MetalFence.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
 
#pragma once
 
#include "MetalRHIPrivate.h"
#include "Containers/LockFreeList.h"
 
#pragma clang diagnostic ignored "-Wnullability-completeness"
 
class FMetalFence
{
public:
    FMetalFence()
    : NumRefs(0)
    {
        Reset();
    }
    
    explicit FMetalFence(FMetalFence const& Other)
    : NumRefs(0)
    {
        operator=(Other);
    }
    
    ~FMetalFence()
    {
        check(!NumRefs);
    }
    
    uint32 AddRef() const
    {
        return uint32(FPlatformAtomics::InterlockedIncrement(&NumRefs));
    }
    uint32 Release() const;
    uint32 GetRefCount() const
    {
        return uint32(FPlatformAtomics::AtomicRead(&NumRefs));
    }
    
    FMetalFence& operator=(FMetalFence const& Other)
    {
        if (&Other != this)
        {
            Fence = Other.Fence;
        }
        return *this;
    }
    
    void Reset(void)
    {
        WriteNum = 0;
        WaitNum = 0;
    }
    
    void Write()
    {
        WriteNum++;
    }
    
    void Wait()
    {
        WaitNum++;
    }
    
    int8 NumWrite() const
    {
        return WriteNum;
    }
    
    int8 NumWait() const
    {
        return WaitNum;
    }
    
    MTL::Fence* Get() const
    {
        return Fence;
    }
    
    void Set(MTL::Fence* InFence)
    {
        Fence = InFence;
    }
    
private:
    MTL::Fence* Fence;
    int8 WriteNum;
    int8 WaitNum;
    mutable int32 NumRefs;  
};
 
class FMetalFencePool
{
    enum
    {
        NumFences = 2048
    };
public:
    FMetalFencePool() {}
    
    static FMetalFencePool& Get()
    {
        static FMetalFencePool sSelf;
        return sSelf;
    }
    
    void Initialise(MTL::Device* InDevice);
    
    FMetalFence* AllocateFence();
    void ReleaseFence(FMetalFence* InFence);
    
    int32 Max() const { return Count; }
    int32 Num() const { return Allocated; }
    
private:
    int32 Count;
    int32 Allocated;
    MTL::Device* Device;
#if METAL_DEBUG_OPTIONS
    TSet<FMetalFence*> Fences;
    FCriticalSection Mutex;
#endif
    TLockFreePointerListFIFO<FMetalFence, PLATFORM_CACHE_LINE_SIZE> Lifo;
};