epoll.ts

/*

See https://en.wikipedia.org/wiki/Epoll

This is a stub implementation of epoll that doesn't do anything in terms
of actually detecting file changes, but also appears not broken to the user.
It's very reasonable that we could implement a real version of epoll.
For linux it could just be a lightweight wrapper around real epoll, and for
other environments, something else depending on constraints.

This is used by the tail coreutils command to watch a file...
*/

export default function epoll({ sleep }: { sleep? }) {
  return {
    // int epoll_create(int flags);
    epoll_create: (_size: number): number => {
      return 0;
    },
    // int epoll_create1(int flags);
    epoll_create1: (_flags: number): number => {
      return 0;
    },

    // int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event);
    epoll_ctl: (
      _epfd: number,
      _op: number,
      _fd: number,
      _epoll_event_ptr: number
    ): number => {
      return 0;
    },

    // int epoll_wait(int epfd, struct epoll_event *events, int maxevents, int timeout);
    epoll_wait: (
      _epfd: number,
      _epoll_event_ptr: number,
      _maxevents: number,
      timeout: number
    ): number => {
      // if blocking sleep is available, we wait timeout *milliseconds*, then return 0
      sleep?.(timeout);
      return 0;
    },
  };
}