# -*- encoding: binary -*-
# Copyright (C) 2013, Eric Wong <normalperson@yhbt.net> and all contributors
# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
class Yahns::Queue < SleepyPenguin::Epoll::IO # :nodoc:
  include SleepyPenguin
  attr_accessor :fdmap # Yahns::Fdmap

  # public
  QEV_QUIT = Epoll::OUT # Level Trigger for QueueQuitter
  QEV_RD = Epoll::IN | Epoll::ONESHOT
  QEV_WR = Epoll::OUT | Epoll::ONESHOT
  QEV_RDWR = QEV_RD | QEV_WR

  def self.new
    super(SleepyPenguin::Epoll::CLOEXEC)
  end

  # for HTTP and HTTPS servers, we rely on the io writing to us, first
  # flags: QEV_RD/QEV_WR (usually QEV_RD)
  def queue_add(io, flags)
    @fdmap.add(io)
    epoll_ctl(Epoll::CTL_ADD, io, flags)
  end

  def thr_init
    Thread.current[:yahns_rbuf] = ""
    Thread.current[:yahns_fdmap] = @fdmap
  end

  # use only before hijacking, once hijacked, io may be unusable to us
  def queue_del(io)
    @fdmap.forget(io)
    epoll_ctl(Epoll::CTL_DEL, io, 0)
  end

  # returns an array of infinitely running threads
  def worker_thread(logger, max_events)
    Thread.new do
      thr_init
      begin
        epoll_wait(max_events) do |_, io| # don't care for flags for now
          case rv = io.yahns_step
          when :wait_readable
            epoll_ctl(Epoll::CTL_MOD, io, QEV_RD)
          when :wait_writable
            epoll_ctl(Epoll::CTL_MOD, io, QEV_WR)
          when :wait_readwrite
            epoll_ctl(Epoll::CTL_MOD, io, QEV_RDWR)
          when :ignore # only used by rack.hijack
            # we cannot call Epoll::CTL_DEL after hijacking, the hijacker
            # may have already closed it  Likewise, io.fileno is not
            # expected to work, so we had to erase it from fdmap before hijack
          when nil, :close
            # this must be the ONLY place where we call IO#close on
            # things that got inside the queue
            @fdmap.sync_close(io)
          else
            raise "BUG: #{io.inspect}#yahns_step returned: #{rv.inspect}"
          end
        end
      rescue => e
        Yahns::Log.exception(logger, 'queue loop', e)
      end while true
    end
  end
end