Is lambda for managed components assured to produce no garbage?

I've run it through in the profiler with a captured local variable. It does indeed produce garbage.

Code (CSharp):

1. protected override void OnUpdate() {
2.     int value = UnityEngine.Random.Range(1, 101);
3.    
4.     this.Entities.With(this.query).ForEach(delegate(SampleManaged sample, AnotherManaged another) {
5.         sample.Value = value;
6.     });
7. }

I've read somewhere that lambdas would be compiled to something that won't throw garbage but I'm not sure if it's applied to managed components.

 

This is the fix to remove the garbage but it's verbose:

Code (CSharp):

1. public class MultipleManagedComponentSystem : ComponentSystem {
2.     private EntityQuery query;
3.  
4.     private readonly Processor processor = new Processor();
5.     private EntityQueryBuilder.F_CC<SampleManaged, AnotherManaged> foreachDelegate;
6.    
7.     protected override void OnCreate() {
8.         this.query = GetEntityQuery(typeof(SampleManaged), typeof(AnotherManaged));
9.         this.foreachDelegate = this.processor.Execute;
10.     }
11.  
12.     protected override void OnUpdate() {
13.         int value = UnityEngine.Random.Range(1, 101);
14.         this.processor.Init(value);
15.         this.Entities.With(this.query).ForEach(this.foreachDelegate);
16.     }
17.    
18.     private class Processor {
19.         private int value;
20.  
21.         public void Init(int value) {
22.             this.value = value;
23.         }
24.  
25.         public void Execute(SampleManaged sample, AnotherManaged another) {
26.             sample.Value = this.value;
27.         }
28.     }
29. }

 

ComponentSystem lambdas don't use the codegen lambdas. Use SystemBase instead with WithoutBurst() and Run().

 

Wait I was also under the impression that the lambda entity api creates no garbage

 

Do you mean to use ComponentSystemBase? It doesn't have the EntityQueryBuilder property (Entities).

 

He mean SystemBase. It’s new compilation of better things from ComponentSystem and JobComponentSystem with better code generation for ForEach and automatic dependency handling for ForEach.

 

Does it make a difference if it's a standalone build? Unity does add a few checks in editor which can also generate garbage, but I don't know for this case. Just a thought.

 

I didn't know that. Will try it.

Edit: Wait, does it mean that lambdas in JobComponentSystem produce garbage as well?

 

No, JobComponentSystem is when they first introduced the codegen to prevent that. However at this point there is no reason to be using ComponentSystem or JobComponentSystem. Unity has said they will be removed eventually. SystemBase is the only thing we should be using.

 

Wait JobComponentSystem is going away. Can I get a link to catch up please.

 

https://docs.unity3d.com/Packages/com.unity.entities@0.8/manual/ecs_systems.html

From the docs:

Important: The ComponentSystem and JobComponentSystem classes, along with IJobForEach, are being phased out of the DOTS API, but have not been officially deprecated yet. Use SystemBase and Entities.ForEach instead.