Oversubscription.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
 
namespace LowLevelTasks::Private
{
 
class FOversubscriptionTls
{
    static thread_local bool bIsOversubscriptionAllowed;
 
    friend class FOversubscriptionAllowedScope;
 
    CORE_API static bool& GetIsOversubscriptionAllowedRef();
 
public:
    static bool IsOversubscriptionAllowed() { return bIsOversubscriptionAllowed; }
};
 
class FOversubscriptionAllowedScope
{
    UE_NONCOPYABLE(FOversubscriptionAllowedScope);
 
public:
    explicit FOversubscriptionAllowedScope(bool bIsOversubscriptionAllowed)
        : bValue(FOversubscriptionTls::GetIsOversubscriptionAllowedRef())
        , bPreviousValue(bValue)
    {
        bValue = bIsOversubscriptionAllowed;
    }
 
    ~FOversubscriptionAllowedScope()
    {
        bValue = bPreviousValue;
    }
 
private:
    bool& bValue;
    bool bPreviousValue;
};
 
} // LowLevelTasks::Private
 
namespace LowLevelTasks
{
 
class FOversubscriptionScope
{
    UE_NONCOPYABLE(FOversubscriptionScope);
 
public:
    explicit FOversubscriptionScope(bool bCondition = true)
    {
        if (bCondition)
        {
            TryIncrementOversubscription();
        }
    }
 
    ~FOversubscriptionScope()
    {
        if (bIncrementOversubscriptionEmitted)
        {
            DecrementOversubscription();
        }
    }
 
private:
    CORE_API void TryIncrementOversubscription();
    CORE_API void DecrementOversubscription();
 
    bool bIncrementOversubscriptionEmitted = false;
    bool bCpuBeginEventEmitted = false;
};
 
} // LowLevelTests