UE几种异步加载

UE多线程分为3种。

1.AsyneTask

2.TaskGrop

3. FRunnable

.前两种应该是属于异步

.h

#include "CoreMinimal.h"
#include "Kismet/BlueprintAsyncActionBase.h"
#include "Async/AsyncWork.h"
#include "MyAsyncAction.generated.h"

DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FMyAsyncTaskNodeResult, int, Result);
/**
 *
 */
UCLASS()
class EDITORTOOLSDEMO_API UMyAsyncAction : public UBlueprintAsyncActionBase
{
	GENERATED_BODY()

public:

	UPROPERTY(BlueprintReadWrite)
		bool bSelfRun = false;

	UPROPERTY(BlueprintAssignable)
		FMyAsyncTaskNodeResult OnSuccess;


	UPROPERTY(BlueprintAssignable)
		FMyAsyncTaskNodeResult OnFail;

	/// <summary>
	/// 自动销毁的FAutoDeleteAsyncTask
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		static UMyAsyncAction* AsyncTaskLoad(int MaxNumber);

	/// <summary>
	/// 手动销毁的FAsyncTask,目前没有实现手动删除。还是建议使用自动删除的AsyncTaskLoad
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		static UMyAsyncAction* SimpleAsyncTaskLoad(int MaxNumber);

	void OnTaskFinish();
};


/// <summary>
/// FAutoDeleteAsyncTask:这同样是一个类模板,特点是Task执行完成之后无需手动垃圾回收  https://www.bilibili.com/read/cv9488877/
/// </summary>
class MyAsyncTask : FNonAbandonableTask
{
	/// <summary>
	/// 1.必备
	/// </summary>
	friend class FAutoDeleteAsyncTask<MyAsyncTask>;


	/// <summary>
	/// 自定义传值格式
	/// </summary>
	UMyAsyncAction* Node;
	//当前计数
	int32 CurrentCount = 0;
	//总计数
	int32 TotalCount;

	MyAsyncTask(UMyAsyncAction* waitNode, int Target)
		:Node(waitNode), TotalCount(Target) {}

	~MyAsyncTask()
	{
		GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Red, TEXT("ClearAsyncTask"));
	}


	/// <summary>
	/// 2.必备。 多线程工作函数
	/// </summary>
	void DoWork();

	/// <summary>
	/// 3.必备。根据不同名字修改"MyAsyncTask"
	/// </summary>
	/// <returns></returns>
	FORCEINLINE TStatId GetStatId() const
	{
		RETURN_QUICK_DECLARE_CYCLE_STAT(MyAsyncTask, STATGROUP_ThreadPoolAsyncTasks);
	}


};

/// <summary>
/// FAsyncTask:这是一个类模板,特点是Task初始化之后会被加入到线程池中执行,但是执行结束之后需要手动进行垃圾回收 https://www.bilibili.com/read/cv9488877/ 
/// </summary>
class  SimpleAsyncTask :FNonAbandonableTask
{
	//如 MyAsyncTask 同注释
	friend class FAsyncTask<SimpleAsyncTask>;

	UMyAsyncAction* Node;
	//当前计数
	int32 CurrentCount = 0;
	//总计数
	int32 TotalCount;

public:
	// 构造函数
	SimpleAsyncTask(UMyAsyncAction* waitNode, int Target)
		: Node(waitNode), TotalCount(Target) {}
	// 析构函数
	~SimpleAsyncTask()
	{
		GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Green, TEXT("ClearSimpleAsyncTask"));
	}

	// 具体任务逻辑执行
	void DoWork();


	// 固定写法，本类将作为函数参数
	FORCEINLINE TStatId GetStatId() const
	{
		RETURN_QUICK_DECLARE_CYCLE_STAT(SimpleAsyncTask, STATGROUP_ThreadPoolAsyncTasks);
	}
};

.cpp

#include "AsyncLoad/MyAsyncAction.h"

UMyAsyncAction* UMyAsyncAction::AsyncTaskLoad(int MaxNumber)
{
	UMyAsyncAction* Node = NewObject<UMyAsyncAction>();


