UE4的多线程

1. 源代码

　　AsyncWork.h

2. 多线程的使用

　　参考文档：https://wiki.unrealengine.com/Using_AsyncTasks

　　当我们需要执行一个需要很长时间的任务时，放在主线程里会导致很卡，把此任务放到其他线程里则会好很多，此时多线程就可以起到关键的作用了。

　　在UE4里，我们可以使用FAsyncTask 或者FAutoDeleteAsyncTask。

　　使用FAsyncTask 时，我们需要手动停止或删除任务；使用FAutoDeleteAsyncTask时，系统则会自动在任务结束后，删除任务。

　　需要先建个继承FNonAbandonableTask的类，如源码中的例子：

class ExampleAutoDeleteAsyncTask : public FNonAbandonableTask

    {

        friend class FAutoDeleteAsyncTask<ExampleAutoDeleteAsyncTask>;

        int32 ExampleData;

        ExampleAutoDeleteAsyncTask(int32 InExampleData)

         : ExampleData(InExampleData)

        {

        }

        void DoWork()

        {

            ... do the work here

        }

        FORCEINLINE TStatId GetStatId() const

        {

            RETURN_QUICK_DECLARE_CYCLE_STAT(ExampleAutoDeleteAsyncTask, STATGROUP_ThreadPoolAsyncTasks);

        }

    };

　　然后具体调用就是：

void Example()

    {

        // start an example job

        (new FAutoDeleteAsyncTask<ExampleAutoDeleteAsyncTask>()->StartBackgroundTask();

        // do an example job now, on this thread

        (new FAutoDeleteAsyncTask<ExampleAutoDeleteAsyncTask>()->StartSynchronousTask();

    }

　　注意：StartBackgroundTask（）是在另一个线程中执行此任务；StartSynchronousTask（）是在当前线程中马上执行此任务。

　　举个例子：

.h:

#pragma once

#include "CoreMinimal.h"

#include "GameFramework/Actor.h"

#include "Kismet/KismetSystemLibrary.h"

#include "MyActor.generated.h"

UCLASS()

class ASYNCWORKSTUDY_API AMyActor : public AActor

{

    GENERATED_BODY()

public:

    // Sets default values for this actor's properties

    AMyActor();

protected:

    // Called when the game starts or when spawned

    virtual void BeginPlay() override;

public:

    // Called every frame

    virtual void Tick(float DeltaTime) override;

    void TestAsync(FString Content);

    //多线程例子

    void Example();

};

class ExampleAutoDeleteAsyncTask : public FNonAbandonableTask

{

    friend class FAutoDeleteAsyncTask<ExampleAutoDeleteAsyncTask>;

    int32 ExampleData;

    UObject* Object;

    AMyActor* Target;

    ExampleAutoDeleteAsyncTask(int32 InExampleData, UObject* InObject, AMyActor* InTarget)

        : ExampleData(InExampleData),

        Object(InObject),

        Target(InTarget)

    {

    }

    void DoWork()

    {

        UKismetSystemLibrary::PrintString(Object, FString::FromInt(ExampleData));

        //调用AMyactor的测试函数

        if (Target) Target->TestAsync("Success");

    }

    FORCEINLINE TStatId GetStatId() const

    {

        RETURN_QUICK_DECLARE_CYCLE_STAT(ExampleAutoDeleteAsyncTask, STATGROUP_ThreadPoolAsyncTasks);

    }

};

.cpp:

    #include "MyActor.h"

// Sets default values

AMyActor::AMyActor()

{

     // Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.

    PrimaryActorTick.bCanEverTick = true;

}

// Called when the game starts or when spawned

void AMyActor::BeginPlay()

{

    Super::BeginPlay();

    UKismetSystemLibrary::PrintString(this, "Hello");

    Example();

}

// Called every frame

void AMyActor::Tick(float DeltaTime)

{

    Super::Tick(DeltaTime);

}

void AMyActor::TestAsync(FString Content)

{

    UKismetSystemLibrary::PrintString(this, Content);

}

void AMyActor::Example()

{

    //在其他线程里执行此任务

    auto task = new FAutoDeleteAsyncTask<ExampleAutoDeleteAsyncTask>(, GetWorld(), this);

    if (task) task->StartBackgroundTask();

    //此任务会在当前线程中马上开始。

    auto task2= new FAutoDeleteAsyncTask<ExampleAutoDeleteAsyncTask>(, GetWorld(), this);

    if (task2) task2->StartSynchronousTask();

}

巴特西

UE4的多线程

1. 源代码

2. 多线程的使用

最新文章

热门文章