ThreadSingleton.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Templates/Function.h"
#include "HAL/PlatformTLS.h"
#include "HAL/TlsAutoCleanup.h"
 
template <typename FuncType> class TFunctionRef;
 
class FThreadSingletonInitializer
{
public:
 
    static CORE_API FTlsAutoCleanup* Get( TFunctionRef<FTlsAutoCleanup*()> CreateInstance, uint32& TlsSlot );
 
    static CORE_API FTlsAutoCleanup* TryGet(uint32& TlsSlot);
 
    static CORE_API FTlsAutoCleanup* Inject(FTlsAutoCleanup* Instance, uint32& TlsSlot);
};
 
#define UE_DECLARE_THREAD_SINGLETON_TLS(Type, Api) template<> Api uint32& TThreadSingleton<Type>::GetTlsSlot();
#define UE_DEFINE_THREAD_SINGLETON_TLS(Type, Api) template<> Api uint32& TThreadSingleton<Type>::GetTlsSlot() { static uint32 TlsSlot = FPlatformTLS::InvalidTlsSlot; return TlsSlot; }
 
template < class T >
class TThreadSingleton : public FTlsAutoCleanup
{
#if PLATFORM_UNIX || PLATFORM_APPLE
    CORE_API static uint32& GetTlsSlot()
    {
        static uint32 TlsSlot = FPlatformTLS::InvalidTlsSlot;
        return TlsSlot;
    }
#else
#if PLATFORM_CONSOLE_DYNAMIC_LINK
    FORCENOINLINE
#endif
    static uint32& GetTlsSlot()
    {
        static uint32 TlsSlot = FPlatformTLS::InvalidTlsSlot;
        return TlsSlot;
    }
#endif
 
protected:
 
    TThreadSingleton()
        : ThreadId(FPlatformTLS::GetCurrentThreadId())
    {}
 
    virtual ~TThreadSingleton()
    {
        // Clean the dangling pointer from the TLS.
        check(GetTlsSlot() != FPlatformTLS::InvalidTlsSlot);
        if(((FTlsAutoCleanup*)FPlatformTLS::GetTlsValue(GetTlsSlot())) == static_cast<FTlsAutoCleanup*>(this))
        {
            FPlatformTLS::SetTlsValue(GetTlsSlot(), nullptr);
        }
    }
 
    static FTlsAutoCleanup* CreateInstance()
    {
        return new T();
    }
 
    const uint32 ThreadId;
 
public:
 
    FORCEINLINE static T& Get()
    {
        return *(T*)FThreadSingletonInitializer::Get( [](){ return (FTlsAutoCleanup*)new T(); }, T::GetTlsSlot() ); //-V572
    }
 
    FORCEINLINE static T& Get(TFunctionRef<FTlsAutoCleanup*()> CreateInstance)
    {
        return *(T*)FThreadSingletonInitializer::Get(CreateInstance, T::GetTlsSlot()); //-V572
    }
 
    FORCEINLINE static T* TryGet()
    {
        return (T*)FThreadSingletonInitializer::TryGet( T::GetTlsSlot() );
    }
 
    FORCEINLINE static T* Inject(T* Instance)
    {
        return (T*)FThreadSingletonInitializer::Inject(Instance, T::GetTlsSlot());
    }
};