prosody/net/cqueues.lua

-- 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";

-- 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;
	server.base:addevent(cq:pollfd(), EV_READ, function(e)
			assert(cq:loop(0));
			-- Convert a cq timeout to an acceptable timeout for luaevent
			local t = cq:timeout();
			if t == 0 then -- if you give luaevent 0, it won't call this callback again
				t = 0.000001; -- 1 microsecond is the smallest that works (goes into a `struct timeval`)
			elseif t == nil then -- you always need to give a timeout, pick something big if we don't have one
				t = 0x7FFFFFFF; -- largest 32bit int
			end
			return EV_READ, t;
		end,
		-- Schedule the callback to fire on first tick to ensure any cq:wrap calls that happen during start-up are serviced.
		0.000001);
else
	error "NYI"
end

return {
	cq = cq;
}