Re: [Boost-users] Boost.Utility/Singleton Problem when using with dynamic libraries

From: NFarnsworth_at_[hidden]
Date: 2008-02-06 13:07:26

Hello,
Unfortunately I still need help with these problems please. Is there anybody who could explain me how to use the Boost.Utilty/Singleton with dlls?
The test examples of the singleton didn't clearify for me, how I can do this.
Best regards
Niklas

> 
> Hello,
> I want to use the Boost.Utility/Singleton together with dll's. I use the Visual Studio 2005 and Windows XP.
> I have three dynamic libraries. In library A the Singleton is implemented and library B and C access to the Singleton. The dynamic libraries B and C
> 
> are compiled with the clr compiler Option. The Problem is, that the Singleton will be twice instantiated when library A and B access to the singleton.
> 
> The singleton declaration looks like the following code:
> //Singleton.h
> class Singleton :  public  boost::singleton<Singleton ,1,factorylib_tag >
> {
>         public:
>         CPP_API  Singleton (boost::restricted);
> &#8230;
> BOOST_SINGLETON_PLACEMENT_DECLARATION
> &#8230;
> }
> CPP_API is a definition of the dll export.
> 
> #if defined( _WIN32 ) && defined( _MSC_VER )
> #       if defined SINGLETON_EXPORTS
> #               define CPP_API __declspec( dllexport )
> #       else
> #               define CPP_API __declspec( dllimport )
> #               pragma warning( disable : 4251 )        // 'identifier' : class 'type' needs to have dll-interface to be used by clients of class 'type2'
> 
> #       endif
> #endif
> 
> In the Project properties of library B and C in "additional linkage input" I included the import library of the dll A.
> 
> Another problem is, that the application crashes when I close the application.
> The crash happens in
>         C.dll!_CRT_INIT(void * hDllHandle=0x0f8b0000, unsigned long dwReason=0, void * lpreserved=0x00000001) line 420
>         -> _free_crt ( onexitbegin ) ;
> And also :
>         B.dll!_CRT_INIT(void * hDllHandle=0x0f8b0000, unsigned long dwReason=0, void * lpreserved=0x00000001) line 420
>         -> _free_crt ( onexitbegin ) ;
> If I don't use the singleton, the application will not crash.
> 
> Another Problem is, that I can not compile the following code:
> 
> class DataPoolManagerImpl :  public boost::mutexed_singleton<DataPoolManagerImpl,2,datapoollib_tag>
> {
> 
> Then I will get the following error message:
> 
> boost\utility\mutexed_singleton.hpp(212) : error C2248: "boost::mutexed_singleton<Derived,DisposalSlot>::instance_proxy": cannot access private class, which is declared in boost::mutexed_singleton<Derived,DisposalSlot>
> 
> with
> [
> Derived=DataPoolManagerImpl,
> DisposalSlot=2
> ]
> \boost\utility\mutexed_singleton.hpp(41): see declaration of 'boost::mutexed_singleton<Derived,DisposalSlot>::instance_proxy'
> 
> with
>        [
> Derived=DataPoolManagerImpl,
> DisposalSlot=2
> ]
> \boost\utility\mutexed_singleton.hpp(211): During compiling the class template of the static data member "const boost::mutexed_singleton<Derived,DisposalSlot,SubsystemTag>::instance_proxy boost::mutexed_singleton<Derived,DisposalSlot,SubsystemTag>::instance".
> 
> with
> [
> Derived=DataPoolManagerImpl,
> DisposalSlot=2,
> SubsystemTag=datapoollib_tag
> ]
> \datapoolmanager.h(43): see reference of instantiation of compiled class template "boost::mutexed_singleton<Derived,DisposalSlot,SubsystemTag>".
> 
> with
> [
> DataPoolManagerImpl,
> DisposalSlot=2,
> datapoollib_tag
> ]
> \boost\utility\mutexed_singleton.hpp(212) : error C2440: Initialization': 'boost::mutexed_singleton<Derived,DisposalSlot>::instance_proxy' could not converted in 'boost::mutexed_singleton<Derived,DisposalSlot,SubsystemTag>::instance_proxy'
> 
> with
> [
> Derived=DataPoolManagerImpl,
> DisposalSlot=2
> ]
> 
> With :
>  class DataPoolManagerImpl :  public boost::singleton<DataPoolManagerImpl,2,datapoollib_tag>
> There are no compiler errors.
> 
> Could you tell me how I can solve these problems please?
> Thank you for your help in advance and best regards
> Niklas 

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