	///FAutoDeleteAsyncTask:这同样是一个类模板,特点是Task执行完成之后无需手动垃圾回收 
	auto MyTDeleteTask = new FAutoDeleteAsyncTask<MyAsyncTask>(Node, MaxNumber);
	MyTDeleteTask->StartBackgroundTask();

	return Node;

}

FAsyncTask<SimpleAsyncTask>* MyTask;
UMyAsyncAction* UMyAsyncAction::SimpleAsyncTaskLoad(int MaxNumber)
{
	UMyAsyncAction* Node = NewObject<UMyAsyncAction>();


	/// <summary>
	/// FAsyncTask:这是一个类模板,特点是Task初始化之后会被加入到线程池中执行,但是执行结束之后需要手动进行垃圾回收
	/// </summary>

	MyTask = new FAsyncTask<SimpleAsyncTask>(Node, MaxNumber);
	MyTask->StartBackgroundTask();



	 MyTask->StartSynchronousTask; 在当前线程执行，可能会导致主线程阻塞S
	//GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Red, TEXT("END111"));

	/* MyTask->IsDone()  可以配合定时器检测是否完成任务

	等待任务完成后，进行手动删除 [下面这段会导致卡顿。 目前没有实现手动删除。还是建议使用自动删除]
	/*MyTask->EnsureCompletion();
	delete MyTask;
	MyTask = nullptr;*/

	return Node;
}


//注意,需要在等待FAsyncTask结束后手动回收,如果FAsyncTask需要一段时间才能结束,可能需要在“Timer”中循环执行下面函数
void UMyAsyncAction::OnTaskFinish()
{
	//使用IsDone()判断task是否完成
	bool bTaskFinished = MyTask->IsDone();
	if (bTaskFinished)
	{
		//手动回收内存
		delete MyTask;
		MyTask = nullptr;
	}
}

void MyAsyncTask::DoWork()
{


	while (CurrentCount < TotalCount)
	{
		/// <summary>
	   /// 判断是否在游戏进程中
	   /// </summary>
		AsyncTask(ENamedThreads::GameThread, [=]()
			{

				//Node->OnSuccess.Broadcast(Actor->Counter);
				CurrentCount++;
				Node->OnSuccess.Broadcast(CurrentCount);
				GEngine->AddOnScreenDebugMessage(-1, 2.0f, FColor::Yellow, FString::Printf(TEXT("this is %d"), CurrentCount), true);

			}
		);

		FPlatformProcess::Sleep(0.1f);
	}


	AsyncTask(ENamedThreads::GameThread, [=]()
		{
			Node->OnFail.Broadcast(-1);
		}
	);

	GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Red, TEXT("ENDAsyncTask"));

	/// <summary>
	/// 跳出就是结束多线程
	/// </summary>
	return;
}

void SimpleAsyncTask::DoWork()
{
	while (CurrentCount < TotalCount)
	{
		/// <summary>
	   /// 判断是否在游戏进程中
	   /// </summary>
		AsyncTask(ENamedThreads::GameThread, [=]()
			{

				//Node->OnSuccess.Broadcast(Actor->Counter);
				CurrentCount++;
				Node->OnSuccess.Broadcast(CurrentCount);
				GEngine->AddOnScreenDebugMessage(-1, 2.0f, FColor::Yellow, FString::Printf(TEXT("this is %d"), CurrentCount), true);
				Node->OnTaskFinish();

			}
		);

		FPlatformProcess::Sleep(0.1f);
	}


	AsyncTask(ENamedThreads::GameThread, [=]()
		{
			Node->OnFail.Broadcast(-1);
		}
	);
	GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Red, TEXT("ENDSimpleAsyncTask"));

	/// <summary>
	/// 跳出就是结束多线程
	/// </summary>
	return;
}

.h


#pragma once

#include "CoreMinimal.h"
#include "Engine/AssetManager.h"
#include "MyAssetManager.generated.h"


