From 6fd4ef735ed71d9c35f1c296e9b4bc72b3b997af Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Tue, 12 Aug 2025 23:35:12 +0200
Subject: [PATCH] Add `InvokeOnUpdate` to C++ scripting api

---
 Source/Engine/Scripting/Scripting.cpp | 29 +++++++++++++++++++++++++++
 Source/Engine/Scripting/Scripting.h   |  5 +++++
 2 files changed, 34 insertions(+)

diff --git a/Source/Engine/Scripting/Scripting.cpp b/Source/Engine/Scripting/Scripting.cpp
index 593092b8f..db6867d34 100644
--- a/Source/Engine/Scripting/Scripting.cpp
+++ b/Source/Engine/Scripting/Scripting.cpp
@@ -106,6 +106,7 @@ namespace
     MMethod* _method_LateFixedUpdate = nullptr;
     MMethod* _method_Draw = nullptr;
     MMethod* _method_Exit = nullptr;
+    Array<Function<void()>> UpdateActions;
     Dictionary<StringAnsi, BinaryModule*, InlinedAllocation<64>> _nonNativeModules;
 #if USE_EDITOR
     bool LastBinariesLoadTriggeredCompilation = false;
@@ -242,6 +243,27 @@ void ScriptingService::Update()
     PROFILE_CPU_NAMED("Scripting::Update");
     INVOKE_EVENT(Update);
 
+    // Flush update actions
+    _objectsLocker.Lock();
+    int32 count = UpdateActions.Count();
+    for (int32 i = 0; i < count; i++)
+    {
+        UpdateActions[i]();
+    }
+    int32 newlyAdded = UpdateActions.Count() - count;
+    if (newlyAdded == 0)
+        UpdateActions.Clear();
+    else
+    {
+        // Someone added another action within current callback
+        Array<Function<void()>> tmp;
+        for (int32 i = newlyAdded; i < UpdateActions.Count(); i++)
+            tmp.Add(UpdateActions[i]);
+        UpdateActions.Clear();
+        UpdateActions.Add(tmp);
+    }
+    _objectsLocker.Unlock();
+
 #ifdef USE_NETCORE
     // Force GC to run in background periodically to avoid large blocking collections causing hitches
     if (Time::Update.TicksCount % 60 == 0)
@@ -303,6 +325,13 @@ void Scripting::ProcessBuildInfoPath(String& path, const String& projectFolderPa
         path = projectFolderPath / path;
 }
 
+void Scripting::InvokeOnUpdate(const Function<void()>& action)
+{
+    _objectsLocker.Lock();
+    UpdateActions.Add(action);
+    _objectsLocker.Unlock();
+}
+
 bool Scripting::LoadBinaryModules(const String& path, const String& projectFolderPath)
 {
     PROFILE_CPU_NAMED("LoadBinaryModules");
diff --git a/Source/Engine/Scripting/Scripting.h b/Source/Engine/Scripting/Scripting.h
index be5e9ca34..1e7daf6f0 100644
--- a/Source/Engine/Scripting/Scripting.h
+++ b/Source/Engine/Scripting/Scripting.h
@@ -230,6 +230,11 @@ public:
 
     static void ProcessBuildInfoPath(String& path, const String& projectFolderPath);
 
+    /// <summary>
+    /// Calls the given action on the next scripting update.
+    /// </summary>
+    /// <param name="action">The action to invoke.</param>
+    static void InvokeOnUpdate(const Function<void()>& action);
 private:
 
     static bool LoadBinaryModules(const String& path, const String& projectFolderPath);