Editor.UseLegacyGetReferencersForDeletion
Editor.UseLegacyGetReferencersForDeletion
#Overview
name: Editor.UseLegacyGetReferencersForDeletion
This variable is created as a Console Variable (cvar).
- type:
Var - help:
Choose the algorithm to be used when detecting referencers of any assets/objects being deleted.\n\n0: Use the most optimized version (default)\n1: Use the slower legacy version (for debug/comparison)
It is referenced in 8 C++ source files.
#Summary
#Usage in the C++ source code
The purpose of Editor.UseLegacyGetReferencersForDeletion is to control the algorithm used for detecting referencers of assets or objects being deleted in the Unreal Engine editor.
This setting variable is primarily used in the UnrealEd module, specifically in the ObjectTools namespace. It affects the asset deletion process and how the engine detects object references.
The value of this variable is set through a console variable (CVar) system. It’s defined as a TAutoConsoleVariable in ObjectTools.cpp, with a default value of false.
The associated variable CVarUseLegacyGetReferencersForDeletion interacts directly with Editor.UseLegacyGetReferencersForDeletion. They share the same value and purpose.
Developers must be aware that:
- When set to false (default), it uses an optimized version of the reference detection algorithm.
- When set to true, it uses a slower, legacy version of the algorithm, which is mainly kept for debugging and comparison purposes.
Best practices when using this variable include:
- Generally, keep it set to false for better performance.
- Use the legacy version (true) only when debugging reference issues or comparing results with the optimized version.
- Be cautious when changing this value during runtime, as it can affect the behavior of asset deletion operations.
Regarding the associated variable CVarUseLegacyGetReferencersForDeletion:
- It’s used to directly access and modify the value of Editor.UseLegacyGetReferencersForDeletion.
- It’s used in various parts of the code to check which algorithm should be used for reference detection.
- In test scenarios (e.g., in ObjectToolsTests.cpp), it’s temporarily set to ensure consistent behavior during tests.
- The code includes a mechanism to automatically switch to the legacy version if inconsistencies are detected between the two algorithms, which developers should be aware of when working with this feature.
#References in C++ code
#Callsites
This variable is referenced in the following C++ source code:
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/ObjectTools.cpp:109
Scope: file
Source code excerpt:
static TAutoConsoleVariable<bool> CVarUseLegacyGetReferencersForDeletion(
TEXT("Editor.UseLegacyGetReferencersForDeletion"),
false,
TEXT("Choose the algorithm to be used when detecting referencers of any assets/objects being deleted.\n\n")
TEXT("0: Use the most optimized version (default)\n")
TEXT("1: Use the slower legacy version (for debug/comparison)"),
ECVF_Default
);
#Loc: <Workspace>/Engine/Plugins/Tests/EditorTests/Source/EditorTests/Private/UnrealEd/ObjectToolsTests.cpp:208
Scope (from outer to inner):
file
function bool FObjectToolsTests_GatherObjectReferencersForDeletion::RunTest
Source code excerpt:
//Make sure we do not use the legacy referencers for deletion
static IConsoleVariable* CVarUseLegacyGetReferencersForDeletion = IConsoleManager::Get().FindConsoleVariable(TEXT("Editor.UseLegacyGetReferencersForDeletion"));
check(CVarUseLegacyGetReferencersForDeletion);
bool PreviousCVarUseLegacyGetReferencersForDeletionValue = CVarUseLegacyGetReferencersForDeletion->GetBool();
CVarUseLegacyGetReferencersForDeletion->Set(0);
//Put back the previous value when the test is done
ON_SCOPE_EXIT
{
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/AssetDeleteModel.cpp:678
Scope (from outer to inner):
file
function void FPendingDelete::CheckForReferences
Source code excerpt:
AssetRegistryModule.Get().GetReferencers(Object->GetOutermost()->GetFName(), DiskReferences);
IConsoleVariable* UseLegacyGetReferencersForDeletion = IConsoleManager::Get().FindConsoleVariable(TEXT("Editor.UseLegacyGetReferencersForDeletion"));
if (UseLegacyGetReferencersForDeletion == nullptr || !UseLegacyGetReferencersForDeletion->GetBool())
{
// This new version uses the fast reference collector to gather referencers and handles transaction referencers in a single pass
ObjectTools::GatherObjectReferencersForDeletion(Object, bIsReferencedInMemoryByNonUndo, bIsReferencedInMemoryByUndo, &MemoryReferences);
}
else
#Associated Variable and Callsites
This variable is associated with another variable named CVarUseLegacyGetReferencersForDeletion. They share the same value. See the following C++ source code.