DECLARE_DYNAMIC_DELEGATE(FOnAsyncLoadFinished);
/**
 *
 */
UCLASS()
class EDITORTOOLSDEMO_API UMyAssetManager : public UAssetManager
{
	GENERATED_BODY()

		UPROPERTY()
		FString LoadPackagePath;

	bool bIsLoaded;

	UFUNCTION(BlueprintCallable, Category = "AsyncLoadLevelTest")
		void MyAsyncLoad(FSoftObjectPath path, const FOnAsyncLoadFinished& OnAsyncLoadFinished);

	UFUNCTION(BlueprintCallable, Category = "AsyncLoadLevelTest")
		float GetLoadProgress();

};

.cpp



#include "AsyncLoad/MyAssetManager.h"




void UMyAssetManager::MyAsyncLoad(FSoftObjectPath path, const FOnAsyncLoadFinished& OnAsyncLoadFinished)
{

	//LoadPackagePath = FPaths::GetBaseFilename(, LoadPackageSoftObjectPath.ToString(), false);
	LoadPackagePath = path.ToString();
	bIsLoaded = false;

	UE_LOG(LogTemp, Warning, TEXT("String: %s"), *LoadPackagePath);
	LoadPackageAsync(
		LoadPackagePath,
		FLoadPackageAsyncDelegate::CreateLambda([=](const FName& PackageName, UPackage* LoadedPackage, EAsyncLoadingResult::Type Result)
			{
				if (Result == EAsyncLoadingResult::Failed)
				{
					UE_LOG(LogTemp, Warning, TEXT("Load Failed"));
				}
				else if (Result == EAsyncLoadingResult::Succeeded)
				{
					bIsLoaded = true;
					UE_LOG(LogTemp, Warning, TEXT("Load Succeeded"));
					OnAsyncLoadFinished.ExecuteIfBound();
				}
			}), 0, PKG_ContainsMap);

}

float UMyAssetManager::GetLoadProgress()
{
	float FloatPercentage = GetAsyncLoadPercentage(*LoadPackagePath);
	if (!bIsLoaded)
	{
		FString ResultStr = FString::Printf(TEXT("Percentage: %f"), FloatPercentage);
		GEngine->AddOnScreenDebugMessage(-1, 2.0f, FColor::Green, ResultStr);
		UE_LOG(LogTemp, Warning, TEXT("Percentage: %f"), FloatPercentage);
	}
	else {
		FloatPercentage = 100;
	}
	return FloatPercentage;

}


#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "Runtime/Core/Public/Async/TaskGraphInterfaces.h"
#include "AsyncLoadActor.generated.h"

/// <summary>
/// TaskGraph 系统是UE4一套抽象的异步任务处理系统可以创建任意多线程任务， 异步任务， 序列任务， 并行任务等，并可以指定任务顺序， 设置任务间的依赖， 最终形成一个任务图 https://zhuanlan.zhihu.com/p/430187330
/// 特点是操作简单,可以用来进行一些简单的运算,但是复杂运算请使用FRunnable.  https://www.bilibili.com/read/cv9486649?spm_id_from=333.999.0.0 
/// </summary>
class FTaskGraphTest
{


public:
	FTaskGraphTest(int32 TotalCount) :TotalCount(TotalCount) {}
	~FTaskGraphTest() {}

	//最大计数
	int32 TotalCount;
	//初始计数
	int32 CurrentCount = 0;


	// 固定写法
	FORCEINLINE TStatId GetStatId() const
	{
		//第一个参数传入自己创建的TaskGraph类型,第二个参数照写即可 
		RETURN_QUICK_DECLARE_CYCLE_STAT(FTaskGraph_SimpleTask, STATGROUP_TaskGraphTasks);
	}

