UObjectMigrationContext.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Templates/UniquePtr.h"
#include "UObject/RemoteExecutor.h"
#include "UObject/RemoteObjectTypes.h"
 
#define UE_API COREUOBJECT_API
 
enum class EObjectMigrationSide : uint8
{
    Receive,
 
    Send
};
 
enum class EObjectMigrationRecvType : uint8
{
    Invalid,
 
    Borrowed,
 
    ReturnedLoan,
 
    AssignedOwnership
};
UE_API const TCHAR* ToString(EObjectMigrationRecvType Value);
 
enum class EObjectMigrationSendType : uint8
{
    Invalid,
 
    Loan,
 
    ReturnBorrowed,
 
    ReassignBorrowed,
 
    ReassignOwnership
};
UE_API const TCHAR* ToString(EObjectMigrationSendType Value);
 
struct FUObjectMigrationContext final
{
    FRemoteObjectId ObjectId;
 
    FRemoteServerId RemoteServerId;
 
    FRemoteServerId OwnerServerId;
 
    FRemoteServerId PhysicsServerId;
 
    uint32 PhysicsLocalIslandId;
 
    EObjectMigrationSide MigrationSide = EObjectMigrationSide::Receive;
 
    FRemoteTransactionId MultiServerCommitRequestId;
 
    UE_API bool IsValid() const;
 
    UE_API EObjectMigrationRecvType GetObjectMigrationRecvType(const UObjectBase* Object) const;
    UE_API EObjectMigrationRecvType GetObjectMigrationRecvType(FRemoteObjectId ObjectId) const;
 
    UE_API EObjectMigrationSendType GetObjectMigrationSendType(const UObjectBase* Object) const;
    UE_API EObjectMigrationSendType GetObjectMigrationSendType(FRemoteObjectId ObjectId) const;
 
    static const FUObjectMigrationContext* const GetCurrentMigrationContext()
    {
        checkf(IsInGameThread(), TEXT("%hs: We expect migrations to only occur on the GameThread."), __func__);
        return CurrentMigrationContext;
    }
 
    
private: // Interface used for FScopedObjectMigrationContext
    friend struct FScopedObjectMigrationContext;
 
    inline static const FUObjectMigrationContext* CurrentMigrationContext = nullptr;
    static void SetCurrentMigrationContext(const FUObjectMigrationContext* NewMigrationContext)
    {
        checkf(IsInGameThread(), TEXT("%hs: We expect migrations to only occur on the GameThread."), __func__);
        CurrentMigrationContext = NewMigrationContext;
    }
};
 
struct FScopedObjectMigrationContext
{
    FScopedObjectMigrationContext(const FUObjectMigrationContext& NewMigrationContext)
        : PreviousMigrationContext(FUObjectMigrationContext::CurrentMigrationContext)
    {
        FUObjectMigrationContext::SetCurrentMigrationContext(&NewMigrationContext);
    }
 
    ~FScopedObjectMigrationContext()
    {
        FUObjectMigrationContext::SetCurrentMigrationContext(PreviousMigrationContext);
    }
 
private:
    const FUObjectMigrationContext* PreviousMigrationContext;
};
 
#undef UE_API