Code review comment for lp:~robertcarr/mir/session-transactions

...having thought about it: doesn't the problem stem from not holding SessionManager::mutex when these actions occur?

void msh::SessionManager::close_session(std::shared_ptr<mf::Session> const& session)
{
    auto shell_session = std::dynamic_pointer_cast<Session>(session);

    session_listener->stopping(shell_session);

    app_container->remove_session(shell_session);

    std::unique_lock<std::mutex> lock(mutex);
    set_focus_to_locked(lock, focus_sequence->default_focus());
}

Note that the SessionManager::mutex isn't seized until after the remove_session() call.

inline void msh::SessionManager::set_focus_to_locked(std::unique_lock<std::mutex> const&, std::shared_ptr<Session> const& shell_session)
{
    auto old_focus = focus_application.lock();

    focus_application = shell_session;

    focus_setter->set_focus_to(shell_session);
    if (shell_session)
    {
        session_listener->focused(shell_session);
    }
    else
    {
        session_listener->unfocused();
    }
}

Note that the SessionManager::mutex isn't seized.