#include <boost/thread.hpp>
#include <boost/bind.hpp>
#include <assert.h>
#include <iostream>

struct counter
{
    static unsigned count;
    static boost::mutex count_mutex;
    
    counter()
    {
        boost::lock_guard<boost::mutex> lk(count_mutex);
        ++count;
    }
    
    counter(counter const&)
    {
        boost::lock_guard<boost::mutex> lk(count_mutex);
        ++count;
    }
    
    ~counter()
    {
        boost::lock_guard<boost::mutex> lk(count_mutex);
        --count;
    }
    
    static unsigned get_count()
    {
        boost::lock_guard<boost::mutex> lk(count_mutex);
        return count;
    }
        
    void do_stuff(int)
    {}
};

unsigned counter::count=0;
boost::mutex counter::count_mutex;

int main()
{
    boost::shared_ptr<counter> c(new counter);
    boost::thread t(boost::bind(&counter::do_stuff,c,42));
    std::cout<<"instances="<<counter::get_count()<<std::endl;
    t.join();
    std::cout<<"instances="<<counter::get_count()<<std::endl;
    c.reset();
    std::cout<<"instances="<<counter::get_count()<<std::endl;
    assert(!counter::get_count());
}