Question

I have the following code I have simplified:

Thread two:

  boost::unique_future<void> future;
  TaskPtr task(new task::ReloadConfig(future));
  Listener::PushTask(task);
  future.wait();

  try
  {
    future.get();
  }
  catch (const cfg::ConfigError& e)
  {
    return cmd::Result::Okay;
  }

Thread two:

  try
  {
    cfg::UpdateShared(std::shared_ptr<cfg::Config>(new cfg::Config(configFile)));
  }
  catch (...) // should be cfg::ConfigError
  {
    promise.set_exception(boost::current_exception());
    return;
  }

  promise.set_value();

Instead of a the Cfg::ConfigError exception or one of its derived exceptions being propogated from thread two to thread one I get the following:

terminate called after throwing an instance of
‘boost::exception_detail::clone_impl’
what(): std::exception

Seems this other person had similar troubles and no answer:

https://stackoverflow.com/questions/10857834/how-to-use-boostfuture-get-to-get-user-defined-exception

I also get the following error if I try to use boost::enable_current_exception:

/usr/local/include/boost/exception/exception.hpp:419:20: error: no
matching function for call to ‘std::runtime_error::runtime_error()’

I can get the code working fine without exceptions, by just returning a boolean value, but this is a compromise.

Answer 1

I would try to do something like that in your thread two:

catch (const cfg::ConfigError& e)
{
    promise.set_exception(boost::make_exception_ptr(e));
}

Otherwise if you want that current_exception() to work you have to mess with things like:

throw boost::enable_current_exception(cfg::ConfigError("meh"));