	// 指定在哪个线程运行 ，该函数返回一个目标线程类型,决定taskgraph运行之后在哪个线程执行.
	static ENamedThreads::Type GetDesiredThread()
	{
		/*
		 *在这里我们返回AnyNormalThreadNormalTask(优先级正常的线程)
		 *额外说明:
		 *1.可选线程有GameThread(主线程),AnyThread(任意线程),AudioThread(音频线程)等等
		 *2.线程逻辑在GameThread执行,可能会阻塞主线程,不可取
		 *3.线程逻辑很明显也不适合在音频线程,渲染线程之类的专职线程上进行
		 *4.AnyThread,字如其名,如果把线程逻辑放到AnyThread线程上执行,那这段线程逻辑有可能会
		 *被随机分配一个线程上执行,运气不好的话,分配渲染,物理,音频线程上执行就会出问题
		 *5.所以我们选择了对AnyThread进行限制,即:
		 *AnyNormalThreadNormalTask = AnyThread | NormalThreadPriority | NormalTaskPriority
		 *具有正常线程优先级和正常任务优先级的线程,这样就会避免线程逻辑运行在错误的线程上
		*/
		return ENamedThreads::AnyNormalThreadNormalTask;
	}

	// 后续执行模式 固定写法
	static ESubsequentsMode::Type GetSubsequentsMode()
	{

		return ESubsequentsMode::TrackSubsequents;
	}

	// 线程逻辑执行函数
	void DoTask(ENamedThreads::Type CurrentThread, const FGraphEventRef& MyCompletionGraphEvent)
	{
		//本例在task中打印从0-TotalCount的数值,每次打印间隔1s
		while (CurrentCount < TotalCount)
		{
			UE_LOG(LogTemp, Warning, TEXT("Current Count :%d"), CurrentCount);
			CurrentCount++;
			FPlatformProcess::Sleep(1.f);
		}
	}
};




/**
 *FRunnable多线程 https://zhuanlan.zhihu.com/p/430187330   & https://blog.csdn.net/u011718663/article/details/118105259#_14
 */
class EDITORTOOLSDEMO_API FSimpleRunnable : public FRunnable
{
public:
	FSimpleRunnable(const FString& ThreadName);
	~FSimpleRunnable();


	void PauseThread();				// 线程挂起 方法一	
	void WakeUpThread();			// 线程唤醒 方法一
	void Suspend(bool bSuspend);	// 线程挂起/唤醒 方法二
	void StopThread();				// 停止线程，一般用该方法
	void ShutDown(bool bShouldWait);// 停止线程，bShouldWait true的时候可强制 kill 线程

private:

	FString m_ThreadName;
	int32 m_ThreadID;
	bool bRun = true;				// 线程循环标志
	bool bPause = false;			//线程挂起标志
	FRunnableThread* ThreadIns;		// 线程实例
	FEvent* ThreadEvent;			//FEvent指针,挂起/激活线程, 在各自的线程内使用


	/// <summary>
	/// FRunnable 4个固有函数
	/// </summary>
	virtual bool Init() override;
	/// <summary>
	/// 执行函数
	/// </summary>
	virtual uint32 Run() override;
	virtual void Stop() override;
	virtual void Exit() override;
};


DECLARE_DYNAMIC_DELEGATE(FOnAsyncLoadLevel);
DECLARE_DYNAMIC_DELEGATE(FOnAsyncLoadFailed);

UCLASS()
class EDITORTOOLSDEMO_API AAsyncLoadActor : public AActor
{
	GENERATED_BODY()

public:
	// Sets default values for this actor's properties
	AAsyncLoadActor();

protected:
	// Called when the game starts or when spawned
	virtual void BeginPlay() override;

public:
	// Called every frame
	virtual void Tick(float DeltaTime) override;

	/// <summary>
	/// TaskGraph生成
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		void CreateTaskGraphSimpleTask(int32 TotalCount);


	/// <summary>
	/// 异步加载关卡 LoadingScreen https://blog.csdn.net/ttod/article/details/127716475 &https://www.bilibili.com/video/BV1Mr4y1A7nZ/?spm_id_from=333.337.search-card.all.click&vd_source=8a96d7f1981e32d11ac0eb4847916c44
	/// </summary>
	bool bIsLoaded;

