DeltaCompressionBaselineStorage.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Array.h"
#include "Containers/ChunkedArray.h"
#include "Net/Core/NetBitArray.h"
#include "Iris/ReplicationSystem/DeltaCompression/DeltaCompressionBaseline.h"
 
namespace UE::Net
{
    class FReplicationStateStorage;
}
 
namespace UE::Net::Private
{
 
using DeltaCompressionBaselineStateInfoIndexType = uint32;
 
constexpr DeltaCompressionBaselineStateInfoIndexType InvalidDeltaCompressionBaselineStateInfoIndex = 0;
 
struct FDeltaCompressionBaselineStorageInitParams
{
    FReplicationStateStorage* ReplicationStateStorage = nullptr;
    uint32 MaxBaselineCount = 0;
};
 
class FDeltaCompressionBaselineStateInfo
{
public:
    bool IsValid() const { return StateBuffer != nullptr; }
 
    uint8* StateBuffer = nullptr;
    DeltaCompressionBaselineStateInfoIndexType StateInfoIndex = InvalidDeltaCompressionBaselineStateInfoIndex;
};
 
 
class FDeltaCompressionBaselineStorage
{
public:
    FDeltaCompressionBaselineStorage();
    ~FDeltaCompressionBaselineStorage();
 
    void Init(FDeltaCompressionBaselineStorageInitParams& InitParams);
    void Deinit();
 
    FDeltaCompressionBaselineStateInfo CreateBaselineFromCurrentState(uint32 ObjectIndex);
    void AddRefBaseline(DeltaCompressionBaselineStateInfoIndexType StateInfoIndex);
    void ReleaseBaseline(DeltaCompressionBaselineStateInfoIndexType StateInfoIndex);
    /* GetBaseline requires the StateInfoIndex to point to a created baseline, not one that is just reserved. */
    FDeltaCompressionBaselineStateInfo GetBaseline(DeltaCompressionBaselineStateInfoIndexType StateInfoIndex) const;
 
    /*
     * Reserves a baseline for the current state. The returned info will contain a pointer to the current state.
     * OptionallyCommitAndReleaseBaseline needs to be called later which will clone the current state if there are
     * references after decrementing the ref count. AddRefBaseline and ReleaseBaseline may be called in between
     * the first call to ReserveBaselineForCurrentState and a call to OptionallyCommitAndDoReleaseBaseline.
     */
    FDeltaCompressionBaselineStateInfo ReserveBaselineForCurrentState(uint32 ObjectIndex);
    /* Decrements the ref count on the baseline and frees associated storage if it's zero and clones the current state if it's still referenced.  */
    void OptionallyCommitAndDoReleaseBaseline(DeltaCompressionBaselineStateInfoIndexType StateInfoIndex);
    /* When you want to retrieve the info for a reserved baseline when GetBaseline() cannot be used. */
    FDeltaCompressionBaselineStateInfo GetBaselineReservationForCurrentState(DeltaCompressionBaselineStateInfoIndexType StateInfoIndex);
 
 
private:
    enum : unsigned
    {
        BaselineStateInfoGrowCount = 256U,
    };
 
    struct FInternalBaselineStateInfo
    {
        uint8* StateBuffer = nullptr;
        uint32 ObjectIndex = 0;
        uint32 RefCount = 1;
    };
 
    void ConstructBaselineStateInfo(FInternalBaselineStateInfo* BaselineStateInfo) const;
    void DestructBaselineStateInfo(FInternalBaselineStateInfo* BaselineStateInfo);
 
    DeltaCompressionBaselineStateInfoIndexType AllocBaselineStateInfo();
    void FreeBaselineStateInfo(DeltaCompressionBaselineStateInfoIndexType StateInfoIndex);
    void FreeAllBaselineStateInfos();
 
    FInternalBaselineStateInfo* GetBaselineStateInfo(DeltaCompressionBaselineStateInfoIndexType StateInfoIndex);
    const FInternalBaselineStateInfo* GetBaselineStateInfo(DeltaCompressionBaselineStateInfoIndexType StateInfoIndex) const;
 
private:
    FNetBitArray UsedBaselineStateInfos;
    TChunkedArray<FInternalBaselineStateInfo, BaselineStateInfoGrowCount*sizeof(FInternalBaselineStateInfo)> BaselineStateInfos;
    FReplicationStateStorage* ReplicationStateStorage = nullptr;
};
 
inline FDeltaCompressionBaselineStorage::FInternalBaselineStateInfo* FDeltaCompressionBaselineStorage::GetBaselineStateInfo(uint32 StateInfoIndex)
{
    return &BaselineStateInfos[StateInfoIndex];
}
 
inline const FDeltaCompressionBaselineStorage::FInternalBaselineStateInfo* FDeltaCompressionBaselineStorage::GetBaselineStateInfo(uint32 StateInfoIndex) const
{
    return &BaselineStateInfos[StateInfoIndex];
}
 
}