Creating ArchetypeChunk not every update inside ComponentSystem

Hello,

I have got question about creating NativeArray<ArchetypeChunk> from ComponentGroup or EntityManager for iterating data throught chunks. Is it alright if i recreate Chunks only if ComponentOrderVersion change? e.g. store inside variable (deallocate inside OnDestroyManager)

I mean i have for example 10k entities who's match my EntityArchetypeQuery. Creating and destroing can only happened occasionally (only if i change settings).

Spoiler: Example

Code (CSharp):

1.  
2. public class TestSystem : ComponentSystem
3. {
4.     private ComponentGroup _group;
5.     private NativeArray<ArchetypeChunk> _chunks;
6.     private int _testComponentOrderVersion = -1;
7.  
8.     protected override void OnCreateManager()
9.     {
10.         base.OnCreateManager();
11.         _group = GetComponentGroup(typeof(TestComponent));
12.     }
13.  
14.     protected override void OnDestroyManager()
15.     {
16.         base.OnDestroyManager();
17.         if (_chunks.IsCreated)
18.         {
19.             _chunks.Dispose();
20.         }
21.     }
22.  
23.     protected override void OnUpdate()
24.     {
25.         UpdateArchetypeChunks();
26.         // work with chunks ...
27.     }
28.  
29.     private void UpdateArchetypeChunks()
30.     {
31.         var testComponentOrderVersion = EntityManager.GetComponentOrderVersion<TestComponent>();
32.         if (testComponentOrderVersion == _testComponentOrderVersion)
33.         {
34.             return;
35.         }
36.  
37.         if (_chunks.IsCreated)
38.         {
39.             _chunks.Dispose();
40.         }
41.  
42.         _chunks = _group.CreateArchetypeChunkArray(Allocator.Persistent);
43.  
44.         _testComponentOrderVersion = testComponentOrderVersion;
45.     }
46. }
47.  

 

it's working, but i have little problem. OrderVersion from ComponentGroup or EntityManager is not same, but i can accept it. But problem goes when i try to create new entities with different components (without components from cached archetypechunk). Suddenly OrderVersion from ComponentGroup (cached archetypechunk array) start increasing. Is this correct behaviour?

Spoiler: Example

Code (CSharp):

1. public struct SomeData1 : IComponentData
2. {
3.     public int value;
4. }
5.  
6. public struct SomeData2 : IComponentData
7. {
8.     public int value;
9. }

Code (CSharp):

1. [ExecuteAlways]
2. public class CreateSystem : ComponentSystem
3. {
4.     private EntityArchetype _entityArchetype;
5.  
6.     protected override void OnCreateManager()
7.     {
8.         base.OnCreateManager();
9.         EntityManager.CreateEntity(EntityManager.CreateArchetype(typeof(SomeData1)));
10.         EntityManager.CreateEntity(EntityManager.CreateArchetype(typeof(SomeData1)));
11.         EntityManager.CreateEntity(EntityManager.CreateArchetype(typeof(SomeData1)));
12.         EntityManager.CreateEntity(EntityManager.CreateArchetype(typeof(SomeData1)));
13.      
14.         _entityArchetype = EntityManager.CreateArchetype(typeof(SomeData2));
15.     }
16.  
17.     protected override void OnUpdate()
18.     {
19.         PostUpdateCommands.CreateEntity(_entityArchetype);
20.     }
21. }
22.  

Code (CSharp):

1. public class UpdateSystem : ComponentSystem
2. {
3.     private ComponentGroup _group;
4.  
5.     protected override void OnCreateManager()
6.     {
7.         base.OnCreateManager();
8.         _group = GetComponentGroup(typeof(SomeData1));
9.     }
10.  
11.     protected override void OnUpdate()
12.     {
13.         Debug.Log("----------------");
14.         Debug.Log($"ComponentGroup: {_group.GetCombinedComponentOrderVersion()}");
15.         Debug.Log($"EntityManager: {EntityManager.GetComponentOrderVersion<SomeData1>()}");
16.     }
17. }

 

Can someone explain me previous post? I thought that ComponentOrderVersion from ComponentGroup would not change if i don't create new entity with same components. Is it bug or correct behaviour?
Thanks

 

Yeah this i know, but in my example i have two systems:

1. CreateSystem - ExecuteAlways
   • OnCreateManager - create 4 entities with component SomeData1, none of it has SomeData2
   • OnUpdate - create new entity with component SomeData2, none of it has SomeData1
2. UpdateSystem
   • OnCreateManager - ComponentGroup of entities with component SomeData1
     
   • OnUpdate - printing order version from coponent SomeData1 via ComponentGroup / EntityManager

So I'm not creating any new entities with component SomeData1. Only creating entities with component SomeData2. So why is ComponentOrderVersion change from ComponentGroup if i dont modify any entity or create/delete with component type SomeData1?

or maybe i something missing?