4 ms·

For many use cases, either of the two can be written as an emulation over the other.

• zrm 10y ago
  > For many use cases, either of the two can be written as an emulation over the other. Between select/poll/epoll/kqueue/etc and each other that is easy. You have a few functions like "register(ctx, fd, event)" and "wait_for_events(ctx)" that map straight to each of the implementations. To use IOCP it's not just those you have to wrap. It's also send(), sendto(), sendmsg(), write(), recv(), recvfrom(), recvmsg(), read(), connect(), accept() and others. In ways that don't make for trivial or efficient implementations. And then contend with any third party library that uses any of those internally. There is a reason libev doesn't support IOCP and libevent only supports it by exposing a different API on Windows.
  • JdeBP 10y ago
    The devil is in the details. Consider Mark Heily's libkqueue library for Linux that emulates kqueue/kevent. Because of the way that signalfd, upon which it is built, works, code that uses kevent with signals on the BSDs has to be written one way and on Linux has to be written another. It's a subtle difference in the manual page; and it's all too easy to read the wrong implementation's manual page on the WWW (if one makes the mistake of using a search engine to find manual pages) and write things incorrectly. It is also telling, of how difficult to interconvert it actually is in practice, that the Heily libkqueue does not implement EVFILT_AIO, EVFILT_FS, or EVFILT_PROCDESC, and implements some of the others in only a limited fashion.