- static std::map<std::string, std::shared_ptr<const Image>> all_images;
- static std::map<std::string, std::thread> update_threads;
+ static std::map<std::string, std::shared_ptr<const Image>> all_images; // Under all_images_lock.
+ static bool update_thread_started; // Under all_images_lock.
+ static std::thread update_thread; // Under all_images_lock.