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Unity Engine

Read

Issues an asynchronous file read operation. Returns a ReadHandle.
Read time 3 minutesLast updated 10 days ago

Definition

Read(string, ReadCommand*, uint, string, ulong, AssetLoadingSubsystem)

Issues an asynchronous file read operation. Returns a ReadHandle.
public static ReadHandle Read(string filename, ReadCommand* readCmds, uint readCmdCount, string assetName = "", ulong typeID = 0, AssetLoadingSubsystem subsystem = AssetLoadingSubsystem.Scripts)

Parameters

filename

string
The filename to read from.

readCmds

ReadCommand*
A pointer to an array of ReadCommand structs that specify offset, size, and destination buffer.

readCmdCount

uint
The number of read commands pointed to by readCmds.

assetName

string
(Optional) The name of the object being read, for metrics purposes.

typeID

ulong
(Optional) The TypeID of the object being read, for metrics purposes.

subsystem

AssetLoadingSubsystem
(Optional) The Subsystem tag for the read operation, for metrics purposes.

Returns

Type

Description

ReadHandleUsed to monitor the progress and status of the read command.

Remarks

You can set the 
assetName
, 
typeId
, and 
subsystem
parameters to collect asset-specific metrics for this read operation. When you enable metrics collection with AsyncReadManagerMetrics.StartCollectingMetrics, Unity includes this information as part of the AsyncReadManagerMetrics, allowing you to analyze how different types of assets affect performance.
The AsyncReadManager copies the data referenced by readCmds; you can dispose or free the data immediately after calling 
Read
.

Examples

using System.IO;using Unity.Collections;using Unity.IO.LowLevel.Unsafe;using Unity.Collections.LowLevel.Unsafe;using UnityEngine;class AsyncReadSample : MonoBehaviour{    private ReadHandle readHandle;    NativeArray<ReadCommand> cmds;    string assetName = "myfile";    ulong typeID = 114; // from https://docs.unity.com/engine/6000.5/manual/working-with-scenes/text-scene-format/class-idreference    AssetLoadingSubsystem subsystem = AssetLoadingSubsystem.Scripts;    public unsafe void Start()    {        string filePath = Path.Combine(Application.streamingAssetsPath, "myfile.bin");        cmds = new NativeArray<ReadCommand>(1, Allocator.Persistent);        ReadCommand cmd;        cmd.Offset = 0;        cmd.Size = 1024;        cmd.Buffer = (byte*)UnsafeUtility.Malloc(cmd.Size, 16, Allocator.Persistent);        cmds[0] = cmd;        readHandle = AsyncReadManager.Read(filePath, (ReadCommand*)cmds.GetUnsafePtr(), 1, assetName, typeID, subsystem);    }    public unsafe void Update()    {        if (readHandle.IsValid() && readHandle.Status != ReadStatus.InProgress)        {            Debug.LogFormat("Read {0}", readHandle.Status == ReadStatus.Complete ? "Successful" : "Failed");            readHandle.Dispose();            UnsafeUtility.Free(cmds[0].Buffer, Allocator.Persistent);            cmds.Dispose();        }    }}

Read(FileHandle, ReadCommandArray)

Queues a set of read operations for a file opened with AsyncReadManager.OpenFileAsync.
public static ReadHandle Read(in FileHandle fileHandle, ReadCommandArray readCmdArray)

Parameters

fileHandle

FileHandle
The FileHandle to be read from, opened by AsyncReadManager.OpenFileAsync.

readCmdArray

ReadCommandArray
A struct containing the read commands to queue.

Returns

Type

Description

ReadHandleA ReadHandle object you can use to check the status and monitor the progress of the read operations.

Remarks

This function makes a copy of the ReadCommandArray struct passed as a parameter internally, so you do not need to maintain the array.
Note: WebGL builds do not support using 
AsyncReadManager
to open files from a remote web server; for example, from the path 
Application.streamingAssetsPath
which maps to a URL on a remote web server.

Examples

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 void Start()    {        ReadCommand cmd;        cmd.Offset = 0;        cmd.Size = 1024;        cmd.Buffer = (byte*)UnsafeUtility.Malloc(cmd.Size, 16, Allocator.Persistent);        FileHandle fileHandle = AsyncReadManager.OpenFileAsync(TestFilename);        ReadCommandArray readCmdArray;        readCmdArray.ReadCommands = &cmd;        readCmdArray.CommandCount = 1;        ReadHandle readHandle = AsyncReadManager.Read(fileHandle, readCmdArray);        JobHandle closeJob = fileHandle.Close(readHandle.JobHandle);        closeJob.Complete();        // ... Use the data read into the buffer        readHandle.Dispose();        for (int i = 0; i < readCmdArray.CommandCount; i++)            UnsafeUtility.Free(readCmdArray.ReadCommands[i].Buffer, Allocator.Persistent);    }}