-- Prosody IM

-- Copyright (C) 2014 Daurnimator

--

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

-- This module allows you to use cqueues with a net.server mainloop

--

local server = require "net.server";

local cqueues = require "cqueues";

assert(cqueues.VERSION >= 20150113, "cqueues newer than 20150113 required")

-- Create a single top level cqueue

local cq;

if server.cq then -- server provides cqueues object

	cq = server.cq;

elseif server.get_backend() == "select" and server._addtimer then -- server_select

	cq = cqueues.new();

	local function step()

		assert(cq:loop(0));

	end

	-- Use wrapclient (as wrapconnection isn't exported) to get server_select to watch cq fd

	local handler = server.wrapclient({

		getfd = function() return cq:pollfd(); end;

		settimeout = function() end; -- Method just needs to exist

		close = function() end; -- Need close method for 'closeall'

	}, nil, nil, {});

	-- Only need to listen for readable; cqueues handles everything under the hood

	-- readbuffer is called when `select` notes an fd as readable

	handler.readbuffer = step;

	-- Use server_select low lever timer facility,

	-- this callback gets called *every* time there is a timeout in the main loop

	server._addtimer(function(current_time)

		-- This may end up in extra step()'s, but cqueues handles it for us.

		step();

		return cq:timeout();

	end);

elseif server.event and server.base then -- server_event

	cq = cqueues.new();

	-- Only need to listen for readable; cqueues handles everything under the hood

	local EV_READ = server.event.EV_READ;

	-- Convert a cqueues timeout to an acceptable timeout for luaevent

	local function luaevent_safe_timeout(cq)

		local t = cq:timeout();

		-- if you give luaevent 0 or nil, it re-uses the previous timeout.

		if t == 0 then

			t = 0.000001; -- 1 microsecond is the smallest that works (goes into a `struct timeval`)

		elseif t == nil then -- pick something big if we don't have one

			t = 0x7FFFFFFF; -- largest 32bit int

		end

		return t

	end

	local event_handle;

	event_handle = server.base:addevent(cq:pollfd(), EV_READ, function(e)

			-- Need to reference event_handle or this callback will get collected

			-- This creates a circular reference that can only be broken if event_handle is manually :close()'d

			local _ = event_handle;

			-- Run as many cqueues things as possible (with a timeout of 0)

			-- If an error is thrown, it will break the libevent loop; but prosody resumes after logging a top level error

			assert(cq:loop(0));

			return EV_READ, luaevent_safe_timeout(cq);

		end, luaevent_safe_timeout(cq));

else

	error "NYI"

end

return {

	cq = cq;

}