/osu.Game/Database/ArchiveModelManager.cs
@@ -59,7 +59,7 @@ public abstract class ArchiveModelManager<TModel, TFileModel> : ICanAcceptFiles
         // ReSharper disable once NotAccessedField.Local (we should keep a reference to this so it is not finalised)
         private ArchiveImportIPCChannel ipc;
 
-        private readonly List<Action> cachedEvents = new List<Action>();
+        private readonly List<Action> queuedEvents = new List<Action>();
 
         /// <summary>
         /// Allows delaying of outwards events until an operation is confirmed (at a database level).
@@ -77,20 +77,26 @@ public abstract class ArchiveModelManager<TModel, TFileModel> : ICanAcceptFiles
         /// <param name="perform">Whether the flushed events should be performed.</param>
         private void flushEvents(bool perform)
         {
+            Action[] events;
+            lock (queuedEvents)
+            {
+                events = queuedEvents.ToArray();
+                queuedEvents.Clear();
+            }
+
             if (perform)
             {
-                foreach (var a in cachedEvents)
+                foreach (var a in events)
                     a.Invoke();
             }
 
-            cachedEvents.Clear();
             delayingEvents = false;
         }
 
         private void handleEvent(Action a)
         {
             if (delayingEvents)
-                cachedEvents.Add(a);
+                lock (queuedEvents) queuedEvents.Add(a);
             else
                 a.Invoke();
         }