From 42a3ca3d560084a60b2f18828b25d32b87a6913a Mon Sep 17 00:00:00 2001
From: Boondorl <boondorl@live.com>
Date: Wed, 9 Jul 2025 20:34:29 -0400
Subject: [PATCH] Move OnLoad to after everything is done serializing

Makes behavior much more consistent and safer.
---
 src/g_level.cpp          |  4 ++++
 src/playsim/dthinker.cpp | 52 ++++++++++++++++++++++++++++++----------
 src/playsim/dthinker.h   |  3 ++-
 3 files changed, 46 insertions(+), 13 deletions(-)

diff --git a/src/g_level.cpp b/src/g_level.cpp
index f5921948e..9ea40c929 100644
--- a/src/g_level.cpp
+++ b/src/g_level.cpp
@@ -1538,6 +1538,10 @@ void FLevelLocals::DoLoadLevel(const FString &nextmapname, int position, bool au
 	{
 		I_Error("no start for player %d found.", pnumerr);
 	}
+
+	// If loading in from existing data, allow things to reinitialize if needed.
+	if (FromSnapshot || savegamerestore)
+		Thinkers.OnLoad();
 }
 
 
diff --git a/src/playsim/dthinker.cpp b/src/playsim/dthinker.cpp
index 2d37ffcfd..a5cffd67a 100644
--- a/src/playsim/dthinker.cpp
+++ b/src/playsim/dthinker.cpp
@@ -362,6 +362,20 @@ void FThinkerCollection::DestroyAllThinkers(bool fullgc)
 //
 //==========================================================================
 
+void FThinkerCollection::OnLoad()
+{
+	for (auto& list : FreshThinkers)
+		list.OnLoad();
+	for (auto& list : Thinkers)
+		list.OnLoad();
+}
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
 void FThinkerCollection::SerializeThinkers(FSerializer &arc, bool hubLoad)
 {
 	//DThinker *thinker;
@@ -415,12 +429,12 @@ void FThinkerCollection::SerializeThinkers(FSerializer &arc, bool hubLoad)
 								else if (thinker->ObjectFlags & OF_JustSpawned)
 								{
 									FreshThinkers[i].AddTail(thinker);
-									thinker->CallPostSerialize();
+									thinker->PostSerialize();
 								}
 								else
 								{
 									Thinkers[i].AddTail(thinker);
-									thinker->CallPostSerialize();
+									thinker->PostSerialize();
 								}
 							}
 						}
@@ -645,6 +659,30 @@ void FThinkerList::SaveList(FSerializer &arc)
 //
 //==========================================================================
 
+void FThinkerList::OnLoad()
+{
+	DThinker* node = GetHead();
+	if (node == nullptr)
+		return;
+
+	while (node != Sentinel)
+	{
+		NextToThink = node->NextThinker;
+		if (!(node->ObjectFlags & OF_EuthanizeMe))
+		{
+			IFOVERRIDENVIRTUALPTRNAME(node, NAME_Thinker, OnLoad)
+				VMCallVoid<DThinker*>(func, node);
+		}
+		node = NextToThink;
+	}
+}
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
 int FThinkerList::TickThinkers(FThinkerList *dest)
 {
 	int count = 0;
@@ -833,16 +871,6 @@ void DThinker::PostSerialize()
 {
 }
 
-void DThinker::CallPostSerialize()
-{
-	PostSerialize();
-	IFOVERRIDENVIRTUALPTRNAME(this, NAME_Thinker, OnLoad)
-	{
-		VMValue params[] = { this };
-		VMCall(func, params, 1, nullptr, 0);
-	}
-}
-
 //==========================================================================
 //
 // 
diff --git a/src/playsim/dthinker.h b/src/playsim/dthinker.h
index 95c2bb4bc..8a446e461 100644
--- a/src/playsim/dthinker.h
+++ b/src/playsim/dthinker.h
@@ -60,6 +60,7 @@ struct FThinkerList
 	bool IsEmpty() const;
 	void DestroyThinkers();
 	bool DoDestroyThinkers();
+	void OnLoad();
 	int TickThinkers(FThinkerList *dest);	// Returns: # of thinkers ticked
 	int ProfileThinkers(FThinkerList *dest);
 	void SaveList(FSerializer &arc);
@@ -83,6 +84,7 @@ struct FThinkerCollection
 	void DestroyAllThinkers(bool fullgc = true);
 	void SerializeThinkers(FSerializer &arc, bool keepPlayers);
 	void MarkRoots();
+	void OnLoad();
 	DThinker *FirstThinker(int statnum);
 	void Link(DThinker *thinker, int statnum);
 
@@ -105,7 +107,6 @@ public:
 	virtual void PostBeginPlay ();	// Called just before the first tick
 	virtual void CallPostBeginPlay(); // different in actor.
 	virtual void PostSerialize();
-	void CallPostSerialize();
 	void Serialize(FSerializer &arc) override;
 	size_t PropagateMark();