EM_Task/CoreUObject/Private/Serialization/ArchiveObjectGraph.cpp

// Copyright Epic Games, Inc. All Rights Reserved.

#include "Serialization/ArchiveObjectGraph.h"
#include "UObject/UObjectIterator.h"

// This is from FArchiveTraceRoute -This only creates object graph of all objects
// This can be used by other classes such as FTraceReferences - trace references of one object
FArchiveObjectGraph::FArchiveObjectGraph(bool IncludeTransients, EObjectFlags KeepFlags)
    : CurrentReferencer(NULL),
      bIncludeTransients(IncludeTransients),
      RequiredFlags(KeepFlags)
{
    ArIsObjectReferenceCollector = true;

    // ALL objects reference their outers...it's just log spam here
    // ArIgnoreOuterRef = true;

    TArray<UObject*> RootObjects;

    // allocate enough memory for all objects
    ObjectGraph.Empty(GUObjectArray.GetObjectArrayNum());
    RootObjects.Empty(GUObjectArray.GetObjectArrayNum());

    // search for objects that have the right flags and add them to the list of objects that we're going to start with
    // all other objects need to be tagged so that we can tell whether they've been serialized or not.
    for (FThreadSafeObjectIterator It; It; ++It)
    {
        UObject* CurrentObject = *It;
        if (CurrentObject->HasAnyFlags(RequiredFlags))
        {
            // make sure it isn't tagged
            // ASKRON: WHY do we need this?
            CurrentObject->UnMark(OBJECTMARK_TagExp);
            RootObjects.Add(CurrentObject);
            ObjectGraph.Add(CurrentObject, new FObjectGraphNode(CurrentObject));
        }
        else
        {
            // ASKRON: WHY do we need this?
            CurrentObject->Mark(OBJECTMARK_TagExp);
        }
    }

    // Populate the ObjectGraph - this serializes our root set to map out the relationships between all rooted objects
    GenerateObjectGraph(RootObjects);

    // we won't be adding any additional objects for the arrays and graphs, so free up any memory not being used.
    RootObjects.Shrink();
    ObjectGraph.Shrink();

    // we're done with serialization; clear the tags so that we don't interfere with anything else
    for (FThreadSafeObjectIterator It; It; ++It)
    {
        It->UnMark(OBJECTMARK_TagExp);
    }
}

FArchiveObjectGraph::~FArchiveObjectGraph()
{
    for (TMap<UObject*, FObjectGraphNode*>::TIterator It(ObjectGraph); It; ++It)
    {
        delete It.Value();
        It.Value() = NULL;
    }
}

/** Handles serialization of UObject references */
FArchive& FArchiveObjectGraph::operator<<(class UObject*& Obj)
{
    if (Obj != NULL && (bIncludeTransients || !Obj->HasAnyFlags(RF_Transient)))
    {
        // grab the object graph node for this object and its referencer, creating them if necessary
        FObjectGraphNode* CurrentObjectNode = ObjectGraph.FindRef(Obj);
        if (CurrentObjectNode == NULL)
        {
            CurrentObjectNode = ObjectGraph.Add(Obj, new FObjectGraphNode(Obj));
        }
        FObjectGraphNode* ReferencerNode = ObjectGraph.FindRef(CurrentReferencer);
        if (ReferencerNode == NULL)
        {
            ReferencerNode = ObjectGraph.Add(CurrentReferencer, new FObjectGraphNode(CurrentReferencer));
        }

        if (Obj != CurrentReferencer)
        {
            FTraceRouteRecord* Record = ReferencerNode->ReferencedObjects.Find(Obj);
            // now record the references between this object and the one referencing it
            if (!Record)
            {
                ReferencerNode->ReferencedObjects.Add(Obj, FTraceRouteRecord(CurrentObjectNode, GetSerializedProperty()));
            }
            else
            {
                Record->Add(GetSerializedProperty());
            }

            Record = CurrentObjectNode->ReferencerRecords.Find(CurrentReferencer);
            if (!Record)
            {
                CurrentObjectNode->ReferencerRecords.Add(CurrentReferencer, FTraceRouteRecord(ReferencerNode, GetSerializedProperty()));
            }
            else
            {
                Record->Add(GetSerializedProperty());
            }
        }

        // if this object is still tagged for serialization, add it to the list
        if (Obj->HasAnyMarks(OBJECTMARK_TagExp))
        {
            Obj->UnMark(OBJECTMARK_TagExp);
            ObjectsToSerialize.Add(Obj);
        }
    }
    return *this;
}

void FArchiveObjectGraph::GenerateObjectGraph(TArray<UObject*>& Objects)
{
    const int32 LastRootObjectIndex = Objects.Num();

    for (int32 ObjIndex = 0; ObjIndex < Objects.Num(); ObjIndex++)
    {
        CurrentReferencer = Objects[ObjIndex];
        CurrentReferencer->UnMark(OBJECTMARK_TagExp);

        // Serialize this object
        if (CurrentReferencer->HasAnyFlags(RF_ClassDefaultObject))
        {
            CurrentReferencer->GetClass()->SerializeDefaultObject(CurrentReferencer, *this);
        }
        else
        {
            CurrentReferencer->Serialize(*this);
        }

        // ObjectsToSerialize will contain only those objects which were encountered while serializing CurrentReferencer
        // that weren't already in the list of objects to be serialized.
        if (ObjectsToSerialize.Num() > 0)
        {
            // add to objects, so that we make sure ObjectToSerialize are serialized
            Objects += ObjectsToSerialize;
            ObjectsToSerialize.Empty();
        }
    }

    Objects.RemoveAt(LastRootObjectIndex, Objects.Num() - LastRootObjectIndex);
}

void FArchiveObjectGraph::ClearSearchFlags()
{
    for (TMap<UObject*, FObjectGraphNode*>::TIterator Iter(ObjectGraph); Iter; ++Iter)
    {
        FObjectGraphNode* GraphNode = Iter.Value();
        if (GraphNode)
        {
            GraphNode->Visited        = 0;
            GraphNode->ReferenceDepth = MAX_int32;
            GraphNode->ReferencerProperties.Empty();
        }
    }
}