MovieSceneMaybeAtomic.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "HAL/PlatformAtomics.h"
#include "Templates/UnrealTemplate.h"
 
namespace UE
{
namespace MovieScene
{
 
enum class EEntityThreadingModel : uint8
{
    NoThreading,
 
    TaskGraph,
};
 
struct FEntitySystemMaybeAtomicInt32 final
{
    FEntitySystemMaybeAtomicInt32() = default;
    FEntitySystemMaybeAtomicInt32(int32 Payload) : Payload(Payload) {}
 
    int32 Load(EEntityThreadingModel ThreadingModel) const
    {
        if (EEntityThreadingModel::NoThreading == ThreadingModel)
        {
            return Payload;
        }
        else
        {
            return FPlatformAtomics::AtomicRead(&Payload);
        }
    }
 
    int32 Add(EEntityThreadingModel ThreadingModel, const int32 Value)
    {
        if (EEntityThreadingModel::NoThreading == ThreadingModel)
        {
            const int32 Old = Payload;
            Payload += Value;
            return Old;
        }
        else
        {
            return FPlatformAtomics::InterlockedAdd(&Payload, Value);
        }
    }
 
    int32 Sub(EEntityThreadingModel ThreadingModel, const int32 Value)
    {
        if (EEntityThreadingModel::NoThreading == ThreadingModel)
        {
            const int32 Old = Payload;
            Payload -= Value;
            return Old;
        }
        else
        {
            return FPlatformAtomics::InterlockedAdd(&Payload, -Value);
        }
    }
 
    int32 Exchange(EEntityThreadingModel ThreadingModel, int32 Other)
    {
        if (EEntityThreadingModel::NoThreading == ThreadingModel)
        {
            Swap(Payload, Other);
            return Other;
        }
        else
        {
            return FPlatformAtomics::InterlockedExchange(&Payload, Other);
        }
    }
 
    int32 Increment(EEntityThreadingModel ThreadingModel)
    {
        if (EEntityThreadingModel::NoThreading == ThreadingModel)
        {
            return Payload++;
        }
        else
        {
            return FPlatformAtomics::InterlockedIncrement(&Payload);
        }
    }
 
    int32 Decrement(EEntityThreadingModel ThreadingModel)
    {
        if (EEntityThreadingModel::NoThreading == ThreadingModel)
        {
            return Payload--;
        }
        else
        {
            return FPlatformAtomics::InterlockedDecrement(&Payload);
        }
    }
 
private:
    int32 Payload = 0;
};
 
} // namespace MovieScene
} // namespace UE