#include <boost/exception.hpp>
#include <boost/thread.hpp>
#include <string>

typedef boost::error_info<struct tag_throw_string, std::string> err_info;

class err
  : public boost::exception
  , public std::exception
{
};

class future
{
public:
  future () : ready_ (false) {}

  void set_exception (boost::exception_ptr const& e)
  {
    boost::unique_lock<boost::mutex> lck (mux_);
    exc_ = e;
    ready_ = true;
    cond_.notify_all();
  }

  void get_exception () const
  {
    boost::unique_lock<boost::mutex> lck (mux_);
    while (! ready_)
      cond_.wait (lck);
    rethrow_exception (exc_);
  }

private:
  bool ready_;
  boost::exception_ptr exc_;
  mutable boost::mutex mux_;
  mutable boost::condition_variable cond_;
};

void producer (future& f)
{
  f.set_exception (boost::copy_exception (err () << err_info ("stub")));
}

void consumer ()
{
  future f;
  boost::thread thr (boost::bind (&producer, boost::ref (f)));

  try { f.get_exception (); }
  catch (err const& e) {}

  thr.join ();
}


void consume ()
{
  for (int i=0;i<100;++i)
    consumer ();
}

int main ()
{
  boost::thread_group grp;
  for (int i=0; i<50; ++i)
    grp.create_thread (&consume);

  grp.join_all ();
}