[UE4]Engine Source Analysis

keywords: [UE4]Engine Source Analysis - Load Object

Callstack from FStreamableManager::LoadSynchronous to FUObjectHashTables::AddObject:

UE4Editor-CoreUObject.dll!HashObject(UObjectBase * Object) Line 904    
UE4Editor-CoreUObject.dll!UObjectBase::AddObject(FName InName, EInternalObjectFlags InSetInternalFlags) Line 246    
UE4Editor-CoreUObject.dll!UObjectBase::UObjectBase(UClass * InClass, EObjectFlags InFlags, EInternalObjectFlags InInternalFlags, UObject * InOuter, FName InName) Line 102    
UE4Editor-CoreUObject.dll!StaticAllocateObject(UClass * InClass, UObject * InOuter, FName InName, EObjectFlags InFlags, EInternalObjectFlags InternalSetFlags, bool bCanRecycleSubobjects, bool * bOutRecycledSubobject) Line 2434    
UE4Editor-CoreUObject.dll!StaticConstructObject_Internal(UClass * InClass, UObject * InOuter, FName InName, EObjectFlags InFlags, EInternalObjectFlags InternalSetFlags, UObject * InTemplate, bool bCopyTransientsFromClassDefaults, FObjectInstancingGraph * InInstanceGraph, bool bAssumeTemplateIsArchetype) Line 3161    
[Inline Frame] UE4Editor-CoreUObject.dll!NewObject(UObject * Outer, FName) Line 1164    
UE4Editor-CoreUObject.dll!CreatePackage(UObject * InOuter, const wchar_t * PackageName) Line 645    
UE4Editor-CoreUObject.dll!GetPackageLinker(UPackage * InOuter, const wchar_t * InLongPackageName, unsigned int LoadFlags, UPackageMap * Sandbox, FGuid * CompatibleGuid) Line 642    
UE4Editor-CoreUObject.dll!LoadPackageInternal(UPackage * InOuter, const wchar_t * InLongPackageNameOrFilename, unsigned int LoadFlags, FLinkerLoad * ImportLinker) Line 1240    
UE4Editor-CoreUObject.dll!LoadPackage(UPackage * InOuter, const wchar_t * InLongPackageName, unsigned int LoadFlags) Line 1436    
UE4Editor-CoreUObject.dll!ResolveName(UObject * & InPackage, FString & InOutName, bool Create, bool Throw, unsigned int LoadFlags) Line 792    
UE4Editor-CoreUObject.dll!StaticLoadObjectInternal(UClass * ObjectClass, UObject * InOuter, const wchar_t * InName, const wchar_t * Filename, unsigned int LoadFlags, UPackageMap * Sandbox, bool bAllowObjectReconciliation) Line 880    
UE4Editor-CoreUObject.dll!StaticLoadObject(UClass * ObjectClass, UObject * InOuter, const wchar_t * InName, const wchar_t * Filename, unsigned int LoadFlags, UPackageMap * Sandbox, bool bAllowObjectReconciliation) Line 947    
UE4Editor-Engine.dll!FStreamableManager::StreamInternal(const FSoftObjectPath & InTargetName, int Priority, TSharedRef<FStreamableHandle,0> Handle) Line 786    
UE4Editor-Engine.dll!FStreamableManager::StartHandleRequests(TSharedRef<FStreamableHandle,0> Handle) Line 989    
UE4Editor-Engine.dll!FStreamableManager::RequestAsyncLoad(const TArray<FSoftObjectPath,FDefaultAllocator> & TargetsToStream, TBaseDelegate<void> DelegateToCall, int Priority, bool bManageActiveHandle, bool bStartStalled, const FString & DebugName) Line 936    
UE4Editor-Engine.dll!FStreamableManager::RequestSyncLoad(const TArray<FSoftObjectPath,FDefaultAllocator> & TargetsToStream, bool bManageActiveHandle, const FString & DebugName) Line 962    
UE4Editor-Engine.dll!FStreamableManager::RequestSyncLoad(const FSoftObjectPath & TargetToStream, bool bManageActiveHandle, const FString & DebugName) Line 979    
UE4Editor-Engine.dll!FStreamableManager::LoadSynchronous(const FSoftObjectPath & Target, bool bManageActiveHandle, TSharedPtr<FStreamableHandle,0> * RequestHandlePointer) Line 1012

Callstack from ConditionalCollectGarbage to FUObjectHashTables::RemoveObject:

UE4Editor-CoreUObject.dll!UnhashObject(UObjectBase * Object) Line 934    
UE4Editor-CoreUObject.dll!UObjectBase::LowLevelRename(FName NewName, UObject * NewOuter) Line 259    
UE4Editor-CoreUObject.dll!UObject::BeginDestroy() Line 721    
UE4Editor-CoreUObject.dll!UObject::ConditionalBeginDestroy() Line 884    
UE4Editor-CoreUObject.dll!CollectGarbageInternal(EObjectFlags KeepFlags, bool bPerformFullPurge) Line 1496    
UE4Editor-CoreUObject.dll!TryCollectGarbage(EObjectFlags KeepFlags, bool bPerformFullPurge) Line 1560    
UE4Editor-Engine.dll!UEngine::ConditionalCollectGarbage() Line 1072    
UE4Editor-Engine.dll!UWorld::Tick(ELevelTick TickType, float DeltaSeconds) Line 1612    
UE4Editor-UnrealEd.dll!UEditorEngine::Tick(float DeltaSeconds, bool bIdleMode) Line 1481    
UE4Editor-UnrealEd.dll!UUnrealEdEngine::Tick(float DeltaSeconds, bool bIdleMode) Line 401    
UE4Editor.exe!FEngineLoop::Tick() Line 3320    
[Inline Frame] UE4Editor.exe!EngineTick() Line 62

Callstack from LoadSynchronous to FAsyncLoadEventQueue::AddAsyncEvent:

FAsyncLoadEventQueue::AddAsyncEvent(int32 UserPriority, int32 PackageSerialNumber, int32 EventSystemPriority, TFunction<void(FAsyncLoadEventArgs& Args)>&& Payload) Line CoreUObject\Private\Serialization\AsyncLoadingThread.h(88)
FAsyncLoadingThread::QueueEvent_CreateLinker(FAsyncPackage * Package, int EventSystemPriority) Line CoreUObject\Private\Serialization\AsyncLoading.cpp(1360)
FAsyncLoadingThread::InsertPackage(FAsyncPackage * Package, bool bReinsert, FAsyncLoadingThread::EAsyncPackageInsertMode InsertMode) Line CoreUObject\Private\Serialization\AsyncLoading.cpp(4046)
FAsyncPackage::LoadImports_Event() Line CoreUObject\Private\Serialization\AsyncLoading.cpp(1843)
FAsyncPackage::Event_StartImportPackages() Line CoreUObject\Private\Serialization\AsyncLoading.cpp(1616)
FAsyncLoadingThread::QueueEvent_StartImportPackages::__l2::<lambda>(FAsyncLoadEventArgs & Args) Line CoreUObject\Private\Serialization\AsyncLoading.cpp(1606)
UE4Function_Private::TFunctionRefCaller<void <lambda>(FAsyncLoadEventArgs &),void __cdecl(FAsyncLoadEventArgs &)>::Call(void * Obj, FAsyncLoadEventArgs & <Params_0>) Line Core\Public\Templates\Function.h(549)
UE4Function_Private::TFunctionRefBase<UE4Function_Private::TFunctionStorage<0>,void __cdecl(FAsyncLoadEventArgs &)>::operator()(FAsyncLoadEventArgs & <Params_0>) Line Core\Public\Templates\Function.h(677)
FAsyncLoadEventQueue::PopAndExecute(FAsyncLoadEventArgs & Args) Line CoreUObject\Private\Serialization\AsyncLoadingThread.h(109)
FAsyncLoadingThread::ProcessAsyncLoading(int & OutPackagesProcessed, bool bUseTimeLimit, bool bUseFullTimeLimit, float TimeLimit, FFlushTree * FlushTree) Line CoreUObject\Private\Serialization\AsyncLoading.cpp(4150)
FAsyncLoadingThread::TickAsyncThread(bool bUseTimeLimit, bool bUseFullTimeLimit, float TimeLimit, bool & bDidSomething, FFlushTree * FlushTree) Line CoreUObject\Private\Serialization\AsyncLoading.cpp(4936)
FAsyncLoadingThread::TickAsyncLoading(bool bUseTimeLimit, bool bUseFullTimeLimit, float TimeLimit, FFlushTree * FlushTree) Line CoreUObject\Private\Serialization\AsyncLoading.cpp(4636)
FAsyncLoadingThread::FlushLoading(int PackageID) Line CoreUObject\Private\Serialization\AsyncLoading.cpp(7102)
FlushAsyncLoading(int PackageID) Line CoreUObject\Private\Serialization\AsyncPackageLoader.cpp(643)
LoadPackageInternal(UPackage * InOuter, const wchar_t * InLongPackageNameOrFilename, unsigned int LoadFlags, FLinkerLoad * ImportLinker, FArchive * InReaderOverride, const FLinkerInstancingContext * InstancingContext) Line CoreUObject\Private\UObject\UObjectGlobals.cpp(1169)
LoadPackage(UPackage * InOuter, const wchar_t * InLongPackageName, unsigned int LoadFlags, FArchive * InReaderOverride, const FLinkerInstancingContext * InstancingContext) Line CoreUObject\Private\UObject\UObjectGlobals.cpp(1491)
ResolveName(UObject * & InPackage, FString & InOutName, bool Create, bool Throw, unsigned int LoadFlags, const FLinkerInstancingContext * InstancingContext) Line CoreUObject\Private\UObject\UObjectGlobals.cpp(791)
StaticLoadObjectInternal(UClass * ObjectClass, UObject * InOuter, const wchar_t * InName, const wchar_t * Filename, unsigned int LoadFlags, UPackageMap * Sandbox, bool bAllowObjectReconciliation, const FLinkerInstancingContext * InstancingContext) Line CoreUObject\Private\UObject\UObjectGlobals.cpp(865)
StaticLoadObject(UClass * ObjectClass, UObject * InOuter, const wchar_t * InName, const wchar_t * Filename, unsigned int LoadFlags, UPackageMap * Sandbox, bool bAllowObjectReconciliation, const FLinkerInstancingContext * InstancingContext) Line CoreUObject\Private\UObject\UObjectGlobals.cpp(950)
FSoftObjectPath::TryLoad(FUObjectSerializeContext * InLoadContext) Line CoreUObject\Private\UObject\SoftObjectPath.cpp(443)
FSoftObjectPtr::LoadSynchronous() Line CoreUObject\Public\UObject\SoftObjectPtr.h(57)
TSoftObjectPtr<UObject>::LoadSynchronous() Line CoreUObject\Public\UObject\SoftObjectPtr.h(302)

