FilePackageStore.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "IO/PackageId.h"
#include "Serialization/PackageStore.h"
#include "Misc/PackagePath.h"
 
struct FIoContainerHeader;
struct FFilePackageStoreEntry;
struct FFilePackageStoreEntrySoftReferences;
 
namespace UE::FilePackageStorePrivate
{
    
struct FMountedDataRange
{
    bool Contains(uint32 Offset) const { return Offset >= Begin && Offset <= End; }
 
    uint32 Begin = 0;
    uint32 End = 0;
};
 
struct FMountedContainer
{
    FIoContainerHeader* ContainerHeader;
    uint32 Order;
    uint32 Sequence;
    uint32 NumMountedPackages = 0;
    FMountedDataRange EntryDataRange;
};
 
struct FEntryHandle
{
    static constexpr uint32 OffsetBits = 29;
 
    uint32 Offset : OffsetBits;
    uint32 HasPackageIds : 1;
    uint32 HasShaderMaps : 1;
    uint32 HasSoftRefs : 1;
 
    FEntryHandle()
    {
        FMemory::Memzero(*this);
    }
};
 
// Memory-optimized immutable FPackageId -> FEntryHandle hash map
class FPackageIdMap
{
public:
    FPackageIdMap() = default;
    explicit FPackageIdMap(TArray<TPair<FPackageId, FEntryHandle>>&& Pairs);
    FPackageIdMap(FPackageIdMap&& O) { *this = MoveTemp(O); }
    FPackageIdMap& operator=(FPackageIdMap&& O);
    ~FPackageIdMap() { Empty(); }
    
    void Empty();
    const FEntryHandle* Find(FPackageId Key) const;
    uint32 GetCapacity() const { return MaxValues; }
    uint64 GetAllocatedSize() const;
    class FConstIterator;
 
private:
    uint32 MaxValues = 0;
    uint32 SlotBits = 0;
    uint32* Slots = nullptr;
    uint16* Values = nullptr;
    
    uint32 NumSlots() const
    {
        return SlotBits ? (1u << SlotBits) : 0u;
    }
};
 
struct FUncookedPackage
{
    FName PackageName;
    EPackageExtension HeaderExtension;
};
 
} // namespace UE::FilePackageStorePrivate
 
/*
 * File/container based package store.
 */
class FFilePackageStoreBackend final : public IPackageStoreBackend
{
public:
    virtual void OnMounted(TSharedRef<const FPackageStoreBackendContext>) override {}
    virtual void BeginRead() override;
    virtual void EndRead() override;
    virtual EPackageStoreEntryStatus GetPackageStoreEntry(FPackageId PackageId, FName PackageName, FPackageStoreEntry& OutPackageStoreEntry) override;
    virtual bool GetPackageRedirectInfo(FPackageId PackageId, FName& OutSourcePackageName, FPackageId& OutRedirectedToPackageId) override;
    virtual TConstArrayView<uint32> GetSoftReferences(FPackageId PackageId, TConstArrayView<FPackageId>& OutPackageIds) override;
 
    void Mount(FIoContainerHeader* ContainerHeader, uint32 Order);
    void Unmount(const FIoContainerHeader* ContainerHeader);
 
private:
    using FMountedDataRange = UE::FilePackageStorePrivate::FMountedDataRange;
    using FMountedContainer = UE::FilePackageStorePrivate::FMountedContainer;
    using FEntryHandle = UE::FilePackageStorePrivate::FEntryHandle;
    using FPackageIdMap = UE::FilePackageStorePrivate::FPackageIdMap;
    using FUncookedPackage = UE::FilePackageStorePrivate::FUncookedPackage;
 
    FRWLock EntriesLock;
    FCriticalSection UpdateLock;
    TArray<FMountedContainer> MountedContainers;
    TAtomic<uint32> NextSequence{ 0 };
 
    FPackageIdMap PackageEntries;
    TArray<uint32> EntryData;
    TMap<FPackageId, TTuple<FName, FPackageId>> RedirectsPackageMap;
    TMap<FPackageId, FName> LocalizedPackages;
    bool bNeedsContainerUpdate = false;
 
#if WITH_EDITOR
    FDelegateHandle OnContentPathMountedDelegateHandle;
    FDelegateHandle OnContentPathDismountedDelegateHandle;
    FCriticalSection UncookedPackageRootsLock;
    TSet<FString> PendingAddUncookedPackageRoots;
    TSet<FString> PendingRemoveUncookedPackageRoots;
    TMap<FPackageId, FUncookedPackage> UncookedPackagesMap;
    TMap<FPackageId, const FFilePackageStoreEntry*> OptionalSegmentStoreEntriesMap;
    bool bNeedsUncookedPackagesUpdate = false;
 
    uint64 AddUncookedPackagesFromRoot(const FString& RootPath);
    uint64 RemoveUncookedPackagesFromRoot(const TSet<FString>& RootPath);
#endif //if WITH_EDITOR
 
    void Update();
    FEntryHandle AddNewEntryData(const FFilePackageStoreEntry& Entry, const FFilePackageStoreEntrySoftReferences* SoftReferences);
    FEntryHandle AddOldEntryData(FEntryHandle OldHandle, TConstArrayView<uint32> OldEntryData);
    TConstArrayView<FPackageId> GetImportedPackages(FEntryHandle Handle);
    TConstArrayView<FSHAHash> GetShaderHashes(FEntryHandle Handle);
    TConstArrayView<uint32> GetSoftReferenceIndices(FEntryHandle Handle);
};