require 'kqueue'

# Inheritance
# class Kqueue < IO
#   # ident: file descriptor identifier for this event
#   # filter: filter for event(just one)
#   # flags: general flags(complex fragment)
#   # fflags: filter-specific flags(complex fragment)
#   # data: filter-specific data
#   # udata: opaque user data(can set any object)
#   class Event < Struct.new(:ident, :filter, :flags, :fflags, :data, :udata)
#     # Event::Constants include all kqueue constants
#     include Event::Constants
#   end
# end

# create kqueue object and ensure close
Kqueue.open do |kq|
  # ...
end

# or
begin
  kq = Kqueue.new
  # ...
ensure
  kq.close
end

# watch event
IO.pipe do |r, w|
  Kqueue.open do |kq|
    kev = Kqueue::Event.new(r.fileno, EVFILT_READ, EV_ADD, 0, 0, proc {
      puts "you can read #{r.fileno} with non block!"
    })
    # set a event
    kq.kevent([kev], 0)

    # wait a event
    # wait until event occur
    kq.kevent(nil, 1)

    # wait 0.1 sec
    kq.kevent(nil, 1, 0.1) #=> []

    w.write 'ok go'
    w.flush

    # get a notified event
    kevs = kq.kevent(nil, 1) #=> [#<a Event object>]

    # udata have one any object
    kevs.first.udata.call #=> you can read 7 with non block!
  end
end