Core/Misc: Fixed thread-unsafe access to list of objects that should be spawned in a cell

Closes #29372

(cherry picked from commit 7b6589c1ecc159f6949c5535785fba79a04b2c4a)

4 files changed, 35 insertions, 27 deletions

diff --git a/src/server/game/Entities/Transport/Transport.cpp b/src/server/game/Entities/Transport/Transport.cpp
index ee309c908de..53f0157f7b2 100644
--- a/src/server/game/Entities/Transport/Transport.cpp
+++ b/src/server/game/Entities/Transport/Transport.cpp
@@ -532,22 +532,23 @@ void Transport::UpdatePosition(float x, float y, float z, float o)
 
 void Transport::LoadStaticPassengers()
 {
-    if (uint32 mapId = GetGOInfo()->moTransport.mapID)
+    uint32 mapId = GetGOInfo()->moTransport.mapID;
+    if (!mapId)
+        return;
+
+    CellObjectGuidsMap const* cells = sObjectMgr->GetMapObjectGuids(mapId, GetMap()->GetSpawnMode());
+    if (!cells)
+        return;
+
+    for (auto const& [cellId, guids] : *cells)
     {
-        CellObjectGuidsMap const& cells = sObjectMgr->GetMapObjectGuids(mapId, GetMap()->GetSpawnMode());
-        CellGuidSet::const_iterator guidEnd;
-        for (CellObjectGuidsMap::const_iterator cellItr = cells.begin(); cellItr != cells.end(); ++cellItr)
-        {
-            // Creatures on transport
-            guidEnd = cellItr->second.creatures.end();
-            for (CellGuidSet::const_iterator guidItr = cellItr->second.creatures.begin(); guidItr != guidEnd; ++guidItr)
-                CreateNPCPassenger(*guidItr, sObjectMgr->GetCreatureData(*guidItr));
-
-            // GameObjects on transport
-            guidEnd = cellItr->second.gameobjects.end();
-            for (CellGuidSet::const_iterator guidItr = cellItr->second.gameobjects.begin(); guidItr != guidEnd; ++guidItr)
-                CreateGOPassenger(*guidItr, sObjectMgr->GetGameObjectData(*guidItr));
-        }
+        // GameObjects on transport
+        for (ObjectGuid::LowType spawnId : guids.gameobjects)
+            CreateGOPassenger(spawnId, sObjectMgr->GetGameObjectData(spawnId));
+
+        // Creatures on transport
+        for (ObjectGuid::LowType spawnId : guids.creatures)
+            CreateNPCPassenger(spawnId, sObjectMgr->GetCreatureData(spawnId));
     }
 }
 
diff --git a/src/server/game/Globals/ObjectMgr.cpp b/src/server/game/Globals/ObjectMgr.cpp
index 301ff49ec8e..67bf9047c82 100644
--- a/src/server/game/Globals/ObjectMgr.cpp
+++ b/src/server/game/Globals/ObjectMgr.cpp
@@ -2338,6 +2338,19 @@ void ObjectMgr::LoadCreatures()
     TC_LOG_INFO("server.loading", ">> Loaded {} creatures in {} ms", _creatureDataStore.size(), GetMSTimeDiffToNow(oldMSTime));
 }
 
+CellObjectGuids const* ObjectMgr::GetCellObjectGuids(uint16 mapid, uint8 spawnMode, uint32 cell_id)
+{
+    if (CellObjectGuidsMap const* mapGuids = Trinity::Containers::MapGetValuePtr(_mapObjectGuidsStore, MAKE_PAIR32(mapid, spawnMode)))
+        return Trinity::Containers::MapGetValuePtr(*mapGuids, cell_id);
+
+    return nullptr;
+}
+
+CellObjectGuidsMap const* ObjectMgr::GetMapObjectGuids(uint16 mapid, uint8 spawnMode)
+{
+    return Trinity::Containers::MapGetValuePtr(_mapObjectGuidsStore, MAKE_PAIR32(mapid, spawnMode));
+}
+
 void ObjectMgr::AddCreatureToGrid(ObjectGuid::LowType guid, CreatureData const* data)
 {
     uint8 mask = data->spawnMask;
diff --git a/src/server/game/Globals/ObjectMgr.h b/src/server/game/Globals/ObjectMgr.h
index aff5d05118d..6eb39767842 100644
--- a/src/server/game/Globals/ObjectMgr.h
+++ b/src/server/game/Globals/ObjectMgr.h
@@ -1281,15 +1281,9 @@ class TC_GAME_API ObjectMgr
             return nullptr;
         }
 
-        CellObjectGuids const& GetCellObjectGuids(uint16 mapid, uint8 spawnMode, uint32 cell_id)
-        {
-            return _mapObjectGuidsStore[MAKE_PAIR32(mapid, spawnMode)][cell_id];
-        }
+        CellObjectGuids const* GetCellObjectGuids(uint16 mapid, uint8 spawnMode, uint32 cell_id);
 
-        CellObjectGuidsMap const& GetMapObjectGuids(uint16 mapid, uint8 spawnMode)
-        {
-            return _mapObjectGuidsStore[MAKE_PAIR32(mapid, spawnMode)];
-        }
+        CellObjectGuidsMap const* GetMapObjectGuids(uint16 mapid, uint8 spawnMode);
 
         /**
          * Gets temp summon data for all creatures of specified group.
diff --git a/src/server/game/Grids/ObjectGridLoader.cpp b/src/server/game/Grids/ObjectGridLoader.cpp
index bcb6e6b41af..b5e5826f042 100644
--- a/src/server/game/Grids/ObjectGridLoader.cpp
+++ b/src/server/game/Grids/ObjectGridLoader.cpp
@@ -121,15 +121,15 @@ void LoadHelper(CellGuidSet const& guid_set, CellCoord &cell, GridRefManager<T>
 void ObjectGridLoader::Visit(GameObjectMapType &m)
 {
     CellCoord cellCoord = i_cell.GetCellCoord();
-    CellObjectGuids const& cell_guids = sObjectMgr->GetCellObjectGuids(i_map->GetId(), i_map->GetSpawnMode(), cellCoord.GetId());
-    LoadHelper(cell_guids.gameobjects, cellCoord, m, i_gameObjects, i_map);
+    if (CellObjectGuids const* cell_guids = sObjectMgr->GetCellObjectGuids(i_map->GetId(), i_map->GetSpawnMode(), cellCoord.GetId()))
+        LoadHelper(cell_guids->gameobjects, cellCoord, m, i_gameObjects, i_map);
 }
 
 void ObjectGridLoader::Visit(CreatureMapType &m)
 {
     CellCoord cellCoord = i_cell.GetCellCoord();
-    CellObjectGuids const& cell_guids = sObjectMgr->GetCellObjectGuids(i_map->GetId(), i_map->GetSpawnMode(), cellCoord.GetId());
-    LoadHelper(cell_guids.creatures, cellCoord, m, i_creatures, i_map);
+    if (CellObjectGuids const* cell_guids = sObjectMgr->GetCellObjectGuids(i_map->GetId(), i_map->GetSpawnMode(), cellCoord.GetId()))
+        LoadHelper(cell_guids->creatures, cellCoord, m, i_creatures, i_map);
 }
 
 void ObjectWorldLoader::Visit(CorpseMapType& /*m*/)