Method AddJobHandleForProducer

AddJobHandleForProducer(JobHandle)

Adds the specified JobHandle to this system's list of dependencies.

Declaration

public void AddJobHandleForProducer(JobHandle producerJob)

Parameters

Type	Name	Description
JobHandle	producerJob	The JobHandle of a Job which this buffer system should wait for before playing back its pending command buffers.

Remarks

When you write to an EntityCommandBuffer from a Job, you must add the JobHandle of that Job to this EntityCommandBufferSystem's input dependencies by calling this function. Otherwise, this system could attempt to execute the command buffer contents while the writing Job is still running, causing a race condition.

Examples

The following example illustrates how to use one of the default EntityCommandBufferSystems. The code selects all entities that have one custom component, in this case, AsyncProcessInfo, and processes each entity in the Execute() function of an IJobEntity Job. After processing, the Job uses a EntityCommandBuffer to remove the ProcessInfo component and add a ProcessCompleteTag component. Another system could use the ProcessCompleteTag to find entities that represent the end results of the process.

public struct ProcessInfo : IComponentData { public float Value; }
public struct ProcessCompleteTag : IComponentData { }

[BurstCompile]
public partial struct ProcessInBackgroundJob : IJobEntity
{
    public EntityCommandBuffer.ParallelWriter ConcurrentCommands;

    public void Execute(Entity entity, [ChunkIndexInQuery] int chunkIndex, in ProcessInfo info)
    {
        // ...hypothetical processing goes here...

        // Remove ProcessInfo and add a ProcessCompleteTag...
        ConcurrentCommands.RemoveComponent<ProcessInfo>(chunkIndex, entity);
        ConcurrentCommands.AddComponent<ProcessCompleteTag>(chunkIndex, entity);
    }
}

public partial class AsyncProcessJobSystem : SystemBase
{
    protected override void OnUpdate()
    {
        // Get a reference to the system that will play back
        var ecbSystem = World.GetOrCreateSystemManaged<NonSingletonECBSystem>();
        var ecb = ecbSystem.CreateCommandBuffer();

        // Pass the command buffer to the writer job, using its ParallelWriter interface
        var job = new ProcessInBackgroundJob
        {
            ConcurrentCommands = ecb.AsParallelWriter(),
        };
        Dependency = job.ScheduleParallel(Dependency);

        // Register the writer job with the playback system as an input dependency
        ecbSystem.AddJobHandleForProducer(Dependency);
    }
}