	/// <summary>
	/// 加载包地址
	/// </summary>
	UPROPERTY(BlueprintReadWrite)
		FString LoadPackagePath;

	//UPROPERTY(EditAnywhere, BlueprintReadWrite)
	//	FSoftObjectPath LoadPackageSoftObjectPath;


	/// <summary>
	/// 生成异步加载关卡绑定回调
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadLevelTest")
		void MyAsyncLoad(FSoftObjectPath path, const FOnAsyncLoadLevel& OnAsyncLoadFinished, const FOnAsyncLoadFailed& OnAsyncLoadFailed);


	/// <summary>
	/// 异步加载关卡进度
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadLevelTest")
		float GetLoadProgress();



	/// <summary>
	/// FRunnable
	/// </summary>
protected:
	virtual void EndPlay(const EEndPlayReason::Type EndPlayReason) override;

private:
	static FSimpleRunnable* MySimpleRunnable; // 声明静态单例

public:

	/// <summary>
	/// FRunnable线程生成
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		void CreateNewThread(const FString& ThreadName);

	/// <summary>
	/// FRunnable线程挂起
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		void PauseThread();

	/// <summary>
	/// FRunnable程挂起/唤醒 方法二
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		void SuspendThread(bool bSuspend);

	/// <summary>
	/// FRunnable线程唤醒
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		void WakeUpThread();

	/// <summary>
	///  FRunnable停止
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		void StopThread();

	/// <summary>
	///  FRunnable强制停止（有概率引起崩溃。建议:使用另一个停止）
	/// </summary>
	UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		void ForceKillThread(bool bShouldWait);


};

FSimpleRunnable* AAsyncLoadActor::MySimpleRunnable = nullptr;

.cpp

#include "AsyncLoad/AsyncLoadActor.h"


// Sets default values
AAsyncLoadActor::AAsyncLoadActor()
{
	// 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 AAsyncLoadActor::BeginPlay()
{
	Super::BeginPlay();

}

// Called every frame
void AAsyncLoadActor::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);

}

void AAsyncLoadActor::EndPlay(const EEndPlayReason::Type EndPlayReason)
{

	if (MySimpleRunnable) // 防止线程挂起，退出无响应
	{
		MySimpleRunnable->StopThread();
		delete MySimpleRunnable;
		MySimpleRunnable = nullptr;
	}
}

void AAsyncLoadActor::CreateNewThread(const FString& ThreadName)
{
	if (MySimpleRunnable == nullptr)
	{
		MySimpleRunnable = new FSimpleRunnable(ThreadName);
	}
}

void AAsyncLoadActor::PauseThread()
{
	if (MySimpleRunnable)
	{
		MySimpleRunnable->PauseThread();
	}
}

void AAsyncLoadActor::SuspendThread(bool bSuspend)
{
	if (MySimpleRunnable)
	{
		MySimpleRunnable->Suspend(bSuspend);
	}
}

void AAsyncLoadActor::WakeUpThread()
{
	if (MySimpleRunnable)
	{
		MySimpleRunnable->WakeUpThread();
	}
}

void AAsyncLoadActor::StopThread()
{
	if (MySimpleRunnable)
	{
		MySimpleRunnable->StopThread();
	}
}

void AAsyncLoadActor::ForceKillThread(bool bShouldWait)
{
	if (MySimpleRunnable)
	{
		MySimpleRunnable->ShutDown(bShouldWait);
		delete MySimpleRunnable;
		MySimpleRunnable = nullptr;
	}

}

FSimpleRunnable::FSimpleRunnable(const FString& ThreadName)
{
	// 获取 FEvent 指针
	ThreadEvent = FPlatformProcess::GetSynchEventFromPool();

	// 创建线程实例
	m_ThreadName = ThreadName;
	ThreadIns = FRunnableThread::Create(this, *m_ThreadName, 0, TPri_Normal);
	m_ThreadID = ThreadIns->GetThreadID();
	UE_LOG(LogTemp, Warning, TEXT("Thread Start! ThreadID = %d"), m_ThreadID);
}