#Loc: <Workspace>/Engine/Plugins/Tests/EditorTests/Source/EditorTests/Private/UnrealEd/ObjectToolsTests.cpp:208
Scope (from outer to inner):
file
function bool FObjectToolsTests_GatherObjectReferencersForDeletion::RunTest
Source code excerpt:
//Make sure we do not use the legacy referencers for deletion
static IConsoleVariable* CVarUseLegacyGetReferencersForDeletion = IConsoleManager::Get().FindConsoleVariable(TEXT("Editor.UseLegacyGetReferencersForDeletion"));
check(CVarUseLegacyGetReferencersForDeletion);
bool PreviousCVarUseLegacyGetReferencersForDeletionValue = CVarUseLegacyGetReferencersForDeletion->GetBool();
CVarUseLegacyGetReferencersForDeletion->Set(0);
//Put back the previous value when the test is done
ON_SCOPE_EXIT
{
if (PreviousCVarUseLegacyGetReferencersForDeletionValue)
{
CVarUseLegacyGetReferencersForDeletion->Set(1);
}
};
// Test direct references to ObjectInPackage
{
UObjectToolsTestObject* DirectRootReferencer = NewObject<UObjectToolsTestObject>(GetTransientPackage(), NAME_None, RF_Transactional);
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/ObjectTools.cpp:108
Scope: file
Source code excerpt:
DEFINE_LOG_CATEGORY_STATIC(LogObjectTools, Log, All);
static TAutoConsoleVariable<bool> CVarUseLegacyGetReferencersForDeletion(
TEXT("Editor.UseLegacyGetReferencersForDeletion"),
false,
TEXT("Choose the algorithm to be used when detecting referencers of any assets/objects being deleted.\n\n")
TEXT("0: Use the most optimized version (default)\n")
TEXT("1: Use the slower legacy version (for debug/comparison)"),
ECVF_Default
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/ObjectTools.cpp:268
Scope (from outer to inner):
file
namespace ObjectTools
function void GatherObjectReferencersForDeletion
Source code excerpt:
bOutIsReferencedInMemoryByUndo = false;
if (!CVarUseLegacyGetReferencersForDeletion.GetValueOnAnyThread())
{
const UTransactor* Transactor = GEditor ? ToRawPtr(GEditor->Trans) : nullptr;
bool bIsGatheringPackageRef = InObject->IsA<UPackage>();
// Get the cluster of objects that are going to be deleted
TArray<UObject*> ObjectsToDelete;
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/ObjectTools.cpp:396
Scope (from outer to inner):
file
namespace ObjectTools
function void GatherObjectReferencersForDeletion
Source code excerpt:
{
UE_LOG(LogObjectTools, Warning, TEXT("Detected inconsistencies between reference gathering algorithms. Switching 'Editor.UseLegacyGetReferencersForDeletion' on for the remainder of this editor session."));
CVarUseLegacyGetReferencersForDeletion->Set(1);
}
GEditor->Trans->EnableObjectSerialization();
}
}
// This is the old/slower behavior that is kept for debug/comparison and is going to be removed in a future release
else
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/ObjectTools.cpp:3209
Scope (from outer to inner):
file
namespace ObjectTools
function static void RecursiveRetrieveReferencers
Source code excerpt:
static void RecursiveRetrieveReferencers(const TArray<UObject*>& InInterestSet, TSet<FWeakObjectPtr>& OutReferencingObjects)
{
if (!CVarUseLegacyGetReferencersForDeletion.GetValueOnAnyThread())
{
// Use the fast reference collector to recursively find referencers until no more are found
TSet<UObject*> InterestSet;
InterestSet.Append(InInterestSet);
// Continue until we're not adding any more referencers to the set