Interface of AsynLoading process：Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading.cpp

int32 LoadPackageAsync(const FString& InName, const FGuid* InGuid /*= nullptr*/, const TCHAR* InPackageToLoadFrom /*= nullptr*/, FLoadPackageAsyncDelegate InCompletionDelegate /*= FLoadPackageAsyncDelegate()*/, EPackageFlags InPackageFlags /*= PKG_None*/, int32 InPIEInstanceID /*= INDEX_NONE*/, int32 InPackagePriority /*= 0*/)
{
    static bool bOnce = false;
    if (!bOnce && GEventDrivenLoaderEnabled)
    {
        bOnce = true;
        FGCObject::StaticInit(); // otherwise this thing is created during async loading, but not associated with a package
    }

    // The comments clearly state that it should be a package name but we also handle it being a filename as this function is not perf critical
    // and LoadPackage handles having a filename being passed in as well.
    FString PackageName;
    if (FPackageName::IsValidLongPackageName(InName, /*bIncludeReadOnlyRoots*/true))
    {
        PackageName = InName;
    }
    // PackageName got populated by the conditional function
    else if (!(FPackageName::IsPackageFilename(InName) && FPackageName::TryConvertFilenameToLongPackageName(InName, PackageName)))
    {
        // PackageName will get populated by the conditional function
        FString ClassName;
        if (!FPackageName::ParseExportTextPath(PackageName, &ClassName, &PackageName))
        {
            UE_LOG(LogStreaming, Fatal, TEXT("LoadPackageAsync failed to begin to load a package because the supplied package name was neither a valid long package name nor a filename of a map within a content folder: '%s'"), *PackageName);
        }
    }

    FString PackageNameToLoad(InPackageToLoadFrom);
    if (PackageNameToLoad.IsEmpty())
    {
        PackageNameToLoad = PackageName;
    }
    // Make sure long package name is passed to FAsyncPackage so that it doesn't attempt to 
    // create a package with short name.
    if (FPackageName::IsShortPackageName(PackageNameToLoad))
    {
        UE_LOG(LogStreaming, Fatal, TEXT("Async loading code requires long package names (%s)."), *PackageNameToLoad);
    }

    if ( FCoreDelegates::OnAsyncLoadPackage.IsBound() )
    {
        FCoreDelegates::OnAsyncLoadPackage.Broadcast(InName);
    }

    // Generate new request ID and add it immediately to the global request list (it needs to be there before we exit
    // this function, otherwise it would be added when the packages are being processed on the async thread).
    const int32 RequestID = GPackageRequestID.Increment();
    FAsyncLoadingThread::Get().AddPendingRequest(RequestID);

    // Allocate delegate on Game Thread, it is not safe to copy delegates by value on other threads
    TUniquePtr<FLoadPackageAsyncDelegate> CompletionDelegatePtr;
    if (InCompletionDelegate.IsBound())
    {
        CompletionDelegatePtr.Reset(new FLoadPackageAsyncDelegate(InCompletionDelegate));
    }

    // Add new package request
    FAsyncPackageDesc PackageDesc(RequestID, *PackageName, *PackageNameToLoad, InGuid ? *InGuid : FGuid(), MoveTemp(CompletionDelegatePtr), InPackageFlags, InPIEInstanceID, InPackagePriority);
    FAsyncLoadingThread::Get().QueuePackage(PackageDesc);

    return RequestID;
}

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[UE4]Engine Source Analysis - Load Object

Wang Aiguo