This is the advanced example of a tcp server implementation powered by poll API. Just writing socket programs is boring and not so exciting so I started writing an example program, spending boring new year's holidays.
In general, Poll API helps server applications scale well. The key to a scale-well theory is to make file descriptors none-blocking, meaning putting descriptors into a queue and letting OSes read/write 'em later when OSes have time for it. Epoll has been the main API used by many heavy I/O-use programs/libraries for years. The example is intended to understand technologies and hope to utilize poll APIs for daily application developments.
struct poll_data *new_poll(void); // Make an instance of poll_data.
void register_client(struct poll_data *, int); // Register client file descriptor.
int dispatch(struct poll_data *, read_callback); // Dispatch with read callback. $ gdb ./debug/server
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$ echo hello | nc 0.0.0.0 2000
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