ReadOnlyAttribute

描述

借助 ReadOnly 属性，您可以将作业中所用结构的某个成员标记为只读。

在作业中使用原生容器时，这些容器在默认情况下处于读写状态。这意味着，您无法同时安排两个作业来引用相同的容器。通过向作业结构中的容器字段添加 [ReadOnly] 属性，将容器标记为只读，这样一来，两个作业可以并行运行，并从同一容器中读取数据。

另请参阅：IJob、IJobParallelFor。

using Unity.Jobs;
using Unity.Collections;
using UnityEngine;

public struct MyJob : IJob
{
    [ReadOnly]
    public NativeArray<int> input;

    public NativeArray<int> output;

    public void Execute()
    {
        for (var i = 0; i < output.Length; ++i)
            output[i] = input[i];
    }
}

public class ParallelReplicator : MonoBehaviour
{
    public void OnUpdate()
    {
        const int n = 10000;
        var original = new NativeArray<int>(n, Allocator.Persistent);
        var clone1 = new NativeArray<int>(n, Allocator.Persistent);
        var clone2 = new NativeArray<int>(n, Allocator.Persistent);

        var job1 = new MyJob
        {
            input = original,
            output = clone1
        };
        var job2 = new MyJob
        {
            input = original,
            output = clone2
        };

        var jobX = new MyJob
        {
            input = original,
            output = clone2
        };

        // Run the jobs in parallel.
        var jobs = JobHandle.CombineDependencies(job1.Schedule(), job2.Schedule());

        // jobX.Schedule(); // Not allowed, throws exception because job2 is writing into copy2.

        jobs.Complete();

        jobX.Schedule().Complete(); // Allowed, because job2 has been completed by now.

        original.Dispose();
        clone1.Dispose();
        clone2.Dispose();
    }
}