If a function needs to maintain the state of some data over successive calls, such as a working buffer or a pointer, the caller should provide this data.
如果函数需要在一系列调用期间维持某些数据的状态，比如工作缓存或指针，那么调用者应该提供此数据。
The selector internally calls a native poll() function (shown in Listing 5), which provides a mechanism for multiplexing inputs and outputs over a set of file descriptors
选择器在内部调用一个本机 poll() 函数（见 清单 5），这个函数支持在一组文件描述符上多路复用输入和输出
应用推荐