1 local co_time_tbl = {}
 2 setmetatable(co_time_tbl, { __len = function(o)
 3     local count = 0
 4     for k, v in pairs(o) do
 5         count = count + 1
 6     end
 7     return count
 8 end
 9 })
10 
11 local function isWindows()
12     return package.config:sub(1, 1) == "\\"
13 end
14 
15 local function sleep(n)
16     if isWindows() then
17         if n > 0 then
18             os.execute("ping -n " .. tonumber(n + 1) .. " localhost > NUL")
19         end
20     else
21         os.execute("sleep " .. tonumber(n))
22     end
23 end
24 
25 local function Update(deltaTime)
26     -- main loop
27 end
28 
29 local function updateCoroutine()
30     local iTime = os.time()
31     for kco, vTime in pairs(co_time_tbl) do
32         if iTime >= vTime then
33             if coroutine.status(kco) == "suspended" or coroutine.status(kco) == "normal" then
34                 coroutine.resume(kco)
35             elseif coroutine.status(kco) == "dead" then
36                 co_time_tbl[kco] = nil
37             end
38         end
39     end
40 end
41 
42 function coroutine.waitforSeconds(second)
43     assert(type(second) == "number" or second <= 0)
44     local iEndTime = os.time() + second
45     local co = coroutine.running()
46     if co then
47         co_time_tbl[co] = iEndTime
48         return coroutine.yield()
49     end
50 end
51 
52 local function main()
53     local co1 = coroutine.wrap(function()
54         coroutine.waitforSeconds(5)
55         print("after 5 seconds")
56     end)
57     local co2 = coroutine.wrap(function()
58         coroutine.waitforSeconds(4)
59         print("after 4 seconds")
60     end)
61     local co3 = coroutine.wrap(function()
62         coroutine.waitforSeconds(3)
63         print("after 3 seconds")
64     end)
65     local count = 0
66     local co4 = coroutine.wrap(function()
67         while (true) do
68             coroutine.waitforSeconds(1)
69             count = count + 1
70             print("coroutine num: " .. #co_time_tbl .. " | second count:" .. count)
71         end
72     end)
73     co1()
74     co2()
75     co3()
76     co4()
77     while true do
78         sleep(0.033)
79         Update()
80         updateCoroutine()
81     end
82 end
83 
84 main()