ObjectScopeHysteresisUpdater.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Containers/Array.h"
#include "Containers/Map.h"
#include "Net/Core/NetBitArray.h"
 
namespace UE::Net::Private
{
    typedef uint32 FInternalNetRefIndex;
}
 
namespace UE::Net::Private
{
 
class FObjectScopeHysteresisUpdater
{
public:
    void Init(uint32 MaxObjectCount);
    void Deinit();
 
    void OnMaxInternalNetRefIndexIncreased(FInternalNetRefIndex NewMaxInternalIndex);
 
    void SetHysteresisFrameCount(FInternalNetRefIndex NetRefIndex, uint16 HysteresisFrameCount);
 
    void RemoveHysteresis(FInternalNetRefIndex NetRefIndex);
 
    void RemoveHysteresis(const FNetBitArrayView& ObjectsToRemove);
 
    void RemoveHysteresis(TArrayView<const uint32> ObjectsToRemove);
 
    void Update(uint8 FramesSinceLastUpdate, TArray<FInternalNetRefIndex>& OutObjectsToFilterOut);
 
    bool HasObjectsToUpdate() const;
 
    FNetBitArrayView GetUpdatedObjects() const;
 
    bool IsObjectUpdated(FInternalNetRefIndex NetRefIndex) const;
 
private:
    enum : unsigned
    {
        LocalIndexGrowCount = 256U,
    };
 
    typedef uint32 FLocalIndex;
 
    FLocalIndex GetOrCreateLocalIndex(FInternalNetRefIndex NetRefIndex);
    void FreeLocalIndex(FLocalIndex LocalIndex);
 
    // Per LocalIndex how many frames left to update before filtering out the object.
    TArray<uint16> FrameCounters;
    // Lookup table for local index to InternalNetRefIndex.
    TArray<FInternalNetRefIndex> LocalIndexToNetRefIndex;
    // Lookup map for InternalNetRefIndex to LocalIndex to be able to figure out whether an object already is assigned a LocalIndex or not.
    TMap<FInternalNetRefIndex, FLocalIndex> NetRefIndexToLocalIndex;
    // A set bit indicates that the LocalIndex is used. Only stores MaxLocalIndex bits. The bitarray grows as needed.
    FNetBitArray UsedLocalIndices;
    // A set bit indicates that the InternalNetRefIndex is being updated. Can always hold the MaxObjectCount passed to Init().
    FNetBitArray ObjectsToUpdate;
};
 
inline bool FObjectScopeHysteresisUpdater::HasObjectsToUpdate() const
{
    return !NetRefIndexToLocalIndex.IsEmpty();
}
 
inline FNetBitArrayView FObjectScopeHysteresisUpdater::GetUpdatedObjects() const
{
    return MakeNetBitArrayView(ObjectsToUpdate);
}
 
inline bool FObjectScopeHysteresisUpdater::IsObjectUpdated(FInternalNetRefIndex ObjectIndex) const
{
    return ObjectsToUpdate.GetBit(ObjectIndex);
}
 
}