lua timer. based on luajit ffi load signal

timer.lua

--Lua timer library based on C signal.
--Notice: signal need Posfix system support

local ffi = require "ffi"

ffi.cdef[[
typedef void (*sighandler_t) (int32_t);
extern sighandler_t signal (int32_t signum, sighandler_t handler);
unsigned int alarm(unsigned int seconds);
]]

local SIG_ERR = -1
local SIGALRM = 14
local SIG_CANCEL = 0

local Timer = {}

function Timer.new(self,expire,callback, ...)
	self.__index = self
	self.expire = expire
	self.callback = callback
	self.args = {...}
	return setmetatable({},self)
end

function Timer.start(self)
	local trigger = function() self:call() end
	local handler = ffi.C.signal(SIGALRM,trigger)
	ffi.C.alarm(self.expire)
end

function Timer.cancel(self)
	-- self.callback = nil
    ffi.C.alarm(SIG_CANCEL)
end

function Timer.call(self)
	if self.callback then
		local ok = pcall(self.callback,unpack(self.args))
		if not ok then
			error("fail execute timer callback.")
		end
	end
end

function Timer.timeout(self)
	return os.time() > self.expired
end

local function sleep(n)
    os.execute("sleep " .. tonumber(n))  
end

local callback = function(s) print(s) end

local timer = Timer:new(1,callback,"abc")
timer:start()

sleep(3)