How to Jobfy this ComponentSystem-based code?

Let's say I have a bunch of source positions that need to be updated to some target positions, and each target's entity information is contained by the source positon's companion EntityHolder component. The only way I can think of is using ComponentDataFromEntity<Position> to take that entity info from that "Position(source) & EntityHolder" ComponentGroup and write to it in a for loop. I wonder how this should be implemented in the job system.

Code (CSharp):

1. public class PositioningSystem : ComponentSystem
2. {
3.     struct SourceGroup
4.     {
5.         public readonly int Length;
6.         [ReadOnly] public ComponentDataArray<Position> Positions;
7.         [ReadOnly] public ComponentDataArray<EntityHolder> EntityHolder;
8.     }
9.     [Inject] SourceGroup sourceGroup;
10.  
11.     [Inject] ComponentDataFromEntity<Position> TargetPosition;
12.  
13.     protected override void OnUpdate()
14.     {
15.         for (int i = 0; i < sourceGroup.Length; i++)
16.         {
17.             TargetPosition[sourceGroup.EntityHolder[i].TargetEntity] = sourceGroup.Positions[i];
18.         }
19.     }
20. }

 

Just derive from JobComponentSystem and launch a Job. There is nothing in your code making this a problem. All Injected arrays are automatically protected. While your Job is running no other System accessing Position or writing to EntityHolder components is allowed to run.

 

The problem was I can't put

[WriteOnly] ComponentDataFromEntity<Position>

inside a job.

 

Can we use

ComponentDataFromEntity<Position>

in IJobProcessComponentData?