FSimpleRunnable::~FSimpleRunnable()
{
	if (ThreadEvent)	// 清空 FEvent*
	{
		FPlatformProcess::ReturnSynchEventToPool(ThreadEvent); // delete ThreadEvent;
		ThreadEvent = nullptr;
	}
	if (ThreadIns)		// 清空 FRunnableThread*
	{
		delete ThreadIns;
		ThreadIns = nullptr;
	}
}

void FSimpleRunnable::PauseThread()
{
	bPause = true;
	UE_LOG(LogTemp, Warning, TEXT("Thread Pause!"));
}

void FSimpleRunnable::WakeUpThread()
{
	bRun = true;
	bPause = false;
	if (ThreadEvent)
	{
		ThreadEvent->Trigger(); // 唤醒线程
	}
	UE_LOG(LogTemp, Warning, TEXT("Thread Wakeup!"));
}

void FSimpleRunnable::Suspend(bool bSuspend)
{
	if (ThreadIns)
	{
		ThreadIns->Suspend(bSuspend); //挂起/唤醒
	}
}

void FSimpleRunnable::StopThread()
{
	Stop();
}

void FSimpleRunnable::ShutDown(bool bShouldWait)
{
	if (ThreadIns)
	{
		ThreadIns->Suspend(false);
		ThreadIns->Kill(bShouldWait); // bShouldWait 为false，Suspend(true)时，会崩
	}
}

bool FSimpleRunnable::Init()
{
	return true;//若返回 false ,线程创建失败，不会执行后续函数
}

uint32 FSimpleRunnable::Run()
{

	int32 count = 0;
	FPlatformProcess::Sleep(0.03f); //延时，等待初始化完成
	while (bRun)
	{
		if (bPause)
		{
			ThreadEvent->Wait(); // 线程挂起
			if (!bRun)			 // 线程挂起时执行线程结束
			{
				return 0;
			}
		}

		UE_LOG(LogTemp, Warning, TEXT("ThreadID: %d, Count: %d"), m_ThreadID, count);
		count++;
		FPlatformProcess::Sleep(0.1f); // 执行间隔，防止堵塞
	}

	return 0;
}

void FSimpleRunnable::Stop()
{

	bRun = false;
	bPause = false;
	if (ThreadEvent)
	{
		ThreadEvent->Trigger(); // 保证线程不挂起
	}

	GEngine->AddOnScreenDebugMessage(-1, 10.0f, FColor::Yellow, FString::Printf(TEXT("Stop")), true);

}

void FSimpleRunnable::Exit()
{
	GEngine->AddOnScreenDebugMessage(-1, 10.0f, FColor::Yellow, FString::Printf(TEXT("Exit")), true);
}



/// <summary>
/// TaskGraph
/// </summary>
void AAsyncLoadActor::CreateTaskGraphSimpleTask(int32 TotalCount)
{

	/*
   *第一个参数默认值为NULL
   *第二个参数为线程逻辑运行的线程,上面已经介绍过
   *ConstructAndDIspatchWhenReady会调用创建的TaskGraph类型(本例中为FTaskGraph)的构造函数,只需要按照构造
   *函数参数列表传入参数即可完成TaskGraph的初始化
  */
	TGraphTask<FTaskGraphTest>::CreateTask().ConstructAndDispatchWhenReady(TotalCount);
}



/// </summary>
/// <param name="path">地址</param>
/// <param name="OnAsyncLoadFinished">成功回调</param>
/// <param name="OnAsyncLoadFaile">失败回调</param>
void AAsyncLoadActor::MyAsyncLoad(FSoftObjectPath path, const FOnAsyncLoadLevel& OnAsyncLoadFinished, const FOnAsyncLoadFailed& OnAsyncLoadFaile)
{
	//LoadPackagePath = FPaths::GetBaseFilename(LoadPackageSoftObjectPath.ToString(), false);
	LoadPackagePath = FPaths::GetBaseFilename(path.ToString(), false);

	bIsLoaded = false;

