Make callback manager thread safe again

Fixes #1424
SteamRE · Sep 10, 2024 · 48f5000 · 48f5000
1 parent b41b923
commit 48f5000
Showing 1 changed file with 28 additions and 11 deletions.
diff --git a/SteamKit2/SteamKit2/Steam/SteamClient/CallbackMgr/CallbackMgr.cs b/SteamKit2/SteamKit2/Steam/SteamClient/CallbackMgr/CallbackMgr.cs
@@ -22,7 +22,7 @@ public sealed class CallbackManager : ICallbackMgrInternals
     {
         SteamClient client;
 
-        List<CallbackBase> registeredCallbacks;
+        CallbackBase[] registeredCallbacks = [];
 
 
 
@@ -34,8 +34,6 @@ public CallbackManager( SteamClient client )
         {
             ArgumentNullException.ThrowIfNull( client );
 
-            registeredCallbacks = [];
-
             this.client = client;
         }
 
@@ -142,18 +140,42 @@ public IDisposable Subscribe<TCallback>( Action<TCallback> callbackFunc )
 
         void ICallbackMgrInternals.Register( CallbackBase call )
         {
-            if ( registeredCallbacks.Contains( call ) )
+            var oldCallbacks = registeredCallbacks;
+
+            if ( Array.IndexOf( oldCallbacks, call ) != -1 )
+                return;
+
+            // Create a new array for Handle() to be thread safe
+            var newCallbacks = new CallbackBase[ oldCallbacks.Length + 1 ];
+            Array.Copy( oldCallbacks, newCallbacks, oldCallbacks.Length );
+            newCallbacks[ ^1 ] = call;
+
+            Interlocked.Exchange( ref registeredCallbacks, newCallbacks );
+        }
+
+        void ICallbackMgrInternals.Unregister( CallbackBase call )
+        {
+            var oldCallbacks = registeredCallbacks;
+            var oldIndex = Array.IndexOf( oldCallbacks, call );
+
+            if ( oldIndex < 0 )
                 return;
 
-            registeredCallbacks.Add( call );
+            var newCallbacks = new CallbackBase[ oldCallbacks.Length - 1 ];
+
+            Array.Copy( oldCallbacks, 0, newCallbacks, 0, oldIndex );
+            Array.Copy( oldCallbacks, oldIndex + 1, newCallbacks, oldIndex, oldCallbacks.Length - oldIndex - 1 );
+
+            Interlocked.Exchange( ref registeredCallbacks, newCallbacks );
         }
 
         void Handle( ICallbackMsg call )
         {
+            var callbacks = registeredCallbacks;
             var type = call.GetType();
 
             // find handlers interested in this callback
-            foreach ( var callback in registeredCallbacks )
+            foreach ( var callback in callbacks )
             {
                 if ( callback.CallbackType.IsAssignableFrom( type ) )
                 {
@@ -162,11 +184,6 @@ void Handle( ICallbackMsg call )
             }
         }
 
-        void ICallbackMgrInternals.Unregister( CallbackBase call )
-        {
-            registeredCallbacks.Remove( call );
-        }
-
         sealed class Subscription : IDisposable
         {
             public Subscription( CallbackBase call, ICallbackMgrInternals manager )