Re: need feedback on singleton template
"Dmitry Teslenko" <dteslenko@gmail.com> wrote in message
news:b22cafae-d213-4d3e-b112-ec1ca39a4be5@m34g2000hsc.googlegroups.com...
Hello! I've come up with this singleton template. It works and seems
to correctly free resources.
One bad thing is WorkerSingleton's constructor/destructor must be
public in order to use Singleton template.
[...]
Not going to work as-is because shared_ptr honors only basic thread-safety.
Here is an outline of an atomically thread-safe singleton:
_______________________________________________________________
template<typename T>
class once {
static T* m_state;
static pthread_mutex_t m_mtx;
public:
static T* get() {
T* local = ATOMIC_LOADPTR_MBDEPENDS(&m_state);
if (local == NULL) {
pthread_mutex_lock(&m_mtx);
if ((local = m_state) == NULL) {
try {
local = new T;
} catch (...) {
pthread_mutex_unlock(&m_mtx);
throw;
}
ATOMIC_STOREPTR_MBRELEASE(&m_state, local);
}
pthread_mutex_unlock(&m_mtx);
}
return local;
}
};
template<typename T>
T* once<T>::m_state = NULL;
template<typename T>
pthread_mutex_t once<T>::m_mtx = PTHREAD_MUTEX_INITIALIZER;
_______________________________________________________________
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