First, you need to modify your blocking function by wrapping the blocking part(sleep, i/o, etc) in async.AsyncRun. And the return values of the async.AsyncRun will be the return values of the await.


func Sleep(L *lua.LState) int {
    sec := L.CheckInt(1)
    caller := L.CheckString(2)

    async.AsyncRun(func() []lua.LValue {
        time.Sleep(time.Second * time.Duration(sec))
        return []lua.LValue{lua.LString(caller)}
    }, L)

    return 0
}

And you can use it in your function. Use async to start a coroutine and use await to wait some blocking result in an async function.

function main(str)
    -- A
    async(function()
        for i=3, 1, -1 do
            result = await(sleep, 1, "a")
            print("it's "..result)
        end
    end)

    -- B
    async(function()
        for i=3, 1, -1 do
            result = await(sleep, 2, "b")
            print("it's "..result)
        end
    end)
    
    -- C
    async(function()
        for i=3, 1, -1 do
            result = await(sleep, 3, "c")
            print("it's "..result)
        end
    end)

    return str
end

Finally, you can call main function, and you also need to wrap your function in async.WrapAsyncFunc.


L.CallByParam(lua.P{
    Fn:      async.WrapAsyncFunc(L, L.GetGlobal("main").(*lua.LFunction)),
    NRet:    1,
    Protect: true,
}, lua.LString("hello"))

for i := 1; i <= L.GetTop(); i++ {
    log.Println(L.Get(i).String())
}