Re: singleton in a DLL loaded class
PaulH <paul.heil@gmail.com> wrote:
On Jun 25, 2:00 pm, "Igor Tandetnik" <itandet...@mvps.org> wrote:
PaulH <paul.h...@gmail.com> wrote:
On Jun 25, 1:29 pm, "Igor Tandetnik" <itandet...@mvps.org> wrote:
PaulH <paul.h...@gmail.com> wrote:
I have a class loaded from a DLL that I would like to implement
as a multi-threadable singleton. Unfortunately, I seem to still be
getting two distinct instances of this class. It is implemented as
below.
//singletonclass.h
class SingletonClass : BaseClass
{
public:
static SingletonClass& Instance();
~SingletonClass();
//... Implement BaseClass functions
private:
static std::auto_ptr< SingletonClass > _theInstance;
static Mutex* _m;
}
//singletonclass.cpp
std::auto_ptr< SingletonClass > SingletonClass::_theInstance;
Mutex* SingletonClass::_m;
/*static*/ SingletonClass& SingletonClass::Instance()
{
Mutex::Create( &_m );
What does Mutex::Create do? It appears you are creating a new mutex
every time Instance() is called.
I am.
But that defeats the whole point of having the mutex in the first
place.
So how do I make them use the same mutex?
Initialize it when the DLL loads. Just have a global object with a
constructor specifically for this purpose:
struct MutexCreator {
MutexCreator() {
Mutex::Create( &SingletonClass::_m );
}
// Perhaps a ~MutexCreator to destroy the mutex
};
// Runs the constructor during DLL initialization. Not used otherwise
MutexCreator mutex_creator;
--
With best wishes,
Igor Tandetnik
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