kqueue.cr

c_sys_event.cr

require "c/sys/time"

lib LibC
  KQUEUE_CLOEXEC = O_CLOEXEC

  # todo: constants
  # EV_ADD = ...
  # EV_ENABLE = ...
  # ...

  struct Kevent
    ident : SizeT # uintptr_t
    filter : Short
    flags : UShort
    fflags : UInt
    data : Int64
    udata : Void*
  end

  fun kqueue : Int
  fun kqueue1(flags : Int) : Int # fixme: may be named kqueuex or not be available (depends on the BSD variant)
  fun kevent(kq : Int, changelist : Kevent*, nchanges : SizeT, eventlist : Kevent*, nevents : SizeT, timeout : Timespec) : Int
end

kqueue.cr

{% skip_file unless flag?(:bsd) || flag?(:darwin) %}

require "./c/sys/event"

struct Kqueue
  def initialize
    {% if LibC.has_method?(:kqueue1) %}
      @kq = LibC.kqueue1(LibC::KQUEUE_CLOEXEC)
      raise RuntimeError.from_errno("kqueue1") if @kq == -1
    {% else %}
      @kq = LibC.kqueue
      raise RuntimeError.from_errno("kqueue") if @kq == -1

      {% unless flag?(:openbsd) %}
        ret = LibC.fcntl(LibC::F_SETFD, LibC::FD_CLOEXEC) == -1
        raise IO::Error.from_errno("fcntl")
      {% end %}
    {% end %}
  end

  def call(changes : Slice(LibC::Kevent)?, events : Slice(LibC::Kevent)?, timeout : Time::Span?) : Int32
    if timeout
      ts = uninitialized LibC::Timespec
      ts.tv_sec = LibC::Long.new!(timeout.seconds)
      ts.tv_nsec = LibC::Long.new!(timeout.nanoseconds)
      tsp = pointerof(ts)
    end

    nchanges = changes.try(&.size) || 0
    nevents = events.try(&.size) || 0

    if LibC.kevent(@kq, changes, nchanges, events, nevents, tsp) == -1
      raise RuntimeError.from_errno("kevent")
    end

    events.try(&.size) || 0
  end

  def close : Nil
    if LibC.close(@kq) == -1
      raise RuntimeError.from_errno("close")
    end
  end
end