TickableObjectRenderThread.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Stats/Stats.h"
 
class FRHICommandListImmediate;
 
class FTickableObjectRenderThread
{
public:
 
    struct FRenderingThreadTickableObjectsArray : public TArray<FTickableObjectRenderThread*>
    {
        ~FRenderingThreadTickableObjectsArray()
        {
            // if there are any Tickable objects left registered at this point, force them to unregister
            int32 MaxIterations = Num();    // prevents runaway loop (extra safety)
            while(Num() > 0 && MaxIterations-- > 0)
            {
                FTickableObjectRenderThread* Object = Top();
                check(Object);
                Object->Unregister();
            }
            // if we exited uncleanly from a runaway loop, crash explicitly in Dev
            check(Num() == 0);
        }
    };
 
    static RENDERCORE_API FRenderingThreadTickableObjectsArray RenderingThreadTickableObjects;
    static RENDERCORE_API FRenderingThreadTickableObjectsArray RenderingThreadHighFrequencyTickableObjects;
 
    FTickableObjectRenderThread(bool bRegisterImmediately=true, bool bInHighFrequency=false)
        : bHighFrequency(bInHighFrequency)
    {
        if(bRegisterImmediately)
        {
            Register();
        }
    }
 
    virtual ~FTickableObjectRenderThread()
    {
        Unregister();
    }
 
    void Unregister()
    {
        if (bRegistered)
        {
            // make sure this tickable object was registered from the rendering thread
            checkf(IsInRenderingThread(), TEXT("Game thread attempted to unregister an object in the RenderingThreadTickableObjects array."));
 
            FRenderingThreadTickableObjectsArray& TickableObjectArray = bHighFrequency ? RenderingThreadHighFrequencyTickableObjects : RenderingThreadTickableObjects;
            const int32 Pos = TickableObjectArray.Find(this);
            check(Pos!=INDEX_NONE);
            TickableObjectArray.RemoveAt(Pos);
            bRegistered = false;
        }
    }
 
    void Register()
    {
        // make sure that only the rendering thread is attempting to add items to the RenderingThreadTickableObjects list
        checkf(IsInRenderingThread(), TEXT("Game thread attempted to register an object in the RenderingThreadTickableObjects array."));
        check(!RenderingThreadTickableObjects.Contains(this));
        check(!RenderingThreadHighFrequencyTickableObjects.Contains(this));
        check(!bRegistered);
        if (bHighFrequency)
        {
            RenderingThreadHighFrequencyTickableObjects.Add(this);
        }
        else
        {
            RenderingThreadTickableObjects.Add(this);
        }       
        bRegistered = true;
    }
 
    UE_DEPRECATED(5.7, "bIsRenderingThreadObject argument is no longer needed")
    void Register(bool bIsRenderingThreadObject)
    {
        Register();
    }
 
    virtual void Tick(FRHICommandListImmediate& RHICmdList, float DeltaTime) = 0;
 
    virtual TStatId GetStatId() const = 0;
 
    virtual bool IsTickable() const = 0;
 
    virtual bool NeedsRenderingResumedForRenderingThreadTick() const
    {
        return false;
    }
 
private:
    bool bRegistered = false;
    const bool bHighFrequency;
};
 
extern RENDERCORE_API void TickRenderingTickables(FRHICommandListImmediate& RHICmdList);
 
UE_DEPRECATED(5.7, "TickRenderingTickables needs a command list")
extern RENDERCORE_API void TickRenderingTickables();