决定是否保持进程运行

【Deciding whether to keep the process running】

与 libuv 句柄类似，线程安全函数可以被“引用”或“取消引用”。一个“被引用”的线程安全函数会导致它所在线程的事件循环保持活跃，直到该线程安全函数被销毁。相比之下，一个“被取消引用”的线程安全函数不会阻止事件循环退出。为此，存在 napi_ref_threadsafe_function 和 napi_unref_threadsafe_function 这些 API。

【Similarly to libuv handles, thread-safe functions can be "referenced" and "unreferenced". A "referenced" thread-safe function will cause the event loop on the thread on which it is created to remain alive until the thread-safe function is destroyed. In contrast, an "unreferenced" thread-safe function will not prevent the event loop from exiting. The APIs napi_ref_threadsafe_function and napi_unref_threadsafe_function exist for this purpose.】

napi_unref_threadsafe_function 并不会将线程安全函数标记为可以被销毁，napi_ref_threadsafe_function 也不会阻止它被销毁。

【Neither does napi_unref_threadsafe_function mark the thread-safe functions as able to be destroyed nor does napi_ref_threadsafe_function prevent it from being destroyed.】