AsyncReadManager.ReadDeferred

参数

返回值

ReadHandle 一个 ReadHandle 对象，您可以使用它来检查读取操作的状态和监控进度。

描述

在指定作业完成之后，为文件排队一组读取操作。

此函数不会复制作为参数传递的 ReadCommandArray 结构。您可以在将作业作为依赖项传递到此函数之前更改读取命令。读取将自动等待 FileHandle.JobHandle 完成。

作为不安全的低级 API，用户有责任避免在读取操作开始后更改或释放 ReadCommandArray。这样做会导致缓冲区溢出和竞争条件。（如果更改命令数量，请记住也要更新 ReadCommandArray.CommandCount 字段。）

注意：WebGL 构建不支持使用 AsyncReadManager 从远程 Web 服务器打开文件；例如，从映射到远程 Web 服务器上 URL 的路径 Application.streamingAssetsPath。

using System.IO;
using Unity.Collections;
using Unity.IO.LowLevel.Unsafe;
using Unity.Collections.LowLevel.Unsafe;
using UnityEngine;
using Unity.Jobs;

class AsyncReadSample : MonoBehaviour
{
    static string TestFilename = Path.Combine(Application.streamingAssetsPath, "myfile.bin");

    public unsafe struct ReadCommandJob : IJob
    {
        public NativeArray<ReadCommandArray> ReadCmdArrayNative;

        public void Execute()
        {
            const int kReadCount = 1;
            const int kReadSize = 2048;

            ReadCommand* readCmds = (ReadCommand*)UnsafeUtility.Malloc(sizeof(ReadCommand) * kReadCount, 16, Allocator.Persistent);

            readCmds[0] = new ReadCommand()
            {
                Buffer = (byte*)UnsafeUtility.Malloc(kReadSize, 16, Allocator.Persistent),
                Offset = 0,
                Size = kReadSize
            };

            ReadCmdArrayNative[0] = new ReadCommandArray
            {
                ReadCommands = readCmds,
                CommandCount = kReadCount
            };
        }
    }

    public unsafe void SetupReadInJob()
    {
        NativeArray<ReadCommandArray> readCmdArrayNative = new NativeArray<ReadCommandArray>(1, Allocator.Persistent);
        ReadCommandArray* readCmdArrayPtr = (ReadCommandArray*)readCmdArrayNative.GetUnsafePtr();

        FileHandle fileHandle = AsyncReadManager.OpenFileAsync(TestFilename);

        var createReadCommandJob = new ReadCommandJob
        {
            ReadCmdArrayNative = readCmdArrayNative
        }.Schedule();

        ReadHandle readHandle = AsyncReadManager.ReadDeferred(fileHandle, readCmdArrayPtr, createReadCommandJob);

        JobHandle closeJob = fileHandle.Close(readHandle.JobHandle);

        createReadCommandJob.Complete(); // Ensure the NativeArray is finished with before using
        closeJob.Complete();

        // ... Use the data read into the buffer

        readHandle.Dispose();

        for (int i = 0; i < readCmdArrayNative[0].CommandCount; i++)
            UnsafeUtility.Free(readCmdArrayNative[0].ReadCommands[i].Buffer, Allocator.Persistent);
        UnsafeUtility.Free(readCmdArrayNative[0].ReadCommands, Allocator.Persistent);

        readCmdArrayNative.Dispose();
    }
}