	UE_LOG(LogTemp, Warning, TEXT("String: %s"), *LoadPackagePath);
	//UE_LOG(LogTemp, Warning, TEXT("String2: %s"), *LoadPackagePath2);
	LoadPackageAsync(
		LoadPackagePath,
		FLoadPackageAsyncDelegate::CreateLambda([=](const FName& PackageName, UPackage* LoadedPackage, EAsyncLoadingResult::Type Result)
			{
				if (Result == EAsyncLoadingResult::Failed)
				{
					UE_LOG(LogTemp, Warning, TEXT("Load Failed"));
					OnAsyncLoadFaile.ExecuteIfBound();
				}
				else if (Result == EAsyncLoadingResult::Succeeded)
				{
					bIsLoaded = true;
					UE_LOG(LogTemp, Warning, TEXT("Load Succeeded"));
					OnAsyncLoadFinished.ExecuteIfBound();
				}
			}), 0, PKG_ContainsMap);
}

float AAsyncLoadActor::GetLoadProgress()
{
	/// <summary>
	/// 加载资产进度
	/// </summary>
	/// <returns>资产路径</returns>
	float FloatPercentage = GetAsyncLoadPercentage(*LoadPackagePath);
	if (!bIsLoaded)
	{
		FString ResultStr = FString::Printf(TEXT("Percentage: %f"), FloatPercentage);
		GEngine->AddOnScreenDebugMessage(-1, 2.0f, FColor::Green, ResultStr);
		UE_LOG(LogTemp, Warning, TEXT("Percentage: %f"), FloatPercentage);
	}
	else {
		FloatPercentage = 100;
	}
	return FloatPercentage;
}

.h


#pragma once

#include "CoreMinimal.h"
#include "Kismet/BlueprintFunctionLibrary.h"
#include "AsyncLoadFunctionLibrary.generated.h"


DECLARE_DYNAMIC_DELEGATE_OneParam(FAsyncTaskDelegate, int, IntOut);
/**
 * https://zhuanlan.zhihu.com/p/430187330
 */
UCLASS()
class EDITORTOOLSDEMO_API UAsyncLoadFunctionLibrary : public UBlueprintFunctionLibrary
{
	GENERATED_BODY()

		/// <summary>
		/// 使用AsyncTask 
		/// </summary>
		UFUNCTION(BlueprintCallable, Category = "AsyncLoadTest")
		static void AsyncPrimeCount(FAsyncTaskDelegate Out, int32 PrimeCount);



};

.cpp

#include "AsyncLoad/AsyncLoadFunctionLibrary.h"

void UAsyncLoadFunctionLibrary::AsyncPrimeCount(FAsyncTaskDelegate Out, int32 PrimeCount)
{
	// Schedule a thread                               // Pass in our parameters to the lambda expression
	AsyncTask(ENamedThreads::AnyHiPriThreadNormalTask, [Out, PrimeCount]()
		{

			//整个代码只是循环数字并计算它找到了多少质数
			int PrimesFound = 0;
			int TestNumber = 2;

			/*	while (PrimesFound< PrimeCount)
				{
					TestNumber++;
					Out.ExecuteIfBound(TestNumber);

					/// <summary>
					/// 等待0.1秒再执行下一次
					/// </summary>
					FPlatformProcess::Sleep(0.1f);
				}
				return;*/
			while (PrimesFound < PrimeCount)
			{
				bool bIsPrime = true;

				for (int i = 2; i < TestNumber / 2; i++)
				{
					if (TestNumber % i == 0)
					{
						bIsPrime = false;
						break;
					}
				}

				if (bIsPrime)
				{
					PrimesFound++;

					// 每1000个质数

					if (PrimesFound % 1000 == 0)
					{
						//回到主线程并传递参数
						AsyncTask(ENamedThreads::GameThread, [Out, PrimesFound]()
							{
								// 执行委托和参数
								Out.ExecuteIfBound(PrimesFound);
							});
					}
				}
				TestNumber++;
			}
		});
}

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