Fix join-point reload cache crash

Source/Client/AsyncTime/AsyncWorldTimeComp.cs

@@ -276,7 +276,10 @@ public void ExecuteCmd(ScheduledCommand cmd)
 
     private static void CreateJoinPointAndSendIfHost()
     {
-        Multiplayer.session.dataSnapshot = SaveLoad.CreateGameDataSnapshot(SaveLoad.SaveAndReload(true), Multiplayer.GameComp.multifaction);
+        Multiplayer.session.dataSnapshot = SaveLoad.SaveReloadAndCreateSnapshot(
+            Multiplayer.GameComp.multifaction,
+            ReloadOptimizationMode.ForJoinPointSnapshot
+        );
 
         if (!TickPatch.Simulating && !Multiplayer.IsReplay)
         {

Source/Client/Saving/ReloadOptimization.cs

@@ -0,0 +1,53 @@
+using System;
+using Verse;
+
+namespace Multiplayer.Client
+{
+    public enum ReloadOptimizationMode
+    {
+        None,
+        ForJoinPointSnapshot,
+    }
+
+    internal static class ReloadOptimization
+    {
+        public static ReloadOptimizationPlan PlanFor(ReloadOptimizationMode mode)
+        {
+            return mode switch
+            {
+                ReloadOptimizationMode.ForJoinPointSnapshot => new(
+                    RegenerateMapDrawersWhenRestoringFaction: false,
+                    RegenerateMapDrawersAfterSnapshot: true
+                ),
+                _ => new(
+                    RegenerateMapDrawersWhenRestoringFaction: true,
+                    RegenerateMapDrawersAfterSnapshot: false
+                ),
+            };
+        }
+
+        public static void Complete(ReloadOptimizationMode mode)
+        {
+            Complete(mode, RegenerateMapDrawers);
+        }
+
+        internal static void Complete(ReloadOptimizationMode mode, Action regenerateMapDrawers)
+        {
+            if (!PlanFor(mode).RegenerateMapDrawersAfterSnapshot)
+                return;
+
+            regenerateMapDrawers();
+        }
+
+        private static void RegenerateMapDrawers()
+        {
+            foreach (var map in Find.Maps)
+                map.mapDrawer.RegenerateEverythingNow();
+        }
+    }
+
+    internal readonly record struct ReloadOptimizationPlan(
+        bool RegenerateMapDrawersWhenRestoringFaction,
+        bool RegenerateMapDrawersAfterSnapshot
+    );
+}

Source/Client/Saving/SaveLoad.cs

@@ -20,13 +20,23 @@ public record TempGameData(XmlDocument SaveData, byte[] SessionData);
 
     public static class SaveLoad
     {
-        public static TempGameData SaveAndReload(bool cache = false)
+        public static TempGameData SaveAndReload()
+        {
+            return SaveAndReload(ReloadOptimizationMode.None);
+        }
+
+        public static TempGameData SaveAndReload(ReloadOptimizationMode optimizationMode)
+        {
+            var data = SaveAndReloadCore(optimizationMode);
+            ReloadOptimization.Complete(optimizationMode);
+            return data;
+        }
+
+        private static TempGameData SaveAndReloadCore(ReloadOptimizationMode optimizationMode)
         {
             Multiplayer.reloading = true;
 
-            var worldGridSaved = Find.WorldGrid;
             var tweenedPos = new Dictionary<int, Vector3>();
-            var drawers = new Dictionary<int, MapDrawer>();
             var localFactionId = Multiplayer.RealPlayerFaction.loadID;
             var mapCmds = new Dictionary<int, Queue<ScheduledCommand>>();
             var planetRenderMode = Find.World.renderer.wantedMode;
@@ -37,8 +47,6 @@ public static TempGameData SaveAndReload(bool cache = false)
 
             foreach (Map map in Find.Maps)
             {
-                drawers[map.uniqueID] = map.mapDrawer;
-
                 foreach (Pawn p in map.mapPawns.AllPawnsSpawned)
                     tweenedPos[p.thingIDNumber] = p.drawer.tweener.tweenedPos;
 
@@ -58,21 +66,6 @@ public static TempGameData SaveAndReload(bool cache = false)
                 gameData = SaveGameData();
             }
 
-            if (cache)
-            {
-                MapDrawerRegenPatch.copyFrom = drawers;
-                WorldGridCachePatch.copyFrom = worldGridSaved;
-                WorldGridExposeDataPatch.copyFrom = worldGridSaved;
-                WorldRendererCachePatch.copyFrom = worldGridSaved;
-            }
-            else
-            {
-                MapDrawerRegenPatch.copyFrom.Clear();
-                WorldGridCachePatch.copyFrom = null;
-                WorldGridExposeDataPatch.copyFrom = null;
-                WorldRendererCachePatch.copyFrom = null;
-            }
-
             MusicManagerPlay musicManager = null;
             if (Find.MusicManagerPlay.gameObjectCreated)
             {
@@ -88,7 +81,11 @@ public static TempGameData SaveAndReload(bool cache = false)
             if (musicManager != null)
                 Current.Root_Play.musicManagerPlay = musicManager;
 
-            Multiplayer.game.ChangeRealPlayerFaction(Find.FactionManager.GetById(localFactionId));
+            var reloadPlan = ReloadOptimization.PlanFor(optimizationMode);
+            Multiplayer.game.ChangeRealPlayerFaction(
+                Find.FactionManager.GetById(localFactionId),
+                reloadPlan.RegenerateMapDrawersWhenRestoringFaction
+            );
 
             foreach (Map m in Find.Maps)
             {
@@ -118,6 +115,14 @@ public static TempGameData SaveAndReload(bool cache = false)
             return gameData;
         }
 
+        public static GameDataSnapshot SaveReloadAndCreateSnapshot(bool removeCurrentMapId, ReloadOptimizationMode optimizationMode)
+        {
+            var data = SaveAndReloadCore(optimizationMode);
+            var snapshot = CreateGameDataSnapshot(data, removeCurrentMapId);
+            ReloadOptimization.Complete(optimizationMode);
+            return snapshot;
+        }
+
         public static void LoadInMainThread(TempGameData gameData)
         {
             DeepProfiler.Start("Multiplayer LoadInMainThread");